CONFORMING EMI SHIELDING

• US 20110085316A1
• Filed: 05/11/2010
• Published: 04/14/2011
• Est. Priority Date: 10/12/2009
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Myers, Scott, Weber, Douglas
• Granted Patent: US 8,493,749 B2
• Time in Patent Office: Days
• US Class Current: 361/818
• CPC Class Codes: H05K 1/0218 by printed shielding conductors, ground planes or power plane H05K1/0236 takes precedence
• CPC Class Codes: H05K 2201/09872 Insulating conformal coating foil encapsulation H05K2203/1311
• CPC Class Codes: H05K 2203/1311 Foil encapsulation, e.g. of mounted components
• CPC Class Codes: H05K 3/284 for encapsulating mounted components H05K1/185 takes precedence
• CPC Class Codes: H05K 9/0024 Shield cases mounted on a PCB, e.g. cans or caps or conformal shields
• CPC Class Codes: Y10T 29/49146 with encapsulating, e.g., potting, etc.

Abstract

This is directed to an EMI shield constructed from a conformal coating. A circuit board can include electronic components for which EMI shielding is required. To provide such shielding in a space-efficient manner, a first non-conductive conformal coating can be placed over the circuit board and the electronic components. A second conductive conformal coating can then be placed over the first such that at least portions of the second coating around the periphery of the electronic components are electrically coupled to the circuit board.

Claims

1. An electronic device, comprising:

a circuit board;

at least one component coupled to the circuit board, the at least one component requiring EMI shielding;

a first conformal coating placed over the circuit board and the at least one component, the first conformal coating constructed from a non-conductive material; and

a second conformal coating placed over the first conformal coating, the second conformal coating constructed from a conductive material and at least partially grounded to the circuit board.

2. The electronic device of claim 1, wherein:

the circuit board comprises at least one conductive pad; and

the second conformal coating is electrically connected to the at least one conductive pad.

3. The electronic device of claim 2, wherein:

the first conformal coating comprises at least one opening aligned with the at least one conductive pad, wherein the second conductive coating is electrically connected to the at least one conductive pad through the at least one opening of the first conformal coating.

4. The electronic device of claim 2, wherein the second conformal coating is electrically connected to the at least one conductive pad by at least one of:

soldering;

surface mount technology;

a conductive adhesive; and

a mechanical connector.

5. The electronic device of claim 1, wherein:

the component comprises a plurality of sides; and

the second conformal coating is partially grounded to the circuit board along at least two of the plurality of sides.

6. The electronic device of claim 5, wherein:

the second conformal coating is grounded to the circuit board along each of the plurality of sides of the component.

7. The electronic device of claim 1, wherein:

the first conformal coating covers the entirety of the component.

8. The electronic device of claim 1, wherein:

the circuit board comprises a plurality of contact pads substantially surrounding the periphery of the component; and

the first conformal coating comprises a plurality of openings, wherein the plurality of openings are substantially aligned with the plurality of contact pads.

9. The electronic device of claim 8, wherein:

the contact pads comprise a substantially rectangular shape; and

the openings comprise a substantially rectangular shape, such that the intersection of the contact pads and the openings substantially forms a criss-cross pattern.

11. The method of claim 8, wherein:

the at least one portion of the conformal coating is grounded to a region adjacent to an interface between the component and the circuit board.

12. The method of claim 8, further comprising:

placing a non-conductive layer between the component and the conformal coating to prevent shorting of the component by the conformal coating.

13. The method of claim 12, wherein:

placing further comprises applying a non-conductive conformal coating between the component and the conductive conformal coating layer.

14. The method of claim 13, further comprising:

defining at least one opening in the non-conductive conformal coating; and

electrically connecting the conductive conformal coating to the circuit board through the defined at least one opening.

15. The method of claim 8, further comprising:

defining at least one conductive pad on a surface of the circuit board; and

electrically connecting the conformal coating to the at least one conductive pad.

10. A method for shielding an electronic device component from electromagnetic interference, comprising:

coupling the component to a circuit board; and

applying a conductive conformal coating over the component and circuit board, wherein at least one portion of the conformal coating is grounded to the circuit board.

16. An electromagnetic interference shield, comprising:

a sheet of conductive material, wherein the sheet is operative to be coated on an electronic device component coupled to a circuit board; and

a connection interface for electrically connecting the sheet of conductive material to a conductive pad of the circuit board.

17. The electromagnetic interference shield of claim 16, wherein the sheet is applied using at least one of:

an adhesive;

a heat process;

sputter; and

physical vapor deposition.

18. The electromagnetic interference shield of claim 16, wherein:

a non-conductive coating is positioned between the sheet of conductive material and the electronic device component.

19. The electromagnetic interference shield of claim 16, wherein the connection interface comprises at least one of:

solder;

surface mount technology;

a conductive adhesive;

a mechanical fastener.

20. The electromagnetic interference shield of claim 16, wherein:

a top surface of the component comprises a first fiducial; and

the sheet of conductive material comprises a second fiducial, wherein the first and second fiducials are to aligned when the sheet is coated on the component to ensure that the sheet covers the entirety of the component.