Radio frequency identification tag on a single layer substrate

• US 6,424,263 B1
• Filed: 12/01/2000
• Issued: 07/23/2002
• Est. Priority Date: 12/01/2000
• Status: Active Grant

• Current Assignee: Microchip Technology Incorporated
• Original Assignee: Microchip Technology Incorporated
• Inventors: Lee, Youbok, Furey, Lee, St. Amand, Roger
• Primary Examiner(s): TWEEL JR, JOHN ALEXANDER
• Application Number:
  US09/728,217
• Publication Number:
  US 20020067266A1
• Time in Patent Office: 599 Days
• Field of Search: 340/572.7, 340/572.8, 340/572.5, 340/551, 340/10.34, 343/872, 343/873
• US Class Current: 340/572.7
• 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 19/07749 the record carrier being capable of non-contact communication, e.g. constructional details of the antenna of a non-contact smart card
• CPC Class Codes: G06K 19/0775 arrangements for connecting the integrated circuit to the antenna
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2924/00014 the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details
• CPC Class Codes: H01L 2924/01079 Gold [Au]
• CPC Class Codes: H01L 2924/19041 being a capacitor

Abstract

A radio frequency identification (RFID) tag on a single layer substrate comprises a semiconductor integrated circuit RFID tag device and antenna circuit. A connection jumper may be used to bridge over the antenna circuit coil turns. The RFID tag device is located on the same side as an inductor coil and capacitor which forms a parallel resonant antenna circuit. The inductor coil has an inner end and an outer end. The inner or outer end may be connected directly to the RFID tag device and the outer or inner end be may connected to the RFID tag device with a jumper over the inductor coil turns, or the RFID tag device may bridge the inductor coil turns when being connected to both the inner and outer ends. An encapsulation (glop top) may be used to seal the RFID tag device and jumper, and an insulated coating may be used to cover the entire surface of the substrate to create an inexpensive “chip-on-tag.” The encapsulation may be epoxy, plastic or any protective material known to one of ordinary skill in the art of electronic circuit encapsulation. The insulated coating may be of any type suitable for the application of use of the RFID tag.

Claims

1. A radio frequency identification (RFID) tag, comprising:

a substrate that is electrically insulated and transparent to radio frequency signals, said substrate having a surface;

an inductor coil on the surface of said substrate, said inductor coil having an outer end and an inner end;

a RFID tag device positioned over a portion of said inductor coil on the surface of said substrate, wherein said RFID tag device connects to the inner and outer ends of said inductor coil.

2. The RFID tag of claim 1, further comprising a conductive trace through said RFID tag device, wherein said conductive trace is adapted for connecting a capacitor to said inductor coil.

3. The RFID tag of claim 2, further comprising a comprising a capacitor located on the surface of said substrate and connected to said inductor coil.

4. The RFID tag of claim 3, wherein the capacitor is connected in parallel with said inductor coil.

5. The RFID tag of claim 3, wherein the capacitor is connected in series with said inductor coil.

6. The RFID tag of claim 1, wherein said inductor coil forms a resonant circuit antenna with an internal capacitor of said RFID tag device.

7. The RFID tag of claim 6, wherein said inductor coil and the internal capacitor form a parallel resonant circuit antenna.

8. The RFID tag of claim 1, wherein said RFID tag device is a flipchip having solder bump connections which are adapted to connect to the inner and outer ends of said inductor coil.

9. The RFID tag of claim 1, wherein said RFID tag device connects to the inner and outer ends of said inductor coil with bond wires.

10. The RFID tag of claim 1, wherein said inductor coil turns have a substantially constant width.

11. The RFID tag of claim 10, wherein said inductor coil turns have a low resistance and a high quality factor (Q).

12. The RFID tag of claim 1, further comprising an electrically insulating layer between said RFID tag device and the portion of said inductor coil.

13. The RFID tag of claim 12, wherein the electrically insulating layer is selected from the group consisting of mylar, mica, plastic, teflon, kapton and polyimide.

14. The RFID tag of claim 12, wherein the electrically insulating layer is attached to the portion of said inductor coil and said RFID tag device.

15. A method of fabricating an inexpensive radio frequency identification (RFID) tag, said method comprising the steps of:

providing a substrate that is electrically insulated and transparent to radio frequency signals, wherein said substrate has a surface;

forming an inductor coil on the surface of said substrate, said inductor coil having an outer end and an inner end;

disposing a RFID tag device over a portion of said inductor coil on the surface of said substrate; and

connecting said RFID tag device to the inner and outer ends of said inductor coil.

16. The method of claim 15, further comprising the step of providing a conductive trace through said RFID tag device, wherein said conductive trace is adapted for connecting a capacitor to said inductor coil.

17. The method of claim 16, further comprising the steps of locating a capacitor on the surface of said substrate and connecting said capacitor to said inductor coil.

18. The method of claim 17, wherein the capacitor is connected in parallel with said inductor coil.

19. The method of claim 17, wherein the capacitor is connected in series with said inductor coil.

20. The method of claim 15, further comprising the steps of providing an internal capacitor of said RFID tag device and connecting said internal capacitor to said inductor coil to form a resonant circuit antenna.

21. The method of claim 20, wherein said inductor coil and the internal capacitor form a parallel resonant circuit antenna.

22. The method of claim 15, wherein said RFID tag device is a flipchip having solder bump connections which are adapted for connecting to the inner and outer ends of said inductor coil.

23. The method of claim 15, further comprising the steps of connecting said RFID tag device to the inner and outer ends of said inductor coil with bond wires.

24. The method of claim 15, wherein said inductor coil turns have a substantially constant width.

25. The method of claim 24, wherein said inductor coil turns have a low resistance and a high quality factor (Q).