Application of robust design on the optimal process design of thermo-mechanical reliability of PBGA solder joint

Based on Robust Design (Taguchi Method) and Finite Element Method (FEM), the thermo-mechanical reliability of Plastic Ball Grid Array (PBGA) solder joint subject to an accelerated thermal cycling test condition is studied. Including PCB size, substrate thickness, die coefficient of thermal expansion (CTE), and solder joint CTE et al, 8 different control factors are considered for a Robust Design towards enhancement of the thermal fatigue resistance of solder joint by using a mixed-level orthogonal array. From the results, importance of these factors on the thermo-mechanical reliability of PBGA solder joint is ranked. The best parameter combination is A(1)B(2)C(3)D(1)E(2)F(1)G(3)H(1), in which the substrate CTE, solder joint CTE, the thickness of substrate, die CTE are the most important. The optimal design, after the comparative experiment with ANN (artificial neural network) and conformation experiment, has remarkable enhancement in thermo-mechanical reliability compared with the original design.