An integrated modelling approach to solder joint formation

The attachment of electronic components to printed circuit boards is a complex process where solder material undergoes a number of physical processes. This paper presents a modelling methodology which aims to integrate the governing physics taking place during the reflow process. A multi-physics simulation tool, Physica, is described which has the ability to simulate fluid flow, heat transfer including solidification, and stress evolution in an integrated manner. Results using this code are presented, detailing the mechanical response of two solder materials as they solidify and cool during the reflow process. Surface Evolver is a program used to predict the shape that a specific solder volume takes during joint formation. Details are given on how this code has been coupled with the above computational mechanics code. This coupling now provides a modelling route by which the shape, solidification history, and resulting stress profiles can be simulated in an integrated manner. Some preliminary results from this modelling framework are shown