The development and investigation of highly stretchable conductive inks for 3-dimensional printed in-mold electronics

摘要

We developed and investigated highly stretchable conductive inks for three-dimensional in-mold electronics technology, which enables injection molding and installation of electronic circuits and optical devices with hard coating lamination through a one-step process. Ag was selected as a conductive filler, and we combined Ag particles of various shapes, including nanowires. Highly stretchable binders with excellent miscibility in the conductive filler combinations were formulated well. A fluorine rubber binder with high electronegativity generated new Ag nanoparticles through heat treatment, resulting in higher electrical conductivity. After the formulation of the stretchable conductive inks, circuit patterns were screen-printed precisely, and a one-step injection molding process was conducted. It was noted that, after a high-temperature, high-pressure in-mold electronics process, the conductive fillers of the ink circuits were tightly packed, resulting in a considerable increase in their electrical conductivity. The highly stretchable conductive ink with Ag nanowireFR-2, constituting the circuits of the in-mold electronics product, exhibited a conductivity of 17.416 kS/cm even under a design strain of 4.77%.