GB512856A - Improvements in metallic screens and processes of making them - Google Patents

Abstract

512,856. Making perforated metal screens by electrodeposition; etching. NORRIS, Inc., E.O. March 22, 1938, Nos. 8774 and 8775. Convention dates, April 22, 1937, and Feb. 19, 1938. [Class 41] [Also in Groups XVI and XXII] A thin finely apertured metal sheet is provided with a reinforcement in the form of a coarse mesh screen by electrodeposition. In one method of manufacture metal is deposited in the form of a fine mesh screen on a matrix with depressions filled with insulating material. Areas of the screen are then covered with insulating ink leaving uncovered lanes on which further metal is deposited to form a reinforcing grid. The reinforced grid is then removed from the matrix. Alternatively the reinforcement may be applied after removal of the fine mesh screen from the matrix. In another method, after deposition of metal to form a fine mesh screen 16, Fig. 6, on a matrix 12 provided with depressions 13 filled with insulating material, a layer of copper 20 is deposited over the whole screen. Areas 21 are then stopped out and nickel is deposited over intersecting lanes 22. The stopping out material is then removed and the copper layer 20 is removed by etching, electrolytically or otherwise, except where protected by the overlying nickel ribs. In another method, the matrix 13, Fig. 9, is provided with intersecting grooves corresponding in position to the desired reinforcement. In the deposition of the grid 16 metal 27 is also deposited in the grooves so as to join up the sections of the grid. A layer 28 of copper is then deposited over the whole and is coated with a resist 30 except above the grooves. Nickel is then deposited in the intervening grooved lanes to form ribs 31 ; the resist is then removed and the copper layer 28 etched away except where protected by the nickel ribs. The screen on removal from the matrix is thus provided with reinforcing ribs on both sides. Suitable baths for etching copper are (1) a solution of potassium cyanide (2) a solution containg 2 1bs suphuric acid, 1 1b chromic acid to 10 gallons of water; these are inert to nickel.