I would like to know if somebody has got some experience in using the, so called, "Bi58" (i.e. Sn = 42%, Bi = 58%) solder.
As I know solder with lead are the best (melting point around 180 C°) but I want to be a good boy: only lead-free solder. At the moment I'm using the common and cheap Sn99Cu1 (227 C° as melting point) but I'm really unsatisfied with it. I mean... it's a good solder but... damn! When you try to desolder it's a real nightmare. After two or three day it becomes hard as steal and it is so sticky! You need an atom bomb to free a pin from that obstinate thing.
Before you ask the answer is yes: I have a desoldering pump and an hot air gun, but every time is a battle. Using the hot air gun you have to reach a temperature close to nuclear fusion to melt it again.
Since the Bi58 has a melting point at just 138 C° I was thinking that it could have a workability close to the one of solders with lead added. I've examined wikipedia with attention and seems the best candidate:
Bi58. Reasonable shear strength and fatigue properties. Combination with lead-tin solder may dramatically lower melting point and lead to joint failure. Low-temperature eutectic solder with high strength. Particularly strong, very brittle. Used extensively in through-hole technology assemblies in IBM mainframe computers where low soldering temperature was required. Can be used as a coating of copper particles to facilitate their bonding under pressure/heat and creating a conductive metallurgical joint. Sensitive to shear rate. Good for electronics. Used in thermoelectric applications. Good thermal fatigue performance. Established history of use. Expands slightly on casting, then undergoes very low further shrinkage or expansion, unlike many other low-temperature alloys which continue changing dimensions for some hours after solidification.
Since my PCB boards are not exposed to high temperatures and I don't want to damage ICs with excessive heat while soldering pins and wires I think that Bi58 could be a good choice.