Method of manufacturing a touch sensor with a low visibility conductive micro-mesh
Light reflection from a metal mesh touch sensor is reduced or prevented by encasing the metal lines with a passivation coating and including non-reflective nanoparticles in the patterning photoresist. The photoresist is mixed with catalytic nanoparticles wherein the nanoparticles are formed to minimize light reflection. The nanoparticles may be carbon coated metallic particles, or uncoated palladium nanoparticles. Also, a standoff photoresist layer may be included between the substrate and the photoresist composition to prevent reflection from the edges of the metallic lines.
1. A method of manufacturing a touch sensor with a conductive micro-mesh comprising:
dispersing carbon-coated metallic nanoparticles into a photoresist to form a catalytic photoresist composition;
applying a standoff layer over a transparent substrate of the touch sensor;
applying the catalytic photoresist composition over the standoff layer;
photo patterning the standoff layer and the catalytic photoresist composition to have a layer of catalytic photoresist pattern over a standoff layer pattern;
plating a metal layer on the layer of catalytic photoresist pattern; and
applying a metal passivation layer over the metal layer.
2. The method of claim 1 , wherein dispersing the carbon-coated metallic nanoparticles to form a catalyst component content comprises dispersing the nanoparticles in a range between 5 percent and 70 percent by weight into a photoresist composition forming photoresist component content in a range between 30 percent and 95 percent by weight.
3. The method of claim 2 , wherein the catalytic photoresist composition includes negative photoresist component content in a range between 50 percent and 70 percent by weight and catalyst component content in a range between 30 percent and 50 percent by weight.
4. The method of claim 1 , wherein the carbon-coated metallic nanoparticles have a size between 15 to 30 nanometers.
5. The method of claim 1 , wherein plating the metal layer comprises forming a gap between the metal layer and the substrate, thus exposing the standoff layer between the catalytic photoresist composition and the transparent substrate.
6. The method of claim 1 , further comprising applying the catalytic photoresist composition to both sides of the substrate.
7. The method of claim 1 , wherein the catalytic nanoparticles include carbon coated silver nanoparticles.
8. The method of claim 1 , wherein the catalytic nanoparticles include carbon coated copper oxide nanoparticles.
9. The method of claim 1 , wherein the metal layer includes copper.
10. The method of claim 1 , wherein the metal passivation layer includes palladium.
11. A method for fabricating a touch sensor, comprising:
dispersing carbon-coated metallic nanoparticles into a photoresist to form a catalytic photoresist;
applying a standoff layer over an optically transparent substrate, the standoff layer formed of non-catalytic photoresist;
applying the catalytic photoresist over the standoff layer;
photo patterning the standoff layer and the catalytic photoresist to form a layer of catalytic photoresist patterns over standoff patterns on the optically transparent substrate; and,
plating a metal layer on the layer of catalytic photoresist patterns.
12. The method of claim 11 , further comprising applying a metal passivation layer over the metal layer.
13. The method of claim 12 , further comprising applying the optically transparent substrate to a display device.
14. The method of claim 12 , further comprising adhering the optically transparent substrate to a display device using optically clear adhesive.
15. The method of claim 12 , wherein the metal passivation layer includes palladium.
16. The method of claim 11 , further comprising applying a metal passivation layer over the metal layer and into a gap formed between the catalytic photoresist composition and the transparent substrate.
17. The method of claim 11 , wherein dispersing carbon-coated metallic nanoparticles comprises dispersing one of carbon-coated silver nanoparticles or carbon-coated copper nanoparticles to form a catalyst component content in a range between 5 percent and 70 percent by weight into a photoresist composition forming photoresist component content in a range between 30 percent and 95 percent by weight.
18. The method of claim 17 , wherein the catalytic photoresist composition includes negative photoresist component content in a range between 50 percent and 70 percent by weight and catalyst component content in a range between 30 percent and 50 percent by weight.
19. The method of claim 11 , wherein the carbon-coated metallic nanoparticles have a size between 15 to 30 nanometers.
20. The method of claim 11 , wherein the carbon-coated metallic nanoparticles include carbon coated silver nanoparticles.
21. The method of claim 11 , wherein the carbon-coated metallic nanoparticles include carbon coated copper oxide nanoparticles.
22. The method of claim 11 , wherein the metal layer includes copper.