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Printed Circuit Board Assembly & PCB Design Forum

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PWB Pad Finish & dewetting

Carol Stirling

#18357

PWB Pad Finish & dewetting | 6 December, 2001

This SMT process certainly makes a body want to win the $$$ and retire! We have been trying to stabalize the process and keep running into new problems. Any help would be appreciated on this issue. All pads on both sides have the same look - partial pad finish is bright, shiny and solders well, the remainder of the pad is dull and shows obvious dewetting. The larger the pad, the larger the dull area. The pattern is the same for both sides. It looks like the board was dipped in solder but it only stuck to the bottom end of all the pads. Would I be correct in assumeing this is the board house's responsibility and should be rejected back to them? Any solutions or recommendations are appreciated, especially for the boards we have processed and can't use. We are a Class 3 Manufacturing facility.

or somebody can send me a million $$$$?

Thanks for the help...

Carol

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#18362

PWB Pad Finish & dewetting | 6 December, 2001

First, we�re assuming that we�re talking hot air solder leveled [HASL] bare boards, eh?

Consider using A-600 - Acceptability of Printed Boards as the basis for discussing the bare board problems. It is the bare board analog of A-610 - Acceptability Of Electronic Assemblies.

As with the solder connections that we assembler make, fabricators don�t put a whole lot of stock in �shiney� or �dull�. Appropriately each discussion revolves around a properly formed solder connection. Your's doesn�t sound like one we�d like.

As part of our receiving process, we wave one board from each lot received and inspect it for acceptable solderability according to A-600 [ http://www.ipc.org/TOC/IPC-A-600F.pdf ]."

Sure, I�ve got a million $$$$ to send you, but first you need to send me just $50,000 as a sign of good faith.

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