Jim

I can't tell you why this happens since I didn't see any of the parts but I believe Steve with his never ending story of experience in production could have given you the right input ( Well, to be honest I don't see the connection between a via consuming heat and the degradation of a solder joint that used to be OK. I mean the worst that can happen is that the Joint gets partially melted and solidifies again ) . Just two remarks:

- Steve, what do you mean by via too close. Do you have a number how far a via should be away of the pad?

- Jim, In my opinion it doesn't matter if the solder is heated up. Above 20 deg.C solder is in its plastic stage ( metallurgically speaking) and I don't know that it's loosing ist strength when recristallizing ( The metal is allready cristallized whenever it is solid ). The recristallization process takes place anyway whithin the first weeks of operation of the assembly and I think it would be very sad if all the leads could be lifted off easily by than. 

Have a great day

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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