摘 要

由于传统Sn-Pb钎料的焊接强度和高温稳定性较差，且不符合环保要求，近年来无铅钎料的开发成为了新的研究课题。作为传统Sn-Pb钎料的替代品之一，Sn-58Bi无铅钎料合金如今广泛应用于电子封装技术中，但Bi相本身硬而脆，使得Sn-58Bi合金脆性大、延展性小，难以加工成焊片，针对此问题，国内外已有许多通过添加第三组元改善其加工性能的研究。本文着重研究Ag的添加对快速凝固Sn-58Bi共晶钎料组织与性能的影响。采用双辊法快速凝固技术制备Sn-58Bi-xAg共晶钎料薄带，利用光学显微镜、扫描电镜、综合热分析仪等实验仪器研究添加不同Ag含量对Sn-58Bi共晶钎料组织与性能的影响，寻找合适的Ag添加量，解决Sn-58Bi合金加工性能差的问题。

研究结果表明：添加0.5-1.0wt.%Ag可以细化组织，添加1.5wt.%Ag反而会使组织粗化，即随着Ag质量分数的增加，Sn-58Bi共晶钎料组织呈先细化后粗化的趋势；界面IMCs厚度随Ag含量的增加而加厚，显微硬度也随之增加，熔点几乎无变化，而润湿性随Ag的添加有所降低。焊接强度随Ag含量的增加先增大后减小，在Ag添加量为1.0wt.%时达到最大。

根据一系列实验测试结果，添加1.0wt.%Ag可以使Sn-58Bi共晶钎料得到最佳的组织和性能，在极大程度上改善Sn-58Bi的加工性能，使其成为性能更优良的电子封装材料。

关键词：无铅钎料；Sn-58Bi；Ag；显微组织；性能

Abstract

In recent years, the development of lead-free solder has become a new research topic because of the poor welding strength and high temperature stability of the traditional Sn-Pb solder and not meet the requirements of environmental protection. As one of the replacement of Sn-Pb solder, Sn-58Bi lead-free solder alloys are now widely used in electronic packaging technology, but the Bi phase itself is hard and brittle, which makes the Sn-58Bi alloy brittle, low ductility and difficult to be machined into solder. In this regard, there have been many studies in the world to improve its processing performance by adding third components. The effect of Ag addition on the microstructure and properties of Sn-58Bi eutectic solder is studied in this paper. The Sn-58Bi-xAg eutectic brazing strip was prepared by double roll rapid solidification technology. The effects of different content of Ag on the microstructure and properties of Sn-58Bi eutectic solder were studied by optical microscope, scanning electron microscope and comprehensive thermal analyzer. Finding suitable Ag content to solve the problem of poor processing performance of Sn-58Bi alloy.

The results of the study show that adding 0.5-1.0wt.%Ag can refine the microstructure, and the addition of 1.5wt.%Ag can make the microstructure coarser. That is, with the increase of the mass fraction of Ag, the microstructure of the Sn-58Bi eutectic solder is thinning and then coarsening. The thickness of the interface IMCs thickens with the increase of Ag content, and the microhardness is also increased. The wettability decreased with the addition of Ag. The welding strength increases first and then decreases with the increase of Ag content, and reaches the maximum when the Ag content is 1.0wt.%.

According to a series of experimental results, adding 1.0wt.% mass fraction of Ag can make the Sn-58Bi eutectic solder get the best microstructure and properties, improve the processing performance of Sn-58Bi to a great extent, and make it a better electronic packaging material.

Key Words：lead-free solders；Sn-58Bi；Ag；microstructure；properties

目 录

摘要..............................................................................................................................Ⅰ

Abstract........................................................................................................................Ⅱ

第1章 绪论..................................................................................................................1

1.1 电子封装.........................................................................................................1

1.1.1 电子封装概述......................................................................................1

1.1.2 电子封装的发展..................................................................................1

1.2 无铅钎料.........................................................................................................2

1.2.1 传统Sn-Pb钎料的危害......................................................................2

1.2.2 无铅钎料的发展..................................................................................2

1.2.3 常见的无铅钎料..................................................................................2

1.3 Sn-58Bi无铅钎料............................................................................................2

1.3.1 Sn-58Bi无铅钎料的特点.....................................................................2

1.3.2 第三组元对Sn-58Bi共晶钎料的影响...............................................3

1.4 Ag对钎料的影响.............................................................................................3

1.4.1 Ag的基本性能......................................................................................3

1.4.2 Ag作为第三组元对钎料的影响..........................................................4

1.5 快速凝固.........................................................................................................4

1.5.1 快速凝固基本原理..............................................................................4

1.5.2 快速凝固方法......................................................................................5

1.5.3 快速凝固的特征..................................................................................6

1.6 研究意义与内容.............................................................................................6

1.6.1 研究意义..............................................................................................6

1.6.2 研究内容..............................................................................................7

第2章 实验方法..........................................................................................................8

2.1 快速凝固技术制备Sn-58Bi-xAg共晶钎料薄带.........................................8

2.1.1 实验装置..............................................................................................8

2.1.2 工艺参数..............................................................................................8