Membrane Keypad

A membrane keypad incorporates many layers in its construction.

The various layers are:

1)      Overlay

The top-most layer is the membrane made up of polycarbonate (in our case) , it is the interface user interacts with, it is the visual layer, with keys and design.

2)      Shielding (Optional): Usually preferred for protection of the keypad from electromagnetic interference (EMI) or electrostatic discharge (ESD)—typically in environments with sensitive electronics or high electrical noise.

3)      Top circuit layer or dome

The top circuit layer uses conductive ink to create a circuit or instead of a circuit layer, dome switches are placed.

4)      Spacer

It is like a separating layer between 2 conducting layers. The thickness of a spacer ranges from 0.1mm to 0.10mm and can be increased based on requirements. It keeps the circuits apart to avoid any accidental contact and ensures that feedback is registered only when keys are pressed.

5)      Bottom circuit layer

It is a printed circuit layer. When keys are pressed, top circuit layer touches bottom circuit layer and circuit completes.

6)      Adhesive

This is the layer of adhesive to stick the membrane keypad to the machine.

7)      Backplate (Optional)

It is rigid base made up of metal or plastic, used to mount the membrane keypad assembly. Using a backplate, makes a keypad fixed and prevents it from flexing or bending. It can be incorporated based on requirements.