Optical backplane connector system

Abstract

A backplane connector for mating with a daughter card connector assembly, the backplane connector having a forward orientation and a rearward orientation and comprising: (a) a retainer block configured for attachment to a backplane and defining a plurality of ferrule slots, each slot configured to receive a ferrule; (b) a plurality of ferrules disposed in the ferrule grooves; (c) a plurality of ferrule springs for pushing the plurality of ferrules forward; and (d) a plurality of ferrule spring retainers for retaining the ferrule springs and mounted rearward on the retainer block, wherein each ferrule spring retainer retains a spring for two or more ferrules.

Description

TECHNICAL FIELD

[0001] The present invention relates generally to printed circuit board (PCB) based backplane connector assemblies, and more particularly to PCB based backplane connector systems having blind mate optical interfaces. BACKGROUND

[0002] Printed circuit board (PCB) based backplane connectors are well known. For example, the MULTIGIG RT interconnect family from TE Connectivity (TE) is used in a variety of computer, communications, medical, industrial control, and military applications. These connector systems use printed circuit board (PCB) cards or “wafers” in place of traditional pin and socket contact systems, thereby eliminating the open pin field area on the plug-in module portion of the backplane connector and reducing the risk of end users being exposed to field failures in the card cage system. A typical PCB backplane subcard connector assembly includes a housing defining a plurality of slots, with each slot configured to receive a separate PCB wafer.

[0003] Applicant recognized that PCB wafers could be improved by adding functionality to the wafers that converts between electrical signals and optical signals. To this end, Applicant disclosed a high density optical subcard connector assembly, such as described in U.S. Patent No. 10,852,489. This optical subcard connector assembly met many needs, particularly with respect to its configurable free end optical fibers. However, Applicant recognized that there was a further need for a blind mate optical subcard connector assembly. The present invention meets these needs, among others. SUMMARY

[0004] The solution is provided by a backplane connector for mating with a subcard connector assembly, the backplane connector having a forward and a rearward direction and comprising: (a) a retainer block configured to attach to a backplane and defining a plurality of ferrule slots, each slot configured to receive a ferrule; (b) a plurality of ferrules disposed in the ferrule slots; (c) a plurality of ferrule springs for urging the plurality of ferrules forward; and (d) a plurality of ferrule spring retainers for retaining the ferrule springs and mounting rearward on the retainer block, wherein each ferrule spring retainer retains springs for two or more ferrules. BRIEF DESCRIPTION OF DRAWINGS

[0005] The invention will now be described by way of example with reference to the accompanying drawings in which:

[0006] Figure 1 A perspective view of one embodiment of a subcard connector assembly of the present invention is shown.

[0007] Figure 2A A perspective view of a subcard connector assembly of Figure 1 is shown, wherein optical fibers connect the optical connectors with the optical components, and Figure 2Ba close-up view of a portion of Figure 2A

[0008] Figure 3 shows an exploded view of one embodiment of the backplane connector of the present invention.

[0009] Figure 4A and Figure 4B shows front and rear perspective views, respectively, of the backplane connector of Figure 3

[0010] Figure 5 shows a front view of the backplane connector of Figure 3

[0011] Figure 6 shows a front view of the connector assembly of Figure 1

[0012] Figure 7 shows a rear perspective view of the backplane connector of Figure 1 Figure 3

[0013] Figure 8 shows a front perspective view of the backplane connector of Figure 1 Figure 3

[0014] Figure 9 shows a cross-sectional view of the coupled connectors of Figure 7

[0015] Figures 10A-10D shows a perspective view of an alternative embodiment of the daughter card connector assembly having a heat sink to draw heat away from the die. DETAILED DESCRIPTION

[0016] Reference is made to Figures 1-2A ​​​​​​​​​FIG. 2B illustrates one embodiment of a daughter card connector assembly 100. The daughter card connector assembly 100 includes a housing 101 defining a first plane 101a configured to be mounted parallel to a backplane, a second plane 101b for mounting parallel to a daughter card (not shown), and a plurality of parallel slots 102 perpendicular to the first plane. The daughter card connector assembly 100 also includes one or more optoelectronic cards 103. Each of the one or more optoelectronic cards is disposed in one of the plurality of slots and includes at least a printed circuit board (PCB) 104 having at least a first edge 105 and a second edge 106. When the optoelectronic card is mounted in the slot, the first edge is parallel to the first plane and the second edge is parallel to the second plane. A blind mate optical connector (or ferrule) 107 is disposed along the first edge and an electrical interface is disposed along the second edge (in the figure, the electrical interface is obscured by the housing 101). At least one optical component 110 is mounted on the PCB for converting between electrical and optical signals, the PCB being electrically connected to at least a portion of the electrical interface. In this particular embodiment, the optical component 110 includes an optoelectronic device 110a and a driver circuit 110b. One or more waveguides 111 connect the optical component with the optical connector. In this embodiment, the waveguides are optical fibers 112.

[0017] Each of these elements / features is described in detail below in connection with selected alternative embodiments.

[0018] In one embodiment, the daughter card connector assembly includes discrete / modular optoelectronic cards 104. In one embodiment, each discrete optoelectronic card is releasably engaged with the housing 101. In one embodiment, the housing 101 includes a plurality of slots 102 and each optoelectronic card 104 is slidably engaged with one of the slots. Generally, each optoelectronic card includes one or more optical components for transmitting / receiving electrical / optical signals, although it should be appreciated that the optoelectronic card can be a dedicated optical receiver or a dedicated optical transmitter. In this regard, the modular configuration of the optoelectronic cards allows a given daughter card connector assembly to be configured in different ways. For example, depending on the application, the daughter card connector assembly can include a portion of optoelectronic cards configured for transceiving, and another portion of optoelectronic cards dedicated to receiving and / or transmitting.

[0019] Not only does the modularity of the optocar provide flexibility in configuring the subcard connector assembly with transceiver / transmit / receive optocars, but it also provides scalability. That is, in one embodiment, the subcard connector assembly of the present application can be scaled to meet the needs of an application rather than purchasing and installing a subcard connector assembly with all of its lanes. For example, initially, a backplane connector housing with relatively few optocars can be installed, and subsequently, as the need for additional lanes grows, additional optocars can be added to the housing. Thus, in one embodiment, the subcard connector assembly of the present application provides a pay-as-you-grow solution.

[0020] Another benefit of the modular configuration of the optocar is the ability to replace a defective optocar or periodically upgrade the optocars without having to replace the entire subcard connector assembly. In other words, unlike conventional transceivers in which, if one or more lanes become inoperable, the entire transceiver must be replaced, in one embodiment of the backplane connector assembly, only the inoperable or outdated optocar need be replaced. Thus, the modular construction of the optocar eliminates single point of failure of the entire subcard connector assembly. Moreover, the discrete optocar solution of the present application enables configurable ratios of lane protection. More specifically, the scalable configuration of the present application enables a user to precisely configure the desired level of lane protection, e.g., from 1 : 1 redundancy to 1 : N redundancy, rather than having to provide a full single redundant multi-lane transceiver (e.g., a 12 lane device) at a higher initial and replacement cost.

[0021] One important feature of the subcard connector assembly is the blind mate optical connector 107 on the first edge 105 of the optocar 103. Such a connector facilitates blind mating of the connector with the backplane. As shown, the optical connector is an MT type optical connector with alignment pins / alignment pin holes 150 at its end and a fiber end face 151 presented in the center. In this particular embodiment, the distance between the alignment pin holes is relatively large compared to the relatively few fibers present in the ferrule center. This configuration is generally preferred (although not required) because the longer distance between the fiber end face and the alignment pin holes tends to improve the alignment of the fiber end face with the fiber end face of the mating connector 106 on the backplane. Although MT type connectors are shown in the embodiments of Figure 1 While MT type connectors are shown in the embodiments of Figs. 1 and 2, other embodiments are possible within the scope of the present application. For example, essentially any blind mate optical connector can be used so long as it has a thin profile to accommodate the relatively small spacing between the slots of the subcard connector assembly 100. For example, in one embodiment, the spacing is less than 2 mm, and in another embodiment, the spacing is less than 1.8 mm, and in another embodiment, the spacing is less than 1.5 mm.

[0022] As Figure 1 andFigure 2A 、 2B As shown, one or more waveguides 111 connect the insert 110a to the blind mate optical connector 107. In one embodiment, the waveguides are optical fibers 112 as shown in Figure 1 and Figure 2A 、 2B In yet another embodiment, the waveguides can be defined in the PCB such that the optical connector 107 is optically coupled to the PCB.

[0023] In one embodiment, the first edge of the card 104 also includes an electrical interface 130 for connecting to a mating connector on a backplane. In one embodiment, the electrical interface on the first edge is a blind mate electrical connector.

[0024] In one embodiment, the electrical interface on the second edge of the card is similar to the electrical interface disclosed in U.S. Patent No. 9,196,985, which is incorporated by reference herein. Also, in one embodiment, the second plane of the housing has a daughter card interface similar to the daughter card interface defined in the '985 patent. Specifically, in one embodiment, the daughter card interface includes a pinhole connector 120 along the second plane. (Such connectors are well known and will not be described in detail here.)

[0025] In one embodiment, the optical component 110 includes an insert 110a and a chip 110b. The insert 110a includes an innovative insert that minimizes skew and simplifies optical alignment. For example, one embodiment of the inventive insert is disclosed in U.S. Patent Application No. 16 / 450,189, which is incorporated by reference herein in its entirety. In one embodiment, the insert 110a is perpendicular to the optoelectronic card as shown in Figure 1 and Figure 2A 、 2B Such an embodiment has a number of advantages as described in the aforementioned application. In one embodiment, the insert is disposed in an intermediate board, thereby reducing the length of the wire bonds between the traces in the PCB or the electrical interface on the second edge and the insert, thereby reducing impedance / skew. In one embodiment, the insert is part of a board-mounted optical module that is mounted to the optoelectronic card.

[0026] In one embodiment, the interposer integrates both the optical device and the chip.As used herein, an optical device may be any known or later developed component that can be optically coupled to an optical conduit, as described below. The optical device can be, for example: (a) an optoelectronic device (OED), which is an electronic device that generates, detects and / or controls light (e.g., a laser, such as a vertical-cavity surface-emitting laser (VCSEL), a dual-channel, planar buried heterostructure (DC-PBH), a buried crescent (BC), a distributed feedback (DFB), a distributed Bragg reflector (DBR); a light-emitting diode (LED), such as a surface-emitting LED (SLED), an edge-emitting LED (ELED), a superluminescent diode (SLD); a photodiode, such as a P-intrinsic-N (PIN) and an avalanche photodiode (APD); a photonic processor, such as a CMOS photonic processor for receiving optical signals, processing signals and sending response signals, an electro-optical memory, an electro-optical random access memory (EO-RAM) or an electro-optical dynamic random access memory (EO-DRAM), and an electro-optical logic chip (EO-logic chip) for managing optical memory); or (b) a hybrid device that does not convert optical energy into another form but changes state in response to a control signal (e.g., a switch, a modulator, an attenuator and a tunable filter). It should also be understood that the optical device can be a single discrete device, or it can be assembled or integrated into an array of devices. It should also be understood that the optical device can be a single-mode or multi-mode device. In one embodiment, the optical device is a surface emitting light source. In one embodiment, the surface emitting light source is a VCSEL. In one embodiment, the optical component is photosensitive. In one embodiment, the photosensitive optical component is a photodiode.

[0027] In one embodiment, the optical component operates in conjunction with one or more electronic chips 110b. As used herein, "chip" refers to any electronic / semiconductor chip required to facilitate the functionality of the optical component. For example, if the optical component is a transmitter, the chip may be a driver, or if the optical component is a receiver, the chip may be a transimpedance amplifier (TIA). The chips required for a given optical component are well known in the art and will not be described in detail here.

[0028] Despite Figure 1 and Figure 2A 、 2B As shown, the chip is provided on an optoelectronic card, but in other embodiments it may be preferable to integrate the chip with the optical device on an interposer, as disclosed in the '189 application.

[0029] Now refer to Figure 3 , shows an embodiment of a backplane connector 300 of the present invention. The backplane connector is configured to be connected to a daughter card connector assembly (e.g., Figure 1) is mated with the daughter card connector assembly 100 shown in . The backplane connector has a forward and rearward orientation and includes a retainer block 301 configured to be attached to a backplane 303. The retainer block 301 defines a plurality of ring slots 302, each of which is configured to receive a ring 304. As shown, the plurality of rings 304 are configured to be disposed in the ring slots 302. A plurality of ring springs 306 are shown for urging the plurality of rings forward. The springs are retained in a plurality of ring spring retainers 307. The ring spring retainers are mounted rearwardly on the retainer block, with each ring spring retainer retaining springs for two or more rings. Each of these features and selected alternative embodiments are described in more detail below.

[0030] The function of the retainer block 301 is to secure the connector 300 to the backplane 303 and to keep the ferrule properly aligned with respect to the optoelectronic card of the daughter card connector assembly. This can be achieved in different ways. For example, in Figure 3 In an embodiment, a portion of the retainer block "floats" relative to the backplate. For example, in this embodiment, retainer block 301 includes a float 301b defining a ferrule groove for receiving a ferrule and maintaining proper alignment, and a bracket 301a for securing the float to the backplate. Specifically, the bracket is configured to be fastened to the backplate with fasteners 309, such that the float is sandwiched between the bracket and the backplate but is not fastened to the backplate, thereby allowing the float to move relative to the backplate. In this particular embodiment, the bracket is fastened to the front portion 303a of the backplate, although the bracket could also be fastened to the rear portion 303b of the backplate. Additionally, while a floating retainer block is shown in this embodiment, it is possible, although perhaps not preferred, for the retainer assembly to be rigidly secured to the backplate.

[0031] although Figure 3 The holder block shown has a single row of ferrule groove arrays, but other configurations are possible within the scope of the present invention. For example, in one embodiment, the holder block may define multiple rows of ferrule grooves.

[0032] In one embodiment, the retainer block (or at least a portion thereof) comprises metal or other thermally conductive material to carry heat away from the optoelectronic card of the daughter card connector assembly. For example, in one embodiment, the optoelectronic card includes one or more thermally conductive pads 130, such as Figure 2B As shown, it is thermally coupled with the heat conducting portion of the holder to draw heat away from the optoelectronic card. Figure 4AIn one embodiment, the retainer block includes a protruding thermally conductive ear 402 that defines a slot 401 that coincides with the ferrule slot, such that the slot 401 is aligned with the leading edge of the optical electrical card of the daughter card connector assembly and thermally coupled with the thermally conductive pad 130 when the daughter card connector assembly 100 is coupled with the backplane connector 300. Other thermally conductive paths between the optical electrical board and the backplane connector can be determined by one skilled in the art without undue experimentation in light of the present disclosure.

[0033] The ferrule spring retainer is used to retain the spring that pushes the ferrule forward. Applicant has found that the relatively small spacing between the optical electrical cards makes the traditional approach of using a spring retainer for each ferrule difficult. Accordingly, in one embodiment of the present invention, a single ferrule retainer retains the springs for multiple ferrules. For example, referring to Figure 3 , each ferrule spring retainer retains the springs for two adjacent ferrules. In that particular embodiment, two springs correspond to each ferrule, and each ferrule spring retainer retains four springs. It should be appreciated that other embodiments are possible.

[0034] In Figure 3 the illustrated embodiment, each ferrule spring retainer is fastened to the back side of the retainer block with at least one fastener. In that particular embodiment, only two fasteners are used in an up / down relationship. Such a configuration allows for a tight spacing between the ferrule slots.

[0035] Referring to Figure 4B , in one embodiment, each ferrule spring retainer defines at least one channel 405 (see Figure 3 ) through which the optical cable 305 passes. In a more particular embodiment, each ferrule spring retainer defines two channels to accommodate the cables of two ferrules terminated with optical fibers. In one embodiment, the channels define a beveled portion 406 at the location where the optical cable exits the ferrule spring retainer. As Figure 8 illustrated, the beveled portion allows the cable to bend as it exits the ferrule spring retainer. As Figure 8 illustrated, the cable is a ribbon cable, although variations are possible. For example, in one embodiment, the cable includes a ribbon cable portion 880a (see Figure 9 ) terminated to the ferrule and a round cable portion 880b for easier cable management (bending), as described in U.S. Patent Application Publication US20220283392A1. In another embodiment, the optical fiber is in a cable that is terminated to the ferrule using conventional means.

[0036] As Figure 3As shown, backplane connector 300 includes a plurality of ferrules for optically connecting with the subcard connector assembly. The function of ferrules is well known and will not be described in detail here. In this particular embodiment, the plurality of ferrules includes expanded beam lens ferrules. Expanded beam ferrules are generally preferred, although not required, because they do not require physical contact with mating ferrules. Rather, so long as the distance along the optical axis remains substantially constant between two mating ferrules. Sufficient optical coupling is achieved. In one embodiment, the plurality of ferrules includes guide pins for alignment. In a more particular embodiment, the plurality of ferrules includes MT-type ferrules.

[0037] Referring to Figures 10A-10D , an alternative embodiment of a subcard connector assembly 1000 is shown having a heat sink 1001 to draw heat away from the die 1002 of an optoelectronic card 1003. In particular, referring to Figure 10A , the connector assembly 1000 is shown fully populated with optoelectronic cards 1003. Each card includes a heat sink 1001 to dissipate heat from the optoelectronic drivers 1030. In particular, referring to Figure 10B , the optoelectronic drivers 1030 have been removed from one of the optoelectronic cards to expose a front side ground pad 1019 having a card-through-hole 1020 to provide a thermal path from the front side ground pad to the back side of the die of the heat sink 1001. See Figure 10C and 10D , the back of the optoelectronic card is shown. Figure 10D A portion of the heat sink is shown removed to expose a back side thermal pad 1021 in thermal communication with the through-hole 1020. The back side thermal pad 1021 is in thermal communication with the heat sink 1001. In one embodiment, the back side thermal pad 1021 is significantly larger than the front side ground pad 1019, thereby maximizing the thermal coupling between the thermal pad and the heat sink 1001.

[0038] In one embodiment, the die is thermally coupled to the backplane connector and / or the subcard to conduct heat away from the die. For example, in one embodiment, the card edge connector of the PCB die includes one or more thermal pads to conduct heat from the optoelectronic card through the connector into the backplane connector. In another embodiment, the thermal connectors in the connector 120 are configured to conduct heat from the optoelectronic card to the subcard. Alternatively, the heat sink 1001 can also be thermally coupled to the thermal pads or thermal conductors described above. In one embodiment, the rigidity of the heat sink 1001 can be used to dissipate heat from the subcard. In such an embodiment, the thermal conductors would be configured to conduct heat away from the subcard and into the heat sink 1001 to be dissipated to the environment. Other embodiments for dissipating heat will be apparent to those skilled in the art in light of this disclosure.

Claims

1. A backplane connector for mating with a daughter card connector assembly, the backplane connector having a forward orientation and a rearward orientation and comprising: a retainer block configured for attachment to the backing plate and defining a plurality of ferrule slots, each slot configured to receive a ferrule; a plurality of ferrules disposed in the ferrule grooves; a plurality of collar springs for pushing the plurality of collars forward; and A plurality of ferrule spring retainers are used to retain the ferrule springs and are mounted rearwardly on the retainer block, wherein each ferrule spring retainer retains springs for two or more ferrules.

2. The backplane connector according to claim 1, wherein: The ferrule slots are arranged in a linear array, and wherein each of the ferrule spring retainers retains springs of two adjacent ferrules.

3. The backplane connector according to claim 1, wherein: Two of the plurality of coil springs correspond to each coil, and wherein each of the coil spring holders holds four springs.

4. The backplane connector according to claim 1, wherein: Each of the ferrule spring retainers is fastened to the retainer block using no more than two fasteners.

5. The backplane connector according to claim 1, wherein: Each of the ferrule spring retainers defines at least one passage through which an optical cable passes.

6. The backplane connector according to claim 5, wherein: The channel defines a ramped portion at a location where the optical cable exits the ferrule spring retainer, the ramped portion allowing the optical cable to bend when exiting the ferrule spring retainer.

7. The backplane connector according to claim 5, wherein: The cable is a ribbon cable.

8. The backplane connector according to claim 5, wherein: The cable includes a ribbon cable portion and a round cable portion for easier cable management.

9. The backplane connector according to claim 1, wherein: The ferrule retainer block is metallic to absorb heat from the daughter card connector assembly.

10. The backplane connector according to claim 1, wherein: The retainer block includes a floating block and a bracket defining the ferrule groove.

11. The backplane connector according to claim 10, wherein: The bracket is configured to be secured to the backplate such that the slider is sandwiched between the bracket and the backplate but is not secured to the backplate, thereby allowing the slider to move relative to the backplate.

12. The backplane connector according to claim 11, wherein: The bracket is secured to the front of the back panel.

13. The backplane connector according to claim 10, wherein: Each of the ferrule slots is configured to align with a front edge of an optoelectronic card of the daughtercard connector assembly.

14. The backplane connector according to claim 1, wherein: The plurality of ferrules includes an expanding beam ferrule.

15. The backplane connector according to claim 1, wherein The plurality of ferrules include guide pins for alignment.

16. The backplane connector according to claim 15, wherein: The plurality of ferrules include MT-type ferrules.

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