Membrane Touch switches: Thick-Film Materials Systems and Processing Options

Thick-film materials and processing parameters critical to the production of membrane touch switches are reviewed. The primary emphasis is on polymer-bonded silver conductor systems; electrical conductivity versus silver content, conduction mechanisms, techniques to determine adhesion, materials for screen printing, choice of Mylarr polyester film, and appropriate drying conditions are discussed. Also described is the performance of a new series of polymeric resistors on various substrates (including Mylarr polyester), under different curing and storage conditions. Future trends in the development of materials systems for membrane switches and associated circuitry are also briefly reviewed.