The present invention relates generally to interconnections made between a printed circuit board and one or more electrical cables carrying signals to and from the printed circuit board.
The interconnection of printed circuit boards to other circuit boards, cables, or other electronic devices is well known in the art. Such interconnections typically have not been difficult to form, especially when the circuit switching speeds (also referred to as signal transition times) have been slow when compared to the length of time required for a signal to propagate through a conductor in the interconnect or on the printed circuit board. However, as circuit switching speeds continue to increase with modern integrated circuits and related computer technology, the design and fabrication of satisfactory interconnects has grown more difficult.
Specifically, there is a continued and growing need to design and fabricate printed circuit boards and their accompanying interconnects with closely controlled electrical characteristics to achieve satisfactory control over the integrity of the signal as it travels through the interconnect to and from the printed circuit board. The extent to which electrical characteristics (such as impedance) of the interconnect must be controlled depends heavily upon the switching speed of the circuit. That is, the faster the circuit switching speed, the greater the importance of providing an accurately controlled impedance within the interconnect.
Connector systems developed for high-speed board-to-board and board-to-cable interconnect applications are replete in the art. In general, an optimum printed circuit board interconnect design minimizes the length of marginally controlled signal line characteristic impedance by minimizing the physical spacing between the printed circuit board and the connector. Also, connector designs which involve relatively large pin and socket connectors with multiple pins devoted to power and ground contacts provide only marginally acceptable performance for high speed printed circuit boards.
Unfortunately, currently available high speed interconnect solutions for board-to-cable applications are typically complex, requiring extremely accurate component designs which are very sensitive to even small manufacturing variations and which, as a result, are expensive and difficult to manufacture. Even then, the performance of the available board-to-cable interconnect systems is becoming only marginally acceptable as switching speeds continue to increase. What is needed is a printed circuit board-to-cable interconnect system that provides the necessary impedance control for high speed integrated circuits while still being inexpensive and easy to manufacture.
In one aspect, the present invention provides a carrier for use with an electrical connector assembly. The carrier includes an insulating housing having a front exterior wall on which a plurality of contact pin insertion apertures is disposed. The insulating housing further includes side exterior walls laterally extending from the front exterior wall. A plurality of first apertures is disposed on at least one of the side exterior walls. Each first aperture is configured to receive a first external electrical cable termination ground contact. The insulating housing further includes a plurality of interior walls laterally extending from the front exterior wall. Each of the plurality of interior walls includes a second aperture configured to receive a second external electrical cable termination ground contact. Optionally, the insulating housing may include a first housing part and a second housing part.
In another aspect, the present invention provides an electrical connector assembly including a printed circuit board having a printed circuit board ground contact, a header coupled to the printed circuit board and comprising a plurality of contact pins, a carrier, and a plurality of electrical cable terminations retained by the carrier. The carrier includes an insulating housing having a front exterior wall on which a plurality of contact pin insertion apertures is disposed. The insulating housing further includes side exterior walls laterally extending from the front exterior wall. A plurality of first apertures is disposed on at least one of the side exterior walls. Each first aperture is configured to receive a first external electrical cable termination ground contact. The insulating housing further includes a plurality of interior walls laterally extending from the front exterior wall. Each of the plurality of interior walls includes a second aperture configured to receive a second external electrical cable termination ground contact. The header and electrical cable terminations are configured such that each of the plurality of electrical cable terminations makes electrical contact with one or more of the contact pins and printed circuit board ground contact when the header and carrier are in a mated configuration.
In another aspect, the present invention provides an electrical connector assembly including a printed circuit board having a printed circuit board ground contact, a header coupled to the printed circuit board and comprising a plurality of contact pins and a plurality of ground elements, a carrier, and a plurality of electrical cable terminations retained by the carrier. The carrier includes an insulating housing having a front exterior wall on which a plurality of contact pin insertion apertures and a plurality of ground element insertion apertures are disposed. The insulating housing further includes side exterior walls laterally extending from the front exterior wall. A plurality of first apertures is disposed on at least one of the side exterior walls. Each first aperture is configured to receive a first external electrical cable termination ground contact. The insulating housing further includes a plurality of interior walls laterally extending from the front exterior wall. Each of the plurality of interior walls includes a second aperture configured to receive a second external electrical cable termination ground contact. The header and electrical cable terminations are configured such that each of the plurality of electrical cable terminations makes electrical contact with one or more of the contact pins, ground elements, and printed circuit board ground contact when the header and carrier are in a mated 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 and their equivalents.
For purpose of clarity, aspects of the invention are described and illustrated herein as used with twinaxial cables and twinaxial cable terminations. However, such illustration is exemplary only, and it is understood and intended that other types of electrical cables and their associated electrical cable terminations can be used, including but not limited to coaxial cables and other cable configurations with signal and ground elements. It is further understood and intended that different types and configurations of electrical cables and electrical cable terminations may be used simultaneously with electrical connector assemblies according to aspects of the present invention. For example, a portion of electrical cable terminations retained by a carrier may be twinaxial cable terminations, while another portion of electrical cable terminations retained by a carrier may be coaxial cable (or other) terminations.
Referring to
Printed circuit board 102 is substantially conventional in design except for the addition of a printed circuit board ground contact. In the exemplary embodiment of
Header 104 and electrical cable terminations 108 may be configured such that each of the plurality of electrical cable terminations 108 makes electrical contact with one or more of contact pins 114 of header 104 and a printed circuit board ground contact when header 104 and carrier 106 are in a mated configuration. In the exemplary embodiment of
Referring to
Each electrical cable termination 108 is retained within its respective cavity 142 by a resilient latch 144 present in each cavity 142. As an electrical cable termination 108 is inserted into its respective cavity 142, a front edge 108b (as shown in
In one embodiment, carrier 106 further includes a wedge element 118 configured to secure the plurality of latch 144 and help retain the plurality of electrical cable terminations 108, as shown in
In other embodiments, electrical cable terminations 108 may be retained within carrier 106 by any suitable method/structure, including but not limited to snap fit, friction fit, press fit, mechanical clamping, and adhesive. Further, the method/structure used to retain electrical cable terminations 108 within carrier 106 may permit electrical cable terminations 108 to be removed individually, such as described above, the method/structure used to retain electrical cable terminations 108 within carrier 106 may permit electrical cable terminations 108 to be removed as a set, or the method/structure used to retain electrical cable terminations 108 within carrier 106 may permanently secure electrical cable terminations 108 within carrier 106. In other embodiments, cavities 142 of insulating housing 122 may be configured to receive more than one or all of the electrical cable terminations 108.
Each interior wall 128 of insulating housing 122 has an aperture 130 configured to receive a second external electrical cable termination ground contact 158, described in further detail below and illustrated in
In one embodiment, side exterior walls 126b and 126d of insulating housing 122 include cooperative latch elements 136 configured to retain first insulating housing part 122a and second insulating housing part 122b in an assembled configuration. In the embodiment illustrated in
Electrical cable terminations that can be used in conjunction with carrier 106 can be constructed substantially similar to the shielded controlled impedance (SCI) connectors for a coaxial cable described in U.S. Pat. No. 5,184,965, incorporated by reference herein. In particular, an exemplary embodiment of an electrical cable termination that can be used in conjunction with carrier 106 is shown in
Electrical cable termination 108 further includes a first external electrical cable termination ground contact 156. First external electrical cable termination ground contact 156 extends from an external surface of conductive housing 152 and is configured to make electrical contact with a ground contact of a printed circuit board. In the exemplary embodiment of an electrical connector assembly shown in
Electrical cable termination 108 further includes a second external electrical cable termination ground contact 158 extending from an external surface of conductive housing 152. In the exemplary embodiment of an electrical connector assembly shown in
In the illustrated embodiments, both first external electrical cable termination ground contacts 156 and second external electrical cable termination ground contacts 158 include resilient beams extending from conductive housing 152. In other embodiments, first external electrical cable termination ground contacts 156 and/or second external electrical cable termination ground contacts 158 can take alternate forms from those illustrated, and may include, for example, a Hertzian bump extending from conductive housing 152.
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).
Conductor 212 may be made of a various conductive materials, including bare copper, tinned copper, silver plated copper, copper-covered steel, aluminum, or other suitable materials. Also, conductor 212 may be either a stranded or a solid element. In the case of a stranded element, conductor 212 is made of a plurality of electrically engaged conductive strands.
Electrical cable 210 is used in high frequency signal applications, such as those greater than 100 MHz. As described above, as signal frequency increases, the resistance of a conductor increases due to skin effect. Skin effect describes a condition where, due to magnetic fields produced by current flowing through the conductor, there is a concentration of current near the conductor surface. To maximize the surface area at the conductor surface, conductor 212 has a substantially oblong curvilinear cross-section. A substantially oblong curvilinear cross-section includes any elongated shape having rounded sides including, but not limited to, ovate, elliptical, capsule-shaped, and egg-shaped cross-sections. Because the substantially oblong curvilinear cross-section increases the surface area at the surface of conductor 212 over a conventional cylindrical conductor, the skin effect is minimized because more current flows along the larger surface. As a result, the signal attenuation characteristics of electrical cable 210 are improved since the overall resistance of conductor 212 is decreased.
In addition, in conventional approaches to improving the signal attenuation characteristics of electrical cables, larger cylindrical conductor diameters are used to compensate for the increase in resistance at higher frequencies. Larger inner conductor diameter sizes typically require larger volumes of dielectric surrounding the conductor to maintain desired cable impedance. This increases the overall size of the cable and prevents the cable from being used with standard micro-connectors used in high frequency systems. The substantially oblong curvilinear cross-section of conductor 212 allows electrical cable 210 to be used with existing cable connectors. In particular, conductor 212 permits a larger thousand circular mils (MCM) gauge equivalent conductor to fit into the height space restrictions of existing micro-connectors. The larger gauge conductor 212 also demonstrates better electrical performance (e.g., improved eye opening) due to improved rise time degradation characteristics.
Dielectric sheath 214 is formed around conductor 212 to provide insulation between conductor 212 and metallic shield 216. The thickness of dielectric sheath 214 is adjustable to control the impedance of electrical cable 210, since the thickness of dielectric sheath 214 controls the spacing between conductor 212 and metallic shield 216. In one embodiment, dielectric sheath 214 is extruded over conductor 212. In another embodiment, dielectric sheath 214 is a tape or wrap made of a dielectric material. Exemplary materials that may be used for dielectric sheath 214 include polyvinyl chloride (PVC), fluoropolymers including perfluoroalkoxy (PFA), fluorinated ethylene propylene (FEP), and foamed fluorinated ethylene propylene (FFEP), and polyolefins such as polyethylene (PE), foamed polyethylene (FPE), polypropylene (PP), and polymethyl pentane. In an alternative embodiment, dielectric sheath 214 may comprise a dielectric tube and a solid core filament spacer to define an air core surrounding conductor 212, such as that shown and described in U.S. Pat. No. 6,849,799, assigned to 3M Innovative Properties Company, St. Paul, Minn., which is herein incorporated by reference.
Metallic shield 216 is formed around dielectric sheath 214 to shield conductor 212 from producing external electromagnetic interference (EMI). Metallic shield 216 also helps to prevent signal interference from electromagnetic and electrostatic fields outside of electrical cable 210. Furthermore, metallic shield 216 provides a continuous ground for electrical cable 210. In one embodiment, the interior surface of metallic shield 216 is an equal distance d from conductor 212 around the entire periphery of conductor 212, as shown in
Jacket 218 is formed around metallic shield 216 and provides a protective coating for electrical cable 210 and support for the components of electrical cable 210. Jacket 218 also insulates the components of electrical cable 210 from external surroundings. When jacket 218 is formed around metallic shield 216, outer surfaces 226 and 228 are substantially planar and parallel with surfaces 222 and 224 of conductor 212. Electrical cable 210 has a low profile in that the distance between surfaces 226 and 228 is less than the distance between the curved outer surfaces of electrical cable 210. This low profile allows electrical cable 210 to be used in applications having confined spaces or minimal amounts of extra space. Jacket 218 may be made of a flexible rubber material or a flexible plastic material, such as polyvinyl chloride (PVC), to permit installation of electrical cable 210 around obstructions and in tortuous passages. Other materials that may be used for jacket 218 include ethylene propylene diene (EPDM) elastomer, mica tape, neoprene, polyethylene, polypropylene, silicon, rubber, and fluoropolymer films available under the trade names TEFLON and TEFZEL from E.I. du Pont de Nemours and Company.
Drain wire 332 is in electrical contact with metallic shield 316. Drain wire 332 controls the impedance of electrical cable 310 by providing a method for electrical connection of metallic shield 316 to a connector. Drain wire 332 may be made of various conductive materials, including bare copper, tinned copper, silver plated copper, copper-covered steel, aluminum, or other suitable materials. Also, drain wire 332 may be either a stranded or a solid element. In the case of a stranded element, drain wire 332 is made of a plurality of electrically engaged conductive strands.
Conductors 452a and 452b may be made of various conductive materials, including bare copper, tinned copper, silver plated copper, copper-covered steel, aluminum, or other suitable materials. Also, conductors 452a and 452b may be either a stranded or a solid element. In the case of a stranded element, each conductor is made of a plurality of electrically engaged conductive strands. In one embodiment, conductors 452a and 452b are positioned relative to each other such that major axes of the substantially oblong curvilinear cross-sections of conductors 452a and 452b are coplanar (as shown in
Electrical cable 410 is used in high frequency signal applications, such as those greater than 100 MHz. As described above, to minimize the skin effect, it is desirable to maximize the surface area of each conductor at the conductor surface. To increase the surface area over conventional cylindrical conductors, conductors 452a and 452b each have a substantially oblong curvilinear cross-section. A substantially oblong curvilinear cross-section includes any elongated shape having rounded sides including, but not limited to, ovate, elliptical, capsule-shaped, and egg-shaped cross-sections. Because the substantially oblong curvilinear cross-section increases the surface area at the surface of conductors 452a and 452b over conventional cylindrical conductors, the skin effect is minimized since more current flows along the larger surface. As a result, the signal attenuation characteristics of electrical cable 410 is improved since the overall resistance of conductors 452a and 452b is decreased.
In addition, in conventional approaches to improving signal attenuation characteristics, larger cylindrical conductor diameters are used to compensate for the increase in resistance at higher frequencies. Larger conductor diameter sizes typically require larger volumes of dielectric surrounding the conductor to maintain desired cable impedance. This increases the overall size of the cable and prevents the cable from being used with standard micro-connectors used in high frequency systems. The substantially oblong curvilinear cross-sections of conductors 452a and 452b allow electrical cable 410 to be used with existing cable connectors. In particular, conductors 452a and 452b permit larger thousand circular mils (MCM) gauge equivalent conductors to fit into the height space restrictions of existing micro-connectors. The larger gauge conductors 452a and 452b also demonstrate better electrical performance (e.g., improved eye opening) due to improved rise time degradation characteristics.
Dielectric sheath 454 is formed around conductors 452a and 452b to provide insulation between conductors 452a and 452b and metal foil 456. In one embodiment, dielectric sheath 454 is extruded over conductors 452a and 452b. The thickness of dielectric sheath 454 is adjustable to control the impedance of electrical cable 410, since the thickness of dielectric sheath 454 controls the spacing between conductors 452a and 452b and metal foil 456. The orientation of and spacing between conductors 452a and 452b, which can also have an effect on the impedance of electrical cable 410, may also be controlled by the extrusion of dielectric sheath 454 over conductors 452a and 452b. Exemplary materials that may be used for dielectric sheath 454 include polyvinyl chloride (PVC), fluoropolymers including perfluoroalkoxy (PFA), fluorinated ethylene propylene (FEP), and foamed fluorinated ethylene propylene (FFEP), and polyolefins such as polyethylene (PE), foamed polyethylene (FPE), polypropylene (PP), and polymethyl pentane. In an alternative embodiment, dielectric sheath 454 may comprise a dielectric tube and a solid core filament spacer to define an air core surrounding conductors 452a and 452b, such as that shown and described in U.S. Pat. No. 6,849,799.
Metal foil 456 and metallic wire shield 457 are formed around dielectric sheath 454 to shield conductors 452a and 452b from producing external EMI. Metal foil 456 and metallic wire shield 457 also help to prevent signal interference from electromagnetic and electrostatic fields outside of electrical cable 410. The combination of metal foil 456 and metallic wire shield 457 provides excellent shielding properties. Furthermore, metal foil 456 and metallic wire shield 457 provide a continuous ground for electrical cable 410. Metal foil 456 may be comprised of a material such as copper and copper alloys. Metallic wire shield 457 may be comprised of a braided copper or copper alloys.
Jacket 458 is formed around metallic wire shield 457 and provides a protective coating for electrical cable 410 and support for the components of electrical cable 410. Jacket 458 also insulates the components of electrical cable 410 from external surroundings. Electrical cable 410 has a low profile in that the distance D1 between the planar surfaces of electrical cable 410 is less than the distance D2 between the curved outer surfaces of electrical cable 410 (see
Dielectric sheath 564 is taped or wrapped around conductors 552a and 552b to provide insulation between conductors 552a and 552b and metallic shield 556. Dielectric sheath 564 also controls the spacing between metal foil 556 and conductors 552a and 552b, the spacing between conductors 552a and 552b, and the orientation of conductors 552a and 552b. Because all of these parameters have an effect on the impedance of electrical cable 510, the impedance can be controlled by adjusting the thickness of dielectric sheath 564 and the orientation of conductors 552a and 552b held by dielectric sheath 564. Alternatively, dielectric sheath 564 may be extruded over conductors 552a and 552b, similar to dielectric sheath 454 in
Referring to
Printed circuit board 602 is substantially conventional in design except for the addition of a printed circuit board ground contact. In the exemplary embodiment of
Header 604 and electrical cable terminations 108 may be configured such that each of the plurality of electrical cable terminations 108 makes electrical contact with one or more of contact pins 614 of header 604 and a printed circuit board ground contact when header 604 and carrier 106 are in a mated configuration. In the exemplary embodiment of
In the exemplary embodiment of an electrical connector assembly shown in
In one embodiment, header 704 and carrier 106 include cooperative latch elements 780 configured to retain header 704 and carrier 106 in a mated configuration. In the embodiment of
Referring to
Header 704 and electrical cable terminations 108 may be configured such that each of the plurality of electrical cable terminations 108 makes electrical contact with one or more of contact pins 714 of header 704, ground elements 760 of header 704, and a printed circuit board ground contact when header 704 and carrier 106 are in a mated configuration. In the exemplary embodiment of
In the exemplary embodiment of an electrical connector assembly shown in
In each of the embodiments and implementations described herein, the various components of the electrical connector assembly and elements thereof are formed of any suitable material. The materials are selected depending upon the intended application and may include both polymers and metals. In one embodiment, insulating housing 122 of carrier 106 and insulative housing 112 of header 104 are formed of polymeric materials 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, 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.
Number | Name | Date | Kind |
---|---|---|---|
3671662 | Miller et al. | Jun 1972 | A |
3757029 | Marshall | Sep 1973 | A |
4234759 | Harlow | Nov 1980 | A |
4406512 | Schell | Sep 1983 | A |
4655518 | Johnson et al. | Apr 1987 | A |
4680423 | Bennett et al. | Jul 1987 | A |
4816618 | Bongianni | Mar 1989 | A |
4976628 | Fedder | Dec 1990 | A |
4984992 | Beamenderfer et al. | Jan 1991 | A |
5015197 | Redmond et al. | May 1991 | A |
5116230 | Dechelette et al. | May 1992 | A |
5184965 | Myschik et al. | Feb 1993 | A |
5194020 | Voltz | Mar 1993 | A |
5197893 | Morlion et al. | Mar 1993 | A |
5245134 | Vana, Jr. et al. | Sep 1993 | A |
5421735 | Dechelette | Jun 1995 | A |
5455383 | Tanaka | Oct 1995 | A |
5554038 | Morlion et al. | Sep 1996 | A |
5631446 | Quan | May 1997 | A |
5711676 | Michael, III | Jan 1998 | A |
6005193 | Markel | Dec 1999 | A |
6010788 | Kebabjian et al. | Jan 2000 | A |
6086383 | Fasano et al. | Jul 2000 | A |
6146202 | Ramey et al. | Nov 2000 | A |
6148130 | Lee et al. | Nov 2000 | A |
6183301 | Paagman | Feb 2001 | B1 |
6231391 | Ramey et al. | May 2001 | B1 |
6338653 | Jones et al. | Jan 2002 | B1 |
6340795 | Caldwell | Jan 2002 | B1 |
6368120 | Scherer et al. | Apr 2002 | B1 |
6371813 | Ramey et al. | Apr 2002 | B2 |
6501350 | Lester | Dec 2002 | B2 |
6527561 | Glauser | Mar 2003 | B1 |
6527588 | Paagman | Mar 2003 | B2 |
6544045 | Paagman | Apr 2003 | B1 |
6545223 | Baldock | Apr 2003 | B2 |
6780069 | Scherer et al. | Aug 2004 | B2 |
6849799 | Springer et al. | Feb 2005 | B2 |
7004793 | Scherer et al. | Feb 2006 | B2 |
20020002013 | Baldock | Jan 2002 | A1 |
20040110420 | Wu | Jun 2004 | A1 |
20050077074 | Tanaka | Apr 2005 | A1 |
20060254805 | Scherer et al. | Nov 2006 | A1 |
20070141871 | Scherer et al. | Jun 2007 | A1 |
Number | Date | Country |
---|---|---|
41 16 166 | Jul 1992 | DE |
HEI 06-181007 | Jun 1994 | JP |
WO 99 36998 | Jul 1999 | WO |
WO 02 29938 | Apr 2002 | WO |