Production of radio frequency ID tags

• US 20060276987A1
• Filed: 06/03/2005
• Published: 12/07/2006
• Est. Priority Date: 06/03/2005
• Status: Active Grant

• Current Assignee: Tagent Corp.
• Original Assignee: Tagent Corp.
• Inventors: Lovoi, Paul A., Baron, Bernard, Bolander, Jarie G., Jarvis, Neil, Wunderlich, Forrest, Lee, Christopher J.
• Granted Patent: US 7,257,504 B2
• Time in Patent Office: Days
• US Class Current: 702/106
• CPC Class Codes: G06K 19/0723 the record carrier comprising an arrangement for non-contact communication, e.g. wireless communication circuits on transponder cards, non-contact smart cards or RFIDs
• CPC Class Codes: G06K 19/0726 the arrangement including a circuit for tuning the resonance frequency of an antenna on the record carrier
• CPC Class Codes: G06K 7/10059 transponder driven

Abstract

A radio frequency ID tag, very small in size and with an onboard antenna, is manufactured, tested and applied cost-efficiently. The transmit frequency for the tag is set during manufacture approximately, within a selected range, in a gross tuning step. The gross calibration is based on one or more measured characteristics of electronic componentry on wafers, and based on such measured characteristics, the chips can be grossly calibrated and parallel so that all tags will be within a fairly close tolerance of the target transmit frequency. A second tuning step fine tunes each tag by RF communication to set values of capacitance, resistance, etc., and this can be at the point of application of the tags. Other disclosed aspects of the invention also add to economy of producing the tag and reliability of the tags in service.

Claims

1. In the production of a radio frequency ID tag, of the type that receives and stores RF energy from an interrogator and uses that energy for the transmission of a responding signal, a method for imposing a randomized transmit time delay on each tag manufactured, such time delay being different for essentially every tag to avoid simultaneous responsive transmission by multiple tags, comprising:

including a non-volatile settable element in an integrated circuit of the tag,

with a computer in the manufacturing process, generating a pseudo-random number using an algorithm, such pseudo-random number essentially being different for each tag in a batch of tags for a particular application, and

placing such a pseudo-random number in the non-volatile element of each such tag, such number controlling the transmit time delay for responding transmission of each tag,

whereby no random number generator is needed onboard the tag.

2. The method of claim 1, wherein the non-volatile settable element comprises non-volatile RAM in the integrated circuit of the tag.

3. The method of claim 2, wherein the integrated circuit includes a variable capacitor, and the step of placing the pseudo-random number includes using bits from the non-volatile RAM to set a value of the variable capacitor on each tag.

4. The method of claim 1, wherein the non-volatile element is a bank of fuses.

5. In the production of an RF ID tag that receives and stores energy from an interrogator signal and sends a responsive signal on a transmit frequency back to the interrogator, a method for efficiently tuning and assuring accuracy of the tag'"'"'s transmit frequency in responding to an interrogator, comprising:

in manufacture of a series of tags on a wafer, only roughly setting the transmit frequency to a gross frequency range for all tags, by measuring a characteristic of a circuit component in the tag that affects transmit frequency and roughly tuning based on this characteristic in a testing phase of manufacture,

at the point of application of the tags to products or product containers, fine tuning each tag'"'"'s transmit frequency over the air by sending an interrogating signal within the gross frequency range to the tag and detecting a response from the tag, measuring the frequency of the response, determining a frequency adjustment amount for each tag, and sending a further signal within the gross frequency range to each tag to set bits in a non-volatile element of the tag circuitry to adjust the tag substantially to the desired tag transmit frequency, and

applying a plurality of the tags to products or containers, at the point of application.

6. The method of claim 5, including, after fine tuning of a tag substantially to the desired tag transmit frequency, re-testing the tag over the air by sending a signal via the interrogator and measuring a responding signal transmitted from the tag, to determine whether the tag has been correctly tuned to the desired transmit frequency, and if not, again determining a frequency adjustment for the tag and sending a further signal to the tag to reset bits in the tag circuitry to achieve substantially the desired tag transmit frequency.

7. The method of claim 5, wherein bits set in the non-volatile element control adding or subtracting capacitance or resistance to obtain the correct frequency.

8. The method of claim 5, wherein the gross frequency range within which the tags on the wafer are roughly set is approximately within 10% of the desired tag transmit frequency.

9. The method of claim 5, wherein, at the point of application of the tags, if the interrogator detects a response from a tag indicating that the tag'"'"'s transmit frequency is more than 10% deviant from the desired transmit frequency, the tag is rejected as a failure and discarded.

10. The method of claim 5, wherein the step of fine tuning each tag'"'"'s transmit frequency comprises, at the point of application of the tags, selecting a tag transmit frequency in accordance with regional frequency requirements for RF ID tags at point of application, and, when determining the frequency adjustment amount, measuring the difference between the frequency of the tag'"'"'s response and collected regional frequency.

11. The method of claim 5, further including, after fine tuning of a tag, applying a serial number to the tag over the air.

12. The method of claim 11, wherein the serial number is transmitted to the tag via an RF link and stored in a non-volatile element.

13. The method of claim 5, further to applying each tag, testing for additional parameters in the integrated circuit of the tag, by over-the-air testing.

14. The method of claim 13, wherein the additional parameters include at least some of the parameters voltage, current, resistance and capacitance of circuit components.

15. The method of claim 13, wherein the additional testing is performed by test circuitry included in the tag integrated circuit, which tests the additional parameters onboard the chip using power from an interrogating RF signal from a tester, the integrated circuit including means for producing digital representations of values for the tested parameters and transmitting the digital representations over-the-air to the tester.

16. A method for producing and testing a multiplicity of integrated circuits, comprising:

forming a multiplicity of integrated circuit dice on a wafer,

forming a test die on the wafer and connecting the test die to all integrated circuit dice,

testing all integrated circuit dice by connecting a tester to the test die while all dice remain together on the wafer, and addressing each integrated circuit die via the test die by issuing commands to each die under test and receiving responses for each die relative to parameters of the integrated circuit to be tested, and

gathering test result information for the integrated circuit dice in the test die and the tester and using that information, discarding bad integrated circuit dice on trimming the integrated circuit dice from the wafer.

17. The method of claim 16, wherein the multiplicity of integrated circuit dice are connected in series to the test die, so that the test die addresses each integrated circuit die serially and sequentially.

18. The method of claim 17, wherein the test die enables each integrated circuit die serially, one by one, by shifting in a selection value down a shift register chain to the die to be tested. The selection value being unique for each die and only allowing the enabling of one die at a time.

19. The method of claim 16, wherein the test die enables all integrated circuit dice for testing simultaneously, and sends testing commands to all integrated circuit dice simultaneously, each integrated circuit die having a memory element and each die performing the desired tests and then storing the test results in the memory or register element, and including the test die'"'"'s then sequentially shifting an enable bit through each tested integrated circuit die sequentially to read status of that die, then the test die'"'"'s writing a memory element on the die under test to signify that each particular die was tested and whether the die passed or failed, for subsequent determination or to whether the tag is to be used.

20. The method of claim 16, wherein the integrated circuits comprise RF ID tags.

21. In the production of an RF ID tag that receives and stores energy from an interrogator signal and sends a responsive signal on a transmit frequency back to the interrogator, a method for efficiently tuning and assuring accuracy of the tag'"'"'s transmit frequency in responding to the interrogator, comprising:

(a) for an initial period of production of RF ID tags, as each of many series of tags is produced on a wafer, roughly setting the transmit frequency of each tag to a gross frequency range for all tags, by measuring a characteristic of a circuit component in the tag that affects transmit frequency and roughly tuning based on this characteristic in a testing phase of manufacture,

(b) at the point of application of the tags to products or product containers, fine tuning each tag'"'"'s transmit frequency over the air by sending an interrogating signal within the gross frequency range to the tag and detecting a response from the tag, measuring the frequency of the response, determining a frequency adjustment amount for each tag, and sending a further signal within the gross frequency range to each tag to set bits in a non-volatile element of the tag circuitry to adjust the tag substantially to the desired tag transmit frequency, and

(c) applying a plurality of the tags to products or containers, at the point of application;

(d) for said initial period of production of the RF ID tags, monitoring the actual transmit frequency of each tag, or of a sampling of tags or selective wafer probing, as measured at the point of application prior to fine tuning, and using this information, making adjustments to the process of production of the tags on the wafers to improve the accuracy of the transmit frequency toward the desired tag transmit frequency, and continuing to adjust the process of production of the tags until a target percentage is achieved of tags having a transmit frequency within said gross frequency range before any rough tuning of tags during production as in step (a), and

(e) after said target percentage has been achieved in the initial period of production of the RF ID tags, discontinuing all testing of tags during the wafer production and relying on the integrated circuitry of the tags as produced, continuing to fine tune the transmit frequency of the tags at the point of application of the tags, with discarding of tags that fail to fine tune to the desired transmit frequency at the point of application.

22. The method of claim 21, further including, prior to applying each tag, testing for additional parameters in the integrated circuit in the tag, by over-the-air testing.

23. The method of claim 22, wherein said additional parameters include voltage, current, resistance or capacitance of circuit components of the tag.