Packaging technology for high performance CMOS server Fujitsu GS8900

Abstract

Corresponding to high performance single-chip CPUs adopting 0.18 um process and copper wiring, high density wiring and multi terminal MCMs, on which the CPU and large capacity second caches can be mounted up to 4 pairs, have been newly developed. As for LSIs, bare chips are directly mounted on MCM substrates with 153 um pitch high density area bumps. The maximum LSI terminal count is more than 10,000. LSIs are connected to one another by multi layer high density fine pitch wiring, which are all made of copper and formed in thin films of MCM substrates. The supporting technologies, such as a high density multi terminal connector for the MCM, and a multi layer system mother board of high speed signal transmission correspondence where 16 CPUs and 64 GB main memories can be mounted for a maximum configuration, have been developed. Meanwhile, two kinds of newly developed lead free solders are applied in the system packaging considering of the environment protection. The following two methods have been developed in cooling technique. The high performance thermosyphon has been developed and adopted in the general air-cooled system. Moreover, in order to draw out the performance to its maximum by using the characteristics of CMOS LSI, a low temperature liquid cooling method, using a coolant around 0 degrees C, has been newly adopted to practical use in the large-scale system. With the liquid cooling scheme, not only the installation and maintainability are realized being equal to that for air-cooling, but also high reliability is achieved by a redundant cooling system that cools two or more MCMs.