Methods of optical filament scribing of circuit patterns with planar and non-planar portions
View Patent ↗Methods of forming optical filament circuit patterns with planar and non-planar portions are provided. An optical filament circuit pattern is scribed by moving a filament guide and a substrate relative to one another at a speed between about 110 inches/minute and about 190 inches/minute, and dispensing an optical filament on, or in the vicinity of, a surface of the substrate. The filament or the substrate or both have adhesive surface(s). The adhesive surface is capable of being adhesively actuated by application of energy. Energy is applied simultaneous with, or subsequent to, scribing. Preferably, ultrasound energy is applied having an output power between about 2.0 watts and about 3.5 watts while applying a pressure to the filament between about 1.177 Newtons and about 1.324 Newtons. A portion of the filament circuit pattern is planar and another portion is non-planar. The non-planar portion traverses but does not contact or adhere to a pre-selected area of the substrate. The pre-selected area corresponds with a pad, a contact pattern, a hole, a slot, a raised feature, a part of the previously scribed planar portion of the pattern, and a filament termination point. Alternately, the non-planar portion may be embedded below the surface of the substrate. Another planar portion of the filament circuit traverses the non-planar portion but does not contact or adhere to a pre-selected part of the previously scribed non-planar portion. Optical filament-scribed circuit boards are formed by this method.
1. A method of forming an optical filament circuit pattern having planar and non-planar portions on or in the vicinity of a surface of a dielectric substrate, the method comprising:
scribing at a speed between 110 inches/minute and 190 inches/minute a pre-selected length of a continuous optically conductive filament in a plane parallel to the substrate surface and on or in a vicinity of the substrate surface to form a planar portion of the circuit pattern from the scribed length of filament;
forming a non-planar portion of the circuit pattern by controllably moving the filament in planar and non-planar directions and placing a next pre-selected length of the continuous filament that is contiguous to the immediately preceding scribed length so that the next pre-selected length of filament traverses but does not adhere to a pre-selected surface or feature forming part of the substrate surface; and
scribing at a speed between 110 inches/minute and 190 inches/minute in a plane parallel to the substrate surface, and on or in a vicinity of the substrate surface a next pre-selected length of the continuous filament that is contiguous to the length of the filament that forms the non-planar portion of the filament circuit to form another planar portion of the circuit,
wherein a bond strength between the optical filament and the substrate is achieved of between 7 grams and 14 grams.
2. The method of claim 1 , wherein the substrate or the filament or both have an adhesive surface capable of being activated by application of energy, and wherein scribing steps (a) and (c) comprise:
feeding the filament to a filament guide, while moving the filament guide and the substrate relative to each other, so that a length of filament is dispensed from the filament guide onto the surface of the substrate in the filament circuit pattern; and
simultaneously or subsequently applying energy capable of activating the adhesive surface of the substrate and/or the filament forming a pre-selected circuit path, so that the filament adheres to the substrate in the filament circuit pattern.
3. The method of claim 2 , wherein the filament guide and the substrate are moved relative to each other at a speed of about 150 inches/minute.
4. The method of claim 3 , wherein the filament guide is moved relative to the substrate and the substrate is kept stationary.
5. The method of claim 3 , wherein the substrate is moved relative to the filament guide and the filament guide is kept stationary.
6. The method of claim 5 , wherein the step of applying energy comprises applying energy in a form selected from a group consisting of heat, ultrasound, pressure, and combinations thereof.
7. The method of claim 6 , wherein the step of applying energy to activate the adhesive surface comprises ultrasonic energy to the surface.
8. The method of claim 6 , wherein the step of applying energy to activate the adhesive surface comprises heating the surface to within a temperature range of 90° and 160° F.
9. The method of claim 2 , wherein the step of applying energy comprises applying ultrasound energy having an output power between 2.0 watts and 3.5 watts.
10. The method of claim 9 , wherein the ultrasound energy has an output power between about 2.5 watts and about 3.0 watts.
11. The method of claim 9 , wherein the step of applying energy further comprises applying a pressure to the filament between 1.177 Newtons and 1.324 Newtons.
12. The method of claim 11 , wherein the pressure between about 1.275 Newtons and about 1.324 Newtons.
13. The method of claim 1 , wherein step (b) comprises:
interrupting the application of energy so that the filament does not adhere to the pre-selected surface, or feature forming part of the surface, of the substrate;
moving a filament guide and the substrate away from each other in a Z-axis direction perpendicular to the plane defined by the surface of the substrate;
traversing the pre-selected surface, or feature forming part of the surface, of the substrate by moving the filament guide and the substrate relative to each other in a plane parallel to the plane defined by the surface of the substrate, while feeding the filament to the filament guide so that the next pre-selected length of the continuous filament is dispensed over, but does not contact the pre-selected surface, or feature forming part of the surface, of the substrate; and
moving the filament guide and the substrate closer to each other in the Z-axis direction until the filament guide is positioned in a plane defined by the planar portion of the circuit pattern.
14. A method of optical filament scribing comprising:
scribing at a speed between 110 inches/minute and 190 inches/minute a pre-selected continuous length of an optical filament to a surface of a thermoplastic substrate to form a filament circuit pattern having a pre-determined path; and
applying sufficient energy to the filament or substrate to achieve a bond strength between the filament and the substrate between 7 grams and 14 grams.
15. The method of claim 14 , wherein the filament circuit pattern has at least one crossover.
16. The method of claim 15 , wherein the scribing step comprises:
scribing a first substantially planar portion of the filament circuit pattern by controllably moving and placing a pre-selected length of the continuous filament in a plane parallel to the substrate surface to form; and
scribing a substantially non-planar portion of the filament circuit pattern by controllably moving the filament in planar and non-planar directions and placing a next pre-selected length of the continuous filament that is contiguous to the immediately preceding scribed length so that the next pre-selected length of filament traverses but does not adhere to a pre-selected surface or feature forming part of the substrate surface; and
scribing a second substantially planar portion of the filament circuit pattern by controllably moving in a plane parallel to the substrate surface and placing a next pre-selected length of the continuous filament that is contiguous to the length of the filament that forms the non-planar portion of the filament circuit.
17. An apparatus for optical filament scribing comprising:
means for scribing at a speed between 110 inches/minute and 190 inches/minute a pre-selected continuous length of an optical filament to a surface of a thermoplastic substrate to form a filament circuit pattern having a pre-determined path; and
means for applying sufficient energy to the filament or substrate to achieve a bond strength between the filament and the substrate between 7 grams and 14 grams.