Tag Archives: tactile switches

What are Tactile Switches?

Tactile switches are electromechanical switches that make or break an electrical circuit with the help of manual actuation. In the 1980s, tactile switches were screen-printed or membrane switches that keypads and keyboards used extensively. Later versions offered switches with metal domes for improved feedback, enhanced longevity, and robust actuation. Today, a wide range of commercial and consumer applications use tactile switches extensively.

The presence of the metal dome in tactile switches provides a perceptible click sound, also known as a haptic bump, with the application of pressure. This is an indication that the switch has operated successfully. As tactile switches are momentary action devices, removal of the applied pressure releases the switch immediately, causing the current flow to be cut off.

Although most tactile switches are available as normally open devices, there are normally closed versions also in the market. In the latter model, the application of pressure causes the current flow to turn off and the release of pressure allows the current flow to resume.

Mixing up the names and functions of tactile and pushbutton switches is quite common, as their operation is somewhat similar. However, pushbutton switches have the traditional switch contact mechanism inside, whereas tactile switches use the membrane switch type contacts.

Their construction makes most pushbutton switches operate in momentary action. On the other hand, all tactile switches are momentary, much smaller than pushbutton switches, and generally offer lower voltage and current ratings. Compared to pushbutton switches, the haptic or audible feedback of tactile switches is another key differentiator from pushbutton switches. While it is possible to have pushbutton switches in PCB or panel mounting styles, the design of tactile switches allows only direct PCB mounting.

Comparing the construction of tactile switches with those of other mechanical switches shows a key area of difference, leading to the tactile switches being simple and robust. This difference is in the limited number of internal components that allows a tactile switch to achieve its intended function. In fact, a typical tactile switch has only four parts.

A molded resin base holds the terminals and contacts for connecting the switch to the printed circuit board.

A metallic contact dome with an arched shape fits into the base. It reverses its shape with the application of pressure and returns to its arched shape with the removal of pressure. This flexing process causes the audible sound or haptic click. At the same time, the dome also connects two fixed contacts in the base for the completion of the circuit. On removal of the force, the contact dome springs back to its original shape, thereby disconnecting the contacts. As the material for both the contacts and the dome are metal, they determine the haptic feel and the sound the switch makes.

A plunger directly above the metallic contact dome is the component the user presses to flex the dome and activate the switch. The plunger is either flat or a raised part.

The top cover, above the plunger, protects the switch’s internal mechanism from dust and water ingress. Depending on the intended function, the top cover can be metallic or other material. It also protects the switch from static discharge.

How do you select a Tactile Switch?

We find tactile switches almost everywhere – on keyboards, on mice, beside the monitor, on TV sets, on set-top boxes, on toys and on mobile phones. These tiny switches give a distinctive feeling when pressed. We are so used to using tactile switches; we press them a dozen times a day and never think twice about them – that is, as long as they work. However, tactile switches can also stop working, and engineers must select tactile switches with great care so they last long. After all, most feel that a bad or nonfunctioning switch equals a bad device.

Therefore, to avoid the possibility of a quality black eye, you must essentially select the right switch. Deciding what it is that exactly makes a tactile switch right of the job, may depend on a host of factors, of which two are most important. One is the actuation force and deflection characteristics necessary to meet the requirements of the application. The other is the reliability with which the switch must work during the life of the host electronic gadget.

Thinking of switches as commodity items selected straight off a datasheet, is an expensive mistake that many engineers do make. In reality, picking a durable switch with the right feel does require somewhat more than a mere glance at its specifications. Here is what you should be looking for.

Click ratio

The click ratio of a switch expresses the relationship of its actuation and contact forces. A higher click ratio is indicative of a snappier or crisper switch feel. The deflection or travel distance of a pressed switch also contributes to its overall feel.

A typical datasheet holds the force and travel specifications and these can be a starting point for selecting a switch that feels just right in its intended application. However, the ideal switch depends on the application – an important thing to remember.

For example, users of portable consumer electronic devices prefer crisp tactile switches that have a relatively high click ratio and shorter travel distances. On the other hand, tactile switches for the automotive industry need lower click ratios and longer travel distances. This prevents accidental actuation while driving. Therefore, each electronic application needs to reach a unique balance between the travel distance and the actuation forces.


Consumer electronics and medical applications need tactile switches that are protected against ingress of liquids and other contaminants – IP 67. Usually, these sealed tactile switches reach their maximum lifecycle, because of the sealing.

Manufacturers have traditionally used a bonded silicone membrane to seal the innards of a tactile switch. Now, technologically improved IP67 rated tactile switches use a patented laser welding process that seals the switch with a thin nylon film. This goes over the actuator rather than under it, giving a better seal. The seal not only preserves the crisp feel, but also protects the switch against side loads.


Protecting the switch with the nylon film improves its inherent reliability by not allowing ingress of contaminants. The best switches will typically offer a life expectancy of above one million press-and-release cycles.