Reliability comparison of two metallurgies for ceramic ball grid array

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 family of microprocessors, 21 mm CBGA packages (256 leads) were used to evaluate two different ball metallurgies-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 to evaluate the relative fatigue behavior of the interconnections. Ball attach techniques and module-to-card assembly processes are described, including screening, placement, and reflow. Failure mechanisms and fatigue reliability are discussed for both metallurgies. >