Sn-Ag-Cu-Ni-Zn无铅焊料与Cu基体界面反应的扩散模拟和原位观测

焊接过程中焊料与基体的界面反应直接影响焊接服役性能，建立精准的扩散动力学数据库，并耦合热力学和原位实验是实现焊接界面反应定量描述的有效手段。本项目拟以Sn-Ag-Cu-Ni-Zn无铅焊料/Cu基体界面反应为对象开展如下研究：1）耦合扩散偶技术和数值回归法高通量测定多元无铅焊料合金固溶体相精准互扩散系数矩阵；2）基于CALPHAD方法获得无铅焊料合金液相和固溶体相原子移动性参数描述，并模拟回流焊接时Cu基体与液相焊料界面的溶解行为；3）集成反应扩散偶、电子探针、高温激光共聚焦显微分析等技术对Sn-Ag-Cu-Ni-Zn无铅焊料与Cu基体间化合物生长进行原位观测，并获得化合物的原子移动性参数。基于所建立的目标体系原子移动性参数数据库，实现无铅焊料/Cu基体焊接及长期服役过程界面反应的定量预测。项目的完成有望为Sn-Ag-Cu-Ni-Zn无铅焊料合金成分设计和界面组织调控提供理论支撑。

The interfacial reaction between solder and substrate can directly affect the service performance after soldering process. Establishing an accurate diffusion dynamics database to couple with thermodynamics and numerical simulation is an effective method to quantitatively study the welding interface reaction. This project is thusly intending to carry out the following research on the interface reaction between Sn-Ag-Cu-Ni-Zn lead-free solder alloys and Cu substrate: (1) Determination of chemical diffusion coefficients of solid solution phase in lead-free solder alloys via diffusion couple technique and new practical numerical regression method; (2) Establishment of an atomic mobility database for the liquid and solid solution phases of lead-free solder alloys, and simulating the interface dissolution behavior of solid Cu matrix and liquid solder during reflow soldering; (3) In-situ observation of the growth of compounds between Sn-Ag-Cu-Ni-Zn lead-free solder alloys and Cu substrate via a hybrid approach of diffusion couple, high-temperature microscope and electron probe micro-analyzer, and further construction of atomic mobilities for intermetallic compounds. Based on the established atomic mobility database of liquid, solid and intermetallic phases, prediction of the growth of intermetallic compounds at the solder/substrate interface during soldering as well as long-term service can be performed. The completion of this project can provide theoretical bases for the composition design and interface reaction control of the Sn-Ag-Cu-Ni-Zn lead-free solder alloys system.