The Influence of Solder Void on IGBT Temperature

The void in solder layer is the main factor that causes bad heat dissipation of IGBT (Insulated Gate Bipolar Transistor) module. Based on the seven-layer structure of IGBT, this article established a three-dimensional finite element model of IGBT module packaging structure and carried out its thermal analysis, then had a study on the effect of welding layer void on the temperature of IGBT chip. The overall distribution of IGBT module with or without solder hole is compared, meanwhile the article analyzed the effects of void type, size, shape, number and distribution on the temperature distribution of IGBT chips. The results show that the void in the solder layer of the chip has a great influence on the temperature of the chip. The influence of penetrating voids on chip temperature is greater than that of non-penetrating voids, the bigger the single hole is, the higher the temperature of IGBT chip. Voids of the same shape have greater influence on chip temperature at edge and corner positions than those inside the welding layer. The more concentrated the distribution of multiple holes, the higher the chip’s temperature. Therefore, in order to improve the reliability of IGBT, it is necessary to avoid voids in the chip welding layer during the packaging process.