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PCB Solder Mask Adhesion

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#67462

PCB Solder Mask Adhesion | 9 October, 2012

Hello All, I have PCB's in a 30 up panel that have signs of improper solder mask adhesion. Per IPC 6012 they specify a maximum of 5 Percent allowed to have problems adhering to base laminate per class 2. I am trying to figure out if this 5% is for the entire assembly or if it is for an individual board. We are seeing solder mask lift in between the lands of a 25 mil connector. This lifting is lot specific and am trying to gather evidence that the board house is at fault. Any help would be greatly appreciated.

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#67473

PCB Solder Mask Adhesion | 9 October, 2012

You're correct. It hinges on who's talking about a "production printed board." * You think a "production printed board" is the board that you're trying to produce and ship. * Your fab thinks a "production printed board" is a 30-up panel.

It would be nice if that was defined in your procurement documents.

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#67479

PCB Solder Mask Adhesion | 10 October, 2012

Thanks Dave, The funny thing is that 2 years ago the suppplier did not have any problems with adhesion in these areas.

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#67480

PCB Solder Mask Adhesion | 10 October, 2012

I agree. You should build your case, based on your interpretation of the specs. Let him / her know the boards are shit, have the fab replace the panels, etc

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#67481

PCB Solder Mask Adhesion | 10 October, 2012

Well after converting everything and crunching some numbers total 5% allowance per IPC would be 6.1553 I am only seeing .084 so according to IPC Spec the boards are acceptable, But i will update AABUS and procurment Docs to avoid future issues.

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#67490

PCB Solder Mask Adhesion | 11 October, 2012

We have seen two issues which have caused problems with solder mask adhesion. The first was improper curing of the mask but also solder temps which were too high, particularly with a white tin finish. Rather than tell your supplier their material is shit you should probably try and work with them.

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