Membrane Switches are widely used in many industries because they satisfy multiple requirements in one design. It’s made with durable materials that withstand high temperatures, chemicals, and moisture. Additionally, the design of membrane switches is to be highly responsive and accurate for enhanced user experience.
Membrane switches are a user interface device and critical product design component. But the switch itself is made up of several layers. With its numerous features, you must know what these are as it can help you understand how they work and why they are so helpful.
Construction of a Membrane Switch
Below are the critical components of a membrane switch.
The top layer of a membrane switch is the graphic overlay. It serves as the visual representation of the final product, making it a vital component of any membrane switch. It is usually made from highly flexible materials, such as polyester and polycarbonate.
Overlay or Mounting Adhesive
The overlay or mounting adhesive is typically made of acrylic compounds, which secures the graphic overlay to the top circuit layer of the membrane switch assembly. The adhesive must be durable to ensure that the graphic overlay doesn’t separate from the circuit layer.
Membrane Switch Domes
The components that provide tactile feedback are called membrane switch domes and are available in either plastic or metal. The size of the dome will depend on the size of the membrane switch keys, which can range from 0.24 to 0.79 inches.
Domes are available in different sizes and shapes, which include the following:
The circuit layer is composed of other components, depending on the specific type of membrane switch. It’s also the layer where the conductive path of the switches is established.
These paths are produced using two methods including:
- Screen printing: A silver conductive ink is applied to the stencil on top of the substrate. Screen printing is usually used for flexible and thinner membrane keypads and uses a stencil with the circuit path’s pattern.
- Photochemical etching: A copper-laminated substrate is selectively patterned using chemical etching and photolithography. It’s thicker and more durable, ideal for flexible printed circuits or printed circuit boards.
The circuit tail connects the membrane switch to the machine’s control unit. It has multiple conductive tracks printed on a polyester strip and is flat and flexible. You can find standard connectors at the end of the tail, which match the termination block of the control unit.
The back panel is optional, but it provides additional support to the structure of the membrane switch assembly. It gives rigidity to the device and has a pressure-sensitive adhesive on its underside for mounting purposes.
These are transparent areas where the LCD or LED displays are placed. The design depends on the requirement of the display to ensure readability. For instance, LCDs require clear windows. On the other hand, LED displays need optical filtering to maintain readability in bright lights.
Backlighting & Indicators
Indicators are used to point out activated keys. On the other hand, backlighting is an added feature that can improve the interface’s readability and facade.
Choose from the four main types of backlighting:
- Optical fibers
- Light guide films
- Electroluminescence backlighting
Membrane Switches are The Perfect Choice for a User Interface
The varying components of a membrane switch show that it’s a complex device. But it’s still the perfect choice for any user interface because of its durability, versatility, and cost-effectiveness.