Metal NFC business cards: how the chip actually gets inside

Metal blocks the signal a tap depends on. Every metal NFC card on the market is a workaround for that one fact, and the workaround you buy decides the weight, the finish, which side reads, and what it costs. Here are the five constructions, what each is good at, and which one we run.

Why metal kills a tap

NFC is not radio in the broadcast sense. It is two coils sharing a magnetic field. Your phone's reader coil pushes a 13.56 MHz alternating field; the card's antenna coil sits inside that field and picks up enough energy to wake the chip and answer. No battery, no transmitter — just induction, the same physics as a wireless charger.

Put a conductive sheet in that field and two things happen. First, the alternating field induces eddy currents in the metal — swirling loops of current that generate their own opposing field and cancel the reader's field almost completely on the far side. Second, the metal sits so close to the card's coil that it detunes it, dragging the resonant frequency off 13.56 MHz so even the energy that does arrive is poorly absorbed. A plain steel card with a stock chip stuck on it reads at zero range from either side. It is not a weak signal problem. It is a no-signal problem.

So every metal NFC card does one of two things: keeps the antenna away from the metal with a non-conductive layer, or puts a ferrite sheet between them. Ferrite is a magnetic ceramic with high permeability and low conductivity — it gives the field a path to flow through instead of into the steel, so the coil behind it can still resonate. That is the entire trick. The five constructions below are just different places to hide it.

Metal face bonded to a plastic backTHE HYBRID · MOST COMMON

A solid stainless (or brass, or anodised aluminium) plate roughly 0.4–0.5 mm thick, laminated to a thin PVC or PET layer that carries the chip and antenna. Total thickness lands around 0.8–0.9 mm — a hair thicker than a credit card. The chip and coil live entirely in the plastic layer, on the far side of the metal from where you tap, with a thin ferrite film between antenna and steel.

Solid metal with a milled pocketFULL METAL

Start with a solid blank — usually 0.8 mm stainless — and CNC-mill a shallow pocket into the back, leaving a thin floor. A ferrite-backed NFC inlay drops into the pocket and is sealed with epoxy or a flush cap, sanded level. Both faces are metal. The pocket is invisible if the cap is finished to match, or visible as a small panel if you let it be.

Metal core sandwiched in plasticMETAL-INFUSED

The inverse of the hybrid. A thin steel core sits in the middle, laminated between PVC print layers on both sides. The antenna lives in one of the outer plastic layers over a ferrite film; the core is often cut slightly smaller than the card so the antenna loop can run around its perimeter, or a section of the core is removed under the coil. The outside is 100% plastic — you see metal only as weight and, sometimes, a dark line at the edge.

Slot or window antennaCUT-THROUGH

Two related tricks. The first laser-cuts a window clean through the metal and fills it with a plastic insert carrying the chip — the field passes through the insert on both sides, so the card reads from either face. The second cuts a narrow slot from the coil position to the card edge; the interrupted metal can no longer sustain a closed eddy-current loop, and with careful tuning the plate itself becomes part of the antenna. The slot version is used in some premium payment cards.

On-metal stickerTHE RETROFIT

Take any metal card and stick an "on-metal" NFC tag on the back. These tags are a normal inlay with a ferrite sheet already laminated under the antenna, so they read on steel where a standard tag wouldn't. It works. It is also a sticker on a metal card.

Finishes: what each construction can carry

The construction decides which surfaces are metal and which are plastic, and those two surfaces print completely differently.

On the metal face: laser engraving (removes the top finish to reveal bare steel — bright on black, dark on brushed), chemical etching (recessed, can be colour-filled), PVD coating for the base colour (matte black, gold, rose gold, gunmetal, iridescent), and spot-colour silk screen — one to three PMS inks, opaque and saturated, which is what we recommend for brand colour on metal. Full-colour UV printing works on metal too but needs an opaque white ink underbase on dark or mirror surfaces or the colours go translucent and dull.

On a plastic face (the hybrid back, or both faces of a metal-infused card): UV inkjet in full colour, matte or gloss overlaminate. It prints like a good PVC card because it is one. You cannot engrave it, and it will never read as metal.

Two details that matter on every one of these: corners are radiused — 3 mm is standard on metal, because a square steel corner cuts pockets and people — and mixing a matte body with a mirror-polished element on the same card is one of the most dramatic things you can do with metal, far more than brushed alone.

Side by side

Range figures are typical phone-to-card distances for an NTAG213 inlay; they vary with phone model and antenna placement. Payment-grade contactless has stricter tolerances than a business card needs.

Which one we make, and why

We run the hybrid: a matte-black (or PVD gold, rose gold, silver, iridescent) metal face bonded to a UV-printed back, NTAG213 chip fully enclosed and invisible, 85.5 × 54 mm at about 0.84 mm thick, 3 mm corners. It is the one construction where the thing you hand someone is real metal, the tap is reliable, and the price is defensible for a run of 100 or 250 rather than a one-off.

The honest cost is the one-sided read. We tell every customer the same thing: the tap happens on the back. In practice people learn it in a day, and it has an upside — the metal face carries nothing but your mark and your name, which is the reason you wanted metal in the first place.

If you need both faces to read, ask us about the window construction. If you want metal on both faces and can live with a short tap, the milled pocket exists and we can quote it. If a supplier is selling you "metal cards" that print full colour on both sides for the price of plastic, you are looking at a metal core — fine product, wrong name. See the full range on the metal business cards hub.

Common questions

Why does my metal card only tap from the back?

Because the antenna is in the plastic layer behind the steel, and steel blocks the field. It's the hybrid construction — the most common one — working as designed.

Can the chip be reprogrammed later?

Yes, unless it was locked. NTAG213/215/216 chips are rewritable with any free NFC app; we only lock on request. The better setup is a link you control, so the destination changes without touching the chip.

NTAG213, 215 or 216?

Memory only — 144, 504 and 888 bytes. A URL fits in 213 with room to spare. You'd want 216 for a full vCard stored on-chip, which most people don't need because the URL does the work.

Will a metal card set off airport security or wipe my hotel key?

No and no. It's a passive tag with no battery; it does nothing until a reader powers it. Stacked directly against another NFC card it can make both hard to read, which is true of any two NFC cards.

Can you put NFC in a wood or plastic card?

Easily — neither blocks the field, so the inlay laminates straight in and reads from both sides. Metal is the only material that needs the engineering above.

See the products: NFC metal cards · NFC plastic cards