Ag含量对Sn-Zn-Ag无铅钎料腐蚀性能的影响

在Sn-Zn共晶钎料中加入不同含量的Ag元素制成Sn-9Zn-xAg无铅钎料,利用失重法、扫描电镜的腐蚀形貌观察以及EDS成分分析,分析了Sn-9Zn-xAg无铅钎料在3%NaCl溶液浸泡腐蚀情况下的腐蚀行为,并与Sn-Pb以及Sn-Zn钎料进行比较.结果表明:随着Ag含量的增加,钎料合金的抗腐蚀性能有所提高.     

微电子组装中Sn-Zn系无铅钎料的研究与开发

无铅钎料的研究开发是我国电子材料行业目前面临的紧迫课题.其中Sn-Zn系无铅钎料具有低的熔点,优良的力学性能,能获得可靠的钎焊接头,且其原材料丰富、价格便宜,有望替代Sn-Pb钎料.但该系钎料易氧化,抗腐蚀性较差,目前还未得到广泛的采用.介绍了开发新型无铅钎料应满足的要求,及几种有潜力的Sn-Zn系无铅钎料.     

Sn-Zn-Bi-X(Ag,Cu)系钎料的断裂韧性研究

通过对两种具有代表性的无铅软钎料断口的分析,介绍了Sn-Zn-Bi-X(Ag,Cu)系钎料合金的断裂韧性的初步研究结果,发现Bi固溶于钎料基体导致了钎料合金脆性的增加,随着Bi含量的增加,脆性随之增大。同时发现,钎料的冷却方式对钎料的脆性倾向有较大的影响。     

无铅钎料对不锈钢的腐蚀性研究

相对于传统的Sn-Pb合金,无铅钎料在高温下对不锈钢的腐蚀性明显加强,从而造成波峰焊接设备的损坏。通过试验的方式,在450℃条件下将不锈钢材料、表面特殊氮化处理不锈钢、钛合金和铸铁浸入液态无铅钎料Sn-0.7Cu中720h,通过腐蚀界面的微观组织分析,研究了无铅钎料侵蚀不锈钢界面的机理以及几种材料的耐腐蚀性分析,从而为防止无铅钎料的腐蚀提供可靠的依据。     

无铅软钎料的研究现状与展望

随着国际上禁止含铅钎料使用日期的临近，无铅软钎料的研究开发与推广应用已迫在眉睫。综述了近年来国内外在无铅软钎料领域的研究开发情况，着重介绍了近一两年来的研究成果及应用情况，并指出目前国内对于该领域最值得关注的Sn-Zn与Sn-Ag两个系列无铅钎料的研究相对滞后，应当加快这方面的研究开发与实用化的步伐，争取早日赶上国际水平。     

锡基无铅钎料的性能研究与新进展

介绍了现阶段锡基无铅钎料的使用和生产情况,归纳了钎料合金的特点,综述了不同系列无铅钎料的熔化特性、焊后的剪切强度及可焊性等,总结了目前无铅钎料研究所取得的新成果、新进展以及存在的问题。从锡晶须,虚焊等方面指出了无铅钎料可靠性的不足,并提出部分解决方案,指出了无铅钎料的发展趋势和应用前景。     

Sn-Zn系钎料研究及应用现状

随着钎料无铅化的发展,Sn-Zn钎料以其低廉的成本,与SnPb钎料相近的熔点成为无铅钎料研究的重点.但是Sn-Zn钎料存在易氧化,抗腐蚀性差,润湿性差的问题,通常在SnZn钎料中加入不同元素,改善其性能.主要阐述不同添加元素Bi、Al、In、Re(稀土元素)、Ag、Cu、P和多元合金对SnZn钎料自身性能和钎料与Cu结合性能的影响,概述SnZn系钎料的工业应用现状.     

三种典型Sn-Ag-Cu无铅钎料的组织和性能研究

对比研究了三种典型标称成分的Sn-Ag-Cu钎料(即日本JEIDA推荐的Sn-3.0Ag-0.5Cu、欧盟IDEALS推荐的Sn-3.8Ag-0.7Cu和美国NEMI推荐的Sn-3.9Ag-0.6Cu)的显微组织特征、熔化特性、润湿性以及钎焊接头微焊点的力学性能等。结果表明,三种钎料的组织和性能非常接近。然而从性价比等方面综合考虑,Sn-3.0Ag-0.5Cu为三种钎料中最具优势的替代传统Sn-Pb钎料(共晶和近共晶钎料)的无铅合金。     

热力学计算在无铅钎料合金设计中的应用

依据CALPHAD方法进行相平衡计算过程中热力学模型的建立及其求解作了简要介绍，对热力学数据库的特征作了描述。对基于CALPHAD方法而开发的Thermo Calc系统的数据库及几个主要模块的功能作了概括的介绍。并针对在无铅钎料研究领域，利用ThermoCalc进行无铅钎料多元合金相平衡计算、预测液态钎料的表面张力和粘度以及钎料与基底之间形成的金属间化合物的驱动力的研究进展进行了总结。着重介绍了日本Tohoku大学材料系的研究人员开发的钎料合金热力学数据库。     

Ag对Sn-Pb电子钎料合金性能的影响

研究了Ag的合金化对Sn-Pb钎料合金材料性能的影响。并从钎料的润湿性能，机械性能及抗腐蚀性能等方面讨论了Ag的有利作用，研究表明，在一些特定条件下的电子元件的焊接，Sn-Pb-Ag钎料可部分地或全部地替代昂贵的遗金属钎料合金。     

无铅焊料的蠕变行为研究进展

无铅焊料已经逐渐代替锡铅焊料广泛应用于电子产品连接技术。但其在环境中的物理和机械性能,尤其是蠕变性能却低于锡铅焊料合金,成为无铅焊料可靠性的主要问题。综述了近些年来无铅焊料蠕变性能的研究,包括蠕变机制、蠕变本构方程、焊点尺寸、无铅合金成分、金属间化合物以及微观组织结构对蠕变性能影响等主要研究热点,并对此领域的发展做出了展望。     

电子产品无铅化的环保新问题

电子制造过程无铅化已是大势所趋。但目前研发的无铅焊料也存在一些问题:如所添加的合金元素也会污染环境并危害人体健康;大部分添加的合金元素储量有限;无铅焊料生产加工所消耗的能量大大高于锡铅焊料等。指出研发新的绿色互连技术、采取有效的废弃物回收再利用措施才能从根本上解决电子产品废弃物对环境影响的问题。     

无铅焊料及其可靠性的研究进展

环保和微电子器件高度集成化的发展驱动了高性能无铅焊料的研究和开发。本文介绍了国内外对Sn-Ag,Sn-Zn,Sn-Bi,Sn-Sb和Sn-In系无铅焊料的发展现状及所取得的研究成果;列出了美国抗高温疲劳焊料研究计划筛选的七种抗热疲劳无铅焊料合金;对焊点的一般可靠性问题及无铅焊料引入的新的可靠性问题进行了归纳和讨论。     

Sn-Zn系无铅焊料研究和亟待解决的问题

文章介绍了无铅焊料研究的趋势及Sn-Zn系焊料研究取得的最新进展,分析了Sn-Zn系焊料与Sn-Ag系焊料研究的差距。最后,文章还总结了Sn-Zn系焊料研究面临的困难,找出了存在于基础研究和应用研究领域的若干问题,指出Sn-Zn系焊料的研究还需要更加深入。     

Analysis of ring and plug shear strengths for comparison of lead-free solders

The drive to replace the use of toxic lead metal and its alloys has spurred the development of many new lead-free solder alloys. Moreover, current leaded solders lack shear strength, resistance to creep and to thermal-mechanical fatigue. Solder that exhibits enhancements of these properties and retains solderability is crucial in applications where the solder joints are subjected to thermal cycling, severe vibrations, and temperatures of up to 125°C. Modified ring and plug joints were made with 18 selected lead-free solders and three well characterized lead-containing solders. Analysis of the results provides a guide for the design of additional testing.     

无铅焊料的研究（4）——电迁移效应

电迁移是金属原子沿着电流方向的移动。阐述了无铅焊料中电迁移的物理特性,由于焊点的特殊几何形状,电流拥挤效应将发生在焊点与导线的接点处;电迁移效应导致无铅焊料中金属间化合物(IMC)的生成与溶解,以及焊点下的金属化层(UBM)的溶解和消耗,使原子发生迁移并会产生孔洞,造成焊点破坏,缩短了焊点平均失效时间(MTTF),从而带来可靠性问题。     

Spreading Kinetics of Liquid Solders over an Intermetallic Solid Surface. Part 2: Lead-Free Solders

This study is devoted to a phenomenological and quantitative investigation of␣the physics of spreading of lead-free solder systems (Sn, Sn-0.7Cu, and Sn-3.5Ag) over Cu₆Sn₅/Cu₃Sn/Cu substrates. Wetting kinetics was studied using real-time in situ monitoring of the triple-line kinetics under a controlled atmosphere. Three different intermetallic (IMC) substrates were used for this investigation. It was found that the grain size of the deposited IMC compound coating has a sizable influence on the triple-line movement of the liquid solders considered. More pronounced spreading of solders on IMC substrates was observed for all lead-free solders over an intermetallic with the smallest grain size. Lead-free solder spreading over IMC surfaces exposed to aging at elevated temperatures, hence featuring larger grain size, did not feature a significant improvement of wettability when compared with the behavior of the same solders on virgin copper substrates.     

High-temperature lead-free solder alternatives

For lead-free solders in the high-temperature regime, unfortunately, a limited number of alloying systems are available. These are Bi based alloys, gold involving alloys and Zn-Al based alloys. Based on these systems, possible candidate alloys were designed to have a melting range between 270 °C and 350 °C. Each has its own superior characteristics as well as some drawbacks however none of them can fulfill all the requirements to replace the current high-lead content solders. Even the alternative technologies that are currently being developed cannot address several critical issues of high-temperature soldering. Therefore, further research and development of high-temperature lead-free soldering is obviously needed.     

Investigation of multi-component lead-free solders

Binary phase diagrams of interest for lead-free solder development have been entered into the THERMO-CALC data base. These may be used directly to calculate multi-component phase relations vs temperature provided there are no ternary or higher order interactions. Such occur in the Sn-Ag-Zn system and are being evaluated. Contact angles of a number of solder-flux combinations on copper were directly measured in spreading tests. With a rosin-isopropyl alcohol flux, the contact angles of binary eutectic solders were in degrees: Sn-Bi at 166°C, 40; Sn-Zn at 225°C, 60; Sn-Ag at 250°C, 45. These angles were little affected by a number of 1% ternary additions to the solder. The contact angles were 20 degrees or less when SnCl₂ was used as a flux. The SnCl₂ reacts with Cu to form Cu₃Sn. The most likely successful approach to obtain satisfactory wetting with lead-free solders appears to be development of a satisfactory flux.