Thermal conductivity influence in SMT reflow soldering process

Abstract

One of the most used soldering processes for SMD components is the reflow process. For the PCBs one should expect the increasing of the components density and interconnection density together with the continuous reducing of component size and weight. It is well known how important it is for a proper soldering process to have the temperature distribution on the junction point between component pins and the corresponding pads. Mainly convection and radiation realize the temperature distribution in the reflow oven. Usual thermal conduction is treated to study the dissipation characteristics from a structure to the environment. In case of SMT assembly it is reversed, the influence of inside environment of a reflow oven acts on the assembled structure. The way of heat transfer and physical properties of the subassemblies are very important to obtain reliable product; "zero defects". The paper has two main goals. First, to present a simple method to realize a map of heaters according with the oven's geometrical profile. This is necessary for mathematical modeling, computing and/or simulation. In the second part this method will be emphasized.