Electronic – Does solder expire

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I have some solder that is past the "expiration date" on it. How does solder expire? Is it still good? What happens if I use it?

It seems odd that solder could expire, so I'm just looking for some clarification. Thanks!

Best Answer

Solder can definitely expire. This is because of the flux which can separate or in the case of solder paste dry out and become ineffective. The composition of the flux also matters as I have an at least 40 year old roll of Kester solder which still works brilliantly because it has a pine based flux, on the other hand I have a much newer roll of Alpha Metals solder which spatters because of an inconsistent flux mixture. The metal itself can also oxidize but it is so slow it is unlikely to matter and also depends on the type of metals used.

For hobby projects, if it still works then use it :)