A high thermal conductivity, low dielectric composite material, its preparation method and application

Abstract

This invention relates to a high thermal conductivity, low dielectric composite material, its preparation method, and its application, belonging to the technical field of high-frequency copper-clad laminates for 5G communication. The preparation method of the high thermal conductivity, low dielectric composite material of this invention includes the following steps: (1) redistributing low molecular weight thermoplastic polyphenylene ether and modifying it by end-hydroxyl group propylene oxidation to obtain thermosetting polyphenylene ether; (2) dispersing the thermosetting polyphenylene ether obtained in step (1), adding boron nitride modified with a silane coupling agent containing double bonds, mixing evenly, drying, and hot pressing to obtain a high thermal conductivity, low dielectric composite material. When the modified boron nitride of this invention is mixed with thermosetting polyphenylene ether, the carbon-carbon double bonds on the surface of the modified boron nitride react with the double bonds on the main chain of the thermosetting polyphenylene ether, increasing the interfacial force between the two phases of the composite material, reducing the interfacial thermal resistance between the sheet-like boron nitride powder and the organic resin matrix, improving the uniformity of the composite material's properties, and obtaining a high thermal conductivity, low dielectric composite material.

Description

Technical Field

[0001] This invention relates to the field of high-frequency copper-clad laminate technology for 5G communication, and particularly to a high thermal conductivity, low dielectric composite material, its preparation method and application. Background Technology

[0002] With the rapid development of communication technologies towards high-frequency bands such as 5G and 6G, printed circuit boards (PCBs) based on epoxy resin are facing obsolescence because their dielectric properties cannot meet the requirements for high-speed and low-loss signal transmission. Simultaneously, the integration and power density of electronic devices are gradually increasing, leading to a significant increase in heat generated per unit area. To prevent overheating from affecting operational stability and lifespan, PCBs also need to significantly improve their thermal conductivity. Therefore, developing polymer-based composite materials with low dielectric constant (Dk), low dielectric loss (Df), and high thermal conductivity (TC) for the fabrication of high-frequency PCBs is a pressing issue that the industry needs to address.

[0003] PCB substrates—copper clad laminates—are primarily composed of thermosetting resins and ceramic fillers. The mixture undergoes a mixing, coating, and baking process to obtain a prepreg, which is then laminated with copper foil through multi-layer lamination. For high-frequency copper clad laminates, the thermosetting resins are typically hydrocarbon resins, polytetrafluoroethylene (PTFE), and polyphenylene ether (PPE). PPE exhibits low dielectric constant and dielectric loss, low hygroscopicity, and good mechanical strength, making it a promising candidate for high-frequency PCBs. However, PPE is a thermoplastic material, requiring chemical or physical modification to convert it into a thermosetting resin. Furthermore, its compatibility with thermally conductive filler BN is poor, resulting in a low BN filling rate and limiting the development of higher thermal conductivity composites based on BN. While chemical or physical surface modification of BN can improve the compatibility between the filler and the matrix to some extent, the interfacial forces between the two phases of the composite material remain weak, resulting in a relatively high interfacial thermal resistance. Consequently, the thermal conductivity of the composite material remains low, failing to meet the requirements for thermal conductivity and dielectric properties in high-frequency, high-speed copper clad laminates. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a composite material with advantages such as good compatibility between filler and resin matrix, high thermal conductivity, and low dielectric constant, as well as its preparation method and application.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] In a first aspect, the present invention provides a method for preparing a high thermal conductivity, low dielectric composite material, comprising the following steps:

[0007] (1) A thermosetting polyphenylene ether is obtained by modifying a low molecular weight thermoplastic polyphenylene ether with hydroxyl groups; the molecular weight of the low molecular weight thermoplastic polyphenylene ether is 2000-4000.

[0008] (2) Disperse the thermosetting polyphenylene ether obtained in step (1), add boron nitride modified with a silane coupling agent containing double bonds, mix evenly, dry, and hot press to obtain a high thermal conductivity and low dielectric composite material; the modified boron nitride is composed of at least one modified hexagonal plate boron nitride with a plate diameter of 1.0-30.0 μm.

[0009] This invention modifies boron nitride with a silane coupling agent containing double bonds. When mixed with thermosetting polyphenylene ether, the double bonds on the surface of the modified boron nitride undergo an addition reaction with the double bonds on the molecular chain of the thermosetting polyphenylene ether. This enhances the compatibility and interfacial forces between the two phases, improves the compatibility between the two phases, and significantly improves the uniformity of the composition and properties of the composite material. In turn, it reduces the interfacial thermal resistance between the boron nitride powder and the polyphenylene ether matrix, resulting in an improved thermal conductivity and a decreased dielectric constant and dielectric loss in the composite material. It has the advantages of high thermal conductivity and low dielectric strength.

[0010] The hexagonal plate boron nitride used in this invention has the advantages of high thermal conductivity, excellent dielectric properties, and stable chemical properties; the thermoplastic polyphenylene ether used for modification has good mechanical strength and high temperature resistance, making it more suitable for application in the preparation of high-frequency copper-clad laminates for 5G communication.

[0011] In a preferred embodiment of the preparation method of the high thermal conductivity and low dielectric composite material of the present invention, the weight ratio of thermosetting polyphenylene ether to modified boron nitride is thermosetting polyphenylene ether: modified boron nitride = 5:(3-20). When the weight ratio of thermosetting polyphenylene ether to modified boron nitride is 5:(3-20), the composite material of the present invention has the technical effect of high thermal conductivity and low dielectric properties.

[0012] In a preferred embodiment of the preparation method of the high thermal conductivity and low dielectric composite material of the present invention, the weight ratio of thermosetting polyphenylene ether to modified boron nitride is thermosetting polyphenylene ether: modified boron nitride = 5:(3-7.5). When the weight ratio of thermosetting polyphenylene ether to modified boron nitride is 5:(3-7.5), the filling rate of modified boron nitride in the composite material of the present invention is 60%. The increased filling rate of modified boron nitride not only improves the thermal conductivity of the composite material, but also reduces the dielectric constant and dielectric loss, giving the composite material of the present invention the technical effect of higher thermal conductivity and lower dielectric properties.

[0013] In a preferred embodiment of the preparation method of the high thermal conductivity and low dielectric composite material of the present invention, the modified boron nitride is composed of modified hexagonal plate boron nitride with a plate diameter of 30 μm and a plate diameter of 3.0 μm, and the weight ratio of the modified hexagonal plate boron nitride with a plate diameter of 30 μm to the modified hexagonal plate boron nitride with a plate diameter of 3.0 μm is (10-12):(2-3).

[0014] This invention uses a combination of two types of modified hexagonal boron nitride with different sheet sizes, which can improve the contact between boron nitrides. The composite material prepared by mixing with polyphenylene ether has improved density, excellent thermal conductivity and dielectric properties.

[0015] In a preferred embodiment of the preparation method of the high thermal conductivity and low dielectric composite material of the present invention, the weight ratio of the modified hexagonal boron nitride with a sheet diameter of 30 μm and the modified hexagonal boron nitride with a sheet diameter of 3.0 μm is (10.6-11):(2.5-2.8). Under this preferred ratio range, the high thermal conductivity and low dielectric composite material prepared by the present invention has a further improved density and further improved thermal conductivity and dielectric properties.

[0016] In a preferred embodiment of the preparation method of the high thermal conductivity and low dielectric composite material of the present invention, the weight ratio of modified boron nitride with a sheet diameter of 30 μm and 3.0 μm is 10.6:2.7 (modified boron nitride with a sheet diameter of 30 μm: modified boron nitride with a sheet diameter of 3.0 μm). This ratio results in the best contact between the two types of modified hexagonal sheet boron nitride, leading to the best composite material density and thermal conductivity.

[0017] As a preferred embodiment of the preparation method of the high thermal conductivity and low dielectric composite material of the present invention, in step (2), the silane coupling agent containing double bonds includes at least one of vinyltrimethoxysilane, methylvinyldimethoxysilane, γ-aminopropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, and γ-methacryloyloxypropyltrimethoxysilane.

[0018] In a preferred embodiment of the preparation method of the high thermal conductivity and low dielectric composite material of the present invention, the boron nitride is treated with a concentrated alkali solution, namely 5 mol / L NaOH, before reacting with the silane coupling agent containing double bonds.

[0019] This invention reacts hexagonal plate-shaped boron nitride with concentrated alkaline solution to obtain hydroxylated boron nitride. When the hydroxylated boron nitride is mixed with a silane coupling agent, the silane coupling agent can fully wet the hydroxylated boron nitride powder due to its small steric hindrance and coat its surface with a dense organic thin layer, thereby improving the uniformity of the modified boron nitride when mixed with the resin and resulting in a composite material with better overall performance.

[0020] In a preferred embodiment of the preparation method of the high thermal conductivity and low dielectric composite material of the present invention, the mass ratio of the silane coupling agent to the hexagonal plate-shaped boron nitride is silane coupling agent: hexagonal plate-shaped boron nitride = 0.06:(2.5-3.3). When the mass ratio of the silane coupling agent to the hexagonal plate-shaped boron nitride is 0.06:(2.5-3.3), the double bond distribution on the modified boron nitride obtained by the present invention is more uniform, giving the high thermal conductivity and low dielectric composite material of the present invention the technical effect of higher thermal conductivity and lower dielectric.

[0021] As a preferred embodiment of the preparation method of the high thermal conductivity and low dielectric composite material of the present invention, step (1) is: to obtain low molecular weight polyphenylene ether by redistribution reaction of thermoplastic polyphenylene ether, and then mix it with methacrylic anhydride and add a catalyst to obtain thermosetting polyphenylene ether.

[0022] In a preferred embodiment of the preparation method of the high thermal conductivity and low dielectric composite material of the present invention, the weight ratio of the low molecular weight polyphenylene ether to methacrylic anhydride is 3:0.87. When the weight ratio of low molecular weight polyphenylene ether to methacrylic anhydride is 3:0.87, the high thermal conductivity and low dielectric composite material of the present invention has the technical effect of higher thermal conductivity and lower dielectric.

[0023] As a preferred embodiment of the preparation method of the high thermal conductivity and low dielectric composite material of the present invention, at least one of the following (a) to (c) is provided:

[0024] (a) The thermosetting polyphenylene ether in step (2) is dispersed as thermosetting polyphenylene ether dispersed in an organic solvent;

[0025] (b) The drying in step (2) is baking at 60-100℃ for 6-12 hours;

[0026] (c) The hot pressing conditions in step (2) are 220°C, 10MPa, and 1.5h.

[0027] Secondly, the present invention provides the above-mentioned high thermal conductivity and low dielectric composite material, which is prepared by the above-mentioned method for preparing high thermal conductivity and low dielectric composite material.

[0028] Thirdly, the present invention provides the application of the above-mentioned high thermal conductivity and low dielectric composite material in the preparation of high frequency copper clad laminates for 5G communication.

[0029] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0030] 1. The present invention uses thermosetting polyphenylene ether obtained by modifying thermoplastic polyphenylene ether as a resin matrix, and mixes it with filler to obtain a composite material with significantly improved dielectric properties without adding other resin matrices.

[0031] 2. When the modified boron nitride of the present invention is mixed with the silane coupling agent after being treated with concentrated alkali solution, the steric hindrance between the boron nitride and the silane coupling agent is reduced due to the presence of hydroxyl groups in the boron nitride. The boron nitride is fully wetted, and a dense organic thin layer is coated on the surface of the boron nitride, which is beneficial to improving the compatibility between boron nitride and polyphenylene ether.

[0032] 3. When the modified boron nitride of the present invention is mixed with thermosetting polyphenylene ether, the carbon-carbon double bonds on the surface of the modified boron nitride react with the double bonds on the main chain of the thermosetting polyphenylene ether, which improves the interfacial force between the two phases of the composite material, reduces the interfacial thermal resistance between the sheet-like boron nitride powder and the organic resin matrix and the interfacial polarization between the two phases, improves the uniformity of the composite material properties, and obtains an insulating composite material with excellent comprehensive performance. Detailed Implementation

[0033] To better illustrate the purpose, technical solution, and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments.

[0034] In the following examples and comparative examples, the thermoplastic polyphenylene ether was manufactured by Asahi Kasei Corporation of Japan, and its grade was S201.

[0035] The manufacturer of bisphenol A is Shanghai Aladdin Biochemical Technology Co., Ltd., and the product number is B802575.

[0036] The manufacturer of benzoyl peroxide is Shanghai Aladdin Biochemical Technology Co., Ltd., and the product number is B104630.

[0037] The manufacturer of methyl vinyl dimethoxysilane is Shanghai Aladdin Biochemical Technology Co., Ltd., and its brand name is D13192.

[0038] The manufacturer of γ-aminopropyltriethoxysilane is Shanghai Aladdin Biochemical Technology Co., Ltd., and the brand name is A107147.

[0039] Unless otherwise specified, all other reagents and materials are available commercially.

[0040] Example 1

[0041] An embodiment of the high thermal conductivity, low dielectric composite material and its preparation method of the present invention is provided. The high thermal conductivity, low dielectric composite material of this embodiment is prepared by the following preparation method:

[0042] 1. Preparation of thermosetting polyphenylene ether.

[0043] (a) 15 parts by weight of toluene solution and 9 parts by weight of thermoplastic polyphenylene ether were stirred in an oil bath at 95°C until the thermoplastic polyphenylene ether was completely dissolved. 4.5 parts by weight of bisphenol A were added and mixed evenly. 0.36 parts by weight of benzoyl peroxide were added and stirred for 6 hours. The mixture was cooled to room temperature, and excess methanol was added to wash the mixture. The mixture was filtered and dried to obtain low molecular weight polyphenylene ether with a molecular weight of 2000-4000.

[0044] (b) 6 parts by weight of the low molecular weight polyphenylene ether obtained in step (a) and 100 parts by weight of chlorobenzene were stirred in an oil bath at 70°C until the low molecular weight polyphenylene ether was completely dissolved. 1.74 parts by weight of methacrylic anhydride were added and mixed. 1.40 parts by weight of 4-dimethylaminopyridine were added and stirred for 4 hours. The mixture was cooled to room temperature, washed with excess methanol, filtered, and dried at 100°C for 6 hours to obtain thermosetting polyphenylene ether.

[0045] 2. Preparation of modified boron nitride.

[0046] 10.6 parts by weight of hexagonal plate-shaped boron nitride (plate diameter 30 μm) were mixed with 400 parts by weight of 5 mol / L NaOH, and 2.7 parts by weight of hexagonal plate-shaped boron nitride (plate diameter 3.0 μm) were added. The mixture was stirred evenly and reacted at 100 °C for 24 h. After filtration, washing, and drying, hydroxylated boron nitride was obtained. 3 parts by weight of hydroxylated boron nitride were mixed with 150 parts by weight of ethanol, and 0.06 parts by weight of methylvinyldimethoxysilane were added. The mixture was stirred at 60 °C for 2 h, filtered to remove the solvent, and dried at 100 °C to obtain modified boron nitride.

[0047] 3. Preparation of high thermal conductivity and low dielectric composite materials.

[0048] Five parts by weight of the thermosetting polyphenylene ether obtained in step 1 were mixed with 50 parts by weight of toluene, and 7.5 parts by weight of modified boron nitride were added. The mixture was stirred for 3 hours to mix evenly, baked at 100°C for 6 hours, and then placed in a stainless steel mold and hot-pressed at 220°C and 10MPa for 1.5 hours to obtain a high thermal conductivity, low dielectric composite material with a thickness of 0.35-0.40 mm.

[0049] Example 2

[0050] An embodiment of the high thermal conductivity, low dielectric composite material and its preparation method of the present invention, wherein the high thermal conductivity, low dielectric composite material of this embodiment is prepared by the following preparation method:

[0051] 1. The preparation of thermosetting polyphenylene ether is the same as step 1 in Example 1.

[0052] 2. Preparation of modified boron nitride.

[0053] Similar to step 2 of Example 1, except that the amount of hexagonal boron nitride with a diameter of 30 μm is 10.2 parts by weight, and the amount of hexagonal boron nitride with a diameter of 3.0 μm is 2.5 parts by weight, while the other parameters remain unchanged.

[0054] 3. Preparation of high thermal conductivity and low dielectric composite materials.

[0055] Similar to step 3 of Example 1, except that the amount of modified boron nitride used is 5 parts by weight, while the other parameters and conditions remain unchanged.

[0056] Example 3

[0057] An embodiment of the high thermal conductivity, low dielectric composite material and its preparation method of the present invention is provided. The high thermal conductivity, low dielectric composite material of this embodiment is prepared by the following preparation method:

[0058] 1. The preparation of thermosetting polyphenylene ether is the same as step 1 in Example 1.

[0059] 2. Preparation of modified boron nitride.

[0060] Similar to step 2 of Example 1, except that the amount of hexagonal boron nitride with a diameter of 30 μm is 11 parts by weight and the amount of hexagonal boron nitride with a diameter of 3.0 μm is 2.8 parts by weight, while the other parameters and conditions remain unchanged.

[0061] 3. Preparation of high thermal conductivity and low dielectric composite materials.

[0062] Five parts by weight of the thermosetting polyphenylene ether obtained in step 1 were mixed with 50 parts by weight of toluene, and 3.33 parts by weight of modified boron nitride were added. The mixture was stirred for 3 hours to mix evenly, baked at 100°C for 12 hours, and then placed in a stainless steel mold and hot-pressed at 220°C and 10MPa for 1.5 hours to obtain a high thermal conductivity, low dielectric composite material with a thickness of 0.35-0.40 mm.

[0063] Example 4

[0064] This invention provides an embodiment of a high thermal conductivity, low dielectric composite material and its preparation method. The preparation method of the high thermal conductivity, low dielectric composite material and its raw material, thermosetting polyphenylene ether, in this embodiment is the same as in Example 1. The preparation method of the raw material modified boron nitride is as follows:

[0065] 10.6 parts by weight of hexagonal plate-shaped boron nitride (plate diameter 30 μm) were mixed with 400 parts by weight of 5 mol / L NaOH, and 2.7 parts by weight of plate-shaped boron nitride (plate diameter 3.0 μm) were added. The mixture was stirred evenly and reacted at 100 °C for 24 h. After filtration, washing, and drying, hydroxylated boron nitride was obtained. 3 parts by weight of hydroxylated boron nitride were mixed with 150 parts by weight of ethanol, and 0.06 parts by weight of γ-aminopropyltriethoxysilane were added. The mixture was stirred at 60 °C for 2 h, filtered to remove the solvent, and dried at 100 °C to obtain modified boron nitride.

[0066] Example 5

[0067] This invention provides an embodiment of a high thermal conductivity, low dielectric composite material and its preparation method. The preparation method of the high thermal conductivity, low dielectric composite material and its raw material, thermosetting polyphenylene ether, in this embodiment is the same as in Example 1. The preparation method of the raw material modified boron nitride is as follows:

[0068] Ten parts by weight of hexagonal plate-shaped boron nitride (plate diameter 30 μm) were mixed with 400 parts by weight of 5 mol / L NaOH and reacted at 100 °C for 24 h. The mixture was then filtered, washed, and dried to obtain hydroxylated boron nitride. Three parts by weight of hydroxylated boron nitride were mixed with 150 parts by weight of ethanol, and 0.06 parts by weight of methylvinyldimethoxysilane were added. The mixture was stirred at 60 °C for 2 h, filtered to remove the solvent, and dried at 100 °C to obtain modified boron nitride.

[0069] Comparative Example 1

[0070] This invention provides a comparative example of a high thermal conductivity, low dielectric composite material and its preparation method. The preparation method of the thermosetting polyphenylene ether, the raw material in the high thermal conductivity, low dielectric composite material described in this comparative example, is the same as that in Example 1. The composite material preparation method is as follows:

[0071] Five parts by weight of the thermosetting polyphenylene ether obtained in step 1 were mixed with 50 parts by weight of toluene, and 7.5 parts by weight of unmodified hexagonal platen boron nitride (plate diameter of 30 μm) were added. The mixture was stirred for 3 hours to achieve uniform mixing, baked at 100°C for 6 hours, and then placed in a stainless steel mold and hot-pressed at 220°C and 10 MPa for 1.5 hours to obtain a high thermal conductivity, low dielectric composite material with a thickness of 0.35-0.40 mm.

[0072] Comparative Example 2

[0073] This invention provides a comparative example of a high thermal conductivity, low dielectric composite material and its preparation method. The preparation method of the thermosetting polyphenylene ether, the raw material in the high thermal conductivity, low dielectric composite material described in this comparative example, is the same as that in Example 1. The composite material preparation method is as follows:

[0074] Five parts by weight of the thermosetting polyphenylene ether obtained in step 1 were mixed with 50 parts by weight of toluene. Six and one parts by weight of unmodified hexagonal boron nitride (30 μm in diameter) and one and a half parts by weight of unmodified hexagonal boron nitride (3.0 μm in diameter) were added. The mixture was stirred for 3 hours to achieve uniform mixing. The mixture was baked at 100°C for 6 hours and then placed in a stainless steel mold and hot-pressed at 220°C and 10 MPa for 1.5 hours to obtain a high thermal conductivity, low dielectric composite material with a thickness of 0.35-0.40 mm.

[0075] Comparative Example 3

[0076] This invention provides a comparative example of a high thermal conductivity, low dielectric composite material and its preparation method. The preparation method of the thermosetting polyphenylene ether, the raw material in the high thermal conductivity, low dielectric composite material described in this comparative example, is the same as that in Example 1. The composite material preparation method is as follows:

[0077] Five parts by weight of the thermosetting polyphenylene ether obtained in step 1 were mixed with 50 parts by weight of toluene. 3.75 parts by weight of unmodified hexagonal platen boron nitride (plate diameter 30 μm) and 3.75 parts by weight of unmodified hexagonal platen boron nitride (plate diameter 3.0 μm) were added, and the mixture was stirred for 3 hours to achieve uniform mixing. The mixture was baked at 100°C for 6 hours, placed in a stainless steel mold, and hot-pressed at 220°C and 10 MPa for 1.5 hours to obtain a high thermal conductivity, low dielectric composite material with a thickness of 0.35-0.40 mm.

[0078] Comparative Example 4

[0079] This invention provides an embodiment of a high thermal conductivity, low dielectric composite material and its preparation method. The preparation method of the high thermal conductivity, low dielectric composite material and its raw material, thermosetting polyphenylene ether, in this embodiment is the same as in Example 1. The preparation method of the raw material modified boron nitride is as follows:

[0080] 10.6 parts by weight of hexagonal plate-shaped boron nitride (plate diameter 30 μm) were mixed with 400 parts by weight of 5 mol / L NaOH, and 2.7 parts by weight of plate-shaped boron nitride (plate diameter 3.0 μm) were added. The mixture was stirred evenly and reacted at 100 °C for 24 h. After filtration, washing, and drying, hydroxylated boron nitride was obtained. 2.97 parts by weight of hydroxylated boron nitride were mixed with 150 parts by weight of ethanol, and 0.45 parts by weight of methylvinyldimethoxysilane were added. The mixture was stirred at 60 °C for 2 h, filtered to remove the solvent, and dried at 100 °C to obtain modified boron nitride.

[0081] Comparative Example 5

[0082] This invention provides a comparative example of a high thermal conductivity, low dielectric composite material. The method for preparing the high thermal conductivity, low dielectric composite material using modified boron nitride is the same as in Example 1. The method for preparing the composite material is also similar to that in Example 1, except that the thermosetting polyphenylene ether is replaced with thermoplastic polyphenylene ether.

[0083] Example of effect

[0084] The composite materials of each embodiment and comparative example were subjected to performance tests. The test results are shown in Table 1. The test items are as follows:

[0085] Thermal conductivity, tested at 25°C according to ASTM-E1461 standard;

[0086] Dielectric constant and dielectric loss were tested at a frequency of 10 GHz according to IEC 61189-2-721 (2015-04).

[0087] Table 1. Composite material performance test results for each embodiment and comparative example.

[0088]

[0089] As shown in Table 1, through Examples 1-3, it can be seen that with the increase of modified boron nitride filling rate, the density of the composite material increases, forming an efficient thermal conductivity pathway, and its thermal conductivity is significantly improved. Meanwhile, the dielectric properties of the composite material change little, indicating that the uniformity of the modified composite material is improved. The prepared composite material has good thermal conductivity and excellent dielectric properties, improving its overall performance and stability when applied to copper-clad laminates. Furthermore, since modified boron nitride is a thermally conductive filler, the higher the filling rate, the better the thermal conductivity of the composite material. Therefore, the thermal conductivity of Examples 2 and 3 is worse than that of Example 1, while the dielectric constant and dielectric loss are close to those of Example 1. This indicates that increasing the modified boron nitride filling rate can increase the dielectric constant and reduce the dielectric loss of the composite material, but its effect is relatively small.

[0090] The comparison between Comparative Example 2 and Example 1 shows that the chemical reaction between the double bonds on the thermosetting polyphenylene ether molecular chain and the double bonds on the modified boron nitride surface can significantly improve the interfacial force between the two phases of the composite material, enhance the compatibility between the two phases, thereby reducing the interfacial thermal resistance, resulting in a significant improvement in the thermal conductivity and dielectric properties of the modified composite material.

[0091] Example 4 involves modifying two types of plate-like boron nitride using γ-aminopropyltriethoxysilane coupling agent. The modification effect is not as good as in Example 1. This is because the boron nitride modified by γ-aminopropyltriethoxysilane coupling agent cannot chemically react with polyphenylene ether. Although it can improve the compatibility between boron nitride and polyphenylene ether, the interaction between the two phases is weak. It cannot significantly improve the performance of the composite material through chemical reaction at the phase interface as in Example 1. However, compared with the comparative example, the thermal conductivity of the composite material in Example 4 is significantly improved and the dielectric properties are significantly reduced.

[0092] Example 5 is a composite material prepared by modifying boron nitride. Compared with Comparative Example 1, its comprehensive performance is significantly improved, which also shows that the modification of double bonds on the surface of boron nitride is beneficial to enhancing the interfacial forces and improving the performance of the composite material.

[0093] Comparative Examples 1 and 2 are composite materials obtained by combining one or two different sizes of unmodified hexagonal boron nitride with thermosetting polyphenylene ether, respectively. The comparative examples are modified boron nitride with two different sheet diameters in unsuitable weight ratios. As shown in Table 1, in Comparative Example 1, with a single-size boron nitride as a filler, there is less contact between the boron nitride particles, resulting in a lower density, relatively lower thermal conductivity, and relatively higher dielectric constant and dielectric loss in the composite material prepared with the thermosetting polyphenylene ether resin matrix. Comparative Examples 2 and 3 are composites of boron nitride with different sheet diameters. At the same filler ratio, the density of the composite material is significantly improved and the thermal conductivity is effectively enhanced after the two types of sheet boron nitride are combined and filled into the modified polyphenylene ether. However, the dielectric properties of the composite material do not change much, and may even increase slightly. The overall performance is weaker than the composite material of the examples. Copper-clad laminates prepared using the composite materials obtained in Comparative Examples 1 and 3 will have a significant disadvantage in performance.

[0094] The silane coupling agent used in Comparative Example 4 was used in an amount higher than the range value, which caused the silane coupling agent to undergo a cross-linking reaction after hydrolysis. At the same time, the excessive modifier on the surface of boron nitride also increased the interfacial thermal resistance between the two phases, thereby reducing the performance of the composite material.

[0095] Comparative Example 5, due to the lack of modification of polyphenylene ether, exhibits thermoplasticity, resulting in poor dimensional stability of the composite material, which is a significant disadvantage in the preparation of copper-clad laminates.

[0096] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A method for preparing a high thermal conductivity, low dielectric composite material, characterized in that, Includes the following steps: (1) Thermoplastic polyphenylene ether is redistributed to obtain low molecular weight polyphenylene ether, which is then mixed with methacrylic anhydride, a catalyst is added, and an acylation reaction is carried out to obtain thermosetting polyphenylene ether; the molecular weight of the low molecular weight polyphenylene ether is 2000-4000. (2) Disperse the thermosetting polyphenylene ether obtained in step (1), add boron nitride modified with a silane coupling agent containing double bonds, mix evenly, dry, and hot press to obtain a high thermal conductivity and low dielectric composite material. The weight ratio of the thermosetting polyphenylene ether to the modified boron nitride is thermosetting polyphenylene ether: modified boron nitride = 5: (3-20). The modified boron nitride is composed of modified hexagonal plate-shaped boron nitride with a plate diameter of 30 μm and a plate diameter of 3.0 μm, and the weight ratio of the modified hexagonal plate-shaped boron nitride with a plate diameter of 30 μm to that with a plate diameter of 3.0 μm is (10-12):(2-3). The mass ratio of the silane coupling agent to the hexagonal plate boron nitride is silane coupling agent: hexagonal plate boron nitride = 0.06: (2.5-3.3).

2. The method for preparing the high thermal conductivity, low dielectric composite material as described in claim 1, characterized in that, The weight ratio of the thermosetting polyphenylene ether to the modified boron nitride is thermosetting polyphenylene ether: modified boron nitride = 5: (3-7.5).

3. The method for preparing the high thermal conductivity, low dielectric composite material as described in claim 1, characterized in that, The weight ratio of the modified hexagonal plate boron nitride with a plate diameter of 30 μm and the modified hexagonal plate boron nitride with a plate diameter of 3.0 μm is (10.6-11):(2.5-2.8).

4. The method for preparing the high thermal conductivity, low dielectric composite material as described in claim 1, characterized in that, In step (2), the silane coupling agent containing double bonds includes at least one of vinyltrimethoxysilane, methylvinyldimethoxysilane, and γ-methacryloyloxypropyltrimethoxysilane.

5. A high thermal conductivity, low dielectric composite material, characterized in that, It is prepared by the preparation method according to any one of claims 1 to 4.

6. The application of the high thermal conductivity, low dielectric composite material as described in claim 5 in the preparation of high frequency copper clad laminates for 5G communication.

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