Structures and assembly methods for radio-frequency-identification modules

• US 20020044057A1
• Filed: 08/03/2001
• Published: 04/18/2002
• Est. Priority Date: 08/04/2000
• Status: Active Grant

• Current Assignee: HEI, Inc.
• Original Assignee: HEI, Inc.
• Inventors: Zirbes, Glen
• Granted Patent: US 6,696,952 B2
• Time in Patent Office: Days
• US Class Current: 340/572.1
• CPC Class Codes: G06K 19/041 Constructional details G06K19/06 takes precedence
• 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

Abstract

Radio-frequency identification (RFID) devices are used in a variety of applications to facilitate the identification and tracking of people, objects, and animals. One problem with RFID devices or tags concerns manufacturing cost. Specifically, some tag designs use an integrated-circuit chip requiring three external connections, instead of two as do many other designs. Accordingly, the present inventor devised a unique RFID module which uses a three-terminal integrated circuit and two capacitors, but only requires two external leads. One exemplary embodiment of the module includes two external terminals for connection to an antenna coil and an internal terminal for connection to a center-tap of a dual (center-tapped) capacitor. Other aspects of the invention include subcomponents of the module and methods of tag assembly using the module.

Claims

1. A method of assembling a radio-frequency identification (RFID) module, the method comprising:

providing a lead frame having first, second, and third contact regions and first and second recessed regions;

attaching an RFID chip to the first recessed region of the lead frame, with the RFID chip having first, second, and third contact regions;

attaching a separate capacitor chip to the second recessed region of the lead frame, with the separate capacitor chip including an integrated silicon capacitor having first and second end contacts and a tap;

electrically coupling the first end contact of the capacitor to the first contact region;

electrically coupling the second end contact of the capacitor to the third contact region;

electrically coupling the tap of the capacitor to the second contact region;

.

electrically coupling the first contact region of the RFID chip to the second contact region of the lead frame;

electrically coupling the second contact region of the RFID chip to the first contact region of the lead frame;

electrically coupling the third contact region of the RFID chip to the third contact region of the lead frame;

encapsulating at least partially the lead frame, the RFID chip, and the capacitor chip in an insulative material.

2. The method of claim 1, wherein the second contact region of the lead frame is between the first and third contact regions of the lead frame.

3. The method of claim 1, wherein the second contact region of the lead frame is between the first and second recessed regions.

4. The method of claim 1, wherein the lead frame comprises silver-plated copper metal.

5. The method of claim 1, wherein electrically coupling the first end contact of the capacitor to the first contact region, comprises forming a wire-bond connection or forming an aluminum-edge bond.

6. The method of claim 1, wherein electrically coupling the first end contact of the capacitor to the first contact region, comprises forming a double-wire-bond connection.

7. The method of claim 1, wherein encapsulating at least partially the lead frame, the RFID chip, and the capacitor chip in an insulative material comprises:

transfer molding using semiconductor transfer molding compound;

or

using an epoxy globing technique.

8. A method of making a radio-frequency-identification assembly, the method comprising:

providing an RFID module assembled according to claim 1;

providing a substrate having an antenna coil and a pair of connection regions electrically coupled to the antenna coil; and

electrically coupling the first and third contact regions of the lead frame to the pair of connection regions.

9. A lead frame for use in making a radio-frequency-identification module, the lead frame including:

first and second recessed regions for receiving first and second chips; and

at least three contact pads, with at least two of the pads for connection to components external to the module.

10. A lead frame for use in making a radio-frequency-identification module, the lead frame including:

a first conductive structure having a first body portion and a first extended portion, with the first extended portion for extension outside the module and connection to an antenna coil;

a second conductive structure having a second body portion and a second extended portion, with the second extended portion for extension outside the module and connection to the antenna coil; and

a third conductive structure completely separated from the first and second conductive structures and for connection to one or more contact pads inside the module.

11. The lead frame of claim 10, wherein the first conductive structure includes a recessed region for receiving an integrated-circuit chip.

12. The lead frame of claim 10, wherein the first conductive structure is between the first and second conductive structures.

14. The method of claim 13, wherein forming the first and the second recessed region comprises etching first and second corresponding portions of the layer of metal.

15. The method of claim 13, further comprising silver plating at least a portion of each of the three contact structures.

17. The module of claim 16, further comprising:

an insulative housing enclosing the first and second electrically connected chips.

18. The module of claim 16, wherein the first chip comprises a wireless-communications circuit and a memory.

19. The module of claim 16, wherein the two capacitors define a center-tapped capacitor.

13. A method of making a lead frame for a radio-frequency identification module, the method comprising:

forming at least a first and a second recessed region in a layer of metal; and

forming the layer of metal into at least three contact structures, with at least one of the structures positioned between the first and second recessed regions.

16. A radio-frequency-identification module comprising:

first and second electrically connected chips, with one of the chips including an external terminal and at least two capacitors, with each of the capacitors coupled to the external terminal; and

first and second external leads electrically coupled to the first and second chips, with the external leads for connection to an antenna coil.

20. A radio-frequency-identification module comprising:

a lead frame having at least first, second, and third separate contact regions, with the first and second contact regions for connection to an antenna coil;

an RFID chip fixed relative to the first contact region;

a capacitor chip fixed relative to the second contact region and having at least first, second, and third terminals;

a first electrical connection between the first terminal and the first contact region;

a second electrical connection between the second terminal and the second contact region; and

a third electrical connection between the third terminal and the the third contact region.

21. The module of claim 20, wherein the RFID chip and the capacitor chip are attached respectively to the first and second contact regions.

22. The module of claim 20, wherein the capacitor chip includes a center-tapped capacitor.

23. An assembly comprising:

an antenna coil having first and second conductive portions; and

the module of claim 20, wherein the first and second contact regions are coupled respectively to the first and second conductive portions.