Method for forming radio frequency antenna

• US 20030011523A1
• Filed: 09/11/2002
• Published: 01/16/2003
• Est. Priority Date: 03/13/2000
• Status: Active Grant

• Current Assignee: Robert R. Oberle
• Original Assignee: Robert R. Oberle
• Inventors: Oberle, Robert R.
• Granted Patent: US 6,933,892 B2
• Time in Patent Office: Days
• US Class Current: 343/700MS
• 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: H01Q 1/2225 used in active tags, i.e. provided with its own power source or in passive tags, i.e. deriving power from RF signal
• CPC Class Codes: H01Q 1/36 Structural form of radiating elements, e.g. cone, spiral, umbrella; Particular materials used therewithH01Q1/08, H01Q1/14 take precedence
• 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 9/27 Spiral antennas
• CPC Class Codes: H05K 1/095 for polymer thick films, i.e. having a permanent organic polymeric binder
• CPC Class Codes: H05K 1/165 incorporating printed inductors
• CPC Class Codes: H05K 2201/0347 Overplating, e.g. for reinforcing conductors or bumps; Plating over filled vias
• CPC Class Codes: H05K 2203/0191 Using tape or non-metallic foil in a process, e.g. during filling of a hole with conductive paste
• CPC Class Codes: H05K 2203/0769 Dissolving insulating materials, e.g. coatings, not used for developing resist after exposure
• CPC Class Codes: H05K 3/242 characterised by using temporary conductors on the printed circuit for electrically connecting areas which are to be electroplated
• CPC Class Codes: H05K 3/246 Reinforcing conductive paste, ink or powder patterns by other methods, e.g. by plating
• CPC Class Codes: Y10T 29/49016 Antenna or wave energy "plumbing" making

Abstract

A metalized circuit suitable for application as a radio frequency antenna is produced by forming an antenna coil pattern on a flexible substrate. The antenna coil pattern is formed using a conductive ink which is patterned on the substrate. The conductive ink is cured and an electrical-short layer is formed across the coils of the conductive ink pattern. An insulating layer is formed over top of the electrical-short layer, a metal layer electroplated on top of the conductive layer, and then the electrical-short layer is removed. The use of the electrical-short layer during the electroplating allows for the voltage at the different points on the conductive ink layer to be relatively similar, so that a uniform electroplate layer is formed on top of the conductive ink layer. This results in a better quality radio frequency antenna at a reduced cost.

Claims

9. An RF antenna comprising:

a substrate layer;

a seed layer on top of the substrate in an antenna coil pattern;

a conductive layer over portions of the antenna coil pattern, wherein the antenna has a removed short region across the coil pattern, the removed short region comprising a portion of the seed layer not covered by the conductive material or comprising a portion of the seed layer wherein the conductive layer is thinner than the remaining portions.

1. A method of forming an RF antenna, comprising:

providing a substrate layer;

forming a seed layer on top of the substrate in an antenna coil pattern;

forming an electrical-short layer across the coil pattern;

using the electrical-short layer to electroplate a conductive layer over at least part of the antenna coil pattern; and

removing the electrical-short layer.

2. The method of claim 1 wherein the seed layer comprises a conductive ink layer.

3. The method of claim 2 wherein the conductive ink layer is cured.

4. The method of claim 1 wherein a non-conductive layer is formed over top of the electrical-short layer before the electroplating step.

5. The method of claim 1 wherein the removing step comprises using a solvent to remove the electrical-short layer.

6. The method of claim 1 wherein the electrical-short layer is differentially removable from the seed layer.

7. The method of claim 1 wherein the substrate layer is flexible.

8. The method of claim 1 wherein the electrical-short layer comprises a line across one section of the coil pattern.

10. The RF antenna of claim 9 wherein the removed short region includes adjacent sections on the antenna coil pattern.

11. The RF antenna frequency antenna of claim 9 wherein the seed layer comprises a cured conductive ink layer.

12. The RF frequency antenna of claim 9 wherein the removed short region comprises a portion of the seed layer not covered by conductive material.

13. The method of claim 9 wherein the removed short region comprises a portion of the seed layer wherein the conductive layer is thinner than the remaining portions of the electroplated conductive layer.

14. The RF frequency antenna of claim 13 wherein the removed short region includes a single electroplated layer while the remaining portions of the conductive layer comprise two electroplated layers.

16. The method of claim 15 wherein the conductive foil material is attached to the substrate using a conductive adhesive.

17. The method of claim 15 further comprising the step of electroplating an electroplated conductive layer on top of the antenna coil pattern.

18. The method of claim 15 wherein the antenna coil pattern is such that there are two adjacent conductive pads not separated by loops of the antenna coil pattern.

19. The method of claim 18 wherein the conductive pads are adapted for connection to an integrated circuit device.

20. The method of claim 15 wherein the conductive ink layer is cured.

21. The method of claim 15, wherein the at least one hole comprises at least two holes.

22. The method of claim 15, further comprising forming a conductive layer on the first side of the substrate layer.

24. The method of claim 23 wherein the conductive foil material is attached to the substrate using a conductive adhesive.

25. The method of claim 23 wherein the connection between the circuit elements and the conductive foil is made with a conductive ink.

26. The method of claim 23 further comprising the step of electroplating an electroplated conductive layer on top of the antenna coil pattern.

27. The method of claim 23 wherein the antenna coil pattern is such that there are two adjacent conductive pads not separated by loops of the antenna coil pattern.

28. The method of claim 22 wherein the conductive pads are adapted for connection to an integrated circuit device.

15. A method of forming an RF antenna, comprising:

providing a substrate layer;

forming at least one hole in the substrate layer

on a first side of the substrate layer, attaching a conductive foil material such that the conductive foil covers one side of the at least one hole;

on a second side of the substrate layer, forming a conductive ink layer on top of the substrate in at least part of an antenna coil pattern, the conductive ink filling the at least one hole to form an electrical contact with the metal foil.

23. A method of forming an RF antenna, comprising:

providing a substrate layer;

on each side of the substrate forming the elements of a single circuit

forming one or more holes in the substrate layer;

on one or both sides of the substrate layer, attaching a conductive foil material such that the conductive foil substatially covers one or both sides of at least one of the holes,

forming an electrical interconnect through the at least one of the holes of the substrate, the electrical interconnect contacting the conductive foil layer and interconnecting circuit elements on both sides of the substrate.

28-1. The method of claim 22 wherein the conductive ink layer is cured.