Heat channel design and heat dissipation material compounding method of high-brightness mobile phone display screen

Abstract

The invention relates to the technical field of intelligent terminal thermal management, in particular to a thermal channel design and heat dissipation material compounding method for a high-brightness mobile phone display screen, which is characterized in that an in-plane high-thermal-conductivity uniform-temperature thin film layer, a thermal-conductive interface material layer TIM comprising a vertical thermal-conductive filler network and a double-layer micro-channel radiator are sequentially compounded on the back surface of a display screen module; through a synergistic heat channel of in-plane temperature equalization, thickness-direction low thermal resistance introduction and double-layer reverse flow efficient heat exchange, heat generated by a high-brightness working condition is quickly introduced into a micro-channel and is taken away by a closed loop cooling medium, and meanwhile, the heat is diffused and dissipated through a middle frame or a rear cover; the micro pump performs grading or continuous speed regulation based on brightness and / or temperature, and gives consideration to both heat dissipation capability and power consumption noise. Dielectric liquid is adopted as a cooling medium, the micro-channel geometry and the inner wall surface micro-nano structure are strengthened, and the heat exchange and temperature equalization performance is improved. Hot-spot temperature rise is reduced within the limited thickness, temperature uniformity is improved, and the heat dissipation device is suitable for stable and reliable heat dissipation of a high-brightness mobile phone display screen.

Description

TECHNICAL FIELD The present application relates to the technical field of intelligent terminal heat management, in particular to a heat channel design and heat dissipation material compounding method for high-brightness mobile phone display screens. BACKGROUND High-brightness mobile phone display screens (such as those used for outdoor strong light readability, HDR display, and high-APL game screens) will generate significant heat under continuous high-brightness working conditions. Existing mobile phones often use a combination of graphite sheets / thermal diffusion films, heat pipes / VCs, heat-conductive pads, and heat-conductive middle frames for heat dissipation. However, under the contradictory constraints of "display screen back heat generation area - limited thickness stacking - hot spot suppression - overall temperature uniformity", the following problems often occur: (1) In-plane diffusion is strong, but the thickness direction heat conduction is insufficient, making it difficult to quickly transfer heat to the heat sink; (2) The interface thermal resistance is large, and the hot spot temperature rise is obvious; (3) Single path or single layer cold plate easily forms non-uniform cooling caused by along-the-way temperature rise; (4) When further increasing the brightness, it is difficult to simultaneously consider hot spots and temperature uniformity. SUMMARY To overcome the above problems, the present application provides a heat channel design and heat dissipation material compounding method for high-brightness mobile phone display screens that can effectively solve the above problems.

[0001] A technical solution provided by the present application to solve the above technical problems is to provide a heat channel design and heat dissipation material compounding method for high-brightness mobile phone display screens, comprising: Step S1: A high-thermal-conductivity temperature-uniformity film layer is attached to the back heat generation area of the mobile phone display screen module, covering 70% to 100% of the projected area of the heat generation area, with a thickness of 20 to 100 microns; Step S2: A thermal interface material layer (TIM) is compounded on the back of the temperature-uniformity film layer, with a thickness of 0.10 to 0.50 mm, and a vertical thermal-conductivity filler network is constructed through the thickness direction of the TIM, with the main orientation of the vertical thermal-conductivity filler network having an angle of not more than 20° relative to the normal of the TIM, and the volume fraction of the vertical thermal-conductivity filler being 5% to 25%; Step S3: A double-layer micro-channel heat sink is attached and installed on the back of the TIM, with a total thickness of not more than 2.0 mm, and the cooling medium flow directions of the upper and lower layers of micro-channels being opposite to form counter-flow; the channel width of each layer of micro-channels is 0.10 to 0.50 mm, and the channel height is 0.05 to 0.30 mm; Step S4: The inlet and outlet of the double-layer micro-channel heat sink are connected to form a sealed closed loop through a flexible micro-pipe and a micro-pump, and cooling medium is injected into the loop; Step S5, during the display screen operation, the micro pump is controlled by grading or continuous speed regulation based on the display brightness and / or the temperature of the back of the display screen, so that heat is transferred along the heat channel of the "uniform temperature film layer-vertical heat conduction TIM-double layer reverse flow micro channel radiator" and diffused out through the middle frame and / or back cover of the mobile phone.

[0002] Preferably, the uniform temperature film layer is a graphite sheet, a graphene film, a graphite and graphene composite film, or a laminated structure thereof, and the in-plane thermal conductivity thereof is not less than 800 W / (m·K).

[0003] Preferably, the vertical heat conduction filler network includes one or more of carbon fiber bundles, vertically oriented graphite / graphene sheets, and carbon nanotube bundles, and forms a continuous heat conduction contact link through the thickness direction.

[0004] Preferably, the vertical heat conduction filler network is formed by any of the following ways: a) The vertical filler is arranged and oriented by a mold, then a TIM matrix is injected and solidified; b) A graphene foam or a porous heat conduction preform is prepared first, and then a silicone-based or epoxy-based TIM is infiltrated and solidified; c) A multi-layer heat conduction sheet is laminated / rolled to form a through-thickness contact link, and then combined with a TIM matrix.

[0005] Preferably, at least one layer of the micro channel of the double-layer micro channel radiator is provided with a gradually expanding diverging section along the flow direction, and the diverging angle is 1° to 8%, so as to reduce the pressure drop and improve the temperature uniformity.

[0006] Preferably, the inner wall of the micro channel is provided with one or more surface strengthening structures such as micro cavities, micro grooves, laser textures, and nano coatings, so as to improve the convective heat exchange capacity and / or enhance the stability of optional two-phase heat exchange.

[0007] Preferably, the cooling medium is a dielectric liquid, and the volume resistivity thereof is not less than 10^8 Ω·cm; the dielectric liquid is a fluorinated liquid, a silicone oil-based dielectric liquid, or a mixture thereof.

[0008] Preferably, the cooling medium further comprises an anti-corrosion additive and / or an anti-cavitation additive, and the mass fraction of the additive is 0.1% to 3%.

[0009] Preferably, the speed regulation control of the micro pump adopts a double-threshold hysteresis strategy: when the display brightness L is greater than or equal to 900 nits or the temperature T is greater than or equal to T1, the pump speed is increased; when L is less than or equal to 700 nits and T is less than or equal to T2, the pump speed is decreased, wherein T1 T2 is 2 to 8℃.

[0010] Preferably, the double-layer micro-channel heat sink is thermally coupled with the middle frame and / or rear cover of the mobile phone through a heat-conducting pad or heat-conducting silicone grease, the heat-conducting pad has a thickness of 0.1-1.0 mm and a thermal conductivity not less than 2 W / (m K), and the contact pressure is maintained at 5-50 kPa through a pressing rib, an elastic pressing piece or a screw limiting structure Compared with the prior art, the heat channel design and heat dissipation material compounding method of the high-brightness mobile phone display screen has the following beneficial effects: (1) Hot spot suppression: the uniform temperature film + vertical heat-conducting TIM significantly reduces the interfacial thermal resistance of the hot spot area; (2) Uniform temperature improvement: the double-layer reverse flow micro-channel weakens the cooling capacity unevenness caused by the temperature rise along the path; (3) Enhanced implementability: engineering windows such as thickness, channel size, filler orientation and content, sealing and detection are given; (4) Reliability and safety: dielectric working medium and sealing detection, and controlled pressure pressing coupling with the middle frame improve the feasibility of mobile phone applications. BRIEF DESCRIPTION OF DRAWINGS Figure 1 The flow chart of the heat channel design and heat dissipation material compounding method of the high-brightness mobile phone display screen. DETAILED DESCRIPTION In order to make the purpose, technical scheme and advantages of the present application clearer, the present application will be further described in detail below with reference to the drawings and examples. It should be understood that the specific examples described herein are only used to explain the present application and do not limit the present application.

[0011] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present application are only relative positions on the specified view, not absolute positions.

[0012] In addition, in the present application, the description such as "first", "second" and the like is only for the purpose of description, and cannot be understood as indicating or implying the relative importance of the indicated technical features or implying the number of the indicated technical features. Therefore, the features limited by "first" and "second" can be explicitly or implicitly included at least one of the features. In the description of the present application, the meaning of "a plurality of" is at least two, such as two, three, etc., unless otherwise specifically limited.

[0013] Please refer to Figure 1 The heat channel design and heat dissipation material compounding method of the high-brightness mobile phone display screen of the present application comprises: S1, a face-in high-thermal-conductivity uniform temperature film layer is attached to the back of the mobile phone display screen module in the heat generating area, the uniform temperature film layer covers 70%-100% of the projected area of the heat generating area, and the thickness is 20-100 μm; S2, TIM is attached to the back of the isothermal film layer, the thickness of the TIM is 0.10-0.50mm, and the vertical heat conduction filler network is constructed through the thickness direction of the TIM, the main orientation of the vertical heat conduction filler network is not more than 20° to the deflection angle of the TIM normal, and the volume fraction of the vertical heat conduction filler is 5%-25%; S3, a double-layer micro-channel radiator is attached to the back of the TIM, the total thickness of the double-layer micro-channel radiator is not more than 2.0mm, the cooling medium flow direction of the upper layer micro-channel is opposite to that of the lower layer micro-channel to form a reverse flow; the channel width of each layer of micro-channel is 0.10-0.50mm, and the channel height is 0.05-0.30mm; S4, the inlet and outlet of the double-layer micro-channel radiator are connected with a micro-pump through a flexible micro-pipe to form a sealed closed loop, and a cooling medium is injected into the loop; S5, during the operation of the display screen, the micro-pump is controlled by grading or continuous speed regulation based on the display brightness and / or the temperature of the back of the display screen, so that heat is transferred along the heat channel of "isothermal film layer→vertical heat conduction TIM→double-layer reverse flow micro-channel radiator" and diffused out through the middle frame and / or the back cover of the mobile phone.

[0014] The isothermal film layer is a graphite sheet, a graphene film, a graphite / graphene composite film or a laminated structure thereof, and the in-plane thermal conductivity coefficient is not less than 800W / (m·K).

[0015] The vertical heat conduction filler network includes one or more of carbon fiber bundles, vertically oriented graphite / graphene sheets and carbon nanotube bundles, and forms a continuous heat conduction contact link through the thickness direction.

[0016] The vertical heat conduction filler network is formed by any of the following ways: a) The vertical filler is arranged by mold limiting and directional arrangement, then the TIM matrix is injected and solidified; b) First, a graphene foam or a porous heat conduction preform is prepared, and then a silicone-based or epoxy-based TIM is infiltrated and solidified; c) A multi-layer heat conduction sheet is laminated / rolled to form a through-thickness contact link, and then combined with the TIM matrix.

[0017] At least one layer of micro-channel of the double-layer micro-channel radiator is provided with a diverging section along the flow direction, and the diverging angle is 1%-8%, so as to reduce the pressure drop and improve the isothermality.

[0018] The inner wall of the micro-channel is provided with one or more surface strengthening structures such as micro-cavity, micro-groove, laser texture and nano-coating, so as to improve the convective heat exchange capacity and / or enhance the stability of optional two-phase heat exchange.

[0019] The cooling medium is a dielectric liquid, and the volume resistivity thereof is not less than 10^8 ohm*cm; the dielectric liquid is a fluorinated liquid, a silicon oil dielectric liquid, or a mixture thereof.

[0020] The cooling medium further comprises an anti-corrosion additive and / or an anti-gas corrosion additive, and the additive mass fraction is 0.1% to 3%.

[0021] The speed control of the micro pump adopts a double-threshold hysteresis strategy: when the display brightness L is greater than or equal to 900 nits or the temperature T is greater than or equal to T1, the pump speed is increased; when L is less than or equal to 700 nits and T is less than or equal to T2, the pump speed is decreased, wherein T1 T2 is 2 to 8 DEG C.

[0022] The double-layer micro-channel radiator is thermally coupled with the middle frame and / or the back cover of the mobile phone through a heat-conducting gasket or heat-conducting silicone grease, the thickness of the heat-conducting gasket is 0.1 to 1.0 mm, and the heat-conducting coefficient is not less than 2 W / (m*K); and the contact pressure is maintained at 5 to 50 kPa through a pressing rib, an elastic pressing piece, or a screw limiting structure.

[0023] The application also provides a high-brightness mobile phone display screen heat dissipation structure, comprising a display screen module and a heat dissipation assembly arranged on the back of the display screen module, wherein the heat dissipation assembly comprises, in sequence, an in-plane high-thermal-conductivity uniform temperature film layer, a heat-conducting interface material layer TIM containing a vertical heat-conducting filler network, and a double-layer micro-channel radiator; the double-layer micro-channel radiator, the micro pump, and the flexible micro tube jointly form a sealed closed cooling loop, and the cooling medium flow directions of the upper micro channel and the lower micro channel are opposite to form a reverse flow; and the heat dissipation structure is configured to execute the method.

[0024] The double-layer micro-channel radiator is made of an aluminum alloy, a copper alloy, stainless steel, or a high-thermal-conductivity composite material, and the packaging and sealing mode thereof is any one of brazing, laser welding, diffusion welding, adhesive sealing, or one-piece injection molding, and 20 to 120 kPa of air / liquid tightness detection is performed before the product is shipped, and the pressure maintaining time is not less than 60 s.

[0025] The heat generating area refers to an area corresponding to the back of the display screen and the backlight, the driving IC, the light emitting pixel array, or a combination thereof. In order to adapt to the structure of the mobile phone, the total thickness of the heat dissipation assembly is preferably controlled to be within 2.5 mm, and the double-layer micro-channel radiator is preferably less than or equal to 2.0 mm.

[0026] The back of the display screen module is sequentially provided with the uniform temperature film layer, the TIM layer, and the double-layer micro-channel radiator. The uniform temperature film layer is responsible for in-plane diffusion; the TIM layer establishes a thickness-direction heat conduction channel through the vertical heat-conducting filler network; and the double-layer micro-channel radiator strengthens heat exchange and uniform temperature through the reverse flow. The back of the radiator is thermally coupled with the middle frame / back cover through a heat-conducting gasket / silicone grease layer, so as to diffuse heat to the whole machine structure and dissipate to the environment.

[0027] The uniform temperature film layer is selected from graphite sheet, graphene film or a composite stack thereof, with a thickness of 20-100 μm, covering 70%-100% of the heating area. The adhesion can be achieved by using a heat-conducting pressure-sensitive adhesive or a heat-conducting adhesive, with a thickness of 10-80 μm, to avoid the increase of thermal resistance caused by air bubbles and voids.

[0028] The TIM layer has a thickness of 0.10-0.50 mm, and is internally provided with a network of vertical heat-conducting fillers with an angle of ≤20° and a volume fraction of 5%-25%.

[0029] The total thickness of the double-layer micro-channel radiator is ≤2.0 mm, and the upper micro-channel and the lower micro-channel flow in opposite directions. The width of each micro-channel is 0.10-0.50 mm, and the height is 0.05-0.30 mm.

[0030] The radiator is connected to a micro-pump to form a sealed closed loop, and the cooling medium is preferably a dielectric liquid (volume resistivity ≥ 10^8 Ω·cm), which can be added with 0.1%-3% of anti-corrosion / anti-cavitation additives.

[0031] The micro-pump is controlled by a step or continuous speed regulation, and the input control at least includes display brightness L and back temperature T. Hysteresis control is preferably used: when L≥900 nits or T≥T1, the speed is increased; when L≤700 nits and T≤T2, the speed is decreased, T1 T2 is 2-8 ℃, to avoid noise and power consumption fluctuations caused by frequent start-stop.

[0032] The back of the radiator is coupled to the middle frame / rear cover through a heat-conducting gasket or a heat-conducting silicone grease layer. The heat-conducting gasket has a thickness of 0.1-1.0 mm and a heat-conducting coefficient of ≥2 W / (m·K). The contact pressure is 5-50 kPa by means of compression ribs, elastic compression members or screws, to reduce the contact thermal resistance and improve the assembly consistency.

[0033] Compared with the prior art, the heat channel design and the heat dissipation material compounding method of the high-brightness mobile phone display screen of the present application have the following beneficial effects: (1) Hot spot suppression: the uniform temperature film + vertical heat-conducting TIM significantly reduces the interfacial thermal resistance of the hot spot area; (2) Uniform temperature improvement: the double-layer opposite-flow micro-channel weakens the cooling capacity unevenness caused by the temperature rise along the way; (3) Enhanced implementability: the engineering windows of thickness, channel size, filler orientation and content, sealing and detection are given; (4) Reliability and safety: the dielectric working medium and the sealing detection are coupled with the controlled compression of the middle frame, to improve the feasibility of mobile phone applications.

[0034] The above merely describes the preferred embodiments of the present application, and is not intended to limit the patent scope of the present application. Any modification, equivalent replacement and improvement within the concept of the present application shall be included in the patent protection scope of the present application.

Claims

1. A method for heat channel design and heat dissipation material compounding of a high-brightness mobile phone display screen, characterized in that, The application relates to a heat dissipation method for a mobile phone display screen module. Step S1: a face-in high-thermal-conductivity uniform temperature film layer is attached to the back of a mobile phone display screen module in a heating area, the uniform temperature film layer covers 70-100% of the projection area of the heating area, and the thickness of the uniform temperature film layer is 20-100 mu m; Step S2: a TIM (thermal interface material) layer is compounded on the back of the uniform temperature film layer, the thickness of the TIM layer is 0.10-0.50 mm, a vertical thermal conductive filler network penetrating through the thickness direction of the TIM layer is constructed in the TIM layer, the main orientation of the vertical thermal conductive filler network is not larger than 20 degrees relative to the deflection angle of the TIM normal, and the volume fraction of the vertical thermal conductive filler is 5-25%; Step S3: a double-layer micro-channel radiator is attached to the back of the TIM layer, the total thickness of the double-layer micro-channel radiator is not larger than 2.0 mm, the cooling medium flow directions of the upper layer micro-channel and the lower layer micro-channel are opposite to form reverse flow, the channel width of each layer micro-channel is 0.10-0.50 mm, and the channel height of each layer micro-channel is 0.05-0.30 mm; Step S4: the inlet and outlet of the double-layer micro-channel radiator are connected with a micro-pump through a flexible micro-pipe to form a sealed closed loop, and a cooling medium is injected into the loop; Step S5: during the operation of the display screen, the micro-pump is controlled by grading or continuous speed regulation based on the display brightness and / or the back temperature of the display screen, so that heat is transmitted along the heat path of the uniform temperature film layer-vertical thermal conductive TIM-double-layer reverse flow micro-channel radiator and diffused out through the mobile phone middle frame and / or back cover.

2. The method of claim 1, wherein the heat channeling design of the high brightness mobile phone display screen is combined with the heat dissipating material. The uniform temperature film layer is a graphite sheet, a graphene film, a graphite and graphene composite film or a laminated structure thereof, and the in-plane thermal conductivity coefficient of the uniform temperature film layer is not lower than 800 W / (m.K).

3. The method of claim 1, wherein the heat channeling design of the high brightness mobile phone display screen is combined with the heat dissipating material. The vertical thermal conductive filler network comprises one or more of carbon fiber bundles, vertically oriented graphite / graphene sheets and carbon nanotube bundles, and forms a continuous thermal conductive contact link penetrating through the thickness direction.

4. The method of claim 1, wherein the heat channeling design of the high brightness mobile phone display screen is combined with the heat dissipating material. The vertical thermal conductive filler network is formed by any one of the following modes: a) the vertical filler is arranged in a limited and directional mode through a mold, then a TIM (thermal interface material) matrix is injected and solidified; b) a graphene foam or a porous thermal conductive preform is prepared first, and then a silica gel-based or epoxy-based TIM is infiltrated and solidified; c) a multi-layer thermal conductive sheet is laminated / rolled to form a contact link penetrating through the thickness direction, and then the contact link is compounded with a TIM matrix.

5. The method of claim 1, wherein the heat channeling design of the high brightness mobile phone display screen is combined with the heat dissipating material. At least one layer of the micro-channel of the double-layer micro-channel radiator is provided with a gradually expanding diverging section along the flow direction, and the diverging angle is 1-8%, so that the pressure drop is reduced and the temperature is uniform.

6. The method of claim 1, wherein the heat channeling design of the high brightness mobile phone display screen is combined with the heat dissipating material. The inner wall of the micro-channel is provided with one or more surface strengthening structures such as micro-cavities, micro-slots, laser textures and nano-coatings, so that the convective heat exchange capacity is improved and / or the stability of optional two-phase heat exchange is enhanced.

7. The method of claim 1, wherein the heat channeling design of the high brightness mobile phone display screen is combined with the heat dissipating material. The cooling medium is a dielectric liquid, and the volume resistivity of the dielectric liquid is not lower than 10^8 ohm*cm; the dielectric liquid is a fluorinated liquid, a silicon oil dielectric liquid or a mixture thereof.

8. The method of claim 1, wherein the heat channeling design of the high brightness mobile phone display screen is combined with the heat dissipating material. The cooling medium further comprises an anti-corrosion additive and / or an anti-cavitation additive, and the mass fraction of the additive is 0.1-3%.

9. The method of claim 1, wherein the heat channeling design of the high brightness mobile phone display screen is combined with the heat dissipating material. The speed control of the micro pump adopts a double threshold hysteresis strategy: when the display brightness L is greater than or equal to 900 nits or the temperature T is greater than or equal to T1, the pump speed is increased; when L is less than or equal to 700 nits and T is less than or equal to T2, the pump speed is decreased, wherein T1 T2 is 2-8℃.

10. The method of claim 1, wherein the heat channeling design of the high brightness mobile phone display screen is combined with the heat dissipating material, and the heat channeling design of the high brightness mobile phone display screen is formed by a plurality of heat channeling grooves formed on the back surface of the display screen. The double-layer micro-channel radiator is coupled with the middle frame and / or back cover of the mobile phone through a heat-conducting gasket or heat-conducting silicone grease, the heat-conducting gasket has a thickness of 0.1-1.0 mm and a heat-conducting coefficient not less than 2 W / (m·K), and the contact pressure is maintained at 5-50 kPa through a pressing rib, an elastic pressing piece or a screw limiting structure.

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