Electrographic method of forming conductive circuit patterns and circuit boards formed thereby.

摘要

An electrographic method of forming conductive circuits on a circuit board substrate (2) comprises the formation of an electrostatic charge pattern of the circuit followed by development of the charge pattern with an electrographic toner (5) such as a thermosetting polymeric toner, electroless plating catalyst particles (6) are then adhered to the toner pattern and the substrate is immersed in an electroless plating bath to deposit conductive material (3) on the toner pattern. In one embodiment, the electrostatic charge extends onto the walls of through-holes in the substrate which lie within the area of the charge pattern, thus permitting simultaneous development of the charge on the surface of the substrate and on the walls of the through-holes (4). In another embodiment, conductive patterns are formed on both sides of the substrate (a method known as duplexing). The method provides circuit boards with improved conductive circuits, particularly within through-hole regions of the board.