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seperation of soldermask and pcb

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#71834

seperation of soldermask and pcb | 18 March, 2014

Our contract manufacturing agency have procured pcbs from approved vendor. After assembly we found solder mask separated from the PCB on the epoxy area as patches. The top side is intact.

also over the pcb tracks, the mask got damaged.

In what condition during assembly the Mask gets affected ?

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#71835

seperation of soldermask and pcb | 19 March, 2014

I can't picture much of what you're saying, not for nothing, I'm just not connecting.

During assembly, solder mask can affected by heat and chemicals. Typically this would be during: * Soldering * Cleaning

I will tell you this: Not to defend assemblers, but it's very difficult for an assembler to affect a properly applied and cured solder mask. Not to say that it can't be done, it's not the first place I'd look.

I think that you should sit your assembler and your fab down at a table and have each of them tell you a story. Get back to us and we'll tell you which story we'd buy.

BR davef

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#71867

seperation of soldermask and pcb | 25 March, 2014

Please refer the attached jpegs, The problem is noticed after reflow soldering followed by conventional through hole soldering.

Flux used one is MIL Std. Brush cleaning in IPA is followed after each soldering step.

regards,

R.Saravanan

Attachments:

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#71870

seperation of soldermask and pcb | 25 March, 2014

Have you tried to bake the boards before you process them?

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#71871

seperation of soldermask and pcb | 25 March, 2014

The boards are baked for 2 hours at 120 deg C

Regards,

R.Saravanan

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#71872

seperation of soldermask and pcb | 25 March, 2014

The first impression I get is that the mask was applied over dirty or contaminated copper. What is the trace and land finish on the PCB? You also appear to have a wetting problem.

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#71873

seperation of soldermask and pcb | 25 March, 2014

It is Solder Mask on Bare copper, The land finish is HASL as per MIL-PRF-55110G which accepts trace of HASL as acceptable.

Wetting is acceptable. regards,

R.Saravanan

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#71875

seperation of soldermask and pcb | 25 March, 2014

Ok lets put it this way. If the PCB house used a high quality mask and properly applied it to a properly cleaned surface and properly cured it, then as Dave stated above there are only two things that can destroy it. Excessive heat and overly aggressive chemicals. I only mentioned wetting because the solder on the leaded component in the center picture does not look like it wetted to the pads, however the chip components look fine. Not knowing the details of your process I will say no more.

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