Method of making radio frequency identification tags

• US 6,820,314 B2
• Filed: 12/13/2002
• Issued: 11/23/2004
• Est. Priority Date: 05/19/1995
• Status: Expired due to Fees

• Current Assignee: IPC Unipost SC
• Original Assignee: International Post Corporation SC
• Inventors: Ferguson, Donald Harold, Paun, Mircea
• Primary Examiner(s): TRINH, MINH N
• Application Number:
  US10/318,544
• Publication Number:
  US 20030106204A1
• Time in Patent Office: 711 Days
• Field of Search: 29/254.2, 296/01, 296/021, 298/41, 174/250, 361/737, 361/749, 361/782, 361/783, 361/814, 343/895, 343/702, 340/572.4
• US Class Current: 29/25.42
• CPC Class Codes: G06K 19/04 characterised by the shape
• CPC Class Codes: G06K 19/0702 the arrangement including a battery
• 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 19/07749 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 19/07758 arrangements for adhering the record carrier to further objects or living beings, functioning as an identification tag
• CPC Class Codes: G06K 19/07779 the inductive antenna being a coil
• CPC Class Codes: G06K 19/07781 the coil being fabricated in a winding process
• CPC Class Codes: G06K 19/07783 the coil being planar
• CPC Class Codes: G08G 1/017 identifying vehicles G08G1/015, G08G1/054 take precedence
• CPC Class Codes: H05K 1/16 incorporating printed electric components, e.g. printed resistor, capacitor, inductor
• CPC Class Codes: H05K 1/165 incorporating printed inductors
• CPC Class Codes: Y10T 29/435 Solid dielectric type
• CPC Class Codes: Y10T 29/49018 with other electrical component
• CPC Class Codes: Y10T 29/4902 Electromagnet, transformer or inductor
• CPC Class Codes: Y10T 29/49146 with encapsulating, e.g., potting, etc.
• CPC Class Codes: Y10T 29/49155 Manufacturing circuit on or in base
• CPC Class Codes: Y10T 29/49169 Assembling electrical component directly to terminal or elongated conductor
• CPC Class Codes: Y10T 29/49171 with encapsulating

Abstract

A radio frequency identification tag is made with a printed antenna coil integrated on a flexible substrate, and an integrated circuit area of the substrate adjacent to the antenna coil for carrying circuit elements. The radio frequency identification tag is designed to be sufficiently robust to withstand the rigors of mail efficiency processing measurement applications. Robustness is accomplished by encapsulating a sensing circuit formed on the flexible substrate thereby forming a semi-rigid area on the substrate and leaving the antenna portion of the substrate flexible.

Claims

1. A method of making an identification tag, the method comprising:

providing a flexible substrate having an antenna portion and an integrated circuit portion;

forming an antenna on the antenna portion of said substrate;

forming a sensing circuit on a laminate substrate and securing the laminate substrate to the integrated circuit portion of the flexible substrate;

forming a connection between said sensing circuit and said antenna on said substrate; and

encapsulating the sensing circuit to form a semi-rigid area on said substrate while said antenna portion remains flexible.

2. The method of making an identification tag according to claim 1 wherein the step of encapsulating the sensing circuit to form a semi-rigid area on said substrate includes:

applying an encapsulating material over said sensing circuit; and

curing said encapsulating material to form an encapsulation.

3. The method of making an identification tag according to claim 2, wherein the step of applying an encapsulating material over said sensing circuit includes the step of applying a UV adhesive over said sensing circuit, said UV adhesive having a limited degree of flexibility so that it will not crack or fracture under stress.

4. The method of making an identification tag according to claim 2, further comprising the step of forming an ink dam around said semi-rigid area to retain said encapsulating material within the semi-rigid area.

5. The method of making an identification tag according to claim 1, further comprising the step of applying a slip surface over said antenna portion and said integrated circuit portion of said flexible substrate.

6. The method of making an identification tag according to claim 5, wherein said slip surface comprises a protective polyester film.

7. The method of making an identification tag according to claim 5, wherein said slip surface comprises a polyester bag enclosing the entire identification tag.

8. The method of making an identification tag according to claim 1, wherein the step of forming an antenna on a first portion of said flexible substrate includes:

forming a first winding on a top side of said flexible substrate;

forming a second winding on a bottom side of said flexible substrate; and

forming a single plated hole between said first and second windings.

9. The method of making an identification tag according to claim 8, wherein the step of forming a second winding on a bottom side of said substrate includes offsetting the second winding from the first winding in order to minimize the parasitic capacitances between the first and second windings.

10. The method of making an identification tag according to claim 8, further comprising the step of cutting out an excess portion of said flexible substrate within the first and second windings.