Method for forming radio frequency antenna

• US 7,268,740 B2
• Filed: 08/24/2004
• Issued: 09/11/2007
• 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): Dinh, Trinh Vo
• Application Number:
  US10/925,229
• Publication Number:
  US 20050078035A1
• Time in Patent Office: 1,113 Days
• Field of Search: None
• US Class Current: 343/866
• 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 1/38 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 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 9/27 Spiral antennas
• CPC Class Codes: H05K 1/0393 Flexible materials H05K1/038 takes precedence; specific organic compositions are classified in H05K1/0313 and subgroups
• 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 2203/1476 Same or similar kind of process performed in phases, e.g. coarse patterning followed by fine patterning
• CPC Class Codes: H05K 2203/1545 Continuous processing, i.e. involving rolls moving a band-like or solid carrier along a continuous production path
• CPC Class Codes: H05K 2203/173 Adding connections between adjacent pads or conductors, e.g. for modifying or repairing programmable, customizable or modifiable circuits H05K1/0286
• CPC Class Codes: H05K 2203/175 Configurations of connections suitable for easy deletion, e.g. modifiable circuits or temporary conductors for electroplating; Processes for deleting connections
• 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 3/245 Reinforcing conductive patterns made by printing techniques or by other techniques for applying conductive pastes, inks or powders; Reinforcing other conductive patterns by such techniques
• CPC Class Codes: H05K 3/246 Reinforcing conductive paste, ink or powder patterns by other methods, e.g. by plating

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, the seed layer including bond pads;

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 layer or comprising a portion of the seed layer wherein the conductive layer is thinner than the remaining portions of the conductive layer, wherein the conductive layer does not cover at least a portion of the bond pads.

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

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 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 comprises 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, the seed layer including bond pads;

forming an electrical-short layer across the coil pattern;

using the electrical-short layer to electroplate a conductive layer over at least a part of the antenna coil pattern, wherein the conductive layer does not cover at least a portion of bond pads 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.

15. An RF antenna comprising:

a substrate layer;

a seed layer on top of the substrate layer in an antenna coil pattern, the seed layer including bond pads;

a conductive layer contacting the seed layer over portions of the antenna coil pattern, wherein the conductive layer does not cover at least a portion of the bond pads;

wherein the antenna has a removed short region across the coil pattern and;

wherein the removed short region comprising a portion of the seed layer not covered by the conductive layer or comprising a portion of the seed layer wherein the conductive layer is thinner than the remaining portion of the conductive layer.

16. The RF antenna of claim 15 wherein the conductive layer does not cover the bond pads.

17. A system including the RF antenna of claim 15 further including an integrated circuit connected to the bond pads.

18. The RF antenna frequency antenna of claim 15 wherein the seed layer comprises a cured conductive ink layer.

19. An RF antenna comprising:

a substrate layer;

a seed layer on top of the substrate layer in an antenna pattern, the seed layer including bond pads;

a conductive layer contacting the seed layer over portions of the antenna pattern, wherein the conductive layer does not cover at least a portion of the bond pads;

wherein the antenna has a removed short region across the antenna pattern and;

wherein the removed short region comprising a portion of the seed layer not covered by the conductive layer or comprising a portion of the seed layer wherein the conductive layer is thinner than the remaining portion of the conductive layer.

20. The RF antenna of claim 19 wherein the conductive layer does not cover the bond pads.

21. A system including the RF antenna of claim 19 further including an integrated circuit connected to the bond pads.

22. The RF antenna frequency antenna of claim 19 wherein the seed layer comprises a cured conductive ink layer.

23. The RF antenna frequency antenna of claim 19 wherein the antenna pattern is an antenna coil pattern.