摘  要：当今世界，尤其是发达国家，虽然Sn-Pb钎料的工艺性能及物理性能较好，但是它的接头可靠性、材料的环境协调性甚至力学性能都已经无法满足日常的生产生活需要。随着使用者环保意识的逐渐加强和对自身身体健康越来越重视，世界电子工业都朝着电子产品无铅化的方向发展，包括中国在内的世界主流发达国家都在大力发展电子工艺的无铅化。目前已经投入生产的Sn-Bi系无铅钎料由于存在着质脆、塑性较差等问题，十分容易影响焊接接头的可靠性。而且，其界面IMC层微观形貌随着温度而发生改变也会影响电子产品的使用寿命。为了改善Sn-Bi系无铅钎料的性能，可以选择在二元钎料合金的基础上添加第三种金属元素，利用合金化的方法开发三元钎料合金。本文研究的是Sn-18Bi-xCu三元无铅钎料：Sn-18Bi、Sn-18Bi-0.3Cu、Sn-18Bi-0.5Cu、Sn-18Bi-1.0Cu。主要研究了母材成分为Cu时焊点与母材界面处IMC的微观组织形貌、界面IMC生长行为、断裂面的显微组织以及探究了Cu元素的添加如何对焊点的可靠性产生影响。添加Cu能够细化富Bi相，富Bi相以细小弥散的形式存在于钎料基体中，能够降低钎料合金的熔点。添加Cu也能够提高合金自身的抗拉强度，这主要是由于在合金基体中棒状Cu6Sn5金属间化合物起到的钉扎强化作用。对于Sn-18Bi-xCu/Cu焊点液态时效一段时间后发现，在同等条件下Sn-18Bi-1.0Cu/Cu焊点界面IMC层最薄。

关键词：Sn-Bi-Cu钎料；金属间化合物；显微组织；液态时效

Abstract：Nowaday, especially in developed countries, although the Sn-Pb solder process performance and physical properties are better than the others, its connector reliability, material, environmental coordination and mechanical properties have been unable to meet people's production and living needs. Coupled with the gradual strengthening of environmental awareness and the importance of their own health, electronic products and lead-free solder has become the world's electronics industry currents and trends. The world's major developed countries including China are vigorously developing the lead-free process of electronic technology. Sn-Bi solder has been put into production due to the existence of crisp, poor shape and other issues, easily to affect the reliability of welded joints. Moreover, the microscopic morphology of the interface IMC layer can change with the temperature and affect the life of electronic products. In order to improve the performance of Sn-Bi solder, you can choose to add a third metal element on the basis of the binary solder alloy, and use the alloying method to develop the ternary solder alloy. In this paper, Sn-18Bi-xCu solder is studied. Four kinds of solder are prepared according to the ratio: Sn-18Bi, Sn-18Bi-0.3Cu, Sn-18Bi-0.5Cu, Sn-18Bi-1.0Cu. The microstructures of the interfacial interface, the growth of interface IMC, the microstructure of the fracture surface and the influence of the addition of Cu on the long term stability of the solder joint are studied. It is found that the addition of Cu can refine the Bi-rich phase and the Bi-rich phase is present in the solder in the form of fine dispersion, which can reduce the melting point of the solder alloy. For the alloy itself, the addition of Cu can improve the tensile strength of the alloy, mainly due to the alloy matrix in the rod Cu6Sn5 intermetallic compounds play a pinning enhancement. For the Sn-18Bi-xCu/Cu interface, the IMC layer at the interface is the thinnest under the same conditions.

Keywords: Sn-Bi-Cu solder; intermetallic compound; microstructure; liquid aging

目  录

第1章 绪论 1

1.1 电子封装的无铅化发展 1

1.2 无铅钎料的发展 2

1.2.1 无铅钎料的开发 2

1.2.2 无铅钎料的研究现状 3

1.3 钎料基板间的固/液界面反应 4

1.4 焊点可靠性及液态时效机制 5