Comparative Research of Infrared Thermography and Electrical Measurement Method for the Thermal Characteristics Test of GaN HEMT Devices

In this study, the infrared method and the electrical test method are compared through the thermal resistance measurement of GaN HEMT device which is flip-mounted to the PCB board. In order to ensure the identical heat dissipation, measuring system of electrical method is integrated with heating platform of thermal microscope. The comparison results show that in the infrared test calibration process, the inconsistency in temperature of the device surface and the heating platform would cause the deviation from the infrared test results. This paper proposes a compensation method to correct the infrared thermal test results. After the temperature compensation, junction temperature was slightly lower than the electrical test results (162°C) instead of higher than that, which was consistent with the trend of theoretical analysis. In addition, the test shows that the bottom temperature of the device was not equal to the temperature of heating platform under both dry and wet condition. Compared with the electrical method, the surface temperature of the device is suggested to being measured under the dry contact surfaces when using the infrared method.