Li Longteng, Jing Bo, Hu Jiaxing
Prognostics and Health Management Lab, Air Force Engineering University, 1# Baling Road, Baqiao District, Xi'an 710038, China.
Materials (Basel). 2020 Apr 12;13(8):1813. doi: 10.3390/ma13081813.
The chip is the core component of the integrated circuit. Degradation and failure of chip solder joints can directly lead to function loss of the integrated circuit. In order to establish the degradation model of chip solder joints under coupled stress, this paper takes quad flat package (QFP) chip solder joints as the study object. First, solder joint degradation data and failure samples were obtained through fatigue tests under coupled stress. Three types of micro failure modes of solder joints were obtained by scanning electron microscope (SEM) analysis and finite element model (FEM) simulation results. Second, the characterization of degradation data was obtained by the principal component of Mahalanobis distance (PCMD) algorithm. It is found that solder joint degradation is divided into three stages: strain accumulation stage, crack propagation stage, and failure stage. Later, Coffin-Manson model and Paris model were modified based on the PCMD health index and strain simulation. The function relationship between strain accumulation time, crack propagation time, and strain was determined, respectively. Solder joint degradation models at different degradation stage were established. Finally, through strain simulation, the models can predict the strain accumulation time and failure time effectively under each failure mode, and their prediction accuracy is above 85%.
芯片是集成电路的核心部件。芯片焊点的退化和失效会直接导致集成电路功能丧失。为了建立耦合应力作用下芯片焊点的退化模型，本文以四边扁平封装（QFP）芯片焊点为研究对象。首先，通过耦合应力下的疲劳试验获取焊点退化数据和失效样本。通过扫描电子显微镜（SEM）分析和有限元模型（FEM）模拟结果得到了三种焊点微观失效模式。其次，利用马氏距离主成分（PCMD）算法得到退化数据的特征。发现焊点退化分为三个阶段：应变积累阶段、裂纹扩展阶段和失效阶段。随后，基于PCMD健康指数和应变模拟对Coffin-Manson模型和Paris模型进行了修正。分别确定了应变积累时间、裂纹扩展时间与应变之间的函数关系。建立了不同退化阶段的焊点退化模型。最后，通过应变模拟，该模型能够有效预测各失效模式下的应变积累时间和失效时间，预测精度均在85%以上。
