Electrical and cyclic bending properties of screen-printed conductive patterns containing different ratios of silver microparticles and silver microflakes

Silver microparticles (Ag MPs) are widely used in conductive pastes for printed flexible electronics because of their easier synthesis and lower cost than silver nanoparticles. However, the cyclic bending reliability of the printed conductive patterns containing Ag MPs needs to be improved to use the devices under bending conditions. In this work, the conductive paste was prepared by mixing two silver pastes containing silver microparticles and silver microflakes (Ag MFs). These mixed pastes were screen-printed on PEN films to fabricate conductive patterns. Although the electrical resistivity increased 3.7 times as the Ag MFs content increased from 0 to 30 wt%, the bending stability was improved by Ag MFs in conductive patterns because the formation of crack under cyclic bending stress was suppressed. The increase of the resistivity was due to decreasing the number of electrical contacts caused by the formation of voids within the patterns containing a large amount of Ag MFs. These results are useful for designing printed conductive metal patterns with high bending stability.