ron_sutherland:
A little over year old circuit board looks very odd. It had Immersion Tin (edit: probably Silver) pads, now the pads won't take solder and look like a fungus has got all over them. All I can find that describes this is "Tin Pest". Anyone else ever see this sort of thing with immersion tin.
Some of our customers require silver plating on their boards. The board house vacuum seals packages of boards in plastic, along with a desiccant package. Even so, some boards have tarnish on the silver in some places. We have used liquid "Tarnex" solution to clear the tarnish and then the boards solder as new. The package really should have nitrogen to replace all the air, but doesn't seem to be done.
Paul