Abstract: A plasma ashing system includes a plasma generator configured to generate a plasma from a gas source. The system further includes a plasma reaction chamber configured to house a substrate comprising a Parylene coating, wherein the plasma reaction chamber is configured to expose surfaces of the Parylene coating on the substrate to the plasma, wherein the plasma is configured to remove portions of the Parylene coating on the substrate. The system further includes a masking fixture including at least one opening and configured to shield areas of the substrate from plasma ashing, and further including a gasket between the masking fixture and the substrate.