Lead-free solder solutions for electronic packages
Lead is a toxic heavy metal. It has recently been removed from gasoline, paints and other materials in order to reduce the risk of lead poisoning. The IMECAT project, supported by the GROWTH Programme, aimed to remove lead from another common application - solders. IMEC, a top-notch research centre located in Belgium, began by reviewing all previous research into lead-free alternative alloys. Several promising compounds were identified and their material properties (e.g. brittleness) were evaluated in the laboratory setting. Finally, IMEC turned to Finite Element Models (FEM) to simulate normal wear and tear in order to derive expected lifetimes. Various electronic package types were evaluated, including under-filled flip chips, Polymer Stud Grid Arrays (PSGA), Ball Grid Arrays (BGA) and Chip Scale Packages (CSP), and compared with a tin-lead (SnPb) benchmark. IMEC discovered that increasing the silver (Ag) content raises the temperature at which the solder becomes brittle, but it may not be appropriate for low temperature applications. They also identified the conditions under which the different package types may develop cracks or other problems that can lead to solder failure. IMEC has moved to copyright its IMECAT research results, which will contribute to de-leading the electronics industry.
