Stretchable anisotropic conductive film (S-ACF) for electrical interfacing in high-resolution stretchable circuits.

Hwang, Hyejin; Kong, Minsik; Kim, Kyunghwan; Park, Doowon; Lee, Sangyeop; Park, Soojin; Song, Ho-Jin; Jeong, Unyong · Sci Adv · 2021

basic_science · Level V

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Abstract

In stretchable electronics, high-resolution stretchable interfacing at a mild temperature is considered as a great challenge and has not been achieved yet. This study presents a stretchable anisotropic conductive film (S-ACF) that can electrically connect high-resolution stretchable circuit lines to other electrodes whether they are rigid, flexible, or stretchable. The key concepts of this study are (i) high-resolution (~50 μm) but low-contact resistance (0.2 ohm in 0.25 mm<sup>2</sup>) interfacing by periodically embedding conductive microparticles in thermoplastic film, (ii) low-temperature interfacing through the formation of chemical bonds between the S-ACF and the substrates, (iii) economical interfacing by selectively patterning the S-ACF, and (iv) direct interfacing of chips by using the adhesion of the thermoplastic matrix. We integrate light-emitting diodes on the patterned S-ACF and demonstrate stable light operation at large biaxial areal stretching (ε<sub>xy</sub> = 70%).