Roll-to-roll printing of silver oxide pastes and low temperature conversion to silver patterns

This paper reports a continuous roll-to-roll printing of mesh patterns of silver oxide pastes on flexible polymer films and subsequent thermal treatment at 150 °C of the patterned pastes to convert to silver patterns. The pastes consist of silver(I) oxide particles, silver salt of tertiary fatty acid, AgOCO-C(CH3)2-(CH2)n-CH3 and a-terpineol as the solvent. During the thermal process, nanosized silver particles were formed by the thermal reduction of silver oxide particles and the salt, followed by spontaneous condensation and further fusing, resulting in conductive silver films. The linear chain length n of silver salt, AgOCO-C(CH3)2-(CH2)n-CH3, in the pastes, affects the electrical conductivity of resulting silver films significantly. An optimal range of linear chain length is found as n - 5-9. In the case of the paste with n - 5, an optimal weight fraction range of the salt in the paste is found as 20-40 wt % if the solvent composition is held constant at 20 wt %. Using the paste with an optimal composition, we obtained high-performance electromagnetic wave interference (EMI) shielding films that have shown a comparable shielding effectiveness as that made of conventional sputtered metallic silver films.