Over the years, we’ve written a number of posts regarding the benefits of using molded silicone in keypad assemblies. One question that frequently gets asked by many of our customers is what type of webbing should be utilized and integrated into the rubber keypad design.
There are a number of factors that should be taken into consideration when answering this question and they really are dependent on the end product’s functionality requirements. For instance, does the particular product call for a keypad with buttons that are relatively difficult to actuate to avoid accidental activation of keys? Does the product require a keypad that has buttons that are easy to activate? Does the product call for buttons that make an audible tactile snap when pressed? Regardless of the requirement, we have a number of methods to customize your elastomer keypad to work and feel a number of different ways. The main design feature that is utilized is the webbing or flex wall.
An elastomer button with an active web design has a small web or flex wall at the base of the button that flexes when the button is pressed. The resistance of this flex wall gives a tactile response as the button is pressed. The tactile response lets the user of the switch know that the key as been actuated. This particular design requires a carbon or metallic pill or puck which is molded into the underside of the rubber button. This pill completes the circuit when the button is pressed by making connection with the contact designed into the board or circuit. More on carbon pill technology can be found here.
In contrast, a dead web rubber keypad design has buttons that do not include any web at the base of the keys or very minimal webs. By not using a web or flex wall, there must be some method of providing tactile feedback to the user. In this design, we typically use a metal dome which is placed under the rubber key. The metal dome makes contact with the board or circuit and provides the tactile audible feedback when pressed. There are a multitude of metal dome options that can be integrated into the keypad with different sizes and actuation forces really allowing the customer to get the exact feel they desire. More on metal dome technology and options can be found here.