Archive for the ‘FAQ’ Category

What is Thermal Conductivity of Ceramic Materials?

Thursday, October 10th, 2024

What is Thermal Conductivity?

Thermal conductivity refers to a material’s ability to conduct heat. It’s a physical property that indicates how easily heat can pass through a substance when there is a temperature difference. In scientific terms, thermal conductivity is measured in watts per meter-kelvin (W/m·K), describing how much heat (in watts) is transferred through a material for every meter of thickness when there’s a one-degree temperature difference across it.

For ceramic materials, thermal conductivity plays a pivotal role in determining their usability in various industrial and electronic applications. Materials with high thermal conductivity can transfer heat quickly, so it is important in situations where heat must be dissipated rapidly to avoid damage to components, like in electronics or aerospace industries. On the other hand, materials with low thermal conductivity are used for thermal insulation, preventing unwanted heat transfer in applications like kiln linings or fireproofing.

Do Ceramic Materials Have High Thermal Conductivity?

Ceramic materials are generally known for their thermal insulation properties, meaning they typically have low thermal conductivity. However, not all ceramics are insulators. There are a few exceptions with significantly higher thermal conductivity, making them valuable for heat-dissipating applications.

Traditional ceramics such as alumina and zirconia are typically poor conductors of heat due to their atomic structure, which restricts the movement of heat. However, advanced ceramics like aluminum nitride (AlN) and silicon carbide (SiC) exhibit impressive levels of thermal conductivity. These materials are increasingly being used in industries like electronics, aerospace, and automotive manufacturing, where managing heat efficiently is critical to the performance and safety of equipment.

High thermal conductivity ceramics, though less common, have opened new avenues for using ceramic materials in areas where heat transfer was traditionally a limiting factor. So, while most ceramics are not known for high thermal conductivity, advancements in ceramic technology have led to the development of high-performance materials that challenge this generalization.

Why is Thermal Conductivity Important for Ceramic Materials?

Thermal conductivity in ceramics is a key factor that dictates where and how these materials can be used. There are several reasons why thermal conductivity matters for ceramic materials:

Heat Management in Electronics

In electronics, high thermal conductivity ceramics are crucial to ensure that components do not overheat during operation. Many electronic devices produce heat as a byproduct, and if this heat is not managed properly, it can lead to equipment failures. Ceramic materials like AlN and BeO are widely used in applications such as LED packaging, power electronics, and semiconductor manufacturing due to their ability to transfer heat away from sensitive components quickly and efficiently.

Thermal Insulation

On the flip side, some ceramic materials with low thermal conductivity are perfect for insulation. In industries like metallurgy or construction, materials like silicon oxide or zirconia are used to keep heat in or out, making them excellent choices for furnace linings, kilns, and thermal barrier coatings.

Thermal Shock Resistance

Many ceramics with low thermal conductivity also possess high thermal shock resistance, meaning they can withstand rapid temperature changes without cracking or breaking. This is important in applications such as aerospace, where materials are often exposed to extreme temperature variations.

Energy Efficiency

Thermal conductivity affects the energy efficiency of systems. In applications like heating elements, components with good thermal conductivity allow heat to be transferred more effectively, leading to better energy efficiency and lower operational costs. Ceramics that balance both thermal insulation and conductivity provide optimized energy management, crucial for industrial processes.

5 Typical High Thermal Conductivity Ceramic Materials

Aluminum Nitride (AlN)

Thermal Conductivity: ~170-230 W/m·K

Aluminum nitride is one of the most well-known ceramics for high thermal conductivity. It is electrically insulating, which makes it an ideal material for electronic substrates and heat sinks in devices like LEDs and power modules. Its ability to rapidly dissipate heat while maintaining electrical isolation makes it a popular choice in electronics where heat management is critical.

Silicon Carbide (SiC)

Thermal Conductivity: ~120-270 W/m·K

Silicon carbide is not only known for its excellent thermal conductivity but also its incredible hardness and mechanical strength. It is used in high-temperature applications, such as in gas turbines and heat exchangers. Its ability to withstand harsh conditions while transferring heat efficiently makes it invaluable in aerospace and automotive industries.

Beryllium Oxide (BeO)

Thermal Conductivity: ~200-330 W/m·K

Beryllium oxide offers one of the highest thermal conductivities among ceramics, rivaling some metals. Its superior ability to conduct heat while remaining electrically insulating makes it ideal for high-performance electronic devices. However, its use is limited due to the toxic nature of beryllium, requiring careful handling during manufacturing.

Alumina (Al2O3)

Thermal Conductivity: ~20-35 W/m·K

Alumina is a widely used ceramic due to its good combination of thermal conductivity, mechanical strength, and electrical insulation. Though not as high in thermal conductivity as AlN or SiC, alumina’s affordability and versatility make it a common choice in many industrial applications, including substrates for electronics and thermal barriers.

Silicon Nitride (Si3N4)

Thermal Conductivity: ~20-30 W/m·K

Silicon nitride is a material prized for its thermal shock resistance and mechanical strength. Though it does not have the highest thermal conductivity, its ability to withstand extreme temperatures and thermal cycling makes it valuable in engines and high-performance bearings.

What Ceramic Materials Are Best for Thermal Conductivity?

Aluminum nitride is one of the most suitable ceramic materials for conducting heat. ‌ aluminum nitride (AlN) has a thermal conductivity of 170-230 W/mK, is one of the best thermal conductivity ceramic substrate materials, especially suitable for high power density and high-frequency electronic devices heat. Aluminum nitride is suitable for heat conduction, mainly for the following reasons:

1. High thermal conductivity: aluminum nitride has extremely high thermal conductivity and can effectively transfer heat from one area to another.

‌2. Excellent mechanical properties: aluminum nitride not only has good thermal conductivity, but also has high mechanical strength and chemical stability, can maintain the stability of its structure and properties in a variety of environments.

‌3. Wide application: aluminum nitride is widely used in the heat dissipation of high power density electronic devices and high-frequency electronic devices to meet the needs of modern electronic equipment for efficient heat dissipation.

What are the Thermal Properties of Ceramic Materials?

The thermal properties of ceramic materials mainly include melting point, heat capacity, thermal expansion and thermal conductivity. ‌ The melting point of ceramic materials is generally higher than that of metals, up to 3000℃ or more, and has excellent chemical stability at high temperatures‌.

The heat capacity of ceramic materials refers to the heat required to increase the temperature of ceramic materials by 1℃ per unit mass. Ceramic has a lower heat capacity, which means that it is less able to absorb heat when heated‌.

The coefficient of thermal expansion of ceramic materials is small, much lower than that of metal. This means that when the temperature changes, the size of the ceramic changes less and has good dimensional stability.

The thermal conductivity of ceramic materials is lower than that of metal materials, but its thermal conductivity depends on the specific type of ceramic. Some ceramics are good thermal insulation materials, while some ceramics are good thermal conductivity materials, such as boron nitride and silicon carbide ceramics.

Your Most Reliable Ceramic PCB Manufacturer – Best Technology

When it comes to finding a reliable manufacturer for ceramic PCBs, Best Technology stands out in the market. As a leader of ceramic material and ceramic PCB manufacturer, Best Technology has over 18 years experience, we are so confident that we can provide the highest quality and high specification PCB for you! Backing up with a group of professional engineers, and well established quality system. Best Technology has grown to become a major PCB manufacturer in Asia to serve in diverse customers base. At Best Technology, you can enjoy a full turn-key service from IC substrate design, prototyping, mass production and ceramic PCB assembly.

Whether you need ceramic materials with high thermal conductivity for your electronics, or specialized products for unique applications, we have the expertise and the technology to deliver. Trust Best Technology to provide you with the best in ceramic PCB manufacturing, ensuring that your projects are completed to the highest standards.

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Aluminum Nitride PCB | Aluminum Nitride Ceramic PCB Design

Thursday, October 10th, 2024

What is Aluminum Nitride PCB?

Aluminum nitride PCB also known as Aluminum nitride ceramic PCB or short for AlN PCB. It is a high-performance circuit board made from aluminum nitride ceramic, a material known for its exceptional thermal conductivity and electrical insulation properties. These boards are commonly used in industries where efficient heat dissipation is crucial, such as in power electronics, LED applications, and high-frequency devices. AlN PCBs are gaining popularity due to their ability to withstand extreme temperatures.

Aluminum Nitride PCB | Aluminum Nitride Ceramic PCB

Benefits of AlN PCBs

One of the key advantages of AlN PCBs is their excellent thermal conductivity, which helps prevent overheating in electronic components. With exceptional thermal conductivity of 170 W/mK, strong dielectric strength, and a low thermal expansion coefficient (CTE <4 ppm/°C), AlN is widely used in applications like high-power LEDs, lasers, high-current switches, and even ultra-low temperature vacuum electronics such as those in quantum computing. In addition to these features, AlN offers the same benefits as other ceramic materials, including rigidity, environmental and chemical resistance, and 0% water absorption.

Key reasons for choosing Aluminum Nitride over other PCB materials include:

Outstanding thermal conductivity of 170 W/mK

Excellent dielectric properties

High operating temperatures exceeding 350°C

Low thermal expansion coefficient (<4 ppm/°C)

Compact designs due to better integration

Hermetically sealed packages with 0% water absorption

Minimal to no outgassing

What is the Thermal Conductivity of Aluminum Nitride PCB?

‌The thermal conductivity of aluminum nitride PCB ranges from 170-230W/(m·K).

The high thermal conductivity of aluminum nitride PCB is due to its unique structure and chemical composition. The thermal conductivity of aluminum nitride ceramic substrate is 2-3 times higher than that of traditional alumina ceramics and silicon-based ceramics, and 10-20 times higher than that of titanium substrate. This high thermal conductivity allows them to effectively dissipate heat from high-power electronic components, preventing overheating and ensuring stable performance. The ability to manage heat efficiently makes AlN PCBs an ideal choice for applications that generate a significant amount of heat, such as power modules, LEDs, and RF components. In comparison to other materials like aluminum oxide, which has lower thermal conductivity (around 20-30 W/mK), aluminum nitride stands out as a top choice for heat-sensitive applications.

Factors affect thermal conductivity of AlN PCB

Although the theoretical thermal conductivity of AlN is extremely high, its performance in practical applications is limited by a number of factors, mainly including:

Microstructure

Phonon scattering is a key mechanism for heat conduction. Grain boundaries, interfaces, second phases, and defects can all affect the mean free path of phonons, thereby influencing thermal conductivity. High-purity, low-defect single-crystal AlN has a longer phonon mean free path and higher thermal conductivity.

Oxygen Impurity Content

AlN’s strong affinity with oxygen leads to the easy introduction of oxygen impurities, which form alumina films and lattice defects, such as aluminum vacancies. These significantly reduce the phonon mean free path, lowering thermal conductivity. When the oxygen concentration is below 0.75%, oxygen atoms primarily replace nitrogen atoms in the lattice; however, exceeding this concentration causes aluminum vacancies to disappear and results in the formation of extended defects, further affecting thermal conductivity.

Sintering Process and Additives

By selecting appropriate sintering additives (such as Y₂O₃-Li₂O, Y₂O₃-CaC₂ composite systems), densification can be achieved at lower temperatures, while reducing the formation of oxygen impurities and second phases, effectively improving the thermal conductivity of AlN ceramics. These additives help purify grain boundaries and optimize the microstructure, facilitating more efficient phonon transmission.

What is Aluminum Nitride PCB Used For?

Aluminum nitride as a stable hexagonal wurtzite covalent bond compound, has shown extensive application potential in the field of electronics and optoelectronics due to its unique physical and chemical properties. Its crystal structure takes AlN4 tetrahedron as the basic unit, space group P63mc, belongs to the hexagonal crystal system, which gives AlN a series of excellent properties and use in advanced applications.

Some common applications include:

Optical Communication

Integrated Circuits and High-Power Electronic Devices

Power Electronics

Wafer chips

Epoxy Resin Packaging

Optical Devices and Piezoelectric Devices

Industrial Materials

Acoustic Devices

Aerospace

Military

Why is Aluminum Nitride Expensive?

The high cost of aluminum nitride PCBs stems from several factors.

First of all, the raw material cost of aluminum nitride PCB is higher. The preparation of aluminum nitride powder requires high purity raw materials, synthesis methods include direct nitriding method, carbothermal reduction method, self-propagating high temperature synthesis and chemical vapor deposition method, etc. These methods have high requirements on equipment and technology, resulting in higher costs.

Secondly, the production process is complicated. The preparation process of aluminum nitride PCB is complex, including multiple steps such as molding and sintering, which has high requirements for equipment and technology and a high production threshold.

Finally, the market demand is large. Aluminum nitride PCB in power electronics, communication equipment, automotive electronics and other fields have a wide range of applications, especially in high power, high frequency and other occasions, its excellent heat dissipation and insulation performance can not be replaced, resulting in short supply in the market, the price of natural rising.

Aluminum Nitride PCB vs. Alumina Oxide PCB

Both aluminum nitride (AlN) and alumina oxide (Al2O3) are ceramic materials used in PCB manufacturing, but they differ significantly in terms of performance. AlN offers superior thermal conductivity, typically 170-230 W/mK, compared to aluminum oxide’s lower range of 20-30 W/mK. This makes AlN the better option for applications requiring efficient heat dissipation, such as high-power electronics and LED lighting.

However, aluminum oxide is more cost-effective and is often used in applications where high thermal conductivity is not as crucial. While Al2O3 provides good electrical insulation and is easier to produce, it may not perform as well in heat-sensitive environments as AlN. Therefore, the choice between AlN and Al2O3 depends on the specific thermal and budgetary requirements of the application. Here are the parameters of AlN and Al2O3 materials:

Parameter	Aluminum Nitride (AlN)	Alumina Oxide (Al2O3)
Thermal conductivity	170-230 W/m.k	24-30 W/m.k
Dielectric constant	8.8	9.2-10
Dielectric strength	15-25kV/mm	10-15kV/mm
Temperature resistance	1000-1500C	1000-1200C
CTE	4.0 ppm/K	6.5-7 ppm/K
Flexural strength	450MPa	320MPa
Dielectric breakdown voltage	14 V/m	10 V/m

AlN Ceramic PCB Design Considerations

When designing an aluminum nitride PCB, several factors need to be considered to optimize performance:

1. Trace Width

The trace width on AlN PCBs should be a minimum of 10 mils. This ensures that the conductor cross-section is sufficient to handle the current and heat dissipation needs. Given the thermal advantages of AlN, wider traces help in spreading heat more efficiently, minimizing the risk of overheating in power-dense applications.

2. Trace Clearance

Clearances between adjacent traces should be at least 8 to 10 mils. AlN PCBs often work with higher voltage levels, making spacing critical to prevent arcing or dielectric breakdown. In high-power designs, careful spacing between traces reduces the likelihood of signal interference and maintains the board’s insulation integrity.

3. Via Pads

For via pads, a minimum diameter of 16 mils is recommended. This provides sufficient area for stable soldering and ensures proper electrical connection through the via. Depending on the board’s application, larger via pads may be necessary to accommodate higher currents or thermal dissipation needs. Via sizing should also account for assembly techniques, such as reflow soldering or thermal management features, like thermal vias, which enhance heat transfer away from components.

4. Pad Geometry Adjustments

Unlike FR-4 designs, AlN PCBs often require specific adjustments in pad geometries. The mechanical and thermal properties of AlN are quite different from those of traditional PCBs. The expansion rate, hardness, and substrate fragility mean that pad designs should allow for thermal expansion and contraction without causing stress fractures. Proper pad design also ensures better solder joint reliability, particularly for components exposed to continuous thermal cycling.

5. Gold Plating for Wire Bonding Pads

In high-performance applications, wire bonding is often used, and gold plating is a preferred surface finish for wire bonding pads. The use of gold provides a stable, corrosion-resistant surface that improves bond integrity and longevity. Wire bonding is especially critical in high-frequency, high-reliability devices, where the connections must maintain integrity under thermal stress or in harsh environments.

6. Component and Solder Matching

All components and solder materials must match the electrical and mechanical properties of the AlN substrate. Mismatches in thermal expansion between the PCB material and components can lead to stress, causing cracking or delamination. It’s important to select components and solder that can withstand high temperatures and thermal cycles while maintaining compatibility with AlN’s characteristics, especially in applications like power electronics and RF circuits.

7. Hermetic Sealing and Height Restrictions

For applications requiring hermetic sealing, such as aerospace or medical devices, height restrictions may apply to the components on the PCB. Hermetic seals protect against moisture and environmental contaminants, ensuring long-term reliability in sensitive applications. The overall component height should be kept in line with the sealing requirements, and compact designs are often necessary to meet stringent packaging constraints.

8. Thermal Expansion Management

When attaching large dies or high-power devices, it’s crucial to model and account for thermal expansion. Even though AlN has a low thermal expansion coefficient (<4 ppm/°C), the difference in expansion rates between components and the substrate can create mechanical stress, especially during thermal cycling. Careful design, including flexible connections or underfill materials, can help mitigate these effects.

9. Thermal Vias

Thermal vias are essential for managing heat in high-power applications. By placing thermal vias directly underneath hot components, heat can be efficiently transferred away from sensitive areas, extending the lifespan of both the components and the PCB itself. In many designs, a network of thermal vias is integrated with heat sinks or spreaders to further improve heat dissipation.

10. Surface Finishes and Coatings

Aluminum nitride PCBs can benefit from surface finishes such as electroless nickel immersion gold (ENIG) or immersion silver, which protect the copper traces from oxidation and provide excellent solderability. The choice of surface finish may also depend on the specific application environment and the reliability requirements, especially in high-power or high-frequency circuits.

FAQs About AlN PCBs

1. How durable are aluminum nitride PCBs?

AlN PCBs are highly durable and can withstand extreme temperatures and harsh environments.

2. Can AlN PCBs be used in high-frequency applications?

Yes, aluminum nitride PCBs are well-suited for high-frequency and high-speed applications due to their excellent electrical insulation and low signal loss.

3. Are aluminum nitride PCBs environmentally friendly?

While the production process can be resource-intensive, AlN PCBs offer longer lifespans and higher efficiency, which can reduce the environmental impact over time.

4. How do AlN PCBs compare with metal-core PCBs?

Metal-core PCBs, such as those with an aluminum core, provide good thermal management but lack the superior electrical insulation of AlN PCBs. AlN PCBs are preferred for applications requiring both high thermal conductivity and insulation.

5. What industries typically use aluminum nitride PCBs?

Industries like power electronics, aerospace, automotive, and telecommunications commonly use AlN PCBs for their high-performance needs.

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2 Layer Aluminum PCB | Metal Core PCB Manufacturer

Wednesday, October 9th, 2024

What is a 2 Layer Aluminum PCB?

A 2-layer aluminum PCB is a type of metal core circuit board that contains two conductive layers, usually copper, with an aluminum core or base material. Aluminum PCBs are used for their excellent heat dissipation properties, and always used in high-power applications like LED lighting, power supplies, and automotive systems. The aluminum base offers better thermal management than standard FR4 PCBs. In a 2-layer aluminum PCB, the two conductive copper layers allow more complex routing for electrical signals compared to single-layer boards.

2 Layer Aluminum PCB | Metal Core PCB Manufacturer

2 Layer Aluminum PCB Stack-Up

The stack-up of a 2-layer aluminum PCB consists of the following:

Top Copper Layer: This is where the signal traces and components are located. It can vary in thickness, depending on current-carrying requirements.

Dielectric Layer: A layer of insulation that separates the top copper layer from the aluminum core. It plays a key role in electrical isolation and heat transfer.

Aluminum Base: This core provides structural support and excellent heat dissipation properties. It also serves as the grounding plane in some designs.

Bottom Copper Layer: The second conductive layer allows for more advanced routing.

How Thick is a 2 Layer PCB Layer?

The thickness of a 2-layer aluminum PCB can vary depending on the specific design requirements, but typically, the copper layer is about 1 to 2 ounces (35 to 70 microns) thick. The aluminum base itself is thicker, usually between 1.0 mm and 3.0 mm, depending on the board’s required rigidity and heat dissipation needs. The overall board thickness generally ranges between 1.2 mm and 3.2 mm.

A thicker aluminum core improves heat transfer, but the board’s thickness must also align with the product’s mechanical and electrical requirements. Designers often have to balance between sufficient thermal performance and the overall board size for practical applications.

Is Thicker Aluminum PCB have Better Heat Dissipation?

Generally speaking, the thinner the thickness of the aluminum PCB, the faster the heat conduction speed. The thicker the thickness of the aluminum PCB, the slower the heat conduction rate. The thermal conductivity of aluminum-based circuit board mainly depends on its material and structure. Although thickness affects the path length of heat conduction, the more critical factors are the thermal conductivity and structural design of the material. For example, high thermal conductivity materials such as copper, silver and other high thermal conductivity materials will significantly improve the thermal conductivity of aluminum substrate. In addition, the thickness and thermal conductivity of the insulation layer will also affect the overall thermal conductivity effect ‌.

Specifically, the thermal conductivity of the aluminum-based circuit board is also related to the thickness of its insulation layer. The thicker the insulation layer, although it can withstand higher voltage, it will also reduce the heat transfer efficiency. Therefore, choosing the appropriate insulation layer thickness and materials with high thermal conductivity is the key to ensuring efficient thermal conductivity of aluminum-based circuit boards ‌.

2 Layers Aluminum PCB vs. Double Sided Aluminum PCB

Though the terms “2 layers aluminum PCB” and “double-sided aluminum PCB” might sound similar, there are slight differences.

A 2-layer aluminum PCB contains two conductive copper layers. These layers can be arranged to handle signal routing and ground planes separately. In contrast, a double-sided aluminum PCB typically has one copper layer on either side of the aluminum core, offering less flexibility in routing. Here is the stack up of double sided aluminum PCB:

How Much Does Aluminum PCB Cost?

The cost of an aluminum PCB, including a 2-layer version, depends on several factors such as the board’s thickness, copper weight, design complexity, and production volume. On average, 2-layer aluminum PCBs cost more than single-sided aluminum PCBs because of the additional copper layer and routing complexity.

For small orders, prices might range between $5 and $15 per square foot. For larger production runs, costs can decrease significantly due to economies of scale. Factors like the thickness of the aluminum base and copper layer, as well as additional features like surface finishes, can also influence the price.

While aluminum PCBs are more expensive than standard FR4 boards, their enhanced thermal performance can reduce overall system costs by improving reliability and reducing the need for additional cooling measures.

How Many Layers Should a PCB Have?

The number of layers a PCB should have depends on the complexity of the design. For simple applications like LED lighting or power conversion, a 2-layer aluminum PCB is often sufficient. It provides more routing flexibility than a single-layer board while still offering effective heat dissipation.

For more complex designs requiring high-density interconnections or additional functionality, a multi-layer PCB with three or more layers might be necessary. However, multi-layer aluminum PCBs are rare because their primary function is thermal management, which is typically solved within one or two layers. The decision to use more layers depends on the specific application, power requirements, and signal integrity needed in the design.

Aluminum PCB Design Guidelines

When designing a 2-layer aluminum PCB, several factors must be considered to maximize performance:

Thermal Management: Since aluminum PCBs are chosen for their thermal properties, optimizing heat dissipation is critical. Components that generate significant heat should be placed near the aluminum core, allowing for faster heat transfer.

Copper Thickness: The copper thickness should match the current-carrying requirements of the design. Using thicker copper can help manage higher current loads, but it also increases the cost and weight of the PCB.

Dielectric Layer: The thickness and material of the dielectric layer play a crucial role in both thermal and electrical performance. A thinner dielectric layer improves heat dissipation but may limit electrical isolation. Choosing the right dielectric material is key for balancing performance and reliability.

Via Placement: For a 2-layer design, vias must be carefully placed to connect the two copper layers. Vias should be positioned to minimize electrical interference and maintain signal integrity.

Component Placement: Heat-sensitive components should be placed away from high-power components. This minimizes thermal stress on sensitive devices and ensures reliable operation over the PCB’s lifespan.

Aluminum PCBs may come with a higher price tag compared to traditional FR4 boards, but the long-term benefits in heat management, performance, and durability make them an excellent investment for demanding applications. Whether you’re working on power electronics, automotive circuits, or lighting solutions, a 2-layer aluminum PCB can provide the right balance between complexity and thermal efficiency.

If you’re in need of high-quality, custom aluminum PCBs, Best Technology specializes in delivering tailored solutions for your specific design needs. With 18+ years of experience in PCB manufacturing, we ensure top-notch performance, quality, and reliability for all your projects. Let us help you bring your ideas to life with the right aluminum PCB solution!

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What is the thermal conductivity coefficient of copper?

Wednesday, October 9th, 2024

What is the Thermal Conductivity Coefficient?

The thermal conductivity coefficient is a measure of how well a material conducts heat. It’s represented by the symbol k or λ, and it is measured in units of watts per meter-kelvin (W/m·K). It’s defined as the amount of heat that passes through a material 1 meter thick, with a temperature difference of 1 degree (K or °C) between its two sides, in one second, over an area of 1 square meter.

In general, the higher the thermal conductivity coefficient, the better the material is at transferring heat, so in some high power or power supply electronics, thermal conductivity value is important to transfer heat out. Materials with a high k value, like metals such as copper, allow heat to flow through them easily, which is why they are used in applications that require efficient heat dissipation. In contrast, materials with low thermal conductivity coefficients, such as insulators, are used to minimize heat transfer and preserve energy.

The thermal conductivity is only for the heat transfer form with thermal conductivity. When there are other forms of heat transfer, such as radiation, convection, mass transfer and other forms of heat transfer, the composite heat transfer relationship. The composite heat transfer relationship is often referred to as the apparent thermal conductivity, the dominant thermal conductivity, or the effective thermal transmissivity of material. In addition, the thermal conductivity is for homogeneous materials, in the actual situation, there are also porous, multi-layer, multi-structure, anisotropic materials, the thermal conductivity obtained by this material is actually a comprehensive thermal conductivity performance, also known as the average thermal conductivity.

According to Fourier’s law, the thermal conductivity is defined as

Where x is the direction of heat flow.

qx’’ is the heat flux in this direction in W/m2, and another is the temperature gradient in this direction, expressed in K/m.

For an isotropic material, the thermal conductivity is the same in all directions.

What Is the k Value of Copper?

The thermal conductivity of copper is about 401W/m.K. Copper is a transition element, pure copper is a soft metal, when it is cut on the surface, it is red-orange, and its ductility is good, thermal conductivity is relatively high, so it is a more commonly used material in cables and electronic components, can be used as building materials, and it is composed of many kinds of alloys.

What is the thermal conductivity coefficient of copper?

Copper’s high k value meaning it can quickly absorb and distribute heat. That is why copper is used extensively in heat sinks, electrical wiring, and cooling systems. Because of this, it’s highly valued in industries that rely on rapid heat dissipation. Whether in electronics or heavy machinery, the high thermal conductivity of copper ensures that heat does not build up, preventing overheating.

Thermal Conductivity of Common Solid Materials

Here are the thermal conductivity values of some common materials:

Aluminum: 237 W/m·K at 300°C

Copper: 401 W/m·K at 100°C

Iron: 61 W/m·K at 18°C

Steel: 45 W/m·K at 18°C (for carbon steel with 1% carbon)

Silver: 412 W/m·K at 100°C

Graphite: 151 W/m·K at 0°C

These values highlight the differences in heat conduction across materials, with metals like copper and silver being among the most efficient conductors of heat, while materials like steel and graphite have comparatively lower conductivity.

Is Copper a Good Conductor of Heat?

Yes, copper is an exceptionally good conductor of heat. For example, in electronics, copper is often used to cool down processors by transferring heat away quickly, thus ensuring systems run smoothly without overheating. In plumbing, copper pipes help distribute hot water faster, enhancing energy efficiency. From cookware to cooling systems, copper’s outstanding ability to conduct heat makes it indispensable across many fields.

Copper vs. Aluminum PCB: Which is Better?

Both copper and aluminum are excellent conductors of heat in circuit boards manufacturing, but how do they compare? Let’s discuss them from below aspects:

1. Thermal conductivity

First, let’s take a look at the thermal conductivity of aluminum and copper, which is a key indicator of the material’s heat dissipation performance. The higher the thermal conductivity, the better the material’s ability to transfer heat.

Copper: 401W/m.k

Aluminum: 237W/m.k

It can be seen from the data that the thermal conductivity of copper is almost twice that of aluminum, which means that under the same conditions, copper can transfer heat more efficiently. For this reason, copper is often the material of choice in applications that require extremely high thermal performance.

2. Density

Aluminum: Density of about 2.7 g/cm³.

Copper: Density of about 8.96 g/cm³.

Copper is nearly three times as dense as aluminum, which makes copper much heavier than aluminum. In some weight-sensitive applications, such as portable electronic devices, heavy cooling components may affect the portability and user experience of the product. Therefore, in these scenarios, although aluminum is not as conductive as copper, it is still a very popular choice due to its lower weight.

3. Cost

The prices of aluminum materials are low, and processing costs are relatively low. At the same time, aluminum is easy to process into a variety of shapes, which makes aluminum very cost-effective in the manufacturing process. However, the cost of copper is much higher and the manufacturing process is more complex, so the overall cost is much higher than aluminum.

4. Corrosion resistance

Aluminum and copper also have significant differences in corrosion resistance. Aluminum has good oxidation resistance, and the aluminum oxide layer formed on the surface can effectively protect the internal material from further corrosion. However, the corrosion resistance of copper is relatively poor, and it is easy to generate patina (carbonate of copper) in humid environments, which not only affects the appearance but also reduces the heat dissipation performance.

Why Does Copper Have the Highest Thermal and Electrical Conductivity?

Copper has very good conductivity because it has a large number of freely moving electrons in its interior. When a voltage is added to both ends of a metal, the positive electrode piles up positive charges, and the negative electrode piles up negative charges, because the same charges attract each other and the dissimilar charges repel each other, forcing the electrons to move in a directional way, thus forming a current. In addition, copper has a very low resistivity of only 1.68×10^-8Ω·m, second only to silver, and is the second most widely used conductive material.

Copper’s good thermal conductivity is also related to its internal free electrons. Metal nuclei have a weak ability to bind electrons, allowing free electrons to move freely within the metal and transfer heat rapidly. When one end of a metal is heated, the electrons of atoms or molecules at that end absorb energy and begin to vibrate. These vibrations are passed on to the electrons of neighboring atoms or molecules, forming a heat flow ‌4. Copper is metal-bonded in a way that makes it easier for its electrons to transfer energy inside the metal, and thus heat faster.

Here is the end of this blog sharing, if you have other questions about copper material, welcome to e-mail us: sales@bestpcbs.com.

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Why NRE fee is important for your PCB project?

Tuesday, October 8th, 2024

What Does NRE Stand For?

NRE, or Non-Recurring Engineering, refers to the upfront cost associated with developing and preparing the tools, processes, and engineering resources required for manufacturing a specific product. When it comes to PCB projects, NRE fees are vital because they cover the initial setup expenses that are incurred only once during the product development phase. These charges include design, tooling, programming, and testing requirements tailored to a particular PCB design, ensuring that the production is efficient and meets the required specifications.

Why Is It Necessary to Charge NRE Cost?

Charging an NRE cost is necessary because every PCB project is unique. The manufacturer must allocate resources to tailor the production to your specific design. The NRE fee ensures that all the necessary engineering work is done upfront to avoid delays or errors during mass production. If this fee weren’t charged, manufacturers would have to spread these costs across the entire production, making each unit more expensive, especially for small runs. This way, you can keep per-unit costs lower once production begins.

What Is the NRE Charge For?

The NRE charge is a crucial investment in ensuring that your PCB project gets off to the right start. It covers the engineering resources, setup, and processes that are required to customize the production environment specifically for your PCB design. Here are the main aspects that NRE fees typically cover:

Design Validation

Before manufacturing begins, the manufacturer must confirm that your PCB design is feasible and ready for production. This involves scrutinizing the layout for errors, verifying that it meets performance specifications, and ensuring compatibility with the chosen materials. This step can prevent expensive issues later in the process, such as defective boards or production delays.

Custom Tooling Setup

Every PCB design requires specific tools and fixtures to manufacture efficiently. NRE fees cover the creation or modification of tools that will allow your design to be assembled accurately. This might involve creating custom molds, dies, or specialized equipment that aligns with your PCB’s dimensions and complexity.

Programming and Firmware

For PCBs that require microcontrollers or other programmable components, the NRE charge often includes developing the necessary firmware or software to test and initialize these components. Manufacturers need to upload specific programs to ensure each unit functions correctly in real-world applications.

Prototype Creation

In some cases, the NRE fee also covers the cost of creating prototypes for testing. These prototypes are essential for verifying that the design works as intended before moving into full-scale production. The prototype phase allows for any last-minute adjustments and ensures that the final product will perform optimally.

How to Pay NRE Cost?

Paying the NRE cost is straightforward, but it’s important to clarify this with your manufacturer. Typically, the NRE fee is charged as a separate, one-time payment when you place your order. Depending on your arrangement with the manufacturer, it might be paid upfront or included in the first invoice along with the cost of your first production run. Payment terms can vary, but many manufacturers will expect it before starting the engineering and tooling processes. By paying this fee early, you ensure that your project can begin on time.

How to Reduce NRE Fee?

Reducing NRE costs may not always be possible, but there are ways to minimize them:

1. Reusing designs: If you’ve produced a similar PCB before, you can avoid some NRE costs by reusing or adapting the same designs.

2. Standardization: Using standard components and layouts rather than custom or unusual specifications can cut down on the design and tooling time.

3. Ordering in bulk: A larger production run can sometimes allow manufacturers to absorb some NRE costs, spreading the expense over a larger quantity of units.

4. Simplify design: A less complex design reduces the need for custom tools or special processes, leading to a lower NRE fee.

5. Choose experienced manufacturers: Partnering with a manufacturer like Best Technology who has experience in your industry can reduce the amount of custom setup needed, as they may already have processes and equipment suited to your project.

Considerations During the NRE Process

It’s important to approach the NRE process with a clear understanding of your project’s needs and goals. Communicate clearly with your manufacturer to avoid misunderstandings about what the NRE fee covers. For example, make sure you know if the fee includes changes or revisions to the design after the initial setup. You should also ask about the lead time for the engineering work. Knowing how long it will take to complete the NRE tasks helps you plan your project schedule more effectively.

Another consideration is the long-term benefits. While NRE fees may seem costly upfront, they are an investment that pays off as your project moves into full production. By ensuring that the initial design and setup are correct, you minimize the risk of costly production errors later.

When to Use Non-Recurring Engineering?

Non-Recurring Engineering is most beneficial when your PCB project involves custom designs or complex requirements. This is especially true when you need prototypes, new product development, or designs that require unique tools or processes. If you are producing a PCB that will have ongoing updates or revisions, it might also be necessary to pay an NRE fee each time the design changes. In general, the NRE fee is used whenever a manufacturer has to set up specialized processes or equipment that won’t be reused for other products.

How to Calculate NRE Cost?

NRE costs are calculated based on several factors. Manufacturers will consider the complexity of the design, the number of custom tools needed, and the extent of testing and programming required. The more custom features your PCB has, the higher the NRE cost is likely to be. Additionally, the cost of manpower to design and set up the project is included. Some manufacturers also calculate NRE based on the projected production run—larger runs may benefit from lower NRE fees as costs are spread over more units.

While it may seem daunting, NRE costs are ultimately a necessary investment for ensuring the success of your project. They allow manufacturers to deliver the best quality and avoid production errors, which can lead to greater savings in the long run.

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Aluminum PCB Circuit Board | Aluminum PCB Design & Prototype

Tuesday, October 8th, 2024

What is Aluminum PCB Circuit Board?

An aluminum PCB, also known as an aluminum circuit board, is a type of metal core printed circuit board that uses aluminum as its base material. Unlike traditional PCBs, which are typically made with fiberglass, aluminum PCBs offer superior heat dissipation. This makes them ideal for high-power applications where excess heat can damage sensitive components. Aluminum PCBs are widely used in industries such as LED lighting, automotive, and power equipment because they provide better thermal management.

Aluminum PCBs are made from a combination of the following materials:

Aluminum Substrate: The base layer, responsible for mechanical support and heat dissipation.
Dielectric Layer: This layer provides insulation between the conductive layer and the aluminum base, while also helping with thermal transfer.
Conductive Layer: Made of copper, this layer is etched to form the circuit pattern and provides electrical connectivity.
Solder Mask Layer: This is a protective layer to protect the traces.

Aluminum PCB Circuit Board | Aluminum PCB Design & Prototype

Types of Aluminum PCB

Aluminum circuit board is a kind of metal base copper clad plate with good heat dissipation function, the main types include single-sided aluminum PCB, double-sided aluminum PCB and multi-layer aluminum PCB. ‌

Single sided aluminum PCB

The single-sided aluminum substrate is composed of a conductive graphic layer and an insulating material plus aluminum plate, which is relatively simple in structure and suitable for the installation and connection of some basic electronic components.

Double sided aluminum PCB

The double-sided circuit aluminum substrate has two layers of conductive graphics layer and the insulating material plus aluminum plate superimposed together, providing a larger circuit layout space and better heat dissipation effect, which is often used in electronic devices requiring higher integration and better heat dissipation performance.

Multilayer aluminum PCB

Multi-layer printed aluminum-based circuit board consists of three or more layers of conductive graphic layer and insulating material and aluminum plate alternately laminated together, with complex circuit design and excellent heat dissipation performance, suitable for high-end applications such as LED lighting, automotive electronics ‌.

In addition, there are other special types of aluminum-based circuit boards, such as flexible aluminum substrates, mixed aluminum substrates, etc. Flexible aluminum substrate has excellent electrical insulation, flexibility and thermal conductivity, and is suitable for product design in various shapes and angles. The hybrid aluminum substrate is a multilayer component made of conventional FR-4 bonded to an aluminum substrate with a thermoelectric medium, designed to improve heat dissipation and rigidity, and used as a shield ‌.

Aluminum PCB Features

The aluminum substrate, a metal-based cooling plate (including aluminum, copper, and iron substrates), is made from a low-alloyed Al-Mg-Si series high-plastic alloy plate. This material offers excellent thermal conductivity, electrical insulation, and mechanical processing capabilities. When compared to traditional FR-4 materials, aluminum substrates of the same thickness and line width can carry higher currents. Additionally, they can withstand voltages up to 4500V and have a thermal conductivity greater than 2.0, making aluminum substrates the preferred choice in the industry.

● Surface mount technology (SMT);

● Very effective treatment of thermal diffusion in circuit design;

● Reduce product operating temperature, improve product power density and reliability, extend product service life;

● Reduce product volume, reduce hardware and assembly costs;

● Replace fragile ceramic substrate for better mechanical durability.

Aluminum PCB vs. Copper PCB

Both aluminum and copper PCBs have their own advantages, but they cater to different applications:

1. Thermal Conductivity

In general, the higher the thermal conductivity, the more efficient the heat transfer, resulting in better heat dissipation and a longer lifespan. Among metal substrates, copper substrates offer the best thermal conductivity, outperforming aluminum substrates.

2. Electrical Conductivity

Both aluminum and copper are metals and conduct electricity, though their exact levels of conductivity differ. In terms of electrical conductivity, copper is significantly superior to aluminum. In applications that require high electrical conductivity, copper is the ideal choice.

3. Resistance

Resistance is crucial in PCB design as it affects the overall functionality and stability of the components. Given that copper has a higher density than aluminum, its resistance is generally lower. Therefore, in applications requiring thinner circuits and faster power transmission, copper is the better option.

4. Weight

Due to copper’s higher density per unit area, copper PCBs are much heavier than aluminum PCBs with the same design.

In applications where lightweight structures are critical, aluminum is the preferred material. On the other hand, applications where weight is not a major concern often favor the use of copper.

5. Applications

Aluminum substrates are somewhat specialized. They are mainly used in energy-saving lighting products such as indoor lighting, energy-efficient lighting, and street lights. Copper substrates are suitable for high-power lighting equipment like car headlights, tail lights, and some high-tech electronics.

6. Manufacturing Process

The manufacturing process for aluminum-based PCBs is simpler than that for copper-based PCBs, which also impacts their production time and delivery schedules. Below is aluminum PCB and copper core PCB that made by Best Technology:

Aluminum PCB Manufacturing Process

The manufacturing process for aluminum PCBs involves several steps to ensure high quality and performance. Here is a basic manufacturing process of aluminum PCB:

1. Substrate Selection and Preprocessing

Aluminum alloys with high thermal conductivity, such as the 5052 and 6061 series, are selected as the base material. The aluminum sheet is first cut and cleaned to remove surface grease and impurities, ensuring proper adhesion for subsequent processes.

2. Chemical Etching of Patterns

Photosensitive ink is used to form the desired circuit patterns on the aluminum surface. After exposure and development, the ink-covered areas protect the underlying aluminum from being etched by chemicals, while the unprotected areas are etched away, forming the circuit pattern.

3. Insulation Layer Deposition

To achieve electrical isolation, an insulating material, usually thermosetting resin or ceramic-filled epoxy resin, is deposited on the aluminum substrate. This step is typically completed using screen printing or inkjet printing technology to ensure a uniform and appropriately thick insulation layer.

4. Metallization

Creating conductive paths on the insulation layer is a key step. Copper foil is deposited onto the insulation layer using methods such as electroplating, sputtering, or chemical copper deposition. This copper foil serves as the conductive layer for connecting LED chips and other components.

5. Drilling and Metallization

Holes are drilled in the board according to the design to achieve electrical connections between different layers. The hole walls are then metallized to ensure good conductivity inside the holes.

6. Surface Treatment

To improve solderability and corrosion resistance, the aluminum substrate undergoes additional surface treatments, such as tin spraying, gold plating, or silver plating.

7. Assembly and Testing

LED chips, resistors, capacitors, and other components are soldered onto the circuit board to complete the assembly. Here you can see the whole manufacturing process of aluminum metal core PCB.

What Affects Aluminum PCB Circuit Board Price?

First of all, ‌ raw material cost ‌ is one of the important factors affecting the price of aluminum based circuit board. The raw materials of aluminum substrate include aluminum substrate and other auxiliary materials, such as insulating layer materials. The price fluctuation of aluminum substrate will directly affect the production cost of aluminum substrate, and then affect its market price. In addition, the cost of electricity is also a part of the production process cannot be ignored, the fluctuation of electricity price will further affect the production cost ‌.

Secondly, ‌ market supply and demand ‌ is also a key factor in determining the price of aluminum-based circuit boards. If demand increases and supply is insufficient, prices will naturally go up. On the other hand, if there is an oversupply, the price will fall. Changes in demand in the construction, automotive and other industries, as well as changes on the supply side such as the construction of new plants or the closure of old plants, will have a direct impact on the price of aluminum-based circuit boards ‌.

‌The macroeconomic environment ‌ also has an important impact on the price of aluminum-based circuit boards. When economic growth is expected to be good, the demand for aluminum substrate in related industries increases, driving up prices; The expectation of economic recession will lead to a decline in demand and pressure on aluminum substrate prices ‌.

‌Policies and regulations ‌ is also one of the factors affecting the price of aluminum-based circuit boards. The government’s environmental protection policies, trade policies and industry subsidies will have an impact on the aluminum substrate market. For example, environmental policies that limit production may reduce supply and push up prices; The establishment of trade barriers may affect the import and export of aluminum substrate, and then affect the domestic market price.

Aluminum PCB Production Capability – Best Technology

Best Technology is known for its strong production capability when it comes to aluminum PCBs. Our manufacturing facilities are equipped with the latest technology to produce high-quality aluminum PCBs that meet industry standards. We have the ability to produce single-sided, double-sided, and multi-layer aluminum PCBs, below you can see our capability of aluminum PCBs:

Applications of Aluminum PCB

Aluminum PCBs are used in a variety of applications, particularly where heat management is crucial:

LED Lighting
Automotive Electronics
Power Supplies
Consumer Electronics
Medical
Household appliance

FAQs about Aluminum PCB Circuit Board

1. What is the main advantage of aluminum PCBs?

Aluminum PCBs excel in thermal management, making them perfect for heat-sensitive applications.

2. Are aluminum PCBs expensive?

No, aluminum PCBs are generally affordable, making them a cost-effective option for many industries.

3. Can aluminum PCBs be used in consumer electronics?

Yes, aluminum PCBs are commonly used in consumer electronics, especially in devices that generate significant heat.

4. What industries commonly use aluminum PCBs?

Industries such as automotive, LED lighting, and power supplies frequently use aluminum PCBs due to their thermal properties.

5. Is aluminum PCB better than copper PCB?

It depends on the application. Aluminum is better for heat dissipation, while copper excels in electrical conductivity.

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What is Blank PCB?

Monday, October 7th, 2024

What Is a Blank PCB Called?

A blank PCB is commonly referred to as a bare board. This term is used because the board has no components soldered onto it yet. It’s simply the foundation of a printed circuit board (PCB), typically made from a material like fiberglass and copper. The copper traces on the board outline where the electrical connections will eventually be made, but before any components are attached, the board remains “blank.”

A bare board is key point in the manufacturing process of electronic devices. Once components like resistors, capacitors, and integrated circuits are added, the blank PCB transforms into a fully functional circuit board. This is the stage where the blank board evolves, moving from raw material to the heart of a functioning device.

How to Use a Blank PCB Board?

Using a blank PCB starts with designing a circuit schematic. Specialized software is used to create a layout that specifies where each component will be placed and how they’ll be connected through copper traces. Once the design is finalized, the blank board serves as a canvas where components are either soldered by hand or using automated machines in mass production.

If you are working on a DIY project or prototyping, the blank PCB allows for customization and flexibility. You can use a soldering iron to manually attach your components. For large-scale production, automated machines place and solder components onto the blank board with precision. Using blank PCBs for custom designs or modifications is a cost-effective way to experiment with electronics.

Why Is PCB So Cheap?

PCBs are considered affordable due to mass production techniques. Modern manufacturing processes, such as automated assembly lines and the use of standard materials, have significantly reduced costs. The global nature of the electronics industry also plays a role, as many manufacturers source materials and labor from countries with lower production costs.

The materials used, primarily fiberglass and copper, are relatively inexpensive. Furthermore, technological advancements have optimized the process of making PCBs, allowing manufacturers to produce them quickly and in large quantities. The result is that even highly specialized PCBs can be produced at a low cost, making them accessible to hobbyists, startups, and large corporations alike. If you want to know the details about factors affect the price of PCB board, welcome to check our another blog:

How Are Blank PCBs Made?

The process of making blank PCBs is a sophisticated, multi-stage operation that ensures the boards meet high precision standards before any components are added. Here’s a detailed breakdown of the steps involved in manufacturing a blank PCB:

Material Selection and Lamination

Blank PCBs start with a substrate, typically made from fiberglass-reinforced epoxy laminate (FR4), which serves as the board’s structural foundation. This substrate is non-conductive, providing insulation for the circuit. A copper layer is then bonded to one or both sides of the substrate using heat and pressure, forming what is known as a copper-clad laminate. The thickness of this copper layer varies based on the board’s intended application, with typical copper thickness ranging from 1 oz (35 µm) to 2 oz (70 µm) per square foot. Thicker copper layers may be used for boards handling higher currents.

Photoresist Application

After lamination, the copper layer is coated with a light-sensitive material called photoresist. This step prepares the board for the next process, which is exposing the circuit pattern. The photoresist layer can be either liquid or dry film and plays a critical role in protecting certain parts of the copper during etching.

Imaging the Circuit Pattern

The desired circuit pattern, generated from PCB design software, is transferred onto the board. This is done by aligning the photoresist-coated board with a photomask (a stencil-like film) that contains the circuit layout. The board is then exposed to ultraviolet (UV) light. The areas of the photoresist not covered by the photomask are hardened, while the areas shielded by the mask remain soft and will later be removed.

Etching Process

The next step is to remove the unneeded copper from the board, a process called etching. Chemical etchants, like ferric chloride or ammonium persulfate, are used to dissolve the unprotected copper, leaving behind only the circuit traces. The areas of the copper protected by the hardened photoresist remain intact, forming the conductive pathways for the future components.

Drilling Holes for Components

After the etching process, holes need to be drilled into the board. These holes, called vias, allow for the placement of components such as resistors, capacitors, and integrated circuits, and are also used to connect different layers in multi-layer PCBs. Advanced PCB manufacturing often uses computer numerical control (CNC) drilling machines to ensure precision, especially for boards with many layers or small trace designs. Some manufacturers employ laser drilling for microvias.

Plating and Hole Metallization

Once the holes are drilled, they need to be plated to create electrical connections between the different layers of the PCB. This is done through a process called electroless copper plating, which deposits a thin layer of copper inside the drilled holes. The plating process ensures that when components are later inserted, electrical signals can flow between layers through the plated holes.

Solder Mask

After drilling and plating, the board is cleaned and coated with a layer of solder mask. This mask protects the copper traces and prevents solder from accidentally bridging across traces during assembly. The solder mask is typically green, though other colors like blue, red, black, or white can also be used. The solder mask is applied through a screen-printing process or as a dry film, and it is cured using UV light or heat.

Silkscreen Printing

Silkscreen printing is applied to the board to mark component locations, symbols, logos, or other identifiers needed during the assembly process. This layer is typically applied using a silk-screening process, similar to how images are printed onto clothing. White is the most common color used for silkscreen, as it provides high contrast against the green solder mask, but other colors can be used depending on the design.

Surface Finishing

The copper pads, where components will be soldered later, are treated with a surface finish to protect them from oxidation and ensure good solderability. Common finishes include HASL (Hot Air Solder Leveling), where the board is dipped in molten solder and excess solder is blown off with hot air, leaving a smooth surface. Another popular finish is ENIG (Electroless Nickel Immersion Gold), where a thin layer of nickel followed by gold is applied to the copper pads.

Electrical Testing and Quality Control

The final step in producing a blank PCB is electrical testing and quality control. Every trace and connection is tested to ensure there are no shorts or opens, which could render the board useless. Automated Optical Inspection (AOI) systems are used to visually inspect the board for defects, while flying probe tests and bed-of-nails tests check for electrical continuity. Any defects found at this stage are flagged for repair or, in severe cases, the board is scrapped.

What Is the Difference Between Bare PCB and PCB?

The term bare PCB refers to the unpopulated circuit board, which means it lacks any electronic components. In contrast, a PCB refers to a fully assembled board that includes all the necessary components to function.

In the bare stage, the PCB is simply the foundation for the circuit but isn’t functional. Once components are soldered onto the bare PCB, it becomes an operational printed circuit board, ready to be integrated into electronic devices.

How Do You Cut Blank PCB?

Cutting a blank PCB requires precision. Tools such as PCB shears, laser cutters, or CNC machines are commonly used to achieve clean, straight cuts without damaging the copper traces. For smaller DIY projects, a hand saw or scoring tool can be used, but these methods require a steady hand and careful planning to avoid mistakes.

Before cutting, it’s important to mark the board clearly to ensure the cuts are accurate. If the board is part of a larger project, cutting should be done after confirming that all components will fit within the intended space.

Why Are PCBs Green?

The green color on most PCBs comes from the solder mask that coats the board. While green is the most common color, the solder mask can be found in other colors such as red, blue, or black. The preference for green is largely historical, as it provided the best contrast for technicians to inspect the board visually.

Green solder masks also tend to offer better performance under different lighting conditions, which can be helpful during manufacturing and quality control processes.

Do PCBs Use AC or DC?

PCBs can handle both AC (alternating current) and DC (direct current), depending on the design and the type of components used. Some boards are designed specifically for DC circuits, while others are built to handle AC power.

For example, a power supply PCB may convert AC from a wall outlet into DC, which is used by many electronic devices. The flexibility to work with either type of current makes PCBs essential for a wide range of applications.

Blank PCB Board Supplier – Best Technology

With over 18 years as an industry leader, Best Technology is one of the most experienced PCB and PCB assembly manufacturer in Asia. We are highly specialized not only in quick-turn PCB prototype and PCB assembly, but also medium and small volume PCB fabrication. In Best Technology, you can enjoy a full-comprehensive one-stop service from PCB design, layout, PCB fabricate, PCB assembly, function testing and delivery. We always try our best to fabricate your PCB with copper clad laminate with the highest quality to meet your demands.

If you have any questions, please feel free to contact us with sales@bestpcbs.com, we will be happy to help you.

Tags:blank pcb
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Can you use AC in PCB?

Monday, October 7th, 2024

Can you use AC in PCB?AC can be used in PCB boards. PCB boards are designed to support the use of AC, and the functions of AC can be realized through proper circuit design and component selection.

Can you use AC in PCB?

The use of AC in PCB boards requires consideration of the characteristics of AC. The current magnitude and direction of AC change continuously over time, which requires the components and layout on the PCB to adapt to such changes. For example, components such as inductors and capacitors play an important role in AC circuits, and their parameters and layout need to be carefully designed to achieve the desired circuit performance.

Specifically, AC circuit design on PCB boards includes selecting appropriate components, layout, and routing. For example, using test instruments such as LCR digital bridges can measure the parameters of components in AC circuits to ensure that the performance of the circuit meets the design requirements. In addition, reasonable ground routing and layout can reduce signal interference and ensure the stable transmission of AC.

Is the circuit board DC or AC?

Circuit boards can transmit both direct current and alternating current. In modern electronic products, we use alternating current for power supply, so most circuit boards are also designed to transmit alternating current. Of course, in some special application scenarios, some circuit boards also need to transmit direct current. Whether transmitting direct current or alternating current, the circuit board needs to meet the requirements of the transmitted current.

What is the PCB in AC?

The alternating current in PCB refers to the current whose direction changes periodically, that is, alternating current (AC). The application of alternating current in PCB is mainly reflected in power conversion and power transmission. PCB power supply usually converts AC into stable direct current (DC) output to meet the demand of electronic equipment for stable power supply. PCB power supply converts AC into the required DC through components such as transformers, rectifiers, filters and voltage regulators, and provides stable power output.

How to calculate the bandwidth of AC in PCB traces

The calculation of AC PCB trace width can be performed by the following formula: W = (I / J) * K, where W represents the trace width, I represents the current, J represents the current density, and K represents a coefficient related to materials and processes. ‌This formula shows that the trace width is related to the current, current density, and material properties‌.

AC in PCB Design Guide

Current Carrying Capacity: The width of a trace directly affects its ability to handle current without exceeding temperature limits or causing excessive voltage drop.
‌Impedance Control: In high-frequency applications, maintaining controlled impedance is critical for signal integrity. Trace width, trace spacing, and dielectric properties affect the characteristic impedance of the transmission line.
‌Heat Dissipation: Adequate trace width helps to effectively dissipate heat, preventing thermal issues such as trace delamination or solder joint failure.
‌Voltage Drop: Narrower traces exhibit higher resistance, resulting in increased voltage drop along the length of the trace. By adjusting the trace width, the voltage drop can be minimized.
‌Manufacturability: The PCB manufacturing process imposes restrictions on the minimum trace width, and designers must balance performance requirements with manufacturability constraints. ‌2.
‌Minimum Trace Width: Most manufacturers have a minimum trace width of 6mil or 0.152mm, and typically use traces of 0.254-0.3mm.
‌Material and Process Deviations: Due to the possibility of material and process deviations in the actual PCB manufacturing process, a certain margin needs to be left when calculating the line width.
‌Signal Integrity Simulation‌: Perform signal integrity simulations to ensure impedance is controlled and signal degradation due to reflections, crosstalk, or transmission line effects is minimized‌

AC in PCB wiring

The current trend is that the power supply voltage is getting lower and lower (especially for highly integrated digital devices), the space occupied is getting smaller and smaller, the weight is getting lighter and lighter, and the efficiency is getting higher and higher, which requires the precise design of the power supply circuit starting from the PCB.

Safety distance includes electrical clearance (spatial distance), creepage distance (surface distance) and insulation penetration distance…

Electrical clearance: the shortest distance between two adjacent conductors or one conductor and the adjacent motor housing surface measured along the air.
Creepage distance: the shortest distance between two adjacent conductors or one conductor and the adjacent motor housing surface measured along the insulation surface.

Determination of electrical clearance:

The distance can be determined according to the measured working voltage and insulation level

The electrical clearance size requirements of the primary side line are shown in Table 3 and Table 4

The electrical clearance size requirements of the secondary side line are shown in Table 5

But usually: Primary side AC part: L-N ≥ 2.5mm before the fuse, L.N PE (earth) ≥ 2.5mm, no requirements are made after the fuse is installed, but a certain distance should be maintained as much as possible to avoid short circuit damage to the power supply.

Primary side AC to DC part ≥2.0mm

Primary side DC ground to earth ≥2.5mm (primary side floating ground to earth)

Primary side to secondary side ≥4.0mm, components connected between primary and secondary sides

Secondary side gap ≥0.5mm

Secondary side ground to earth ≥1.0mm

Note: Before determining whether it meets the requirements, the internal parts should be applied with a force of 10N and the outer shell with a force of 30N to reduce the distance so that the space distance still meets the requirements under the worst case.

Determination of creepage distance:

Based on the working voltage and insulation level, the creepage distance can be determined by looking up Table 6

But usually: (1), primary side AC part: L-N ≥2.5mm before the fuse, L.N earth ≥2.5mm, no requirement is required after the fuse, but try to keep a certain distance to avoid short circuit damage to the power supply.

(2) Primary side AC to DC part ≥2.0mm

(3) Primary side DC ground to ground ≥4.0mm such as primary side ground to earth

(4) Primary side to secondary side ≥6.4mm, such as optocoupler, Y capacitor and other components, the foot spacing ≤6.4mm needs to be slotted.

(5) Secondary side parts ≥0.5mm

(6) Secondary side ground to earth ≥2.0mm or more

(7) Transformer two-stage ≥8.0mm or more

Insulation penetration distance:

It should meet the following requirements according to the working voltage and insulation application:

For working voltage not exceeding 50V (71V AC peak or DC value), there is no thickness requirement;
The minimum thickness of additional insulation should be 0.4mm;
When the reinforced insulation is not subjected to any mechanical stress that may cause deformation or performance degradation of the insulating material at normal temperature, the minimum thickness of the reinforced insulation should be 0.4mm. If the insulation provided is used in the protective casing of the equipment and will not be bumped or scratched during maintenance by the operator, and any of the following conditions apply, the above requirements do not apply to thin insulating materials regardless of their thickness;
For additional insulation, at least two layers of material are used, each of which can pass the dielectric strength test for additional insulation; or:
For additional insulation composed of three layers of material, any combination of two layers of material can pass the dielectric strength test for additional insulation; or:
For reinforced insulation, at least two layers of material are used, each of which can pass the dielectric strength test for reinforced insulation; or:
For reinforced insulation composed of three layers of insulating material, any combination of two layers of material can pass the dielectric strength test for reinforced insulation.

Points to note about wiring process:

Flat components such as capacitors must be flat without glue.

If the distance between two conductors can be shortened by applying a force of 10N, which is less than the safety distance requirement, glue can be used to fix the part to ensure its electrical clearance.

When laying PVC film inside some shell equipment, attention should be paid to ensuring the safety distance (pay attention to the processing technology).

When fixing the parts with glue, be careful not to leave foreign matter such as glue wire on the PCB board.

When processing parts, insulation damage should not be caused.

Requirements for flame-proof materials:

Heat shrink tubing V-1 or VTM-2 or above; PVC tubing V-1 or VTM-2 or above

Teflon tubing V-1 or VTM-2 or above; plastic materials such as silicone sheets, insulating tape V-1 or VTM-2 or above

PCB board 94V-1 or above

Regarding insulation level

(1) Working insulation: insulation required for normal operation of equipment

(2) Basic insulation: insulation that provides basic protection against electric shock

(3) Supplementary insulation: independent insulation applied in addition to basic insulation to protect against electric shock in case of basic insulation failure

(4) Double insulation: insulation consisting of basic insulation plus supplementary insulation

(5) Reinforced insulation: a single insulation structure that provides the same level of protection against electric shock as double insulation under the conditions specified in this standard

The applicable situations of various insulation are as follows:

A. Operational insulation

a. Between parts with different voltages

b. Between ELV circuits (or SELV circuits) and grounded conductive parts.

B. Basic insulation

a. Between parts with dangerous voltages and grounded conductive parts;

b. Between SELV circuits with dangerous voltages and grounding-dependent;

c. Between the primary power conductor and the grounded shield or the core of the main power transformer;

d. As part of double insulation.

C. Supplementary insulation.

a. Generally speaking, between accessible conductive parts and parts that may carry dangerous voltages after basic insulation is damaged, such as:

Ⅰ. Between the surface of handles, knobs, handles or similar objects and their ungrounded axis.

Ⅱ. Between the metal casing of the second category equipment and the outer skin of the power cord passing through this casing.

Ⅲ. Between the ELV circuit and the ungrounded metal casing.

b. As part of double insulation

D. Double insulation

Double insulation Reinforced insulation

Generally speaking, between the primary circuit and

a. between accessible ungrounded conductive parts, or

b. between floating SELV circuits, or

c. between TNV circuits

Double insulation = basic insulation + supplementary insulation

Note: ELV circuit: extra low voltage circuit

Under normal working conditions, the AC peak value between conductors or between any conductors does not exceed 42.4V or the DC value does not exceed 60V.

SELV circuit: safety extra low voltage circuit.

A properly designed and protected secondary circuit so that under normal conditions or single fault conditions, the voltage between any two accessible parts, and between any accessible parts and the protective grounding terminal of the equipment (only for Class I equipment) will not exceed the safety value.

TNV: communication network voltage circuit

Under normal working conditions, the circuit carrying communication signals

Difference between direct current and alternating current

‌The main differences between DC and AC include direction and polarity, voltage change, current loss, transformer use, and application scenarios.

‌Direction and polarity:

DC: The direction of the current remains unchanged, and the electrons flow from the positive electrode to the negative electrode.

AC: The direction of the current changes periodically, and the electrons flow back and forth between the positive and negative electrodes. ‌
‌Voltage change:

DC: The voltage remains constant and does not change over time.

AC: The voltage magnitude and direction change periodically over time. For example, the mains is an AC with a sine waveform.

‌Current loss:

DC: Fault losses are relatively small.

AC: There is capacitive current, and there is capacitive current in the transmission line. ‌
‌Transformer use:

DC: The voltage cannot be changed using a transformer.

AC: The voltage can be changed using a transformer, which is suitable for boosting voltage to reduce losses during long-distance transportation.

‌Application scenarios:

DC: Suitable for low-voltage electrical appliances and occasions that require stable current.
‌Alternating current‌: Suitable for household and industrial use, using transformers to change voltage to suit different needs.‌

FAQ About AC in PCB

FAQ About AC in PCB

Q: The relationship between PCB current and line width. Is the current divided into AC or DC?
A: The relationship between PCB current and line width is not divided into AC or DC. In terms of the nature of the lines on the PCB, the lines are all made of copper materials, and both AC and DC can pass. However, how much current can pass depends on the cross-sectional area of the line on your PCB. That is, line width x thickness of the copper foil of the line. If the cross-sectional area of the line is small, only small current signals can pass, and if the cross-sectional area is large, large current signals can pass. This signal can be AC or DC.
Not just 1mm, any line width can pass DC or AC signals.

Q: There is a packaged device, and there are 2 pins in the device that need to be connected to the live wire and neutral wire of 220V AC respectively. So how to deal with this power line when drawing the PCB? Are there any size requirements for pads, wires, etc.? Are there any protective measures required? Is it not possible to directly add pads to connect to the pin pads of the device?
A: It is best to mill a groove between the neutral wire and the live wire, and choose the thickness of the wire according to the current. When the current is large, you can put a tin layer on the wire, and the pad should be slightly larger.

Q: The grounding of the PCB circuit board design is also the negative pole. What is the difference between the grounding here and the AC grounding?

A: The concept of the circuit board ground is somewhat different from that of the power supply system. The power supply system refers to the earth, that is, the terminal with the same potential as the earth.

The ground in the circuit board is just a common terminal of a potential, which can be positive or negative, depending on the needs of the designer. It’s just that everyone is used to and assumes that the negative pole is the common terminal, that is, the ground. The circuit board ground is not necessarily connected to the earth.

But it must be connected to the earth when EMI filtering is required.

Q: Should all GNDs on the PCB board be connected? There is a terminal (screw type) with two terminals marked as V1+ and V1- on the PCB schematic. Should V1- be connected to the power supply ground? But I used a multimeter to measure why V3- is not connected to other GNDs on the board?

So how do you connect the ground and 10V of the power supply to the V1+ and V1- ends of the terminal?

A: Not all ground wires on the board are connected together. The ground wires are divided into analog ground and digital ground, just like the ground wire in DC and the ground wire in AC cannot be connected together. That is to say, there is a ground wire that is specifically used for power supply, and there is a ground wire that is specifically used for signals (shielding signal interference). These two ground wires cannot be connected together.
In addition, you mentioned V1+ and V1-, and V1- should not be considered a ground wire. Generally, the signal represented by this method is a differential signal, that is, the V1 signal is differentially divided into V1+ and V1-, which can reduce external interference and transmit farther. Finally, V1+ and V1- are integrated into the V1 signal.
You need to figure out whether the V1+ and V1- of the terminal are used for power supply. If they are used for power supply, then V1+ is the positive pole. V1- is the negative pole. Since you didn’t show us the picture, you can’t just connect it randomly. The circuit board needs to connect not only power but also signals, depending on how your board is made.

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How to convert .brd to .hyp file

Friday, October 4th, 2024

How to convert .brd to .hyp file?You can try to use HyperLynx’s built-in conversion function to directly convert Allegro’s .brd file, but this method may encounter some problems and cause the conversion to fail. ‌

If the built-in conversion function fails, you can try to convert the .brd file to ODB++ format and then import it into HyperLynx. The specific steps are as follows:

Open the PCB file in Allegro, select “File” -> “Export”, and then select ODB++ format for export.
After the export is successful, open HyperLynx, select “File” -> “Open ODB++”, select the exported ODB file, and wait for the import to complete before performing PCB board-level simulation. ‌1.
If the above method still cannot solve the problem, you can try to add the system variable CDSROOT to solve the conversion failure problem. The specific steps are as follows:
Add the system variable CDSROOT, and the value is the installation path of Cadence Allegro, such as D:\Cadence\Cadence_SPB_17.2-2016\tools\bin.
After confirming, restart the computer and try the conversion operation again‌

How to convert Cadence17.2’s .brd file to HyperLynx9.4.1’s .hyp file

How to convert Cadence17.2’s .brd file to HyperLynx9.4.1’s .hyp file?Recently, I used Hyperlynx to simulate the signal integrity of PCBs, and I needed to convert various PCB formats into .hyp formats. In the process, I found that the PCB drawn by AD can be directly exported in .hyp format, which is very convenient, but the PCB drawn by Cadence cannot be directly exported. I need to use the built-in PCB converter of Hyperlynx to convert the .brd file of Cadence, as shown below:

But the conversion has always failed. I checked the .ERR file and found a line like this: ERROR: Cadance Allegro utility:extracta, so it is a problem with extracta.exe.

The specific solution is to add the system variable CDSROOT, and the value is D:\Cadence\Cadence_SPB_17.2-2016\tools\bin (the location of your extracta.exe). After confirming, restart the computer and the problem is solved.

Tutorial on converting Cadence17.2’s .brd file to HyperLynx9.4.1’s .hyp file

Tutorial on converting Cadence17.2’s .brd file to HyperLynx9.4.1’s .hyp file?Open the PCB file in Allegro, select ODB++inside in file–>export, select Export as ODBV6, click 1, and then click Accept….

HyperLynx’s built-in conversion function can directly convert Allegro’s .brd file for use, but for some reason the following error always occurs. I didn’t find a solution online, so I had to find another way.

Another way to import PCB into HyperLynx is to convert the file to ODB++inside format. This method requires the installation of the ODB++inside plug-in in advance.

After installing the plug-in, you can convert the .brd file.
First open the PCB file in Allegro, select ODB++inside in file–>export, the following figure appears, select Export as ODBV6, click 1, and then click Accept.

Wait for the conversion to succeed.

This file is the converted file
Open HyperLynx9.4.1, select open ODB++ in file, select the odbjob_v6 folder, and click select folder.

Wait to open.

Click ok. .

What is a .hyp file?

.hyp file is a file used to record key information such as boundary conditions, material properties, solver settings, etc. of the analysis. ‌ This file is usually associated with HyperWorks analysis software and is the basis for numerical calculation and analysis.

The specific uses of .hyp files include:

‌Geometry model file‌: represents the geometry of the product or structure.
‌Mesh file‌: shows the process of dividing the model into finite elements.
‌Simulation setting file‌: records the key setting information of the analysis.
‌Result file‌: contains the calculated engineering quantities such as strain, stress, displacement, etc.
‌Post-processing file‌: used to visualize and analyze results in tools such as HyperView.
‌Report document‌: usually in PDF or Word format, recording detailed results and conclusions of the analysis‌1.
In terms of use, for example, in PCB tool software, .hyp files can be created and edited through the BroadSim function, including setting line characteristics, editing stacking information, etc., to simulate and analyze circuit boards‌2. In addition, the Hype software also supports exporting to .hyp format files for further analysis and processing.

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Board electronics with holes

Friday, October 4th, 2024

Board electronics with holes The types of vias in PCB include through holes, blind holes and buried holes, which have different characteristics and requirements in design and manufacturing. The selection of the appropriate via type should consider the number of PCB layers, wiring density, signal frequency, cost budget and production process. The via design should pay attention to avoid affecting the welding quality, preventing electrical short circuits, and saving costs in high-density packaging.

What are the holes in a PCB called?

What are the holes on PCB called? What are the holes in the circuit? The holes on PCB can be roughly divided into 3 types, screw holes (mounting holes), conductive holes (vias), and plug-in holes.

Screw holes: Screw holes are used for fixing.

Conductive holes: Conductive holes (also called vias) are used for conducting electricity just like circuits.

Plug-in holes: Plug-in holes are of course used to plug in various parts, such as diodes, transistors, capacitors, inductors, etc.

What is a through hole

What is a through hole? Through holes, also known as perforations, are holes in a PCB that go all the way through the board. Their main purpose is to provide electrical connections for component pins while allowing soldering on both sides of the board.

1.A via is a special through hole whose wall is metallized to achieve electrical connection between different layers on a circuit board. This type of hole is usually used to connect component pins to internal circuits, or to achieve electrical connection between different layers in a multi-layer PCB. Vias need to be metallized during the PCB manufacturing process, which usually includes drilling, desmearing, chemical copper plating, and electroplating.

2.Non-conducting holes are the opposite of through holes. Their hole walls are not metallized, so they do not have electrical connection functions. These holes are mainly used for mechanical fixation, heat dissipation or identification purposes. Non-conducting holes are relatively simple in the PCB manufacturing process, and only drilling operations are required.

What is a blind via?

A blind via is a hole that extends from one side of a PCB to a certain internal layer without penetrating the entire board. The emergence of blind vias is mainly due to the development of HDI technology, which provides circuit designers with greater flexibility and more compact layout. Blind vias are usually used to connect surface mount components (SMD) to internal circuit layers, or to connect circuits between different internal layers.

What are buried vias?

Buried vias are holes located inside the PCB that do not penetrate any side of the board. They are completely hidden inside the board and are used to connect circuits between different internal layers. Buried vias are especially useful in HDI boards because they can reduce the overall thickness of the board while maintaining electrical connections between internal circuits.

What is a microvia?

Microvia refers to a hole with a smaller diameter, usually at the micron level. The emergence of microvia technology enables PCB designers to achieve more complex circuit layouts in a smaller space. Microvias are often used in high-density, high-reliability electronic devices such as mobile phones and tablets. The manufacture of microvias requires high-precision drilling equipment and technology to ensure the accuracy and reliability of the holes.

What are Mounting holes？

What are Mounting holes?Locking holes are auxiliary holes used in the PCB manufacturing and assembly process to accurately locate and fix the circuit board. They are usually located at the edge or specific position of the PCB to ensure that the circuit board can be accurately aligned and fixed during manufacturing, testing and assembly. The locating holes do not participate in the connection of the circuit, but are essential to ensure the quality and performance of the circuit board.

What are Mounting holes？

What are thermal vias?

Thermal vias are holes designed specifically for heat dissipation, usually large and can run through the entire PCB or multiple layers. Their role is to reduce heat buildup on the circuit board by increasing surface area and air flow, thereby improving the stability and reliability of the device. Thermal vias are particularly important in high-performance, high-power electronic devices.

FAQ About board electronics with holes

How to solve the contradiction between manual routing and automatic routing of high-speed signals?

Most of the current powerful routing software’s automatic routing tools have set constraints to control the routing method and the number of vias. The routing engine capabilities and constraint setting items of various EDA companies are sometimes very different. For example, whether there are enough constraints to control the winding method of the serpentine, whether the routing spacing of the differential pair can be controlled, etc. This will affect whether the routing method generated by automatic routing can meet the designer’s ideas. In addition, the difficulty of manually adjusting the routing is also related to the capabilities of the routing engine. For example, the pushing ability of the routing, the pushing ability of the via, and even the pushing ability of the routing pair copper. Therefore, choosing a routing tool with strong routing engine capabilities is the solution.

Will adding test points affect the quality of high-speed signals?

As for whether it will affect the signal quality, it depends on the method of adding test points and how fast the signal is. Basically, the additional test points (not using the existing vias (via or DIP pins) as test points) may be added to the line or a small section of wire may be pulled out from the line. The former is equivalent to adding a very small capacitor to the line, while the latter is an additional branch. Both of these situations will have some impact on high-speed signals, and the extent of the impact is related to the frequency speed of the signal and the edge rate of the signal. The magnitude of the impact can be learned through simulation. In principle, the smaller the test point, the better (of course, it must meet the requirements of the test equipment) and the shorter the branch, the better.

Can you introduce some foreign technical books and data on high-speed PCB design?

Now the application of high-speed digital circuits includes communication networks and calculators and other related fields. In the communication network, the operating frequency of PCB boards has reached around GHz, and the number of layers is as many as 40 layers as far as I know. Due to the advancement of chips, the operating frequency of calculator-related applications, whether it is a general PC or server, has reached 400MHz (such as Rambus) or above. In response to the demand for high-speed and high-density routing, the demand for blind/buried vias, mircrovias and build-up process technology is gradually increasing. These design requirements can be mass-produced by manufacturers.

Does the design of rigid-flexible boards require special design software and specifications? Where can I undertake the processing of such circuit boards in China?

Can I use general PCB design software to design flexible printed circuits (Flexible Printed Circuit). The Gerber format is also used for FPC manufacturers to produce. Since the manufacturing process is different from that of general PCBs, each manufacturer will have its own restrictions on line width, line spacing, and aperture (via) based on their manufacturing capabilities. In addition, some copper foil can be laid at the turning point of the flexible circuit board for reinforcement. As for the manufacturer, you can search for “FPC” as a keyword on the Internet and you should be able to find it.

If the size of the circuit board is fixed, if the design needs to accommodate more functions, it is often necessary to increase the routing density of the PCB, but this may lead to increased mutual interference between the routings, and at the same time, the impedance cannot be reduced if the routing is too thin. Please introduce the techniques in the design of high-speed (>100MHz) high-density PCBs?

When designing high-speed and high-density PCBs, crosstalk interference does need to be paid special attention to because it has a great impact on timing and signal integrity. Here are a few things to note:

Control the continuity and matching of the characteristic impedance of the trace.

The size of the trace spacing. The spacing commonly seen is twice the line width. Through simulation, you can know the impact of trace spacing on timing and signal integrity and find the tolerable spacing. The results of different chip signals may be different.

Choose an appropriate termination method.

Avoid the same routing direction of the upper and lower adjacent layers, or even have traces overlapped up and down, because this kind of crosstalk is greater than the case of adjacent traces on the same layer.

Use blind/buried vias to increase the trace area. However, the production cost of the PCB board will increase. It is indeed difficult to achieve complete parallelism and equal length in actual implementation, but it should be done as much as possible.

In addition, differential termination and common mode termination can be reserved to mitigate the impact on timing and signal integrity.

The RF part, IF part, and even the low-frequency circuit part of the outdoor unit are often deployed on the same PCB. What are the material requirements for such PCB? How to prevent interference between RF, IF, and even low-frequency circuits?

Hybrid circuit design is a big problem. It is difficult to have a perfect solution.

Generally, RF circuits are laid out and wired as an independent single board in the system, and there will even be a special shielding cavity. Moreover, RF circuits are generally single-sided or double-sided boards, and the circuits are relatively simple. All of these are to reduce the impact on the distributed parameters of RF circuits and improve the consistency of RF systems. Compared with general FR4 materials, RF circuit boards tend to use high-Q substrates. The dielectric constant of this material is relatively small, the distributed capacitance of the transmission line is small, the impedance is high, and the signal transmission delay is small. In hybrid circuit design, although RF and digital circuits are made on the same PCB, they are generally divided into RF circuit area and digital circuit area, and laid out and wired separately. Shielding is used between ground vias and shielding boxes.

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