Test Method Research On Reliability Enhancement Testing For Module-Level Electronic Products

Reliability Enhancement Testing (RET) put forward by The Boeing Company in 1990s is a brand-new method for reliability test. Since RET can efficaciously solve the problem that highly reliable electronic products are required to be developed rapidly and economically, it has been widely spread and applied in western developed countries. However this technique has been still closely kept secret by many of the most advanced companies, the kernel of the technique has not been realized in our country, and how to implement RET efficiently for the electronic products has not been studied systemically. With the support of a Major Armament Preparatory Research Project, the Ansys Finite Element Analysis (FEA) software and the advanced RET equipment imported recently have been used to study the primary theories and methods of RET for module-level electronic products in this dissertation,, the goal is to master the technique, make RET become a powerful tool to enhance the competition of our electronic products in the international market and improve the battle effectiveness of the armament.The RET for electronic products mainly includes vibration test and the thermal cycling test, Its general purpose is to expose the design weaknesses in compressed time by applying accelerated stress far exceeding the field environments to the specimen in the design phases. Therefore the main focus of this dissertation has been concentrated on what defects there are in the module-level electronic product and how to use vibration test and thermal cycling test to expose them. Around these points, the RET method for module-level electronic products has been researched deeply in the view of both theory and experimentation.The failure mode and failure mechanism of the module-level electronic product have been investigated, and the possible defects and their activation condition in the module-level electronic product have been analyzed. According to the RET characteristics and the RET equipment capability, the RET strategy for the module-level electronic product has been put forward at last, and the problem that what defects there are in the module-level electronic product and which of them can or can not be exposed by the module-level RET have been answered definitely. Therefore, the goal and task of RET for the module-level electronic product has been determined, it is valuable to guides RET application and research.Because the solder joints and the leads of the components are the major origin of the defects of the module-level electronic product, the main attention has been concentrated on how to stimulate the solder joint and lead defects completely in this dissertation. According to the structure characteristic of the Surface Mounted Devices, the Printed-Circuit Board, on which EBGA(Enhanced Ball Grid Array) and PQFP(Plastic Quad Flat Packaging) packaging have been mounted, has been taken as the main research object during the study.In this dissertation, Finite Element Method(FEM) is the basic method of calculation andanalysis. Because the shape and the constitutive equation of the solder joints directly affect the calculation accuracy, the three-dimensional solder joint shape has been predicted on the base of minimal energy principle, and the constitutive equation of the material has been deeply analyzed. After the PCB(Printed-Circuit Board) Finite Element Model has been built based on the predicted joint shape, the stress and strain in the solder joint and lead under vibration and thermal cycling testing excitation have been analyzed with the finite element method. At last the effect of the test profile parameter on the stress, strain and fatigue life of the solder joints has been studied in detail, and the problem that how to expose the defects in the electronic product by thermal cycling test, what disadvantage the thermal test have and how to remedy its demerit by vibration test have been proposed. In general, the main points and conclusion can be summarized as follows.1. Based on Elastic-visco-plastic theory, the creep and stress relaxation...