Patent Grant
9859635
The subject matter herein relates generally to electrical connectors that have an array of signal and ground contacts.
Some electrical connector systems utilize electrical connectors, such as mezzanine connectors, to interconnect two circuit boards, such as a motherboard and daughter card. The conductors of one electrical connector are terminated to one circuit board and extend through the housing towards a mating end to engage mating conductors of the mating connector terminated to the other circuit board.
Some known electrical connectors have electrical problems, particularly when transmitting at high data rates. For example, the electrical connectors typically utilize differential pair signal conductors to transfer high speed signals. Ground conductors improve signal integrity. However, electrical performance of known electrical connectors, when transmitting electrical signals at high data rates, is inhibited by resonance spikes at certain frequencies.
A need remains for a high density, high speed electrical connector having reliable performance.
In an embodiment, an electrical connector is provided that includes a housing and plural contact modules stacked adjacent to each other along a stack axis and held by the housing. Each contact module includes a contact array, a dielectric holder, and lossy blocks. The contact array includes signal contacts and ground contacts arranged in a column. The signal contacts and the ground contacts are arranged in alternating pairs along a length of the column such that a pair of ground contacts extends between two pairs of signal contacts. The signal and ground contacts extend between respective mating ends configured to engage a mating connector and terminating ends configured to engage a circuit board. The dielectric holder surrounds and engages the signal and ground contacts along intermediate segments of the signal and ground contacts between the mating and terminating ends to secure the signal and ground contacts in place relative to the dielectric holder. The dielectric holder is composed of a low loss material. The lossy blocks are mounted to the intermediate segments of the ground contacts within the dielectric holder. Each lossy block is associated with a corresponding pair of ground contacts and engages at least one of the ground contacts in the corresponding pair. The lossy blocks are composed of a lossy material that that has a loss tangent greater than a lost tangent of the low loss material of the dielectric holder.
In another embodiment, an electrical connector is provided that includes a housing and plural contact modules stacked adjacent to each other along a stack axis and held by the housing. Each contact module includes a contact array, a dielectric holder, and lossy blocks. The contact array includes signal contacts and ground contacts arranged in a column. The signal contacts and the ground contacts are arranged in alternating pairs along a length of the column such that a pair of ground contacts extends between two pairs of signal contacts. The signal and ground contacts extend between respective mating ends configured to engage a mating connector and terminating ends configured to engage a circuit board. The dielectric holder surrounds and engages the signal and ground contacts along intermediate segments of the signal and ground contacts between the mating and terminating ends to secure the signal and ground contacts in place relative to the dielectric holder. The dielectric holder is composed of a low loss material. The lossy blocks are overmolded over the intermediate segments of the ground contacts within the dielectric holder. Each lossy block is associated with a corresponding pair of ground contacts and overmolded over at least one of the ground contacts in the corresponding pair. The lossy blocks are composed of a lossy material that has a loss tangent greater than a lost tangent of the low loss material of the dielectric holder.
In a further embodiment, an electrical connector is provided that includes a housing and plural contact modules stacked adjacent to each other along a stack axis and held by the housing. Each contact module includes a contact array, a dielectric holder, and lossy blocks. The contact array includes signal contacts and ground contacts arranged in a column. The signal and ground contacts extend between respective mating ends configured to engage a mating connector and terminating ends configured to engage a circuit board. The lossy blocks are mounted to the ground contacts. Each lossy block engages a different corresponding ground contact. The lossy blocks are composed of a lossy material. The dielectric holder is overmolded over the contact array and the lossy blocks to secure the signal contacts, the ground contacts, and the lossy blocks in place relative to the dielectric holder. The mating ends and the terminating ends of the signal contacts and the ground contacts protrude outward from respective front and rear ends of the dielectric holder. The dielectric holder is composed of a low loss material that has a loss tangent lower than a lost tangent of the lossy material of the lossy blocks.
In an exemplary embodiment, the first electrical connector 102 is a receptacle connector, and the second electrical connector 104 is a header connector. The electrical connectors 102, 104 are mating halves of a mezzanine connector. However, the subject matter described herein is not intended to be limited to mezzanine connectors but rather may have application to other types of connectors in alternative embodiments, such as right angle connectors or cable-mounted connectors.
The first electrical connector 102 and the second electrical connector 104 are configured to be mounted to and electrically connected to respective first and second circuit boards 106, 108. The first and second electrical connectors 102, 104 are utilized to provide a signal transmission path to electrically connect the circuit boards 106, 108 to one another at a separable mating interface. In
In the illustrated embodiment, the header connector 104 includes a header housing 112 and a plurality of header contacts 114. The header housing 112 extends between a mating end 122 and a mounting end 124. The header housing 112 includes multiple outer walls that define a chamber 120 therebetween. For example, the header housing 112 may include opposite side walls 115, 116 and opposite end walls 117, 118. Optionally, the header housing 112 defines a rectangular cross-sectional shape because the side walls 115, 116 are longer in a longitudinal direction than the end walls 117, 118 are wide in a lateral direction. However, the header housing 112 may have other walls defining other shapes in other embodiments.
The chamber 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 therein. All or at least some of the walls 115-118 may be beveled at the mating end 122 to provide a lead-in section to guide the receptacle connector 102 into the chamber 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. The header housing 112 may be formed of at least one dielectric material, such as a plastic or one or more other polymers. A base wall 128 (shown in
The header contacts 114 include signal contacts and ground contacts arranged in an array, such as along rows and columns in the chamber 120. Optionally, the ground contacts may be longer than the signal contacts to form a sequenced mating interface for mating with the receptacle connector 102. The contacts 114 are formed of a conductive material, such as copper, a copper alloy, and/or another metal or metal alloy. In the illustrated embodiment, the contacts 114 include flat blades at mating ends thereof that are disposed in the chamber 120. However, the contacts 114 may have other mating interfaces in alternative embodiments, such as spring beams, sockets, pins, or the like. The header contacts 114 also include terminating segments (not shown) that are configured to engage and electrically connect to a corresponding conductor (not shown) of the circuit board 108. The conductors of the circuit board 108 may be electric pads or traces, plated vias, or the like. In various embodiments, the terminating segments of the header contacts 114 are compliant pins, such as eye-of-the-needle pins, which are received in plated vias of the circuit board 108.
The receptacle connector 102 includes a housing 200 that extends between a mating end 222 and a receiving end 224. The housing 200 is provided at a front of the receptacle connector 102 and in thus referred to herein as a front housing 200. 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. In an alternative embodiment, the front housing 200 may be a first housing that is coupled a second housing rearward of the front housing 200. For example, the front housing 200 may be stackable with additional housings to adjust the height of the receptacle connector 102. The front housing 200 may be manufactured from a low loss dielectric material, such as a plastic material. The low loss dielectric material has dielectric properties that have relatively little variation with frequency.
The receptacle connector 102 includes a plurality of contact modules 214 stacked adjacent to one another along a stack axis 216. The contact modules 214 are held by the front housing 200. For example, the front housing 200 defines a cavity 218 (shown in
In an embodiment, the signal contacts 230 and the ground contacts 232 of the contact array 234 are arranged in a column 240. Thus, the contacts 230, 232 in each contact module 214 may align with one another in a corresponding column 240 of contacts. Optionally, the signal contacts 230 and ground contacts 232 may be similar or identical to each other. For example, the signal and ground contacts 230, 232 extend between mating ends 242 and terminating ends 244. The mating ends 242 of the signal contacts 230 and the ground contacts 232 are configured to engage and electrically connect to the corresponding signal and ground contacts of the header contacts 114 of the header connector 104. The mating ends 242 include or define flat blades in the illustrated embodiment, but may have other mating interfaces in other embodiments, such as spring beams, pins, sockets, or the like. The terminating ends 244 are configured to engage and electrically connect to corresponding conductors or conductive elements (not shown) of the circuit board 106 (shown in
In an embodiment, the signal contacts 230 and the ground contacts 232 of the contact array 234 are arranged in alternating pairs along the length of the column 240. Thus, a pair of ground contacts 232 (referred to herein as a ground pair 250) is disposed between two pairs of signal contacts 230 (referred to herein as signal pairs 252) in the column 240 and/or a signal pair 252 is disposed between two ground pairs 250. The signal pairs 252 may be configured to convey differential signals. The ground pairs 250 provide electrical shielding between adjacent signal pairs 252. In an alternative embodiment, only a single ground contact 232 may be disposed between two signal pairs 252. In another alternative embodiment, the signal contacts 230 may alternate with the ground contacts 232 along the column 240 such that a signal contact 230 is flanked on both sides by ground contacts 232.
The lossy blocks 202 (shown in phantom in
The dielectric holder 236 surrounds and engages the signal and ground contacts 230, 232 of the contact array 234 to secure the contacts 230, 232 in place relative to the dielectric holder 236. In an embodiment, the dielectric holder 236 surrounds and engages the intermediate segments 246 of the contacts 230, 232. The dielectric holder 236 also surrounds (for example, encases) the lossy blocks 202 mounted to the ground contacts 232. The dielectric holder 236 has a front end 254 and an opposite rear end 256. The signal and ground contacts 230, 232 protrude from the front end 254 to the respective mating ends 242. The signal and ground contacts 230, 232 protrude from the rear end 256 to the respective terminating ends 244. Thus, the mating ends 242 and the terminating ends 244 are exposed from the dielectric holder 236 for engaging the corresponding header contacts 114, and the terminating ends 244 are exposed from the dielectric holder 236 for engaging the electrical elements of the circuit board 106.
The dielectric holder 236 is composed of a low loss dielectric material, such as a plastic, that has a lower electrical loss characteristic than the lossy material of the lossy blocks 202. For example, the low loss dielectric material of the dielectric holder 236 may have a lower dielectric constant relative to the lossy material of the lossy blocks 202. The low loss dielectric material of the dielectric holder 236 may be the same or different than the low loss dielectric material of the front housing 200. In an embodiment, the dielectric holder 236 is overmolded over the contact array 234 and the lossy blocks 202. Thus, the dielectric holder 236 may be formed in situ over the contact array 234 by flowing the low loss dielectric material in a heated flowable state over the contact array 234 and allowing the low loss dielectric material to cool to a rigid state. In an alternative embodiment, the dielectric holder 236 may be formed by joining two pre-formed shell members together at an interface to entrap the contact array 234 between the shell members.
The lossy material of the lossy blocks 202 provides lossy conductivity and/or magnetic lossiness through a portion of the receptacle connector 102. The lossy material has dielectric properties that vary with frequency. The lossy material has a loss tangent that is greater or higher than respective loss tangents of the low loss dielectric materials of the housing 200 and the dielectric holder 236. The lossy material is able to conduct electrical energy, but with at least some loss. The lossy material is less conductive than the conductive material of the contacts 230, 232. The lossy material may be designed to provide electrical loss in a certain, targeted frequency range. The lossy material may include conductive filler elements, such as particles, dispersed within a dielectric binder material. The dielectric binder material, such as a polymer or epoxy, is used as a binder to hold the conductive filler elements in place. The conductive filler elements impart loss to the lossy material. In some embodiments, the lossy material is formed by mixing a binder with a filler that includes conductive particles. Examples of conductive particles that may be used as a filler to form electrically lossy materials include carbon or graphite formed as fibers, flakes, powders, or other particles. Metal in the form of powder, flakes, fibers, or other conductive particles may also be used as the conductive filler elements to provide suitable lossy properties. Alternatively, combinations of fillers may be used. For example, metal plated (or coated) particles may be used. Silver and nickel may also be used to plate particles. Plated (or coated) particles may be used alone or in combination with other fillers, such as carbon flakes. In some embodiments, the fillers may be present in a sufficient volume percentage to allow conducting paths to be created from particle to particle. For example when metal fiber is used, the fiber may be present at an amount up to 40% or more by volume. The lossy material may be magnetically lossy and/or electrically lossy. For example, the lossy material may be composed of a binder material with magnetic particles dispersed therein to provide magnetic properties. The magnetic particles may be in the form of flakes, fibers, or the like. Materials such as magnesium ferrite, nickel ferrite, lithium ferrite, yttrium garnet and/or aluminum garnet may be used as magnetic particles. In some embodiments, the lossy material may simultaneously be an electrically-lossy material and a magnetically-lossy material. Such lossy materials may be formed, for example, by using magnetically-lossy filler particles that are partially conductive or by using a combination of magnetically-lossy and electrically-lossy filler particles.
As used herein, the term “binder” encompasses material that encapsulates the filler or is impregnated with the filler. The binder material may be any material that will set, cure, or can otherwise be used to position the filler material. In some embodiments, the binder may be a thermoplastic material such as those traditionally used in the manufacture of electrical connectors. The thermoplastic material may facilitate the molding of the lossy block 202 into the desired shape and/or location. However, many alternative forms of binder materials may be used. Curable materials, such as epoxies, can serve as a binder. Alternatively, materials such as thermosetting resins or adhesives may be used.
In an embodiment, the lossy blocks 202 may be overmolded over the ground contacts 232. For example, the lossy blocks 202 may be formed in situ over the ground contacts 232 by flowing the lossy material in a heated flowable state over the corresponding ground contacts 232 and allowing the lossy material to cool to a rigid state. The lossy blocks 202 are formed on the ground contacts 232 prior to the contact array 234 being received in the dielectric holder 236. For example, in an embodiment, the contact module 214 is formed via a multi-stage overmolding process in which the lossy blocks 202 are overmolded over the ground contacts 232 in a first molding stage and the dielectric holder 236 is overmolded over the contact array 234 and lossy blocks 202 in a subsequent, second molding stage.
The receptacle connector 102 is assembled by loading the contact modules 214 into the cavity 218 of the front housing 200. The dielectric holder 236 may include latching features 258, such as deflectable latches and/or catches, configured to engage complementary latching features (not shown) of the front housing 200 to secure the contact module 214 in the cavity 218. The mating ends 242 of the signal contacts 230 and ground contacts 232 may be received in corresponding contact channels (not shown) of the front housing 200. When the receptacle connector 102 is mated to the header connector 104, the mating end 222 of the front housing 200 is received in the chamber 120 of the header housing 112. The mating ends 242 of the signal contacts 230 and the ground contacts 232 engage the corresponding signal and ground header contacts 114 to establish electrically conductive signal transmission paths between the receptacle and header connectors 102, 104. The header housing 112 optionally includes divider walls 260 within the chamber 120 that partition the chamber 120. The divider walls 260 may extend between the two signal contacts 230 in each signal pair 252 and between the two ground contacts 232 in each ground pair 250 when the receptacle connector 102 is mated to the header connector 104.
The signal contacts 230 and the ground contacts 232 in the contact array 234A have respective inner sides 302, outer sides 304, front sides 306, and back sides 308. The inner sides 302 of the ground contacts 232 in each ground pair 250 face each other and define an inner gap 310 between the ground contacts 232. The outer sides 304 of the ground contacts 232 in each pair 250 face away from each other and define portions of outer gaps 312 between the ground pairs 250 and adjacent signal pairs 252 in the same column 240. The front and back sides 306, 308 extend between the inner and outer sides 302, 304. In an embodiment, the lossy blocks 202 mounted to the ground pairs 250 extend into the inner gaps 310 of the ground pairs 250. For example, the lossy blocks 202 may engage the inner sides 302 of the ground contacts 232. The lossy blocks 202 may extend at least partially around the corresponding ground contacts 232, engaging the front side 306, the back side 308, and the inner side 302 of a corresponding ground contact 232. In an embodiment, the lossy blocks do not engage the outer sides 304 of the ground contacts 232. The lossy blocks 202 associated with a corresponding ground pair 250 optionally do not extend laterally outward beyond the outer sides 304 of the two ground contacts 232 in the pair 250. The lossy blocks 202 extend into the inner gap 310 between the two ground contacts 232, but do not extend into the outer gaps 312. In the illustrated embodiment, two lossy blocks 202 are associated with each ground pair 250. Each of the two lossy blocks 202 engages a different one of the two ground contacts 232 in the pair 250. The two lossy blocks 202 do not engage one another. For example, the lossy blocks 202 are separated from each other by a lossy block gap 314 within the inner gap 310. The lossy block gap 314 may be filled by the low loss dielectric material of the dielectric holder 236 (shown in
The signal contacts 230 and the ground contacts 232 each include opposite broad sides and opposite edge sides narrower than the broad sides. In an embodiment, the broad sides are the front and back sides 306, 308, and the edge sides are the inner and outer sides 302, 304. The contacts 230, 232 may be manufactured by stamping and forming, such as from a blank or sheet of stock metal material. The edge sides are defined by the sheared or cut edges during the stamping process. The broad sides are defined by the planar surfaces of the sheet of stock material. In an alternative embodiment, the contacts 230, 232 are oriented such that the broad sides are inner and outer sides 302, 304, and the edge sides are the front and back sides 306, 308.
In an embodiment, the lossy blocks 202 include a base 320 and arms 322 (for example, wings or ledges) extending from the base 320. The lossy blocks 202 may include two arms 322 extending generally parallel to each other in a common direction from the base 320. The arms 322 optionally extend an entire length of the lossy block 202. The corresponding ground contact 232, on which the lossy block 202 is mounted, extends between the two arms 322. The arms 322 engage the front and back sides 306, 308, respectively, of the ground contact 232, and a surface 324 of the base 320 between the two arms 322 engages the inner side 302 of the ground contact 232. In an embodiment, the base 320 comprises a majority of the size (for example, mass) of the respective lossy block 202, and the arms 322 comprise less than half of the size of the lossy block 202. Therefore, most of the lossy material of the lossy block 202 is disposed within the inner gap 310 between the ground contacts 232 in the associated ground pair 250. In an alternative embodiment, the base 320 comprises less than half of the size of the lossy block 202, such that a combination of the sizes of the arms 322 is greater than the size of the base 320. In an embodiment, no portion of the lossy block 202 extends beyond the outer side 304 of the ground contact 232 into the outer gap 312 between the ground pair 250 and a signal contact 230 of an adjacent signal pair 252. Arranging the lossy blocks 202 to extend within the inner gaps 310 and not into the outer gaps 312 may reduce detrimental cross-talk between the lossy material of the lossy blocks 202 and the surrounding signal contacts 230, while providing effective absorption of electrical resonance along the ground contacts 232.
In an embodiment, the lossy blocks 202 are formed via overmolding the lossy material over the ground contacts 232. Therefore, the base 320 and the arms 322 are segments or portions of the lossy blocks 202 defined by the shape of the mold and the shape of the ground contact 232. The arms 322 are the portions of the lossy material of the lossy block 202 disposed laterally between the inner side 302 and the outer side 304 of the respective ground contact 232. The base 320 is the portion of the lossy material disposed in the inner gap 310 between the two ground contacts 232 of the associated ground pair 250.
In an alternative embodiment, instead of two lossy blocks 202 that are associated with each ground pair 250 and spaced apart from each other by a lossy block gap 314, a single lossy block may extend between and mount to both ground contacts 232 in the ground pair 250. The single lossy block extends the width of the inner gap 310. The single lossy block absorbs electrical resonance from both ground contacts 232 in the associated pair 250.
The above described embodiments provide an electrical connector, such as a mezzanine connector, that provides lossy blocks along portions of the ground contacts. The lossy material absorbs at least some electrical resonance that propagates along the current path defined by the signal contacts and/or the ground contacts to provide lossy conductivity and/or magnetic lossiness. The lossy material provides electrical loss in a certain, targeted frequency range. Electrical performance of the electrical connector is enhanced by the inclusion of the lossy material. For example, at various data rates, including high data rates, return loss is inhibited by the lossy material. For example, the return loss of the small pitch, high speed data of the signal contacts due to the close proximity of signal and ground contacts is reduced by the lossy material. For example, energy from the ground contacts on either side of the signal pair reflected in the space between the ground contacts is absorbed, and thus connector performance and throughput is enhanced.
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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