Numerical modelling approaches to current reflow soldering applications: a brief overview

This paper presents a brief overview of numerical modelling approaches from recent years to current soldering applications. Reflow soldering is the primary interconnecting method for surface mount technology (SMT) applications. The solder paste is deposited onto the pads of the printed circuit board (PCB) and the surface mounted components (SMC) are placed onto them. During the reflow process the assembly is heated to melt the solder paste to form solder joints. Successful implementation requires low defect rate, rooting in proper material properties, process parameters and PCB design. Identification and elimination of these causes can be greatly hastened by the aid of simulation based on numerical modelling that grants in depth understanding of many phenomena that are not even measurable directly by conventional methods. The main focus was on the following topics: description of reflow types; summarisation of related partial differential equations (PDE) and their numerical solution methods; heat transfer aspects, temperature distribution characteristics, and thermomechanical stresses during reflow from modelling point of view.