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Reply To: | DesignerCouncil Mail Forum. |
Date: | Sun, 17 Aug 1997 17:43:27 -0400 |
Content-Type: | text/plain |
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Hi Jeffrey,
It certainly is appropriate for you to cry--Help!--
As a first step you should get IPC-D-279, Design Guidelines for Reliable
Surface Mount Technology Printed Board Assemblies, and go through Appendix A.
There are only two ways to make the SM solder attachments more reliable, if
you can not reduce the delta-T: (1) reduce the CTE-mismatch (not an adequate
solution if you have both plastic and ceramic components), (2) make the
attachment nore compliant (solder columns or compliant leads). Other options
(with less promise) are: use fine-pitch to reduce component size, and use
underfill to remove the thermal expansion mismatch from the solder joints.
Werner Engelmaier
Engelmaier Associates, Inc.
Electronic Packaging, Interconnection and Reliability Consulting
23 Gunther Street
Mendham, NJ 07945 USA
Phone & Fax: 973-543-2747
E-mail: [log in to unmask]
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