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Archive for August, 2020

How to prevent the FR4 PCB bended and warped after reflowing?

Wednesday, August 19th, 2020

Everyone may know that PCBs are easy to be bended or warped when get through the reflow process. Do you how to avoid this issue? here are some advices your reference.

  1. Reduce the effect of temperature on PCB board stress

Due to the “temperature” is the main source of stress for board, so as long as the temperature of the reflow oven reduce the temperature or slow the speed of warming up and cooling down in the reflow oven, the board bending and warping issue can be reduced. But it may be occurring other issues, such as short circuit when soldering. See Best Tech make control for the temperature of the reflowing process.

reflow machine

 2. Use high Tg plate

 Tg is the glass transition temperature. The lower of the Tg value, the faster of board starts to soften after finishing reflowing, and deformed of the board become more serious. if use of higher Tg 170 material can increase the ability to withstand stress deformation, but the price of TG170 material is higher. See the stock of high Tg material from Best Tech.

Use high Tg plate

3. Increase the board thickness

If final application allowed, we recommend 1.6mm thickness to prevent the risk of board bending. Best Tech can provide PCB board thickness to 4.5~8.0mm.

PCB board thickness
  • Try to reduce the size of the board and the number of panels during design

 Since most reflow oven use chains to driving the board forward, if larger size of the FR4 PCB, the own weight will be deformed in the reflow oven, so during design try to design the long side of the PCB as a board edge, it can reduce the deformed. And

Same reason, if there are many PCBs in a big panel, PCB will be bigger and heavier, when get through the oven, the speed in the oven will be slowly and it will influence the deformed of the PCB. See following PCB board, we only panel 1 single piece into a panel to keep the size of FR4 PCB panel not bigger.

pcb
pcb

5. Use the reflow carrier/tray

If above methods cannot get a good result for deforming, you maybe can use a reflow carrier/tray to reduce the deformation. The reason reflow tray can fix the circuit board, after the temperature of the printed circuit board is lower than the Tg value, it can maintain the original size.

pcb in tray

6. Use Router instead of V-Cut

Since V-Cut will destroy the structural strength of the panels, try to use Router PCB board or just reduce the depth of the V-Cut will helps the deform issue.

pcb
pcb

If you want to know more about how we control the bended and warped for PCB, you are welcome to contact us.

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What’s the advantages for AMB ceramic PCB comparing with DPC, DCB, LTCC, HTCC, thick film ceramic PCB?

Tuesday, August 18th, 2020

As we know, there are all kinds of ceramic PCB, DPC ceramic PCB, DBC ceramic PCB, LTCC ceramic PCB, HTCC ceramic PCB, thick film/thin film ceramic PCB.

Very few people know that there is AMB (Active Metal Bonding) ceramic PCB.

Do you know what’s the advantage for AMB ceramic PCB compare with other ceramic PCB (Al2O3/AlN/BeO/Si3N4 PCB)?

For AMB PCB, the substrate can be AlN ( Aluminium Nitride) and Si3N4 (Silicon Nitride) normally, AlN is the most popular. It is widely known that AlN with very high thermal conductivity ( Theoretical Value is 320W/m.k).

Using AMB technology to combine the oxygen-free copper and AlN material under high temperature, AlN with smaller thermal resistance, lower coefficient of thermal expansion and more stable partial discharge capability.

Compared with the traditional DBC or other substrate, the Aluminum Nitride copper-clad ceramic substrate made by the AMB technology with higher bonding strength of the copper layer and better cold and hot cycling characteristics.

So it  is widely used in the field of IGBT, especially for the high-power device control module.

AMB with competitive price and the copper thickness can be much thicker.

AlN max 300um
Si3N4 max 1200um

For more details, please contact me sales@bestpcbs.com 
I will update the manufacture process at the end of this month.

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What are the Differences between Double Sided MCPCB and Double/Two Layers MCPCB?

Friday, August 14th, 2020

Metal Core PCB are differentiated on the basis of their construction, which can be divided into following types: single layer, double/two layers, double sided, and multi layer. The double sided and double/two layers MCPCB are commonly used in advanced electronic circuits, some people may be confused about them due to their similar names. So in this blog I’d like to share with you the differences between the two types. 

Actually the main difference is the double sided and double/two layers MCPCB have different layout due to the positioning of the metal core.

Double/two layers MCPCB

As you can see the following stack up, the metal core is at the bottom, with two copper layers on top side, the dielectric layer is between the copper layer and the bottom metal base. In short, the conductor layers is in same side of the metal core. The components can only be assembled on the top layer.

double/two mcpcb stack up
double/two mcpcb

Double sidedMCPCB

As you can see the following MCPCB stack up, the metal core is in the middle of two conductor layers. There is also a dielectric layer between the metal core and a copper layer. The metal core and conductors are connected to each other through PTH (Plated Through Hole). The components can be assembled on both the bottom and top.

double sided mcpcb stack up
double sided mcpcb
Double sided MCPCB

Both double sided and double/two layers aluminum/copper core have the good heat dissipation, reliable performance at high temperatures and excellent thermal expansibility, according to our experience, for the same design, the heat dissipation on Double Sided MCPCB is a little better than Double Layers MCPCB.

The choice of the either type will depend on customer’s application requirements. If you are still confused about the two types and their benefits for your application, please feel free to contact Tammy (Email:sales9@bestpcbs.com), the Metal Core PCB International Sales in Best Technology.

Welcome to visit our website to learn more about us, we can provide different types of MCPCB in diverse specifications.

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