摘 要

Sn-58Bi共晶钎料因其低熔点、优良的力学性能以及价格低廉等优点，被国际上公认为Sn-Pb钎料的最佳替代材料之一。但是在凝固过程中Bi易出现偏析导致Sn-58Bi合金铸态组织粗大，脆性较大，塑性较低，钎焊接头性能差等缺陷。为了探究传统制备工艺对Sn-58Bi钎料组织性能的影响，发展新型制备技术，以达到改善钎料组织性能及提高产品质量、生产效率的目的。

本文以Sn-58Bi共晶合金为研究对象，采用铸造轧制法制备出共晶钎料薄带，借助光学显微镜、XRD、EPMA、SEM、DSC和MTS陶瓷拉伸试验系统等测试手段和方法，对Sn-58Bi钎料薄带的显微组织、物相组成、成分分布、熔化特性、润湿性和焊接强度进行了研究分析，并与快速凝固技术制备Sn-58Bi共晶钎料的组织性能进行对比。

研究结果表明：普通铸造轧制Sn-58Bi共晶钎料的显微组织中没有树枝晶，最终显微组织中只有-Sn和Bi两种组成相均匀分布；快速凝固态钎料组织中无初生-Sn相，为全共晶组织，与铸轧态显微组织相比，晶粒尺寸较小，组织细化且分布均匀。快速凝固态共晶成分中Sn和Bi的含量分别为43.33%和56.67%，相比于铸轧态（48.56wt.%Sn和51.44wt.%Bi）更加接近于理论成分（Sn/Bi=42/58）。两种不同工艺制备钎料的性能好坏有所不同，快速凝固技术制备Sn-58Bi共晶钎料的熔化性能、润湿性能、焊接强度均优于普通铸造轧制法制备的钎料。

关键词：Sn-58Bi共晶钎料；铸造轧制；显微组织；性能

Abstract

Sn-58Bi eutectic solder has been widely recognized as one of the best alternative materials for Sn-Pb solders due to its low melting point, excellent mechanical properties, and low cost. However, in the solidification process, Bi tends to segregate and lead to coarsening of the as-cast microstructure of the alloy, and Sn-58Bi has the disadvantages of high brittleness, low plasticity, and poor brazed joint performance. In order to explore the influence of the traditional preparation process on the microstructure and properties of Sn-58Bi solder, a new type of preparation technology was developed to achieve the purpose of improving the properties of the solder and improving the product quality and production efficiency.

In this study, the Sn-58Bi eutectic alloy was prepared into a eutectic solder thin strip by casting and rolling.The microstructure, phase composition, composition distribution, melting characteristics, wettability and welding strength of the Sn-58Bi brazing alloy ribbon were studied and analyzed by means of optical microscopy, XRD, EPMA, SEM, DSC, and MTS ceramic tensile test systems. Finally, the microstructure and properties of Sn-58Bi eutectic solder prepared by rapid solidification were compared.

The results show that there are no dendrites in the microstructure of ordinary cast and rolled Sn-58Bi eutectic solder. In the final microstructure, only the two Sn–58Bi components are evenly distributed; in the microstructure of rapid solidified solder, there is no primary structure. The Sn phase is a fully eutectic structure. Compared with the as-rolled microstructure, the grain size is small, and the microstructure is refined and distributed uniformly. The contents of Sn and Bi in the rapidly solidified eutectic composition are 43.33% and 56.67%, respectively, which are closer to the theoretical composition (Sn/Bi=42/58) than those in the as-rolled state (48.56wt.% Sn and 51.44wt.%Bi) . The performance of brazing materials prepared by two different processes is different. The melting properties, wettability, and welding strength of Sn-58Bi eutectic solder prepared by rapid solidification technology are better than those of brazing materials prepared by ordinary casting and rolling methods.

Key words: Sn-58Bi eutectic solder; casting and rolling; microstructure; properties

目 录

摘 要 I

Abstract II

第1章 绪论 1

1.1 电子封装发展现状 1

1.2 电子封装材料 1

1.3 无铅钎料概述 3

1.3.1 无铅钎料的研究背景及性能要求 3

1.3.2 无铅钎料分类 3

1.4 Sn-Bi钎料研究现状 4

1.4.1 Sn-Bi钎料的性能特点 4

1.4.2 Sn-58Bi钎料性能改善 4

1.4.3 钎料薄带制备技术 5

1.5 主要研究意义及内容 5

1.5.1 研究意义 5

1.5.2 研究内容 5

第2章 实验过程 6

2.1 钎料薄带的制备 6

2.2 钎料的显微组织观察 6

2.2.1 金相制备及显微组织观察 6

2.2.2 X射线衍射分析 7

2.2.3 电子探针X射线显微分析 7

2.2.4 扫描电子显微分析 8

2.3 钎料的性能测试 8

2.3.1 熔化性能测试 8

2.3.2 润湿性能测试 8

2.3.3 焊接强度测试 8

第3章 Sn-58Bi钎料薄带的组织与性能分析 9

3.1 Sn-58Bi共晶钎料显微组织及物相分析 9

3.2 Sn-58Bi钎料薄带电子探针微区形貌及成分分析 10

3.3 Sn-58Bi钎料的性能分析 13

3.3.1 熔化性能分析 13

3.3.2 润湿性能分析 14

3.3.3 焊接强度分析 15

3.4 与快速凝固技术制备的钎料薄带进行组织和性能对比 17

3.4.1 Sn-Bi二元合金相图 17

3.4.2 显微组织对比分析 18

3.4.3 性能对比分析 20

第4章 结论 24

参考文献 25

致 谢 27

第1章 绪论

1.1电子封装发展现状

安装集成电路内置芯片时外用的管壳即为电子封装，它能够保护和支撑集成电路内置芯片，同样还起着芯片的散热、绝缘以及与外电路连接的作用，可以增强环境适应能力。采用组装、焊接等方式将电子器件装配成独立系统的工艺技术即为电子封装技术。

在电子工业飞速发展的今天，随着现代电子信息技术的提高以及各种小型便携、多功能化和低成本的电子产品的问世，对电子封装也提出了更高的要求，从而发展出各种各样的封装技术，同时大量新工艺、新材料和新产品也不断产生。所以了解国内外电子封装技术的研究和发展现状，有利于新技术的创新。