Thermal Deformation Analysis of Electronic Packages by Moire Interferometry and Phase-Shifting Method

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In the present research work, moire interferometry was applied to analyze thermal deformations of electronic packages, QFP (Quad Flat Package), MCM (Multi Chip Module) and FC (Flip-Chip Package). High-resolution moire interferometry was also developed to determine thermal displacements and strains of electronic packages, SOJ (Small Outline J-Leaded Package) and Stacked-MCP (Multi Chip Package). The conclusions from the present study can be summarized as follows.The thermal deformations of QFP and MCM packages measured by moire interferometry showed that high deformations occurred at the edges and corners of the chip. When the QFP was mounted on PWB (Printed Wiring Board), the deformations increased due to the influence of the substrate with high CTE (Coefficient of Thermal Expansion). It is also found that the number of chips and their locations in MCM greatly affected the package deformation.The thermal deformations of FCs were evaluated and the effects of underfill and substrate were … More investigated. The results showed that the underfill created similar curvatures between the chip and substrate. The multi-layer substrate decreased the CTE mismatch between the chip and substrate and the bending deformations of the packages. It is found that the thermal strains of solder balls were the smallest in the package underfilled and mounted on multi-layer substrate.Phase-shifting moire interferometry and digital image processing were developed and applied to nano-order resolution measurement in the displacements. The digital image processing made it possible to analyze the strain fields accurately.The phase-shifting method was also applied to the thermal deformation analyses of SOJ and Stacked-MCP. The results of the two packages showed that the normal strains were high at the ends of the chip, and the shear strain concentrated at the chip corners. The strain values in SOJ increased by about 50% when the package was mounted on PWB. In Stacked-MCP, the normal strain also concentrated at the interface of the two chips. The shear strain at the ends of the lower chip increased by about 76% with a temperature change of 25 deg.C. Less