Alphalevel is immersion silver coating. As of today, this coating is not
widely used in US and it is quiet difficult to find somebody (except the
supplier) who has production experience. I had some experience of work with
electroplated silver coatings. The major problem of silver surfaces is
tarnishing. The solderability of silver is good but significantly degrades
when sulfides form on the surface. Under high temperature, the sulfides react
with oxygen and form sulfates. One of the solutions to this problem is
protection of silver with anti-tarnishing coatings (BTA, etc.). However, all
these coatings are extremely fragile and can be easily destroyed. It was also
observed that the thin coatings (thinner than 40 uin) degrade much faster.
This problem was solved by placing an intermediate nickel layer.


Chris

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