In a message dated 09/26/00 5:36:50, [log in to unmask] writes:
>Just some advice if possible.  I have a board that shows a plating crack
>in the barrel and another with a plating crack at the knee (corner). The
>hole is a via .3mm (11.8 mils) with about 20 to 21 microns (~0.8 mils) of
plating >(checked by micro section) This is a first this year and cannot find
any cause. Could
>someone out there give me a starting point please. Thank you first.
>Frank

Hi Frank,
You do not tell us how thick the PWB is nor what thermal excursions it has
seen.  This information is crucial for a full understanding of what is going
on. Also how uniform is the plating thickness (dog-boning), and what kind the
strength and elongation values do you get on your mandrel samples? Has
anything changed in your plating process? How automated is your plating
chemistry maintenance process?
However, generally it can be said that 20 microns is not what I would
recommend as the optimal plating thickness for reliable vias; you should pl
ate at least 25 microns or better yet 30 microns.

Werner Engelmaier
Engelmaier Associates, L.C.
Electronic Packaging, Interconnection and Reliability Consulting
7 Jasmine Run
Ormond Beach, FL  32174  USA
Phone: 904-437-8747, Fax: 904-437-8737
E-mail: [log in to unmask], Website: www.engelmaier.com

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