CN115605009B

CN115605009B - Middle frame, electronic equipment and preparation method of middle frame

Info

Publication number: CN115605009B
Application number: CN202211604278.0A
Authority: CN
Inventors: 万伟舰; 陈金玉
Original assignee: Honor Device Co Ltd
Current assignee: Honor Device Co Ltd
Priority date: 2022-12-14
Filing date: 2022-12-14
Publication date: 2023-05-16
Anticipated expiration: 2042-12-14
Also published as: CN115605009A

Abstract

The application relates to a middle frame, electronic equipment and a preparation method of the middle frame, wherein the middle frame comprises a body and a heat conduction layer, the heat conduction layer is attached to the body, and the bonding strength of the heat conduction layer and the body is F, wherein F is more than or equal to 10N and less than or equal to 20N. The heat conduction layer is directly attached to the body of the middle frame through spraying and other processes, and the heat conduction layer is formed on the surface of the body, so that the middle frame can have higher heat conduction performance, the heat dissipation efficiency of electronic components and the whole machine in the electronic equipment is improved, and the reliability of the electronic equipment is improved. The bonding strength of the heat conducting layer and the body is F which is more than or equal to 10N and less than or equal to 20N, so that the heat conducting layer is not easy to separate from the body, the heat radiating effect of the middle frame is guaranteed, the manufacturing process difficulty is low, and the manufacturing cost can be saved. In addition, as the heat conducting layer is directly attached to the body, the heat conducting effect between the heat conducting layer and the body can be prevented from being influenced due to the fact that the heat resistance of the third-party medium is high, and therefore the heat dissipation effect of the middle frame is further improved.

Description

Middle frame, electronic equipment and preparation method of middle frame

Technical Field

The application relates to the technical field of electronic equipment, in particular to a middle frame, electronic equipment and a preparation method of the middle frame.

Background

With the rapid development of the internet technology (Internet Technology, IT) market, electronic devices are gradually miniaturized and refined, and the power consumption of various chips is continuously increased, so that the temperature has a great influence on the working performance of the electronic devices, and the heat dissipation requirement of the electronic devices is continuously increased.

The heat dissipation scheme of the existing electronic equipment generally adopts graphite sheet heat dissipation, heat pipe heat dissipation, temperature equalization plate heat dissipation, copper foil heat dissipation, VC heat dissipation pipe heat dissipation, heat conduction gel heat dissipation and the like, and the principles of the heat dissipation schemes are different, namely heat dissipation modes from different aspects, and the common characteristic is that heat conduction is carried out through a third party medium lamination combination, but in the heat dissipation mode of heat conduction through the lamination combination, the adhesive capacity of heat dissipation media is poor.

Disclosure of Invention

The embodiment of the application provides a middle frame, electronic equipment and a preparation method of the middle frame, which solve the problem of poor adhesion capability of a heat dissipation medium in the prior art.

The first aspect of the embodiment of the application provides a middle frame, which comprises a body and a heat conduction layer, wherein the heat conduction layer is attached to the body, and the bonding strength of the heat conduction layer and the body is F, and F is more than or equal to 10N and less than or equal to 20N.

In this scheme, the heat conduction layer is directly attached to the body of center through technologies such as spraying, forms the heat conduction layer at the surface of body to make the center can have higher heat conductivility, thereby improve the radiating efficiency of electronic component and complete machine in the electronic equipment, improve electronic equipment's reliability. The bonding strength of the heat conduction layer and the body is F which is more than or equal to 10N and less than or equal to 20N, the bonding strength between the heat conduction layer and the body is moderate, the heat conduction layer is not easy to separate from the body, the heat dissipation effect of the middle frame is guaranteed, the manufacturing process difficulty is low, and the manufacturing cost can be saved. In addition, as the heat conducting layer is directly attached to the body, the heat conducting layer and the body are not connected through a third-party medium (such as a rubber material), so that the heat conduction effect between the heat conducting layer and the body can be prevented from being influenced due to the fact that the heat resistance of the third-party medium is high, and the heat dissipation effect of the middle frame is further improved.

In one possible design, the thickness of the heat conducting layer is d,0.02 mm.ltoreq.d.ltoreq.0.06 mm.

In this scheme, when thickness d of heat conduction layer satisfies 0.02mm and is less than or equal to d and is less than or equal to 0.06mm, can make the thickness of heat conduction layer moderate, can guarantee the heat flux of heat conduction layer, guarantee the heat conductivility of heat conduction layer, promote the radiating efficiency of electronic assembly and the complete machine of electronic equipment, can also make the center lighter and thinner, satisfy electronic equipment's frivolous design demand, practice thrift manufacturing cost.

In one possible design, the thermally conductive layer is a graphene thermally conductive layer.

In this scheme, when the heat conduction layer is graphene heat conduction layer, have excellent heat conductivility, make the heat flux of heat conduction layer increase, make the center have better radiating effect, improve electronic equipment's reliability, and because its material property, can realize that the quality is lighter, the thinner heat conduction layer design of thickness, satisfy electronic equipment's design demand of frivolous more.

A second aspect of the present application provides an electronic device, including an electronic component and a middle frame as described in any one of the above embodiments, where the electronic component is mounted on the middle frame. Because the middle frame has the technical effects, the electronic device comprising the middle frame should also have corresponding technical effects, and will not be described in detail herein.

In one possible design, the electronic device is one of a mobile phone, a tablet computer, and a notebook computer.

A third aspect of the embodiments of the present application provides a method for preparing a middle frame, which is used for preparing the middle frame in any one of the above embodiments, and the method includes the following steps:

preparing graphene slurry;

in the step, the graphene slurry needs to be prepared, so that the graphene slurry is uniform in texture and moderate in viscosity, and is convenient for subsequent spraying.

Spraying the graphene slurry on the body of the middle frame to form a graphene coating;

in the step, the prepared graphene slurry is poured into a spray gun, and uniformly sprayed to the body, so that the graphene slurry is attached to the surface of the body to form a graphene coating.

Baking the graphene coating sprayed on the body to form a heat conducting layer;

in the step, the body sprayed with the graphene coating is orderly placed on a baking rack in sequence, and baking is carried out, so that the graphene coating is solidified, and a heat conduction layer with higher bonding strength with the body is formed.

Wherein, the bonding strength of the heat conduction layer and the body is F, and F is more than or equal to 10N and less than or equal to 20N.

In one possible design, in the step of baking the graphene coating sprayed on the body, the baking temperature is 260-280 ℃ and the baking time is 20-30 min.

In the scheme, when the baking temperature is 260-280 ℃ and the baking time is 20-30 min, the graphene coating sprayed on the surface of the body can be uniformly cured, so that the graphene coating is uniformly fused, the overall strength of the heat conducting layer is improved, and the bonding strength of the heat conducting layer and the body can be improved.

In one possible design, the modulating graphene slurry specifically includes:

adding ceramic powder and graphene powder into a solvent, and mixing to form graphene slurry;

wherein the particle size distribution of the ceramic powder is within the range of 2-100 mu m, and the particle size distribution of the graphene powder is within the range of 3-40 mu m.

In the scheme, the particle size distribution of the ceramic powder is within the range of 2-100 mu m, the granularity of the graphene slurry can be increased, and the graphene slurry has better adhesive force, so that the wear resistance and the bonding strength with a body of a formed heat conducting layer are improved, the particle size distribution of the graphene powder is within the range of 3-40 mu m, and the heat conducting layer can be guaranteed to have better heat conducting performance.

In one possible design, the graphene slurry includes first particles with a particle size ranging from 98 μm to 100 μm, second particles with a particle size ranging from 38 μm to 40 μm, third particles with a particle size ranging from 3 μm to 5 μm, and fourth particles with a particle size ranging from 0.01 μm to 2 μm, wherein the mass ratio of the first particles, the second particles, the third particles, and the fourth particles is (0.2 to 0.3): (0.35 to 0.45): (0.2 to 0.3): (0.1 to 0.2).

In this scheme, can guarantee that the surface of the heat conduction layer that forms after the spraying is smooth, can not lead to the fact wearing and tearing to electronic equipment's electronic component, can also improve heat conduction layer's bulk strength, wearability and with the bonding strength of body.

In one possible design, the graphene slurry further comprises a dispersant in an amount of 0.5wt% to 4 wt%.

In this scheme, can prevent that each granule from gathering each other in the graphene slurry from leading to the viscosity of slurry too high, can also prevent graphene powder and ceramic powder in the graphene slurry to sink, make graphene powder and ceramic powder evenly distributed in the solvent, guarantee that the graphene slurry has better mobility to do benefit to the even spraying of graphene slurry.

In one possible design, the dispersant includes at least one of sodium polyacrylate, polyethylene glycol, sodium hexametaphosphate.

In this scheme, sodium polyacrylate, polyethylene glycol, sodium hexametaphosphate all have higher dispersion, can prevent graphene powder and ceramic powder in the graphene slurry subsidence, and have higher thermal stability, do not influence the performance of graphene slurry, sodium polyacrylate, polyethylene glycol, sodium hexametaphosphate are nontoxic, cheap in addition, can improve the safety in utilization.

In one possible design, the solid phase content of the graphene slurry is 45% -75%, wherein the mass ratio of the graphene powder to the ceramic powder is (2-10): 1.

in the scheme, the solid phase content of the graphene slurry is 45% -75%, the heat conduction layer formed after spraying can be guaranteed to have higher strength and higher bonding strength with the body, and the mass ratio of the graphene powder to the ceramic powder is (2-10): 1 can ensure that the heat conduction layer formed after spraying has higher heat conduction performance and ensures the heat dissipation effect of the middle frame.

In one possible design, the preparation method satisfies at least one of the following features:

(1) The stirring time of the graphene slurry is 5 min-10 min;

(2) The viscosity of the graphene slurry is 0.01 Pa.s-3 Pa.s;

(3) The spraying thickness of the graphene slurry on the body is 0.02 mm-0.06 mm;

(4) The step of spraying the graphene slurry on the body of the middle frame to form a graphene coating comprises the following steps: controlling the caliber of a spray gun to be 0.8-1.5 mm, the angle of the spray gun to be +/-60 degrees, the speed of the spray gun to be 5-8 m/s, the spraying distance to be 20-25 mm, and the spraying pressure to be 0.4-0.8 MPa, so that the graphene slurry is sprayed onto the body through the spray gun;

(5) The thickness of the heat conducting layer is d, and d is more than or equal to 0.02mm and less than or equal to 0.06mm.

In this scheme, the stirring time of graphite alkene thick liquids is 5min ~10min, can make graphite alkene powder and ceramic powder in the thick liquids and solvent intensive mixing, guarantees graphite alkene powder and ceramic powder evenly distributed in the solvent. The viscosity of the graphene slurry is 0.01 Pa.s-3 Pa.s, the viscosity is moderate, the graphene slurry is not easy to flow during spraying, so that the heat conducting layer is uniformly distributed, the graphene slurry is also ensured to have higher fluidity, and the spraying of the graphene slurry is facilitated. The spraying thickness of the graphene slurry on the body is 0.02 mm-0.06 mm, the thickness is moderate, the heat conduction layer formed by the too thin spraying thickness is prevented from being too thin, the heat conduction layer is ensured to have higher heat flux, the heat conductivity of the heat conduction layer is ensured, the too thick spraying thickness is prevented, and the drying and curing of the graphene coating are facilitated. The caliber of the spray gun is controlled to be 0.8-1.5 mm, the angle of the spray gun is +/-60 degrees, the speed of the spray gun is 5-8 m/s, the spraying distance is 20-25 mm, and the spraying pressure is 0.4-0.8 MPa, so that graphene slurry is sprayed onto the body through the spray gun, and the high bonding strength between a heat conducting layer formed after spraying and the body is ensured. The thickness of the heat conduction layer is d, d is more than or equal to 0.02mm and less than or equal to 0.06mm, so that the thickness of the heat conduction layer is moderate, namely, the heat flux of the heat conduction layer can be ensured, the heat conduction performance of the heat conduction layer is ensured, the heat dissipation efficiency of an electronic component and the whole machine of the electronic equipment is improved, the middle frame can be lighter and thinner, the light and thin design requirement of the electronic equipment is met, and the manufacturing cost is saved.

In one possible design, the baking the graphene coating sprayed on the body, after forming the heat conducting layer, the method further includes:

and (3) conducting power-on aging on the middle frame, wherein the power-on current is controlled to be 1A-3A, and the power-on time is 30-40 min.

In the step, the dried and solidified middle frame is placed into an aging machine, 1A-3A of current is introduced, and the electrifying time is 30-40 min, so that the middle frame is electrified and aged.

In this scheme, after carrying out the circular telegram ageing to the center, can make the graininess graphite in the heat conduction layer change into netted graphite to improved the heat conduction efficiency of heat conduction layer, increased its radiating efficiency, guaranteed the radiating effect of center. The power-on current is 1A-3A, and the power-on time is 30 min-40 min, so that granular graphite in the heat conducting layer can be converted into netlike graphite as completely as possible, and the heat conducting efficiency of the heat conducting layer is further improved.

In one possible design, before the spraying the graphene slurry on the body of the middle frame to form the graphene coating, the method further includes:

and carrying out sand blasting on the body so that the surface roughness Ra of the body after sand blasting is 0.5-5 mu m.

In this step, the surface of the body is sandblasted to increase the roughness of the body surface to 0.5 μm to 5 μm.

In this scheme, when the surface roughness Ra of body 1 after the sand blasting is 0.5 mu m ~5 mu m, can increase the adhesion effect of graphite alkene thick liquids on the body surface, reduce the flow of graphite alkene thick liquids on the body surface, improve the thickness homogeneity of the heat conduction layer that forms, guarantee the heat conductivility of heat conduction layer, guarantee the radiating effect of center, can also improve the bonding strength of heat conduction layer and body, make the heat conduction layer be difficult for droing.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the application.

Drawings

Fig. 1 is a block diagram of a middle frame of an electronic device according to an embodiment of the present application;

FIG. 2 is a cross-sectional view of the middle frame of FIG. 1;

fig. 3 is a flowchart of a method for preparing a middle frame according to an embodiment of the present application.

Reference numerals:

10-middle frame;

1-a body;

2-a heat conducting layer.

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the application and together with the description, serve to explain the principles of the application.

Detailed Description

First, description will be made of the related art: the heat dissipation scheme of the existing electronic equipment generally adopts graphite sheet heat dissipation, heat pipe heat dissipation, temperature equalization plate heat dissipation, copper foil heat dissipation, VC heat dissipation pipe heat dissipation, heat conduction gel heat dissipation and the like, and the principles of the heat dissipation schemes are different, namely heat dissipation modes from different aspects, and the common characteristic is that heat conduction is carried out through a third party medium lamination combination, but in the heat dissipation mode of heat conduction through the lamination combination, the adhesive capacity of heat dissipation media is poor.

In order to solve the technical problem, the embodiment of the application provides a middle frame for installing an electronic component of electronic equipment, wherein a heat conducting layer of the middle frame is not required to be connected with a body of the middle frame through a third-party medium, and the middle frame has high bonding strength. The electronic device may be a cell phone, tablet computer, ultra-mobile personal computer, UMPC, netbook, as well as cellular telephone, personal digital assistant (personal digital assistant, PDA), augmented reality (augmented reality, AR) device, virtual Reality (VR) device, artificial intelligence (artiFicial intelligence, AI) device, wearable device, vehicle-mounted device, smart home device, and/or smart city device. The specific form of the electronic device is not particularly limited, and the electronic device is taken as an example of a mobile phone for convenience in description.

For a better understanding of the technical solutions of the present application, embodiments of the present application are described in detail below with reference to the accompanying drawings.

The embodiment of the application provides a middle frame 10, as shown in fig. 1 and 2, the middle frame 10 includes a body 1 and a heat conducting layer 2, the heat conducting layer 2 is attached to the body 1, the bonding strength between the heat conducting layer 2 and the body 1 is F, and F is more than or equal to 10N and less than or equal to 20N. For example, F may be 10N, 12N, 14N, 16N, 18N, 20N, etc., and the bonding strength of the heat conductive layer 2 and the body 1 may be other values within the above range, which is not limited thereto.

In this embodiment, as shown in fig. 1 and 2, the heat conducting layer 2 is directly attached to the body 1 of the middle frame 10 through a spraying process and other processes, and a heat conducting layer is formed on the surface of the body 1, so that the middle frame 10 can have higher heat conducting performance, thereby improving the heat dissipation efficiency of electronic components and the whole machine in the electronic device, and improving the reliability of the electronic device. Wherein, the bonding strength of the heat conduction layer 2 and the body 1 is F which is more than or equal to 10N and less than or equal to 20N, the bonding strength between the heat conduction layer 2 and the body 1 is moderate, the heat conduction layer 2 is not easy to separate from the body 1, the heat dissipation effect of the middle frame 10 is ensured, the manufacturing process difficulty is lower, and the manufacturing cost can be saved. In addition, as the heat conducting layer 2 is directly attached to the body 1, the heat conducting layer 2 and the body 1 are not connected through a third-party medium (such as a glue material), so that the heat conduction effect between the heat conducting layer 2 and the body 1 can be prevented from being influenced due to the fact that the heat resistance of the third-party medium is high, and the heat dissipation effect of the middle frame 10 is further improved.

If the bonding strength between the heat conducting layer 2 and the body 1 is too low, that is, F is less than 10N, the heat conducting layer 2 is easy to drop from the body 1, the heat conducting performance of the middle frame 10 is easy to be affected, and the heat dissipation effect of the middle frame 10 is reduced. If the bonding strength between the heat conductive layer 2 and the body 1 is too high, i.e. F > 20N, the difficulty of the manufacturing process of the middle frame 10 is increased, so that the manufacturing cost is increased, and the cost is too high.

In addition, the middle frame 10 may be mainly composed of an alloy, for example, an aluminum alloy, a magnesium alloy, or the like, which may be formed by injection molding with a mold, but may be formed by other means, without limitation.

In one embodiment, as shown in FIG. 2, the thickness of the heat conductive layer 2 is d,0.02 mm.ltoreq.d.ltoreq.0.06 mm. For example, d may be 0.02mm, 0.03mm, 0.04mm, 0.05mm, 0.06mm, etc., and the thickness d of the heat conductive layer 2 may be other values within the above range, without limitation.

In this embodiment, as shown in fig. 2, if the thickness of the heat conducting layer 2 is too low, i.e. d is less than 0.02mm, the heat flux of the heat conducting layer 2 is too thin, the heat dissipation effect of the heat conducting layer is affected, so that the heat dissipation efficiency of the middle frame 10 is reduced, and if the thickness of the heat conducting layer 2 is too large, i.e. d is greater than 0.06mm, the manufacturing materials of the heat conducting layer 2 are easily increased, the cost is higher, and the thickness of the middle frame 10 is also easily increased, so that the lighter and thinner design of the electronic device is not facilitated. Therefore, when the thickness d of the heat conducting layer 2 is less than or equal to 0.02mm and less than or equal to 0.06mm, the thickness d of the heat conducting layer 2 can be moderate, namely, the heat flux of the heat conducting layer 2 can be ensured, the heat conducting performance of the heat conducting layer 2 is ensured, the heat radiating efficiency of the electronic component and the whole machine of the electronic equipment is improved, the middle frame 10 can be lighter and thinner, the light and thin design requirement of the electronic equipment is met, and the manufacturing cost is saved.

In a specific embodiment, the thermally conductive layer 2 is a graphene thermally conductive layer.

Graphene (Graphene) is a two-dimensional carbon nanomaterial in which carbon atoms hybridized by sp are closely packed into a hexagonal honeycomb lattice structure, is a single-layer structure of graphite, and has excellent optical, electrical and mechanical properties.

In this embodiment, when the heat conducting layer 2 is the graphene heat conducting layer 2, the heat conducting layer has excellent heat conducting performance, so that the heat flux of the heat conducting layer 2 is increased, the middle frame 10 has better heat dissipation effect, the reliability of the electronic device is improved, and due to the material characteristics, the design of the heat conducting layer 2 with lighter weight and thinner thickness can be realized, and the design requirement of lighter weight and thinner thickness of the electronic device is met.

Of course, in other embodiments, the heat conducting layer 2 may be made of other materials, which is not limited herein.

The embodiment of the application also provides an electronic device, which comprises an electronic component and the middle frame 10 in any of the above embodiments, wherein the electronic component is mounted on the middle frame 10. Because the middle frame 10 has the above technical effects, the electronic device including the middle frame 10 should also have corresponding technical effects, and will not be described herein.

In a specific embodiment, the electronic device is one of a mobile phone, a tablet computer, and a notebook computer. Of course, the electronic device may also be an ultra-mobile personal computer (UMPC), a cellular phone, a personal digital assistant (personal digital assistant, PDA), an augmented reality (augmented reality, AR) device, a Virtual Reality (VR) device, an artificial intelligence (artiFicial intelligence, AI) device, a wearable device, a vehicle-mounted device, a smart home device, and/or a smart city device, which are not limited herein.

The embodiment of the present application further provides a method for preparing the middle frame 10, as shown in fig. 3, for preparing the middle frame 10 in any of the above embodiments, where the method includes the following steps:

step S1, preparing graphene slurry.

And S3, spraying graphene slurry on the body 1 of the middle frame 10 to form a graphene coating.

In the step, the prepared graphene slurry is poured into a spray gun, and uniformly sprayed to the body 1, so that the graphene slurry is attached to the surface of the body 1, and a graphene coating is formed.

And S4, baking the graphene coating sprayed on the body 1 to form the heat conduction layer 2.

In the step, the body 1 sprayed with the graphene coating is orderly placed on a baking rack in sequence, and baking is carried out, so that the graphene coating is solidified, and the heat conduction layer 2 with higher bonding strength with the body 1 is formed.

Wherein, the bonding strength of the heat conduction layer 2 and the body 1 is F, and F is more than or equal to 10N and less than or equal to 20N.

In this embodiment, as shown in fig. 1 to 3, the heat conducting layer 2 is directly attached to the body 1 of the middle frame 10 through a spraying process and other processes, and a heat conducting layer is formed on the surface of the body 1, so that the middle frame 10 can have higher heat conducting performance, thereby improving the heat dissipation efficiency of electronic components and the whole machine in the electronic device, and improving the reliability of the electronic device. Wherein, the bonding strength of the heat conduction layer 2 and the body 1 is F which is more than or equal to 10N and less than or equal to 20N, the bonding strength between the heat conduction layer 2 and the body 1 is moderate, the heat conduction layer 2 is not easy to separate from the body 1, the heat dissipation effect of the middle frame 10 is ensured, the manufacturing process difficulty is lower, and the manufacturing cost can be saved. In addition, as the heat conducting layer 2 is directly attached to the body 1, the heat conducting layer 2 and the body 1 are not connected through a third-party medium (such as a glue material), so that the heat conduction effect between the heat conducting layer 2 and the body 1 can be prevented from being influenced due to the fact that the heat resistance of the third-party medium is high, and the heat dissipation effect of the middle frame 10 is further improved.

In addition, the bonding strength between the heat conducting layer 2 and the body 1 may be F, and specific values thereof may be selected or set according to actual requirements.

In a specific embodiment, in the step of baking the graphene coating sprayed on the body 1, the baking temperature is 260-280 ℃ and the baking time is 20-30 min.

In this embodiment, if the baking temperature is too low, that is, the baking temperature is lower than 260 ℃, the baking time is longer than 30min, the manufacturing efficiency is reduced, the cost is increased, the moisture at the connection part of the graphene coating and the body 1 is easy to volatilize, the risk of incomplete curing of the graphene coating is caused, if the baking temperature is too high, that is, the baking temperature is higher than 280 ℃, the baking time can be shortened, that is, the baking time is lower than 20min, but the surface layer of the graphene coating is easy to cause the prior curing, so that the inside and the outside of the graphene coating cannot be completely fused, the overall strength of the formed heat conducting layer 2 is lower, and the surface layer of the heat conducting layer 2 is easy to crack and fall off in the subsequent use process. Therefore, when the baking temperature is 260-280 ℃ and the baking time is 20-30 min, the graphene coating sprayed on the surface of the body 1 can be uniformly cured, so that the graphene coating is uniformly fused, the overall strength of the heat conducting layer 2 is improved, and the bonding strength of the heat conducting layer 2 and the body 1 can be improved.

It should be noted that, in order to ensure that the graphene coating will not crack due to transitional baking of the graphene coating, the shorter the baking time required when the baking temperature is higher.

In one embodiment, the baking temperature may be 260 ℃ and the baking time may be 30min, in another embodiment, the baking temperature may be 280 ℃ and the baking time may be 20min, and of course, the baking temperature may also be 270 ℃ and the baking time may be 25min, which may be specifically set according to specific practical situations, so as to meet manufacturing requirements.

In a specific embodiment, the preparation of graphene slurry specifically comprises:

wherein the particle size distribution of the ceramic powder is within the range of 2-100 μm, and the particle size distribution of the graphene powder is within the range of 3-40 μm.

In this embodiment, the particle size distribution of the ceramic powder is within the range of 2 μm to 100 μm, which can increase the granularity of the graphene slurry, and has better adhesion, so as to increase the wear resistance and the bonding strength of the formed heat conducting layer 2 and the body 1, and the particle size distribution of the graphene powder is within the range of 3 μm to 40 μm, which can ensure that the heat conducting layer 2 has better heat conducting performance.

The particle size of the ceramic powder is too small, namely the particle size of the ceramic powder is smaller than 2 mu m, or the particle size of the graphene powder is too small, namely the particle size of the graphene powder is smaller than 3 mu m, so that the particles are too fine, the abrasion resistance is not obvious, the adhesive force is not high, and the cost is increased. The ceramic powder has overlarge particle size, namely the particle size of the ceramic powder is larger than 100 mu m, so that the surface of a coating formed by spraying is rough, the luster is darker, large particles are easy to collapse, and the electronic components of the electric and electronic equipment are easy to wear. When the particle size of the graphene powder is too large, that is, the particle size of the graphene powder is larger than 40 μm, the heat flux of the heat conducting layer 2 is reduced, and the heat conducting performance is reduced.

Of course, the particle sizes of the ceramic powder and the graphene powder may also have other values, and specific values thereof may be selected or set according to actual requirements. The ceramic powder may be barium titanate powder or alumina powder, or other ceramic powder, and is not limited herein.

The mixing method of the graphene slurry may be various, for example, stirring, ultrasonic wave, or other methods, as long as the graphene slurry can be mixed to form a uniform slurry, and the method is not limited thereto.

In addition, the solvent comprises 45% -85% of organic solution, 0.2% -1% of cross-linking agent and 0.12% -0.7% of initiator. The organic solution may be an organic solution formed by mixing acrylamide and deionized water, so as to facilitate mixing of ceramic powder and graphene powder, the cross-linking agent may be N, N-methylene bisacrylamide, so as to improve the connection strength between particles in the heat conducting layer 2, and the initiator may be ammonium persulfate, so as to improve the waterproof effect and the curing effect of the heat conducting layer 2. Of course, the organic solution, the cross-linking agent and the initiator can be other materials, and can be set or selected according to specific practical situations.

In addition, 0.04% -0.2% of catalyst can be added into the solvent to improve the preparation efficiency of the graphene slurry, and the catalyst can be tetramethyl ethylenediamine. The surface of the heat conducting layer 2 can be sprayed with impregnating liquid, so that the overall strength of the heat conducting layer 2 can be further improved.

Wherein, the cross-linking agent, the initiator and the catalyst all need to have chemical purity, and the organic solution and the impregnating solution adopt analytical purity.

In one embodiment, the graphene slurry includes first particles having a particle size ranging from 98 μm to 100 μm, second particles having a particle size ranging from 38 μm to 40 μm, third particles having a particle size ranging from 3 μm to 5 μm, and fourth particles having a particle size ranging from 0.01 μm to 2 μm, wherein the mass ratio of the first particles, the second particles, the third particles, and the fourth particles is (0.2 to 0.3): (0.35 to 0.45): (0.2 to 0.3): (0.1 to 0.2).

In this embodiment, the first particles, the second particles, the third particles and the fourth particles with different particle size ranges are mixed in the prepared graphene slurry, and when the mass ratio of the first particles, the second particles, the third particles and the fourth particles is (0.2-0.3): (0.35 to 0.45): (0.2 to 0.3): (0.1-0.2), can guarantee that the surface of the heat conduction layer 2 that forms after the spraying is smooth, can not lead to the fact wearing and tearing to electronic equipment's electronic component, can also improve heat conduction layer 2's bulk strength, wearability and with the bonding strength of body 1.

In a specific embodiment, the powder is calculated by using a powder grading method, and the mass ratio of the first particles, the second particles, the third particles and the fourth particles may be 0.221:0.401:0.216:0.142, the heat conducting layer 2 formed at this time has the advantages of higher strength, higher hardness and high bonding strength.

Of course, the mass ratio of the first particles, the second particles, the third particles and the fourth particles may also have other values, and the specific values thereof may be selected or set according to actual requirements.

In a specific embodiment, the graphene slurry further comprises a dispersing agent with a mass ratio of 0.5-4 wt%.

A Dispersant (dispersont) is a surfactant having both lipophilic and hydrophilic opposite properties within the molecule. The solid and liquid particles of inorganic and organic pigments which are difficult to dissolve in liquid can be uniformly dispersed, and the sedimentation and agglomeration of the particles can be prevented to form the amphiphilic agent required for stable suspension.

In the embodiment, the dispersing agent with the mass ratio of 0.5-4wt% is added in the solvent, so that the slurry viscosity is prevented from being too high due to mutual aggregation among particles in the graphene slurry, and the graphene powder and the ceramic powder in the graphene slurry can be prevented from sinking, so that the graphene powder and the ceramic powder are uniformly distributed in the solvent, the graphene slurry is ensured to have better fluidity, and uniform spraying of the graphene slurry is facilitated.

The addition amount of the dispersing agent is less than 0.5wt%, so that particles in the graphene slurry are easy to aggregate, the viscosity is too high, the fluidity of the slurry is poor, the spraying is not facilitated, the viscosity of the graphene slurry is too low when the addition amount of the dispersing agent is more than 4wt%, and the slurry is easy to flow on the surface of the body 1 during spraying.

The amount of the dispersant may be 0.5wt%, 1wt%, 2wt%, 3wt%, 0.5wt%, etc., but of course, the amount of the dispersant may be other values, and the specific values thereof may be selected or set according to actual demands.

In a specific embodiment, the dispersant comprises at least one of sodium polyacrylate, polyethylene glycol, sodium hexametaphosphate.

In the embodiment, the sodium polyacrylate, the polyethylene glycol and the sodium hexametaphosphate have higher dispersion performance, so that the graphene powder and the ceramic powder in the graphene slurry are prevented from sinking, the thermal stability is higher, the performance of the graphene slurry is not affected, in addition, the sodium polyacrylate, the polyethylene glycol and the sodium hexametaphosphate are nontoxic and low in cost, and the use safety can be improved.

In the embodiment of the application, three dispersing agents of sodium polyacrylate, polyethylene glycol and sodium hexametaphosphate are selected for dispersion experiments, wherein the dispersion of the suspension is the best when the sodium polyacrylate and the sodium hexametaphosphate are used as the dispersing agents. In the embodiment of the application, sodium polyacrylate is selected as the dispersing agent, so that the graphene powder and the ceramic powder are uniformly distributed in the solvent, and the graphene slurry is ensured to have better fluidity so as to be favorable for uniform spraying of the graphene slurry.

In a specific embodiment, the solid phase content of the graphene slurry is 45% -75%, wherein the mass ratio of the graphene powder to the ceramic powder is (2-10): 1.

in this embodiment, the solid phase content of the graphene slurry is 45% -75%, so that the heat conduction layer 2 formed after spraying can be ensured to have higher strength and higher bonding strength with the body 1, and the mass ratio of the graphene powder to the ceramic powder is (2-10): 1 can ensure that the heat conduction layer 2 formed after spraying has higher heat conduction performance and ensures the heat dissipation effect of the middle frame 10.

The solid phase content of the graphene slurry may be 45%, 50%, 62%, 72%, 75%, etc., the mass ratio of the graphene powder to the ceramic powder may be 2:1, 4:1, 6:1, 8:1, 10:1, etc., of course, the solid phase content of the graphene slurry may also be other values, the mass ratio of the graphene powder to the ceramic powder may also be other values, and specific values thereof may be selected or set according to actual requirements.

In a specific embodiment, the stirring time of the graphene slurry is 5 min-10 min, so that the graphene powder and the ceramic powder in the slurry can be fully mixed with the solvent, and the graphene powder and the ceramic powder are ensured to be uniformly distributed in the solvent. If the stirring time is less than 5 minutes, the graphene powder and the ceramic powder in the graphene slurry cannot be sufficiently mixed with the solvent, and if the stirring time is more than 10 minutes, the production efficiency is low, and the viscosity of the graphene slurry is easily too high. In addition, the stirring time of the graphene slurry can be 5min, 6min, 8min, 10min and the like, and of course, the stirring time of the graphene slurry can also be other numerical values, and specific numerical values can be selected or set according to actual requirements.

In a specific embodiment, the viscosity of the graphene slurry is 0.01 Pa.s-3 Pa.s, the viscosity is moderate, the graphene slurry is not easy to flow during spraying, so that the heat conducting layer is uniformly distributed, the graphene slurry is also ensured to have higher fluidity, and the spraying of the graphene slurry is facilitated. If the viscosity of the graphene slurry is lower than 0.01Pa.s, the graphene coating is easy to drip during spraying, so that the thickness of the formed heat conduction layer 2 is uneven, and if the viscosity of the graphene slurry is higher than 3Pa.s, the gun opening of a spray gun is easy to be blocked by the graphene slurry, and the spraying of the graphene slurry is not facilitated. In addition, the viscosity of the graphene slurry may be 0.01pa.s, 0.2pa.s, 0.5pa.s, 1pa.s, 2pa.s, 3pa.s, etc., and of course, the viscosity of the graphene slurry may also be other values, and specific values thereof may be selected or set according to actual requirements.

In a specific embodiment, the spraying thickness of the graphene slurry on the body 1 is 0.02 mm-0.06 mm, the thickness is moderate, the formed heat conduction layer 2 is prevented from being too thin due to too thin spraying thickness, the heat conduction layer 2 is ensured to have higher heat flux, the heat conductivity of the heat conduction layer 2 is ensured, and the too thick spraying thickness can be avoided to facilitate the drying and curing of the graphene coating. The spraying thickness of the graphene slurry is lower than 0.02mm, the formed heat conducting layer 2 is too thin, the heat flux of the heat conducting layer 2 is too low, the heat conducting performance is low, the spraying thickness of the graphene slurry is higher than 0.06mm, the heat conducting layer 2 is too thick, complete solidification of the heat conducting layer 2 is not facilitated, and the overall strength of the heat conducting layer 2 is low. In addition, the spraying thickness of the graphene slurry can be 0.03mm, 0.04mm, 0.05mm, 0.06mm and the like, and of course, the spraying thickness of the graphene slurry can also be other numerical values, and specific numerical values can be selected or set according to actual requirements.

In a specific embodiment, the step of spraying the graphene slurry on the body 1 of the middle frame 10 to form a graphene coating layer includes: the caliber of the spray gun is controlled to be 0.8-1.5 mm, the angle of the spray gun is +/-60 degrees, the speed of the spray gun is 5-8 m/s, the spraying distance is 20-25 mm, and the spraying pressure is 0.4-0.8 MPa, so that graphene slurry is sprayed onto the body 1 through the spray gun, and the high bonding strength between the heat conducting layer 2 formed after spraying and the body 1 is ensured. And forming a graphene coating with the thickness of 0.02-0.06 mm after multiple spraying by adopting a multiple spraying method. In addition, the spray gun is required to be cleaned by ethanol before being used and cleaned by clean water so as to ensure the cleanness of sprayed graphene slurry.

In a specific embodiment, the spraying can be performed by adopting a spray gun with the caliber of 1mm, the spraying pressure of 0.4Mpa, the spraying distance of 20mm, the speed of the spray gun of 5m/s and the transverse four-side back and forth spraying mode, so as to ensure the spraying effect of the graphene slurry.

In a specific embodiment, the thickness of the heat conducting layer 2 is d, d is more than or equal to 0.02mm and less than or equal to 0.06mm, so that the thickness of the heat conducting layer 2 is moderate, namely, the heat flux of the heat conducting layer 2 can be ensured, the heat conducting performance of the heat conducting layer 2 is ensured, the heat radiating efficiency of an electronic component and the whole machine of the electronic equipment is improved, the middle frame 10 can be lighter and thinner, the light and thin design requirement of the electronic equipment is met, and the manufacturing cost is saved. If the thickness of the heat conducting layer 2 is too low, i.e. d is less than 0.02mm, the heat conducting layer 2 is too thin, the heat flux of the heat conducting layer 2 is smaller, and the heat dissipation effect of the heat conducting layer is affected, so that the heat dissipation efficiency of the middle frame 10 is reduced, if the thickness of the heat conducting layer 2 is too large, i.e. d is more than 0.06mm, the manufacturing material of the heat conducting layer 2 is easily increased, the cost is higher, the thickness of the middle frame 10 is easily caused to be larger, and the lighter and thinner design of the electronic equipment is not facilitated. In addition, d may be 0.02mm, 0.03mm, 0.04mm, 0.05mm, 0.06mm, or the like, and of course, the thickness of the heat conductive layer 2 may be other values, and specific values thereof may be selected or set according to actual requirements.

In a specific embodiment, the graphene coating sprayed on the body 1 is baked, and after the heat conducting layer 2 is formed, the method further includes:

and S5, conducting power-on aging on the middle frame 10, controlling the power-on current to be 1A-3A, and controlling the power-on time to be 30-40 min.

In the step, the dried and cured middle frame 10 is placed in an aging machine, and 1A-3A of current is introduced, wherein the current is introduced for 30-40 min, so that the middle frame 10 is electrified and aged.

In this embodiment, after the middle frame 10 is subjected to power aging, granular graphite in the heat conducting layer 2 can be converted into netlike graphite, so that the heat conducting efficiency of the heat conducting layer 2 is improved, the heat radiating efficiency is increased, and the heat radiating effect of the middle frame 10 is ensured. The electrifying current is 1A-3A, and the electrifying time is 30-40 min, so that granular graphite in the heat conducting layer 2 can be converted into netlike graphite as completely as possible, and the heat conducting efficiency of the heat conducting layer 2 is further improved.

The current can be 1A, 2A, 3A and the like, the electrifying time is 40min, 35min, 40min and the like, and the ageing effect is ensured, so that the conversion degree of the granular graphite in the heat conducting layer 2 is improved. Of course, the current and the energizing time can be other values, and the specific values can be selected or set according to the actual requirements.

In a specific embodiment, before spraying the graphene slurry on the body 1 of the middle frame 10 to form the graphene coating, the method further includes:

and S2, carrying out sand blasting on the body 1 so that the surface roughness Ra of the body 1 after sand blasting is 0.5-5 mu m.

In this step, the surface of the body 1 is sandblasted to increase the roughness of the surface of the body 1 to 0.5 μm to 5 μm.

In this embodiment, when the surface roughness Ra of the body 1 after the sand blasting is 0.5 μm to 5 μm, the adhesion effect of the graphene slurry on the surface of the body 1 can be increased, the flow of the graphene slurry on the surface of the body 1 is reduced, the thickness uniformity of the formed heat conducting layer 2 is improved, the heat conducting performance of the heat conducting layer 2 is ensured, the heat dissipation effect of the middle frame 10 is ensured, the bonding strength of the heat conducting layer 2 and the body 1 can be improved, and the heat conducting layer 2 is not easy to fall off. Too small or too large roughness can easily cause poor layer binding force and easy falling off.

Wherein the roughness Ra of the surface of the body 1 may be 0.5 μm, 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, etc., thereby improving the bonding force of the heat conductive layer 2 with the body 1. Of course, the roughness Ra may also have other values, and the specific value thereof may be selected or set according to actual requirements.

Of course, the surface roughness Ra of the body 1 may be 0.5 μm to 5 μm by pickling, ultrasonic cleaning, or the like, so as to ensure the adhesion fastness of the graphene slurry on the surface of the body 1, which is not limited herein.

The roughness Ra is the arithmetic mean deviation of the profile.

The following examples are provided to further illustrate embodiments of the invention. The embodiments of the present invention are not limited to the following specific embodiments. The modification can be appropriately performed within the scope of the main claim.

Example 1

(1) Performing sand blasting treatment on the middle frame body prepared by the aluminum alloy to obtain a pretreated middle frame with a clean surface; wherein the surface roughness of the pretreatment body is Ra0.5μm-5 μm;

(2) And (3) spraying graphene slurry prepared by mixing ceramic powder and graphene powder and having a solid phase content of 62% on the surface of the body, and baking to form a heat conducting layer with a thickness of 0.06mm, thereby obtaining the middle frame. The mass ratio of graphene powder to ceramic powder in the graphene slurry is 10:1, the graphene slurry comprises first particles with the particle size range of 98-100 microns, second particles with the particle size range of 38-40 microns, third particles with the particle size range of 3-5 microns and fourth particles with the particle size range of 0.01-2 microns, and the mass ratio of the first particles to the second particles to the third particles to the fourth particles is 0.221:0.401:0.216:0.142, baking temperature is 280 ℃, and baking time is 20min.

Example 2

(2) And (3) spraying graphene slurry with the solid phase content of 40% prepared by mixing ceramic powder and graphene powder on the surface of the body, and baking to form a heat conducting layer with the thickness of 0.06mm, thereby obtaining the middle frame. The mass ratio of graphene powder to ceramic powder in the graphene slurry is 10:1, the graphene slurry comprises first particles with the particle size range of 98-100 microns, second particles with the particle size range of 38-40 microns, third particles with the particle size range of 3-5 microns and fourth particles with the particle size range of 0.01-2 microns, and the mass ratio of the first particles to the second particles to the third particles to the fourth particles is 0.221:0.401:0.216:0.142, baking temperature is 280 ℃, and baking time is 20min.

Example 3

(2) And (3) spraying graphene slurry with the solid phase content of 75% prepared by mixing ceramic powder and graphene powder on the surface of the body, and baking to form a heat conducting layer with the thickness of 0.06mm, thereby obtaining the middle frame. The mass ratio of graphene powder to ceramic powder in the graphene slurry is 10:1, the graphene slurry comprises first particles with the particle size range of 98-100 microns, second particles with the particle size range of 38-40 microns, third particles with the particle size range of 3-5 microns and fourth particles with the particle size range of 0.01-2 microns, and the mass ratio of the first particles to the second particles to the third particles to the fourth particles is 0.221:0.401:0.216:0.142, baking temperature is 280 ℃, and baking time is 20min.

Example 4

(2) And (3) spraying graphene slurry with the solid phase content of 80% prepared by mixing ceramic powder and graphene powder on the surface of the body, and baking to form a heat conducting layer with the thickness of 0.06mm, thereby obtaining the middle frame. The mass ratio of graphene powder to ceramic powder in the graphene slurry is 10:1, the graphene slurry comprises first particles with the particle size range of 98-100 microns, second particles with the particle size range of 38-40 microns, third particles with the particle size range of 3-5 microns and fourth particles with the particle size range of 0.01-2 microns, and the mass ratio of the first particles to the second particles to the third particles to the fourth particles is 0.221:0.401:0.216:0.142, baking temperature is 280 ℃, and baking time is 20min.

Example 5

(2) And (3) spraying graphene slurry prepared by mixing ceramic powder and graphene powder and having a solid phase content of 62% on the surface of the body, and baking to form a heat conducting layer with a thickness of 0.06mm, thereby obtaining the middle frame. The mass ratio of graphene powder to ceramic powder in the graphene slurry is 2:1, the graphene slurry comprises first particles with the particle size range of 98-100 microns, second particles with the particle size range of 38-40 microns, third particles with the particle size range of 3-5 microns and fourth particles with the particle size range of 0.01-2 microns, and the mass ratio of the first particles to the second particles to the third particles to the fourth particles is 0.221:0.401:0.216:0.142, baking temperature is 260 ℃ and baking time is 30min.

Example 6

(2) And (3) spraying graphene slurry prepared by mixing ceramic powder and graphene powder and having a solid phase content of 62% on the surface of the body, and baking to form a heat conducting layer with a thickness of 0.06mm, thereby obtaining the middle frame. The mass ratio of the graphene powder to the ceramic powder in the graphene slurry is 1:1, the graphene slurry comprises first particles with the particle size ranging from 98 mu m to 100 mu m, second particles with the particle size ranging from 38 mu m to 40 mu m, third particles with the particle size ranging from 3 mu m to 5 mu m and fourth particles with the particle size ranging from 0.01 mu m to 2 mu m, and the mass ratio of the first particles to the second particles to the third particles to the fourth particles is 0.221:0.401:0.216:0.142, baking temperature is 260 ℃ and baking time is 30min.

Example 7

(2) And (3) spraying graphene slurry prepared by mixing ceramic powder and graphene powder and having a solid phase content of 62% on the surface of the body, and baking to form a heat conducting layer with a thickness of 0.06mm, thereby obtaining the middle frame. The mass ratio of graphene powder to ceramic powder in the graphene slurry is 5:1, the graphene slurry comprises first particles with the particle size range of 98-100 microns, second particles with the particle size range of 38-40 microns, third particles with the particle size range of 3-5 microns and fourth particles with the particle size range of 0.01-2 microns, and the mass ratio of the first particles to the second particles to the third particles to the fourth particles is 0.221:0.401:0.216:0.142, baking temperature is 260 ℃ and baking time is 30min.

Example 8

(2) And (3) spraying graphene slurry prepared by mixing ceramic powder and graphene powder and having a solid phase content of 62% on the surface of the body, and baking to form a heat conducting layer with a thickness of 0.06mm, thereby obtaining the middle frame. The mass ratio of graphene powder to ceramic powder in the graphene slurry is 15:1, the graphene slurry comprises first particles with the particle size range of 98-100 microns, second particles with the particle size range of 38-40 microns, third particles with the particle size range of 3-5 microns and fourth particles with the particle size range of 0.01-2 microns, and the mass ratio of the first particles to the second particles to the third particles to the fourth particles is 0.221:0.401:0.216:0.142, baking temperature is 260 ℃ and baking time is 30min.

Example 9

(2) And (3) spraying graphene slurry prepared by mixing ceramic powder and graphene powder and having a solid phase content of 62% on the surface of the body, and baking to form a heat conducting layer with a thickness of 0.06mm, thereby obtaining the middle frame. The mass ratio of graphene powder to ceramic powder in the graphene slurry is 10:1, the graphene slurry comprises first particles with the particle size range of 98-100 microns, second particles with the particle size range of 38-40 microns, third particles with the particle size range of 3-5 microns and fourth particles with the particle size range of 0.01-2 microns, and the mass ratio of the first particles to the second particles to the third particles to the fourth particles is 0.23:0.35:0.29:0.11, baking temperature is 270 ℃, and baking time is 25min.

Example 10

(2) And (3) spraying graphene slurry prepared by mixing ceramic powder and graphene powder and having a solid phase content of 62% on the surface of the body, and baking to form a heat conducting layer with a thickness of 0.06mm, thereby obtaining the middle frame. The mass ratio of graphene powder to ceramic powder in the graphene slurry is 10:1, the graphene slurry comprises first particles with the particle size range of 98-100 microns, second particles with the particle size range of 38-40 microns, third particles with the particle size range of 3-5 microns and fourth particles with the particle size range of 0.01-2 microns, and the mass ratio of the first particles to the second particles to the third particles to the fourth particles is 0.115:0.215:0.366:0.302, baking temperature is 270 ℃, and baking time is 25min.

Example 11

(2) And (3) spraying graphene slurry prepared by mixing ceramic powder and graphene powder and having a solid phase content of 62% on the surface of the body, and baking to form a heat conducting layer with a thickness of 0.06mm, thereby obtaining the middle frame. The mass ratio of graphene powder to ceramic powder in the graphene slurry is 10:1, the graphene slurry comprises first particles with the particle size range of 98-100 microns, second particles with the particle size range of 38-40 microns, third particles with the particle size range of 3-5 microns and fourth particles with the particle size range of 0.01-2 microns, and the mass ratio of the first particles to the second particles to the third particles to the fourth particles is 0.332:0.425:0.11:0.12, baking temperature is 270 ℃, and baking time is 25min.

Example 12

(2) And (3) spraying graphene slurry prepared by mixing ceramic powder and graphene powder and having a solid phase content of 62% on the surface of the body, and baking to form a heat conducting layer with a thickness of 0.06mm, thereby obtaining the middle frame. The mass ratio of graphene powder to ceramic powder in the graphene slurry is 10:1, the graphene slurry comprises first particles with the particle size range of 98-100 microns, second particles with the particle size range of 38-40 microns, third particles with the particle size range of 3-5 microns and fourth particles with the particle size range of 0.01-2 microns, and the mass ratio of the first particles to the second particles to the third particles to the fourth particles is 0.221:0401:0216:0.142, baking temperature is 240 ℃, and baking time is 40min.

Example 13

(2) And (3) spraying graphene slurry prepared by mixing ceramic powder and graphene powder and having a solid phase content of 62% on the surface of the body, and baking to form a heat conducting layer with a thickness of 0.06mm, thereby obtaining the middle frame. The mass ratio of graphene powder to ceramic powder in the graphene slurry is 10:1, the graphene slurry comprises first particles with the particle size range of 98-100 microns, second particles with the particle size range of 38-40 microns, third particles with the particle size range of 3-5 microns and fourth particles with the particle size range of 0.01-2 microns, and the mass ratio of the first particles to the second particles to the third particles to the fourth particles is 0.221:0401:0216:0.142, baking temperature is 260 ℃ and baking time is 30min.

Example 14

(2) And (3) spraying graphene slurry prepared by mixing ceramic powder and graphene powder and having a solid phase content of 62% on the surface of the body, and baking to form a heat conducting layer with a thickness of 0.06mm, thereby obtaining the middle frame. The mass ratio of graphene powder to ceramic powder in the graphene slurry is 10:1, the graphene slurry comprises first particles with the particle size range of 98-100 microns, second particles with the particle size range of 38-40 microns, third particles with the particle size range of 3-5 microns and fourth particles with the particle size range of 0.01-2 microns, and the mass ratio of the first particles to the second particles to the third particles to the fourth particles is 0.221:0401:0216:0.142, baking temperature is 275 ℃, and baking time is 22min.

Example 15

(2) And (3) spraying graphene slurry prepared by mixing ceramic powder and graphene powder and having a solid phase content of 62% on the surface of the body, and baking to form a heat conducting layer with a thickness of 0.06mm, thereby obtaining the middle frame. The mass ratio of graphene powder to ceramic powder in the graphene slurry is 10:1, the graphene slurry comprises first particles with the particle size range of 98-100 microns, second particles with the particle size range of 38-40 microns, third particles with the particle size range of 3-5 microns and fourth particles with the particle size range of 0.01-2 microns, and the mass ratio of the first particles to the second particles to the third particles to the fourth particles is 0.221:0401:0216:0.142, baking temperature is 290 ℃ and baking time is 15min.

And (3) testing:

1. thickness measurement is to observe and measure the relevant thickness of the cross section of the product under a microscope;

2. testing of bond strength of thermally conductive layer and body:

the test was performed according to GB/T8642, the national standard for tensile bond strength determination. The preparation method comprises the following steps: as far as possible, the same type of material as the practical application is selected as the substrate of the sample, and the substrate is flat and has no deformation. And uniformly coating the bonding system in the structure of the ten-level square standard bonding tensile sample or the ten-level circular standard bonding tensile sample according to the bonding modes of the marked tensile samples of different levels. After the coating bonding system is cured, the bonded sample combination is placed on a proper tensile testing machine, and the tensile force required for damaging the adhesion between the coating and the substrate is measured by a controllable tensile test (pull-off test) of the bonded sample, so that the equivalent bonding strength of the corresponding grade is calculated.

In order to enable the tensile force to uniformly act on the bonding area of the sample without any twisting action, a tensile stress is applied in the direction perpendicular to the bonding plane of the sample, and the tensile force which damages the bonding of the sample is accurately obtained.

Table 1 test experimental data

As can be seen from examples 1 to 4 shown in table 1, the solid phase content of the graphene slurry is controlled within the range of 45% -75%, the heat conducting layer and the body have better bonding effect, and the bonding strength is higher; if the solid phase content of the graphene slurry is too low, the connection strength among particles in the graphene slurry is affected, the compactness of the heat conduction layer is affected, and the bonding strength between the heat conduction layer and the body is affected; if the solid phase content of the graphene slurry is too high, each particle in the graphene slurry is not easy to separate, and the thickness uniformity of the heat conducting layer is affected, so that the heat conducting layer and the body are combined poorly.

As can be seen from examples 1 and 5-8 shown in table 1, the mass ratio of graphene powder to ceramic powder of the graphene slurry is controlled within (2-10): 1, and the heat conductive layer has better bonding strength with the body and better heat conductive property; if the mass ratio of graphene powder to ceramic powder is too low, namely the content of graphene is too low, the connection effect between particles in graphene slurry is poor, the compactness of the heat conduction layer is influenced, and the heat conduction effect of the heat conduction layer can be influenced.

As can be seen from examples 1 and 9-11 shown in table 1, the prepared graphene slurry is mixed with first particles, second particles, third particles and fourth particles having different particle size ranges, and when the mass ratio of the first particles, second particles, third particles and fourth particles is controlled to be (0.2-0.3): (0.35 to 0.45): (0.2 to 0.3): in the range of (0.1-0.2), particles in the graphene slurry are easy to disperse to form suspension, so that the spraying is convenient, the sprayed graphene slurry and the body have higher adhesive force, so that the heat conducting layer and the body have higher bonding strength, the surface of the heat conducting layer formed after the spraying is smooth, the electronic components of the electronic equipment are not worn, and the overall strength and the wear resistance of the heat conducting layer can be improved; if the first particles in the graphene occupy more, larger particles in the graphene slurry are more, so that the formed heat conduction layer is rough, the bonding effect between the heat conduction layer and the body can be influenced, if the fourth particles in the graphene occupy more, smaller particles in the graphene slurry are more, the attaching effect between the graphene slurry and the body is poorer, and the bonding strength between the heat conduction layer and the body is not high.

As can be seen from examples 1, 7, 9 and 12 to 15 described in table 1, for the body sprayed with the graphene coating, the baking temperature is controlled to be 260 to 280 ℃ and the baking time is controlled to be 20 to 30 minutes, so that the graphene coating sprayed on the surface of the body 1 can be uniformly cured, and the graphene coating can be uniformly fused, so that the overall strength of the heat conducting layer is improved, and the bonding strength of the heat conducting layer and the body can be improved. If the baking temperature is too low, namely the baking temperature is lower than 260 ℃, the baking is required to be performed for a long time, namely the baking time is longer than 30 minutes, the manufacturing efficiency is reduced, the cost is increased, the moisture of the connecting part of the graphene coating and the body is easy to volatilize, the risk of incomplete curing of the graphene coating is caused, if the baking temperature is too high, namely the baking temperature is higher than 280 ℃, the baking time can be shortened, namely the baking time is lower than 20 minutes, but the surface layer of the graphene coating is easy to be cured, the inside and outside of the graphene coating cannot be completely fused, the overall strength of the formed heat conducting layer is lower, the surface layer of the heat conducting layer is easy to crack and fall off in the subsequent use process, and the bonding strength is not high.

The foregoing is merely specific embodiments of the present application, but the scope of the present application is not limited thereto, and any person skilled in the art can easily think about changes or substitutions within the technical scope of the present application, and the changes or substitutions are intended to be covered by the scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

Claims

1. The preparation method of the middle frame is characterized by comprising the following steps of:

preparing graphene slurry;

carrying out electrifying aging on the middle frame, controlling electrifying current to be 1A-3A, and electrifying time to be 30-40 min;

the bonding strength of the heat conduction layer and the body is F, F is more than or equal to 10N and less than or equal to 20N, and the thickness of the heat conduction layer is d, wherein d is more than or equal to 0.02mm and less than or equal to 0.06mm;

the graphene slurry comprises first particles with the particle size ranging from 98 mu m to 100 mu m, second particles with the particle size ranging from 38 mu m to 40 mu m, third particles with the particle size ranging from 3 mu m to 5 mu m and fourth particles with the particle size ranging from 0.01 mu m to 2 mu m, wherein the mass ratio of the first particles, the second particles, the third particles and the fourth particles is (0.2-0.3): (0.35 to 0.45): (0.2 to 0.3): (0.1 to 0.2).

2. The method for preparing the middle frame according to claim 1, wherein in the step of baking the graphene coating sprayed on the body, the baking temperature is 260-280 ℃, and the baking time is 20-30 min.

3. The method for preparing a middle frame according to claim 1, wherein the preparing graphene slurry specifically comprises:

4. The method for preparing the middle frame according to claim 3, wherein the graphene slurry further comprises a dispersing agent with a mass ratio of 0.5-4 wt%.

5. The method for preparing a middle frame according to claim 4, wherein the dispersing agent comprises at least one of sodium polyacrylate, polyethylene glycol, and sodium hexametaphosphate.

6. The method for preparing a middle frame according to claim 4, wherein the solid phase content of the graphene slurry is 45% -75%, and the mass ratio of the graphene powder to the ceramic powder is (2-10): 1.

7. the method of manufacturing a middle frame according to claim 1, wherein the method of manufacturing meets at least one of the following characteristics:

(1) The stirring time of the graphene slurry is 5 min-10 min;

(2) The viscosity of the graphene slurry is 0.01 Pa.s-3 Pa.s;

(4) The step of spraying the graphene slurry on the body of the middle frame to form a graphene coating comprises the following steps: the caliber of the spray gun is controlled to be 0.8-1.5 mm, the angle of the spray gun is +/-60 degrees, the speed of the spray gun is 5-8 m/s, the spraying distance is 20-25 mm, and the spraying pressure is 0.4-0.8 MPa, so that the graphene slurry is sprayed onto the body through the spray gun.

8. The method for preparing a middle frame according to claim 1, wherein before spraying the graphene slurry on the body of the middle frame to form a graphene coating, the method further comprises: