Mechanical Shock and Vibration Fatigue Behavior of Environmentally-Benign PB-Free Solders in Electronic Packaging

电子封装中环保无铅焊料的机械冲击和振动疲劳行为

• 批准号: 0805144
• 负责人: Nikhilesh Chawla
• 金额: $ 36万
• 依托单位: Arizona State University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-07-01 至 2012-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0805144&HistoricalAwards=false
• 关键词: Mechanical; Shock; Vibration; Fatigue; Behavior

TECHNICAL: With the increasing focus on developing environmentally-benign electronic packages, Pb-free alloys have received a great deal of attention. The mechanical behavior of these alloys is extremely important because solder joints must retain their mechanical integrity under thermo-mechanical fatigue, creep, and mechanical shock and vibration fatigue. The latter has become an increasing problem in the industry. Relatively low cyclic stresses may be applied to electronic packages, particularly in automotive and aircraft applications, which results in isothermal fatigue. Fundamental issues related to this problem have received very little attention. To date, the understanding of mechanical shock is largely empirical. Typical testing involves dropping the modules on the ground, from a given height, and measuring the electrical resistance and qualitative appearance to determine whether the component has failed. An understanding of the stress and strain state in the package during mechanical shock is largely non-existent. Furthermore, the role of intermetallic thickness and solder microstructure on mechanical shock and vibration fatigue has not really been examined. A methodology for modeling the stress state under mechanical shock is urgently required. PIs will conduct a thorough study and analysis of the mechanical shock and vibration fatigue behavior of Sn-3.5Ag-0.7Cu and Sn-Ag solders with a comparison to pure Sn. The program will: (i) quantify the mechanical shock and vibration fatigue behavior using a novel, sophisticated system that enables application of realistic and controlled strain rates (10/s or higher) on single and multiple solder joints, as well as bulk solder, (ii) measure the strain distribution and evolution in a small-length scale solder joint, with fiducial marks micromachined by Focused Ion Beam (FIB), using a high speed camera and digital image correlation (DIC), (iii) understand the relationships between intermetallic thickness at the solder/joint interface and solder microstructure with mechanical shock and vibration fatigue resistance, (iv) model deformation of solder joints during mechanical shock and vibration, using multi-scale numerical techniques, to obtain a fundamental understanding of microstructural and geometric effects on solder deformation. NON-TECHNICAL: Pb-free solders are of importance because of the environmentally-benign nature of these materials. The research program will yield a thorough understanding of mechanical shock and vibration fatigue damage in Pb-free solders. It will also provide the semiconductor industry with a quantitative understanding of high strain rate deformation in these materials. The research program will include substantial interaction between university and industry. While research on solders has been extensive over the last several years, education of students in this area has not received the same attention. An integrated education outreach program that combines: (a) contributions to the development of a new Master?s in Electronic Packaging Program at ASU, (b) project-oriented activities for students, and (c) industrial outreach, is planned.

技术：随着人们对开发环保电子封装的日益关注，无铅合金受到了极大的关注。这些合金的机械性能极其重要，因为焊点必须在热机械疲劳、蠕变以及机械冲击和振动疲劳下保持其机械完整性。后者已成为行业中日益严重的问题。 相对较低的循环应力可能应用于电子封装，特别是在汽车和飞机应用中，这会导致等温疲劳。与这个问题相关的基本问题很少受到关注。迄今为止，对机械冲击的理解很大程度上是经验性的。典型的测试包括将模块从给定高度掉落到地面上，并测量电阻和定性外观，以确定组件是否出现故障。对机械冲击期间封装中的应力和应变状态的了解基本上不存在。此外，金属间化合物厚度和焊料微观结构对机械冲击和振动疲劳的作用尚未得到真正的研究。迫切需要一种对机械冲击下的应力状态进行建模的方法。 PI将对Sn-3.5Ag-0.7Cu和Sn-Ag焊料的机械冲击和振动疲劳行为进行彻底的研究和分析，并与纯锡进行比较。该计划将：(i) 使用新颖、复杂的系统量化机械冲击和振动疲劳行为，该系统能够在单个和多个焊点以及散装焊点上应用真实且受控的应变率（10/s 或更高）， (ii) 使用高速相机和数字图像相关 (DIC)，通过聚焦离子束 (FIB) 微加工基准标记，测量小长度焊点中的应变分布和演变，(iii) 了解之间的关系金属间化合物厚度具有抗机械冲击和振动疲劳性能的焊料/接头界面和焊料微观结构，(iv) 使用多尺度数值技术对机械冲击和振动期间焊点的变形进行建模，以获得对焊料变形的微观结构和几何效应的基本了解。非技术性：无铅焊料非常重要，因为这些材料具有环保性质。该研究计划将深入了解无铅焊料中的机械冲击和振动疲劳损伤。它还将为半导体行业提供对这些材料的高应变率变形的定量了解。该研究计划将包括大学和工业界之间的实质性互动。虽然过去几年对焊料的研究已经很广泛，但该领域的学生教育并未受到同样的关注。计划实施一项综合教育推广计划，其中包括：(a) 为亚利桑那州立大学电子封装项目新硕士学位的开发做出贡献，(b) 面向学生的项目导向活动，以及 (c) 工业推广。