I agree with the point raised about pre heating during rework and repair of
ceramic capacitors. In the good old days the problem with these parts was a real
issue. I have always evaluated ranges of parts for production buy immersing the
parts in a solder bath without preheat for process compatibility as suggested in
the IEC test method. This sorts out the men from the boys. All other guidelines
for wave and reflow are still relevant but preheating of parts ?????

When originally asked to comments on the IPC video tape on rework, which I guess
this comes from,  where the pre heating on a hot plate was suggested I stated
that it did not happen in the real world. Cracking to day in parts is mainly
seen as a result of flexture failure of parts. If they crack during soldering it
is more likely to be a result of questionable parts.

Bob Willis
Process Engineering Consultant
Electronic Presentation Services
2 Fourth Avenue, Chelmsford, Essex CM1 4HA. England.
Tel: (44) 01245 351502
Fax: (44) 01245 496123
Home Page: http://ourworld.compuserve.com/homepages/Bwillis
Email: [log in to unmask]


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