Reliability Comparison of Two Metallurgies for Ceramic Ball Grid Array

Abstract

Surface-mountable ceramic ball grid array (CBGA) packages have proven to be attractive in a variety of applications as designers seek to maximize electrical performance, reduce card real estate, and improve manufacturing process yields. In support of the PowerPC/sup TM/ family of microprocessors, 21mm CBGA packages (256 leads) were used to evaluate two different ball metalturgies--90/10 Pb/Sn and 62/36/2 Sn/Pb/Ag. Test modules were assembled to printed circuit cards and cycled at 0 to 100/spl deg/C and -40 to 125/spl deg/C. Ball attach techniques and module-to-card assembly processes are described, including screening, placement, and reflow. Failure mechanisms and reliability are discussed for both metallurgies.