Reliability Test of Inkjet-Printable Silver Conductive Ink

Abstract

Inkjet printing is a promising technique for fabricating printed electronics. This technique acquires the utilization of conductive ink to form a fine and thin resolution conductive structure on a flexible substrate. The challenges are to design a stable conductive ink with a controlled properties to prevent nozzle clogging. Furthermore, a fine structure construction often demonstrated poor device performance due low mechanical durability. In this work, we have characterized morphology of the newly developed inkjet-printable nanosilver conductive ink (Mi-Ag) in our laboratory. The ink shows a stable colloidal ink zeta potential of-79.1 mV with nanoparticle size less than 100 nm properties has been tailored for compatibility with inkjet printing of conductive pattern on polyethylene terephthalate (PET) flexible substrate. It has been ascertained that the flexible electronic form factor affects the quality of the physical and electrical properties of printed pattern and the device performance. Hence, the bending test of the printed RFID patterns fabricated with different layer of thicknesses was investigated. Electrical properties of the samples were monitored by in-situ conductivity and resistivity measurement under cyclic bending testing. Pattern with thinnest layer of 1.31μm (1X) had the smallest electrical properties percentage drop (38.4%) at 12,000 bending cycles due to the fact that in thick layer, the interparticle network started to change during bending and became weaker due to the large amount of the particles in the dense printed layer. In contrast, printed device exhibited minimal increase in resistivity. Consequently the particle gap increased which allowed the movement of electrons, leading to the increased of electrical resistance. The device endurance characteristic is crucial to satisfy future design requirement of flexible electronic applications.