US20210084746A1 - Secondary side heatsink techniques for optical and electrical modules - Google Patents
Secondary side heatsink techniques for optical and electrical modules Download PDFInfo
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- US20210084746A1 US20210084746A1 US16/571,722 US201916571722A US2021084746A1 US 20210084746 A1 US20210084746 A1 US 20210084746A1 US 201916571722 A US201916571722 A US 201916571722A US 2021084746 A1 US2021084746 A1 US 2021084746A1
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- heatsink
- secondary side
- module
- primary side
- circuit board
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K1/00—Printed circuits
- H05K1/02—Details
- H05K1/0201—Thermal arrangements, e.g. for cooling, heating or preventing overheating
- H05K1/0203—Cooling of mounted components
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K1/00—Printed circuits
- H05K1/02—Details
- H05K1/0201—Thermal arrangements, e.g. for cooling, heating or preventing overheating
- H05K1/0203—Cooling of mounted components
- H05K1/021—Components thermally connected to metal substrates or heat-sinks by insert mounting
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K1/00—Printed circuits
- H05K1/18—Printed circuits structurally associated with non-printed electric components
- H05K1/181—Printed circuits structurally associated with non-printed electric components associated with surface mounted components
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K7/00—Constructional details common to different types of electric apparatus
- H05K7/20—Modifications to facilitate cooling, ventilating, or heating
- H05K7/2039—Modifications to facilitate cooling, ventilating, or heating characterised by the heat transfer by conduction from the heat generating element to a dissipating body
- H05K7/205—Heat-dissipating body thermally connected to heat generating element via thermal paths through printed circuit board [PCB]
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K2201/00—Indexing scheme relating to printed circuits covered by H05K1/00
- H05K2201/06—Thermal details
- H05K2201/066—Heatsink mounted on the surface of the PCB
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K2201/00—Indexing scheme relating to printed circuits covered by H05K1/00
- H05K2201/10—Details of components or other objects attached to or integrated in a printed circuit board
- H05K2201/10007—Types of components
- H05K2201/10121—Optical component, e.g. opto-electronic component
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K2201/00—Indexing scheme relating to printed circuits covered by H05K1/00
- H05K2201/10—Details of components or other objects attached to or integrated in a printed circuit board
- H05K2201/10007—Types of components
- H05K2201/10189—Non-printed connector
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K2201/00—Indexing scheme relating to printed circuits covered by H05K1/00
- H05K2201/10—Details of components or other objects attached to or integrated in a printed circuit board
- H05K2201/10227—Other objects, e.g. metallic pieces
- H05K2201/10265—Metallic coils or springs, e.g. as part of a connection element
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K2201/00—Indexing scheme relating to printed circuits covered by H05K1/00
- H05K2201/10—Details of components or other objects attached to or integrated in a printed circuit board
- H05K2201/10227—Other objects, e.g. metallic pieces
- H05K2201/10409—Screws
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K2201/00—Indexing scheme relating to printed circuits covered by H05K1/00
- H05K2201/10—Details of components or other objects attached to or integrated in a printed circuit board
- H05K2201/10227—Other objects, e.g. metallic pieces
- H05K2201/10416—Metallic blocks or heatsinks completely inserted in a PCB
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K2201/00—Indexing scheme relating to printed circuits covered by H05K1/00
- H05K2201/10—Details of components or other objects attached to or integrated in a printed circuit board
- H05K2201/10613—Details of electrical connections of non-printed components, e.g. special leads
- H05K2201/10621—Components characterised by their electrical contacts
- H05K2201/10734—Ball grid array [BGA]; Bump grid array
Definitions
- the present disclosure generally relates to cooling via heatsinks of electrical and optical hardware. More particularly, the present disclosure relates to systems and methods for a secondary side heatsink for optical and electrical modules.
- Thermal management i.e., cooling to dissipate heat
- hardware includes electrical and/or optical components that are mounted on a Printed Circuit Board Assembly (PCBA).
- PCBA Printed Circuit Board Assembly
- Networking, computing, and/or storage devices are formed via hardware modules which include the PCBA and which are typically engaged in a chassis, shelf, or the like, i.e., a hardware platform.
- a hardware module, or simply a module may also be referred to as a circuit pack, a line module, a blade, etc. Modules are getting increasingly more powerful along with the PCBA design becoming significantly more complex and densely packed.
- a PCBA can have a primary side where the bulk of optical and electrical components are mounted and a secondary side opposite the primary side.
- the secondary side is space-constrained relative to the primary side, specifically in a vertical direction. Further, as component placement is limited, there are techniques where components are being mounted on the secondary side.
- thermal management in a hardware platform, including heatsinks, heat spreaders, airflow (fans), etc. Heatsinks or heat spreaders require real estate which is at a premium on high density modules.
- the airflow is fixed based on a type of hardware platform.
- thermal management improvements including thermal management on the secondary side.
- a module for use in a hardware platform for networking, computing, and/or storage includes a printed circuit board assembly having a primary side and a secondary side, wherein the primary side includes more physical space, in a vertical direction extending out from the printed circuit board assembly, than the secondary side; electrical and/or optical components disposed on the primary side of the printed circuit board assembly; and a secondary side heatsink located on and extending from the secondary side, wherein the secondary side heatsink is disposed to one of i) an electrical and/or optical component disposed on the secondary side, and ii) an optical component disposed on the primary side, for thermal management.
- the primary side can include interface components for connectivity to data and/or power connections in the hardware platform.
- the secondary side heatsink can be a floating heatsink disposed to the electrical and/or optical component disposed on the secondary side.
- the electrical and/or optical component disposed on the secondary side can be a Ball Grid Array (BGA) component.
- BGA Ball Grid Array
- the floating heatsink can be connected through the printed circuit board assembly to the primary side via a compact wave spring.
- the secondary side heatsink can be a coin-style heatsink that extends through the printed circuit board assembly to the optical component disposed on the primary side.
- the coin-style heatsink can have an adjustable height on the secondary side.
- the coin-style heatsink can have an adjustable height on the secondary side via set screws and cylindrical posts.
- the optical component disposed on the primary side can be a pluggable module.
- the module can further include a cage disposed on the primary side, for the optical component, wherein a hole is located in the printed circuit board assembly where the secondary side heatsink is able to contact the pluggable module.
- the secondary side heatsink can be a coin-style heatsink that protrudes from the secondary side to the optical component.
- the module can further include a primary side heatsink for the optical component, wherein the primary side heatsink is fixedly attached at one pivot point and attached to a faceplate at an opposite point via spring tabs.
- a printed circuit board assembly for use in a module or circuit pack in a hardware platform for networking, computing, and/or storage includes a primary side and a secondary side, wherein the primary side includes more physical space, in a vertical direction extending out from the printed circuit board assembly, than the secondary side; electrical and/or optical components disposed on the primary side; and a secondary side heatsink located on and extending from the secondary side, wherein the secondary side heatsink is disposed to one of i) an electrical and/or optical component disposed on the secondary side, and ii) an optical component disposed on the primary side, for thermal management.
- the primary side can include interface components for connectivity to data and/or power connections in the hardware platform.
- the secondary side heatsink can be a floating heatsink disposed to the electrical and/or optical component disposed on the secondary side.
- the secondary side heatsink can be a coin-style heatsink that extends through the printed circuit board assembly to the optical component disposed on the primary side.
- the optical component disposed on the primary side can be a pluggable module.
- a method includes providing a module that includes a printed circuit board assembly having a primary side and a secondary side, wherein the primary side includes more physical space, in a vertical direction extending out from the printed circuit board assembly, than the secondary side, electrical and/or optical components disposed on the primary side of the printed circuit board assembly, and a secondary side heatsink located on and extending from the secondary side, wherein the secondary side heatsink is disposed to one of i) an electrical and/or optical component disposed on the secondary side, and ii) an optical component disposed on the primary side, for thermal management.
- the primary side can include interface components for connectivity to data and/or power connections in a hardware platform.
- the secondary side heatsink can be one of i) a floating heatsink disposed to the electrical and/or optical component disposed on the secondary side, and ii) a coin-style heatsink that extends through the printed circuit board assembly to the optical component disposed on the primary side.
- FIGS. 1A and 1B are perspective diagrams of an example module illustrating a primary side ( FIG. 1A ) and a secondary side ( FIG. 1B ).
- FIG. 2 is a side view diagram of the example module.
- FIGS. 3A and 3B are a top view ( FIG. 3A ) and a section view ( FIG. 3B ) of a conventional module with a floating heatsink on the primary side.
- FIGS. 4A and 4B are a top view ( FIG. 4A ) and a section view ( FIG. 4B ) of an example module having components on the secondary side.
- FIGS. 5A and 5B are a top view ( FIG. 5A ) and a section view ( FIG. 5B ) of an example module having components on the secondary side with a heatsink positioned on the space-restricted secondary side.
- FIGS. 6A and 6B are perspective diagrams of an example module illustrating a primary side ( FIG. 6A ) and a secondary side ( FIG. 6B ) with a coin-style heatsink that protrudes from the secondary side.
- FIGS. 7A and 7B are a top view ( FIG. 7A ) and a section view ( FIG. 7B ) of the example module illustrating the coin-style heatsink that protrudes from the secondary side.
- FIGS. 8A and 8B are a top view ( FIG. 8A ) and a section view ( FIG. 8B ) of the example module illustrating the coin-style heatsink from another section relative to FIG. 7B .
- FIGS. 9A and 9B are a top view ( FIG. 9A ) and a section view ( FIG. 9B ) of a conventional module illustrating a conventional inset copper coin heatsink.
- FIGS. 10A and 10B are a top view ( FIG. 10A ) and a section view ( FIG. 10B ) of a conventional module illustrating a conventional adhesive copper coin heatsink.
- FIGS. 11A-11E are diagrams of example module supporting two example pluggable modules and illustrating a perspective of a primary side of the module ( FIG. 11A ), a perspective of a secondary side of the module ( FIG. 11B ), a top view of the secondary side of the module ( FIG. 1C ), a front view of the module ( FIG. 11D ), and a side view of the module ( FIG. 11E ).
- FIGS. 12A-12D are diagrams of the example module illustrating steps in a process for heatsink mounting, heatsink alignment, heatsink pivoting and springing, in corresponding cages for the pluggable modules.
- the present disclosure relates to systems and methods for a secondary side heatsink for optical and electrical modules.
- the systems and methods include a floating secondary side heatsink/heat spreader.
- the systems and methods include a height-adjustable secondary side heatsink.
- the systems and methods include secondary side thermal management techniques.
- the systems and methods contemplate use in high density modules including pluggable optical and electrical modules and especially with space restricted PCBAs.
- FIGS. 1A and 1B are perspective diagrams of an example module 10 illustrating a primary side 12 ( FIG. 1A ) and a secondary side 14 ( FIG. 1B ).
- FIG. 2 is a side view diagram of the example module 10 .
- FIGS. 3A and 3B are a top view ( FIG. 3A ) and a section view ( FIG. 3B ) of a conventional module 10 A with a floating heatsink 20 on the primary side 12 .
- FIGS. 4A and 4B are a top view ( FIG. 4A ) and a section view ( FIG. 4B ) of an example module 10 B having components on the secondary side 14 .
- FIGS. 5A and 5B are a top view ( FIG. 5A ) and a section view ( FIG. 5B ) of an example module 10 C having components on the secondary side 14 with a heatsink 20 positioned on the space-restricted secondary side 14 .
- the modules 10 , 10 A, 10 B, 10 C are used in a hardware platform to implement some functionality.
- the modules 10 , 10 A, 10 B, 10 C can include various optical and/or electrical components on a PCBA 18 that includes the primary side 12 and the secondary side 14 .
- the primary side 12 has more space, i.e., real estate than the secondary side 14 . Accordingly, higher height components, including thermal management components are typically placed on the primary side 12 , as in FIGS. 1A, 1B, and 2 .
- the modules 10 , 10 A, 10 B, 10 C include interface components 16 that are configured to connect to a backplane, midplane, etc. for data and/or power connections in the hardware platform.
- the modules 10 , 10 A, 10 B, 10 C can slot into the backplane of the hardware platform, and the primary side 12 can be the one where the interface components 16 extend from.
- the labeling of the primary side 12 and the secondary side 14 can be arbitrary based on which side has more space.
- Modules and circuit packs such as the modules 10 , 10 A, 10 B, 10 C, are getting increasingly more powerful and the PCBA 18 design significantly more complex and densely packed. As a result, thermal powers are also increasing, and the component placement locations are limited.
- some high power Ball Grid Array (BGA) components 22 (or other types of components) are being placed on the secondary side 14 of the PCBA 18 .
- BGA Ball Grid Array
- prior art placement of the BGA components 22 on the primary side 12 is illustrated in FIGS. 3A and 3B
- placement of the BGA components 22 on the secondary side 14 is illustrated in FIGS. 4A, 4B, 5A, and 5B .
- the placement of the BGA components 22 on the secondary side 14 is where vertical space is limited, especially on conventional circuit packs, such as the modules 10 , 10 A, 10 B, 10 C.
- Such components 22 require floating heatsinks 20 that apply a consistent, uniform spring force across the top of the component 22 in order to maintain sufficient contact across the thermal interface and dissipate heat from the component 22 .
- conventional techniques of applying spring force take up too much vertical height 24 as illustrated in FIG. 3B .
- the vertical height 24 in FIG. 3B on the primary side 12 is not available on the secondary side 14 of the module 10 , 10 A, 10 B PCBA 18 , as illustrated in FIGS. 4B and 5B .
- the spring force is provided via shoulder screws 26 and a coil spring 28 that are screwed into a thread fastener in the PCBA 18 , as illustrated in FIG. 3B .
- the shoulder screw 26 passes through a clearance hole in the PCBA 18 and screws into the heatsink 20 or heat spreader itself, as illustrated in FIG. 4B . This allows for the spring force to be applied to the component using the shoulder screws 26 and the coil spring 28 within the space constraints of the secondary side 14 .
- FIG. 4B occupies significant real estate 32 on the primary side 12 of the PCBA 18 which could ideally be accommodated by heatsinks 20 , components 22 , removable (pluggable) modules, etc. That is, the approach in FIG. 4B wastes the real estate 32 on the primary side 12 .
- This approach in FIG. 4B is difficult to implement in the module 10 as it reduces density on the primary side 12 .
- the volume that would typically be needed for the shoulder screws 26 and coil springs 28 needs to be occupied by other components 22 and heatsinks 20 , or removable modules instead. In this scenario, a more compact option is presented herein in FIG. 5B .
- the present disclosure includes a heatsink 20 or heat spreader positioned on a PCBA 18 component 22 on the space-restricted secondary side 14 of the PCBA 18 that floats and is sprung in such a way as that sufficient normal force is consistently applied to the component 22 , while doing so within the restricted space afforded on the secondary side 14 of a PCBA 18 only, without the use of overly large shoulder screws 26 and coil springs 28 on the primary side 12 , as is illustrated in FIG. 3B .
- the present disclosure makes use of a heatsink 20 or heat spreader with a recessed cylindrical inset mounting point 34 which houses a compact wave spring 36 and a custom shoulder nut 38 that rests on top of the wave spring 36 .
- This is held to the circuit pack assembly with a screw 40 from the primary side 12 which connects to the shoulder nut 38 by way of a through hole 42 in the PCBA 18 .
- the wave spring 36 has the advantage of applying a proportionally more spring force per amount of spring deflection than a conventional coil spring 28 , thus saving significant amounts of space 46 on the primary side 12 of the PCBA 18 .
- the approach in FIG. 5B allows a heatsink 20 or heat spreader that is floating under spring force in order to dissipate the heat of a higher power component 22 on the secondary side 14 of the PCBA 18 of a circuit pack 10 .
- a heatsink 20 or heat spreader that is floating under spring force in order to dissipate the heat of a higher power component 22 on the secondary side 14 of the PCBA 18 of a circuit pack 10 .
- some of these higher power devices 22 must be placed on the PCBA 18 secondary side 14 , without sufficient space on the primary side 12 to use a floating approach, necessitating this disclosure.
- the spring mechanism which includes the wave spring 36 , the mounting point 34 , and the shoulder nut 38 to the secondary side 14 , so the entire floating heatsink 20 is effectively moved to the secondary side 14 within the available volume envelope while still providing the same level of normal force and heatsink performance as a conventional approach ( FIGS. 3B and 4B ).
- FIGS. 6A and 6B are perspective diagrams of an example module 100 illustrating a primary side 12 ( FIG. 6A ) and a secondary side 14 ( FIG. 6B ) with a coin-style heatsink 102 that protrudes from the secondary side 14 .
- FIGS. 7A and 7B are a top view ( FIG. 7A ) and a section view ( FIG. 7B ) of the example module 100 illustrating the coin-style heatsink 102 that protrudes from the secondary side 14 .
- FIGS. 8A and 8B are a top view ( FIG. 8A ) and a section view ( FIG. 8B ) of the example module 100 illustrating the coin-style heatsink 102 from another section relative to FIG. 7B .
- FIGS. 10A and 10B are a top view ( FIG. 9A ) and a section view ( FIG. 9B ) of a conventional module 100 A illustrating a inset copper coin heatsink 124 .
- FIGS. 10A and 10B are a top view ( FIG. 10A ) and a section view ( FIG. 10B ) of a conventional module 100 B illustrating a conventional adhesive copper coin heatsink 106 .
- the modules 10 , 10 A, 10 B, 10 C may be circuit packs, line modules, etc. while the modules 100 , 100 A, 100 B may be smaller such as pluggable modules, daughter boards, etc.
- the floating heatsink 20 described with respect to the modules 10 , 10 C may be used with the modules 100 , 100 A, 100 B and the height-adjustable heatsink 102 in the modules 100 may be used with respect to the modules 10 , 10 A, 10 B, 10 C.
- the present disclosure includes the coin-style heatsink 102 that protrudes from the secondary side 14 of a PCBA 18 to heatsink 102 an optical device 110 on the primary side 12 of the PCBA 18 .
- the coin-style heatsink 102 protrudes through a hole 112 in the PCBA 18 to make contact with the optical device 110 through a thermal interface 114 .
- Its contact surface located at the thermal interface 114 is height adjustable using two set screws 116 in the coin style heatsink 102 and two cylindrical posts 118 mounted to the PBCA 18 secondary side 14 .
- the height adjustment is a necessity due to PCB thickness tolerances being +/ ⁇ 10%.
- the coin-style heatsink 102 is adjustable to various PCBA 18 thicknesses by using the adjustable set screws 116 that interface with the cylindrical post 118 on the secondary side 14 of the PCBA 18 to hold the contact surface of the coin-style heatsink 102 at the correct distance for thermal interface 114 spacing with the primary side 12 and the optical device 110 mounted there. By doing so, this allows the heatsink 102 to make proper thermal contact with the optical device 110 , through the single thermal interface 114 , regardless of manufacturing tolerance on PCBA 18 thickness, reducing PCBA 18 complexity by removing the need for embedded copper coins 120 ( FIG. 9B ).
- adjustable set screws 116 that interface with the cylindrical posts 118 are an example of an adjustable mechanical interface for adjusting the height of the heatsink 102 .
- Other approaches are also contemplated.
- an inset copper coin 120 would be required in the PCBA ( FIG. 9B ), which is a complex and costly option.
- the embedded coin 120 solution requires two thermal interfaces 122 between the optical device 120 and a heatsink 124 on the secondary side 14 of the PCBA 18 .
- the heatsink 124 is typically secured to the embedded coin 120 via screws 126 and PEMs 128 .
- a secondary option would be to produce a similar coin-style heatsink 130 , as illustrated in FIG. 10B , and adhere it to the optical device 110 through a hole 132 in the PCBA 18 with adhesive 134 .
- the embedded copper coin 120 in FIG. 9B is complicated, and there are many manufacturing issues that need to be considered to properly fabricate. This is costly and complex, and lower PCBA yields may also be present as a result. Additionally, two thermal interfaces 122 are required between the optical device 110 and its heatsink 124 , reducing heatsink 124 performance.
- the adhesive 134 coin style heatsink 130 option in FIG. 10B is simple, but has risks, as the adhesive 134 may fail over time, causing the heatsink 130 to fall off, potentially damaging the module 100 B or PCBA 18 . There is also potential to damage the sensitive optical device 110 during handling since the heatsinks' 130 only mechanical connection is direct to the underside of the optical device 110 via adhesive 134 instead of a stronger connection to the PCBA 18 as with the approach of FIGS. 6-8 .
- the present disclosure removes the need for a PCBA imbedded coin 120 by allowing a coin-style heatsink's 102 contact surface at the thermal interface 114 to be height adjustable to make proper thermal contact with the base of the optical device 110 on the primary side 12 of the PCBA 18 .
- the coin-style heatsink's 102 positions can be accurately set without the need for problematic adhesives 134 .
- thermal interface materials with better thermal conductivity can be used, increasing the heatsink 102 performance.
- FIGS. 11A-11E are diagrams of example module 200 supporting two example pluggable modules 202 A, 202 B and illustrating a perspective of a primary side 12 of the module 200 ( FIG. 11A ), a perspective of a secondary side 14 of the module 200 ( FIG. 11B ), a top view of the secondary side 14 of the module 200 ( FIG. 11C ), a front view of the module 200 ( FIG. 11D ), and a side view of the module 200 ( FIG. 11E ).
- FIGS. 12A-12D are diagrams of the example module 200 illustrating steps in a process for heatsink mounting, heatsink alignment, heatsink pivoting and springing, in corresponding cages 204 A, 204 B for the pluggable modules 202 A, 202 B.
- the pluggable module 202 is a CFP2-DCO module (C Small Form Factor Pluggable Digital Coherent Optics).
- CFP2-DCO C Small Form Factor Pluggable Digital Coherent Optics
- other types of pluggable optical modules are also contemplated, such as, for example, CFP, CFP2, CFP4, QSFP, QSFP2, QSFP-DD, etc.
- CFP2-DCO is described in OIF IA #OIF-CFP2-DCO-01.0 “Implementation Agreement for CFP2-Digital Coherent Optics Module,” Oct. 17, 2018, the contents of which are incorporated herein by reference.
- the present disclosure provides techniques to address the thermal management of a higher power module (e.g., the CFP2-DCO) where primary side 12 and secondary side 14 heatsink fin height must be quite limited.
- a higher power module e.g., the CFP2-DCO
- MSA Multi-Source Agreement
- transmission platforms continue to increase power densities with every generation of products.
- the temperature of a pluggable module 202 must be kept to 70 deg. C or below otherwise it will not function correctly.
- the above density increases are pushing the thermal profile of these optical modules 202 much higher than what the MSA originally intended to support.
- the needed enhanced thermal management is achieved by modifying an MSA standard CFP2 cage 204 to allow for the addition of direct pluggable module heatsinking from the secondary side 14 of the module 200 and through to the secondary side 14 of the PCBA 18 .
- the present disclosure provides a broad array of thermal management techniques which make use of the available space on space constricted areas and/or the secondary side 14 of a pluggable module 202 , and/or the secondary side 14 of the PCBA 18 itself.
- the various thermal management techniques described herein make novel use of available, but limited space within an assembly, to fully optimize thermal management by leveraging all possible available space to do so.
- component and piece part density on the primary side 12 of assemblies (the PCBA 18 ) and/or pluggable modules 202 are in some cases becoming extremely space limited, making thermal management a significant challenge, which is driving innovation of enhanced heatsinking techniques.
- the present disclosure includes techniques for heatsink mounting, heatsink alignment, heatsink pivoting and springing to ensures the pluggable module 202 has the necessary surface contact to both the primary side 12 and secondary side 14 heatsinks while inserted. It also ensures the forces needed to insert and remove the pluggable module 202 are within acceptable limits.
- the present disclosure includes cutting a hole 210 through the MSA standard CFP2 cage 204 and PCB 18 to access the pluggable module 202 from the secondary side 14 of the PCBA 18 ( FIGS. 11B, 11C, 12A ), for a secondary side heatsink 212 .
- the coin heatsink 102 in the PCBA 18 could be used to bring the heat out to the secondary side heatsink 212 while minimizing thermal resistance.
- the hole 210 allows access to the pluggable module 202 from the secondary side 14 of the PCBA 18 or PCB coin. This hole 210 allows the use of additional heatsinking from the secondary side 14 of the PCBA 18 . Normally no heatsinking at all is possible from the secondary side 14 when using MSA standard cages. This will allow further cooling of the pluggable module 202 to aid in keeping it within its operational temperature limits
- the present disclosure includes mounting a spring-loaded secondary heatsink 212 to ensure appropriate insertion forces during the pluggable module 202 insertion and to provide good contact at full insertion.
- the present disclosure further includes mounting a primary side heatsink 214 using external force and pivot point to ensure appropriate insertion forces during the pluggable module 202 insertion and to provide good contact at full insertion.
- the goal is to apply a uniform and controlled force against the module 202 .
- the conventional approach is to use the available clip-system provided by the cage manufacturer.
- the present disclosure makes use of force points external to the cage 204 in a manner which ensures the load is uniform and controlled between CFP2-DCO module 202 and the adjacent heat sinks. This could include four spring points positioned approximately adjacent to each of the four corners of the module 202 .
- This particular feature at the faceplate minimizes the footprint on the PCBA 18 .
- this external force and pivot point can be used with or without the hole 210 for the secondary side heatsink 212 .
- the heatsink mounts in such a way that the pluggable module 202 will slide into the cage 204 and slide up against the primary side only heatsink during insertion and have good contact between the module 202 and the heatsink once fully inserted.
- the MSA required insertion force, and the contact specifications must be respected.
- the module rather than sliding between cage bottom and primary side heatsink 214 , will now slide up against both the primary and secondary side heatsinks 214 , 212 .
- a pivot point mounting approach is used. The pivot point is towards the center of the primary side heatsink 214 and allows for easy insertion (normal insertion force) at the beginning of the insertion and enough and appropriate contact to both the primary and secondary side heatsinks 214 , 212 once the module 202 is fully inserted. That is, the present disclosure supports heatsinks 212 , 214 on both sides of the pluggable module 202 while conforming to MSA standards.
- FIGS. 12A-12D illustrate the steps in a process for heatsink mounting, heatsink alignment, heatsink pivoting, and springing.
- the holes 210 are included in the cages 204 and through the PCBA 18 .
- Standoffs 220 are installed through mounting holes from the secondary side 14 of the module 202 .
- Washers 222 are placed over the standoffs 220 from the primary side 12 , along with springs 224 and nuts 226 .
- the heatsink 212 is placed over the hole 210 and screwed in place with screws 228 that attach to the standoffs 220 .
- faceplate support rails 230 are installed utilizing screws 232 and washers 234 .
- a support rail 236 is installed by aligning tabs with grooves on the rails 230 .
- the primary heatsinks 214 are screwed in place with screws 240 and springs 242 .
- a faceplate 250 is installed utilizing screws 252 , 254 .
- a module 10 , 100 , 200 , 202 for use in a hardware platform for networking, computing, and/or storage includes a printed circuit board assembly 18 having a primary side 12 and a secondary side 14 , wherein the primary side 12 includes more physical space, in a vertical direction, extending out from the printed circuit board assembly 18 , than the secondary side 14 ; electrical and/or optical components 22 , 110 disposed on the primary side 12 of the printed circuit board assembly 18 ; and a secondary side heatsink 30 , 102 , 212 located on and extending from the secondary side 14 , wherein the secondary side heatsink 30 , 102 , 212 is disposed to one of i) an electrical and/or optical component 22 disposed on the secondary side 14 , and ii) an optical component 110 disposed on the primary side 12 , for thermal management.
- the primary side 12 includes interface components 16 for connection to data and/or power connections in the hardware platform.
- the secondary side heatsink 30 , 102 , 212 can be a floating heatsink 30 disposed to the electrical and/or optical component 22 disposed on the secondary side 14 .
- the electrical and/or optical component 22 disposed on the secondary side 14 is a Ball Grid Array (BGA) component.
- BGA Ball Grid Array
- the floating heatsink 30 is connected through the printed circuit board assembly to the primary side via a compact wave spring 36 .
- the secondary side heatsink 30 , 102 , 212 can be a coin-style heatsink 102 that extends through the printed circuit board assembly 18 to the optical component 110 disposed on the primary side 12 .
- the coin-style heatsink 102 has an adjustable height on the secondary side 14 .
- the module of claim 6 wherein the coin-style heatsink 102 has an adjustable height on the secondary side via set screws 116 and cylindrical posts 118 .
- the optical component disposed on the primary side can be a pluggable module 202 .
- the module can further include a cage 204 disposed on the primary side 12 , for the optical component, wherein a hole 210 is located in the printed circuit board assembly 18 where the secondary side heatsink 212 is able to contact the pluggable module 202 .
- the secondary side heatsink 212 is a coin-style heatsink that protrudes from the secondary side to the optical component.
- the module can further include a primary side heatsink 214 for the optical component, wherein the primary side heatsink is fixedly attached at one pivot point and attached to a faceplate at an opposite point via spring tabs.
Abstract
A module for use in a hardware platform for networking, computing, and/or storage includes a printed circuit board assembly having a primary side and a secondary side, wherein the primary side includes more physical space, in a vertical direction extending out from the printed circuit board assembly, than the secondary side; electrical and/or optical components disposed on the primary side of the printed circuit board assembly; and a secondary side heatsink located on and extending from the secondary side, wherein the secondary side heatsink is disposed to one of i) an electrical and/or optical component disposed on the secondary side, and ii) an optical component disposed on the primary side, for thermal management.
Description
- The present disclosure generally relates to cooling via heatsinks of electrical and optical hardware. More particularly, the present disclosure relates to systems and methods for a secondary side heatsink for optical and electrical modules.
- Thermal management, i.e., cooling to dissipate heat, is a challenge in networking hardware (as well as compute, storage, etc. hardware). The challenge is due to the ever-increasing capacity and density. As described herein, hardware includes electrical and/or optical components that are mounted on a Printed Circuit Board Assembly (PCBA). Networking, computing, and/or storage devices are formed via hardware modules which include the PCBA and which are typically engaged in a chassis, shelf, or the like, i.e., a hardware platform. A hardware module, or simply a module, may also be referred to as a circuit pack, a line module, a blade, etc. Modules are getting increasingly more powerful along with the PCBA design becoming significantly more complex and densely packed. As a result, thermal management requirements are increasing, and the component placement locations are limited. A PCBA can have a primary side where the bulk of optical and electrical components are mounted and a secondary side opposite the primary side. In this context, the secondary side is space-constrained relative to the primary side, specifically in a vertical direction. Further, as component placement is limited, there are techniques where components are being mounted on the secondary side.
- There are various techniques for thermal management in a hardware platform, including heatsinks, heat spreaders, airflow (fans), etc. Heatsinks or heat spreaders require real estate which is at a premium on high density modules. The airflow is fixed based on a type of hardware platform. There is a need for thermal management improvements, including thermal management on the secondary side.
- In an embodiment, a module for use in a hardware platform for networking, computing, and/or storage, includes a printed circuit board assembly having a primary side and a secondary side, wherein the primary side includes more physical space, in a vertical direction extending out from the printed circuit board assembly, than the secondary side; electrical and/or optical components disposed on the primary side of the printed circuit board assembly; and a secondary side heatsink located on and extending from the secondary side, wherein the secondary side heatsink is disposed to one of i) an electrical and/or optical component disposed on the secondary side, and ii) an optical component disposed on the primary side, for thermal management. The primary side can include interface components for connectivity to data and/or power connections in the hardware platform. The secondary side heatsink can be a floating heatsink disposed to the electrical and/or optical component disposed on the secondary side. The electrical and/or optical component disposed on the secondary side can be a Ball Grid Array (BGA) component. The floating heatsink can be connected through the printed circuit board assembly to the primary side via a compact wave spring.
- The secondary side heatsink can be a coin-style heatsink that extends through the printed circuit board assembly to the optical component disposed on the primary side. The coin-style heatsink can have an adjustable height on the secondary side. The coin-style heatsink can have an adjustable height on the secondary side via set screws and cylindrical posts. The optical component disposed on the primary side can be a pluggable module. The module can further include a cage disposed on the primary side, for the optical component, wherein a hole is located in the printed circuit board assembly where the secondary side heatsink is able to contact the pluggable module. The secondary side heatsink can be a coin-style heatsink that protrudes from the secondary side to the optical component. The module can further include a primary side heatsink for the optical component, wherein the primary side heatsink is fixedly attached at one pivot point and attached to a faceplate at an opposite point via spring tabs.
- In another embodiment, a printed circuit board assembly for use in a module or circuit pack in a hardware platform for networking, computing, and/or storage includes a primary side and a secondary side, wherein the primary side includes more physical space, in a vertical direction extending out from the printed circuit board assembly, than the secondary side; electrical and/or optical components disposed on the primary side; and a secondary side heatsink located on and extending from the secondary side, wherein the secondary side heatsink is disposed to one of i) an electrical and/or optical component disposed on the secondary side, and ii) an optical component disposed on the primary side, for thermal management. The primary side can include interface components for connectivity to data and/or power connections in the hardware platform. The secondary side heatsink can be a floating heatsink disposed to the electrical and/or optical component disposed on the secondary side. The secondary side heatsink can be a coin-style heatsink that extends through the printed circuit board assembly to the optical component disposed on the primary side. The optical component disposed on the primary side can be a pluggable module.
- In a further embodiment, a method includes providing a module that includes a printed circuit board assembly having a primary side and a secondary side, wherein the primary side includes more physical space, in a vertical direction extending out from the printed circuit board assembly, than the secondary side, electrical and/or optical components disposed on the primary side of the printed circuit board assembly, and a secondary side heatsink located on and extending from the secondary side, wherein the secondary side heatsink is disposed to one of i) an electrical and/or optical component disposed on the secondary side, and ii) an optical component disposed on the primary side, for thermal management. The primary side can include interface components for connectivity to data and/or power connections in a hardware platform. The secondary side heatsink can be one of i) a floating heatsink disposed to the electrical and/or optical component disposed on the secondary side, and ii) a coin-style heatsink that extends through the printed circuit board assembly to the optical component disposed on the primary side.
- The present disclosure is illustrated and described herein with reference to the various drawings, in which like reference numbers are used to denote like system components/method steps, as appropriate, and in which:
-
FIGS. 1A and 1B are perspective diagrams of an example module illustrating a primary side (FIG. 1A ) and a secondary side (FIG. 1B ). -
FIG. 2 is a side view diagram of the example module. -
FIGS. 3A and 3B are a top view (FIG. 3A ) and a section view (FIG. 3B ) of a conventional module with a floating heatsink on the primary side. -
FIGS. 4A and 4B are a top view (FIG. 4A ) and a section view (FIG. 4B ) of an example module having components on the secondary side. -
FIGS. 5A and 5B are a top view (FIG. 5A ) and a section view (FIG. 5B ) of an example module having components on the secondary side with a heatsink positioned on the space-restricted secondary side. -
FIGS. 6A and 6B are perspective diagrams of an example module illustrating a primary side (FIG. 6A ) and a secondary side (FIG. 6B ) with a coin-style heatsink that protrudes from the secondary side. -
FIGS. 7A and 7B are a top view (FIG. 7A ) and a section view (FIG. 7B ) of the example module illustrating the coin-style heatsink that protrudes from the secondary side. -
FIGS. 8A and 8B are a top view (FIG. 8A ) and a section view (FIG. 8B ) of the example module illustrating the coin-style heatsink from another section relative toFIG. 7B . -
FIGS. 9A and 9B are a top view (FIG. 9A ) and a section view (FIG. 9B ) of a conventional module illustrating a conventional inset copper coin heatsink. -
FIGS. 10A and 10B are a top view (FIG. 10A ) and a section view (FIG. 10B ) of a conventional module illustrating a conventional adhesive copper coin heatsink. -
FIGS. 11A-11E are diagrams of example module supporting two example pluggable modules and illustrating a perspective of a primary side of the module (FIG. 11A ), a perspective of a secondary side of the module (FIG. 11B ), a top view of the secondary side of the module (FIG. 1C ), a front view of the module (FIG. 11D ), and a side view of the module (FIG. 11E ). -
FIGS. 12A-12D are diagrams of the example module illustrating steps in a process for heatsink mounting, heatsink alignment, heatsink pivoting and springing, in corresponding cages for the pluggable modules. - The present disclosure relates to systems and methods for a secondary side heatsink for optical and electrical modules. In an embodiment, the systems and methods include a floating secondary side heatsink/heat spreader. In another embodiment, the systems and methods include a height-adjustable secondary side heatsink. In a further embodiment, the systems and methods include secondary side thermal management techniques. Variously, the systems and methods contemplate use in high density modules including pluggable optical and electrical modules and especially with space restricted PCBAs.
-
FIGS. 1A and 1B are perspective diagrams of anexample module 10 illustrating a primary side 12 (FIG. 1A ) and a secondary side 14 (FIG. 1B ).FIG. 2 is a side view diagram of theexample module 10.FIGS. 3A and 3B are a top view (FIG. 3A ) and a section view (FIG. 3B ) of aconventional module 10A with a floatingheatsink 20 on theprimary side 12.FIGS. 4A and 4B are a top view (FIG. 4A ) and a section view (FIG. 4B ) of anexample module 10B having components on thesecondary side 14.FIGS. 5A and 5B are a top view (FIG. 5A ) and a section view (FIG. 5B ) of anexample module 10C having components on thesecondary side 14 with aheatsink 20 positioned on the space-restrictedsecondary side 14. - Again, the
modules modules PCBA 18 that includes theprimary side 12 and thesecondary side 14. As described herein, theprimary side 12 has more space, i.e., real estate than thesecondary side 14. Accordingly, higher height components, including thermal management components are typically placed on theprimary side 12, as inFIGS. 1A, 1B, and 2 . In an embodiment, themodules interface components 16 that are configured to connect to a backplane, midplane, etc. for data and/or power connections in the hardware platform. For example, themodules primary side 12 can be the one where theinterface components 16 extend from. Of course, the labeling of theprimary side 12 and thesecondary side 14 can be arbitrary based on which side has more space. - Modules and circuit packs, such as the
modules PCBA 18 design significantly more complex and densely packed. As a result, thermal powers are also increasing, and the component placement locations are limited. In some instances, some high power Ball Grid Array (BGA) components 22 (or other types of components) are being placed on thesecondary side 14 of thePCBA 18. For example, prior art placement of theBGA components 22 on theprimary side 12 is illustrated inFIGS. 3A and 3B , whereas placement of theBGA components 22 on thesecondary side 14 is illustrated inFIGS. 4A, 4B, 5A, and 5B . The placement of theBGA components 22 on thesecondary side 14 is where vertical space is limited, especially on conventional circuit packs, such as themodules -
Such components 22 require floatingheatsinks 20 that apply a consistent, uniform spring force across the top of thecomponent 22 in order to maintain sufficient contact across the thermal interface and dissipate heat from thecomponent 22. However, conventional techniques of applying spring force take up too muchvertical height 24 as illustrated inFIG. 3B . Thevertical height 24 inFIG. 3B on theprimary side 12 is not available on thesecondary side 14 of themodule 10 B PCBA 18, as illustrated inFIGS. 4B and 5B . - There is a requirement to provide the spring force to the
heatsink 20. Conventionally, the spring force is provided via shoulder screws 26 and acoil spring 28 that are screwed into a thread fastener in thePCBA 18, as illustrated inFIG. 3B . Here, there is adequate space on theprimary side 12. When thecomponents 22 are on thesecondary side 14, as inFIG. 4B , instead of screwing into a thread fastener in thePCBA 18, theshoulder screw 26 passes through a clearance hole in thePCBA 18 and screws into theheatsink 20 or heat spreader itself, as illustrated inFIG. 4B . This allows for the spring force to be applied to the component using the shoulder screws 26 and thecoil spring 28 within the space constraints of thesecondary side 14. - The approach in
FIG. 4B occupies significantreal estate 32 on theprimary side 12 of thePCBA 18 which could ideally be accommodated byheatsinks 20,components 22, removable (pluggable) modules, etc. That is, the approach inFIG. 4B wastes thereal estate 32 on theprimary side 12. This approach inFIG. 4B is difficult to implement in themodule 10 as it reduces density on theprimary side 12. The volume that would typically be needed for the shoulder screws 26 andcoil springs 28 needs to be occupied byother components 22 andheatsinks 20, or removable modules instead. In this scenario, a more compact option is presented herein inFIG. 5B . - As illustrated in
FIG. 5B , the present disclosure includes aheatsink 20 or heat spreader positioned on aPCBA 18component 22 on the space-restrictedsecondary side 14 of thePCBA 18 that floats and is sprung in such a way as that sufficient normal force is consistently applied to thecomponent 22, while doing so within the restricted space afforded on thesecondary side 14 of aPCBA 18 only, without the use of overly large shoulder screws 26 and coil springs 28 on theprimary side 12, as is illustrated inFIG. 3B . - The present disclosure makes use of a
heatsink 20 or heat spreader with a recessed cylindricalinset mounting point 34 which houses acompact wave spring 36 and acustom shoulder nut 38 that rests on top of thewave spring 36. This is held to the circuit pack assembly with ascrew 40 from theprimary side 12 which connects to theshoulder nut 38 by way of a throughhole 42 in thePCBA 18. This results in only ascrew head 44 occupying space on theprimary side 12, which can be minimized by using a low-profile screw 40 head such as a wafer head. Thewave spring 36 has the advantage of applying a proportionally more spring force per amount of spring deflection than aconventional coil spring 28, thus saving significant amounts ofspace 46 on theprimary side 12 of thePCBA 18. - Advantageously, the approach in
FIG. 5B allows aheatsink 20 or heat spreader that is floating under spring force in order to dissipate the heat of ahigher power component 22 on thesecondary side 14 of thePCBA 18 of acircuit pack 10. As described herein, due to increasedPCBA 18 complexity andcomponent 22 density, some of thesehigher power devices 22 must be placed on thePCBA 18secondary side 14, without sufficient space on theprimary side 12 to use a floating approach, necessitating this disclosure. - In
FIG. 5B , the spring mechanism which includes thewave spring 36, the mountingpoint 34, and theshoulder nut 38 to thesecondary side 14, so the entire floatingheatsink 20 is effectively moved to thesecondary side 14 within the available volume envelope while still providing the same level of normal force and heatsink performance as a conventional approach (FIGS. 3B and 4B ). -
FIGS. 6A and 6B are perspective diagrams of anexample module 100 illustrating a primary side 12 (FIG. 6A ) and a secondary side 14 (FIG. 6B ) with a coin-style heatsink 102 that protrudes from thesecondary side 14.FIGS. 7A and 7B are a top view (FIG. 7A ) and a section view (FIG. 7B ) of theexample module 100 illustrating the coin-style heatsink 102 that protrudes from thesecondary side 14.FIGS. 8A and 8B are a top view (FIG. 8A ) and a section view (FIG. 8B ) of theexample module 100 illustrating the coin-style heatsink 102 from another section relative toFIG. 7B .FIGS. 9A and 9B are a top view (FIG. 9A ) and a section view (FIG. 9B ) of aconventional module 100A illustrating a insetcopper coin heatsink 124.FIGS. 10A and 10B are a top view (FIG. 10A ) and a section view (FIG. 10B ) of aconventional module 100B illustrating a conventional adhesive copper coin heatsink 106. - The
modules modules heatsink 20 described with respect to themodules modules adjustable heatsink 102 in themodules 100 may be used with respect to themodules - The present disclosure includes the coin-
style heatsink 102 that protrudes from thesecondary side 14 of aPCBA 18 to heatsink 102 anoptical device 110 on theprimary side 12 of thePCBA 18. The coin-style heatsink 102 protrudes through ahole 112 in thePCBA 18 to make contact with theoptical device 110 through athermal interface 114. Its contact surface located at thethermal interface 114 is height adjustable using two setscrews 116 in thecoin style heatsink 102 and twocylindrical posts 118 mounted to thePBCA 18secondary side 14. The height adjustment is a necessity due to PCB thickness tolerances being +/−10%. By implementing such aheatsink 102, expensive copper coins 120 (FIG. 9B ) are not required to be added to thePCBA 18 stack-up to allow for heat dissipation from thisprimary side 12optical devices 110. Note, theset screws 116 do not show up in the sectional drawing ofFIG. 7B , only due to the direction of the section; a different orientation of theset screws 116 may result in them showing up in this same sectional view. - The coin-
style heatsink 102 is adjustable tovarious PCBA 18 thicknesses by using theadjustable set screws 116 that interface with thecylindrical post 118 on thesecondary side 14 of thePCBA 18 to hold the contact surface of the coin-style heatsink 102 at the correct distance forthermal interface 114 spacing with theprimary side 12 and theoptical device 110 mounted there. By doing so, this allows theheatsink 102 to make proper thermal contact with theoptical device 110, through the singlethermal interface 114, regardless of manufacturing tolerance onPCBA 18 thickness, reducingPCBA 18 complexity by removing the need for embedded copper coins 120 (FIG. 9B ). - Note, the
adjustable set screws 116 that interface with thecylindrical posts 118 are an example of an adjustable mechanical interface for adjusting the height of theheatsink 102. Other approaches are also contemplated. - Conventionally, an
inset copper coin 120 would be required in the PCBA (FIG. 9B ), which is a complex and costly option. The embeddedcoin 120 solution requires twothermal interfaces 122 between theoptical device 120 and aheatsink 124 on thesecondary side 14 of thePCBA 18. Theheatsink 124 is typically secured to the embeddedcoin 120 viascrews 126 andPEMs 128. A secondary option would be to produce a similar coin-style heatsink 130, as illustrated inFIG. 10B , and adhere it to theoptical device 110 through ahole 132 in thePCBA 18 withadhesive 134. - The embedded
copper coin 120 inFIG. 9B is complicated, and there are many manufacturing issues that need to be considered to properly fabricate. This is costly and complex, and lower PCBA yields may also be present as a result. Additionally, twothermal interfaces 122 are required between theoptical device 110 and itsheatsink 124, reducingheatsink 124 performance. - The adhesive 134
coin style heatsink 130 option inFIG. 10B is simple, but has risks, as the adhesive 134 may fail over time, causing theheatsink 130 to fall off, potentially damaging themodule 100B orPCBA 18. There is also potential to damage the sensitiveoptical device 110 during handling since the heatsinks' 130 only mechanical connection is direct to the underside of theoptical device 110 via adhesive 134 instead of a stronger connection to thePCBA 18 as with the approach ofFIGS. 6-8 . - The present disclosure removes the need for a PCBA imbedded
coin 120 by allowing a coin-style heatsink's 102 contact surface at thethermal interface 114 to be height adjustable to make proper thermal contact with the base of theoptical device 110 on theprimary side 12 of thePCBA 18. By using setscrews 116 on theheatsink 102 interfacing with twoposts 118 on thesecondary side 14 of thePCBA 18, the coin-style heatsink's 102 positions can be accurately set without the need forproblematic adhesives 134. Additionally, thermal interface materials with better thermal conductivity can be used, increasing theheatsink 102 performance. -
FIGS. 11A-11E are diagrams ofexample module 200 supporting twoexample pluggable modules primary side 12 of the module 200 (FIG. 11A ), a perspective of asecondary side 14 of the module 200 (FIG. 11B ), a top view of thesecondary side 14 of the module 200 (FIG. 11C ), a front view of the module 200 (FIG. 11D ), and a side view of the module 200 (FIG. 11E ).FIGS. 12A-12D are diagrams of theexample module 200 illustrating steps in a process for heatsink mounting, heatsink alignment, heatsink pivoting and springing, in correspondingcages pluggable modules - In an embodiment and in the description herein, the pluggable module 202 is a CFP2-DCO module (C Small Form Factor Pluggable Digital Coherent Optics). Of course, other types of pluggable optical modules are also contemplated, such as, for example, CFP, CFP2, CFP4, QSFP, QSFP2, QSFP-DD, etc. For example, CFP2-DCO is described in OIF IA #OIF-CFP2-DCO-01.0 “Implementation Agreement for CFP2-Digital Coherent Optics Module,” Oct. 17, 2018, the contents of which are incorporated herein by reference.
- Conventional approaches to providing adequate thermal relief for CFP2 modules 202 is to provide large heatsinks, located on the
primary side 12 of themodule 200. Other approaches may include changing the airflow direction from side to side airflow over the module 202 to front to back airflow of the module 202. This can help provide cooler air over the module 202. Disadvantageously, these solutions require the availability of large physical areas around and behind the pluggable module cage 204 to provide large heatsinks which in most designs is not available due to the product density needed, e.g., on themodule 200, in the hardware platform, etc. As for changing from side to side airflow to front to back airflow is not possible on existing and established products and are not always accepted in some markets segments or go against current customer practices. That is, airflow is fixed in a hardware platform, and many customers require a certain direction airflow based on their deployment practices. - The present disclosure provides techniques to address the thermal management of a higher power module (e.g., the CFP2-DCO) where
primary side 12 andsecondary side 14 heatsink fin height must be quite limited. Technology consolidation is now allowing higher-powered coherent optical modules to fit into Multi-Source Agreement (MSA) standard form-factor pluggable optics module. In addition, transmission platforms continue to increase power densities with every generation of products. Typically, the temperature of a pluggable module 202 must be kept to 70 deg. C or below otherwise it will not function correctly. However, the above density increases are pushing the thermal profile of these optical modules 202 much higher than what the MSA originally intended to support. These changes make thermal management of the higher power optical modules 202 an increasing challenge and is driving the need for enhanced heatsinking techniques. - In an embodiment, the needed enhanced thermal management is achieved by modifying an MSA standard CFP2 cage 204 to allow for the addition of direct pluggable module heatsinking from the
secondary side 14 of themodule 200 and through to thesecondary side 14 of thePCBA 18. The present disclosure provides a broad array of thermal management techniques which make use of the available space on space constricted areas and/or thesecondary side 14 of a pluggable module 202, and/or thesecondary side 14 of thePCBA 18 itself. The various thermal management techniques described herein make novel use of available, but limited space within an assembly, to fully optimize thermal management by leveraging all possible available space to do so. As mentioned, component and piece part density on theprimary side 12 of assemblies (the PCBA 18) and/or pluggable modules 202 are in some cases becoming extremely space limited, making thermal management a significant challenge, which is driving innovation of enhanced heatsinking techniques. The present disclosure includes techniques for heatsink mounting, heatsink alignment, heatsink pivoting and springing to ensures the pluggable module 202 has the necessary surface contact to both theprimary side 12 andsecondary side 14 heatsinks while inserted. It also ensures the forces needed to insert and remove the pluggable module 202 are within acceptable limits. - The present disclosure includes cutting a
hole 210 through the MSA standard CFP2 cage 204 andPCB 18 to access the pluggable module 202 from thesecondary side 14 of the PCBA 18 (FIGS. 11B, 11C, 12A ), for asecondary side heatsink 212. Alternately, thecoin heatsink 102 in thePCBA 18 could be used to bring the heat out to thesecondary side heatsink 212 while minimizing thermal resistance. Thehole 210 allows access to the pluggable module 202 from thesecondary side 14 of thePCBA 18 or PCB coin. Thishole 210 allows the use of additional heatsinking from thesecondary side 14 of thePCBA 18. Normally no heatsinking at all is possible from thesecondary side 14 when using MSA standard cages. This will allow further cooling of the pluggable module 202 to aid in keeping it within its operational temperature limits - Also, the present disclosure includes mounting a spring-loaded
secondary heatsink 212 to ensure appropriate insertion forces during the pluggable module 202 insertion and to provide good contact at full insertion. - The present disclosure further includes mounting a
primary side heatsink 214 using external force and pivot point to ensure appropriate insertion forces during the pluggable module 202 insertion and to provide good contact at full insertion. The goal is to apply a uniform and controlled force against the module 202. The conventional approach is to use the available clip-system provided by the cage manufacturer. The present disclosure makes use of force points external to the cage 204 in a manner which ensures the load is uniform and controlled between CFP2-DCO module 202 and the adjacent heat sinks. This could include four spring points positioned approximately adjacent to each of the four corners of the module 202. Also, this could include two spring points 216 (per heat sink) adjacent to the rear corners, and one sprung line-contact 218 at the faceplate (this can also be called a spring line or spring gasket). This particular feature at the faceplate minimizes the footprint on thePCBA 18. Of note, this external force and pivot point can be used with or without thehole 210 for thesecondary side heatsink 212. - On MSA standard CFP2 cages 204, the heatsink mounts in such a way that the pluggable module 202 will slide into the cage 204 and slide up against the primary side only heatsink during insertion and have good contact between the module 202 and the heatsink once fully inserted. The MSA required insertion force, and the contact specifications must be respected.
- With the addition of the
secondary side heatsink 212, the module, rather than sliding between cage bottom andprimary side heatsink 214, will now slide up against both the primary andsecondary side heatsinks primary side heatsink 214 and allows for easy insertion (normal insertion force) at the beginning of the insertion and enough and appropriate contact to both the primary andsecondary side heatsinks heatsinks -
FIGS. 12A-12D illustrate the steps in a process for heatsink mounting, heatsink alignment, heatsink pivoting, and springing. InFIG. 12A , theholes 210 are included in the cages 204 and through thePCBA 18. Standoffs 220 are installed through mounting holes from thesecondary side 14 of the module 202. Washers 222 are placed over the standoffs 220 from theprimary side 12, along withsprings 224 and nuts 226. Theheatsink 212 is placed over thehole 210 and screwed in place withscrews 228 that attach to the standoffs 220. InFIG. 12B , faceplate support rails 230 are installed utilizingscrews 232 andwashers 234. Asupport rail 236 is installed by aligning tabs with grooves on therails 230. InFIG. 12C , theprimary heatsinks 214 are screwed in place withscrews 240 and springs 242. InFIG. 12D , afaceplate 250 is installed utilizingscrews - In an embodiment, a
module circuit board assembly 18 having aprimary side 12 and asecondary side 14, wherein theprimary side 12 includes more physical space, in a vertical direction, extending out from the printedcircuit board assembly 18, than thesecondary side 14; electrical and/oroptical components primary side 12 of the printedcircuit board assembly 18; and asecondary side heatsink secondary side 14, wherein thesecondary side heatsink optical component 22 disposed on thesecondary side 14, and ii) anoptical component 110 disposed on theprimary side 12, for thermal management. - The
primary side 12 includesinterface components 16 for connection to data and/or power connections in the hardware platform. Thesecondary side heatsink heatsink 30 disposed to the electrical and/oroptical component 22 disposed on thesecondary side 14. The electrical and/oroptical component 22 disposed on thesecondary side 14 is a Ball Grid Array (BGA) component. The floatingheatsink 30 is connected through the printed circuit board assembly to the primary side via acompact wave spring 36. - The
secondary side heatsink style heatsink 102 that extends through the printedcircuit board assembly 18 to theoptical component 110 disposed on theprimary side 12. The coin-style heatsink 102 has an adjustable height on thesecondary side 14. The module ofclaim 6, wherein the coin-style heatsink 102 has an adjustable height on the secondary side viaset screws 116 andcylindrical posts 118. - The optical component disposed on the primary side can be a pluggable module 202. The module can further include a cage 204 disposed on the
primary side 12, for the optical component, wherein ahole 210 is located in the printedcircuit board assembly 18 where thesecondary side heatsink 212 is able to contact the pluggable module 202. Thesecondary side heatsink 212 is a coin-style heatsink that protrudes from the secondary side to the optical component. The module can further include aprimary side heatsink 214 for the optical component, wherein the primary side heatsink is fixedly attached at one pivot point and attached to a faceplate at an opposite point via spring tabs. - Although the present disclosure has been illustrated and described herein with reference to preferred embodiments and specific examples thereof, it will be readily apparent to those of ordinary skill in the art that other embodiments and examples may perform similar functions and/or achieve like results. All such equivalent embodiments and examples are within the spirit and scope of the present disclosure, are contemplated thereby, and are intended to be covered by the following claims.
Claims (11)
1-20. (canceled)
21. A module for use in a hardware platform for networking, computing, and/or storage, the module comprising:
a printed circuit board assembly having a primary side and a secondary side, wherein the primary side includes more physical space, in a vertical direction extending out from the printed circuit board assembly, than the secondary side;
electrical and/or optical components disposed on the primary side of the printed circuit board assembly; and
a secondary side heatsink located on and extending from the secondary side, wherein the secondary side heatsink is disposed to one of the optical components disposed on the primary side, for thermal management,
wherein the secondary side heatsink is a coin-style heatsink that extends through the printed circuit board assembly to the one of the optical components disposed on the primary side, and wherein the coin-style heatsink has an adjustable height on the secondary side via set screws and cylindrical posts.
22. The module of claim 21 , wherein the primary side includes interface components for connectivity to data and/or power connections in the hardware platform.
23. The module of claim 21 , wherein the one of the optical components disposed on the primary side is a pluggable module.
24. The module of claim 23 , further comprising
a cage disposed on the primary side, for the optical component, wherein a hole is located in the printed circuit board assembly where the secondary side heatsink is able to contact the pluggable module.
25. The module of claim 23 , wherein the secondary side heatsink is a coin-style heatsink that protrudes from the secondary side to the optical component.
26. The module of claim 23 , further comprising
a primary side heatsink for the optical component, wherein the primary side heatsink is fixedly attached at one pivot point and attached to a faceplate at an opposite point via spring tabs.
27. A module for use in a hardware platform for networking, computing, and/or storage, the module comprising:
a printed circuit board assembly having a primary side and a secondary side, wherein the primary side includes more physical space, in a vertical direction extending out from the printed circuit board assembly, than the secondary side;
electrical and/or optical components disposed on the primary side of the printed circuit board assembly;
a secondary side heatsink located on and extending from the secondary side, wherein the secondary side heatsink is disposed to one of the optical components disposed on the primary side, for thermal management, wherein one of the optical components disposed on the primary side is a pluggable module; and
a primary side heatsink for the pluggable module, wherein the primary side heatsink is fixedly attached at one pivot point and attached to a faceplate at an opposite point via spring tabs.
28. The module of claim 27 , wherein the primary side includes interface components for connectivity to data and/or power connections in the hardware platform.
29. The module of claim 28 , further comprising
a cage disposed on the primary side, for the optical component, wherein a hole is located in the printed circuit board assembly where the secondary side heatsink is able to contact the pluggable module.
30. The module of claim 28 , wherein the secondary side heatsink is a coin-style heatsink that protrudes from the secondary side to the optical component.
Priority Applications (2)
Application Number | Priority Date | Filing Date | Title |
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US16/571,722 US10939536B1 (en) | 2019-09-16 | 2019-09-16 | Secondary side heatsink techniques for optical and electrical modules |
PCT/US2020/049852 WO2021055194A1 (en) | 2019-09-16 | 2020-09-09 | Secondary side heatsink techniques for optical and electrical modules |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
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US16/571,722 US10939536B1 (en) | 2019-09-16 | 2019-09-16 | Secondary side heatsink techniques for optical and electrical modules |
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US10939536B1 US10939536B1 (en) | 2021-03-02 |
US20210084746A1 true US20210084746A1 (en) | 2021-03-18 |
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WO (1) | WO2021055194A1 (en) |
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