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Cracking solder found in cross sections

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#64350

Cracking solder found in cross sections | 25 May, 2011

Hi All,

I am new the PCBA process fabrication. I have found many cracks in the PCB after we have cross sections analysis. The cracking has same kind of pattern. It happens betwen the solder and the PCB, or between the solder and the part, BUT not betwwen the soldering and the PCB laminate. I guess the heating/cooling issue. How do I know the root cause of the cracking failure? Please help me out.

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#64352

Cracking solder found in cross sections | 26 May, 2011

What process steps have been completed before the cross-section? What type of devices have solder cracks? Are the cracks found after just normal processing or after some type of validation testing?

It is very unlikely to be a heating/cooling issue (I assume you mean reflow). Cracked solder joints due to assembly are almost always due to overstress. Cracks due to reflow wouldn't be in the solder, they'd be in the laminate itself. I would check the strain levels at in-circuit test, singulation, and any other process that could be subjecting the board to mechanical forces.

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#64354

Cracking solder found in cross sections | 26 May, 2011

Maybe attaching some pictures of your cracked solder connections might help us in offering suggestions to help you with your problem

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