A method for measuring residual stress of csp solder spot after welding

Abstract

The invention provides a method for measuring residual stress of CSP solder joints after welding. First, the influencing factors that have an impact on the residual stress value of CSP solder joints after welding are determined, and then the significant influencing factors that have a significant impact on the residual stress after welding are selected from the sensitivity analysis results. , establish a BP neural network with a momentum term, and perform a linear regression analysis on the correlation between the output value after training and the target output value to establish a nonlinear mapping relationship between the significant influencing factors and the residual stress value. The prediction of residual stress after spot welding provides theoretical guidance for further in-depth study of residual stress after CSP welding and improving the reliability of CSP welding after service.

Description

technical field [0001] The invention relates to the technical field of electronic component packaging, in particular to a method for measuring residual stress of CSP solder joints after welding. Background technique [0002] With the continuous development of electronic products in the direction of miniaturization, thinning, multi-function and high reliability, high-density, high-precision, fine-pitch and micro-scale in packaging technology have become an inevitable trend. Chip scale package (Chip ScalePackage: CSP) as a new type of packaging technology has emerged and has been widely used. It has the advantages of ultra-small packaging, high packaging density and good electrical and thermal performance. In the CSP package structure, the interconnect solder joints (ie, CSP solder joints) directly undertake the functions of electrical connection, mechanical support and heat dissipation. Usually, the failure of CSP devices is mostly caused by the failure of the solder joints. ...

AI Technical Summary

Problems solved by technology

At present, scholars at home and abroad have studied the influence of the change of the structural parameters of the solder joints on the residual stress of the solder joints, but the research on the residual stress of the solder joints is not sufficient. The ranking of the degree of influence of post-weld residual stress does not provide a prediction model for post-weld residual stress in welding spots to solve the problem of large residual stress calculation workload.

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