无铅爆料合金表面腐蚀行为及微量元素的影响

IMR OpenIR

	无铅爆料合金表面腐蚀行为及微量元素的影响
	颜忠
学位类型	硕士
导师	冼爱平
	2012
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	材料学
关键词	无铅焊料微合金化大气腐蚀海洋环境 Xps Lead Free Solder Microalloying Atmosphere Corrosion
摘要	"自从无铅焊料出现以来，对于其有可能影响焊点可靠性的因素，包括润湿性、界面反应、力学性能、电迁移、锡晶须生长和液态焊料氧化等，人们都进行了大量的研究。然而，随着电子产品应用场合越来越广泛，其使用环境也越来越复杂。对于在苛刻环境下使用的电子产品，大气污染物、高湿度和Cl-等都极大地加速金属材料的腐蚀。因此，腐蚀问题将成为影响焊点可靠性的一个重要因素。本文选择工业上广泛应用的Sn-0.7Cu合金和Sn-3Ag-0.5Cu合金作为研究对象，采用微合金化的方法添加微量元素Ga和P，研究它们对Sn-0.7Cu合金抗腐蚀性能的影响。通过盐雾实验、大气暴露实验和动电位极化实验研究了不同合金的腐蚀行为。并采用扫描电子显微镜(SEM)、X-射线光电子能谱(XPS)、X射线衍射(XRD)等多种实验手段观察和分析了不同环境下和不同腐蚀时间后的合金表面腐蚀产物的形貌、成分和结构，分析微量元素在合金表面的分布和作用机理。实验结果表明：人工模拟海洋大气环境下，点蚀和均匀腐蚀(网状微裂纹为特征)是Sn-0.7Cu合金腐蚀初期的两种形式，且以点蚀为主。点蚀易于在富Cu区萌生并以触须状形式扩展。初期腐蚀产物由SnO，Sn(OH)2和 SnO•xH2O组成。后续腐蚀产物出现分层，龟裂且易于剥落。XRD分析表明合金长期的腐蚀产物主要为非晶态的SnO，同时还有少量SnCl2•2H2O；添加微量Ga能显著提高Sn-0.7Cu合金的抗腐蚀性能，主要原因是微量Ga在合金表面高度偏析，与Sn一起形成一层致密的保护性的复合氧化膜；作为对比，微量P的添加则影响不大；在工业大气环境下暴露试验结果表明，大气中的悬浮物颗粒对锡基合金的腐蚀形核和发展起主要作用。"
其他摘要	"Since the lead-free solders emerged, the reliability of soldering joint have been paid much attention by many researchers，and the factors include wettability, interfacial reaction, mechanical properties, electromigration, tin whisker growth，as well as oxidation of liquid solders etc. With the universal application，the electronic products may suffer more complicated environment today. For example，in outdoor environment, the air pollutant, and sometime high humidity and Cl- will dramatically accelerate the corrosion of metal materials. In this case, corrosion can become next issue that will affect the reliability of solder joint. In this paper, the Sn-0.7Cu and Sn-3Ag-0.5Cu alloy were selected as the sample，which have been widely used as the lead-free solders to replace the Sn-Pb solder in electronic industry now. The microalloying effects of trace Ga or P on the corrosion resistance of Sn-0.7Cu solder alloy were investigated also. The corrosion behavior of different alloys were studied by the salt spray test, atmosphere exposure and potentiadynamic polarization. The morphology, composition and structure of the corrosive products of the alloys in different environment were observed and measured by the Scanning Electron Microscope (SEM), X-ray photoelectron spectroscopy (XPS) and X-ray Diffraction（XRD）. The mechanism of the microalloying to inhibit the corrosion of the alloys is also discussed in present paper. The results show that，in the simulated marine atmosphere, the pitting and uniform corrosion are the two main forms of corrosion in the early stage of corrosion process, in which the pitting is the important form for the Sn-Cu alloy. The pits easily form at the Cu enrichment area on the surface of Sn-0.7Cu alloy, and then the pits propagate by the way of the tentacles. The initial corrosion products could be composed of SnO，Sn(OH)2 and SnO•xH2O, the latter the corrosion products have cracks, laminates and easily falls off, so it does not have corrosion resistance to the future corrosion at all. XRD result indicate that the long term corrosion products are mainly amorphous SnO, with a little SnCl2•2H2O. Doping with trace Ga in the Sn-0.7Cu alloy, the corrosion resistance of the alloy can be significantly improved in the salt spray test. XPS result shows that trace Ga segregates highly on the surface of Sn-0.7Cu alloy after solidification, which form a protective oxide film that can improve the corrosion resistance. As a comparison, doping with P in the Sn-0.7Cu alloy has little effect on the corrosion resistance. In the industrial atmosphere, the dust (suspended particulates) plays a significant role in the process of the atmosphere corrosion of the Sn based alloys, which can promote both the nucleation and development of the corrosion products."
文献类型	学位论文
条目标识符	http://ir.imr.ac.cn/handle/321006/64539
专题	中国科学院金属研究所
推荐引用方式 GB/T 7714	颜忠. 无铅爆料合金表面腐蚀行为及微量元素的影响[D]. 北京. 中国科学院金属研究所,2012.