Abstract Multilayer printed circuit board is fabricated by coating a suitable substrate, metal, plastic, paper, with a photosensitive coating, exposing the photosensitive coating to form a dielectric thereof, coating the dielectric layer with a coating of a photosensitive chemical solution, selectively imaging and developing the photosensitive coating to form a desired circuit pattern on the dielectric coating, forming a first layer of circuitry by coating the circuit pattern with a conducting material, coating the circuitry bearing layer with a second layer of photosensitive material, selectively exposing and developing the second layer of photosensitive material to form a dielectric with open windows to the first circuit layer, coating the second dielectric layer of the first circuitry with a coating of photosensitive chemical solution, selectively imaging and developing the coating of photosensitive chemical solution to form a circuit pattern and an interconnect pattern and forming a conductor layer of circuitry and interconnects, the interconnect metallization connecting the second circuitry layer with the first circuitry layer, repeating the process to form additional circuitry layers to perform a desired electrical function and forming on the last dielectric layer a metallization such as either a solder mask for circuit terminals or a ground plane and thereafter either retaining the substrate if desired for, for example, a heat sink or additional support or both, or removing the substrate to form a very light weight multilayer printed circuit board.
A method for fabricating a multilayer printed wiring circuit board comprising: a. forming a dielectric layer on a substrate; b. coating the dielectric layer with a first layer of photosensitive material; c. selectively exposing the first layer of photosensitive material to form a layer defining a first conductor pattern of exposed photosensitive material; d. forming the conductor pattern with a conductor material to form conductors in the conductor pattern; e. coating the circuit bearing layer with a layer of photosensitive substrate material; f. selectively exposing the layer of photosensitive substrate material to form a second dielectric layer defining circuit layer interconnections; g. coating the second dielectric layer with a second layer of photosensitive material; h. selectively exposing the second layer of photosensitive material to form a layer defining a second circuit pattern of exposed photosensitive material; i. forming the second conductor pattern with electrically conducting material; and j. repeating steps e through i to form a plurality of electrically
Claim 2
Independent Claim
159 words
A method for fabricating a multilayer printed wiring circuit board comprising: a. forming a dielectric layer on a substrate; b. coating the dielectric layer with a first layer of photosensitive material; c. selectively exposing the first layer of photosensitive material to form a layer defining a first conductor pattern of exposed photosensitive material; d. forming the conductor pattern with a conductor material to form conductors in the conductor pattern; e. coating the circuit bearing layer with a layer of photosensitive substrate material; f. selectively exposing the layer of photosensitive substrate material to form a second dielectric layer defining circuit layer interconnections; g. coating the second dielectric layer with a second layer of photosensitive material; h. selectively exposing the second layer of photosensitive material to form a layer defining a second circuit pattern of exposed photosensitive material; i. forming the second conductor pattern with electrically conducting material; and j. repeating steps e through i to form a plurality of electrically
Claim 3
Dependent Claim
38 words
A method according to claim 1 further comprising forming apertures of a feed through hole pattern in the substrate prior to forming the dielectric layer on the substrate and coating the holes of the hole pattern with a
Claim 4
Dependent Claim
11 words
A method according to claim 1 wherein the coatings of photosensitive
Claim 5
Dependent Claim
11 words
A method according to claim 1 wherein the coatings of photosensitive
Claim 6
Dependent Claim
11 words
A method according to claim 1 further comprising removing the core
Claim 7
Dependent Claim
11 words
A method according to claim 2 comprising forming the multilayer circuits
Claim 8
Dependent Claim
12 words
A method according to claim 1 further comprising forming a ground plane
Claim 9
Dependent Claim
11 words
A method according to claim 1 further comprising forming a metallization
Claim 10
Dependent Claim
11 words
A method according to claim 8 wherein the desired metallization pattern
Claim 11
Dependent Claim
12 words
A method according to claim 1 further comprising forming a solder mask
Claim 12
Dependent Claim
46 words
A method according to claim 10 wherein the soldering mask comprises selectively coating the outer circuit layer with an epoxy to define areas to be soldered, curing the epoxy layer; and coating the epoxy layer with a protective coating to prevent oxidation of the solder areas.