Forming patterns of electrically conductive materials
A pattern of an electrically conductive print material is formed on a receiver element using an elastomeric relief element that has a relief pattern comprising (1) an uppermost relief surface, and (2) an average relief image depth of at least 50 μm relative to the uppermost relief surface. A printable material composition is applied to the uppermost relief surface, which printable material composition contains an electrically conductive print material and a carrier liquid. At least 50 weight % of the carrier liquid is removed from the uppermost relief surface, leaving the electrically conductive print material on the uppermost relief surface. Either the elastomeric relief element or the printable material composition on the elastomeric relief element, or both, are treated with an acid in vapor or liquid form to improve conductivity of the electrically conductive print material after it has been transferred from the uppermost relief surface to the receiver element.
1. A method for forming a pattern of a print material on a receiver element comprising a receptive surface, the method comprising the following features:
(a) providing an elastomeric relief element that comprises a relief pattern comprising (1) an uppermost relief surface, and (2) an average relief image depth of at least 50 μm relative to the uppermost relief surface,
(c) applying a printable material composition to the uppermost relief surface of the elastomeric relief element, the printable material composition comprising an electrically conductive print material and a carrier liquid,
(d) removing at least 50 weight % of the carrier liquid from the printable material composition that is disposed on the uppermost relief surface of the elastomeric relief element, leaving the electrically conductive print material on the uppermost relief surface,
(e) treating the printable material composition on the uppermost relief surface with an acid in vapor or liquid form to form a reacted electrically conductive print material on the uppermost relief surface, and
(f) transferring the reacted electrically conductive print material from the uppermost relief surface of the elastomeric relief element to a receptive surface of a receiver element,
carrying out at least one feature (e), and
repeating features (c) and (d), in the noted sequence, at least once using additional amounts of the same printable material composition and the same elastomeric relief element, to provide an increased amount of electrically conductive print material disposed on the uppermost relief surface.
2. The method of claim 1 , comprising at least one feature (e) using nitric acid, acetic acid, or hydrochloric acid in vapor or liquid form.
3. The method of claim 1 , comprising at least one feature (e) using hydrochloric acid in vapor or liquid form.
4. The method of claim 1 , wherein feature (e) is carried out using an acid in vapor form for at least 0.5seconds at a temperature of at least 20° C.
5. The method of claim 1 , wherein feature (e) is carried out using an acid present in solution at a concentration of at least 0.001 molar for at least 0.1 second.
6. The method of claim 1 , comprising in feature (d), removing at least 80 weight % of the carrier liquid from the printable material composition on the uppermost relief surface of the elastomeric relief element.
7. The method of claim 1 , wherein the printable material composition has a viscosity of at least 100 cps and up to and including 900 cps.
8. The method of claim 1 , wherein the elastomeric relief element is a flexographic printing member and the relief pattern has an average relief image depth of at least 100 μm relative to the uppermost relief surface.
9. The method of claim 1 , wherein the electrically conductive print material comprises nanoparticles of an electrically conductive material selected from the group consisting of silver, gold, copper, palladium, platinum, nickel, iron, indium-tin oxide, carbon black, combinations thereof, and precursors thereof.
10. The method of claim 1 , wherein the printable material composition comprises a colorant other than the electrically conductive print material.
11. The method of claim 1 for providing a pattern of the electrically conductive print material on the receiver element comprising lines having an average line width of less than 15 μm.
12. The method of claim 1 for providing a pattern of a multilayer structure that comprises an electroless seed material for a subsequent electroless plating process.
13. The method of claim 1 , wherein the receiver element has been heated before transferring either the electrically conductive print material or the reacted electrically conductive print material from the uppermost relief surface to the receptive surface of the receiver element having a glass transition temperature (T g ), the receiver element being heated to a heating temperature that is higher than the glass transition temperature (T g ) of the receiver element.
14. The method of claim 13 , comprising transferring either the electrically conductive print material or the reacted electrically conductive print material from the uppermost relief surface of the elastomeric relief element to the receptive surface in a manner such that the elastomeric relief element is compressed by at least 10 μm of its original thickness when measured at the heating temperature.