Patent Grant
7731528
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 insulative spacer bars configured to guide the one or more electrical contacts during their insertion into the insulator. The insulator may be positioned away from the one or more electrical contacts along at least a major portion of the length of the one or more electrical contacts in an impedance controlling relationship.
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 insulative spacer bars configured to guide the one or more electrical contacts during their insertion into the insulator.
In another aspect, the present invention provides an insulator having one or more insulative spacer bars configured to guide one or more electrical contacts during their insertion into the insulator. The one or more spacer bars may be configured to enable straight pull injection molding of the insulator. The insulator may be positioned away from the one or more electrical contacts along at least a major portion of the length of the one or more electrical contacts configured to enable an impedance controlling relationship when the insulator and the one or more electrical contacts are in an 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, the 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 one or more insulative spacer bars 74. One or more spacer bars 74 are shaped to receive one or more electrical contacts 44 (
A significant advantage of an insulator according to an aspect of the present invention is its skeletonized configuration. A skeletonized configuration, e.g., such as described above, enables the insulator to have an effective dielectric constant of a value close to the dielectric constant of air, which is 1, even though a material with a higher dielectric constant is used to form the insulator. A low effective dielectric constant of insulator 42 allows for more freedom in designing and tolerance in manufacturing electrical contact 44 and shield element 40 of electrical termination device 12 while still meeting a desired target value of the characteristic impedance of the electrical termination device and cable assembly. This can be illustrated using the equation immediately below for calculating the characteristic impedance of a coaxial cable.
Z0=(138/√{square root over (∈)})log(D/d) Equation 1
where:
Although this equation is intended specifically for coaxial cables, it generally shows the relationship between shield element 40 (represented as the inner diameter of the cable shield D), electrical contact 44 (represented as the diameter of the center conductor d), and the effective dielectric constant of insulator 42 (represented as the dielectric constant ∈). For example, in light of the continuous miniaturization of electrical connectors, a lower effective dielectric constant of insulator 42 allows for a smaller size shield element 40 and thereby a smaller size electrical termination device 12 while still meeting a desired target value of the characteristic impedance of the electrical termination device and cable assembly without the need to reduce the size of electrical contact 44. In addition, a skeletonized configuration, e.g., such as described above, enables at least a substantial portion of the total mass of insulator 42 to be positioned away from one or more electrical contacts 44 (i.e., positioned closer to shield element 40 than to one or more electrical contacts 44) along at least a major portion of the length of one or more electrical contacts 44 in an impedance controlling relationship. An impedance controlling relationship means that one or more electrical contacts 44, insulator 42, and shield element 40 are cooperatively configured to control the characteristic impedance of the electrical termination device and cable assembly. This would bring at least a substantial portion of the total mass of insulator 42 in an area where the electric field strength is lowest, which enables the insulator to have an effective dielectric constant of a value close to the dielectric constant of air, which is 1, even though a material with a higher dielectric constant is used to form the insulator. This can be illustrated using the equation immediately below for calculating the effective dielectric constant in an air gap type coaxial cable (i.e. a coaxial cable having an “air supported dielectric”).
where:
Although this equation is intended specifically for air gap type coaxial cables, it generally shows the relationship between shield element 40 (represented as the inner diameter of the cable shield D3), electrical contact 44 (represented as the diameter of the center conductor d), and the effective dielectric constant of insulator 42 (represented as the effective dielectric constant ∈r). Positioning at least a substantial portion of the total mass of insulator 42 away from electrical contact 44 (i.e., closer to shield element 40 than to electrical contact 44) reduces the effective dielectric constant of insulator 42, allowing for more freedom in designing and tolerance in manufacturing electrical contact 44 and shield element 40 of electrical termination device 12 while still meeting a desired target value of the characteristic impedance of the electrical termination device and cable assembly.
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.
In the exemplary embodiment of FIGS. 1 and 3A-3I, insulator 42 further 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, three spacer bars 74 are provided that properly position and space first and second insulative members 70, 72 with respect to each other. The first and second insulative members 70, 72 and three spacer bars 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 three spacer bars 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.
In other embodiments, insulator 42 may include two or more mating insulator parts (not shown). Each insulator part may be separately formed or may be integrally hinged in a clamshell fashion to facilitate injection molding or machining and to provide an ease of assembly of one or more electrical contacts 44. The two or more mating insulator parts can be assembled using any suitable method/structure, including but not limited to snap fit, friction fit, press fit, mechanical clamping, and adhesive. In one exemplary embodiment, insulator 42 may include two mating insulator parts, each insulator part extending longitudinally along the length of one or more electrical contacts 44. In another exemplary embodiment, insulator 42 may include two mating insulator parts, each insulator part, which may be hermaphroditic, encompassing substantially one-half the length of one or more electrical contacts 44.
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 is formed by straight pull injection molding, whereby the one or more spacer bars 74 of insulator 42 are configured to enable straight pull injection molding of insulator 42. An advantage of straight pull injection molding is that a straight pull injection mold, as opposed to a side core pull injection mold, can be used to form insulator 42. Generally, a straight pull injection mold requires significantly less precision to manufacture, is significantly less expensive to manufacture (about 25-30%), and requires a significantly less expensive injection molding machine to operate than more the more complex side core pull injection molds. Particularly when making an injection mold with multiple cavities, the cams in a side core pull injection mold are difficult to implement between cavities and cause a significant increase in size and weight of the mold. In addition, straight pull injection molds can generally achieve higher production capacities because they can be made smaller than side core pull injection molds, require less maintenance, and are less likely to malfunction.
In the embodiment illustrated in
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 end 72 of insulator 42 prior to one or more electrical contacts 44 being fully seated against end 70 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, 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 one embodiment, second insulative member 72 of insulator 42, at least a portion of electrical cable 20, and at least a portion of one or more electrical contacts 44 are cooperatively configured in an impedance controlling relationship. For example, referring to the embodiment illustrated in
In one embodiment, first and second insulative members 70, 72 and spacer bars 74 of insulator 42 are configured to provide an open path between the area of shield element 40 to be soldered to ground shield 92 and the area under latch 54 of shield element 40, such that solder flux vapor may be vented during soldering.
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 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, electro-mechanical, 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.
This application is a continuation-in-part of U.S. patent application Ser. No. 11/627,258, filed Jan. 25, 2007, now U.S. Pat. No. 7,553,187, which claims priority to U.S. Provisional Patent Application No. 60/763,733, filed Jan. 31, 2006 and U.S. Provisional Patent Application No. 60/824,332, filed Sep. 1, 2006. The disclosures of each of the aforementioned Applications are incorporated by reference herein in their entirety.
| Number | Name | Date | Kind |
|---|---|---|---|
| 5046960 | Fedder | Sep 1991 | A |
| 5063659 | Wright | Nov 1991 | A |
| 5116230 | Dechelette et al. | May 1992 | A |
| 5184965 | Myschik et al. | Feb 1993 | A |
| 5194020 | Voltz | Mar 1993 | A |
| 5222898 | Fedder et al. | Jun 1993 | A |
| 5431578 | Wayne | Jul 1995 | A |
| 5554050 | Marpoe, Jr. | Sep 1996 | A |
| 5647766 | Nguyen | Jul 1997 | A |
| 5766036 | Ahmad et al. | Jun 1998 | A |
| 5938476 | Wu et al. | Aug 1999 | A |
| 5964621 | Wolla et al. | Oct 1999 | A |
| 5975950 | Yamaguchi | Nov 1999 | A |
| 6146202 | Ramey et al. | Nov 2000 | A |
| 6203369 | Feldman | Mar 2001 | B1 |
| 6231391 | Ramey et al. | May 2001 | B1 |
| 6257931 | Sakurai et al. | Jul 2001 | B1 |
| 6368120 | Scherer et al. | Apr 2002 | B1 |
| 6371813 | Ramey et al. | Apr 2002 | B2 |
| 6498506 | Beckous | Dec 2002 | B1 |
| 6524135 | Feldman et al. | Feb 2003 | B1 |
| 6533609 | Koide | Mar 2003 | B2 |
| 6540565 | Babel et al. | Apr 2003 | B2 |
| 6688920 | Lehner et al. | Feb 2004 | B2 |
| 6743050 | Wu | Jun 2004 | B1 |
| 6764350 | Kosmala | Jul 2004 | B2 |
| 6780068 | Bartholoma et al. | Aug 2004 | B2 |
| 6780069 | Scherer et al. | Aug 2004 | B2 |
| 6824427 | Feldman et al. | Nov 2004 | B1 |
| 6830480 | Yoshioka | Dec 2004 | B2 |
| 6849799 | Springer et al. | Feb 2005 | B2 |
| 6929507 | Lin | Aug 2005 | B2 |
| 6971916 | Tokunaga | Dec 2005 | B2 |
| 7021963 | Feldman | Apr 2006 | B2 |
| 7044789 | Yohn et al. | May 2006 | B2 |
| 7044793 | Takemasa | May 2006 | B2 |
| 7134911 | Bernhart et al. | Nov 2006 | B2 |
| 7331821 | Feldman | Feb 2008 | B2 |
| 7553187 | Feldman et al. | Jun 2009 | B2 |
| 20050054237 | Gladd et al. | Mar 2005 | A1 |
| 20080020615 | Feldman et al. | Jan 2008 | A1 |
| Number | Date | Country |
|---|---|---|
| 41 16 166 | May 1991 | DE |
| 0 570 181 | Nov 1993 | EP |
| 8096864 | Apr 1996 | JP |
| 10335008 | Dec 1998 | JP |
| 11074037 | Mar 1999 | JP |
| 2000040563 | Feb 2000 | JP |
| 2000-067980 | Mar 2000 | JP |
| 2002319458 | Oct 2002 | JP |
| 2002334764 | Nov 2002 | JP |
| WO 2006120373 | Nov 2006 | WO |
| Number | Date | Country | |
|---|---|---|---|
| 20080020615 A1 | Jan 2008 | US |
| Number | Date | Country | |
|---|---|---|---|
| 60763733 | Jan 2006 | US | |
| 60824332 | Sep 2006 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 11627258 | Jan 2007 | US |
| Child | 11830703 | US |
