Hi Werner,
 
Thanks for this bit of additional information.  Are you referring to ceramic capacitors here or chip components?
 
Leland

________________________________

From: TechNet on behalf of Werner Engelmaier
Sent: Tue 6/21/2005 9:49 AM
To: [log in to unmask]
Subject: Re: [TN] IC Lead Conditioning Services



Hi Susan,
Sorry, didn't mean to 'leave you hanging'--thought this was a well-known
fact, considering the massive study in Germany and the fact that the pertinent
data are in IPC-D-279.
It has to do with the off-set restrictions; Class 2 allows up to a 50%
off-set and Class 3 only 25%. This leads to a higher propensity of CCs cracking for
Class 3 product than Class 2 product, because the smaller the off-set the
larger are the solder joint fillets and thus the stresses on the CCs.

Regards,
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, Cell: 386-316-5904
E-mail: [log in to unmask], Website: www.engelmaier.com


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