Integrated signal pair element and connector using same

Integrated signal pair elements are disclosed that can be inserted into and removed from a backplane connector housing as a single piece. Each element includes an insulative frame that supports a pair of conductive terminals in a spaced-apart arrangement. The frame is attached to a ground shield that provides a ground plane that extends around three sides of the signal pair. Cable wires are terminated to tail portions of the signal pair and an insulative material is molded over the cable wire termination area to form an integrated signal pair element. The individual signal pair elements may also be commoned together in a linear array of signal pair elements by a commoning member that contacts the ground shields of the array of signal pair elements.

BACKGROUND OF THE PRESENT DISCLOSURE

The Present Disclosure relates, generally, to backplane connectors, and, more particularly, to improved cable assembly connectors utilized in backplane applications.

Existing backplane connectors which utilize waferized structures can be prohibitively expensive to tool-up. Wafers are designed to support a set number of signal pairs and ground elements associated with the signal pairs. These elements are supported by a frame typically formed from a thermoplastic and molded over portions of the signal and ground elements. As such, each particular wafer requires its own mold and stamping and forming operation. Thus, the costs required to tool up waferized connectors are large.

A customer usually needs to have very significant volume or a willingness to pay non-recoverable tooling fees for tooling up a new wafer. Each wafer count must be tooled as a new part including stamping dies, mold cavities, plating tooling, assembly tooling, and the tooling for assembling the connectors into finished cable assemblies as a mold for a four-pair wafer cannot be used to make either a three- or five-pair wafer. In essence, multiple sets of tooling are required to produce different pair count wafers. It is also somewhat costly to use the same stamping and forming equipment for terminal assemblies of different pair count wafers as the stamping and forming members must be changed for each particular count wafer, thereby not only incurring labor, but also increasing manufacturing time.

Existing backplane cable connectors that utilize a wafer construction do not easily support wiring schemes that are more complex than connecting all pairs from one column to another column. “Lettered” wiring schemes, such as W, X and Y wiring schemes where the pairs track the configuration of the particular letter are difficult to construct. A need therefore exists fir a connector that utilizes signal pair components that reduce the cost of manufacturing.

The Present Disclosure is directed to an improved connector that utilizes individual signal pair elements which may be inserted into a variety of differently configured connector housings and which overcomes the aforementioned disadvantages.

SUMMARY OF THE PRESENT DISCLOSURE

In accordance with the principles of the Present Disclosure, signal pair elements are provided with an integrated structure of signal terminals and ground terminals or shields that permit a connector designer to modify only the connector housing of a backplane connector assembly to accept a variety of signal pair arrangements. This concept eliminates the need for multi-pair wafers and replaces it with a single-pair element, or “chicklet,” concept in which the signal terminals and ground plane are integrated together in a single unit that is insertable and removable from a connector housing. For a new pair count connector assembly, the only structure that needs to be tooled is a front connector housing and its associated tooling, i.e., molds and inserts, should cost less than $25,000.00. This greatly reduces the cost of entry for new connector design programs, even for programs with smaller volumes as tooling for specific count wafers can approach and even exceeds $500,000.00.

If any single pair within a multi-pair wafer is bad (e.g., open, short, miswired, bad impedance or insertion loss) the entire wafer has to be discarded, with all of its associated signal terminals and ground planes, In doing so, a repairman must cut all of the wires associated with the bad wafer and terminate them to the replacement wafer, which increases the time and cost of repair. In the design of the Present Disclosure, only a single pair element needs to be replaced if it is bad and logically, only 2-3 wires will need to be terminated to a replacement signal pair element. This alone minimizes the amount of labor and materials that are lost to a defective single pair. Futhermore, because the smallest unit, or building block, of connectors of the Present Disclosure is a signal pair element, or chicklet, which integrates the signal pair and a ground plane together, it now is feasible to support complex wiring patterns in a connector housing in any W, X or Y fashion. In terms of system architecture, it means that pairs from one column on a line card can be split up to go to many other line cards.

In accordance with an embodiment as described in the following Present Disclosure, a signal pair element is defined by two elongated conductive signal terminals that extend longitudinally in a spaced-apart fashion. An insulative support frame is provided that supports the two signal terminals in their spaced-apart arrangement. The frame may have one or more openings that encompass portions of the terminals to control the characteristic impedance of the signal pair element at that location. The leading ends of the terminals include contact portions preferably formed as pins which engage corresponding contact portions of an opposing, mating connector. The terminals include tail portions at their opposite ends and wires of a cable are terminated to them, preferably by soldering, welding or the like.

A ground member, preferably in the form of a ground shield, is provided in association with each pair of signal terminals. The ground shield may have a general U-shaped configuration to define an elongated ground channel in which the signal pair terminals are supported. In this regard, the ground shield has a wide base that extend transversely to the longitudinal axes of the signal terminals and two spaced-apart sidewalls that are spaced transversely from the terminals and which define sides of the signal pair element. The frame is received within the interior of the ground shield and it serves to space the signal terminals from the ground shield base and sidewalls. Accordingly, the terminals are bounded on at least three of their four sides by a portion of the ground shield. The area where the cable wires are terminated to the signal terminals is filled with an insulative material, such as a hot melt, low density polyethylene, polypropylene or liquid crystal polymer, to enclose and protect the wire terminations and form an integrated assembly in which the signal terminals, ground shield and cable wires are formed as a single piece, which is insertable into and removable from a single opening in a connector housing.

The cross-sectional configuration of the signal pair elements is preferably rectangular, and square configurations can also be utilized so that a manufacturer need only make simple openings in the connector housing to receive the signal pair element. As such, the signal pair element introduces both a signal pair and an associated ground structure that maintains a desired spacing between the pair of signal terminals and between the signal terminals and ground shield. Thus, the in-pair spacing is easy to maintain and the out-pair spacing between nearby other signal pairs is likewise easy to maintain. The openings in the connector housing do not have to be separately made or formed in a complex manner, because the ground plane is already integrated into the signal pair structure itself such that one opening will accommodate one signal pair element.

As such, the signal pair elements of the Present Disclosure and connectors incorporating them distinguish themselves from known waferized connectors in that they utilize individual signal pair elements, or chicklets, rather than columns or rows of multi-pair wafers. Such known wafers populate their columns with two or more differential signal pairs and necessarily further include associated ground terminals or a ground plane, overmolded to maintain the spacing between the signal terminals and the ground structure. Often two wafer halves must be assembled and pressed together to form a completed wafer wherein where the ground structure of one wafer is partially shared by an adjacent wafer. As one can easily see, such a structure is complex and costly to tool.

In contrast, the individual signal pair elements of the Present Disclosure can be inserted into any suitable connector housing in either lettered arrangements for custom mating applications or in conventional rows and columns. The signal pair elements may be inserted either manually or by machine and the channel-like configuration of the ground shield provides a protective shell that protects the contact portions of the signal terminals during insertion into a connector housing. The integration of the ground shield with the terminal support frame means that it is not necessary to form ground elements in the connector housing arranged in a particular pattern to mate with ground elements of an opposing, mating connector.

The individual signal pair elements of the Present Disclosure may be ganged together in a row or a band by means of a metal commoning strap or bar that engages not only the ground shield of each signal pair element, but also the outer conductive wrap of the cable wires to interconnect multiple signal pair elements via their ground shields. An insulative resin may then be molded over portions of the support frame, terminals, cable wires, ground shield and commoning strap to form a single row of signal pair elements which can be easily inserted into a like number of openings in a connector housing.

These and other objects, features and advantages of the Present Disclosure will be clearly understood through a consideration of the following detailed description.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

While the Present Disclosure may be susceptible to embodiment in different forms, there is shown in the Figures, and will be described herein in detail, specific embodiments, with the understanding that the Present Disclosure is to be considered an exemplification of the principles of the Present Disclosure, and is not intended to limit the Present Disclosure to that as illustrated.

As such, references to a feature or aspect are intended to describe a feature or aspect of an example of the Present Disclosure, not to imply that every embodiment thereof must have the described feature or aspect. Furthermore, it should be noted that the description illustrates a number of features. While certain features have been combined together to illustrate potential system designs, those features may also be used in other combinations not expressly disclosed. Thus, the depicted combinations are not intended to be limiting, unless otherwise noted.

In the embodiments illustrated in the Figures, representations of directions such as up, down, left, right, front and rear, used for explaining the structure and movement of the various elements of the Present Disclosure, are not absolute, but relative. These representations are appropriate when the elements are in the position shown in the Figures. If the description of the position of the elements changes, however, these representations are to be changed accordingly.

FIG. 1illustrates a backplane connector20that utilizes an insulative connector housing22with a fiat base portion24and one or more sidewalls25a,2bthat extend out from the base portion24to define a slot therebetween. The housing base portion24, as illustrated best inFIG. 2has a plurality of openings26formed therein in a desired arrangement. InFIG. 2, the arrangement is one of staggered openings. Conductive signal and ground elements extend through and out of these openings as will be explained in greater detail to follow.

In conventional waferized backplane connectors, a series of signal elements are supported by insulative frame portions. Ground elements are also usually incorporated wafers used in these style connectors and because they are supported by the insulative frame, the ground elements must necessarily take the form of flat, planer elements. It is difficult to insert mold complex configured ground elements with “complex” meaning the ground elements have portions that extend in at least two different directions and three distinct planes. This structural limitation can hamper a backplane connector designer on the wafer side of the connector assembly. This may lead to crosstalk issues in the connector.

Accordingly, the Present Disclosure is directed at new backplane connectors and signal pair elements used therein. As shown inFIG. 4, the Present Disclosure provides a plurality of individual signal pair elements, or chicklets,30, which are insertable into the connector housing22such that the conductive elements thereof project through the connector housing openings26in alignment with an opposing mating connector (not shown). Each signal pair element30includes a pair of elongated, conductive signal terminals32a, bthat extend longitudinally of the element30. The signal terminals32a, bhave respective, opposing contact portions38and tail portions40which are interconnected by intervening body portions39.

In practice, the terminals are spaced from the inside surface of the ground shield sidewalls a distance of L and the terminals of the pair are preferably spaced apart a distance equal to about or equal to 2L as a preferred spacing. The terminals are also preferably spaced above the ground shield a height of about 40% of the height from the inner surface of the ground shield base to the top edge, with “top” taking the orientation as shown inFIG. 3.

The terminals32a, bare supported in an insulative frame34that includes a front mounting portion35and a rear mounting portion36that are spaced apart from each other in the longitudinal direction. These two mounting portions35,36extend transversely with respect to the terminals32a, band are overmolded onto the terminals. The mounting portions35,36include body portions that are disposed in the space between the terminal pair and may be joined, as illustrated inFIGS. 4C-D, to longitudinal portions that define, in effect, sidewalls37a, bof the support frame30. The two mounting portions35,36are joined to the sidewalls37a, band cooperatively define an open window42that exposes portions of the terminal body portions39to air. The sidewalk37a, bmay include portions that serve as crush ribs43on their upper surfaces, which assist in holding the signal pair elements30in place within the connector housing22. The bottom surface41of the support frame34is preferably flat as shown inFIG. 4G. The rear portion of the bottom surface41may include a recess41athat receives the support frame button63.

The support frame34is shown as further including an endwall44athat extends transversely and a pair of shoulder portions44bthat extend longitudinally rearwardly from the endwall44ato define a termination nest44cin which the terminal tail portions40extend. This area is overmolded with an insulative material45which serves to fix the termination of the signal pair element30to the cable wires48as well as maintains the signal pair spacing and alignment. The signal pair conductive elements include the aforementioned signal terminals32a, band also a ground plane element that is shown in the Figures as an elongated ground shield56. The ground shield56includes a base portion75which is generally flat and the shield includes a pair of upturned flanges that define sidewalls58a, bthat extend for almost the length of the ground shield56. The general U-shape that the ground shield56has provides a ground plane for each terminal pair that extends along three of the four sides of the terminal pair. Such a structure promotes coupling by the terminals in three different directions. The front end of the ground shield56may take the form of a mating blade as shown that provides a flat surface for contacting an opposing ground element of a conventional mating connector.

The rear end of the ground shield56is provided with a cable nest59that receives and supports a wire cable48having two signal wires49a, bthat are surrounded by outer insulative coverings50. A drain, or ground wire51, is typically provided for each wire pair49a, band it extends lengthwise through the pair underneath an outer conductive wrap52. A free end of the cable48is prepared as a termination end and has a length of the free end of each wire conductor49a, bexposed and the cable drain wire51folded back upon the cable48over the cable outer conductive wrap52. The cable nest59is spaced apart from the ground shield base57and offset by way of a tab62in the vertical direction from the ground shield base57, as best illustrated inFIG. 4C. The nest59further includes unable clamp60that has two arm portions60athat are folded over the cable48and crimped, or otherwise contacted to the cable outer wrap52. A pair of stablizing wings61extend outwardly from the cable nest59and serve to provide reinforcement for the rear, overmolded portion45of the element. These wings61will provide reinforcement for the overmolded portion45of the signal pair element, but also provide a contact platform, or surface, on which the cable drain wire is positioned fur soldering. Importantly, the drain wires51are folded backwards along the cable outer conductive wrap52so that it will not extend anywhere near the exposed free ends of the signal wires49a,49b.In this structure, the drain wires51extend in a direction opposite the direction in which the cable signal wire free ends extend.

The endwall44aand shoulders44bform a horizontal, general U-shape in the horizontal direction that partially encloses the terminal tail portions40and they cooperatively form a foundation for the overmolded portion45to adhere to the support frame34while enclosing the termination area, the cable nest59and the free ends of the cable wires48. The cable nest wings61are captured by this overmolded portion45, and they at least partially reinforce the area to resist failure during the assembly process if stress is applied to the signal pair elements. This area, as shown in4-A, also fills the area between the exposed wire conductors and their associated tail portions with a plastic-type material having a certain dielectric constant so that the impedance of the system in the termination area may be kept close or at a desired level.

Turning toFIGS. 4D-F, it will be noted that the signal terminals32a,32bhave irregular shapes, but are substantially mirror images of each other. In particular, the width of the terminals32a, bis narrowed in two areas, A1and B1, and these areas occur where the front and rear portions35,36of the support frame34engage the terminals32a, b. In these areas, the spaces between the terminals32a, bare filled in with the plastic or resin of the support frame34in order to maintain a desired amount of capacitive coupling between the signal terminals32a, bas well as between the ground shield56and the two signal terminals32a, b. The dielectric constant of the support frame material will be greater than the dielectric constant of air (1.0), so that in order to maintain a desired level of coupling between the signal pair, and the impedance profile through the signal pair element, it is preferred that the terminal widths in these areas are narrowed. The narrowing of the terminals in these two areas also creates edges along the sides of the terminals32a, bthat enhance the ability of the support frame material to fix the terminals in their desired spacing. Likewise, the width of the signal terminals32a, bin the window42of the support frame34is larger than in other areas as the terminals in that area are separated only by air.

The support frame34preferably engages the ground shield56in a manner that retains it and its terminals32a, bin a desired proper position. As shown one means for securing the support frame34to the ground shield56may include pairs of first and second stops,46,47respectively that protrude outwardly from the support frame sidewalls37a, b. These stops are preferably received within corresponding pairs of first and second slots65,66so that the facing edges of the stops46,47and the slots65,66contact each other. The slots65,66maybe configure as illustrated to include indentations or the like that engage protuberances on the stops46,47. An alternate means of engagement may include depressions formed on the support frame34and complementary-shaped indentations formed on the ground shield sidewalls58a, b.

The ground shield56may also include a raised member in the shape of an elongated button63that aligns the support frame with the ground shield. Elongated button63may be embossed, to aid in strength and rigidity of the ground shield at the location of the slots66. In order to retain the signal pair element30in place within the connector housing22, the ground shield56may include a catch portion, shown as a tongue or tab member64that is stamped in the ground shield base57and formed at an outward angle as shown best inFIGS. 2A-Bto catch on a secondary shoulder28to resist forces that would tend to pull the signal pair elements30out of their connector housing openings26. The support frame endwall44aconfronts and contacts a primary shoulder27formed in the connector housing22to limit the extent to which the signal pair element may be inserted into the housing opening26. The openings26, as shown, have a stepped configuration with central slots26aand shoulders26bso that interior surfaces of the shoulders26bwilt engage the support frame sidewall crush ribs43, and the interior surfaces of the slots26a(shown at the bottom of the slots ofFIG. 2) will engage the ground shield button63.

It can be seen that each of the signal pair elements, or chicklets,30form an integrated signal pair with two terminals suitable for transmitting differential signals and which are supported within an associated ground shield that at least partially encloses the terminals on three different sides thereof, leaving only one side with selected surfaces of the terminals exposed. These exposed terminals will be spaced apart from the ground shield bases of the signal pair elements above (or below, depending on the orientation) so that coupling may occur with the ground shield of an adjacent signal pair element. This is best shown inFIG. 3, where, in the staggered arrangement shown, it can be seen the two terminals of each signal pair element in the odd-numbered rows are aligned vertically with each other. Likewise, the terminals of each signal pair element in the even-numbered rows are aligned together in the vertical direction. Furthermore, the right terminal of each pair in the even-number rows2,4,6and8is approximately centered with respect to adjacent ground shields of signal pair elements located above or below in the odd-numbered rows, and the left terminal of each signal pair in the odd-number rows3,5and7is approximately centered with respect to adjacent ground shields of the signal pair elements above and below it. The signal pair elements in one row are offset from those in an adjacent row by about 4.7 min, or about 115 to about 120% of the width of a signal pair element.

This provides connectors utilizing the signal pair element with larger flexibility in design. These chicklets30are, in essence, individual building blocks of a backplane connector and may be arranged in a variety of different arrangements within a connector housing such as in lettered styles that display a C, H, O, U, X, Y or W configuration. Using such individual building block signal pair elements requires tooting costs only for simple the connector housings, which may only involve a single mold with different inserts, and not a complex one for complex wafers. For a new pair count in a connector design, only the connector housing needs to be tooled. If any signal pair in the connector is bad, only the bad signal pair element need be replaced, rather than discarding the entire wafer. The single signal pair element design therefore minimizes the labor and materials required to only that of a single pair element and not a multi-pair wafer, in which the conductive elements thereof need to be inserted into multiple openings in a connector housing.

FIGS. 6-7Billustrate an alternate embodiment of a signal pair element70according to the Present Disclosure, and one that is particularly suitable for use in ganged applications where a plurality of signal pair elements70are interconnected to form a linear array71of such elements70. The arrays70may then be inserted as a group to speed up the connector assembly process, but each signal pair element, i.e., the terminal pair and ground shield, are still inserted into corresponding single openings26of a connector housing22. It can be seen inFIG. 6that each signal pair element70supports a pair of conductive terminals72a, band an insulative support frame73. As with the prior embodiment, the support frame73and terminal pair72a, bare partially encompassed by an associated ground shield74that has a general U-shaped configuration with a flat base74athat is flanked by two sidewalls74b, c. The ground shield base74aand sidewalk74b, cextend around and partially encompass the terminals72a, bto present a ground plane on at least three sides of the terminal pair, providing coupling in three directions.

The rear end of the ground shield74includes a wire nest75that receives the free ends of a cable wire pair49a, btherein; this nest75includes portions of the ground shield sidewalk74b, cand an inner shoulder76that is stamped and formed from part of the ground shield74. Preferably, this inner shoulder76contacts the outer wrap52of the wire pair49a, band urges it into contact with the opposing sidewall74cof the ground shield74. A second lower shoulder76amay be provided as shown inFIG. 7Bwhich provides a second point of contact between the wire outer wrap52and the ground shield74along the bottoms of the wire pair49a, b. The top surface74bof the inner shoulder provides a surface to which the wire pair drain wire51may be connected.

A commoning member78is provided to interconnect multiple signal pair elements by way of their ground shields. The commoning member78extends transversely across the ground shield74and engages the ground shield sidewalk74b, cby way of complementary shaped shield tabs77and commoning member slots79. The commoning member78extends transversely with respect to the signal pair element70and may include, as illustrated, a raised bump or detent,80that accommodates the difference in heights between drain wire51and the cable pair outer wrap53. The commoning member78may be a singular member, that is, extending across only a single signal pair element ground shield, or it may extend further transversely and commonly connect multiple signal pair elements by way of their associated ground shields in the fashion of a linear array. As such, the commoning member78of this embodiment70serves a similar purpose as the wire nest ground clamp60of the prior embodiment.

An insulative material82is molded over the terminal tail portions, the wire pair free ends, the ground shield74and the commoning member78to form a structure that interconnects the signal pair elements70together in a linear array71that holds individual signal pair elements70in a desired arrangement. Although shown as an entirely linear array, it will be understood that the signal pair elements of such array may be out of plane, as if they were interconnected in an alternating arrangement of peaks and valleys or if they were interconnected in a vertical direction. The integrated structure of the singular signal pair element that permits single insertion of such elements into single openings of a connector housing permits the interconnection or ganging of multiple elements together to form arrays of elements. Such arrays will cut down the time needed for insertion of singular elements while still maintaining the integrated structure of the signal pair element which permits insertion of a single signal pair element into a single opening of a connector housing.

The signal pair elements of the Present Disclosure not only provide an economic benefit to a connector designer due to their reduced cost, especially when repair and/or replacement is considered, but also in electrical performance. A connector design of the type illustrated inFIG. 3was electrically modeled and compared against a model of a conventional waferized model. The modeling revealed that over the range of 2.5 to 15 GHz frequency the signal pair element concept of the Present Disclosure showed an improvement of between 4 and 10 dB as compared to the conventional waferized model and performed, for the most part better against it in the 15 to 25 GHz frequency range. This modeling showed that there was less energy coupled from the aggressor pair to the victim pair and that the majority of the energy at 25 GHz was below 17.5 GHz. Thus, the signal pair elements of the Present Disclosure also provide performance improvements.

While a preferred embodiment of the Present Disclosure is shown and described, it is envisioned that those skilled in the art may devise various modifications without departing from the spirit and scope of the foregoing Description and the appended Claims.