Calculation Of Elastic Fields Under The Influence Of Joule Heating And The Temperature Field In Microelectronic Solder Joints

With the electronic products gradually developing toward the multi-functional and miniaturization,assembly density continues to improve.A solder joint damage often lead to the failure of the entire package structure,which makes solder joint reliability attract more and more people’s attention.One of the main failure modes of solder joints is that th e solder joints are subjected to periodic stress and strain,resulting in initiation of cracks and failure of solder joints.Therefore,it is very important to study the elastic field distribution of solder joints under various conditions,which is of grea t significance to improve the reliability of solder joints and prolong the life of electronic products.In this paper,two-dimensional model and three-dimensional model of inverted chip solder joint are established by using Free Fem++.The effects of different stress boundary conditions,defects,Joule heat,thermal stress and elastic field distribution are discussed respectively.The simulation results show that:(1)The elastic fields of the microelectronic solder joint in the case of two-dimensional simulation is determined by the stress boundary conditions,the solder joint defect,the Joule heat and the temperature stress.The influence of shearing stress on the maximum equivalent stress in the solder joint is greater than that of the tensile stress.In the case of cracks in the solder joint,the maximum equivalent stress in the solder joint increases with t he increase of the crack length,which usually leads to fracture.With the presence of a hole,stress concentration occurs within the vicinity of the hole The effect of temperature field on the elastic field of solder joint is greater than that of external stress.The maximum equivalent stress in the solder joint increases as the input current density increases.(2)Under the condition of three-dimensional simulation,the shearing stress has much stronger influence on the elastic field of the solder joint under the same stress condition.The effect of the Joule heat ing on the temperature field of the solder joint is evident,and the maximum temperature in the solder joint increases with the increase of the input current density.The effect of thermal stress on the elastic field is greater than that of the external stress.The results of the three-dimensional case verify the results of the two-dimensional case.