Patent ID: 7435922

Claim:
A method of forming a keypad, the method comprising: providing: a substrate having a plurality of donut-shaped recesses located at each site of a key button for inputting user information; a plurality of polymer cushions each filled with an incompressible fluid; a flex circuit layer; a plurality of metal membranes; a plurality of plastic adhesive layers; and a thermoplastic elastomer layer; forming a plurality of switch assemblies by: adhering a cushion to each of the plurality of donut-shaped recesses; placing a flex circuit layer above all of the cushions; adhering the plurality of metal membranes to the flex circuit layer; and swaging the plurality of switch assemblies to the substrate; over-molding the thermoplastic elastomer layer over the plurality of switch assemblies to form a keypad; and deflating each of the cushions by removing the incompressible fluid such that a cavity is formed between each of the plurality of metal membranes and the flex circuit layer.