MAXIMIZING SOLDER JOINT RELIABILITY THROUGH OPTIMAL SHAPE DESIGN

The automated search techniques from the field of numerical optimizati on provide tools that enable optimal design of electronic packages in general, and solder joints in particular. However, there is considerab le difficulty in using these procedures for solder joints since the es timation of fatigue life is computationally very expensive. In this pa per, global approximation schemes based on designed experiments, linea r regression models, and artificial neural network models are develope d to approximate the fatigue life as a function of solder joint design parameters. Since these approximate surfaces are inexpensive to evalu ate, their use with the numerical optimization techniques lends to a c omputationally efficient method for optimizing electronic packages. Th e developed techniques are demonstrated using the 225 I/O Plastic Ball Grid Array (PBGA) package, manufactured by Motorola, Inc. An exact op timization of the solder joints (without approximations) is also carri ed out and used as a basis for comparing the accuracy and efficiency o f the developed methods.