MCM-D/C packaging solution for IBM latest S/390 servers

The G5, the most recent member of the S390 server family, was announced in May 1998. The multichip module (MCM) at the heart of the G5 system consists of 29 CMOS chips on a 127.5 mm glass ceramic substrate with 6 levels of th in films (TF) including 1 signal plane pair. System performance of the G5 e xceeds 1000 MIPS, This breakthrough performance resulted from the synergy c reated by combining IBM's leadership technologies in CMOS high frequency mi croprocessor design with advanced packaging and flip chip interconnections. From a substrate perspective, IBM moved from alumina ceramic with molybden um (Mo) conductor to cordurite/glass ceramic, and copper (Cu) conductor, an d from TF redistribution (4 levels) to TF wiring (6 levels). This paper dis cusses the TF implications from a change of substrate material and increase d wiring density, as well as the need to implement a polyimide cushion laye r as part of a pin grid array (PGA) fabrication process that supports 4224 I/O's.