How do membrane switches work?
When most people look at their electronic devices, they don’t often think about what makes them work. Electrical switches are a major electrical component with the primary purpose of controlling the on and off mechanism. When you turn something on, the circuit is powered up. When you turn it off, the circuit is closed, cutting off power. While electrical switches are incredibly common, membrane switches have become the new alternative for many manufacturers. Not only are they useful, but they provide many unique advantages.
But what exactly are membrane switches, and how do they work?
Below you can find our detailed breakdown of how a membrane switch works and the purposes it serves.
What is a membrane switch?
Firstly, what are membrane switches? This is a common question. Membrane switches are thin electronic circuits that allow users to interface with a device by applying pressure. Pushing on a membrane switch can open and close the circuit. They essentially allow humans to interact with electronic devices and machines.
For example, a microwave has a panel with numbers, a start button, and other additions. When you operate a device like this, you’re interacting with a membrane switch.
The origin of membrane switches
Over 30 years ago, membrane switches were considered an unreliable method of inputting data. After decades of improvements, membrane switches have become an established and effective method in numerous technical applications.
The first real membrane switches came to the market in the early 1980s and were made of polycarbonate. They were brittle, which led to cracking around the keys. The next iteration solved the durability and quality issues by switching the polycarbonate plastic film to polyester and adding metal domes. Although this improved their functionality, they remained an unpopular application since mechanical keyboards dominated the market during the era.
It wasn’t until the 90s that thinner keyboard keys and membrane switches became a more popular choice for compact devices. This was at a time when smaller electronics began to flourish, and the need for smaller electronic components increased. Hence, the demand for membrane switches.
Today, membrane switches are widely relied on for industrial, medical, and consumer markets/applications.
How do membrane switches work?
So, how do membrane switches work? The top layer of the switch is an overlay with keys, which is what the user sees and touches. Underneath the layer are two circuits printed in conductive ink, such as copper, graphite, or silver. This helps with circuit correspondence when engaging with the buttons. A spacer adhesive is used to prevent continuous contact between the circuits to ensure they remain open until pressure is applied.
When a user presses a button, it completes a printed circuit specific to that key, and because that circuit was activated, the unit knows which button was engaged. Once the processing unit identifies the pressed button, it generates a corresponding output signal.
The benefits of membrane switches
Thin & compact
The thin and compact profile of a membrane switch aids in its appeal. Each layer has a thickness between 0.9mm and 1.3 mm. They typically have three to six layers depending on the design. Even with the addition of conductive inks, metallic domes, and EMF screens, the thickness of the membrane switch is only a fraction of an inch. Their size makes them suitable for household appliances and controllers.
Resistance against elements
One of the more popular advantages of membrane switches is their ability to shield against external elements. Their sealed construction is achieved by implementing pressure-sensitive adhesive or heat seals. Plastics like polyesters and polycarbonates provide a barrier against moisture without reducing the visibility of the screen or panel. There are no holes for liquids or gases to enter and accumulate, resulting in an efficient interface with quality protection.
Easy cleaning & maintenance
Membrane switches are also easy to clean. All you need is as little as a lint-free cloth to dust it off. Most mechanical switches fall victim to dirt and debris buildup that gets trapped under the buttons. You don’t have to disassemble the switch to clean out the buttons or keys.
Tactile feedback
Many membrane switches can provide tactile feedback. What is it? Well, tactile feedback is the physical sensation created by an electrical switch that responds when used. For example, snap-style domes are used in membrane switches that flatten when pressed and snap back when released, creating what’s known as tactile feedback.
Backlighting
Backlighting is often implemented to illuminate buttons or keys that improve the functionality of a membrane switch. Electroluminescence is a common type of backlighting used for membrane switches. While using only coloured phosphor compounds, EL bulbs can illuminate the front of a switch. The second most common choice is a light-emitting diode (LED). LED lights last longer and are considered more energy efficient.
As you have learned, membrane switches are a common element in technological devices. They provide endless advantages and continue to improve numerous designs and applications. We hope now that we’ve highlighted the important aspects of this switch alternative, you can understand its place in the technological age.