Packaging a 150-W bipolar ECL microprocessor

Recent developments in computer-aided design have made possible the highly automated layout of custom ECL (emitter coupled logic) circuits. These layouts have a much higher circuit and power density than gate array designs. It is now possible to place an entire ECL microprocessor, including floating point unit and cache memory, on one large die. To demonstrate the capability of supporting such a die, the authors built and tested low-cost, air-cooled single-chip packaging for a 12.6-mm×15.4-mm die. The PPGA (plastic pin grid array) package supplied the required current and maintained junction temperatures at less than 100°C while dissipating 150 W. This required innovation in five areas: die metalization, bondwire layout, PPGA package design, die attach, and cooling by a thermosiphon