The types of solders (1) According to the melting temperature of solders, they can be divided into soft solders and hard solders. The solder with melting temperature lower than 450 C is called soft solder (also known as easy solder); the solder with melting temperature higher than 450 C is called hard solder (also known as refractory solder). 450 is the artificial demarcation temperature, and "soft" and "hard" are only relative. (2) According to the main components of solders, the solders are classified as indium-based solders, bismuth-based solders, tin-based solders, lead-based solders, cadmium-based solders, zinc-based solders, etc. The solders are aluminum-based solders, silver-based solders, copper-based solders, manganese-based solders, nickel-based solders, gold-based solders, etc.