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Seo, Seung-Ho;Lee, Jae-Hak;Song, Jun-Yeob;Lee, Won-Jun
- Journal of the Microelectronics and Packaging Society
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- v.23 no.2
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- pp.79-84
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- 2016
A flexible electronic device deformed by external force causes the failure of a semiconductor die. Even without failure, the repeated elastic deformation changes carrier mobility in the channel and increases resistivity in the interconnection, which causes malfunction of the integrated circuits. Therefore it is desirable that a semiconductor die be placed on a neutral line where the mechanical stress is zero. In the present study, we investigated the effects of design factors on the position of neutral line by finite element analysis (FEA), and expected the possible failure behavior in a flexible face-down packaging system assuming flip-chip bonding of a silicon die. The thickness and material of the flexible substrate and the thickness of a silicon die were considered as design factors. The thickness of a flexible substrate was the most important factor for controlling the position of the neutral line. A three-dimensional FEA result showed that the von Mises stress higher than yield stress would be applied to copper bumps between a silicon die and a flexible substrate. Finally, we suggested a designing strategy for reducing the stress of a silicon die and copper bumps of a flexible face-down packaging system.
https://doi.org/10.6117/kmeps.2016.23.2.079 인용 PDF KSCI

Kim, Byoung-Joon
- Journal of the Microelectronics and Packaging Society
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- v.20 no.4
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- pp.1-6
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- 2013
Recently, various types of flexible devices such as flexible displays, batteries, e-skins and solar cell panels have been reported. Most of the researches focus on the development of high performance flexible device. However, to realize these flexible devices, the long-term reliability should be guaranteed during the repeated deformations of flexible devices because the direct mechanical stress would be applied on the electronic devices unlike the rigid Si-based devices. Among various materials consisting electronics devices, metal electrode is one of the weakest parts against mechanical deformation because the mechanical and electrical properties of metal films degrade gradually due to fatigue damage during repeated deformations. This article reviews the researches of fatigue behavior of thin metal film, and introduces the methods to enhance the reliability of metal electrode for flexible device.
https://doi.org/10.6117/kmeps.2013.20.4.001 인용 PDF KSCI