A through hole is formed by a drill in a defective through hole in a board. An insulating resin is coated on the inner surface of the through hole and a cylindrical conductor is closely fixed with an adhesive to the hole h1 to form a reproduced through hole. Thereafter, as usual, a part lead is inserted...http://www.google.com.au/patents/US5257452?utm_source=gb-gplus-sharePatent US5257452 - Methods of recovering a multi-layer printed circuit board
