The key technique specifications of silicone rubber key-pad include:
Force specifications
Dimensional tolerate and contact resistance

(1) Force specification terminology

Above shows a typical force curve displacement when a knob of a keymat is depressed.

(2) Peak force or Actuation force is the force to cause the web structure to buckle.

(3) Contact force or Make force is the force level when the travel/stroke is completed.

(4) Return force or Rebound force is the amount needed to cause knob to return to original position. Return force is generally 10grams lower than contact force.

(5) Travel or Stroke is the distant the conductive layer make contact with PCB.

(6) Force Specification Recommendation

(7) Tactile and Non- Tactile Knobs

(8) Actuation Force + Tolerances    

(9) Return/Rebound Force

In order to prevent a "stuck" knob situation, Gotada recommend Return/Rebound force from 20 grams to 30 grams and above, depending on actuation force.

(10) Snap Ratio / Tactile Ratio

This ratio is calculated: (Peak force - contact force) / Peak force
Recommended tactile ratio is between 0.4-0.6
For toggle / rocker button, we recommend ratio to be 0.3-0.5

(11) Travel / Stroke

2. Dimensional Tolerance And Contact Resistance

(1) Dimensional Tolerance

Conductive silicone rubber is achieved by mixing carbon black to silicone rubber.
General hardness of conductive silicone rubber is 65 JIS.