Electronic devices

Abstract

An electronic device is provided having a thermal management system. The thermal management system includes a monolithic graphite element having a thickness of at least 150 microns. The graphite element has a thermal conductivity of at least about 700 W / mK. The graphite element does not have an internal adhesive, i.e., the graphite element is monolithic. The thermal management system is in operative contact with a heat source comprising a plurality of electronic components. Preferably, the plurality of electronic components are disposed on a stacked motherboard.

Description

Technical Field

[0001] (Cross - reference to Related Applications) This application claims the priority and benefit of U.S. Provisional Patent Application No. 63 / 074,876, filed on September 4, 2020, and all of the content of that application is incorporated herein by reference.

Background Art

[0002] With the Internet of Things (IoT), electronic devices are everywhere in daily life, especially portable electronic devices. Once, everyone carried a key, but now everyone has a cellular phone. Similar to the keys of the past, the cellular phone is an access point for our work and many leisure - time activities.

[0003] As cellular phones become increasingly central to activities, the functions of such phones have improved dramatically. Since 2007, "smart" cellular phones have become common, replacing phones dedicated to voice calls, text messages, and emails. With such functions, it is possible to conduct video conferences from anywhere in the world using a cellular phone, watch the latest movies, and have goods and services delivered to one's home from all corners of the world. The devices themselves are also changing, such as having multi - displays, high - resolution cameras, and foldable forms.

Summary of the Invention

Means for Solving the Problems

[0004] Disclosed herein is an electronic device. This device is described as a portable electronic device such as a cellular phone, a laptop computer, or a tablet, but this technology is applicable to any type of electronic device that requires thermal management of multiple electronic components and for which passive cooling is preferred or required rather than active cooling.

[0005] Active cooling refers to cooling techniques that transfer heat using a cooling medium such as heat pipes, vapor chambers, or fans. Passive cooling does not involve a cooling medium and is not a forced convection system.

[0006] An electronic device having a thermal management system is provided according to an aspect of the present disclosure. This thermal management system has a monolithic graphite element having a thickness of at least 150 microns. This graphite element has a thermal conductivity of at least about 700 W / mK. This graphite element does not have an internal adhesive (also called a binder). This thermal management system is in functional contact with a heat source comprising a plurality of electronic components. Preferably, these plurality of electronic components are arranged on a stacked motherboard.

[0007] An electronic device is provided, comprising a graphite element functionally in contact with a heat source, the heat source comprising a plurality of electronic components arranged on a stacked motherboard. The graphite element is preferably a monolithic graphite element having a thickness of at least about 150 microns. The graphite element has a thermal conductivity of at least about 700 W / mK. The graphite element does not have an internal adhesive (also called a binder). A preferred type of graphite is flexible graphite. The device may have a thickness of 15 mm or less.

[0008] According to aspects of the present disclosure, an electronic device is provided comprising a thermal management system including a flexible graphite element having a thickness of at least about 150 microns and a thermal conductivity of at least about 700 W / mK. Preferably, the flexible graphite element does not have an internal adhesive. The thermal management system may not have additional heat dissipation elements. Furthermore, the thermal management system is in functional contact with a heat source, which comprises a plurality of electronic components arranged on a stacked motherboard.

[0009] Unless otherwise specified, “functional contact” is used herein to mean that heat is dissipated from a heat source to a thermal management system, particularly to a graphite element. Unless otherwise specified, “direct functional contact” is used herein to mean that the two parts are physically adjacent or touching in a manner that allows functional contact to be established.

[0010] The aspects of this disclosure described above apply equally to all electronic devices of the following types and others, regardless of whether the electronic device is portable or not. [Brief explanation of the drawing]

[0011] [Figure 1] Figure 1 is a schematic diagram of an embodiment disclosed herein. [Figure 2] Figure 2 shows the internal view of the device used in the embodiment with the back cover removed. [Figure 3a] Figure 3a is an internal view of the device containing the test sample disclosed in the example. [Figure 3b] Figure 3b is an internal view of the device including the VC control disclosed in the embodiment. [Figure 4] Figure 4 shows graphs of screen temperature during normal operation ("no") and charging ("yes"). [Figure 5] Figure 5 is a graph showing the performance results for both normal operation ("no") and charging ("yes"). [Figure 6] Figure 6 is a graph showing the heat dissipation results from the CPU during both normal operation ("no") and charging ("yes"). [Figure 7] Figure 7 is a graph showing the heat dissipation results from the GPU during both normal operation ("no") and charging ("yes"). [Modes for carrying out the invention]

[0012] This disclosure relates to electronic devices. Such electronic devices include portable and stationary electronic devices. Examples of such devices include mobile phones, tablets, laptops, and wearable devices. These devices also include foldable devices. This applicable device also includes a device having a user interface on at least two main surfaces of the device (e.g., Nubia® X Phone). A phone with a second user interface is sometimes called a phone with a rear screen. In accordance with this disclosure, this electronic device may have a first user interface on a first main surface of the device and a second user interface on a second main surface of the device. This embodiment is also applicable to components of vehicles and other means of transport.

[0013] The thermal management systems of this disclosure are particularly advantageous for electronic devices having a thickness of 15 mm or less, preferably 12.5 mm or less. A preferred thickness is 10 mm or less. A non-limiting exemplary range of the preferred thickness of this device is from about less than 15 mm to about 5 mm. Specific devices included in this range include mobile phones, tablets, portable gaming systems, household goods, IoT devices, and wearable devices such as watches and medical devices.

[0014] The thermal management system applicable to the above device includes a flexible graphite element having a thickness of at least about 150 microns. This graphite element has an in-plane thermal conductivity of at least about 700 W / mK. This graphite element does not have an internal adhesive. The absence of an adhesive may also be called binderless. The thermal management system is in functional contact with a heat source comprising multiple electronic components. Preferably, the multiple electronic components are arranged on a stacked motherboard. This graphite element may be called "monolithic".

[0015] In other aspects of this disclosure, a thermal management system applicable to the above-described electronic device includes a graphite element functionally in contact with a heat source. This heat source includes a plurality of electronic components arranged on a stacked motherboard. The graphite element is preferably a monolithic graphite element having a thickness of at least about 150 microns. This graphite element has an in-plane thermal conductivity of at least about 700 W / mK. This graphite element may not have an internal adhesive. A preferred type of graphite is flexible graphite. Preferably, this device has a thickness of 15 mm or less. This device may have a thickness of 10 mm or less.

[0016] Another aspect of the present disclosure is an electronic device comprising a thermal management system including a graphite element having a thickness of at least about 150 microns and a thermal conductivity of at least about 700 W / mK. The graphite element may be a flexible graphite element. Preferably, the flexible graphite element does not have an internal adhesive. The thermal management system may not have additional heat dissipation elements. Furthermore, the thermal management system is in functional contact with a heat source. This heat source may be a heat source within an electronic device. This heat source may comprise a plurality of electronic components, where these plurality of electronic components are arranged on a stacked motherboard.

[0017] The general embodiments described above are further explained below. The following explanation is applicable to all of the general embodiments described above.

[0018] Regarding this graphite element, a preferred type of graphite is flexible graphite. Suitable examples of flexible graphite are NeoNxGen® flexible graphite (「NNG」) available from NeoGraf Solutions, LLC of Lakewood, Ohio, USA. Suitable grades of NNG include N-150, N-200, N-250, N-270, N-300, and P-150 and P-200 of the P series grades. Suitable flexible graphite may have a density within the range of 1.75 g / cm3 to 2.15 g / cm3 (including 1.85 g / cm3 to 2.10 g / cm3, 1.90 g / cm3 to 2.10 g / cm3, and 1.95 g / cm3 to 2.05 g / cm3). Suitable flexible graphite may have an electromagnetic interference (EMI) shielding effect of at least 100 dB (including at least 150 dB, at least 200 dB, at least 225 dB, and at least 250 dB) at a frequency of up to 6 GHz.

[0019] This graphite element comprises a single piece of graphite. This may also be referred to as a monolithic graphite piece. This can also be rephrased as this graphite element is not composed of two or more graphite pieces adhered using an adhesive or binder, or this graphite element does not have an adhesive or binder.

[0020] This graphite element has a thickness of at least about 150 microns. Other exemplary thicknesses include at least about 175 microns, at least about 200 microns, at least about 250 microns, and at least about 300 microns. In some applications, the thickness of this graphite element may be limited to about 500 microns, but this limitation does not apply to all applications.

[0021] This graphite element has an in-plane thermal conductivity of at least about 700 W / mK. If desired, this graphite element may have a thermal conductivity of at least about 800 W / mK. Further exemplary thermal conductivities include about 1000 W / mK or more. Other preferred thermal conductivities include about 1100 W / mK or more.

[0022] The through-plane thermal conductivity of this graphite element is less than about 6 W / mK, preferably less than about 5 W / mK.

[0023] This graphite element has a diffusivity of at least about 3.8 cm2 / s (including over 3.8 cm2 / s), preferably at least about 4 cm2 / s. Non-limiting examples of preferred ranges of diffusivity include about 5 - 10 cm2 / s.

[0024] Optionally, the graphite element of this thermal management system may have a protective coating on one or more of its outer surfaces. An example of a suitable coating type is a PET film.

[0025] As another optional element, this graphite element may have an adhesive applied to one or both of the major surfaces of the graphite element. The adhesive applied to this graphite element can be used to adhere the graphite element to a heat source. As a further optional embodiment, this adhesive is used to adhere the graphite element only to one or more electronic components constituting the heat source. In a further optional embodiment, this graphite element may include both one or more surfaces of the graphite element to which the protective coating is applied and an adhesive as an external coating of the thermal management system for adhering this system to a heat source. The embodiments disclosed herein are not limited to any of the foregoing components. Other optional components may be included as needed.

[0026] Optionally, the thermal management systems disclosed herein do not have to have one or more fins. Preferably, the thermal management system has a substantially planar body and does not have any portion of the thermal management system extending from the body on the plane in an orientation outward from the plane of the body.

[0027] In other optional configurations, preferably, the thermal management system does not include a fan, heat pipes, and / or a vapor chamber. In these embodiments, preferably, the thermal management system does not include an active cooling element or an active cooling medium.

[0028] Optionally, the surface area of ​​a portion of the thermal management system adjacent to a heat source is greater than the surface area of ​​the heat source functionally in contact with the thermal management system. Furthermore, this also applies to a graphite element, i.e., the graphite element has a larger surface area than the surface area of ​​the heat source functionally in contact with the thermal management system. Further specific embodiments according to the thermal management system and / or graphite element of the present disclosure have a first principal surface adjacent to the heat source that is functionally in contact with the heat source. This first principal surface has a first portion that is in direct functional contact with the heat source and a second portion that is not in direct functional contact with the heat source. The surface area of ​​this second portion is greater than the surface area of ​​the heat source. Alternatively, the surface area of ​​this second portion includes at least 10% of the surface area of ​​the heat source. Alternatively, the surface area of ​​this second portion includes at least 25% of the surface area of ​​the heat source. Further or alternatively, the surface area of ​​this second portion includes at least 50% of the surface area of ​​the heat source. Further or alternatively, the surface area of ​​this second portion includes at least 75% of the surface area of ​​the heat source. Alternatively, the surface area of ​​this second part may be approximately the same as the surface area of ​​the heat source, or may include approximately 100% of the surface area of ​​the heat source. Alternatively, the surface area of ​​this second part may be approximately the same as the surface area of ​​the motherboard, or may include approximately 100% of the surface area of ​​the motherboard. In a third configuration, the surface area of ​​this second part may be smaller than the surface area of ​​the heat source.

[0029] Figure 1 shows an electronic device 100 of the present disclosure, comprising a thermal management system 110 ("heat spread") having substantially the same surface area as the "heat source" 120. In this embodiment, the heat source 120 may include a stacked motherboard 130. As shown, the stacked motherboard 130 comprises a printed circuit board having at least one chip, such as a GPU, on one side of the motherboard 130, and at least a second chip (not shown), such as a CPU, on the other side of the motherboard 130, thereby forming the heat source 120 (any at least two chips may be used to form the motherboard 130). Any of the thermal management systems (110) described herein are positioned in functional contact with the heat source 120. The thermal management system 110 may be bonded to the heat source 120, for example, to at least one electronic component of the heat source 120. As shown in Figure 1, the thermal management system 110 (heat spread) has substantially the same surface area as the heat-generating chip (i.e., heat source). In addition, this thermal management system may be located on the device's midplate 140 (also called the "chassis"). In that case, the chosen thermal management system may also be bonded to the midplate 140. This may be achieved with or without a gap pad (not shown).

[0030] The thermal management system described in this disclosure is used to create electronic devices that minimize the device's touch temperature (also known as surface temperature). One standard for defining surface temperature is ASTM C1055. A summary of the standard cited in the September 2016 edition of Electronics Cooling Magazine is as follows:

[0031] ASTM C1055 (Standard Guideline for Conditions of Heating System Surfaces that Cause Contact Burn Injuries) recommends that surface temperatures be kept below 140°F. This is because the average person will not suffer irreversible burn injury from touching a 140°F surface for up to 5 seconds.

[0032] [Table 1]

[0033] According to ASTM C1055, it is even more preferable for electronic devices to operate at surface temperatures below 44°C (~111°F), which is considered the pain threshold (above "heat"). For comparison, the same article states that 46°C is considered a very high risk level by OSHA. The thermal management systems disclosed herein can be incorporated into electronic devices to ensure that the devices operate below the pain threshold.

[0034] The advantages that can be realized by using the thermal management system disclosed herein include one or more of the following: (1) Ease of use and simplification of the manufacture of the thermal management system; (2) The thermal management system has few inactive components such as internal adhesive layers or other insulating materials; (3) Ease of installation of the thermal management system; (4) The thermal management system has no lifespan; (5) The thermal management system is independent of the working medium (e.g., latent heat of evaporation / condensation of the vapor chamber medium). As a further advantage, the thermal management system may have a thickness of 200 microns or more and a thermal conductivity of at least 1000 W / mK in plane. [Examples]

[0035] A Samsung® Note 10 mobile phone ("Device") was used to evaluate the thermal management systems disclosed herein in comparison to currently available commercial thermal management systems ("OEM Thermal Management Systems"). One embodiment of the OEM Thermal Management Systems included a vapor chamber functionally in contact with the GPU and CPU on the motherboard. In this embodiment, the vapor chamber is adjacent to the midplate (chassis). Opposite the vapor chamber is a stacked motherboard containing the GPU and CPU. This motherboard is completely shielded. This embodiment is shown as "VC" in Figures 4-7. Other commercial options tested include a three-layer stack of 70-micron synthetic graphite, shown as "3 / sg" in Figures 4-7, and a four-layer stack of 70-micron synthetic graphite, shown as "4 / sg" in Figures 4-7. Adhesives were used between each layer of the 3 / sg and 4 / sg thermal management systems. All three alternatives are controls or collectively the "control group". Each control was glued to the motherboard during the test.

[0036] Figure 2 shows device 200 with its back cover removed, exposing the motherboard 210. In Figure 3a, the motherboard 210 has been removed and positioned to the right of device 200. One embodiment of the thermal management system disclosed herein ("Test Sample") 220 was placed on device 200 in a position where it was functionally in contact with this motherboard. This Test Sample had approximately the same surface area as the corresponding heat source on this motherboard. Figure 3b shows the setup of device 200 as a VC control embodiment, including the motherboard 210 and the vapor chamber heat spread 230.

[0037] This test sample contained a graphite element made of 270-micron thick NeoNxGen® flexible graphite, available from NeoGraf Solutions, LLC in Lakewood, Ohio. The graphite element in this test sample had an in-plane thermal conductivity of approximately 1100 W / mK or higher and an interplane thermal conductivity of less than approximately 5 W / mK. The test sample also included a plastic layer on each main surface and an adhesive on one side for bonding the test sample to the motherboard. The test sample had an overall thickness of approximately 330 microns. This test sample is shown as "NNG" in Figures 4-7.

[0038] The variables tested included heat dissipation from the GPU or CPU, the surface temperature of the device's screen, and the overall performance of the device. These variables were tested during normal device operation (indicated as "no" in Figures 4-7) and while the device was charging (indicated as "yes" in Figures 4-7).

[0039] UL's 3DMark - Slingshot Extreme was chosen for testing as a widely accepted benchmark for scoring the physical (CPU) and graphics (GPU) performance of high-end smartphones. To obtain steady-state test results, a professional version of 3DMark was purchased and installed on the device to allow for an infinite loop of the 90-second Slingshot Extreme benchmark test. All tests were conducted in a still air environment with strictly controlled ambient temperature and humidity. Measurable parameters included surface temperature via thermocouple, images via an IR camera (Fluke®, Model Ti55), internal component temperatures (CPU, GPU, etc.) via built-in thermistors, CPU and GPU clock frequencies, and system performance via the Slingshot Extreme benchmark score. The version used was OpenGL® ES3.1.

[0040] In each example, the thermal management system was used in the same location as the OEM control, including the vapor chamber (VC). This thermal management system was in thermal contact with both the GPU and the CPU ("heat source"). In addition to the above, this embodiment may further describe a phone screen, a midplate below the screen, and the thermal management system located adjacent to the midplate. This thermal interface was used to bring the thermal management system into thermal contact with the GPU and CPU on the motherboard. The back of this motherboard was covered with a plastic cover. Adjacent to the plastic cover was a wireless charger. This wireless charger was also adjacent to the back cover of the device.

[0041] Figure 4 is a graph showing the performance of the test sample, three control samples, and a sample without thermal management measures (indicated as "NoSpread"), testing the screen surface temperature variable over several runs. The test sample was the only embodiment in which the screen temperature was kept below 44°C in each test and its average, and this was true both during normal operation and charging. The test sample was the only experiment in which the screen temperature remained below the pain threshold. Surprisingly, the 3-layer synthetic graphite control (3 / sg) performed better at minimizing screen temperature than the 4-layer synthetic graphite control (4 / sg). Also interestingly, the vapor chamber control (VC) performed the worst at reducing screen temperature. It is a common understanding that active cooling, such as vapor chambers, is superior to passive cooling, such as that used in the test sample.

[0042] Regarding Figure 5, the performance of the devices was compared. As shown in Figure 5, the test samples showed the best average performance in both normal operation and charging, based on several runs, as well as minimizing screen temperature. Similar to the screen temperature results, it is thought that the test samples and the 4-layer synthetic graphite showed similar results because they have similar amounts of graphite. As is clear from Figure 5, this is not the case in each example.

[0043] Regarding Figure 6, the heat dissipation from the CPU, based on the average (maximum) CPU temperature measured over several runs, showed that the OEM control vapor chamber (VC) was the only instance where it outperformed the passive thermal management systems of the test sample and two control stacks (3 / sg and 4 / sg). In other experiments, the test sample exhibited the best heat dissipation from the CPU during normal operation.

[0044] Regarding Figure 7, the test sample exhibits the best heat dissipation from the GPU during normal operation, but lies on the opposite side of the spectrum during charging (with a slightly higher average temperature during charging). It is also interesting to see how well the 3-layer and 4-layer stack control groups (3 / sg and 4 / sg, respectively) agree on heat dissipation from the GPU between normal operation and charging. For these two control samples, process operations such as normal operation or charging during operation appear to have little effect on heat dissipation from the GPU.

[0045] All weights associated with the listed materials are based on their activity levels and, therefore, do not include solvents or by-products that may be present in commercially available materials unless otherwise specified.

[0046] Every reference in this disclosure to a singular feature or limitation includes the corresponding plural feature or limitation unless otherwise specified or explicitly stated in the context in which the reference is made. Therefore, in this disclosure, the words "a" or "an" are interpreted as including both singular and plural. Conversely, any reference to a plural item shall include the singular, where appropriate.

[0047] Unless otherwise specified (for example, by the use of the term "exactly"), all figures used in the specification and claims to express properties such as quantities, molecular weight, reaction conditions, etc., shall in all cases be understood to be modified by the word "approximately". Accordingly, unless otherwise specified, the numerical properties set forth in the following specification and claims are approximations that will vary depending on the desired properties to be obtained in the embodiments of the present invention.

[0048] Unless otherwise specified, thermal conductivity is provided at room temperature and standard pressure (1 atm), and if a standard test protocol such as the angstrom method, ASTM E1225, and / or ASTM D 5470 is known, it will instead be provided under the appropriate test conditions.

[0049] All combinations of steps in the methods or processes used herein may be performed in any order unless otherwise specified or explicitly stated otherwise in the context of the referenced combination.

[0050] All ranges and parameters disclosed herein (including, but not limited to, percentages, fractions, ratios, etc.) are understood to encompass all assumed subranges contained therein, including all numbers between the endpoints. For example, it should be considered that a range referred to as "1 to 10" includes any (and inclusive) subranges between the minimum value of 1 and the maximum value of 10, i.e., all subranges starting with a minimum value of 1 or greater (e.g., 1 to 6.1), subranges ending with a maximum value of 10 or less (e.g., 2.3 to 9.4, 3 to 8, 4 to 7), and finally, each number contained within the range: 1, 2, 3, 4, 5, 6, 7, 8, 9, and 10.

[0051] The thermal management systems and electronic devices of this disclosure are comprised of, or substantially comprised of, any additional or selective materials, components or limitations described herein or otherwise useful in thermal management systems and / or electronic devices, in addition to the substantial elements and limitations of the disclosure described herein.

[0052] Wherever the term “includes” is used in the specification or claims, it is intended to be inclusive, similar in meaning to the term “equipped with” when used as a conjunction in a claim. Furthermore, wherever the term “or” is used (e.g., A or B), it is intended to mean “A or B, or both A and B.” If the applicant intends to indicate “A or B only, and not both,” the term “A or B only, and not both” is used. Thus, the use of the term “or” in this specification is inclusive and non-exclusive.

[0053] In some embodiments, various inventive concepts can be used in combination with one another. In addition, certain elements presented in relation to a particular embodiment of this disclosure should be construed as being usable in all disclosed embodiments, provided that incorporating such elements does not conflict with the express conditions of that embodiment. Additional advantages and modifications will be readily apparent to those skilled in the art. Thus, this disclosure, in its broader aspects, is not limited to the specific details, representative apparatus, or examples presented herein. Accordingly, deviations from such details can be made without departing from the spirit or scope of the general inventive concept. [Explanation of Symbols]

[0054] 100 Electronic Devices 110 Thermal Management Systems 120 Heat source 130 Motherboards 140 Midplate 200 devices 210 Motherboards 220 test samples 230 Vapor Chamber Heat Spread

Claims

1. Equipped with a thermal management system and a heat source, The thermal management system includes a graphite element having a thickness of at least 150 microns, a density of 1.75 g / cm³ to 2.15 g / cm³, and a thermal conductivity of at least 1100 W / mK. The graphite element is binderless, The thermal management system functionally contacts the heat source, The heat source comprises electronic components arranged on the first surface of the stacked motherboards, The graphite element is installed on the second surface of the stacked motherboard. Electronic devices.

2. Having a thickness of 15 mm or less, The electronic device according to claim 1.

3. Having a thickness of 10 mm or less, The electronic device according to claim 1.

4. The aforementioned graphite element is monolithic. The electronic device according to claim 1.

5. The graphite element has a thickness of at least 270 microns. The electronic device according to claim 1.

6. The graphite element has a diffusion rate exceeding 3.8 cm² / s. The electronic device according to claim 1.

7. The first main surface has a first user interface, and the second main surface has a second user interface. The electronic device according to claim 1.

8. The aforementioned thermal management system does not have one or more fins. The electronic device according to claim 1.

9. The thermal management system has a substantially planar main body and does not have any portion of the thermal management system extending from the main body in an orientation outward from the plane of the main body. The electronic device according to claim 1.

10. The aforementioned thermal management system is (1) Without a fan, heat pipe, and vapor chamber, and / or (2) Without an active cooling medium, The electronic device according to claim 1.

11. The thermal management system has a first main surface adjacent to the heat source and functionally in contact with the heat source, The first main surface has a first portion that is in direct functional contact with the heat source and a second portion that is not in direct functional contact with the heat source. The electronic device according to claim 1.

12. The second part has a surface area larger than the surface area of ​​the heat source. The electronic device according to claim 11.

13. The second portion has a surface area of ​​at least 10% of the surface area of ​​the heat source. The electronic device according to claim 11.

14. The second portion has a surface area of ​​at least 50% of the surface area of ​​the heat source. The electronic device according to claim 11.

15. The second portion has a surface area of ​​at least 75% of the surface area of ​​the heat source. The electronic device according to claim 11.

16. The second part has a surface area that is approximately the same as the surface area of ​​the heat source. The electronic device according to claim 11.

17. The aforementioned thermal management system does not have additional heat dissipation elements. The electronic device according to claim 1.

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