Stress And Strain Analysis And Optimization Of Solder Joints Of Board-Level Components Under Combined Electro-Magnetic-Vibration Loading

In the actual complex working environment,board-level components are often subjected to external electromagnetic shock and vibration shock,which will cause a large number of troubles such as solder joint flexibility,dehiscence and deformation,resulting in failure of solder joints.So,it is essential to discuss the reliability of plate assembly solder joints under electric-magnetic-vibration composite loading.Combined with simulation analysis,experimental test and theoretical arithmetic,and analyzes the stress-strain of the solder joints under electro-magnetic and electro-magnetic-vibration composite loading.Firstly,the simulation model of board-level component is established,which includes CCGA,CSP and QFN chips.The stress and strain distribution of solder joints under combined electro-magnetic and electro-magnetic-vibration loading is analyzed.The results are as follows:the stress and strain size of solder joints of different types of components under electro-magnetic loading conditions is sorted as:CCGA solder joints>CSP solder joints>QFN solder joints;Under the condition of electro-magnetic-vibration loading,the order of its size is:CCGA solder joints>QFN solder joints>CSP solder joints;Under the two composite loading modes,the biggest stress and strain of the solder joint are all at the four corners of the CCGA solder joint matrix,and occur at the outer circumference of the upper end of the CCGA welding column get in touch with the solder joint.In addition,based on the electromagnetic theoretical analysis,the theoretical calculation values of relevant electromagnetic parameters of CSP solder joints under electro-magnetic loading are obtained,and compared with their simulation values to verify the accuracy of electro-magnetic simulation analysis of board component solder joints.Secondly,according to the CCGA solder joint with the biggest electro-magnetic and electro-magnetic-vibration catena stress and strain,the single factor analysis and range variance analysis are carried out for the relationship between the solder joint material and morphological parameters and their biggest stress.Under the two composite loading modes,the solder joint catena stress is the smallest when the solder joint material is 63Sn37Pb,and the solder joint catena stress is the biggest when the solder joint material is SAC357;The biggest electro-magnetic catena stress of CCGA solder joint diminishes first and then enlarges with the enlargement of solder joint volume,enlarges first and then diminishes with the enlarges of solder joint spacing,and diminishes with the enlargement of pad diameter;The biggest electro-magnetic-vibration catena stress of CCGA solder joint enlarges with the enlargement of solder joint volume and diminishes with the enlargement of solder joint spacing and diameter of the CCGA pad.When the confidence is 95%,the influence of solder joint material on the electro-magnetic catena stress of solder joint is obvious.In addition,the influence of solder joint material and solder joint spacing on the electro-magnetic-vibration catena stress of solder joint is obvious.Thirdly,for the CCGA solder joint,the morphological parameters of the solder joint are optimized by regression analysis and seagull algorithm to diminish the biggest electro-magnetic-vibration catena stress of the CCGA solder joint,and the optimum parameter combination of the CCGA solder joint is obtained as follows:the solder joint volume is0.072mm~3,the solder joint spacing is 1.67mm,The diameter of the pad is 0.9mm,and the corresponding simulation model is established with the optimal parameter combination,and the simulation value of the biggest electro-magnetic-vibration catena stress of the solder joint is 7.7722MPa,which is less than the minimum value of 8.9814MPa in the parameter combination test table,which realizes the optimized design of the morphological parameters of the CCGA solder joint.Finally,the experimental samples of QFN solder joints of board-level components were made,and the electro-magnetic catena strain measurement platform was built,and the strain measurement of QFN solder joints under electro-magnetic combined loading was completed.Then,the corresponding comparative experiments were carried out,and the accuracy of simulation analysis was verified according to the experimental results.