Study Of Thermal Transient Measurement For Multi-thermal Sources Of Power Devices And The Analysis Of Influence Factors

High junction temperature of electronic devices will lead to the reduction of performance, reliability and life expectancy and other failures. With the smaller size of devices and higher integration process, power density due to limited space is increasing, especially for multi-chip module(MCM) which is typically a multi-thermal sources device, heat dissipation has seriously impeded the development of multi-chip module. Thermal resistance is an important thermal parameter to characterize thermal performance of devices, the test of thermal resistance is inseparable for the study of thermal performance of electronic devices. So it has significance and application value to expand the research of transient thermal resistance testing technology for multi-thermal sources device.This thesis analyzed the thermal resistance testing principle based on electrical method of NPN transistor, tested samples at the conditions of different currents, case temperatures, pressures, voltages-current combinations with the same power, and summed up the influence rules of various factors on thermal parameters of devices. Based on these rules, the best transient thermal resistance testing conditions could be achieved. The feasibility of using linear superposition principle to characterize transient thermal impedance matrix was validated experimentally and theoretically based on the analysis of linear superposition principle. The expression of transient thermal resistance matrix function related to time was deduced according to RC network theory. The correctness of the transient thermal resistance matrix function was verified by using Origin software to fit and analyze the transient thermal resistance testing results. Integral structure function, the graphical representation of CAUER model which corresponds to the actual physical structure of devices was given. The transient thermal response curve processed by integral structure function was used to separate the structure of devices from the turning point of integral structure function, and each part of the separation corresponds to the thermal resistance of each layer of the device. Origin software and theoretical calculations were performed to verify the advisability of the extraction method for the integral structure function.