Research on BGA solder joint morphology in convection reflow soldering based on Fluent

Solder joint failure is one of the primary causes of electronic product failures. The morphology of BGA solder joints significantly influences their reliability. Although numerical simulation is a commonly used method to predict solder joint morphology, extensive existing studies simplify the joint shapes as spherical, cylindrical, or hourglass configurations, which substantially deviate from actual morphologies. To overcome this defect, this study establishes a morphology prediction model for BGA solder joints during convection reflow soldering using Fluent, based on principles of fluid dynamics and heat transfer. A geometric model of the BGA solder joint is established based on actual reflow soldering conditions, incorporating coupled multiphysics simulations of flow field, thermal field, and solid-liquid phase transition field. The dynamic melting and solidification processes of BGA solder joints are analyzed and summarized, revealing the evolution of joint morphology. When the solder joint height remains constant, the spreading diameter of the solder joint increases from 0.454 mm to 0.534 mm with the increase in temperature, and the contact angle decreases from 127° to 103°. When the solder joint height decreases, the contact angles between the solder and the substrate/PCB gradually decrease, and the spreading area gradually increases. Finally, the predicted solder joint morphology was compared and validated with the actual morphology. The simulated values of the solder joint morphology were basically consistent with the measured values. The good agreement between the experiment and the simulation proves that the method can effectively predict the shape of the molten solder joint. The method proposed in this paper paves the way for the prediction and optimization of solder joint shapes in electronic assembly.