What are NFC tags made of? What shapes do they have? What characteristics do they achieve and what parts are they made up of? You will learn all this in this section.
Construction of NFC tags
Every NFC tag consists of an NFC chip and an antenna, which is usually made of aluminium. These two basic components are attached to a thin layer of plastic so that everything holds together. In addition, the tag can be supplemented with further layers so that it better meets the final requirements for its placement.
How does an NFC tag work?
NFC tags are activated by bringing them close to an NFC device (for example a mobile phone, a reader). Data transfer works on the principle of transferring energy by means of magnetic induction. The active device creates an electromagnetic field around itself, from which the passive NFC tag is charged. The NFC tag uses this energy to send the stored data, which is again captured by the active device in close proximity.
Antenna
The antenna in most NFC tags is made of etched aluminium, and exceptionally also of copper. Copper is a more expensive material, but shows better conductivity, so it is used where aluminium might not be strong enough.
NFC antennas in fact have little in common with real antennas. Technically speaking, they are rather induction coils designed to be easily charged with energy when they are in close proximity to a source of an electromagnetic field. These antennas are constructed very precisely so that they resonate only at the required frequency (13.56 MHz), and as efficiently as possible.
The performance of the antenna does not depend on its thickness, but on its size (or diameter). That is why tags are available in the form of thin stickers without loss of reading distance. If there is a large electromagnetic field, the rule is that the larger the antenna, the better the data transfer. Mobile phones, however, do not produce too strong a field, so there is a limit to the size of the antenna. If we had too large an antenna and a weak electromagnetic field, it would rather be an obstacle that would, on the contrary, reduce performance (and reading distance).
Bonded joint
It is the joint between the microchip and the antenna and, at the same time, the Achilles heel of the entire NFC tag. It is the thing that breaks when you bend the tag too much, thereby rendering the whole thing useless.
Custom printing
If you wish to have your NFC tag printed with any pattern, it is necessary to order a sufficient quantity of these labels. In our range, however, we have ready-made designs of NFC labels, where the quantity does not matter and the price is not high.
Tag sizes
We offer NFC tags of various sizes and shapes. The size of the tag depends on the size of the antenna. It is therefore advisable to choose the tag according to the purpose it is to serve.
Ideal antenna size
Simply put, for use with mobile phones we recommend tags with dimensions of 29 mm or 38 mm (with an antenna size of 25 mm and 35 mm). Credit-card-sized antennas very rarely work better with mobile phones, and their price is higher. The reason is that the larger the antenna a tag has, the more energy it requires to charge the chip. Phones, however, do not produce that much "NFC energy", so in the end the reading distance would be significantly reduced.
For higher-power devices (readers) we can observe an increase in efficiency when using a larger antenna. But it always depends also on the size of the antenna in the given reading device.
Various options for the version of the tag
NFC tags can take various forms thanks to their various versions. The basis of every tag is the inlay, that is, the chip and antenna, both attached to a piece of thin plastic layer. The simplest version is the so-called dry inlay; somewhat more sophisticated is the sealed dry inlay and the wet inlay. These tag versions are not much used for ordinary needs, and that is why we do not keep them in stock in the e-shop either. On demand we are able to supply all versions.
Much better known and more used are NFC tags in the form of a sticker (NFC sticker), where you can choose between a clear (clear sticker) and a white (white sticker) finish. If you plan to place the tags on metal, you need to choose tags that are intended for this purpose. Such tags additionally have a special ferrite layer that shields the NFC tag from the substrate. They are produced in two different versions (classic and reverse). Our speciality is NFC magnets, which we produce to order with a minimum order volume of 500 pcs.
Take a look at the overview and graphic depiction of the versions described above.
Dry inlay
This is the basic type of tag that can be found on the market. It is made up of a chip, an antenna and only one thin layer of plastic. The antenna is not protected by anything on one side.
Sealed inlay
Unlike the dry inlay, in this case the antenna is protected on both sides by a thin layer of plastic (usually PET).
Wet inlay
In this case the antenna is protected on one side by thin plastic (PET), while on the other side it has only a thin adhesive layer. So that this type of tag can be stored well, it is supplied on a so-called transfer film (like classic stickers).
Clear NFC tag
In this version the antenna with the chip is placed between two transparent plastic (PET) layers, with an adhesive layer added on one side. These tags are supplied on a transfer film.
White NFC tag
This tag has the same version as the clear NFC tag, with one single difference – the plastic in which the antenna with the chip is sealed is not transparent, but white, which allows graphics to be printed on the tag as needed.
Printed NFC tag (NFC label)
There is more than one way to produce this type of tag. The simplest is to imagine a classic white NFC tag and add to it one layer that is glued on one side to the upper white plastic layer and on the other side has the print. The second option is, again, to imagine a classic white tag, where we replace the upper white layer with a printed layer that is additionally covered by a transparent film. The method of production depends on the number of pieces ordered.
NFC tag for metal - classic
Tags for metal must have a special construction so that interference with the underlying metal does not occur; the metal absorbs the electromagnetic field around the tag and thus significantly reduces its reading distance. Most often a special ferrite layer is used, which serves as shielding insulation. The classic version has this ferrite layer between the bottom plastic layer and the adhesive layer, and is made for the case where we stick the tag onto metal and want to read it from the front side.
NFC tag for metal – reverse
This type of tag was designed so that it can be stuck, for example, on the back of a poster that is then placed on a metal substrate. The ferrite layer is between the antenna and the upper plastic layer.
Magnetic NFC tag
This is an NFC tag for metal that additionally has a bottom layer of magnetic film, so it works like a magnet. If needed, one more upper layer with print can be added, creating a stylish gadget. For example, an advertising fridge magnet.
