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What is the cause of blister in PCB resistance welding?

What is the cause of blister in PCB resistance welding?

PCB circuit board solder resist blister refers to the circuit board under the environment of high temperature (above 250 ℃), the welding layer separated from plate or copper foil, fall off, so that the loss of resistance welding and choke effect.The appearance of PCB will be affected not only by the resistance welding blister, but also by the performance of PCB.So what is the cause of blistering PCB resistance

welding?Analysis by FASTPCBA technician:

 


1. Poor surface treatment: due to the fact that the PCB surface has not been well treated, such as unevenness of brush, residual water and oil stains, etc., the PCB resistance welding blister easily occurs.
2. Uneven ink thickness: during the resistance welding of printed circuit board, especially manual printing, the thickness of resistance welding printing is often different. Therefore, in the places where the resistance welding is relatively thick, the adhesion of resistance welding will be reduced due to insufficient drying time, leading to the blistering of resistance welding.
3. Repeated soldering or excessive temperature of tin pan: generally, the resistance welding of circuit board has a certain resistance to high temperature. Once the resistance welding exceeds its range, it will affect the adhesion of the resistance welding.Usually, repeated soldering or high temperature will affect the adhesion of PCB resistance welding.
4, copper surface depression: there are many kinds of PCB board, the board that general international won’t appear the phenomenon of copper foil sag, some use contractor in order to reduce the cost of PCB manufacturers use price lower PCB board, when the solder resist printing to the concave position decreased adhesion so will produce the phenomenon of resistance welding fall off.
The reason of PCB resistance welding blister is introduced here today.The blister phenomenon occurred in the resistance welding of PCB circuit board. The staff can solve it according to the above reasons to avoid the blister phenomenon.

10月-24-2018

FASTPCBA