Abstract:
The invention is directed to a novel solution to providing heat management and cooling to electronic devices. According to various embodiments, heat produced during the operation of the processing components in the computing device is absorbed by heat management features integrated within a supporting mid-frame. The heat management features include phase changing materials that allow the processing components to be kept at a isothermal state through changes in phase, thereby prolonging the duration of time in which the processing components can operate at high performance levels without the need to throttle the performance.

Description:
BACKGROUND OF THE INVENTION 
     The prevailing design methodology of mobile computing devices (such as smart phones, tablets devices, netbooks, personal data assistants, portable media devices, wearable devices, etc.) emphasizes slimmer profiles while offering ever increasing processing and image rendering capabilities and larger display sizes. As a natural result of minimizing the width or thickness of the underlying mobile computing devices, a similar trend of minimizing the height of the internal modules has developed out of necessity. 
     A common implementation of a mobile computing device includes a main printed circuit board (PCB) having one or more processing elements. The distinct lack of internal space due to the smaller form factor not only makes heat dissipation more critical, but also presents additional challenges for heat distribution and dispersal. Moreover, other components (such as camera modules, battery modules, etc.) also generate heat during operation. A popular solution for managing heat levels in mobile computing devices is through the use of performance throttling. 
     Performance throttling is performed by intentionally limiting or reducing performance levels of components in a system below the highest possible level(s) in order to reduce a heat generated during operation/usage. Typically, a component such as a processor is able to operate at the highest possible rates (e.g., processing frequencies) for a relatively short period. When the heat (as determined by sensors) generated by the processor due to operation exceeds a threshold, operating rates are throttled to reduce the heat produced commensurately. Typically, the threshold at which the performance is throttled corresponds to a higher level of risk with respect to user comfort, or to comply with safe operating limits with respect to the component. However, throttling the performance can negatively impact user experience, since performance levels are reduced, sometimes perceptibly. 
     To address the throttling issue, recently proposed solutions have incorporated materials with phase changing properties for thermal management. Proposed implementations include heat sink fins interspersed with portions of phase change material, compositions that mix phase change materials with other materials for structural effect, and adhering phase change materials on system-on-chips. However, the proposed solutions each present different issues that may be less than ideal. For example, heat sink fins interspersed with phase change materials would be limited to phase change materials with significantly high melting points, as liquids would not be bound by such a structure, and may leak or otherwise escape from between the heat sink fins. Meanwhile, phase change materials mixed with materials for structural effect (typically graphite or other such compositions) are often mixed with materials that do not exhibit the same thermal properties. Typically, the materials have less ideal thermal properties, such as less heat absorption efficiency. As such, the efficacy of these solutions can be significantly less than solutions where the phase change material is unadulterated. Likewise, adhering phase change materials on system-on-chips would require additional steps, such as encapsulating the phase change materials in molding compounds, that would increase the height of such structures. 
     SUMMARY OF THE INVENTION 
     This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the invention, nor is it intended to be used to limit the scope of the invention. 
     An aspect of the present invention proposes a system for absorbing and managing heat in a computing device using heat management features directly integrated within a support structure or panel. According to these embodiments, a support panel is provided with integrated heat management features as a sheet or block of phase change material (PCM). The heat absorption of the support structure is improved through the integration of the heat management features, since the features will typically have significantly higher latent heat capacitance than the composition of the underlying frame/support structure. 
     According to another aspect of the present invention, a mobile consumer electronics device—such as a mobile phone, wearable computing device, or tablet—is provided with a mid-frame panel that provides structural and mechanical support to the device while also absorbing heat produced by neighboring components in the computing device to achieve a more even temperature profile. According to these embodiments, heat produced during the operation of the processing components in the computing device is absorbed by heat management features integrated within the mid-frame. In an embodiment, the heat management features include a structure (e.g., a sheet or block) of a solid-liquid phase change material. The phase change material absorbs the heat produced by the processing components. When the heat exceeds the melting point of the phase change material, the phase change material melts to absorb additional heat, keeping the processing components isothermal or nearly isothermal. The phase change material solidifies when operation of the processing components is discontinued and the temperature in the system cools. Through the integration of the phase change material(s), systems with internal performance throttling mechanisms to reduce heat production may delay performance throttling, allowing longer periods of high performance usage. 
     According to yet another aspect, a support panel is described herein with integrated thermal management features that include phase change materials. In an embodiment, the support panel is implemented to include a metal frame with the thermal management features fully integrated with the panel as a single discrete and contiguous unit. Changes in phase (e.g., solid to liquid) of the thermal management features are contained within the metal frame. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings are incorporated in and form a part of this specification. The drawings illustrate embodiments. Together with the description, the drawings serve to explain the principles of the embodiments: 
         FIG. 1  depicts a first exemplary component layer stack of a mobile computing device, in accordance with various embodiments of the present invention. 
         FIG. 2  depicts a second exemplary component layer stack of a mobile computing device, in accordance with various embodiments of the present invention. 
         FIG. 3  depicts a third exemplary component layer stack of a mobile computing device, in accordance with various embodiments of the present invention. 
         FIG. 4  depicts a fourth exemplary component layer stack of a mobile computing device, in accordance with various embodiments of the present invention. 
         FIG. 5  depicts a fifth exemplary component layer stack of a mobile computing device, in accordance with various embodiments of the present invention. 
         FIG. 6  depicts a three-dimensional view of an exemplary mid-frame of a mobile computing device with integrated heat management features, in accordance with various embodiments of the present invention. 
         FIG. 7  depicts an exemplary back panel of a mobile computing device with integrated heat management features, in accordance with various embodiments of the present invention. 
         FIG. 8  depicts a flowchart for manufacturing a mobile computing device with integrated heat management features, in accordance with various embodiments of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     Reference will now be made in detail to the preferred embodiments of the invention, a method and system for the use of a reputation service provider, examples of which are illustrated in the accompanying drawings. While the invention will be described in conjunction with the preferred embodiments, it will be understood that they are not intended to be limit to these embodiments. On the contrary, the invention is intended to cover alternatives, modifications and equivalents, which may be included within the spirit and scope as defined by the appended claims. 
     Furthermore, in the following detailed descriptions of embodiments of the invention, numerous specific details are set forth in order to provide a thorough understanding of the invention. However, it will be recognized by one of ordinary skill in the art that the invention may be practiced without these specific details. In other instances, well known methods, procedures, components, and circuits have not been described in detail as not to unnecessarily obscure aspects of the invention. 
     Some portions of the detailed descriptions that follow are presented in terms of procedures, steps, logic blocks, processing, and other symbolic representations of operations on data bits that can be performed on computer memory. These descriptions and representations are the means used by those skilled in the data processing arts to most effectively convey the substance of their work to others skilled in the art. A procedure, computer generated step, logic block, process, etc., is here, and generally, conceived to be a self-consistent sequence of steps or instructions leading to a desired result. The steps are those requiring physical manipulations of physical quantities. Usually, though not necessarily, these quantities take the form of electrical or magnetic signals capable of being stored, transferred, combined, compared, and otherwise manipulated in a computer system. It has proven convenient at times, principally for reasons of common usage, to refer to these signals as bits, values, elements, symbols, characters, terms, numbers, or the like. 
     It should be borne in mind, however, that all of these and similar terms are to be associated with the appropriate physical quantities and are merely convenient labels applied to these quantities. Unless specifically stated otherwise as apparent from the following discussions, it is appreciated that throughout the present invention, discussions utilizing terms such as “storing,” “creating,” “protecting,” “receiving,” “encrypting,” “decrypting,” “destroying,” or the like, refer to the action and processes of a computer system or integrated circuit, or similar electronic computing device, including an embedded system, that manipulates and transforms data represented as physical (electronic) quantities within the computer system&#39;s registers and memories into other data similarly represented as physical quantities within the computer system memories or registers or other such information storage, transmission or display devices. 
     Embodiments of the invention are directed to solutions for delaying performance throttling in computing devices by using heat management features integrated with a mid-frame support panel. By fully integrating the heat management features within the support panel, performance throttling due to excessive heat may be delayed by maintaining isothermal conditions in mobile computing devices for longer durations. 
     Integrated Phase Changing Materials 
       FIG. 1  represents a profile of a first exemplary component layer stack  100  in a mobile computing device, according to embodiments of the invention. The mobile computing device may be implemented as, for example, a mobile phone, a tablet device, a netbook, a laptop device, a video game console, a personal data assistant, a media player, a wearable computing device, or any computing system or mobile computing device where heat is a concern, heat management is an interest, and/or a slimmer profile may be desirable. As depicted in  FIG. 1 , a component layer stack  100  includes a main printed circuit board (PCB)  101  that houses various components that collectively perform a significant portion (if not all) of the processing and rendering in the computing device. These components may include processors, including but not limited to: one or more central processing units (CPUs), one or more graphics processing units (GPUs), one or more application processors (APs, and one or more special purpose processors. According to further embodiments, these components may also include memory devices (flash memory, RAM) and power amplification devices. 
     According to one or more embodiments, the PCB  101  may be centrally positioned (with respect to height or thickness) within the component layer stack  100 , between a front panel (collectively including, for example, a sensor array layer  115  and display panel  117 ), and a back panel (collective including, for example, a back cover  119  and a battery cover  121 ). The sensor array layer  115  may also include a camera module consisting of one or more camera lens and shutter devices. Sensor array layer  115  may also comprise a two dimensional array of one or more sensor devices configured to detect touch gestures and contact. In one or more embodiments, the display panel  117  may be implemented as a liquid crystal display (LCD), for example. Component layer stack  100  may also include a rechargeable power source such as a battery  107 , positioned on or near the same vertical plane as the PCB, i.e., likewise positioned between the front and back panels. 
     According to some embodiments, the component layer stack  100  may include one or more shield layers  105  configured to shield, obstruct, or block radio waves from reaching the components of the PCB  101 . Other components of the computer layer stack  100  may include a second, alternate, or supplementary “flex” PCB  109  for additional processing, rendering, or memory storage, a speaker module  113 , and a subscriber identity module (SIM) card reader  111  used for identification of subscribers in certain cellular data networks. 
     As depicted in  FIG. 1 , a component layer stack  100  also includes a mid-frame  103  that provides mechanical and structural support for the component layer stack  100 . Mid-frame  103  may be implemented as, for example, a metal frame consisting of a rigid metal or metallic alloy material. According to embodiments of the invention, one or more heat management structures  123  are intrinsically integrated within the mid-frame  103 . The heat management structures  123  may be implemented as, for example, one or more structures of a phase change material (PCM) that are operable to absorb heat produced by proximate processing components (of the PCB  101  for example). 
     In one or more further embodiments, the heat management structures  123  may also include one or more heat spreaders that work with the phase change material to more evenly distribute the absorbed heat and to eliminate hot spots. In one or more embodiments, the heat spreader can be comprised of graphite or other such material with relatively high thermal conductivity. In one or more embodiments, the one or more heat spreaders may be positioned within the mid-frame  103 , next to the phase change material, for example. In one or more alternate embodiments, the one or more heat spreaders may be affixed to the mid-frame  103  and between the mid-frame  103  and the processing components of the PCB  101 . 
     In one or more embodiments, the heat management structures  123  are entirely integrated within the mid-frame  103  such that no portion of the heat management structures  123  extends or protrudes beyond the dimensions of the mid-frame structure  103 , thereby providing heat management capability without compromising the profile of the mobile computing device. In further embodiments, the heat management structures  123  may be implemented from phase change materials such as: solid-liquid phase change materials, liquid-vapor phase change materials; and crystalline to amorphous structure phase change materials. According to one or more embodiments, the latent heat capacity of the PCM is substantially high. Other desirable qualities exhibited by a PCM according to embodiments of the invention include high thermal conductivity, low thermal expansion, and high specific heat. According to these embodiments, via the integration of the phase change materials, the supporting mid-frame  103  allows adjacent components (such as the PCB  101 ) to remain isothermal or substantially isothermal, through the phase change of the PCM (e.g., melting of the solid-liquid PCM, vaporization of the liquid-vapor PCM, and liquefying of the crystalline to amorphous structure PCM). 
     In one or more embodiments, firmware executing in various components of the component layer stack  100  are configured to throttle the performance of the corresponding component when heat produced during operation of a mobile computing device comprising the component layer stack  100  exceeds a pre-determined threshold. Components performing at higher levels naturally produce higher temperatures, and may be reduced or capped at a performance level below the highest performance level possible when the generated heat threshold is reached or exceeded. A threshold may correspond, for example, to a temperature at which the palpable heat emanating from the device becomes noticeable and/or uncomfortable for a user of the device. An alternate threshold may correspond to the upper range of safe operating limits corresponding to the particular component (e.g., as provided by the component&#39;s manufacturer). 
     Through the integration of the phase change materials within the mid-frame, the heat produced during operation can be absorbed for a portion (or entirety, depending on use) of the device&#39;s operation, with throttling of the performance being delayed or eliminated entirely. This allows the mobile computing device to maintain high performance levels longer than conventional implementations while maintaining the same vertical profile as just the frame itself. Other advantages include a shorter thermal transfer path from the PCB to the mid-frame by eliminating the thermal resistance of the solder or thermal adhesive. An additional benefit to such an implementation can be realized during assembly and testing since the risk of the heat management structures being peeled or scraped off during assembly, testing, and/or real application can be avoided. 
       FIG. 2  depicts a second exemplary component layer stack  200  of a mobile computing device, in accordance with various embodiments of the present invention. As depicted in  FIG. 2 , the second exemplary component layer stack  200  also includes a PCB  201 , a front panel (collectively including, for example, a sensor array layer  215  and display panel  217 ); a back panel (collective including, for example, a back cover  219  and a battery cover  221 ); a rechargeable power source such as a battery  207 ; and one or more shield layers  205 . Other components of the computer layer stack  200  may include a second, alternate, or supplementary “flex” PCB  209 , a speaker module  213 , and a subscriber identity module (SIM) card reader  211 . As depicted in  FIG. 2 , a component layer stack  200  also includes a mid-frame  203  and one or more heat management structures  223   a  are intrinsically integrated within the mid-frame  203 . In an embodiment, each of the elements  201 - 223  is similar to like numbered elements (e.g.,  101 - 123 ) described above with respect to  FIG. 1 . 
     In one or more embodiments, a component layer stack  200  also includes heat management structures  223   b  integrated in the battery cover  221 . According to such embodiments, heat produced during the operation of the battery  207  is absorbed by the heat management structures  223   b  such that the battery  207  may remain isothermal or substantially isothermal. The heat management structures  223   b  may be implemented as, for example, one or more structures of a phase change material (PCM), such as one or more sheets, slabs, or blocks. In an alternate embodiment, heat management structures  223   b  may be used in lieu of, rather than in addition to, heat management structures  223   a  within the mid-frame  203 . 
       FIG. 3  depicts a third exemplary component layer stack  300  of a mobile computing device, in accordance with various embodiments of the present invention. As depicted in  FIG. 3 , the third exemplary component layer stack  300  also includes a PCB  301 , a front panel (collectively including, for example, a sensor array layer  315  and display panel  317 ); a back panel (collective including, for example, a back cover  319  and a battery cover  321 ); a rechargeable power source such as a battery  307 ; and one or more shield layers  305 . Other components of the computer layer stack  300  may include a second, alternate, or supplementary “flex” PCB  309 , a speaker module  313 , and a subscriber identity module (SIM) card reader  311 . As depicted in  FIG. 3 , a component layer stack  300  also includes a mid-frame  303 , with one or more heat management structures  323   a  intrinsically integrated within the mid-frame  303 . In an embodiment, each of the elements  301 - 323   a  is similar to like numbered elements (e.g.,  101 - 123 ) described above with respect to  FIG. 1 . 
     In one or more embodiments, a component layer stack  300  also includes heat management structures  323   c  and  323   d  integrated in the shield layers  305 . According to such embodiments, heat produced during the operation of the mobile computing unit is absorbed by the heat management structures  323   c ,  323   d  such that adjacent components (such as the PCB  301 ) may remain isothermal or substantially isothermal. The heat management structures  323   c ,  323   d  may be implemented as, for example, one or more structures of a phase change material (PCM), such as one or more sheets, slabs, or blocks. In an alternate embodiment, heat management structures  323   c  and  323   d  may be used in lieu of, rather than in addition to, heat management structures  323   a  within the mid-frame  303 . 
       FIG. 4  depicts a fourth exemplary component layer stack of a mobile computing device, in accordance with various embodiments of the present invention. As depicted in  FIG. 4 , the fourth exemplary component layer stack  400  also includes a PCB  401 , a front panel (collectively including, for example, a sensor array layer  415  and display panel  417 ); a back panel (collective including, for example, a back cover  419  and a battery cover  421 ); a rechargeable power source such as a battery  407 ; and one or more shield layers  405 . Other components of the computer layer stack  400  may include a second, alternate, or supplementary “flex” PCB  409 , a speaker module  413 , and a subscriber identity module (SIM) card reader  411 . As depicted in  FIG. 4 , a component layer stack  400  also includes a mid-frame  403 , with one or more heat management structures  423   a  intrinsically integrated within the mid-frame  403 . In an embodiment, each of the elements  401 - 423   a  is similar to like numbered elements (e.g.,  101 - 123 ) described above with respect to  FIG. 1 . 
     In one or more embodiments, a component layer stack  400  also includes heat management structures  423   e  integrated in the front panel (specifically, the camera module in the sensor array layer  415 ). In one or more further embodiments, the camera module in the sensor array layer  415  includes one or more light-emitting diodes (LED) devices for generating flashes of light (e.g., during flash photography for example). Other LED devices may be used to provide a backlight for the display layer  417 . According to such embodiments, heat produced during the operation of the mobile computing unit (camera module and/or display) is absorbed by the heat management structures  423   e  such that adjacent components (such as the sensor array layer  415  and display panel  417 ) may remain isothermal or substantially isothermal. The heat management structures  423   e  may be implemented as, for example, one or more structures of a phase change material (PCM), such as one or more sheets, slabs, or blocks. In an alternate embodiment, heat management structures  423   e  may be used in lieu of, rather than in addition to, heat management structures  423   a  within the mid-frame  403 . 
       FIG. 5  depicts a fifth exemplary component layer stack of a mobile computing device, in accordance with various embodiments of the present invention. As depicted in  FIG. 5 , the fifth exemplary component layer stack  500  also includes a PCB  501 , a front panel (collectively including, for example, a sensor array layer  515  and display panel  517 ); a back panel (collective including, for example, a back cover  519  and a battery cover  521 ); a rechargeable power source such as a battery  507 ; and one or more shield layers  505 . Other components of the computer layer stack  500  may include a second, alternate, or supplementary “flex” PCB  509 , a speaker module  513 , a subscriber identity module (SIM) card reader  511 ; and a mid-frame  503 . As depicted in  FIG. 5 , one or more heat management structures  523   a ,  523   b ,  523   c ,  523   d , and  523   e  are intrinsically integrated within the mid-frame  503 , battery cover  521 , front panel (including sensor array/camera module  515 ), and shielding layers  505 , respectively. In an embodiment, each of the elements  501 - 523   a  is similar to like numbered elements (e.g.,  101 - 123 ) described above with respect to  FIG. 1 . Element  523   b  is similar to like numbered elements (e.g.,  223   b ) described above with respect to  FIG. 2 . Elements  523   c  and  523   d  are similar to like numbered elements 
       FIG. 6  depicts a three-dimensional view  600  of an exemplary mid-frame  601  in a mobile computing device with integrated heat management features  603 , in accordance with various embodiments of the present invention. As depicted in  FIG. 6 , the integrated heat management features  603  consists of a structure (such as a sheet, slab, or block) of phase change material encased entirely internally with respect to the mid-frame  601 . While depicted in such a configuration, it is to be understood that the integrated heat management features are well suited to varying other compositions. For example, alternate embodiments may be implemented as a chamber with liquid to vapor phase change materials, or a structure of crystalline to amorphous structure phase changing materials. 
       FIG. 7  depicts a block diagram  700  of an exemplary back panel  701  of a mobile computing device. As depicted in  FIG. 7 , the back panel  701  may have an integrated structure of thermal phase change material  703 . As discussed in the foregoing descriptions, the structure may consist of a sheet, slab, block or other generally flat arrangement sufficient to fit entirely within the dimensions of the back panel  701 . As depicted in  FIG. 7 , back Panel  701  may include an aperture  705  for a camera module, according to various embodiments. 
       FIG. 8  depicts a flowchart  800  of dissipating heat using heat management structures integrated within a mid-frame of a mobile computing device, in accordance with various embodiments of the present invention. Steps  810 - 850  describe exemplary steps of the flowchart  800  in accordance with the various embodiments herein described. 
     In one or more embodiments, a frame structure is formed at step  810 . In an embodiment, the frame structure may comprise a mechanical support structure, such as a mid-frame, and may be composed of a metal, such as aluminum. According to alternate embodiments, the frame structure may be implemented as a shield layer, a battery cover, or a front panel (including, in some embodiments, a sensor array and/or camera module). In an embodiment, the frame structure may be formed as a hollow shell with a cavity. At step  820 , heat management structures are integrated into the cavity of frame structure. In an embodiment, the heat management structures may be implemented as a sheet (or similar physical structure) of one or more phase change materials (PCMs). As described above, the PCMs may include, but are not limited to, solid-liquid PCMs, liquid-vapor PCMs, and crystalline-amorphous structure PCMs. Integrating may be performed by injecting (in liquid, amorphous, or vapor form) the corresponding PCM into the cavity of the frame structure formed in step  810 . At  830 , the PCM either solidifies (from a liquid), liquefies (from a vapor), or crystallizes (from an amorphous structure). The frame structure with the integrated heat management structures is then positioned at step  840  within the mobile computing device. Proper positioning depends on the particular purpose of the frame structure. A frame structure such as a mid-frame for example, may be disposed over a printed circuit board (PCB), or both a PCB and a battery. Likewise, a frame structure implemented as a battery cover may have at least a portion of the battery cover disposed in contact with a surface of a battery. Other frame structures may be positioned immediately next to the particular component(s) for which heat regulation is desirable. 
     In the foregoing specification, embodiments have been described with reference to numerous specific details that may vary from implementation to implementation. Thus, the sole and exclusive indicator of what is the invention, and is intended by the applicant to be the invention, is the set of claims that issue from this application, in the specific form in which such claims issue, including any subsequent correction. Hence, no limitation, element, property, feature, advantage, or attribute that is not expressly recited in a claim should limit the scope of such claim in any way. Accordingly, the specification and drawings are to be regarded in an illustrative rather than a restrictive sense.