A Membrane Switch
Membrane switches are switches that have at least one contact that is made of or attached to a flexible substrate. They perform the simple function of opening and closing a circuit. These switches are constructed into a thin stack of layers sandwhiched together using pressure-sensitive adhesives, usually as part of a keypad assembly.
Fortunately, most applications benefit from the simplicity of membrane switch construction, which also makes them easy to design and relatively inexpensive. However, the simplicity of membrane switches becomes more complicated due to the overwhelming list of configurable options they provide, including Metal Domes, Polyester Domes, Tactile, Non-Tactile, Force Sensors, SnapMax Switches, Flexible Circuits, Printed Circuit Boards, Adhesives, Seals, Vents, Embossing and more.
Why ALMAX?
The benefits of using ALMAX-made switch assemblies.
- Many Different Options
- Backlighting Integration
- Compatible With Graphic Overlays
- Rigid, Flexible, or Hybrid Circuits
- ESD, EMI or RFI Shielding Compatible
- Compact & Thin Profile
- Efficient Input & Output Controls
- Water Resistance & Sealing
- Long Switch Cycle Life
- Affordable
- Versatile
Tactile vs Non-Tactile Membrane Switches
- Key Differences
Membrane Switches can be split into two subcategories, namely Tactile, and Non-Tactile. The main difference between these two subcategories is the feedback the switch gives to the person operating the switch.
Tactile Membrane Switches
The purpose of a Tactile Membrane Switch is to deliver a physical and audible sensation upon actuation. When the switch is depressed, the switch typically responds with a ‘snap’, ‘click’, or ‘pop’. This is due largely to the type of actuator that has been adopted for the particular application. Metal Domes, SnapMax Switches, Dome Emboss, and PolyDomes are all Tactile Switches. Tactile feedback, size, and the force necessary to trigger the switch can all be fine-tuned to meet your desired specifications.
Tactile Membrane Switch Cutaway
Non-Tactile Membrane Switch Cutaway
Non-Tactile Force Sensors
Non-Tactile Membrane Switches
When a Non-Tactile Membrane Switch is utilized, the result is no direct physical or audible response indicating that the button has been pressed. Instead, Indication is handled by other means, usually through embedded processing or direct electrical connections. This can turn on LEDs, make sounds, provide haptic feedback, or show readings on an instrument display.
The layer stack of a non-tactile switch requires two circuit layers and an air gap between them to function. Two variations are commonly used to provide this.
The first most common method uses two flat circuit layers with space between (Dual Circuit Switch). The secondary method involves printing the top circuit directly on the backside of the overlay (Conductive Overlay Switch).
Both methods operate identically. When the switch is pressed, the two circuit layers connect, completing the circuit and allowing an electronic signal to reach its desired destination.
Non-tactile switches are inherently more durable and fully sealed from the outside environment. Giving Non-Tactile Membrane Switches the advantage of being rated for up to three times as many actuations as a Tactile Membrane Switch.
Membrane Switch Actuators
- Key Differences
Membrane Switches must contain at least one contact that is made of or adheres to a flexible substrate. Otherwise, it is not a membrane switch. The part of these assemblies that is flexible, is almost always the actuator, which is the component that also provides the the tactile feedback. Each type of actuator uses different electro-mechanics to provide a switch closure.
Metal Dome Actuators
Tactile metal dome actuators are momentary switch contacts made from conductive metals that become normally-open tactile switches when utilized on a PCB or flex circuit.
To secure metal domes to the circuit layer, a custom fit pressure-sensitive adhesive tape is used. In its relaxed state (not pressed), Metal domes lie against the upper rim of their directional pathway. When pressed, the dome collapses or bends, reaching the end of its travel on the circuit layer, and, in turn closing the designated circuit. There are many various forms and actuation forces to choose from depending on your application.
SnapMax® Actuators
SnapMax® actuators are a switch technology that was acquired and revised by ALMAX from the original DuraSwitch PushGate Switches.
They are a patented actuator that incorporates crisp tactile feedback similar to most other switches. However, what makes this switch unique is its use of magnets and an armature, as opposed to bending, flexing, or grinding. This means that parts that normally wear out in membrane switches are now excluded.
Polyester Dome (PolyDome) & Dual Circuit Actuators
Unlike the previously mentioned membrane switch actuators, polydome switches do not include any metal dome or hard materials in its makeup. Instead, polydomes use conductive ink and 2 separate circuit layers so that they can work the same as a metal dome.
The polyester, or PET, is thermoformed to provide a stiff plastic dome. When the polydome is pressed, the conductive ink on the back of the polydome connects with the lower circuit layer to close the switch.
Rubber Keypad & Conductive Overlay Actuators
A rubber keypad membrane switch uses compression molded silicone rubber that has conductive carbon pills on rubber plungers. These rubber switches are compression molded creating an angled web around the center of the key.
When a key is pressed, the webbing around the switch collapses or deforms to produce a tactile response. When the pressure on the key is released, the webbing springs back to its original shape, providing positive feedback. The closure of the switch circuit occurs when the conductive pill or printed conductive ink makes contact to the lower circuit layer.
澳洲幸运10平台注册
| Layers (Top To Bottom) |
Metal Dome (Tactile) |
SnapMax® (Tactile) |
Polyester Dome (Tactile) |
Dual Circuit (Non-Tactile) |
Conductive Overlay (Non-Tactile) |
|---|---|---|---|---|---|
1 |
Graphic Overlay |
Graphic Overlay |
Graphic Overlay |
Graphic Overlay |
Graphic Overlay w/ Upper Dome Circuit |
2 |
Overlay Adhesive/Spacer |
Overlay Adhesive/Spacer |
Overlay Adhesive/Spacer |
Overlay Adhesive/Spacer |
Overlay Adhesive/Spacer |
3 |
Dome Retainer/ESD Shield |
SnapMax® Retainer/Spacer |
Upper PolyDome Circuit/ESD Shield |
Upper Non-Tactile Circuit/ESD Shield |
Lower Circuit |
4 |
Metal Dome |
SnapMax® Switch |
Circuit Spacer |
Circuit Spacer |
Mounting Adhesive |
5 |
Switch Spacer |
Pad Printed Carbon |
Lower Circuit |
Lower Circuit |
|
6 |
Pad Printed Carbon |
Lower Circuit |
Mounting Adhesive |
Mounting Adhesive |
|
7 |
Lower Circuit |
Mounting Adhesive |
|
|
|
8 |
Mounting Adhesive |
|
|
|
|
Membrane Switch Manufacturing Services
ALMAX provides top tier manufacturing for a complete array of membrane switch technologies. From concept design to volume manufacturing, our partners entrust their custom membrane switch needs to our engineering and manufacturing teams. We specialize in solving human interface challenges and establishing quality control across the entire membrane switch manufacturing process.
In over 20 years, we have expanded our operations greatly, including a domestic prototype facility and two offshore manufacturing plants. This gives us the ability to meet high volumes of production.
ALMAX offers high quality switches that serve a variety of industries. This is thanks to our state of the art facilities and processes, as well as our expert engineering team.
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