Abstract: A push button switch and methods for manufacturing the same result in increased manufacturing efficiency and increased design freedom. The push button switch includes a key top, a dome section and a leg section which are integrally formed from a silicone rubber material. The key top includes a colored section formed by penetrating the coloring dye of a dye impregnated ink below the upper surface of the key top. The push button switches are formed into a rubber cover configuration by charging a mold for forming a plurality of the push button switches with a silicone rubber material. The dye impregnated ink is then applied onto the surface of each of the key tops by either a wet printing process or a sublimation transfer technique, and is subjected to a heat treatment which causes the dye to penetrate into each of the key tops.

Abstract: A key-board switching unit for electronic instruments is constructed with a printed circuit board provided with a plural number of pairs of fixed contact points on the surface and an insulating covering sheet member mounted on or above the printed circuit board and provided on the bottom surface with movable contact points to face the fixed contact points.