Silicon powder-boron nitride composite material, preparation method and application thereof

Abstract

The application relates to a silicon micro powder-boron nitride composite material and a preparation method and application thereof, and the preparation method comprises the following steps: mixing silicon micro powder, a silane coupling agent and an organic solvent and heating, so that the surface of the silicon micro powder is grafted with amino groups, thereby obtaining a seed solution; mixing the seed solution, an emulsifier and a solvent, thereby obtaining a seed emulsion; mixing a boron-containing compound, a nitrogen-containing compound and an organic solvent, thereby obtaining a precursor solution; and mixing the seed emulsion and the precursor solution and heating, so that the surface of the silicon micro powder is coated with boron nitride, thereby obtaining the silicon micro powder-boron nitride composite material. The preparation method realizes the regulation of the structure and performance of the silicon micro powder-boron nitride composite material and is beneficial to improving the consistency of the prepared silicon micro powder-boron nitride composite material. The operation process of the preparation method is relatively simple, the cost is controllable, and the preparation method has a good industrial production prospect.

Description

Silica micropowder-boron nitride composite materials, their preparation methods, and applications Technical Field

[0001] This application relates to the field of materials preparation, and in particular to a silicon micropowder-boron nitride composite material, its preparation method, and its application. Background Technology

[0002] Traditional copper-clad laminates (CCLs) have poor insulation properties when facing high-frequency, high-speed signal transmission, leading to significant signal loss during transmission and affecting communication quality and data transmission speed. Furthermore, as the power of electronic devices increases, the heat generated also increases. Traditional CCLs lack thermal stability and are prone to warping and delamination when temperatures change, affecting the long-term use of electronic devices. Summary of the Invention

[0003] In view of this, this application provides a silicon micropowder-boron nitride composite material, its preparation method, and its application, thereby solving at least one of the above-mentioned technical problems.

[0004] To achieve the above objectives, in a first aspect, this application provides a method for preparing a silicon micropowder-boron nitride composite material. The method includes: mixing silicon micropowder, a silane coupling agent, and an organic solvent and heating to graft amino groups onto the surface of the silicon micropowder to obtain a seed liquid; mixing the seed liquid, an emulsifier, and a solvent to obtain a seed emulsion; mixing a boron-containing compound, a nitrogen-containing compound, and an organic solvent to obtain a precursor solution; and mixing the seed emulsion and the precursor solution and heating to coat the surface of the silicon micropowder with boron nitride, thereby obtaining the silicon micropowder-boron nitride composite material.

[0005] Based on the first aspect, in some possible implementations, the boron-containing compound includes one or more of boric acid, boron chloride, and sodium borate tetradecylhydrate, and the nitrogen-containing compound includes one or more of urea, melamine, hexamethylenetetramine, ethylenediamine, and ammonia.

[0006] Based on the first aspect, in some possible implementations, the pH of the precursor solution is between 8 and 10.

[0007] Based on the first aspect, in some possible implementations, after heating the seed emulsion and precursor solution, the above preparation method further includes: washing, drying and annealing the heated product.

[0008] Based on the first aspect, in some possible implementations, the emulsifier includes one or more of sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, sodium dodecyl sulfonate, and hexadecyltrimethylammonium bromide.

[0009] Based on the first aspect, in some possible implementations, the mass ratio of silane coupling agent to silicon micropowder is 2% to 10%.

[0010] Based on the first aspect, in some possible implementations, the mass ratio of emulsifier to silica powder is 0.5% to 2.5%.

[0011] Based on the first aspect, in some possible implementations, the mass ratio of boron-containing compounds to nitrogen-containing compounds is 40% to 60%.

[0012] Based on the first aspect, in some possible implementations, the mass ratio of boron-containing compound to silicon micropowder is 12.5% ​​to 37.4%.

[0013] Based on the first aspect, in some possible implementations, the temperature after heating is between 90 ℃ and 140 ℃.

[0014] Secondly, this application provides a silicon micropowder-boron nitride composite material, which is prepared by the above-described preparation method. The silicon micropowder-boron nitride composite material includes a core and a coating disposed on at least a portion of the surface of the core. The core includes silicon micropowder, and the coating includes boron nitride.

[0015] Based on the second aspect, in some possible implementations, the mass ratio of boron nitride to silicon micropowder is 5% to 15%.

[0016] Based on the second aspect, in some possible implementations, boron nitride includes hexagonal boron nitride.

[0017] Thirdly, this application provides a copper-clad laminate, comprising a copper foil layer and a dielectric layer stacked together, wherein the dielectric layer comprises the aforementioned silicon micropowder-boron nitride composite material.

[0018] The preparation method of this application involves compounding silicon micropowder with boron nitride to obtain a silicon micropowder-boron nitride composite material with a specific structure. This composite material combines the advantages of silicon micropowder, such as its low coefficient of thermal expansion and insulation, with boron nitride, such as its high thermal conductivity and low dielectric constant. It also allows for more comprehensive optimization of the complementary properties of the two materials. Specifically, grafting amino groups onto the surface of the silicon micropowder enhances the bonding force between the core silicon micropowder and the encapsulated boron nitride, resulting in a more stable silicon micropowder-boron nitride composite material structure. When applied to copper-clad laminates (CCLs), the obtained silicon micropowder-boron nitride composite material improves the insulation performance of CCLs, reduces signal transmission loss, meets the requirements of high-frequency and high-speed communication, and also improves thermal conductivity, enhances thermal stability, reduces the coefficient of thermal expansion, minimizes warping and delamination, and strengthens the mechanical strength and resistance to deformation of the CCL. Furthermore, the obtained silicon micropowder-boron nitride composite material exhibits good adhesion to the CCL resin matrix, which helps improve the compatibility of the interface between the CCL filler and the resin matrix, thereby further enhancing the overall performance of the CCL. Attached Figure Description

[0019] Figure 1 is a schematic flowchart of a method for preparing a silicon micropowder-boron nitride composite material according to an embodiment of this application. Detailed Implementation

[0020] The embodiments of this application are described in detail below. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application; it should be noted that, unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs; where there is no conflict, the implementation methods and features of the implementation methods of this application can be combined with each other; many specific details are set forth in the following description to provide a full understanding of this application, and the described implementation methods are only a part of the implementation methods of this application, and not all of the implementation methods.

[0021] To address existing problems in copper-clad laminates (CCLs), filling them with high-performance ceramic materials has become an important research direction. Silica powder is widely used as a filler material in CCLs due to its excellent insulation, low coefficient of thermal expansion, and low cost. However, the effectiveness of silica powder alone in improving the thermal conductivity and mechanical properties of CCLs remains to be enhanced. Boron nitride, on the other hand, possesses excellent properties such as high thermal conductivity, good chemical stability, and a low dielectric constant. Theoretically, combining boron nitride with silica powder could create a complementary advantage, thereby improving the overall performance of CCLs.

[0022] However, the inventors of this application have discovered numerous problems with the existing methods for preparing composite materials for copper-clad laminates using silicon micropowder and boron nitride. For example, existing preparation processes lack control over the structure and composition ratio of the composite material, resulting in significant fluctuations in product performance and poor consistency. Moreover, the preparation process is complex and costly, hindering large-scale industrial production. Furthermore, the composite material prepared by existing methods exhibits poor interfacial compatibility when bonded to the resin matrix of the copper-clad laminate, failing to fully realize its reinforcing effect.

[0023] Based on this, one embodiment of this application provides a method for preparing a silicon micropowder-boron nitride composite material. Please refer to Figure 1. The preparation method includes:

[0024] Step 1: Mix silica powder, silane coupling agent and organic solvent and heat to graft amino groups onto the surface of silica powder to obtain seed liquid.

[0025] Amino groups grafted onto the surface of silicon micropowder can improve the interfacial affinity of silicon micropowder and enhance the bonding force between silicon micropowder and coatings.

[0026] In some embodiments, the temperature after heating is between 90°C and 140°C. For example, the temperature after heating can be 90°C, 100°C, 110°C, 120°C, 130°C, 140°C, or any value within the range of any two of the above values. Controlling the temperature within the above range is beneficial for the grafting of amino groups onto the surface of the silicon micropowder.

[0027] In some embodiments, the mass ratio of silane coupling agent to silicon powder is 2% to 10%. For example, the mass ratio of silane coupling agent to silicon powder can be 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, or any value within the range of any two of the above values. Controlling the ratio of silicon powder to silane coupling agent within the above range is beneficial for fully grafting amino groups onto the surface of the silicon powder, improving the subsequent bonding force with the coating, and thus improving the performance of the silicon powder-boron nitride composite material.

[0028] Step 2: Mix the seed liquid, emulsifier and solvent to obtain the seed emulsion.

[0029] Converting the above seed liquid into an emulsion system helps improve the dispersibility of the seed liquid components, which in turn facilitates the subsequent reaction with the coating material.

[0030] In some embodiments, the emulsifier includes one or more of sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, sodium dodecyl sulfonate, and hexadecyltrimethylammonium bromide. Selecting the above emulsifiers can convert the seed liquid into an emulsion system, thereby facilitating better subsequent reaction with the coating material and promoting the formation of the silica micropowder-boron nitride composite material of this application.

[0031] In some embodiments, the mass ratio of emulsifier to silicon powder is 0.5% to 2.5%. For example, the mass ratio of emulsifier to silicon powder can be 0.5%, 1%, 1.5%, 2%, 2.5%, or any value within the range of any two of the above values. Controlling the above mass ratio of emulsifier to silicon powder is beneficial to improving the consistency of the composition of the obtained silicon powder-boron nitride composite material, making the performance of the obtained silicon powder-boron nitride composite material more controllable, and thus better improving the overall performance of copper clad laminate.

[0032] Step 3: Mix boron-containing compounds, nitrogen-containing compounds, and organic solvents to obtain a precursor solution.

[0033] In some embodiments, the boron-containing compound includes one or more of boric acid, boron chloride, and sodium borate tetradecylhydrate, and the nitrogen-containing compound includes one or more of urea, melamine, hexamethylenetetramine, ethylenediamine, and ammonia.

[0034] In some embodiments, the mass ratio of the boron-containing compound to the nitrogen-containing compound is 40% to 60%. For example, the mass ratio of the boron-containing compound to the nitrogen-containing compound can be 40%, 43%, 45%, 48%, 50%, 52%, 55%, 57%, 60%, or any value within the range of any two of the above values. This is beneficial for controlling the content of reactive substances in the precursor solution and for promoting the formation of the silicon micropowder-boron nitride composite material of this application.

[0035] In some embodiments, the mass ratio of the boron-containing compound to the silicon micropowder is from 12.5% ​​to 37.4%. For example, the mass ratio of the boron-containing compound to the silicon micropowder can be 12.5%, 14.5%, 17.5%, 20.5%, 23.5%, 26.5%, 29.5%, 32.5%, 35.5%, 37.4%, or any value within the range of any two of the above values. This facilitates control over the boron nitride content coated on the surface of the silicon micropowder. A suitable amount of boron nitride coating helps to better combine the performance advantages of silicon micropowder and boron nitride, thereby improving the performance of the silicon micropowder-boron nitride composite material.

[0036] In some embodiments, the pH of the precursor solution is 8 to 10. The precursor solution with the preset pH exhibits good reactivity and promotes the reaction with the seed emulsion components under subsequent heating, thereby promoting the formation of the silica micropowder-boron nitride composite material of this application.

[0037] Step 4: Mix the seed emulsion and precursor solution and heat to coat the surface of the silica powder with boron nitride, thereby obtaining a silica powder-boron nitride composite material.

[0038] In some embodiments, the temperature after heating is between 90°C and 140°C. For example, the temperature after heating can be 90°C, 100°C, 110°C, 120°C, 130°C, 140°C, or any value within the range of any two of the above values. Within the above temperature range, it is beneficial for the precursor solution to form a boron nitride coating on the surface of the silicon micropowder.

[0039] In some embodiments, after heating the seed emulsion and precursor solution, the preparation method further includes washing, drying, and annealing the heated product. Washing removes unreacted substances, drying removes the washing liquid, and annealing helps reduce the internal stress of the silicon micropowder-boron nitride composite material, optimizes its structure, and improves its stability.

[0040] The preparation method of this application involves compounding silicon micropowder with boron nitride to obtain a silicon micropowder-boron nitride composite material with a specific structure. This composite material combines the advantages of silicon micropowder, such as its low coefficient of thermal expansion and insulation, with boron nitride, such as its high thermal conductivity and low dielectric constant. It also allows for more comprehensive optimization of the complementary properties of the two materials. Specifically, grafting amino groups onto the surface of the silicon micropowder enhances the bonding force between the core silicon micropowder and the encapsulated boron nitride, resulting in a more stable silicon micropowder-boron nitride composite material structure. When applied to copper-clad laminates (CCLs), the obtained silicon micropowder-boron nitride composite material improves the insulation performance of CCLs, reduces signal transmission loss, meets the requirements of high-frequency and high-speed communication, and also improves thermal conductivity, enhances thermal stability, reduces the coefficient of thermal expansion, minimizes warping and delamination, and strengthens the mechanical strength and resistance to deformation of the CCL. Furthermore, the obtained silicon micropowder-boron nitride composite material exhibits good adhesion to the CCL resin matrix, which helps improve the compatibility of the interface between the CCL filler and the resin matrix, thereby further enhancing the overall performance of the CCL.

[0041] Therefore, the preparation method of this application enables the control of the structure and properties of silicon micropowder-boron nitride composite materials, which is beneficial to improving the consistency of the prepared silicon micropowder-boron nitride composite materials. Furthermore, the preparation method of this application has a relatively simple operation process, controllable cost, and good prospects for industrial production, and is expected to bring economic benefits and technological innovation to the copper clad laminate industry.

[0042] An embodiment of this application also provides a silicon micropowder-boron nitride composite material, which is prepared by the above-described preparation method. The silicon micropowder-boron nitride composite material includes a core and a coating disposed on at least a portion of the surface of the core. The core includes silicon micropowder, and the coating includes boron nitride.

[0043] In the silicon micropowder-boron nitride composite material of this application, silicon micropowder and boron nitride form a specific structural relationship, which is beneficial to better combine the insulating properties of silicon micropowder with the high thermal conductivity and low dielectric constant of boron nitride. The composite structure of silicon micropowder and boron nitride through the predetermined structural relationship can more fully achieve the complementary optimization of the properties of the two materials. Specifically, the amino groups on the surface of the silicon micropowder enhance the bonding force between the core silicon micropowder and the encapsulated boron nitride, making the silicon micropowder-boron nitride composite material structure more stable. When applied to copper-clad laminates (CCLs), it helps improve the insulation performance of CCLs, reduce signal transmission loss, meet the requirements of high-frequency and high-speed communication, and also improves thermal conductivity, enhances thermal stability, reduces the coefficient of thermal expansion, reduces warping and delamination, and strengthens the mechanical strength and deformation resistance of CCLs. Furthermore, the silicon micropowder-boron nitride composite material of this application has good adhesion to the resin matrix of CCLs, which helps improve the compatibility of the interface between the filler and the resin matrix, thereby further improving the overall performance of the CCL.

[0044] In some embodiments, the mass ratio of boron nitride to silicon powder is 5% to 15%. For example, the mass ratio of boron nitride to silicon powder can be 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, or any value within the range of any two of the above values. Controlling the mass ratio of boron nitride to silicon powder within the above range is beneficial for better utilizing the advantages of both silicon powder and boron nitride, and for more fully realizing the complementary optimization of the properties of the two materials, thereby improving the performance of silicon powder-boron nitride composite materials.

[0045] In some embodiments, boron nitride includes hexagonal boron nitride. The selection of the above-mentioned types of boron nitride as the coating material in the silicon micropowder-boron nitride composite material can achieve complementary and optimized material properties, and the coating materials are all beneficial for improving the thermal conductivity and thermal stability of the copper-clad laminate.

[0046] One embodiment of this application also provides a copper-clad laminate, including a copper foil layer and a dielectric layer stacked together, wherein the dielectric layer includes the aforementioned silicon micropowder-boron nitride composite material.

[0047] The silicon micropowder-boron nitride composite material of this application has good bonding with copper clad laminate resin, which is beneficial to improving the compatibility of the interface between the copper clad laminate filler and the resin matrix. Therefore, copper clad laminates with the silicon micropowder-boron nitride composite material in the dielectric layer have improved overall performance.

[0048] The present application's solution will be explained below with reference to embodiments. Those skilled in the art will understand that the following examples are for illustrative purposes only and should not be construed as limiting the present application. Unless otherwise stated, reagents, software, and instruments involved in the following embodiments that are not specifically mentioned are all conventional commercially available products or open-source materials.

[0049] Example 1:

[0050] (1) A silicon micropowder-boron nitride composite material, the preparation method of which includes:

[0051] Step 1: Weigh a certain mass of spherical silica powder and pour it into ethanol. Turn on the stirring device to make the silica powder evenly dispersed in the ethanol. Then, weigh 2% to 10% of the silica powder mass and slowly add the corresponding mass of γ-aminopropyltriethoxysilane to the above dispersion system. Place the round-bottom flask in an oil bath at 120 °C and stir the reaction for 4 h. After the reaction is completed, the seed liquid is obtained.

[0052] Step 2: Weigh out 0.5% to 2.5% of the mass of silica powder, add sodium dodecyl sulfate to water, and stir until completely dissolved; add the seed liquid to the aqueous solution containing sodium dodecyl sulfate, and sonicate for 30 minutes to evenly disperse the seed liquid in the aqueous solution, forming a stable emulsion system, and obtain the seed emulsion.

[0053] Step 3: Weigh a certain mass of urea, and weigh the corresponding mass of boric acid according to 40%~60% of the mass of urea. First, add the boric acid to ethanol and stir to dissolve it. Similarly, add the urea to another ethanol and stir to dissolve it. Mix the two solutions of boric acid and urea evenly, and then use ammonia water to adjust the pH to between 8 and 10. Stop adding ammonia water and stir the reaction for 2 hours to obtain the precursor solution.

[0054] Step 4: Slowly add the precursor solution dropwise through a constant pressure dropping funnel to the reaction vessel containing the seed emulsion, while keeping the vessel stirred during the addition. After the addition is complete, place the reaction vessel in an oil bath, heat it to 120 °C, and continue stirring for 8 hours.

[0055] Step 5: After the reaction is completed, the product of the above reaction is centrifuged and washed multiple times, and then vacuum dried at 70 °C; the dried product is placed in a muffle furnace and heated to 900 °C at a heating rate of 5 °C / min, and annealed at this temperature for 3 h; after annealing, it is cooled to room temperature at a rate of 5 °C / min to obtain the silicon micropowder-boron nitride composite material.

[0056] (2) A copper-clad laminate, the preparation method of which includes:

[0057] Step 1: The synthesized silicon micropowder-boron nitride composite material is thoroughly mixed with PTFE emulsion to obtain co-condensate powder.

[0058] The second step is to obtain a raw base film (i.e., a dielectric layer) by curing, extruding, and calendering the co-condensate powder.

[0059] Step 3: Copper foil is laminated on both sides of the base film at high temperature and vacuum to obtain copper-clad laminate.

[0060] Example 2:

[0061] (1) A silicon micropowder-boron nitride composite material, the preparation method of which differs from that of Example 1 in that, in the third step, urea is replaced with melamine, and boric acid is weighed according to 40%~60% of the mass of melamine. The remaining steps are basically the same as those of Example 1.

[0062] (2) A copper-clad laminate, the preparation method of which is basically the same as that in Example 1.

[0063] Comparative Example 1:

[0064] A traditional copper-clad laminate, the preparation method of which includes:

[0065] Step 1, preparing the adhesive: Add bisphenol A type epoxy resin to the reactor, heat to 50 ℃ to 70 ℃, stir until completely dissolved, then add curing agent, initiator, and flame retardant in sequence, and continue stirring for 30 minutes to 60 minutes, controlling the speed at 50 r / min to 300 r / min to ensure that the additives are evenly dispersed to form a uniform and stable epoxy resin adhesive. The curing agent accounts for 5% to 15% of the epoxy resin mass, the accelerator accounts for 0.5% to 3%, and the flame retardant accounts for 10% to 30%.

[0066] The second step is impregnation: the fiberglass cloth is immersed in epoxy resin solution, and the impregnation speed is controlled from 0.5 m / min to 2 m / min to ensure full wetting.

[0067] The third step is adhesive application and drying: Use a scraper or extrusion roller to remove excess adhesive from the surface of the fiberglass cloth, so that the resin content of the prepreg is controlled between 40% and 60%. Then, put it into a drying oven and dry it at 120 ℃ to 150 ℃ for 10 to 30 minutes to allow the solvent to evaporate fully, thus obtaining the prepreg.

[0068] Step 4, lamination: The copper foil on both sides of the prepreg obtained above is laminated under high temperature and vacuum to obtain a copper-clad laminate.

[0069] Comparative Example 2:

[0070] (1) A silicon micro powder-boron nitride composite material, the preparation method of which differs from that of Example 1 is: weighing spherical silicon micro powder and hexagonal boron nitride powder in a mass ratio of 10:1, and mixing them thoroughly by mechanical stirring to obtain the silicon micro powder-boron nitride composite material.

[0071] (2) A copper-clad laminate, the preparation method of which is basically the same as that in Example 1.

[0072] Comparative Example 3:

[0073] (1) A silicon micropowder-boron nitride composite material, the preparation method of which differs from that of Example 1 is as follows: in the first step, the silane coupling agent is removed and the surface of the silicon micropowder is not modified; that is, the first step is: weigh a certain mass of spherical silicon micropowder and pour it into ethanol, turn on the stirring device to make the silicon micropowder uniformly dispersed in ethanol, transfer it into an oil bath at 120 °C, and stir and react for 4 h. The remaining steps are basically the same as those in Example 1.

[0074] (2) A copper-clad laminate, the preparation method of which is basically the same as that in Example 1.

[0075] This application also conducted the following performance tests on the copper-clad laminates of Examples 1-2 and Comparative Examples 1-3:

[0076] (1) Dielectric constant and dielectric loss factor test: The dielectric properties were tested using the Split Cylindrical Resonator Method (SPDR) (a standard of the American Society for Testing and Materials, method number ASTM 2520). First, the 10 GHz test fixture was connected to the network analyzer, and the center frequency f of the cavity was measured. c and quality factor Q c Then, after inserting the sample, the center frequency f after loading the sample was measured again. s and loaded quality factor Q s Then, using the following formula:

[0077] Dielectric constant (Dk) = , Dielectric loss (Df) = ;

[0078] Calculate the dielectric constant and dielectric loss, where f c It is the center frequency of the cavity, f s It is the center frequency of the sample, Q. c It is the cavity quality factor, Q s It is the sample quality factor, V c It is the volume of the cavity, V s It is the volume of the sample.

[0079] (2) Thermal expansion coefficient test: Thermomechanical analysis was used. The sample was heated by the thermomechanical analyzer using an IPC TM 650 2.4.24.4 (-55~288℃). The thermal expansion coefficient α was calculated by measuring the change in length of the sample at different temperatures. i :

[0080]

[0081] Where, α i It is the coefficient of thermal expansion of the material in the i-direction (i=X,Y,Z), with units of ppm / ℃, ΔL i It is the change in length of the material in the i-direction (i=X,Y,Z), with units of μm and L. 0i ΔT is the initial length of the material in the i-direction (i=X,Y,Z), in meters (m), and ΔT is the change in temperature, in degrees Celsius (℃).

[0082] (3) Thermal conductivity test: The steady-state heat flow method is used. A certain heat flow rate (the heat flow output is detected by a heat flow sensor) and pressure are applied to the sample above and below it. The thickness of the sample and the temperature difference between the hot plate and the cold plate are tested to obtain the thermal conductivity λ of the sample.

[0083]

[0084] Where λ is the thermal conductivity of the sample, in units of W / Mk, Q h This is the heat flux output from the sensor above, measured in W / m³. 2 Q c This is the heat flux output from the sensor below, measured in W / m³. 2 L is the thickness of the sample in meters (m), and ΔT is the temperature difference between the upper and lower surfaces of the sample in kilometer (K).

[0085] (4) Peel strength test:

[0086] ① Sample preparation: Cut a sample with a length of 120 mm and a width of 70 mm from the area more than 2.54 mm from the edge of the laminated copper-clad board. Apply anti-corrosion tape to the sample and use ferric chloride etching solution to make three test strips with a width of 3.18 mm and a length of 100 mm in the sample area.

[0087] ② Sample measurement: Using a universal testing machine, with the copper foil side of the test strip facing upwards, align the test strip with the center of the sample holder, place the pin plate on top of the test strip, insert the clamping head into the hole, align the copper foil strip with the inclined groove, clamp the copper foil strip, and make the peeling direction 90 degrees with the insulating substrate, and start peeling at a rate of 50.8 mm / min.

[0088] ③ Calculate the peel strength: Peel strength = minimum peel force / sample width.

[0089] Please refer to Table 1 for the test results above.

[0090] Table 1. Performance test results of copper clad laminates in Examples 1-2 and Comparative Examples 1-3 of this application

[0091]

[0092] Examples 1-2 of this application, prepared using a pre-defined method, yield a silicon micropowder-boron nitride composite material comprising a core (mainly silicon micropowder) and a coating (mainly boron nitride) on the core surface. The silicon micropowder surface also contains amino groups to enhance the bonding force between the silicon micropowder and boron nitride, approximating a core-shell structure. This silicon micropowder-boron nitride composite material better combines the advantages of silicon micropowder's low coefficient of thermal expansion and insulation with boron nitride's high thermal conductivity and low dielectric constant. The pre-defined structural relationship between silicon micropowder and boron nitride allows for better complementary optimization of the two materials' properties. Therefore, the copper-clad laminates obtained in Examples 1-2 of this application exhibit improved insulation, lower signal transmission loss, meeting the requirements of high-frequency, high-speed communication. Simultaneously, they possess improved thermal conductivity and good thermal stability, which helps reduce warping and delamination, thus improving the overall performance of the copper-clad laminate.

[0093] Compared to Example 1, Comparative Example 1 is a traditional copper-clad laminate, whose performance is significantly inferior to that of Example 1 of this application, indicating that the silicon micropowder-boron nitride composite material of this application can significantly improve the overall performance of copper-clad laminates.

[0094] Compared to Example 1, the composite material of Comparative Example 2 simply mixes silicon micropowder and boron nitride, which cannot obtain the silicon micropowder-boron nitride composite material of this application. The copper-clad laminate obtained by Comparative Example 2 has lower performance than that of Example 1 of this application. This shows that in the silicon micropowder-boron nitride composite material obtained by the preparation method of this application, silicon micropowder and boron nitride can better achieve complementary optimization of the properties of the two materials by combining them through a preset structural relationship.

[0095] Compared to Example 1, the composite material in Comparative Example 3 did not use a silane coupling agent to modify the surface of the silicon micropowder. The performance of the resulting composite material was inferior to that of the Example 1. This indicates that the present application uses a silane coupling agent to graft amino groups onto the surface of the silicon micropowder, which is beneficial to improving the performance of the resulting silicon micropowder-boron nitride composite material.

[0096] The above embodiments are only used to illustrate the technical solutions of this application and are not intended to limit it. Although this application has been described in detail with reference to the above preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions to the technical solutions of this application should not depart from the spirit and scope of the technical solutions of this application.

Claims

1. A method for preparing a silicon micropowder-boron nitride composite material for a copper-clad laminate dielectric layer, characterized in that, The preparation method includes: mixing silicon micropowder, silane coupling agent and organic solvent and heating to graft amino groups onto the surface of the silicon micropowder to obtain a seed liquid; mixing the seed liquid, emulsifier and solvent to obtain a seed emulsion; mixing a boron-containing compound, a nitrogen-containing compound and organic solvent to obtain a precursor solution; mixing the seed emulsion and the precursor solution and heating to coat the surface of the silicon micropowder with boron nitride, thereby obtaining the silicon micropowder-boron nitride composite material.

2. The preparation method according to claim 1, characterized in that, The boron-containing compound includes one or more of boric acid, boron chloride, and sodium borate tetradecylhydrate, and the nitrogen-containing compound includes one or more of urea, melamine, hexamethylenetetramine, ethylenediamine, and ammonia.

3. The preparation method according to claim 1, characterized in that, The pH of the precursor solution is 8 to 10.

4. The preparation method according to claim 1, characterized in that, After heating the seed emulsion and the precursor solution, the preparation method further includes washing, drying and annealing the heated product.

5. The preparation method according to claim 1, characterized in that, The emulsifier includes one or more of sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, sodium dodecyl sulfonate, and hexadecyltrimethylammonium bromide.

6. The preparation method according to claim 1, characterized in that, The preparation method satisfies at least one of the following conditions: (1) the mass ratio of the silane coupling agent to the silicon micropowder is 2% to 10%; (2) the mass ratio of the emulsifier to the silicon micropowder is 0.5% to 2.5%; (3) the mass ratio of the boron-containing compound to the nitrogen-containing compound is 40% to 60%; (4) the mass ratio of the boron-containing compound to the silicon micropowder is 12.5% ​​to 37.4%.

7. The preparation method according to claim 1, characterized in that, The temperature after heating is between 90 ℃ and 140 ℃.

8. A silicon micropowder-boron nitride composite material, characterized in that, The silicon micropowder-boron nitride composite material, prepared by any one of claims 1-7, comprises a core and a coating disposed on at least a portion of the surface of the core, wherein the core comprises silicon micropowder and the coating comprises boron nitride.

9. The silicon micropowder-boron nitride composite material as described in claim 8, characterized in that, The silicon micropowder-boron nitride composite material satisfies at least one of the following conditions: (1) the mass ratio of the boron nitride to the silicon micropowder is 5% to 15%; (2) the boron nitride includes hexagonal boron nitride.

10. A copper-clad laminate, comprising a copper foil layer and a dielectric layer stacked thereon, characterized in that, The dielectric layer comprises the silicon micropowder-boron nitride composite material as described in claim 8 or 9.

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