Co-shaft in-situ rolling-imprinting technique for printing of silver micro-nanowire array

A ‘co-shaft in-situ rolling-imprinting technique’ is proposed for the production of a silver micro-nanowire array with ultra-high slenderness ratio on transparent polyethylene terephthalate (PET) film. Two major mechanisms microrolling-tooth array mold cutting and silver micro-nanowire array rolling-imprinting are designed for the rolling-imprinting system. The setup allowed for mold cutting and micro-nanowire rolling-imprinting to be conducted in the same coordinate system with the same concentric accuracy. To provide steady micro-amounts of silver-paste supply, a silver-paste supply mechanism was designed comprising a fine screw thread, paste storage tank and comb-shaped microchannel array. Experiments show by changing surface roughness so that the contact angle of the silver-paste on the roller mold is larger than on the PET film, it was possible to transfer of silver-paste smoothly onto the PET film. Doctoring blade placement was optimized by using optimal letterpress-width and minimal letterpress-gap to ensure silver-paste was scraped off the roller mold in a manner that minimized wire-width. Silver-paste molecules were subject to optimal congregation effect to ensure minimal wire-width for a 5-μm letterpress-width, 1-μm letterpress-gap, and Ra 6-nm surface roughness on the roller mold. The study utilized silver-paste's innate ‘internal force balance characteristic’ to great effect. The resultant silver micro-nanowires were 5.1 μm is width, 1 μm in thickness and of ultra-high slenderness ratio, high-straightness, -consistency and -regularity. The effectiveness of the array was tested driving a LED device. The influence of convex versus concave microrolling-tooth molds, droplet forces, and silver-paste thixotropy were also all discussed in detail.