Multilayer printed circuit board

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.

Dependencies are inferred from the claim text.