Browse Prior Art Database

Plating Through Holes

IP.com Disclosure Number: IPCOM000090553D
Original Publication Date: 1969-May-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 49K

Publishing Venue

IBM

Related People

Gagnon, B: AUTHOR [+2]

Abstract

Forming conductive through-holes in printed circuit boards after the boards are personalized with conductive patterns is difficult. To accomplish through-hole plating, it is essential that cathodic contact be established at each hole location. After circuit patterns are produced on the board surfaces, the usual techniques do not usually permit such contact at each hole location. This technique uses a steel wool cathode to provide a solution to the problem.

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Plating Through Holes

Forming conductive through-holes in printed circuit boards after the boards are personalized with conductive patterns is difficult. To accomplish through-hole plating, it is essential that cathodic contact be established at each hole location. After circuit patterns are produced on the board surfaces, the usual techniques do not usually permit such contact at each hole location. This technique uses a steel wool cathode to provide a solution to the problem.

Shown at A is board 1 having conductive circuit patterns 2 and 3 to be electrically connected via through-hole 4. Prior to drilling hole 4 at the desired location, resist layer 5 is applied to all exposed surfaces of board 1 to protect the previously applied circuit pattern. Board 1 is next processed through an electroless copper bath to obtain thin Cu coating 6 on the walls of hole 4 as in B. Coating 6 makes contact between the patterns 2 and 3. A light buffing removes the electroless Cu on the surfaces of 1 surrounding hole 4.

An electroplating operation can be then carried out to deposit a sufficient copper coating 9 through hole 4 over layer 6 to provide the current carrying contact required. Cathodic contact with layer 6 is achieved for electroplating by pressing steel wool cathode 7 against one surface of board 1 at the hole 4 location. The steel wool fibers enter hole 4, as in C, to provide the cathodic contact while still permitting a free flow of plating solution through hole 4. A...