Preparation process of a high thermal conductivity composite substrate

Abstract

The present invention discloses a preparation process for a high thermal conductivity composite substrate, comprising: fixing a pre-prepared framework on an insulating base layer, and the branches of the framework and the surface of the insulating base layer jointly define a plurality of heat dissipation spaces; dividing the plurality of heat dissipation spaces into at least one high heat dissipation space and at least one low heat dissipation space according to the layout and heat generation characteristics of predetermined electronic components; injecting a first thermal conductive filler into the high heat dissipation space and injecting a second thermal conductive filler into the low heat dissipation space, and performing a curing treatment, wherein the thermal conductivity coefficient of the first thermal conductive filler is greater than that of the second thermal conductive filler, and the first thermal conductive filler and the second thermal conductive filler are combined with the framework to form a thermal conductive layer; fixing a functional layer of a printed circuit board on the surface of the thermal conductive layer, and the area of the functional layer corresponding to the high heat dissipation space is used for installing high heat generating electronic components, and the area corresponding to the low heat dissipation space is used for installing low heat generating electronic components. The technical solution of the present invention can adopt different thermal conductive measures for different heat generating components.

Description

Technical Field

[0001] The present invention relates to the technical field of the preparation of printed circuit boards, and particularly to a preparation process of a high - thermal - conductivity composite substrate. Background Art

[0002] A printed circuit board (PCB) is an indispensable core component in modern electronic devices, which provides mechanical support and electrical connection for various electronic components. With the miniaturization and high - performance of electronic devices, the component density on the PCB has been continuously increasing, and the power consumption has also risen accordingly, which has led to serious thermal management problems. Excessive temperature will not only reduce the performance and lifespan of electronic components, but may also cause safety hazards. Therefore, effective heat dissipation and thermal conduction design are crucial for ensuring the reliability and performance of the PCB, which has become a key challenge in the design of electronic products.

[0003] Currently, PCB heat dissipation usually adopts an integral metal layer for heat conduction. Although this method is simple and direct, it has significant defects. Due to the uniform heat - conduction characteristics of the integral metal layer, it is impossible to take differentiated heat - dissipation measures for components with different heat - generating characteristics on the PCB. This results in uneven heat distribution, where some high - heat - generating components may not receive sufficient heat dissipation, while the heat - dissipation resources in the area of low - heat - generating components may be wasted. Summary of the Invention

[0004] The main objective of the present invention is to solve the technical problem that the prior art uses an integral metal layer for heat conduction and cannot adopt different heat - conduction measures for different heat - generating components.

[0005] The first aspect of the present invention provides a preparation process of a high - thermal - conductivity composite substrate, and the preparation process of the high - thermal - conductivity composite substrate includes:

[0006] Fix a pre - prepared skeleton on the insulating base layer of the printed circuit board. The skeleton is composed of a plurality of interconnected branches, and the branches and the surface of the insulating base layer jointly define a plurality of heat - dissipation spaces;

[0007] According to the layout and heat - generating characteristics of the predetermined electronic components, divide the plurality of heat - dissipation spaces into at least one high - heat - dissipation space and at least one low - heat - dissipation space;

[0008] Inject a first thermal - conductivity filler into the high - heat - dissipation space and perform a curing treatment, and inject a second thermal - conductivity filler into the low - heat - dissipation space and perform a curing treatment. The thermal - conductivity coefficient of the first thermal - conductivity filler is greater than that of the second thermal - conductivity filler, and the first thermal - conductivity filler and the second thermal - conductivity filler combine with the skeleton to form a thermal - conduction layer;

[0009] Fix the functional layer of the printed circuit board on the surface of the heat-conducting layer. The area on the functional layer corresponding to the high heat-dissipation space is used to install high-heat-generating electronic components, and the area corresponding to the low heat-dissipation space is used to install low-heat-generating electronic components.

[0010] Optionally, the branches are made of styrene-butadiene-styrene (SBS) thermoplastic elastomer.

[0011] Optionally, fixing a pre-prepared skeleton on the insulating base layer of the printed circuit board includes:

[0012] According to the branch structure pattern of the skeleton, selectively perform surface modification treatment on the surface of the insulating base layer so that the surface energy of the surface of the insulating base layer in the predetermined contact area with the branches of the skeleton is higher than that of other areas;

[0013] Selectively apply an adhesive with temperature-responsive characteristics in the predetermined contact area;

[0014] Place the skeleton on the insulating base layer so that the branches of the skeleton correspond to the predetermined contact area;

[0015] Fix the skeleton on the insulating base layer by adjusting the temperature of the adhesive and the pressure applied to the skeleton.

[0016] Optionally, the adhesive with temperature-responsive characteristics is an epoxy resin-based thermosetting adhesive. The process of fixing the skeleton on the insulating base layer by adjusting the temperature of the adhesive and the pressure applied to the skeleton includes:

[0017] Set the temperature in the range of 35 - 45 °C, apply a pressure of 0.03 - 0.07 MPa to the skeleton, and hold for 10 - 15 minutes;

[0018] Increase the temperature to the range of 55 - 65 °C at a heating rate of 2 - 5 °C / minute, and at the same time increase the pressure to 0.08 - 0.12 MPa, and hold for 20 - 30 minutes;

[0019] Reduce the temperature to the range of 45 - 55 °C, and reduce the pressure to 0.03 - 0.07 MPa, and continue for 20 - 40 seconds;

[0020] Increase the temperature to the range of 75 - 85 °C at a heating rate of 2 - 5 °C / minute, increase the pressure to 0.18 - 0.22 MPa, and hold for 50 - 70 minutes;

[0021] Reduce the temperature to room temperature at a cooling rate of 1 - 2 °C / minute, and at the same time reduce the pressure to 0 MPa at a rate of 0.01 - 0.03 MPa / minute.

[0022] Optionally, according to the layout and heat generation characteristics of the predetermined electronic components, after dividing the plurality of heat dissipation spaces into at least one high heat dissipation space and at least one low heat dissipation space, it includes:

[0023] Identifying at least one partition branch among the plurality of branches located between the high heat dissipation space and the low heat dissipation space;

[0024] Providing a heat insulation groove on the surface of the partition branch facing away from the insulating base layer, wherein the heat insulation groove extends along the length direction of the partition branch.

[0025] Optionally, the branch is made of styrene-butadiene-styrene (SBS) thermoplastic elastomer;

[0026] The step of providing a heat insulation groove on the surface of the partition branch facing away from the insulating base layer includes:

[0027] Obtaining the predetermined heat insulation groove position on the surface of the partition branch facing away from the insulating base layer;

[0028] Forming a plurality of positioning holes penetrating the thickness direction of the partition branch at the predetermined heat insulation groove position of the partition branch;

[0029] Connecting the plurality of positioning holes to form the heat insulation groove.

[0030] Optionally, the step of forming a plurality of positioning holes penetrating the thickness direction of the partition branch at the predetermined heat insulation groove position of the partition branch includes:

[0031] Forming a plurality of surface activation regions at the predetermined heat insulation groove position;

[0032] Applying a photosensitive swelling agent on the surface activation regions;

[0033] Performing selective light irradiation on the regions applied with the photosensitive swelling agent to induce controllable swelling of the SBS material in the light irradiation regions;

[0034] Dissolving the swollen regions to form the plurality of positioning holes.

[0035] Optionally, the material of the first thermal conductive filler includes:

[0036] 70-80 parts by weight of an epoxy resin matrix;

[0037] 15-25 parts by weight of carbon nanotubes;

[0038] 3-5 parts by weight of aluminum nitride powder;

[0039] 1-2 parts by weight of a coupling agent;

[0040] The second thermal conductive filler includes:

[0041] 80 - 90 parts by weight of an epoxy resin matrix;

[0042] 8 - 15 parts by weight of carbon nanotubes;

[0043] 1 - 3 parts by weight of aluminum nitride powder;

[0044] 1 - 2 parts by weight of a coupling agent;

[0045] Wherein, the epoxy resin matrix of the first thermal conductive filler and the epoxy resin matrix in the second thermal conductive filler are both mixtures of bisphenol A type epoxy resin and an anhydride curing agent, and the coupling agent is a silane coupling agent.

[0046] Optionally, injecting the first thermal conductive filler into the high heat dissipation space and performing a curing treatment includes:

[0047] Providing a detachable cofferdam structure at the periphery of the insulating base layer, and the height of the cofferdam structure is not lower than the height of the branches;

[0048] Applying a negative pressure environment with a vacuum degree not lower than -0.09 MPa to the high heat dissipation space;

[0049] While maintaining the negative pressure state, filling the high heat dissipation space with the pre - degassed first thermal conductive filler at an injection rate not exceeding 2 mL / s until the filling height reaches 99% - 100% of the height of the branches;

[0050] After completing the filling of the first thermal conductive filler, maintaining the negative pressure state for 5 - 10 minutes;

[0051] While maintaining the negative pressure state, raising the temperature to 90% - 95% of the gel point temperature of the first thermal conductive filler and holding for 10 - 15 minutes to make the filler form a semi - gel state;

[0052] Raising the temperature to the curing starting temperature of the first thermal conductive filler and holding for 20 - 30 minutes to make the filler as a whole form a preliminary cross - linked network structure;

[0053] After lowering the temperature to room temperature, removing the detachable cofferdam structure;

[0054] Coating a layer of thermal conductive interface material with a thickness of 10 - 20 μm on the surface of the first thermal conductive filler and the surface of the skeleton branches;

[0055] Performing a post - curing treatment on the entire surface, and holding for 60 - 90 minutes under the condition that the temperature is 95% - 100% of the curing peak temperature of the first thermal conductive filler to ensure that the thermal conductive filler and the thermal conductive interface material are completely cured and cross - linked.

[0056] Optionally, the functional layer for fixing the printed circuit board on the surface of the heat-conducting layer includes:

[0057] Prepare the functional layer material, which is epoxy prepreg;

[0058] Perform plasma treatment on the surface of the heat-conducting layer;

[0059] Form a preset microstructural pattern on the surface of the treated heat-conducting layer;

[0060] Place the functional layer material on the surface of the heat-conducting layer with the microstructural pattern;

[0061] Under the conditions of a temperature of 120 - 150 °C and a pressure of 0.5 - 1.5 MPa, perform vacuum-assisted lamination on the functional layer material;

[0062] Perform annealing treatment on the laminated structure and hold it at 80 - 100 °C for 2 - 4 hours.

[0063] The preparation process of the high heat-conducting composite substrate proposed by the present invention adopts a skeleton structure composed of multiple interconnected branches. This structure not only provides mechanical support but also creates multiple independently controllable heat dissipation spaces. By dividing these heat dissipation spaces into high heat dissipation spaces and low heat dissipation spaces, the present invention realizes differential thermal management for components with different heat generation characteristics. This design overcomes the limitation of the uniform thermal conductivity of the traditional integral metal layer and can specifically meet the heat dissipation requirements of different regions. The present invention injects fillers with different thermal conductivities into the high and low heat dissipation spaces respectively and performs curing treatment, which further enhances the accuracy and efficiency of thermal management. Fillers with high thermal conductivity are used in the high heat dissipation spaces to ensure that high heat generation components obtain sufficient heat dissipation; while fillers with low thermal conductivity are used in the low heat dissipation spaces to provide moderate heat dissipation capacity for low heat generation components. This differential filler strategy enables the high heat generation regions to dissipate heat quickly, preventing the formation of hot spots, and at the same time avoiding excessive heat dissipation for low heat generation regions. In this way, the present invention realizes a more balanced temperature distribution inside the PCB and improves the overall heat dissipation efficiency. This precise thermal management method not only solves the problem of uneven heat distribution in traditional methods but also provides the most suitable heat dissipation environment for components with different heat generation characteristics, ensuring the reliable operation of high heat generation components and avoiding excessive cooling of low heat generation components. Thus, while ensuring the performance of the PCB, it optimizes resource utilization and provides important support for the development of high-performance and high-reliability electronic devices. Description of the Drawings

[0064] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on the structures shown in these drawings.

[0065] Figure 1 It is a schematic diagram of an embodiment of the preparation process of the high - thermal - conductivity composite substrate in the embodiment of the present invention;

[0066] Figure 2 It is a schematic structural diagram of an embodiment of the high - thermal - conductivity composite substrate in the embodiment of the present invention.

[0067] Explanation of the reference numerals in the drawings:

[0068] 1. Insulating base layer; 2. Skeleton; 21. Branches; 211. Heat - insulating groove; 212. High - heat - dissipation space; 213. Low - heat - dissipation space; 3. Functional layer; 4. High - heat - generating electronic component; 5. Low - heat - generating electronic component.

[0069] The realization of the object, functional features and advantages of the present invention will be further described with reference to the embodiments and the drawings. Detailed implementation manners

[0070] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0071] It should be noted that if there are directional indications (such as up, down, left, right, front, back...) involved in the embodiments of the present invention, the directional indications are only used to explain the relative positional relationship and movement conditions between components in a specific posture (as shown in the drawings). If the specific posture changes, the directional indications will also change accordingly.

[0072] In addition, the descriptions involving "first", "second", etc. in the present invention are for descriptive purposes only, and should not be construed as indicating or implying their relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one such feature. In addition, "and / or" throughout the text includes three scenarios. Taking A and / or B as an example, it includes the technical solution of A, the technical solution of B, and the technical solution that both A and B are satisfied at the same time. In addition, the technical solutions between various embodiments can be combined with each other, which must be based on the ability of those of ordinary skill in the art to implement. When the combination of technical solutions results in contradictions or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0073] An embodiment of the present application provides a preparation process for a high thermal conductivity composite substrate. Figure 1 It is a flowchart of a preparation process for a high thermal conductivity composite substrate provided by an embodiment of the present application. For ease of understanding the structure of the present application, please refer to Figure 2 a simple schematic diagram of the high thermal conductivity composite substrate. The branches in the figure are arranged in a parallel manner. The structure where the branches are blocked by the functional layer can be connected by some horizontally extending branches to achieve a more refined division of the space. In other embodiments, the branches can also be arranged in other arrangements, such as irregular arrangements, which are not specifically limited herein. In this embodiment, the method includes:

[0074] Please refer to Figure 1 , fix the pre-prepared skeleton 2 on the insulating base layer 1 of the printed circuit board. The skeleton 2 is composed of a plurality of interconnected branches 21, and the branches 21 and the surface of the insulating base layer 1 jointly define a plurality of heat dissipation spaces;

[0075] In an embodiment of the present invention, the branch 21 is made of styrene-butadiene-styrene (SBS) thermoplastic elastomer.

[0076] Specifically, the SBS material has excellent flexibility and elasticity, which enables the structure of the skeleton 2 made of it to adapt to various stresses and deformations during the manufacturing and use of the PCB, reducing the risk of structural damage caused by thermal expansion or mechanical stress. Secondly, the SBS material has good heat resistance and can maintain stable physical and mechanical properties within the operating temperature range of the electronic device, which is crucial for maintaining the long-term effectiveness of the heat dissipation structure. In addition, the SBS material has good compatibility with the epoxy resin-based composite material, which is conducive to forming a strong interfacial bond between the skeleton 2 and the heat-conducting filler, improving the stability and heat dissipation efficiency of the overall structure. The SBS material also has a low thermal conductivity, and this characteristic enables it to form a certain thermal resistance between the high and low heat dissipation regions, contributing to more precise heat control and distribution. Finally, the SBS material has excellent processing performance and can precisely manufacture complex skeleton 2 structures through methods such as injection molding or 3D printing, which provides technical possibilities for realizing differentiated heat dissipation designs.

[0077] In an embodiment of the present invention, fixing the pre-prepared skeleton 2 on the insulating base layer 1 of the printed circuit board includes: selectively performing surface modification treatment on the surface of the insulating base layer 1 according to the structure pattern of the branches 21 of the skeleton 2, so that the surface energy of the surface of the insulating base layer 1 in the predetermined contact area with the branches 21 of the skeleton 2 is higher than other areas; selectively applying an adhesive with temperature-responsive characteristics in the predetermined contact area; placing the skeleton 2 on the insulating base layer 1 so that the branches 21 of the skeleton 2 correspond to the predetermined contact area; and fixing the skeleton 2 on the insulating base layer 1 by adjusting the temperature of the adhesive and the pressure applied to the skeleton 2.

[0078] Specifically, according to the pre-designed structure pattern of the branches 21 of the skeleton 2, the surface of the insulating base layer 1 is selectively surface-modified using low-temperature plasma treatment technology. This step uses a mask, and the openings on the mask correspond to the predetermined contact areas of the branches 21 of the skeleton 2. The mask is covered on the surface of the insulating base layer 1 and then placed in the plasma treatment chamber. By controlling the power of the plasma (usually 50 - 200 W) and the treatment time (generally 30 - 120 seconds), only the area at the openings of the mask is treated, thereby achieving selective surface modification. This treatment increases the surface roughness and polar groups, significantly improving the surface energy and providing a good foundation for the subsequent adhesion of the adhesive. Next, a temperature-responsive adhesive is applied to the predetermined contact areas that have undergone surface modification using a dispensing device. This device has an XYZ-axis control system and a micro-dispensing valve (this device belongs to the prior art and the solution of this application does not improve this device), and can precisely control the application position and amount of the adhesive. For example, the dispensing pressure can be set to 0.1 - 0.5 MPa and the dispensing time to 0.1 - 0.5 seconds to ensure that the amount of adhesive at each predetermined contact point is uniform and appropriate. The selected adhesive is in a low-viscosity state at room temperature (such as 500 - 1000 cps) and rapidly cures after heating, and this characteristic provides an operation time window for the subsequent positioning and fixing of the skeleton 2.

[0079] Subsequently, the pre-prepared SBS skeleton 2 is placed on the insulating base layer 1 using a mechanical positioning system. This system includes a vision alignment module and a precision robotic arm, and can achieve a positioning accuracy of ±10 μm. Through the alignment marks pre-set on the skeleton 2 and the base layer, the system can automatically complete the precise placement of the skeleton 2, ensuring that the branches 21 of the skeleton 2 precisely correspond to the predetermined contact areas.

[0080] Finally, the entire assembly is placed in a precision temperature-controlled press for curing. The equipment can precisely control the temperature (accuracy ±1°C) and pressure (accuracy ±0.01 MPa). Through multi-step temperature and pressure control, a high-quality bond between the skeleton 2 and the base layer is achieved. This fine process control not only ensures a firm bond between the skeleton 2 and the base layer, but also minimizes the generation of internal stress, effectively improving the stability and reliability of the entire structure, laying a solid foundation for subsequent differential thermal filling.

[0081] In one embodiment of the present invention, the temperature-responsive adhesive is an epoxy-based thermosetting adhesive. Fixing the skeleton 2 on the insulating base layer 1 by adjusting the temperature of the adhesive and the pressure applied to the skeleton 2 includes: setting the temperature in the range of 35 - 45 °C, applying a pressure of 0.03 - 0.07 MPa to the skeleton 2, and maintaining for 10 - 15 minutes; increasing the temperature to the range of 55 - 65 °C at a heating rate of 2 - 5 °C / minute, while increasing the pressure to 0.08 - 0.12 MPa and maintaining for 20 - 30 minutes; reducing the temperature to the range of 45 - 55 °C, reducing the pressure to 0.03 - 0.07 MPa, and lasting for 20 - 40 seconds; increasing the temperature to the range of 75 - 85 °C at a heating rate of 2 - 5 °C / minute, increasing the pressure to 0.18 - 0.22 MPa, and maintaining for 50 - 70 minutes; reducing the temperature to room temperature at a cooling rate of 1 - 2 °C / minute, while reducing the pressure to 0 MPa at a rate of 0.01 - 0.03 MPa / minute.

[0082] Specifically, the temperature is set within the range of 35 - 45 °C, and at the same time, a pressure of 0.03 - 0.07 MPa is applied to the skeleton 2 and maintained for 10 - 15 minutes. The purpose of this stage is to evenly spread the adhesive and at the same time allow for minor position adjustments of the skeleton 2. For example, a hot press with a temperature control system can be used, with the temperature accuracy controlled within ±0.5 °C and the pressure accuracy controlled within ±0.01 MPa. Then, the temperature is increased to within the range of 55 - 65 °C at a heating rate of 2 - 5 °C per minute, and at the same time, the pressure is increased to 0.08 - 0.12 MPa and maintained for 20 - 30 minutes. In this stage, the adhesive begins to undergo a cross-linking reaction, the viscosity gradually increases, and the position of the skeleton 2 is initially fixed. Subsequently, the temperature is reduced to within the range of 45 - 55 °C, and the pressure is reduced to 0.03 - 0.07 MPa and maintained for 20 - 40 seconds. This short stage of temperature reduction and pressure reduction can release some internal stress and improve the stability of the final structure. Immediately afterwards, the temperature is again increased to within the range of 75 - 85 °C at a heating rate of 2 - 5 °C per minute, and the pressure is increased to 0.18 - 0.22 MPa and maintained for 50 - 70 minutes. This is the key stage for the complete curing of the adhesive. The high temperature and high pressure ensure the full progress of the cross-linking reaction and form a strong bonding interface. Finally, the temperature is reduced to room temperature at a cooling rate of 1 - 2 °C per minute, and at the same time, the pressure is reduced to 0 MPa at a rate of 0.01 - 0.03 MPa per minute. This slow cooling and pressure reduction process can minimize the generation of thermal stress and ensure the integrity of the structure. The entire process can be achieved through a programmed hot press equipment, such as a precision hot press equipped with a PID control system, which can automatically complete the entire curing process according to the preset temperature and pressure curves. This multi-step, finely controlled curing process not only ensures the full curing of the adhesive and excellent bonding strength, but also effectively reduces the generation of internal stress and significantly improves the reliability and durability of the entire structure.

[0083] Please continue to refer to Figure 1 According to the layout and heat generation characteristics of the predetermined electronic components, the plurality of heat dissipation spaces are divided into at least one high heat dissipation space 212 and at least one low heat dissipation space 213;

[0084] Specifically, it is necessary to obtain the detailed information of all electronic components on the PCB, including their positions, dimensions, and estimated power consumption. This can be achieved through the export function of the PCB design software. For example, by using the BOM (Bill of Materials) export function of Altium Designer, the position coordinates and power consumption data of the components can be obtained. Then, using a thermal simulation software, such as ANSYS Icepak, a virtual model of the PCB is created, and thermal analysis is performed based on the power consumption data of the components. By setting a threshold (for example, the area where the power consumption is greater than 2W is defined as the high heat dissipation area), the surface of the PCB is divided into different heat zones. Then, the information of these heat zones is superimposed on the mesh of the skeleton 2 structure to determine which heat dissipation type each space surrounded by the branches 21 of the skeleton 2 belongs to. For example, if more than 50% of the area within a space belongs to the high heat dissipation area, then this space is defined as the high heat dissipation space 212. Finally, a heat dissipation space distribution map is generated to guide the subsequent process of injecting the thermal conductive filler.

[0085] In an embodiment of the present invention, after dividing the plurality of heat dissipation spaces into at least one high heat dissipation space 212 and at least one low heat dissipation space 213 according to the layout and heat generation characteristics of the predetermined electronic components, it includes: identifying at least one separating branch 21 located between the high heat dissipation space 212 and the low heat dissipation space 213 among the plurality of branches 21; setting a heat insulation groove 211 on the surface of the separating branch 21 facing away from the insulating base layer 1, wherein the heat insulation groove 211 extends along the length direction of the separating branch 21.

[0086] Specifically, the setting of the heat insulation groove 211 can effectively reduce the heat transfer from the high heat generation heat source to the low heat generation heat source. Secondly, the existence of the heat insulation groove 211 creates a thermal resistance, which helps to maintain the temperature gradient between the high and low heat dissipation spaces 213 and improves the thermal management efficiency of the entire PCB. In addition, the design of the heat insulation groove 211 also increases the flexibility of the entire structure, helps to reduce the stress caused by thermal expansion, and improves the reliability and service life of the PCB.

[0087] Specifically, based on the embodiment where the branch 21 is made of styrene-butadiene-styrene (SBS) thermoplastic elastomer, the setting of the heat insulation groove 211 on the surface of the separating branch 21 facing away from the insulating base layer 1 includes: obtaining the positions of the predetermined heat insulation grooves 211 on the surface of the separating branch 21 facing away from the insulating base layer 1; forming a plurality of positioning holes penetrating the thickness direction of the separating branch 21 at the predetermined positions of the heat insulation grooves 211 on the separating branch 21; and connecting the plurality of positioning holes to form the heat insulation groove 211.

[0088] Specifically, in the process of implementing the separation of the high and low heat dissipation spaces 213 and the setting of the heat insulation grooves 211, it is first necessary to identify the separation branch 21 located between the high heat dissipation space 212 and the low heat dissipation space 213. This step can be completed by analyzing the aforementioned heat dissipation space distribution map. Specifically, image processing software such as MATLAB can be used to perform edge detection on the heat dissipation space distribution map, find the boundary of the high and low heat dissipation spaces 213, and compare it with the structure diagram of the skeleton 2 to determine the position of the separation branch 21. For example, if one side of a branch 21 is the high heat dissipation space 212 and the other side is the low heat dissipation space 213, then this branch 21 is identified as the separation branch 21.

[0089] After determining the separation branch 21, the next step is to set the heat insulation groove 211 on the surface of the separation branch 21 facing away from the insulation base layer 1. This process first requires obtaining the position of the predetermined heat insulation groove 211 on the surface of the separation branch 21 facing away from the insulation base layer 1. 3D modeling software such as SolidWorks can be used to mark the ideal position of the heat insulation groove 211 on the 3D model of the separation branch 21. This position can be selected on the center line of the branch 21 to ensure the best heat insulation effect.

[0090] Next, a plurality of positioning holes penetrating the thickness direction of the separation branch 21 are formed at the position of the predetermined heat insulation groove 211. This step can be completed using a laser drilling device. For example, a pulsed Nd:YAG laser with a wavelength of 1064 nm, a pulse width of 10 ns, and a single pulse energy of 0.1 mJ can be used. By controlling the focus position and the number of pulses of the laser, through holes with a diameter of 50 - 100 microns can be accurately formed on the SBS material. The spacing of these positioning holes is set to 1.5 - 2 times the hole diameter to ensure the smooth progress of the subsequent connection process.

[0091] After forming the positioning holes, the last step is to connect these positioning holes to form a complete heat insulation groove 211. This process can be achieved using selective laser ablation technology. A CO2 laser with a wavelength of 10.6 μm and a power set between 10 - 20 W is used. By controlling the scanning path of the laser, the material between the positioning holes is gradually removed. The scanning speed of the laser is usually set between 10 - 20 mm / s to ensure that the material is fully removed without over-damaging the surrounding structure.

[0092] By forming the positioning holes first and then connecting them, the positional accuracy and consistency of the heat insulation groove 211 can be ensured. Secondly, this method has less thermal impact on the SBS material, avoiding structural deformation that may be caused by large-area thermal damage. Moreover, by controlling the size and spacing of the positioning holes, the width and depth of the heat insulation groove 211 can be flexibly adjusted, thereby optimizing the heat insulation effect. Finally, this method also allows for the retention of some tiny connecting bridges when necessary, providing sufficient heat insulation while not completely cutting off the structural continuity of the branch 21, which is beneficial to maintaining the mechanical strength of the overall framework 2.

[0093] In an embodiment of the present invention, forming a plurality of positioning holes penetrating the thickness direction of the partition branch 21 at the position of the predetermined heat insulation groove 211 of the partition branch 21 includes: forming a plurality of surface activation regions at the position of the predetermined heat insulation groove 211; applying a photosensitive swelling agent on the surface activation regions; performing selective light irradiation on the regions where the photosensitive swelling agent is applied to induce controllable swelling of the SBS material in the light-irradiated regions; and dissolving the swollen regions to form the plurality of positioning holes.

[0094] Specifically, during the process of forming the heat insulation groove 211, first, a plurality of surface activation regions need to be formed at the position of the predetermined heat insulation groove 211. This step can be completed by plasma treatment technology. Specifically, an oxygen plasma treatment device can be used to treat the surface of the SBS material at a low pressure of 5 - 20 Pa with a power of 50 - 100 W. The treatment time is controlled within 30 - 60 seconds, which can increase the polar groups on the surface without overly damaging the material, improving the adhesion ability of the subsequent photosensitive swelling agent. To achieve precise local treatment, a laser-cut micro-hole mask can be used, and the openings on the mask precisely correspond to the positions of the predetermined heat insulation grooves 211.

[0095] After the surface activation is completed, the next step is to apply the photosensitive swelling agent on the activation regions. The photosensitive swelling agent selected here is an organic compound sensitive to ultraviolet light. For example, a polymer containing azobenzene groups can be used. This swelling agent will change its molecular configuration and cause volume expansion when irradiated with light of a specific wavelength. The application process can adopt micro-dispensing technology, using a dispensing device such as a micro-level piezoelectric dispensing valve to precisely apply the swelling agent to the activation regions.

[0096] Next, selective illumination is performed on the area where the photosensitive swelling agent is applied to induce controlled swelling of the SBS material in the illuminated area. This step is completed using an ultraviolet laser equipped with an optical system. For example, an ultraviolet LED light source with a wavelength of 365 nm can be selected, and the light spot is reduced to a diameter of 100 - 200 microns through an optical focusing system. The illumination intensity is controlled at 50 - 100 mW / cm², and the irradiation time is 10 - 30 seconds. This illumination can not only activate the swelling agent but also control the degree of swelling, thereby achieving controlled swelling of the SBS material.

[0097] The last step is to dissolve the swollen area to form multiple positioning holes. This process is achieved through selective solvent treatment. The selected solvent needs to be able to dissolve the swollen SBS material while having less impact on the unswollen area. For example, tetrahydrofuran (THF) is used as the solvent, and the solvent is precisely applied to the swollen area through micro-injection technology. The dosage and action time of the solvent need to be precisely controlled. Usually, a pulsed micro-injection valve is used, and 1 - 3 drops of solvent are sprayed on each swollen area, with each drop having a volume of about 10 - 20 nanoliters. After the dissolution process lasts for 20 - 40 seconds, an inert gas such as nitrogen is used for purging to remove the dissolution products and residual solvent, finally forming the required positioning holes.

[0098] After the positioning holes are formed, the process of connecting these holes to form the heat insulation groove 211 can be achieved through various methods. A commonly used method is to use precision laser cutting technology. For example, a femtosecond laser is used to remove materials between the positioning holes in a pulsed manner. Another method is to use chemical etching technology, where a specific etching agent is precisely applied to the area between the positioning holes, and the etching time is controlled to form the required channels. Mechanical machining using a micro-mill can also be considered. Through a precisely controlled micro CNC device, the materials between the positioning holes are removed to form a continuous heat insulation groove 211. This application does not make specific restrictions on this part of the content.

[0099] Please continue to refer to Figure 1 , inject the first thermal conductive filler into the high heat dissipation space 212 and perform a curing treatment, inject the second thermal conductive filler into the low heat dissipation space 213 and perform a curing treatment. The thermal conductivity coefficient of the first thermal conductive filler is greater than that of the second thermal conductive filler. The first thermal conductive filler and the second thermal conductive filler combine with the skeleton 2 to form a thermal conductive layer;

[0100] In an embodiment of the present invention, the material of the first thermal conductive filler includes: 70 - 80 parts by weight of an epoxy resin matrix; 15 - 25 parts by weight of carbon nanotubes; 3 - 5 parts by weight of aluminum nitride powder; 1 - 2 parts by weight of a coupling agent;

[0101] The second thermal conductive filler includes: 80-90 parts by weight of an epoxy resin matrix; 8-15 parts by weight of carbon nanotubes; 1-3 parts by weight of aluminum nitride powder; 1-2 parts by weight of a coupling agent;

[0102] Among them, the epoxy resin matrix of the first thermal conductive filler and the epoxy resin matrix in the second thermal conductive filler are both mixtures of bisphenol A epoxy resin and an anhydride curing agent, and the coupling agent is a silane coupling agent.

[0103] Specifically, the epoxy resin matrix, as the main component, provides good mechanical strength and adhesion. The addition of carbon nanotubes significantly improves the thermal conductivity, and the higher proportion of carbon nanotubes (15-25 parts by weight) in the first thermal conductive filler ensures excellent thermal conductivity in the high heat dissipation space 212. The aluminum nitride powder, as an auxiliary thermal conductive filler, further enhances the heat conduction ability and helps to reduce the coefficient of thermal expansion. The use of the coupling agent improves the interfacial bonding between the filler and the epoxy resin matrix, enhancing the overall performance of the composite material. The combination of bisphenol A epoxy resin and an anhydride curing agent provides excellent thermal stability and mechanical properties, and the selection of the silane coupling agent further enhances the compatibility between the filler and the matrix. This formulation achieves different thermal conductivity performances in the high and low heat dissipation spaces 213 and ensures the structural integrity and long-term stability of the entire thermal conductive layer.

[0104] In an embodiment of the present invention, injecting the first thermal conductive filler into the high heat dissipation space 212 and performing a curing treatment includes: setting a detachable cofferdam structure at the periphery of the insulating base layer 1, and the height of the cofferdam structure is not lower than the height of the branch 21; applying a negative pressure environment with a vacuum degree not lower than -0.09 MPa to the high heat dissipation space 212; while maintaining the negative pressure state, filling the first thermal conductive filler that has been pre-degassed into the high heat dissipation space 212 at an injection rate not exceeding 2 mL / s until the filling height reaches 99%-100% of the height of the branch 21; after completing the filling of the first thermal conductive filler, maintaining the negative pressure state for 5-10 minutes; while maintaining the negative pressure state, raising the temperature to 90%-95% of the gel point temperature of the first thermal conductive filler and holding for 10-15 minutes to make the filler form a semi-gel state; raising the temperature to the curing starting temperature of the first thermal conductive filler and holding for 20-30 minutes to make the filler as a whole form a preliminary cross-linked network structure; after cooling the temperature to room temperature, removing the detachable cofferdam structure; coating a layer of thermal conductive interface material with a thickness of 10-20 μm on the surface of the first thermal conductive filler and the surface of the skeleton 2 branch 21; performing a post-curing treatment on the entire surface, and holding for 60-90 minutes under the condition that the temperature is 95%-100% of the curing peak temperature of the first thermal conductive filler to ensure that the thermal conductive filler and the thermal conductive interface material are completely cured and cross-linked.

[0105] Specifically, a detachable cofferdam structure is provided at the periphery of the insulating base layer 1. The height of the cofferdam structure is not lower than the height of the branch 21. The purpose of this step is to prevent the thermal conductive filler from overflowing during the injection process. The cofferdam structure can be made of high-temperature resistant silicone material and formed by a mold to ensure its tight fit with the insulating base layer 1. Next, a negative pressure environment of not less than -0.09 MPa is applied to the high heat dissipation space 212. This can be achieved by connecting a vacuum pump and covering the entire working area with a sealing cover. The creation of the negative pressure environment helps to remove the air in the space and reduce the possible bubbles in the filler.

[0106] While maintaining the negative pressure state, the pre-degassed first thermal conductive filler is filled at an injection rate of not more than 2 mL / s. This process is completed using injection equipment. For example, an injection system controlled by a servo motor can be used to control the injection rate. During the filling process, a real-time monitoring system, such as a high-definition camera or a laser rangefinder, is used to monitor the filling height to ensure that the filling height reaches 99%-100% of the height of the branch 21. This precise control can prevent overflow caused by overfilling and ensure the sufficiency of filling.

[0107] After the first thermal conductive filler is filled, the negative pressure state is maintained for 5 - 10 minutes. The purpose of this step is to allow the filler to fully penetrate into all corners of the skeleton 2 structure and further remove any possible remaining tiny bubbles. Subsequently, while maintaining the negative pressure state, the temperature is raised to 90%-95% of the gel point temperature of the first thermal conductive filler and maintained for 10 - 15 minutes. This step can be completed using a temperature control system. For example, using Peltier elements or infrared heating devices, combined with temperature sensors, a temperature control accuracy of ±1°C can be achieved. The purpose of this stage is to make the filler form a semi-gel state in preparation for the subsequent cross-linking reaction.

[0108] Next, the temperature is raised to the curing starting temperature of the first thermal conductive filler and maintained for 20 - 30 minutes to form a preliminary cross-linked network structure throughout the filler. This process is achieved through a programmed temperature control system. For example, using a PID control algorithm to ensure the smoothness and accuracy of the temperature curve. The formation of the preliminary cross-linked network helps the filler maintain its shape and prevent flow during subsequent operations.

[0109] After the temperature drops to room temperature, the detachable cofferdam structure is removed. A thin and flexible plastic scraper can be used to slowly insert and separate along the contact line between the cofferdam and the substrate to avoid damaging the cured filler.

[0110] Apply a layer of thermal interface material with a thickness of 10 - 20 μm on the surface of the first thermal conductive filler and the surface of the branches 21 of the skeleton 2. This is completed by coating equipment, such as using an automated spraying system or screen printing equipment, to ensure a uniform coating thickness. The application of the thermal interface material can fill in tiny surface irregularities and improve the heat conduction efficiency.

[0111] Finally, perform a post-curing treatment on the entire surface, maintaining it at 95% - 100% of the curing peak temperature of the first thermal conductive filler for 60 - 90 minutes. This process can be carried out in an industrial oven, which needs to have precise temperature control capabilities and uniform heat distribution characteristics. The post-curing treatment ensures that the thermal conductive filler and the thermal interface material are fully cured and cross-linked, maximizing their thermal and mechanical properties.

[0112] The process of injecting the second thermal conductive filler into the low heat dissipation space 213 and performing the curing treatment is similar to that of the high heat dissipation space 212, but attention needs to be paid to adjusting the injection rate and curing parameters to adapt to the characteristics of the second thermal conductive filler. For example, since the content of carbon nanotubes in the second thermal conductive filler is relatively low, its viscosity may be lower, so the injection rate can be appropriately increased, but still kept below 2 mL / s. The curing temperature and time also need to be adjusted according to the characteristics of the second thermal conductive filler, and usually, a slightly lower temperature and a shorter curing time can be adopted.

[0113] It should be noted that the thermal conductivity of the first thermal conductive filler is greater than that of the second thermal conductive filler, which is achieved by adjusting the ratio of carbon nanotubes and aluminum nitride powder in the two fillers. The higher proportion of thermal conductive filler in the high heat dissipation space 212 ensures effective heat dissipation for high-heat-generating components, while the lower thermal conductivity in the low heat dissipation space 213 avoids excessive heat dissipation, achieving an overall heat balance. The thermal conductive layer formed by combining the two thermal conductive fillers with the SBS skeleton 2 not only provides differentiated heat dissipation capabilities but also ensures the mechanical stability and thermal management efficiency of the entire structure.

[0114] Please continue to refer to Figure 1 , fix the functional layer 3 of the printed circuit board on the surface of the thermal conductive layer. The area of the functional layer 3 corresponding to the high heat dissipation space 212 is used to install high-heat-generating electronic components 4, and the area corresponding to the low heat dissipation space 213 is used to install low-heat-generating electronic components 5.

[0115] In one embodiment of the present invention, the functional layer 3 for fixing the printed circuit board on the surface of the heat-conducting layer includes: preparing the material of the functional layer 3, where the material of the functional layer 3 is epoxy prepreg; performing plasma treatment on the surface of the heat-conducting layer; forming a preset microstructural pattern on the surface of the heat-conducting layer after treatment; placing the material of the functional layer 3 on the surface of the heat-conducting layer with the microstructural pattern; performing vacuum-assisted lamination on the material of the functional layer 3 under the conditions of a temperature of 120 - 150 °C and a pressure of 0.5 - 1.5 MPa; performing annealing treatment on the laminated structure and maintaining it at 80 - 100 °C for 2 - 4 hours.

[0116] Specifically, first, it is necessary to prepare the material of the functional layer 3, and epoxy prepreg is selected as the main material. Epoxy prepreg is a semi-cured composite material, which is pre-impregnated with epoxy resin and glass fiber or other reinforcing materials. The advantage of this material selection lies in its excellent electrical insulation, mechanical strength, and processing performance, making it suitable as the substrate of the printed circuit board. During the preparation stage, the prepreg needs to be cut into a shape matching the size of the heat-conducting layer and stored in a constant temperature and humidity environment to ensure the stability of the material properties.

[0117] Next, perform plasma treatment on the surface of the heat-conducting layer. The purpose of this step is to increase the surface energy and improve the bonding strength between the functional layer 3 and the heat-conducting layer. Plasma treatment can be completed using a low-temperature plasma treatment device. For example, using oxygen as the working gas, treat it at a power of 50 - 100 W for 30 - 60 seconds. During the treatment process, a large number of active groups will be generated on the surface of the heat-conducting layer by the plasma. These groups can form chemical bonds with the material of the functional layer 3, significantly enhancing the interfacial bonding strength.

[0118] After the plasma treatment, the next step is to form a preset microstructural pattern on the surface of the heat-conducting layer. This step is achieved through micro-nano imprinting technology. Specifically, when operating, first, a mold with a microstructure needs to be fabricated. The mold can be fabricated using electron beam lithography or nanoimprint lithography technology. Then, press the mold onto the surface of the heat-conducting layer and maintain it at a certain temperature (usually 10 - 20 °C above the glass transition temperature of the mold material) and pressure (0.1 - 1 MPa) for several minutes, and a microstructural pattern opposite to the mold can be formed on the surface of the heat-conducting layer. These microstructures can not only increase the interfacial bonding area but also provide a mechanical interlocking effect, further enhancing the bonding strength between the functional layer 3 and the heat-conducting layer.

[0119] After the microstructural pattern is formed, place the material of the functional layer 3 (epoxy prepreg) on the surface of the heat-conducting layer with the microstructural pattern. This step requires careful operation to ensure that the prepreg is closely attached to the surface of the heat-conducting layer, avoiding the generation of bubbles or wrinkles. A vacuum-assisted positioning system can be used to slowly lay the prepreg on the surface of the heat-conducting layer under a slight negative pressure to ensure a perfect fit.

[0120] Subsequently, under the conditions of a temperature of 120 - 150 °C and a pressure of 0.5 - 1.5 MPa, vacuum-assisted lamination is performed on the material of the functional layer 3. This process can be completed in a professional vacuum laminator. First, the entire structure is placed in the vacuum chamber of the laminator, and the vacuum is pumped down to below 0.1 Pa to remove any possible air bubbles between the materials. Then, lamination is carried out according to the preset temperature and pressure curves. The temperature selection is based on the curing characteristics of the epoxy resin, usually 20 - 30 °C above its gel point, while the pressure selection needs to balance the fluidity of the material and the integrity of the structure. The advantage of vacuum-assisted lamination is that it can ensure close contact between the materials, avoid the generation of air bubbles, and thus obtain high-quality lamination results.

[0121] After lamination, the laminated structure is annealed at 80 - 100 °C for 2 - 4 hours. The purpose of annealing is to release the internal stress generated during the lamination process and improve the dimensional stability and mechanical properties of the material. The annealing temperature is selected below the glass transition temperature of the epoxy resin, but high enough to allow the molecular chains to have a certain degree of mobility, thus achieving stress release. The selection of the annealing time needs to balance the sufficiency of stress release and production efficiency.

[0122] It is not difficult to understand that through plasma treatment and the formation of the microstructural pattern, the interfacial bonding strength between the functional layer 3 and the heat-conducting layer is significantly enhanced, improving the reliability of the entire structure. Secondly, the vacuum-assisted lamination technology ensures close contact between the materials, reducing the generation of air bubbles and defects. Finally, the annealing treatment further optimizes the material properties and improves the long-term stability of the entire structure. This precise process control not only achieves high-quality fixation of the functional layer 3 but also provides excellent electrical performance and mechanical strength for the entire PCB, significantly improving the reliability and performance of electronic devices.

[0123] It should be noted that in this application, the distinction between the high-heat-generating electronic component 4 and the low-heat-generating electronic component 5 is based on the heat generated during their operation. The high-heat-generating electronic component 4 usually refers to components that generate a large amount of heat during operation, such as high-performance processors, power amplifiers, or high-power LEDs, etc. These components often require more efficient heat dissipation measures to maintain their normal operating temperatures. The low-heat-generating electronic component 5, on the other hand, is a component that generates relatively less heat during operation, such as memory chips, low-power microcontrollers, etc.

[0124] The above are only the preferred embodiments of the present invention, and do not limit the patent scope of the present invention accordingly. Any equivalent structural transformation made under the inventive concept of the present invention, using the content of the specification and drawings of the present invention, or directly / indirectly applied in other related technical fields, is included within the patent protection scope of the present invention.

Claims

1. A process for preparing a high thermal conductivity composite substrate, characterized in that: include: Fixing a pre-prepared skeleton on the insulating base layer of the printed circuit board, wherein the skeleton is composed of a plurality of interconnected branches, and the branches and the surface of the insulating base layer jointly define a plurality of heat dissipation spaces; According to the layout and heating characteristics of the predetermined electronic components, the plurality of heat dissipation spaces are divided into at least one high heat dissipation space and at least one low heat dissipation space; Identify at least one partitioning branch located between the high heat dissipation space and the low heat dissipation space among the plurality of branches; provide a heat insulation groove on a surface of the partitioning branch away from the insulating base layer, wherein the heat insulation groove extends along the length direction of the partitioning branch; The branches are made of styrene-butadiene-styrene (SBS) thermoplastic elastomer; The heat-insulating groove is provided on the surface of the separating branches away from the insulating base layer, comprising: Obtaining a predetermined heat insulation groove position on the surface of the separation branch away from the insulation base layer; A plurality of positioning holes penetrating the thickness direction of the partitioning branches are formed at the predetermined heat insulation groove position of the partitioning branches; specifically comprising: forming a plurality of surface activation areas at the predetermined heat insulation groove position; applying a photosensitive swelling agent on the surface activation area; selectively irradiating the area to which the photosensitive swelling agent is applied to induce controllable swelling of the SBS material in the irradiated area; dissolving the swollen area to form the plurality of positioning holes; Connecting the plurality of positioning holes to form the heat insulation groove; Injecting a first thermally conductive filler into the high heat dissipation space and performing a curing treatment, injecting a second thermally conductive filler into the low heat dissipation space and performing a curing treatment, the thermal conductivity of the first thermally conductive filler is greater than the thermal conductivity of the second thermally conductive filler, and the first thermally conductive filler and the second thermally conductive filler are combined with the skeleton to form a thermally conductive layer; The functional layer of the printed circuit board is fixed on the surface of the heat-conducting layer, and the area corresponding to the high heat dissipation space on the functional layer is used to install high-heat generating electronic components, and the area corresponding to the low heat dissipation space is used to install low-heat generating electronic components.

2. The process for preparing a high thermal conductivity composite substrate according to claim 1, characterized in that: The method of fixing the pre-prepared skeleton on the insulating base layer of the printed circuit board comprises: According to the branch structure pattern of the skeleton, the surface of the insulating base layer is selectively modified so that the surface energy of the area on the surface of the insulating base layer that is in contact with the branches of the skeleton is higher than that of other areas; selectively applying an adhesive having temperature responsive properties to the predetermined contact area; Placing the skeleton on the insulating base layer so that the branches of the skeleton correspond to the predetermined contact areas; The frame is fixed on the insulating base layer by adjusting the temperature of the adhesive and the pressure applied to the frame.

3. The process for preparing a high thermal conductivity composite substrate according to claim 2, characterized in that: The adhesive with temperature responsiveness is an epoxy resin-based thermosetting adhesive, and the frame is fixed on the insulating base layer by adjusting the temperature of the adhesive and the pressure applied to the frame, comprising: The temperature is set in the range of 35-45°C, and a pressure of 0.03-0.07 MPa is applied to the skeleton for 10-15 minutes; Raise the temperature to 55-65°C at a rate of 2-5°C / min, and simultaneously increase the pressure to 0.08-0.12MPa for 20-30 minutes; Lower the temperature to 45-55°C and the pressure to 0.03-0.07MPa for 20-40 seconds; Raise the temperature to 75-85°C at a heating rate of 2-5°C / min, increase the pressure to 0.18-0.22MPa, and maintain for 50-70 minutes; The temperature was lowered to room temperature at a cooling rate of 1-2°C / min, while the pressure was lowered to 0 MPa at a rate of 0.01-0.03 MPa / min.

4. The process for preparing a high thermal conductivity composite substrate according to claim 1, characterized in that: The material of the first thermally conductive filler includes: 70-80 parts by weight of epoxy resin matrix; 15-25 parts by weight of carbon nanotubes; 3-5 parts by weight of aluminum nitride powder; 1-2 parts by weight of a coupling agent; The second thermally conductive filler comprises: 80-90 parts by weight of epoxy resin matrix; 8-15 parts by weight of carbon nanotubes; 1-3 parts by weight of aluminum nitride powder; 1-2 parts by weight of a coupling agent; The epoxy resin matrix of the first thermally conductive filler and the epoxy resin matrix of the second thermally conductive filler are both a mixture of bisphenol A epoxy resin and an acid anhydride curing agent, and the coupling agent is a silane coupling agent.

5. The process for preparing a high thermal conductivity composite substrate according to claim 4, characterized in that: The step of injecting a first thermally conductive filler into the high heat dissipation space and performing a curing process comprises: A detachable cofferdam structure is arranged at the periphery of the insulating base layer, and the height of the cofferdam structure is not less than the height of the branches; Applying a negative pressure environment with a vacuum degree not less than -0.09 MPa to the high heat dissipation space; While maintaining negative pressure, fill the high heat dissipation space with the pre-degassed first thermal conductive filler at an injection rate not exceeding 2 mL / s until the filling height reaches 99%-100% of the branch height; After the first thermal conductive filler is filled, the negative pressure is maintained for 5-10 minutes; While maintaining negative pressure, raising the temperature to 90%-95% of the gel point temperature of the first thermally conductive filler and maintaining it for 10-15 minutes to allow the filler to form a semi-gel state; Raising the temperature to the curing starting temperature of the first thermally conductive filler and maintaining it for 20-30 minutes to allow the filler to form a preliminary cross-linked network structure; After the temperature is lowered to room temperature, the detachable cofferdam structure is removed; Coating a layer of thermal conductive interface material with a thickness of 10-20 μm on the surface of the first thermal conductive filler and the surface of the skeleton branches; The entire surface is post-cured at a temperature of 95%-100% of the peak curing temperature of the first thermally conductive filler for 60-90 minutes to ensure that the thermally conductive filler and the thermally conductive interface material are completely cured and cross-linked.

6. The process for preparing a high thermal conductivity composite substrate according to claim 1, characterized in that: The functional layer for fixing the printed circuit board on the surface of the heat-conducting layer comprises: Preparing a functional layer material, wherein the functional layer material is an epoxy resin prepreg; Performing plasma treatment on the surface of the heat conducting layer; forming a preset microstructure pattern on the surface of the treated thermal conductive layer; placing the functional layer material on the surface of the heat conductive layer having the microstructure pattern; Under the conditions of a temperature of 120-150° C. and a pressure of 0.5-1.5 MPa, vacuum-assisted lamination is performed on the functional layer material; The laminated structure is annealed at 80-100°C for 2-4 hours.

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