Electromagnetic interference shielding for a printed circuit board

• US 7,443,693 B2
• Filed: 04/15/2004
• Issued: 10/28/2008
• Est. Priority Date: 04/15/2003
• Status: Active Grant

• Current Assignee: Deep Coat, LLC, WaveZero, Inc.
• Original Assignee: WaveZero, Inc.
• Inventors: Montauti, Fabrizio, Arnold, Rocky R., Zarganis, John C.
• Primary Examiner(s): Reichard; Dean A.
• Assistant Examiner(s): Getachew; Abiy
• Application Number:
  US10/825,999
• Publication Number:
  US 20040240191A1
• Time in Patent Office: 1,657 Days
• Field of Search: 361/815, 361/818, 361/800, 361/803, 174/52.3, 257/660
• US Class Current: 361/800
• CPC Class Codes: H01L 21/50 Assembly of semiconductor devices using processes or apparatus not provided for in a single one of the subgroups H01L21/06 - H01L21/326, e.g. sealing of a cap to a base of a container
• CPC Class Codes: H01L 2224/05599 Material
• CPC Class Codes: H01L 2224/16 of an individual bump connector
• CPC Class Codes: H01L 2224/16235 the bump connector connecting to a via metallisation of the item
• CPC Class Codes: H01L 2224/32225 the item being non-metallic, e.g. insulating substrate with or without metallisation
• CPC Class Codes: H01L 2224/45099 Material
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/48227 connecting the wire to a bond pad of the item
• CPC Class Codes: H01L 2224/48233 connecting the wire to a potential ring of the item
• CPC Class Codes: H01L 2224/49171 Fan-out arrangements
• CPC Class Codes: H01L 2224/49175 Parallel arrangements
• CPC Class Codes: H01L 2224/73253 Bump and layer connectors
• CPC Class Codes: H01L 2224/73265 Layer and wire connectors
• CPC Class Codes: H01L 23/04 characterised by the shape of the container or parts, e.g. caps, walls
• CPC Class Codes: H01L 23/3128 the substrate having spherical bumps for external connection
• CPC Class Codes: H01L 23/315 the encapsulation having a cavity
• CPC Class Codes: H01L 23/4334 Auxiliary members in encapsulations H01L23/49568 takes precedence
• CPC Class Codes: H01L 23/49816 Spherical bumps on the substrate for external connection, e.g. ball grid arrays [BGA]
• CPC Class Codes: H01L 23/49822 Multilayer substrates multilayer metallisation on monolayer substrate H01L23/498
• CPC Class Codes: H01L 23/49838 Geometry or layout
• CPC Class Codes: H01L 23/50 : for integrated circuit devices, e.g. power bus, number of leadsH01L23/482 - H01L23/498 take precedence
• CPC Class Codes: H01L 23/552 : Protection against radiation, e.g. light or electromagnetic waves
• CPC Class Codes: H01L 24/16 : of an individual bump connector
• CPC Class Codes: H01L 24/48 : of an individual wire connector
• CPC Class Codes: H01L 24/49 : of a plurality of wire connectors
• CPC Class Codes: H01L 2924/00 : Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/00014 : the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details
• CPC Class Codes: H01L 2924/01006 : Carbon [C]
• CPC Class Codes: H01L 2924/01013 : Aluminum [Al]
• CPC Class Codes: H01L 2924/01014 : Silicon [Si]
• CPC Class Codes: H01L 2924/01027 : Cobalt [Co]
• CPC Class Codes: H01L 2924/01028 : Nickel [Ni]
• CPC Class Codes: H01L 2924/01029 : Copper [Cu]
• CPC Class Codes: H01L 2924/01047 : Silver [Ag]
• CPC Class Codes: H01L 2924/0105 : Tin [Sn]
• CPC Class Codes: H01L 2924/01074 : Tungsten [W]
• CPC Class Codes: H01L 2924/01078 : Platinum [Pt]
• CPC Class Codes: H01L 2924/01079 : Gold [Au]
• CPC Class Codes: H01L 2924/014 : Solder alloys
• CPC Class Codes: H01L 2924/07802 : not being an ohmic electrical conductor
• CPC Class Codes: H01L 2924/12042 : LASER
• CPC Class Codes: H01L 2924/14 : Integrated circuits
• CPC Class Codes: H01L 2924/15192 : Resurf arrangement of the internal vias
• CPC Class Codes: H01L 2924/15311 : being a ball array, e.g. BGA
• CPC Class Codes: H01L 2924/1532 : the connection portion being formed on the die mounting surface of the substrate
• CPC Class Codes: H01L 2924/16152 : Cap comprising a cavity for hosting the device, e.g. U-shaped cap
• CPC Class Codes: H01L 2924/1617 : Cavity coating
• CPC Class Codes: H01L 2924/16315 : Shape
• CPC Class Codes: H01L 2924/166 : Material
• CPC Class Codes: H01L 2924/181 : Encapsulation
• CPC Class Codes: H01L 2924/3011 : Impedance
• CPC Class Codes: H01L 2924/3025 : Electromagnetic shielding
• CPC Class Codes: H05K 1/0218 : by printed shielding conductors, ground planes or power plane H05K1/0236 takes precedence
• CPC Class Codes: H05K 2201/10734 : Ball grid array [BGA]; Bump grid array
• CPC Class Codes: H05K 9/003 : made from non-conductive materials comprising an electro-conductive coating H05K9/0031 takes precedence
• CPC Class Codes: H05K 9/0035 : with retainers mounted beforehand on the PCB, e.g. clips

Abstract

The present invention provides shielded printed circuit boards and electronic devices. The printed circuit board may comprise an internal network of grounded conductive elements that are coupleable to an EMI shield that is mounted on the printed circuit board. The network of grounded conductive elements are coupleable to a grounded layer and to the EMI shield and provides improved EMI shielding through the volume of the printed circuit board below an electronic component mounted on the printed circuit board.

Claims

1. A shielded printed circuit board (PCB) comprising:

a PCB comprising a first surface and a second surface;

a metallized polymer shield coupled to the first surface of the PCB;

a grounded layer coupled to the second surface of the PCB;

a plurality of conductive vias that extend from the first surface to the grounded layer so as to electrically couple the metallized polymer shield to the grounded layer;

an electronic component mounted to the first surface of the PCB;

wherein adjacent conductive vias are spaced within the PCB a distance that is small enough to reduce a passage of electromagnetic radiation from the electronic component through the spacing between the adjacent conductive vias;

wherein the metallized polymer shield comprises a shaped polymer substrate that provides a cavity that is sized and shaped to receive the electronic component, wherein the shaped polymer substrate comprises a flange that extends around at least a portion of a perimeter of the cavity in a direction that is substantially parallel to the first surface of the PCB; and

a metal layer disposed over at least one surface of the shaped polymer substrate.

2. The shielded PCB of claim 1 wherein the plurality of conductive vias, grounded layer, and metallized polymer shield forms a three dimensional grounded EMI shield that substantially envelopes the electronic component.

3. The shielded PCB of claim 1 wherein the metallized polymer shield is removably coupled to the first surface of the PCB.

4. The shielded PCB of claim 3 wherein the metallized polymer shield is coupled to the vias through a conductive element.

5. The shielded PCB of claim 4 wherein the conductive element comprises a conductive adhesive.

6. The shielded PCB of claim 3 wherein the metallized polymer shield is coupled to the vias through a mechanical connector.

7. The shielded PCB of claim 1 wherein the PCB comprises two or more layers, wherein the second surface is between two adjacent layers of the PCB.

8. The shielded PCB of claim 1 wherein the second surface is an external, bottom surface of the PCB.

9. The shielded PCB of claim 1 wherein the grounded layer comprises a ground plane.

10. The shielded PCB of claim 1 wherein the grounded layer is electrically coupled to a ground plane.

11. The shielded PCB of claim 1 wherein the flange of the metallized polymer shield comprises a plurality of openings.

12. An electronic device comprising the PCB of claim 1.

13. The shielded PCB of claim 1 wherein at least one of said conductive vias is located below said PCB.

14. A printed circuit board comprising:

a multi-layered substrate that comprises a first external surface and a second external surface, wherein a portion of the first external surface is configured to receive an electronic component;

one or more internal grounded layers disposed between adjacent layers of the multi-layered substrate;

a network of conductive elements that extend through at least a portion of the multi-layered substrate, wherein the electrically conductive elements extend from at least one of the internal grounded planes to the first external surface;

a shield coupled to the first surface, the shield electrically coupled to at least some of the conductive elements to provide an electrical grounding connection between the shield and the one or more internal grounded planes;

wherein spaces between adjacent conductive elements comprise a largest dimension that is small enough to substantially reduce emission of electromagnetic radiation from the electronic component;

wherein the shield comprises a shaped polymer substrate that provides a cavity that is sized and shaped to receive an electronic component, wherein the shaped polymer substrate comprises a flange that extends around at least a portion of a perimeter of the cavity in a direction that is substantially parallel to the first external surface of the PCB; and

a metal layer disposed over at least one surface of the shaped polymer substrate.

15. The printed circuit board of claim 14 wherein the network of conductive elements comprises a plurality of conductively coated or filled vias.

16. The printed circuit board of claim 14 further comprising a grounding trace on the first external surface that substantially surrounds the portion of the first external surface that is configured to receive an electronic component.

17. The printed circuit board of claim 14 wherein the largest dimension is smaller than half a wavelength of EMI emissions from the electronic component.

18. The printed circuit board of claim 14 wherein the first surface comprises at least one mechanical connector that electrically couples a conductive portion of the shield to the network of conductive elements.

19. The printed circuit board of claim 18 wherein the mechanical connector comprises a conductive or nonconductive adhesive.

20. The printed circuit board of claim 18 wherein the mechanical connector comprises a groove in the first surface, wherein the groove is sized to receive a portion of an EMI shield.

21. The printed circuit board of claim 14 wherein the shield comprises a metal can.

22. The printed circuit board of claim 14 wherein the shield is coupled to a ground trace positioned on the first external surface, wherein the ground trace is in electrical communication with at least some of the conductive elements.

23. The printed circuit board of claim 14 wherein the conductive elements make direct contact with a flange of the shield.

24. The printed circuit board of claim 23 wherein a conductive element is disposed on a portion of the conductive elements to create an electrical connection to the shield positioned on the first external surface.

25. The printed circuit board of claim 23 wherein the conductive element comprises conductive adhesive.

26. An electronic device comprising the PCB of claim 14.

27. The printed circuit board of claim 14 wherein at least one of said conductive elements is located below said electronic component.

37. The method of claim 20 wherein said providing a PCB further comprises providing at least one of said plurality of conductive vias to be located below said PCB.

28. A method of shielding an electronic component on a printed circuit board (PCB), the method comprising:

providing a PCB that comprises an electronic component on a first surface of the PCB and one or more grounded layers, and a plurality of conductive vias that extend from the first surface to at least one of the grounded layers;

coupling a metallized polymer shield to the first surface of the PCB and around the electronic component to create an electrical connection to the conductive vias and the grounded layer(s),

wherein the electrical connection between the grounded layer(s), vias, and the metallized polymer shield forms a grounded EMI shield that substantially surrounds the electronic component;

wherein adjacent conductive vias are spaced within the PCB a distance that is small enough to reduce a passage of electromagnetic radiation from the electronic component through the spacing between the adjacent conductive vias;

wherein the metallized polymer shield comprises a shaped polymer substrate that provides a cavity that is sized and shaped to receive the electronic component, wherein the shaped polymer substrate comprises a flange that extends around at least a portion of a perimeter of the cavity in a direction that is substantially parallel to the first surface of the PCB; and

a metal layer disposed over at least one surface of the shaped polymer substrate.

29. The method of claim 28 comprising placing the PCB in a housing of an electronic device.

30. The method of claim 28 wherein the metallized polymer shield is removably coupled to the first surface of the PCB.

31. The method of claim 28 wherein the metallized polymer shield is coupled to the conductive vias through a ground trace on the first surface of the PCB.

32. The method of claim 28 comprising positioning a conductive adhesive between the metallized polymer shield and the first surface before the metallized polymer shield is coupled to the first surface of the PCB.

33. The method of claim 28 further comprising creating openings in a flange of the metallized polymer shield that correspond to the position of the vias on the PCB;

and

placing a conductive element over the openings to create a conductive path between a metal layer on the metallized polymer shield and the vias.

34. The method of claim 28 wherein providing a PCB comprises forming the vias in the PCB,

wherein the vias are conductively coated or filled and are in a spaced configuration that has a largest distance between an adjacent via that is smaller than half a wavelength of the electromagnetic radiation that is emitted from the electronic component.

35. The method of claim 28 wherein at least one of the grounded layers comprises a ground plane.

36. The method of claim 28 wherein providing a PCB comprises forming a groove in the first surface of the PCB.