At&t Bell Laboratories

Bell Telephone Laboratories

Frederick R Wight, Jr

David J Lando

Printed circuit boards having a plurality of circuit layers are produced using a specific processing sequence. A copper-clad substrate is first patterned in a desired configuration to produce the first layer of the printed circuit board. The patterned metallization is then covered with a specifically formalated energy sensitive material. The energy sensitive material is delineated in a desired pattern and developed to uncover portions of the underlying metallization pattern. The entire substrate is blanket-cured to produce a rigid layer having openings in appropriate places. The openings are metallized and a second copper pattern is produced on the cured polymer by conventional metallization and lithographic techniques. If desired, the process is repeated until a suitable number of copper patterned levels are obtained.

Circuit board fabrication leading to increased capacity

Materials and methods are shown for increasing the antioxidant protection of polyolefin insulation, such as low density polyethylene insulation on electrical conductors. The materials may be applied in the field to increase the service life of in-place cable. The material is typically applied by brushing or spraying a lacquer-based carrier containing the inventive stabilizer onto the insulation to be protected. The stabilizer migrates into the polyolefin insulation, typically increasing the service life of antioxidant depleted cable by several years.

Growing community of inventors

West Millington, NJ, United States of America

Frederick R Wight, Jr