Reliability Design and Multi-mode Fracture Control of Micro Joint Structure in Advanced Electronics Packaging

在本报告中，采用分析和实验方法对无铅焊料在实际应用之前必须解决的机械可靠性问题进行了研究。本报告共分七章。每章的内容如下。第一章介绍了目前电子器件的表面贴装技术、表面贴装元件的可靠性评估方法、无铅焊料应用的必要性和存在的问题。第二章给出了回流条件与焊点疲劳强度的关系。第三章指出了各无铅焊点断裂方式的差异。同时，采用分析和实验方法研究了金属间化合物层的生长和焊料的材料性能对焊点断裂模式的影响。第四章对低温无铅焊料备受关注的Sn-Zn体系焊点的界面强度进行了分析，并提出了提高可靠性的方法。第五章通过有限元分析和CSP焊点的剪切疲劳试验，阐述了焊点的空洞形成与疲劳强度之间的关系。第六章采用机械剪切疲劳试验研究了无铅焊料的硬化特性。研究了硬化规律和蠕变规律对无铅焊点应力和非线性应变估计的影响，提出了一种收敛性好、精度高的弹塑性蠕变分析方法。最后，第七章给出了前几章的结论。通过本文的研究，揭示了无铅焊料在实际应用中存在的界面强度下降、空洞形成、本构方程的应用等机械可靠性问题，并提出了解决这些问题的方法。研究结果可以提高无铅焊点的可靠性，提高可靠性评估的效率，降低生产成本。少

In this report, mechanical reliability problems, which must be solved before lead-free solder can be used in practical applications, are examined using analytical and experimental methods. This report consists of seven chapters. The contents of each chapter are as follows. Chapter 1 describes the current surface mount technology of electron devices, the reliability assessment method of surface mounted components, and the necessity and problems of lead-free solder applications. Chapter 2 shows the relationship between reflow condition and the fatigue strength of a solder joint. In Chapter 3, the difference of fracture modes in each lead-free solder joint is noted. Also, the effect of the growth of the intermetallic compound layer and the material properties of solder on the fracture mode of a solder joint are shown using analytical and experimental methods. In Chapter 4, the interface strength of the Sn-Zn system solder joint, which is attracting attention as a low-temperature lead-free … More solder, is analyzed and a technique to improve reliability is proposed. Chapter 5 shows the relationship between the formation of voids and fatigue strength of solder joints using FEM analysis and mechanical shear fatigue tests of CSP joints.In Chapter 6, the hardening characteristics of lead-free solder are examined using mechanical shear fatigue testing. Also, the effect of the hardening rule and creep law on the estimation of stress and nonlinear strain for lead-free solder joints is examined and an elastic-plastic-creep analysis method is proposed, which shows good convergence and high precision. Finally, Chapter 7 presents the conclusions gained from the preceding chapters.Through this study, mechanical reliability problems such as the decrease of interface strength, formation of voids, and the application of a constitutive equation, all of which have become very important in practical applications of lead-free solder, are shown and solutions for these problems are proposed. As the results of this study, it is possible to improve the reliability of lead-free solder joints and the efficiency of reliability evaluations as well as to reduce production costs. Less