TLM Modeling of Solder Joints in Semiconductor Devices

Transmission-line matrix (TLM) is an elegant technique for modeling heat flow in semiconductor devices. Unlike some other numerical methods a sense of the physical nature of the problem is retained and irregular boundaries, inhomogeneities, and temperature dependent thermal parameters can be easily incorporated. The inclusion of a layer of solder between a device and its PaCkage has a substantial influence on the temperature distribution. This theoretical paper investigates the effects of solder joint perfection and indicates the extent to which topographical methods such as infrared thermal imaging can give useful experimental results.