ABSTRACT
Beginning in 1991, the microelectronics community worldwide became increasingly aware of the possibility of being required, by law, by tax, or by market pressure, to replace tin-lead eutectic solders in electronic assemblies. Over the next 10 years that followed, separate groups formed in the United States, Europe, and Japan to examine solder-based alternatives to tin-lead eutectic solder and to understand the implications of such a change before it becomes necessary. Lead-free solder research projects from industrial, academic, and national laboratory groups are described in the Lead Free Soldering report sponsored by the UK Department of Trade and Industry [1]. The time line for comprehensive national or regional studies, shown in Figure 1, illustrates the long-term commitment to develop lead-free solder assemblies. The following studies are featured in this chapter: the National Center for Manufacturing Sciences (NCMS) Lead-Free Solder Project and the NCMS High-Temperature Fatigue-Resistant Solder Project from the United States, the Japan Institute of Electronics Packaging (JIEP) and Japan Electronic Industry Association (JEIDA) projects from Japan, and the IDEALS Lead-Free Solder Project from the European Union (EU). Based on these studies, the microelectronics community gained sufficient experience with the performance of lead-free solders to begin addressing lead-free assembly to assess lead-free issues, including manufacturing yield, process windows for complex boards, and component survivability. Results from these five studies are compared with subsequent data obtained by Motorola and IBM. Progress on more recent national and/or industrial sector groups investigating lead-free solders, such as the National Electronics Manufacturing Initiative (NEMI) Lead-Free Task Force and the High Density Packaging Users Group (HDPUG) is also outlined. Updates and information obtained by these groups can be found at https://www.nemi.org, https://www.leadfree.org, and https://www.lead-free.org.
