Research and Application of Distributed Thermal Resistance Model for High-Reliability Power Circuit in Space Application

The power circuit for aerospace equipment includes power converters, drive circuit, etc. Due to the need to withstand extreme physical and environmental conditions such as high and low temperatures, vacuum environments,radiation,etc., thick-film assembly and hermetic sealing processes are usually used. With the high-reliability hybrid integrated circuits for aerospace applications developing towards high-density and high-power, the failure problems caused by heat dissipation have gradually become prominent. The concentrated heat generation of high-power components in the module is likely to cause local over-temperature failure. However, as a component of the complete machine system, the thermal model of the circuit product is greatly simplified during the thermal simulation process of the complete system, and cannot truly reflect the actual temperature of the internal power chip of the product. This article models and simulates a typical power hybrid integrated circuit based on FOLTHERM software, and measures the temperature distribution inside the module using infrared imaging technology. A distributed thermal resistance network model covering the power devices inside the module is proposed. Using the temperature of the reference point at the bottom of the casing as the benchmark, the model calculates the temperature of key power devices. The error between the calculated results, simulationresults, and measured results is less than 3°C. The model is compatible with the overall thermal network model of the system, improving the thermal simulation accuracy by more than 50% in the thermal simulation of the entire electronic system. This lays the foundation for precise thermal management of high-reliability aerospace electronic systems.