Electrical connectors – Electromagnetic or electrostatic shield – Shielding individually surrounding or interposed between...
Reexamination Certificate
1999-07-21
2003-05-20
Nasri, Javaid (Department: 2839)
Electrical connectors
Electromagnetic or electrostatic shield
Shielding individually surrounding or interposed between...
Reexamination Certificate
active
06565385
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
This invention relates generally to printed circuit boards and associated connectors and, more particularly, to reducing electromagnetic emissions from a connector coupled to a printed circuit board.
BACKGROUND OF THE INVENTION
Manufacturers of electronic devices frequently use printed circuit boards to mount resistors, capacitors, inductors, integrated circuits, and other electronic components. A printed circuit board generally provides electrical paths, called traces, that electrically couple to the electronic components mounted on the board. To communicate signals to external components, a printed circuit board typically includes one or more connectors that electrically couple traces within the printed circuit board to an external component using a communication link, such as a telecommunications cable.
Electromagnetic emissions from printed circuit boards generally, and from associated connectors in particular, create numerous problems for equipment operators and manufacturers. First, electromagnetic emissions from a connector may degrade the integrity of signals communicated within the printed circuit board and, consequently, may interfere with the operation of electronic components mounted on the printed circuit board. This interference is commonly known as crosstalk or feedback. Second, regulatory agencies, such as the Federal Communications Commission in the United States, often restrict electromagnetic emissions from electronic devices to ensure that emissions from one device do not interfere with the operation of other devices.
As technology advances, the electronic components mounted on printed circuit boards, as well as the traces within the printed circuit board, continue to decrease in size. In addition, printed circuit boards must increasingly communicate signals at higher frequencies. Due to these higher frequencies and the closer proximity of traces and electronic components, previous connectors for printed circuit boards are increasingly unable to limit electromagnetic emissions sufficiently to meet both the signal integrity and regulatory requirements. These and other deficiencies make previous printed circuit boards and associated connectors inadequate for many applications.
SUMMARY OF THE INVENTION
According to the present invention, disadvantages and problems associated with printed circuit boards and associated connectors have been substantially reduced or eliminated.
According to one embodiment, a connector for coupling a communication link to a printed circuit board includes a plurality of pins and a shield. The pins electrically couple the communication link to an interface on the printed circuit board and generate electromagnetic emissions when supplied with an electric current. The shield is displaced outwardly from the pins and prevents at least some of the electromagnetic emissions from radiating outside the connector. The shield includes a plurality of tabs that extend into the printed circuit board when the pins are electrically coupled to the interface.
According to another embodiment, a printed circuit board includes an interface and a plurality of openings. The interface electrically couples one or more traces to a plurality of pins on a connector, the interface and pins generating electromagnetic emissions when supplied with an electric current. The openings extend into the printed circuit board and are displaced outwardly from the interface. Each opening receives a corresponding tab of the connector when the pins are electrically coupled to the interface. The tabs prevent at least some of the electromagnetic emission from radiating outside the connector.
The present invention provides a number of important technical advantages. Unlike previous techniques, the present invention provides a connector including a shield with tabs that extend into an associated printed circuit board. The shield reduces electromagnetic emissions from the connector when the connector is coupled to the printed circuit board. First, because the tabs extend into the printed circuit board, the shield partially encloses the pins of the connector and prevents at least some of the electromagnetic emissions generated by electric currents through the pins from radiating outside the connector. Second, because the tabs may couple together ground planes within the printed circuit board, the shield may reduce any difference in voltage between the ground planes and prevent at least some electromagnetic emissions caused by ground current from radiating outside the connector. By reducing undesirable electromagnetic emissions from the connector, the present invention helps manufacturers avoid multiple design iterations and often costly product-level electromagnetic emission fixes, while allowing manufacturers and equipment operators to meet signal integrity and regulatory requirements. Other technical advantages are readily apparent to those skilled in the art.
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Anderson Michael G.
Lutz, Jr. Ronald D.
Baker & Botts L.L.P.
Cisco Technology Inc.
Nasri Javaid
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