Patent Application
20190148862
The subject matter herein relates generally to an electrical connector configured to transmit electrical signals with low insertion loss, and, more specifically, to an electrical connector with conductors designed to have lower conducting-surface losses at high signal transmission speeds relative to known conductors in electrical connectors.
Electrical connectors include terminals or conductors that provide conductive current paths through the connectors for interconnecting cables, circuit boards, or the like. Typical conductors are composed of a copper alloy core and have nickel plating surrounding the core to protect the core from corrosion. The specific metals within the copper alloy core may be selected based on various considerations, such as cost and material properties. For example, a conductor that includes a deflectable contact at a mating interface may have a copper alloy core that includes metals that provide a desired amount of flexibility and elasticity to the conductor.
Typical conductors in connectors have several disadvantages, however, especially at high signal transmission speeds above 10 Gb/s. Due to the phenomenon referred to as the skin effect, the current density of a signal transmitted along the conductors concentrates near the surface. The copper alloy core and the nickel plating at the surface of the typical conductors have relatively low electrical conductivities, so transmitted signals experience significant insertion losses along the conductors. The conductor-caused insertion losses are exacerbated at higher signal frequencies.
High speed and high signal density connectors provide the benefit of increased signal throughput, but the high insertion losses caused by the material properties of the typical conductors detract from this benefit by reducing the signal transmission efficiency and quality. A need remains for a high speed electrical connector with low insertion loss conductors.
In one or more embodiments, an electrical connector is provided that includes a housing and a plurality of conductors held within the housing. The conductors are configured to electrically connect to mating conductors of a mating connector. The conductors each extend a length between a mating end and a mounting end of the respective conductor. One or more of the conductors include a copper alloy core, a copper plating layer, and a protective outer layer. The copper plating layer surrounds the copper alloy core, and is composed of a different material than the copper alloy core. The protective outer layer is disposed on and surrounds the copper plating layer. The protective outer layer is composed of a non-conductive polymeric material.
In one or more embodiments, an electrical connector is provided that includes a housing and a plurality of conductors held within the housing. The conductors are configured to electrically connect to mating conductors of a mating connector. The conductors each extend a length between a mating end and a mounting end of the respective conductor. The conductors each include a spring beam at the mating end, a contact tail at the mounting end, and an intermediate segment extending from the spring beam to the contact tail. One or more of the conductors include a copper alloy core, a copper plating layer, and a protective outer layer. The copper plating layer surrounds the copper alloy core. The copper plating layer is composed of a different material than the copper alloy core and has a greater electrical conductivity than the copper alloy core. The protective outer layer is disposed on and surrounds the copper plating layer. The protective outer layer is composed of a non-conductive polymeric material.
In one or more embodiments, an electrical connector is provided that includes a housing, a plurality of conductors held within the housing, and a dielectric body held within the housing. The conductors are configured to electrically connect to mating conductors of a mating connector. The conductors are arranged in at least one linear array. The conductors each extend a length between a mating end and a mounting end of the respective conductor. The conductors each include a spring beam at the mating end, a contact tail at the mounting end, and an intermediate segment extending from the spring beam to the contact tail. One or more of the conductors includes a copper alloy core and a protective outer layer surrounding the copper plating layer around a full perimeter of the copper alloy core. The protective outer layer is composed of a non-conductive polymeric material. The dielectric body encases the conductors of a common array along the intermediate segments thereof to secure the conductors in place relative to each other. The dielectric body engages the protective outer layer of the conductors.
The electrical connector 10 includes a housing 12 that has a mating end 14 and a back end 54. The housing 12 is composed of a dielectric material, such as one or more plastics or other polymeric materials. The housing 12 defines a plurality of contact cavities 18 at the mating end 14 that are configured to receive mating contacts (not shown) of the mating connector through the mating end 14. The housing 12 in the illustrated embodiment includes an alignment rib 42 along an upper surface 26 of the housing 12. The alignment rib 42 is configured to bring the connector 10 into alignment with the mating connector during the mating process to enable the mating contacts of the mating connector to be received into the corresponding contact cavities 18 without stubbing.
The housing 12 also includes a plurality of contact modules (e.g., contact module assemblies) 50 that are received in the housing 12 and extend from the back end 54 of the housing 12. The housing 12 holds the contact modules 50 in place relative to one another and to the housing 12. In the illustrated embodiment, the contact modules 50 engage a hood 48 of the housing 12 that extends rearward beyond the back end 54. The contact modules 50 are stacked side-by-side. The contact modules 50 collectively define a mounting end 56 of the electrical connector 10. Each of the contact modules 50 includes plural conductors 51 and a dielectric body 52. The dielectric bodies 52 define a mounting end 56 of the electrical connector 10. The contact modules 50 also may include conductive shields 53 mounted to sides 55 of the dielectric bodies 52 to provide shielding for the conductors 51.
The conductors 51 include contact tails 58 that protrude beyond the dielectric bodies 52 at the mounting end 56. The contact tails 58 are configured to be mounted to and electrically connected to a substrate (not shown), such as a printed circuit board. The contact tails 58 are illustrated as, but are not limited to, eye-of-the-needle-type pin contacts. The conductors 51 of the contact modules 50 also include mating contact portions 34 (shown in
In the illustrated embodiment, the electrical connector 10 is a right angle connector as the mounting end 56 is oriented substantially perpendicular to the mating end 14 of the housing 12. The electrical connector 10 is configured to interconnect electrical components, such as a backplane circuit board and a daughter circuit board, that are disposed at a right angle relative to one another. In an alternative embodiment, the electrical connector 10 may have a different orientation. For example, the connector 10 may be an in-line connector that extends linearly between the mating end 14 and the mounting end 56, with the mating end 14 oriented substantially parallel to the mounting end 56.
Referring to
The mating contact portions 34 in the illustrated embodiment are each oriented horizontally. Adjacent mating contact portions 34 are stacked vertically in a column 106. The contact tails 58 in the illustrated embodiment are each oriented vertically. Adjacent contact tails 58 are stacked laterally side-by-side in a row 108. The row 108 is substantially perpendicular to the column 106. Thus, the mating contact portions 34 extend substantially perpendicular to the contact tails 58. The intermediate segments 104 of the conductors 51 extend along predetermined paths between the mating contact portions 34 and the contact tails 58. The paths may include oblique sections 124 that extend at approximately 45 degree angles between the respective mating contact portion 34 and contact tail 58. The intermediate segments 104 of different conductors 51 may extend different lengths depending on the locations of the mating contact portions 34 and the contact tails 58 in the array 102. In an alternative embodiment, the mating contact portions 34 may be arranged parallel to the contact tails 58.
Each of the conductors 51 may be individually designated as a signal conductor, a ground conductor, or a power conductor. The array 102 may include any number of conductors 51, any number of which may be selected as signal, ground, or power conductors according a desired wiring pattern. Optionally, adjacent signal conductors may function as differential pairs configured to convey electrical signals at speeds greater than 10 Gb/s. Each differential pair may be separated from an adjacent differential pair by at least one conductor 51 designated as a ground conductor.
Referring back to
In an embodiment, the dielectric body 52 is formed via an overmold process. For example, a heated, non-conductive polymeric material in a flowable state is applied onto the array 102 of conductors 51 and allowed to cool and set, encasing the intermediate segments 104 of the conductors 51 in the resulting solid dielectric body 52. Prior to the overmold process, the conductors 51 may be held together using a carrier strip that is subsequently removed and discarded after the overmold process. In other embodiments, the dielectric body 52 may be a pre-formed single frame (or multiple frame members) into which the conductors 51 are inserted and held via an interference fit, a latching connection, an adhesive bond, or the like.
In the illustrated embodiment, the mating contact portions 34 of the conductors 51 are spring beams 34. With additional reference to
The copper alloy core 202 and the copper plating layer 204 are composed of different materials. The copper plating layer 204 has a greater electrical conductivity than the core 202 due to the material properties of the different materials. For example, the copper plating layer 204 may include a greater amount or percentage of copper present per weight or mass than the copper alloy core 202. The copper plating layer 204 may have a greater % IACS value than the copper alloy core 202. As used herein, “% IACS” values refer to a unit of the International Annealed Copper Standard (IACS), which is an empirically derived standard value for the electrical conductivity of copper. A material with a value of 10% IACS means that the electrical conductivity of that material is 10% of the electrical conductivity of copper. For example, the copper alloy core 202 may have a % IACS value less than 40%, and the copper plating layer 204 may have a % IACS value greater than 70%.
The material of the core 202 is a copper alloy that includes copper and one or more other metals. Some non-limiting examples of copper alloys that may form the core 202 include a phosphor bronze alloy, a copper nickel silicon alloy, and similar alloys. In one embodiment, the copper plating layer 204 is composed of substantially pure copper. As used herein, “substantially pure copper” includes materials that are 100% copper as well as materials that, due to the presence of trace materials, include at least 95% copper (e.g., by mass or weight), at least 97% copper, or at least 99% copper. In the embodiment in which the copper plating layer 204 is substantially pure copper, the % IACS value may be greater than 95%. In other embodiments, the copper plating layer 204 is a copper alloy includes copper and non-trace amounts of one or more other metals, but the % IACS value is still greater than that of the copper alloy core 202.
The copper plating layer 204 is the outermost conductive layer of the conductor 51. During operation, the electrical current transmitted along the conductor 51 concentrates along the copper plating layer 204 that surrounds the core 202 due to the skin effect phenomenon. Although the protective outer layer 206 surrounds the copper plating layer 204, the electrical current density does not concentrate along the protective outer layer 206 because the protective outer layer 206 is composed of a non-conductive polymeric material.
Some known conductors include a nickel plating layer that surrounds a copper alloy core and defines an outermost layer of the known conductor. Therefore, the electrical current density concentrates along the nickel plating layer in the known conductors. The copper plating layer 204 of the conductors 51 has a greater conductivity than nickel plating layers, which may be less than 30% IACS. Due to the greater conductivity of the outermost conductive layer, the conductors 51 described herein may have a reduced amount of conductor-caused insertion loss during operation than the known conductors with outermost nickel plating layers. The reduced amount of insertion loss may allow an electrical connector with the conductors 51 (e.g., the electrical connector 10 shown in
In the illustrated embodiment, the copper plating layer 204 is disposed directly on an outer surface 208 of the copper alloy core 202. But, in an alternative embodiment, the copper plating layer 204 may be separated from the core 202 by one or more intervening layers. The copper plating layer 204 surrounds the core 202 around a full perimeter of the core 202. The copper plating layer 204 engages the outer surface 208 along the entire perimeter of the core 202. As shown in
The protective outer layer 206 is disposed directly on an outer surface 210 of the copper plating layer 204 and surrounds the copper plating layer 204. The protective outer layer 206 is composed of a non-conductive polymeric material, such as one or more plastics, epoxies, resins, or the like. In an embodiment, the protective outer layer 206 surrounds the copper plating layer 204 around a full perimeter of the copper plating layer 204. The protective outer layer 206 engages the outer surface 210 along a full perimeter of the copper plating layer 204. As shown in
An outer surface 212 of the protective outer layer 206 defines an exterior surface of the conductor 51 along the intermediate segment 104. The protective outer layer 206 is discrete from the dielectric body 52 (shown in
In the illustrated embodiment, the nickel plating layer 220 surrounds the copper alloy core 202. The nickel plating layer 220 is disposed between the core 202 and the copper plating layer 204. The nickel plating layer 220 engages the outer surface 208 of the core 202 and extends around the full perimeter of the core 202. The copper plating layer 204 is disposed directly on an outer surface 222 of the nickel plating layer 220 and surrounds the nickel plating layer 220 around a full perimeter thereof. Similar to the embodiment shown in
Since some known conductors have a copper alloy core similar to the core 202 that is surrounded by a nickel plating layer, the embodiment of the conductor 51 shown in
The conductor 51 in the illustrated embodiment includes the non-conductive protective outer layer 206 of the conductors 51 shown in
The outer surface 304 of the iron phosphorus copper core 302 defines the outermost conductive layer of the conductor 51 in the illustrated embodiment. Due to the skin effect, the electrical current density may concentrate towards the outer surface 304 of the core 302. Since the iron phosphorus copper core 302 has a relatively high conductivity relative to known core materials and nickel plating layers, the core 302 of the conductor 51 may have a reduced amount of conductor-caused insertion loss during operation than known conductors with outermost nickel plating layers.
The conductor 51 at the first state 402 includes only the copper alloy core 202. The core 202 may be stamped and formed from a sheet of metal or molded. The core 202 extends the entire length of the conductor 51 from the mating end 120 to the mounting end 122. At the second state 404, the copper plating layer 204 is applied on the copper alloy core 202. The copper plating layer 204 surrounds the core 202 along the entire length of the conductor 51 from the mating end 120 to the mounting end 122. Only the copper plating layer 204 is visible in the schematic diagram at the second state 404 because the core 202 is underneath the copper plating layer 204. The copper plating layer 204 may be applied via any plating method, such as electroplating, physical vapor deposition, dipping, painting, sputter deposition, or the like. Since the copper plating layer 204 covers the entire length of the conductor 51, the plating process may be relatively simple without necessitating masking certain portions of the conductor 51.
At the finished state 406, the non-conductive protective outer layer 206 covers the copper plating layer 204 along the intermediate segment 104. The protective outer layer 206 may be applied by spraying, dipping, or painting the non-conductive polymeric material onto the conductor 51 and subsequently curing to solidify the protective outer layer 206. In an embodiment, the protective outer layer 206 is only applied to the intermediate segment 104, and not along either of the contact tail 58 or the mating contact portion 34. For example, the contact tail 58 and the mating contact portion 34 may be masked prior to applying the non-conductive polymeric material to the intermediate segment 104.
In the illustrated embodiment, the copper plating layer 204 along the mating contact portion 34 is selectively spot-plated with a series of mating finishing metals 408. For example, the mating finishing metals 408 may include a palladium layer, a nickel layer, and a gold layer that defines an outermost layer. The mating finishing metals 408 are selected to provide desired electrical properties at the mating interface between the conductor 51 and a mating contact of a mating connector. The mating finishing metals 408 are only applied along the mating contact portion 34.
The copper plating layer 204 along the contact tail 58 is selectively spot-plated with a series of one or more mounting finishing metals 410. For example, the mounting finishing metals 410 may include a nickel layer covered by a tin layer. The mounting finishing metals 410 are selected to provide desired electrical and mechanical properties at the mounting interface between the conductor 51 and a circuit board. The mounting finishing metals 410 are only applied along the contact tail 58.
The conductor 51 at the first state 502 includes only the copper alloy core 202. The conductor 51 at the first state 502 may be identical to the conductor 51 at the first state 402 described in
The conductor 51 at the third state 506 is selectively plated with different metals along the different lengths of the conductor 51. For example, the copper plating layer 204 is applied along the intermediate segment 104. The copper plating layer 204 optionally is not applied along the mating contact portion 34 or the contact tail 58. Thus, in the illustrated embodiment, the copper plating layer 204 only surrounds the core 202 and the nickel plating layer 220 along the intermediate segment 104. The mating contact portion 34 is selectively spot-plated with the mating finishing metals 408 described with reference to
The conductor 51 at the finished state 508 includes the non-conductive protective outer layer 206 that covers the copper plating layer 204 along the intermediate segment 104. The protective outer layer 206 may be applied as described with reference to the finished state 406 in
Referring now back to
The inventive subject matter described herein may not be limited to a specific type of electrical connector, such as the right angle receptacle-style electrical connector 10 shown in
Unlike the electrical connector 10, the housing 608 of the connector 600 includes a mating shroud 621 that defines a card slot 622. The mating connector 602 includes a circuit card 624 that is received within the card slot 622 during a mating operation. The spring beams 616 of the contact modules 610 in the module stack 606 are arranged in a first contact row 626 and a second contact row 628. The first and second rows 626, 628 are held within the mating shroud 621 and extend into the card slot 622. The spring beams 616 in the first contact row 626 are configured to engage contact elements (not shown) along a first side 630 of the circuit card 624, and the spring beams 616 in the second contact row 628 are configured to engage contact elements (not shown) along a second side 632 of the circuit card 624 that is opposite the first side 630. In an embodiment, the conductors 612 are formed according to one of the embodiments of the conductors 51 described herein. For example, the intermediate segments 620 of the conductors 612 may have the same cross-sections as at least one of the embodiments of the conductors 51 shown in
It is to be understood that the above description is intended to be illustrative, and not restrictive. For example, the above-described embodiments (and/or aspects thereof) may be used in combination with each other. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from its scope. Dimensions, types of materials, orientations of the various components, and the number and positions of the various components described herein are intended to define parameters of certain embodiments, and are by no means limiting and are merely exemplary embodiments. Many other embodiments and modifications within the spirit and scope of the claims will be apparent to those of skill in the art upon reviewing the above description. The scope of the invention should, therefore, be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled. In the appended claims, the terms “including” and “in which” are used as the plain-English equivalents of the respective terms “comprising” and “wherein.” Moreover, in the following claims, the terms “first,” “second,” and “third,” etc. are used merely as labels, and are not intended to impose numerical requirements on their objects. Further, the limitations of the following claims are not written in means-plus-function format and are not intended to be interpreted based on 35 U.S.C. § 112(f), unless and until such claim limitations expressly use the phrase “means for” followed by a statement of function void of further structure.
