Twinstar - Dual Pentium~R Processor Module

摘要

The Twinstar MCM contains two Intel Pentium~R processors in a single 347 pin, 49.5 mm sq. plastic PGA package. The module consumes 50% less PC board area than equivalent single chip designs and eliminates 148 PWB routes between the processors. The dice are interconnected inside the package on a high density Cu/photo-BCB thin film substrate. The substrate is fabricated on a 150 mm polished aluminum wafer. The aluminum substrate is used as the ground layer as well as one electrode of a decoupling capacitor. A sputtered seed layer of Cr/Cu is deposited and the copper traces are electroplated up. The use of photo BCB (Cyclotene~(TM)) results in 20% fewer processing steps when compared to a previous Copper/Polyimide process. 16 μm lines on 62 μm pitch and 45 μm vias are typical. Substrate processing and reliability testing are described.