Breakdown characteristics of silicone gel for power semiconductor device packaging under steep voltage rise rate

• Published in: Dianji yu Kongzhi Xuebao = Electric Machines and Control Vol. 29; no. 6; p. 63
• Main Authors: Su, Dazhi, Zeng, Fuping, Huang, Meng, Zhong, Hengxin, Chen, Rirong, Tang, Ju
• Format: Journal Article
• Language: Chinese; English
• Published: Harbin Harbin University of Science and Technology 01.01.2025
• Subjects: Breakdown; Defects; Electric equipment; Electric field strength; Electric fields; Electric potential; Electrical insulation; Electronic packaging; Field ionization; Power semiconductor devices; Silicones; Space charge; Voltage
• ISSN: 1007-449X
• DOI: 10.15938/j.emc.2025.06.007

The existing research shows that the insulation strength of silicone gel for power device packaging is greatly affected by the voltage rise rate at the edge of pulse voltage. Therefore, the focus is on the breakdown characteristics of silicone gel at a steep voltage rise rate. In this paper, a steep voltage rise rate breakdown experimental platform which was built based on the typical insulation structure of electrical equipment. The steep wave breakdown characteristics of silicone gel under different voltage rise rates under non-uniform electric field were studied, and the breakdown process of silicone gel was discussed. The results show that the field ionization theory can better explain the breakdown process of silicone gel. The generation of cavity defects will lead to the enhancement of collision ionization, which will promote the gradual expansion of the defect area and eventually breakdown. Under the slightly non-uniform electric field and the extremely non-uniform electric field, the breakdown field strength of the silicone gel decreases with the increase of the voltage rise rate, and the damage effect on the insulating medium also increases. However, due to the modulation of the space charge in the cavity defect, the breakdown field strength gradually stabilizes. There is an obvious "area effect" under a slightly non-uniform electric field, which makes the breakdown field strength of the silicone gel sample under a slightly non-uniform electric field smaller than that under a very non-uniform electric field. The research results can provide theoretical support for improving the packaging reliability of power semiconductor devices such as IGBT.