铜柱栅阵列互连结构的剪切行为

Shear behavior of copper column grid array interconnect structure

关键词:  铜柱栅阵列  剪切曲线特征  挠曲变形  剪切力

Key words:  copper column grid array (CuCGA)  shear curve feature  flexural deformation  shear force

摘要:

鉴于柔性铜柱与钎料球显著的性能差异,采用试验和数值模拟方法研究了铜柱栅阵列互连结构的剪切行为.结果表明,与焊球抛物线形的剪切曲线相比,阵列铜柱互连剪切曲线呈现不同的新特征,随剪切位移增加,剪切力首先呈大斜率的线性增加;随后由于焊柱开始挠曲变形,位移增加引起的应力增加被部分释放,故剪切力呈小斜率的线性增加;最后阶段,与BGA焊球相同,剪切力呈抛物线形变化,并在钎料/铜柱界面拉脱断裂.第一、二阶段曲线斜率均随铜柱长径比的增加和铜焊柱刚度的降低而减小.

Abstract:

Considering the significant difference in mechanical properties between the flexible copper column and the solder ball, the shear behavior of the copper column grid array (CuCGA) interconnect was studied by experimental and numerical methods. Results show that the shear curves of CuCGA interconnects presented obviously different new features, comparing with the parabolic shear curve of solder ball in the ball grid array (BGA) interconnect. The shear force linearly increased at first with a larger slope when the shear displacement increased, but it subsequently changed into a smaller slope due to the flexural deformation of Cu solder column and the partial release of stress caused by the increased displacement. The shear curves displayed the same parabolic shape as BGA solder ball in the final stage, and all pull-off fractures occurred in solder/Cu column interface. The curves slopes decreased with the increase of aspect ratio of the Cu column and the decrease of stiffness of Cu soldering column in the first and second stage.