Multi-stress Coupling Simulation And Reliability Analysis Of Solder Joints

The miniaturization and multifunctionalization of modern electronic devices and products require high-density packaging,which leads to a significant increase in the probability of reliability problems in the solder joints in the package.As the connection between the chip and the substrate,the solder joint not only provides mechanical support but also plays an important role in electrical connection.The life of the solder joint will directly affect the service life of electronic products.Therefore,research on the reliability and life of solder joints is very important.In the actual working environment,thermal stress,electrical stress and vibration stress have a significant impact on the reliability and life of the solder joint.Under temperature cycling conditions,due to the difference in thermal expansion coefficients between the solder joints and the contact parts,thermal stress and thermal strain will occur,which will cause the package components to warp due to expansion or contraction,which makes the components in the package,especially solder Deformation occurs in the spot,which induces the initiation and propagation of cracks,resulting in the failure of the solder joint.When the current density flowing through the solder joint gradually increases,it will cause significant electromigration.With the continuous impact of the electron flow,metal atoms migrate.As different types of atoms migrate at different speeds,Kirkendall voids will appear in the IMC layer of the solder joint,which will further deteriorate the electrical and mechanical properties of the solder joint,and even cause open-circuit failure of the solder joint;when the solder joint is in a vibrating environment.At the same time,the structural characteristics of the solder joints determine the degree of mechanical constraints of each part.The stress modes and sizes of different solder joints are different,which causes the solder joints to undergo loads such as fatigue,shear,and tension.Under the combined effect of multiple stresses,the failure mode and failure mechanism of the solder joint will become more complicated,and the coupling of multiple stresses will have a very direct impact on the reliability of the solder joint.Therefore,for the board-level package solder joints under the coupled thermo-electric-vibration stress,the finite element simulation of the structural response is studied in this paper,and the reliability analysis and life prediction of the solder joints are performed accordingly.The main contents are as follows:(1)The typical failure modes and failure mechanisms of solder joints under multiple stress conditions are studied.The relationship between stress and failure mechanism in a multi-stress environment is clarified,and the effect of multi-stress interaction on the failure mechanism of solder joints is analyzed.(2)The reliability simulation method of solder joints under the coupling of multiple stresses is studied.Using finite element modeling and analysis methods,the stress and strain characteristics of solder joints under the coupling of three typical stress fields and multiple stress fields are studied.(3)The reliability prediction methods of solder joints are studied.Based on the results of finite element simulation and analysis,the reliability prediction method related to the life characteristic quantity was studied through the physical failure model,and the life of the solder joint under multiple stress coupling was predicted.