微量稀土元素铈对Sn-Ag-Cu无铅钎料物理性能和焊点抗拉强度的影响

研究了微量稀土元素铈对Sn-3．5Ag-0．5Cu无铅钎料的物理性能、润湿性能、焊点抗拉强度和显微组织的影响。结果表明，添加微量的铈后，钎料的导电性能提高，密度下降；铈含量（质量分数）在0．03％和0．05％时可以改善钎料的润湿性；特别是0．03％质量分数时晶粒组织最为细小均匀，焊点抗拉强度也最高；当铈含量（质量分数）大于0．1％时对钎料的性能产生不利影响，润湿时间升高，焊点抗拉强度大幅降低，因此稀土元素铈的最佳含量（质量分数）应为0．03％。     

Converting to lead-free solders: An automotive industry perspective

The solder tests currently used in defining solder alloy properties are not sufficient for selecting interconnect materials for improved reliability and reduced cost in automotive electronic applications. A “preventive” design approach based upon more accurate models of failure mechanisms and life prediction than are currently available will be required in order to assess solder alloys and to determine whether lead-free solders will provide improved reliability and lower-cost manufacturing options when compared to the lead-based solders currently used.     

美国社区学院的高等职业技术教育及启示

社区学院以其灵活的办学方式和广泛的适应性，在美国高等教育中占有重要地位。它为美国高等教育的大众化和社区文化水平的提高等提供了有效途径。社区学院也是美国实施高等职业技术教育的重要场所。本文主要探讨了美国社区学院高等职业技术教育的办学特色，以期为我国发展高等职业技术教育提供一些参考与借鉴。     

Local melting and shape controlling of solder joint via induction heating

A rapid yet simple methodology to form the solder joints used in electronic packaging has been demonstrated through an induction heating system in this paper. The objective is to control the shapes of the solder joints precisely and form the hourglass-shaped solder joint using local melting phenomenon. For Sn–Ag eutectic solder bullet-shaped solder bumps and hourglass-shaped solder joints can be obtained easily within 2.3 s. The reason for the formation of hourglass-shaped solder joints has been analyzed using different morphologies of Ag₃Sn intermetallic compound (IMC), and is explained by the non-uniform temperature distribution caused by a local melting phenomenon and skin effect.     

Impact of processing conditions and solder materials on surface mount assembly defects

The conversion to lead-free solder alloys and increasing dynamic warpage due to the coefficient of thermal expansion (CTE) mismatch and thinner microelectronic packaging technology has resulted in a significant increase in the risk of solder joint defects for ball grid array (BGA) components. This paper will review head-and-pillow (HnP) defects observed after surface mount assembly with specific focus on fine-pitch BGA technology on motherboards. The mechanisms related to various aspects of design and materials characteristics that affect the creation of these defects within the solder joints will be discussed. Finally, potential material solutions for eliminating these defects will be reviewed.     

增强颗粒Cu对锡铅基复合钎料铺展性能的影响

颗粒增强是提高合金性能的重要手段之一。增强体的不同含量对基体的性能会产生不同的影响。分析和讨论了Cu的不同体积分数对Cu颗粒增强的锡铅基复合钎料铺展性能的影响。试验结果表明：当Cu颗粒的体积分数小于1％时，随着Cu的体积分数的增加，复合钎料的铺展性能有所提高；当Cu的体积分数大于1％时，随着Cu颗粒体积分数的增加，复合钎料的铺展性能降低；当Cu颗粒的体积分数大于10％时，复合钎料的铺展性能急剧降低，且外观质量变差。     

Sn60Pb40 solder powders produced by the planar flow casting atomization process

Conventional planar flow casting (PFC) is one of rapid solidification processes for the fabrication of microcrystalline or amorphous ribbons. Based on the conventional PFC process, the planar flow casting atomization (PFCA) process has been developed, which is a new rapid solidification process for the production of metal powder directly from alloy melts. A prototype experimental apparatus was designed and manufactured.With the apparatus, Sn60Pb40 alloy solder powders were prepared, and the effects of the main technological parameters on the powder size distribution and morphology were experimentally studied. The experimental investigations indicate that the metal powders produced by the PFCA process can be classified by velocity; and fine spherical tin-lead alloy solder powders can be fabricated by adjusting the technical parameters. The new PFCA process has such features as high productivity and efficiency, low energy consumption, simple operation,short technological process, and large gross yield.     

Databases for computational thermodynamics and diffusion modeling

Databases for computational thermodynamics and diffusion modeling can be applied to the prediction of phase diagrams and microstructural evolution. These predictions can be used for alloy and process design, as well as to improve modeling capabilities that would decrease the time for new alloy and process development. Databases that are currently available to scientists, engineers, and students need to be expanded and improved. Accordingly, a workshop was held March 21–22, 2002, to identify the database and information delivery tool needs of industry and education. As a result of the workshop a roadmap was developed to show how these needs can be met during the next decade in a cost-effective way through expanded collaborative efforts in education, basic research, and database development. The workshop consisted of a series of invited talks given to the group as a whole followed by general discussions of needs and benefits, and the construction of a roadmap of future activities. A brief report of a follow-up meeting held on May 27, 2003, is given in the Appendix.     

Databases for computational thermodynamics and diffusion modeling

Databases for computational thermodynamics and diffusion modeling can be applied to the prediction of phase diagrams and microstructural evolution. These predictions can be used for alloy and process design, as well as to improve modeling capabilities that would decrease the time for new alloy and process development. Databases that are currently available to scientists, engineers, and students need to be expanded and improved. Accordingly, a workshop was held March 21–22, 2002, to identify the database and information delivery tool needs of industry and education. As a result of the workshop a roadmap was developed to show how these needs can be met during the next decade in a cost-effective way through expanded collaborative efforts in education, basic research, and database development. The workshop consisted of a series of invited talks given to the group as a whole followed by general discussions of needs and benefits, and the construction of a roadmap of future activities. A brief report of a follow-up meeting held on May 27, 2003, is given in the Appendix.     

Emerging Science and Research Opportunities for Metals and Metallic Nanostructures

During the next decade, fundamental research on metals and metallic nanostructures (MMNs) has the potential to continue transforming metals science into innovative materials, devices, and systems. A workshop to identify emerging and potentially transformative research areas in MMNs was held June 13 and 14, 2012, at the University of California Santa Barbara. There were 47 attendees at the workshop (listed in the Acknowledgements section), representing a broad range of academic institutions, industry, and government laboratories. The metals and metallic nanostructures (MMNs) workshop aimed to identify significant research trends, scientific fundamentals, and recent breakthroughs that can enable new or enhanced MMN performance, either alone or in a more complex materials system, for a wide range of applications. Additionally, the role that MMN research can play in high-priority research and development (R&D) areas such as the U.S. Materials Genome Initiative, the National Nanotechnology Initiative, the Advanced Manufacturing Initiative, and other similar initiatives that exist internationally was assessed. The workshop also addressed critical issues related to materials research instrumentation and the cyberinfrastructure for materials science research and education, as well as science, technology, engineering, and mathematics (STEM) workforce development, with emphasis on the United States but with an appreciation that similar challenges and opportunities for the materials community exist internationally. A central theme of the workshop was that research in MMNs has provided and will continue to provide societal benefits through the integration of experiment, theory, and simulation to link atomistic, nanoscale, microscale, and mesoscale phenomena across time scales for an ever-widening range of applications. Within this overarching theme, the workshop participants identified emerging research opportunities that are categorized and described in more detail in the following sections in terms of the following: three-dimensional (3-D) and four-dimensional (4-D) materials science. Structure evolution and the challenge of heterogeneous and multicomponent systems. The science base for property prediction across the length scales. Nanoscale phenomena at surfaces—experiment, theory, and simulation. Prediction and control of the morphology, microstructure, and properties of “bulk” nanostructured metals. Functionality and control of materials far from equilibrium. Hybrid and multifunctional materials assemblies. Materials discovery and design: enhancing the theory-simulation-experiment loop. Following an introduction, these emerging research opportunities are discussed in detail, along with challenges and opportunities for the materials community in the areas of instrumentation, cyberinfrastructure, education, and workforce development.     

稀土Ce加速Sn晶须生长的研究

稀土被认为是金属中的"维他命",在钎料中添加微量的稀土Ce可以显著地改善钎料合金的综合性能.然而,当钎料中添加过量的稀土时,将会发现Sn晶须的快速生长现象.结果表明,如果将Sn3.8Ag0.7Cu1.0Ce钎料内部的稀土相暴露于空气中,稀土相将发生氧化而产生体积膨胀,钎料基体对体积膨胀的抑制作用将使稀土相内部产生巨大的压应力从而加速Sn晶须的生长.     

Effect of cerium on microstructure and mechanical properties of Sn-Ag-Cu system lead-free solder alloys

The melting point, spreading property, mechanical properties and microstructures of Sn-3.0Ag-2.8Cu solder alloys added with micro-variable-Ce were studied by means of optical microscopy, scanning electron microscopy（SEM） and energy dispersive X-ray（EDX）. The results indicate that the melting point of Sn-3.0Ag-2.8Cu solder is enhanced by Ce addition; a small amount of Ce will remarkably prolong the creep-rupture life of Sn-3.0Ag-2.8Cu solder joint at room temperature, especially when the content of Ce is 0.1%, the creep-rupture life will be 9 times or more than that of the solder joint without Ce addition; the elongation of Sn-3.0Ag-2.SCu solder is also obviously improved even up to 15.7%. In sum, the optimum content of Ce is within 0.05%-0.1%.     

铟银软钎料的制备与钎焊性研究

用感应熔炼方法制备了一系列InAg钎料,考察银添加量对铟基钎料性能的影响。采用化学分析和X射线衍射(XRD)对钎料的成分和物相进行了对比分析;采用示差扫描量热仪(DSC)测试了不同成分钎料的熔点;利用扫描电镜(SEM)对In-7Ag焊料与基体的界面反应进行了研究,并测试了不同成分钎料的润湿性及接头剪切强度。结果表明,In-7Ag具有较大的剪切强度以及良好的润湿性,是月球样品返回装置密封材料的不错选择。焊料与密封材料剧烈反应可能弱化焊接组织的一致性,不利于金属密封,因此,寻求合适的焊接温度和时间是未来研究的重点。     

Dispersion strengthening for dimensional stability in low-melting-point solders

An improved solder structure with an ultrafine grain size of ∼200–500 nm and significantly enhanced mechanical properties has been created by incorporating nanosized, nonreacting, noncoarsening oxide dispersoids into solder alloys. These solders display up to three orders of magnitude reduction in the steady-state creep rate, 4–5 times higher tensile strength at low strain rates, and improved ductility under highstrain-rate deformation. With a dispersion of TiO₂ particles, the Pb-Sn eutectic solder with a low-melting point of 183°C can be made more creep resistant than the Au-20Sn eutectic solder with a much higher melting point of 278°C. This technique can be extended to other solder systems, such as the emerging lead-free solder alloys, and used to achieve enhanced dimensional stability. For more information, contact H. Mavoori, Bell Laboratories, Lucent Technologies, 1A-102 Bell Labs, 600 Mountain Avenue, Murray Hill, New Jersey 07974; e-mail hareesh@lucent.com.     

锌对共晶锡铋合金的电迁移可靠性的影响

本文选取了应用最为广泛的无铅钎料之一的共晶锡铋合金进行研究,对其进行锌的掺杂,以期透彻的了解锌对无铅钎料在电迁移作用下的行为。研究结果显示,在钎焊结束之后,电流加载之前,掺入的锌会通过促进合金晶粒粗化在一定程度上降低焊点的抗拉强度。但是对焊点进行电流密度为104 A/cm2的电流加载100h后,锌的掺入可以避免锡铋合金中锡相与铋相晶粒之间形成缝隙,从而对焊点的可靠性有显著的提升。     

SnAgCuEr系稀土无铅钎料的显微组织

系统研究了添加微量稀土Er对Sn3.8Ag0.7Cu无铅钎料合金显微组织和性能的影响.试验发现,微量Er的添加,使Sn3.8Ag0.7Cu钎料合金的熔化温度稍有降低,铺展面积有所增加,抗剪强度有所提高.通过显微组织观察,加Er后网状共晶物体积百分比增大,初晶金属间化合物(IMC)的尺寸变小.微量Er抑制了时效过程钎料与铜基体界面IMC层(IML)的增厚,时效400 h后差别更明显,有利于提高钎料接头的可靠性.指出含微量稀土的SnAgCuEr合金是性能优良的无铅钎料合金.     

Cr元素对Ni基无硼钎料钎焊金刚石的组织及性能影响

针对B元素易使钎焊金刚石接头出现较多硬脆相的问题，制备一种新型Ni–Cr–Si–Cu–Sn无硼活性钎料，分析Cr元素对钎料组织和钎焊金刚石试样性能的影响规律。结果表明:Cr元素具有细化钎料晶粒和调控钎料中各元素分布的作用，可以提高钎料合金的显微硬度。当Cr元素质量分数过高时，会使钎料的熔点升高，钎料的润湿性能下降。综合来说，含有质量分数为15%的Cr的无硼钎料性能最佳，钎焊金刚石试样的磨削性能较优良，接头处出现多种形状的Cr₇C₃相，实现了钎料对金刚石的高强度连接。      

Creep behavior on Ag particle reinforced SnCu based composite solder joints

1 Introduction The EU had issued the WEEE mandate that aimed to prohibit the use of SnPb solders by 2006. Under the pressure of legislation and trade competitions, large electronic manufacturers and research institutes studied substitutes for SnPb solders…     

Design of a visual system for predicting SMT solder joint shape

A visual software system has been developed for predicting and analyzin g the shape of solder joints in surface mount technology (SMT). The formation of the solder joint is numerically simulated through Surface Evolver program and the calculation is automated with an additional controller. A preprocessor is developed in which process parameters determining the shape of solder joints can be input visually and transferred into Evolver program automatically. A postproces sor is built to analyze the global three-dimensional shape and cross-section profiles of solder fillets in multiple windows. Also, the application for predicting the solder joint shape of RC chip component is conducted with the PSJS system.     

基于数字孪生的智能装配车间管控模式

基于数字孪生的智能装配车间技术是一种未来装配车间生产管控新模式,针对机翼装配车间生产过程中装配工艺路线复杂、资源利用率低、装配效率、质量低等问题,提出基于数字孪生的智能装配车间管控模式,通过构建真实装配车间、孪生装配车间和装配车间管控系统协同作业的智能装配车间,在实现资源位置信息、装配流程信息、装配质量信息实时采集的基...