Patent Publication Number: US-2023143331-A1

Title: Heat sink for a printed circuit board

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application is a continuation of U.S. patent application Ser. No. 17/487,817, filed on Sep. 28, 2021, which is a continuation of U.S. patent application Ser. No. 16/790,196, filed on Feb. 13, 2020, now U.S. Pat. No. 11,166,366, issued on Nov. 2, 2021, the entire contents of which are incorporated herein by reference. 
     STATEMENT RE: FEDERALLY SPONSORED RESEARCH/DEVELOPMENT 
     Not Applicable 
    
    
     BACKGROUND 
     1. Technical Field 
     The present disclosure relates generally to a heat sink for a printed circuit board, and a more specifically to a heat sink attachable to a memory module for dissipating heat from the memory module and also for stabilizing the memory module within a connector socket on a motherboard. 
     2. Description of the Related Art 
     Many computing systems include a motherboard, e.g., mainboard, main circuit board, system board, etc., that holds and facilitates communication between several critical electrical components included in the computing system. For instance, the motherboard may include a central processor, memory modules, interface connectors, i.e., input/output devices, and other components for general purposes use and applications. 
     A common memory module used in computer systems is a dual in-line memory module (DIMM) that is natively 64 bits\72 bits and 128 bits\144 bits to enable fast data transfer. A DIMM may include a module that includes one or several random-access memory (RAM) chips on a small circuit board with pins (e.g. 288 pins) that connect to a connector socket on the computer motherboard. Common standard DIMMs typically have a length of approximately 5.5 inches and a height of 1.18 inches and may include unbuffered DIMMs (UDIMMs), fully-buffered DIMMs (FB-DIMMs), registered DIMMS (RDIMMs), load-reduced DIMMs (LR-DIMMs), and non-volatile DIMMs (NV-DIMMs). Other standard heights for DIMMs may include, but are not limited to 0.738 inches, 0.900 inches, 1.000 inches, 1.230 inches, and 1.500 inches. Unbuffered DIMMs are used regularly in desktop and server computers and are configured such that commands may go directly from the memory controller residing in the CPU to the memory module. Fully-buffered DIMMS are commonly employed as the main memory in systems that require large capacities, such as servers and workstations. Registered DIMMs may also be referred to as buffered memory and may be used in servers and other applications that may require robustness and stability. RDIMMs may feature an onboard memory registers that are placed between the memory and the memory controller. The memory controller may buffer command, addressing and clock cycling, and may direct instructions to the dedicated memory registers rather than directly accessing the DRAM. Load-reduced DIMMs may use isolation memory buffer (iMB) technology that buffers the data and address lanes, which may reduce the load on the memory controller. The iMB chip may also buffer data signals and may isolate electrical loading, including data signals of the DRAM chips on the DIMM from the memory controller. Non-Volatile DIMMs may refer to a hybrid computer memory that retains data during a service outage. NVDIMMs may integrate non-volatile NAND flash memory with dynamic random access memory and dedicated backup power on a single memory subsystem. 
     The connector socket on the motherboard may be configured to receive a DIMM, and to that end, may include a channel which receives a portion of the DIMM. A corresponding pin connector may be located in the connector socket such that placement of the memory module into the connector socket creates an electrical connection between the memory module and the connector socket. When the memory module is received within the connector socket, a frictional engagement may be created between the memory module and the connector socket. Some connector sockets may include a locking tab which may be moved into engagement with the memory module when the memory module is inserted into the connector socket for providing additional securement between the memory module and the connector socket. 
     During operation of the motherboard, there may be several factors which may impact operation thereof. One factor may be heat generated by the memory module. If such heat is not dissipated, the buildup of heat may affect the operation of the memory module. Furthermore, in some environments, such as military environments, the motherboard may be subjected to extreme vibrations or movement. In such environments, the memory module may become disconnected from the connector socket, which may compromise the operability of the motherboard or one or more applications running thereon. 
     Accordingly, there is a need in the art for a device which may allow for heat dissipation from the memory module, while also assisting in securing the memory module to the connector socket. Various aspects of the present disclosure address this particular need, as will be discussed in more detail below. 
     BRIEF SUMMARY 
     Various aspects of the present disclosure are directed toward a heat sink for a memory module mountable in a connector socket. The heat sink may be configured to extend over the memory module to allow heat to be transferred from the memory module to the heat sink, preferably through a thermal interface material. The heat sink may also be configured to engage with the connector socket when the memory module is mounted therein to stabilize the memory module relative to the connector socket. The enhanced stabilization may be particularly useful in environments subject to vibrations, such as computers used in military applications. 
     In accordance with one embodiment of the present disclosure, there is provided a heat dissipating circuit board assembly for use with a socket having a socket body and a socket electrical connector. The circuit board assembly includes a heat sink having a first wall, a second wall spaced from the first wall, and an end wall extending between the first and second walls. The first wall, the second wall, and the end wall collectively define a cavity. The circuit board assembly additionally includes a printed circuit board having a circuit board electrical connector connectable with the socket electrical connector. The printed circuit board additionally includes a first face and a second face opposite the first face. The printed circuit board is located within the cavity such that the first wall of the heat sink extends over the first face and the second wall of the heat sink extends over the second face to allow heat to be transferred from the printed circuit board to the heat sink. The heat sink is configured to interface with the socket body when the circuit board electrical connector is connected to the socket electrical connector for stabilizing the printed circuit board relative to the socket. 
     The heat sink may include a flared end portion opposite the end wall. The first wall may include a first curved end portion and the second wall may include a second curved end portion, with the first and second curved end portions extending away from each other and collectively defining the flared end portion of the heat sink. An adhesive may be connected to the flared end portion for enhancing engagement between the heat sink and the socket. 
     The printed circuit board may include a pair of opposed lateral faces and a pair of notches extending from respective ones of the pair of opposed lateral faces. The heat sink may include a pair of intermediate edges, with each intermediate edge extending along a respective axis that overlaps a respective one of the pair of notches. Each intermediate edge may be located between a first end axis defined by the end wall and a second end axis defined by a terminal end of the first wall or a terminal end of the second wall. 
     The assembly may additionally include a clip connected to the heat sink and configured to apply a first force to the first wall and a second force to the second wall, with the second force being applied in a direction opposite to that of the first force. The heat sink may include a pair of ridges extending on opposed sides of the clip. The heat sink may additionally include a locking tab interfacing with the clip to restrict removal of the clip from the heat sink. 
     The assembly may also include an adhesive element disposed between the printed circuit board and the heat sink. The adhesive element may include adhesive tape and/or adhesive paste. 
     The heat sink may be formed from aluminum. 
     According to another embodiment, there is provided a heat sink for use with a printed circuit board and a socket engageable with the printed circuit board, with the printed circuit board including a first face and a second face opposite the first face. The heat sink includes a first wall, a second wall spaced from the first wall, and an end wall extending between the first and second walls. The first wall, the second wall, and the end wall collectively define a cavity configured to receive the printed circuit board such that the first wall of the heat sink extends over the first face and the second wall of the heat sink extends over the second face when the printed circuit board is received within the cavity to allow heat to be transferred from the printed circuit board to the heat sink. The heat sink is configured to interface with the socket body when the printed circuit board is connected to the socket for stabilizing the printed circuit board relative to the socket. 
     The present disclosure will be best understood by reference to the following detailed description when read in conjunction with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and other features and advantages of the various embodiments disclosed herein will be better understood with respect to the following description and drawings, in which: 
         FIG.  1    is an upper perspective view of a heat dissipating circuit board assembly including a heat sink on a memory module, the circuit board assembly being aligned with a connector socket for connection therewith; 
         FIG.  2    is a front view of the circuit board assembly and connector socket depicted in  FIG.  1   ; 
         FIG.  3    is an exploded upper perspective view of the circuit board assembly; 
         FIG.  4    is a front view of the circuit board assembly mounted to the connector socket; 
         FIG.  5    is a cross sectional end view of the circuit board assembly taken along line  5 - 5  of  FIG.  4   ; 
         FIG.  6    is a cross sectional end view of the circuit board assembly taken along line  6 - 6  of  FIG.  4   ; and 
         FIG.  7    is an enlarged detail view depicting engagement of a connector tab to the circuit board assembly. 
     
    
    
     Common reference numerals are used throughout the drawings and the detailed description to indicate the same elements. 
     DETAILED DESCRIPTION 
     The detailed description set forth below in connection with the appended drawings is intended as a description of certain embodiments of a heat sink for a memory module that is mountable in a connector socket on a motherboard, and is not intended to represent the only forms that may be developed or utilized. The description sets forth the various structures and/or functions in connection with the illustrated embodiments, but it is to be understood, however, that the same or equivalent structure and/or functions may be accomplished by different embodiments that are also intended to be encompassed within the scope of the present disclosure. It is further understood that the use of relational terms such as first and second, and the like are used solely to distinguish one entity from another without necessarily requiring or implying any actual such relationship or order between such entities. 
     Referring now to the drawings, wherein the showings are for purposes of illustrating preferred embodiments of the present disclosure, and not for purposes of limiting the same, there is depicted a heat dissipating memory module assembly  10  configured to be mountable in a connector socket  12 . The memory module assembly  10  includes a memory module  14  and a heat sink  16  connected to the memory module  14 . The heat sink  16  may extend over the memory module  14  in proximity to the memory module  14  to allow heat generated by the memory module  14  to flow to the heat sink  16 . In addition to providing heat dissipating functionality to the memory module  14 , the heat sink  16  may also be configured to stabilize the memory module  14  by preventing three-dimensional movements relative to the socket  12  along the x-axis, the y-axis, and the z-axis (see  FIG.  1   ). In this regard, the heat sink  16  may include a flared end portion that may be formed like a wing, such that when the memory module  14  is inserted into a channel  18  of the connector socket  12 , the flared, wing shaped bottom may contact the connector socket  12  thereby immobilizing the memory module  14  with respect to the connector socket  12 . An adhesive layer may be included on the contact surfaces of the flared end portion to adhere to the outer surface of the connector socket  12  to further assist in holding the memory module  14  in place relative to the connector socket  12 . The dual functionality of the heat sink  16 , i.e., heat dissipation and memory module stabilization, may be particularly desirable for memory modules  14  used in environments subjected to extreme vibrations, such as computers used in military applications. 
       FIGS.  1  and  2    shows the memory module assembly  10  detached from the connector socket  12 , while  FIG.  3    is an exploded view of the memory module assembly  10 . The memory module  14  is a printed circuit board including a substrate  20  having a first face  22 , a second face  24  opposite the first face  22 , a longitudinal face  26 , and a pair of opposed lateral faces  28 . The substrate  20  may be formed in a generally quadrangular configuration. The memory module  14  may include notches  30  formed therein, with the notches  30  extending into the substrate  20  from the lateral faces  28  thereof. Each notch  30  may include a pair of opposed edges  32  extending into the substrate  20  from the lateral face  28 , and an inner edge  34  extending between the pair of opposed edges  32 . The purpose of the notches  30  will be described in more detail below. 
     The memory module  14  may include several electrical components  36  mounted to the first and/or second faces  22 ,  24 . The electrical components  36  may include a dynamic random-access memory (DRAM) chip, processors, databases, or other electrical components known in the art. The memory module  14  may additionally include an electrical connector  38  formed along a peripheral edge of the substrate  20  positioned opposite to the longitudinal face 26 . The electrical connector  38  may be in electrical communication with the electrical components  36  mounted on the substrate  20 . In the exemplary embodiment the electrical connector  38  is a 288-pin connector, however, it is understood that the electrical connector  38  may include a 168-pin connector, a 184-pin connector, a 240-pin connector, a 288-pin connector, or other pin connector currently known in the art or later developed in the art. 
     The heat sink  16  extends over the memory module  14  and is generally complementary to the configuration of the memory module  14 . According to one embodiment, the heat sink  16  includes a first wall  40 , a second wall  42  spaced from the first wall  40 , and an end wall  44  extending between the first and second walls  40 ,  42 . The heat sink  16  may additionally include a pair of lateral walls  46  extending between the first and second walls  40 ,  42  and positioned adjacent the end wall  44 . In one embodiment, each lateral wall  46  may be formed by a pair of tabs connected to respective ones of the first and second walls  40 ,  42  and folded toward each other, such that the pair of tabs collectively define a given lateral wall  46 . Each tab may be integrally formed with one of the first and second walls  40 ,  42 , and may be folded relative thereto to be approximately perpendicular to the corresponding first and second wall  40 ,  42 . Each lateral wall  46  may include an edge  48  which is positioned between the end wall  44  and an opposing distal end of the heat sink  16 , and thus, the edge  48  may be referred to as an intermediate edge. In one embodiment, at least a portion of the intermediate edge  48  may be generally perpendicular to the lateral wall  46 , and generally parallel to the end wall  44 . The importance of the intermediate edge  48  will be described in more detail below. 
     The heat sink  16  may include a flared end portion opposite the end wall  44 . In this regard, the first wall  40  may include a first planar portion extending from the end wall  44 , and a first curved end portion  50  extending away from the second wall  42 . The first curved end portion  50  may extend longitudinally in spaced, generally parallel relation to the end wall  44 . Similarly, the second wall  42  may include a second planar portion extending from the end wall  44  in generally parallel relation to the first planar portion, and second curved end portion  52  extending away from the first wall  40 . The second curved end portion  52  may extend longitudinally in spaced, generally parallel relation to the end wall  44  and the first curved end portion  50 . The first and second curved end portions  50 ,  52  may extend away from each other and may collectively define the flared end portion of the heat sink  16 . The flared end portion may be configured to engage with the connector socket  12  to provide stabilization to the memory module  14 , as will be described in more detail below. 
     The heat sink  16  may be formed from aluminum or other materials known in the art exhibiting desirable heat transfer material characteristics. 
     The heat sink  16  may define a cavity  54  which is sized to receive the memory module  14 . In one embodiment, the cavity  54  is collectively defined by the first wall  40 , the second wall  42 , the end wall  44 , and the pair of lateral walls  46 . The width of the cavity  54 , i.e., the distance between the inner surfaces of the first and second walls  40 ,  42 , may be slightly larger than the width of the memory module  14 , e.g., the maximum distance defined by opposing surfaces generally parallel to the first and second faces  22 ,  24 . In this regard, the width of the memory module  14  may be defined by opposing electrical components  36 , and/or the first and second faces  22 ,  24 . 
     The memory module  14  may be inserted into the heat sink  16  such that the longitudinal face  26  is disposed adjacent the end wall  44 , and the first wall  40  extends over the first face  22  and the second wall  42  extends over the second face  24 . The electrical connector  38  on the memory module  14  may protrude out of the cavity  54  and may remain exposed to allow for connection with the socket  12 . When the memory module  14  is completely inserted into the heat sink  16 , the intermediate edges  48  of the heat sink  16  may overlap with one of the notches  30  formed on the substrate  20 . In other words, with each intermediate edge  48  may extend along a respective axis that overlaps a respective one of the pair of notches  30 . Thus, the resultant clearance defined collectively by a first edge  38  of the notch  30  and the corresponding intermediate edge  48  of the heat sink  16  (i.e., D 1 ) is smaller than the distance defined by the pair of opposed edges  32  of the notch  30  (i.e., D 2 ). The amount of over-hang of the heat sink  16  relative to the notch  30  may be equal to D 2 -D 1 . The importance of this reduction in clearance will be described in more detail below. 
     An adhesive  56  may be used to secure the heat sink  16  to the memory module  14 . The adhesive  56  may include a thermal tape or a thermal paste, which may act as a thermal conductor to facilitate heat transfer from the memory module  14  to the heat sink  16 , while also acting as an electrical insulator for the electrical components  36  mounted on the substrate  20 . According to one embodiment, the thickness of the adhesive  56  extending between the heat sink  16  and the electrical components  36  is between 0.75 mm and 1.75 mm, and more preferably 1.25 mm. 
     The memory module  14  may also be secured to the heat sink  16  through the use of one or more clips  58  externally attachable to the heat sink  16  for applying a compressive force to the heat sink  16 . Each clip  58  may include a first side  60  and a second side  62  opposite the first side  60 . The first and second sides  60 ,  62  define a width therebetween, with the width being equal to a first distance when the clip  58  is detached from the heat sink  16  and is allowed to assume a neutral configuration. The clip  58  may be resilient so as to allow the width to vary and depart from the neutral configuration. However, when the clip  58  transitions from the neutral position, the clip  58  is biased to return to the neutral configuration. Thus, the clip  58  is configured such that it defines a width having a first distance (e.g., at its neutral position) that is slightly smaller than the external width of the heat sink  16 . In this regard, in order to place the clip  58  on the heat sink  16 , with the first side  60  extending over the first wall  40  and the second side  62  extending over the second wall  42 , expansion of the clip width is required to extend over the heat sink  16 . Therefore, when the clip  58  is placed on the heat sink  16 , the biasing force associated with the clip  58  applies a compressive force on the heat sink  16  to secure the heat sink  16  to the memory module  14 . In particular, a first force is applied to the first wall  40  and a second force to the second wall  42 , with the second force being applied in a direction opposite to that of the first force. 
     The heat sink  16  may include several pairs of ridges  64  for positioning the clip  58  on the heat sink  16 . In the exemplary embodiment, the heat sink  16  includes two pairs of ridges  64  protruding outwardly (e.g., away from the cavity) from the first wall  40 , and two pairs of ridges  64  protruding outwardly from the second wall  42 . Each clip  58  is centered by a pair of ridges  64  on the first face  22  and a pair of ridges  64  on the second face  24 . The ridges  64  may prevent the clips  58  from sliding over the outer surface of the heat sink  16 . 
     The heat sink  16  may additionally several unidirectional locking tabs  66  configured to retain the clips  58  on the heat sink  16 . Each locking tab  66  may be formed with one of the first and second walls  40 ,  42  and may be located between a given pair of ridges  64 . Each locking tab  66  may include a proximal end positioned adjacent the end wall  44  and a distal end extending away from the end wall  44 . Each locking tab  66  may further be angled relative to the respective first and second wall  40 ,  42  such that the distal end protrudes away from the respective first and second wall  40 ,  42 . When the clip  58  is placed on the heat sink  16 , a portion of the clip  58  may pass over at least one locking tab  66 . The width of the clip  58  may expand as it passes over the locking tab  66 . When the clip  58  is pressed all the way onto the heat sink  16 , the portion of the clip  58  previously extending over the locking tab  66  is moved passed the locking tab  66 , which allows the clip  58  to transition from its expanded configuration to its neutral configuration due to the inherent resiliency of the clip  58 . The angled distal end of the locking tab  66  may interface with an edge of the clip  58  to restrict removal of the clip  58  from the heat sink  16 . 
     The memory module  14  is configured to be connectable to the socket  12 , which includes a socket body  68  and socket electrical connector  70 . An exemplary socket  12  is a Molex® 288-pin memory DIMM socket. The socket electrical connector  70  may be complementary to the memory module  14 , and thus, the number of pins on the socket electrical connector  70  may correspond to the number of pins included on the memory module  14 . The socket body  68  may be mounted on a motherboard, e.g., a main printed circuit board included in general purpose computers and/or other expandable computing systems. The socket body  68  may be elongate and include a central portion  72  including a pair of primary walls defining the central channel  18  therebetween. Referring to  FIG.  1   , the central portion  72  defines a Y-axis, which extends parallel to the central channel  18 . An X-axis is perpendicular to the Y-axis and may pass through both the primary walls of the central portion  72 . A Z-axis is perpendicular to the X-axis and the Y-axis. 
     The socket electrical connector  70  is connected to the primary walls, located within the central channel  18 , and electrically connectable to the electrical connector  38  on the memory module  14  when the memory module  14  is connected to the socket  12 . The socket electrical connector  70  may be in electrical communication with other electrical components  36  on the motherboard. 
     The socket body  68  may additionally include a pair of lateral supports  74  extending from respective ends of the central portion  72 , with each lateral support  74  including a guide slot  76  extending in generally perpendicular relation to the central channel  18 , while also being in communication with the central channel  18 . The guide slot  76  is configured to receive the memory module  14  and guide the memory module  14  into the channel  18  when connecting the memory module  14  to the socket  12 . 
     The socket  12  may additionally include a pair of locking members  78  at opposed end portions thereof and configured to be engageable with the substrate  20  when the memory module  14  is connected to the socket  12 . Each locking member  78  is pivotally connected to one of the lateral supports  74  and includes a pivot shaft  80  and a head  82  connected to the pivot shaft  80 . The head  82  includes a finger grip  84  and a locking body  86 . The locking body  86  is configured to be received in a respective notch  30  formed on the substrate  20  when the memory module  14  is connected to the socket  12 . The locking body  86  includes a pair of opposed surfaces  88 ,  89  which are sized to fit within the reduced clearance (i.e., D 1 ) defined by the overlapping configuration of the heat sink  16  and the notches  30  to create a tight, secure fit. 
     Each locking member  78  may be pivotable relative to the socket body  68  between an unlocked configuration and a locked configuration. The locking member  78  is moved to the unlocked configuration to allow for insertion of the memory module  14  into the connector socket  12 , or removal of the memory module  14  from the connector socket  12 . The locking member  78  is moved to the locked position when the memory module  14  is completely inserted into the socket body  68  to retain the memory module  14  therein. According to one embodiment, each locking member  78  may pivot relative to the socket body  68  by a magnitude of less than 90 degrees as the locking member  78  transitions between the locked and unlocked positions. 
     To connect the memory module assembly  10  to the socket  12 , the exposed lateral faces  28  of the substrate  20  are aligned with respective guide slots  76  formed on the lateral supports  74 . The memory module assembly  10  is then pressed toward the socket body  68  along the Z-axis until the memory module assembly  10  assumes an inserted position relative to the socket  12 . In the inserted position, the electrical connector  38  on the memory module  14  is in electrical communication with the electrical connector  70  on the socket  12 . Furthermore, when the memory module assembly  10  is in the inserted position, the flared end portion of the heat sink  16  may contact an outer surface of the socket body  68 . In this regard, an adhesive  90  may be optionally connected to, or disposed on, the flared end portion for enhancing engagement between the heat sink  16  and the socket  12 . The engagement between the flared end portion and the optional use of the adhesive  90  may mitigate movement of the memory module  14  relative to the socket in the X-Y plane. 
     When the memory module assembly  10  is in the inserted position, the locking members  78  may be transitioned from their unlocked positions toward their locked positions. As the locking members  78  assume the locked position, the locking body  86  is received within the notch  30 , with the surface  88  of the locking body  86  being disposed between an intermediate edge  48  on the heat sink  16  and an edge  32  formed on the substrate  20 . In this regard, the distance between the opposed surfaces  88 ,  89  on the locking body  86  are spaced by substantially the same distance as the separation between the intermediate edge  48  of the heat sink  16  and the opposing edge on the substrate  20  (e.g., D 1 ). In this regard, the slight dimensional difference between the effective size of the notch (e.g., D 1 ) and the size of the locking body  86  allows the locking member  78  to transition between the unlocked position and the locked position when the memory module assembly  10  is in the inserted position, while at the same time interface with the intermediate edge  48  on the heat sink  16  and the opposing edge along the notch to minimize movement of the memory module assembly  10  in a direction perpendicular to the channel  18  (e.g., restricts movement of the memory module assembly  10  in the Z-axis). In one embodiment, the surface  88  of the locking body  86  is in face-to-face contact with the intermediate edge  48  of the heat sink  16  when the locking member  78  is in the locked position. The face-to-face contact may extend along a length, Li defined by the contacting portions of the edge  48  and surface  88 . Thus, the contact between the surface  88  and the intermediate edge  48  may restrict movement of the memory module assembly  10  relative to the socket  12  along the z-axis. 
     According to one embodiment, the temperature of the outer surfaces of the electrical components  36  should be around 70-85 degrees Celsius for normal operations. The use of the thermal adhesive between the electrical components  36  and the heat sink  16  helps to dissipate the heat. Furthermore, the heat sink  16  may be capable of expelling a minimum of 8%-12% of the heat. 
     Although the foregoing describes the heat sink  16  as being used in connection with a memory module  14 , it is understood that the use of the heat sink  16  may not be limited thereto. In this regard, the heat sink  16  may be used with any printed circuit board that may be connected to a connector socket. 
     The particulars shown herein are by way of example only for purposes of illustrative discussion, and are not presented in the cause of providing what is believed to be most useful and readily understood description of the principles and conceptual aspects of the various embodiments of the present disclosure. In this regard, no attempt is made to show any more detail than is necessary for a fundamental understanding of the different features of the various embodiments, the description taken with the drawings making apparent to those skilled in the art how these may be implemented in practice.