Electrical connector

Abstract: A shielded electrical connector having a housing and a cover each of which are formed by inmoulding an insulative portion respectively within a respective outer shield portion. Terminals are mounted within the housing and the housing and cover are joined together. Shielding characteristics are improved by a carrier strip interconnecting the shielding of adjacent connectors within a connector stack. Further shielding improvements are recognized by incorporating a contact surface external the shielding for engaging an outer reference terminal. The connector includes terminals having a floatable contact portion and a support feature for preventing damage to the terminals as a result of stubbing with a mating terminal. The connector being impedance matched to the cable.

Description: The subject of the invention relates to an electrical connector and, in particular, to a shielded electrical connector for use in high frequency cable applications. From EP 411888 A2 an electrical connector with a multi terminal plug and a multi terminal socket is known, in which a female terminal is composed of a contact section, a rear section for connecting to a conductor on a printed circuit board and an intermediate middle portion providing compliance between the front and rear portion. The contact portion and the rear portion are both fitted in a separate housing part. The two housing parts may move relative to each other, because of the compliance middle portion of the terminals. By this is achieved that misalignment of the contact section of the mating terminal plug can be compensated. In high frequency applications, the trend in industry is to increase the density of electrical connections while reducing the overall cost of the connector. The increase in density is significantly reducing the size of the connectors, along with the housings and contacts therein which has a direct affect upon electrical transmission characteristics and structural integrity. In addition, high frequency applications typically involve shielding the connector structure with a conductive member that is then interconnected to the conductive shielding of the high frequency cable. In high frequency applications, the best situation is when the impedance of the connector structure is exactly that of the impedance of the cable herein. This enables the connector structure to be essentially invisible to the cable, thereby providing the best possible data transmission capability for the particular connector/cable combination. As impedance is roughly dependant on the square root of the ratio of inductance over the capacity, when the density increases, the capacitance of a particular connector structure becomes higher and higher due to the small distances between the shielding and the conductors. This results in a lower impedance connector structure at the end of the cable. Difficulties arise in equalizing the impedance of the connector and the impedance of the cable in high density applications where the small dimensions associated with the high density effectively limit the amount of shielding and space between the contacts and the shielding that may be utilized to control the impedance of the connector. It would be advantageous to provide an electrical contact that enables the impedance of the connector to be matched with the cable. In high density applications, it is possible that some of the contacts and terminals are not in optimal alignment. There are many electrical terminals known in the art that electrically engage contacts of a mating connector, such as those having a deflectable beam that wipes a pin or tab contact surface as the interconnection is made. In an effort to accommodate the misalignment, float between the contacts and the terminal has been provided in some electrical interconnection devices. This float ensures that over a range of misalignment the contact and terminals can be correctly seated. Therefor, it would be advantageous to provide an electrical contact where the contact portion that electrically engages a mating contact can float relative the rest of the connector. However, in some smaller, high density applications where the terminals must also be quite small, the thickness of the deflecting beam also becomes small, thereby limiting the structural integrity of the terminal. In these applications, the terminal portion is prone to damage caused by "stubbing". "Stubbing" occurs when the mating tab or pin contact does not slide over the deflecting beam, but rather becomes stuck against it. The causes of "stubbing" can be traced to improper alignment during the interconnection or manufacturing deficiencies such as burrs. As a result of the contact not being able to slide over the deflecting beam, continued insertion typically will cause the beam to buckle and fail. Unfortunately, even if float is provided it is still possible for the contact and the terminal to stub when the connectors are initially mated together. In order to prevent damage from stubbing it would be desirable to provide support to the contact, thereby preventing buckling and the ultimate failure of the contact due to the excessive loading being transferred into the terminal as a result of the stubbing. In order to provide cost savings in order to produce the high density connectors, it would be desirable to incorporate into the contacts Insulation Displacement Contact (IDC) technology. Typically, high frequency cables will incorporate a TEFLON insulation about the conductor, so it would be desirable to incorporate into the contact IDC structure that is especially useful in terminating conductors encased in TEFLON insulation. In many applications, especially the data communications industry, the connectors used to form electrical interconnections must be shielded to prevent spurious electrical signals and noise from effecting the signals in the network. It is known in the art to provide conductive shielding around an electrical connector to prevent the adverse interference exterior of the connector from effecting the signals being conducted within the connector. Typically, the conductive shielding is formed as a metal shell that surrounds the terminal block of the electrical connector. The structure and components of a connector of this type is represented by the structure of the connector shown in US Patent 5,009,616. These connectors have a terminal block that contains electrical contacts that are connected to a cable. A conductive back shell is fitted around the terminal block and the cable. This conductive back shell is separate and distinct from the terminal block and is affixed thereabout by mechanical fasteners. While functionally adequate, having the shielding as a separate component that is distinct from the terminal block adds to the expense of manufacturing the connector. As the requirement for shielded connectors increases and the connectors themselves are miniaturized this expense becomes significant. It would be desirable to form an electrical connector incorporating shielding in an economical manner. It would also be desirable to provide a manufacturing technic that enables a high frequency and high density electrical connector to be formed in an economical manner. United States Patent No. 5,108,317 discloses an electrical connector having an outer metal shielding shell and a transverse opening therein. The metal shell and the pin contacts that make up the connector are positioned within a mold and a plastic septum is inmolded to the metal shell and about the pin terminals such that a sealed connector unit is formed. The plastic septum is mechanically joined to the metal shell by a dove-tail shape therein about which the plastic septum is inmolded. In addition, while the conventional shielding incorporated into the prior art connector described above has been adequate for the applications it was intended, it would be desirable to improve upon the shielding, especially in high density applications where it may be desirable to couple multiple connectors together into a connector stack. It is an object of this invention to provide an improved shielded electrical connector for high density applications. It is an object of this invention to provide an improved method of manufacturing a shielded electrical connector. It is an object of this invention to provide an electrical terminal having a contact end that floats relative a conductor engaging end for aligning with a mating contact. It is an object of this invention to provide an electrical terminal where the inductance of the terminal and/or its capacitance to the shielding is tailored to effect the overall impedance of the connector. It is an object of this invention to provide support to a contact portion of a terminal during mating with a complementary contact so that if the complementary contact stubs against the terminal continued insertion does not destroy the terminal. It is an object of this invention to provide improved shielding and grounding structure for a high density electrical connector. It is an object of this invention to make high density electrical connectors stackable. It is an object of this invention to provide additional reference paths for an electrical connector. It is an object of this invention to provide an improved insulation displacement structure for interconnection to insulated wires, and especially those having TEFLON insulation. It is an object of this invention to provide a low cost shielded data connector where the conductive electrical shielding and the corresponding portion of the terminal block have been incorporated into a single unit. It is an object of this invention to provide improved shielding characteristics within a compact and economical package. It is an object of this invention to prevent damage to the contact arms of an electrical terminal as a result of stubbing. It is an object of this invention to provide an electrical connector incorporating the forgoing objects. There is disclosed herein a shielded electrical connector that has an insulative terminal block having a terminal therein and an outer conductive shell surrounding the insulative terminal block and the terminals therein where the terminal block is inmoulded directly upon the shell to form a unitary structure. There is further disclosed herein a method of manufacturing the shielded electrical connector that comprises a shield portion and an insulative body portion where the shield portion acts as a palette for the direct moulding of the insulative body portion thereupon. Adjacent shielding may be interconnected by a conductive strap to provide improved positioning and grounding. Grounding contacts may be included along the outer shielding of a shielded electrical connector. Objects of this invention have been accomplished by providing an electrical connector as defined in claim 1. This connector includes a supporting feature along the wall of a housing wherein a terminal is disposed such that when a complementary terminal is mated therewith and stubs thereagainst the contact deflects against the supporting feature such that further insertion of the complementary contact is prevented from buckling the terminal. There is further disclosed herein a terminal having a contact portion interconnected to a conductor engaging portion by way of an impedance compensating section that has a tailored inductance and/or capacitance. The invention will now be described by reference to the attached Figures where: Figure 1 is an perspective view of an improved terminal according to the present invention; Figure 2 is an upper plan of the terminal shown in Figure 1; Figure 3 is a side view of the terminal shown in Figure 1; Figure 4 is a perspective view of an alternative embodiment of the improved terminal of Figure 1; Figure 5 is a partially cut away perspective view showing the improved terminal of Figure 4 within a first halve of a connector housing; Figure 6 is a perspective view of the terminal of the entire first connector halve of Figure 5; Figure 7 is an perspective view of electrical shield sections upon a carrier strip utilized in the manufacture of the connector housing partially shown in Figure 5 and Figure 6; Figure 8 is a perspective view of housing sections of the connector housing showing inmoulded housings within the shield section of Figure 7; Figure 9 is a cross-sectional view of the housing section of Figure 8 taken along line 9-9; Figure 10 is a perspective of cover sections of the connector housings showing the inmoulded cover section within shield sections of Figure 7; Figure 11 is a cross-sectional view of the cover section of Figure 10 taken along line 11-11; Figure 12 is a perspective over-view of the assembly process used to manufacture of the complete electrical connectors according to the present invention; Figure 13 is a perspective view of an alternative embodiment of the electrical connector of the present invention stacked with other similar electrical connectors to form a connector set; Figure 14 is a perspective view of a pin header that is engageable by electrical connectors according to the present invention; Figure 15 is a partially exploded perspective view of the connector set of Figure 8 incorporating a carrier strip; Figure 16 is a perspective view of the assembled connector set of Figure 15; Figure 17 is a partially exploded perspective view of the connector set of Figure 8 incorporating contacts as part of an alternative carrier strip; Figure 18 is a perspective view of the connector set of Figure 17; Figure 19 is a partially cut-away side view of the connector set of Figure 18 being received within the pin header of Figure 14; Figure 20 is an perspective view of an improved housing to prevent damage to contact arms as a result of stubbing by a mating contact; and Figure 21 is a side view showing the mating contact stubbing the terminal. With reference first to Figures 1-3, an electrical terminal is shown at 2. The electrical terminal 2 includes a base portion 4 which is separated into individual components 4a and 4b integrally interconnected by a flap portion 4c which stands upright to the base portions 4a and 4b. A contact portion 6 is connected to the base portion 4a and includes contact arms 8 which are twisted at 10 such that the planer surface 12 has been displaced through 90 degrees and is now providing parallel surfaces at contacts 14 for interconnection to a mating pin or tab contact (Fig. 14 and Fig. 21). Furthermore, the base portion 4b extends rearwardly through a stepped portion at 18 to provide a base portion 16 for an insulation displacement contact that is shown generally at 20. The stepped portion 18 is optional and, in the connector embodiments described below, is incorporated into terminals that need an offset so that the terminal can be be brought into contact with the shielding of the overall connector, as will be described below. The insulation displacement contact 20 of the terminal 2 is defined by forward upstanding and opposing walls 22 and rearward upstanding and opposing walls 24 to form U-shaped sections wherein the mating conductor is to be received. Each wall 22,24 includes an integral plate portion 26 and 28 respectively. The pairs of plates 26 and 28 face each other and are folded inward over the base portion 16 in a converging manner from their respective opposing walls 22,24 to define wire receiving slots at 30 and 32 respectively that take on a chevron-like configuration. It should be appreciated that each of the plate portions 26 and 28 include corners at 36,38 which form cutting surfaces for cutting through the insulation of an insulated conductor to be inserted therein, whereby the corners 36 and 38 can make contact with an electrical conductor forced transversely into the slots 30 and 32. Additionally, the converging pairs of plates 26 and 28 are oriented to converge towards each other, thereby assuring that pulling or pushing upon the conductor results in one set of plates 26,28 gripping in a selftightening manner. Furthermore, having the converging pairs of plates 26,28 converging towards each other enables more effective cutting of the insulation, such that the aforementioned structure is especially effective for cutting through TEFLON insulation. The pairs of converging plates 26,28 cooperate to grip the insulated conductor in a manner that enables effective cutting of the insulation by trapping a portion of the insulation therebetween. The contact portion 6 will float relative the insulation displacement portion 20 as a result of the configuration of the base portion 4. As the base portion 4 comprises two separated sections 4a and 4b that are interconnected by the upwardly folded plate portion 4c along one side thereof, the contact portion 6 can be displaced up-and-down and from side-to-side. The upwardly folded plate portion 4c acts as a spring element between the contact portion 6 and the insulation displacement portion 20. This float enables alignment and easy mating with the complementary contacts. With reference now to Figure 4, another embodiment of a contact is shown generally at 102. For convenience, corresponding reference numerals will be carried through in the 100 series of numbers for relevant features. As with the electrical terminal 2 described above, the alternative terminal 102 includes a contact portion 106 that includes a pair of opposed contact arms 108 that are twisted through 90 degrees at 110 such that what started out as the width of the contact arm 108 is now its height so that the larger planar surface 112 is provided at the contacts 114 for interconnection to a mating pin or tab terminal (Fig. 14 and Fig. 21). The contact arms 108 are of conventional cantilevered construction and converge towards each other at contacts 114 before diverging to form a mouth 115 for receiving the mating pin terminal. Opposite the contact portion 106 is a conductor engaging portion 116 shown in this embodiment as an insulation displacement contact 120. The insulation displacement contact 120 is defined by upstanding wall portions 122 and 124. The wall portions 122 and 124 are unitary with the contact 102 herein. Each of the wall portions 122,124 include integral respective plates 126,128 that converge towards each other to define wire receiving slots 130,132 respectively. Each of the plates 126,128 include corners 136,138 which form cutting surfaces for cutting through insulation and making contact with the electrical conductor therein when the conductor is forced into the receiving slots at 130,132. Between the cutting edges 138,136 is a central region 140 wherein a piece of the insulation is trapped between the two sets of plate portions 126,128. The contact portion 106 and the conductor engaging portion 116 are interconnected by base portion 104. The base portion 104 includes a rearward plate section 142 and a forward plate section 144 that are connected to the conductor engaging portion 116 and the contact portion 106 respectively. Located between the two plate sections 142,144 is middle portion 146. Middle portion 146 serves two functions. The first function of section 146 is to act as a positional spring similar to that described above with reference to the embodiment disclosed in Figures 1-3. As a positional spring, the middle portion 146 allows for the movement of the contact portion 106 up-and-down and from side-to-side in order to receive the mating pin or tab terminals therein. The second function of the middle portion 146 is to provide an increased inductance. As impedance depends upon the square root of the ratio of inductance over capacitance, impedance will tend to increase with an increase in inductance of the contact structure or a reduction in the capacitance. The particular design of this middle portion 146 will be selected based upon the actual connector configuration and the impedance of the cable to which the conductor is to be affixed. As the connectors are being miniaturized, the amount of free-air space within the connector is reduced as the dielectric of the housing fills a larger and larger portion of the space formed between shield members. The serpentine configuration shown in Figure 4 increases the effective length of the contact and produces a higher inductance. In the particular embodiment shown, the middle portion 146 is serpentine in nature and defines a notch 148 formed to receive a post 150 of a connector housing 152 (Figure 5) in order to position and retain the terminal 102 therein. Rearward of notch 148 is an opening 154 extending through rearward plate 142 of the middle portion 104. The opening 154 is created to reduce the capacitance between the contact 102 and the shield 156 (Figure 5 and Figure 6), thereby effecting an increase in overall impedance of the connector structure. By selectively establishing the configurations of the serpentine section at 146 and the opening 154 the impedance of the connector can be tailored to provide impedance matching with the cable to which it is to be attached. With reference now to Figure 5 and Figure 6, the electrical contact 102 is shown positioned in one halve of an electrical connector having an insulative housing 152 surrounded by a conductive outer shell 156a. The two pairs of outer terminals 102 are constructed as signal contacts as shown in Figure 4 and would be connected to the conductors of the two pairs of differential conductors within the cable. The inner contact is a grounding contact that would include a bend at 118 forward of rear plate section 142, similar to that shown at 18 in Figure 3. This bend enables the conductor engaging end 116 to be in direct contact with the shielding member while the contact arms 106 and the middle portion 104 are supported by the insulative material of the housing 152. With only this slight difference, either terminal 2 or 102 can be used as a signal contact (as shown in Figure 4) or a ground contact (as shown in Figures 1-3). With reference further to Figure 12, the illustrated embodiment of the present invention utilizes a pair of identical shield sections 156a,b to produce a housing 212 and a cover 214, each of which have an inmoulded insulative section 152 and 218 moulded directly thereupon as shown in Figure 8 and Figure 10 respectively. With reference now to Figure 7, the shield sections 156a have a flat bottom inner surface 220a with opposing side walls 222 that extend upward from the bottom surface 220a into outwardly extending flanges 224. The side walls 222 include ports 226 therealong that are used to retain the inmoulded insulative sections 152 and 218, as-described below. The flanges 224 include auxiliary ports 228 that are used to retain an overmoulded housing 229 (Figure 12). At one end of the shield sections 156a is a strain relief 230 that includes a pair of troughs 232 for receiving portions of a cable 234 (as further shown in Figure 12). Although desirable from an economics standpoint to use the same shield section 156a for both the housing 12 and the cover 14, differently configured sections may be used as required. To further emphasize that the shield sections need not be the same, when referring to the features of the shield section associated with the housing 212 the designation "a" will be included and the designation "b" will be included for the features associated with the cover 214. The shield members are manufactured using conventional stamping technics and may be left attached to carrier strip 236a,b. By leaving the shield sections 156a,b attached to the carrier strip 236a,b automated production technics may be easily incorporated into the manufacturing process, as is shown in Figure 12. With reference to Figure 8 and Figure 9, housings 212 are formed while the shield sections 156a are still on carrier strips 236a by moulding the insulative housing inmould section 152 directly onto the shield section 156a. The housing inmould 152 has a number of channels 238 for positioning therein signal-style terminals 102 (or those of Figure 1-3 without step 18). Channel 238a is exposed to the shield section 156a at location 239 so that a ground-style terminal 2 (or 102 with a stepped portion 118 disposed therein), as shown in Figure 6, may be connected to the shield section 156a as previously described to establish a central ground contact. Shielding or drain wires of a co-axial or twin-axial cable may be attached thereto. The channels 238,238a include a post 150 for retaining the terminal 2,102 therein. The housing inmould 152 is moulded directly onto the inner bottom surface 220a of the shield section 156a. This process enables the shield 156a itself to be used as part of the moulding structure, thereby reducing the costs required to manufacture and to advantageously enable low-profile shield-housing combinations to be produced. As there might be a tendency for the bottom surface to bow during the moulding process a hole 231 is included. In order to assure the inmoulded housing 152 is maintained in proper position within the shield section 156a, housing lugs 244a extend out of the ports 226a in the side walls 222a of the shield section 156a, as best seen in Figure 9. These lugs 244a are formed by allowing the material of the inmould 152 to flow outward through the ports 226a. Cavities are included in the moulding structure (not shown), where the shield 156a is seated that correspond to these lugs 244a. The lugs 244a are formed along the outside of each of the oppositely disposed side walls 222 into a shape that is larger than the ports 226a, whereby the moulded housing portion 152 on the inside of the walls 222a, which is also larger than the ports 226a, is captivated in the shield section 156a. This process forms an integral housing section 212 comprising both shield 156a and insulative housing inmould 152, while still maintaining the newly formed housing section 212 on the carrier strip 236a of the shield member 156a for further processing and connector assembly. With reference to Figure 10 and Figure 11, the cover 214 is formed by inmoulding the cover inmould 218 directly to shield section 156b while the shield section 156b remains upon respective carrier strip 236b. The cover inmould 218 is formed only at the front half of the shield 156b, thereby leaving a portion 223 of the central plate 220 of the shield 156b exposed, thereby minimizing the amount of dielectric to be used. The cover inmould 218 includes a forward row of upstanding lugs 225 and a rearward row of upstanding lugs 227 that, when the housing 212 and the cover 214 are assembled, assure the contacts 2 or 102 remain properly seated within their respective channels 238. As described above with reference to the housing 212, the cover inmould 218 is retained within the shield section 156b by cover lugs 246 that are an integral part of the inmould section 218 that has flowed out through the ports 226b of the shield section 156b. As will be apparent from a comparison of Figure 9 and Figure 11 the cover lugs 246 and the housing lugs 244 do not have to be similarly proportioned. In this particular embodiment, the cover lugs 246 can be observed to extend outward further along the flange 224b than the housing lugs 244 extend along the flange 224a. In addition to retaining the housing inmould 152 and the cover inmould 218 to their respective shield sections 156a and 156b, the housing lugs 244 and the cover lugs 246 can be configured to provide a polarizing or keying function. The lugs may be joined together to form rails, as shown and described with reference to Figures 13-19. It would also be possible to configure the lugs 244,246 to define the perimeter of the connector, so that the connector would be closely received within a mating receptacle or housing, or provide for any other function accomplished by the exterior of a connector housing where it is more advantageous to do so by way of moulding as opposed to incorporating these, possibly complex features into the stamping process used to form the shields 156a,b. With reference to Figure 12, the remaining assembly operations are presented in this drawing. The housings 212 are shown attached to their respective carrier strips 236a with the terminals 2 and 2a mounted therein. The covers 214 are shown above the housings 212 on terminal strip 236b. Proceeding left to right in the assembly overview, the next step shows portions of a twin-axial cable 234 inserted into the housing 212. The outer portion of the cable 234 is positioned in the troughs 232 of the strain relief 230a (Figure 8). It is possible for the conductive foil common to this type of cable to be exposed to the troughs 232 for electrical engagement therewith, thereby also commoning this portion of the cable to the shielding 156a,156b. The conductors of the cable 234 are terminated in their respective terminals 2 by pressing the insulated conductor into the insulation displacement portion of the terminal 2. The drain wires of a cable of this type may also be terminated in the ground contact 2a, if desired. Other configurations than insulation displacement may also be desirable for connecting the conductor to the terminal 2. The housing 212 and the cover 214 are separated from their respective carrier strips 236a,b as they are being brought together. In the next step, the cover 214 and the housing 212 are joined together to form an electrical connector 290. The housing 212 and cover 214 may be joined by mechanical features, resistance, laser or spot welding or another technic. In this embodiment, they are joined along the flanges 224a,b between the lugs 244,246 and along the strain reliefs 230a,b between the troughs 232. If desired, in a final step, an overmoulded housing 229 is moulded over the strain relief 230a,b and the rear ends of flanges 224a,b of the shield sections 156a,b. The material used in this overmould flows through the auxiliary ports 228 to form an integral unit that is anchored to the connector 290. This housing 229 provides additional strain relief for the cables and a way to easily handle the connector 201. It is an advantage of this invention that electrical connectors 201 having minimal thickness can be produced. This advantage may be further exploited by adapting connector 201 to enable the connectors 201 to be stacked together, thereby providing the highest density possible. As seen in Figure 12, the cover 214 and overmoulded housing 229 includes studs 292 extending above the shield section 136b through holes 294 (Fig.7) therein. As in this embodiment the shields 156a,b are identical, these studs 292 formed during the inmoulding of the cover 214 may be received in corresponding holes in the shielding 156a of the housing 212 so that they are positioned within seats (not shown) formed in the inmould 152 of housing 212. With reference now to Figure 13, such a connector stack is shown at 300. The connector stack 300 incorporates a pair of alternative embodiment electrical connectors 302 to the ones described above. While a connector stack 300 of two electrical connectors 302 is shown in the included figures, it is envisioned that additional connectors 302 may be advantageously. incorporated into the stack 300, as will be further described below. Each electrical connector 302 has a housing 312 and a cover 310 constructed basically as described above, where shields 311a,b have inmoulded insulative portion 316,318 respectively. The shield sections 311a,b are similarly U-shaped to those described above with a flat base 320 and upstanding side walls 122a,b. In this embodiment, the flanges 224a,b of the shields 156a,b described above, do not extend as far along the side walls 122a,b, instead they are shortened so that they are entirely encapsulated within the overmoulded strain relief housing 329, whereby sides 122a,b extend forwardly in an unconnected manner. At the front edge 325 of the shield 311a,b, within the plane of the base 320a,b, tabs 327a,b are formed that extend out beyond their respective sides 322a,b. The inmoulded insulative portions 316,318 are retained within their respective shield portions 311a,b as described above. However, rather than forming the multiplicity of lugs 244,246 extending from respective ports 226, single rails 344a,b are formed along the respective side walls 322a,b. These rails 344a,b are used to locate, polarize and aid in mating the connectors 302, individually or as part of a stack 300, with a mating header 350 (Figure 14). Once the connectors 302 are assembled, as described above, each connector 302 includes two pairs of signal ports 331 separated by a central grounding port 333. These ports 331,333 are open so the terminals 2,102 (described above, but not shown here) that are within the connector 302 can engage pin terminals 358 (Figure 14 and Figure 19) in the mating header 350. The header 350 includes a U-shaped moulded plastic housing 352 having a pair of outstanding walls 354 extending from a base 356 through which a plurality of pin terminals 358 extend. The pin terminals 358 have a pin end 360 for engagement by terminals, such as those constructed similarly to those depicted at 2 and 102 above. Opposite the pin end 360 is a conductor engaging end 362, in this case adapted for plated through-hole engagement with circuit traces incorporated into a substrate, such as a printed circuit board 364 (Figure 19). The interior surface 366 of walls 354 include grooves 368 and 370 for receiving the lugs 244,246 or rails 344a,b of the previously described connectors 201, 302 or 300 for positioning or polarizing relative the pins 358. While header 350 includes four columns of seven pin terminals 358 each, additional columns or pins may be included as desired. Furthermore, in order to incorporate a high density of pin terminals 358, the center-to-center spacing of 2 millimetres is achievable. In at least one form, the outer terminals 358a and the central terminal 358b are connected to a reference plane by way of the substrate 364 (Figure 19). Although the shielding offered by the outer shields 311a,b described above and the ground terminal within the central port 333 and connected to the drain wires of the cable the connector is attached to is adequate for numerous applications, improved shielding is sometimes desirable. In order to accomplish this, the prior art has resorted to enclosing the entire connector-header interface within a conductive housing and even going as far as wrapping the outside of the cable with a conductive foil. This is very expensive and adds considerable structure to the interconnection. With reference now to Figure 15 and Figure 16, the connector stack 300 of Figure 13 is shown with a pair of carrier strips 380 disposed therealong. These carrier strips 380 are conductive elements and are affixed to the shielding 311a,b of the connector 302, such as by laser welding, where an electrical interconnection is assured. Each carrier strip 380 includes a plate 382 extending forward from a strip 384 to fit between the tabs 327a,b extending from the shield 311a,b. Strip portions 386 extend from either side of the plate 382. Where only a single connector is being used, the carrier strip 380 is used to join the shields 311a,b together in a manner that provides positive electrical interconnection therebetween at the front of the connector and holds the front of the connector together in a manner that assures the overall height profile of the connector 302 is accurately maintained. As illustrated in Figures 15 and 16, where a plurality of connectors 302 are to be formed into a connector stack 300, the carrier strip 380 serves both mechanical and electrical functions with respect to the stack 300 and the individual connectors 302. Mechanically, the carrier strip 380 holds the shields 311a,b together at the front end of each connector 302 and assures the accurate pitch positioning of the connectors 302 within the stack 300 in order to minimize any inaccuracies resulting from tolerance build-up that may occur over the connectors 302. An opening 388 is formed between each plate 382 of the carrier strip 380 that is sized to receive adjacent tabs 327a,327b of the stacked connectors 302. Furthermore, when the connectors 102 are properly positioned, for example in a tooling fixture, such that the ports 331,333 are located to comply with pin terminals 358 of the header 350, affixing the carrier strip 380 assures that the desired positioning will be maintained, thereby enabling stacks 300 containing a large number of connectors 302 to be realized. Electrically, as the carrier strip 380 is conductive, the carrier strip 380 acts not only to interconnect the shields 311a,b of the same connector 302 but also to electrically interconnect the shielding of all of the connectors 302 within the stack 300. The electrical interconnection, by way of the carrier strip 380, provides a conductive strip across both sides of the stack 300, thereby improving the low frequency performance of the connector stack 300. The performance benefits are provided without detracting from the other desirable features of the connector package, for example the size of the connector and the use of the rails 344. With reference now to Figures 17 and 18, another carrier strip 390 is presented. This alternative carrier strip 390 is of ladder-type configuration, having a front bar 392 constructed basically the same as carrier strip 380 of Figures 15 and 16 and which performs basically the same function. A rear bar 394 that is generally parallel to the front bar 392 and is spaced therefrom so that the front bar 392 is at the front of the rails 344a,b while the rear bar 394 is at the rear of the rails 344a,b. A contact rung 396 extends between the front bar 392 and the rear bar 394. These contact rungs 396 are constructed to fit between the rails 144a,144b when at least the front bar 392 is attached to the shields 310 of the connectors 302. The contact rungs 396 are bowed to space-the bowed portion 399 away from the sides 322a,b of the shields 311a,b so that the bowed portion 399 may act as a contact surface for engaging a contact pin 358 of the header 350 (Figure 14). This configuration is especially useful for headers 350 incorporating a popular configuration that utilizes multiple seven pin terminal columns with the outer terminals 358a and the central terminal 358b being reference or ground terminals. In this application the central terminal 358b is received within the central port 333 to electrically engage the contact therein and the bowed surface 399 of the contact rungs 396 engages the respective outer terminal 358a (Figure 19). This configuration improves the reference, or grounding, of the connector 302 by providing two additional reference paths along the outer boundaries of each of the connectors 302, thereby enhancing the shielding characteristics of the connector, which is especially helpful with respect to high frequency applications that are EMI/RFI critical. Especially advantageous is that the improved shielding characteristics can be achieved by the carrier strips 380,390 without effecting the basic size and configuration of the connector stack 300, thereby minimizing costs. In the case of carrier strip 390, additional contact surfaces 399 are incorporated into the connector stack 300 without effecting the rails 144a,144b or their function. With reference now to Figure 20, terminals, such as signal terminals 2 or grounding terminals 2a, are mounted in a channels 238 of a connector housing portion 212, as described in greater detail above with reference to Figures 5-12. The terminals 2,2a are maintained in position within the channel 238 at least in part by post 150 that corresponds to a notch 148 (Figure 5). A support member 460 that prevents damage to the contact arms 8 from stubbing with a mating terminal 358 is also incorporated along the forward end of the channel 452 at a location that generally corresponds to the inwardly converging and outwardly diverging portion of the contact arms 8, which is semi-circular and designated 44 in Figure 21. With further reference to Figure 21, the tab or pin contact 450 of the mating connector, possibly similar to that shown in Figure 14, can enter the housing misaligned to such an extent as to "stub" against one of the contact arms 8. This "stubbing" occurs when the contact 50 comes into contact with one of the contact arms 8 in such a manner that the-contact 450 does not slide along, and thereby deflect the contact arm 8 to produce a wiping interconnection. In order to overcome the "stubbing", the terminal needs to be supported along the contact arms 8 as the pin or tab contact 450 is inserted to prevent the buckling of the terminal, enabling the stubbed condition to be overcome without damaging the contact arms 8 as the contact 50 and the terminal are interconnected. The support member 460 is positioned within the channel 452 so that it can supportingly engage the region 44 on the back of the contact arms 8 in a manner that provides sufficient back-up to the diverging lead-in portion of the contact arms 8 to prevent buckling. The support member 460 is shown as being unitary with the walls of the channel 452 and having a generally triangular cross-sectional shape with a radiused peak. The support member 460 may take on any number of other shapes that could interact with the contact arms 8 in the desired manner by transferring the loading into the housing 54, rather than along the contact arms 8 and into the terminal where damage could occur in another part of the overall connector structure. As the terminal is prevented from moving longitudinally within the channel 452 by the engagement of the post 150, continued insertion of the contact 50 causes the front portion 6 of the contact to deflect until the contact leg 8 comes into contact with the support member 460 positioned along the channel 52. As the lead-in portion 44 is now supported, the stubbing can be overcome as the insertion forces associated with mating are transferred into the housing containing the terminal. While this aspect of the invention has been described in relation to the terminals, housings and connectors according to the present invention, this should not be a limitation. The concept is easily transferable to other configurations.

Claims: An electrical connector for establishing an electrical connection with a contact (450) of a mating device, comprising a housing (156) having at least one row of channels (238) therethrough; a terminal (2, 102) mounted within each channel (238), said terminal (2, 102) having a front contact portion (6, 106) constructed to electrically engage the contact and a rear conductor engaging portion (20, 120) that are interconnected by a middle portion (4, 104) therebetween, the middle portion (4, 104) acting to provide compliance between the front contact portion (6, 106) and the rear portion (20, 120); said connector being characterized in that a support feature is (44) included on the front contact portion (6, 106) of the terminal (2, 102) and a support member (460) is disposed along the channel (238) of the housing corresponding to the support feature (44) of the terminal (2, 102) and configured to supportingly engage the support feature (44) during connection with the contact (450) to limit the loading imposed on the terminal (2, 102) and further characterized in that the contact section (6, 106) floats within the channel (238) for alignment with the mating contact (450). The electrical connector of claim 1 characterized in that the connector comprises an outer shielding shell and an insulative housing therein, where the terminal has an impedance compensation feature therein. The electrical connector of claim 2 wherein the impedance compensation feature is an opening through the terminal. The electrical connector (201; 302) of claim 1, further characterized in that the connector (302) comprises a conductive outer shield (156a,b; 311a,b) surrounding inner insulative housing (152; 218) that is inmolded directly upon the conductive outer shield (156a,b; 311a,b) and in that the electrical connector (201; 302) includes a housing portion (212, 214; 312, 310) including a portion of the conductive shield (156a,b; 311a,b) and an inmolded portion (152, 218; 316, 318) of the inner housing. The electrical connector (201; 302) of claim 4 further characterized in that one of the conductive outer shield portions (156a,b) includes a port (226a,b) therethrough wherein a portion (244, 244b) of the respective inmolded insulative housing (152, 218) extends through the port (226a,b). The electrical connector (201; 302) of claim 5 further characterized in that the portion (244; 244b) of the insulative housing (152; 218) extending through the port (226a,b) is formed as a positioning member for positioning the connector relative a mating connector. The electrical connector (201; 302) of claim 4 further characterized in that the contact section (106) is interconnected to a rear conductor engaging section (120) by an impedance compensation section (104) wherein the inductance and/or the capacitance is tailored such that the connector is approximately invisible to the shielded cable.

Inventors: DEN OTTER JOHANNES MARINUS JAC, SMITS WILLEM REGINALD MARIA, SOES LUCAS, WIEKAMP JAN HENDRIK ATE, DEN OTTER, JOHANNES MARINUS JACOBUS, SMITS, WILLEM REGINALD MARIA, SOES, LUCAS, WIEKAMP, JAN HENDRIK ATE
Applicants: WHITAKER CORP, THE WHITAKER CORPORATION
Application year: 1995
Main classification: H01R13
IPC codes: H01R13, H01R43