Functional screen printing pastes for membrane keyboards

Colours for membrane keyboards and other input systems

The membrane keyboard exists in various variations and for decades has been the input interface in diverse applications. Medical technology, tool and machine building and also consumer electronics without membrane keyboards are now hardly conceivable. In addition to cost-effectiveness, of course reliability also plays a decisive role for the proliferation of such systems. Membrane keyboards are comprised of a number of materials, such as the carrier foil (as a rule a PET film), functional screen printing pastes, spacer films and laminated films, metallic switch wafers, graphical colours, and LEDs. Due to the constantly increasing additional functions in modern input systems, it is necessary to accommodate as many circuit paths as possible in the smallest possible space without compromising the performance capability. 

The Printed Electronics product line of ELANTAS Europe develops and produces functional screen printing pastes and matched material systems under the brand name Bectron®. As a member of the Fachgemeinschaft Eingabesysteme (Association of Input System Specialists), ELANTAS Europe profits from many years of experience in this range of applications.

The Printed Electronics product line offers different silver and carbon-based conductive pastes, along with insulating pastes, which are distinguished by their ruggedness, cost-effectiveness and flexibility. 

Your advantages:
•    The requirements of the membrane keyboard provider are completely fulfilled.
•    High flexibility (80 double crease < 10% bending)
•    Fine-line printing for superior accuracy and efficiency. Very high conductivity (< 10 mΩ/sq/mil)
•    Excellent adhesion to pre-treated and untreated PET films

In order to offer the best possible quality, in addition to the established tests for adhesion, flexibility and viscosity we also utilise the newest and most reliable measurement methods for film thickness measurements and electrical characterisation. Furthermore, for the development of screen printing pastes we place particular emphasis on processability and runnability and also on cost -effectiveness.

Due to the large number of available substrates it is not possible to utilise a single colour system for all carrier foils. Two basic systems are therefore available, for pre-treated and untreated PET substrates. The interdisciplinary competence within the ALTANA Group was brought together at the Hamburg site. This enables the development of products with very specific requirement profiles, such as pastes with good adhesive properties for films, and metallic or ceramic surfaces.

The hardening and drying mechanisms also play an important role for the choice of product when, for example, production is to take place on a background with limited drying capacities. Here, we offer fast-drying pastes and variants which are particularly insensitive to drying and consequently exhibit a so-called long screen service life.

For new projects, unknown substrates can be tested for paste compatibility in our own pressure laboratory. Alternatively, we can also make paste samples available for initial testing in order to assess the behaviour under real conditions. Our Applications Engineering will be happy to support you and provide training on-site.

ProductDescriptionCuringBenefit
Bectron® CP 6662Conductive silver ink10 min at 120°C

Optimized for fine line printing, very flexible, long screen
open time, good adhesion to untreated and treated PET films, <0.010 Ω/sq/mil

Bectron® CP 6619
 
Conductive silver / carbon ink 10 min at 120°C"Long screen open time, Long screen open time,
<0.025 Ω/sq/mil"
Bectron® GP 9552Conductive carbon ink10 min at 120°C"Silver top-coat with good adhesion to treated PET films,
Silver top-coat with good adhesion to treated PET films,
<40 Ω/sq/mil"
Bectron® GP 9553Conductive carbon ink10 min at 120°CGood adhesion to silver and untreated PET films, <40 Ω/sq/mil
Bectron® DP 8442Insulating ink green5 m/min at >600 mJ/cm² UVAGood adhesion to silver, untreated and treated PET films
Bectron® DP 8443Insulating ink blue5 m/min at >600 mJ/cm² UVAGood adhesion to silver, untreated and treated PET films
Bectron® DP 8444Insulating ink colorless5 m/min at >600 mJ/cm² UVAGood adhesion to silver, untreated and treated PET films

 

Request your technical data sheet advancedPrinting@remove-this.altana.remove-this-also.com

As a rule, the conductive Bectron® CP silver screen printing pastes have a high silver content, enabling very fine lines and at the same time a high film thickness. Compared with many competitors‘ products claiming to have good conductivity values, Bectron® pastes excel by their greater coating thicknesses, ultimately resulting in higher current carrying capacity and signal accuracy. These pastes can therefore also be used beyond the membrane keyboard application for printing antennas, feed cables for heating systems, and other sensor-based applications. Suitable modification of the screen can reduce the ink consumption and the film thickness to no more than the required value for the particular application, generating an excellent cost-performance ratio compared with many existing silver pastes.
 

The Bectron® GP graphite pastes and the UV-hardening Bectron® DP insulation pastes complement the Bectron® silver inks.

Bectron® GP graphite pastes serve to protect the silver paste at sites with mechanical loading, e.g. at contact points, in order to prevent metal-to-metal abrasion. The graphite serves as a lubricant, while the special formulation prevents stirring up dust from graphite particles, which could cause short circuiting. The graphite can, however, also serve as a series resistor for LEDs or as a touch electrode.
 
In addition to their insulating capability, Bectron® DP insulation pastes enable bridge printing in order to realise printed conductor crossings. Multilayer constructions are therefore no problem for the matching Bectron® material system.

With the optimally chosen product properties, throughput times can be shortened and investments in new equipment made unnecessary. The functional Bectron® pastes fulfil the wish for a higher integration density for modern input systems at attractive prices without having to comprise quality.

For questions about the choice of appropriate materials and application-specific questions, please feel free to contact us directly under advancedPrinting@remove-this.altana.remove-this-also.com

Learn more about our portfolio for printed electronics.