Optical backplane connector system

Abstract

A backplane connector for mating with a daughter card connector assembly, the backplane connector having a front-to-back orientation, and comprising: (a) a retainer block configured to be mounted on 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 biasing the plurality of ferrules forward; and (d) a plurality of ferrule spring retainers for holding the ferrule springs and mounting them to the rear of the retainer block, each ferrule spring retainer holding a spring for two or more ferrules.

Description

Technical Field

[0001] The present invention generally relates to a printed circuit board (PCB)-based backplane connector assembly, and more particularly to a PCB-based backplane connector system having a blind mating optical interface.

Background Art

[0002] Printed circuit board (PCB)-based backplane connectors are well known. For example, TE Connectivity's MULTIGIG RT interconnect family is employed in various computer, communication, medical, industrial control, and military applications. These connector systems use a printed circuit board (PCB) card or "wafer" instead of a conventional pin-and-socket contact system, eliminating the open pin field in the plug-in module part of the backplane connector and making it less likely for end users to encounter on-site failures in card cage systems. A typical PCB backplane daughter card connector assembly includes a housing that defines a plurality of slots, each slot being configured to receive an individual PCB wafer.

Summary of the Invention

Problems to be Solved by the Invention

[0003] The applicant has recognized that the PCB wafer can be improved by adding a function of converting electrical signals and optical signals to the wafer. Therefore, the applicant has disclosed, for example, a high-density optical daughter card connector assembly described in U.S. Patent No. 10,852,489. This optical daughter card connector assembly meets many needs, especially with respect to its configurable free-end optical fibers. However, the applicant has recognized further needs for a blind mating optical daughter card connector assembly. The present invention particularly meets these needs. [Means for solving the problem]

[0004] The solution is provided by a backplane connector for mating with a daughter card connector assembly, the backplane connector having a front-to-back orientation and comprising: (a) a retainer block configured to mount on a backplane and defining a plurality of ferrule slots, each slot configured to receive a ferrule; (b) a plurality of ferrules positioned in the ferrule slots; (c) a plurality of ferrule springs for biasing the plurality of ferrules forward; and (d) a plurality of ferrule spring retainers for holding the ferrule springs and mounting behind the retainer block, each ferrule spring retainer holding a spring for two or more ferrules.

[0005] The present invention will now be described with reference to the accompanying drawings as an example. [Brief explanation of the drawing]

[0006] [Figure 1] This is a perspective view of one embodiment of the daughter card connector assembly of the present invention. [Figure 2A] Figure 1 is a perspective view of the daughter card connector assembly, where the fiber connects the optical connector to the optical components. [Figure 2B] This is a magnified view of a portion of Figure 2A. [Figure 3] This is an exploded view of one embodiment of the backplane connector of the present invention. [Figure 4A] Figure 3 is a front perspective view of the backplane connector. [Figure 4B] Figure 3 is a rear perspective view of the backplane connector. [Figure 5] Figure 3 is a front view of the backplane connector. [Figure 6] Figure 1 is a front view of the connector assembly. [Figure 7]Figure 3 is a rear perspective view of the backplane connector coupled to the daughter card connector assembly shown in Figure 1. [Figure 8] Figure 3 is a front perspective view of the backplane connector coupled to the daughter card connector assembly shown in Figure 1, with the cable extending at an angle from the back of the backplane connector. [Figure 9] Figure 7 is a cross-sectional view of the connected connector. [Figure 10A] This is a perspective view of an alternative embodiment of a daughter card connector assembly equipped with a heat sink for dissipating heat from the wafer. [Figure 10B] This is a perspective view of an alternative embodiment of a daughter card connector assembly equipped with a heat sink for dissipating heat from the wafer. [Figure 10C] This is a perspective view of an alternative embodiment of a daughter card connector assembly equipped with a heat sink for dissipating heat from the wafer. [Figure 10D] This is a perspective view of an alternative embodiment of a daughter card connector assembly equipped with a heat sink for dissipating heat from the wafer. [Modes for carrying out the invention]

[0007] Referring to Figures 1 and 2, one embodiment of the daughter card connector assembly 100 is shown. The daughter card connector assembly 100 comprises a housing 101 that defines a plurality of parallel slots 102 perpendicular to the first face, a first face 101a configured to mount parallel to the backplane, and a second face 101b configured to mount parallel to a daughter card (not shown). The daughter card connector assembly 100 also comprises one or more photoelectric cards 103. Each of the one or more photoelectric cards comprises at least a printed circuit board (PCB) 104 that is positioned in one of the plurality of slots and has at least a first edge 105 and a second edge 106. When a photoelectric card is mounted in a slot, the first edge becomes parallel to the first face, and the second edge becomes parallel to the second face. A blind-mating optical connector (or ferrule) 107 is positioned along a first edge, and an electrical interface is positioned along a second edge. (In Figures 1 and 2, the electrical interface is hidden by the housing 101). At least one optical component 110 is mounted on the PCB to convert electrical signals to optical signals, and the PCB is electrically connected to at least a portion of the electrical interface. In this particular embodiment, the optical component 110 comprises a photoelectric device 110a and a drive circuit 110b. One or more waveguides 111 connect the optical component to the optical connector. In this embodiment, the waveguide is an optical fiber 112.

[0008] Each of these elements / features is described in detail below in relation to the selected alternative embodiment.

[0009] In one embodiment, the daughter card connector assembly comprises individual / modular photoelectric cards 104. In one embodiment, each individual photoelectric card is releasably engaged with a housing 101. In one embodiment, the housing 101 comprises a plurality of slots 102, and each photoelectric card 104 is slidably engaged with one of the slots. Generally, each photoelectric card comprises one or more optical components for transmitting / receiving electrical / optical signals, but it should be understood that a photoelectric card may be a dedicated optical receiver or a dedicated optical transmitter. In this regard, the modular configuration of the photoelectric cards allows for different configurations of a given daughter card connector assembly. For example, the daughter card connector assembly may, depending on the application, configure a portion of the photoelectric card for transmission and reception, and another portion of the photoelectric card for reception only and / or transmission only.

[0010] The modularity of photoelectric cards provides not only flexibility in configuring daughter card connector assemblies with transceiver / transmitter / receiver photoelectric cards, but also expandability. That is, in one embodiment, the daughter card connector assembly of the present invention can be expanded to meet the demands of the application, rather than purchasing and implementing a daughter card connector assembly with all the channels. For example, a backplane connector housing with a relatively small number of photoelectric cards may be implemented initially, and then more photoelectric cards may be added to the housing as the demand for channels increases. Thus, in one embodiment, the daughter card connector assembly of the present invention provides an expandable solution.

[0011] Another advantage of the modular configuration of photoelectric cards is that a faulty photoelectric card can be replaced or photoelectric cards can be upgraded periodically without having to replace the entire daughter card connector assembly. In other words, unlike conventional transceivers where the entire transceiver must be replaced if one or more channels become inoperable, in one embodiment of the backplane connector assembly, only the inoperable or outdated photoelectric card needs to be replaced. Thus, the modular configuration of photoelectric cards avoids the entire daughter card connector assembly being affected by a single failure. Furthermore, the individual photoelectric card solution of the present invention allows for a configurable channel protection ratio. More specifically, the expandable configuration of the present invention allows users to precisely set the desired channel protection level (e.g., from 1:1 redundancy to 1:N redundancy) without having to prepare a single redundant multichannel transceiver (e.g., 12 channel devices), which would incur high initial deployment and replacement costs.

[0012] One important feature of the daughter card connector assembly is the blind mating optical connector 107 at the first edge 105 of the optical card 103. Such a connector facilitates the blind mating of the connector to the backplane. As shown in FIGS. 1 and 2, the optical connector is an MT type optical connector having end alignment pins / alignment pin holes 150 and a fiber end face 151 present at the center. In this particular embodiment, the distance between the alignment pin holes is relatively large compared to the relatively small number of fibers present at the center of the ferrule. Such a configuration is generally preferred (but not essential) because when the distance between the fiber end face and the alignment pin holes is long, the alignment between the fiber end face and the fiber end face of the mating connector on the backplane is improved. Although an MT type connector is shown in the embodiments of FIGS. 1 and 2, other embodiments are also possible within the scope of the present invention. For example, basically any blind mating optical connector may be used as long as it has a thin outer shape to accommodate the relatively narrow pitch between the slots of the daughter card connector assembly 100. For example, in one embodiment, the pitch is less than 2 mm, in another embodiment, it is less than 1.8 mm, and in another embodiment, it is less than 1.5 mm.

[0013] As shown in FIGS. 1 and 2, one or more waveguides 111 connect the interposer 110a to the blind mating optical connector 107. In one embodiment, the waveguide is an optical fiber 112 as shown in FIGS. 1 and 2. In yet another embodiment, the waveguide may be defined on a PCB such that the optical connector 107 optically couples to the PCB.

[0014] In one embodiment, the first edge of the card 104 also includes an electrical interface 130 for connection to the mating connector on the backplane. In one embodiment, the electrical interface at the first edge is a blind mating electrical connector.

[0015] In one embodiment, the electrical interface at the second edge of the card is similar to that disclosed in U.S. Patent No. 9,196,985, which is incorporated herein by reference. Similarly, in one embodiment, the second face 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 needle icon connector 120 along the second face (such connectors are well-known and will not be described in detail herein).

[0016] In one embodiment, the optical component 110 includes an interposer 110a and a chip 110b. The interposer 110a includes an innovative interposer that minimizes hysteresis and simplifies optical alignment. One embodiment of the interposer of the present invention is disclosed, for example, in U.S. Patent Application No. 16 / 450,189, which is incorporated herein in its entirety by reference. In one embodiment, as shown in FIGS. 1 and 2, the interposer 110a is perpendicular to the optoelectronic card. Such an embodiment has several advantages as described in the above application. In one embodiment, by placing the interposer at the center of the substrate, the length of the PCB traces and wire bonds between the electrical interface at the second edge and the interposer is shortened, thereby reducing impedance / hysteresis. In one embodiment, the interposer is part of an on-board optical module attached to the optoelectronic card.

[0017] In one embodiment, the interposer integrates both an optical device and a chip. As used herein, an optical device may be any known or future-developed component that can be optically coupled to an optical waveguide, as described below. Optical devices are, for example, (a) electrical devices that generate, detect and / or control light, such as photoelectric devices (OEDs) (e.g., lasers such as vertical cavity surface-emitting lasers (VCSELs), double-channel, planar-buried heterostructures (DC-PBHs), buried crescent (BCs), distributed feedback (DFBs), distributed Bragg reflectors (DBRs), light-emitting diodes (LEDs) such as surface-emitting LEDs (SLEDs), edge-emitting LEDs (ELEDs), superluminescent diodes (SLDs), and avalanche photodiodes (APDs) (b) Photonic processors such as photodiodes, CMOS photonic processors that receive and process optical signals and transmit response signals, electro-optical memory, electro-optical random-access memory (EO-RAM) or electro-optical dynamic random-access memory (EO-DRAM), and electro-optical logic chips (EO-logic chips) for managing optical memory, or (b) hybrid devices that do not convert optical energy into another form but whose state changes in response to control signals (e.g., switches, modulators, attenuators, and tunable filters). Furthermore, it should be understood that the optical device may be a single, individual device, or it may be assembled or integrated as an array of devices. It should also be understood that the optical device may be a single-mode device or a 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 (Vertical-Camera-Selective-Layer). In one embodiment, the optical component is photosensitive. In one embodiment, the photosensitive optical component is a photodiode.

[0018] In one embodiment, the optical component cooperates with one or more electronic chips 110b. As used herein, a chip refers to any electronic / semiconductor chip necessary to facilitate the function 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.

[0019] As shown in Figures 1 and 2, the chip is located on a photoelectric card, but in other embodiments, it may be preferable to integrate the chip with the optical device on an interposer, as disclosed in '189 application.

[0020] Referring now to Figure 3, one embodiment of the backplane connector 300 of the present invention is shown. The backplane connector is configured to mate with a daughter card connector assembly, for example, the daughter card connector assembly 100 shown in Figure 1. The backplane connector includes a retainer block 301 which has a front-to-back orientation and is configured to be mounted on a backplane 303. The retainer block 301 defines a plurality of ferrule slots 302, each slot configured to receive a ferrule 304. As shown in Figure 3, the plurality of ferrules 304 are configured to be positioned in the ferrule slots 302. A plurality of ferrule springs 306 for biasing the plurality of ferrules forward is shown. The spring is held in multiple ferrule spring retainers 307. The ferrule spring retainers are mounted behind the retainer block, and each ferrule spring retainer holds the spring for two or more ferrules. Each of these features, along with selected alternative embodiments, is described in more detail below.

[0021] The retainer block 301 functions to secure the connector 300 to the backplane 303 and to hold the ferrule in the correct position relative to the photoelectric card of the daughter card connector assembly. This can be implemented in various ways. For example, in the embodiment shown in Figure 3, a portion of the retainer block "floats" relative to the backplane. For example, in this embodiment, the retainer block 301 comprises a floating block 301b that defines a ferrule slot for receiving and holding the ferrule in the correct position, and a bracket 301a for securing the floating block to the backplane. Specifically, the bracket is configured to be fastened to the backplane using a fastener 309 such that the floating block is sandwiched between the bracket and the backplane but not fastened to the backplane, thereby allowing the floating block to move relative to the backplane. In this particular embodiment, the bracket is fastened to the front portion 303a of the backplane, but the bracket may also be fastened to the rear portion 303b of the backplane. Furthermore, although a floating retainer block is shown in this embodiment, it is also possible (though potentially undesirable) to firmly fix the retainer block to the backplane.

[0022] The retainer block shown in Figure 3 has a single-row array of ferrule slots, but other configurations are possible within the scope of the present invention. For example, in one embodiment, the retainer block may define multiple rows of ferrule slots.

[0023] In one embodiment, the retainer block (or at least a portion thereof) may include a metal or other thermally conductive material for dissipating heat from the photoelectric card of the daughter card connector assembly. For example, in one embodiment, the photoelectric card includes one or more thermally conductive pads 130 for dissipating heat from the photoelectric card by thermally coupling with the thermal conduction portion of the retainer, as shown in Figure 2B. Referring to Figure 4A, for example, in one embodiment, the retainer block includes a protruding thermally conductive ear 402 which defines a slot 401 that coincides with a ferrule slot, so that when the daughter card connector assembly 100 is coupled to the backplane connector 300, the slot 401 aligns with the front end of the photoelectric card in the daughter card connector assembly and thermally couples with the thermally conductive pad 130. Those skilled in the art can determine other heat conduction paths between the photoelectric substrate and the backplane connector without excessive experimentation in view of the present disclosure.

[0024] A ferrule spring retainer functions to hold a spring that biases a ferrule forward. The applicant recognized that the relatively narrow pitch between photoelectric cards makes the conventional method of using a spring retainer for each ferrule difficult. As a result, in one embodiment of the present invention, a single ferrule retainer holds springs for multiple ferrules. Referring to Figure 3, for example, each ferrule spring retainer holds springs for two adjacent ferrules. In this particular embodiment, two springs correspond to each ferrule, and each ferrule spring retainer holds four springs. It should be understood that other embodiments are also possible.

[0025] In the embodiment shown in Figure 3, each ferrule spring retainer is fastened to the rear of the retainer block using at least one fastener. In this particular embodiment, only two fasteners are used in an upper-lower relationship. This configuration allows for a narrow pitch between the ferrule slots.

[0026] Referring to Figure 4B, in one embodiment, each ferrule spring retainer defines at least one channel 405 through which the optical cable 305 passes (see Figure 3). In a more specific embodiment, each ferrule spring retainer defines two channels for housing the cables of two ferrules to which the fibers are terminated. In one embodiment, the channels define a chamfered portion 406 where the optical cable exits the ferrule spring retainer. As shown in Figure 8, the chamfered portion allows the cable to bend as it exits the ferrule spring retainer. As shown in Figure 8, the cable is a ribbon cable, but variations are possible. For example, in one embodiment, as described in U.S. Patent Application Publication No. 20220283392(A1), the cable comprises a ribbon cable section 880a terminated to a ferrule (see Figure 9) and a round cable section 880b for facilitating cable management (bending). In another embodiment, the fiber is in a cable terminated to a ferrule using conventional means.

[0027] As shown in Figure 3, the backplane connector 300 comprises a plurality of ferrules for optical connection with the photoelectric substrate of the daughter card connector assembly. The function of the ferrules is well known and will not be described in detail herein. In this particular embodiment, the plurality of ferrules include a ferrule with an extended beam lens. Extended beam ferrules are generally preferred, but not required, because they do not require physical contact with the mating ferrule. Rather, sufficient optical coupling can be achieved if the distance along the optical axis between the two mating ferrules is essentially constant. In one embodiment, the plurality of ferrules comprises guide pins for alignment. In a more specific embodiment, the plurality of ferrules include an MT type ferrule.

[0028] Referring to Figures 10A to 10D, alternative embodiments of the daughter card connector assembly 1000 are shown, which have a heat sink 1001 for dissipating heat from the wafer 1002 of the photoelectric card 1003. Specifically, referring to Figure 10A, the connector assembly 1000 is shown with the photoelectric card 1003 fully mounted. Each card is provided with a heat sink 1001 for dissipating heat from the photoelectric driver 1030. Specifically, referring to Figure 10B, the photoelectric driver 1030 is removed from one of the photoelectric cards to expose the front grounding pad 1019, and a card-through via 1020 is provided to realize a heat path from the front grounding pad to the back of the wafer and the heat sink 1001. Referring to Figures 10C and 10D, the back of the photoelectric card is shown. Figure 10D shows a portion of the heatsink removed to reveal the rear thermal pad 1021 which is in thermal communication with via 1020. The rear thermal pad 1021 is in thermal communication with the heatsink 1001. In one embodiment, the rear thermal pad 1021 is significantly larger than the front grounding pad 1019 to maximize the thermal coupling between the thermal pad and the heatsink 1001.

[0029] In one embodiment, the wafer is thermally coupled to a backplane connector and a daughter card to dissipate heat from the wafer. For example, in one embodiment, the card edge connector of the PCB wafer includes one or more thermal pads for conducting heat from the photoelectric card through the connector to the backplane connector. In another embodiment, the thermal connector of the connector 120 is configured to conduct heat from the photoelectric card to the daughter card. Alternatively, the heat sink 1001 may be thermally coupled to the thermal pads or thermal conductors described above. In one embodiment, the robustness of the heat sink 1001 may be used to dissipate heat from the daughter card. In such embodiments, the thermal conductor may be configured to conduct heat from the daughter card to the heat sink 1001 and dissipate it into the environment. Those skilled in the art will also see, in view of this disclosure, that further embodiments for heat dissipation will be apparent.

Claims

1. A backplane connector for mating with a daughter card connector assembly, wherein the backplane connector has a front-to-back orientation. The aforementioned backplane connector is - A retainer block configured to be mounted on a backplane and defining multiple ferrule slots, each slot configured to receive a ferrule, and - Multiple ferrules arranged in the ferrule slot, - Multiple ferrule springs for biasing the multiple ferrules forward, - A plurality of ferrule spring retainers for holding the ferrule spring and mounting it behind the retainer block, wherein each ferrule spring retainer holds a spring for two or more ferrules and A backplane connector equipped with the following features.

2. The backplane connector according to claim 1, wherein the ferrule slots are arranged as a linear array, and each ferrule spring retainer holds the springs of two adjacent ferrules.

3. The backplane connector according to claim 1, wherein two of the plurality of ferrule springs correspond to each ferrule, and each ferrule spring retainer 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 two or fewer fasteners.

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

6. The backplane connector according to claim 5, wherein the channel defines a chamfered portion at the location where the optical cable exits the ferrule spring retainer, and the chamfered portion allows the optical cable to bend as it exits the ferrule spring retainer.

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

8. The backplane connector according to claim 5, wherein the optical cable comprises a ribbon cable portion and a round cable portion for facilitating cable management.

9. The backplane connector according to claim 1, wherein the retainer block for the ferrule is made of metal for absorbing heat from the daughter card connector assembly.

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

11. The backplane connector according to claim 10, wherein the bracket is configured to fasten to the backplane such that the floating block is sandwiched between the bracket and the backplane but is not fastened to the backplane, thereby allowing the floating block to move relative to the backplane.

12. The backplane connector according to claim 11, wherein the bracket is fastened to the front of the backplane.

13. The backplane connector according to claim 10, wherein each of the ferrule slots is configured to align with the front end of the photoelectric card of the daughter card connector assembly.

14. The backplane connector according to claim 1, wherein the plurality of ferrules include an extended beam ferrule.

15. The backplane connector according to claim 1, wherein the plurality of ferrules are provided with alignment guide pins.

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

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