Beginning July 1, the European Union will strictly limit the amount of lead and other hazardous materials lurking within the circuitry of any electronic appliance sold.1 Given the global nature of the electronics industry, however, the European ban is in essence international in scope. As electronics and appliance manufacturers scramble to meet those tough new restrictions, a lead-free solder developed at the U.S. Department of Energy's Ames Laboratory is playing a key role.
Solder is the shiny metallic "glue" that holds components on circuit boards and bonds other electrical connections. Though a computer's circuit boards contain only small amounts of lead solder, the problem is overall volume. By some estimates, about 3,000 tons of electronic waste is discarded daily just in the U.S.
Composed of lead and tin, traditional solder melts and flows easily, but sets up quickly to create a strong, durable bond between the mating surfaces. A solder blend of 63 percent tin and 37 percent lead, results in a eutectic alloy one that acts like a pure metal with a single melting (and solidification) point.
"Finding a substitute for lead that gave the solder similar properties was difficult," said Ames Laboratory senior metallurgist Iver Anderson. "With our basic understanding of alloys, we developed a tin-silver-copper alloy that offered a lower melting temperature and greater strength than other lead-free alternatives being considered."