Preparation process of high-thermal-conductivity composite substrate

Abstract

The invention discloses a preparation process of a high-thermal-conductivity composite substrate, and the process comprises the steps: fixing a pre-prepared skeleton on an insulating base layer, and enabling branches of the skeleton and the surface of the insulating base layer to 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 heating characteristics of a predetermined electronic component; a first heat-conducting filler is injected into the high-heat-dissipation space, a second heat-conducting filler is injected into the low-heat-dissipation space, curing treatment is conducted, the heat conductivity coefficient of the first heat-conducting filler is larger than that of the second heat-conducting filler, and the first heat-conducting filler and the second heat-conducting filler are combined with the framework to form a heat-conducting layer; a functional layer of the printed circuit board is fixed on the surface of the heat conduction layer, the area, corresponding to the high-heat-dissipation space, of the functional layer is used for installing high-heat-dissipation electronic elements, and the area, corresponding to the low-heat-dissipation space, of the functional layer is used for installing low-heat-dissipation electronic elements According to the technical scheme, different heat conduction measures can be adopted for different heating elements.

Description

Technical Field

[0001] The invention relates to the technical field of printed circuit board preparation, and in particular to a preparation process of a high thermal conductivity composite substrate. Background Art

[0002] Printed circuit boards (PCBs) are an indispensable core component in modern electronic devices, providing mechanical support and electrical connections for various electronic components. With the miniaturization and high performance of electronic devices, the density of components on PCBs continues to increase, and power consumption also rises, which leads to serious thermal management issues. Excessive temperatures will not only reduce the performance and life of electronic components, but may also cause safety hazards. Therefore, effective heat dissipation and thermal conductivity design are essential to ensure the reliability and performance of PCBs, which has become a key challenge in electronic product design.

[0003] At present, PCB heat dissipation usually uses an integral metal layer for heat conduction. Although this method is simple and direct, it has significant defects. Since the thermal conductivity of the overall metal layer is uniform, it is impossible to take differentiated heat dissipation measures for components with different heat generation characteristics on the PCB. This leads to uneven heat distribution, some high-heat generating components may not get enough heat dissipation, and the heat dissipation resources in the low-heat generating component area may be wasted. Summary of the invention

[0004] The main purpose 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 heating elements.

[0005] A first aspect of the present invention provides a process for preparing a high thermal conductivity composite substrate, the process for preparing the high thermal conductivity composite substrate comprising: 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; 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.

[0006] Optionally, the branches are made of styrene-butadiene-styrene (SBS) thermoplastic elastomer.

[0007] Optionally, fixing the pre-prepared skeleton on the insulating base layer of the printed circuit board includes: 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 to the insulating base layer by adjusting the temperature of the adhesive and the pressure applied to the frame.

[0008] Optionally, the adhesive having temperature responsive characteristics is an epoxy resin-based thermosetting adhesive, and the frame is fixed to 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.

[0009] Optionally, after 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 the predetermined electronic components, the method further comprises: Identify at least one partitioning branch located between the high heat dissipation space and the low heat dissipation space among the plurality of branches; A heat insulation groove is provided on a surface of the dividing branch away from the insulating base layer, wherein the heat insulation groove extends along a length direction of the dividing branch.

[0010] Optionally, 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 positions of the partitioning branches; The plurality of positioning holes are connected to form the heat insulation groove.

[0011] Optionally, a plurality of positioning holes penetrating the thickness direction of the partitioning branches are formed at the predetermined heat insulation groove positions of the partitioning branches, including: forming a plurality of surface activation areas at the predetermined heat insulation groove positions; applying a photosensitive swelling agent onto the surface activated area; The area to which the photosensitive swelling agent is applied is selectively illuminated to induce controllable swelling of the SBS material in the illuminated area; The swollen area is dissolved to form the plurality of positioning holes.

[0012] Optionally, 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.

[0013] Optionally, injecting a first thermally conductive filler into the high heat dissipation space and performing a curing process includes: 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.

[0014] Optionally, the functional layer for fixing a printed circuit board on the surface of the heat-conducting layer includes: 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.

[0015] The preparation process of the high thermal conductivity composite substrate proposed in the present invention adopts a skeleton structure composed of multiple interconnected branches, which 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 differentiated thermal management of components with different heating characteristics. This design overcomes the limitation of uniform thermal conductivity of the traditional integral metal layer, and can meet the heat dissipation requirements of different regions in a targeted manner. The present invention uses fillers with different thermal conductivities to be injected into high and low heat dissipation spaces respectively and cured, which further enhances the accuracy and efficiency of thermal management. Fillers with high thermal conductivity are used in high heat dissipation spaces to ensure that high heat dissipation components obtain sufficient heat dissipation; while fillers with low thermal conductivity are used in low heat dissipation spaces to provide appropriate heat dissipation capacity for low heat dissipation components. This differentiated filler strategy enables high heat dissipation areas to dissipate heat quickly, prevents the formation of hot spots, and avoids excessive heat dissipation of low heat dissipation areas. In this way, the present invention achieves 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 heating characteristics, ensuring the reliable operation of high-heat components and avoiding overcooling of low-heat components. It optimizes resource utilization while ensuring PCB performance, providing important support for the development of high-performance and high-reliability electronic equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0017] Figure 1 A schematic diagram of an embodiment of a preparation process of a high thermal conductivity composite substrate in an embodiment of the present invention; Figure 2 FIG. 1 is a schematic structural diagram of an embodiment of a high thermal conductivity composite substrate in an embodiment of the present invention.

[0018] Description of Figure Numbers: 1. Insulation base layer; 2. Skeleton; 21. Branches; 211. Insulation groove; 212. High heat dissipation space; 213. Low heat dissipation space; 3. Functional layer; 4. High heat generation electronic components; 5. Low heat generation electronic components.

[0019] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0020] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0021] It should be noted that if the embodiments of the present invention involve directional indications (such as up, down, left, right, front, back...), the directional indications are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0022] In addition, the descriptions of "first", "second", etc. in the present invention are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, "and / or" in the full text includes three solutions. Taking A and / or B as an example, it includes technical solution A, technical solution B, and technical solution that satisfies both A and B. In addition, the technical solutions between the various embodiments can be combined with each other, which must be based on the ability of ordinary technicians in the field to implement. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0023] An embodiment of the present application provides a process for preparing a high thermal conductivity composite substrate. Figure 1 A flow chart of a process for preparing a high thermal conductivity composite substrate provided in one embodiment of the present application. To facilitate understanding of the structure of the present application, please refer to Figure 2 A simplified schematic diagram of a high thermal conductivity composite substrate is shown, in which the branches are arranged in parallel, and the structure where the branches are blocked by the functional layer can be connected to each other through some laterally extending branches to achieve a finer division of space. In other embodiments, the branches can also be arranged in other arrangements, such as unregulated arrangements, which are not specifically limited here. In this embodiment, the method includes: See also Figure 1 , fixing a pre-prepared skeleton 2 on the insulating base layer 1 of the printed circuit board, wherein 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; In one embodiment of the present invention, the branches 21 are made of styrene-butadiene-styrene (SBS) thermoplastic elastomer.

[0024] Specifically, SBS materials have excellent flexibility and elasticity, which enables the skeleton 2 structure made of it to adapt to various stresses and deformations during the manufacture and use of PCBs, reducing the risk of structural damage caused by thermal expansion or mechanical stress. Secondly, SBS materials have good heat resistance and can maintain stable physical and mechanical properties within the operating temperature range of electronic equipment, which is crucial to maintaining the long-term effectiveness of the heat dissipation structure. In addition, SBS materials have good compatibility with epoxy resin-based composite materials, which is conducive to the formation of a strong interface bond between the skeleton 2 and the thermally conductive filler, improving the stability of the overall structure and the heat dissipation efficiency. SBS materials also have a low thermal conductivity, which allows them to form a certain thermal resistance between high and low heat dissipation areas, which helps to achieve more precise heat control and distribution. Finally, SBS materials have excellent processing performance and can accurately manufacture complex skeleton 2 structures through methods such as injection molding or 3D printing, which provides technical possibilities for achieving differentiated heat dissipation design.

[0025] In one embodiment of the present invention, the method of fixing a pre-prepared skeleton 2 on the insulating base layer 1 of a printed circuit board comprises: selectively performing surface modification treatment on the surface of the insulating base layer 1 according to the structural pattern of the branches 21 of the skeleton 2, so that the surface energy of the predetermined contact area with the branches 21 of the skeleton 2 on the surface of the insulating base layer 1 is higher than that of other areas; selectively applying an adhesive with temperature response characteristics to 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.

[0026] Specifically, according to the pre-designed structural pattern of the skeleton 2 branches 21, the surface of the insulating base layer 1 is selectively 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 skeleton 2 branches 21. The mask is covered on the surface of the insulating base layer 1 and then placed in a plasma treatment chamber. By controlling the power of the plasma (usually 50-200W) and the treatment time (generally 30-120 seconds), only the area at the opening of the mask is treated, thereby achieving selective surface modification. This treatment will increase the roughness and polar groups of the surface, significantly increase the surface energy, and provide a good foundation for the subsequent adhesion of the adhesive. Next, a dispensing device is used to apply an adhesive with temperature-responsive characteristics to the predetermined contact area that has been surface-modified. This device has an XYZ-axis control system and a micro-dispensing valve (the device belongs to the prior art, and the present application scheme has not improved this device), which can accurately control the application position and amount of the adhesive. For example, the dispensing pressure can be set to 0.1-0.5MPa and the dispensing time can be set to 0.1-0.5 seconds to ensure that the amount of adhesive on each predetermined contact point is uniform and appropriate. The selected adhesive has a low viscosity (such as 500-1000cps) at room temperature and cures quickly after heating. This property provides an operating time window for the subsequent positioning and fixing of the skeleton 2.

[0027] Subsequently, the pre-prepared SBS skeleton 2 is placed on the insulating base layer 1 using a mechanical positioning system. This system includes a visual alignment module and a precision robotic arm that can achieve a positioning accuracy of ±10μm. 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 accurately correspond to the predetermined contact area.

[0028] Finally, the entire assembly is placed in a precision temperature-controlled press for curing. The equipment is able to precisely control temperature (accuracy ±1°C) and pressure (accuracy ±0.01MPa). Through multi-step temperature and pressure control, high-quality bonding between the skeleton 2 and the base layer is achieved. This fine process control not only ensures a strong 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, and laying a solid foundation for subsequent differentiated thermal conductive filling.

[0029] In one embodiment of the present invention, the adhesive having temperature responsive characteristics is an epoxy resin-based thermosetting adhesive, and the frame 2 is fixed to the insulating base layer 1 by adjusting the temperature of the adhesive and the pressure applied to the frame 2, including: setting the temperature in the range of 35-45°C, applying a pressure of 0.03-0.07MPa to the frame 2, and maintaining it for 10-15 minutes; raising the temperature to the range of 55-65°C at a heating rate of 2-5°C / min, and increasing the pressure to 0 .08-0.12MPa, hold for 20-30 minutes; reduce the temperature to within the range of 45-55℃, reduce the pressure to 0.03-0.07MPa, hold for 20-40 seconds; increase the temperature to within the range of 75-85℃ at a heating rate of 2-5℃ / min, increase the pressure to 0.18-0.22MPa, hold for 50-70 minutes; reduce the temperature to room temperature at a cooling rate of 1-2℃ / min, and reduce the pressure to 0MPa at a rate of 0.01-0.03MPa / min.

[0030] Specifically, the temperature is set in the range of 35-45°C, and a pressure of 0.03-0.07MPa is applied to the skeleton 2 for 10-15 minutes. The purpose of this stage is to spread the adhesive evenly while allowing the skeleton 2 to make slight position adjustments. For example, a hot press with a temperature control system can be used, with a temperature accuracy of ±0.5°C and a pressure accuracy of ±0.01MPa. Next, the temperature is increased to a range of 55-65°C at a heating rate of 2-5°C / min, and the pressure is increased to 0.08-0.12MPa for 20-30 minutes. At 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 a range of 45-55°C, and the pressure is reduced to 0.03-0.07MPa for 20-40 seconds. This short cooling and decompression stage can release some internal stress and improve the stability of the final structure. Next, the temperature is raised again to a range of 75-85°C at a heating rate of 2-5°C / min, and the pressure is increased to 0.18-0.22MPa for 50-70 minutes. This is the critical stage for the complete curing of the adhesive. The high temperature and high pressure ensure the full cross-linking reaction and form a strong bonding interface. Finally, the temperature is lowered to room temperature at a cooling rate of 1-2°C / min, while the pressure is reduced to 0MPa at a rate of 0.01-0.03MPa / min. This slow cooling and decompression process can minimize the generation of thermal stress and ensure the integrity of the structure. The entire process can be achieved through programmed hot pressing 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 curve. This multi-step, finely controlled curing process not only ensures the full curing and excellent bonding strength of the adhesive, but also effectively reduces the generation of internal stress, significantly improving the reliability and durability of the entire structure.

[0031] Please continue reading Figure 1 , 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 predetermined electronic components; Specifically, it is necessary to obtain detailed information of all electronic components on the PCB, including their location, size and expected power consumption. This can be achieved through the export function of the PCB design software, such as using the BOM (Bill of Materials) export function of Altium Designer to obtain the location coordinates and power consumption data of the components. Then, a virtual model of the PCB is created using thermal simulation software, such as ANSYS Icepak, and thermal analysis is performed based on the power consumption data of the components. The PCB surface is divided into different thermal zones by setting thresholds (such as defining areas with power consumption greater than 2W as high heat dissipation zones). Next, these thermal zone information is superimposed on the grid of the skeleton 2 structure to determine which type of heat dissipation each space surrounded by the branches 21 of the skeleton 2 belongs to. For example, if more than 50% of the area in a space belongs to the high heat dissipation zone, the space is defined as a high heat dissipation space 212. Finally, a heat dissipation space distribution map is generated to guide the subsequent thermal conductive filler injection process.

[0032] In one embodiment of the present invention, after dividing the multiple 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 heating characteristics of predetermined electronic components, the method further includes: identifying at least one partitioning branch 21 located between the high heat dissipation space 212 and the low heat dissipation space 213 among the multiple branches 21; and providing a heat insulation groove 211 on the surface of the partitioning branch 21 away from the insulating base layer 1, wherein the heat insulation groove 211 extends along the length direction of the partitioning branch 21.

[0033] Specifically, the setting of the heat insulation groove 211 can effectively reduce the heat transfer from the high heat generating heat source to the low heat generating 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.

[0034] Specifically, based on the embodiment in which the branch 21 is made of styrene-butadiene-styrene (SBS) thermoplastic elastomer, the heat insulation groove 211 is set on the surface of the separating branch 21 away from the insulating base layer 1, comprising: obtaining a predetermined heat insulation groove 211 position on the surface of the separating branch 21 away from the insulating base layer 1; forming a plurality of positioning holes that penetrate the separating branch 21 in the thickness direction at the predetermined heat insulation groove 211 position of the separating branch 21; and connecting the plurality of positioning holes to form the heat insulation groove 211.

[0035] Specifically, in the process of realizing the separation of high and low heat dissipation spaces 213 and the setting of the heat insulation groove 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 boundaries of the high and low heat dissipation spaces 213, and compare them with the structure diagram of the skeleton 2 to determine the position of the separation branch 21. For example, if it is detected that one side of a branch 21 is a high heat dissipation space 212 and the other side is a low heat dissipation space 213, then the branch 21 is identified as a separation branch 21.

[0036] After determining the partitioning branch 21, the next step is to set the heat insulation groove 211 on its surface away from the insulating base layer 1. This process first requires obtaining the predetermined heat insulation groove 211 position on the surface of the partitioning branch 21 away from the insulating 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 partitioning branch 21. This position can be selected on the center line of the branch 21 to ensure the best insulation effect.

[0037] Next, a plurality of positioning holes penetrating the thickness direction of the partition branches 21 are formed at the predetermined position of the heat insulation groove 211. This step can be completed using a laser drilling device. For example, a pulsed Nd:YAG laser can be used, with a wavelength of 1064nm, a pulse width of 10ns, and a single pulse energy of 0.1mJ. By controlling the focal position and pulse number 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 aperture to ensure the smooth progress of the subsequent connection process.

[0038] After forming the positioning holes, the last step is to connect these positioning holes to form a complete thermal insulation groove 211. This process can be achieved using selective laser ablation technology. Using a CO2 laser with a wavelength of 10.6μm and a power setting between 10-20W, the material between the positioning holes is gradually removed by controlling the scanning path of the laser. The laser scanning speed is usually set at 10-20mm / s to ensure that the material is fully removed without excessively damaging the surrounding structure.

[0039] By forming the positioning holes first and then connecting them, the position 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. Furthermore, by controlling the size and spacing of the positioning holes, the width and depth of the heat insulation groove 211 can be flexibly adjusted to optimize the heat insulation effect. Finally, this method also allows some tiny connecting bridges to be retained when necessary, which will not completely cut off the structural continuity of the branches 21 while providing sufficient heat insulation effect, which is conducive to maintaining the mechanical strength of the overall skeleton 2.

[0040] In one embodiment of the present invention, a plurality of positioning holes penetrating the thickness direction of the partitioning branch 21 are formed at the predetermined insulation groove 211 of the partitioning branch 21, including: forming a plurality of surface activation areas at the predetermined insulation groove 211; 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; and dissolving the swollen area to form the plurality of positioning holes.

[0041] Specifically, in the process of forming the insulation groove 211, it is first necessary to form multiple surface activation areas at the predetermined insulation groove 211 position. This step can be completed by plasma treatment technology. Specifically, oxygen plasma treatment equipment can be used to treat the surface of the SBS material at a power of 50-100W in a low-pressure environment of 5-20Pa. The treatment time is controlled at 30-60 seconds, so that the polar groups on the surface can be increased without excessively damaging the material, thereby improving the adhesion ability of the subsequent photosensitive swelling agent. In order to achieve precise local treatment, a laser-cut microporous mask can be used, and the openings on the mask accurately correspond to the predetermined insulation groove 211 position.

[0042] After the surface activation is completed, the next step is to apply a photosensitive swelling agent to the activated area. The photosensitive swelling agent selected here is an organic compound that is sensitive to ultraviolet light, such as a polymer containing an azobenzene group. This swelling agent will undergo a change in molecular configuration after being exposed to light of a specific wavelength, resulting in an increase in volume. The application process can use micro-dispensing technology, using dispensing equipment such as a microliter-level piezoelectric dispensing valve to accurately apply the swelling agent to the activated area.

[0043] Next, the area where the photosensitive swelling agent was applied is selectively illuminated to induce controllable swelling of the SBS material in the illuminated area. This step is accomplished using a UV laser equipped with an optical system. For example, a UV LED light source with a wavelength of 365nm can be selected, and the spot can be reduced to a diameter of 100-200 microns through an optical focusing system. The light intensity is controlled at 50-100mW / cm², and the irradiation time is 10-30 seconds. This type of illumination can not only activate the swelling agent, but also control the degree of swelling, thereby achieving controllable swelling of the SBS material.

[0044] 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 already swollen SBS material while having little effect on the unswollen area. For example, tetrahydrofuran (THF) is used as a solvent, and the solvent is precisely applied to the swollen area by micro-injection technology. The amount and action time of the solvent need to be precisely controlled. Usually a pulsed micro-injection valve is used to spray 1-3 drops of solvent per swollen area, and the volume of each drop is about 10-20 nanoliters. After the dissolution process lasts for 20-40 seconds, an inert gas such as nitrogen is used to purge to remove the dissolved product and residual solvent, and finally form the desired positioning holes.

[0045] After the positioning holes are formed, the process of connecting these holes to form the heat insulation groove 211 can be achieved by a variety of methods. A commonly used method is to use precision laser cutting technology, such as using a femtosecond laser to remove material between the positioning holes in a pulsed manner. Another method is to use chemical etching technology to accurately apply a specific etchant to the area between the positioning holes and control the etching time to form the desired groove. It is also possible to consider using a micro milling cutter for mechanical processing, and using a precisely controlled micro CNC device to remove the material between the positioning holes to form a continuous heat insulation groove 211. This application does not impose specific restrictions on this part of the content.

[0046] Please continue reading Figure 1 , injecting a first thermally conductive filler into the high heat dissipation space 212 and performing a curing treatment, injecting a second thermally conductive filler into the low heat dissipation space 213 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 2 to form a thermally conductive layer; In one embodiment of the present invention, the material of the first thermal 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 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; and 1-2 parts by weight of 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.

[0047] 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, wherein a higher proportion of carbon nanotubes (15-25 parts by weight) in the first thermally conductive filler ensures the excellent thermal conductivity of the high heat dissipation space 212. Aluminum nitride powder, as an auxiliary thermally conductive filler, further enhances the thermal conductivity while helping to reduce the thermal expansion coefficient. The use of a coupling agent improves the interface bonding between the filler and the epoxy resin matrix and improves the overall performance of the composite material. The combination of bisphenol A epoxy resin and anhydride curing agent provides excellent thermal stability and mechanical properties, while the selection of a silane coupling agent further enhances the compatibility of the filler with the matrix. This formulation achieves differentiated thermal conductivity of high and low heat dissipation spaces 213 and ensures the structural integrity and long-term stability of the entire thermal conductive layer.

[0048] In one embodiment of the present invention, the first thermally conductive filler is injected into the high heat dissipation space 212 and cured, comprising: setting a detachable cofferdam structure at the periphery of the insulating base layer 1, wherein the height of the cofferdam structure is not less than the height of the branch 21; applying a negative pressure environment with a vacuum degree of not less than -0.09MPa to the high heat dissipation space 212; while maintaining the negative pressure, filling the high heat dissipation space 212 with the first thermally conductive filler that has been degassed in advance at an injection rate of not more than 2mL / s until the filling height reaches 99%-100% of the height of the branch 21; after completing the filling of the first thermally conductive filler, maintaining the negative pressure for 5-10 minutes; while maintaining the negative pressure, raising the temperature Raise the temperature to 90%-95% of the gel point temperature of the first thermally conductive filler, maintain for 10-15 minutes, so that the filler forms a semi-gel state; raise the temperature to the curing starting temperature of the first thermally conductive filler, maintain for 20-30 minutes, so that the filler as a whole forms a preliminary cross-linked network structure; after reducing the temperature to room temperature, remove the removable cofferdam structure; apply a layer of thermal conductive interface material with a thickness of 10-20μm on the surface of the first thermally conductive filler and the surface of the branches 21 of the skeleton 2; post-cure the entire surface, and maintain it for 60-90 minutes at a temperature of 95%-100% of the peak curing temperature of the first thermally conductive filler to ensure that the thermally conductive filler and the thermally conductive interface material are completely cured and cross-linked.

[0049] Specifically, a detachable cofferdam structure is provided at the periphery of the insulating base layer 1, and the height of the cofferdam structure is not less than the height of the branches 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 molded by a mold to ensure that it fits tightly with the insulating base layer 1. Next, a negative pressure environment of not less than -0.09MPa is applied to the high heat dissipation space 212, which can be achieved by connecting a vacuum pump and using a sealing cover to cover the entire working area. The creation of a negative pressure environment helps to remove air in the space and reduce bubbles that may be generated in the filler.

[0050] Under negative pressure, the first thermally conductive filler that has been previously degassed is filled at an injection rate of no more than 2 mL / s. This process is completed using an injection device, such as an injection system with servo motor control, which can 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 while ensuring the adequacy of the filling.

[0051] After the first thermally conductive filler is filled, the negative pressure is maintained for 5-10 minutes. The purpose of this step is to allow the filler to fully penetrate into every corner of the skeleton 2 structure and further remove any remaining tiny bubbles. Subsequently, while maintaining the negative pressure, the temperature is raised to 90%-95% of the gel point temperature of the first thermally conductive filler and maintained for 10-15 minutes. This step can be completed using a temperature control system, such as using a Peltier element or an infrared heating device, in conjunction with a temperature sensor, to achieve a temperature control accuracy of ±1°C. The purpose of this stage is to allow the filler to form a semi-gel state in preparation for the subsequent cross-linking reaction.

[0052] Next, the temperature is raised to the curing starting temperature of the first thermally conductive filler and maintained for 20-30 minutes to allow the filler to form a preliminary cross-linked network structure. This process is achieved through a programmed temperature control system, such as using a PID control algorithm to ensure a smooth and accurate temperature curve. The formation of a preliminary cross-linked network helps the filler maintain its shape and prevents it from flowing during subsequent operations.

[0053] After the temperature drops to room temperature, remove the removable cofferdam structure. A thin and tough 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.

[0054] A layer of thermal conductive interface material with a thickness of 10-20 μm is applied on the surface of the first thermal conductive filler and the surface of the branches 21 of the skeleton 2. This is done by coating equipment, such as using an automated spraying system or screen printing equipment to ensure uniform coating thickness. The application of thermal conductive interface material can fill in tiny surface unevenness and improve heat conduction efficiency.

[0055] Finally, the entire surface is post-cured at 95%-100% of the peak curing temperature of the first thermally conductive filler for 60-90 minutes. This process can be performed in an industrial-grade oven with precise temperature control and uniform heat distribution. The post-curing process ensures that the thermally conductive filler and thermally conductive interface material are fully cured and cross-linked, maximizing their thermal and mechanical properties.

[0056] The process of injecting the second thermally conductive filler into the low heat dissipation space 213 and performing the curing treatment is similar to the process of the high heat dissipation space 212, but it is necessary to adjust the injection rate and curing parameters to adapt to the characteristics of the second thermally conductive filler. For example, since the content of carbon nanotubes in the second thermally conductive filler is low, its viscosity may be low, so the injection rate can be appropriately increased, but it still needs to be kept below 2mL / s. The curing temperature and time also need to be adjusted according to the characteristics of the second thermally conductive filler, and a slightly lower temperature and a shorter curing time can usually be used.

[0057] It is noteworthy that the thermal conductivity of the first thermally conductive filler is greater than that of the second thermally conductive filler, which is achieved by adjusting the ratio of carbon nanotubes and aluminum nitride powder in the two fillers. The higher ratio of thermally conductive fillers in the high heat dissipation space 212 ensures effective heat dissipation of high heat generating components, while the lower thermal conductivity in the low heat dissipation space 213 avoids excessive heat dissipation and achieves overall thermal balance. The thermally conductive layer formed by the combination of the two thermally conductive fillers and 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.

[0058] Please continue reading Figure 1 A functional layer 3 of a printed circuit board is fixed on the surface of the heat-conducting layer, and an area on the functional layer 3 corresponding to the high heat dissipation space 212 is used to install high-heat-generating electronic components 4, and an area corresponding to the low heat dissipation space 213 is used to install low-heat-generating electronic components 5.

[0059] In one embodiment of the present invention, the functional layer 3 of the printed circuit board is fixed on the surface of the thermal conductive layer, comprising: preparing a functional layer 3 material, wherein the functional layer 3 material is an epoxy resin prepreg; performing plasma treatment on the surface of the thermal conductive layer; forming a preset microstructure pattern on the surface of the thermal conductive layer after the treatment; placing the functional layer 3 material on the surface of the thermal conductive layer having the microstructure pattern; performing vacuum-assisted lamination on the functional layer 3 material at a temperature of 120-150°C and a pressure of 0.5-1.5MPa; and performing annealing treatment on the laminated structure at 80-100°C for 2-4 hours.

[0060] Specifically, it is necessary to prepare the material for the functional layer 3 first, and epoxy resin prepreg is selected as the main material. Epoxy resin 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 is its excellent electrical insulation, mechanical strength and processing performance, which is suitable as a substrate for printed circuit boards. In the preparation stage, the prepreg needs to be cut into a shape that matches the size of the thermal conductive layer and stored in a constant temperature and humidity environment to ensure the stability of the material performance.

[0061] Next, the surface of the thermal conductive layer is subjected to plasma treatment. The purpose of this step is to increase the surface energy and improve the bonding strength between the functional layer 3 and the thermal conductive layer. Plasma treatment can be performed using low-temperature plasma treatment equipment, for example, using oxygen as the working gas and treating at a power of 50-100W for 30-60 seconds. During the treatment process, the plasma will generate a large number of active groups on the surface of the thermal conductive layer. These groups can form chemical bonds with the functional layer 3 material, significantly enhancing the interface bonding strength.

[0062] After plasma treatment, the next step is to form a preset microstructure pattern on the surface of the thermal conductive layer. This step is achieved by micro-nanoimprinting technology. In specific operations, it is first necessary to make a mold with a microstructure, which can be made using electron beam lithography or nanoimprint lithography. Then, the mold is imprinted onto the surface of the thermal conductive layer, and kept at a certain temperature (usually 10-20°C above the glass transition temperature of the mold material) and pressure (0.1-1MPa) for a few minutes to form a microstructure pattern opposite to the mold on the surface of the thermal conductive layer. These microstructures can not only increase the interface bonding area, but also provide a mechanical interlocking effect, further enhancing the bonding strength between the functional layer 3 and the thermal conductive layer.

[0063] After the microstructure is formed, the functional layer 3 material (epoxy prepreg) is placed on the surface of the thermal conductive layer with the microstructure pattern. This step requires careful operation to ensure that the prepreg fits tightly to the surface of the thermal conductive layer without bubbles or wrinkles. A vacuum-assisted positioning system can be used to slowly lay the prepreg on the surface of the thermal conductive layer under a slight negative pressure to ensure a perfect fit.

[0064] Subsequently, the functional layer 3 material is vacuum-assisted laminated at a temperature of 120-150°C and a pressure of 0.5-1.5MPa. This process can be completed in a professional vacuum laminator. First, the entire structure is placed in the vacuum chamber of the laminator and evacuated to below 0.1Pa to remove any bubbles that may exist between the materials. Then, lamination is performed according to a preset temperature and pressure curve. The choice of temperature is based on the curing characteristics of the epoxy resin, usually 20-30°C above its gel point, while the choice of pressure requires a balance between 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 and avoid the generation of bubbles, thereby obtaining high-quality lamination results.

[0065] 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 lamination and improve the dimensional stability and mechanical properties of the material. The annealing temperature is selected to be lower than the glass transition temperature of the epoxy resin, but sufficient to allow the molecular chain to obtain a certain degree of mobility, thereby achieving stress release. The selection of annealing time requires a balance between the adequacy of stress release and production efficiency.

[0066] It is not difficult to understand that through plasma treatment and the formation of microstructure patterns, the interfacial bonding strength between the functional layer 3 and the thermal conductive layer is significantly enhanced, and the reliability of the entire structure is improved. Secondly, the vacuum-assisted lamination technology ensures close contact between the materials and reduces the generation of bubbles and defects. Finally, the annealing treatment further optimizes the performance of the material and improves the long-term stability of the entire structure. This fine 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 equipment.

[0067] It should be noted that in the present application, the distinction between high-heat-generating electronic components 4 and low-heat-generating electronic components 5 is based on the heat generated during operation. High-heat-generating electronic components 4 generally refer to components that generate a large amount of heat during operation, such as high-performance processors, power amplifiers, or high-power LEDs. These components often require more efficient heat dissipation measures to maintain normal operating temperatures. Low-heat-generating electronic components 5 are components that generate relatively less heat during operation, such as memory chips, low-power microcontrollers, etc.

[0068] The above description is only a preferred embodiment of the present invention, and does not limit the patent scope of the present invention. All equivalent structural changes made by using the contents of the present invention specification and drawings under the inventive concept of the present invention, or directly / indirectly applied in other related technical fields are included in 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; 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 branches are made of styrene-butadiene-styrene (SBS) thermoplastic elastomer.

3. The process for preparing a high thermal conductivity composite substrate according to claim 2, 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 to the insulating base layer by adjusting the temperature of the adhesive and the pressure applied to the frame.

4. The process for preparing a high thermal conductivity composite substrate according to claim 3, 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 within the range of 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.

5. The process for preparing a high thermal conductivity composite substrate according to claim 1, characterized in that: After 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 the predetermined electronic components, the method further comprises: Identify at least one partitioning branch located between the high heat dissipation space and the low heat dissipation space among the plurality of branches; A heat insulation groove is provided on a surface of the dividing branch away from the insulating base layer, wherein the heat insulation groove extends along a length direction of the dividing branch.

6. The process for preparing a high thermal conductivity composite substrate according to claim 5, characterized in that: 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 positions of the partitioning branches; The plurality of positioning holes are connected to form the heat insulation groove.

7. The process for preparing a high thermal conductivity composite substrate according to claim 6, characterized in that: A plurality of positioning holes penetrating the thickness direction of the partitioning branches are formed at the predetermined heat insulation groove positions of the partitioning branches, including: forming a plurality of surface activation areas at the predetermined heat insulation groove positions; applying a photosensitive swelling agent onto the surface activated area; The area to which the photosensitive swelling agent is applied is selectively illuminated to induce controllable swelling of the SBS material in the illuminated area; The swollen area is dissolved to form the plurality of positioning holes.

8. 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.

9. The process for preparing a high thermal conductivity composite substrate according to claim 8, 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.

10. 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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