Components · Inlay
The radio inside the card
An etched aluminium coil on PET film, bonded by adhesive engineered for a pairing ordinary glue fails. You never see it — every read at every door depends on it.
The inlay is where the card stops being plastic and becomes a credential: a chemically etched antenna on PET carrier, laminated between dip-coated bonding films whose adhesive holds > 7 N/cm as made and > 3.5 N/cm after damp-heat ageing. It is the same construction transit systems have proven across billions of tickets.
Highlights
Etched, not wound
Photo-etched coils repeat perfectly — every card reads at the same distance.
A bond built for PET-PVC
Dip-coated films solve the pairing standard adhesives fail, humidity included.
Transit-proven construction
The identical build behind billions of metro smart tickets worldwide.
Inlay & antenna materials — technical data
- What it is
- The radio heart of every contactless card: an etched aluminium antenna on a PET carrier, bonded by dip-coated adhesive films
- Antenna
- Aluminium coil chemically etched on a PET film sheet — repeatable geometry, tuned to 13.56 MHz chip families
- Bonding film
- Card-grade PVC dip-coated with adhesive both sides: clear 60–200 μm, white 70–200 μm
- Adhesive
- 6–9 g/m² per side — engineered for the PET-to-PVC bond that ordinary laminate adhesives fail
- Bond durability
- Peel strength > 7 N/cm as made; > 3.5 N/cm after damp-heat ageing — the card stays bonded through years of humidity cycles
- Format
- Webs 200–1300 mm — inlays are laminated as large sheets, then punched to card positions
- Pedigree
- The same construction used in transit smart tickets issued by the billions
Inside an RFID inlay
PET and PVC do not naturally bond — their surface chemistries fight each other. The dip-coated film solves it: a PVC sheet carrying adhesive tuned for exactly this pairing. Antenna sheet plus bonding film laminate into a prelam that behaves as one material, which then disappears invisibly inside the finished card. When a key card still reads after two years of pockets and pool bags, this bond is why.
The prelam at the centre of every contactless card we laminate
- Coated bonding film · 60–200 μm Dip-coated PVC, adhesive on both faces
- Etched antenna on PET + chip Aluminium coil, chemically etched — the card’s radio
- Coated bonding film · 60–200 μm Seals the antenna sheet from the other side
Why the inlay spec matters to you
- Read reliability is bond reliability: a delaminating inlay shifts the antenna and kills reads — the > 7 N/cm bond prevents it.
- Humidity is the real enemy: damp-heat-aged peel strength is the number that predicts survival in tropical properties.
- Etched antennas hold tuning: repeatable geometry means every card in the batch reads at the same distance.
Inlay & antenna questions
What is an “etched” antenna and why prefer it?
The coil is chemically etched from aluminium foil laminated to PET film, like a flexible circuit board. Compared to wound copper wire, etched coils have perfectly repeatable geometry — so resonance tuning, and therefore read distance, is identical from the first card to the hundred-thousandth.
Why does bonding PET to PVC need a special film?
The two plastics have incompatible surface chemistries, and ordinary card adhesives let go — especially in humidity. The dip-coated bonding film carries an adhesive developed for exactly this pairing, holding > 7 N/cm when new and > 3.5 N/cm even after damp-heat ageing tests.
Does the guest ever see or feel the inlay?
Never. The inlay laminates dead-centre in the card stack, and the finished 760 μm body shows no witness lines. Its only visible evidence is behaviour: the card reads instantly, flat or at an angle, year after year.
Is this the same technology as metro tickets?
Yes — single-journey transit tickets are paper-faced cards built on exactly this etched-antenna construction, proven across billions of issued tickets. Hotel key cards inherit a supply chain that transit systems already stress-tested at world scale.
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