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

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%).

E-Textile Seam Crossing with Screen Printed Circuits and Anisotropic Conductive Film

Screen printed circuits on substrates such as thermoplastic polyurethane (TPU) have been usedfor many years in certain wearable applications such as heart rate monitors [...]

Possibility of Fabricating Anisotropic Conductive Film with a Line-and-Space-Like Pattern by Stick-Slip Accompanying Abrasion

The development of an anisotropic conductive film was attempted using original microfabrication (stick-slip (SS) processing) involving SS accompanying abrasion. During SS processing, the film surface was periodically scraped with a razor. For a metal-deposited polyethylene terephthalate (PET) film (metal/PET film), fine periodic structures (line and space (L/S)-like patterns) were formed on its surface because the metal layer was periodically scraped. This result proved that SS processing can be applied not only to polymers but also to metals. Moreover, the line interval of an SS-processed metal/PET film shortened as the contact force decreased, and the depth of the line became shallower in proportion to the line interval. In addition, SS-processed copper/PET (Cu/PET) film did not conduct electricity in the direction perpendicular to the Cu line; however, it conducted electricity in the direction parallel. Thus, this study shows the possibility of using SS processing for fabricating an anisotropic conductive film.