First- and second-level packaging for the IBM eServer z900

This paper describes the system packaging of the processor cage for the IBM eServer z900. This server contains the world’s most complex multichip module (MCM), with a wiring length of 1 km and a maximum power of 1300 W on a glass-ceramic substrate. The z900 MCM contains 35 chips comprising the heart of the central electronic complex (CEC) of this server. This MCM was implemented using two different glass-ceramic technologies: one an MCM-D technology (using thin film and glass-ceramic) and the other a pure MCM-C technology (using glass-ceramic) with more aggressive wiring ground rules. In this paper we compare these two technologies and describe their impact on the MCM electrical design. Similarly, two different board technologies for the housing of the CEC are discussed, and the impact of their electrical properties on the system design is described. The high-frequency requirements of this design due to operating frequencies of 918 MHz for on-chip and 459 MHz for off-chip interconnects make a comprehensive design methodology and post-routing electrical verification necessary. The design methodology, including the wiring strategy needed for its success, is described in detail in the paper.