Study of Impingement Cooling of Heat Sinks for LSI Packages with Longitudinal Fins

Abstract

This paper describes an experimental and a semi-empirical study of impingement cooling characteristics of heat sinks with longitudinal fins, which are suitable for LSI packages. The experiments are performed with a variety of longitudinal fins. For enhancing impingement cooling, one slot-shaped inlet orifice (slit) over the center of the heat sink is found to be the best structure. The optimum orifice width is about 1/6 of base width of the heat sink. The thermal resistance at the same volumetric flow rate and orifice width varies little with size of a gap between the fin top and inlet orifice ; however the gap of about 2 mm slightly reduces it. Correlations are proposed between the thermal resistance of the heat sink and the longitudinal fins. The estimation error for the predicted thermal resistance is found to be within ±25% of the experimental data.