Research on Strength Evaluation of Electronic Packages and Materials

该研究旨在开发电子封装完整性评估方法。主要结果总结如下：1。已经开发和验证了用于评估焊料的蠕变断裂强度和抗拉-压缩、扭转和冲击载荷的疲劳强度的方法。并成功地分析了铜的疲劳特性.薄膜机械性能和粘接强度的无损评价方法已经发展起来。并在开发新的测试方法的基础上，揭示了薄膜的疲劳特性.已经公开了聚合物注射焊缝的形成及其对机械性能的影响。并对固化过程中产生的内应力进行了解析估算.找到了YAG激光辐照IC塑封颜色变化的条件.已经开发了一种方法来增加柔性印刷电路的失效周期数。提出了一种基于可靠性工程方法的寿命设计和试验的新方法.提出了一种新的基于裂纹测量的玻璃光纤延迟断裂性能的评价方法.提出了一种分析集成电路封装热应力的数值方法。也会导致分层和断裂。分析了塑料LSI封装的安装工艺。提出了微电子导体热疲劳寿命的估算方法和由应力迁移引起的导体失效模型.分析了异种材料接头拐角处的奇异应力场。使用红外热成像和超声波的新技术已被开发和验证，用于检测分层。

The research has been performed to develop methods for integrity assessment of electronic packages. The main results are summarized as follows :1. Methods have been developed and verified for evaluation of creep rupture strength of solder and fatigue strength against tension-compression, torsional and impact loadings. Also fatigue characteristics of copper have been successfully analyzed.2. Methods for nondestructive evaluation of mechanical properties and adhesive strength have been developed for thin films. Also fatigue characteristics of the thin films have been revealed based on developing a new testing method.3. Formation of a polymer injection weld and its effect on mechanical properties have been disclosed. Also internal stress which occurs in the curing process has been estimated analytically.4. Irradiation conditions of YAG laser have been found for the change in color of plastic IC package.5. A method has been developed to increase number of cycles to failure of flexible printed circuits.6. A new method for life design and testing has been proposed on the basis of the reliability engineering approach.7. A new method has been developed to evaluate accurately the delayed fracture behavior of an optical glass fiber, based on crack measurement.8. A numerical method for analyzing thermal stress of IC package has been developed. Also delamination and fracture caused. in mounting process of plastic LSI packages have been analyzed. Moreover, a method for evaluating the thermal fatigue life in microelectronic conductor and a model for the conductor failure due to stress migration have been proposed.9. Singular stress fields near a corner of jointed dissimilar materials have been analyzed.10. New techniques using infrared thermography and ultrasonics have been developed and verified for inspection of delamination.