Development and Experimental Validation of a 3-D Solder Self-Alignment Model for Alignment Accuracy Prediction of Flip-Chip Assembly

We describe a 3-D model for predicting the self-alignment accuracy of solder flip-chip assemblies. The model was developed using a force optimization method based on an explicit regression model, and validated experimentally using flip-chip test vehicles. The experimental results correlate with the model prediction to within 3% for the lateral alignment and 2% for the standoff height. The effects of important manufacturing parameters such as solder volume variations and distributions, chip mass, and die tilt, on the post-assembly alignment accuracies were investigated and characterized with the model. This model can be used to aid in the design of flip-chip assemblies requiring high alignment accuracies, such as those found in optoelectronics packaging.