Mechanical Stress Wave Noncontact Laser Detection Method of Power Semiconductor Devices—Observation of Low-Frequency Signals

Power semiconductor device condition monitoring technology based on the mechanical stress wave (MSW) is an important means to study device failure mechanisms and evaluate device reliability. However, MSW signals have mainly been detected through acoustic emission (AE) sensors for contact detection. The operating temperature of the device will affect the detection results, and the presence of MSW low-frequency components may be overlooked due to limitations in sensor performance. This article proposes an offline, noncontact MSW measurement method based on a laser Doppler vibrometer for power semiconductor devices. This method obtained the complete MSW signal generated during the switching process of power semiconductor devices, especially the low-frequency components below 20 kHz. Moreover, the proposed method exhibits greater sensitivity in detecting the high-frequency components of the MSW compared to contact detection. This study extends the detection methods and frequency ranges for the MSW in power semiconductor devices, thereby expecting to facilitate the generation and propagation mechanisms research of the MSW.