Method for coating thru holes in a printed circuit substrate
AssigneeWestern Electric Company, Inc.
InventorsGeorge J. Plichta, Thomas E. Unger
Life of this patent
Estimating the term…
Abstract
The walls 41 (FIG. 4) of thru holes 11 in a printed wiring board substrate 12 are coated with a liquid 24 by inserting fingers 22 into the thru holes. Each of the fingers has a diameter slightly less than the diameter of the associated thru hole and has a length no greater than the thickness of the substrate 12. After ink 24 has been applied to the top surface of the substrate, the inserted fingers 22 are withdrawn, thereby drawing the ink down into the thru holes and coating the walls 41. In another embodiment, fingers 62 are aligned with selected portions 52 of an edge 55 of the substrate 50 to coat the portions of the edge as the fingers are moved by the edge after the heads of the fingers have been coated with the ink 24.
Claims10
A method of coating the walls of a thru hole formed in a substrate with a liquid, which comprises:
- (a) inserting a close-fitting, undersized pin into the hole so that a front end of the pin is positioned adjacent to a first surface of the substrate;
- next
- (b) applying the liquid to portions of the first surface inluding the area about the hole and the front end of the pin;
- and then
- (c) withdrawing the pin from the hole so that the liquid is drawn by the pin into the hole and coats the walls of the hole with a film of the liquid.
A method of applying ink to selected portions of a printed circuit substrate, including the uniform coating of a plurality of thru holes formed in the substrate and coating selected portions of the edges of the substrate, which method comprises the steps of:
- moving an applicator member, having a plate and a plurality of fingers mounted on the plate, some of the fingers being located on the plate so that the fingers are aligned with the plurality of thru holes in the substrate and others of the fingers are aligned with the selected portions of the edges of the substrate, against a bottom surface of the substrate such that some of the fingers are inserted into the thru holes and the others of the fingers are placed adjacent to the selected portions of the edges of the substrate;
- applying ink to a top surface of the substrate including the tops of the plurality of fingers;
- and
- retracting the applicator member from the substrate so that the inserted fingers draw the liquid into the holes coating the walls of the plurality of holes with a liquid as the fingers are retracted and the other fingers coat the selected portions of the edge of the board as the inked tops of the fingers are retracted.
Dependencies are inferred from the claim text.