Most high-reliability products either have an exemption or are out of scope of the RoHS Directive, yet the companies that manufacture these products are evaluating the impact of Pb-free SAC solder assembly on the reliability of these more demanding applications. Complex high-reliability assemblies often feature broad component mixes and pose many thermal challenges. Pb-free assembly challenges are exacerbated by the variability of component mass, large size and high layer count of PWBs, the need to rework, and the high likelihood of mixed through-hole, surface-mount and back-side assembly.      

“New soldering materials, maximum qualified component temperatures and primary attach and/or rework equipment all need to be addressed relative to reliability in the face of Pb-free assembly requirements,” said Joe Smetana, principal engineer, advanced technology, for Alcatel and co-chair of the iNEMI High-Reliability RoHS Task Force. “These recommendations were developed to communicate the needs of the high reliability segment to the supply chain and the relevant standards groups that must address these needs.”