Micro-Alloying Effects on Joint Microstructures in Sn-Ag-Cu Solder Joints for High Reliability in Thermal Cycling
Authors: Dave Hillman and Iver Anderson, Ph.D. Company: Rockwell Collins and Iowa State University/Ames Laboratory Date Published: 7/1/2014
Abstract: The dominant lead-free solder alloy used by the high performance segment of the electronics industry is the Tin (Sn) - Silver (Ag) - Copper (Cu) family. The SAC305 solder alloy has acceptable thermal cycle properties but a number of other characteristics such as copper dissolution rate and drop shock resistance that makes it less than ideal for many product design teams. Significant research is being conducted to evaluate other lead-free solder alloys and the practice of micro-alloying. Micro-alloying permits the “tweaking” of a solder alloy to establish desired material characteristics. This paper describes a micro-alloying effort (SAC+X) of two solder alloys that are compared to SAC305 solder using thermal cycle testing per IPC-9701.