Printed circuit board including a terminated power plane and method of manufacturing the same

• US 5,898,576 A
• Filed: 11/12/1996
• Issued: 04/27/1999
• Est. Priority Date: 11/12/1996
• Status: Expired due to Term

• Current Assignee: RPX Clearinghouse LLC (RPX Corporation)
• Original Assignee: Bay Networks, Inc. (Nortel Networks Corporation)
• Inventors: Pavlu, III, Edward J., Lockwood, John J.
• Primary Examiner(s): Picard, Leo P.
• Assistant Examiner(s): Gandhi, Jayprakash N.
• Application Number:
  US08/747,397
• Time in Patent Office: 896 Days
• Field of Search: 361/212, 361/220, 361/766, 361/780, 361/782, 361/794, 361/803, 361/811, 361/818, 333/12, 333/22 R, 333/181, 333/184, 333/185, 333/24 C, 333/246, 174/255, 174/260, 174/35 R
• US Class Current: 361/782
• CPC Class Codes: H05K 1/0227 Split or nearly split shielding or ground planes
• CPC Class Codes: H05K 1/0231 Capacitors or dielectric substances
• CPC Class Codes: H05K 1/0234 Resistors or by disposing resistive or lossy substances in or near power planes H05K1/0246 takes precedence
• CPC Class Codes: H05K 1/167 incorporating printed resistors
• CPC Class Codes: H05K 2201/093 Layout of power planes, ground planes or power supply conductors, e.g. having special clearance holes therein reduction of cross-talk, noise or interference by patterned shielding planes, ground planes or power planes H05K1/0224
• CPC Class Codes: H05K 2201/09309 Core having two or more power planes; Capacitive laminate of two power planes
• CPC Class Codes: H05K 2201/09663 Divided layout, i.e. conductors divided in two or more parts branched layout H05K2201/09254
• CPC Class Codes: H05K 2201/10022 Non-printed resistor
• CPC Class Codes: H05K 2201/10522 Adjacent components
• CPC Class Codes: H05K 2201/10636 Leadless chip, e.g. chip capacitor or resistor
• CPC Class Codes: H05K 9/0039 Galvanic coupling of ground layer on printed circuit board [PCB] to conductive casing printed shielding conductors, ground planes or power planes for reduction of cross-talk or noise in printed circuits H05K1/0218
• CPC Class Codes: Y02P 70/50 Manufacturing or production processes characterised by the final manufactured product

Abstract

A printed circuit board including a terminated power plane is described. Specifically, the power-ground plane construction includes a dielectric layer, a power plane having a peripheral edge, and a ground plane. The ground plane is spaced from the power plane by the dielectric layer, and is positioned in an opposed relationship to the power plane. The power-ground plane construction also includes a termination element coupling the power plane, at or adjacent the peripheral edge thereof, to the ground plane so as to terminate the power plane. In one embodiment, a plurality of termination elements couple the power plane, at or adjacent the peripheral edge thereof, to the ground plane. The termination elements are spaced from each other at substantially regular intervals. In another embodiment, a termination element is a strip or sheet element coupling continuous lengths of the peripheral edge of the power plane to ground plane.

Claims

1. A printed circuit board comprising:

a dielectric layer;

a power plane having a peripheral edge;

a ground plane spaced from the power plane by the dielectric layer; and

a termination element coupling the power plane to the ground plane at or adjacent a peripheral edge of the power plane so as to terminate the power plane and reduce resonances therein.

2. The printed circuit board of claim 1 including a plurality of termination elements coupling the power plane, at or adjacent the peripheral edge thereof, to the ground plane, and wherein the plurality of termination elements are spaced from each other at substantially regular intervals.

3. The printed circuit board of claim 2 wherein the power plane is substantially rectangular in shape and has first, second, third and fourth side edges, the plurality of termination elements coupling the power plane, at or adjacent the first side edge thereof, to the ground plane.

4. The printed circuit board of claim 3 wherein the first and third side edges of the power plane are located at opposed ends thereof, and the plurality of termination elements couple the power plane, at or adjacent the first and third side edges thereof, to the ground plane.

5. The printed circuit board of claim 3 wherein the plurality of termination elements couple the power plane, at or adjacent the first, second, third and fourth side edges thereof, to the ground plane.

6. The printed circuit board of claim 1 wherein the termination element comprises a discrete element having resistive and capacitive characteristics.

7. The printed circuit board of claim 1 wherein the termination element comprises discrete resistor and capacitor elements.

8. The printed circuit board of claim 2 wherein the plurality of termination elements are connected in parallel between the power and ground planes.

9. The printed circuit board of claim 1 wherein the termination element comprises a strip element coupling the power plane, at or adjacent a continuous edge portion thereof, to the ground plane.

10. The printed circuit board of claim 9 wherein the power plane is substantially rectangular in shape and has first, second, third and fourth side edges, the strip element coupling the power plane, at or adjacent the first side edge thereof, to the ground plane.

11. The printed circuit board of claim 10 wherein the first and third side edges of the power plane are located at opposed ends thereof, and the strip element couples the power plane, at or adjacent the first and third side edges thereof, to the ground plane.

12. The printed circuit board of claim 9 wherein the strip element couples the power plane, at or adjacent the entire peripheral edge thereof, to the ground plane.

13. The printed circuit board of claim 9 wherein the strip element has both resistive and capacitive elements, the resistive element comprising a resistor coupled to the power plane, at or adjacent a peripheral edge thereof, and the spacing between a plane coupled to the resistor and the ground plane creates an intrinsic capacitance to provide the capacitive element of the termination element.

14. A method of manufacturing a printed circuit board, the method including the steps of:

providing a dielectric layer having opposed first and second surfaces;

locating a power plane, having a peripheral edge, and a ground plane, on the first and second surfaces respectively, so that the power and ground planes are in a spaced, opposed relationship to each other; and

coupling a termination element between a location on the power plane, at or adjacent the peripheral edge thereof, and the ground plane so as to terminate the power plane.

15. The method of claim 14 including the step of coupling a plurality of termination elements between the power plane, at or adjacent the peripheral edge thereof, and the ground plane, the termination elements being spaced from each other at substantially regular intervals.

16. The method of claim 15 wherein the power plane is substantially rectangular in shape and has first, second, third and fourth side edges, the method including the step of coupling the plurality of termination elements between the power plane, at or adjacent the first side edge thereof, and the ground plane.

17. The method of claim 16 wherein the first and third side edges of the power plane are located at opposed ends thereof, the method including the step of coupling the plurality of termination elements between the power plane, at or adjacent the first and third side edges thereof, and the ground plane.

18. The method of claim 16 including the step of coupling the plurality of termination elements between the power plane, at or adjacent the first, second, third and fourth sides edges thereof, and the ground plane.

19. The method of claim 14 wherein the termination element comprises a discrete element having resistive and capacitive characteristics.

20. The method of claim 14 wherein the termination element comprises discrete resistor and capacitor elements.

21. The method of claim 15 including the step of connecting the plurality of termination elements in parallel between the power and ground planes.

22. The method of claim 14 including the step of coupling a strip element between the power plane, at or adjacent a continuous portion of the peripheral edge thereof, and the ground plane.

23. The method of claim 22 wherein the power plane is substantially rectangular in shape and has first, second, third and fourth side edges, the method including the step of coupling the strip element between the power plane, at or adjacent the first side edge thereof, and the ground plane.

24. The method of claim 23 wherein the first and third side edges of the power plane are located at opposed ends of the power plane, the method including the step of coupling the strip element between the power plane, at or adjacent the first and third side edges thereof, and the ground plane.

25. The method of claim 22 including the step of coupling the strip element between the power plane, at or adjacent the entire respective peripheral edge thereof, and the ground plane.