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| Reply To: | TechNet E-Mail Forum. |
| Date: | Wed, 26 Jun 2002 14:44:06 +0200 |
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FEM analysis and simulation of temperature changes are interesting tools, you get information about the tensions and forces in different parts of the solder joint, and so you can give the joint geometry an optional design. It's like aching muscles, you need know exactly where and how to make massage. If not you may cause even more pain.
One guy at our company has done impressive such works, can link you together, if you want.
Regards
Ingemar Hernefjord
Ericsson Microwave Systems
-----Original Message-----
From: Werner Engelmaier [mailto:[log in to unmask]]
Sent: den 26 juni 2002 13:37
To: [log in to unmask]
Subject: Re: [TN] fractured solder joints
Hi Patti,
What you have is most likely a combination of the large ceramic/FR-4 thermal
expansion mismatch causing cyclic creep-fatigue and tensile displacements
frozen-in during hand-soldering causing creep rupture.
"More ductile solder" is not a solution. More uniform soldering and lower
thermal expansion mismatch strains are; the latter can be accomplished by
more compliant lead geometries, and if that is not possible, to a lesser
extent by an increased stand-off to increase solder joint thickness.
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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