Solder is the life and blood of any PCB. The quality of solder used during soldering and PCB assembly decides the life and performance of any electronic machine, equipment, appliance or gadget.
Different alloys of solder are available but the real ones are those that are eutectic. Eutectic solder is one that melts exactly at the temperature of 183 Degree Celsius. An alloy of tin and lead in the ration 63/37 is eutectic and hence 63/37 tin-lead solder is called eutectic solder. Solders that are non-eutectic will not change from solid to liquid at 183 Degree Celsius. They may remain semi-solid at this temperature. The nearest alloy to eutectic solder is tin-lead in the ration 60/40. The favorite solder for electronic manufacturers have been 63/37 for years. It is stilly widely used across the world.
Because lead is harmful to the environment and human beings, the European Union took the initiative to ban lead from electronics. It has been decided to get rid of lead from solder and electronic components. This has given rise to another form of solder called lead-free solder. This solder is called-free because there is no lead in it. Lead-free solder alloys melt around 250 °C (482 °F), depending on their composition. Most common lead-free alloy is tin / silver / copper in the ratio Sn96.5/Ag3.0/Cu0.5 (SAC). Lead-Free solder is also called “No-Lead” Solder.