Good day Technet:

We have a small custom part made of brass that's tin plated with .0001 to
.00025" of tin.  When we attempt to solder a wire to this part, the solder
flows up the side and stops at the top, where there is a sharp corner.  Some
of these solder joints appear to be cracked at the sharp corner.  I'm
assuming this is similar to the "weak knee" scenario, where the sharp corner
has very thin plating that has an exposed intermetallic compound, which is
unsolderable.  My questions are:  1)  what type (if any) of intermetallic
compound would I expect with tin-plated brass?  2)  what should I look for
in the microsection?

Thanks in advance,
Jim Marsico
Senior Engineer
Production Engineering
EDO Electronics Systems Group
[log in to unmask] <mailto:[log in to unmask]>
631-595-5879

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