Detailed Description
Accordingly, in one embodiment, the present invention is directed to a daughter card connector assembly comprising (a) a housing defining a first plane configured to be mounted parallel to a backplane, a second plane for being mounted parallel to the daughter card, and a plurality of parallel slots perpendicular to the first plane, and (b) one or more optoelectronic cards each disposed in one of the plurality of slots and including at least (i) a Printed Circuit Board (PCB) defining at least a first edge and a second edge, wherein the first edge is parallel to the first plane and the second edge is parallel to the second plane when the optoelectronic cards are mounted in the slots, (ii) a blind mate optical connector along the first edge, (iii) an electrical interface along the second edge, (iv) at least one optical component mounted on the PCB for converting between electrical signals and optical signals, electrically connecting to at least a portion of the electrical interface, and (v) a waveguide connecting the optical component to the one or more PCBs.
In another embodiment, the invention is directed to an optoelectronic card for mounting in a slot of a housing of a daughter card connector assembly, the housing defining a first plane configured to be mounted parallel to a backplane, a second plane configured to be mounted parallel to the daughter card, and a plurality of parallel slots perpendicular to the first plane, the card including (a) a Printed Circuit Board (PCB) configured to be received within the slots and defining at least a first edge and a second edge, wherein the first edge is parallel to the first plane and the second edge is parallel to the second plane when the optoelectronic card is mounted in the slots, (b) a blind mate optical connector along the first edge, (c) an electrical interface along the second edge, (d) at least one optical component mounted on the PCB for converting between electrical signals and optical signals, the PCB being electrically connected to at least a portion of the electrical interface, and (e) one or more waveguides connecting the optical component and the optical connector.
Referring to fig. 1-2, one embodiment of a daughter card connector assembly 100 is shown. The daughter card connector assembly 100 includes a housing 101, the housing 101 defining a first plane 101a configured to mount parallel to the 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 figures, 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 drive circuit 110b. One or more waveguides 111 connect the optical components with the optical connectors. In this embodiment, the waveguide is an optical fiber 112.
Each of these elements/features is described in detail below in connection with selected alternative embodiments.
In one embodiment, the daughter card connector assembly includes a discrete/modular optoelectronic card 104. In one embodiment, each discrete optoelectronic card is releasably engaged with housing 101. In one embodiment, housing 101 includes a plurality of slots 102, and each optoelectronic card 104 slidably engages one of the slots. Typically, each optoelectronic card includes one or more optical components for transmitting/receiving electrical/optical signals, but it should be understood that the optoelectronic cards may be dedicated optical receivers or dedicated optical transmitters. In this regard, the modular construction of the optoelectronic card allows a given daughter card connector assembly to be constructed in different ways. For example, depending on the application, the daughter card connector assembly may include one portion of an optoelectronic card configured for transceiving and another portion of the optoelectronic card dedicated to receiving and/or transmitting.
Not only does the modularity of the optoelectronic card provide flexibility in constructing a daughter card connector assembly with a transmit/receive optoelectronic card, but also provides scalability. That is, in one embodiment, the daughter card connector assembly of the present invention may be scaled up to meet the needs of the application, rather than purchasing and installing a daughter card connector assembly with all of its complementary channels. For example, initially, a backplane connector housing with relatively few optoelectronic cards may be installed, and then additional optoelectronic cards may be added to the housing as the demand for additional channels grows. Thus, in one embodiment, the daughter card connector assembly of the present invention provides a pay-as-you-grow solution.
Another benefit of the modular construction of the optoelectronic card is the ability to replace defective optoelectronic cards or to periodically upgrade the optoelectronic card without having to replace the entire daughter card connector assembly. In other words, unlike conventional transceivers in which if one or more channels become inoperable, the entire transceiver must be replaced, in one embodiment of the backplane connector assembly, only the inoperable or outdated optoelectronic card need be replaced. Thus, the modular construction of the optoelectronic card eliminates a single point of failure of the entire daughter card connector assembly. Furthermore, the discrete optoelectronic card solution of the present invention enables a configurable ratio of channel protection. More specifically, the scalable architecture of the present invention enables a user to precisely construct a desired level of channel protection, e.g., from 1:1 redundancy to 1:N redundancy, rather than having to provide an entire single redundant multi-channel transceiver (e.g., a 12-channel device) at higher initial and replacement costs.
An important feature of the daughter card connector assembly is the blind mating optical connector 107 on the first edge 105 of the optoelectronic card 103. Such connectors facilitate blind mating of the connector with the back plate. As shown, the optical connector is an MT-type optical connector having alignment pins/alignment pin holes 150 at its ends, and fiber end face 151 is presented centrally. In this particular embodiment, the distance between the aligned pin holes is relatively large compared to the relatively few fibers present in the center of the ferrule. Such a configuration is generally preferred (although not required) because the longer distance between the fiber end face and the alignment pin holes tends to improve aligning the fiber end face with the fiber end face of the mating connector 106 on the backplane. Although an MT-type connector is shown in the embodiments of fig. 1 and 2, other embodiments are possible within the scope of the invention. For example, essentially any blind mate optical connector may be used, so long as it has a thin profile to accommodate the relatively small pitch between the slots of the daughter card connector assembly 100. For example, in one embodiment, the pitch is less than 2mm, and in another embodiment, the pitch is less than 1.8 mm, and in another embodiment, the pitch is less than 1.5 mm.
As shown in fig. 1 and 2, one or more waveguides 111 connect the interposer 110a to the blind mate optical connector 107. In one embodiment, the waveguide is an optical fiber 112 as shown in fig. 1 and 2. In yet another embodiment, the waveguide may be defined in the PCB such that the optical connector 107 is optically coupled with the PCB.
In one embodiment, the first edge of the card 104 further includes an electrical interface 130 for connection to a mating connector on the backplane. In one embodiment, the electrical interface on the first edge is a blind mate electrical connector.
In one embodiment, the electrical interface on 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. Also, in one embodiment, the second plane of the housing has a daughter card interface similar to that defined in the' 985 patent. Specifically, in one embodiment, the daughter card interface includes an eye-of-the-needle connector 120 along the second plane. (such connectors are well known and will not be described in detail here)
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 inserter of the present invention is disclosed, for example, in U.S. patent application Ser. No.16/450,189, which is incorporated by reference in its entirety. In one embodiment, interposer 110a is perpendicular to the optoelectronic card, as shown in fig. 1 and 2. Such an embodiment has a number of advantages as described in the aforementioned application. In one embodiment, the interposer is disposed in the middle of the board, reducing the length of the wire bonds between the electrical interfaces on the second edge or traces in the PCB and the interposer, thereby reducing impedance/hysteresis. In one embodiment, the interposer is part of an on-board optical module mounted to the optoelectronic card.
In one embodiment, the interposer integrates both the optics and the chip. As used herein, an optical device may be any known or later developed component that may be optically coupled to an optical conduit, as described below. The optical device may be, for example, (a) an optical device (OED) which is an electrical device that emits, detects and/or controls light (e.g., a laser such as a Vertical Cavity Surface Emitting Laser (VCSEL), a double channel, a 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 the light signal, processing the signal and transmitting a response signal, 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 the optical memory, or (b) a hybrid device (e.g., a switch, modulator, attenuator and tunable filter) that does not convert the light energy into another form but changes state in response to the control signal. It should also be appreciated that the optical device may be a single discrete device, or it may be assembled or integrated into an array of devices. It should also be appreciated that the optical device may be a single mode or multimode 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.
In one embodiment, the optical components work in conjunction with one or more electronic chips 110 b. A chip as used herein refers to any electronic/semiconductor chip that is required to facilitate the function of an 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 element are well known in the art and will not be described in detail here.
Although shown in fig. 1 and 2, the chip is disposed on an optoelectronic card, in other embodiments, as disclosed in the' 189 application, it may be desirable to integrate the chip with the optics on an interposer.
Referring now to fig. 3, one embodiment of a backplane connector 300 of the present invention is shown. The backplane connector is configured to mate with a daughter card connector assembly (e.g., the daughter card connector assembly 100 shown in fig. 1). The back board connector has a front orientation and a back orientation and includes a retainer block 301 configured for attachment to a back board 303. The retainer block 301 defines a plurality of ferrule slots 302, each slot configured to receive a ferrule 304. As shown, a plurality of ferrules 304 are configured to be disposed in the ferrule slots 302. A plurality of ferrule springs 306 are shown for urging the plurality of ferrules forward. The springs are held in a plurality of ferrule spring holders 307. The ferrule spring holders are mounted back on the holder block, with each ferrule spring holder holding a spring for two or more ferrules. Each of these features, as well as selected alternative embodiments, are described in more detail below.
The function of the retainer block 301 is to secure the connector 300 to the back plate 303 and to maintain the ferrule in proper registration with respect to the optoelectronic card of the daughter card connector assembly. This may be achieved in different ways. For example, in the embodiment of FIG. 3, a portion of the retainer block "floats" relative to the back plate. For example, in this embodiment, the retainer block 301 includes a slider 301b and a bracket 301a, the slider 301b defining a ferrule slot for receiving a ferrule and maintaining proper registration, and the bracket 301a for securing the slider to the backplate. Specifically, the bracket is configured to be fastened to the back plate with fasteners 309 such that the slider is sandwiched between the bracket and the back plate, but not fastened to the back plate, thereby allowing the slider to move relative to the back plate. In this particular embodiment, the bracket is secured to the front portion 303a of the back plate, although the bracket may also be secured to the rear portion 303b of the back plate. In addition, although a floating retainer block is shown in this embodiment, the retainer block may be rigidly secured to the back plate, although this may not be preferred.
Although the retainer block shown in fig. 3 has a single row ferrule slot array, other arrangements are possible within the scope of the invention. For example, in one embodiment, the retainer block may define a plurality of rows of ferrule slots.
In one embodiment, the retainer block (or at least a portion thereof) includes 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 thermal pads 130, as shown in fig. 2b, to thermally couple with the thermally conductive portion of the holder to draw heat away from the optoelectronic card. For example, referring to fig. 4a, in one embodiment, the retainer block includes protruding thermally conductive ears 402 defining slots 401 that coincide with the ferrule slots such that the slots 401 are aligned with the front edges of the optoelectronic cards of the daughter card connector assembly and the slots 401 thermally couple with the thermal pads 130 when the daughter card connector assembly 100 is coupled with the backplane connector 300. Other heat conduction paths between the photovoltaic panel and the backplane connector can be determined by those skilled in the art without undue experimentation in light of the present disclosure.
The ferrule spring retainer is used to retain a spring that urges the ferrule forward. Applicants have found that the relatively small spacing between the optoelectronic cards makes conventional methods of using spring retainers difficult for each ferrule. Thus, in one embodiment of the invention, a single ferrule holder holds springs for multiple ferrules. For example, referring to FIG. 3, each ferrule spring holder holds the springs of two adjacent ferrules. In this particular embodiment, two springs correspond to each ferrule, and each ferrule spring holder holds four springs. It should be understood that other embodiments are possible.
In the embodiment shown in fig. 3, each ferrule spring holder is fastened to the rear side of the holder block with at least one fastener. In this particular embodiment, only two fasteners are used in an up/down relationship. Such a configuration allows for tight spacing between ferrule slots.
Referring to fig. 4b, in one embodiment, each ferrule spring holder defines at least one channel 405 (see fig. 3) through which the optical cable 305 passes. In a more specific embodiment, each ferrule spring holder defines two channels to accommodate a cable terminating two ferrules of optical fibers. In one embodiment, the channel defines a ramp portion 406 at the point where the cable exits the ferrule spring holder. The beveled portion allows the cable to bend as it exits the ferrule spring holder as shown in fig. 8. As shown in fig. 8, the cable is a ribbon cable, although variations are possible. For example, in one embodiment, the cable includes a ribbon cable portion 880a (see fig. 9) terminated to the ferrule, and a round cable portion 880b for easier cable management (bending), as described, for example, in U.S. patent application publication US20220283392 A1. In another embodiment, the optical fibers are in a cable that is terminated to the ferrule using conventional equipment.
As shown in fig. 3, the backplane connector 300 includes a plurality of ferrules for optical connection with the optoelectronic board of the daughter card connector assembly. The function of the ferrule is well known and will not be described in detail here. In this particular embodiment, the plurality of ferrules includes an expanded beam lens ferrule. Expanded beam ferrules are generally preferred, although not required, as they do not require physical contact with the mating ferrule. Instead, as long as the distance along the optical axis remains substantially constant between the two mating ferrules. A sufficient optical coupling is achieved. In one embodiment, the plurality of ferrules includes guide pins for alignment. In a more specific embodiment, the plurality of ferrules includes MT-type ferrules.
Referring to fig. 10A-10d, an alternative embodiment of a daughter card connector assembly 1000 is shown having a heat sink 1001 to draw heat away from a wafer 1002 of an optoelectronic card 1003. In particular, referring to fig. 10a, the connector assembly 1000 is shown completely filled with an optoelectronic card 1003. Each card includes a heat sink 1001 to dissipate heat from the optoelectric drive 1030. In particular, referring to fig. 10b, the optoelectronic driver 1030 has been removed from one of the optoelectronic cards to expose a front side ground pad 1019 having a through-card aperture 1020 to provide a thermal path from the front side ground pad to the backside of the wafer and heat sink 1001. Referring to fig. 10c and 10d, the back side of the optoelectronic card is shown. Fig. 10d shows a portion of the heat sink removed to expose the backside thermal pad 1021 in thermal communication with the via 1020. The backside thermal pad 1021 is in thermal communication with the heat sink 1001. In one embodiment, the backside thermal pad 1021 is significantly larger than the front side thermal pad 1019 to maximize the thermal coupling between the thermal pad and the heat sink 1001.
In one embodiment, the wafer is thermally coupled to the backplane connector and/or daughter card to transfer heat away from the wafer. 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 between connectors 120 are configured to conduct heat from the optoelectronic card to the daughter card. Alternatively, the heat sink 1001 may also be thermally coupled to the thermal pad or conductor described above. In one embodiment, the robustness of the heat sink 1001 may be used to dissipate heat from the daughter card. In such an embodiment, the thermal conductor would be configured to conduct heat away from the daughter card and into the heat sink 1001 for dissipation into the environment. Other embodiments for heat dissipation will be apparent to those skilled in the art in light of this disclosure.