Membrane switches are a type of HMI (human machine interface) that can be used to control electrical devices. Without knowing it, you are likely encountering these multiple times a day. Ever use a microwave? Fill your car with gas? Have you found yourself in a hospital bed and needed to adjust its position? All of these scenarios utilize membrane switches to create the buttons of the machine. They are very reliable, durable, and can be custom designed to meet any requirements. Membrane switches are widely used in a variety of industries, including medical, automotive, military, industrial, and consumer goods.
Membrane switches are a cost-effective and efficient way to create user interface technology. They are easy to use and can be applied to a wide range of applications, from simple switches to complex systems. With the right design, membrane switches can provide the user with a comfortable and intuitive experience.
What are Membrane Switches?
Membrane switches are composed of two or more layers of flexible materials, such as polyester or polycarbonate, that are adhered together to form a switch. The layers are usually separated by a spacer material and are electronically printed with conductive inks. These conductive layers are typically made of metal or carbon, and the non-conductive layers are usually made of plastic.
When a human presses down on the switch (the button), the two layers make contact, creating a circuit that sends a signal to the device being controlled. The signals can be used to control the device or to trigger other actions, such as activating a motor or an alarm.
Design Considerations for Membrane Switches
Designing a membrane switch requires careful consideration of several factors. The design must be tailored to the application and the environment in which the switch will be used. There are certain products that may be more susceptible to environmental elements. It is important to consider the temperature, humidity, and other environmental conditions that may affect the switch’s performance. Others may require LEDs or backlit areas for optimal user functionality. It is important to consider the size, shape, and materials used for the switch, as well as the signals that will be sent when the switch is pressed.
When designing a membrane switch, the user interface should be a priority. The top layer is a printed graphic overlay that tells the user where to push to achieve a certain result. The switch should be easily identifiable and, in many cases, such as medical devices, it should have a tactile feel, like a dome, that allows the user to easily and quickly locate and press the switch.
Benefits of Membrane Switches
Membrane switches are a cost-effective and efficient way to create user interface technology, and they can be designed to meet any specific requirements. For example, because they utilize printed electronics, the profile of these sub-assemblies is thin, requiring less space in the overall integrated product.
Membrane switches are also a great solution for businesses that need to control multiple devices. They can send many signals at once, which makes them ideal for controlling several devices at the same time.
Parts of a Membrane Switch
Think of membrane switches like a sandwich. They have several components that work together to make the switch function properly. The number of layers can vary greatly depending on the application, but, if we are sticking with the sandwich analogy, the bread and butter of a membrane switch are the overlay, adhesive, spacer, and circuitry.
The overlay is what we see as the end user. This graphic tells the person using the product where to push to cause an action. Although the image looks to be printed on top, it is actually printed on the underside of this layer to prevent it from scratching or peeling off. This layer can be made of polycarbonate, polyester, or acrylic, depending on durability requirements.
The adhesive layer is just glue, right? Well, it’s actually much more vital than that. Because its sole purpose is to ensure the graphic overlay and the circuitry stay attached, engineers must put great through into selecting the right adhesive to prevent these layers from pulling or breaking away from the rest of the product.
The spacer layer is the layer that separates the contact layer from the circuitry. This layer is usually made of plastic or rubber and is designed to provide a cushion between the two layers.
Next, we see the brains of the operation: the printed circuitry. This is its primary power source. Essentially, two layers of circuits are printed with conductive inks. When the top layer is pressed, it makes contact with the lower circuit, sending a signal to the machine to perform an action.
Finally, another layer of adhesive is added to secure the completed switch in place. Remember this is just the basic package. A number of layers can be added into the design to include LEDS, backlighting, and more.
Membrane switches are a powerful and efficient way to create human interface technology. Not only are they incredibly easy to use, but they are also affordable and have near limitless possibilities which make them highly adaptable to any number of product specifications.
With the right design and manufacturing expertise, membrane switches can provide you with an intuitive and comfortable user experience.