3 Important Things To Know For High-Temp RFID

Over the years, the use of RFID has expanded to cover many new applications and industries and with each new advance in range, speed and standardization, the technology becomes more widely accepted and cost effective. But one application need, especially for industrial RFID users has been there almost from the beginning. That is the use and survivability of RFID tags in high temperature applications. When I talk about high-temp RFID tags, it generally means temperatures above 120° C (248° F) to over 200° C (392° F) or higher. There are three important factors that you want to know for using RFID in these temperature conditions.

1. The maximum rated temperature of the RFID tag (transponder),
2. The exposure time at a specific temperature and,
3. The cooling time before the tag is read or written.

The bonding between the antenna coil or rod and the IC (many newer tags use a single IC which includes processor, transponder and memory) is the most vulnerable connection that can deteriorate when exposed to high heat. Depending on how the bond is created or the “solder” that connects them together, the bond will separate when exceeding the rated temperature, especially based on exposure time. Depending on the tag type, labels for example, temperature can also cause deterioration of the inlay material the IC and antenna are mounted to. To help communicate these limits for a tag, the manufacturer will typically publish multiple tag temperature per exposure time ratings to show ranges of possible use. The illustration below is a typical rating example for a high-temp tag.

This brings us to point number two, exposure time at temperature. Very few tags can sustain exposure to elevated temperatures, generally above 120° C for an infinite or even prolonged amount of time. The tag will typically have a rated exposure time in minutes versus temperature, at which time the tag must be allowed to cool to a rated sustained or as in many noted cases, “Storage” temperature in order to prevent damage to the IC’s memory, circuitry, or the antenna bonding. You must be very careful to look into the details of the operation or use of a high-temp rated tag to make sure that the temperatures you will expose it to versus time do not exceed these limits or you will most likely see premature failure or deterioration in operation.

The final point is cooling time before operation or reading and writing. All tags will have a temperature rating for what temperature it can be read or written to safely. This is typically noted as the “Operating” temperature. It is critical not to activate the tag for reading or writing before the tag falls within this temperature range. There are several reasons for this including again, IC damage and/or antenna bond damage. For example, if a tag is mounted to a pallet on a conveyor, the tag must be allowed to cool from the exit of an oven before it reaches the read/write head. This means the process must allow ether a dwell time or a long enough distance between the two operations so the tag can adequately cool. A recommendation here would be to try not to mount the tag directly to a metal surface or provide insulation between the metal and tag to prevent the residual heat from the metal causing secondary heating of the tag.

For your next track and trace application that involves high temperatures, you may be surprised to find that there is an RFID tag that will fit your needs (see Balluff’s at High Temp Tags), but just be aware that there are key factors you want to know about before jumping in. It’s also never a bad idea to test the tags you want to use in the process as a pilot to verify there survivability.


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