Patent Application
20090221180
The present invention relates to high speed electrical connectors. In particular, the present invention relates to electrical termination devices that can be used in these high speed electrical connectors to facilitate high signal line density and shielded controlled impedance (SCI) for the signal lines.
Interconnection of integrated circuits to other circuit boards, cables or electronic devices is known in the art. Such interconnections typically have not been difficult to form, especially when the signal line densities have been relatively low, and when the circuit switching speeds (also referred to as edge rates or signal rise times) have been slow when compared to the length of time required for a signal to propagate through a conductor in the interconnect or in the printed circuit board. As user requirements grow more demanding with respect to both interconnect sizes and circuit switching speeds, the design and manufacture of interconnects that can perform satisfactorily in terms of both physical size and electrical performance has grown more difficult.
Connectors have been developed to provide the necessary impedance control for high speed circuits, i.e., circuits with a transmission frequency of at least 5 GHz. Although many of these connectors are useful, there is still a need in the art for connector designs having increased signal line densities with closely controlled electrical characteristics to achieve satisfactory control of the signal integrity.
In one aspect, the present invention provides an electrical termination device including an electrically conductive shield element, an insulator disposed within the shield element, and one or more electrical contacts. The one or more electrical contacts are supported within and electrically isolated from the shield element by the insulator, and are configured for making electrical connections through a front end and back end of the shield element. The insulator includes one or more first keying elements configured to orient and retain the one or more electrical contacts in the insulator.
In another aspect, the present invention provides an electrical connector including an electrical cable, one or more electrical contacts, an insulator disposed around the one or more electrical contacts, and an electrically conductive shield element. The electrical cable includes one or more conductors and a ground shield surrounding the one or more conductors. The one or more electrical contacts are connected to the one or more conductors. The electrically conductive shield element is disposed around the insulator and connected to the ground shield. The insulator includes one or more first keying elements configured to orient and retain the one or more electrical contacts in the insulator.
In another aspect, the present invention provides an insulator having one or more first keying elements configured to orient and retain one or more electrical contacts in the insulator and configured to prevent assembly of the insulator into an electrically conductive shield element when the one or more electrical contacts are incorrectly oriented in the insulator. The one or more first keying elements may be configured to prevent the one or more electrical contacts from rotating in the insulator when the one or more electrical contacts and the insulator are in a correctly assembled configuration.
The above summary of the present invention is not intended to describe each disclosed embodiment or every implementation of the present invention. The Figures and detailed description that follow below more particularly exemplify illustrative embodiments.
In the following detailed description of the preferred embodiments, reference is made to the accompanying drawings that form a part hereof. The accompanying drawings show, by way of illustration, specific embodiments in which the invention may be practiced. It is to be understood that other embodiments may be utilized, and structural or logical changes may be made without departing from the scope of the present invention. The following detailed description, therefore, is not to be taken in a limiting sense, and the scope of the invention is defined by the appended claims.
Referring to FIGS. 1 and 2A-2D, electrically conductive shield element 40 has a front end 46, a back end 48, and side surfaces 50a-50d (collectively referred to herein as “sides 50”) defining a non-circular transverse cross-section. Although the illustrated embodiment includes four sides 50 defining a substantially square transverse cross-section, shield element 40 may have other numbers of sides defining other generally rectangular or non-circular transverse cross-sections. In other embodiments, shield element 40 may have a generally curvilinear (such as, e.g., a circular) transverse cross-section. As illustrated, shield element 40 includes laterally protruding resilient ground contact beams 52 disposed on opposed side surfaces 50a and 50c. In other embodiments, shield element 40 includes only a single ground contact beam 52. A latch member 54 extends from at least one of sides 50. Latch member 54 is configured to retain termination device 12 in a retainer or organizer plate (not shown) configured to receive, secure, and manage a plurality of electrical termination devices. In one embodiment, latch member 54 is designed to yield (i.e., deform) at a lower force than required to break the attached electrical cable 20, so that an electrical termination device 12 can be pulled out of the retainer or organizer plate for the purpose of replacing or repairing an individual electrical termination device and cable assembly. In the illustrated embodiment of
Referring now to FIGS. 1 and 3A-3I, insulator 42 according to an aspect of the present invention includes a first insulative member 70 disposed within shield element 40 adjacent front end 46, and a second insulative member 72 disposed within shield element 40 adjacent back end 48. First and second insulative members 70, 72 are configured to provide structural support to insulator 42. In this embodiment, a spacer bar 74 is provided that properly positions and spaces first and second insulative members 70, 72 with respect to each other. The first and second insulative members 70, 72 and spacer bar 74 are shaped to receive an electrical contact 44 and are configured for slidable insertion into shield element 40, such that electrical contact 44 lies substantially parallel to a longitudinal axis of shield element 40. The first and second insulative members 70, 72 and spacer bar 74 are configured to guide electrical contact 44 during its insertion into insulator 42. In this configuration, electrical termination device 12 can serve as a coaxial electrical termination device, whereby electrical contact 44 can be connected, e.g., to a single coaxial cable.
In another embodiment, one or more spacer bars 74 are shaped to receive two electrical contacts 44 and are configured for slidable insertion into shield element 40, such that two electrical contacts 44 lie substantially parallel to a longitudinal axis of shield element 40. One or more spacer bars 74 are configured to guide two electrical contacts 44 during their insertion into insulator 42. In this configuration, electrical termination device 12 can serve as a twinaxial electrical termination device, whereby two electrical contacts 44 can be connected, e.g., to a single twinaxial cable.
Insulator 42 further includes a first keying element 76 configured to orient and retain electrical contact 44 in insulator 42. In one aspect, retaining electrical contact 44 in insulator 42 prevents substantial movement of electrical contact 44 in a direction substantially parallel to a longitudinal axis of electrical contact 44. In one embodiment, electrical contact 44 includes a second keying element 78 configured to engage with first keying element 76 when electrical contact 44 and insulator 42 are in a correctly assembled configuration. First keying element 76 may be configured to prevent electrical contact 44 from rotating in insulator 42 when electrical contact 44 and insulator 42 are in a correctly assembled configuration.
In a preferred embodiment, spacer bar 74 and first keying element 76 are shaped and positioned relative to one or more electrical contacts 44 and shield element 40 such that air is the major dielectric material surrounding one or more electrical contacts 44, so as to lower the effective dielectric constant of electrical termination device 12 and thereby lower the characteristic impedance of the electrical termination device and cable assembly closer to the desired target value, such as, for example, 50 ohms.
In the embodiment illustrated in
Still referring to FIGS. 1 and 3A-3I, insulator 42 has a front end 94, a back end 96, and outer surfaces 98a-98d (collectively referred to herein as “outer surface 98”) defining a non-circular shape. Although the illustrated embodiment includes an outer surface 98 defining a substantially square shape, insulator 42 may have an outer surface 98 defining other suitable shapes, including generally rectangular, non-circular, or curvilinear (such as, e.g., circular) shapes.
Insulator 42 can be formed of any suitable material, such as, e.g., a polymeric material, by any suitable method, such as, e.g., injection molding, machining, or the like.
In one embodiment, insulator 42 and one or more first keying elements 76 may be monolithic. For example, insulator 42 and first keying elements 76 may be injection molded as a monolithic structure. In another embodiment, insulator 42 and one or more first keying elements 76 may comprise separate elements, assembled by any suitable method or structure, including but not limited to snap fit, friction fit, press fit, mechanical clamping, and adhesive. For example, insulator 42 may be injection molded and one or more first keying elements 76 may be machined and assembled to insulator 42 by press fit.
In one embodiment, electrical termination device 12 is configured for termination of an electrical cable 20, such that a conductor 90 of electrical cable 20 is attached to electrical contact 44 and ground shield 92 of electrical cable 20 is attached to shield element 40 of electrical termination device 12 using conventional means, such as soldering. The type of electrical cable used in an aspect of the present invention can be a single wire cable (e.g., single coaxial or single twinaxial) or a multiple wire cable (e.g., multiple coaxial, multiple twinaxial, or twisted pair). In one embodiment, prior to attaching one or more electrical contacts 44 to one or more conductors 90 of electrical cable 20, ground shield 92 is stiffened by a solder dip process. After one or more electrical contacts 44 are attached to one or more conductors 90, the one or more electrical contacts 44 are slidably inserted into insulator 42. The prepared end of electrical cable 20 and insulator 42 are configured such that the stiffened ground shield 92 bears against back end 96 of insulator 42 prior to one or more electrical contacts 44 being fully seated against front end 94 of insulator 42. Thus, when insulator 42 (having one or more electrical contacts 44 therein) is next slidably inserted into shield element 40, the stiffened ground shield 92 acts to push insulator 42 into shield element 40, and one or more electrical contacts 44 are prevented from pushing against insulator 42 in the insertion direction. In this manner, one or more electrical contacts 44 are prevented from being pushed back into electrical cable 20 by reaction to force applied during insertion of insulator 42 into shield element 40, which may prevent proper connection of one or more electrical contacts 44 with a header. In one embodiment, and as can be seen in
In one embodiment, electrical termination device 12 includes two electrical contacts 44 and is configured for termination of an electrical cable 20 including two conductors 90. Each conductor 90 of electrical cable 20 is connected to an electrical contact 44 of electrical termination device 12, and ground shield 92 of electrical cable 20 is attached to shield element 40 of electrical termination device 12 using conventional means, such as soldering. The type of electrical cable used in this embodiment can be a single twinaxial cable.
In each of the embodiments and implementations described herein, the various components of the electrical termination device and elements thereof are formed of any suitable material. The materials are selected depending upon the intended application and may include both metals and non-metals (e.g., any one or combination of non-conductive materials including but not limited to polymers, glass, and ceramics). In one embodiment, insulator 42 is formed of a polymeric material by methods such as injection molding, extrusion, casting, machining, and the like, while the electrically conductive components are formed of metal by methods such as molding, casting, stamping, machining, and the like. Material selection will depend upon factors including, but not limited to, chemical exposure conditions, environmental exposure conditions including temperature and humidity conditions, flame-retardancy requirements, material strength, and rigidity, to name a few.
Although specific embodiments have been illustrated and described herein for purposes of description of the preferred embodiment, it will be appreciated by those of ordinary skill in the art that a wide variety of alternate and/or equivalent implementations calculated to achieve the same purposes may be substituted for the specific embodiments shown and described without departing from the scope of the present invention. Those with skill in the mechanical, electromechanical, and electrical arts will readily appreciate that the present invention may be implemented in a very wide variety of embodiments. This application is intended to cover any adaptations or variations of the preferred embodiments discussed herein. Therefore, it is manifestly intended that this invention be limited only by the claims and the equivalents thereof.
