Electrical connectors – With guiding means for mating of coupling part – Rodlike guide member extending in coupling direction or...
Reexamination Certificate
1997-09-30
2002-12-17
Ta, Tho D. (Department: 2833)
Electrical connectors
With guiding means for mating of coupling part
Rodlike guide member extending in coupling direction or...
C439S284000, C439S717000, C439S607560
Reexamination Certificate
active
06494734
ABSTRACT:
The present invention relates generally to electrical connectors and more particularly, to a connector assembly comprising a receptacle and a header, having a high signal density and enhanced signal carrying capability.
BACKGROUND OF THE INVENTION
As electronic circuits and components become increasingly miniaturized, the demand for electrical connectors to electrically and mechanically interconnect a first PCB, such as a back panel or mother board, to a second PCB, such as a daughter board has also increased. As existing and additional components are enhanced or added to circuit boards, the electrical connectors that interconnect the circuit boards must accommodate the resulting additional connections. Further, as clock speeds increase other demands are being placed on the electrical connectors that interconnect circuit boards.
Typically, high density connectors have a signal density of 50-65 signals per inch of connector. Conventional techniques to increase signal density have been directed to minimizing the amount of space occupied by each receptacle or contact of the connector assembly. However, closely spaced electrical signals can interfere with one another. The interference phenomenon is referred to as “cross talk.” Density and pin count are often viewed interchangeably, but there are important differences. Density refers to the number of contacts provided per unit length. In contrast, the number of contact elements that can reasonably withstand the mating and unmating forces is referred to as the pin count.
As more functions become integrated on semiconductor chips or on flexible circuit substrates and more chips are provided on printed circuit boards (PCBs), each PCB or flexible circuit must provide more inputs and outputs (I/Os). The demand for more I/Os directly translates to a demand for greater density. In addition, many system components are capable of operation at faster speeds than previously. Faster speed can result in the generation of potentially interfering signals, i.e., crosstalk and noise. The connectors used in such high-speed board-to-board, board-to-cable and cable-to-cable communications may be treated for design purposes like transmission lines in which crosstalk and noise become significant concerns. Indeed, the electrical performance of high-speed board-to-board, board-to-cable and cable-to-cable communications is dependent upon the amount of crosstalk and noise introduced at the connector interface.
One method of controlling cross talk is to connect certain terminals of the high density connector to grounded conductive areas of a printed circuit board. This solution is provided externally to the connector and provides for flexibility of design. In particular, a designer may configure the number of grounds and/or signals passed by the connector based on the particulars of the connections to the printed circuit board.
For example, U.S. Pat. No. 4,900,258, to Hnatuck et al., entitled “Multi-port Coaxial Printed Circuit Board Connector”, discloses a connector having plural coaxial subassemblies. Each coaxial subassembly is provided with a center contact for passing a signal and an outer contact which is connected to ground. The individual coaxial subassemblies are arranged in rows and columns within the connector assembly which is then mounted at a right angle to a motherboard.
U.S. Pat. No. 5,547,385, to Spangler, entitled “Blind Mating Guides on Backwards Compatible Connector”, discloses an electrical connector assembly comprising a first electrical connector having alignment posts which mate with receiving cavities provided in a second mating electrical connector. The ground contacts which extend from the first connector are longer than the signal contacts so the ground contacts engage respective conductors in the mating electrical connector prior to the signal contacts engaging their respective conductors in order to discharge electrostatic charge to a chassis ground.
According to another method of controlling cross talk, conductive material is disposed between rows and/or columns of signal carrying terminals in the high density connector. The conductive material is generally separated from the signal leads by a dielectric material such as plastic. According to this method, the conductive material is connected to a corresponding grounded conductive area of the printed circuit board. Such connectors have been termed in the art as strip-line or micro-strip connectors. Unlike the first method above, this solution is provided within the connector itself.
For example, U.S. Pat. No. 4,705,332, to Sadigh-Behzadi, entitled “High Density, Controlled Impedance Connectors”, discloses a modular connector where discrete wafers having signal carrying conductors are stacked together. The discrete wafers are formed having multiple signal carrying contact elements which may be mounted at a right angle to a mother board or daughter board. Locating pins are provided, which are received by apertures in the mother board. Between each wafer is a planar ground element such that a strip line configuration is created.
U.S. Pat. No. 4,806,107, to Arnold et al., entitled “High Frequency Connector” discloses a strip line type connector having ground plates that extend from the connector. The ground plates are inserted into a complementary connector and are formed by bending single metal sheets into a U-shape. The extending portion of the U-shaped metal sheet form pairs of ground plates. A flexible connector attached near the base of the “U” is connected to a ground contact on a mother board.
U.S. Pat. No. 5,632,635, to VanBesien et al., entitled “Electrical Connector Array”, discloses an electrical connector array having a plurality of signal contacts separated by a ground strip. The ground strip is provided with connection points which are spaced in an manner to minimally affect the particular routing of the connector.
In addition to the above-mentioned methods of controlling cross talk, the dielectric material used to separate conductive leads may affect cross talk by altering the characteristic impedance of the connector. Conventionally, non-conductive materials such as plastic are used as a dielectric to insulate regions between conductors within a connector.
For example, U.S. Pat. No. 4,070,048, to Hutchinson, entitled “Controlled Impedance Connector”, discloses a connector for a computer backplane or printed circuit board where the signal carrying conductors are embedded in a dielectric block. A metallic foil is provided as a ground plane between rows of right angle pins. The metallic foil is connected with ground pins which are spaced apart in the connector assembly and are used as a reference to all signal carrying conductors and to obtain a desired impedance. Hutchinson also discloses embedding a flexible micro strip having signal carrying conductors and a ground plane within the dielectric block. Ground reference sockets, provided at each corner, are connected to the round plane on the micro strip.
While the prior art teaches connectors having a high pin count, the prior art connectors fails to teach a connector having a signal density which meets the demands of ever-increasing miniaturization of printed circuit boards. The prior art also fails to address increasing signal density by eliminating space consuming dielectric and insulative elements from the header array, such as plastic slots into which circuit cards are inserted. Moreover, the prior art fails to adequately address the problem of increased insertion forces that are generated and sequential mating concerns when a large number of header contacts are inserted into a receptacle. Still further, the prior art fails to teach a connector that uses air as a dielectric material to insulate signal leads while adequately reducing cross talk and maintaining a proper characteristic impedance.
SUMMARY OF THE INVENTION
In view of the above, the present invention, through one or more of its various aspects and/or embodiments is thus presented to accomplish one or more objects and advantages, such as those noted belo
FCI Americas Technology Inc.
Hammond Briggitte R.
Ta Tho D.
Woodcock & Washburn LLP
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