How do you put a tag inside a product package?
By deciding two things before anything else: what the pack is made of, and what is inside it. Metallised film, foil liners and liquid contents defeat a chip that would work perfectly on a plain carton, and none of them are obvious from a design brief.
What the pack is made of
Card and plain paper are transparent to the field, so a chip behind them reads normally.
Metallised film is not. A great deal of food, cosmetic and pharmaceutical packaging uses a metallised or foil laminated layer for barrier properties, and it behaves like a conductive sheet.
It also looks like ordinary printed film, so the constraint is invisible in a design and discovered on a production line.
Ask the converter for the structure of the laminate before choosing a position, and test on the actual material rather than on a mock up in card.
What is inside it
Liquids absorb the field. A chip on the far side of a full bottle or pouch reads far worse than the same chip on an empty one, which makes testing on empty packs misleading.
Metal contents cancel it outright: a can, a foil blister, a tin, a tube.
Dense powders and pastes sit in between and need testing rather than reasoning.
The practical rule is to test with the pack full and closed, in the state a customer meets it, since every other state is optimistic.
Surviving the production line
Packaging is converted at speed under heat, pressure and rollers, which is the combination that breaks the bond between chip and antenna.
An inlay applied by the converter as part of the web is the usual route at volume, and it is a process the converter has to qualify.
Filling adds its own stresses: heat sealing, capping pressure, pasteurisation.
So verification has to happen after filling rather than after application. A chip that survived converting and died at the sealer is a chip nobody counted.
Choosing the position
Away from the metallised area, away from the metal contents, and where a hand naturally holds the pack.
Consistent across the range, so a customer who learns where to tap one pack can tap the next.
Marked on the outside, because a chip inside a pack is invisible and unannounced.
And decided with a full pack in hand rather than on a flat artwork, since the folded, filled object is the only version that matters.
Frequently asked questions
Does foil packaging block NFC?
Metallised and foil laminated layers behave like conductive sheets and stop it. Much barrier packaging uses them and it is not visible in the design.
Can a tag work on a bottle of liquid?
On the near side, sometimes. Liquid absorbs the field, so test with the bottle full and closed rather than empty.
Who applies the tag at volume?
Usually the packaging converter, as an inlay in the web. It is a process they have to qualify rather than an addition you make afterwards.
When should the tags be verified?
After filling and sealing, not after application. Heat sealing and capping break chips that survived converting.