RELIABILITY COMPARISON OF 2 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 max imize electrical performance, reduce card real estate, and improve man ufacturing process yields. In support of the PowerPC(TM) family of mic roprocessors, 21 mm CBGA packages (256 leads) were used to evaluate tw o different ball metallurgies-90/10 Pb/Sn and 62/36/2 Sn/Pb/Ag. Test m odules were assembled to printed circuit cards and cycled at 0 to 100 degrees C and -40 to 125 degrees C to evaluate the relative fatigue be havior of the interconnections. Ball attach techniques and module-to-c ard assembly processes are described, including screening, placement, and reflow. Failure mechanisms and fatigue reliability are discussed f or both metallurgies.