The subject matter herein relates generally to electrical connector systems.
Some electrical connector systems utilize electrical connectors to interconnect two circuit boards, such as a motherboard and daughter card. Signal loss and/or signal degradation is a problem in known electrical systems. For example, crosstalk results from an electromagnetic coupling of the fields surrounding an active conductor (or differential pair of conductors) and an adjacent conductor (or differential pair of conductors). The strength of the electromagnetic coupling generally depends on the separation between the conductors, such that crosstalk may be significant when the electrical connectors are placed in close proximity to each other. Moreover, as speed and performance demands increase, known electrical connectors are proving to be insufficient. Additionally, there is a desire to increase the density of electrical connectors to increase throughput of the electrical system, without an appreciable increase in size of the electrical connectors, and in some cases, with a decrease in size of the electrical connectors. Such an increase in density and/or reduction in size causes further strains on performance.
In order to address performance, some electrical connectors have been developed that utilize shielding between pairs of signal contacts. The shielding is provided in both connectors along the signal lines, such as through ground contacts. Typically, the individual shields are electrically commoned in both circuit boards. However, the shields remain electrically independent between the circuit boards. The signal lines may experience degradation, such as resonance noise, along their lengths through the electrical connectors. The resonance noise is due to standing electromagnetic waves created at the ends of the ground contacts that propagate along the ground contacts and cause the electrical potential of the ground contact to vary along the length, referred to as resonance spikes. The resonance noise can couple to the pairs of signal contacts to degrade the signal performance. The resonance noise and crosstalk between pairs of signal contacts increases as the electrical connectors are used to convey more data at faster data rates and transmitted at higher frequencies. The resonance noise also increases as the length of the ground contacts between grounding locations increases.
A need remains for an electrical connector that reduces resonance noise to improve signal performance of an electrical connector system.
In an embodiment, an electrical connector is provided that includes a front housing and a plurality of contact modules. The front housing extends between a front side and a rear side. The front side defines a mating end of the electrical connector that is configured to interface with a mating connector. The contact modules are coupled to the rear side of the front housing and stacked side by side along a lateral stack axis. Each contact module comprises a housing frame, multiple signal conductors and ground conductors held in the housing frame, and a ground shield coupled to an outer side of the housing frame. The housing frame is formed by a first shell member and a second shell member that abut one another at an interface. At least one of the first shell member or the second shell member defines multiple openings extending therethrough. The openings align with and provide access to the ground conductors held in the housing frame. The signal conductors and the ground conductors have broad sides. The broad sides of the signal conductors and the ground conductors are oriented orthogonal to the interface between the first and second shell members. The ground shield includes ground tabs that extend through the openings of one of the first shell member or the second shell member and engage the ground conductors to electrically connect the ground shield and the ground conductors of the contact module.
In another embodiment, an electrical connector is provided that includes a front housing and a plurality of contact modules. The front housing extends between a front side and a rear side. The front side defines a mating end of the electrical connector that is configured to interface with a mating connector. The contact modules are coupled to the rear side of the front housing and are stacked side by side along a lateral stack axis. Each contact module comprises a housing frame, multiple signal conductors and ground conductors held in the housing frame, and a ground shield coupled to an outer side of the housing frame. The housing frame is formed by a first shell member and a second shell member. The housing frame defines signal slots and ground slots. The signal slots and the ground slots are defined partially by the first shell member and partially by the second shell member such that the signal slots and the ground slots extend across a seam at an interface between the first and second shell members. At least one of the first shell member or the second shell member further defines multiple openings extending therethrough. The openings align with the ground slots. The signal conductors are each held in a corresponding signal slot. The ground conductors are each held in a corresponding ground slot. The ground shield includes ground tabs that extend through the openings of one of the first shell member or the second shell member and engage the ground conductors within the ground slots to electrically connect the ground shield and the ground conductors of the respective contact module.
The electrical connector system 100 is oriented with respect to a vertical or elevation axis 191, a lateral axis 192, and a longitudinal axis 193. The axes 191-193 are mutually perpendicular. Although the elevation axis 191 appears to extend in a vertical direction generally parallel to gravity, it is understood that the axes 191-193 are not required to have any particular orientation with respect to gravity. The elevation axis 191 is referred to herein as a mating axis 191, as the first electrical connector 102 is mated to the second electrical connector 104 by moving the first connector 102 towards the second connector 104 and/or moving the second connector 104 towards the first connector 102 along the mating axis 191.
In an exemplary embodiment, the first electrical connector 102 is a receptacle connector, and is referred to herein as receptacle connector 102. In addition, the second electrical connector 104 is a header or mating connector in an exemplary embodiment, and is referred to herein as a header connector 104. Although one or more embodiments shown and described below describe the receptacle connector 102 as having multiple contact modules 138, it is recognized that in an alternative embodiment, the contact modules 138 and/or other components of the receptacle connector 102 may be part of the header connector 104 instead of, or in addition to, being part of the receptacle connector 102.
The electrical connector system 100 may be disposed on or in an electrical component, such as a server, a computer, a router, or the like. The electrical component may include other electrical devices in addition to the electrical connector system 100 that are located near the electrical connector system 100. Due to space constraints in or on the electrical component, it may be useful to vary the height of the electrical connector system 100 in order to vary the distance between the first and second circuit boards 106, 108. For example, configuring the connector system 100 with a tall height may allow the first circuit board 106 to extend over one or more short electrical devices located on or near the second circuit board 108, to prevent the short electrical device(s) from interfering with the mating between the receptacle and header connectors 102, 104. In another example, configuring the connector system with a short height may allow the first circuit board 106 to extend below one or more overhanging electrical devices, to prevent the overhanging electrical device(s) from interfering with the mating between the receptacle and header connectors 102, 104.
In an embodiment, the receptacle connector 102 is modular in design. The receptacle connector 102 includes a front housing 136 and a plurality of contact modules 138 coupled to the front housing 136. For example, the front housing 136 extends between a front side 140 and a rear side 142. The front side 140 defines a mating end 132 of the receptacle connector 102 that is configured to interface with the header connector 104 or another mating connector. The contact modules 138 are coupled to the rear side 142 of the front housing 136 and are stacked side by side along the lateral axis 192, referred to herein as a lateral stack axis 192. The contact modules 138 may be collectively referred to as a module stack 130. The module stack 130 extends between a front side 143 and a rear side 144. The front side 143 couples to the front housing 136. The rear side 144 defines the mounting end 134 of the receptacle connector 102 that mounts to the circuit board 106. As used herein, relative or spatial terms such as “top,” “bottom,” “front,” “rear,” “left,” and “right” are only used to distinguish the referenced elements and do not necessarily require particular positions or orientations in the electrical connector system 100 or in the surrounding environment of the electrical connector system 100. The receptacle connector 102 may have any number of contact modules 138 stacked together across the lateral stack axis 192 in the module stack 130, subject to the size and coupling accommodations of the front housing 136.
In an embodiment, a length of the contact modules 138 may be modified in order to adjust the length of the module stack 130 between the front side 143 and the rear side 144, which adjusts the height of the electrical connector system 100 between the circuit boards 106, 108. For example, a first set of contact modules 138 each having a first length may be assembled to the front housing 136 to produce a connector system 100 with a first height. The first set of contact modules 138 may be substituted for a second set of contact modules 138 that each has a second length different from the first length in order to produce a connector system 100 with a second height.
In the illustrated embodiment, the header connector 104 includes a header housing 112 and a plurality of signal contacts 114 and ground contacts 116. The header housing 112 extends between a mating end 122 and a mounting end 124. The header housing 112 includes multiple outer walls 118 that define a socket 120 therebetween. The socket 120 is open at the mating end 122 of the header housing 112 and is configured to receive a portion of the receptacle connector 102 (that includes the mating end 132) therein. The header housing 112 may be box-shaped with four outer walls 118. All or at least some of the outer walls 118 may be beveled at the mating end 122 to provide a lead-in section to guide the receptacle connector 102 into the socket 120 during mating. In the illustrated embodiment, the header housing 112 has a fixed height between the mating end 122 and the mounting end 124. Alternatively, the header connector 104 may have a variable height by stacking multiple housing units together to adjust the height of the header connector 104. The header housing 112 may be formed of at least one dielectric material, such as a plastic or one or more other polymers. The mounting end 124 of the header housing 112 faces, and may also abut, a surface 126 of the second circuit board 108.
The signal contacts 114 and ground contacts 116 of the header connector 104 protrude through a base wall 129 of the header housing 112 into the socket 120. The base wall 129 extends between the outer walls 118 and defines a back wall of the socket 120. The signal contacts 114 and the ground contacts 116 are formed of a conductive material, such as copper, a copper alloy, and/or another metal or metal alloy. In the illustrated embodiment, the signal contacts 114 and the ground contacts 116 each include a pin 128 that extends into the socket 120. Although not clearly shown in
The receptacle connector 102 includes a plurality of signal conductors 150 and ground conductors 152 that are held in the contact modules 138. At least portions of the signal conductors 150 and the ground conductors 152 may extend into the front housing 136 for engaging with the pins 128 of the signal contacts 114 and ground contacts 116, respectively, of the header connector 104. The signal conductors 150 and the ground conductors 152 may extend parallel to the mating axis 191. The signal and ground conductors 150, 152 extend along lengths that are at least as long as the module stack 130 between the front side 143 and the rear side 144. The ground conductors 152 are configured to provide shielding for the signal conductors 150 along the length of the module stack 130. In the illustrated embodiment, the signal and ground conductors 150, 152 each have a terminating segment 154 that extends beyond the rear side 144 of the module stack 130 (for example, at the mounting end 134) for electrical termination to corresponding conductors (not shown) on the first circuit board 106. The terminating segment 154 may be an eye-of-the-needle pin, which is configured to be through-hole mounted to a corresponding via of the circuit board 106. Alternatively, one or more of the terminating segments 154 may be bent tails configured to be soldered or otherwise surface mounted to conductive pads on the circuit board 106.
The receptacle connector 102 further includes ground shields 156 (shown in
It is recognized that electromagnetic interference (EMI), such as resonance noise and crosstalk, between pairs of signal conductors 150 generally increases with increasing data transfer rates, frequencies, and lengths of the ground paths between grounding locations. Such resonance noise and crosstalk may degrade the signal integrity and performance of the electrical connector system 100. In an embodiment, the conductive ground circuits provided by the ground shields 156 reduce the length of the conductive ground paths between grounding locations, thereby improving signal integrity by reducing resonance noise and crosstalk within the connector system 100. For example, shortening the ground paths of the ground conductors 152 may reduce the magnitude of resonance peaks in resonance waves that propagate through the ground conductors 152 within the receptacle connector 102. The length of the ground paths also may affect the resonance frequency of the ground conductors 152. A longer ground path between grounding locations corresponds with a relatively lower resonance frequency, while a shorter ground path length corresponds with a relatively higher resonance frequency. Shortening the length of the ground path via the ground shield 156 may increase the resonance frequency to a level outside of an operating frequency range or band, such that the resonance frequency does not have a detrimental effect on the signal performance of the signal conductors 150. The resonance frequency may be increased to a level at or above 12 GHz, 16 GHz, 20 GHz, or the like.
The contact module 138 includes a housing frame 158. The signal conductors 150 and the ground conductors 152 are held in the housing frame 158. The ground shield 156 is coupled to an outer side of the housing frame 158. For example, the housing frame 158 includes a first outer side 160 and a second outer side 162. In
The housing frame 158 is formed by a first shell member 164 and a second shell member 166. The first shell member 164 defines the first outer side 160 of the housing frame 158. The second shell member 166 defines the second outer side 162 of the housing frame 158. The first shell member 164 abuts the second shell member 166 at an interface 168. In an embodiment, the interface 168 is linear and defines a seam 170. The second shell member 166 of the contact module 138 shown in
As shown in
In an embodiment, the signal conductors 150 and the ground conductors 152 are held by the housing frame 158 in a single file line. The single file line of conductors 150, 152 extends along the interface 168 between the first shell member 164 and the second shell member 166. Within the line, the signal conductors 150 may be arranged in a plurality of signal pairs 180 that are configured to carry differential signals. The ground conductors 152 are interleaved between the signal pairs 180 in order to provide shielding between adjacent signal pairs 180. Along the line of conductors 150, 152, the two signal conductors 150 of each signal pair 180 are directly next to one another, and the signal pair 180 is bordered on each side by at least one ground conductor 152. This arrangement is referred to as a repeatable ground-signal-signal-ground (GSSG) sequence or pattern. In the illustrated embodiment, a single ground conductor 152 is positioned or interleaved between adjacent signal pairs 180 of signal conductors 150. However, in other embodiments, adjacent signal pairs 180 may be separated by at least two ground conductors 152.
The ground shield 156 has a planar body 182. The planar body 182 may be formed of a metal plate or the like. The body 182 may abut against the corresponding outer side of the housing frame 158 (for example, the second outer side 162 in the embodiment shown in
In an embodiment, the ground tabs 184 (shown in
In
The front housing 136 extends between the front side 140 and the rear side 142. The front housing 136 in the illustrated embodiment has a rectangular or square-shaped cross-sectional area that includes four outer walls 194 extending between the front side 140 and the rear side 142. The front housing 136 is configured to fit within the socket 120 (shown in
The signal cavities 146 and the ground cavities 148 are arranged in plural columns 190. Each column 190 corresponds to the signal conductors 150 (shown in
Optionally, adjacent columns 190 are staggered relative to a reference edge 198 of the front housing 136. The reference edge 198 is an edge of the front housing 136 between the front side 140 and one of the outer walls 194 that is used as a point of reference. For example, the signal cavities 146 and the ground cavities 148 in one column 190 may be offset from the signal cavities 146 and the ground cavities 148 in an adjacent column 190 at respective different distances from the reference edge 198. The cavities 146, 148 of adjacent columns 190 may be offset by a half pitch, a full pitch, or the like. A “pitch” as used herein refers to the distance between the centers of adjacent cavities 146, 148 in the same column 190. Staggering the columns 190 of cavities 146, 148 increases the distance between signal conductors 150 (shown in
In an embodiment, the stems 200 of the signal and ground conductors 150, 152 have two broad sides 202, although only one broad side 202 of each of the conductors 150, 152 is visible in
The first and second shell members 164, 166 may each be composed of a dielectric material, such as a plastic and/or one or more other polymers. The first shell member 164 and the second shell member 166 each include an interior side 204 and an exterior side 206. The interior sides 204 of both shell members 164, 166 are visible in
In an embodiment, the interior side 204 of the first shell member 164 mirrors the interior side 204 of the second shell member 166. In each of the shell members 164, 166, the portions of the signal slots 208 and the ground slots 210 extend parallel to one another. The portions of the signal and ground slots 208, 210 extend the length of the respective shell members 164, 166 between a first end 212 and an opposite second end 214. The first and second ends 212, 214 of the first and second shell members 164, 166 define the front end 178 (shown in
The signal slots 208 each receive and hold a corresponding signal conductor 150 therein. The ground slots 210 each receive and hold a corresponding ground conductor 152 therein. The portions of the signal slots 208 and the ground slots 210 defined by each of the first and second shell members 164, 166 may be sized to accommodate the respective conductors 150, 152 with little or no clearance such that the conductors 150, 152 are retained in the corresponding slots 208, 210 by a friction or interference fit. For example, the portions of the signal slots 208 and the ground slots 210 defined by at least one of the shell members 164, 166 may include deformable crush ribs that are configured to engage at least one of the broad sides 202 of the corresponding conductors 150, 152. Alternatively, or in addition, an adhesive and/or a mechanical feature may be used to hold the signal conductors 150 and the ground conductors 152 in the corresponding signal and ground slots 208, 210, such as to prevent axial movement of the conductors 150, 152 relative to the slots 208, 210.
The planar body 182 of the ground shield 156 includes an inner surface 216 and an opposite outer surface 218. The ground tabs 184 of the ground shield 156 extend from the inner surface 216 out of plane from the body 182. The ground tabs 184 in an embodiment do not extend from the outer surface 218. The ground tabs 184 may be integral to the body 182, or, alternatively, may be coupled to the body 182. In the illustrated embodiment, the inner surface 216 of the ground shield 156 is configured to be placed along the exterior side 206 of the second shell member 166. The ground tabs 184 align with and extend through the openings 172 of the second shell member 166 to access and engage the ground conductors 152 that are loaded within the ground slots 210. In some other contact modules 138 (shown in
The ground shield 156 may be composed of a conductive material, such as copper, a copper alloy, silver, or another metal or metal alloy. The ground shield 156 optionally may be stamped and formed from a plate, panel, or sheet of metal. For example, the ground tabs 184 may be formed by stamping the body 182 and then bending the ground tabs 184 out of the plane of the body 182. Alternatively, the ground shield 156 may include a dielectric material that is plated with a metal material to provide electrically conductive properties. The conductive properties of the ground shield 156 allows the ground shield 156 to electrically connect to the ground conductors 152 engaged by the ground tabs 184 and to provide a ground circuit that electrically commons the ground conductors 152 of the contact module 138.
In an embodiment, the ground tabs 184 of the ground shield 156 are configured to engage each ground conductor 152 of the contact module 138 and/or to engage each ground conductor 152 at multiple axial locations along a length of that corresponding ground conductor 152. As shown in
In addition, the ground tabs 184 along one of the rows 220 are configured to engage different ground conductors 152 of the contact module 138 at the same (or approximately the same) axial location along the length of the contact module 138 between the front end 178 and the rear end 174. For example, the tabs 184 in the row 220A are configured to extend through corresponding openings 172 in the second shell member 166 that are most proximate to the front end 178 of the contact module 138. Each of the tabs 184 in the row 220A engages a respective different ground conductor 152 at an axial location that is most proximate to the front end 178 (compared to other contact locations between other ground tabs 184 of the ground shield 156 and the ground conductors 152). In the illustrated embodiment, each row 220 includes five ground tabs 184, and each ground tab 184 is configured to engage a respective different one of the five ground conductors 152 held in the contact module 138. The ground shield 156 creates a conductive ground circuit, defined by the body 182 and the ground tabs 184, that electrically commons the ground conductors 152 to one another. It is recognized that the rows 220 and/or columns 222 of the ground shield 156 may include other than five ground tabs 184 in other embodiments.
As shown in
As shown in
Optionally, the signal and ground conductors 150, 152 of the first contact modules 138A may be staggered from the signal and ground conductors 150, 152 of the second contact modules 138B. For example, the signal and ground conductors 150, 152 of each first contact module 138A are offset from a reference side wall 242 of the module stack 130 at respective distances that are different than distances of the signal and ground conductors 150, 152 of each adjacent second contact module 138B, in order to increase the distance between signal conductors 150 of adjacent contact modules 138. The reference side wall 242 is one of the walls of the module stack 130 that extends between the front side 143 (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.
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