| There is one very good reason to use silver-bearing solder (2% to 4% silver, with tin and lead). If you solder onto silver-plated contacts (like the ones on those ceramic terminals in your Tektronix oscilloscope) using normal tin-lead solder, then the solder will leach the silver out of the contact point and ruin it. Silver-bearing solder doesn't do that. I've been told this also applies to gold contacts, but I don't actually know if that's true.
For years I bought the silver-bearing solder from Radio Shack as my go-to solder because I had no trouble working with it, and it's available on Sunday afternoon. Now I keep some of it around, but there are other solders I use most of the time. It is not eutectic, so it kind of "eases" from liquid to solid, which can cause problems if you're unable to hold the joint motionless as it cools. That's probably most likely with cable assemblies where you're always using your knees and elbows to keep the cable from falling on the floor while you solder. Interestingly, the tin/silver/copper solder I have around for repairing our lead-free assemblies is eutectic, and it really "snaps". It also turns dull grey when it solidifies, which is unnerving because it makes you think you messed up the solder joint. So you reflow it to make sure, and it does the same thing again. Kind of annoying until you get used to it. |