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One disincentive to the encapsulation of semiconductor devices using transfer molding is the resulting deterioration in releasability. This is because deterioration in releasability causes the chip to crack and external appearance defects to be transcribed from the mold stain. In this study, the authors have measured the in situ release force using an actual semiconductor package (LQFP2020), and have investigated the release behavior by numerically simulating the release process. The release force was found to be about 5 to 8 N, and the release time was 30 ms or less after continuous molding of 300 shots. The relationship between various release factors and the release force was also investigated. With regard to the surface roughness of the mold cavity, the release force of a ldquosatin-finished surfacerdquo was about half of that of a ldquomirror surface.rdquo In addition, the release force was slightly reduced by reducing the cure time and the release speed.
Electronics Packaging Manufacturing, IEEE Transactions on (Volume:30 , Issue: 3 )
Date of Publication: July 2007