Patent Publication Number: US-2022217870-A1

Title: Circuit boards for electronic devices

Description:
BACKGROUND 
     Electronic devices may include circuit boards that carry a number of electronic components. For instance, a circuit board may include a central processing unit (CPU), a graphics processing unit (GPU), a memory, and a host of other components and devices for operating the associated electronic device. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Various examples will be described below referring to the following figures: 
         FIG. 1  is a perspective view of an electronic device according to some examples; 
         FIG. 2  is a schematic side view of the electronic device of  FIG. 1  according to some examples; 
         FIG. 3  is a side, partial cross-sectional view of a circuit board of the electronic device of  FIG. 1  according to some examples; and 
         FIG. 4  is an exploded view of the circuit board of  FIG. 3  according to some examples. 
     
    
    
     DETAILED DESCRIPTION 
     In the figures, certain features and components disclosed herein may be shown exaggerated in scale or in somewhat schematic form, and some details of certain elements may not be shown in the interest of clarity and conciseness. In some of the figures, in order to improve clarity and conciseness, a component or an aspect of a component may be omitted. 
     In the following discussion and in the claims, the terms “including” and “comprising” are used in an open-ended fashion, and thus should be interpreted to mean “including, but not limited to. . . . ” Also, the term “couple” or “couples” is intended to be broad enough to encompass both indirect and direct connections. Thus, if a first device couples to a second device, that connection may be through a direct connection or through an indirect connection via other devices, components, and connections. In addition, as used herein, the terms “axial” and “axially” generally refer to positions along or parallel to a central or longitudinal axis (e.g., central axis of a body or a port), while the terms “radial” and “radially” generally refer to positions located or spaced to the side of the central or longitudinal axis. 
     As used herein, including in the claims, the word “or” is used in an inclusive manner. For example, “A or B” means any of the following: “A” alone, “B” alone, or both “A” and “B.” In addition, when used herein including the claims, the word “generally” or “substantially” means within a range of plus or minus 10% of the stated value. As used herein, the term “electronic device,” refers to an device that is to carry out machine readable instructions, and may include internal components, such as, processors, power sources, memory devices, etc. For example, an electronic device may include, among other things, a personal computer, a smart phone, a tablet computer, a laptop computer, a personal data assistant, etc. 
     As previously described, circuit boards within electronic devices may support a plurality of electronic components (e.g., central processing units (CPUs), graphics processing units (GPUs), memories, etc.). Some of these electronic components generate heat during operations. To maintain an acceptable temperature within the housing of the electronic device, heat transfer mechanisms, structures, assemblies, etc., may be used to remove the heat generated by the electronic components. However, there is a continued push to decrease the size of electronic components. As a result, these heat generating components may be brought into closer proximity, which may prevent a heat transfer assembly from effectively removing heat generated during operations. Accordingly, examples disclosed herein include circuit boards for supporting heat generating electronic components within an electronic device that employ stacked arrangements so as to accommodate a smaller foot print within the electronic device, while still allowing for sufficient heat transfer from the heat generating components during operations. In some examples, a circuit board may include a CPU and a GPU stacked on opposing sides of a heat transfer assembly. 
     Referring now to  FIGS. 1 and 2 , an electronic device  10  according to some examples is shown. In this example, electronic device  10  is a laptop computer that includes a first housing member  12  rotatably coupled to a second housing member  16  at a hinge  13 . The first housing member  12  includes a user input device, such as, for example, a keyboard  14 . The second housing member  16  includes an electronic display  18  (or more simply “display  18 ”) that is to project images for viewing by a user (not shown) of the electronic device  10 . 
     In other examples, electronic device  10  may comprise another type of electronic device (that is, other than a laptop computer as shown in  FIGS. 1 and 2 ). For instance, in other examples, electronic device  10  may comprise any of the other electronic devices above (e.g., a tablet computer, smartphone, desktop computer, server, etc.). 
     Referring specifically to  FIG. 2 , a circuit board  100  is disposed within first housing member  12 . As will be described in more detail below, circuit board  100  may support a number of heat generating components (e.g., CPU, GPU, etc.) that are used during operation of electronic device  10 . In addition, the circuit board  100  includes a heat transfer assembly  140  comprising a vapor chamber that transfers heat from a plurality of the heat generating components during operations. Further details of examples of circuit board  100  are now discussed below. 
     Referring now to  FIG. 3 , an example of circuit board  100  that may be used within electronic device  10  is shown. Generally speaking, circuit board  100  includes a first substrate  102 , a second substrate  104 , a CPU  110  coupled first substrate  102 , a GPU  120  coupled to second substrate  104 , and heat transfer assembly  140  coupled between the CPU  110  and GPU  120 . 
     The substrates  102 ,  104  may comprise any suitable platform or support surface for physically supporting and (in some examples) electronically coupling electronic components (e.g., CPU  110 , GPU  120 ) to other components (e.g., such as those that may be coupled to circuit board  100  and/or adjacent thereto). In some examples, substrates  102 ,  104  comprise a plurality of electrically conductive and insulating layers laminated together. For instance, in some examples, substrate  102  and/or substrate  104  may comprise alternating layers of electrically insulating materials (e.g., composite materials including fiber glass, epoxy resin, etc.) and an electrically conductive material (e.g., copper). The first substrate  102  and second substrate  104  include support surfaces  102   a  and  104   a , respectively, that are to support electronic components (e.g., CPU  110 , GPU  120 , etc.) during operations. 
     CPU  110  may be a processor of an electronic device (e.g., electronic device  10  in  FIGS. 1 and 2 ). The CPU  110  may execute machine readable instructions that are stored (e.g., partially, wholly, etc.) on a memory device (e.g., volatile and/or non-volatile memory devices). GPU  120  may comprise suitable circuitry or components (e.g., processors, controllers, etc.) that are to generate images that are then output to a display of a corresponding electronic device (e.g., such as display  18  of electronic device  10  in  FIGS. 1 and 2 ). CPU  110  is secured to support surface  102   a  of first substrate  102 , and GPU  120  is secured to support surface  104   a  of second substrate  104 . Any suitable method or mechanism may be used to secure CPU  110  and GPU  120  to support surfaces  102   a  and  104   a , respectively, such as, for instance, soldering, screws, pins, latches, etc. 
     Together, the CPU  110  and GPU  120  may operate to execute machine readable instructions and output corresponding images (e.g., still images, videos, etc.) to a display of an electronic device during operations. However, the operation of the CPU  110  and GPU  120  generate heat (e.g., due to electrical resistance therein) that may eventually cause damage to the CPU  110 , GPU  120  or other components within the electronic device (e.g., electronic device  10 ) if not properly removed. Accordingly, the heat transfer assembly  140  may be in contact with both the CPU  110  and GPU  120  so as to draw heat away from these components during computing operations. 
     Referring now to  FIGS. 3 and 4 , heat transfer assembly  140  includes a vapor chamber  150 , and a pair of fin banks  160 . Vapor chamber  150  is a generally hollow member that defines an inner cavity  156 . The inner cavity  156  may be filled (e.g., partially or wholly) with a fluid that is to change phase (e.g., from liquid to vapor) when exposed to heat (e.g., heat transferred into the cavity  156  from CPU  110  and GPU  120  during operations). In some examples, the fluid within cavity  156  comprises water. The vapor chamber  150  may be constructed from a thermally conductive material so as to efficiently conduct heat into the cavity  156  during operations. For instance, in some examples, vapor chamber  150  is constructed from copper. 
     As best shown in  FIG. 4 , vapor chamber  150  includes a central body  157 , and a pair of lateral extensions  159  extending outward from central body  157 . Cavity  156  may be defined within both the central body  157  and the lateral extensions  159 . In some examples, the lateral extensions  159  may extend from opposing sides of the central body  157  such that vapor chamber  150  is generally T-shaped. 
     Vapor chamber  150  (including the central body  157  and lateral extensions  159 ) includes a first side  152  and a second side  154  opposite first side  152 . The first side  152  is in contact with CPU  110  and the second side  154  is in contact with GPU  120 . Thus, vapor chamber  150  is stacked between the CPU  110  and GPU  120  so as to transfer heat from both the CPU  110  and GPU  120  during operations. In addition, in some examples (e.g., such as the example of  FIGS. 3 and 4 ), the CPU  110  and GPU  120  are disposed on and in contact with the opposite sides  152 ,  154  of vapor chamber  150  along the central body  157 . Thus, when fully assembled, circuit board  100  may form a stack along a central axis  105  that includes, in order along the axis  105 , the CPU  110 , the vapor chamber  150 , and the GPU  120 . Thus, the stack of components formed by the CPU  110 , vapor chamber  150 , and GPU  120  is coupled to the support surfaces  102   a ,  104   a  of the substrates  102 ,  104 , respectively. In some examples (e.g., such as the example of  FIGS. 3 and 4 ), the axis  105  may extend normally (or perpendicularly) through the support surfaces  102   a ,  104   a  of substrates  102 ,  104 , respectively. 
     Referring still to  FIGS. 3 and 4 , fin banks  160  include a plurality of parallel plates or fins  162 . The fins  162  may comprise a thermally conductive material (e.g., a metallic material) such that fins  162  may conduct heat during operations. Fin banks  160  may be secured to support surface  102 a of first substrate  102  via any suitable structure or mechanism (e.g., soldering, screws, latches, etc.). In addition, fins  162  are in contact with first side  152  of vapor chamber  150 . Specifically, fins  162  are in contact with lateral extensions  159 . 
     As shown in  FIG. 4 , each fin bank  160  is coupled to a corresponding fan  170  that includes an impeller  172  rotatably disposed therein. During operations, the impellers  172  of fan assemblies  170  may rotate to direct airflow across the fins  162  of fin banks  160  so as to convectively remove heat from the fins  162 . Impellers  172  may be rotated with any suitable driver or mechanism (not shown) such as, for instance, electric motors. The airflow across the fins  162  may be directed from the fins  162  into the impellers  172  (e.g., such that impellers  172  operate in a so-called drawn air arrangement with respect to fin banks  160 ) or may be directed from the impeller  172  to the fins  162  (e.g., such that impellers  172  operate in a so-called forced air arrangement with respect to fin banks  160 ). 
     Referring still to  FIGS. 3 and 4 , during operations, CPU  110  and GPU  120  are mounted to the opposing sides  152 ,  154 , respectively, of vapor chamber  150  in the manner described above. Thereafter, CPU  110  and GPU  120  may be utilized in a computing operation so that heat is generated within the CPU  110  and GPU  120  as described above. The heat generated by the CPU  110  and GPU  120  may be transferred (e.g., conducted) into to vapor chamber  150  via the contact at first side  152  and second side  154 , respectively. The heat transferred to vapor chamber  150  may then be transferred (e.g., via convection and/or radiation) into the fluid disposed within cavity  156 . As a result, the fluid may begin to vaporize (e.g., thereby forming water vapor for examples that utilize water within the vapor chamber  150 ). The vaporized fluid may then flow (e.g., due to a differential pressure driven by the vaporization process as well as a thermal gradient within cavity  156 ) into the lateral extensions  159  so as to transfer the heat (e.g., via convection and conduction) through the first side  152  of vapor chamber  150  at lateral extensions  159  into the fins  162  of fin banks  160 . The airflow driven by impeller  172  may then carry heat away from fins  162  (e.g., into the outer environment surrounding the circuit board  110  and/or into the outer environment surrounding the associated electronic device). 
     Within lateral extensions  159 , the vaporized fluid may cool (e.g., due to the heat transfer into the fins  162  described above) and therefore condense. Capillary forces acting between the relatively narrow lateral extensions  159  and the condensed fluid disposed therein may then drive the condensed fluid from the lateral extensions  159  back into the central body  157  to thereby restart the vaporization and heat transfer cycle described above. 
     Thus, the vapor chamber  150  may allow for effective heat transfer from the CPU  110  and GPU  120  within a stacked arrangement such that the overall footprint (e.g., a footprint in a plane extending radially to the axis  105 ) may be reduced. Thus, a size of the circuit board  100  may be reduced while still allowing sufficient heat to be transferred away from the electronic components (e.g., CPU  110 , GPU  120 , etc.) during operations. 
     It should be appreciated that other components may be mounted to the first side  152  and second side  154  of vapor chamber  150  in some examples. For instance, other components may be mounted to first substrate  102  adjacent CPU  110  and/or on the second substrate  104  adjacent GPU  120  that also contact the vapor chamber  150  so as to transfer heat thereto during operations. In some examples, these additional components may include for example, memories (e.g., random access memories), voltage regulators, inductors, etc. In addition, in some examples, more or less than two lateral extensions  159  may be included on vapor chamber  150 . For instance, in some examples, a single lateral extension  159  or three lateral extensions  159  may be included on vapor chamber  150 . In still other examples, no laterals extensions  159  may be included. 
     The examples disclosed herein have included circuit boards for supporting heat generating electronic components (e.g., CPU  110 , GPU  120 ) in a stacked arrangement on either side of a vapor chamber (e.g., vapor chamber  150 ) of a heat transfer assembly (e.g., heat transfer assembly  140 ). Thus, through use of the examples disclosed herein, a circuit board may have a reduced footprint while still allowing for sufficient heat transfer from the heat generating components during operations. 
     The above discussion is meant to be illustrative of the principles and various examples of the present disclosure. Numerous variations and modifications will become apparent to those skilled in the art once the above disclosure is fully appreciated. It is intended that the following claims be interpreted to embrace all such variations and modifications.