Methods of forming printed circuit boards having optical functionality
View Patent ↗Provided are methods of forming printed circuit boards having optical functionality. The methods involve applying a dry-film to a printed circuit board substrate and forming an optical waveguide over the dry-film. The invention finds particular applicability in the electronics and optoelectronics industries.
1. A method of forming a printed circuit board having optical functionality, comprising:
applying a dry-film layer to a printed circuit board substrate; and
forming an optical waveguide directly on the dry-film layer, the forming comprising:
forming a first clad layer directly on the dry-film layer, wherein the first clad layer forms a lowermost portion of the waveguide;
forming a core layer on the first clad layer;
patterning the core layer to form a core; and
forming a second clad layer on the first clad layer and the core.
2. The method of claim 1 , wherein the dry-film layer is of a type which is useful as solder-mask or dielectric dry-film layer.
3. The method of claim 1 , wherein the waveguide core and/or clad comprises units of the formula (RSiO 1.5 ), wherein R is a substituted or unsubstituted organic group.
4. The method of claim 1 , further comprising forming a second optical waveguide on the optical waveguide in a stacked arrangement.
5. The method of claim 4 , further comprising applying a second dry-film layer on the waveguide and forming the second optical waveguide directly on the second dry-film layer.
6. The method of claim 1 , further comprising before formation of the clad, treating the surface of the dry-film layer to improve adhesion to the waveguide.
7. The method of claim 6 , wherein the treating comprises one or more of mechanical polishing or treatment with corona discharge, flame, ozone or plasma.
8. The method of claim 1 , further comprising forming electrical circuitry on the printed circuit board substrate.
9. A printed circuit board formed by the method of claim 1 .
10. The method of claim 1 , wherein the dry-film layer is formed of a material chosen from acrylates, urethanes and epoxies.
11. The method of claim 3 , wherein the dry-film layer is formed of a material chosen from acrylates, urethanes and epoxies.
12. The method of claim 11 , wherein the waveguide core and clad comprise units of the formula (RSiO 1.5 ), wherein R is a substituted or unsubstituted organic group.