# US 5,350,594 A · Conformally coated faraday cage

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- Number: US 5,350,594 A
- Document ID: US5350594A
- Status: Granted
- Kind: A
- Application number: 08/008,202
- Filed: 1993-01-25
- Granted: 1994-09-27
- Earliest claimed: 1993-01-25
- Assignees: Tech Spray, Inc.
- Inventors: Greg R. Unruh
- Web page: https://patentgrep.com/patent/US5350594A

## CPC

- H05K 1/0218: {by printed shielding conductors, ground planes or power plane (H05K1/0236 takes precedence)}
- H05K 1/0259: {Electrostatic discharge [ESD] protection}
- H05K 9/0067: {Devices for protecting against damage from electrostatic discharge}
- H05K 3/284: {for encapsulating mounted components (H05K1/185 takes precedence)}
- H05K 2201/0715: provided by an outer layer of PCB
- H05K: PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS

## 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

### Claim 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.

### Claim 2 (depends on 1)

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.

### Claim 3 (depends on 1)

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.

### Claim 4 (depends on 1)

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

### Claim 5 (depends on 1)

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.

### Claim 6 (depends on 1)

The method of claim 1 wherein said conductive conformal layer has a surface resistivity of less than 10.sup.9 Ohms/square.

### Claim 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.

### Claim 8 (depends on 7)

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.

### Claim 9 (depends on 7)

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

### Claim 10 (depends on 7)

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.

### Claim 11 (depends on 7)

The method of claim 7 wherein said conductive conformal layer has a surface resistivity of less than 10.sup.9 Ohms/square.