Flexo printing of fine lines

Flexography is being considered for the volume reel to reel printing of flexible electronics and sensors. It is critical that the process accurately and consistently reproduces small features, particularly gaps and lines. Two plates were made using conventional and digital plate making technology. These were geometrically characterised and compared to the prints produced under identical conditions. The manufacture of gaps, key to semi-conductors and sensors, highlighted the complex geometric shape on the plate and its potential interaction with the substrate during printing. Each gap had a ridge between it and the solid plateau area. While the width of the gap was similar to the width between the two plateau, the printed line was in most cases approximately double the width. The ridge acts as a bund retaining the ink on the plateau and preventing it from filling in the gap. The main differences between the plate technologies was found in the gaps produced on the plates. The conventional plate produced shallower gaps with more gently sloped sides at the top of the gap. The printed lines were similar from both technologies, but double the width on the plate. The printed acute and right angled corners were affected by the plate geometry leading to rounding of the outside edges and filling in of the angle between the lines.