Electrets

Abstract

A process for preparing polymer electrets comprising the following steps: (a) providing a parylene film having one side affixed to a metal layer and grounding said metal layer; (b) charging the free side of the film with a direct current corona, the charge being of sufficient magnitude to convert the film to an electret; (c) providing p-xylylene monomer vapor in sufficient amount to coat the charged film; and (d) introducing the vapor from step (c) and the electret into a deposition zone, said zone being under vacuum and at a temperature at which the vapor will condense, whereby the electret is conformally coated with parylene.

Dependencies are inferred from the claim text.