# US 5,353,202 A · Personal computer with shielding of input/output signals

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- Number: US 5,353,202 A
- Document ID: US5353202A
- Status: Granted
- Kind: A
- Application number: 08/185,723
- Filed: 1994-01-24
- Granted: 1994-10-04
- Earliest claimed: 1990-07-20
- Assignees: International Business Machines Corporation
- Inventors: Daniel F. Ansell; Jeffrey W. Benck; Thomas A. Bocchino; James W. Deiso; Jose E. Richards; Mark L. Shipley; Robert D. Wysong
- Web page: https://patentgrep.com/patent/US5353202A

## CPC

- H05K 9/0018: {with provisions to reduce aperture leakages in walls, e.g. terminals, connectors, cables}
- G06F 1/182: {with special features, e.g. for use in industrial environments; grounding or shielding against radio frequency interference [RFI] or electromagnetical interference [EMI]}
- H05K 1/0218: {by printed shielding conductors, ground planes or power plane (H05K1/0236 takes precedence)}
- H05K 1/0298: {Multilayer circuits}
- H05K: PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N)

## Abstract

This invention relates to personal computers, and more particularly to the provision of a shielding structure for attenuating the possible effects of electromagnetic interference on input/output circuits of the computer while structurally reinforcing a side edge portion of a multilayer planar board. The shielding structure has two cooperating constituent parts, one being particularly formed ground plane areas in exterior layers of the planar board and the other being a particularly formed thin sheet metal member which extends about and substantially encloses connectors by which input/output signals are passed to circuits within the planar board.

## Claims

### Claim 1

A microcomputer comprising:
a chassis for mounting a multilayer printed circuit board and having a base and a panel, at least portions of said chassis being connected to a system ground for dissipation of electromagnetic interference,
a multilayer printed circuit board mounted on said chassis for interconnecting operating components of the microcomputer and having a side edge portion extending adjacent said panel, certain interior layers of said multilayer printed circuit board defining adjacent said side edge portion conductive pathways for input/output signals flowing to and from the operating components of the microcomputer,
at least one connector mounted on said multilayer printed circuit board for passing input/output signals to and from said conductive pathways, and
a shielding structure having two elements, each of said elements functioning for (i) shielding against adverse effects otherwise possibly arising from passage of input/output signals to and from said conductive pathways and (ii) structurally reinforcing said side edge portion of said multilayer printed circuit board, said shielding structure being operatively connected to a portion of said chassis connected to a system ground and substantially enclosing a region through which said input/output signals pass between said conductive pathways and said panel.

### Claim 2 (depends on 1)

A microcomputer according to claim 1 wherein one of said elements of said shielding structure comprises ground plane areas in layers of said multilayer printed circuit board to the exterior of said conductive pathways for input/output signals, said ground plane areas extending adjacent said side edge portion.

### Claim 3 (depends on 2)

A microcomputer according to claim 2 wherein the other of said elements of said shielding structure comprises a formed thin metal strip bridging between said multilayer printed circuit board and said panel.

### Claim 4 (depends on 1)

A microcomputer according to claim 1 wherein one of said elements of said shielding structure comprises a formed thin metal strip bridging between said multilayer printed circuit board and said panel.

### Claim 5 (depends on 4)

A microcomputer according to claim 4 wherein said formed thin metal strip is mechanically secured and electrically connected to said connector.

### Claim 6 (depends on 1)

A microcomputer according to claim 1 wherein one of said elements of said shielding structure comprises ground plane areas in layers of said multilayer printed circuit board to the exterior of said conductive pathways for input/output signals, said ground plane areas being defined by an array of lines of conductive material extending adjacent said side edge portion.

### Claim 7 (depends on 6)

A microcomputer according to claim 6 wherein said array of lines comprises a plurality of first lines extending in a first direction and parallel one to another, said first lines being spaced one from another at a distance approximately equal to the width thereof, and a plurality of second lines extending in a second direction and parallel one to another, said second direction being such that said second lines cross said first lines and said lines together define a grid pattern.

### Claim 8 (depends on 7)

A microcomputer according to claim 7 wherein said second direction is perpendicular to said first direction.

### Claim 9

A microcomputer having a high speed system processor compatible with application programs and operating system software designed to execute on slower speed system processors and comprising:
a chassis for mounting a planar board and having a base, a front panel and a rear panel, and at least portions of said chassis being maintained at a system ground for dissipation of electromagnetic interference,
a multilayer planar board mounted on said chassis for interconnecting operating components of the microcomputer and having a side edge portion extending adjacent one of said front and rear panels, interior layers of said planar board defining adjacent said side edge portion conductive pathways for input/output signals flowing to and from the operating components of the microcomputer,
a high speed microprocessor having a real and protected mode of operation electrically connected with said planar board and coupled to a high speed data bus;
non-volatile memory electrically connected with said planar board and coupled to a slower speed data bus;
a bus controller electrically connected with said planar board for providing communications between the high speed data bus and the slower speed data bus;
volatile memory electrically responsive to the high speed data bus;
a memory controller electrically coupled to said volatile memory and said non-volatile memory, said memory controller regulating communications between said volatile memory and said high speed microprocessor;
a cover for engaging said chassis and forming with said chassis a shielded, enclosed volume for containing said microprocessor, memory and controller components of the microcomputer,
at least one connector mounted on said planar board for passing input/output signals to and from said conductive pathways, and
a shielding structure having two elements, each of said elements functioning for (i) shielding against adverse effects otherwise possibly arising from passage of input/output signals to and from said conductive pathways and (ii) structurally reinforcing said side edge portion of said multilayer printed circuit board, said shielding structure being operatively connected to a portion of said chassis connected to a system ground and substantially enclosing a region through which said input/output signals pass between said conductive pathways and said panel.