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摘要Sn-3.0Ag-0.5Cu无铅钎料已广泛应用于电子封装中,但是与传统的Sn-Pb钎料相比，其抗冲击能力相对较差，且成本远远高于锡铅钎料。因此，为了改善抗冲击性能，降低钎料的成本，低银型无铅钎料成为研究的热点。本文对比分析了Sn-0.3Ag-0.7Cu和Sn-3.0Ag-0.5Cu两种无铅钎料的润湿性及力学性能，同时研究了焊后和高温时效 600h后两种钎料焊点的显微组织。结果表明：随着Ag含量的增加，钎料的铺展面积显著增加，不同钎焊温度条件下，钎料的铺展面积随着钎焊温度的升高而明显增大。Sn-3.0Ag-0.5Cu钎料焊点的拉伸力和剪切力也明显高于Sn-0.3Ag-0.7Cu钎料，但随着时效时间的增加，高银型钎料的力学性能下降速率略高于低银型钎料。焊后两种钎料对应界面层为Cu6Sn5，经150˚C时效 600h，界面金属间化合物的厚度随着时效时间的增加而增加。同时，界面层随着Ag含量的增加而增厚。40901
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毕业论文关键词：无铅钎料；铺展面积；界面层；金属间化合物
Study on the effect of aging on the properties and microstructure of lead-free solder / solder joints
Abstract
Sn-3.0Ag-0.5Cu lead-free solder is widely used in the electronic industry for packaging application. However, compared with the traditional Sn-Pb solder, its impact resistance is relatively poor, and the cost is much higher than the tin-lead solder. Therefore, in order to improve impact resistance and reduce the cost of solder, low Ag-content Sn-Ag-Cu lead-free solder has become a hot research. In this paper, the effects of Ag content on the wettability and mechanical properties of the solder joints were studied. Microstructures of Sn-0.3Ag-0.7Cu and Sn-3.0Ag-0.5Cu solder joints was also investigated under both as-reflowed and after high temperature aging conditions. The results show that, with the Ag content increasing, the spreading areas of Sn-Ag-Cu lead-free solder joint increase markedly, and the spreading area rises with the reflow temperature increased. In addition, the tensile and shear strength of Sn-3.0Ag-0.5Cu solder joints were also bigger than Sn-0.3Ag-0.7Cu However, with the increase of aging time, mechanical properties of high-Ag solder drop rate is slightly higher than the low Ag solder. Cu6Sn5 is detected at the as-reflowed interface. After isothermal aging for 600h, the thickness of intermetallic compound (IMC) is increased with the increasing of aging time, and the IMC layer thickness is increased with increasing of Ag content.
Keywords: lead-free solder; spreading area; interface layer; intermetallic compound
目录
摘要 Ⅰ
Abstract Ⅱ
第一章 绪论 1
1.1 无铅钎料研究背景 1
1.2 国内外的发展现状 2
1.3 无铅钎料市场前景 3
1.4 钎料在Cu基板上IMC的生成 3
1.5 IMC的研究意义 3
1.6 本设计研究主要内容以及设计来源 4
1.7 本章小结 4
第二章 钎料性能研究方法与试验过程 5
2.1 研究概述 5
2.2 试验所选设备 5
2.3 试验所需材料 5
2.4 钎焊试验过程 6
2.5 焊接后钎料的湿润铺展研究 6
2.5.1关于杨氏方程的介绍 6
2.5.2 润湿性试验 7
2.6 焊点力学性能试验 7
2.7 对时效试件进行抛光试验 8
2.8显微组织分析及IMC层厚度测量 9
2.9 本章小结 9
第三章 钎料湿润性测试试验结果及分析研究 10
3.1 研究概述 10