The Real-time Measurement Research Of High Power Diode Junction Temperature Rise

The semiconductor device development with smaller size and higher integration, power diode is working in high density, high voltage and high current in pules working condition. Because of the high transient power density and transient temperate rising, the operation reliability of device is declined and the lifetime is shorter. To improve the reliability, the transient junction temperature measurement with high accurate is becoming more and more important.Measuring the thermal resistance is been take to monitor the transient junction temperature rise of the power diode, according to multiply the power and thermal resistance. However, the thermal resistance is varied with ambition temperature and power conditions and it will also affected by the condition of heat dissipation and the condition of measurement. The transient junction temperature rise measurement method by transient high current in real-time will avoid these problems.In this article, a transient junction temperature measurement method using transient high current is discussed in detail. The phenomenon of the calibration curve bended under high current is analyzed. The results, which are measured by the high transient current method, traditional electricity and infrared junction temperature measured, are compared. The errors are analyzed. The diode junction is measured by on-line measurement system under different pulse duty cycles, and variation characteristics are summarized. Moreover, real-time data acquire device system high-power diode temperature is designed. Topics include the following: 1. The calibration curve under high current is researched. Measuring the calibration1. The calibration curve under high current is researched. Measuring the calibration curves with pulse current(pulse 250μs and duty cycle 5%) under different temperature and analyzing the reason of the curves going bended.2. The result of large transient current method is compared with the traditional method of temperature measurement results. The diode junction temperature is measured by traditional method, infrared method, and transient high current under the same conditions. The measurement results were compared and analyzed the reasons for the deviate.3. The online real-time junction temperature measurement system is designed and performed. This system is consisting of computer, signal generator, driving circuit, power supply and some other instruments. When the system working, the diode isdrove by the pulse current with different duty cycle generated by the system, then the calibration curve is measured under pulse voltage with different duty cycle, respectively.4. The real-time acquire system is designed and performed. Using VEE programming control the source to obtain the diode voltage under turn on and turn off in real-time. The junction temperature rise of the diode is obtained by comparison with the calibration curve.