We experimentally examined the warpage behavior of a viscoelastic three-layer laminated structure consisting of steel/epoxy resin/printed board which modeled that of electronic devices caused simply by a series of thermal load from heating to cooling. We also calculated the warpage behavior using the finite element method and a thermo-viscoelastic stress/deformation analysis program based on linear viscoelastic theory which we have developed. Then, those experimental values were compared with those two theoretical values. From our results, the experimental warpage values are in good agreement with the thermo-viscoelastic analysis values, but are not in good agreement with the finite element analysis values. In addition, the warpage behavior of the viscoelastic three-layer laminated structure is influenced not only by the material properties such as glass transition temperature, modulus of longitudinal elasticity, and thermal expansion coefficient which depend on the temperature and flexural rigidity based on the thickness and width of the three-layer laminated structure.

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When a passive component electrode is metalized, conventional barrel electrolytic plating is used. However, as the size of the component becomes smaller, it is difficult to perform plating uniformly. In order to solve this problem, we carried out electroless plating, achieving selective electroless deposition on the metallic electrodes of the micro passive chip component.

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We developed a simple method for accurately predicting the warpage of the ball grid array (BGA) interposer in consideration of the wiring layers. In recent years, this interposer has become thinner, so the influence of the wiring layers has become larger. Consequently, modeling the wiring layers is important for predicting the warpage of the BGA package. However, detailed modeling of the wiring layers causes an increase of the analysis scale. For this reason, we calculated the anisotropic material properties of the wiring layers using the homogenization method. From this, we reveal that it is possible to achieve the same precision as that of a real wiring shape model while decreasing the analysis scale by using this method. We also reveal that this method is effective for high temperatures.

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