Membrane Switch Structure
Raised membrane switch: The switch button bulges slightly, which is a little higher than its panel, thus forming a membrane switch in a solid shape. The solid button can help the mainpulator accurately determine the position of the key body, improve the recognition speed and stimulate their sensitive feelings. The bulge of the membrane switch can be designed to be well diversified across the market, in order to increase the decorative effect for the perfect appearance.
Flat membrane switch: The membrane switch is relatively common in its initial stage. The key in the membrane switch is simple in design, only with simple colors to express the position, shape and size of the key body. The manipulators can only use their vision to recognize the accuracy of the key operation. There is no appropriate feedback to show whether the manipulator presses the effective range of the switch with his fingers to control it, thus affecting our confidence for monitoring the whole machine and operation speed.
Kinds of Materials
Polycarbonate(PC): Temperature Resistance: -60~120℃
Smooth, high transmittance, environment-friendly, low water-absorbing quality, high dimensional stability, high bending strength, tensile strength and compressive strength; excellent heat resistance, cold resistance, electrical insulation and atmosphere aging resistance. PC can cause stress cracking easily,and then forming the flaking of coating gradually through the process of oxidation owing to its poor chemical (organic solvent) and fatigue resistance. The flaking of coating is determined by the environment and broken down gradually until finally. The time of physical damage is within 3 to 8 years. With its very wide scope of application, PC can meet the requirement of most of the membrane switch panel.It can also meet the needs of the membrane switch with LCD (liquid crystal display) screen because of its high transmittance.
Polyester(PET): Temperature Resistance: -30~160℃
Smooth, good chemical resistance, insoluble in common organic solvents, not alkali-resistant; good mechanical propertym, insulation, heat resistance, hardness; The toughness of PET is the highest among all thermoplastic plastics;low water absorption capacity, excellent abrasion and frictional resistance, especially its high bending resistance and elasticity; high size stability. PET’s tensile strength which is far higher than that of PC and PVC, would be rivaled only by aluminum film. PET is the optimal base material for making the Haven membrane switch circuit. It is the first choice to make the Haven membrane switch panel by using PET that has textures (Autotype sequence), which is more expensive than common PET (Haven 80% selection of materials).
Polyvinyl Chloride(PVC): Temperature Resistance: -20~60℃
Smooth, stable to acids, alkalis and salts at room temperature, excellent abrasion resistance, fire retardancy and self-extinguishing, noise elimination and shock absorption, excellent electrical insulation and poor heat stability.
Types of Membrane Switch
Flat Tact Switch (without hand feeling)——The contact surfact does not adopt any secondary technologies.
Advantages: The keystoke life is more than 2 million times and the contact area is large.
Disadvantages: monotonous; no hand feeling; result in operation errors easily.
Disadvantages: The shrapnel may be damaged, which could cause a short circuit or not rebound so that it cannot be re-assembled when there has little bumps on lining plate or the arc shape of the plate is in a wide curve.
Hot-Pressing Sensor Switch (PET keys)——After the contact surface is printed on the keys which are made from PET materials, there will have a bump on the panel under the action of hot-pressing and thus will result in resilience force.
Advantages: The keystoke life is more than 1 million times; good hand feeling.
Disadvantages: It may reduce the hand feeling of keys when the membrane switch is used in high temperature.
Metal Shrapnel Switch (snap dome) —— Adopting shrapnel as the key contact surface of the upper circuit.
Advantages: a) Good hand feeling, uniform force; b) The mainpulator can hear the clear sound when operating it; c) It can still be used for normal even in high temperature.environment.
LGP (Light Guide Plate) Switch —— The light guide plate is embedded into a conventional membrane switch.
Advantages: The switch can still be operated even when it is in a dark place; more ornamental; Its cost is lower than EL.
Disadvantages: It can only be fixed in such an embedded mode because of its big thickness.
EL Backlight Switch —— The EL backlight is embedded into a conventional membrane switch.
Advantages: The switch can still be operated even when it is in a dark place; more ornamental.
Disadvantages: The cost is more higher; EL needs to be configured the driver;110V voltage.
FPC (Flexible Printed Circuit) Switch —— The circuit layer of the membrane switch adopts FPC material.
Advantages: High-precision circuits; The minimum line-spacing can achieve 0.5MM; extremely low resistance value; It can be welded with many kinds of smaller components such as LED, resistance, optical fiber and so on; reliable performance; long life; The non-common silver paste FPC switch may compare.
PCB (Printed Circuit Board) Switch ——The circuit layer of the membrane switch adopts PCB material.
Advantages: Low resistance; High-precision circuits; It can be directly welded with some components of the circuits on the back of the PCB switch.
Disadvantages:It can be more than a little inconvient when assemblying the whole machine, compared with FPC switch, because it needs to be soldered the connector and threaded the lead with flat cable.
Switch with LED light (Light-emitting Diode): The LED light is installed in the membrane switch as a whole.
(a) The LED circuit is in the same layer with lower circuit: It is simple in structure, but the surface of the LED windows should be in a convex shape, otherwise the LED light will lift the panel; It should choose little height of small LED light and be applyed to the situations where the amount of LED lights is relatively small.
(b) The LED circuit is in different layers with lower circuit: It is complex in structure, but the surface of the LED windows don’t have to be in a convex shape; It should be applyed to the situations where the amount of LED lights is relatively large; It needs to be opened the punching die and primer die.
Disadvantages: It is more likely to be NG under great pressure and difficult to repair.
Different products has different request, so need the material is different, the material used on the membrane switch depends where is the membrane used, then can decide what material used!
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Post time: Apr-29-2019