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Reply To: | TechNet E-Mail Forum. |
Date: | Wed, 23 Jun 2004 07:33:33 -0400 |
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Thanks, Guenter, for your response, one more question, though. If the
solder joints are allowed to stabilize at the temperature extremes, won't
the internal stresses diminish in time (creep)? If so, will the strain rate
still have an affect? With that said, will the soak time have an affect on
solder joint reliability?
Jim Marsico
Senior Engineer
Production Engineering
EDO Electronics Systems Group
[log in to unmask] <mailto:[log in to unmask]>
631-595-5879
-----Original Message-----
From: Guenter Grossmann [SMTP:[log in to unmask]]
Sent: Wednesday, June 23, 2004 3:28 AM
To: [log in to unmask]
Subject: [TN] Antw: [TN] Shock vs. Cycling
James
The results you will achieve will be totally different and specific
to
the test.
In thermal shock deformation and degradation mechanisms will be
activated that are irrelevant in thermal cycling and vice versa.
- Degradation in solder joints depends on the strain rate
- The degradation path in solder joints can be influenced by the
stress
applied. And, the higher the strain rate the higher the stress.
- Thermal shock can lead to the destruction of the components
something
that will not occur in thermal cycling
- Due to thermal shock the substrate will bend or warp and bring in
additional stress into the component and the joints not occurring in
thermal cycling
If your application includes thermal shock you must test the
specimen
accordingly if the stress is thermal cycling, thermal cycling is the
test you have to do otherwise it is impossible to make any
connection
between the test results and the real application. I do have even
doubts
about the validity of comparative tests done with thermal shock if
no
thermal shock occurs in the application (see above).
Best regards
Guenter
EMPA
Swiss Federal Laboratories for Materials Testing and Research
Centre for Reliability
Guenter Grossmann, Senior Engineer
8600 Duebendorf
Switzerland
Phone: xx41 1 823 4279
Fax : xx41 1 823 4054
mail: [log in to unmask]
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