Capacitive touch sensors

Printed capacitive touch sensors may be used as cost-effective user interface on professional machines and consumer applications, where button-less touch operation is preferred.

Capacitive touch sensors is typically placed behind a sheet of glass or plastic that offers a simplified operation and a design expression that meets the ever-growing trend towards touch-operated user interfaces.

Each sensor is adapted 100% to the end product with a focus on developing the most user-friendly and cost-optimised control panel.

The development of the capacitive touch sensor is done in close cooperation between the customer and Mekoprint’s engineers.

Read more about the functionality and structure below. Contact Mekoprint for input on capacitive touch sensors.

R2R PRODUCTION

Mekoprint’s production of printed electronics takes place in a fully automated roll-to-roll setup, adapted to the NPI process from early development to series production and testing.

Mekoprint has a setup for the production of prototypes which enables cost-effective design verification early in the development process.

The volume production of capacitive touch sensors on continuous rolls ensures great advantages in relation to the overall cost, production time and quality. Depending on the product’s further processing, the workpieces can be delivered on roll, in sheets or as stamped workpieces.

All processes from printing, post-processing and final testing are carried out with a minimum of manual handling.

FULL DESIGN FREEDOM

When developing a printed capacitive touch sensor, there is complete freedom with respect to design, size and shape of the electrode area, which can be adapted to any interface design.

Capacitive touch sensors are produced in flexible, pliable foils which make them particularly well suited for use on curved and irregular surfaces.

There is an option for transparent and backlit fields, just as diverse operation with keys, slider, wheel or screen application can be integrated.

A printed capacitive touch sensor can be combined with a graphic printed cover. This is an extremely cost effective way to add functionality to a graphic foil overlay.

MATERIALS AND ASSEMBLY

MATERIALS
Often, a thin polymer foil is used, typically PET or PC, where silver, carbon, transparent conductors or transparent lacquer is applied via screen printing. The materials selected are based on the sensor’s application environment.

MOUNTING AND CONNECTION
The flexible capacitive touch sensor is easily mounted on the back of a front cover with pressure activated adhesive or by mechanical fastening.

Connection to the underlying electronics is made with springs or flat cable connection (FPC).

MASKING OF THE SENSOR

DEAD FRONT AND BLACKOUT EFFECT
Do you want the capacitive touch sensor behind the glass pane masked, so that the front appears as a uniform black colour when switched off?

There are various ways to achieve such an effect. Either a tinted glass can be used, or a dead front can be printed on the foil. The black colour can be graded, depending on how much light should be able to slip through.

The solution for optimum optical appearance varies from product to product. In collaboration, we find the solution that gives the final product the best visual appearance.

LIGHT DIFFUSION

If the key is backlit, the diode located behind the foil will typically light up in one point. In order to ensure uniform symbols with homogeneous lighting, a diffuser is integrated. Hereby, LED hotspots are avoided and symbols will appear as if lit up from multiple angles.

There are two options. Either a transparent foil with an inherent diffuser capability is chosen. Or, a standard is chosen, on which diffusing colour is applied.

DIFFUSING COLOUR

Low costs
Flexibility in design (print areas)
Freedom of choice regarding foil and colour
Degree of integration (printable directly on graphics or circuit)

DIFFUSER FOIL

High transmission efficiency is optimal for low light
Long service-life
Better diffusion compared to printed diffuser ink
Higher cost

100% ELECTRICAL TEST

Mekoprint offers electrical testing of all or part of the production. Like the rest of the production, this is done in a roll-to-roll setup.

Measurement of capacitance
Measurement of resistance
Measurement of inductance
Measurement of broken conductor courses
Measurement of shorted conductor courses
Measurement of components

WHITE GOODS

A foil-based capacitive touch sensor with an adhesive is particularly suitable in combination with curved surfaces, which is often seen in major household appliances such as washing machines, dryers, ovens and dishwashers.

It is also an option to develop capacitive touch foils for plastic casting (IME/Plasttronics).

Mekoprint’s customers in the white goods sector are some of the biggest in the world. In cooperation with them, Mekoprint constantly challenges the limits for how foils can be developed, produced in terms of screen printing and tested with 100% electrical tests.