Process method of asphalt-based and boron nitride-based heat-conducting composite board

Abstract

The invention relates to the technical field of production of electronic equipment accessories, in particular to a process method of a heat-conducting composite board with an asphalt base combined with a boron nitride base material. The preparation method comprises the following steps: S1, dispersing and mixing a heat-conducting filler hexagonal boron nitride in an epoxy resin glue solution, uniformly stirring, vacuumizing, and defoaming to remove air in the glue solution, so as to obtain an epoxy resin heat-conducting mixed solution; s2, arranging the heat-conducting asphalt reinforced base fibers to form a one-way belt with a single-layer yarn thickness, impregnating and permeating the one-way belt in an epoxy resin heat-conducting mixed solution for preimpregnation, extruding excess resin, and drying to obtain a heat-conducting sheet material; s3, cooling the heat-conducting sheet-shaped material, rolling, and packaging to obtain a sheet-shaped raw material; and S4, cutting the sheet-shaped raw materials according to the required shape, stacking a plurality of sheet-shaped raw materials to form a sheet material, putting the sheet material into a mold, and carrying out high-temperature and high-pressure hot press molding to form a heat-conducting battery back cover product. The process solves the problem of poor heat conductivity of the resin and improves the heat-conducting property of the product.

Description

Technical Field

[0001] This invention relates to the field of electronic device component manufacturing technology, and in particular to a process method for a thermally conductive composite board made of asphalt-based material combined with boron nitride substrate. Background Technology

[0002] With the development of 5.5G and 6G mobile phones, the demands on batteries from mobile applications are increasing, and battery heat generation will become more noticeable. If the heat generated by the battery cannot be dissipated in time, it will affect the performance of the mobile phone and the user experience.

[0003] The traditional principle of thermal conductivity in battery back covers involves using thermally conductive filler (boron nitride) and thermally conductive fibers as structural composite materials, followed by surface coating and 3D texturing. The application of composite materials as battery back covers mainly presents the following technical challenges. 1. Glass fiber + non-thermal conductive resin: Because the glass fiber shell material has poor thermal conductivity, the standby time and battery life of the mobile phone are greatly reduced.

[0004] Second: Short battery life of mobile phones increases the cost of use for consumers.

[0005] Third: Insufficient heat dissipation from the battery back cover can cause heat to accumulate inside the device, especially under high load scenarios (such as gaming and fast charging). This can cause the CPU and battery temperatures to rise, triggering a frequency reduction mechanism and resulting in stuttering, frame rate fluctuations, and other problems.

[0006] Fourth: The lifespan of lithium batteries decreases rapidly at high temperatures (the lifespan is halved for every 10°C increase in temperature), and in extreme cases, it may cause risks such as bulging and leakage.

[0007] Fifth: The low thermal conductivity material of the back cover exacerbates internal heat retention, further threatening battery safety. Summary of the Invention

[0008] This invention provides a process for manufacturing a thermally conductive composite sheet material based on asphalt and combined with boron nitride substrate, aiming to solve the technical problems existing in the application of traditional composite materials in battery back covers.

[0009] This invention provides a process for manufacturing a thermally conductive composite plate based on asphalt and bonded to a boron nitride substrate, comprising the following steps: S1. Disperse and mix the thermally conductive filler hexagonal boron nitride in the epoxy resin solution, stir evenly, and perform degassing treatment under vacuum to remove air from the solution, thereby obtaining a thermally conductive epoxy resin mixture. S2. Arrange the thermally conductive asphalt-reinforced base fibers to form a unidirectional tape with a single-layer yarn thickness. Impregnate the unidirectional tape in an epoxy resin thermally conductive mixed solution for pre-impregnation. After pre-impregnation, extrude the excess resin and dry to obtain a thermally conductive sheet material. S3. After cooling, rolling up and packaging the thermally conductive sheet material, a sheet raw material of thermally conductive reinforced fiber pre-thermal conductive filler is obtained; S4. After cutting the sheet-like raw materials into the required shape, stack multiple sheet-like raw materials to form a sheet material. After the sheet material is put into the mold, it is hot-pressed under high temperature and high pressure to form a thermally conductive battery back cover product.

[0010] As a further improvement of the present invention, in S1, the hexagonal boron nitride accounts for 15% to 45% of the weight of the epoxy resin adhesive.

[0011] As a further improvement of the present invention, in step S1, the preparation process of the epoxy resin adhesive includes: a1. Mix the curing agent and organic solvent in a weight ratio of 1:(5~10) and stir to obtain mixture A; a2. Mix the organic solvent and resin in a weight ratio of 1:(5~15) and stir to obtain mixture B; a3. Mix the mixture A and the mixture B, and stir to obtain an epoxy resin solution.

[0012] As a further improvement of the present invention, the curing agent is one or a mixture of polyamide, aliphatic amine, and aromatic amine.

[0013] As a further improvement of the present invention, the organic solvent is one or a mixture of styrene, acetone, and butanone.

[0014] As a further improvement of the present invention, the resin is one or a mixture of unsaturated polyester resin, polyurethane resin, and polypropylene resin.

[0015] As a further improvement of the present invention, in step S1, the degassing treatment is carried out by stirring evenly at 18°C ​​to 22°C and then vacuuming for 10 to 20 minutes.

[0016] As a further improvement of the present invention, in step S2, the thermally conductive sheet material includes a thermally conductive prepreg or a thermally conductive semi-cured sheet. The thermally conductive prepreg is a sheet material made by prepregding thermally conductive asphalt-reinforced fibers with epoxy resin and extruding excess resin. The thermally conductive semi-cured sheet is made by baking and drying the thermally conductive prepreg.

[0017] As a further improvement of the present invention, in step S2, the ambient temperature of the pre-impregnation is 18~25℃ and the humidity is 45%~55%RH.

[0018] As a further improvement of the present invention, in step S2, the operation of extruding excess resin includes pressing the pre-impregnated unidirectional belt with rollers, and controlling the resin content to 42% by the roller gap and pressure.

[0019] The beneficial effects of this invention are: by adding boron nitride filler to epoxy resin, the problem of poor thermal conductivity of the resin is successfully solved; at the same time, by utilizing the good thermal conductivity of pitch fiber itself, replacing glass fiber with pitch fiber can effectively improve the thermal conductivity of the product. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the process of hot pressing preheated thermal filler raw materials in this invention. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0022] Combination Figure 1 As shown, the present invention provides a process for a thermally conductive composite plate made of asphalt-based material and boron nitride substrate, comprising the following steps: S1. The thermally conductive filler, hexagonal boron nitride, is dispersed and mixed in an epoxy resin solution, stirred until homogeneous, and then subjected to vacuum degassing to remove air from the solution, resulting in a thermally conductive epoxy resin mixture. Thermally conductive pitch fiber is added to the epoxy resin as a reinforcing fiber, and hexagonal boron nitride as a thermally conductive filler to form a thermally conductive resin. The pitch fiber is made into a 0.1 mm thick unidirectional fabric using long filaments.

[0023] Specifically, the thermally conductive filler hexagonal boron nitride is dispersed and mixed in epoxy resin liquid, with the hexagonal boron nitride accounting for 15%~45% of the weight of the epoxy resin liquid. The mixture is stirred evenly in an environment of 18℃~22℃ and then subjected to vacuum degassing treatment for 10~20 minutes to remove air from the liquid, thus obtaining a thermally conductive epoxy resin mixture.

[0024] The production process of epoxy resin adhesive includes: a1. Mix the curing agent and organic solvent in a weight ratio of 1:(5~10) and stir to obtain mixture A; a2. Mix the organic solvent and resin in a weight ratio of 1:(5~15) and stir to obtain mixture B; a3. Mix mixture A and mixture B and stir to obtain epoxy resin solution.

[0025] The curing agent is one or a mixture of polyamide, aliphatic amine, and aromatic amine.

[0026] The organic solvent is one or a mixture of styrene, acetone, and butanone.

[0027] The resin is one or a mixture of unsaturated polyester resin, polyurethane resin, and polypropylene resin.

[0028] S2. Arrange the thermally conductive bitumen reinforcing fibers to form a unidirectional tape with a single-layer yarn thickness. Impregnate the unidirectional tape with a thermally conductive epoxy resin mixture for pre-impregnation. After pre-impregnation, extrude excess resin and dry to obtain a thermally conductive sheet material. Bitumen fibers are used as reinforcing fibers and pre-impregnated with thermally conductive resin to produce sheet-like thermally conductive prepregs or baked to produce thermally conductive semi-cured sheets.

[0029] In step S2, the thermally conductive sheet material includes thermally conductive prepreg or thermally conductive semicured sheet. The thermally conductive prepreg is a sheet material made by prepregding thermally conductive asphalt-reinforced fibers with epoxy resin and extruding excess resin. The thermally conductive semicured sheet is made by baking and drying the thermally conductive prepreg.

[0030] Specifically, the thermally conductive asphalt-reinforced base fibers are arranged one by one in the width direction using a machine to form a single-layer yarn thickness unidirectional tape. The unidirectional tape is pre-impregnated in a thermally conductive solution through an adhesive bath. The pre-impregnation environment temperature is 18~25℃ and the humidity is 45%~55%RH. Excess resin is extruded by controlling the gap and pressure of the machine rollers, with a resin content of 42%. The material is then dried in a drying oven at 80 degrees Celsius for 15 minutes to finally obtain a thermally conductive prepreg or a thermally conductive semi-cured sheet.

[0031] S3. After cooling and rolling the thermally conductive sheet material, it is packaged to obtain sheet raw material of thermally conductive reinforced fiber pre-thermal conductive filler.

[0032] S4. After cutting the sheet-like raw materials into the required shape, stack multiple sheet-like raw materials to form a sheet material. After the sheet material is put into the mold, it is hot-pressed under high temperature and high pressure to form a thermally conductive battery back cover product.

[0033] Specifically, after being cooled, the material is wound into rolls and packaged to obtain thermally conductive reinforced fiber pre-thermal conductive filler raw material. This raw material is then cut according to product drawings and stacked in a prescribed manner to form sheets. These sheets are then placed into a mold and subjected to high-temperature, high-pressure hot pressing to form the phone back cover. For example... Figure 1 As shown, four layers of boron nitride + asphalt fiber semi-cured sheets are stacked, and release films are stacked on the top and bottom layers. The battery back cover is formed by high-pressure curing at a temperature of 140℃, which meets the product thickness requirements.

[0034] The process for fabricating a thermally conductive composite plate based on asphalt and boron nitride substrate according to the present invention has the following characteristics: 1) The prepreg is made of pitch fiber instead of traditional glass fiber, and hexagonal boron nitride thermally conductive filler is added to the epoxy resin to improve the heat dissipation capacity of the phone back cover; this avoids heat retention inside the phone during long-term use, which could further threaten battery safety.

[0035] 2) With improved heat dissipation, the battery temperature decreases, thereby extending the phone's battery life and increasing its lifespan.

[0036] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the concept of the present invention, and all such modifications and substitutions should be considered within the scope of protection of the present invention.

Claims

1. A process for manufacturing a thermally conductive composite sheet material based on asphalt and bonded to a boron nitride substrate, characterized in that, Includes the following steps: S1. Disperse and mix the thermally conductive filler hexagonal boron nitride in the epoxy resin solution, stir evenly, and perform degassing treatment under vacuum to remove air from the solution, thereby obtaining a thermally conductive epoxy resin mixture. S2. Arrange the thermally conductive asphalt-reinforced base fibers to form a unidirectional tape with a single-layer yarn thickness. Impregnate the unidirectional tape in an epoxy resin thermally conductive mixed solution for pre-impregnation. After pre-impregnation, extrude the excess resin and dry to obtain a thermally conductive sheet material. S3. After cooling, rolling up and packaging the thermally conductive sheet material, a sheet raw material of thermally conductive reinforced fiber pre-thermal conductive filler is obtained; S4. After cutting the sheet-like raw materials into the required shape, stack multiple sheet-like raw materials to form a sheet material. After the sheet material is put into the mold, it is hot-pressed under high temperature and high pressure to form a thermally conductive battery back cover product.

2. The process for fabricating a thermally conductive composite plate with an asphalt-based bonded boron nitride substrate according to claim 1, characterized in that, In S1, the hexagonal boron nitride accounts for 15% to 45% of the weight of the epoxy resin adhesive.

3. The process for fabricating a thermally conductive composite plate with an asphalt-based bonded boron nitride substrate according to claim 1, characterized in that, In step S1, the process of preparing the epoxy resin adhesive includes: a1. Mix the curing agent and organic solvent in a weight ratio of 1:(5~10) and stir to obtain mixture A; a2. Mix the organic solvent and resin in a weight ratio of 1:(5~15) and stir to obtain mixture B; a3. Mix the mixture A and the mixture B, and stir to obtain an epoxy resin solution.

4. The process for fabricating a thermally conductive composite plate with an asphalt-based bonded boron nitride substrate according to claim 3, characterized in that, The curing agent is one or a mixture of polyamide, aliphatic amine, and aromatic amine.

5. The process for fabricating a thermally conductive composite plate based on asphalt and bonded to a boron nitride substrate according to claim 3, characterized in that, The organic solvent is one or a mixture of styrene, acetone, and butanone.

6. The process for fabricating a thermally conductive composite plate with an asphalt-based bonded boron nitride substrate according to claim 3, characterized in that, The resin is one or more of unsaturated polyester resin, polyurethane resin, and polypropylene resin, or a mixture thereof.

7. The process for fabricating a thermally conductive composite plate based on bitumen-based and boron nitride substrate according to claim 1, characterized in that, In step S1, the degassing treatment is carried out by stirring evenly at 18℃~22℃ and then vacuuming for 10~20 minutes.

8. The process for fabricating a thermally conductive composite plate with an asphalt-based bonded boron nitride substrate according to claim 1, characterized in that, In step S2, the thermally conductive sheet material includes thermally conductive prepreg or thermally conductive semicured sheet. The thermally conductive prepreg is a sheet material made by prepregding thermally conductive asphalt-reinforced fibers with epoxy resin and extruding excess resin. The thermally conductive semicured sheet is made by baking and drying the thermally conductive prepreg.

9. The process for fabricating a thermally conductive composite plate with an asphalt-based bonded boron nitride substrate according to claim 1, characterized in that, In S2, the ambient temperature for pre-impregnation is 18~25℃; the humidity is 45%~55%RH.

10. The process for manufacturing a thermally conductive composite sheet with an asphalt-based bonded boron nitride substrate according to claim 1, characterized in that, In step S2, the operation of extruding excess resin includes pressing the pre-impregnated unidirectional belt with rollers, and controlling the resin content to 42% by the roller gap and pressure.

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