As with all high-volume, low-cost technologies, a certain percentage of NFC tags do not work and are considered bad. If a tag is bad it means the NFC tag cannot be read from or written to by any device. A smaller percentage of NFC tags may not work well. Poor performing NFC tags should generally be considered bad also. The customer should be aware that bad NFC tags are expected and plan accordingly. There are several ways to detect bad NFC tags. The NFC encoding strategy has implications to dealing with bad NFC tags.
The industry standard for quantity of bad tags is 1%; meaning that on a roll of 1,000 tags, 10 of them won’t work. Bad tags can occur in groups or randomly throughout the roll/package. In practice, the percentage of bad tags is often much lower than 1%. The ratio for bad NFC tags that GoToTags sells through the GoToTags Store is more often around 0.2%. If more than 1% bad tags are received in an order, there is an issue and the supplier should be contacted.
The most common cause for an NFC tag being bad is a broken bridge between the antenna and the NFC chip. This can happen for several reasons and can occur at any point from manufacturing, through production and to delivery. Common causes for broken NFC tags include:
- Bad weld join during the flip-chip process (excess heat, poor positioning)
- Bending the NFC tag to an extent that it physically breaks the bridge
- Crushing the NFC chip
- Breaking the antenna due to cutting or crushing
- Large electrostatic charge which short-circuits the NFC chip