基于埋置式基板的三维多芯片组件的翘曲研究

Warpage of Three-Dimensional Multi-Chip Module Based on Embedded Substrate

采用粘塑性有限元焊球模型以及大形变理论研究了三维多芯片组件(3D-MCM)的翘曲形态特征及其成因,结果表明基板腔室的存在使埋置式基板形成了双弓形翘曲形态,焊球的粘塑性使组件在温度循环中出现了翘曲回滞现象.基板中心空腔能改变基板翘曲形态,有利于减小基板翘曲,并有利于提高倒扣焊器件的热机械可靠性.底充胶能够增强3D-MCM的互连强度,并且能够有效降低3D-MCM温度循环后的残留翘曲度.底充胶的热膨胀系数(CTE)过高可能引发3D-MCM新的失效模式.3D-MCM的云纹干涉实验结果与数值分析结果相符较好.

The warpage issue of three-dimensional multi-chip module （3D-MCM） was discussed by using finite element （FE） simulation with viscoplastic solder model and large deformation theory. The comparison results show that the existence of the cavity in the embedded substrate results in the double-bow warpage mode of substrate, the viscoplasficity of solder balls results in the residual warpage of 3D-MCM during the temperature cycling. The cavity in the center of substrate can decrease the warpage of 3D- MCM.The application of underfill could strengthen the interconnection between device and subslrate, and decrease the residual warpage of 3D-MCM after temperature cycling.However,the large CTE （coefficient of thermal expansion） of underfill might incur other new failure models. Finally experimental results by Moir6 fringes pattern validated the predication of warpage by the simulation with viscoplastic solder model.