Method for forming radio frequency antenna

• US 6,476,775 B1
• Filed: 03/13/2000
• Issued: 11/05/2002
• Est. Priority Date: 03/13/2000
• Status: Expired due to Fees

• Current Assignee: RCD Technology Corporation
• Original Assignee: RCD Technology Corporation
• Inventors: Oberle, Robert R.
• Primary Examiner(s): Wong, Don
• Assistant Examiner(s): Dinh, Trinh Vo
• Application Number:
  US09/524,505
• Time in Patent Office: 967 Days
• Field of Search: H01/Q.136, 343/895, 343/873, 343/700.MS, 296/00, 361/737, 257/679, 235/488, 235/441, 235/492
• US Class Current: 343/895
• 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 reinforcing the conductive pattern H05K3/24
• 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

1. 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 of the conductive layer.

2. The RF antenna of claim 1 wherein the removed short region includes adjacent sections on the antenna coil pattern.

3. The RF antenna frequency antenna of claim 1 wherein the seed layer comprises a cured conductive ink layer.

4. The RF frequency antenna of claim 1 wherein the removed short region comprises a portion of the seed layer not covered by conductive material.

5. The RF frequency antenna of claim 1 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.

6. The RF frequency antenna of claim 5 wherein the removed short region includes a single electroplated layer while the remaining portions of the conductive layer comprise two electroplated layers.

7. 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.

8. The method of claim 7 wherein the seed layer comprises a conductive ink layer.

9. The method of claim 8 wherein the conductive ink layer is cured.

10. The method of claim 7 wherein a non-conductive layer is formed over top of the electrical-short layer before the electroplating step.

11. The method of claim 7 wherein the removing step comprises using a solvent to remove the electrical-short layer.

12. The method of claim 7 wherein the electrical-short layer is differentially removable from the seed layer.

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

14. The method of claim 7 wherein the electrical-short layer comprises a line across one section of the coil pattern.