反向恢复期脉冲作用下高压晶闸管失效分析

本文搭建了高压晶闸管反向恢复期脉冲作用实验平台与特性参数测试平台,研究了高压晶闸管在反向恢复期不同阶段遭受脉冲冲击过程中的特性参数变化规律,并对退化和失效晶闸管拆片分析,结果表明：反向恢复期脉冲作用下高压晶闸管退化或失效表现为阻断能力的退化或丧失,由此引起晶闸管漏电流剧增,漏电流可作为表征晶闸管状态变化的特征参量；反向恢复期初期和中期冲击失效器件芯片上可见明显击穿点；反向恢复期中期冲击阻断能力退化芯片上可见热应力作用形成的圆斑；反向恢复期末期冲击失效器件可在芯片边缘与绝缘橡胶相接处见雪崩击穿闪痕。#$NL关键词：高压晶闸管; 电压脉冲; 反向恢复期; 失效分析#$NL中图分类号：TM461.4

Failure analysis of high voltage thyristor under impulse during reverse recovery period

To acquire the characteristic parameters which demonstrate the state of high voltage thyristor and to clarify its failure mechanism, an experiment platform which can not only generate high voltage pulses to thyristor at different moments during reverse recovery period, but also accurately measure its key characteristics is established, the change of characteristic parameters during the pulse impact process is studied, and the disassembly of the degraded and failed thyristors is analyzed. The results show that the damage of the thyristor can be mainly manifested as the reduction or loss of its blocking ability. Leakage current can be used as a characteristic parameter to estimate the state of the thyristor. For thyristors undertake voltage pulses in the begining and middle of the reverse recovery period, obvious breakdown spot can be seen on the silicon wafer surface. For thyristors which have a degradation on blocking ability, circular spots formed by thermal stress can be seen on the wafer. For failed thyristors undertake voltage pulses at the end of the reverse recovery period,the breakdown point is located where the edge of the silicon wafer meets the insulating rubber.