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

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 mm2) 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 (εxy = 70%).

Air‐Permeable Waterproofing Electrocardiogram Patch to Monitor Full‐Day Activities for Multiple Days

“…The S‐ACF was made by embedding conductive microparticles in a thermoplastic stencil film with periodically‐arranged holes by following the previous work. [ 46 ] The permanent bonding between the ECG electrode line and the metal wire was accomplished at 80 ° C. The connection did not cause any electrical loss, and the adhesion was strong enough to prevent mechanical disconnection and electrical failure (Figure S6, Supporting Information). The other end of the FPCB‐based metal wire was connected to the MCU by using a metal snap button when the signal measurement is necessary.…”

“…The previous study for the preparation of the S‐ACF was followed. [ 46 ] The electrodes were connected to the MCU.…”

Printable inks and deformable electronic array devices

“…This connection is typically achieved using an anisotropic conductive film (ACF) or via holes. Although a stretchable-ACF (S-ACF) has recently been developed for 50 mm interconnetions, 219 vertical connections on the order of a few micrometers must be achieved for high-definition devices. Using a rigid power source is another hurdle for deformable devices.…”

Flexible hybrid electronics: Enabling integration techniques and applications

“…In recent years, stretchable electronics have been developed towards high-resolution ICs. For instance, Jeong and coworkers [44] fabricated a stretchable anisotropic conductive film (S-ACF) that could form strong covalent bonds at the contact interfaces at the temperature of 80°C, as demonstrated in Figure 3(e). Au/Ni-coated polystyrene conductive microparticles (MPs) with a diameter of 20 μm were periodically and precisely embedded in the thermoplastic polystyrene-block-poly(ethylene-ran-butylene)-block-polystyrene-graft-maleic anhydride (SEBS-g-MA) film, assuring the fine pitch capability (1200 μm 2 for a bump and 52.5 μm for a circuit line) and a low contact resistance (0.19 Ω per 0.25 mm 2 ).…”

“…(e) Schematic diagram of the fabrication scheme of stretchable S-ACF. Reproduced with permission[44]. Copyright@2021, AAAS.…”