无铅焊接技术在微电子封装工业中的应用综述

介绍了无铅焊接技术的现状以及国内外对Sn-Ag和Sn-Zn等二元无铅焊料的研究成果,以及无铅焊接的几种常见技术.     

无铅钎料的研究开发现状

综述了近年来国内外无铅钎料的研究开发现状和部分无铅钎料的应用情况。重点介绍了国内外Sn-Ag和Sn-Zn系无铅钎料的研究与发展,以及合金元素对Sn-Ag和Sn-Zn系无铅钎料的微观组织、润湿性、熔点、腐蚀行为等方面的影响,并介绍了微量稀土元素对无铅钎料的组织和性能的影响。     

合金化元素对Sn-Zn钎料性能的影响

Sn-Zn无铅钎料因其低廉的成本、适合的熔点和良好的机械性能而受到众多研究者的高度关注.综述了Sn-Zn基无铅钎料的研究现状与存在的关键技术问题,分析了添加Bi、Ag、Cu、Al及稀土Re对Sn-Zn钎料熔点、润湿性、力学性能、抗氧化腐蚀及接头组织的影响,指出必须同时进行钎料的合金化、新型钎荆及改进钎焊工艺的研究,才能完成Sn-Zn基无铅钎科的工业实用化.     

微电子互连锡基无铅焊料的发展

对国内外无铅焊料发展情况进行了综述,详细分析了当前运用广泛的Sn-Ag,Sn-Cu和Sn-Ag-Cu无铅焊料的相组织、性能等,列举了商业应用中无铅焊料的使用情况,并阐述了无铅焊料的可靠性问题、发展要求以及发展趋势等.     

浅谈低Ag系Sn-Ag-Cu焊料的发展

电子产品中Pb污染问题使得研究人员开始寻找Sn-Pb焊料的替代品,探索一种新型的零污染、低成本的电子封装合金。Sn-Ag-Cu合金被认为是最有发展前景的无铅焊料。但Ag属于贵金属,成本较高,故发展低Ag系无铅钎料成为了研究热点。本文介绍了低Ag系Sn-Ag-Cu焊料的发展现状,通过掺杂微量元素来改善合金的力学性能、显微组织、润湿性、可靠性、抗跌落性等。     

无铅焊料Sn-Ag-Sb系列合金的研究与开发

采用均匀设计方法对Sn-Ag-Sb系无铅焊料合金进行合金设计,并对其焊料合金进行了熔点、剪切强度及微观组织等研究分析,结果表明:Sb的加入,对Sn-Ag-Sb系合金熔点下降的影响较小,Ag、Sb在Sn基体中形成Ag3Sn和SbSn相,形成良好弥散强化,因此使得焊料合金具有较高的机械强度.     

自适应无铅焊料的开发与研究

可靠性是电子工业发展所面临的最大难题.随着对无铅焊料的深入研究,消除金属间化合物对焊点机械性能的不利影响,及解决由于印刷电路板与电子材料间的热膨胀系数不同所产生的、在热循环过程中出现的热疲劳现象,都是提高可靠性的途径.提出了开发自适应无铅焊料解决上述问题,阐述了制备自适应无铅焊料的可行性,并展望了此种焊料的良好应用前景.     

绿色无铅电子焊料的研究与应用进展

概述了关于无铅电子焊料全球范围的立法与研发计划、国内外无铅焊料的发展现状及所取得的研究成果,探讨了无铅焊料合金的专利问题,进行了无铅软钎焊技术可行性、经济性和可靠性分析,介绍了无铅焊料的应用情况,并展望了前景.     

无铅电子封装焊料的研究现状与展望

随着美、日和欧盟就含铅钎料建立相应立法之后,各国都在紧锣密鼓地开展绿色环保无铅产品的研发工作.介绍了国内外无铅焊料所涉及的4种主要成分设计方法,以及当前研究的主要无铅体系及其各自特征;论述了各焊料体系所应用的范围、组织结构和性能,及无铅焊料所关注的主要性能指标和发展趋势,并结合我国国情展望了我国无铅焊料的前进方向.     

稀土元素对无铅焊料性能的影响

随着公众环保意识的增强,含铅焊料的发展和应用受到了极大的限制,研制新型的、环境友好的无铅焊料来取代传统的锡铅焊料成为近年来研究的热点,而添加微量元素合金化以获得性能优异的无铅焊料尤其受到研究者的关注。本文系统地综述了添加微量稀土元素对无铅焊料物理化学性能、显微组织、力学性能、电迁移及锡晶须生长等的影响,并对稀土元素在无铅焊料中的应用及发展趋势进行了展望。     

无铅焊接合金的制备及性能研究

制备了Sn-Zn、Sn-Zn-Bi、Sn-Zn-Bi-RE与Sn-Zn-Bi-Ag系无铅焊接合金，研究了合金的熔点、熔化温度区间、对铜板的润湿性、微观结构和电化学性能。实验结果表明：Bi元素的加入能够降低Sn-Zn合金的熔点，但熔化温度区间增大；Bi、Ag、混合RE能够细化晶粒，使组织更均匀；电化学研究表明，加入适量的混合RE和Ag可提高合金的耐腐蚀性。     

Sn–Zn low temperature solder

Low temperature soldering is one of the key technologies before the accomplishment of total lead-free conversion in electronics industries. While Sn-Zn eutectic alloy has excellent properties as low temperature solder, it has some drawbacks. Damage by heat exposure and corrosion in humidity are two of the main concerns. Zn has an important role in chemical properties. The material physical properties, wetting, chemical stabilities and various reliabilities have been well understood on this alloy system through the numerous past works. The understanding of both materials and processing aspects enables one to manufacture sound electronic products without any serious problems. The basic properties and the current understandings on the limit of the application of this solder are reviewed in this paper.     

纳米结构强化无铅焊点的力学性能

新型的无铅钎料不仅要具备含铅钎料的工艺性能,更重要的是要有更高的力学性能,特别是焊接接头的抗蠕变能力。将纳米级多面齐聚倍半硅氧烷(Polyhedral oligomeric silsesquioxanes,POSS)颗粒作为增强相添加到基体钎料中,能够有效地改善Sn-3. 5Ag基复合钎料的性能。研究了不同种类POSS增强颗粒对Sn-3. 5Ag钎料显微组织和力学性能的影响,确定出POSS增强颗粒复合钎料的最佳配比,并对最佳配比复合钎料在不同温度不同载荷条件下的蠕变寿命进行了研究。结果表明：POSS颗粒质量分数小于2%时,可以抑制基板界面处初晶金属间化合物的生长;复合钎料的抗剪切强度明显提高;低温时,最大蠕变寿命明显改善。     

Sn-9Zn-xP无铅焊料合金性能研究

以Sn-9Zn合金为研究对象,考察了P的添加对其性能的影响,并对其机制作了初步探讨。通过二次离子质谱(SIMS)分析发现,P的添加显著降低Sn-9Zn合金中的含氧量,从而提高了合金在Cu上的润湿性。P的改善润湿性的效果不仅有利于其工艺性能,也提高了Sn-9Zn/Cu焊点界面的结合强度,只使其塑性略有下降。同时,微量P的添加不改变Sn-9Zn合金与Cu形成的焊点的界面结构。另外,蠕变强度测试结果表明,P的添加能显著提高合金的抗蠕变性能。     

Synthesis and DSC study on Sn3.5Ag alloy nanoparticles used for lower melting temperature solder

The traditional Sn–Pb eutectic solder alloys are being phased out from the electronics industry due to the toxicity of lead (Pb), leading to the development and implementation of lead-free solders. Sn3.5Ag lead-free solder alloy, considered to be one of the promising alternatives to replace the traditionally used Sn–Pb solder, however, still has some weaknesses, such as its higher melting temperature than that of the Sn–Pb solder alloy. A possible way to decrease the melting temperature of a solder alloy is to decrease the alloy particle size to the nanometer range. Sn3.5Ag nanoparticles with different size distribution were synthesized using chemical reduction method by applying NaBH₄ as reduction agent. The melting properties of these synthesized nanoparticles were studied by differential scanning calorimetry (DSC), and size-dependent melting temperature depression of these nanoparticles has been observed. Gibbs–Thomson equation was used to analyze the size-dependent melting temperature property, giving a good prediction of the melting temperature depression for the Sn-based lead-free solder alloy nanoparticles.     

Composite lead-free electronic solders

Composite approaches have been developed in lead-free solder research in an effort to improve the service temperature capabilities and thermal stability of the solder joints. This article overviews the background for composite lead-free solder development, the roles of reinforcements and their requirements, composite solder processing techniques, as well as current status of composite solder research. Examples of several representative lead-free composite solders produced with various methods and reinforcement types are presented. The effects of reinforcement addition on processing and mechanical properties are analyzed. Difficulties and problems that exist in composite solder research are proposed and tentative solutions are attempted with examples of newly emerging novel lead-free composite solders.     

Sn-Cu系无铅钎料微合金化研究进展

电子产品绿色化的需求促进了电子组装中钎料合金的无铅化发展。目前,Sn-Cu系钎料以优良的综合性能和较低的成本成为最具使用前景的无铅钎料之一。但是Sn-Cu系钎料的熔点较高,在Cu基上的铺展性和钎焊性也较Sn-Pb钎料差,这在很大程度上限制了其应用。通过添加多种合金元素可改善Sn-Cu合金的微观组织和焊接性能。本文首先系统地综述了合金元素对Sn-Cu系无铅钎料微观组织、润湿性、力学性能等的影响,然后指出Sn-Cu系无铅钎料存在的问题。最后,对Sn-Cu系无铅钎料的发展方向和前景进行了展望。     

Investigation of microstructures and tensile properties of a Sn-Cu lead-free solder alloy

In recent years, the pollution of environment from lead (Pb) and Pb-containing compounds in microelectronic devices attracts more and more attentions in academia and industry, the lead-free solder alloys begin to replace the lead-based solders in packaging process of some devices and components. In this work, microstructures and mechanical properties of the lead-free solder alloy Sn99.3Cu0.7(Ni) are investigated. This paper will compare the mechanical properties of the lead-based with lead-free solder alloys (Sn99.3Cu0.7(Ni) and 63Sn37Pb). The tensile tests of lead-based and lead-free solder alloys (Sn99.3Cu0.7(Ni) and Sn63Pb37) were conducted at room and elevated temperature at constant strain rate; the relevant tensile properties of Sn99.3Cu0.7(Ni) and Sn63Pb37 were obtained. Specifically, the tensile strength of this lead-free solder- Sn99.3Cu0.7(Ni) in 25^∘C, 50^∘C, 75^∘C, 100^∘C, 125^∘C was investigated; and it was found that tensile strength of the lead-free solder decreased with the increasing test temperature at constant strain rate, showing strong temperature dependence. The lead-free solder alloy Sn99.3Cu0.7(Ni) was found to have favorable mechanical properties and it may be able to replace the lead-based solder alloy such as Sn63Pb37 in the packaging processes in microelectronic industry.