NFC tag classification

One of the main application scenarios of NFC technology is that NFC mobile phones read and write NFC Tags. The "tag" mentioned here is actually just a general term. In actual applications, "NFC tags" are not just like stickers. According to different application scenarios, there can be many different external forms. Some are suitable for sticking on the surface of objects, some are suitable for embedding inside objects, and some are suitable for carrying around. This article will make a simple classification of tags based on the external form of NFC tags:

Tag category:

Dry inlay:

Wet inlay:

This is the simplest and most common form of tag. It should actually be a semi-finished product of label stickers. After the surface composite process, it is the final NFC tag. Its processing process is to first produce an etched aluminum antenna, then turn the chip upside down on the antenna, and fix it with conductive glue. Among them, dry inlay refers to the back of the label without adhesive, and wet inlay refers to the back of the label with adhesive. Wet inlay has all the functions of a label. The surface is transparent and the antenna coil can be directly seen. It is full of technology and can be pasted on the surface of the product or attached to the inside of the object. It is the best choice for pursuing cost-effectiveness in various project applications.

Ordinary label: This is the conventional form of NFC label, which is made of dry inlay or wet inlay and then composited on the surface. The surface material can be coated paper, PP synthetic paper or PET film. The surface pattern can be customized by the customer with exquisite printing. Such NFC Labels are generally attached to the outer surface of the object, and the user can scan directly. The label pattern can reflect the corporate culture and can also be a display of the company's image.

Fragile label: This is a special NFC label that has an anti-transfer effect. After it is attached to the surface of the object, it cannot be completely peeled off, otherwise the antenna will be damaged and the label will become invalid. This label is suitable for the field of commodity anti-counterfeiting, and the manufacturer does not want the genuine label to be peeled off and recycled. Anti-metal label: When you want to attach the label to the surface of a metal object, it must be an anti-metal label. Ordinary labels cannot work on metal surfaces, and a layer of absorbing material must be added between the label and the metal surface to isolate it. Therefore, the anti-metal label is to compound a layer of absorbing material on the back of the ordinary label. Here we need to remind you that adding absorbing materials to the back of ordinary labels will cause the resonant frequency of the labels to drop by about 2MHz. Therefore, when using absorbing materials, we should consider the change in label performance.

Printed labels:

This type of label antenna is directly printed on the substrate with conductive ink, such as A4 paper or packaging carton, and then the chip is turned upside down on the antenna. This type of label is suitable for anti-counterfeiting authentication of some documents, certificates, and commodities.

Glue labels:

This type of label has a layer of transparent soft glue on the surface, which protects the surface on the one hand and looks beautiful and suitable for personal use on the other hand.

Cards:

Standard cards:

This type of standard card is the most common and most common application form. Each of us must have several cards in our pockets, such as Access Control cards, meal cards, membership cards, bus cards, etc. Most of the chips in this type of application cards are S50 (M1) chips (see the next section for the specific relationship with NFC). Of course, with the popularization of NFC applications, the number of chips in this type of card using NFC standard chips has also increased.

The card making process is relatively mature. Generally, copper coils and COB are used to produce the intermediate material first, and then the PVC film is pressed up and down to form the card.

Special-shaped card:

The production process of special-shaped card is the same as that of standard card. Then the mold is made and cut according to the actual required shape. Standard cards and special-shaped cards can be backed with glue as needed, which is suitable for applications where the card is attached to a certain place. Glue card:

Similar to the glue label, this card adds a layer of transparent glue on the surface of the card, which looks beautiful and comfortable, and is suitable for high-end projects. Glue cards and special-shaped cards can also be punched and a lanyard can be added for easy carrying.

Module type:

Coil COB:

This form is also the simplest form of NFC tag and the lowest cost form. The antenna of this tag is directly wound with a copper coil, which can be large or small, and then the copper wire is directly welded on the COB. At present, these processes can all be automated, which is the only choice for low-cost tags. After processing these tags, they are encapsulated in key chains, buttons, cards or other items.

PCB:

This packaging form directly uses the circuit board to process the antenna, then installs the chip and binds it to the PCB, and drips black glue to fix it; or the chip is first packaged in the form of SOT and then mounted on the PCB. The entire processing technology is relatively mature, suitable for mass production, and is also the preferred implementation method for low-cost tags. This tag is suitable for integration in various electronic devices, used for Bluetooth pairing and information interaction with mobile phones. FPC:

The processing process is similar to PCB, and is suitable for occasions where the thickness of the finished product is required. FPC tags can be small in size, thin in thickness, and bendable. However, its production price will be higher.

The above tag types are classified from the perspective of the appearance of NFC tags. The user's final choice of which form should be comprehensively considered from the application scenario and processing cost. In the end, it is the tag chip inside that really determines the function of the tag. The subsequent part of this technical series will introduce the functional characteristics of various types of NFC tag chips from the perspective of chip application.