Impact of a Crack on Heat Flux in a Solder Joint between an Electronic Component Pin and a Printed Circuit Board

The paper discusses the thermal processes in a cracked solder joint between a component pin and a printed circuit board. For modeling temperature distribution in the solder joint, the 2D analytical model is used. The structure of the solder joint is divided into eight rectangular regions one of which is the crack. For all regions, the stationary heat conduction equation and the corresponding boundary conditions are established. The solution of the heat equation for each region is carried out by the analytical method. Using these solutions, the temperature distribution in the solder joint with the crack is determined. Based on the analytical solution for the temperature distribution the expressions for the heat flux through the soldered joint with the crack and for the thermal resistance of this joint are obtained. This approach is used to determine the dependencies of the heat flux and the thermal resistance on the crack length for the following location of the crack in the solder joint: in the middle of the solder zone; under the electrical component; alongside the pad of the printed circuit board.