Electrical characterization of printed circuits on the fabric

Abstract

Fabrication methods of planar printed circuits on fabrics are introduced and their electrical characteristics are measured and analyzed. Wet patterning method like screen printing as well as dry process of sputtering are used to fabricate the patterned film electrodes on various types of fabrics. The minimum width of the patterns is 0.2mm for screen printing and 0.1mm for gold sputtering, and the typical sheet resistance is 44mΩ/□. Fabrication methods of capacitors of 1pF~1nF and inductors of 500nH~1μH at 10MHz on the fabrics are also introduced. Bonding and packaging of silicon chip directly on the fabric circuit board are proposed and their mechanical properties are investigated. The AC impedance of the transmission line is measured as 201 ~ 215Ω with < 7.4% variation, and the TDR profile shows that the -3dB frequency of the printed transmission line of 15 cm on the fabric is 80MHz. A complete system composed of a fabric capacitor sensor input, a controller SoC, and an LED array display is implemented on the fabric and its operation is demonstrated successfully.