A force displacement curve is a good way to visually look at the mechanical function of a switch. The curve primarily shows two things – (1) the amount of force needed to actuate a switch from its open position to closed position, and (2) the amount of travel the switch undergoes from the open position to the closed position. Force displacement curves can also show characteristics such as tactile ratio, return force, and the “tease” of a switch.
Since tactile domes are momentary switches, the top of the curve shows the force needed for the “transition ring” to snap – causing the center of the dome to make contact with the PCB. Snaptron offers a force displacement test machine, the TruTac, to help analyze a switches’ characteristics. Find more information on our website.