First level package design considerations for the IBM´s S/390 G5 server

Summary form only given. The recently announced S/390 G5 server has achieved many “firsts” in the enterprise server market segment. The most prominent achievement is the virtual elimination of the performance gap at the system level between CMOS and bipolar based microprocessor designs. To this end, many new technology elements were introduced to both the semiconductor and package technologies. Specifically, the microprocessor used many innovative circuit design concepts and an advanced CMOS technology (0.18 μm nominal effective channel length) to attain a peak operating frequency of 500 MHz in a chilled operating environment. To support this microprocessor performance with sufficient design margin, the first level package had to operate at 300 MHz under the same environmental conditions. This goal was achieved by the introduction of a glass ceramic MCM containing six layers of a polyimide thin film structure that provided an xy signal line plane pair sandwiched between a power and ground plane for the intra chip connections in addition to the redistribution wiring. This combination of a 127×127 mm glass ceramic MCM with full field thin film wiring was another technology first and its physical and electrical characteristics are presented here