Drill Smear Inhibitor
Original Publication Date: 1985-Sep-01
Included in the Prior Art Database: 2005-Feb-19
In the drilling of printed circuit cards, or the like, comprising layers of copper, or other such conductive material, laminated together with epoxy resin, or other such insulative material, the drill causes smearing of epoxy over the copper when the drill bores through the innerplanes. The epoxy smear must be removed to prevent subsequent plating problems when forming plated through holes that connect the innerplanes. Because epoxy smearing is aggravated by the dulling of the drills, drill life is extended, and its related epoxy smear problem is diminished with the application of a titania-loaded epoxy coating in the following manner. Prior to drilling, a two to ten-mil-thick bulk film of a titania- loaded epoxy coating is screened on one or both outside surfaces (that is, the top and/or bottom) of the printed circuit product.