Temperature Distribution Imaging inside Power Devices by Real-Time Simulation

We propose an imaging method of temperature dis-tribution inside a power device in real-time. The imaging system was constructed by integrating a real-time moni-toring and a real-time simulation. The surface tempera-tures of a device under test (DUT) is monitored by in-frared cameras and a high speed temperature simulator calculates temperature distribution inside the DUT by using the surface temperatures as boundary conditions. Our system successively imaged inside temperature dis-tribution of a TO packaged power diode under power cycling test with frame rate of 1 fps.2017 International Conference on Solid State Devices and Materials (SSDM2017), Sendai International Center, Sendai, Japan, Sep.19-22,201

Infrared image correlation for thermal stress analysis of power devices

Thermal stress analysis is indispensable to improve the reliability of power devices. We propose a technique to observe a temperature distribution and a thermal strain simultaneously for thermal stress analysis of power devices. A temperature distribution is measured by an infrared (IR) camera and a thermal strain is measured by a digital image correlation (DIC) with IR images under a power cycling test. To apply DIC to IR images, we propose techniques to make a random pattern on the surface which can be recognized by IR camera even if a surface temperature is changed. This technique realises an observation with completely same field of view even in a localized area on power devices. This method provides an experimental means to verify simulation results of thermal stress analysis

Real-time imaging of temperature distribution inside a power device under a power cycling test

The analysis of temperature distribution in a power device package is essential to increase the reliability of power devices, because the temperature swing during the operation creates mechanical stress at the interfaces between these materials. However, the temperature distribution is difficult to obtain under operating conditions because of the limitation in the use of non-destructive methods to measure the inside temperature of the device. In this paper, we propose a method of real-time imaging of temperature distribution inside a DUT. This method is based on a “real-time simulation”. The real-time simulation was realized by combining surface temperature monitoring and high-speed thermal simulation. The thermal simulator calculates temperature distribution inside the package by using the monitored surface temperature as a parameter. We demonstrate our system with a TO-220 package device under a power cycling test. The system indicated a temperature distribution change in the package with a frame rate of less than 1 s and the temperature difference at the Si chip was within 2 °C by a comparison with that estimated from forward voltage drop