Hi Tore, Victor, and All,
This problem is nothing new--though a solution sure would be.
What is happening is that you have a small crater-wall-like solder joint at
the periphery of the pad and no metallic connection on the pad  itself--you
can take a look at this in my reliability column in Global SMT & Packaging
magazine: Engelmaier, W., "Soldering: Quality & Reliability Issues," Global
SMT & Packaging, Vol. 1, No. 2, August 2001, pp. 52-53.
You can eliminate the problem from your product by doing a proper ESS, but
that is all after-the-fact [assembly].

Werner Engelmaier
Engelmaier Associates, L.C.
Electronic Packaging, Interconnection and Reliability Consulting
7 Jasmine Run
Ormond Beach, FL  32174  USA
Phone: 386-437-8747, Fax: 386-437-8737
E-mail: [log in to unmask], Website: www.engelmaier.com

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