Comparative thermal performances of various substrate materials in a simple packaging application: actual versus predicted

A finite element study on the thermal performance of several substrate materials in a simple package application was carried out by D.P Button et al. (Proc. Int. Symp. on Ceramic Substrates and Packages, 1989). Materials examined were aluminium nitride, alumina, epoxy-glass, refractory-glass, and a composite consisting of alumina fibers in a polyimide matrix. Three cooling approaches were addressed: natural convection, forced convection, and a heat sink placed on the substrate face opposite the chip. In the present work, experiments to confirm these model predictions are described. Actual packages were prepared, closely resembling those addressed in the previous study. Thermal Test Chips manufactured by Texas Instruments Inc., were used to make the measurements. These chips are designed for this purpose, containing both resistive heating elements and temperature-sensing elements. The test packages of each material were successively placed in natural convection, forced convection, and heat sink environments, and their respective performances were monitored. The results closely support the conclusions of the earlier model study, although numeric differences are noted