Key pad film with spring-back ups and mfg. tool

摘要

A tool for prodn. of a key pad film made of polyester film and having spring cups for circuit contacting comprises a die plate (16) with equal-sized round recesses (19) and a punch plate (17) with corresponding round punches (20) and spherical heads projecting 0.5-1.5 mm from the punch plate (17). Die recess dia. (D2) is 1.1-1.4 times, pref. at least 1 mm, greater than the tool punch dia. (D1). Recess (19) depth is greater than the deforming stroke (h) of the punch (20) into the recess (19). The polyester key board film is claimed and has contact making spherically-shaped, spring-back cups projecting from the film plane. Cups (11) have an electrically conductive coating on the concave side. The spherical central section (28) of the cups (11) is surrounded by a conical ring section (29) projecting from the flat film (4).