Integrated Circuit Package Reliability Related Mechanical Problems Research

At present, with the development of semiconductor technology, the IC package size is becoming smaller. This development makes residual stress of plastic packaging more significant. Influence of the stress on the reliability of plastic packaging device becomes larger. The existence of residual stress can cause Layered package, wire unsoldering, even cracks of the package and so on. Some present researches on plastic residual stress are mainly doing on the structure design and materials optimization of the package. Although there has obtained some achievements, it need a further study. The parameters of packaging processing are one of the key factors in the manufacturing of IC packages and have an important influence on the quality of plastic packaging products. A research on it would be very significant and can make a new way to study the residual stress of the packages. In this paper, there will do some research about the influence rules of the parameters of packaging processing on the residual stress in the packages with FEA and experimental and practical production analysis. So finally we can find out some new way to reduce residual stress in the packages.In this study, the SSOP-20 L would be used to do FEA analysis test and experimental analysis. With MOLDFLOW and ANSYS software, we used orthogonal test analysis to research the influence of the parameters of packaging processing, such as mold temperature, injection pressure, injection time and packing pressure, on the plastic packaging residual stress in the packages. At the same time, two kinds of epoxy mold compound were used to the test, so we could find that whether there wre some common rules of the influence of the parameters of packaging processing on the residual stress in the packages. Because the FEA analysis might have some inaccurate, there needed practical experiment to verify the analysis result. There proposed a new experimental method which based on similarity theory and photo elasticity theory to finish the experiment. Even more, the analysis result was used to deal with the layering of the SOD-123 F package which caused by residual stress.From the work in this paper, there proposed a new experimental method which based on similarity theory and photo elasticity theory to research the residual stress in the package. Through the FEA test and experiment we can find that: In the molding process of different kinds of epoxy molding compound, there are some common rules of the influence of the parameters of the packaging processing on the residual stress. Mold temperature and packing pressure are the significant factors which affect the residual stress. Even more, the higher the mold temperature, the greater the residual stress. And the greater the pressure, the smaller the residual stress. So there is a way to reduce the residual stress and improve the reliability of the packages with low mould temperature and high packing pressure. The molding pressure and time have the less influence on the residual stress. But with good molding quality, there can use low injection pressure and medium time. It can reduce residual stress in a certain extent, and more important can reduce the impact of the epoxy molding compound on the structures in the packages. And also through the production test, it verified the result and the new experimental method was right and reasonable.