Electromagnetic filter for display screens

• US 6,599,681 B2
• Filed: 07/13/2001
• Issued: 07/29/2003
• Est. Priority Date: 07/13/2001
• Status: Expired due to Term

• Current Assignee: Shielding Express
• Original Assignee: Shielding Express
• Inventors: Gilson, Jeffrey R.
• Primary Examiner(s): McPherson, John A.
• Application Number:
  US09/906,025
• Publication Number:
  US 20030013048A1
• Time in Patent Office: 746 Days
• Field of Search: 430/321, 430/319, 430/198, 174/35.R, 174/35.MS
• US Class Current: 430/321
• CPC Class Codes: H05K 1/092 Dispersed materials, e.g. conductive pastes or inks
• CPC Class Codes: H05K 3/02 in which the conductive material is applied to the surface of the insulating support and is thereafter removed from such areas of the surface which are not intended for current conducting or shielding
• CPC Class Codes: H05K 9/0096 for television displays, e.g. plasma display panel

Abstract

A shielded substrate manufacturing technique is described which creates a conductive pattern on at least one transparent surface. The resulting product provides for both EMI shielding and visual transparency. It is formed by placing a thick film photo-printable composition on a substrate, exposing the thick film to a photo mask having a desired grid pattern, developing, and then firing the assembly. The process is less wasteful and more environmentally friendly than prior art processes that rely upon vapor deposition of metal in etching processes to provide the grid and provides a more uniformly spaced grid than techniques that use preconstructed metal wire meshes.

Claims

1. A method for making a visually transparent radio frequency interference shield comprising the steps of:

providing a photo-sensitive, thick film composition on a substrate;

exposing the photo-sensitive composition to photo radiation to define a pattern of interconnected elements forming a grid of crossed and electrically connected conductive lines in two dimensions for the radio frequency interference shield;

developing the exposed photo-sensitive composition in solution to remove the thick film material in areas not exposed to photo radiation; and

firing the developed thick film composition, thereby forming an enhanced conductivity thick film on the optically transparent substrate.

2. A method as in claim 1 wherein the substrate is formed of a material selected from a group consisting of glass, transparent plastic, or other transparent material.

3. A method as in claim 1 wherein photo-printable composition is a conductive thick film paste.

4. A method as in claim 1 wherein the photo-printable composition is printed onto the substrate in the approximate desired grid pattern.

5. A method as in claim 1 wherein the photo-printable composition is fabricated as a film which is roll-laminated onto the substrate.

6. A method as in claim 1 additionally comprising the step of:

transferring the completed electromagnetic shield onto another carrier material.

7. A method as in claim 1 wherein the grid pattern has an open area of at least 40%.

8. A method as in claim 1 wherein the substrate material is a conductive glass.

9. A method as in claim 8 wherein the substrate material comprise an additional conductive thin film layer.

10. A method as in claim 1 additionally comprising the step of laminating:

a second glass layer onto a first glass layer.

11. A method as in claim 1 additionally comprising the step of:

coating a second opaque non-reflective thick film on the developed and fired thick film conductive composition to improve display contrast by decreasing reflections from external light.

12. A method as in claim 11 wherein the second layer is a conductive layer.

13. A method as in claim 11 wherein the second layer is a non-conductive layer.

14. A method as in claim 1 wherein the composition is a conductive black material.

15. A method as in claim 1 additionally comprising the step of after the firing step:

blackening the photo-printable conductive composition.

16. A method as in claim 15 wherein the step of blackening the composition is one of chemically treating or electroplating.

17. A method as in claim 1 wherein the width of the conductive trace is about 0.003 inches or less.

18. A high definition conductive pattern used for electromagnetic interference shielding of an optical window, wherein a photo-sensitive conductive thick film composition defines a conductive pattern of interconnected elements as a grid of crossed and electrically connected conductive lines in two dimensions.

19. An apparatus as in claim 18 wherein the conductive pattern is formed on a visually transparent substrate.

20. An apparatus as in claim 19 wherein the visually transparent substrate is of a material selected from a group consisting of glass, plastic, or other transparent material.

21. An apparatus as in claim 18 additionally comprising:

a second, non-reflective composition coated onto the photosensitive conductive composition to improve display contrast by decreasing reflections from external light.

22. An apparatus as in claim 21 wherein the second composition layer is conductive.

23. An apparatus as in claim 21 where the second composition is nonconductive.