Roll to Roll Printing for Plastic Electronics

A recent newsletter from PolyIC (18th May 2010) highlights their technology for coating thin flexible films with transparent and conductive layers in a roll-to-roll process.  A press release from 6th October  2009 further describes the potential for this technology and provides some technical details around the high resolution capability (15 micron lines).  Applications include displays, touch sensors and heating elements.

Searching the patent literature reveals that PolyIC have a few US patents already granted and more in the pipeline.  The one most closely related to this appears to be US7479670B2.  While it may not be directly relevant it is useful in that it contains many references on the subject matter.  The first four claims relate to the material and are reproduced below:

1. An electronic component made from primarily organic material, comprising: an electrically insulating substrate and/or lower layer having a depression formed by a laser; and at least one electrical conductor track and/or electrode in the depression, the depression having steep walls, sharp contours and a relatively rough bottom surface, the at least one conductor track and/or electrode comprising at least one electrically conductive material for interconnecting electrical components on the substrate.

2. The electronic component as claimed in claim 1, having at least two conductor tracks and at least two electrically conductive electrodes and a distance l smaller than 10 μm between the two conductor tracks, the at least two electrodes and/or between a conductor track and an electrode.

3. The electronic component as claimed in claim 1 wherein the conductor track and/or electrode comprises at least one metallic layer or metal alloy layer.

4. The electronic component as claimed in claim 1 wherein at least one layer of the conductor track is organic material.

You will note that claim 2 makes reference to gaps of smaller than 10 microns between the electrodes or electrode and track, although the description in the main patent section refers to this distance being smaller than 20 microns.  Interesting.  The particular significance of this distance is for construction of FETs where the source to drain distance needs to be a minimum.  This patent may therefore be specific to manufacture of OFETs.

The next claims relate to the process and are reproduced below:

5. A method for producing an organic electronic component with a conductor track or electrode, the component having an insulating lower layer and/or a substrate, the method comprising treating the lower layer and/or substrate with a laser such that at least one depression and/or one modified region are formed in the lower layer and/or the substrate, then filling the depression and/or modified region with an electrically conductive material to thereby produce the conductor track and/or electrode from the electrically conductive material for interconnecting electrical components.

6. The method as claimed in claim 5, including the step of mechanically structuring the electrically conductive material.

7. The method as claimed in claim 5 in which superfluous electrically conductive material is produced, the method including wiping off the superfluous conductive material in a process step following the application of the layer.

8. The method as claimed in claim 6 including forming the at least one depression and/or one modified region with a pulsed laser.

9. The method as claimed in claim 6 which is carried out in a continuous roll-to-roll process.

10. The method as claimed in claim 5 wherein the electrically conductive material is metallic.

These reveal that laser or mechanical patterning is used to assist in the placement of the conductive tracks which must help to achieve the high resolution.  Exact details for how the roll-to-roll process is achieved are not given.

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