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Study on Impact Strength Evaluation of Micro-Solder Joints in Mobile Electronic Units

移动电子装置微焊点冲击强度评价研究

基本信息

批准号：
11555029
负责人：
SHIRATORI Masaki
金额：
$ 8.64万
依托单位：
Yokohama National University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B).
财政年份：
1999
资助国家：
日本
起止时间：
1999 至 2000
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-11555029/
关键词：
Electronics packages Impact Fracture due to impact Static response analysis Dynamic analysis Impact test 衝撃破壊寿命

项目摘要

Recently, the speed-up of the information processing and operation treatment speed due to multimedia needs of the electronic machine, and mobile trend of information technology units are proceeding rapidly. The miniaturization and lightening technologies are the keywords for mobile units electronic units. Furthermore the probability increase of mobile units dropping causes that the impact strength dominates its reliability. The purposes of this study are to develop a effective stress evaltuation method for the dropping behavior by using static finite element analytical system, and make clear dynamic failure mechanics of solder joints in mobile electronic units.The conclusions of this study were given as followings ;1) An impact testing equipment was developed to investigate the dynamic behavior of micro solder joints. Based upon the experimental results of dynamic tests of solder material properties, it was found that the dynamic yield stress is much higher than its static yield stress … More . This restults suggest that solder material can be treated elasticly, when dynamic behavior of solder joints is investigated.2) Cyclic dropping tests of PCB (printed circle board) mounted with a BGA (ball grid array) package were carried out. It was found that the interface fatigue crack is the main failure mode of BGA solder joints, and the interface crack concentrating in the intermeterics layer between the solder and Cu pad. Furthermore it was found that this interface crack mode is caused by the increase of solder yield stress due to dynamic deformation.3) Instead of dynamic finite element analysis, a static analytical method and a mode analytical method have been developed to simulate the dynamic behavior of PCB and solder joints. The proposed methods cant shorten the simulation time to 1/10 and can be used to study the effect of PCB vibration modes beside its first mode on the dynamic stress behavior in solder joints.Based upon the analytical results, it was found that the dynamic stress behavior in solder joints is affected greatly by the vibration modes of PCB and the location of the package. As a conclusion the impact reliability design of BGA package can be dealt by controlling the position of package corresponding to the vibration modes of PCB. Less

近来，由于电子机器的多媒体需求而导致的信息处理和操作处理速度的加速以及信息技术单元的移动的趋势正在迅速发展。小型化和轻量化技术是移动的单元电子单元的关键。此外，移动的单元跌落概率的增加导致冲击强度主导其可靠性。本文的研究目的是利用静态有限元分析系统，建立一种有效的焊点跌落行为应力评估方法，明确移动的电子元器件焊点的动态失效机理，主要研究成果如下：1）研制了一套用于研究微焊点动态行为的冲击试验装置。通过对钎料材料性能的动态测试，发现钎料材料的动态屈服应力远高于静态屈服应力 ...更多信息 .这一结果表明，在研究焊点的动态行为时，可以将焊点材料弹性处理。2）对BGA（球栅阵列）封装的PCB（印刷电路板）进行了循环跌落试验。结果表明，界面疲劳裂纹是BGA焊点的主要失效形式，且界面裂纹集中在钎料与Cu焊盘之间的界面层。此外，还发现这种界面裂纹模式是由于动态变形引起的焊点屈服应力的增加而引起的。3）采用静态分析方法和模态分析方法代替动态有限元分析方法来模拟PCB和焊点的动态行为。所提出的方法不能将仿真时间缩短到原来的1/10，并且可以用来研究PCB振动模式对焊点动态应力行为的影响，分析结果表明，PCB振动模式和封装位置对焊点动态应力行为有很大影响。因此，BGA封装的冲击可靠性设计可以通过控制封装的位置与PCB的振动模态相对应来进行。少