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Control of Position of Neutral Line in Flexible Microelectronic System Under Bending Stress
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 Title & Authors
Control of Position of Neutral Line in Flexible Microelectronic System Under Bending Stress
Seo, Seung-Ho; Lee, Jae-Hak; Song, Jun-Yeob; Lee, Won-Jun;
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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.
Flexible microelectronics system;Face-down package system;Neutral line;Finite element analysis;
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아산화동과 황산간의 고속 화학반응에 의한 미세 Cu 입자의 합성과 삼본밀에 의한 분산성 개선,오상주;이종현;현창용;

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