Compact, cost-effective and endlessly customizable!
No wonder the membrane keypad can be found in almost all areas of application, whether in private households or in industrial applications. Various functions can be easily supplemented with a wide range of additional components: Intensive lighting, complex electronics, modern touch screen, stable carrier plate or noble cast-on key tops(GT technology).
More information about membrane keypads in the Induux Wiki.
The classic membrane keypad with contact spring (also called switching contact or clicker) ensures reliable, low-bounce switching behavior, regardless of the type of key actuation. The shape of the contact spring guarantees reliable contact with clear feedback. Different pressure points from 2N to 10N can be used, completely adapted to your application.
The pressure point may vary depending on the technical design of the membrane keypad.
If tactile feedback is not important in the user area, a membrane keypad can also be used without contact springs. We are then talking about a so-called silver-silver switch. Two layers of foil printed with conductive silver trigger the function when the button is pressed.
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Components and options
Assembly of a membrane keypad
A membrane keypad consists of a wide variety of layers and additional components that can be designed variably. The standard assembly of our flexible membrane keypad always consists of 6 individual layers:
- Decorative film / graphic overlay
- Dome retainer
- Circuit layer
The decorative film is made of a durable polyester film with the custom design printed on the reverse side. The film can be enhanced with our GT technology or various embossing forms. The GT domes and embossing provide the user easy finger guidance. For outdoor use or applications in medical technology, special polyester films with UV protection or antimicrobial properties can be used.
A wide variety of adhesives in variable thicknesses and adhesive properties can be selected depending on the area of application of the membrane keypad.
The dome retainer permanently holds the contact springs or metal domes in place on the circuit layer. The underlying spacer optimally compensates for the height of the contact springs.
The circuit layer is the actual heart of the membrane keypad. The entire electrical function is located on this layer: the printed conductive tracks according to an individual circuit diagram, the assembled contact springs and LEDs.
The circuit layer can also be replaced by a printed circuit board if desired.
Carrier plates or housings give the membrane keypad more stability and can be easily added on request.
Membrane keypads with metal effect: light, durable, elegant!
Go for more unique design with the control unit of your application. A membrane keypad is lightweight, reliable, durable and can be transformed into a high-end control unit with the right design.
The textured and reflective surface resembles brushed metal and blends perfectly with other metal surfaces.
A clear and slim design for your control panel.
Some input systems control extensive functions and are therefore equipped with many keys, symbols and LEDs.
The so-called “dead front” design ensures a clear user interface without having to sacrifice functions. A special printing process can be used to hide non-illuminated areas on the design overlay and display only actively illuminated areas.
Illuminated membrane keypads
For the backlighting of our membrane keypads we use so-called SideLEDs (LEDs that shine in from the side). LED technology combined with a sophisticated keypad design, allows us to illuminate large areas and individual keys in a variety of colors. This technology stands out above all with enormous brightness and long service life.
With our backlighting technology we reduce the installation depth for the customer to a minimum. With a keypad assembly of 2.2 mm, the LED technology requires only slightly more space than an EL film. An optional light partition between the individual keys even allows each key to be illuminated separately. The use of bi-color or RGB LEDs also allows a virtually unlimited color selection. Since the assembly must be placed on a printed circuit board, its unused reversed side can be used for the assembly of series resistors and ICs or even the entire customer-specific circuit electronics.
Additional design elements on the overlay such as embossing or dispensed key domes (GT technology) is of course still possible. Capacitive keys are also illuminated with our SideLED technology.
SMD LEDs are used to integrate status LEDs in membrane keypads. These LEDs can be mounted on film as well as on printed circuit boards. For integration on a film, the LEDs are glued and held in place on the circuit layer. With an overall height of 0.35 mm, the LEDs can be easily integrated into the film assembly. Choose from an extensive color palette between mono, bi-color and RGB LEDs.
Only for areas of application with frequent vibrations, e.g. in vehicles, we advise against glued LEDs on film. Depending on the strength of the shock, the adhesive may come off and the LED may lose its grip. In this case we recommend mounting the LEDs on a printed circuit board.
Membrane keypads with printed circuit board
A printed circuit board serves as a carrier for the membrane keypad and replaces the flexible circuit layer normally used. It is made of epoxy FR4 material and can be used as single/ double sided or multilayer PCB. The PCB gives the keypad assembly more stability and the possibility to add more electronic components, both front and reverse.
We develop customized solutions with integrated microcontrollers and direct connection to the desired interface.
We specialize in the following interfaces:
- RS232, RS485
- CAN bus
- Profibus, Profinet (Gateway)
- I2C, SPI
- USB (generic HID)
- GSM (data connection via mobile radio)
- Analog digital interface (PWM, 0-10V, 4-20mA,…)
Carrier plates and housings made of metal or plastic
Membrane keypads can be mounted on or recessed into carrier plates and housings. Preferably, the carriers are made of aluminum, stainless steel or plastic.
Front panels can be effortlessly integrated into the front of the device or machine by attaching press-in studs or drilled holes. Customized housings protect the sensitive electronics and round off the input system.
The surface of the carrier plate or housing can also be adapted to your application: bare, anodized, chromated or brushed. A milled groove for gaskets ensures that your device is optimally protected from dirt or liquids.
You can also find out more about carrier plates and enclosures from TES Frontdesign, a member of our HK technology network, or from our partner OKW Gehäusesysteme.
Membrane keypads with touchscreen
The tactile feedback of a membrane keypad can be combined with a touch-sensitive touchscreen. Both resistive and capacitive touchscreens can be integrated into the keypad design. The touchscreen is connected to the membrane keypad assembly via an adhesive frame or full-surface OCA bonding.
Membrane keypads with slide-in strips
If the same membrane keypad is used in different countries, the labeling can be solved using slide-in strips in different languages. So-called slide-in pockets are integrated into the keypad structure for this purpose. Via these pockets, the corresponding strips can be easily exchanged.
Membrane keypads with double contact
High safety requirements for control systems demand maximum reliability of the operating unit. For example, a slow or fast running function in a crane control requires two clearly distinguishable switching functions. Hoffmann + Krippner ensures this function the so-called double contact. While the first switching level is activated at a pressure of approx. 7 N, the second level switches only at approx. 13 N. This means that two different actuating forces can be realized in one key.
Molded-on key tips on the membrane surface above the keys (GT technology) reinforce the tactile feedback of both switching levels.
Membrane keyboards with key tops
We give flat membrane keyboards raised key tops. This allows you to feel where the keys are located even in blind operation. For this purpose, we apply a high-gloss plastic compound in the shape of a dome to the surface of the film, precisely above the keys. Our
(GT= casting technology) gives the pre-printed design an additional noble glossy look.
Advantages of our GT technology:
- Extremely high mechanical resistance
- Pressure marks from hard objects “heal” without residue
- creative design possibilities, e.g. via company logos, displays, LEDs
- user-friendly haptics with optimal finger guidance
- good tactile feedback
Membrane keypads with embossing
For optimum finger guidance, foil surfaces up to 0.4 mm high can be embossed in addition to GT technology. In the case of foil keyboards with embossing, the decorative foil is formed into the desired shape using appropriate tools, a vacuum and temperature.
You can choose from the following embossing shapes:
- Surface embossing
- Frame embossing
Integrated EMC shielding prevents radiation generated in the device from penetrating to the outside and influencing surrounding devices and interfering with their function. The penetration of external interference radiation into the interior of the device is also prevented by the EMC shielding.
To make our input systems electromagnetically compatible, an electrically conductive layer is integrated into the structure of the membrane keypad. For this purpose, a polyester film is printed with silver polymer and insulation over its entire surface, and one or more contact areas are printed with graphite. The EMC shielding is contacted via a separate connecting strap, e.g. to the ground connection of the device.
For integrated displays, the radiation that occurs must be collected by transparent conductive layers. Thin metal grids cast into Plexiglas or conductive vaporized foils or filter discs are suitable for this purpose.
Improved technology for less EMC radiation!
For some years now, electronics has developed to the point where:
- almost no more radiation is emitted due to improved components and design rules in the configuration and PCB layout
- Newer displays do not produce significant radiation
- Control electronics of capacitive touch systems are already radiation-minimized
This means that subsequently added EMC shielding is hardly needed nowadays due to the further development of technology.
Seal membrane keypads
To ensure that no water or dirt can penetrate into the interior of the device, we use precisely dispenced seals. For this purpose, we use silicone-containing, silicone-free or conductive sealing materials.
Sealing of cable outlets is also possible. By spraying the cable outlet with
no water or dirt penetrates the inside of the membrane keypad.
More information about our seals.
UV protection for membrane keypads
For devices that are exposed to UV rays in outdoor use, among other things, we recommend a UV-stabilized polyester film. This special film material prevents discoloration and prevents fading colors.
The UV-stable film has a slight yellow tint. Therefore, color deviations may occur.
Antimicrobial film surface – hygienic for life
For hygienically demanding environments such as in medical and dental technology or in the food industry, we offer a specially developed antimicrobial film for the sustainable protection of membrane keyboards against bacterial contamination.
This innovative film material combines
antimicrobial properties with a durable surface. The antimicrobial protection is directly integrated into the textured hard coating. This ensures an even distribution of the antimicrobial agent over the entire surface of the keyboard, for its entire service life.
When microorganisms come into contact with the film surface, their cell walls are penetrated by the film’s protective agents. Cell functions are interrupted, and cell growth and reproduction are prevented.
To our medical keyboards with antimicrobial film.
We realize your design wishes in screen or digital printing. You can choose from a wide range of colors according to RAL-classic, Pantone or HKS. Even metallic colors for a very special effect can be easily implemented. We offer transparent viewing windows for displays or 7-segment displays, either clear or slightly structured.
The mechanics of the membrane keypad are completely adapted to your field of application. From button sizes and positions, to connector tape options and mounting options, to tolerance specifications are individually coordinated with you.
You decide on the connection option of your membrane keypad. Cable, connector, number of poles and wiring diagram will be fully customized to your device.
You want electronics assembly?
We create circuit diagrams, PCB layouts and parts lists for you or you provide us with your files.
Facts and figures
- Temperature: – 40 °C to 70 °C
- Switching current: (max.) 100 mA
- Service life: up to 1 million switching cycles
All technical data are not guaranteed properties, but may deviate depending on the customer-specific design.
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