Key Size

Of course, you’ll also have to consider the size of your membrane keys. Think about the way in which the membrane keypad will be used and choose keys of the appropriate size for the respective application. If the keypad is being designed for mobile purposes, smaller keys is probably the right choice since it will lower the device’s overall size. But if you are building a membrane keypad to use in conjunction with a large machine, larger keys are recommended.

Spacing

Keys should be spaced far enough on a membrane keypad that it doesn’t cause the operator to accidentally press the wrong keys. With that said, they also should also be close enough together so the operator isn’t forced to bend his or her fingers in unusual directions just to reach them.