Computing device using bypass assembly

A computing device includes a first connector near a first wall. The first connector is in communication with a chip package positioned apart for the first wall via a first cable. The chip package includes a chip supported by a support layer. The chip can be supported by a substrate and/or a circuit board. A second connector can be positioned near a second wall and can also be in communication with the chip package via a second cable. If desired, the substrate or circuit board can include a signal board connector that is configured to engage board connectors terminated to ends of the first and second cables.

TECHNICAL FIELD

This disclosure relates to field of high frequency signaling, more particular to computing systems positioned in a chassis.

DESCRIPTION OF RELATED ART

Computing devices such as routers, servers, switches and the like need to operate at high data transmission speeds in order to serve the rising need for bandwidth and delivery of streaming audio and video in many end user devices. These devices include a chassis that supports a circuit board that in turn supports various circuits and use signal transmission lines that extend between a primary chip member, such as an application specific integrated circuit (ASIC), field programmable gate array (FPGA), digital signal processor (DSP), etc., mounted on the circuit board and connectors mounted to the circuit board. These transmission lines are formed as conductive traces on or in the circuit board and extend between the chip member(s) to external connectors or circuitry of the device.

As can be appreciated, the integrated circuits (often referred to as chips) are the heart of these electronic devices. These chips typically include a processor and this processor has a die that can be connected to a substrate (its package) by way of conductive solder bumps. The package may include micro-vias or plated through holes which extend through the substrate to solder balls. These solder balls can comprise a ball grid array by which the package is attached to the circuit board. The circuit board includes numerous traces which designated define transmission lines that include differential signal pairs, ground paths associated with the differential signal pairs, and a variety of low speed transmission lines for power, clock signals and other functions. These traces are routed from the ASIC to the I/O connectors of the device into which external connectors are connected, as well as others that are routed from the ASIC to backplane connectors that permit the device to be connected to an overall system such as a network server or the like, or still others that are routed from the ASIC to components and circuitry on the motherboard or another circuit board of the device.

Typical circuit boards are usually formed from an inexpensive material known as FR4, which is inexpensive. Although inexpensive, FR4 is known to be lossy in high speed signal transmission lines which transfer data at rates of about 6 Gbps and greater (e.g., above 3 GHz signaling frequencies). These losses increase as the frequency increases and therefore make FR4 material undesirable for the high speed data transfer applications at signaling frequencies of about 10 GHz and greater. In order to use FR4 as a circuit board material for high frequency signal transmission lines a designer may have to utilize amplifiers and equalizers, which increase the final cost of the device.

The overall length of the signal transmission lines in FR4 circuit boards can exceed threshold lengths, about 10 inches, and may include bends and turns that can create signal reflection and noise problems as well as additional losses. As noted above, losses can sometimes be corrected by the use of amplifiers, repeaters and equalizers but these elements also increase the cost of manufacturing the final circuit board and further complicate the layout of the circuit board. In addition, the routing of signal transmission lines in the circuit board may require multiple turns and/or transitions. These turns and the transitions, which occur at termination points along the signal transmission lines, tend to reduce the signal to noise ratio. In addition, transitions and terminations tend to create impedance discontinuities that cause reflections in the signals, making it difficult to overcome the signal to noise issue by simply increase the power of the transmission. As a result, the use of a circuit board, especially with the use of FR4 but even with the use of more costly materials, to route signals over distance becomes increasingly difficult as data rates increase. Consequentially, certain individuals would appreciate further improvements.

SUMMARY

A bypass assembly is used to provide a high speed data transmission line extending between a device chip or chip set and backplanes or circuit boards. The bypass cable assemblies include cables which contain signal transmission lines that can avoid, or bypass, a supporting circuit board, no matter the material of construction.

In such applications, an integrated circuit having the form of a chip, such as an application specific integrated circuit (ASIC) or field programmable gate array (FPGA), is provided as part of an overall chip package. The chip can be mounted on a package substrate by way of conventional solder bumps or the like and may be enclosed within and integrated to the substrate by way of an encapsulating material that overlies the chip and a portion of the substrate. The package substrate can include traces or leads that extend from the solder bumps on the chip bottom to a termination area on the substrate. The substrate can further support a connector or contact pads or can alternatively be mounted on a circuit board that includes traces that couple communication points on the substrate to contact pads on the circuit board. A first connector can then be mounted on the circuit board for interfacing with a cable assembly. If desired, the first connector can be mateable with a second connector. Cables, which are terminated to either the first connector or the second connector, extend to external interfaces, such as I/O connectors and backplane connectors.

The chip package may include a plurality of contacts in the form of solder balls disposed on the underside of a chip package for providing connections to and from logic, clock, power and low-speed and high speed signal circuits to traces on the motherboard of a device in which the chip package is used. If the substrate directly supports a connecting interface then the contacts associated with the high speed signal circuits of the chip are removed from the bottom of the chip package inasmuch as the high speed traces are no longer routed to the bottom of the chip package. However, if the substrate is mounted on a circuit hoard then high speed traces may be routed to the circuit board and extend some short distance to an appropriate connector.

Cables utilized for such assemblies can be designed for differential signal transmission and preferably are twin-ax style cables that utilize pairs of signal conductors encased within dielectric coverings to form two wires, or a signal wire pair. First ends of the wire pairs are typically terminated to corresponding chip packages and second ends these wire pairs are terminated directly to terminals of entry or exit connectors, such as I/O and backplane connectors.

DETAILED DESCRIPTION

The detailed description that follows describes exemplary embodiments and is not intended to be limited to the expressly disclosed combination(s). Therefore, unless otherwise noted, features disclosed herein may be combined together to form additional combinations that were not otherwise shown for purposes of brevity. As such, references to a feature or aspect are intended to describe a feature or aspect of an example, 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, 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.

As can be appreciated, the discussion that follows relates to signal transmission. Signals are often referred to as low speed or high speed by persons of skill in the art, depending on the data rate (low data rates being referred as low speed signals and high data rates being referred to as high speed signals). While such nomenclature is technically not the most precise way to refer to such matters, to be consistent with typical usage the low speed/high speed convention will also be used herein.

Embodiments depicted herein are suitable for use with high speed data signal transmission line systems that support high data rates at low losses from chips or processors and the like to backplanes, mother boards and other circuit boards. An assembly is disclosed that connects the chip package of a device to entry connectors (which can be used to provide signals into or out of the device) without significant use of traces on a circuit board so that reduced losses are possible. If desired, an improved connector for use as an entry connector can be connected directly to cables or wires, rather than traces on circuit boards, to define signal transmission lines from the connector directly to chips and processors of the host device. Such a configuration is helpful for what is considered high speed data applications (above 10 Gbps) and above typically will be beneficially utilized in systems operating above 15 Gbps if NRZ encoding is being used. Because the receptacle connectors can be contained entirely within the connector structure and do not need to be directly connected to a circuit board, the bottom wall of the cage can be continuous in its extent to completely seal off the bottom of the cage and thus can improve EMI performance of the connector. The use of press-fit pins to mount the connectors can also be eliminated. Pairs of connector elements in the form of wafers are provided which fit into an opening in the rear of the receptacle connector. A primary ground plane is provided between the connector elements to block signal interference, such as crosstalk, between the signal terminals of the two connector elements. Accordingly, the connectors may be mounted individually to a face panel or a wall of the host device, or even interconnected with other connectors to form an integrated assembly of connectors that are suitable for vertical or horizontal stacking. Furthermore, if desired, the connector can be positioned within the host device as an internal transition connector that can be supported on a circuit board, on standoffs or other supports or stand alone. This structure defines connectors with high speed connectors that form signal transmission lines useful for high speed data applications at 10 Gbps or above that can bypass circuit traces on the host device circuit board.

The data rates of the devices for which the above-described connectors is used are quite high (10 Gbps and often 20 Gbps+) and often the connectors are used with active cable assemblies that tend to generate substantial heat during data transmission. The connector may further include a heat sink assembly that extends into an interior portion of the cage and which is configured to make contact with the mating module inserted into the cage. The cage includes walls that cooperatively define the interior which houses a receptacle connector. Inasmuch as these cages may often be mounted along a face panel of the host device, a heat sink assembly is provided that includes a transfer portion which makes contact with the mating module inserted into the cage, and a dissipating portion connected thereto, which is depicted spaced apart from the transfer portion in a horizontal direction. In this manner, the heat-dissipating portion beneficially extends rearwardly of the shielded cage and will include downward facing fins. This structure takes advantage of the open space behind the cage and may provide a reduction in overall height of the host device, assuming the airflow configuration can be set up accordingly.

In an embodiment, the terminations to at least one set of the connectors are configured so that the second ends of the wire pairs are terminated in a manner and spacing that emulates the ordered geometry of the cable so that crosstalk and other deleterious factors are kept to a minimum at the connector location. In such a configuration all of the connector terminals have the same length. The free ends of the signal terminal pairs are arranged in desired spacings and include associated grounds so that the ground associated with each wire pair may be terminated to a corresponding ground of the connector to define an associated ground that extends the entire length of the cable and its connector. This arrangement will provide shielding, and reduction of cross talk, by defining a ground plane to which the signal terminals can couple to in common mode, while pairs of signal terminals can couple together in differential mode. The termination of the cable wires to the connectors can be done in a manner such that to the extent possible, a specific desired geometry of the signal and ground conductors in the cable is maintained through the termination of the cable to the connector.

A single chip package may be provided that includes an integrated circuit mounted to a substrate. The substrate has termination areas to which first ends of a plurality of twin-ax cables are terminated. The lengths of the cables may vary and will be long enough for some of the cables to be easily and reliably terminated to first external interfaces in the form of a single or multiple I/O style connectors which are part of an external connector of either, or both of the entry and exit connectors. These connectors may be preferably mounted to a panel of the host device in a fashion that permits external connectors, such as plug connectors or pluggable modules to be mated therewith. The assemblies may have their cables extend between entry connectors of the device and the chip package formed as an integrated assembly, or they may further include additional cables that extend between the chip package and exit connectors of the device. The first ends of the bypass cables may be configured so that they may be inserted into connectors on the chip packages so as to have “plug and play” capability. In this manner, the external connectors can be inserted into the host device as single or ganged elements, each containing one or more signal transmission channels. The chip package may be supported within the cage of the device either solely or by way of standoffs or other similar attachments to a low cost, low speed motherboard.

Removing the signal transmission lines from the chip to the external connectors off of the motherboard in this manner frees up space on the motherboard which can accommodate additional functional components to provide added value and function to the device, while maintaining a cost that is lower than a comparable device that utilizes the motherboard for signal transmission lines. Furthermore, incorporating the signal transmission lines in the cables of the bypass assembly reduces the amount of power needed to transmit high speed signals from the chip packages to the external connectors, thereby increasing the “green” value of the bypass assembly and reducing the operating cost of devices that use such bypass assemblies.

The cables extending between connectors and the chip packages are preferably of the “twin-ax” style, with two wires in each cable so that a pair of signal conductor are running lengthwise of the wire, enclosed in a dielectric covering. The pairs of wires are preferably terminated to receptacle connectors at the proximal ends of the cables and at their distal ends directly to the chip packages. The receptacle connectors are preferably contained within a connector structure, such as a cage, adapter frame or the like and cooperate with the connector structure to define a shielded cage configured to receive an external connector, such as a pluggable module. The second ends of the cable wires are terminated directly to the terminals and grounds of the receptacle connectors, and the cables are preferable held in wafer-like supports to define terminal rows on opposing sides of card slots of the receptacle connectors. The cables exit the connector structure through the rear wall thereof.

Turning to the figures,FIG. 1is a perspective view of a computing device50such as a switch, router, server or the like, and with the cover of the host device removed. The computing device50is governed by one or more processors, or integrated circuits, in the form of a chip52(which can be one or more discrete chips packaged together) that may be part of an overall chip package54. The device50has a pair of side walls55and first and second walls,56,57. Connectors80(which can be in the form of an input/output or IO connector) are provided in the first wall56(which can be a front wall) of the host device so that opposing mating connectors in the form of pluggable modules and the like may be inserted in order to connect to circuits of the device50. Backplane connectors30may be provided in a second wall57(which can be a back wall) for connecting the device50to a larger device, such as a server or the like, including backplanes utilized in such devices. The device50includes a power supply58and cooling assembly59as well as a motherboard62with various electronic components thereupon such as capacitors, switches, smaller chips, etc.

FIG. 3Ais a cross-sectional view of a prior art conventional chip package and motherboard assembly that is used in conventional devices. The chip52may be an ASIC or any another type of processor or integrated circuit, such as a FPGA and may be one or more separate integrated circuits positioned together. Accordingly, the term chip will be used herein as a generic term for any suitable integrated circuit. As shown inFIG. 3A, the chip52has contacts on its underside in the form of solder bumps45that connect it to associated contact pads of a supporting substrate47. The substrate47typically includes plated through-holes, micro-vias or traces48that extend through the body of the substrate47to its underside. These elements48connect with contacts49disposed on the underside47aof the substrate47and these contacts49typically may take the form of a BGA, PGA or LGA and the like. The chip52, solder bumps45, substrate47and contacts49all cooperatively define a chip package52-1. The chip package52-1is mated, by way of a socket (not shown) to a motherboard52-2made of FR4 material and used in a device. The motherboard62has a plurality of lengthy conductive traces52a-cthat extend from the chip package contacts49through the motherboard to other connectors, components or the like of the device. For example, a pair of conductive traces52a,52bare required to define differential signal transmission line and a third conductive trace52cprovides an associated ground that follows the path of the signal transmission line. Each such signal transmission line is routed through or on the motherboard and such routing has certain disadvantages.

FR4 circuit board material becomes increasing lossy and at frequencies above 10 Ghz this starts to become problematic. Additionally, turns, bends and crossovers of these signal transmission line traces52a-care usually required to route the transmission line from the chip package contacts49to connectors or other components mounted on the motherboard52-2. These directional changes in the traces52a-ccan create signal reflection and noise problems as well as additional losses. Losses can sometimes be corrected by the use of amplifiers, repeaters and equalizers but these elements also increase the cost of manufacturing the final circuit board52-2. This complicates the layout of the circuit board52-2because additional board space will be needed to accommodate such amplifiers and repeaters and this additional board space may not be available in the intended size of the device. Custom materials for circuit boards are available that reduce such losses, but the prices of these materials severely increase the cost of the circuit board and, consequently, the electronic devices in which they are used. Still further, lengthy circuit traces require increased power to drive high speed signals through them and, as such, they hamper efforts by designers to develop “green” (energy-saving) devices.

FIG. 3Bis a cross sectional view of the chip package54that can be used in the device50ofFIG. 1. The chip52contains high speed, low speed, clock, logic, power and other circuits which are connected to the chip package substrate53. Traces54-1of the package54lead to associated contact pads54-2arranged in termination areas54-3, that are preferably disposed at or proximate to edges54-4of the substrate53. The chip package54may further include an encapsulant54-5, such as an epoxy, that fixes the chip52in place within the package54as an integrated assembly along with associated cable connectors and other components. The chip package54, as illustrated, be connected in part, to the motherboard by way of solder bumps49, but such connections do not need to include high speed signal transmission lines in place on the circuit board62. However, as discussed below with respect toFIGS. 22-29A, the supporting circuit board can include high speed transmission lines if they travel a short distance. For example, the traces52a-ccould quickly terminate to a connector provided on the circuit board62just outside an outer edge of the substrate47.

If cables are to terminate directly to the substrate then the cables60can be terminated to the package contact pads54-2by suitable wire-to-board connectors and the like, and these cables60are preferably of the twin-ax construction with two signal conductors61surrounded by a dielectric covering61-1. The cables60can also include an associated drain wire61-2and an outer shield61-3and a finished insulative outer jacket61-4. (FIG. 2D.) The use of one or more drain wires is optional, as is the outer shield (which can be in the form of a conductive wrap, braided shield or the like). In some instances, the two conductors may be encased in a single dielectric covering. The spacing and orientation of the wires that make up each such wire pair can be easily controlled in a manner such that the cable provides a transmission line separate and apart from the circuit board, and which may extend between a chip, chip set, component and a connector location on the circuit board or between two locations on the circuit board. In certain embodiments the ordered geometry of the cables as transmission components makes it easier to maintain a transmission line with acceptable losses and noise as compared to the difficulties encountered with circuit board signal transmission lines.

As noted above, the cables60and their signal conductor pairs define high speed signal transmission lines that lead from the chip package54to the first (entry) or second (exit) connectors80,30. The ordered geometry of the cables maintains the signal conductors as pairs in a preselected spacing to control the impedance therethrough. Utilizing the cables as signal transmission lines can eliminate the need to lay down high speed signal transmission lines in the form of traces on the motherboard, thereby avoiding high costs of exotic board materials and the losses associated with cheaper board materials such as FR4.

As illustrated inFIGS. 2-2C, the cables60have opposing first and second ends163,164that are respectively connected to the chip package54and the connectors80(which could be a first connector) or backplane connectors30(which could be a second connector) to define high speed signal transmission lines that bypass the motherboard. The cables60maintain the ordered geometry of the signal conductors throughout the lengths they traverse to and from the chip via the external interfaces. The ordered geometry of the cables permits the cables to be turned, bent or crossed in their paths without introducing problematic signal reflection or impedance discontinuities into the transmission lines which can occur in circuit board signal transmission lines. The cables60are arranged in first and second sets of cables, with the first cable set extending between the connectors80and the chip package54, and the second set of cables extending between the chip package54and the connectors30in the second wall57of the device. The manner in which the signal conductors of the cables60may be terminated to the chip substrate can vary. As illustrated inFIG. 2C, the cables60may be terminated by way of wire-to-board connectors66, which can mate with contacts on the chip package substrate54(which is cut away for purposes of illustration). The connectors66can also mate to connectors mounted on a surface of circuit board (such as is depicted inFIGS. 22-28). Heat sinks71may be attached to surfaces of the chips52as shown to dissipate heat, or integrated into the assembly by way of the encapsulant. It should be noted that further details of potential construction configurations are disclosed below with respect to the embodiment depicted inFIGS. 22-28.

The chips, substrate, heat sink and cable connectors66may integrated together by way of an encapsulant or other support structures that holds them together as a single assembly as shown inFIGS. 2-2C. This structure permits a device designer to fully utilize the space available on the motherboard62for additional components and circuit which add value to the host device without the need for complex circuit board designs. These integrated assemblies can be inserted into devices by merely inserting the first and second connectors into respective openings in the front and back walls374,57of the host device50. Ancillary connectors may be provided for connecting the chip package to other circuits of the device as shown inFIG. 3B. The assemblies may also be provided in other forms, such as, for example: 1) without the chip package, but with the chip package substrate; 2) with the chip package and either the first or second connectors, shown respectively at200and201inFIG. 2A; and, 3) with both the entry and exit connectors arranged to extend to openings in the front wall of the device, as shown at202inFIG. 2. In this manner the assemblies200,201and202may be inserted into a basic device to provide the device with its functionality without the need to design such functionality into the motherboard62of the hose device50. Additional details for possible construction will be discussed below.

Turning toFIGS. 4, 7&.8, an internal connector70is received within each of the connectors80and the internal connector70includes a body108formed of an insulative material that includes a card slot109that opens to the front of the connector70and to the entrance67of the connector80. The card slot109is an example of a mating interface and while the card slot configuration is preferable, other mating interface configurations are also suitable. The card slot109is positioned above a polarizing channel110formed by legs110a,110bthat support the card slot109off of the bottom wall68of the connector80and prevent incorrectly positioned opposing mating connectors from being inserted into the card slot109. The body108has a plurality of terminal-receiving cavities111aligned on opposite sides of the card slot109which receive contact portions of cantilevered terminals115a,115bof two connector elements104a,104b. The connector elements104a,104bsupport the terminals115a,115bin respective single rows of terminals as illustrated inFIGS. 4A and 8C. The two connector elements104a,104beach have wafer-like configurations and can be inserted into the body108from the rear to complete the internal connector assembly. As depicted, the terminal arrays of each connector element104a,104bare thereby positioned on opposite sides of the card slot109.

FIG. 8Aillustrates the basic construction of a connector element104that is used in the connectors70. A plurality of twin-ax cables60and regular wires121are arranged in an array extending widthwise of the connector70. The ends of the wires121and cables60are stripped to expose the signal conductors61of the cables60as well as define free ends121a,120aof the wires and cables, respectively, for terminating to corresponding tail portions116of the connector terminals115a,115b. (FIG. 4A.) In the embodiment illustrated, pairs of the twin-ax cables60are located at the outer ends of the array, and the drain wires61-2of the twin-ax cables120are bent simply upwardly and then bent again to lie flat on their associated ground plates125. The terminals115a,115bare held together in their own spaced apart widthwise array by a support bar124. This largely maintains the geometry of the cable in the connector termination.

The depicted receptacle connector70has a structure that promotes the signal integrity of data signals passing therethrough and which provides an impedance transition from the bypass cable wire pairs and the circuits of a circuit card of an opposing mating connector. This transition is from 85 to 100 ohms within a preselected tolerance level and is done in stages, or three zones so that the transition occurs in a gradual manner from an entry level impedance to a first transition impedance and then a second transition impedance and then finally to the final or third transition impedance. In this manner, the impedance transition occurs in a somewhat gradual manner over the entire length of the receptacle connector rather than occurring in the tail or the contact portions of that connector. In embodiments where no impedance transition is needed the transition can be omitted.

If a transition is provided it can provided by presenting three different dielectric mediums through which the receptacle connector terminals extend. The first zone medium is preferably a hot melt adhesive in which the impedance rises by about 6 ohms from the incoming impedance of about 85 ohms, and the second zone medium preferably includes LCP (liquid crystal polymer) where the impedance rises by about another 6 ohms, and finally the third zone medium includes air in which the impedance rises to about 105 ohms, thereby transition the impedance with a tolerance level of about 5%. The changes in surrounding medium are also accompanied by changes in the width of the terminals becoming wider or narrower in different zones. The distances between the terminals and associated ground planes can also contribute to this selected tuning of the impedance. The transition occurs over the length of the connector from the tails to the contact ends to present a gradual increase over a unit length rather than sole in either the tail or the contact portions of the terminals.

As depicted, the termination areas of the cables/wires120,121to the terminals115a,115bare disposed in a nest130, that extends widthwise and which is formed from an insulative material having a desired dielectric constant. (FIGS. 8A-8D.) The depicted nest130has a U-shaped configuration and it is located adjacent the terminal support bar124. In this area, the drain wires61-2of the cables60can be joined to ground plates125that are positioned above the cables60and are spaced vertically apart from and above the terminal tail portions116. The ground plates125have a plate body125awith at least a partially planar surface which the drain wires61-2contact and to which the drain wires may be soldered, or otherwise connected.

Contact legs126are provided as part of the ground plates125in order to form contact portions128of the ground plates125that are preferably attached to the tail portions116of ground terminals of the connector70. The contact legs126are vertically offset so that the ground plates125are spaced apart from and extend over at least a portion of the termination of the signal conductors to the signal terminal tail portions in the row of terminals associated with a corresponding connector element. As shown inFIGS. 8B-8D, each of the ground plates125preferably include three legs126which contact the ground terminals of the connector70in a manner such that any two signal terminal tail portions are flanked by two of the contact legs126. This arrangement permits the spacing of the signal terminals to approximately match that of the signal conductors of the twin-ax cables60from an impedance perspective. In this manner, a G-S-S-G pattern of the terminals115a,115bis maintained for the internal connector70within the two rows of terminals on opposite sides of the card slot109.

A rectangular frame132is provided along the rear of each connector element104a,104band includes four walls133(FIG. 8) joined together around a bottom wall134to at least partially define a hollow interior recess138. The front and rear walls133of the frame132are perforated as shown with openings135that are configured to accommodate the twin-ax cables120and the low power and logic control wires121in their longitudinal extent through the frame132. The frame132is joined to the nest130, along its rear face, by an overmolded portion that fills the termination area. The frame132can be formed of a conductive material, such as metal, or may have an outer conductive coating, so that when in place within the connector80, the connector elements104a,104bmake electrical grounding contact therewith. Thus, the frame can provide a path to ground or other reference plane. The connector element frames132are positioned adjacent to and rearward of the nest (FIG. 8C) and may be fixed to it as noted below.

The sidewalls133of the frame132may be slotted as shown with vertical slots136. These slots136will engage the sidewalk106a,106hof the rear opening106of the connector80and because the frames are conductive, they can also alleviate EMI leakage out of the rear opening106of the connector80. The open recess138of the connector element frame132through which the cables and wires extend is filled with a dielectric material, such as a liquid crystal polymer (“LCP”) that fixes the cables/wires in place in the recess138with respect to the connector element frames132and to the nest, which also receives some of the LCP. In this manner, the wafer-like configuration of the connector elements104a,104bis defined and this overall structure provides a measure of strain relief to the twin-ax cables60.

The bottoms134of the two connector elements104a,104babut each other and may engage each other through a post140and hole141manner of engagement as shown inFIG. 6. In this manner, the two connector elements104a,104hmay be inserted into a rear opening of the connector body108so that the terminal contact portions are aligned with each other and are received in the terminal-receiving cavities111of the connector body108to form an integrated connector assembly. As illustrated inFIG. 6, the connector assembly is pressed into the hollow interior space of the connector60from below. An internal ground plane142is provided in the form of a flat, conductive plate that is located between the two connecting elements104a,104b. It extends from the rear end of the connector element frame132to the forward edge of the nest130. This ground plane142acts as a primary ground plane that serves to block crosstalk between the signal conductor pairs in one connector element and the signal conductor pairs in another connector element. The ground plates125, act as secondary ground plates, or busses to the signal conductors of the cables120and their termination to the signal terminals115a.

The slots136on the sides of the connector elements104a,104bengage the sides106a,106bof the connector rear opening106, while two catches144disposed on opposite exterior sides of the connector body108are received in corresponding openings146in the sidewalls64a,64bof the connector80. The catches144may be oversized so as to deform when the connector assembly is inserted into place in the cage63. The slots136may be rounded in configuration with tips148pointing inwardly or at each other, in order to ensure reliable contact with the connector80. (FIG. 10.)

The two EMI absorbing pads102a,102bmay be applied to opposing surfaces of the connector elements104a,104bof the connector assembly prior to the connector assembly being pressed into the interior61of the connector80from the bottom. The connector elements are vertically slotted, as previously noted, so they can engage the sides106a,106bof the rear wall opening106of the connector and this contact provides in cooperation with the EMI-absorbing pads, four-sided EMI leakage protection around the connector elements. The rear wall of the connector80and the conductive connector elements104a,104bcombine to form, in effect, a fifth wall that prevents EMI leakage. The pads102a,102bseal off the spaces between the connector elements104a,104band opposing surfaces of the cage63. These pads102a,102boccupy the open spaces above and below the connector elements104a,104, which are normally empty in conventional connectors.

The EMI pads102a,102bare preferably aligned with and positioned above the areas of the connector elements where the cable wires are terminated to the terminal tails of the internal connector70. The bottom pad102bis held between the bottom wall68and the bottom connector element104b, while the top pad102ais held in place between the top connector element104aand the cage rear cover90. This is accomplished by ribs103that are formed on the bottom of the rear cover90which extend down into contact with the pad102a, as illustrated inFIG. 13B. The connector elements, EMI-absorbing pads are thereby sandwiched between the cage top and bottom walls66,68and the pads102a,102bhelp ensure that EMI leakage is reduced along the cage rear wall opening106.

With the twin-ax cables60directly terminated to the terminals of the connector70, the connectors80are configured for mounting off of a circuit board and onto a panel or in a manner so as to be a free-standing connector within a host device. The connectors80need not be mounted to a circuit board62in a termination manner, but can be by way of fasteners extending through openings in the circuit board and into the screw bosses. Thus, the beneficial sealing off of the bottom of the connector and elimination of the need for a right-angle connector not only eliminates the need to mount the connector on the motherboard62, but also facilitates stacking of the connectors in both vertical and horizontal arrangements.

Accordingly, the wires of the connector may be directly connected to components of the host device, such as a processor or a chip package and the like bypassing the traces on the circuit board. As the connection now may be direct, the connector does not have to be mounted on a circuit board but may be enclosed within a structure such as the connectors80disclosed and be panel mounted. The connectors80may be arranged on an adapter frame, which can be configured similar to a cage if desired. Still further, the connector may be used an as internal connecting sleeve to provide an internal connector that is positioned within the host device and which receives a plug-style connector. The connector cables are terminated to the connector element terminal tails at one ends of the cables so the cables can be terminated at their second ends to the chip packages or processors of the host device. An integrated bypass assembly such as this can be installed and removed or replaced as a unit, which bypasses the circuit board and the associated loss problems which occur in FR4 materials, thereby simplifying the design and reducing the cost of the circuit board.

Turning now toFIGS. 4-9, a connector80is illustrated inFIGS. 5 and 5Athat can be used as an external interface that accommodates entry connectors of the host device. The connector80is disposed in the first wall374of the device50and receives opposing mating connectors in the form of plug connectors, such as pluggable electronic modules and the like. The connector80includes a cage63that is conductive and includes two sidewalls64a,64b, a rear wall65and top and bottom walls66and68. All of the walls cooperatively define a hollow interior61that receives a corresponding opposing external mating connector that mates with an internal connector70so as to define a port. The walls of the connector80may be formed together as one piece as in an adapter frame, or they may be utilize separate elements that are joined together to form an integrated assembly. It should be noted that the connector80is not limited in its operation to accommodating only pluggable modules but can, with the appropriate configuration, accommodate any suitable connector.

The cage walls64-66&68are all conductive and provide shielding for connections made within the connector80. In this regard, the connector80is provided with a conductive bottom wall68that completely seals off the bottom of the cage63in contrast to known cages and frames that are open at their bottoms to the circuit board upon which they are mounted. The depicted connector80contains an internal, cable-direct connector70(FIG. 4) that has direct wire connections made to its terminals115a,115band therefore does not require termination to traces on the motherboard62of the host device50. Prior art connectors enclosed by cages or frames are of the right angle type, meaning the connector extends at a right angle from its mating face to the circuit board and the traces to which the connector is terminated. Right angle connector terminations to circuit boards can create signal integrity problems in high speed operation, due to the varying lengths of the terminals and the bending thereof, such as increased capacitance in the corners of the bends and jumps or dips in the characteristic impedance of the system at the connector and its interface with the circuit board. In addition, the exiting of the cables out of the rear of the cage can potentially eliminate the need to use press-fit pins as a means to mount the connector to the circuit board, as ordinary mounting holes can be used for threaded fasteners, thereby simplifying the overall design of a host device motherboard. As depicted, the internal connectors70are terminated to wires of cables60and exit out of the rear wall65of the connector80, thereby avoiding the aforementioned problems.

The bottom wall68of the cage, as shown inFIGS. 5-6B, seals off the bottom of the connector80. The bottom wall68is shown as formed from a piece of sheet metal with a bottom plate72, and side attachment flaps73that extend along the outer surfaces of the cage sidewalls64a,64b. Openings74in the attachment flaps73engage catches, or tabs76which are located on the sidewalls64a,64band retain the bottom plate72in place. Additional means of attachment may include inner flaps75that are also bent up from the bottom plate68but are positioned along the edges of the bottom plate68to extend into the interior hollow space61along the inner surfaces of the sidewalls64a,64b. Two such inner flaps75are illustrated inFIGS. 1I & 13Aand include contact tabs75athat extend inwardly for contacting opposite sides of an opposing connector inserted into the interior channel61. Two rims, or flanges77a,77b, may also be provided at opposite ends of the bottom plate68which extend at an angle thereto in order to engage the front and back wall65of the cage63to make conductive contact and provide EMI shielding at those locations. The use of a bottom wall68that covers the entire bottom significantly reduces EMI in this area. Standoffs69may be formed in the bottom wall68if desired. The many points of contact between the bottom wall68and the cage63provide a reliable EMI shielding gasket along the entire bottom of the connector80for the internal connector70.

Turning now toFIG. 5, the top wall66preferably includes an access opening81which communicates with the hollow interior61and which is aligned with the internal connector70and primarily the area in front of the internal connector70. A heat transfer member82shown as a finned heat sink may be provided which has a base84that extends at least partially into the access opening81. The base84has a flat bottom contact surface85that contacts an opposing surface of a module inserted into the cage interior61. Two retainers86are shown as joined to the top wall66and each retainer86has a pair of preloaded contact arms88that exert a downward retention force on a top plate87of the heat sink. An EMI gasket89is provided that extends around the periphery of the opening81and is interposed between the top wall66and the heat transfer member82.

The connector80further includes a rear cover portion90that extends over a rear portion of the interior61to cover part of the internal connector70. A recess91may be formed in the rear cover90to accommodate a chevron-shaped EMI gasket92interposed between opposing surfaces of the rear cover90and the top wall66. The rear cover90can be seen to include an opening in the form of a slot94. The top wall66(FIG. 13A) may include an engagement hook95as shown that is received within the slot94to engage the top wall66to the cage63in a manner such that the top wall66can be slid forward so that its leading edge abuts the front flange of the connector80, which may include a projecting tab96formed therewith which engages a corresponding slot97of the top wall66. (FIGS. 5A & 13A.) Fastener99, which may be a screw or other fasteners, may be used to secure the top wall66onto the cage63by engaging threaded holes formed in screw bosses100supported by the cage63. In this manner, the cage63is sealed in a manner to significant reduce EMI leakage.

Because the internal connectors70are connected directly to the cables60, the connectors80need not be mounted to the motherboard62by direct termination, but can be supported by other structures or can be attached by way of fasteners120that extend through openings122in the circuit board and into the screw bosses100. Sealing off of the bottom of the connector80and elimination of a right-angle connector not only eliminates the need to mount the connector80on the motherboard62but also facilitates stacking of the cages/connectors80in vertical and horizontal arrangements.FIGS. 15 & 16illustrate just two different styles of stacking.FIGS. 15 & 15Aillustrate a pair of connectors80with their entrances67oriented horizontally in a vertical stack. The two connectors80are shown supported on a circuit board62by way of bottom screws120that engage the screw bosses100in an upward manner through openings in the circuit board. A set of middle screws124are provided to engage the screw bosses100of the lower cage and these screws124have threaded male ends and threaded female ends126. The female ends126engage top screws99,128extending into the screw bosses100of the top cage. Thus, multiple connectors80may be stacked in such a fashion without requiring complex high speed connecting traces formed in the circuit board62and terminated to the internal connectors70.

FIGS. 16-16Aillustrate another manner in which the connectors80may be arranged. This arrangement includes a horizontal row of three cages that are aligned vertically along a front of the host device, but raised off of the circuit board62.FIG. 15Billustrates a mounting nest130that has a base132and two extending sidewalls133that form a recess which accommodates a connector80. The mounting nest130has two attachment flanges134that can be attached to a faceplate136with fasteners as shown extending through openings135in the base132. Fasteners may be used to attach the cages to the nest, and they extend through the base openings135into the screw bosses100. The top wall66of the connector80may be attached to the cage63with male-female ended fasteners126as noted above so that adjacent connectors80may be assembled into an integrated arrangement with male fasteners extending through the bases132of the nests130into the female ends126of opposing fasteners or into the screw bosses100of the cage. The connectors80may also be spaced closely together in instances as shown inFIGS. 14-15Bas the heat transfer member82has its heat dissipating fins extending rearwardly of the cage as set forth to follow.

Accordingly, a free-standing connector/cage is provided that can be attached to an external wall of a host device, such as a faceplate or bezel or to a circuit board without requiting any termination traces positioned underneath the cage. Such a free-standing connector does not have to be mounted on a circuit board, but may be panel mounted. The connector may take the form of an adapter frame, a shielding cage or similar type of cage. Still further, the connector may be used an as internal connecting sleeve to provide an internal connector that is positioned within the host device and which receives a plug-style connector. The connector cables are terminated to the connector element terminal tails at the proximal ends of the cables, and the cables can be terminated at their distal ends to the chip packages or processors of the host device. An integrated bypass assembly such as this can be installed and removed or replaced as a unit, which bypasses the circuit board and the associated loss problems which occur in FR4 materials, thereby simplifying the design and reducing the cost of the circuit board.

The mating connectors used to connect to the I/O connectors generate heat during operation, and this heat must be removed in order to maintain efficient transmitting and reception of signals during operation. High temperatures can negatively affect the performance of not only the modules, but also the devices in which they are used, so it is important to remove this operational heat. Such removal is typically accomplished by the use of heat sinks which include solid bases that make contact with selected surfaces of the modules, typically the top surfaces. These heat sinks further have plurality of heat-dissipating fins that project upwardly from the bases into the interior space of the device. The fins are spaced apart from each other so that air can flow over and around the fins in a manner that heat is dissipated from the fins into the surrounding interior atmosphere. The fins are mounted above the heat sinks and modules and extend upwardly for a specific height in order to achieve a desired degree of thermal exchange. However, the use of such heat sinks does not permit a designer to reduce the height of the devices in which modules are used, eliminating the possibility of reducing the overall heights of such devices.

In this regard, as shown inFIGS. 17-19G, a heat sink assembly240is provided that includes a heat transfer portion241which has a solid base242that depends downwardly into the interior space226of the cage/connector222. The heat transfer portion base242is complimentary in shape to the opening232in the cage222so that the base portion242may extend through the opening232and into the interior space226so as to make thermal contact with the top or upper surface of a module inserted into the front opening230of the interior bay229of the cage222. The base242may further include a skirt or lip portion244that extends around at least a substantial portion of the periphery of the base242, and preferably around the entire periphery of the base242. This skirt244is received in a corresponding recess246formed in the top surface233of the cage222and which preferably surrounds the opening232. A conductive EMI ring gasket247is provided that fits in the recess246and which encircles the opening232. The gasket247has a plurality of spring fingers248that provides a conductive seal between the heat transfer portion skirt244and the cage top recess246so as to prevent EMI leakage through the opening232. The EMI gasket247sits within the recess246and surrounds the opening232with the spring fingers248extending radially outwardly, as shown and into contact with the bottom surface of the skirt244. The opening232in the top of the cage222is considered as a contact opening as it permits the heat transfer portion241to extend into the interior space226of the cage222and into thermal transfer contact with any module inserted therein by way of a thermal contact surface250. (FIG. 19C.)

The heat transfer portion241has a solid base portion242that preferably includes a planar thermal contact surface250(on its bottom) that is configured to enter the frame contact opening and contact the top surface of a module inserted into the bay229in effective and reliable thermal contact. The base242may include an angled lead-in portion on its contact surface250to facilitate the insertion of a module. The heat sink assembly240further includes a distinct heat dissipating portion252that dissipates heat generated by the module and transferred to the heat transfer portion241by way of contact between the thermal contact surface250and an opposing top surface(s) of the module. As shown inFIG. 18, this heat dissipating portion252is distinct from the heat transfer portion241and is spaced apart therefrom in a longitudinal or horizontal direction.

The heat dissipating portion252includes a base254that extends out in a cantilevered fashion from the heat transfer portion241along a similar longitudinal axis. A plurality of vertical heat-dissipating fins256are disposed on the base254and extend vertically downwardly from the heat dissipating portion base254. As illustrated, the fins256are spaced apart from each other in the longitudinal (horizontal) direction to define a plurality of cooling passages258therebetween that are spaced away lengthwise from the heat transfer portion241and which further extend lengthwise with respect to the modules. In order to retain the heat transfer portion241in contact with a corresponding module, and also resist any moment that may occur due to the weight and/or length of the heat dissipating portion252, retainers260are illustrated. These retainers260are attached to the frame top surface233by means of fasteners, such as rivets262, which may be formed as part of the cage222in the nature of vertical posts263that are received within corresponding openings264disposed in the retainer base portion265. The free ends of these posts263may be “dead-headed” or “mushroomed” to form the connection between the retainers260and the skirt244. The retainers260are seen to have pairs of cantilevered spring arms267associated with them and which extend longitudinally from the base portions265as illustrated. The spring arms267are flexible and are formed as elastic spring arms267with a preformed downward bias. The spring arms267terminate in free ends268and they extend at a downward angle into contact with the heat transfer member skirt244. Four such contact points are provided for the heat sink240assembly illustrated in the Figures, and the contact points will define a four-sided figure when connected by imaginary lines. However, the contact points of the spring arms267may vary from the locations shown according to the extent to which space is available on the skirt portion244of the heat sink member240.

The elasticity of the spring arms267permits a designer to obtain a desired contact pressure by configuring the length of the spring arm267, the depth to which the spring arm267depends down into the recess246and the height of the stub269that joins the spring arm267to the retainer260. The fastener connection of the retainer260to the skirt plate244eliminates forming and utilizing attachments on the sides of the cage222which would take up space and affect spacing between cage222. The rivets262also have a low profile so that the frame226is not unduly enlarged in any direction, including the vertical direction. The spring arms267are relatively short in length and therefore contact the heat transfer portion241at approximately four corners thereof to exert a reliable contact pressure on it in order to maintain it in good thermal transfer contact with any modules.

Uniquely, the heat-dissipating fins256are removed from immediate contact with the heat transfer portion241of the heat sink assembly240. Rather, they are positioned on the heat dissipating portion252and they extend downwardly therefrom. The fins256are longitudinally spaced away from the heat transfer portion41and its base242. The fins256are further arranged in a series of planes, shown as vertical planes F, that intersect both the horizontal plane, H1, in which the heat transfer portion skirt extends and the horizontal plane H2in which the thermal contact surface(s)250extend. As shown inFIG. 19C, not only do the vertical planes F intersect the two planes H1and H2, but the fins themselves extend for heights that intersect those two planes. Furthermore, adjacent fins256are separated by intervening cooling passages or air channels through which air may circulate. The fins256and cooling passages258extend transversely to a longitudinal axis of the heat sink assembly240. In this manner, the fins256may occupy the space R rearwardly of the cage222and above the wires272which are terminated to the receptacle connector271supported in the cage222. Locating the fins256in this manner permits the overall height of the device in which the cage strictures are used to be reduced by approximately the height of the fins that ordinarily would project upwardly from the cage. It is desired to have the fins256not touch the wires272in this orientation. In this regard, the height of the fins256is preferably less that the height of the cage222as illustrated in the Figures.

The heat transfer and heat dissipating portions241,252are shown as being integrally formed as one piece to promote heat transfer from the transfer portion241to the dissipating portion252. However, it is contemplated that the two portions241,252could be formed separately and subsequently joined together where desirable. In order to further enhance the transfer of heat from the heat transfer portion241, a thermal transfer member274is provided that extends lengthwise along and in contact with the heat transfer and heat dissipating portions241,252. Such a transfer member274is shown in the Figures as a heat pipe275, having an oblong, or elliptical, cross-sectional configuration which include major and minor axes that define such a shape. (FIG. 19D.) The oblong configuration of the heat pipe275increases the amount of contact area between the heat pipe275and the two portions241,252of the heat sink assembly240. Other non-circular configurations such as a rectangular inner cavity may be utilized or even cylindrical ones. The heat pipe275is received within a common channel278that also extends longitudinally along the heat sink assembly240and it follows the contour of the two portion241,252. Accordingly, the heat pipe275has an offset configuration with two distinct portions279,280that extend at the different heights, or elevations, of the heat sink assembly240.

The heat pipe275is a hollow member with an inner cavity282defined by sidewalls283that is sealed at its ends and which contains a two-phase (e.g., vaporizable) fluid within its inner cavity282. Examples of a two-phase fluid that can reside within embodiments of inner cavity282include purified water, freon, etc. The heat pipe275and its walls283can be composed of aluminum, copper or other thermally conductive materials. The inner cavity282preferably includes an evaporator region279located adjacent the heat transfer portion241and a condenser region280located adjacent the heat-dissipating portion252. Heat is transmitted from the heat transfer portion241through bottom and side walls283of the heat pipe275into the inner cavity282where is can cause the two-phase fluid present in the evaporator region279to evaporate. This vapor can then be condensed to liquid in the condenser region280. In the illustrated embodiment, the vapor gives up heat as it condenses, and that heat is transmitted out of the inner cavity282through the walls283of the heat pipe275into the base of the heat dissipating portion252and its associated fins256. The inner cavity282may include a wick284to facilitate travel of the condensed liquid along the wick back to the evaporator region280. (FIG. 19D.) The wick284may take the form of grooved channels on the interior surface of the inner cavity282, or an extent of wire mesh or the like.

As illustrated, the heat transfer and heat dissipating portions241,252of the heat sink assembly240extend longitudinally but extend at different elevations, with the heat dissipating portion252being raised with respect to the heat transfer portion241. This difference in elevation facilitates, to some extent, the movement of the liquid vapor from the heat transfer portion241up into the heat dissipating portion252, but its primary purpose is to accommodate the heat dissipating portion252in its horizontal extent without having to modify the frame222to accommodate it. If one desired to extend the heat dissipating portion252at the same elevation as the heat transfer portion241, the rear wall224and a portion of the top surface233, proximate thereto would need to be modified. A channel, or recess, may be formed in those two walls224,233to accommodate the area of the heat sink assembly40between the heat transfer and dissipating portions241,252. Also, although mostly one heat pipe275has been discussed, it is understood that multiple heat pipes, such as a pair of heat pipes290, as illustrated in phantom inFIG. 19Emay be routed in the heat sink assembly channel. In this instance, the pair of pipes may be encapsulated in a medium that facilitates heat transfer to make up for the amount of direct contact lost between a pair of heat pipes and a single, oblong configured heat pipe as illustrated. Thermally conductive greases or other compounds may be applied to the heat pipes to enhance the thermal transfer.

This heat sink assembly thermally engages the cage and uniquely transfers heat therefrom to an area rearwardly of the cage. With this structure and its downwardly depending heat dissipating fins, the devices in which such heat sink assemblies are used can have a reduced height, permitting additional devices in closets and stacks. The location of heat dissipating tins is such that all of the spaces between the fins are used for cooling as none of them have light pipes or any other members extending therethrough. The heat sink heat-dissipating portion extend horizontally but spaced above the motherboard of the device so a designer can utilize this open space for additional functional components without increasing the lateral size and depth of the host device. Examples of the manner in which the connectors with the heat sinks integrated therewith can be arranged and mounted for use in a host device are illustrated inFIGS. 15-16A.

As noted above, the cage of the connector80can be formed in a manner that allows for positioning the connector80in manner where the connector80is not supported by a circuit board and instead can be supported by other structures (such as conductive or insulative frames). In such a configuration, all the terminals are preferably connected to conductors in a cable so that signals (high speed and low speed) can be directed appropriately. In many such embodiments, the cage of the connector may be formed using a die cast material. Such a construction is not required as convention stamped metal construction will also be suitable.

While a cage can be supported by a separate structure such as a frame, it should be noted that the connector can be mounted to a circuit board in a more conventional manner. For example, connector80′ inFIG. 20is formed of stamped material and is configured to be press fit into a circuit board and provides multiple ports80a′ in a ganged configuration. The cage63′ includes dividing walls63a′ that help define the ports and the cage63′ includes tails63b′ that are configured to be pressed into a circuit board. For certain system configurations where extending a circuit board to an edge of the box is desired, it may be beneficial to have the connector80′ configured so that it can be mounted on the circuit board in a press-fit fashion as shown. In such a configuration, the high speed signal terminals are expected to be connector to cables but the low speed signals can be mounted to cables or connected to the circuit board in a desirable manner (for example, a connector such as is depicted in PCT Application No. PCT/US2014/054100, which is incorporated herein by reference in its entirety).

FIG. 21illustrates an embodiment of a computing device300. The device300includes a chassis301with a first wall305aand a second wall305b. As depicted, the first wall305ain a front wall and the second wall305bis a rear wall (thus the first and second walls305a,305bare opposing) but the first and second walls305a,305bdo not need to be on opposing sides and thus a number of configurations are possible.

The chassis301supports a main circuit board312that extends to adjacent the front wall305a. A chip package340is provided on the circuit board312and first connectors321are connected to the chip package340by cables322that carry the high speed signals. A second connector331is positioned at the second wall305band is connected to the chip package340by cables332. Power is provided to the circuit board312(and the various components supported thereby) via power connection330. It should be noted that the distance between the first and second walls305a,305bcan exceed 20 inches and thus would be problematic if the circuit boards were to be used to transmit the high speed signals, especially as the data rate approaches and exceeds 25 Gbps. Using non-return to zero (NRZ) encoding would require a signaling frequency of about 12.5 GHz and such frequencies are poorly compatible with conventional FR4 based circuit boards. In addition, as data rates approach 40 Gbps (and the signaling approaches 20 GHz) even the use of exotic materials would likely be insufficient to allow for convention circuit board techniques to be used.

FIGS. 22-27illustrate another embodiment of a computing device. Specifically, computing device400includes a chassis401with a first wall405aand a second wall405b. A main circuit board406is provided and the main circuit board includes component circuitry407. Component circuitry407can include power supplies, cooling fans and various digital signaling chips that either do not need to operate at high frequencies in order to support desired bandwidth or are intended to travel short distances. A support connection408(which is shown as a cable assembly for ease of assembly but could also be a two board connectors) can provide control signals and/or power signals to a signal board410that supports one or more chip packages440.

First connectors421are positioned along the first wall405aso as to provide ports421ain the first wall405a. Similarly, second connectors431are positioned along the second wall405bso as to define an appropriate mating interface along the second wall405b. As can be appreciated, however, the signal board410does not extend to first or second connectors. Instead, the first connectors421are coupled to the chip package440via cables422while the second connectors431are coupled to the chip package440via cables432. The first connectors421can be formed in a manner similar to that which was discussed above and thus the internal details of connector421will not be repeated here for purposes of brevity. Instead it will just be noted that the above features of such a connector can be used herein in a desired manner and in a desired combination so as to provide a connector that meets the system requirements.

As can be appreciated, the first connectors421could be supported by a front circuit board411. Alternatively, the front circuit board could be omitted and a frame such as frame132(discussed above) could be used to support the first connectors421. If the front circuit board411is used then connector supports411acan be used to secure the first connector421to the front circuit board411.

The signal board410supports the chip package440, which includes a chip445, and arranged around the chip package440are a plurality of signal board connectors426. Traces, as discussed above, can connect the chip445to the signal board connector(s)426and, as discussed above, an optional substrate can act as a connection between the chip445and the signal board410. In an embodiment, such as is depicted inFIG. 27, the signal board connectors426can be positioned on at least two sides of the chip445and potentially can be positioned on four sides so as to increase system capacity. If desired, at least two signal board connectors426can be provided on each side of the chip445. Naturally, further increases in density can be provided if the signal board410(or corresponding structure if a signal board is not used) has a chip on both sides (e.g., on top and bottom).

In operation it is expected that the signal board410will be prepared (which may include passing through a solder reflow operation) and then be mated to the first connector421. To allow for such an installation process, the cable422has a first end422aterminated to the first connector421and a second end422bis terminated to first board connectors423and first board connectors423are mateable with the signal board connectors426. Likewise, cable432can have a first end432aterminated to the second connector431and a second end432bterminated to the second board connectors433. Such a configuration allows the signal board410to be mounted in the chassis401before being connected to the first connectors421and second connectors433. In operation, it is expected that signal board connector426will include a housing426athat supports a plurality of terminals429that are soldered to the signal board410. Of course, in alternative embodiments a signal board connector could be press-fit onto the signal circuit board410. As the use of solder or press-fit to mount a connector on a circuit board is well known, no further discussion of such connector details will be provided herein.

Regardless of how the signal board connector426is mounted on the signal connector board410, it provides a mateable interface to the signal connector board410. The signal connector board supports a chip445(which typically will be on a carrier or substrate of some nature). The chip445can be connected to the signal circuit board410as discussed above and can be supported by a thermal frame442that supports a cooling block441. The cooling block441, which can be in the form of a conventional heat sink, includes a cooling base441athat will preferably be compressed against the chip445and may include cooling fins441bto increase surface area and improve cooling of the chip. As can be appreciated, a thermal transfer compound443will thermally couple the chip445to the cooling base441a.

The chip445, which as discussed above can be an ASIC, DSP and/or any desired combination of controllers and processors, thus is connected to the first connector421and the second connector431via only a very short path through a signal circuit board410. As signal loss is related to the distance traveled along the board, shortening the distance as depicted allows for much lower loss than convention systems while allowing for the use of conventional circuit board materials and constructions methods.

FIGS. 28A and 28Billustrate an alternative embodiment of a signal board connector and first board connector. Specifically, a first board connector523includes a housing523athat supports one or more rows of cables522. The housing523aof the first board connector523mates with a signal board connector526that includes a housing527ain a cage527bthat has legs527cthat, in operation, help secure the cage527bto the corresponding signal circuit board. A biasing member528asecures the first board connector523in the signal board connector526and includes an actuation member528bthat, when actuated, allows the first board connector523to be removed from the signal board connector526.

Naturally, other configurations of the first board connector and signal board connector are possible and thus the depicted embodiments are not intended to be limiting unless otherwise noted. In addition, the first board connector and the second board connector may be the same or can be different so as to ensure that the proper connectors cannot be mounted in the wrong location. To further protect from potential installation problems, each of the first board connectors and second board connectors can be keyed differently so that only the desired configuration can be installed.

FIG. 29illustrates an alternative embodiment of a chip package640. A support layer614is provided that supports a flex layer690, that in turn is supporting a substrate646and the substrate646supports a chip645. The chip645and substrate646can be as described above. The support layer614could be a circuit board or some other material. While the support layer614is shown as being relatively comparable in size to the chip645and the substrate646, in practice it is expected that the support layer will be larger than the chip646and the substrate646so as to provide additional support. As can be appreciated, rather than use a circuit board to couple the chip to a connector, the depicted embodiment uses a flex circuit to couple connectors626to the chip645. The entire chip package640can be supported by a frame (not shown) or by the support layer614, depending on the desired configuration and can include heat sinks to help dissipate heat away from the chip. In such a system the support layer614could provide a mounting point for the heat sink similar to that discussed above.

Flex circuits can be made with an intricate pattern as they can be multiple layers thick and the flex circuit690can terminate to multiple signal board connectors626(which would be configured to be connected to corresponding first board connectors so that the rest of the system was substantially the same). Thus, solder connections between the flex circuit690and the substrate646or chip645are possible. And, as can be appreciated, a flex circuit can provide high performance, relative to a circuit board. It should be noted that while the substrate646is depicted as a separate component, in an embodiment the flex circuit690could replace the substrate646and thus the use of the substrate646is optional in the chip package640. As can be appreciated, therefore, a signal board connector can but does not have to be mounted on a circuit board.

It should also be noted that the flex circuit, which often is formed with KAPTON but can also be a rigid-flex circuit, can be formed with polyimide, acrylic adhesive, epoxy adhesive and fluoropolymer adhesive solutions. Thus the choice of material is not intended to be limiting as the design of the system allows even relatively lossy materials like FR4 to be used effectively.

Specifically, the path lengths of traces in the signal board (if a signal board is used) are kept short such that for frequencies around 15 GHz (which is slightly above to what is needed to support 25 Gbps using NRZ encoding and 50 Gbps using PAW encoding) it is expected that less than 2 dB (preferably less than 1 dB) of insertion loss due to the circuit board can be provided between the chip and the signal board connector. This is because even less expensive circuit board materials can provide less than 1 dB of loss per inch of travel at that frequency and the system design allows the traces to have a relatively short path length (often less than two inches long) between the chip and the signal board connector. Higher performance circuit board materials can provide loss in the range of about 0.5 dB per inch. Thus it is feasible to have less than 1 dB of loss between the chip and the signal board connector. Naturally, as the operation frequency increase and approaches 25 GHz the depicted configurations that allow for reducing insertion loss become even more important. Applicants have determined that even for 25 GHz signaling operation the depicted system can still provide relatively low insertion loss (less than 2 dB of insertion loss in the circuit board for well-designed systems) and thus the depicted configurations may be highly desirable for high performance applications. In addition, for more sensitive applications a conventional circuit board can be omitted and the chip can be connected to a flex circuit that is terminated to the signal board connector so as to potentially provide less insertion loss than is typically found with circuit boards.

The disclosure provided herein describes features in terms of preferred and exemplary embodiments thereof. Numerous other embodiments, modifications and variations within the scope and spirit of the appended claims will occur to persons of ordinary skill in the art from a review of this disclosure.