Bad NFC tags are a reality of NFC projects and should be be expected and planned for accordingly. The method for detecting bad NFC tags depends on the type of product, manufacturing processes and user experience of the project.
The only way to detect bad NFC tags is to test each NFC tag to ensure it functions. If the NFC tag cannot be read, then it should be considered bad and appropriately dealt with. Small quantities of NFC tags can be tested by manually using an NFC enabled mobile device and an app such as the GoToTags Android App or GoToTags iOS App. For larger quantities of NFC tags, setting up a testing station using the GoToTags Windows App and an NFC reader might be more appropriate. Custom designed software and hardware solutions may need to be developed for large manufacturing systems.
When to Test
NFC tags can be damaged at any point in the supply chain and manufacturing process. It is not enough to test the tags once and assume they will always work. The more that the NFC tags are handled and used in equipment, the more likely tags will be subsequently damaged. To achieve the lowest % of bad tags, the NFC tags should be tested when first received and just before final placement/embedding of the NFC tag into/onto a more expensive product. The goal should be early detection of bad NFC tags to prevent subsequent waste and a final check to ensure the manufacturing process has not damaged a previously working tag. In projects where the NFC tag is being manually placed for deployment, the NFC tag should be tested at that time to ensure functionality.
How Much Testing
The recommended degree of NFC tag testing depends on how important a functioning NFC tag is in the project. Extensive testing may be expensive.
The easiest and cheapest solution is to do nothing and let the bad NFC tag be deployed. This may be appropriate for projects that do not expect a high level of interaction or the “cost” of not having the tag work is low for the consumer.
For other projects, the “cost” of the NFC tag not working is very high and everything possible should be done to detect bad NFC tags and ensure they are not deployed. This additional testing comes with additional cost and complexity.
What to Do
What is done when a bad NFC tag is found depends on several factors including the type of product, the manufacturing equipment and the desired user experience.
Certain roll-based products such as wet NFC inlays and NFC stickers can be tested during the application process, just after they have been peeled off the roll and before they have been applied to a product. Products such as dry NFC inlays come in one long strip and cannot be individually removed. This type of product must be tested at the point the product is cut from the roll. One option in this case is to visually mark the bad NFC tags with bright ink for subsequent optical detection.
NFC tags that are packaged individually such as NFC tokens and NFC cards can also be physically removed from the group of NFC tags; this is sometimes done with a burst of compressed air.