NOT following the current branch of this thread, but related ...
Melting Temperatures of common Tin-Lead solders, arranged in decreasing order:
Melting temperatures: 0/100 ? 621° F (pure Lead) 30/70 ? 491° F 40/60 ? 460° F 100/0 ? 449° F (pure Tin) 50/50 ? 421° F 60/40 ? 374° F 63/37 ? 361° F "Eutectic"
It is interesting to note that some of the alloys melt at lower temperatures than either of their component metals! This is common for many alloys.
For a given alloy, usually the lowest melting point mix is called "Eutectic", it's a state when ALL components of the alloy melt at the same time (temperature). With OTHER alloys (mixtures), components will melt at slightly different temperatures, causing a sort-of "putty" or "granular" state in the melt. This CAN sometimes be useful in structural soldering.
As stated previously, the common 60/40 Tin Lead solder is the most useful for most electronic uses ... note that it's NEARLY the "eutectic" mix.
Other specialty solders have melting temperatures as low as 190 degrees F., a temperature below that of boiling water, and high-temp solders (usually copper-bearing) may exceed 1000 degrees F. melting temperature, though many call soldering at such copper-melt temperatures "brazing". It's not fundamentally different, but much stronger. One limitation, of course, is that the materials being brazed must be able to stand the heat.
All these specialty solders also have matching fluxes.
The most readily available (in the USA) silver-bearing solder is "Stay-Bright", a tin-silver solder with a melting point of 430° F, about the same as the plumbing grade tin-lead solders, and attainable with a common soldering iron.
Higher silver content makes a stronger solder, but considerably increases the melting temperature. These normally require use of a torch.
All kinds of solders with widely varying properties are available for soldering 'difficult" materials, like stainless steel.
Sometimes a variety of solders with different melting points are useful for assembling complex structures. Start with the higher melting point solder to assemble subcomponents, then use the lower temperature solders to assemble these ... thus avoiding un-soldering previous joints.
Dan Mitchell ============