Glass-Free Clearance Rings in Printed Circuit Boards
Original Publication Date: 1988-Mar-01
Included in the Prior Art Database: 2005-Feb-14
A method for improving circuit board reliability, drill hole location, panel warping and reducing the drill smear in the manufacture of printed circuit boards is disclosed. The use of woven fiberglass as a reinforcement material in printed circuit boards is a well-known approach. Inherent within the process are problems associated with the glass matrix which become apparent when holes are drilled to make plane-to-plane interconnection. The problem stems from the wicking of plating solutions and the subsequent growth of conductive dendrites along the glass fiber. A second processing problem is the lack of precision of the exit location of a drill hole caused by the drill deflection off the glass bundles located in the drill path.