Department of Chemical Engineering, National Taiwan University, No. 1 Sec. 4 Roosevelt Road, Taipei 10617, Taiwan
For printed electronic devices, metal thin film patterns with great conductivities are required. Three major ways to produce inkjet-printed metal tracks will be shown in this video. The most commonly-used one is silver nanoparticle ink. Typically, after ink loading, stable droplet ejection is needed for good printing quality. The printed silver tracks need to be sintered at a relatively high temperature for particles to fuse together, which can be observed from the color change after heating. The tracks can exhibit great conductivity close to that of bulk silver.
The second type is metal-organic decomposition. Well-printed ink patterns with great pattern fidelity can be formed by tuning print parameters like dot spacing. The printed silver salts are then transformed into silver after heated at 70 degree C for 10-20 minutes. Several tests, such as resistance measurements, bending and tape tests, are also performed to demonstrate the great conductivity, mechanical stability, and adhesion of printed silver tracks on flexible substrates.
The last demonstration is the inkjet reaction system. First, two inks are printed separately on the substrate. These two inks react and the so-called silver-mirror reaction generate silver over the printed area at room temperature. After rinsing the printed thin film and dried at 70 degree C, the printed track shows good conductivity.
The authors would like to thank Mr. Kuan-Ming Huang and Mr. Chia-Wei Chang for their great help in recording and editing video clips.