Description
Soldering is a method of joining two metal surfaces without melting the base metal. In soft soldering, the filler metal (solder) has a melting point less than 316 degrees C (600 F). Soft soldering does not generate significant lead fume, but workers may be exposed to lead dust during cleanup operations. For hard soldering the melting point is between 316-427 C (600-800 F). Solder containing 65% tin and 35% lead is commonly used for soft soldering in the electronics industry. The flux improves the strength of the bond by displacing interfering gases and tarnish. During the soldering process, the molten solder displaces the flux. [Burgess, p. 375-82]