Radio frequency identification system

• US 6,100,804 A
• Filed: 10/29/1998
• Issued: 08/08/2000
• Est. Priority Date: 10/29/1998
• Status: Expired due to Term

• Current Assignee: Intermec IP Corporation (Honeywell International Inc.)
• Original Assignee: Intermec IP Corporation (Honeywell International Inc.)
• Inventors: Brady, Michael J., Duan, Dah-Weih, Kodukula, Venkata S. R.
• Primary Examiner(s): Lee, Benjamin C.
• Application Number:
  US09/182,170
• Time in Patent Office: 649 Days
• Field of Search: 340/572.1, 340/572.7, 340/572.8, 342/42, 342/44, 342/51, 343/872, 343/873, 257/787, 257/678, 257/679, 257/688
• US Class Current: 340/572.7
• CPC Class Codes: A01K 11/006 Automatic identification systems for animals, e.g. electronic devices, transponders for animals identification systems for access to feeding pens A01K1/0209; ear tags with electronic identification means A01K11/004
• 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: H01L 2224/0401 Bonding areas specifically adapted for bump connectors, e.g. under bump metallisation [UBM]
• CPC Class Codes: H01L 2224/16 of an individual bump connector
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/48227 connecting the wire to a bond pad of the item
• 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 2924/0102 Calcium [Ca]
• CPC Class Codes: H01L 2924/01039 Yttrium [Y]
• CPC Class Codes: H01L 2924/01078 Platinum [Pt]
• CPC Class Codes: H01L 2924/01079 Gold [Au]
• CPC Class Codes: H01L 2924/01087 Francium [Fr]
• CPC Class Codes: H01L 2924/19041 being a capacitor
• CPC Class Codes: H01L 2924/30107 Inductance
• CPC Class Codes: H01L 2924/3011 Impedance
• CPC Class Codes: H01Q 1/38 formed by a conductive layer on an insulating support patch antennas H01Q9/0407; microstrip dipole antennas H01Q9/065; microstrip slot antennas H01Q13/106; transmission line microstrip antennas H01Q13/206; manufacturing reflecting surfaces using insulating material for supporting the reflecting surface H01Q15/142
• CPC Class Codes: H01Q 21/28 Combinations of substantially independent non-interacting antenna units or systems multiple beam H01Q25/00
• CPC Class Codes: H01Q 7/00 Loop antennas with a substantially uniform current distribution around the loop and having a directional radiation pattern in a plane perpendicular to the plane of the loop
• CPC Class Codes: H01Q 9/16 with feed intermediate between the extremities of the antenna, e.g. centre-fed dipole H01Q9/44 takes precedence
• CPC Class Codes: H01Q 9/26 with folded element or elements, the folded parts being spaced apart a small fraction of operating wavelength resonant loop antennas H01Q7/00

Abstract

A radio frequency identification system employing a thin, flexible electronic radio frequency identification (RFID) tag having an overall thickness not exceeding approximately 280 microns and the process for its manufacture is disclosed. The RFID tag includes an insulating, flexible substrate having an aperture formed therein for receiving an RFID circuit chip. An antenna forming an integral part of the substrate is electrically connected to circuit chip. A cured adhesive having a portion substantially parallel with the substrate encapsulates the circuit chip so that the chip is operably retained within the substrate aperture.

Claims

1. A thin flexible electronic radio frequency tag circuit comprising:

a. an insulating, flexible substrate having an aperture therein;

b. an antenna forming an integral part of said substrate;

c. a circuit chip having an antenna connector, said circuit chip being substantially and operably located within the aperture of said substrate;

d. a connector for electrically connecting said antenna to said chip antenna connector; and

e. an encapsulant having a flattened outer surface substantially parallel with said substrate, said encapsulant operably retaining said circuit chip within said substrate.

2. A circuit, as in claim 1, wherein said encapsulant is milled after cure so as to reduce the overall cross-sectional thickness of said encapsulant and thereby providing a thin flexible electronic radio frequency tag having a cross-sectional profile thickness not unnecessarily increased by said encapsulant.

3. A circuit, as in claim 1, wherein said substrate has at least one dimension not exceeding 200 microns.

4. A circuit, as in claim 3, wherein said circuit chip has at least one dimension not exceeding 200 microns.

5. A circuit, as in claim 3, wherein said finished encapsulant does not increase the overall thickness of said substrate by more than 90 microns.

6. A circuit, as in claim 1, wherein said thin flexible electronic radio frequency tag has at least one dimension not exceeding 280 microns.

7. A circuit, as in claim 1, wherein said substrate is a fire-proof circuit board material.

8. A circuit, as in claim 1, wherein said substrate is an organic.

9. A circuit, as in claim 8, wherein said substrate is polyimide.

10. A circuit, as in claim 8, wherein said substrate is polyester.

11. A circuit, as in claim 1, wherein said connector for electrically connecting said antenna to said chip antenna connector is made using any of the bonding types including wire bonding, thermal compression, single point bonding, C4 bonding, and conductive adhesive.

12. A circuit, as in claim 1, wherein said connector for electrically connecting said antenna to said chip antenna connector is low profile wire bonding.

13. A circuit, as in claim 1, wherein said circuit is laminated on at least one side.

14. A circuit, as in claim 1, wherein said antenna is a resonant antenna and is one of the following structures including folded dipole, dipole, and loop.

15. A circuit, as in claim 14, further including an antenna impedance adjustment element.

16. A circuit, as in claim 15, wherein said antenna impedance adjustment element is an integral part of said substrate.

17. A circuit, as in claim 16, wherein said antenna impedance adjustment element is parasitic.

18. A circuit, as in claim 1, wherein a battery is affixed to the substrate in adjacent proximity to the antenna and chip and is connected by one or more battery connecting lines to two or more chip battery contacts wherein the battery contacts are coplanar with the antenna and connecting lines.

19. A circuit, as in claim 1, wherein said encapsulant encapsulates said chip within said aperture and said chip to said antenna and said chip connector.

20. A circuit, as in claim 19, wherein said encapsulant forms an at least somewhat flexible bond between said chip within said substrate aperture and said antenna and chip connector.

21. A circuit, as in claim 19, wherein said encapsulant forms at least one surface coplanar with at least one surface of said substrate.

22. A thin flexible electronic radio frequency tag circuit comprising:

a. an insulating, flexible substrate having an aperture therein;

b. an antenna forming an integral part of said substrate;

c. a circuit chip having a modulator circuit, a logic circuit, a memory circuit, and chip antenna connector, said circuit chip being substantially and operably located within the aperture of said substrate such that an annular space is formed between said chip and said substrate;

d. a connector for electrically connecting said antenna to said chip antenna connector; and

e. a fastener filling the annular space between said circuit chip and said substrate aperture for securing said circuit chip within said substrate aperture and forming a protective covering over said circuit chip, said antenna connector and at least some portion of said antenna, said fastener having a flattened cross-sectional profile including a bottom surface coplanar to the bottom surface of said substrate and a generally flat upper surface parallel to said bottom surface whereby the cross-sectional thickness of said circuit is not unnecessarily increased.

23. A circuit, as in claim 22, wherein said chip fastener does not substantially reduce the overall flexibility of said circuit about more than one axis.

24. A circuit, as in claim 22, wherein said thin flexible electronic radio frequency tag has at least one dimension not exceeding 280 microns.

25. A thin flexible electronic radio frequency tag circuit, comprising:

a. a substrate having an aperture thereon for receiving a radio frequency circuit chip;

b. a radio frequency circuit chip disposed within said substrate aperture;

c. an antenna disposed on said substrate and coupled to said radio frequency circuit chip; and

d. an encapsulant disposed on said substrate for encapsulating said radio frequency circuit chip, said encapsulant having a flattened outer surface substantially parallel with said substrate thereby providing a reduced thickness to allow the tag to pass through a printer without causing damage to said tag or said printer.

26. A circuit, as in claim 25, wherein said encapsulant is milled after cure so as to reduce the overall cross-sectional thickness of said encapsulant and thereby providing a thin flexible electronic radio frequency tag having a cross-sectional profile thickness not unnecessarily increased by said encapsulant.

27. A circuit, as in claim 26, wherein said finished encapsulant does not increase the overall thickness of said substrate by more than 90 microns.

28. A circuit, as in claim 25, wherein said substrate has at least one dimension not exceeding 200 microns.

29. A circuit, as in claim 28, wherein said circuit chip has at least one dimension not exceeding 200 microns.

30. A circuit, as in claim 25, wherein said thin flexible electronic radio frequency tag has at least one dimension not exceeding 280 microns.

31. A circuit, as in claim 25, wherein said substrate is a fire-proof circuit board material.

32. A circuit, as in claim 25, wherein said substrate is an organic.

33. A circuit, as in claim 32, wherein said substrate is polyimide.

34. A circuit, as in claim 32, wherein said substrate is polyester.

35. A circuit, as in claim 25, wherein said antenna is coupled to said chip using any of the bonding types including wire bonding, thermal compression, single point bonding, C4 bonding, and conductive adhesive.

36. A circuit, as in claim 25, wherein said antenna is coupled to said chip using low profile wire bonding.

37. A circuit, as in claim 25, wherein said circuit is laminated on at least one side.

38. A circuit, as in claim 25, wherein said antenna is a resonant antenna and is one of the following structures including folded dipole, dipole, and loop.

39. A circuit, as in claim 38, further including an antenna impedance adjustment element.

40. A circuit, as in claim 39, wherein said antenna impedance adjustment element is an integral part of said substrate.

41. A circuit, as in claim 40, wherein said antenna impedance adjustment element is parasitic.

42. A circuit, as in claim 41, wherein said encapsulant forms an at least somewhat flexible bond between said chip within said substrate aperture and said antenna and chip connector.

43. A circuit, as in claim 39, wherein said encapsulant forms at least one surface coplanar with at least one surface of said substrate.

44. A circuit, as in claim 25, wherein a battery is affixed to the substrate in adjacent proximity to the antenna and chip and is connected by one or more battery connecting lines to two or more chip battery contacts wherein the battery contacts are coplanar with the antenna and connecting lines.

45. A circuit, as in claim 25, wherein said encapsulant encapsulates said chip within said aperture and said chip to said antenna and said chip connector.