Abstract:
A thermal interface may include a thermally conductive cap. The thermally conductive cap may include a base, a finger, and an extension. The base may define a plurality of cap openings. The finger may extend from the base. The extension may extend from the base. The thermal interface may also include a gasket defining a plurality of gasket openings. The gasket may be located on the base of the cap such that the gasket openings are positioned over the cap openings.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. Provisional Patent Application No. 62/307,063, filed Mar. 11, 2016, titled THERMAL INTERFACE FOR COMMUNICATION MODULE, which is incorporated herein by reference in its entirety. 
     
    
     BACKGROUND 
       [0002]    Communication modules, such as electronic or optoelectronic transceivers or transponder modules, are increasingly used in electronic and optoelectronic communication. Each communication module typically communicates with a host device printed circuit board by transmitting and/or receiving electrical data signals to and/or from the host device printed circuit board. The communication module can also transmit electrical data signals outside a host device as optical and/or electrical data signals. Many communication modules include optical subassemblies (individually, an “OSA”) such as transmitter optical subassemblies (individually, a “TOSA”) and/or receiver optical subassemblies (individually, a “ROSA”) to convert between the electrical and optical domains. 
         [0003]    Generally, a ROSA transforms an optical signal received from an optical fiber or other source to an electrical signal provided to the host device, while a TOSA transforms an electrical signal received from the host device to an optical signal emitted onto an optical fiber or other transmission medium. A photodiode or similar optical receiver contained by the ROSA transforms the optical signal to the electrical signal. A laser diode or similar optical transmitter contained within the optical subassembly is driven to emit an optical signal representing the electrical signal received from the host device. 
       SUMMARY 
       [0004]    This Summary is provided to introduce a selection of concepts in a simplified form that are further described below. This Summary is not intended to identify key features or essential characteristics of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter. 
         [0005]    Embodiments may include a thermal interface may including a thermally conductive cap. The thermally conductive cap may include a base, a finger, and an extension. The base may define a plurality of cap openings. The finger may extend from the base. The extension may extend from the base. The thermal interface may also include a gasket defining a plurality of gasket openings. The gasket may be located on the base of the cap such that the gasket openings are positioned over the cap openings. 
         [0006]    Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by the practice of the invention. The features and advantages of the invention may be realized and obtained by means of the instruments and combinations particularly pointed out in the appended claims. These and other features of the present invention will become more fully apparent from the following description and appended claims, or may be learned by the practice of the invention as set forth hereinafter. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]    To further clarify the above and other advantages and features of the present invention, a more particular description of the invention will be rendered by reference to specific embodiments thereof which are illustrated in the appended drawings. These drawings depict only example embodiments of the invention and are therefore not to be considered limiting of its scope. The invention will be described and explained with additional specificity and detail through the use of the accompanying drawings. 
           [0008]      FIG. 1A  illustrates a bottom perspective view of an optoelectronic module. 
           [0009]      FIG. 1B  illustrates a partial bottom perspective view of the optoelectronic module of  FIG. 1A . 
           [0010]      FIG. 1C  illustrates a partial exploded bottom perspective view of the optoelectronic module of  FIG. 1A . 
           [0011]      FIGS. 2A and 2B  illustrate side perspective views of an assembly including a transmitter optical subassembly (TOSA), a cap, and a gasket. 
           [0012]      FIG. 2C  illustrates an exploded side view of the assembly of  FIGS. 2A and 2B . 
           [0013]      FIG. 3  illustrates an exploded perspective view of the cap and the gasket of  FIGS. 2A-2C . 
           [0014]      FIG. 4  illustrates an exploded perspective view of an assembly including the assembly of  FIGS. 2A-2C  and a printed circuit board (PCB) and connector. 
       
    
    
     DESCRIPTION 
       [0015]    The process of converting optical signals to electrical signals and electrical signals to optical signals can generate thermal energy in optical subassemblies (individually, an “OSA”) such as transmitter optical subassemblies (individually, a “TOSA”) and/or receiver optical subassemblies (individually, a “ROSA”). The thermal energy generated in the optical subassembly may potentially cause damage to the optical subassembly. Additionally, high-temperature environments can create unstable thermal conditions that can cause ineffective optical subassembly function. 
         [0016]    For example, for a TOSA, a high temperature environment can reduce laser performance or can cause premature laser failure. High temperatures may also cause problems to epoxies, solder, and/or other bonding materials in the optical subassembly. These high temperatures may become too great to be effectively dissipated and controlled by a thermoelectric cooler (TEC) installed in the optical subassembly. 
         [0017]    Some embodiments may include a thermal interface to dissipate heat produced by an optical subassembly. In some configurations, the thermal interface may conduct heat from an optical subassembly, such as a TOSA, to a shell or housing of the communication module housing the optical subassembly. In some embodiments, the optical subassembly may also include a TEC. Where a TEC is included, the thermal interface may facilitate more effective heat dissipation and control by the TEC. For example, the thermal interface may encourage relatively manageable heat levels. 
         [0018]    Reference is made to the drawings, where similar or equivalent components are referenced using the same reference numbers. 
         [0019]      FIGS. 1A-1C  illustrate various bottom perspective views of an example optoelectronic module  100 . 
         [0020]      FIG. 1A  illustrates a bottom perspective view of the optoelectronic module  100 , including a housing  102  that may include a shell  104  and a shell cover  106  attached together. The optoelectronic module  100  may include a latch mechanism  114  movingly positioned relative to the housing  102 . The latch mechanism  114  may allow the optoelectronic module  100  to be selectively secured relative to a host device. 
         [0021]    The housing  102  may at least partially surround receiver and/or transmitter circuitry, including a printed circuit board (PCB)  110  having an edge connector  112  configured to be electrically coupled to the host device. For example, the optoelectronic module  100  may be configured to be inserted into a host device cage of the host device such that the edge connector  112  may be electrically coupled to a connector of a host printed circuit board. 
         [0022]    In general, the optoelectronic module  100  may be employed in the communication of optical signals and the conversion of optical signals to and from electrical signals. In connection, the host device may be employed in the communication of corresponding electrical signals. 
         [0023]    The optoelectronic module  100  may include a transmit port and a receive port at a front of the optoelectronic module  100 . The optoelectronic module  100  may be configured for optical signal transmission and reception via the transmit port and the receive port at a variety of data rates including, but not limited to, 1.25 Gb/s, 2.125 Gb/s, 2.5 Gb/s, 2.7 Gb/s, 4.25 Gb/s, 8.5 Gb/s, 10.3 Gb/s, 10.5 Gb/s, 11.3 Gb/s, 14.025 Gb/s, or 100 Gb/s or higher. 
         [0024]    The optoelectronic module  100  may be configured for optical signal transmission and reception at various wavelengths including, but not limited to, 850 nm, 1310 nm, 1470 nm, 1490 nm, 1510 nm, 1530 nm, 1550 nm, 1570 nm, 1520-1570 nm, 1590 nm, or 1610 nm. The optoelectronic module  100  may be configured to support various communication protocols including, but not limited to, Optical Fast Ethernet, Optical Gigabit Ethernet, 10 Gigabit Ethernet, and 1×, 2×, 4×, 8×, and 16× Fibre Channel. 
         [0025]    In addition, although one example of the optoelectronic module  100  is configured to have a form factor that is substantially compliant with the SFP MSA, the optoelectronic module  100  may alternatively be configured in a variety of different form factors that are substantially compliant with other MSAs including, but not limited to, the QSFP MSA, the QSFP+MSA, the CFP MSA, the CFP2 MSA, the CFP4 MSA, the XFP MSA, or the SFP+MSA. Finally, although the optoelectronic module  100  is illustrated as a pluggable optoelectronic transceiver module, example embodiments disclosed herein may alternatively be employed, for example, in connection with other communications modules, other optoelectronic devices, or the like. 
         [0026]      FIG. 1B  illustrates a bottom perspective view of the optoelectronic module  100  of  FIG. 1A  with the shell cover  106  and the latch mechanism  114  omitted. The optoelectronic module  100  includes a TOSA  108  and a ROSA  109 . 
         [0027]    The TOSA  108  may include a TEC. A body of the header  111  of the TOSA  108  may be formed from a nickel-cobalt ferrous alloy associated with the trademark Kovar, which is owned by CRS Holdings, Inc. The alloy may be employed, at least in part, for its thermal expansion properties, which may closely resemble the thermal expansion properties of glass, and which may facilitate glass-to-alloy assemblies capable of being exposed to a range of temperatures. Alternately or additionally, the body of the header  111  may include other materials. The material used in the header  111  may exhibit a relatively low thermal conductivity. For example, Kovar may exhibit a thermal conductivity approximately half that of copper. Thus, for example, a thermally conductive connection between the TOSA  108  and the shell  104  that relies significantly on conductive heat transfer through the header  111  may exhibit relative inefficiency. 
         [0028]    A connector  116  may communicatively connect the TOSA  108  to the PCB  110 . Thus, for example, the TOSA  108  may exchange signals with and/or receive electrical power from the PCB  110  via the connector  116 . The connector  116  may include a flex PCB that is soldered to the PCB  110  and soldered to the TOSA  108 . 
         [0029]      FIG. 1C  illustrates an exploded bottom perspective view of the optoelectronic module  100  of  FIG. 1B . In some embodiments, a thermal interface  118  may include a cap  120 , a gasket  122 , and a pad  124 . The use of the term gasket does not imply that the gasket  122  facilitates a fluid-tight connection. The pad  124  may include a pliant thermal interface material (TIM) and may exhibit a relatively high thermal conductivity. The pad  124  may be located within a seat of the shell  104 . When the TOSA  108 , including the cap  120 , is positioned within the shell  104  during assembly, the pad  124  may be compressed such that the TOSA  108  and the cap  120  are accommodated. In some embodiments, the pad  124  may include multiple portions, as illustrated. Alternatively, the pad  124  may be one piece. 
         [0030]      FIGS. 2A and 2B  illustrate side perspective views of the TOSA  108 , the cap  120 , and the gasket  122  of  FIGS. 1A-1C .  FIG. 2C  is an exploded side view of the TOSA  108 , the cap  120 , and the gasket  122 . 
         [0031]    With reference to  FIGS. 2A-2C , the cap  120  may exhibit a relatively high thermal conductivity. For example, the cap  120  may be formed from copper, plated copper, one or more copper alloys, and/or one or more other materials exhibiting a relatively high thermal conductivity. In some embodiments, the cap  120  may be manufactured at least in part via one or more stamping processes. 
         [0032]    The cap  120  may include one or more fingers  128  and an extension  126 . The fingers  128  may be sized and shaped to be positioned at the side of the header  111 . In some embodiments, the fingers  128  may have a length approximately equal to the length of the header  111  and/or a relatively wide portion of the header  111 . For example, the fingers  128  may have a length approximately equal to a base portion of the header  111 . Alternately, the fingers  128  may have some other length that may facilitate the positioning of the cap  120  on the header  111 . The extension  126  may also be sized and shaped to be positioned at a side of the header  111 . The extension  126  may have a longer length than the fingers  128 . For example, the extension  126  may have a length longer than the header  111  or longer than a base portion of the header  111 . The width of the extension  126  may correlate with the size of a corresponding seat width of the shell  104  of  FIGS. 1A-1C . The extension  126  may include a length suitable for facilitating a desired rate of thermal energy transfer from the portion of the cap  120  in contact with the header  111  to the pad  124  and shell  104 . 
         [0033]    The cap  120  includes a base  121  located on an end face  113  (shown in  FIG. 2C ) of the header  111 , which may be an external face of a wall of the header  111  that includes electrically conductive leads  130  (described herein as an end wall). The leads  130  may be attached to the connector  116  and allow the TOSA  108  to be operated. 
         [0034]    Within the body of the header  111 , some or all of the leads  130  are conductively attached to components, such as a laser, a TEC, controlling circuitry, and the like. Most or all of the TOSA  108  components may be located on or near an internal face of the end wall of the header  111 . Thus, for example, the end wall and the end face  113  may receive relatively more thermal energy generated by the TOSA  108  components than other portions of the header  111 . Thermal energy from the end wall and nearby portions of the header  111  may flow to the base  121  of the cap  120 . From there, thermal energy may flow to the extension  126 . 
         [0035]    In some embodiments, portions of the cap  120 , such as the base  121 , may be located relatively closer to the source of heat within the header  111  relative to conventional heat transfer devices. Furthermore, the cap  120  may exhibit a relatively large area of contact to the end face  113  and sides of the header  111 , which may encourage a relatively high rate of heat transfer from the header  111  to the cap  120  via conduction. 
         [0036]    With reference to  FIGS. 1B-1C and 2A-2C , the pad  124  may be shaped to contact both the shell  104  and the extension  126  of the cap  120  and thermal energy may transfer conductively from the extension  126  of the cap  120  to the shell  104  via the pad  124 . Compressing the pad  124  may reduce or eliminate air-filled gaps, which may inhibit the transfer of thermal energy, between the pad  124  and the cap  120  and/or the shell  104 . 
         [0037]    The pad  124  may facilitate a relatively more efficient thermally-conductive connection between the cap  120  and the shell  104  than direct contact between the cap  120  and shell  104 . For example, direct contact between the cap  120  and the shell  104  may be imperfect and may result in air-filled gaps between the cap  120  and the shell  104 . Alternately or additionally, direct contact between the cap  120  and the shell  104  may cause deviations in the thermal conductivity exhibited by the connection when the optoelectronic module  100  is subjected to movement. In some embodiments, the pad  124  may be omitted. For example, direct contact may be made between the cap  120  and the shell  104 . 
         [0038]    In some embodiments, the configuration of the thermal interface  118  may facilitate a floating OSA configuration of optoelectronic module  100 . Thus, for example, the TOSA  108  may not be overly mechanically restrained and may accommodate variations in connector dimensions, manufacturing tolerances, or the like. Alternately or additionally, the configuration of the thermal interface  118  may resist deviations in the thermal conductivity exhibited by the thermal interface  118  when the optoelectronic module  100  is subjected to movement. 
         [0039]    In some embodiments, the thermal interface  118  may facilitate a reduction of power consumption by the optoelectronic module  100 . In some embodiments, power consumption may be reduced by up to 26.4 milliwatts (mW). Alternately, power consumption may be reduced by more than 26.4 mW. Thus, for example, the thermal interface  118  may facilitate a reduction in yield loss. In some embodiments, the thermal interface  118  may be employed in communication modules having a high power transistor outline-can (TO-can) based OSA. 
         [0040]      FIG. 3  is an exploded perspective view of the cap  120  and the gasket  122 . Openings  125  formed in the cap  120  (described herein as “cap openings  125 ”) and corresponding openings  127  formed in the gasket  122  (described herein as “gasket openings  127 ”) may be configured to allow the leads  130  of the header  111 , (shown in  FIGS. 2A-2C ), to pass through the cap  120  and the gasket  122  such that the leads  130  may be soldered to the connector  116  ( FIGS. 1B-1C ). The gasket  122  may be attached to the cap  120  via an adhesive  123 , such as an adhesive tape, an epoxy, or the like. Alternately, the gasket  122  may be attached to the cap  120  by other means. The gasket  122  may be attached to the cap  120  such that the gasket openings  127  are positioned over the cap openings  125 . In some embodiments, the gasket openings  127  and the cap openings  125  may be circular and may be substantially axially aligned. 
         [0041]    The gasket openings  127  may be relatively smaller than the cap openings  125 . With reference to  FIGS. 2A-2C and 3 , the relatively larger cap openings  125  may provide clearance for the leads  130  of the header  111 , such that the cap  120  may not contact one or more of the leads  130  and create an undesirable conductive connection between the cap  120  and the leads  130 . In some embodiments, the cap  120  may be configured to contact one or more of the leads  130  to create a particular conductive connection. For example, in some embodiments, the cap  120  may be conductively connected to a ground lead of the leads  130 . 
         [0042]    The relatively smaller gasket openings  127  and the position of the gasket  122  on the cap  120  may facilitate positioning the leads  130  in a desired position relative to the cap openings  125 . For example, the gasket  122  may be attached to the cap  120  such that each of the gasket openings  127  may be approximately centered relative to one of the cap openings  125 . Thus, for example, when the leads  130  are located within the gasket openings  127 , the leads  130  may be located approximately in the center of the cap openings  125 . 
         [0043]    As may be best seen in  FIGS. 2A-2C , the assembled cap  120  and gasket  122  may be positioned on the header  111  by inserting the leads  130  into the openings formed in the gasket  122  and sliding the assembled cap  120  and gasket  122  into place. In some embodiments, the fingers  128  and/or the extension  126  may be soldered to the header  111 . For example, each side along the length of each of the fingers  128  may be soldered to the header  111 . Alternately or additionally, both sides of the extension  126  may be soldered to the header  111  where the extension  126  is near or in contact with the header  111 . 
         [0044]      FIG. 4  is an exploded perspective view of the TOSA  108 , the cap  120 , the gasket  122 , the PCB  110 , and the connector  116 . In some embodiments, the connector  116  may be soldered to the PCB  110  as a step in the assembly process. In some embodiments, the assembled TOSA  108 , cap  120 , and gasket  122  may be soldered to the assembled connector  116  and PCB  110  at a subsequent step. The gasket  122  may discourage the connector  116  from making a conductive connection with the cap  120 . In some embodiments, the gasket  122  may facilitate a particular conductive connection between the connector  116  and the cap  120 . For example, a ground of the connector  116  may form a conductive connection with the cap  120 . 
         [0045]    As may be best seen in  FIGS. 1A-1C , the assembled TOSA  108  and PCB  110  may be positioned and secured relative to the shell  104  and the pad  124 . Other components, such as the ROSA  109 , the latch mechanism  114 , and the shell cover  106  may also be positioned and secured relative to the shell  104  to form the assembled optoelectronic module  100 .