The requirements of the new TCM (thermal conduction module) for the IBM Enterprise System/9000™ (ES/9000™) module generated a significant number of challenges for the physical and electrical designer. For example, the need to support more circuits meant that more signal and power conductors had to be provided. In addition, the requirement for faster performance called for materials with lower dielectric constants and the use of on-module decoupling capacitors. This paper describes these changes, the design considerations that were applied to signal transmission, and the approaches that were used to contain delta-I and crosstalk noise in the module. Finally, the test measurements used to qualify the module are explained. The result is a TCM that more than doubles the circuit density of the TCM used for the IBM 3090™ machines, with substantially greater speed and reliability.
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