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How Does Thermal Resistance of Solder Mask Effect Ceramic PCBs?

Tuesday, April 23rd, 2024

In the printed circuit board (pcb) fields, thermal management is a key consideration especially in industries such as automotive, aerospace, tele-communications and power electronics. Ceramic PCBs are known for their excellent thermal conductivity and mechanical properties and are becoming increasingly popular in applications where efficient heat dissipation is essential. Under this situation, solder resistance materials play a vital role not only in protecting the circuit, but also in influencing thermal behavior.

ceramic pcb

What is Thermal Resistance in Ceramic Circuit Board?

Ceramic PCBs are usually composed of materials such as alumina (Al2O3) or aluminum nitride (AlN), which have superior thermal conductivity compared to traditional glass fiber PCB substrates. This inherent thermal conductivity promotes the efficient transfer of heat from heating components, improving the reliability and performance of electronic devices. However, while substrate materials make an important contribution to thermal management, the thermal resistance of solder resistance materials must also be considered.

Solder mask materials are mainly used to isolate conductive wires on the pcb, prevent unexpected electrical connections, and protect the circuit from environmental factors such as moisture, dust, and chemical contaminants. Although solder mask is not generally praised for their thermal conductivity, their thermal resistance can affect the heat dissipation within the PCB components.

ceramic pcb

What Factors Influencing Solder Mask Thermal Resistance?

Solder resistance thermal resistance is an important feature in the design and performance of printed circuit boards, especially when considering thermal management of electronic devices. There are several factors that affect the thermal resistance of solder pads, and understanding these factors can help optimize the thermal design of the PCB. Here are the key factors:

Solder Mask Composition

The type of resin and fillers used in the solder mask can significantly affect its thermal properties. Epoxy resins are common, but other materials may offer better thermal conductivity.

Thickness

Thicker layers of solder mask can increase thermal resistance because they add more insulating material between the heat source (such as electronic components) and the ambient environment. Thinner layers might improve heat dissipation but could be less effective in protecting against physical damage or corrosion. Generally, solder mask has around 20-25um thickness and has 0.2W/m.k thermal conductivity.

Curing Process

The process conditions under which the solder mask is cured (temperature, time, and environment) can impact its mechanical and thermal properties. Improper curing can lead to reduced heat transfer efficiency.

Dielectric Constant

The dielectric constant of the solder mask material influences its ability to conduct heat. Materials with higher dielectric constants may provide higher thermal resistance.

Interface with Substrate

The interface between the solder mask and the ceramic substrate can affect thermal resistance. Poor adhesion or air gaps may decrease heat transfer between the layers.

ceramic pcb

What are the Importances of Thermal Resistance in Ceramic PCBs?

Efficient thermal management is crucial for maintaining the reliability and longevity of electronic devices, especially in applications where high temperatures can degrade components or compromise performance. In ceramic PCBs, where heat dissipation is a key advantage, minimizing thermal resistance throughout the assembly is essential.

While ceramic substrates inherently offer excellent thermal conductivity, the solder mask layer presents a potential bottleneck for heat transfer. Therefore, selecting solder mask materials with optimal thermal properties and ensuring proper application are critical steps in PCB design and manufacturing.

Applications and Considerations:

Ceramic PCBs find applications in various industries, including power electronics, LED lighting, automotive systems, and telecommunications infrastructure. In these applications, where thermal management is critical, careful consideration of solder mask thermal resistance is essential for meeting performance requirements and ensuring reliability under challenging operating conditions.

Designers and engineers must balance the need for thermal management with other considerations such as cost, manufacturability, and compatibility with assembly processes. Collaboration with experienced PCB manufacturers and material suppliers can help optimize the selection of solder mask materials and design solutions tailored to specific application requirements.

The thermal resistance of solder mask materials is an important consideration, especially in applications where heat dissipation is a concern, such as high-power electronics or devices operating in harsh environments.

Solder mask materials are designed to withstand the temperatures encountered during the PCB fabrication process, including solder reflow, typically ranging from around 220°C to 280°C (428°F to 536°F), depending on the specific materials and processes used.

ceramic pcb

However, when it comes to the thermal resistance of solder mask materials in terms of their ability to dissipate heat away from components or traces on a PCB, they generally have lower thermal conductivity compared to materials like copper or aluminum. This means that they are not as effective at transferring heat away from heat-generating components.

In high-power applications or those where thermal management is critical, additional measures may need to be taken, such as incorporating heat sinks, thermal vias, or selecting solder mask materials with improved thermal properties. Some manufacturers offer solder mask materials with enhanced thermal conductivity for specific applications where heat dissipation is a concern.

As electronic devices continue to evolve with increasing power densities and miniaturization, the demand for advanced thermal management solutions will grow. In the realm of ceramic PCBs, ongoing research and development efforts aim to enhance the thermal properties of solder mask materials, enabling more efficient heat dissipation and further improving the reliability and performance of electronic systems.

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We Will Be Exhibiting at New-Tech Israel 2024

Friday, April 12th, 2024

Best Technology, a China-based PCB & PCBA manufacturer will be exhibiting at New-Tech 2024 in EXPO Tel-Aviv, Israel at booth No. 66 from May 28, 2024 to May 29, 2024(Western Time). Actually, we have participated in such exhibition for several years. At our exhibition booth, attendees will be able to learn more about our company for PCB manufacturing and PCB assembly technology. Here are some pictures for your reference.

pcb exhibition
AEMS show
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pcb exhibition
ceramic exhibition
Ceramic exhibition
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pcb exhibition

For interested professionals, Best Technology had on hand experts to offer detailed insights and experience on PCB assembly, covering PCB prototype and low/high-volume production. For more information on PCB assembly and fabrication, welcome to visit our booth.

You will see 10mm to 1,500 mm flexible circuit board, from 2layer rigid-flex circuit to 50 layers, 1/2 OZ copper to 3 OZ, 0.15mm extra thin FR4 PCB to 30 OZ heavy copper, various ceramic PCBs (thick film, thin film, DPC, DBC, HTCC, AMB, LTCC). Our new products also will be shown in this exhibition, like copper/aluminum busbar PCB, transparent/PI/rubber silicone flexible heating film, semi-flexible PCB, semi-flexible aluminum PCB.

best products

In Best Technology, you will enjoy one-stop service from components sourcing, board fabrication (FPC, PCB, MCPCB, Ceramic PCB) and final assembly with programming and testing and metal dome that is used in conjunction with a printed circuit board, flex circuit, or membrane switch, become normally-open tactile switches. we have four types of metal domes: four legs with size from 5mm-20mm; triangle with size 4mm-12mm; round dome with size 4-16mm, oblong dome with size 3.7mm-58.1mm, and we also make dome with adhesive, named dome array, custom membrane switches also available in Best Tech.

You are warmly welcome to see how we can manage the components wastage and efficiency to help save your time, money and energy.

About New-Tech:

The New-Tech Exhibition is the largest and major exhibition of the Hi–Tech & Electronics in Israel. More than 150 companies, who lead these fields in Israel and around the world, will take part and exhibit in this trade show.

This exhibition shows a comprehensive array of electronic components, production processes, subcontracting services, clean room equipment, electro-optic devices, test equipment, printed circuit boards, industrial materials, computerization solutions, robotics, power systems, RF/microwave technologies, and more. Attendees can explore cutting-edge innovations in development, design, engineering, and procurement across various industries.

It is important to note:

1. Participation in the exhibition is conditional on prior registration, even for invited customers.

2. After registration and before the conference, a code will be sent to the mobile to confirm participation in the conference.

For more details and registration: https://www.new-techevents.com/exhibition-registration-form/

Welcome to visit us at Booth #66 from May 28, 2024 to May 29, 2024 (Western Time).

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Do You Know What Is PCB Stiffener Busbar?

Wednesday, March 27th, 2024

Busbar PCB is an electronic component, also known as a socket board or mother board, which is an important part of an electronic device and is used to connect and transmit current and signals, so it plays a crucial role in the design of electronic devices. Busbar PCB is like a PCB coated with an “ear”, which we also call it as stiffener busbar. Want to know more about it? Welcome to reading on!

(Busbar_pcb)

What is PCB Stiffener Busbar?

A busbar circuit board is a key component used in electrical systems. It usually consists of a main conductive busbar (usually copper or aluminum) that is covered with an insulating material such as prepreg or resin. Busbar boards are used to transmit high currents in power systems, such as in industrial equipment, power distribution systems, and control panels.

These boards typically have multiple slots for inserting electrical connectors or electrical devices. The design of the bus board can be customized according to the specific application requirements to adapt to different current and voltage requirements. They are widely used in the industrial and commercial sectors because they provide reliable power transmission and connectivity solutions.

(Busbar_aluminum_pcb)

What Are Benefits of Using a Busbar PCB?

Busbar stiffener pcb serves as a crucial element of conducting electricity, especially when simplifying the power distribution process, saving costs and requiring greater flexibility. They come in a variety of sizes and different coatings, such as aluminum and copper. The material type, dimension, size and shape of the busbar determine the current capacity it can carry. Compared with a coil harness, though it is expensive in manufacturing, but has longer life and does not need to replace in a short time. Here we listing some benefits of busbar PCB:

  • Efficient Power Distribution

With the fast development of new energy cars and vehicles, the electronic parts in the cars also should updated to meet the demands of renewable energy powers. So the busbar PCB stands out because it can distribute the powers in devices efficiently. Meanwhile, it also can help to reducing the consumption of energy. Because of its integrated nature, it can easily adapt to the integration of renewable energy, which is quite intriguing to consider in this advanced era of energy.

  • High Conductivity

The busbar stiffener on a PCB is typically crafted from either copper or aluminum. Copper, renowned for its excellent conductivity, stands out as the preferred material for busbars due to its capacity to facilitate the flow of electrons. Moreover, copper’s robust nature enables it to withstand harsh environmental conditions and high temperatures, thus bolstering its longevity and durability. But if you want PCB that can carry higher conductivity, ceramic PCB is the best choice but a little bit higher cost.

(Busbar_copper_pcb)
  • Can be Customized

Busbar is a highly customization product in PCB design, it offers various options for its mechanical capability. So maybe you can find it in every industry, such as educations, medical instruments, factories, communications and various electronic devices. Tight space and compact devices require substitute electrical distribution, and busbars serve the purpose right. Due to its high compact and strong mechanical and chemistry, busbar PCB can be used in extremely harsh weather. This makes them a good choice in substations or devices that need to used outdoors.

  • Space Saving

Due to the copper materials mounted on the PCB, Busbar PCBs can replace multiple traces with a single, wider conductive strip, saving valuable space on the board. This compact design is particularly useful in applications where space is limited. In addition, busbar PCB provides multi-layer structure when your design is complex and has density traces network.

By means our extensive PCB & PCBA manufacturing and professional engineering team, we are highly able to build and design busbar PCBs according to your specific requirements. Meanwhile, we follow the strict quality system to make sure the high-quality of products. You are welcome to contact us or send e-mail if you want to make such busbar stiffener PCB.

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2024 Newest Guide to High Thermal Conductivity PCBs

Monday, March 18th, 2024

Currently, with the rapid development of the digital era, the demands and requirements for electronics have increased significantly. Many double-sided and multi-layer boards have high density and power, making it difficult to dissipate heat efficiently. Conventional printed circuit board substrates such as FR4 and CEM3 are poor thermal conductors with interlayer insulation, the heat can’t transfer out, which leading to high-temperature failure of electronic components and devices. So, engineers and researchers are aiming to find high thermal conductivity PCBs to solve such problems, and metal core PCB and ceramic PCB stand out at this time.

Metal core PCB is a type of PCB that made by metal alloy material as the base core, commonly are aluminum core or copper core, rarely is iron PCB. They are popular because of its good heat dissipation properties and good mechanical strength.

What is Aluminum PCB and Why Use It?

Aluminum substrate is a low-alloyed Al-Mg-Si series high-ductility alloy sheet. It exhibits excellent thermal conductivity, electrical insulation properties, and mechanical machinability. Compared to traditional FR-4, with the same thickness and line width, aluminum substrate can carry higher currents, withstanding voltages up to 4500V. Its thermal conductivity coefficient exceeds 2.0.

A normal single side (1L) aluminum core PCB consists of three layers, aluminum base, dielectric layer and copper trace layer. Generally speaking, 1L aluminum PCB is always used for LED lighting, high current LED, spotlight, etc. So it also called LED PCB. For high-end applications, there are also designs for double-sided boards, structured as circuit layer, insulation layer, aluminum base, insulation layer, and circuit layer. In rare cases, multi-layer boards are used, which can be composed of multi-layer FR4 boards laminated to insulation layers and aluminum base.

Aluminum_PCB

The thermal conductivity of aluminum core is range from 1-3W/m.k, the higher conductivity, the better heat dissipation. However, not all the projects is suitable for higher conductivity, it should depend on the specific requirements, such as mechanical strengthen, corrosivity. Nowadays, Best Technology used 6061, 5052, 1060 aluminum alloy as the metal core, others also available if customers have requirements.

How Does Copper Core PCB Works?

Copper substrate is the most expensive type among metal substrates, offering significantly better thermal conductivity compared to aluminum and iron substrates. It is suitable for high-frequency circuits, regions with large temperature variations, and precision communication equipment for heat dissipation purposes, as well as in the construction and decoration industries.

The copper PCB’s circuit layer requires a significant current-carrying capacity, thus necessitating the use of thicker copper foils, typically ranging from 35μm to 280μm in thickness. The thermal insulation layer is the core technology of the copper substrate, composed of aluminum oxide and silicon powder as the main thermal conductive components, filled with a polymer of epoxy resin. It exhibits low thermal resistance (0.15), excellent viscoelastic properties, and possesses the ability to resist thermal aging, withstanding mechanical and thermal stresses.

The metal base layer of the copper substrate serves as its supporting component, requiring high thermal conductivity. It is typically made of copper foil, though copper plate can also be used (with copper PCB offering better thermal conductivity, around 1-400W/m.k). These substrates are suitable for conventional mechanical processing methods such as drilling, punching, and cutting.

Copper_core_PCB

What Are Differences Between Copper and Aluminum PCB?

Though both copper and aluminum are metal core PCB, they still have some differences in characteristic and manufacturing. Knowing their differentiation can help you to understanding and making correct decision in material selection.

  • Material

Copper has excellent electrical conductivity and mechanical strength, so copper PCB is well-suit for high frequency circuits and high-power electronic equipment. While aluminum is slightly inferior to the copper base, so it is a good choice of low-power devices.

  • Cost

Compared with copper, aluminum PCB has much advantages in cost, so if you have limited budget and require to use for low-power equipment such as LED lights, aluminum is the better one.

  • Manufacturing

Due to copper has great hardness and good strengthen, it requires for special technical and complex processes, for example: chemical etching, electro-plating. However, the lightweight of aluminum makes it easy in manufacturing. In addition, PTH (plated through holes) can be created on copper PCBs, but not on aluminum ones.

  • Physical Property

The difference in elastic modulus between copper and aluminum is significant, resulting in less warping and expansion/contraction in copper substrates compared to aluminum substrates.

  • Application

Aluminum PCB is lighter than copper substrate, the material cost is lower, often used in daily LED lights or electronic equipment. Because of its strong thermal conductivity and better electrical conductivity, copper substrate is usually used in high-speed circuits and high energy circuits. In addition, copper substrates are also widely used in areas requiring high heat transfer and heat dissipation performance, such as power amplifiers, power supplies, power tools, automotive engine controllers and solar inverters.

Sink_Pad_PCB

What is Ceramic PCB? And Its Thermal Conductivity?

Ceramic PCB is one of the high thermal conductivity PCBs in this industry. They have good high-frequency properties and electrical properties, and have high thermal conductivity, chemical stability and excellent thermal stability of organic substrates without. It is a new generation of large-scale integrated circuits and power electronics module ideal packaging materials. The thermal conductivity of the ceramic substrate can reach about 220W/ M.K according to the preparation method and the material formula. Theoretically speaking, the thermal conductivity of ceramic circuit made by alumina is 24-28W/m.k, AlN is 150-240W/m.k and for BeO is 22-250W/m.k.

Ceramic PCB can be divided into various types of PCB according to its different PCB manufacturing process, they are thick film, thin film PCB, DPC, DBC, HTCC and LTCC ceramic circuit board. Different types of PCB made in different temperature and uses different materials, this means they have different chemistry and physical properties. So you should take them into consideration when designing a ceramic PCB for your device.

Ceramic_PCB

A Reliable PCB Supplier in China – Best Technology

Whatever you choose metal core PCB or ceramic PCB, a reliable supplier is necessary and needed. Best Technology has extensive manufacturing experience in PCB and we are very confident that we can serve you the best service and high-quality product. With rich experience and strong R&D team, we know how to provide you the best solution and evaluate the design files for you. We have professional DFM (Design For Manufacturing) process to identify the mistakes or inappropriate layout in design. Welcome to contact with us to discuss your PCB projects.

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What Is Immersion Silver? Why Choose It for PCB Coating?

Monday, February 26th, 2024

Due to the growing concerns and advocacy for environmental friendliness, as well as the prohibition of harmful substances like lead (tin), an increasing number of industries are moving away from the use of HASL (Hot Air Solder Leveling) technologies for PCB (Printed Circuit Board) surface treatment. The current trend is to use other surface treatments such as OSP, gold plating, immersion tin, immersion silver, ENIG and ENEPIG. Among them, immersion silver becoming a popular choice since it has excellent performance and cost effectiveness.

What is Immersion Silver Finish?

Immersion silver finishing is an environment friendly surface treatment that coating a layer of silver (about 0.1~0.4um) on the copper surface to ensure the good solderability when assembly. When comparing its functional performance with other surface finishes like OSP and ENIG, immersion silver falls between them. It exhibits outstanding solderability and exceptional solder joint strength, surpassing OSP, which lacks a conductive barrier. However, when employed as a contact surface, immersion silver demonstrates lower strength compared to gold.

What is the Working Principle of Immersion Silver?

Immersion silver finishing uses chemical deposition to finish the whole processes. Electrochemical deposition is a method of reducing and depositing metals onto the surface of an object by controlling the current in a solution. In the immersion silver process, the pad serves as the anode (positive electrode), while silver acts as the cathode (negative electrode), with a current applied between them. This causes silver ions (Ag+) to be reduced to silver metal under the influence of the electric field, subsequently adhering to the pad surface and gradually forming a silver layer.

The displacement reaction of immersion silver is:

2Ag+ + Cu = 2Ag + Cu++

This method utilizes both electrical current and chemical reactions to deposit silver from the solution onto the surface of the PCB pad, creating a uniform and porous silver layer.

Silver Plated Analyzing: Pros vs Cons

Before selecting the immersion silver coating, we should understand its advantages and disadvantages to consider whether it is suitable for your PCB project and end-applications.

Pros of immersion silver:

  1. Cost-effective than immersion gold
  2. Good surface flatness and low contact resistance
  3. Corrosion resistance
  4. Good solderability, especially for BGA chips or smaller components
  5. Environment friendly
  6. High reliability

Cons of immersion silver:

  1. Difficult to handle, must wear gloves
  2. Special storage conditions – if the package is opened and not all PCBs need to be used, it must be resealed quickly or use them within 24h.
  3. Peelable masks can’t to use

Important Points You Must Know About Storage

  1. For storage and handling, it needs more careful than immersion tin and OSP.
  2. It is compliant with ROHS and safer than HASL.
  3. In the dry conditions, it can be stored 6-12months.
  4. PCB with immersion silver must be soldered within 24hours if package is unsealed.
  5. If the immersion silver PCB has been stored for more than 12 months, a solderability testing is must before assembling.

Immersion Silver vs ENIG

ENIG also is a common surface treatment in the PCB manufacturing, its full name is Electroless Nickel/Immersion Gold finishing. The ENIG technology is a relative expensive than immersion silver, and it suitable for more complex layout design.

ENIG plating involves safeguarding the copper pads on PCBs by first applying a layer of nickel and then overlaying the copper surface with a thin layer of gold. In essence, the procedure is akin to immersion silver, but it significantly improves PCBs by providing enhanced resistance to oxidation, superior solderability, and excellent surface planarity.

Let’s review the performance comparison between these two surface treatments:

Welcome to contact us if you have any questions about immersion silver or other surface treatment.

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How Does the Ceramic PCB Works in IGBT Modules?

Friday, January 19th, 2024

IGBT (Insulated Gate Bipolar Transistor) is a bipolar junction transistor (BJT) with a MOS gate, or we can say that an IGBT module is a combination of BJT and MOS module. Despite its small size, the IGBT chip can control the transmission of electrical energy. It can switch the current 100,000 times within 1 second under an ultra-high voltage of 650 million volts.

What is the Working Principle of IGBT?

IGBT combines the features of a transistor and a switching circuit, making it a new type of electronic component that can control current efficiency. Its structure allows it to achieve current control from turn on to off without generating excessive leakage current, as well as not affecting the operation of other circuits.

The working principle of IGBT modules including two parts – the current control of MOS gate and BJT transistor. When the voltage of MOS gate changes, it affects the conduction of the transistor, thus controlling the flow of current. When the BJT comes into play, it controls the flow of current, so that improve the working efficiency of the IGBT.

(Working_principle_of_IGBT)

How Does A Ceramic PCB Protect IGBT Modules from Overheat?

As you know, IGBT modules have been applied for many years in various industries such as automotive, industrial, aerospace, consumer electronics, and more. However, optimizing the thermal dissipation of IGBT packaging is crucial to enable the modules to operate at higher power conditions. If heat dissipation is improved, IGBT modules can be used in more advanced applications.

You might be wondering how much heat does an IGBT module generate during running? It’s equivalent to the heat produced by 100 electric furnaces. This substantial amount of heat must be dissipated immediately from the IGBT chip, that’s why the ceramic circuit board stands out.

(Ceramic_pcb_with_DPC_technology)

In IGBT modules, ceramic PCBs are placed beneath the IGBT chip, or we can say the chip is assembled on the ceramic circuit board. The ceramic PCB connects and supports the chip, rapidly dissipating heat to the outer package. This method protects the chip from the adverse effects of heat.

Why ceramic PCBs Are Suitable for IGBT thermal dissipation?

Ceramic materials exhibit excellent thermal dissipation and electrical insulation properties. Unlike aluminum metal core PCBs, ceramic PCBs do not use insulation layers that hinder heat dissipation. In the manufacturing process of ceramic PCBs, copper foil is directly bonded to the ceramic substrate under high pressure and temperature (it depends on the different technology and different copper thickness). During PCB manufacturing, IGBT and other components are mounted on the circuit board through assembly technology.

Ceramic materials have extremely high insulation capabilities, enduring breakdown voltages up to 20KV/mm. At present, there are three ceramic materials that can be used for IGBT modules, they are 99% or 96% Alumina (Al₂O₃), Aluminum Nitride (AlN), and Silicon Nitride (Si₃N₄).

The thermal conductivity of alumina PCB is 15-35W/mK, aluminum nitride PCB is 170-230W/mK, and silicon nitride PCB is 80+W/mK. In contrast, aluminum core circuit boards only have a thermal conductivity of 1-12W/mK.

Applications of Ceramic PCBs in IGBT Packaging

Alumina PCBs are the most commonly used circuit boards in IGBT modules due to their lower cost. But if IGBT modules have higher power or precision requirements, AlN ceramic PCBs and Si3N4 PCBs are the most suitable choices. Because they have higher thermal dissipation and thermal expansion coefficients (CTE) close to semiconductors. Since different ceramic substrate has different features, the uses of ceramic PCB should depend on the specific requirements of IGBT modules.

In addition, with the development of Silicon Carbide (SiC) and Gallium Nitride (GaN) materials, they are starting to be used for IGBT chips due to their high-frequency, high-power, and high-temperature characteristics. Maybe in the future, aluminum nitride PCBs and silicon carbide PCBs will be increasingly applied to high-power IGBT modules in high-density three-dimensional packaging.

Common Properties of Using Ceramic Circuit Board

  • Excellent thermal conductivity and voltage resistance of ceramic substrates.
  • Copper trace layers has extremely high current-carrying capacity.
  • Strong adhesion and reliability between circuit layers and ceramic substrates.
  • Good soldering performance, suitable for wire bonding.
(Ceramic_PCB)

How to Solve the Overheat Issues in IGBT?

Though the ceramic PCB is good at heat dissipation, there still some overheat occasions happened if small power or long-time operation. Here we summarized some solutions for such issues.

1. Clean the heat sink to ensure tight contact between the IGBT and the heat sink.

2. Clean the fan, including the fan blades and lubricate the bearings if needed.

3. Clear the airflow path of the fan.

4. Replace with higher power IGBTs, ensuring the withstand voltage is not lower than the original IGBT’s value.

Above all are the information that we’d shared, welcome to contact us if you want to know more. Best Technology is a historic company which has over 17 years PCB manufacturing experience, here you can enjoy the one-stop ODM & OEM service, one-to-one after sales, quick delivery and high-quality products.

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What Are Differences of ENIG VS ENEPIG in PCB Manufacturing – Series 2

Tuesday, January 2nd, 2024

In our last blog, we simply introduced ENIG surface treatment in PCB manufacturing, and this time, we will share more information about the comparison of ENIG and ENEPIG.

What is ENEPIG Surface Treatment?

ENEPIG stands for Electroless Nickel Electroless Palladium Immersion Gold. This type of metal coating on the PCB pad surface consists of three layers—nickel, palladium, and gold. Apart from protecting the copper surface from corrosion and oxidation, the ENEPIG surface treatment is also suitable for high-density SMT (Surface Mount Technology) designs.

For its manufacturing process, manufacturers begin by activating the copper surface, followed by depositing a layer of electroless nickel, then a layer of electroless palladium, and finally, a layer of immersion gold. The process is somewhat similar to the one they follow in the ENIG process, but adding a palladium layer to the ENIG technology. The palladium layer not only improves the surface protection of the PCB, but also prevents nickel from deteriorating and inhibits interactions with the gold layer.

Pros of ENEPIG Surface Treatment

  • Reduce the black pad issues
  • Excellent solderability and high reflow soldering performance
  • Provide high-reliable wire bonding capability
  • High-density design available
  • Meet the miniaturization standards
  • Suitable for extra thin PCBs

Cons of ENEPIG Surface Treatment

  • Expensive than ENIG process
  • Thicker palladium layer will decrease the effective of SMT soldering
  • Longer wettability time

What are the Differences Between ENIG and ENEPIG?

The main difference between ENIG and ENEPIG is the palladium layer. This is the extra layer that added in ENEPIG process, which provides high oxidation resistance, enhance the electrical performance of the surface cleanliness and improve the abrasion resistance of the PCB surface. However, the palladium layer also increases the cost of manufacturing.

Additionally, the inconsistent surface cleanliness of ENIG, resulting from low solder joint reliability, particularly in gold wire bonding, is a concern. Extra procedures are also required to prevent nickel corrosion in ENIG. When considering it into manufacturing, the ENIG is well-suited for lower-end electronic products.

(ENIG_VS_ENEPIG)

The Considerations of Selecting ENIG or ENEPIG Surface Finishing

Though both two surface treatments offer excellent electrical performance and heat dissipation properties, there are still some conditions that need to consider when choose them.

  • Budget

Cost is an important factor when choose a suitable surface treatment. As we explain above, ENEPIG is expensive than ENIG, if you are trying to find a relative cost-effective coating, then ENIG is the best choice.

  • End-applications

The end-applications or finished products also determined the selection of surface finishing. For example, if your PCB will be used in high temperature applications, ENIG would be the better one since it can withstand high temperature.

  • Flatness

Many traditional surface finishes have poor flatness and smoothness, this brings the big challenge of small-size components mounted. Especially for those fine-pitch components like BGA, an uneven surface can result many problems. However, both ENIG and ENEPIG offer highly smooth surface finishes, forming thin and uniform layers on the solder pads.

  • Bonding demand

ENEPIG provides the optimal choice for wire bonding due to its highly smooth surface finish, which enhances wire bonding capabilities.

  • Environment-friendly

Some traditional surface treatments contain hazardous substances, making them non-compliant with RoHS requirements. Both ENIG and ENEPIG made by Best Technology are fully RoHS compliant and lead-free, so you are don’t worry about the environment unfriendly.

At the end, the choice between ENIG and ENEPIG surface treatments in PCB manufacturing involves a careful consideration of various factors. While both options offer excellent electrical performance, heat dissipation properties, and compliance with environmental standards like RoHS, specific project requirements and priorities will guide the decision-making process. If you are still confuse about the selection of surface treatment, welcome to contact with us, Best Team will give you a best solution that can meet your specific demands and save money for you.

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What Are Differences of ENIG VS ENEPIG in PCB Manufacturing – Series 1

Tuesday, January 2nd, 2024

Surface treatment also called surface finishing, it is a protective layer that through coating a layer of metal organic material on the surface of printing circuit boards (PCBs). Apply a layer of surface treatment enable to protect pads from scratches and oxidation, as well as improve the solderability of components mounting. ENIG and ENEPIG are the two common high-reliable surface finishing types in the circuit board manufacturing, they are not only for FR4-PCB, but also available in ceramic PCB, flex circuits and rigid-flex PCB. Today, Best Team would like to sharing information about ENIG and ENEPIG, and explore the differences between them.

(Assembled_PCB)

How to Select the Right Surface Treatment for Your PCB?

With the rapid development of electronics, there are various of PCB types that can be used in electronic devices, and at the same time, there are also increasingly more surface treatment technics available for selection. Until now, the common surface treatments are OSP, HASL, Immersion Silver, Gold Plating, ENIG and ENEPIG. Each of these surface treatments has its own advantages and disadvantages, so it is necessary to choose the most suitable one for a particular application. The selection of surface finish needs to take into account factors such as cost, application environment, fine-pitch components, the use of leaded or lead-free solder, operating frequency, shelf life, drop and impact resistance, volume and throughput, as well as thermal resistance.

With PCBs trending towards micro-vias and finer traces, and the drawbacks of HASL and OSP, such as flatness and flux elimination issues, becoming more pronounced, the demand for surface treatments like ENIG continues to grow. In addition, black pad is a major weakness of ENIG while ENEPIG enable to solve it very well, making it a preferred choice for those PCBs need to wire bonding.

What is the ENIG Surface Treatment?

ENIG, its full name is Electroless Nickel Immersion Gold, is also known as chemical gold or immersion gold in the electronics industry. This type of surface treatment provides two metal layers—gold and nickel—that manufacturers deposit them on the surface of PCB pads sequentially. This surface finish is a selective surface finish, meaning that certain specific pads may have ENIG surface finish, while others may have different types, such as OSP, HASL, or immersion tin. Here are the main processes of the ENIG coating:

  • Copper activation

In this step, manufacturers will active the copper layer through cleaning process, this way can help to remove the dust and oxides residual on the surface, but also remove any gases or air trapped in the perforations (holes) of the PCB by wetting the surface. Next, micro-etching the PCB surface using substances like hydrogen peroxide or sulfuric acid.

  • Electroless nickel

This process is to coat a layer of nickel on the active copper layer by electroplating. The nickel layer serves as a protective layer or inhibitor, which prevent the copper reactive with other elements.

  • Immersion gold

Immersion gold is the last step of whole ENIG process, immersing the PCB into a mixture, oxidizing the nickel surface, generating nickel ions, and then reducing gold from the mixture. The reduced gold forms a metallic coating to protect the nickel surface. This is the whole process of coating ENIG surface treatment.

(PCB_with_ENIG_surface_treatment)

Advantages of ENIG

  • Surface flatness – good for fine-pitch and small size components like BGA.
  • Suitable for press-fit components since it provides a reliable connection for electrical testing.
  • Suitable for wire bonding and gold-fingers connectors.
  • Cost-effective compared with ENEPIG

Disadvantages of ENIG

  • Black pad issues.
  • Varied coating thickness because of the uncontrolled nickel plated and immersion gold.
  • Poor wettability during PCB assembly.

All in all, ENIG is a good option if you want to mount fine-pitch components on the PCB surface or if you are considering its use in plug-and-pull devices such as WIFI interfaces. In our next blog, we will introduce ENEPIG surface treatment, including its pros & cons and the differences between ENIG and ENEPIG. Pay attention to our news or contact us directly if you want to know more.

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Do You Know How Does the ENEPIG Working for Wire Bonding Circuit Boards?

Friday, November 10th, 2023

The electronics industry has continuously pursued smaller and faster electronic products with increased functionality. To meet these demands, the electronic packaging industry has focused on developing more advanced packaging methods, aiming to increase the density of components on a circuit board while integrating multiple functions into a densely package.

The increasing density of packaging and interconnection has driven the progression of assembly methods from through-hole technology (THT) to surface-mount technology (SMT). Additionally, the use of wire bonding to connect chips to substrates has become more prevalent. The adoption of smaller interconnect pitches and chip-scale packaging (CSP) has further increased component density, while multi-chip modules (MCM) and system-in-package (SiP) have enabled the integration of more functions on a single package.

This post describes the key factors affecting the reliability of interconnections, with a particular focus on the specific properties of surface-treated wire bonding, emphasizing the selection of wire bonding surface treatments.

Selection of Surface Treatment for Wire Bonding

While electroless nickel gold provides excellent performance for wire bonding, it has three main drawbacks that hinder its application in cutting-edge technologies:

1. The relatively high demand for gold layer thickness leads to lengthy process costs.

2. Thick gold layers are prone to the formation of weak tin-gold intermetallic compounds (IMC), reducing the reliability of solder joints. To enhance solder joint reliability, alternative surface treatments may be used, but this increases additional process costs.

3. The electroplating process requires the use of electroplating lines, limiting the design freedom and wiring density of the packaging substrate.

The limitations posed by electroplated nickel-gold provide an opportunity for the adoption of chemical plating. The techniques of chemical plating include Electroless Nickel Immersion Gold (ENIG), Electroless Nickel Electroless Gold (ENEG), and Electroless Nickel Palladium Immersion Gold (ENEPIG).

Among these three options, ENIG is generally unproblematic due to its lack of high reliability in gold wire bonding properties (although it has been used in some low-end consumer products). On the other hand, ENEG shares the high production cost and presents complex challenges in terms of the manufacturing process, similar to electroplated nickel-gold.

ENEPIG was initially introduced in the late 1990s, its market acceptance was delayed until around the year 2000 due to fluctuations in palladium metal prices (which were inflated to unreasonable levels around 2000). However, ENEPIG can meet the requirements of many new packaging applications, providing reliable performance and conform to lead-free/ROHS requirements, with a recent strong surge in market demand.

In addition to the advantages in packaging reliability, the cost of ENEPIG is another benefit. With the recent rise in gold prices surpassing US$800/oz, it becomes challenging to control costs for electronic products requiring thick gold plating. The price of palladium (US$300/oz), relative to gold, is less than half, making palladium a cost-effective alternative with surface-related advantages.

Comparison of Surface Treatments

Up to now, for printed circuit boards accommodating fine-pitch QFP/BGA components, there are primarily four lead-free surface treatments:

Immersion Tin (IT)

Immersion Silver (IAg)

Organic Solderability Preservatives (OSP)

Electroless Nickel Immersion Gold (ENIG)

The table below compares these four surface treatments with ENEPIG. Among these surface treatments, none can simultaneously meet all the requirements of lead-free assembly processes, especially when considering multiple reflow experiences, pre-assembly shelf life, and gold wire bonding experiences. In contrast, ENEPIG offers good shelf life, solder joint reliability, gold wire bonding capability, and can serve as a touch button surface, providing surface-related advantages. Moreover, in the final gold replacement deposition reaction, the chemical palladium layer in ENEPIG works to protect the nickel layer, avoiding excessive corrosion during gold replacement.

(Table 1 – Comparison_of_Different_Surface_Treatment_Performances)

What Are Advantages of ENEPIG?

ENEPIG has several crucial advantages, demonstrating reliable solderability and gold wire bonding concurrently. The key benefits are outlined as follows:

  • Prevention of “Black Nickel Problem” – The absence of gold replacement attacking nickel on the surface prevents interfacial corrosion.
  • The chemical palladium layer acts as a barrier, preventing copper from diffusing to the surface, ensuring satisfactory solderability.
  • Palladium layer enable to completely dissolves in the solder, preventing the exposure of a high-phosphorus layer at the alloy interface. After the dissolution of the chemical palladium layer, the chemical nickel layer is revealed, forming a satisfactory nickel-tin alloy.
  • Capability to Withstand Multiple Lead-Free Reflow Cycles
  • Excellent Gold Wire Bonding Properties

These advantages make ENEPIG a preferred choice in various applications, ensuring reliable performance in both soldering and wire bonding processes while offering cost efficiency. As a one-stop PCB supplier in Asia, Best Technology possesses advanced technology and high-tech manufacturing equipment that can meet the “multi-variety, small volume, high quality, strong capability, short delivery” requirements. Welcome to contact us if you are going to find a reliable circuit board manufacturer.

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How Can I Reduce and Optimize the Cost of My PCB in A Best Way? – Series 2

Saturday, October 28th, 2023

At our latest blog, may the readers have understood the factors that will affect the PCB price, or maybe one of your have put it into practice that get a price lower than your budget. However, people are always not satisfied by the existing situation. If this is bother you as well, keep reading since this time we are going to sharing some useful tips that enable to optimize your PCB price until to the best.

  • Reduce board complexity

It can be said that try to simplest your design/layout and make it easy to fabricate is the simplest way to reduce your PCB cost. The more complex and irregular the forms, the higher the cost. Just remember: for every circuit board, no need to maintain a fancy diagram to demonstrate its excellence, perform functionality correctly is enough.

  • Design it in right size and thickness

Design your board in right size doesn’t means make it smaller as possible. You must know, if your design is complex and layouts are density, that means maker need to spend more time to assemble them. Highly compact sizes are always expensive, don’t skimp when it counts. Otherwise, more money will be spent to afford what you saved.

And in theory, the more layers and thickness the board, the more cost that manufacturer spend. Numerous layers in the PCB will have an influence for holes and diameters. It is recommended that if thinner thickness is enough, then just do it. 

  • Shapes, holes and rings should be regularly

Normally, keep the PCB as square or rectangular shapes is cheaper than irregular shapes like pentagon.  And large holes and rings enable to smooth the production run and easy to create. For smaller holes and rings means the driller must be smaller and delicate control.

  • Consider volume and choose manufacturer

In our last blog, we emphasize manufacturers will set a minimum order quantity (MOQ), it is common in this industry. So, consider your volume and check multiple quantities before ordering can help to recognize which one is the most cost-effective.

During the evaluation period, talk to your suppliers as soon as possible, knowing more about the material specifications, technical and PCB tolerances. A wrong choice will lead to much time waste and some unnecessary cost. This is we call “trial and error cost”. Try to make all things are clear and correct before production.

  • Pick the best vias

There are totally three types of vias in PCB: though-hole, blind, buried. The through hole can be passed through the whole board, while blind vias is created from top or bottom side to the middle of the board without through to bottom or top side. Buried vias, just as its names, it is buried inside the boards and we can’t see it by naked eyes.

Obviously, through hole is cost performance than other two vias, try to use more instead of blind or buried vias enable to decrease your cost. In additionally, blind and buried vias are always necessary in HDI PCB and RF board, otherwise, you don’t usually use them.

  • Make sure all SMT components on the one side

Trying to make all the surface mounted (SMT) components on the one side of circuit board if possible. In this way, assembler can finish the SMT process in one-time, so that can save much manufacturing time and cost. But if the components are distributed on both sides, it is needed to assemble two times, that is top side first – bottom side second (or sometimes bottom first).

  • Select easily replaceable component parts

It is assumed that one of part on your circuit becomes obsolete, then you must search for replaceable part or update your design if you would like to continuedly use this board. As an extensive experienced PCB manufacturer, we strongly recommend that select components that has standard dimension, so that it is easy to match alternative one.

In addition, visit some manufacturer’s website carefully to see if any components are marked as “obsolete” or “not recommended for new designs” before finishing your design. This enables to avoid secondary update.

  • Follow manufacturer’s PCB fabricate standards

Understand and follow manufacturer’s fabricate standards can keep your unit PCB price in a relative lower cost. When designing a new project, please make sure to following below tips.

  1. Use standard stack-up with standard materials.
  2. Design 2-4 layers PCB if possible.
  3. Keep your minimum line width and spacing within the standard spacing.
  4. Avoid adding extra special requirements as much as possible.
  • Use SMT components as possible

Choose surface mounted (SMT) components instead of through hole (THT) component whenever possible. SMT and THT are almost treated as separated manufacturing processes. Hence, if all the THT components can be replaced by mounted parts, the THT process will be eliminated completely. It is not only decreasing the manufacturing cost, but also reducing delivery time. Of course, it is not always possible, but it’s worth trying.  

Whatever decisions you make, the best solution is to consult and discuss with your suppliers. They be always to give you the best one that can save your money and meet your requirements as well. Meanwhile, if you don’t believe the suppliers, you are welcome to reach us. We promise that we can give you a most favorable price and high-quality product.

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