Thermal Elastic-plastic Analysis Of Cbga Under Cycling Load

Electronic packaging is a technology which packages intergrated circuit using insulating plastics and ceramics and a connection between semiconductor die and electronic system. With the development of semiconductor and penetrating other industries, electronic packaging has made a significant progress in three decades. Today, electronic packaging not only provide chip protection, but also be satisfied with increasing performance, reliability, heat dissipation and power distribution in some cost. Reliability performance is the key people consider. Stress in solder joints leads to invalidation which is due to coefficient of thermal expansion mismatches in different materials.The effect of underfill in ceramic ball grid array(CBGA) package under thermal cycling load is studied in this paper by using double-scale homogenization theory and finite element nonlinear ananlysis.Firstly, combining double-scale homogenization theory and high order discrete plate using thermal elastic-plastic increment theory, taking account of viscoplastic behaviour of solder joints, it builds nonlinear thermal elastic-plastic model and double-scale homogenization constitutive equation of CBGA.Secondly, using Rayleigh-Ritz method, it gets macro and micro ananlysis solutions of CBGA. Comparing with numerical result, it approves right. It also takes accout of loading velocity, material properties and model structure parameters and provide theoretics for design of CBGA.It simulates nonlinear finite element mechanics behaviour of CBGA under thermal cycling load with ANSYS by using 3-D model. It analyses the change of stress and strain of solder joints when model is in heat increasing, heat preservating and heat decreasing. Finally, it gets solder jiont where most easily happens invalidation by stress strain hysteresis loop and provides proof for further studying reliability of CBGA.