摘要
任何电子产品在进入市场之前的可靠性测试是十分重要的环节。为此,在之前的几十年中开发了多种类型的测试方法。一种广泛使用的测试方法便是线路板弯曲测试。进行可靠性测试的一个主要问题就是需要大量的测试样品,这是因为这种测试必须重复进行直到获得一致并满意的测量结果。其测试样品的设计,组装工艺和测试程序需要花费长期的时间。如果可靠性测试结果不满意,测试样品需要重新设计、重新生产、重新测试,这从商业的观点来看成本过高且低效。为简化可靠性测试程序,提出了计算模拟的方法在前期设计阶段来预测印制板组装线的可靠性。在目前的研究中,可靠性测试采用了三点弯曲测试法。实现了有限元模式确认及关于该模式应用的2种情况研究。
Reliability test is a very important step for any electronic products before they can be sold to the market. In the previous decades, various types of test have been developed. One of the widely used testing methods is the board bending test. A major issue of performing a reliability test is that numbers of testing samples are required since the test has to be repeated until consistent and satisfactory results can be obtained. A long time will be spent on the specimen design, the assembly processes and the testing procedures. In case the reliability test is not satisfied, the specimen will need to be redesigned, reproduced and retested. This is costly and not efficient from the commercial point of view. To simplify the reliability testing process, computational simulation is proposed to predict the reliability of printed circuit board assemblies （PCBA） at the early design stage. In the present study, 3-point bending test is the reliability test adopted. Finite clement model validation and two case studies regarding the application of the model arc the objectives of this work. Comparison between experimental results and computational results is carried out for model validation. The physical properties （stiffiness and strain） of the model show a good agreement with the experiments at both the elastic deformation stage and the plastic deformation stage under the 3-point bending condition. The maximum yon Mises stress at the solder joints of the model at which the samples are found to be failed is also very close to the strength of the solder. This further validates the model. For application, this stress data is used as a failure criterion to indicate whether a PCBA is reliable under different bending conditions. In the first study case, the stress analysis methodology is used to investigate the reliability of a PCBA with increased printed circuit board （PCB） thickness. The corresponding models are built and through the stress analysis on solder joints, the maximum deflection for those PCBA under 3-point bending can be estimated. For another application, the reliability of a PCBA is studied under the depaneling condition. The ＇high risk＇ location for mounting packages on this board is indicated. These study cases shows that the stress analysis methodology employed is a powerful guideline on the product design stage.
出处
《电子工业专用设备》
2007年第3期30-38,共9页
Equipment for Electronic Products Manufacturing
