Modelling the self-alignment of passive chip components during reflow soldering

In my research a 3D model was created to investigate the restoring force arising and the self-alignment occurring during reflow soldering; and simulations were performed to examine the assumptions given by the model. Besides, experiments were carried out to verify both the assumptions and the simulation predictions. Passive components with the size of 0603 (1.5 × 0.75 mm) were placed with intended misplacements and their position was measured before and after soldering. Three cases were examined: how misplacements perpendicular to the longer sides of components affects the restoring force, how parallel misplacements affect the same, and how a sidewall metallization on the component influences that. Based on the results, it is shown that the degree of restoring force is higher in the case of misplacements perpendicular to the longer side of components (x-direction) than in the case of misplacements parallel to that (y-direction). However, in the case of y-direction misplacements, the restoring force increases when sidewall metallization on the components is present.

• Self-alignment of surface mounted passive components was investigated.
• Solder profile of surface mounted components was simulated with Surface Evolver.
• Solder profile simulations were verified with cross-sections of solder joints.
• The degree of self-alignment parallel to longer side of the components is lower.
• Self-alignment parallel to longer side can be improved with sidewall metallization.