WO2023033785A1

WO2023033785A1 - Electronic devices with enclosure structure and methods for forming the same

Info

Publication number: WO2023033785A1
Application number: PCT/US2021/048219
Authority: WO
Inventors: Xiaopeng Huang
Original assignee: Zeku, Inc.
Priority date: 2021-08-30
Filing date: 2021-08-30
Publication date: 2023-03-09

Abstract

An electronic device includes an enclosure structure, a first circuit board disposed in the enclosure structure, and a phase change layer disposed in the enclosure structure in contact with the first circuit board. The phase change layer includes a phase change material, and the phase change material has a phase transition when an operational temperature of the electronic device changes.

Description

ELECTRONIC DEVICES WITH ENCLOSURE STRUCTURE AND METHODS FOR FORMING THE SAME

BACKGROUND

[0001] Embodiments of the present disclosure relate to electronic devices with an enclosure structure and methods for forming the same.

[0002] Consumer electronic devices usually consist of many electronic parts, such as circuit boards or integrated circuits (ICs). The thermal control of the consumer electronic devices becomes an important issue when the size of the consumer electronic devices gets smaller and more electronic parts need to be packed into a smaller space. Furthermore, water damage prevention is another important issue for consumer electronic devices to improve their reliability.

SUMMARY

[0003] Embodiments of electronic devices with an enclosure structure and methods for forming the same are disclosed herein.

[0004] In some embodiments, an electronic device includes an enclosure structure, a first circuit board disposed in the enclosure structure, and a phase change layer disposed in the enclosure structure in contact with the first circuit board. The phase change layer includes a phase change material, and the phase change material has a phase transition when an operational temperature of the electronic device changes.

[0005] In some embodiments, an electronic device includes an enclosure structure, a first circuit board disposed in the enclosure structure, and a second circuit board disposed in the enclosure structure stacking on the first circuit board. A first gap is formed between the first circuit board and the second circuit board. A phase change layer is filled in the first gap in direct contact with the first circuit board and the second circuit board. The phase change layer includes a phase change material.

[0006] In some embodiments, a method for forming an electronic device is disclosed. An enclosure structure is formed, and a first circuit board is disposed in the enclosure structure. A phase change layer in a liquid state is filled into a first gap formed between the enclosure structure and the first circuit board. The phase change layer is solidified into a solid state.

[0007] These illustrative embodiments are mentioned not to limit or define the disclosure, but to provide examples to aid understanding thereof. Additional embodiments are discussed in the Detailed Description, and further description is provided there.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008] The accompanying drawings, which are incorporated herein and form a part of the specification, illustrate embodiments of the present disclosure and, together with the description, further serve to explain the principles of the present disclosure and to enable a person skilled in the pertinent art to make and use the present disclosure.

[0009] FIG. 1 illustrates a cross-section of an electronic device, according to some embodiments of the present disclosure.

[0010] FIG. 2 illustrates a time-temperature relationship diagram of an electronic device, according to some embodiments of the present disclosure.

[0011] FIG. 3 illustrates a cross-section of an electronic device, according to some embodiments of the present disclosure.

[0012] FIG. 4 illustrates a cross-section of an electronic device, according to some embodiments of the present disclosure.

[0013] FIG. 5 illustrates a cross-section of an electronic device, according to some embodiments of the present disclosure.

[0014] FIG. 6 illustrates a cross-section of an electronic device, according to some embodiments of the present disclosure.

[0015] FIG. 7 illustrates a flowchart of a method for forming an electronic device, according to some embodiments of the present disclosure.

[0016] FIG. 8 illustrates a mobile device, according to some embodiments of the present disclosure.

DETAILED DESCRIPTION

[0017] Although specific configurations and arrangements are discussed, it should be understood that this is done for illustrative purposes only. A person skilled in the pertinent art will recognize that other configurations and arrangements can be used without departing from the spirit and scope of the present disclosure. It will be apparent to a person skilled in the pertinent art that the present disclosure can also be employed in a variety of other applications.

[0018] It is noted that references in the specification to “one embodiment,” “an embodiment,” “an example embodiment,” “some embodiments,” “certain embodiments,” etc., indicate that one or more embodiments described may include a particular feature, structure, or characteristic, but every embodiment may not necessarily include the particular feature, structure, or characteristic. Moreover, such phrases do not necessarily refer to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it would be within the knowledge of a person skilled in the pertinent art to affect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described.

[0019] In general, terminology may be understood at least in part from usage in context. For example, the term “one or more” as used herein, depending at least in part upon context, may be used to describe any feature, structure, or characteristic in a singular sense or may be used to describe combinations of features, structures or characteristics in a plural sense. Similarly, terms, such as “a,” “an,” or “the,” again, may be understood to convey a singular usage or to convey a plural usage, depending at least in part upon context. In addition, the terms “based on,” “based upon,” and terms with similar meaning may be understood as not necessarily intended to convey an exclusive set of factors and may, instead, allow for existence of additional factors not necessarily expressly described, again, depending at least in part on context.

[0020] Various aspects of the present disclosure will now be described with reference to various apparatus and methods. These apparatus and methods will be described in the following detailed description and illustrated in the accompanying drawings by various blocks, modules, units, components, circuits, steps, operations, processes, algorithms, etc. (collectively referred to as “elements”). These elements may be implemented using electronic hardware, firmware, computer software, or any combination thereof. Whether such elements are implemented as hardware, firmware, or software depends upon the particular application and design constraints imposed on the overall system.

[0021] As the demand for enhancing functionality and reducing transistor sizes on consumer electronic devices continues to increase, resulting in a rapid increase in power density. However, the operational temperature range of the transistor is limited, which limits the junction temperature of the chips. Accordingly, a heat dissipation solution must be designed to dissipate the heat generated by the electronic chips. The purpose of all of the passive cooling solutions is to increase the coefficient of thermal spreading (CTS) of the electronic devices. Since the consumer electronic devices may occasionally or often contact human skin, the skin temperature of the consumer electronic devices must be lower than that of industry standards, which in turn constitutes a physical limitation on the maximum power that these devices can hold for a long time. In the present disclosure, the junction temperature of the chips inside the consumer electronic devices and the skin temperature of the device housing are improved. The implementations of the present disclosure include, but are not limited to, cell phones, tablets, smart watches, smart speakers, laptop computers, wearable electronic products, fast chargers, etc. The junction temperature of the chips is the maximum temperature within the chips when it is running at a specific time. The skin temperature is the maximum temperature of the outer shell surface of consumer electronic devices. [0022] FIG. 1 illustrates a cross-section of an electronic device 100, according to some embodiments of the present disclosure. Electronic device 100 includes an enclosure structure 102, a first circuit board 104, a second circuit board 106, and a phase change layer 108. First circuit board 104 and second circuit board 106 are disposed in enclosure structure 102. In some embodiments, first circuit board 104 and second circuit board 106 may have chips 112 mounted. In some embodiments, two sides of first circuit board 104 and second circuit board 106 may both have chips 112 mounted. It is understood that chips 112 and circuit boards 104/106 may form any kind of applications in the consumer electronic devices, e.g., SoC, ASIC, communication circuit, power management circuit, CPU, memory, etc. First circuit board 104 and second circuit board 106 may be one-layer printed circuit board assembly (PCB A), multi-layer PCB As, flexible PCB As, or any suitable applications.

[0023] Phase change layer 108 is disposed in enclosure structure 102 in contact with first circuit board 104 and/or second circuit board 106. Phase change layer 108 includes a phase change material (PCM). PCM is a thermal energy storage material that has the characteristics of cyclic heat absorption and release. PCMs are substances that absorb or release large amounts of so-called “latent” heat when they go through a change in their physical state, i.e., from solid to liquid and vice versa. In a heating process or a cooling process, this phase change takes place as soon as the material reaches its specific phase change temperature. During the latent heat absorption or latent heat release, the temperature of the PCM remains almost constant. The PCM’s property of absorbing and releasing large amounts of heat in a controlled way can be utilized to improve the thermal performance of various consumer electronic devices. The latent heat absorbed by the PCM can be stored therein. PCM has a greater thermal storage capacity due to its latent heat being 1-2 orders of magnitude higher than sensible heat. Therefore, PCMs are considered to be highly efficient thermal storage means. In some embodiments, PCM may include organic (carbon- containing) materials or salt hydrates. In some embodiments, PCM may include paraffin waxes, non-paraffin organics, hydrated salts, metallics, or other suitable materials.

[0024] In some embodiments, phase change layer 108 may include paraffin waxes and have a melt temperature between -20 Celsius and over 100 Celsius. In some embodiments, phase change layer 108 may include non-paraffin organics and have a melt temperature between 5 Celsius and over 120 Celsius. In some embodiments, phase change layer 108 may include hydrated salts and have a melt temperature between 0 Celsius and over 100 Celsius. In some embodiments, phase change layer 108 may include metallics and have a melt temperature between 150 Celsius and over 800 Celsius. In some embodiments, phase change layer 108 may include paraffin waxes that have a high heat of fusion per unit weight, have a large melting point selection, provide dependable cycling, are non-corrosive, and are chemically inert, and therefore can be applied over a wide temperature range.

[0025] Other kinds of PCMs may also be applied in electronic device 100, according to some embodiments of the present disclosure. For example, hydrated salts have a high heat of fusion per unit weight and volume, have a relatively high thermal conductivity for non-metals, and show small volume changes between solid and liquid phases. For another example, non-paraffin organics and liquid-to-gas phase change materials are also available to be applied in electronic device 100. For a further example, metallic PCMs may be used at high temperatures.

[0026] The PCMs (in the phase change layer 108) mentioned in the present application may not be just one material with a fixed chemical formula. In some embodiments, the PCMs may be a compound from several materials with different formulas for desired properties. For example, paraffin wax consists of 100% n-Docosane (C22H46) has a melting temperature of 44 Celsius, and paraffin wax consists of 100% n-Tetracosane (C24H50) has a melting temperature of 50.5 Celsius. Thus, a mix of these two kinds of paraffin waxes may have a melting temperature in between depending on the proportion of each.

[0027] When PCMs change from the solid state to the liquid state, PCMs behave like sensible heat storage (SHS) materials. Their temperature rises as they absorb heat. When PCMs reach their phase change temperature (melting point), they absorb large amounts of heat at an almost constant temperature until all the material is melted. When the ambient temperature around the liquid PCMs falls, the PCMs solidify, releasing their stored latent heat.

[0028] In some embodiments, electronic device 100 further includes at least one heat sink 110 in enclosure structure 102. Heat sink 110 may be a passive heat exchanger that transfers the heat generated by first circuit board 104, second circuit board 106, and chips 112 to the external environment, where it is dissipated away from electronic device 100. Heat sink 110 is deposed in contact with enclosure structure 102. In some embodiments, heat sink 110 may be deposed on top and bottom inner sidewalls of enclosure structure 102. In some embodiments, heat sink 110 may be deposed on all inner sidewalls of enclosure structure 102. In some embodiments, enclosure structure 102 and heat sink 110 may have an opening for filling phase change layer 108 into enclosure structure 102. In some embodiments, enclosure structure 102 and/or heat sink 110 may be made of materials with good thermal conductivity. In some embodiments, enclosure structure 102 and/or heat sink 110 may be made of aluminum, aluminum alloy, copper, graphite, graphene, or other suitable materials.

[0029] In some embodiments, electronic device 100 also includes a supporting frame 114 disposed between first circuit board 104 and second circuit board 106 to form a gap between first circuit board 104 and second circuit board 106. In some embodiments, supporting frame 114 may be formed by nonconductive materials. In some embodiments, supporting frame 114 may be made of thermal conductive materials and may function as a heat sink as well.

[0030] In some embodiments, phase change layer 108 may be filled in the gap between first circuit board 104 and top heat sink 110. In some embodiments, phase change layer 108 may be filled in the gap between second circuit board 106 and bottom heat sink 110. In some embodiments, phase change layer 108 may be filled in the gap between first circuit board 104 and second circuit board 106. Phase change layer 108 is deposed in enclosure structure 102 in direct contact with chips 112, first circuit board 104, and second circuit board 106. The description of “in direct contact” means two objects or two elements are in direct contact with no other objects or elements in the middle. In other words, phase change layer 108 fills all voids between first circuit board 104 and top heat sink 110, between second circuit board 106 and bottom heat sink 110, and between first circuit board 104 and second circuit board 106. Therefore, phase change layer 108 may directly contact the heat sources to provide not only good heat conduction function but also a waterproof effect.

[0031] It is understood that first circuit board 104, second circuit board 106, phase change layer 108, and chips 112 may be arranged vertically, horizontally, or in any directions, in enclosure structure 102. The posture of the elements located in enclosure structure 102 is not limited here. In addition, in some embodiments, the elements or devices mounted on first circuit board 104 or second circuit board 106, such as chips 112, may also directly contact top heat sink 110 or supporting frame 114 for better heat dissipation.

[0032] FIG. 2 illustrates a time-temperature relationship diagram 200 of an electronic device, according to some embodiments of the present disclosure. In FIG. 2, curve 202 illustrates the time-temperature relationship of an electronic device without phase change layer 108, and curve 204 illustrates the time-temperature relationship of electronic device 100 with phase change layer 108. As the operation time increases, the accumulated heat of the electronic device without phase change layer 108 makes the temperature of the electronic device gradually increase, as shown by curve 202.

[0033] By filling phase change layer 108 in electronic device 100, as the operation time increases, the accumulated heat of electronic device 100 will be absorbed by phase change layer 108 to change the state of phase change layer 108. For example, phase change layer 108 may be changed from a solid state to a liquid state by absorbing the accumulated heat of electronic device 100 without increasing its temperature. Hence, as shown by curve 204 in FIG. 2, the temperature of electronic device 100 has a nearly flat range which delays the temperature rise and allows longer operation time before a temperature threshold.

[0034] Phase change layer 108 has a phase transition when an operational temperature of electronic device 100 changes. In some embodiments, phase change layer 108 changes from a first phase, e.g., solid state, to a second phase, e.g., liquid or paste state, when the operational temperature of electronic device 100 changes from a low operational temperature to a high operational temperature. In some embodiments, phase change layer 108 changes back from the second phase, e.g., liquid or paste state, to the first phase, e.g., solid state, when the operational temperature of electronic device 100 changes from the high operational temperature back to the low operational temperature. During the change of the states, phase change layer 108 may absorb and release the latent heat to keep the temperature of the electronic device slowly changed.

[0035] The temperature of electronic device 100 depends on the thermal resistance from the components to the environment, and the heat dissipated by the components. Heat dissipation of electronic device 100 may be from the components (chips 112) to the PCBAs (first circuit board 104 and second circuit board 106), to heat dissipation media (phase change layer 108), to the heat sink (heat sink 110), to the housing (enclosure structure 102), and furthermore, to human skin or ambient objects or airflow provided by a fan or just natural convection, but in all instances, eventually to the environment.

[0036] Electronic device 100 includes phase change layer 108, and phase change layer 108 has a predetermined melting point (state changing point) that can absorb or release the latent heat of chips 112, first circuit board 104, and second circuit board 106. Hence, electronic device 100 has the advantages that can lower the chip junction temperature, lower the skin temperature, and increase the operation time to reach a threshold temperature. Time to the threshold (ToT) temperature is the time that the electronic device takes for the junction temperature or the skin temperature to reach its own thresholds posed by design standards under a step power stimulus representing a user scenario of a device, e.g., playing a game on a phone.

[0037] In addition, by using phase change layer 108 to fully cover chips 112, first circuit board 104, and second circuit board 106, electronic device 100 can prevent water from causing damage to critical electrical components. Furthermore, power consumption is saved by reducing leakage due to chip junction temperature reduction. Since phase change layer 108 is in liquid/paste form at warm temperature, it is easy to incorporate into various structures.

[0038] FIGs. 3-6 illustrate cross-sections of electronic device 100 at different stages of a manufacturing process, according to some embodiments of the present disclosure. FIG. 7 illustrates a flowchart of a method 700 for forming electronic device 100, according to some embodiments of the present disclosure. For the purpose of better describing the present disclosure, the cross-sections of electronic device 100 in FIGs. 3-6 and method 700 in FIG. 7 will be discussed together. It is understood that the operations shown in method 700 are not exhaustive and that other operations may be performed as well before, after, or between any of the illustrated operations. Further, some of the operations may be performed simultaneously, or in a different order than shown in FIGs. 3-6 and FIG. 7.

[0039] As shown in FIG. 3 and operation 702 in FIG. 7, enclosure structure 102 is formed. In some embodiments, enclosure structure 102 may be formed by materials with good heat dissipation performance, which can quickly conduct heat to the environment. For example, when electronic device 100 needs to quickly dissipate heat through air convection, enclosure structure 102 could be made of metal materials. In some embodiments, enclosure structure 102 may be formed by materials with a good heat insulation effect, which can insulate the heat from the contacting surface of electronic device 100. For example, when electronic device 100 is a cellphone that usually contacts the human skin, enclosure structure 102 could be made by heat insulation materials.

[0040] In some embodiments, enclosure structure 102 may include some holes or slits 116 on the sidewall for filling the PCM in later operations. In some embodiments, enclosure structure 102 may include a lid allowing filling the PCM first and then covering enclosure structure 102 with the lid.

[0041] As shown in operation 704 in FIG. 7, first circuit board 104 is disposed in enclosure structure 102. In some embodiments, more than one circuit board, e.g., second circuit board 106, may be also disposed in enclosure structure 102. In some embodiments, first circuit board 104 and second circuit board 106 are separated by supporting frame 114. In some embodiments, heat sink 110 may be disposed on inner sidewalls of enclosure structure 102. As shown in FIG. 3, after disposing heat sink 110, supporting frame 114, first circuit board 104, and second circuit board 106 in enclosure structure 102, the gaps, or called voids, are formed between heat sink 110 and first circuit board 104, between heat sink 110 and second circuit board 106, and between first circuit board 104 and second circuit board 106.

[0042] As shown in FIG. 4 and operation 706 in FIG. 7, phase change layer 108 in the liquid state is filled into gaps formed between heat sink 110 and first circuit board 104, between heat sink 110 and second circuit board 106, and between first circuit board 104 and second circuit board 106. In some embodiments, phase change layer 108 in the liquid state may be filled into gaps formed between heat sink 110 and first circuit board 104, and/or between heat sink 110 and second circuit board 106, as shown in FIG. 5. In some embodiments, phase change layer 108 in the liquid state may be filled into gaps formed between first circuit board 104 and second circuit board 106, as shown in FIG. 6. In some embodiments, phase change layer 108, formed by PCM, is filled in enclosure structure 102 with liquid or paste form of PCM at a warm temperature to have chips 112, first circuit board 104, and second circuit board 106 immersed in the PCM.

[0043] In some embodiments, PCMs filled into gaps formed between heat sink 110 and first circuit board 104, between heat sink 110 and second circuit board 106, and between first circuit board 104 and second circuit board 106, may include the same material. In some embodiments, PCMs filled into gaps formed between heat sink 110 and first circuit board 104, between heat sink 110 and second circuit board 106, and between first circuit board 104 and second circuit board 106, may include different materials. In some embodiments, PCMs filled into gaps formed between heat sink 110 and first circuit board 104, and between heat sink 110 and second circuit board 106, may include the same material which is different from PCMs filled into gaps formed between first circuit board 104 and second circuit board 106.

[0044] Then, as shown in operation 708 in FIG. 7, the PCM is solidified at a lower temperature. In some embodiments, phase change layer 108 is solidified at the ambient temperature. Phase change layer 108, formed by the immersive PCM, replaces the air in the gaps between heat sink 110 and first circuit board 104, between heat sink 110 and second circuit board 106, and between first circuit board 104 and second circuit board 106. Hence, phase change layer 108 may fully cover and surround chips 112, first circuit board 104, and second circuit board 106 to significantly improve the heat transfer to outer surface and provide a balance of the heat flow at the two sides of chips. The junction temperature of chips 112 is reduced as well.

[0045] Phase change layer 108, starts to absorb the heat dissipation from the heatgenerating electronic elements, e.g., chips 112, first circuit board 104, and second circuit board, at its melting point without increasing its temperature until its latent heat storage capacity is used up. The heat absorption for the isothermal phase change, which is 1-2 order of magnitude higher than the sensible heat of a non-PCM application, extends the maximum performance period of running the heavy -load scenarios of consumer electronic devices. Therefore, electronic device 100 can lower the junction temperature, lower the leakage power and lower the maximum skin temperature with balanced heat flow.

[0046] Electronic device 100 and method 700 for forming electronic device 100 disclosed herein may be implemented by any consumer electronic device, including, but not limited to, cell phones, tablets, smart watches, smart speakers, laptop computers, wearable electronic products, fast chargers, etc. For example, FIG. 8 illustrates a mobile device 800, according to some embodiments of the present disclosure.

[0047] As shown in FIG. 8, mobile device 800 may be a cellphone 802. In some embodiments, cellphone 802 may be electronic device 100 including enclosure structure 102, first circuit board 104, second circuit board 106, and phase change layer 108. In other embodiments, electronic device 100 including enclosure structure 102, first circuit board 104, second circuit board 106, and phase change layer 108 may be one of the parts of cellphone 802. Chips 112 and circuit boards 104/106 may form various circuits of cellphone 802, such as communication circuit, power management circuit, CPU, memory, etc.

[0048] Phase change layer 108, including the PCM, is disposed in cellphone 802 in contact with chips 112, first circuit board 104, and/or second circuit board 106. When cellphone 802 is in a heavy-loading operation status, the communication circuit, power management circuit, CPU and/or memory may generate a lot of heat, and PCMs may absorb large amounts of the latent heat when PCMs go through a change in their physical state, i.e., from solid to liquid. When cellphone 802 is in idle status, PCMs may release the latent heat and cause PCMs to change their physical state from liquid to solid.

[0049] The passive cooling solution using phase change layer 108 in cellphone 802 may increase the coefficient of thermal spreading of cellphone 802. When cellphone 802 contacts human skin, the skin temperature of cellphone 802 could be lower than that of industry standards. In the present disclosure, the junction temperature of the chips inside cellphone 802 and the skin temperature of cellphone 802 are therefore improved. Hence, cellphone 802 has the advantages that lowers chip junction temperature, lowers skin temperature, and increases operation time to reach a threshold temperature.

[0050] In addition, by using phase change layer 108 to fully cover chips 112, first circuit board 104, and second circuit board 106 in cellphone 802, cellphone 802 can prevent water from causing damage to critical electrical components. Furthermore, the power consumption of cellphone 802 may be saved by reducing leakage due to chip junction temperature reduction. Since phase change layer 108 is in liquid/paste form at a warm temperature, it is easy to incorporate into various structures of cellphone 802 design.

[0051] According to one aspect of the present disclosure, an electronic device includes an enclosure structure, a first circuit board disposed in the enclosure structure, and a phase change layer disposed in the enclosure structure in contact with the first circuit board. The phase change layer includes a phase change material, and the phase change material has a phase transition when an operational temperature of the electronic device changes.

[0052] In some embodiments, the phase change layer changes from a first phase to a second phase when the operational temperature of the electronic device changes from a first operational temperature to a second operational temperature. In some embodiments, the phase change layer changes from the second phase to the first phase when the operational temperature of the electronic device changes from the second operational temperature to the first operational temperature. In some embodiments, the first phase of the phase change layer is a solid state, and the second phase of the phase change layer is a liquid state or a paste state.

[0053] In some embodiments, the phase change layer fills in a first gap between the enclosure structure and the first circuit board. In some embodiments, the electronic device further includes a heat sink disposed in the enclosure structure in contact with sidewalls of the enclosure structure. The phase change layer is disposed between the heat sink and the first circuit board.

[0054] In some embodiments, the electronic device further includes a second circuit board disposed in the enclosure structure, and a supporting frame disposed between the first circuit board and the second circuit board to form a second gap between the first circuit board and the second circuit board. The phase change layer is further disposed in the second gap between the first circuit board and the second circuit board.

[0055] In some embodiments, the electronic device further includes at least one chip mounted on the first circuit board. The phase change layer is in direct contact with surfaces of the chip and the circuit board.

[0056] According to another aspect of the present disclosure, an electronic device includes an enclosure structure, a first circuit board disposed in the enclosure structure, and a second circuit board disposed in the enclosure structure stacking on the first circuit board. A first gap is formed between the first circuit board and the second circuit board. A phase change layer is filled in the first gap in direct contact with the first circuit board and the second circuit board. The phase change layer includes a phase change material.

[0057] In some embodiments, the electronic device further includes a supporting frame disposed between the first circuit board and the second circuit board to form the first gap. In some embodiments, the phase change layer has a phase transition when an operational temperature of the electronic device changes. In some embodiments, the phase change layer changes from a first phase to a second phase when the operational temperature of the electronic device changes from a first operational temperature to a second operational temperature.

[0058] In some embodiments, the electronic device further includes a heat sink disposed in the enclosure structure in contact with sidewalls of the enclosure structure. The phase change layer is further disposed between the heat sink and the first circuit board. In some embodiments, the phase change layer is further disposed between the heat sink and the second circuit board.

[0059] According to still another aspect of the present disclosure, a method for forming an electronic device is disclosed. An enclosure structure is formed, and a first circuit board is disposed in the enclosure structure. A phase change layer in a liquid state is filled into a first gap formed between the enclosure structure and the first circuit board. The phase change layer is solidified into a solid state.

[0060] In some embodiments, a heat sink is formed in the enclosure structure in contact with sidewalls of the enclosure structure, and the phase change layer is filled between the heat sink and the first circuit board. In some embodiments, the phase change layer in the liquid state is provided into the first gap to fill voids between the enclosure structure and the first circuit board. In some embodiments, the phase change layer in the liquid state fully covers the first circuit board. [0061] In some embodiments, a second circuit board is disposed in the enclosure structure. The second circuit board is stacked on the first circuit board, and a second gap is formed between the first circuit board and the second circuit board. The phase change layer in the liquid state is filled into the second gap. The phase change layer is solidified into the solid state.

[0062] In some embodiments, the first circuit board and the second circuit board are separated by a supporting frame, and the second gap is formed between the supporting frame, the first circuit board, and the second circuit board.

[0063] The foregoing description of the specific embodiments will reveal the general nature of the present disclosure that others can, by applying knowledge within the skill of the art, readily modify and/or adapt for various applications such specific embodiments, without undue experimentation, without departing from the general concept of the present disclosure. Therefore, such adaptations and modifications are intended to be within the meaning and range of equivalents of the disclosed embodiments, based on the teaching and guidance presented herein. It is to be understood that the phraseology or terminology herein is for the purpose of description and not of limitation, such that the terminology or phraseology of the present specification is to be interpreted by the skilled artisan in light of the teachings and guidance.

[0064] Embodiments of the present disclosure have been described above with the aid of functional building blocks illustrating the implementation of specified functions and relationships thereof. The boundaries of these functional building blocks have been arbitrarily defined herein for the convenience of the description. Alternate boundaries can be defined so long as the specified functions and relationships thereof are appropriately performed.

[0065] The Summary and Abstract sections may set forth one or more but not all exemplary embodiments of the present disclosure as contemplated by the inventor(s), and thus, are not intended to limit the present disclosure and the appended claims in any way.

[0066] Various functional blocks, modules, and steps are disclosed above. The particular arrangements provided are illustrative and without limitation. Accordingly, the functional blocks, modules, and steps may be re-ordered or combined in different ways than in the examples provided above. Likewise, certain embodiments include only a subset of the functional blocks, modules, and steps, and any such subset is permitted.

[0067] The breadth and scope of the present disclosure should not be limited by any of the above-described exemplary embodiments, but should be defined only in accordance with the following claims and their equivalents.

Claims

WHAT IS CLAIMED IS:

1. An electronic device, comprising: an enclosure structure; a first circuit board disposed in the enclosure structure; and a phase change layer disposed in the enclosure structure in contact with the first circuit board, wherein the phase change layer comprises a phase change material, and the phase change material has a phase transition when an operational temperature of the electronic device changes.

2. The electronic device of claim 1, wherein the phase change layer changes from a first phase to a second phase when the operational temperature of the electronic device changes from a first operational temperature to a second operational temperature.

3. The electronic device of claim 2, wherein the phase change layer changes from the second phase to the first phase when the operational temperature of the electronic device changes from the second operational temperature to the first operational temperature.

4. The electronic device of any of claims 2-3, wherein the first phase of the phase change layer is a solid state and the second phase of the phase change layer is a liquid state or a paste state.

5. The electronic device of claim 1, wherein the phase change layer fills in a first gap between the enclosure structure and the first circuit board.

6. The electronic device of claim 1, further comprising: a heat sink disposed in the enclosure structure in contact with at least one sidewall of the enclosure structure, wherein the phase change layer is disposed between the heat sink and the first circuit board.

7. The electronic device of claim 5, further comprising: a second circuit board disposed in the enclosure structure; and a supporting frame disposed between the first circuit board and the second circuit board to form a second gap between the first circuit board and the second circuit board, wherein the phase change layer is further disposed in the second gap between the first circuit board and the second circuit board.

8. The electronic device of claim 1, further comprising at least one chip mounted on the first circuit board, wherein the phase change layer is in direct contact with at least one surface of the chip and the first circuit board.

9. An electronic device, comprising: an enclosure structure; a first circuit board disposed in the enclosure structure; a second circuit board disposed in the enclosure structure stacking on the first circuit board, wherein a first gap is formed between the first circuit board and the second circuit board; and a phase change layer filled in the first gap in direct contact with the first circuit board and the second circuit board, wherein the phase change layer comprises a phase change material.

10. The electronic device of claim 9, further comprising: a supporting frame disposed between the first circuit board and the second circuit board to form the first gap.

11. The electronic device of claim 9, wherein the phase change layer has a phase transition when an operational temperature of the electronic device changes.

12. The electronic device of claim 11, wherein the phase change layer changes from a first phase to a second phase when the operational temperature of the electronic device changes from a first operational temperature to a second operational temperature.

13. The electronic device of claim 9, further comprising: a heat sink disposed in the enclosure structure in contact with sidewalls of the enclosure structure, wherein the phase change layer is further disposed between the heat sink and the first circuit board. - 16 -

14. The electronic device of claim 13, wherein the phase change layer is further disposed between the heat sink and the second circuit board.

15. A method for forming an electronic device, comprising: forming an enclosure structure; disposing a first circuit board in the enclosure structure; filling a phase change layer in a liquid state into a first gap formed between the enclosure structure and the first circuit board; and solidifying the phase change layer into a solid state.

16. The method of claim 15, wherein filling a phase change layer in a liquid state into a first gap formed between the enclosure structure and the first circuit board comprises: forming a heat sink in the enclosure structure in contact with at lease one sidewall of the enclosure structure; and filling the phase change layer between the heat sink and the first circuit board.

17. The method of claim 15, wherein filling the phase change layer in the liquid state into the first gap formed between the enclosure structure and the first circuit board comprises: providing the phase change layer in the liquid state into the first gap to fill voids between the enclosure structure and the first circuit board.

18. The method of claim 17, wherein the phase change layer in the liquid state fully covers the first circuit board.

19. The method of claim 15, further comprising: disposing a second circuit board in the enclosure structure, wherein the second circuit board is stacked on the first circuit board and a second gap is formed between the first circuit board and the second circuit board; filling the phase change layer in the liquid state into the second gap; and solidifying the phase change layer into the solid state. - 17 -

20. The method of claim 19, wherein the first circuit board and the second circuit board are separated by a supporting frame, and the second gap is formed between the supporting frame, the first circuit board, and the second circuit board.