We've seen the same phenomenon as Susan. If I recall, an average thermal
stress can remove up to a ten of a mil of copper from the knee sitting
in the solder pot. We did a lot of work on this when looking into rework
of a multiple segment edge connector. I know of nothing that would
explain significant loss at the top side knee.

Regards,

Paul Terranova
Analytical and Environmental Test Services Lab

 Digital Equipment Corporation
 200 Forest Street
 Mail Stop: MRO3-1/D2
 Marlboro,  MA  01752-3085

'    Phone: (508)467-3109
* Fax: (508)467-6796
* Email: [log in to unmask]
WebSite: http://www.digital.com/lab-services

                -----Original Message-----
                From:   Robisan1 [mailto:[log in to unmask]]
                Sent:   Sunday, April 26, 1998 10:48 AM
                To:     [log in to unmask]
                Subject:        Re: [TN] Dissolution of plated copper

                Scott
                I have seen this dissolution when performing
                multiple thermal stress tests.  In fact eventually
                knees will disappear completely if you expose
                them enough

                One thing that can effect this is type of plating
                A totally electroless deposit will go into solution
                much faster than the electrolytic deposits.

                I have done nothing that would compare one to
                the other, but I do know it happens

                Susan Mansilla
                Technical Director
                Robisan Lab


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