Magnet in a Plasma Etch System to Improve Uniformity
Original Publication Date: 1986-Oct-01
Included in the Prior Art Database: 2005-Mar-09
Plasma etching is widely used in printed circuit board manufacturing to remove polymer residue (smear) from copper inner pl after drilling through holes. Non-uniformity of plasma etching in this process can be a problem. Etch rates vary depending on location within the hole (particularly in high aspect ratio holes), and for parallel plate reactors field effects cause etch rates to be higher near the edge of a board than at the center.