Backplane power distribution system

• US 6,727,435 B1
• Filed: 06/08/2000
• Issued: 04/27/2004
• Est. Priority Date: 03/12/1996
• Status: Expired due to Fees

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Shepherd, Barry Lee, Egan, Patrick Kevin
• Primary Examiner(s): Zarneke, David A.
• Assistant Examiner(s): Alcala, Jose H.
• Application Number:
  US09/590,564
• Time in Patent Office: 1,419 Days
• Field of Search: 174/250, 174/255, 174/262-266, 174/260, 361/792-795, 361/748, 361/780, 428/310.5, 428/810.5, 338/307-310
• US Class Current: 174/250
• CPC Class Codes: H05K 1/0212 Printed circuits or mounted components having integral heating means
• CPC Class Codes: H05K 1/0265 characterized by the lay-out of or details of the printed conductors, e.g. reinforced conductors, redundant conductors, conductors having different cross-sections
• CPC Class Codes: H05K 2201/044 Details of backplane or midplane for mounting orthogonal PCBs
• 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 2201/0969 Apertured conductors
• CPC Class Codes: H05K 3/4641 having integrally laminated metal sheets or special power cores
• CPC Class Codes: H05K 7/1457 Power distribution arrangements
• CPC Class Codes: H05K 7/1458 Active back panels; Back panels with filtering means

Abstract

A powerplane for use in a backplane power distribution system. The backplane includes a conductive sheet for distributing power from a power source to a load. The powerplane further includes source locations and load locations for coupling the conductive sheet to a power source and a load. The conductive sheet has resistances with appropriate spacing and dimensions so that the resistance near the source locations is greater than the resistance farther away from the source locations. Thus, current is shared more evenly between all the load locations, and the voltage difference between distant load locations and near load locations is reduced to near zero.

Claims

1. A powerplane for use in a backplane power distribution system, comprising:

(a) a conductive sheet;

(b) at least one source location on said conductive sheet for coupling to a power source;

(c) a plurality of load locations on said conductive sheet for coupling to at least one load;

(d) a plurality of resistance variations in the thickness of said conductive sheet between said at least one source location and said plurality of load locations so that substantially the same amount of current is distributed to each of said plurality of load locations from said power source coupled to at least one source location.

2. A powerplane according to claim 1, wherein said powerplane includes a plurality of load pins and at least one source pin and wherein said at least one source location and said plurality of load locations comprise vias for receiving a corresponding one of said at least one source pin and said load pins, at least a portion of said vias having plated perimeters for electrically connecting said powerplane to said load pins and source pins.

3. A powerplane according to claim 1, wherein said conductive sheet comprises copper.

4. A backplane power distribution system for distributing power from a power source, comprising:

a laminate having

a plurality of interleaved dielectric layers and conductive layers wherein at least one of said conductive layers is a powerplane for distributing said power; and

a plurality of source locations and load locations, said source locations being provided to couple said powerplane to said power source and said load locations being provided to couple said powerplane to at least one load,

a plurality of resistance variations arranged within the thickness of said powerplane to distribute current so the voltage difference between said load locations is reduced to near zero.

5. A backplane power distribution system according to claim 4, wherein said source locations and said load locations define a plurality of holes passing through said laminate, said holes forming vias in each of said layers of said laminate, said vias being adapted to couple said powerplane to said loads and said power source.

6. A backplane power distribution system according to claim 5, wherein said laminate further includes source pins and load pins, and wherein a first number of said vias in at least one of said conductive layers are provided with plated perimeters for connection to said load pins and said source pins and a second number of said vias in said at least one of said conductive layer are provided with an insulated perimeter for insulating said second number of vias from said load pins and source pins.

7. A backplane power distribution system according to claim 4, wherein said conductive layers comprise copper.

8. A backplane power distribution system according to claim 4, wherein said load locations are provided to couple said powerplane to at least one circuit board.

9. A powerplane for use in a backplane power distribution system, comprising:

(a) a conductive sheet;

(b) means to electrically couple a power source to said conductive sheet;

(c) means to electrically couple at least one load to said conductive sheet;

(d) means comprising a plurality of resistance variations within the thickness of said conductive sheet to distribute substantially the same amount of current from said power source to all of said coupled at least one load.

10. The powerplane of claim 9, wherein said conductive sheet is copper.

11. The powerplane of claim 9, wherein said means to couple said power source and said means to couple said at least one load to said conductive sheet are selected from the group comprising:

connector straps, pads, and vias which receive a plurality of source pins and a plurality of load pins.

12. The powerplane of claim 11, wherein

said plurality of load locations further comprises near load locations and distant load locations with said near load locations being nearer to said plurality of source locations than said distant load locations, and

wherein said means of a plurality of resistance variations within the thickness of the conductive sheet to distribute substantially the same amount of current further comprises:

means within the thickness of said conductive sheet to variably increase the resistance of the conductive sheet between said plurality of source locations and said load locations, and

means within the thickness of said conductive sheet to substantially reduce the voltage difference between said near load locations and said distant load locations.

13. A powerplane for use in a backplane power distribution system, comprising:

(a) a conductive sheet;

(b) at least one source location on said conductive sheet for coupling to a power source;

(c) a plurality of load locations on said conductive sheet for coupling to at least one load;

(d) a plurality of circular and noncircular resistance variations within the thickness of said conductive sheet so that the current from the coupled power source at said at least one source location to all of said loads coupled to said plurality of load locations is substantially equal.

14. The powerplane of claim 13, wherein said resistance variations are voids within the plane of said conductive sheet.

15. The powerplane of claim 13, wherein said resistance variations are areas of increased thickness of said conductive sheet.

16. The powerplane of claim 13, wherein said resistance variations are materials having a greater resistance than said conductive sheet situated within the thickness of said conductive sheet.