Ink-jet printed conductive films — Geometrical and electrical characterization

This paper presents the results of electrical and geometrical characterization of conductive films ink-jet printed on flexible substrates. Two commercially available single component nanoinks from Amepox, AX JP-6n and AX JP-60n, based on silver grains with 3-7 nm or 50-80 nm diameters were deposited onto Kapton or Mylar substrates and properly cured (sintered). Test structures, composed of a number of different patterns, allow optical inspection as well as measurement of geometrical (planar size, cross-section) and electrical (resistivity, sheet resistance) properties. Presented results show that the control of geometry of ink-jet printed films is more difficult to control than standard screen-printed ones. The cross-section of such paths has two lateral peaks (sometimes very strong) and very thin layer between them. This is related with viscosity and surface tension of the applied ink. There are also large differences in sheet resistance of layers - both kind of inks as well as substrate affects this parameter. The smallest received value, about 8 mΩ/sq (recalculated for 25 μm thick film) is larger than for high-temperature silver cermet pastes (approx. 2-3 mΩ/sq), but smaller than for polymer thick-film conductive inks (approx. 10-30 mΩ/sq).