Silicone rubber material is providing Shin-Etsu keypads a unique Force-travel characteristic and click response feeling. The typical characteristic is expressed in definitions of forces and travel specifications.
F1 = Actuation force or peak force provided by the dome shape and silicone material
F2 = Make force or contact force provided by the dome shape and silicone material
F3 = force at the mechanical end stop given by the application
S1 = Peak travel provided by the dome shape
S2 = Stroke or contact travel depending on the mechanical shape and the position of the contact element
Click ratio (%) = (F1 – F2)/F1 x 100%.