Numerical and experimental study of the effect of thermocouple wire attachment on thermal characterization of a high performance flipchip package

Thermal resistance of an electronic package is a measure of the package´s ability to transfer the heat generated by the chip to the printed wiring board (PWB) or to the ambient. For a high performance flip-chip package, the primary heat transfer path for most applications is through a heat sink or cold plate attached to the package lid. Hence, a test method that evaluates the heat transfer path from the chip to the lid is the most relevant one. The thermocouple wire attachment can have a significant effect on the measurement of the surface temperature during the thermal characterization of a high-performance flip chip package. A cold-plate based test method is used for thermal characterization and internal thermal resistance is used as the basis of all comparisons. A detailed numerical study is presented to study the effect of heat conduction losses through the thermocouple wires on the package thermal resistance calculations.