Lloyd Johnson wrote:

> Jon wrote:
>
> >>.  MillMax usually makes good
> stuff, so it may have something to do with the plating on the chip,
> itself.  Are the contact points of the socket gold-plated?<<
>
> No, the contacts are tin-plated and the leads on the chip are tin plated.

This is a more difficult situation.  Gold contacts, of course, will
stay quite clean in storage.  Tin, or Tin-Lead plating will oxidize
slowly, building up a film over the metal.  Corrosive gases in the
air, like air pollution, will speed this up a lot.  I'm not sure what the
reflow process does to this, but the heat and flux would be expected
to worsen things unless the flux gets activated on the contacts.  Anyway,
sounds like a mess.  I wonder if the sockets could be covered during reflow
to keep flux spatter/fumes out?  Otherwise, it might be necessary to
squirt some sort of flux remover/cleaner on the contacts after reflow,
or before inserting the chips.

Jon


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