Why is the Capacitive Membrane Switch so popular in the market?

1. What is Capacitive Membrane Switch?

Capacitive Membrane Switch is a branch product of membrane switch, but it is different from traditional membrane switches in that most of the time, it has no shrapnel, no protrusions, four-layer structure, and single line and IC input to drive. It can also be said that the Capacitive Membrane Switch can be driven to complete the line function without pressing hard. This is because when a human finger touches the Capacitive Membrane Switch, the IC recognizes the change in capacitance, thereby enabling the function. And fashionable appearance, long service life, can be widely used in smart home, communication equipment.

2. What are the design points of Capacitive Membrane Switch？

The Capacitive Membrane Switch is designed in different directions depending on the environment in which it is used.

• Outdoor use

Problem: Outdoor products are moisture and UV resistant.

Such problems result in a short product life and accelerated functional aging.

Design Considerations:

1. Use anti-ultraviolet materials: such as XE series Ketutai material, or DuPont’s HP92W, etc.
2. Capacitive Membrane Switch using 3M tape can achieve IP65 and above. Effectively resist rain and other problems.
3. Using the waterproof frame structure with 3M adhesive can achieve IP67 and above.

• Indoor use

Problem: glare problem

Indoor use often leads to operational errors due to glare problems, thus affecting work efficiency. Since the Capacitive Membrane Switch does not have Embossing, it will lead to this kind of problem even more.

Design Considerations:

Use anti-glare material, or anti-glare coating: Most of the matte materials are anti-glare, such as F150.V150. Generally, anti-glare coatings are used with Gloss materials such as EBG or EBA type materials. The reason for not considering silicone is that the Capacitive Membrane Switch will not use the Silicone Keypad as a panel

• Thickness

When the Membrane Switch needs to consider the thickness of about 0.5mm, it is very likely to choose the Capacitive.

• Deadfront (most frequently appearing in the discussion topic between users and Niceone-Keypad)

Among Membrane Switches, Deadfront is the most frequently considered Capacitive Membrane Switch.

What is the meaning of Dead Fronting of Graphic Overlay Panel?

Dead Front Printing is a printing method of Graphic Overlay Panel. The indicator light, logo and text are usually close to the background color and hidden when they are not illuminated by the light source. This method is conducive to the effective invisibility of the indicator light, logo and text. In order to let you know more about Dead Front.

Why is Deadfront so often used on Capacitive Membrane Switch?

This is because Capacitive Membrane Switch is often used in conjunction with Backlight. Whether the light source comes from the Capacitive Membrane Switch itself or from the light source with the PCB or external. In the case of opaque light, it is difficult to see that the logo of the product and the characters of the keys are different from the background color when the color is light or black. In the case of lighting, you will notice their difference.

3. What are the advantages of Capacitive Membrane Switch？

Capacitive Membrane Switch as a branch of Membrane Switch has several advantages:

• Easy to clean: Since Capacitive Membrane Switch is a flat product and has no embossing, if Cotutec or DuPont is selected as the overlay material, regular cleaning and drying can refresh the product without affecting the function of the product. It will not hide dirt and dirt like silicone or mechanical switches, which is inconvenient to clean.
• Long lifespan: Proper use and proper structure can exceed millions of taps over conventional Membrane Switches.
• The cost of Backlight is lower: This is because Capacitive Membrane Switch has a four-layer structure, no Metal Dome, and no need for Tactile Dot. At the same time, Capacitive Membrane Switch uses PC-type light guide film in many cases. This will save more costs.
• Small size: The structure of Capacitive Membrane Switch is generally four-layer structure as shown in the figure below. The volume is between 0.45-1mm.

Although the advantages are obvious, there are also disadvantages:

Although the cost of Capacitive Membrane Switch is low, the cost of the whole machine is increased.

At the same time, because it is easily affected by the change of capacitance, the capacitive switch is not well controlled, and it is easy to be triggered by mistake, over or affected by static electricity. This is one of the reasons why many medical devices do not choose capacitive switches.

4. How is the Capacitive Membrane Switch different from the regular Membrane Switch？

Although Capacitive Membrane Switch can be simply called Membrane Switch, it is quite different from the traditional Membrane Switch in structure, usage and design. Let’s let Niceone-Keypad engineer David Lei introduce:

structure:

Capacitive Membrane Switch is usually a four-layer structure. Membrane Switch is a 6-layer structure most of the time. So if you need thinner Membrane Switch, consider Capacitive Membrane Switch.

Circuit itinerary:

Capacitive Membrane Switch keys are single-threaded and controlled via IC. Most Membrane Switch products require positive and negative PINs to achieve key functions. However, the back of the capacitive line button is not allowed to route, because it prevents the line from interfering with the line function.

Design:

Capacitive Membrane Switches are generally flat and non-convex designs. The Membrane Switch is designed with a flat, bump-free and Embossing Dome.

How to use：

The Capacitive Membrane Switch is less used in industries with lower operating error rates, such as the medical industry. Because it is easily affected by static electricity.

5. What material can be selected for the circuit？

There are three optional circuits for Capacitive Membrane Switch: Flex Copper Circuit, Silver Flex Circuit or Printing Circuit Board.

Need excellent and stable performance: Niceone-Keypad will recommend Flex Copper Circuit or Printing Circuit Board. This is because these two types of circuits have lower resistance and better anti-vibration ability.

When a thinner design is required: Niceone-Keypad recommends Flex Copper Circuit and Silver Flex Circuit. At this time, because these two types of circuits are very thin, the overall thickness is between 0.1-0.188mm, which is suitable for thinner Capacitive Membrane Switch. And the thinner PCB goes to 0.4mm.

Need to complete complex circuit functions in a small area: Niceone-Keypad will recommend Flex Copper Circuit or Printing Circuit Board. At this time, because Flex Copper Circuit or Printing Circuit Board can pass.

Low performance requirements and cost sensitive: Niceone-Keypad recommends customers to use Silver Flex Circuit. This is due to the fact that silver oil lines are cheaper than gold plated and copper plate lines.

When the use environment is harsh: In the face of desert, low temperature environment, even high voltage, etc. Niceone-Keypad will recommend Flex Copper Circuit or Printing Circuit Board. In the environment of high humidity and high pressure, the silver migration phenomenon will occur in the conventional Silver Flex Circuit, which is why the first two are selected.

6. What are the additional processes？

Backlight: There are generally two forms, optical fiber or through light guide film to complete. These products are mainly used in low-light areas.

Resin Dome or PU Dome: The aesthetics are better. The buttons are more 3D stereoscopic.

Back Panel Process: The overall thickness can be increased by attaching an aluminum plate, reducing the assembly time for customers.

Contact Niceone-Keypad to customize the Capacitive Membrane Switch that suits you best.

Contact: info@niceone-keypad.com