Time-Dependent Damage Coupled Constitutive Model Of Solder Alloy In Micro-Electronic Packaging At High Tempertaure And It's Application

The solder joints have become the weakest link of the electronic package component as the significant inelastic and creep strain in solder alloy are caused by the thermal mismatch between the solder material and substrate material under service and soldering processing conditions. Nowadays, the study on the cyclic deformation behavior of the solder joints under complicated cyclic loading at high temperature has been one of the key issues for the reliability and durability of soldering joints. Consequently, it is significant to conduct the time-dependent deformation investigation of the solder joints under complex loading conditions at elevated temperature, then to develop a new damage coupled time-dependent constitutive model, and to code it into the finite element software. The study can offer the theoretical plate for improving electronic packaging technology, and the proposed model can be used in the real electronic packaging engineering.The following studies on 63Sn-37Pb solder alloy were carried out in the paper.1. A range of strain rate, dwell time, loading shape.and amplitude cyclic experiments are carried out of 63Sn-37Pb solder alloy at the temperatures of 323K, 353K, 373K and 398K, respectively. And the effect of strain rate, dwell time, loading shape and amplitude on the deformation behavi(?)r of 63Sn-37Pb solder alloy are experimentally investigated. Some time-dependent deformation behavior of the material is explored.2. Based on the time-dependent deformation behavior of the material, in the framework of irreversible thermal-dynamics and continuum mechanics, a new visco-plastic constitutive model is proposed by modifying Sandia model and the model by Xianjie Yang, which can describe the rate effect, amplitude effect, loading shape effect and temperature effect very well. The determination approach for the model parameters is also given in the paper. Then, the proposed constitutive model is coded into ABAQUS software through FORTRAN by using the central difference numerical method. The comparison between the predicted results and the experimental ones shows that the proposed constitutive model can describe the time-dependen(?) behavior very well.3. The finite element implementation is carried out of the new constitutivemodel in ABAQUS. The internal variables are updated through the timediscretization of the constitutive model and implicit integration. Then, theconsistent tangent module used in the equilibrium iteration is deduced. Thevalidation of the implementation is verified through a series of loading cases.Finally, some simple structures for the solder material are analyzed by finiteelement simulation.