Dynamic characteristics measurements of inkjet-printed thin films of nanosilver suspensions on a flexible plastic substrate

The dynamic properties of inkjet-printed thin films on flexible polyimide (PI) substrates were investigated using the vibration analysis adopting wave approach. In order to fabricate the test specimens, the Ag nanoparticle suspension was inkjet printed on the plasma-treated PI substrate and sintered at different temperatures. The beam-shaped Ag-printed PI specimens with 30 mm length and 0.6 mm width were prepared by pico-second laser pulse cutting and were used as the cantilever beam in the vibration test. From the base-excited response of the beam, the frequency-dependent bending stiffness and loss factor were obtained, which were used to calculate Young's modulus and loss factor of the inkjet-printed thin films. The influence of the sintering temperature and film thickness on the dynamic properties was investigated and the nanoindentation test was also performed to compare results from each test. Young's modulus increased and loss factor decreased with increasing sintering temperature and the effect of the film thickness was not significant. Young's modulus from the vibration analysis was in comparable agreement with that from the nanoindentation test. The proposed method enables the direct determination of the dynamic characteristics of thin films without damaging the thin films as well as removing the substrate.