Packaging technology for high performance CMOS server Fujitsu GS8900

Advanced packaging technologies for CMOS based high performance Fujitsu Global Server GS8900, released in late 1999, are introduced in this paper. Extending a new standard for technological leadership among large-scale enterprise servers, the GS8900 broke the 2000 MIPS barrier in performance for the first time by taking advantages of Fujitsu advanced 0.18 mum copper wiring process and chip/MCM/system packaging capabilities, delivering a doubled performance in comparison to its predecessor. The packaging technologies are uniquely characterized in several aspects. First, the high density stacked via type MCM-D technology features four pairs of CPU tightly coupled multiprocessor and large capacity second caches, the maximum processor terminal count is more than 10000. The processors are wired onto a multilayer thin film MCM substrate with 153 mum pitch high-density area array lead-free bumps. Secondly, maximum four CPU-MCMs, including 16 CPU processors, and 64 GB main memory modules are mounted on one multilayer system board of high frequency transmission properties. Each MCM is held through a high-density ZIF connector of around 3000 I/Os in a 1.27 mm pitch full matrix, which is assembled on the system board with lead-free solders. Thirdly, advanced cooling technologies are developed for improving the system performance and reliability. For the air-cooled model, high performance thermosyphons are developed for cooling of the MCMs, resulting reduced operating temperatures and one-third of weight comparing to that of an aluminum fin heatsink. For the turbo model, a low-temperature liquid cooling system is developed, resulting more than 10% performance boost over the air-cooled model, due to significantly reduced junction temperatures. N + 1 redundancy is pro-tided for the cooling system achieving a robust design with high reliability. In addition, two kinds of new lead-free solders were developed for flip-chip and system board assemblies, respectively, which show more than ten times higher reliability than those of prior lead-tin solders.