Recent Progress on Pb-free Electronics in IBM

Lead (Pb)-containing solders have been extensively used in microelectronic interconnect structures between various packaging levels. Since the RoHS enforcement date of July 1st, 2006 by European Union [1] is rapidly approaching, the transition from Pb-containing solders to Pb-free solders is accelerating in the electronic industry.

In IBM, considerable R&D efforts on Pb-free solders technology were conducted well before the RoHS and WEEE directives[2] were enacted by the European Union, as noticed in the early publication and patent literature [3-5]. An example of the application of Pb-free technology within IBM is the usage of Bi-Sn eutectic solder for low temperature wave soldering of PTH (plated through holes) in advanced multilayer printed circuit boards (PCB) since early 1970’s [6, 7]. IBM’s early work had led to the NCMS(National Center for Manufacturing Sciences) Pb-free solder project, the first industry-wide joint efforts to search for Pb-free solders. When the final report of the NCMS Pb-free project was published in 1997, it was dedicated to the memory of Roger Wild (former IBMer) for his pioneering work on Pb-free soldering technology in IBM[8].