Study On Prediction Method Of Thermal Fatigue Life For BGA Solder Joints With Random Viod

Thermal fatigue of solder joints is one of the main failure mechanisms of avionics in the working environment.Electronic packaging in the manufacturing process,the solder joints will inevitably produce internal void defects,and these void defects can have an indefinite effect on the thermal fatigue life of electronic packages.In this paper,the BGA package for aviation is used as the research object.By combining the finite element method and the probabilistic analysis,a method of predicting the thermal fatigue life of the solder joint with random voids is established.The influence of the void on the thermal fatigue life of the solder joint is studied.The main work and conclusion of this paper are as follows:(1)Non-destructive testing of internal defects of BGA solder joints,random feature parameters of the voids were extracted and statistically analyzed.Non-destructive testing of BGA package solder joints using X-Ray inspection equipment,measured void defects size,location and number of other characteristic parameters.Then,probability statistics for the characteristic parameters to obtain the distribution type and probability density function.The results show that the void radius obeys the normal distribution,the parameters of void location obey uniform distribution and the number of voids in a single solder joint obeys the Poisson distribution.(2)Research on thermal fatigue life prediction of solder joints in electronic package.Anand constitutive equation is used to describe the mechanical behavior of solder.Finite element method is used to solve the response of electronic package solder joints under temperature cyclic loading.The Darveaux life model is used to predict the thermal fatigue life of solder joints.The results show that the dangerous solder joint is located at the outermost position of the diagonal of the solder joint array and the maximum stress is located at the upper end of the dangerous solder ball in contact with the BGA area.(3)The prediction method of thermal fatigue life with random void solder joint is established.Combined with submodeling technique,a parametric finite element analysis sub-model of electronic solder joint is established,and polynomial response surface model is used to establish an agent model between random feature parameters of voids and the average viscoplastic strain energy density increment of solder joints.Finally,with Darveaux life model,establishing thermal fatigue life prediction method with random void solder joint.(4)The analysis shows that when the void area ratio is within the range of 0.6% ~ 18.8%,void defects do not reduce the thermal fatigue life of the solder joints.On the contrary,the thermal fatigue life of the solder joints increases as the void radius increases;When the void is located at the top of the solder joint near the BGA,the thermal fatigue life of the solder joint will be reduced relative to the void located at other locations,and the thermal fatigue life of the solder joint will also decrease the sensitivity to the void size.