The most important parts in the NFC transponder are the NFC chip and the antenna. Depending on the applications, the two are built in different kinds of housings.
A NFC sticker or NFC label contains the chip and antenna between thin paper or plastic layers. When applied on metallic surfaces, the NFC sticker needs an additional protective layer, otherwise it does not work. This layer is made from ferritic material and it is called the ‘on-metal or anti-metal layer.’
The most common NFC chip for stickers – NTAG chips
The most commonly used NFC chip for NFC stickers is NTAG213 which supports the protocol ISO/IEC 14443 Type A. It has a seven byte-long UID (the Unique ID encoded by the chip manufacturer) and an EEPROM memory in which a user can store up to 144 bytes of data that equals a 136 character-long URL address.
The memory can be set as ‘read-only,’ and can therefore be locked against future changes.
If the NFC sticker contains the URL address, most NFC devices will automatically open an URL with their default internet browser when scanned. When writing custom data to a NFC chip, you may use a custom key and the content will be hidden from non-authorized users.
The chip ID is always easily readable with many NFC applications and is visible to the public. The ID is usually used as an identifier which connects the user to the other information inside the application database.
The NTAG213 chips are typically used for:
- Marketing applications (URL links, video links, navigation to destination address, etc.)
- Person or product identification (links to websites, YouTube, social media)
- Product presentation (URL links)
- Bluetooth pairing, Wi-Fi configuration, and more.
The memory size of NTAG213 chip is not enough for all the content of digital business card. For this application, we suggest using the NTAG215 with 504 byes of EEPROM memory or the NTAG216 with 888 bytes of EEPROM memory. The NTAG chips are made by NXP Semiconductors. The data retention time for these chips is 10 years.
Mifare Desfire® NFC chips
For NFC applications which require even larger EEPROM memory and additional layers of security, we suggest using the chips Mifare DESFire® with EEPROM size 2k, 4k, or 8k bytes. In 2020, the manufacturer added to their DESFire family a fourth version of the chip, called ‘EV3’ which have some new features, but it is backward compatible with previous versions called ‘EV1’ and ‘EV2.’
Desfire chips use a 3DES or AES hardware cryptographic engine for confidentiality and integrity protection of the transmission data. They have a 7 byte-long UID, and the data retention time for these chips is 25 years. These chips are made by the same manufacturer as NTAG chips and they are more expensive.
Mifare Desfire® chips are typically used for:
- Secure access control
- Public transportation
- Cashless vending
ICODE® NFC chips
The third kind of NFC chips we often use are ICODE® chips which support the protocol ISO/IEC 15693 (NFC Forum Tag Type 5, ISO 18000-3M1) which in turn supports bigger reading distances (up to 1.5 m with the right equipment), it has an 8 byte-long UID and a data retention time of 50 years.
We usually use the chip ICODE® SLIX or SLIX 2, but there are also ICODE DNA and other ICODE chips available.
ICODE® chips are typically used for:
- Asset Identification
- Consumable and accessory identification
NFC stickers for metallic surfaces
If you place a NFC sticker on a metallic surface, the magnetic fluxes of the reader will induce eddy currents within the metal and they will cause the NFC chip to malfunction.
If the printed NFC sticker is to be used on a metallic surface, we have to add a special layer made from ferritic material called the ‘on-metal or anti-metal layer,’ which redirects the magnetic fluxes and allows the chips to work. You have to be aware that the metal affects the reader as well, and so some readers work better in this condition than others.
Adhesive for NFC stickers
For regular short-term NFC applications, we use a regular inorganic adhesive foil, but when planning a long-term use, we recommend using high-quality 3M adhesives.
One of the 3M adhesive we use is the 467MP 200MP, and it is highly viscous, resistant to high temperature and humidity, and can maintain high viscosity for a long time and at higher temperatures.
The dimensions of NFC Stickers
NFC stickers can come in a variety of sizes. Usually, the sticker dimension is adopted to the defined antenna sizes. We have the most experience with stickers ranging in size from 19x12 mm to 76x45 mm.
For stickers smaller than 20x20 mm, the reading distance is almost to the touch. The smaller stickers cannot be read with all NFC devices. Some devices are capable of reading small NFC transponders with diameter like 15 mm, other not. Our biggest NFC sticker has an antenna dimension 76x45 mm and the reading distance is approximately 5 cm. Bigger stickers are easier to use than smaller stickers because they contain larger antenna and the NFC signal covers a larger radius. Stickers with a larger antenna than 76 x 45 mm have proven to be unreliable in practice, as they work poorly with some mobile phones and other readers with a smaller antenna. So, the size of an antenna has to be between 20x20 mm and 76x45 mm. The most popular dimension for NFC sticker is 25 mm and contains a 23 mm antenna.
The thinnest NFC sticker is transparent and has an antenna and an NFC chip applied to a thin plastic base. They are called ‘NFC wet inlays.’ White labels usually have at least two layers, one with an antenna and chip, and a paper or plastic layer on top. NFC labels intended for use on a metal base contain an additional layer of ferrite material and are already thicker (thickness approx. 0.3 mm). If you need very robust NFC stickers, we use several layers of thin PVC. After the heat-treated lamination process, all layers act as a whole and they can be as thick as a bank card (0.85 mm) or even more.
The typical operating temperature range for NFC stickers is -10° C to 85° C. There are also special NFC stickers for demanding temperature conditions which are made of Polyamide and are suitable for use from -40° C to 200° C.
Printed NFC stickers with offset printing technology
Our printed NFC stickers have usually on top a white PET foil, which is printed with color logos or background artwork. They can also contain variable data like serial numbers, chip ID numbers, etc. For a color print, we usually use offset digital printing with CMYK colors and combine the process with silk screen printing when there is a need for Pantone colors or metallic effects (golden colors, silver, glitter, etc.). A printed NFC sticker can contain an additional transparent layer which protects the artwork form scratching and wearing.
The typical printed NFC sticker for on-metal application contains the following layers:
1. A clear protective layer,
2. A layer with color artwork,
3. A layer with a NFC chip and antenna,
4. A layer with on-metal protection,
5. A layer with adhesive.
How to choose the most suitable NFC sticker for your application?
When selecting the best NFC chip, the client should consider the following factors:
1. What is the NFC application? Do you require a massive amount of NFC stickers for short period of time, or small amount of NFC stickers that need to work in a harsh environment for a long time?
2. What kind of a NFC chip do you require? Are low-cost chips with smaller memory ok or do you require more memory? How much data do you wish to write on the chip? What level of security is required?
3. Where will the sticker be placed? What is the desired tag size?
4. Will you place it on a metallic surface or very close to other electronics? Do you need an additional on-metal, protective layer?
5. Will it be used indoors or outdoors? Will it have exposure to high/low temperatures, moisture, UV light rays, strength of adhesive, etc.
6. What is the required reading distance? For longer reading distances than a couple centimeters, there are more appropriate kinds of chips – like UHF chips.
7. What kind of design would you like to be printed on your tags? Do all tags have same design or do they require custom variables such as serial numbers, chip UID, QR codes, or barcodes?
8. What quantity of stickers do you need? Smaller quantities can be made manually and you may cover a thin transparent NFC sticker with some other already-made sticker or label.
Which software to use for encoding NFC stickers?
For encoding NFC stickers, you can use a mobile phone with a NFC and one of the many NFC applications like NXP Tag Writer, NFC Tools, etc. Until recently, these applications were available only for Android phones, but now you may do the encoding with iPhones and other devices as well.
When encoding a bigger number of NFC stickers, you may use the NFC readers ACR122U or ACR1252, and some third-party application like the GoToTags NFC Encoder.
For a quotation, please let us know what kind of NFC stickers you need, the quantity, the chip type, and other specifications and we will send you an offer.
If you need larger quantities send an email to email@example.com or call +38641 884 124 and we will be happy to help you.
If you are an integrator or reseller, we offer special discounts.