Patent ID: 6037020
Filing Date: 2000-03-14
Classification: H05K

Abstract:
A method for applying a particulate conductive carbon coating to a non-conductive through hole surface of a printed wiring board, comprising the steps of:A. providing a printed wiring board including at least one through hole;B. providing at least one carbon bath containing a dispersion of undissolved particulate conductive carbon for coating said through hole;C. providing at least one conditioning bath containing a dispersion which is useful for conditioning said through hole for the application of a particulate conductive carbon coating from said carbon bath; andD. at least partially immersing said through hole in said conditioning bath and said carbon bath under conditions effective to deposit an electrically conductive carbon coating on said through hole; andE. introducing ultrasonic energy in at least one of said conditioning bath and said carbon bath during said immersing step by placing an ultrasonic generator in said at least one bath, under conditions effective to at least reduce the formation of blowholes during later processing of the printed wiring board.