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Multilayer printed circuit board

  • US 3,934,335 A
  • Filed: 10/16/1974
  • Issued: 01/27/1976
  • Est. Priority Date: 10/16/1974
  • Status: Expired due to Term
First Claim
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1. 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

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