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：随着越来越重视开发环保电子软件包，无PB合金引起了很多关注。这些合金的机械行为极为重要，因为焊接接头必须在热机械疲劳，蠕变，机械冲击和振动疲劳下保留其机械完整性。后者已成为行业中越来越多的问题。 相对较低的循环应力可能应用于电子包装，尤其是在汽车和飞机应用中，这会导致等温疲劳。与此问题有关的基本问题很少受到关注。迄今为止，对机械冲击的理解在很大程度上是经验的。典型的测试涉及将模块从给定的高度删除，并测量电阻和定性外观，以确定该组件是否已失败。在机械冲击过程中，对包装中应力和应变状态的理解在很大程度上是不存在的。此外，金属间厚度和焊料微结构在机械冲击和振动疲劳上的作用尚未真正检查。迫切需要一种在机械冲击下建模应力状态的方法。 PIS将对SN-3.5AG-0.7CU和SN-AG焊料的机械休克和振动疲劳行为进行彻底研究和分析，并与纯SN进行了比较。 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）了解具有机械冲击和振动疲劳阻力的焊料/关节界面上的金属间厚度与焊料微结构之间的关系，（IV）使用多规模数值技术在机械冲击和振动过程中焊接接头的模型变形，以获得对微观构造和焊接的根本性理解，以实现对微实现和焊接的根本性效应。非技术：由于这些材料的环境范围性质，无PB焊料非常重要。该研究计划将对无PB焊料的机械冲击和振动疲劳损伤产生透彻的理解。它还将为半导体行业提供对这些材料中高应变速率变形的定量理解。该研究计划将包括大学和工业之间的实质性互动。尽管过去几年对焊料的研究一直很广泛，但该领域的学生的教育并未受到同样的关注。结合了一项综合的教育外展计划：（a）为学生的电子包装计划开发新硕士，（b）计划针对学生的项目，以及（c）工业外展活动。