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Trap Characteristics and Their Temperature-dependence of Silicone Gel for Encapsulation in IGBT Power Modules

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journal contribution
posted on 2022-06-14, 09:00 authored by Jiayu Xu, Xuebao Li, Xiang Cui, Zhibin Zhao, Shenyang Mo, Bing Ji
Silicone gel is a prevailing material for encapsulation in insulated gate bipolar transistor (IGBT) power modules. The space charge transport behavior in silicone gel is significant to evaluate the electrical insulation characteristics. This paper focuses on the trap characteristics and electrical properties of the silicone gel, which were rarely studied before. The experiments are performed on the surface potential decay of silicone gel after the charge injection. Then, the energy distributions of electron or hole traps are determined by a double-trap energy level model, which can be fitted by the Gaussian distribution. In addition, the mobilities of positive and negative charges are determined, which are 1.38 × 10-12 m2 ·V-1·s-1 and 1.74 × 10-12 m2 ·V-1 ·s-1, respectively. Furthermore, considering the heat as a byproduct resulting in thermal issues, the temperature-dependence of surface potential decay characteristics are also studied in this paper. When temperature rises, the decay rate of surface potential increases, especially when the temperature is higher than 80 °C. Finally, the contrastive analysis illustrates that the trap characteristics of silicone gel are between the trap characteristics in liquid-state material and solid-state material, which supports the phenomenon that silicone gel is more resistive to the sharp edges in power modules. This work can provide a useful reference for the design of encapsulation in high-voltage IGBT power modules.

History

Citation

CSEE Journal of Power and Energy Systems ( Volume: 7, Issue: 3, May 2021)

Author affiliation

School of Engineering, University of Leicester

Version

  • VoR (Version of Record)

Published in

CSEE JOURNAL OF POWER AND ENERGY SYSTEMS

Volume

7

Issue

3

Pagination

614 - 621

Publisher

CHINA ELECTRIC POWER RESEARCH INST

issn

2096-0042

eissn

2096-0042

Copyright date

2021

Available date

2022-06-14

Language

English