Process for the Photofabrication of Printed Circuit Boards
Original Publication Date: 1988-Apr-01
Included in the Prior Art Database: 2005-Feb-15
Printed circuit boards (PCBs) are commonly fabricated from thermally- cured glass cloth saturated with an epoxy resin formulation. After additional steps to define copper circuitry, the external surfaces are then coated with a film photopolymer which acts as a solder mask. Depending upon product, a protective coat is sometimes added. The introduction of a photolytically cured polymer as a permanent resist adds yet another layer to the product. In addition to the complications resulting from the number of different resin formulations used in this construction method, there are environmental and safety disadvantages. A cationic photoinitiator technique which fabricates PCBs from one master polymer system simplifies the construction process and eliminates several of the disadvantages.