无铅焊点电迁移失效的多尺度研究

The microstructure evolution phenomena and the scale effect of solder joint exist in the service period, the interactions between the microscopic grain structure evolution and electromigration void evolution are studied from a multi-scale perspective; the impact of the microscopic grain structure evolution on the crystalloid mechanics characteristics of Pb-free solder and its failure mechanism are investigated; the electromigration failure mechanisms of Pb-free solder joint under multi-physical loads are fully studied. The electromigration accelerated test of Pb-free solder joints is carried out for studying the evolution of the microstructure and electromigration void from a phenomenological point of view. Based on the molecular dynamics simulation and the grain scale modeling, the vacancy relaxation properties and electromigration diffusion characteristics of the Pb-free alloy are investigated. Based on the tensile test and simulation of grain scale specimen, the impact of the microscopic grain structure evolution on the micro-mechanical properties of the Pb-free material and its failure mechanism are analyzed. By developing the electromigration finite element methodology with considering the effect of microstructure and void evolution, by combining the phenomenological relationship between the microscopic grain structure evolution and electromigration characteristics with the grain scale mechanical properties, the electromigration failure mechanisms of Pb-free solder joint are finally studied. Through the research of the key scientific issues on the electromigration failure, it will provide a theoretical and numerical basis for the IC design and electromigration failure control of the solder joints.

针对无铅焊点在服役过程中存在明显的微观晶粒结构演化现象和尺度效应，从多尺度角度研究了微观晶粒结构演化和电迁移微空洞演化的相互耦合关系、微观晶粒结构演化对无铅焊料晶体力学特性的影响和失效规律，最终系统研究多场载荷作用下无铅焊点的电迁移失效机理。基于无铅焊点电迁移加速实验，从现象学上探索无铅焊点的微观晶粒结构变化和电迁移微空洞的演化规律；采用分子动力学仿真和晶粒尺度模型，从原理上研究无铅合金的空位松弛特性和电迁移扩散特性；基于晶粒尺度拉伸的实验和仿真，研究微观晶粒结构对无铅焊料力学特性的影响和失效规律；建立晶粒尺度下电迁移微空洞演化的仿真方法，结合微观晶粒结构演化和电迁移特性的现象学关系和晶粒尺度下的微观力学特性，系统研究无铅焊点电迁移的损伤失效机理。 通过研究电迁移失效的关键科学问题，为IC设计和芯片互连焊点的电迁移失效防治提供依据。

针对无铅焊点在服役过程中存在明显的微观晶粒结构演化现象和尺度效应，从多个尺度的角度研究了微观晶粒结构演化和电迁移微空洞演化的相互耦合关系、微观晶粒结构演化对无铅焊料晶体力学特性的影响和失效规律，最终系统研究多场载荷作用下无铅焊点的电迁移失效机理。基于无铅焊点电迁移加速实验，从现象学上探索无铅焊点的微观晶粒结构变化和电迁移微空洞的演化规律；采用分子动力学仿真和晶粒尺度模型，从原子扩散以及界面强度的角度研究无铅焊料中晶体界面结构的可靠性，通过研究晶体取向对电迁移行为的影响，确定了更加适合作为焊盘材料的单晶结构；基于晶粒尺度拉伸的实验和仿真，研究微观晶粒结构对无铅焊料力学特性的影响和失效规律，拟合出了适用于微小尺度下的GTN模型本构参数；建立考虑损伤的电迁移微空洞演化的仿真方法，结合由原子迁移引起的应变场变化和电迁移特性的现象学关系和晶粒尺度下的微观力学特性，系统研究无铅焊点电迁移的损伤失效机理。通过研究电迁移失效的关键科学问题，为IC 设计和芯片互连焊点的电迁移失效防治提供依据。