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May 2005

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Subject:
From:
Guenter Grossmann <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Guenter Grossmann <[log in to unmask]>
Date:
Tue, 10 May 2005 15:14:06 +0200
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Cheryl

To have enough data you need to make cross sections and a metallurgical
analysis. We saw failures looking somewhat like what you mentioned
because of 3 reasons:

1)  Metallisation lifted of the pin.
2) Poor thermal management. The pin and the solder never got together
long enough with ample temperature to form an alloy. Or the solder
solidified from the pin and from the PCB. Where the two solidifying
fronts met the solder was already too cold to join (Just a remark: This
seems to be more pronounced with lead free solder).
3) Contamination of metal surfaces (rare) or reduced solderability
which combined with 2) can lead to soldering problems.

In your case I have the impression that you have a thermal problem
(ground plane).

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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