Hi,
What actually accounts for the large black patches on pads when the
technology goes wrong? Are these sulphates?
Regards


 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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