摘要
The solder joint reliability of a 0.5mm lead pitch, 240-pin quad flat package(QFP) was studied by nonlinear finite element analysis(FEA). The stress/strain distributions within the solder joints and the maximum plastic strain range of the solder joints were determined. Based on the calculated maximum plastic strain range the thermal fatigue life of the solder joints was calculated using Coffin-Manson equation. The influences of shape parameters including volume of solder joint, pad size and stand-off on the thermal fatigue life of the solder joints were also studied. The results show that the stress and strain distribution in the solder joint are not uniform; the interface between the lead and the solder joint is the high stress and strain region; the maximum stress and stain occur at the topmost point where the solder joint intersects with the inner side of the lead. The solder joint cracks should occur firstly at this point and propagate along the interface between the solder and the lead. The solder joint with the pad size of 1.25mm×0.35mm, the stand-off of 0.02mm and the solder volume of 0.026mm^3 has longer fatigue life than that of any others. These optimal parameters have been applied in practice to assemble the 240-pin, 0.5mm pitch QFP.
The solder joint reliability of a 0. 5 mm lead pitch, 240-pin quad flat package（QFP） was studied by nonlinear finite element analysis（FEA）. The stress/strain distributions within the solder joints and the maximum plastic strain range of the solder joints were determined. Based on the calculated maximum plastic strain range the thermal fatigue life of the solder joints was calculated using Coffin-Manson equation. The influences of shape parameters including volume of solder joint, pad size and stand-off on the thermal fatigue life of the solder joints were also studied. The results show that the stress and strain distribution in the solder joint are not uniform; the interface between the lead and the solder joint is the high stress and strain region; the maximum stress and stain occur at the topmost point where the solder joint intersects with the inner side of the lead. The solder joint cracks should occur firstly at this point and propagate along the interface between the solder and the lead. The solder joint with the pad size of 1.25 mm×0. 35 mm, the stand-off of 0.02 mm and the solder volume of 0. 026 mm^3 has longer fatigue life than that of any others. These optimal parameters have been applied in practice to assemble the 240-pin, 0.5 mm pitch QFP.
出处
《中国有色金属学会会刊：英文版》
EI
CSCD
2005年第4期807-812,共6页
Transactions of Nonferrous Metals Society of China
基金
Project(02336060) supported by the Natural Science Foundation of Guangxi Province , China
关键词
金属加工
焊接工艺
疲劳强度问题
非线性有限元分析
fine pitch
solder joint shape
nonlinear finite element analysis
thermal fatigue life
