About Membrane Switches and Membrane Switch Manufacturers
Including: Graphic
Overlays, Membrane
Keyboards, Membrane
Keypads, Metal Domes & Tactile
Switches.
Membrane switches are thin electronic buttons used to activate functions performed by various types of appliances and electronic equipment. Unlike push buttons or mechanical electrical switches, membrane switches contain no moving parts and are comprised of a thin printed electric circuit film laminated with a graphic overlay.
Tactile switches are formed by
metal domes located between the membrane switch's
graphic overlays and printed circuit film, while non-tactile, flat switches connect with the circuit board through electrically conductive ink printed on the underside of the graphic overlay. When pushed, these switches create an electronic connection within the membrane's underlying circuit; this connection sends a signal through circuit connections to activate the electronic appliance to which it is attached in various capacities. Membrane switches are used in
membrane keyboards or
membrane keypads as control panels on microwave ovens, fax machines, copiers, ATM keypads, medical devices, oven/stove controls and TV remotes. Because membrane switches are made from thin flexible polymers and adhesives, they highly space efficient, easy to apply and easy to use. Control panel devices in countless industrial, commercial, consumer, office and household appliances and equipment types.
There are three main elements to a membrane switch: the printed film electrical circuit board, the electrically insulating spacer and the graphic overlay. The circuit board is a thin polymer film which on which a circuit board pattern is printed with an electrically conductive silver-based ink. An adhesive spacer sheet is patterned with cutouts where electronic switches will go and is bonded to the circuit board. For tactile switches with a more concrete feel, small metal domes made from nickel-plated stainless steel are placed above each connecting circuit on the circuit board. A clear polyester adhesive film secures these domes in place. Non-tactile switches make electrical connection through silver-based conductive ink printed on the back of the graphic overlay. The graphic overlay, which is the outer surface of the membrane switch, is an acetate film patterned with buttons through photochemical processing and screen printed with appropriate colors and text. This is finally laid over top the circuit board and spacer sheet with an adhesive, and the membrane switch is ready to be tested and installed. All of these processes are executed under rigidly controlled clean room environments in order to prevent malfunction-causing contamination during assembly.
As a relatively recent technology, membrane switches use a very simple electrical concept in a highly sophisticated way. Membrane switches are easier to fabricate and require fewer materials than mechanically operated push buttons traditional typing keyboards. Because membrane switch manufacturing requires far fewer materials than push-button keyboards and keypads, it is a highly cost-effective process. Switches may be flat or tactile, and miniature LED indicator lights may be incorporated within the switch. If properly sealed from contaminating dirt and moisture, membrane switches avoid the mechanical failure that occurs in mechanically operated switches, and are generally versatile, durable, user friendly and dirt resistant. Membrane switches are impervious to moisture and dirt, an important feature for users of home appliances and children's games that are operated through membrane switch control panels and keyboards. Watertight membrane switches are available as well, opening up a wide array of underwater applications.
Membrane Switch Types
- are decorative covers that are placed over control panels.
- are flat surfaces with printed symbols and outlines rather than traditional moving keys.
- are flat surfaces, rather than moving keys, that are activated with the press of a finger.
-
supply the snap and complete the electrical circuit. The domes are from
pressed stainless steel or aluminum and come in various shapes, sizes
and thicknesses.
-
are membrane switches made without a snap action.
-
are produced by embossing domes into one of the polyester layers in
the construction, which results in a very durable tactile element with
a little more movement than metal domes. This diminishes the quantity
of layers in the assembly.
-
are assembled to supply a positive snap-action reaction to pressure.
They can be attained through polyester domes made in either the graphic
or circuit overlay layer or stainless steel domes embedded in the membrane
switch.
Membrane Switch Terms
- The degree to which a
membrane switch is able to withstand surface wear.
- This is the action of working a switch apparatus.
- The pressure necessary for collapsing the walls
of the dome on a polyester, rubber or metal keypad.
- The molecular attraction of one material to another.
The strength of the bond is determined by the surface energy in each
material.
- An adhesive applied to the back of a membrane
switch for mounting purposes.
- The minimum voltage at which the insulation
between two conductors is destroyed.
- The type of ink that consists of prepared
suspensions of carbon black and is frequently printed over silver circuitry
to diminish the potential of migration of silver. These are used for
lessening costs when the conductivity of a metal base system is not necessary.
- A material's ability to allow electrons to
flow.
- A conductor intersection insulated by dielectric material.
- A cosmetic feature of a graphic overlay in which a
button is only visible when backlit.
- An insulating or non-conducting medium.
- Used for printing
protective patterns on conductive printing to isolate selected regions
from electrical contact with other conductors. This is used for cross-overs
and tail insulation on membrane switches.
- An adhesive
layer made to hold metal domes in the keyswitch.
- A slender device that
illuminates large areas, typically used in LCD membrane switch backlighting
and control panels.
- Procedure of integrating a surface mount LED into
a membrane switch assembly.
- A way to supply a raised characteristic to accentuate
key surfaces through mechanical and thermoforming of graphical features.
This also permits an embedding of a surface mount of an LED inside the
switch.
- The extent of shininess of a substrate, commonly
identified in percentages.
- Control keypads
that use graphics for button functions for navigation on machines or process
operations. Typical graphics include arrows or symbols indicative of a
machine process or operation.
- Switch openings connected to one another to
seal the switch from moisture and other contaminants.
- A measure of the distance from the highest point of
a key to the base of the keypad.
- Embedded in membrane switch layers
to illuminate the button.
- A material's ability to resist the
absorption of water from the air or during complete submersion.
- The decorative front layer of a membrane switch or control
panel.
- The travel that is done by the rubber keyboard or
metal dome after making contact with the circuit.
- Creating a raised surface in the graphic overlay
over the membrane keypad area of membrane switches.
- The schematic that describes the circuit output requirements
for membrane switches.
- Adhesive materials that bond after pressure
without needing heat or solvents.
- Produces a raised ridge circling the key area.
- Printing procedure that uses a stretch of mesh
over a frame, permitting the use of a stencil to discriminately allow
ink through. This is typically used for creating graphic overlays and
membrane circuits.
- Finely-milled particles of silver suspended in various
resin systems that produce conductive patterns on rigid and flexible
substrates. This is a typical conductor material for membrane switches.
- A membrane switch adhesive layer that separates circuit
layers to supply keyswitch openings, permitting the contact of conductors
when depressed.