Leachability of printed wire boards containing leaded and lead-free solder

Due to environmental Concerns and regulatory initiatives, electronics manufactures are replacing the tin/lead solder commonly used oil printed wire boards (PWBs) with alternative solders. To determine the potential waste management impacts of the alternative solders Versus the tin/led solder, two leaching tests on PWBs manufactured with five alternative types of solder were performed: the toxicity characteristic leaching procedure (TCLP) and the synthetic precipitation leaching procedure (SPLP). These tests arc commonly used in the US regulatory community to assess pollutant leachability in different disposal scenarios. The article discusses the application and limitations, of these tests. The five types of solders investigated were 63Sn/37Pb, 99.3Sn/0.7Cu. 95.5Sn/4Ag/0.5 Cu, 96Sn/2.5Ag/1Bi/0.5Cu and 42Sn/1Ag/57Bi. The leaching tests were conducted Oil four PWB sections. each with I unique configuration and solder density. The largest lead concentrations were observed front the PWBs containing Sn/Pb solder, with concentrations exceeding the hazardous waste toxicity charactcristic (TC) in TCLP leachates. Silver, the other regulated element used in the solders, was rarely detected. with none of the samples exceeding the TC limit for silver. High copper concentrations were observed and were determined to result from the PWB itself, not from the copper-containing solders. (C) 2007 Elsevier Ltd. All rights reserved.