Solder joint reliability study of 256 pin, 0.4 mm pitch, PQFP

In this paper, a comprehensive experimental and numerical study of the solder joint reliability for 256 pin, 0.4 mm pitch Plastic Quad Flat Packs (PQFPs) are presented. The reliability of solder joints were assessed through accelerated lifetime testing under the temperature range of -55/spl deg/C to 125/spl deg/C. Sample were progressively taken out at 1000 cycles intervals to study the change in microstructure such as grain coarsening, growth of intermetallics, initiation and propagation of thermal fatigue cracks. Temperature cycling results were modeled by 3-parameter Weibull distribution. The deformation history of solder joints was analyzed by three dimensional non-linear finite element method (FEM) involving thermal elastic-plastic-creep simulation. The plastic and creep strain ranges were used in life prediction models and compared to the experimental results. Satisfactory correlation was observed.