| Summary: | 碩士 === 長庚大學 === 機械工程學系 === 101 === Multi-Chip Package (MCP) has gained increasingly interest in IC assembly industry. For increasing the chip number in the same package size or even smaller, the constituent materials of MCP should be smaller and thinner. The package tends to suffer from large deformation and even structural failure under thermal loading due to mismatch of the coefficients of thermal expansion (CTE) among the materials. The chemical shrinkage of the molding material after curing process may also influence the package warpage. The purpose of this study is to analyze the effects of stacking types (stepped and symmetrical types) and material properties on thermal deformation of MCP. A full-field shadow moiré system is used to measure the out-of-plane deformation of MCP during heating and cooling processes. Finite element method (FEM) simulation and Timoshenko theory are used to calculate the thermal deformation and quantify the chemical shrinkage of MCP, respectively. In this study, the Young’s modulus (E) and CTE of substrate are measured with dynamic mechanical analyzer (DMA) and thermal mechanical analyzer (TMA), respectively. The results show the warpage of MCP would decrease after thermal cycles due to the release of the residual strain of package. Besides, the warpage of both stacking types for MCP are different, which indicates that the stacking type and position of chips in MCP would affect the chemical shrinkage of molding compound during manufacturing process. It's found that the thermal deformations of the packages calculated from FEM are well consistent with experimental ones. Finally, the parametric study shows that Young’s modulus of substrate would significantly affect the deformation of MCP, and the lower stiffness of die-attach material would induce smaller MCP warpage.
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