Printing of conducting inks on paper

摘要

Paper has many attractions as a substrate for the manufacture of flexibleelectronics, particularly the comparative ease of recycling and recovering theconstituents of the inks. However, it is not as smooth as the polymer substratesand also does not normally have sufficient barrier properties for sensitivereactive inks. By careful attention to the coating process a paper has beencreated that has sufficient smoothness for printing of electronics. As a first stageof the evaluation of this coated stock, a series of trials have been undertakenwhere appropriate images have been offset printed using a silver conducting ink.This paper presents an analysis of the images in terms appropriate for themanufacture of electronics. It looks at traditional concepts, such as tone gain, asthis affects the minimum printable line. The surface roughness, both of theprinted image and the paper, edge straightness, defects (including shorts), theresistance of the lines and the impedance of fine line gaps were measured. Theseare evaluated through two print runs to provide consistency data as required forthe manufacture of electronics.In the second print run, an overprint was used to increase the film thickness andhence reduce the resistance of the conductors. This highlighted the problemsassociated with wet on wet printing and the difficulties of obtaining continuitybetween the two layers.The results are encouraging and show the potential of paper as a substrate forvolume manufacture of disposable electronics.