What Are the Advantages of Using Capacitive Touch Switches?​

What Are the Advantages of Using Capacitive Touch Switches?

What are Capacitive Switches?

A capacitive switch is a type of touch-controlled electrical switch that operates by measuring change in capacitance. It works in the same manner as a typical capacitive smartphone: when you touch the surface, a small electrical charge is transferred from your body to the switch, which subsequently causes a change in capacitance. The switch detects this change, responding with the appropriate command.

Upon touching a capacitive switch, this electrical charge disturbs the switch’s own electrical charge; thus, causing a change in capacitance. Because of this change, the switch can identify when and where the touch occurred.

Capacitive Switch Construction:

A capacitive switch consists of three main layers, the graphic overlay, the circuit, and the backer:

  • The overlay consists of the graphic artwork and can also include windows, embossing, coatings, adhesives, and selective texturing.
  • The circuit switch will either be a Flexible Printed Circuit or a Printed Circuit Board.
  • The backer is the final part of the capacitive switch, and may or may not include an adhesive that must bond to your specific substrate. The most common materials used for overlays are plastic, acrylic, and glass due to their durability and versatility.  

Capacitive touch switches are widely used in aerospace, military equipment, medical instruments, intelligence control, commercial appliances, security products, etc.  Capacitive touch interfaces are also widely used in the fields of consumer electronics, household appliances, car security system, LED application, lamps lighting decoration application, solar photovoltaic application, sound, mobile terminal tablets, etc.

Major Features of Capacitive Switches:

  1. Beautiful and aesthetically appealing appearance; strong graphic clarity; straight-forward design.
  2. Sealed design ensuring top performance and wear resistance; anti-fade and non-deformation; long life span.
  3. Waterproof and anti-interference.
  4. No metal contact; simple structure; low cost.
  5. Operation comfort; excellent sensitivity.
  6. It can realize intellectualization and operate more conveniently.
  7. Its reliability can replace various panels, such as metal keypads, membrane keypads, etc.
 

Product Advantages:

There are no mechanical components in a capacitive switch, resulting in a longer lifespan when compared to their mechanical counterpart. Additionally, capacitive switches can withstand some of the harshest environments, including outdoor environments. If the intrusion of dirt, dust or moisture is a concern, capacitive is probably the best option for an electrical switch.

The key thing to remember about capacitive switches is that they require direct contact with a conductive object to operate. This is why using a stylus typically won’t work (unless it’s a capacitive stylus). Capacitive touch control switches can actually detect the touch of a finger through more than 20mm thick of an insulating material shell, such as tempered glass or plastic film. It ensures that the product’s sensitivity, stability, reliability are not changed with ambient conditions and long-term use, and has the waterproof and anti-interference ability.

Capacitive touch control switches do not require the user to touch metal directly, which can eliminate potential safety hazard. The part of touch circuit is placed on the back of insulating material shell, it is easy to make a keypad sealed with the surroundings. It has no any mechanical components, doesn’t wear out, has long a lifespan, and can reduce the later maintenance costs.

Optical Bonding in Membrane Switches and User Interfaces

Optical Bonding in Membrane Switches and User Interfaces

The type of bonding technology you choose for your membrane switch or HMI are all dependent on the design and product requirements. There are three typical bonding methodologies: liquid optically clear adhesive (LOCA), optically clear adhesive (OCA), and air gap bonding. CSI will work closely with you in the early stages of the product development to offer a custom designed solution to fit your exact requirements. 

Opti Bonded Membrane Switch

Bonding Options:

Liquid Optically Clear Adhesive (LOCA)

The air gap between the display surface and the rear side of the sensor is filled with a UV liquid adhesive. The adhesive is silicone-free, non-aging and UV stable. The method is typically suitable for TFT displays with frames.

The liquid adhesive is applied over the cover glass and then bonded to the touch panel or TFT panel. The adhesive is spread evenly and bubble-free between the two components. The adhesive is cured without heat using UV light. This prevents.

LOCA offers the most robust and best overall performance of any bonding technology.  Handheld devices such as tablets and laptops have led the way using LOCA in display integration. Other industries such as agriculture, military and avionics have incorporated LOCA because of its durability. 

Optically Clear Adhesive (OCA)

This is a lamination process with optically clear adhesive (OCA). A lamination from “soft to hard” takes place, e.g. a film-based sensor (ITO / mesh) behind the cover-lense. With the help of storage in an autoclave, the air bubbles are eliminated.

OCA is commonly used on touchscreens, LCD flat panel displays, transparent graphic overlays and other devices requiring an optically clear bond.  OCA’s thin, consistent thickness makes it an ideal choice for flexible to rigid bonding and tight tolerance bonding situations.  OCA is classified as a dry film, pressure sensitive adhesive and there are different versions depending on the application and substrate to which it will be applied.

Air Gap

In this process, the display is glued with an adhesive frame directly behind the sensor or on the printing of the cover-lense in a clean room. An air gap between the display and the sensor and cover-lense remains. Air bonding is both a simple and cost-effective way to integrate displays with cover-lenses or touch sensors. Depending on the application, the assembly takes place with single adhesive strips or with a closed adhesive frame. Both economical and lightweight, an air gap display construction is a popular option for personal handheld electronics such as smartphones. The layers are integrated with a gasket leaving behind a small air gap. 

What is a Capacitive Switch?

What is a Capacitive Switch?

As touch screen solutions have become more prevalent especially with the use of smartphones, capacitive switches have also become a very popular interface solution. A capacitive switch is a type of touch controlled electrical switch that operates by measuring change in capacitance. It works in the same way as a smartphone with a capacitive touch screen. Essentially, a small electrical charge is transferred from your body to the switch when the surface is touched, which  causes a change in capacitance. The switch detects the change in capacitance and responds with the appropriate command.

Upon touching a capacitive switch, this electrical charge disturbs the switch’s own electrical charge; thus, causing a change in capacitance. Because of this change, the switch can identify when and where the touch occurred.

Capacitive Switch Construction:

A capacitive switch consists of three main layers, the graphic overlay, the circuit, and the backer:

  • The overlay consists of the graphic artwork and can also include windows, embossing, coatings, adhesives, and selective texturing.
  • The circuit switch will either be a Flexible Printed Circuit or a Printed Circuit Board.
  • The backer is the final part of the capacitive switch, and may or may not include an adhesive that must bond to your specific substrate. The most common materials used for overlays are plastic, acrylic, and glass due to their durability and versatility. 
 

Benefits of Using Capacitive Switches:

  • Easy to clean
  • Backlighting capabilities
  • Highly decorative solutions
  • Cost effective
  • Integration of displays