钎焊界面反应产物高熵化及其效应的研究

Soldering is one of the most important technology for electronic packaging, performance of soldered joint is mainly determined by interfacial reaction products. Intermetallic compounds (IMC) are the most common products while failure often happens in brittle IMC layer, because local stress concentration always occurs in brittle IMC during service. However, the alloys contain at least 4 principal elements tend to form ductile high-entropy solid solutions rather than IMC. It is expected to enhance the performance of soldered joint after transferred the interfacial reaction product from brittle IMC to ductile high-entropy phase by using multi-components substrate in this reseach. The research contents are as follows: (1) The effect of substrate content, soldering process and service condition on interfacial reaction of Au-20Sn/Ni-Cu-X (X=Ag, Co and Fe) are characterized. The formation and reaction dynamics of high-entropy product is clarified. (2) The influence rules for high-entropy reaction products on shear strength and electrical conductivity of soldered joints are discussed. Furthermore, the effect of high-entropy products on joints performance are revealed. This research aims at providing scientific basis for design the soldered joints with excellent performance.

钎焊是一种重要的电子封装技术，焊点的性能主要受界面反应产物的影响。本项目针对钎焊界面反应产物主要为硬脆金属间化合物(IMC)相，焊点服役中易于在IMC层产生应力集中而导致焊点失效的问题，提出基于多主组元体系(≥4个主要组元)的高熵效应设计多组元基板，使界面生成塑性高熵产物，从而显著提高焊点性能的方法。具体开展以下研究：（1）研究基板成分、焊接工艺和服役条件对Au-20Sn/Ni-Cu-X（X=Ag、Co或Fe等）焊接体系界面反应的影响，阐明界面反应产物高熵化的过程与动力学原理；（2）揭示高熵固溶体相对焊点剪切性能和电导率的影响规律，探明界面反应产物高熵化的效应。本项目的研究为高性能钎焊体系和工艺的设计提供理论依据。

钎焊界面反应产物显著影响焊点的性能。本项目研究双脆性相Au-Sn共晶焊料的变形机制，阐明其超塑性变形机理，制备可应用于微电子封装的Au-Sn焊片；研究基板的成分、钎焊工艺和服役条件对Au-Sn钎焊焊点界面反应产物的影响规律，明确了钎焊界面反应产物高熵化的可行性；研究高熵界面反应产物微观组织形貌的演变，探明了高熵产物的生成机理；构建了界面产物高熵化-剪切强度之间的关联，大幅提高了焊点的剪切强度；提出了钎焊界面反应产物高熵化的设计方法，并在Au-Ge等其他焊料的钎焊体系中推广应用。本研究为高性能钎焊焊点的设计与制备提供理论基础和技术途径。