Steady-State Computer Simulations of Package Sealing Methods

A two-dimensional computer model of a 0.300 inch side braze package is developed. The steady-state energy equation is solved using the finite difference method. Nonlinear radiation, convection, and conductivity terms are handled using an iterative approach. The computer model is used to simulate hermetic package sealing by the selective placement of heat sources and heat sinks. The sealing methods include hot capping, resistance heating, and seam soldering. The results are experimentally verified using a specialized hot capping fixture and the temperature sensitive parameter (TSP) method. It is found that conduction is the dominant form of heat transfer to the package die. Thermal contact resistance between the package base and the heat sink has the greatest effect on the die temperature. Package construction and material are also important. For a source temperature of 454°C and a sink temperature of 24°C, the die temperature was found to vary between 36°C and 93°C, depending on the sealing conditions.