In a message dated 02/16/0 18:16:34, [log in to unmask] writes:
>Copper traces sometimes crack due to mechanical bending/flexing or thermal
>expansion mismatch. Do you know any modeling works on this issue?
>Generally, how do substrate suppliers and packaging houses decide the
>minimum trace width to prevent trace cracking under these situations?
Hi Yuan,
Yes, there has been quite a bit of work done in this area; you may want to
start with IPC-TR-484, Results of IPC Copper Foil Ductility Round Robin
Study. And by the way, trace width has little to do with trace cracking
unless there are significamt edge non-uniformities.

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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