Thermal analysis of a ceramic microelectronic package has been performed for six configurations under prescribed free and forced convective conditions. The corresponding three-dimensional temperature fields, and thus, the complex heat flow patterns within the package have been determined. The predicted temperatures compare favorably with the experimental data obtained using a 44-lead quad package. It is observed that, in forced convection, there is no significant reduction in the junction temperatures when the package is mounted in the cavity-down configuration. In free convection, filling the cavity with helium also results in small reductions in temperatures. On the other hand, conditions existing at the back surface of the board have a fairly significant effect on the junction temperature. Although essentially negligible in the forced convection cases, thermal radiation accounts for about one-fifth of the total heat transfer from the package in the free convection cases.

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