Main board for backplane buses

• US 20060232949A1
• Filed: 04/17/2006
• Published: 10/19/2006
• Est. Priority Date: 04/18/2005
• Status: Active Grant

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Osaka, Hideki
• Granted Patent: US 7,505,285 B2
• Time in Patent Office: Days
• US Class Current: 361/788
• CPC Class Codes: H05K 1/0236 Electromagnetic band-gap structures
• CPC Class Codes: H05K 1/0237 High frequency adaptations H05K1/0216 takes precedence
• CPC Class Codes: H05K 1/0298 Multilayer circuits
• CPC Class Codes: H05K 1/167 incorporating printed resistors
• CPC Class Codes: H05K 2201/044 Details of backplane or midplane for mounting orthogonal PCBs
• CPC Class Codes: H05K 2201/09681 Mesh conductors, e.g. as a ground plane
• CPC Class Codes: H05K 2201/0969 Apertured conductors

Abstract

A motherboard for backplane buses is provided that reduces noise due to entry of external signals into signal wiring which interconnects modules, or noise due to any external signals entering a power supply after being routed around the power supply. An EBG pattern formed up of two wiring regions different from each other in impedance is periodically disposed in at least three arrays as part of the power supply layer(s) constituting a microstripline structure (one layer adjacent to a signal layer is a power supply layer, and the other layer-is interposed in air) or a stripline structure (both layers adjacent to a signal layer are power supply layers); the part of the power supply layer(s) not being involved in signal transmission between the modules on the motherboard for backplane buses.

Claims

1. A main board for backplane buses used for mounting a plurality of sub-boards via connectors, the main board comprising:

signal layers for providing signal wiring between the connectors, wherein one of the signal layers adjacent to each other is interposed between power supply layers, and the other adjacent signal layer is interposed in air, or both of the adjacent signal layers are each interposed between power supply layers; and

a periodic wiring structure in which a pattern formed up of two wiring regions of different impedances is periodically disposed in at least three arrays in a portion of the power supply layers adjacent to the signal layers, the power supply layer portion being a section interposed between the connectors;

wherein the periodic wiring structure is formed so as to avoid including adjacently the signal wiring of the signal layers.

2. The main board for backplane buses according to claim 1, wherein one of adjacent regions of each of the power supply layers including the periodic wiring structure is disposed as a signal layer, and the other adjacent region is disposed as a power supply layer.

3. The main board for backplane buses according to claim 1, wherein both adjacent regions of each of the power supply layers including the periodic wiring structure are disposed as signal layers.

4. The main board for backplane buses according to claim 1, wherein a reference voltage signal line for a receiver is disposed in a signal layer adjacent to the power supply layers including the periodic wiring structure.

5. The main board for backplane buses according to claim 1, wherein one of the two wiring regions of different impedances in the periodic wiring structure is formed into a large square form and the other wiring region is formed into a small square form.

6. The main board for backplane buses according to claim 1, wherein one of the two wiring regions of different impedances in the periodic wiring structure is formed into a large rectangular form and the other wiring region is formed into a small rectangular form.

7. The main board for backplane buses according to claim 1, wherein the periodic wiring structure is formed at a section of the power supply layers, the power supply layer section being adjacent to a section between parallel sets of signal wiring of the signal layers.

8. The main board for backplane buses according to claim 1, comprising at least three connectors, wherein:

to a central connector having at least one connector installed at least at left and right sides of the central connector, all other connectors on the motherboard are connected at a certain signal layer;

signal wiring to the connector(s) installed at the left side, and signal wiring to the connector(s) installed at the right side are separated vertically with respect to and at the central connector; and

inside a power supply layer adjacent to the signal layer, a first periodic wiring structure is formed at a section of a power supply layer present between the central connector and the connector(s) installed to the immediate right of the central connector, wherein the power supply layer section with the first periodic wiring structure formed thereat is adjacent to a section of the signal layer, the section being other than that formed with the signal wiring to the connector(s) installed at the left side of the central connector,

a second periodic wiring structure is formed at a section of a power supply layer present between the central connector and the connector(s) installed to the immediate left of the central connector, wherein the power supply layer section with the second periodic wiring structure formed thereat is adjacent to a section of the signal layer, the section being other than that formed with the signal wiring to the connector(s) installed at the right side of the central connector, and

a third periodic wiring structure is formed at a power supply layer section adjacent to the section at which the two sets of signal wiring are separated vertically with respect to and at the central connector, the power supply layer section being adjacent to a section between parallel signal lines.

9. A router system comprising:

a communications functional module mounted as one of the sub-boards on the main board for backplane buses according to claim 1;

wherein the communications functional module is connected to a plurality of networks via cables, and controls data flow between the networks.

10. A storage system comprising:

a hard-disk read/write functional module mounted as one of the sub-boards on the main board for backplane buses according to claim 1;

and

a functional module further mounted to be connected to a host computer;

wherein a hard disk is connected to the hard-disk read/write functional module via a cable and the module controls data flow between the hard disk and the host computer.