Process for producing flexible optical waveguide
The present invention provides a process for producing a flexible optical waveguide which comprises the steps of: immersing a substrate having an optical waveguide formed thereon in water to thereby reduce adhesion between the optical waveguide and the substrate and then peeling the optical waveguide from the substrate; temporarily bonding the peeled optical waveguide to a surface of a pressure-sensitive adhesive layer containing a foaming agent; cutting the temporarily bonded optical waveguide into a given length; allowing the foaming-agent-containing pressure-sensitive adhesive layer after the cutting step to foam by heating, thereby reducing adhesion between the foaming-agent-containing pressure-sensitive adhesive layer and the optical waveguide; and peeling the optical waveguide cut into the given length from the foamed adhesive layer.
1. A process for producing a flexible optical waveguide which comprises the steps of:
immersing a substrate having an optical waveguide formed thereon in water to thereby reduce adhesion between the optical waveguide and the substrate and then peeling the optical waveguide from the substrate;
temporarily bonding the peeled optical waveguide to a surface of a pressure-sensitive adhesive layer containing a foaming agent;
cutting the temporarily bonded optical waveguide into a given length;
allowing the foaming-agent-containing pressure-sensitive adhesive layer after the cutting step to foam by heating, thereby reducing adhesion between the foaming-agent-containing pressure-sensitive adhesive layer and the optical waveguide; and
peeling the optical waveguide cut into the given length from the foamed adhesive layer.
2. The process for producing a flexible optical waveguide of claim 1 , wherein the substrate comprises at least one member selected from the group consisting of a silicon wafer, a silicon wafer coated with silicon dioxide, a blue plate glass, a synthetic quartz, and a polyimide resin.
3. The process for producing a flexible optical waveguide of claim 1 , wherein the optical waveguide formed on the substrate comprises at least:
an undercladding layer disposed on the substrate; and
a patterned core layer disposed on the undercladding layer.
4. The process for producing a flexible optical waveguide of claim 3 , wherein the undercladding layer comprises a fluorinated polyimide.
5. The process for producing a flexible optical waveguide of claim 3 , wherein the patterned core layer comprises a polyimide having a refractive index higher than that of the undercladding layer.
6. The process for producing a flexible optical waveguide of claim 3 , wherein the optical waveguide further comprises an overcladding layer disposed to surround the patterned core layer.
7. The process for producing a flexible optical waveguide of claim 6 , wherein the overcladding layer comprises a polyimide having a refractive index lower than that of the patterned core layer.
8. The process for producing a flexible optical waveguide of claim 1 , wherein the foaming agent contained in the pressure-sensitive adhesive layer is microencapsulated.
9. The process for producing a flexible optical waveguide of claim 1 , wherein the heating for allowing the foaming-agent-containing pressure-sensitive adhesive layer to foam is carried out at 100° C. to 150° C. for about 30 seconds to 1 minute.
10. The process for producing a flexible optical waveguide of claim 1 , wherein the foaming-agent-containing pressure-sensitive adhesive layer is supported by a support.
11. The process for producing a flexible optical waveguide of claim 10 , wherein the support comprises a polyester or a polypropylene.
12. The process for producing a flexible optical waveguide of claim 10 , wherein the support has a thickness of from 10 to 500 μm.