Journal of the Korean Ceramic Society (한국세라믹학회지)

The Korean Ceramic Society (한국세라믹학회)
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A Study on the Resistance and Crack Propagation of ITO/PET Sheet with 20 nm Thick ITO Film

20 nm 두께의 ITO층이 코팅된 ITO/PET Sheet의 저항 및 균열형성 특성 연구

  • Kim, Jin-Yeol (Department of Advanced-materials Engineering, Chungnam National University) ;
  • Hong, Sun-Ig (Department of Advanced-materials Engineering, Chungnam National University)
  • 김진열 (충남대학교 신소재공학과) ;
  • 홍순익 (충남대학교 신소재공학과)
  • Published : 2009.01.31
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Abstract

The crack formation and the resistance of ITO film on PET substrate with a thickness of 20 nm were investigated as a function of strain. The onset strain for the increase of resistance increased with increasing strain rate, suggesting the crack initiation is dependent on the strain rate. Electrical resistance increased at the strain of 1.6% at the strain rates below $10^{-4}/sec$ while it increased at ${\sim}2%$ at the strain rates above $10^{-3}/sec$. The critical strain at which the cracks were formed is close to the proportional limit. Upon loading, the initial cracks perpendicular to the tensile axis were observed and propagated the whole sample width with increasing strain. The spacing between horizontal cracks is thought to be determined by the fracture strength and the interfacial strength between ITO and PET. The crack density increased with increasing strain. However, the effect of the strain rate on the crack density was less pronounced in ITO/PET with 20 nm ITO thickness than ITO/PET with 125 nm ITO thickness, the strength of ITO film is thought to increase as the thickness on ITO film decreases. The absence of cracks on ITO film at a strain as close as 1.5% can be attributed to the compressive residual stress of ITO film which was developed during cooling after the coating process. The higher critical strain for the onset of the resistance increase and the crack initiation of ITO/PET with a thinner ITO film (20 nm) can be linked with the higher strength of the thinner ITO film.

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References

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