Colors range from copper to redish to almost tarnish blue.




Guenter Grossmann <[log in to unmask]>@IPC.ORG> on 10/03/2001
10:24:12 AM

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Subject:  [TN] Antw: [TN] Solder joints not bonded to copper


Hi W

You say that you see a dull copper surface. What colour does it have?
Reddish or more like tin?
Could it be that you have hell of an intermetallic layer?

No, the wave will not oxidise the copper if it is covered with solder. But
it will for sure make the intermetallics grow. This can be a problem, if
your pad- surface already had free intermetallics prior to SMT soldering
because the components are only partially soldered and any embrittlement of
the joint may cause a failure when a week force is applied.


Best regards

Guenter

Guenter Grossmann

Swiss Federal Institute for Materials Testing and Research EMPA
Centre for Reliability
8600 Duebendorf
Switzerland

Phone: xx41 1 823 4279
Fax :      xx41 1823 4054
mail:     [log in to unmask]

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