Development of a membrane switch-type full-travel tactile keyboard

This paper describes the approaches to design and the rationale that successfully satisfied the requirements for a full-travel keyboard with usage exceeding 10 million actuations per character, satisfactory N-key roll-over, and phantom key control. Emphasis was placed on technical understanding of the effects of all material and design decisions. Interactions among design, material, and processing variables were revealed through statistical parameter modeling and environmental exposure studies. This knowledge facilitated the control of critical parameters to permit an order-of-magnitude reduction of actuation forces and tolerances. Product reliability was achieved through evaluation, environmental protection features, and stringent process controls. This paper highlights the design, materials, and processing aspects of the membrane switch developed for low-force keyboard applications. It also discusses effects of environmental factors on the individual components and overall system function.