Thermal characterization of a 149-lead VLSI package with heat sink

High-power emitter-coupled logic (ECL) circuits in large pin-grid array (PGA) packages must be optimized for thermal dissipation in order to operate reliably in computer applications. The steady-state and dynamic thermal characteristics of a 149-lead hermetic PGA package are studied, with emphasis on three different configurations of a finned heat sink and on two types of fillers for the epoxy heat-sink-attach adhesive. The package described has high thermal performance in an air-cooled regime. Data are presented showing thermal resistance from junction to ambient as a function of number of heatsink fins and composition of heatsink-attach epoxy. At nominal conditions, thermal resistance (junction-to-ambient) of the selected five-fin heatsink and aluminum-filled epoxy adhesive is less than 6 degrees C/W at an airflow of 500 linear feet per minute. Also discussed is the junction-to-case thermal resistance, measured as per SEMI Standard G30-86. A value of 1.2 degrees C/W was measured for the package.<
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