IGBT模块热应力下的分层失效分析

Analysis of delamination failure of IGBT module under thermal stress

利用ANSYS有限元分析软件,分析了在温度循环条件下没有焊层裂纹缺陷的IGBT模块和有焊层裂纹缺陷的IGBT模块的应力和应变分布。仿真结果表明:热应力主要集中在芯片和焊层接触的四个边角处以及芯片和塑封体接触的四个边角处。当纳米银焊层有裂纹缺陷时,在裂纹尖端处会出现应力集中现象,增大焊层所受的应力值;温度从低温增加到室温时,裂纹尖端的应力值和形变量随着温度的升高而减小,应力值从41.074 MPa减小到1.594 MPa,形变量从0.0197 mm减小到0.0074 mm;温度从室温增加到高温时,裂纹尖端的应力值和形变量随着温度的升高而增大,应力值从1.594 MPa增加到54.82 MPa,形变量从0.0074 mm增加到0.0273 mm。在极端低温或者高温的条件下,裂纹区域最容易扩展延伸。

ANSYS finite element analysis software was used to analyze stress and strain distribution in IGBT modules with and without solder layer crack defects under temperature cycle condition.The simulation results show that the thermal stress is mainly concentrated at the four corners of the chip,the welding layer contact,the four edges of the chip,and the plastic seal contact.When nano-silver solder layer has crack defects,stress concentration appears at the crack tip,which increases the stress value of the solder layer.As temperature restores from low temperature to room temperature,the stress and deformation at the crack tip decrease from 41.074 MPa to 1.594 MPa and from 0.0197 mm to 0.0074 mm respectively.As temperature increases from ambient to high temperature,the stress and deformation at the crack tip increase from 1.594 MPa to 54.82 MPa and from 0.0074 mm to 0.0273 mm respectively.The crack area can be extended easily under the extreme low or high temperatures.