Short-stroke switches

Short stroke switches give the user real tactile feedback with a very low stroke height. In contrast to long-stroke switches, the key travel of short-travel variants is between 0.3 and 1 mm. The technological diversity in the 0.7 mm range is greater than one would expect at first glance. Short-stroke switches include all types of snap domes, but also so-called microswitches, which are available in a wide variety of versions.

 

Metal domes are an inexpensive and reliable way of generating tactile key feedback with a very low stroke height. The product range on offer includes domes in sizes from 4 mm and up to over 50 mm with compressive forces of 40 to 680 g. Special shapes, whether round, square or elongated, are available for different applications and some variants achieve a service life of several million actuations. Many special variants allow the integration of orientation or functional lighting through a central hole, and special domes with new specifications are constantly being developed on request.

The operation of a metal dome is relatively simple: a kind of arch is bent upwards into the metal plate. This initially does not react when pressure is exerted, but when the force is increased a little, the curvature suddenly gives way and snaps down, so that the typical crackling sound can be heard. By pressing down on the metal dome, it touches the circuit board on which it is mounted and thereby closes a contact that is directly below it on the circuit board. As soon as the pressure that is exerted on the metal dome drops below the pressure point, the metal dome snaps back into its original state and the contact breaks off.

Metal domes are mostly used in membrane keypads due to their compactness and low price. However, they are also used as contact makers under silicone keypads to give the otherwise rather spongy silicone keypads a clearer switching feel. In both cases, the keypads in which the metal domes are used are usually dustproof and waterproof and are available with or without function LEDs on request.

Metal domes are very easy to apply to a printed circuit board or layer of film and are also suitable for small keypads and individual buttons due to their compactness. As they are largely impact and temperature resistant, films with metal domes are very often used as small keypads in machines and other technical devices.

In most cases, microswitches consist of a lever and a spring that returns the lever to its original position after actuation. Very little force is required to actuate a microswitch. Furthermore, microswitches are characterized by a very small distance between the contacts. This is very often less than one millimeter, but there are also variants with a stroke of up to 3 mm. The materials used to manufacture the switch can withstand thermal stress and mechanical actuation for a long time, so that a long service life of several million switching cycles is generally achieved.

The areas of application for microswitches are very diverse and range from consumer electronics to industrial applications. They are often used as control switches or for one-finger operation. The use of microswitches gives the buttons a pleasant and fatigue-free feel.

Metal domes are very easy to apply to a printed circuit board or layer of film and are also suitable for small keypads and individual buttons due to their compactness. As they are largely impact and temperature resistant, films with metal domes are very often used as small keypads in machines and other technical devices.