Alloys and Their Uses

Solder
There are 2 norms for solder alloys - these are Sn63/Pb37 and SAC305. These 2 alloys are the bult of the usage, but there are a number of other importance alloys

ALLOY MELTING RANGE °F/°C What is it used for
Sn63Pb37 361/183 Most popular alloy, being replaced by lead free, but still more than 50% of the usage
Sn60Pb40 361-374/183-190 Military use, can be found in old specs and some dipping operations
Sn55Pb45 361-397/183-203  
Sn50Pb50 361-420/183-214  
Sn45Pb55 361-440/183-225  
Sn40Pb60 361-460/183-238  
Sn35Pb65 361-477/183-247  
Sn30Pb70 361-496/183-258  
Sn25Pb75 361-514/183-268  
Sn20Pb80 361-536/268-302  
Sn10Pb90 514-576/268-302 Used is component assemblies
Sn05Pb95 574-597/301-314 Used is component assemblies
LEAD-FREE MELTING RANGE °F/°C What is it used for
Sn96.5Ag3.5 430/221 Eutectic alloy, for hi reliability applications 
Sn96Ag04 430-444/221-229  
Sn95Ag05 430-473/221-245 Used is component assemblies
100%Sn 450/232 Tinning leads and rebalancing solder pots
Sn95Sb05 450-464/232-240  
Sn99.3Cu0.7 440/227 Eutectic alloy, for hi reliability applications 
Sn96.6Ag3.0Cu0.5 SAC305) 422-428/217-220 Most popular lead free alloy, replacing Sn63/Pb37 about 30% of the PCB assembly market
95.4Sn3.8Ag0.8Cu  (SAC405) 422-430/217-221 There is a debate about which is better - SAC305 or SAC405. SAC405 has more silver and is more expensive. SAC305 is the bulk of the market. There is some feeling that SAC405 is better, but this is not universally accepted
BISMOUTH ALLOYS MELTING RANGE °F/°C What is it used for
Sn 42 / Bi 58 144-163oC Used for toys, and to solder boards with sensitive plastic components, also good choice for step soldering with SAC305
OTHER ALLOYS MELTING RANGE °F/°C What is it used for
Sn62Pb36Ag02 354-372/179-189 Used is ceramic hybrid applications where Silver based conductors leach into the Sn63Pb37 alloy - the 2% silver addition dramatically slows the leaching, lowers the temp and has shinny joints (good substitute for Sn63/Pb37 but slightly more cost)
Sn60Pb36Ag04 354-475/179-246  
Sn10Pb88Ag02 514-570/268-299 Common High temp alloy, used in component manufacturing, step soldering with Sn63/Pb37
Sn05Pb93.5Ag1.5 565-574/296-301  
Sn05Pb92.5Ag2.5 536/280  
Sn43Pb43Bi14 291-325/144-163