About PCB warpage, standard, handle method, and how to avoid it?|

1.What is PCB warpage? What is warpage standard?

PCBmanufacturerChina talk Board warped refers to the bending of a flat PCB board, also known as warpage.Serious warpage is a bit like an arch.PCB isn’t 100% flated at the actual manufacturing.We can judge the warpage degree of PCB by “warpage degree”.

According to IPS standard, the needed mount PCB’s warpage degrees(WD) should be less or equal to 0.75%.That’s to say, it should be judged as the warped board, or defect product when WD is more than 0.75%.Actually, board flat degrees require be less when it doesn’t mount components and just needs to plug-in parts, WD standard could be less or equal to 1.5%.Of course, some factory for match more higher customer demand, they could pursuit for more stracit stanard, some WD stanard need less or equal 0.5%, even this require is reached to less or eqaul 0.3%.

2.Which demage is PCB warpage?

Excessive warpage will not only affect the placement, but also affect the reliability of the SMT placement machine.

FPCsupplier talk for that no needs mount PCB, warpage will lead to plug-in parts’ pin is hard to cut, and then the PCBA board cannot be installed on chassis or socket in the machine.That it will lead whole machine stability isn’t good, this is nightmare to assembly product line.

Fore that need to mount components’ PCB, it is not only affect mount product qulity and also damage SMT equipment.Solder is diffcult to paste to PCB as it isn’t flat, in automatic SMT line, it will lead to error placement, and components can’t mounted to pcb pad.

3.What is cause warped board?

General, it think to be have 8 causes.It have come from manufacture, another is derived from design.

Manufacturer’s cause is more, common four below:

1.After the board are cutted, the baking is not made, or the baking time is not enough.

2.V-CUT is too deep, leads to two sided V cut place warped.

3.Board material’s TG vaule too low, board easy soften and lead to can’t endurance high temperature, and happed warped board.

4.The plate thickness is less than 1.0mm, and the cold-pressed plate warping process is immature before shipment, resulting in plate warping.

Warped board handle method

Duo to many different caused, for instance, design defect, fixed warped process isn’t work, and still happen warped, what should do it?

PCBmanufacturer talk could put defects product into oven to baking, and under 150 celsius degree to baking it for 3 to 6 hours. Let it natural cool down under higher weight pressure. And then release weight presure take out these board, check it again. The process maybe could save some board, and if it still have bad warped degree, so that have to scrapped it.