A Research Into Thermal Reliability Of BGA Solder Joint

With the improving requirements of micromation and lightweight of electronic products,SMT-chip is gradually widely applied,taking place of traditional-insertion-technology-chip,along with the increasing thermal power dissipation of single board.Due to its excellent thermal performance and electrical performance,BGA is rarely affected by mechanical damages compared with QFP device.Moreover,it can be massively produced when fitted on PCB with abundant I/O applications.However,the thermal fatigue of solder joints will be caused by thermal stress and alternative cycle,because of the CTE discrepancy between ceramic chip and PCB,the thermal parameter mismatch,and the power cycle of integrated circuit and integrated system.Therefore,the performance of solder joints will be degenerated and the reliability will be decreased,even leading to the invalidation of IC and IS and higher soldering failure rate which is around 85% among all SMT products,much higher than other devices or PCB.The author carried out certain researches and wrote this paper,in order to find out a reliable estimating method of the CBGA solder joints' service life,focusing on the thermal failure in heat cycling working condition.First of all,taking advantage of ANSYS,the thermal cycle's service life of this kind of products can be estimated.Secondly,a well-rounded solder joint's cracking monitoring system need to be built to supervise solder joints' cracking status when working in low-and-high temperature cycling environment with different soldering conditions,such as package structure,soldering flux,and solder ball shape,and make concerning pre-warnings.Meanwhile,the author sliced the cracked solder joints to analyze their cracking trends and detailed appearances in different soldering conditions and working environment.By comparing abundant testing data with simulation data,the author revised the ideal factors in simulation experiments,contributing to much more reliability of the estimating method to the service life of solder joint.