PCB & MCPCB - Best Technology

5 Tips Tell You How to Solder BGA Better in PCBA

May 29th, 2023

BGA (Ball Grid Array) soldering is a widely used method in the electronics manufacturing industry for mounting integrated circuits onto printed circuit boards (PCBs). This method provides a more compact and reliable connection compared to traditional through-hole or surface mount technology (SMT). However, the complexity of BGA soldering poses various obstacles during the manufacturing process. Herein, we will explore the challenges faced in BGA soldering and discuss effective strategies to address them.

What is BGA Soldering?

BGA soldering is a technique that involves the attachment of integrated circuit packages to a PCB using an array of solder balls. These solder balls are typically made of lead-based or lead-free alloys, depending on environmental regulations and specific requirements. The BGA package consists of a substrate, which acts as a carrier for the integrated circuit, and the solder balls that form the electrical and mechanical connections between the package and the PCB.

The Importance of BGA Soldering in Electronics Manufacturing

BGA soldering plays a critical role in the manufacturing of various electronic devices such as computers, smartphones, and gaming consoles. The increased demand for smaller and more powerful electronics has driven the adoption of BGA packages. Their compact size and high pin density make them suitable for advanced applications where space is limited.

Challenges Faced in BGA Soldering

Component Alignment and Placement

One of the primary challenges in BGA soldering is ensuring accurate component alignment and placement on the PCB. The small size of the solder balls and the dense layout of the BGA package make it difficult to achieve precise positioning. Misalignment during the assembly process can result in solder bridges, open connections, or mechanical stress on the package.

To address this challenge, manufacturers employ advanced technologies such as Automated Optical Inspection (AOI) and X-ray Inspection. AOI systems use cameras and image processing algorithms to verify the correct alignment and placement of BGA components. X-ray inspection, on the other hand, allows manufacturers to see beneath the surface of the PCB and detect any misalignment or defects that may not be visible to the naked eye.

Solder Paste Application

Another significant challenge in BGA soldering is achieving precise and consistent solder paste application. Solder paste, a mixture of solder alloy and flux, is applied to the PCB pads before placing the BGA package. Inadequate or excessive solder paste can lead to solder defects such as insufficient solder joints, solder voids, or solder bridging.

To overcome this challenge, careful attention must be given to stencil design and aperture selection. Stencils with appropriate thickness and properly sized apertures ensure accurate solder paste deposition. Additionally, manufacturers can employ Solder Paste Inspection (SPI) systems to verify the quality and consistency of the solder paste applied. The solder paste that Best Technology uses is SAC305 solder paste.

Temperature Profiling

Temperature profiling, or we can say the thermal management, it is crucial in BGA soldering to ensure proper reflow of the solder paste. The reflow process involves subjecting the PCB to a carefully controlled temperature profile, allowing the solder paste to melt, form a reliable joint, and solidify. Inadequate temperature profiling can lead to insufficient solder wetting, incomplete reflow, or thermal damage to components.

Manufacturers must optimize the reflow oven setup and calibration to achieve the correct temperature profile. Thermal profiling techniques, such as the use of thermocouples and data loggers, help monitor and control the temperature during the reflow process.

Reflow Process

The reflow process itself presents challenges in BGA soldering. The soak zone, ramp rates, and peak temperature must be carefully controlled to prevent thermal stress on the components and ensure proper solder reflow. Inadequate temperature control or improper ramp rates can result in solder defects such as tombstoning, component warpage, or voids in the solder joints.

Manufacturers need to consider the specific requirements of the BGA package and follow recommended reflow profiles provided by component suppliers. Proper cooling after reflow is also essential to prevent thermal shock and ensure the stability of the solder joints.

Inspection and Quality Control

Inspection and quality control are critical aspects of BGA soldering to ensure the reliability and performance of the solder joints. Automated Optical Inspection (AOI) systems and X-ray inspection are commonly used to detect defects such as misalignment, insufficient solder wetting, solder bridging, or voids in the solder joints.

In addition to visual inspection techniques, some manufacturers may perform cross-section analysis, where a sample solder joint is cut and examined under a microscope. This analysis provides valuable information about the quality of the solder joint, such as solder wetting, void formation, or the presence of intermetallic compounds.

In a word, BGA soldering presents unique challenges in electronics manufacturing, primarily related to various factors. By addressing these challenges effectively, manufacturers can ensure the reliability and performance of BGA solder joints, contributing to the production of high-quality electronic devices. Best Technology has rich experience in PCBA assembly and we mounted thousands PCBs for our customers, whatever it is simple design or complex design, all the products are assemble perfect and work well in customer side. Please feel free to contact us for any questions about PCBA.

Tags: BGA, BGS SOLDERING
Posted in best pcb, bestpcb, Design Guide, FR4 PCB, PCB News, PCB Technology, PCBA, SMT Technology | No Comments »

Key Challenges in Solder Mask Printing for Heavy Copper PCBs

May 23rd, 2023

As the demand for higher power and miniaturization of electronics increases, so does the need for Heavy Copper Printed Circuit Boards (PCBs). From our last blog – Why choose Heavy Copper PCB for your High Current Project, we know the heavy copper PCBs are defined as those with copper thicknesses greater than 3 oz. These PCBs are designed to withstand high current and thermal loads, making them suitable for power electronics applications. However, the increased copper thickness also poses challenges during the solder mask printing process.

(16_layers_heavy_copper_PCB_with_10oz_each_layer)

Understanding solder mask

Solder mask (short for S/M in the industry) is a protective coating applied to PCBs to prevent solder bridges and improve solder joint quality. The solder mask is coated to the PCB surface using a screen-printing process, where the desired pattern is created using a stencil and the solder mask ink is then deposited onto the PCB. The ink is then cured, either through heat baking or UV light, to form a solid coating.

There are several types of solder mask materials available, including epoxy, acrylic, and liquid photo imageable (LPI) solder mask. Each type has its advantages and disadvantages, depending on the application requirements.

The benefits of using solder mask in PCB manufacturing include increased reliability, improved solderability, and reduced risk of short circuits and corrosion. The solder mask we usually use is Taiyo, which has high reliability and excellent heat resistance.

Challenges in solder mask printing of heavy copper PCBs

While solder mask printing is a critical step in PCB manufacturing, the increased copper thickness in heavy copper PCBs presents several challenges for printing process as I mentioned before. It’s difficult to apply enough solder mask to cover thick copper pattern and base material with severe height difference.

1. The high copper thickness and thermal conductivity of heavy copper PCBs make it difficult for the solder mask ink to adhere properly to the surface. This can result in insufficient coverage and registration accuracy, which can affect the overall quality and reliability of the PCB.

2. The high copper thickness can cause stress on the solder mask, leading to mask cracking and peeling. The navigation mark on the substrate has specific ink thickness requirements due to limitations in the ink thickness that can be applied to the substrate. If the ink thickness on the substrate is too thick, it may result in solder resist cracks in the substrate position after the printed circuit board is soldered. This can occur during reflow soldering or thermal cycling, resulting in poor solder joint quality and reduced reliability.

3. The thick solder mask is also more difficult to exposure and develop. If the exposure energy is too weak or not enough, then some undercut problem may happen.

How to overcome this challenge?

To address these challenges, it is essential to choose the right solder mask materials and optimize the application process.

Choosing the right solder mask materials is crucial for ensuring proper adhesion and coverage on heavy copper PCBs. LPI solder mask is often preferred for heavy copper PCBs due to its excellent adhesion and thermal stability. However, epoxy and acrylic solder mask materials can also be used with proper surface preparation.

Optimizing the solder mask application process can also help address the challenges of heavy copper PCBs. This can include using a thinner stencil for improved registration accuracy and applying multiple coats of solder mask for better coverage. Advanced solder mask technology, such as laser direct imaging (LDI), can also help improve registration accuracy and reduce the risk of mask cracking and peeling.

Optimizing the printing process, now in Best Technology, we always make the substrate first, fill the substrate with the solder mask and then treat it as a normal PCB for normal printing solder mask.

If you are in the process of designing a complex multi-layer heavy copper PCB and are looking for a high-quality and experienced manufacturer, feel free to reach out to us at sales@bestpcbs.com, Best Technology can support you by OEM and ODM service to ensure your design is cost-effective and can be easily manufactured.

Tags: heavy copper pcb, solder mask
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Why choose Heavy Copper PCB for your High Current Project?

May 16th, 2023

In the world of electronics, printed circuit boards (PCBs) play a vital role in connecting and powering various components. They are the backbone of every electronic device, from smartphones to industrial machinery. When it comes to designing a PCB for a project, the thickness of the copper layer is an important consideration. Heavy Copper PCB, also known as Thick Copper PCB, has become increasingly popular in charging automotives due to their unique features and benefits. In this article, we will discuss why consider heavy copper PCBs for your high current project.

What a Heavy Copper PCB is?

A heavy copper PCB is a circuit board with an unusually thick copper layer, usually exceeding 3 ounces per square foot (oz/ft²). By comparison, standard PCBs typically have a copper layer thickness of 1 oz/ft². Heavy copper PCBs are used in applications where high current is needed, or the board needs to withstand mechanical and thermal stress.

Benefits of Heavy Copper PCBs

High Current Capacity

The thicker copper layer in a heavy copper PCB allows for a higher current capacity. This makes it ideal for high-power applications such as power supplies, motor controllers, and industrial equipment. Heavy copper PCBs can carry up to 20 amps or more, compared to the standard 5-10 amps of a regular PCB.

Thermal Management

Heavy copper PCBs are known for their excellent thermal management capabilities. The thicker copper layer allows for better heat dissipation, reducing the risk of overheating and component failure. So that they can generate a lot of heat for the end-application.

Durability

Heavy copper PCBs are more robust and durable than standard PCBs. The thicker copper layer provides better mechanical support, making them resistant to damage from vibration, shock, and bending. This makes them suitable for harsh environments and industrial applications.

Increased Flexibility

Heavy copper PCBs offer increased design flexibility compared to standard PCBs. The thicker copper layer allows for more complex and compact designs, reducing the overall size of the board. This makes them ideal for applications where space is limited, that means you can make a very heavy copper while the size is very small.

Better Signal Integrity

The thicker copper layer in heavy copper PCBs provides better signal integrity. This reduces the risk of signal loss and interference, resulting in more reliable and efficient circuit performance.

Copper thickness design for a Heavy Copper PCB?

Due to the thickness of copper in heavy copper PCB is thick then normal FR4 PCB, then it is easily to be warped if the copper thickness is not match each other in symmetrical layers. For example, if you are designing an 8 layers heavy copper PCB, then the copper thickness in each layer should follow L8=L1, L7=L2, L6=L3, L5=L4 standard.

Additionally, the relationship between minimum line space and minimum line width also should be considered, follow the design rule will help to smooth production and shorten the lead time. Below are the design rules between them, LS refers to line space and LW refers to line width.

Drill hole rules for heavy copper board

A plated through hole (PTH) in printed circuit board is to connect top and bottom side to make them electricity. And when the PCB design has multi copper layers, the parameters of holes must be considered carefully, especially hole diameters.

In Best Technology, the minimum PTH diameter should be >=0.3mm while the copper ring annular should be 0.15mm at least. For wall copper thickness of PTH, 20um-25um as default, and maximum 2-5OZ (50-100um).

(16L_heavy_copper_PCB_with_35um_copper_in_via_holes)

Basic parameters of Heavy Copper PCB

Here are some basic parameters of heavy copper PCB, hope this can help you to understand Best Technology’s capability better.

Base material: FR4
Copper thickness: 4 OZ~30 OZ
Extreme Heavy Copper: 20~200 OZ
Outline: Routing, punching, V-Cut
Solder mask: White/Black/Blue/Green/Red Oil (Solder mask printing is not easy in heavy copper PCB.)
Surface finishing: Immersion Gold, HASL, OSP
Max Panel size: 580*480mm (22.8″*18.9″)

Applications of Heavy Copper PCBs

Heavy copper PCBs are used in a variety of applications, including:

Power supplies
Motor controllers
Industrial machinery
Automotive electronics
Aerospace and defense systems
Solar inverters
LED lighting

(Heavy_copper_PCB_for_high_power_supply)

Choosing the right PCB thickness is crucial for the success of any project. Heavy copper PCBs offer unique features and benefits that make them ideal for high-power and high-temperature applications. If you want to ensure the reliability and performance of your project, consider using heavy copper PCBs. Best Technology has more than 16 years manufacturing experience in heavy copper PCBs, so we are so confident that we can be your most reliable supplier in China. Welcome to contact us at any time for any questions or any queries about PCBs.

Tags: heavy copper pcb
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5 PCB Testing details to make your PCB no more quality issues

April 24th, 2023

As we all know, it is very important to get a well-functional PCB from the PCB manufacturers. A well functional PCB means that the electricity testing has been performed well at the PCB manufacturer end. However, you may have found some PCB you purchased are with some electricity issues like short & open circuits, or some visual issues like solder pad missing., etc.

Do you know how this issue come while the PCB testing process?

According to the feedback come from the customers, here we summarized some improper ways during the PCB Electricity testing process which may lead to the PCB fail to the test.

Here are some major points for your reference:

Incorrect direction when placing PCB board on testing worktop, the force on probes will cause indentation on boards.

PCB manufacturers don’t regularly maintain their testing jig, causing some malfunctions on testing jig can’t be found in time. Take the counter for example, if we do not find the counter’s fixing screw loose in time, it will cause the counter to fail to read the caliper scale. Of course, it also could be the counter is dysfunctional sometimes.

PCB manufacturers don’t regularly check/change the testing probes. Dirt on the testing probe cause testing results is inaccurate.

PCB testing operator don’t distinguish functional board from NG board due to unclear placement area.

So, if the circuit boards testing work under above improper way, do you know what effects will be on your products?

Base on some lessons learned from our customers, you may get following influences caused by improper way of the PCB testing.

Increase your quality issues

The low testing accuracy will make the functional PCB mixing together with the defective PCB. If the PCB testing defects can’t be found in time before PCB assembly, defective products will flow into the market, which will seriously increase the quality risk hidden on the end products.

Delay your Progress

After defective PCBs are found, repairing will greatly delay the progress of the project.

Increase your overall cost

The defective PCB will cost many people and time to check and follow, this will directly to increase the overall cost of the projects.

We know deeply that poor testing will bring serious consequences for customers, so with more than 16 years experiences on Printed Circuits Board fabrication, Best Technology has rich experiences on PCB electric testing managements, and following are some of our management solutions to control our PCB testing process:

1. We execute strictly the pre-job training 3 months in advance for the testing operator, and all the testing will be operated by the professional and experienced testers.

2. Maintain or replace the test equipment every 3 months, and use a brush to clean the tester in a regular period or replace the pin cable head to make sure there is no contaminate at the test probe.

3. Add the extra tooling hole at rails for fix purpose to make sure the placement of PCB orientation is no mistake during testing process.

4. The testing workshop must be divided clearly for the qualified board and NG board, the location to keep NG board will be marked with red line.

5. The testing process must be strictly followed with our internal PCB testing standard operating procedure.

With the help from above management solutions for the PCB E-Testing during the PCB manufacturing process, the PCB we send to customers works very well, which also make sure their products can be assembled well and deliver well in the markets. For us, more and more kindly feedback regarding the functional feedback comes from our customers, here are some good feedback from customers for your reference.

If you have any questions about PCB testing or PCB manufacturing, please feel your freely to leave your message or contact us. In our next update, we will share which test methods are used in the during the PCB Assembly.

Tags: PCB quality, PCB test
Posted in best pcb, bestpcb, PCB News, PCBA | No Comments »

Can I Design Via Holes in Thick Film Ceramic Boards?

April 18th, 2023

May some engineers or designers who be interested in thick film ceramic circuit are curious about can thick film ceramic boards design with via holes like FR4 PCB? Herein, we will explore the feasibility of using thick film ceramic boards for via holes, including the materials and processes involved, as well as the advantages of this approach.

What is thick film ceramic board?

The “Thick Film” refers to the thickness of conductor layer on a Ceramic PCB. Normally the thickness will be at least 10um, around 10~13um, which is thicker than spurting technology in Thin Film Ceramic PCB. And of course thickness is less than DCB Ceramic board or FR4 board.

Thick film ceramic circuit enables to put resistor, electric capacitor, conductor, semi-conductor, and interchangeable conductor on ceramic board, after manufacturing steps of printing and high temperature sintering. The more important thing is by using thick film technology, we can make all the resistors with the same value, or different value for different resistor on the same board.

Materials and processes for via holes

In general, thick film ceramic circuit is not suitable for designing via holes. Because the characteristics of thick film ceramic board mainly depends on the insulation properties of its ceramic substrate, rather than conductive properties. The conductivity of thick film ceramic plate is not good than Metal Core PCB, or even we can say it has a very poor conductivity, usually can’t meet the requirements of the via hole.

But, designing via holes in thick film ceramics is available in Best Technology. Generally speaking, the fabrication of via holes in thick film ceramic boards typically involves several key materials and processes.

From the designer’s perspective, a conductive material is used to create a continuous conductive path from one side of the ceramic board to the other. Common conductive materials include gold paste, silver paste, and copper paste. These materials are usually screen printed onto the ceramic board in the desired pattern, and then fired at high temperatures to achieve sintering and form a conductive layer.

Once the conductive layer is formed, the via holes are created by drilling or punching small holes through the ceramic board at the desired locations. These holes are then filled with a conductive material, such as silver paste or copper paste, to establish electrical connections between the different layers of the circuit.

Finally, the via holes are fired again at high temperatures to achieve sintering and ensure good adhesion and electrical performance.

Advantages of Via Holes in Thick Film Ceramic Boards

These via holes offer several advantages in the design and fabrication of thick film ceramic boards, including as following:

Electrical connectivity

Via holes provide electrical connectivity between different layers of a thick film ceramic board. They allow for the interconnection of different circuitry or conductive layers, enabling the flow of electrical signals or power between different parts of the board. This allows for complex and multi-layered circuit designs, which can be highly beneficial in applications that require intricate circuitry or high-density interconnects.

Space-saving

Via holes can provide a means of vertical interconnection, allowing for more efficient use of board real estate. Instead of routing traces or conductors on the surface of the board, which can take up valuable space, via holes can be used to route connections through the board, freeing up surface area for other components or functions. This is especially advantageous in compact or miniaturized electronic devices where space is limited.

Thermal management

Via holes can aid in thermal management in thick film ceramics. They can be used to transfer heat from one layer of the board to another, helping to dissipate heat generated by components or circuits. This can be particularly important in high-power or high-heat applications, where efficient thermal management is crucial for preventing overheating and ensuring reliable performance.

Mechanical stability

Via holes provide additional support and reinforcement to the board, reducing the risk of warping, bending, or cracking. Via holes can also help improve the overall mechanical integrity of the board by reducing stress concentration points and enhancing its structural rigidity.

Design flexibility

Via holes offer design flexibility in thick film ceramic boards. They can be designed and placed according to the specific requirements of the circuit or system, allowing for customized and optimized designs. Via holes can be used to route traces, create vias for component mounting, or provide grounding or shielding, among other functionalities. This flexibility in design allows for more efficient and effective circuit layouts, which can lead to improved performance and reliability.

As previously mentioned, designing via holes in thick film ceramic boards offers various benefits. However, when it comes to choosing the appropriate paste for via holes, silver paste is often recommended to our customers. But why is that? Can I use gold or copper? In our upcoming article, we will delve into the reasons behind this recommendation and provide you with valuable insights. Stay tuned to uncover the answers!

Tags: ceramic PCB
Posted in bestpcb, Ceramic PCB, Design Guide, FAQ | No Comments »

10 Tips to Reduce the manufacturing cost of Printed Circuit Board

March 23rd, 2023

Many times, when PCB engineer or purchaser seek for a PCB manufacturer to make circuit boards, that always think the price is too high, but don’t know where makes the price is so high and how to optimize the cost on the premise of ensuring the quality of the circuit board. Herein, we share a very useful guideline about “Ten tips to reduce the PCB manufacturing cost”, welcome to read on!

Substrate

Different brands of substrate have different price. For a simple example, if you require a multi-layer PCB, Tg should greater than 150^o, and PP need to over 0.20mm, then use GDM will cheaper than KB or SL. But GDM is usually used for making single or double-sided PCB, it is not recommended to make multi-layer circuit board. If you need to fabricate an 8 layers of multi-layer PCB, KB Tg170 is ideal for your choice since it has good performance and relatively cost-efficient.

Solder mask oil

In generally, what we should consider about the solder mask (S/M) are color and brand.

For the solder mask color, the most commonly used are green, white and black, if you would like to choose other special colors such as blue, yellow, gray, the price will be a little more costly.

From the brand aspect, currently the best brand is Taiyo solder mask, because it has high viscosity, stable dielectric constant, good insulation and oxidation resistance properties, but it is more expensive than others. Other brands of solder mask oil will be relatively cheap, but the quality is not particularly stable and can’t be guaranteed. So if the circuit boards need to used on bulk products, we recommend to use Taiyo to get a stable quality.

Printing film

If it is a bulk order with simple design and trace width/space >= 5/5mil, almost manufacturers will use printing film to generate traces. But please remember: the larger the board size, the higher cost of film. (Generally speaking, Prototypes or small orders are use LDI exposure machine to generate the trace, but for mass production, manufacturer will priority choose film and then use LDI.)

Line width/space

The thinner traces, the higher manufacturing price. Because the line is thinner, the accuracy of the equipment and the quality of the chemical solution are required to be relatively high, and the yield will be relatively low, resulting in higher costs. Each manufacturer has its capability, so choose a suitable supplier is most important, view Best’s website to check our capability.

Drill holes

The smaller the hole, the higher the price, the diameter of less than 0.3mm will increase the price. The more holes there are, the higher the price will be. Other special holes will also increase the cost, such as half holes, blind holes, PTH holes larger than 6.0mm, etc. Because the hole is small, only one board can be drilled at a time when drilling the hole on PCB material, which is low efficiency and the possibility of drilling a broken drill bitter is also large, resulting in higher cost.

Finished copper thickness

Finished copper thickness ≥2oz, and hole copper >25μm board will increase the cost. Because the price of copper itself is relatively expensive, the thicker the copper, the higher the price, coupled with the cost of additional electric copper, leads to the overall price rise.

Finished board thickness

There is little difference in the price of PCB with board thickness of 1.2mm and 1.6mm, but if the board thickness is 2.0mm or even thicker, its cost will increase correspondingly. The thicker the board, the more sheets of fiberglass, so the cost will increase accordingly.

Outline

If there are more slots, and the slots are less than 1.0mm, the cost will increase. This is because the gong groove of the board is more shaped, resulting in the processing time is elongated. In addition, if the width of the groove is small, processing can not be too fast, easy to break the milling cutter, so the processing efficiency is low, the natural production cost increases.

Surface treatment

Our common surface treatment processes are: OSP(antioxidant), lead HASL, lead-free HASL (environmental protection), gold plating, immersion gold, ENEPIG and some combination processes. The price of the above process is more expensive in turns, that is, OSP (antioxidant) < lead HASL < lead free HASL < gold plating < immersion gold < ENEPIG.

Tooling fee and testing fee

Tooling fee: in generally most of manufacturers use milling cutter to punch outline if this is a prototype order or small order. But if bulk order, it is needed to use a tooling jig, so there is a tooling fee need to pay.

Testing fee: flying probe tester is usually for small order, mass production need to use testing jig, and there is a different testing fee for both.

Above elements can affect the cost of making a board, you can try to follow those guidelines if you have a limited budget. Or if you want to know a exactly cost, please send RFQ to Best Technology, our sales will give you a best price.

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Why Consider Even-Number Multi-Layer PCBs For Your Project?

March 7th, 2023

With the great demands about high-tech electronic equipment, although the single sided PCB or double-sided printed circuit boards have their advantages, multi-layer designs are more beneficial for some applications, that’s why the more and more popular and wide usage of multi-layer PCBs.

Currently in the market and electronic industry, almost of the multi-layer PCB have an even number of layers such as 8, 10 or 12 layers, why designers didn’t consider an odd-number layers? Today let’s explore the reasons together.

Higher cost spent

Normally the standard layers of a multi-layer PCB in the industry are even-numbers, and as the manufacturing technology becomes more and more mature, the cost of fabricating a multi-layer PCB is relative competitive.

But if you want to produce odd-numbers PCB, may the odd-number layers save the cost of material for one layer but the processing cost increase significantly to an even-numbers. Because the core structure requirement for odd layered PCB increases the production cost greatly. However, an even layered PCB can save these costs and reduce the overall manufacturing cost, so why not consider the even number layers?

Long lead time

Long delivery time is unescapable because of the immature fabricating technology. In particular with the odd-layer, the stack up will be unbalance. For example, if it’s an odd layered circuitry, due to the standard symmetrical requirement, the layers will be separated to 2 layers in a one side and another side is 3 layers, so one of the copper layers will be etched away and the odd layered PCB may create uneven weight during the copper plating stage and result in irregular plating issues. This non-standard, odd-layered stack requires an extra core process for layer bonding and adds to the manufacturing time and cost. So, it’s always recommended to use an even number of layers in the PCB stack-up.

Potential quality issue

Quality is very important and crucial for end-application, and the best reason of why not design an odd-number multi-layer PCB is the odd-number layers PCB is very easy to get twist due to the unbalance copper layers. When the PCB is cooled after the multi-layer circuit bonding process, the different lamination tension between the core structure and the foil structure can cause the PCB to bend when cooled. As the board thickness increases, the risk of bending becomes greater for composite PCBs with two different structures. The key to eliminate circuit board bending is to use balanced layering. Although PCBs with a certain degree of bending meet the specification requirements, subsequent processing efficiency will be reduced, resulting in increased costs. Because assembly requires special equipment and technology, the accuracy of component placement is reduced, so the quality will be damaged.

In addition, the twist of an even-number layers PCB can be controlled below 0.7% (IPC 600 standard), but odd layers unable to reach to this quality standard. What’s more, when the warpage of a circuit board greater than 0.7% will seriously affect the operation of Surface Mounted Technology (SMT) process and the reliability of the whole product. Therefore, the designers do not design odd layer generally, even if the odd layer enables to achieve the function, will be designed into false even layer, that is, 5 layers designed into 6 layers, 7 layers designed into 8 layers of board.

Anyway, more layers it is, more complex & difficult the manufacturing will be, and more expensive the cost will be, and the lead time of multi-layer PCB also is different from normal one. So you must choose a right supplier who can provide One-stop service include designing, evaluating, manufacturing or even repairing. Best Technology is an expert in the production of multi-layer PCBs for many companies around the world for over 16 years. Contact us right now and send us inquiries, we are so confident that we can be one of your most reliable suppliers in China.

Posted in best pcb, bestpcb, FR4 PCB, PCB News, PCB Technology, SMT Technology | No Comments »

“TEN Q & A” about Ceramic Printed Circuit Board

February 27th, 2023

Q1: What do the abbreviations DBC and AMB stand for?

A: DBC means “Direct Bond Copper” while full name of AMB is “Active Metal Brazed”. Both abbreviations refer to bonding technology of attaching a relatively thick copper (generally more than 0.2mm) on the ceramic substrates. These two technologies can be used to fabricate metalized ceramic substrates.

Q2: What is the mainly difference between DBC and AMB?

A: The mainly difference is AMB need to braze the copper to a ceramic board by active metal while DBC can directly connect the copper and substrate without any additional materials.

Q3: Which kind of ceramics are suitable for DBC and AMB?

A: DBC technology is suitable for oxide ceramics such as Al2O3 and ZTA. Non-oxide ceramics must be oxidized before they can be bonded to copper by DBC technology. ALN can be made into DBC or AMB ceramics, but Si3N4 only can be used as AMB substrates.

Q4: What is the function of metalized ceramic PCB?

The metallized ceramic substrate needs to carrier and interconnect multiple power semiconductor devices. The resulting electronic components are called power modules or multi-chip packages, most commonly LED packages or semiconductor packages.

Q5: Does AMB can be used with oxide ceramics?

A: Yes, but the effective of DBC technology is better and the cost is relatively lower.

Q6: What is the most important performance need to be considered when design a new ceramic PCB?

A: It depends on the end application of product will be used in. Ceramics are chemically inert substances that are resistant to corrosion, moisture, and high temperatures, making them preferable to organic dielectrics that degrade in corrosive environments. Electrical, thermal and mechanical properties are equally important in the design of a new substrate. Dielectric strength is an important factor to meet the isolation requirements, which should be set according to the standards, specifications and regulations of the target application. Low thermal conductivity is not conducive to the heat transfer between the chip and the surrounding environment. The bending strength and fracture toughness play an important role in prolonging the service life of the substrate under thermal-mechanical stress.

Q7: How to choose a suitable substrate?

A: First, the heat dissipation of power semiconductor devices should be understood. Then, based on the chip and the ambient temperature, the required substrate thermal resistance is calculated. However, the combination of copper and ceramic may not always achieve the desired thermal resistance. For one thing, the isolation voltage determines the minimum thickness of the ceramic. On the other hand, the thickness ratio of copper to ceramic has a great effect on the reliability. Finally, the set of applicable standards will be very limited.

Q8: Are DBC and AMB substrates suitable for high voltage applications?

A: The DBC substrate is ideal for applications with operating voltages up to 1.7 kV. For higher operating voltages, a thicker ceramic layer is required to meet the relevant isolation requirements. Silicon nitride (ALN) is often used because its high thermal conductivity offsets the increased thickness. In addition, resistance to partial discharge is particularly important in this application. Thus, AMB is superior to DBC techniques for this purpose unless the interfacial gap between copper and ceramics can be eliminated.

Q9: Are DBC and AMB substrates copper plated only on both sides?

A: No, both of two technologies can plate copper only on one side. But this is not a standard combination of materials, however, because the resulting flatness of the substrate is critical in multiple applications.

Q10: What are the shapes of substrates?

A: The rectangle is the cheapest and most common shape to produce. Other shapes are also available, but may incur additional production costs.

Tags: ceramic PCB
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The Difference Between 2L MCPCB and Double Sided MCPCB

February 27th, 2023

In our last article, we know what a metal core PCB is, in this post, we will introduce what is the difference between 2L MCPCB and Double sided MCPCB. Please continue to read if you want to know more about metal core printed circuit board.

Today we will explain from these four contents as following:

Stack up (structure)
Heat dissipation
SMD populate
Manufacturing technology

Stack up of 2L MCPCB and Double Sided MCPCB

For a 2L MCPCB, the metal core is positioning on the bottom side of the MCPCB as a cooling carrier to the whole MCPCB, while the metal base of double sided MCPCB is located in the middle of two copper trace. In generally, some PTH (plated-through-hole) vias are needed to designed to connect the bottom and top traces.

Below are the stack ups of these two kinds of products, from the structure, we can easily distinguish which one is 2L MCPCB and which one is double sided MCPCB.

Heat dissipation of 2L MCPCB and Double Sided MCPCB

Due to the different structure of the two products, their heat dissipation performance is also different. The main reason is the heating of double-sided metal core circuits can be spread out through both top and bottom side, while the heating generate by SMD components of 2 layers circuit only can be dissipated through bottom (metal) side and the heat need to go down layer by layer. In addition to this, the dissipation of FR4 is not good than metal materials, so double-sided metal core printed circuits perform better heat dissipation performance than 2 layers MCPCB.

Surface mounted locations (SMD populate)

Nowadays, surface mounted technology (SMT) is widely used in printed circuit board industry, more and more designers prefer to populate electronic components of the circuit surface to achieve high density, stable electrical performance and high reliability. 2L metal core circuit boards and double-sided metal core circuits also show their different mounted locations in this aspect.

The populate location of a 2L MCPCB only available on copper trace side, that is top side. And a double-sided metal core PCB can mount components on both top and bottom side, because both of them exist copper trace on it.

Manufacturing technology

May somebody will curious about “Are these two products produced in the same process/technology?”

The answer is obvious “NO, they have a different laminate process when fabricating.”

Different with single layer MCPCB, double sided MCPCB requires an additional pressing step to laminate the thermal conductive layer and metal core together. But sometimes, some raw Metal Clad material vendor will supply board material which already laminated.

For 2 layers metal core PCB, due to it is made of a single MCPCB and a double-sided FR4 PCB, the first thing we should make a double sided FR4 PCB, then laminate the PCB together with the single MCPCB. But due to the thermal conductive layer (pure adhesive) is easy to overflow during laminating process, which will cause the poor adhesion and crack between metal core and FR4 PCB. In the meantime, to avoid such problem, an experienced operator is needed to proceed the laminated process. That is why the lead time and cost of a 2 layers metal core circuit is much longer and expensive.

This is the end of this post, if you still have some questions or difficulties about the metal core PCB, welcome to contact us at sales@bestpcbs.com, our professional sales team and engineering team will give you a best solution for free.

Tags: printed circuit board
Posted in best pcb, bestpcb, mcpcb, Metal Core PCB, PCB Technology, SMT Technology | No Comments »

Do You Know What a Metal Core PCB Is?

February 25th, 2023

Metal Core Printed Circuit Board (short for MCPCB) is a technology developed to overcome the thermal limitations of the FR4 Printed Circuit Board. Different with traditional FR4 PCB, the PCB uses FR4 material as base core, while the base material of a metal core PCB is aluminum or copper. So compared with FR4 PCB, Metal Core is a better choice if your boards need to perform in high temperature environment.

What is metal core PCB?

A Metal Core PCB (MCPCB), also known as a thermal PCB or metal backed PCB, is a type of PCB that a metal material as its base for the heating dissipation part of the board. The thick metal is covering one side or double side of the PCB. The purpose of the core of a MCPCB is to redirect heat away from critical board components (such as LED or IC chips), and to less crucial areas such as the metal heatsink backing or metallic core. Base metals in the MCPCB are used as an alternative material to FR4 boards.

Same as FR4 PCB, the metal core PCB can be divided into Single layer MCPCB, Double layers MCPCB and Multi-layer MCPCB.

Single layer MCPCB

A single layer MCPCB is consist of a metal base (usually aluminum or copper alloy), thermal conductivity/dielectric layer and a copper trace layer, you can check below stack up for more details. Due to it only has one layer copper trace, sometimes we called it as one-layer MCPCB or single sided MCPCB.

The single sided MCPCB can be used with surface mount and chip & wire components, and provides much lower thermal resistance than FR4 PCB. What’s more, the metal core provides lower cost than ceramic substrates, and allows much larger areas than ceramic substrates.

Meanwhile, superior heat dissipation and good durability of Aluminum of metal core PCB can greatly eliminate heat sinks or other some voluminous hardware for engineers or designers.

Double layer MCPCB

Double layers MCPCB (2L MCPCB) has two copper layers on one side of PCB, and metal core as a base core on the bottom side of whole MCPCB, so the components only can be populated on the top side, below is a structure of double layer MCPCB.

(Stack_up_of_double_layers_metal_core_PCB)

From the stack up of double layers MCPCB, we can see it consists of a single layer MCPCB and a double sided FR4 PCB, so it needs an additional pressing process to laminate the thermal conductivity and FR4 PCB. Compared with normal FR4, this structure needs more technology and experience on laminating of two layers together with metal core.

There are two layers copper trace on the surface of MCPCB, can we call it as double sided MCPCB like single layer MCPCB?

The answer is NO, because they have different structure and perform different properties. In our next post, we will show you the differences between double sided MCPCB and 2 layers MCPCB.

Multi-layer MCPCB

Same as FR4 PCB, for those copper traces more than 2 layers, we named them Multi-layer MCPCB. Its structure is same as FR4 PCB, but more complex to fabricate. Below is a typical stack up of a 4 layers MCPCB:

Contrast with single layer or double layers MCPCB, multi-layer MCPCB can populate more components and achieve better performance in electronical performance.

Why Choose Metal core PCB?

Metal core PCB offers a great list of advantages when apply in a high-power application, below we listing some benefits of it:

Excellent heat dissipation
Lower thermal expansion than FR4 PCB
Dimensional stability than polyimide FPC
Great durability
Long lifetime
High utilization rate of space due to the heating can be transferred quickly
High strength and lightweight than FR4 PCB
Cost-effective

Where can we use Metal core PCB?

Metal core PCB can be used in high-power filed where requires fast cooling, good heat dissipation characteristics, the following popular applications may give you a guideline:

LED lighting
Power suppliers
Power conversion system
Automotive electronics
Telecom industrial
Photovoltaics
Semiconductors

With more than 16 years manufacturing experience, Best Technology is one of MCPCB supply leaders in Asia with good metal core PCB capability, we are so confident that we can provide you high quality, fast delivery and excellent one-stop service. Warm welcome to contact us if you have inquiries.

Tags: MCPCB
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