Membrane Keypads for Kiosks, ATMs and Self-Service Terminals

A kiosk and ATM keypad presents a different engineering problem than a conventional machine panel. The person operating the device is not a trained operator, hundreds of different hands touch the same terminal every day, the unit usually runs unattended, and when something fails the cost of a field visit far exceeds the cost of the part itself. At Tushan Elektronik, the membrane switch keypads, embossed graphic panels, backlit panels and touch panels we build for self-service terminals are dimensioned around this reality: the design case is abuse, not nominal use.

What makes a kiosk and ATM keypad different?

Anonymous users and uncontrolled actuation force

A machine panel is used all day by the same handful of operators; habits form and actuation force becomes predictable. On a self-service terminal the user changes with every transaction. Keys are pressed with a fingernail, a key tip, a thick glove or an impatient palm strike. Dome selection therefore drives service life directly. Metal dome constructions typically deliver 1-5 million actuations with a crisp snap; polyester embossed (poly dome) constructions sit in the 100,000-500,000 cycle band. For a payment kiosk, ticket machine or PIN entry area handling several hundred transactions a day, metal domes are effectively the only sensible choice.

Unattended operation and the real cost of a service call

The terminal may sit at a hospital entrance, a car park exit, a fuel station or a municipal service point. Dispatching a technician to replace a panel costs many times the panel itself. That is why adhesive and interconnect details matter as much as graphics: 3M 467MP (0.05 mm) suits flat sheet-metal surfaces, while 468MP (0.13 mm) is preferred on painted or lightly textured surfaces. Tail exit direction and length, ZIF 1.0 mm pitch connector compatibility and the bend radius available inside the enclosure determine whether the panel can be swapped in the field by a single technician.

Outdoor conditions: UV, thermal cycling, humidity and sealing

PET or polycarbonate?

Polycarbonate (0.175-1.0 mm) handles deep embossing and gives a harder surface feel; polyester/PET (0.125-0.2 mm) performs better against UV exposure, chemicals and repeated flexing. For terminals behind glass, exposed to daily thermal swings and wiped regularly with alcohol-based disinfectants, a PET overlay with a hardcoat finish is the preferred specification. Graphics are always printed on the second surface, that is, the reverse side of the film, so legends and symbols sit behind the full film thickness and survive abrasion, fingernail scratching and cleaning agents.

IP sealing and the sheet-metal interface

Front-face protection at IP65 to IP67 level comes from joining the membrane layers beneath one continuous overlay and running an uninterrupted adhesive contour around the perimeter. The critical variable is the tolerance chain between panel and enclosure: die cutting works to ±0.2 mm, laser cutting to ±0.3 mm. Window and hole positions in the sheet metal must be dimensioned to absorb that allowance, otherwise the sealing frame loses bonding area. Because a sealed stack encloses a fixed air volume, pressure differences caused by temperature change can alter dome feel; this is accounted for during layer schematic work.

Accessibility and readability on a public terminal

Tactile identification and feedback

On a public terminal, finding a key without looking at the display is a functional requirement rather than a comfort feature. A raised dot on the centre key of a numeric array, rail embossing drawn between key groups and a defined emboss height per key all give orientation to users with limited vision. The typical 150-500 gf actuation force of a metal dome, together with a clean snap ratio, confirms registration even in noisy environments where audible feedback cannot be heard.

Sunlight readability and night-time illumination

A glossy overlay becomes unreadable in direct sun; a matte or selectively textured hardcoat breaks reflection and preserves contrast. For night use, an LED backlight layer is added: LEDs with a typical 50,000-100,000 hour service life, combined with a diffuser layer, produce even illumination across key areas. In a dead-front construction, symbols become visible only when the corresponding LED is on, leaving a plain surface when off. That approach is useful in kiosk interfaces where the same physical key carries different meanings at different steps of a transaction.

Technical requirement checklist for kiosk and ATM projects

• Overlay: PET 0.15-0.2 mm with hardcoat and matte/anti-glare finish for outdoor and high-contact use
• Printing: Second-surface screen printing, Pantone-referenced colour matching, clear windows for displays and readers
• Switching: Metal dome, 1-5 million actuations; actuation force selected per project, typically 150-500 gf
• Illumination: LED backlight or dead-front windows; typical LED life 50,000-100,000 hours
• Sealing: IP65 or IP67 target from the front face, uninterrupted adhesive contour
• Adhesive: 3M 467MP (0.05 mm) on flat metal, 468MP (0.13 mm) on painted or textured surfaces
• Interconnect: ZIF 1.0 mm pitch tail, length and exit direction set by internal bend radius
• Tolerance: Die cutting ±0.2 mm, laser cutting ±0.3 mm
• Accessibility: Raised dot on the centre key, distinguishable embossing or rails between key islands
• Language variants: Print film change only, on the same cutting contour, for alternative language and symbol sets

Typical layer stack and specification

Self-service terminal production in Turkey and the value of local supply

Turkey has a broad manufacturing base ranging from household appliances to textile machinery, and the electronic device and terminal builders that sit on top of that base cover banking automation, car park and access systems, fuel station automation, queue management and ordering kiosks. Part of this output is exported, and every destination market expects its own language, symbol set and colour coding. That is where a local keypad supplier pays off most clearly: language variants produced by changing only the print film on an existing cutting die, low first-batch quantities without a large-batch requirement, and a short revision loop during the prototype phase.

From sample to series: preparing the project data

What shortens quotation and sampling time on kiosk and ATM keypad projects is a complete data package at the first step. To get a fast response, please clarify the following: a DXF/DWG file with the cutting contour and window positions, vector artwork (AI/PDF) with Pantone colour references, key count with matrix or common-line arrangement, tail exit direction and length, connector type, LED positions and colours if illumination is required, target IP rating, operating temperature range and expected annual volume. With this input we prepare the layer schematic and flag critical points while the design is still open; after sample approval, series production runs on the same die and the same film recipe.

If you are specifying a front panel or keypad for a kiosk, ATM or self-service terminal project, send your technical file and we will prepare a layer stack proposal and quotation. Tushan Elektronik manufactures membrane switch keypads, embossed graphic panels, backlit panels and touch panels at its facility in Ikitelli Organized Industrial Zone, Istanbul. Phone: +90 212 671 65 18, Mobile: +90 551 600 62 31, e-mail: info@tushan.com.tr