Joseph,

I just asked a question concerning phosphorous intermetallic growth as
in item 16 or so. I was prompted to do so because of a response I
received some weeks ago concerning the issue you raise.

Again, a major BGA supplier (Motorola) wrote me and confided they found
the problem associated with their sphere attachment to a substrate using
the immersion tin and gold processes. To make a long story short,
someone, at some time dropped a board on the floor detaching BGA devices
at all their termination points.

My question to industry is what can we do to overcome the phosphorous
intermetallic and resulting solder joint embrittlement problem? Can we
go to electroplated nickel in required thicknesses and then deposit
electroless gold over that?

Earl Moon

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