Temperature distribution in IC plastic packages in the reflow soldering process

The temperature distribution in IC (integrated circuit) plastic packages in the reflow soldering process was investigated by both an experimental method and an analytical method. A temperature sensor composed of a p-n junction diode was embedded in a silicon chip and the chip was moulded in an actual plastic package to measure the chip temperature in the soldering process. Temperature variations of the chip during the dip-coating process, the vapour-phase reflow soldering, and the infrared reflow soldering were obtained. Finite-element method analysis was performed to develop an effective method for estimating the temperature distribution in the package. It is concluded that the combination of laboratory experiment, proper modelling of thermal boundary condition for the package, and finite-element analysis is an effective approach to find a satisfactory operative condition for a soldering process.<>