CSI Membrane Switch Solutions

Membrane Switches

Membrane Switch

What is a Membrane Switch?

A membrane switch or flat panel switch consists of a printed polyester or polycarbonate overlay adhered to a printed circuit using pressure to open and close a circuit. The switch is an interface between user and machine, enabling an operator to communicate with equipment, instrumentation, or machinery. The membrane switch circuitry is most often screen printed using conductive inks which are typically made of silver or carbon. Membrane switches are part of a range of devices considered to be user interfaces or human machine interfaces (HMIs).

CSI Keyboards is a global leading custom membrane switch manufacturer and custom keypad manufacturer. With our unlimited design and manufacturing capabilities, CSI Keyboards is able to provide our customers with custom tactile membrane keypads and custom keypads that meet their needs as a user interface and face plate to their product. We engineer and manufacture custom membrane switch and membrane keypad technologies that meets specific customer requirements in both performance and visual aesthetics.

Custom Membrane Switch Solutions & Features

Additional Membrane Keypad Solutions & Features

  • Integrated transparent or smoked windows, deadfront membrane switches
  • Flat switch or non-tactile membrane switches
  • Integrated displays and touch screens
  • Epoxy and UV coated keys
  • Rigid support backers including integrated metal or G10 backers
Membrane Switch Layers

Membrane Switch Backlighting

CSI Keyboards has set itself apart from the competition by its unparalleled excellence in custom membrane keypad backlighting. By utilizing LEDs, electroluminescence, light guide film, fiber optics and other backlighting technologies, CSI Keyboards, Inc. has designed and manufactured keypad backlighting solutions for the top tier medical, military, as well as many different civilian industries. From the simplest single colored LED indicator and LED membrane switch with backlit keys, to the most complicated multicolored membrane keypad switch assembly, CSI Keyboards will work with you to bring your specific custom backlit keypad switch design to life. CSI Keyboards uses many different technologies to backlight your product including but not limited to:

Membrane switches with LEDs are still the most popular and economical method for keyboard backlighting. LEDs are most commonly used to backlight keys, icons and symbols. LEDs are also typically used as indicator lights. A combination of LEDs, Light Guide Film and proprietary CSI backlighting methods can be designed to backlight the entire surface of a user interface.

Light Guide Film (LGF)
Designed to evenly distribute light from top or side firing LEDs, providing bright, uniformed illumination. It also reduces the amount of LEDs needed, saving power consumption. The design and utilization of light guide film (LGF) technology has become one of the most common methods of interface backlighting. CSI Keyboards uses proprietary techniques to design the light guide film so it is optimized for light redirection and reflection giving the customer the brightest possible backlighting solution. Light guide film dots are also designed and implemented which allow for the optimization of light distribution to obtain maximum brightness and uniformity. Common problems that many of our competitors face are light leakage and hot spots. CSI’s backlighting designs prevent any light leakage and hot spots from occurring, and also result in much brighter light guide film and interface.

Electroluminescence (EL)
Applied on a very thin layer between the graphic overlay and the circuit. EL uses a printable ink deposit to illuminate the switch and provide a uniformed illumination.

Fiber Optics
Provides a flexible backlighting layer that can be incorporated between the graphic overlay and the circuit layer allowing the entire surface area of the membrane switch to be evenly backlit.

Treadmil HMI example

Membrane Switch Sealing

Many of our customers require custom keypads that must survive harsh conditions in the toughest of environments. And by utilizing some of our proprietary technologies and designs, our keypads can be built to last two million cycles and beyond. CSI Keyboards utilizes copper flex circuity and proprietary designs such as the Seal Frame and Life Extending Cushion to ensure your keypad is able to withstand and perform in extreme environments.

  • Copper Flex Membrane Switches, also known as polyimide Kapton circuitry, are used in the majority of CSI Keyboards’ keypad designs due to its excellent dielectric strength, thermal stability, chemical resistance and flexibility. Copper Flex membrane switch panels are produced using polyimide (Kapton) as the base material. Copper flex switches are manufactured by laminating a thin sheet of copper to a flexible film substrate. The copper is then chemically etched away, leaving the copper traces. An additional layer of polyimide is laminated to the circuit leaving the gold contacts exposed. Copper flex has become the superior choice over printed silver especially for outdoor applications. Copper flex circuitry construction designs offer a significant advantage over printed silver and a printed silver circuit can be replaced with a copper and polyimide construction with minimal additional cost.
  • Seal Frame is a perimeter frame of adhesive that protects your circuitry from any moisture ingress. It have proven to be as robust as other sealing methods such as perimeter temperature sealing and can be included in your design at minimal additional cost.
  • Environmentally Resistant Adhesives
    CSI Keyboards utilizes the top of the line adhesives in our membrane switches specially formulated to provide high bond strength to surfaces. Our adhesives are resistant to humidity, UV, water, temperature, and chemicals.
CSI Keyboards Membrane Switch


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