1. 2% silver is not going to lower electric resistance much at all. The combo
mentioned in the thread will be a eutectic or close to it, and melt a few
degrees below -- no more -- than the 63tin/37lead eutectic. Silver in solder
or braze tends to lower the surface tension of the molten mix, and you may find
it easier to solder with this combo because it may flow more completely and
smoothly in your applications. I think the chances of a solder in Thailand
really having 100% silver are zero. Thailand has a significant jewlery
manufacturing industry, but the solder for that has about 2 1/2 % to 5% copper
in it.
2. Years ago, I worked as an electronic tech, and learned that some assembly
contracts required first soldering a joint, then sucking and wicking all the
solder out of the connection, then resoldering it. I understood informally
(i.e., not confirmed) that this was the requirement and standard for NASA
contracts, because of the constant vibration in their applications. This
procedure makes for much greater reliability. I concur with the suggestions to
do similarly with a board that has developed an open. It is a little bit of a
pain, but you should suck/wick any suspect solder joint clean and resolder.
Gene May
WB8WKU
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