铜在液态焊料中的溶解动力学研究

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	铜在液态焊料中的溶解动力学研究
	杨泽焱
学位类型	硕士
导师	冼爱平
	2010
学位授予单位	中国科学院金属研究所
学位授予地点	北京
学位专业	材料加工工程
关键词	液态金属铜镍溶蚀金属间化合物
摘要	"电子及电器制造业中大量使用热搪锡工艺对铜导线焊接表面进行热镀锡，特别是铜线表面覆有绝缘涂层条件下，搪锡时需要在400℃左右的高温下进行，以有效去除铜引线表面的有机绝缘涂层，实现高效率的直接热镀锡。生产中发现在此高温下铜线将在液态锡中快速溶解，一些直径较细的铜导线甚至会完全溶解于液态锡，这一问题严重阻碍了生产的正常进行。因此如何有效的降低铜基体在液态锡中的溶解速度是电子及电器制造业中热搪锡工艺面对的一个急需解决的问题。本文在液态锡中加入少量Ni，研究它对铜基体在焊料中溶解速度的影响，并与目前工业中实际采用的Sn-Cu合金进行对比。实验中采用多种分析手段，如X-ray Diffraction (XRD)、Scanning Electron Microscope (SEM)等研究溶蚀后样品界面金属间化合物(Intermetallic Compounds, IMC)的化学组成和结构，分析液态锡中少量Ni抑制铜溶解速度的作用机理。实验结果表明：铜基体在所有液态锡或锡基合金中溶解动力学曲线均为与时间呈线性关系，温度对铜在液态锡中溶解速度影响很大；液态锡中添加少量Ni元素可以有效降低铜在液态锡中溶解速度，Ni的添加量在0.5wt%就有明显的效果，最佳添加量在1wt%左右。Cu在Sn基焊料中溶蚀开始时生成Cu6Sn5，晶粒呈弯曲、扭转、不规则的空心棒状，晶粒取向随机，以后逐渐发展成为规则的实心棒状晶粒。当液态锡中添加少量Ni（0.5-0.75wt%）时，界面反应产物为(Cu,Ni)6Sn5，它是一种Ni原子取代部分Cu原子后的置换固溶体，其中Ni含量与液态锡中镍的浓度成正比。由于这种界面反应产物的变化，使得铜的溶解速度得以减缓。特别地，当Ni的添加量达到1wt%时，在400℃以上高温，界面上生成了新的金属间化合物Cu3Sn和Ni3Sn2(420℃时还会生成Ni3Sn)，后者能更有效地减小铜在液态锡中的溶解速率。"
其他摘要	"In electronic and electrical manufacturing industries, hot dip coating tin is widely used for hot tinning on the welding surface of copper wires. While the surface of copper is covered with insulation coating, dip coating tin requires removing surface coating of copper wire at 400℃, which is the welding temperature, in order to achieve efficient hot tinning. However, it is found that the copper wires, which are used as base metal in soldering, dissolve rapidly in molten Sn-Cu solders according to the high temperature, a number of smaller diameter copper wires or even completely dissolve in liquid tin. This problem has seriouely hindered the normal production. Therefore, how to reduce the dissolution rate of Cu substrate in liquid solders is an urgent issue for hot tinning technology in electronic and electrical manufacturing industry. In present work, Ni was added in the solders, its influence on copper substrate’s dissolution behavior in solders was researched and its effect was compared with Sn-Cu alloy actually used at present. Meanwhile, variety of experimental methods such as X-ray Diffraction (XRD), Scanning Electron Microscope (SEM) and other methods are used to explore the chemical composition and structure of intermetallic compounds (IMC) formed on the interface of samples after dissolution, and the working mechanism of Ni element for the inhibition of dissolution is also analyzed. The experimental results show that dissolution kinetics curves of copper substrate were linear with time in all the liquid tin and tin-based alloys, temperature had a great influence on the dissolution rate of Cu in liquid tin. Adding a small amount of Ni in tin can effectively reduce the dissolution rate, the addition of 0.5wt % Ni has significant results and the best quantity for addition is around 1wt %. Cu6Sn5 was generated at the beginning of copper dissolved in Sn-based solders, the grains were bending, distortion, irregular, presented to be hollow rod, the tropisms were randomly oriented, and then gradually became regular solid rod-like grains. When adding a small amount of Ni (0.5-0.75wt %) in liquid tin, the interfacial reaction product was (Cu, Ni)6Sn5, which is a kind of substitution solid solution for Ni atoms replacing part of the Cu atoms, and the content of Ni was proportional to the concentration of Ni in liquid tin. According to the change of interfacial reaction products, the dissolution rate of Cu substrate slowed down. In particular, when the addition of Ni reached 1wt %, and the temperature was above 400℃, new intermetallic compounds, such as Cu3Sn and Ni3Sn2 appeared(at 420℃ Ni3Sn formed), the latter can reduce the dissolution of Cu in liquid tin more effectively."
文献类型	学位论文
条目标识符	http://ir.imr.ac.cn/handle/321006/64226
专题	中国科学院金属研究所
推荐引用方式 GB/T 7714	杨泽焱. 铜在液态焊料中的溶解动力学研究[D]. 北京. 中国科学院金属研究所,2010.