Conformally coated faraday cage

• US 5,350,594 A
• Filed: 01/25/1993
• Issued: 09/27/1994
• Est. Priority Date: 01/25/1993
• Status: Expired due to Term

• Current Assignee: Illinois Tool Works Inc.
• Original Assignee: Tech Spray LP (Tech Spray)
• Inventors: Unruh, Greg R.
• Primary Examiner(s): Beck, Shrive
• Assistant Examiner(s): DANG, VI
• Application Number:
  US08/008,202
• Time in Patent Office: 610 Days
• Field of Search: 427/96, 427/421, 427/429, 427/430.1, 427/410, 427/419.5
• US Class Current: 427/96.4
• CPC Class Codes: H05K 1/0218 by printed shielding conductors, ground planes or power plane H05K1/0236 takes precedence
• CPC Class Codes: H05K 1/0259 Electrostatic discharge [ESD] protection
• CPC Class Codes: H05K 2201/0715 provided by an outer layer of PCB
• CPC Class Codes: H05K 3/284 for encapsulating mounted components H05K1/185 takes precedence
• CPC Class Codes: H05K 9/0067 Devices for protecting against damage from electrostatic discharge

Abstract

In one form of the invention, an electronic device having a conformally coated Faraday cage, comprising a non-conductive conformal layer (30) substantially coveting the electronic device (10, 12) and a conductive conformal layer (34) substantially coveting the non-conductive conformal layer.

Claims

1. A method of coating an electronic device, comprising the steps of:

(a) applying a non-conductive conformal layer substantially covering said electronic device; and

(b) applying a conductive conformal layer substantially coveting said non-conductive conformal layer, wherein said conductive conformal layer is formed by addition of a conductive additive to a material of substantially the same composition as a material used to form said non-conductive conformal layer.

2. The method of claim 1 wherein said electronic device includes a circuit board and further including the step of operatively coupling said conductive conformal layer to a ground plane of said circuit board.

3. The method of claim 1 wherein said step (a) comprises applying a material selected from the group consisting of acrylic resins, epoxy resins, silicone resins, urethane resins, and paraxylene.

4. The method of claim 1 wherein said conductive additive is an Antimony doped Tin Oxide.

5. The method of claim 1 wherein said steps (a) and (b) comprise a method selected from the group consisting of dip coating, brush coating, non-aerosol spray coating, and aerosol spray coating.

6. The method of claim 1 wherein said conductive conformal layer has a surface resistivity of less than 10⁹ Ohms/square.

7. A method of grounding an electronic circuit board, comprising the steps of:

(a) applying a non-conductive conformal layer substantially coveting said electronic circuit board;

(b) applying a conductive conformal layer substantially coveting said non-conductive conformal layer, wherein said conductive conformal layer is formed by addition of a conductive additive to a material of substantially the same composition as a material used to form said non-conductive conformal layer;

(c) making electrical contact between said conductive conformal layer and a ground plane of said electronic circuit board; and

(d) operatively coupling said ground plane to a ground potential.

8. The method of claim 7 wherein said step (a) comprises applying a material selected from the group consisting of acrylic resins, epoxy resins, silicone resins, urethane resins, and paraxylene.

9. The method of claim 7 wherein said conductive additive is an Antimony doped Tin Oxide.

10. The method of claim 7 wherein said steps (a) and (b) comprise a method selected from the group consisting of dip coating;

brush coating, non-aerosol spray coating, and aerosol spray coating.

11. The method of claim 7 wherein said conductive conformal layer has a surface resistivity of less than 10⁹ Ohms/square.