Membrane switch keyboard Advanced Input Systems

A membrane switch generally consists of two polyester films that are screen printed with conductive ink to form the circuit layers of the switch. A spacer, which is die cut at contact points, is then sandwiched between two circuits. The die-cut holes permit a touch of the finger to close the contact, which in turn completes the circuit. Upon release, the circuit is broken.

A graphic overlay is added to the membrane switch to allow the input device user to identify specific switch contacts.

The panel back is laminated with an adhesive for mounting to a backer or enclosure and is terminated with a means for interfacing with the customer’s electronics.

Tactile feedback in a membrane switch is actually an enhancement, which provides the user feedback when they press the key location. Typically, the switch consists of a top and bottom layer of polyester with a tactile actuator that when pressed, momentarily completes the circuit while providing the user a degree of response based on the switches construction.

Non-tactile membrane switches rely on a sensory response other then tactile touch, such as an audio or visual stimuli that alerts the user to switch closure.

Non-tactile switches perform well in abusive environments and are more conducive in applications where large, hidden or irregular shaped keys are a requirement.

Printed circuit board switches are utilized in situations where there are trace routing limitations with traditional membrane switches or the OEM customer would like to utilize the PCB as a ridged backer that can also be populated with active and passive components, reducing the amount of materials and interconnects.

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