High-heat-resistance copper-clad plate and preparation method thereof
By preparing waterproof and heat-resistant modified benzoxazine monomers and boron nitride-coated expanded plastic microspheres, the oxidation and peeling problems of polyimide films under high temperature and high humidity conditions were solved, and the high heat resistance, peel strength and thermal conductivity of high heat-resistant copper clad laminates were achieved.
Patent Information
- Application Number
- CN202511245013.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-09-02
- Publication Date
- 2026-01-09
AI Technical Summary
Existing polyimide films are prone to oxidation and reduced peel strength under high temperature and high humidity conditions, and their thermal stability and mechanical strength are insufficient, making it difficult to meet the requirements of high-frequency flexible circuit boards.
Waterproof and heat-resistant modified benzoxazine monomers were prepared by reacting gingerone, 2-amino-5-fluorotrifluorotoluene and paraformaldehyde. The monomers were then vacuum impregnated with porous thermally conductive polyimide films and thermocured. The polyamic acid solution containing boron nitride-coated expanded plastic microspheres was combined to form a waterproof and heat-resistant prepreg, which was then thermopressed to cure copper foil.
It improves the heat resistance, peel strength, and moisture resistance of copper-clad laminates, while enhancing thermal conductivity to meet the high heat resistance requirements of high-frequency flexible circuit boards.
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Abstract
Description
Technical Field
[0001] This invention belongs to the field of copper clad laminate technology, specifically relating to a high heat-resistant copper clad laminate and its preparation method. Background Technology
[0002] In recent years, major breakthroughs in communication technology have been driving electronic communication toward higher transmission frequencies, faster transmission rates, and lower signal delays. As a key basic material in this field, copper clad laminates are crucial for their dielectric properties in high-frequency operating environments. This requires their base resin to have key characteristics such as high heat resistance, excellent bonding strength, and low moisture absorption.
[0003] The representative material of existing base resins is polyimide film, which contains special imide rings in its main chain, giving it outstanding characteristics such as high toughness, low dielectric constant, and low coefficient of thermal expansion. However, it generally suffers from disadvantages such as high curing temperature, difficult processing, and poor water resistance, which leads to problems such as copper foil oxidation and reduced peel strength under high temperature and high humidity working conditions. In order to solve the problem of poor water resistance of polyimide materials, inspired by the extremely low moisture absorption of polyester materials, existing technologies have attempted to introduce ester groups into the main chain of polyimide to obtain polyesterimide materials. However, the introduction of ester groups can easily lead to a decrease in the thermal stability and mechanical strength of the material, making it difficult to apply in high-frequency flexible circuit boards. Summary of the Invention
[0004] To address the aforementioned technical deficiencies, this invention presents a method for preparing a high heat-resistant copper-clad laminate, which exhibits high heat resistance stability, high peel strength, and high water resistance.
[0005] A high heat-resistant copper-clad laminate is characterized by comprising an inner layer of waterproof and heat-resistant prepreg and an outer layer of thermo-cured copper foil. The waterproof and heat-resistant prepreg is prepared by reacting gingerone, 2-amino-5-fluorotrifluorotoluene, and paraformaldehyde to obtain a waterproof and heat-resistant modified benzoxazine monomer, which is dissolved in N,N-dimethylformamide to obtain a waterproof and heat-resistant modified adhesive. A porous thermally conductive polyimide film is then immersed in the waterproof and heat-resistant modified adhesive under vacuum impregnation and thermosetting. Copper foil is then applied to both sides of the obtained waterproof and heat-resistant prepreg, followed by thermosetting to obtain the high heat-resistant copper-clad laminate.
[0006] A method for preparing a high heat-resistant copper-clad laminate includes the following steps: S1: Preparation of porous thermally conductive polyimide films Hydroxylated boron nitride and amino-modified expanded plastic microspheres were added to deionized water and ultrasonically mixed until homogeneous. After standing, the mixture was filtered, washed, and dried to obtain boron nitride-coated expanded plastic microspheres. The boron nitride-coated expanded plastic microspheres were added to N,N-dimethylacetamide, followed by the addition of 4,4'-diaminodiphenyl ether and pyromellitic dianhydride. The mixture was stirred and reacted, and then an imidizing agent was added to imidize the mixture, resulting in an imidized polyamic acid solution. The imidized polyamic acid solution was coated into a liquid film and then thermoset at high temperature to obtain a porous thermally conductive polyimide film. S2: Preparation of Waterproof and Heat-Resistant Prepreg Gingerone, 2-amino-5-fluorotrifluorotoluene, and paraformaldehyde were added to a container and subjected to a high-temperature reflux reaction using a toluene-ethanol mixture as a solvent. The resulting reaction solution was recrystallized, filtered, dried, and ground to obtain a waterproof and heat-resistant modified benzoxazine monomer. The waterproof and heat-resistant modified benzoxazine monomer was dissolved in N,N-dimethylformamide to obtain a waterproof and heat-resistant modified adhesive. A porous thermally conductive polyimide film was immersed in the waterproof and heat-resistant modified adhesive and vacuum impregnated, followed by thermosetting to obtain a waterproof and heat-resistant semi-cured sheet. S3: High heat-resistant copper-clad laminate, thermosetting curing Waterproof and heat-resistant semi-cured sheets are coated with copper foil on both sides and then subjected to hot-press curing to obtain high heat-resistant copper-clad laminate.
[0007] Furthermore, the preparation of the porous thermally conductive polyimide film in step S1 specifically includes the following steps: S1.1: Hexagonal boron nitride powder with a particle size of 1-2 μm was immersed in Piranha solution and stirred at 120-150 rpm for 1-1.5 h. Then, it was taken out, washed and dried thoroughly to obtain hydroxylated boron nitride. Expanded plastic microspheres 180DU25 with a particle size of 20-22 μm were immersed in anhydrous ethanol containing 3-aminopropyltriethoxysilane at 50-55℃. 0.2-0.3 wt% acetic acid was added dropwise and soaked for 4-5 h. After soaking, it was taken out and washed with anhydrous ethanol and deionized water for 4-5 min each. Then, it was dried at 80-85℃ to obtain amino-modified expanded plastic microspheres. S1.2: Add 10-15 parts by weight of hydroxylated boron nitride and 40-50 parts by weight of amino-modified expanded plastic microspheres to 200-250 parts by weight of deionized water, add 0.3-0.5 parts by weight of polyacrylic acid, then add 0.1 mol / L NaOH solution to adjust the pH to 8.5-9, sonicate at a frequency of 35-40 kHz for 10-15 min, let stand for 4-6 hours, filter, take the filter cake, rinse it with deionized water, and then dry it at 70-75℃ to obtain boron nitride-coated expanded plastic microspheres; S1.3: Boron nitride-coated expanded plastic microspheres are placed in N,N-dimethylacetamide and ultrasonically dispersed at a frequency of 30-35kHz. Then, 4,4'-diaminodiphenyl ether and pyromellitic dianhydride are added and stirred until completely dissolved. The mixture is stirred and reacted thoroughly at 40℃ to obtain a polyamic acid solution. The mass concentration of boron nitride-coated expanded plastic microspheres in the polyamic acid solution is 6-8wt%, and the mass concentration of polyamic acid is 35-40wt%. Then, 14-15wt% of imidizing agent is added, and the reaction is continued to obtain an imidized polyamic acid solution. The imidized polyamic acid solution is coated to form a liquid film, dried at 180-200℃, and then heated to 400-415℃ and held for 20-25 min to obtain a porous thermally conductive polyimide film with a thickness of 100-125μm.
[0008] Furthermore, the preparation of the waterproof and heat-resistant semi-cured sheet in step S2 specifically includes the following steps: S2.1: Add gingerone, 2-amino-5-fluorotrifluorotoluene and paraformaldehyde sequentially into a container, then add 3-4 times the mass of toluene-ethanol mixed solution, stir evenly, and reflux at 80-85℃ for 8 hours to obtain a reaction solution. Add excess n-hexane solution to the reaction solution and recrystallize until the solution is clear. Filter the solid, dry it to constant weight, grind it into powder, and obtain a waterproof and heat-resistant modified benzoxazine monomer. S2.2: Dissolve the waterproof and heat-resistant modified benzoxazine monomer in N,N-dimethylformamide at a solid-liquid ratio of 1:(1-1.5) g / mL, and then place it in an oven at 60-65℃ for 10-12 hours to obtain a waterproof and heat-resistant modified adhesive. Immerse a porous thermally conductive polyimide film in the waterproof and heat-resistant modified adhesive and vacuum impregnate it at 200-300 Pa for 35-40 minutes. After removing it, scrape off the excess waterproof and heat-resistant modified adhesive from the surface of the porous thermally conductive polyimide film so that the thickness of the liquid film formed by the waterproof and heat-resistant modified adhesive on the surface of the porous thermally conductive polyimide film is 20-25 μm. Then, heat-treat it at 80℃, 140℃, 180℃ and 220℃ for 1-1.2 hours each to obtain a waterproof and heat-resistant semi-cured sheet.
[0009] Furthermore, in step S1.1, the piranha solution is prepared by mixing hydrogen peroxide and concentrated sulfuric acid in a volume ratio of 1:3.
[0010] Further, in step S1.1, the concentration of 3-aminopropyltriethoxysilane in the anhydrous ethanol containing 3-aminopropyltriethoxysilane is 0.4-0.8 mol / L.
[0011] Furthermore, the imidizing agent in step S1.3 is prepared by mixing acetic anhydride and triethylamine in a molar ratio of 1:(0.8-1).
[0012] Further, in step S2.1, the ratio of the phenolic hydroxyl group in gingerone, the amino group in 2-amino-5-fluorotrifluorotoluene, and the aldehyde group in paraformaldehyde is 1:1:2, and the volume ratio of toluene to ethanol in the toluene-ethanol mixed solution is 1:(0.4-0.6).
[0013] Furthermore, the parameters for hot-press curing in step S3 are 175-180℃ and 8-10MPa pressure for 3-4 hours.
[0014] The beneficial effects are: 1. This invention utilizes gingerone, 2-amino-5-fluorotrifluorotoluene, and paraformaldehyde to prepare a waterproof and heat-resistant modified benzoxazine monomer. Then, a porous thermally conductive polyimide film is filled and modified through monomer polymerization. At this point, the trifluoromethyl group in the waterproof and heat-resistant modified benzoxazine monomer... After polymerization, it is directionally enriched on the coating surface to form a low-energy hydrophobic barrier. At the same time, the strong electronegativity of fluorine atoms (F) further reduces the polarity of the coating and inhibits the penetration of water molecules. Meanwhile, gingerone has flexible segments that can enhance the compactness of molecular chain arrangement and reduce microscopic defects. The cross-linked network formed by ring-opening polymerization can effectively bind the movement of polyimide molecular chains. While retaining the excellent intrinsic properties of polyimide, it endows it with excellent moisture resistance, high temperature resistance and interfacial bonding properties. When preparing copper-clad laminates, it can ensure the heat and water resistance stability of copper-clad laminates.
[0015] 2. This invention involves coating amino-modified expandable plastic microspheres with hydroxylated hexagonal boron nitride powder to obtain boron nitride-coated expandable plastic microspheres. These microspheres are then uniformly dispersed in N,N-dimethylacetamide solvent, and reacted with 4,4'-diaminodiphenyl ether and pyromellitic dianhydride to obtain a polyamic acid solution. The polyamic acid is then imidized using a chemical imidization method, coated into a liquid film, and subjected to high-temperature treatment. During this process, the boron nitride-coated expandable plastic microspheres are uniformly dispersed in the liquid film. The subsequent high-temperature treatment not only removes the water and residual solvent generated during the imidization reaction, but also causes the boron nitride-coated expandable plastic microspheres to expand at high temperatures, forming a uniform foam structure in the liquid film. As the temperature further increases, the expandable plastic microspheres decompose at high temperatures, allowing the boron nitride to embed in the inner wall of the foam structure, forming a uniformly connected thermal conductive pathway. This significantly improves the thermal conductivity of the polyimide film, enabling the resulting copper-clad laminate to dissipate heat better and exhibit high heat resistance.
[0016] 3. This invention prepares a porous thermally conductive polyimide film, which is then immersed in a waterproof and heat-resistant modified adhesive for vacuum impregnation. During the vacuum impregnation process, the waterproof and heat-resistant modified adhesive fills the interior of the porous thermally conductive polyimide film, thereby forming a prepolymer inside. At the same time, the thickness of the liquid film formed by the waterproof and heat-resistant modified adhesive on the surface of the porous thermally conductive polyimide film is controlled, and then the film is gradually heated and cured. When the waterproof and heat-resistant modified adhesive is cured inside the porous thermally conductive polyimide film, it can fully combine with the interior of the polyimide to form a uniform bonding structure, further enhancing the overall thermal stability of the material. Detailed Implementation
[0017] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0018] Example 1 A method for preparing a high heat-resistant copper-clad laminate specifically includes the following steps: S1: Preparation of porous thermally conductive polyimide films S1.1: Hexagonal boron nitride powder with a particle size of 1 μm was immersed in a Piranha solution prepared by hydrogen peroxide and concentrated sulfuric acid in a volume ratio of 1:3 and stirred at 120 rpm for 1 h. Then, it was taken out and thoroughly washed and dried to obtain hydroxylated boron nitride. Expanded plastic microspheres 180DU25 with a particle size of 20 μm were immersed in anhydrous ethanol containing 3-aminopropyltriethoxysilane at 50 °C. The concentration of 3-aminopropyltriethoxysilane was 0.4 mol / L. 0.2 wt% acetic acid was added dropwise. After soaking for 4 h, it was taken out and washed with anhydrous ethanol and deionized water for 4 min each. Then, it was dried at 80 °C to obtain amino-modified expanded plastic microspheres. S1.2: Add 10g of hydroxylated boron nitride and 40g of amino-modified expanded plastic microspheres to 200g of deionized water, add 0.3g of polyacrylic acid, then add 0.1mol / L NaOH solution to adjust the pH to 8.5, sonicate at 35kHz for 10min, let stand for 4 hours, filter, take the filter cake, rinse it with deionized water, and then dry it at 70℃ to obtain boron nitride-coated expanded plastic microspheres; S1.3: Boron nitride-coated expanded plastic microspheres were placed in N,N-dimethylacetamide and ultrasonically dispersed at a frequency of 30kHz. Then, 4,4'-diaminodiphenyl ether and pyromellitic dianhydride were added and stirred until completely dissolved. The mixture was stirred and reacted thoroughly at 40℃ to obtain a polyamic acid solution. The mass concentration of boron nitride-coated expanded plastic microspheres in the polyamic acid solution was 6wt%, and the mass concentration of polyamic acid was 35wt%. Then, 14wt% of an imidizing agent prepared by acetic anhydride and triethylamine in a molar ratio of 1:0.8 was added, and the reaction was continued to obtain an imidized polyamic acid solution. The imidized polyamic acid solution was coated to form a liquid film, dried at 180℃, and then heated to 400℃ and held for 20 min to obtain a porous thermally conductive polyimide film with a thickness of 100μm.
[0019] S2: Preparation of Waterproof and Heat-Resistant Prepreg S2.1: Ginger ketone, 2-amino-5-fluorotrifluorotoluene, and paraformaldehyde were added to a container in sequence. The functional groups of the phenolic hydroxyl group in ginger ketone, the amino group in 2-amino-5-fluorotrifluorotoluene, and the aldehyde group in paraformaldehyde were in the ratio of 1:1:2. Then, a toluene-ethanol mixed solution with a volume ratio of 1:0.4 was added, and the mixture was stirred evenly and refluxed at 80°C for 8 hours to obtain a reaction solution. Excess hexane solution was added to the reaction solution and recrystallized until the solution was clear. The solid was filtered, dried to constant weight, and ground into powder to obtain a waterproof and heat-resistant modified benzoxazine monomer. S2.2: The waterproof and heat-resistant modified benzoxazine monomer was dissolved in N,N-dimethylformamide at a solid-liquid ratio of 1:1 g / mL, and then placed in an oven at 60℃ for 10 h to obtain a waterproof and heat-resistant modified adhesive. The porous thermally conductive polyimide film was immersed in the waterproof and heat-resistant modified adhesive and vacuum impregnated at 200 Pa for 35 min. After removal, the excess waterproof and heat-resistant modified adhesive on the surface of the porous thermally conductive polyimide film was scraped off, so that the thickness of the liquid film formed by the waterproof and heat-resistant modified adhesive on the surface of the porous thermally conductive polyimide film was 20 μm. Then, it was successively heat-treated at 80℃, 140℃, 180℃ and 220℃ for 1 h each to obtain a waterproof and heat-resistant semi-cured sheet.
[0020] S3: High heat-resistant copper-clad laminate, thermosetting curing A waterproof and heat-resistant semi-cured sheet is coated with copper foil on one side, and then hot-pressed and cured at 175℃ and 8MPa for 3 hours to obtain a high heat-resistant copper-clad laminate.
[0021] Example 2 A method for preparing a high heat-resistant copper-clad laminate specifically includes the following steps: S1: Preparation of porous thermally conductive polyimide films S1.1: Hexagonal boron nitride powder with a particle size of 1 μm was immersed in a Piranha solution prepared by hydrogen peroxide and concentrated sulfuric acid in a volume ratio of 1:3 and stirred at 120 rpm for 1 h. Then, it was taken out and thoroughly washed and dried to obtain hydroxylated boron nitride. Expanded plastic microspheres 180DU25 with a particle size of 20 μm were immersed in anhydrous ethanol containing 3-aminopropyltriethoxysilane at 50 °C. The concentration of 3-aminopropyltriethoxysilane was 0.4 mol / L. 0.2 wt% acetic acid was added dropwise. After soaking for 4 h, it was taken out and washed with anhydrous ethanol and deionized water for 4 min each. Then, it was dried at 80 °C to obtain amino-modified expanded plastic microspheres. S1.2: Add 15g of hydroxylated boron nitride and 50g of amino-modified expanded plastic microspheres to 250g of deionized water, add 0.5g of polyacrylic acid, then add 0.1mol / L NaOH solution to adjust the pH to 8.5, sonicate at 35kHz for 10min, let stand for 4 hours, filter, take the filter cake, rinse it with deionized water, and then dry it at 70℃ to obtain boron nitride-coated expanded plastic microspheres; S1.3: Boron nitride-coated expanded plastic microspheres were placed in N,N-dimethylacetamide and ultrasonically dispersed at a frequency of 30 kHz. Then, 4,4'-diaminodiphenyl ether and pyromellitic dianhydride were added and stirred until completely dissolved. The mixture was stirred and reacted thoroughly at 40 °C to obtain a polyamic acid solution. The mass concentration of boron nitride-coated expanded plastic microspheres in the polyamic acid solution was 8 wt%, and the mass concentration of polyamic acid was 40 wt%. Then, 15 wt% of an imidizing agent prepared by acetic anhydride and triethylamine in a 1:1 molar ratio was added, and the reaction was continued to obtain an imidized polyamic acid solution. The imidized polyamic acid solution was coated to form a liquid film, dried at 180 °C, and then heated to 400 °C and held for 20 min to obtain a porous thermally conductive polyimide film with a thickness of 100 μm.
[0022] S2: Preparation of Waterproof and Heat-Resistant Prepreg S2.1: Ginger ketone, 2-amino-5-fluorotrifluorotoluene, and paraformaldehyde were added to a container in sequence. The functional groups of the phenolic hydroxyl group in ginger ketone, the amino group in 2-amino-5-fluorotrifluorotoluene, and the aldehyde group in paraformaldehyde were in the ratio of 1:1:2. Then, a toluene-ethanol mixed solution with a volume ratio of 1:0.4 was added, and the mixture was stirred evenly and refluxed at 80°C for 8 hours to obtain a reaction solution. Excess hexane solution was added to the reaction solution and recrystallized until the solution was clear. The solid was filtered, dried to constant weight, and ground into powder to obtain a waterproof and heat-resistant modified benzoxazine monomer. S2.2: The waterproof and heat-resistant modified benzoxazine monomer was dissolved in N,N-dimethylformamide at a solid-liquid ratio of 1:1.5 g / mL, and then placed in an oven at 60℃ for 10 h to obtain a waterproof and heat-resistant modified adhesive. The porous thermally conductive polyimide film was immersed in the waterproof and heat-resistant modified adhesive and vacuum impregnated at 200 Pa for 35 min. After removal, the excess waterproof and heat-resistant modified adhesive on the surface of the porous thermally conductive polyimide film was scraped off, so that the thickness of the liquid film formed by the waterproof and heat-resistant modified adhesive on the surface of the porous thermally conductive polyimide film was 20 μm. Then, it was successively heat-treated at 80℃, 140℃, 180℃ and 220℃ for 1 h each to obtain a waterproof and heat-resistant semi-cured sheet.
[0023] S3: High heat-resistant copper-clad laminate, thermosetting curing A waterproof and heat-resistant semi-cured sheet is coated with copper foil on one side, and then hot-pressed and cured at 175℃ and 8MPa for 3 hours to obtain a high heat-resistant copper-clad laminate.
[0024] Example 3 A method for preparing a high heat-resistant copper-clad laminate specifically includes the following steps: S1: Preparation of porous thermally conductive polyimide films S1.1: Hexagonal boron nitride powder with a particle size of 2 μm was immersed in a Piranha solution prepared by hydrogen peroxide and concentrated sulfuric acid in a volume ratio of 1:3 and stirred at 150 rpm for 1.5 h. Then, it was taken out, washed and dried thoroughly to obtain hydroxylated boron nitride. Expanded plastic microspheres 180DU25 with a particle size of 22 μm were immersed in anhydrous ethanol containing 3-aminopropyltriethoxysilane at 55 °C. The concentration of 3-aminopropyltriethoxysilane was 0.8 mol / L. 0.3 wt% acetic acid was added dropwise. After soaking for 5 h, it was taken out and washed with anhydrous ethanol and deionized water for 5 min each. Then, it was dried at 85 °C to obtain amino-modified expanded plastic microspheres. S1.2: Add 10g of hydroxylated boron nitride and 40g of amino-modified expanded plastic microspheres to 200g of deionized water, add 0.3g of polyacrylic acid, then add 0.1mol / L NaOH solution to adjust the pH to 9, sonicate at 40kHz for 15min, let stand for 6 hours, filter, take the filter cake, rinse it with deionized water, and dry it at 75℃ to obtain boron nitride-coated expanded plastic microspheres; S1.3: Boron nitride-coated expanded plastic microspheres were placed in N,N-dimethylacetamide and ultrasonically dispersed at a frequency of 35 kHz. Then, 4,4'-diaminodiphenyl ether and pyromellitic dianhydride were added and stirred until completely dissolved. The mixture was stirred and reacted thoroughly at 40 °C to obtain a polyamic acid solution. The mass concentration of boron nitride-coated expanded plastic microspheres in the polyamic acid solution was 6 wt%, and the mass concentration of polyamic acid was 35 wt%. Then, 14 wt% of an imidizing agent prepared by acetic anhydride and triethylamine in a 1:1 molar ratio was added, and the reaction was continued to obtain an imidized polyamic acid solution. The imidized polyamic acid solution was coated to form a liquid film, dried at 200 °C, and then heated to 415 °C and held for 25 min to obtain a porous thermally conductive polyimide film with a thickness of 125 μm.
[0025] S2: Preparation of Waterproof and Heat-Resistant Prepreg S2.1: Ginger ketone, 2-amino-5-fluorotrifluorotoluene, and paraformaldehyde were added to a container in sequence. The functional groups of the phenolic hydroxyl group in ginger ketone, the amino group in 2-amino-5-fluorotrifluorotoluene, and the aldehyde group in paraformaldehyde were in the ratio of 1:1:2. Then, a toluene-ethanol mixed solution with a volume ratio of 1:0.6 was added, and the mixture was stirred evenly and refluxed at 85°C for 8 hours to obtain a reaction solution. Excess n-hexane solution was added to the reaction solution and recrystallized until the solution was clear. The solid was filtered, dried to constant weight, and ground into powder to obtain a waterproof and heat-resistant modified benzoxazine monomer. S2.2: The waterproof and heat-resistant modified benzoxazine monomer was dissolved in N,N-dimethylformamide at a solid-liquid ratio of 1:1 g / mL, and then placed in an oven at 65℃ for 12 h to obtain a waterproof and heat-resistant modified adhesive. The porous thermally conductive polyimide film was immersed in the waterproof and heat-resistant modified adhesive and vacuum impregnated at 300 Pa for 40 min. After removal, the excess waterproof and heat-resistant modified adhesive on the surface of the porous thermally conductive polyimide film was scraped off, so that the thickness of the liquid film formed by the waterproof and heat-resistant modified adhesive on the surface of the porous thermally conductive polyimide film was 25 μm. Then, it was successively heat-treated at 80℃, 140℃, 180℃ and 220℃ for 1.2 h each to obtain a waterproof and heat-resistant semi-cured sheet.
[0026] S3: High heat-resistant copper-clad laminate, thermosetting curing The waterproof and heat-resistant semi-cured sheet is coated with copper foil on one side, and then hot-pressed and cured at 180℃ and 10MPa for 4 hours to obtain a high heat-resistant copper-clad laminate.
[0027] Comparative Example 1 Comparative Example 1 is a commercially available polyimide film.
[0028] Comparative Example 2 The difference from Example 1 is that Comparative Example 2 omits steps S1.1 and S1.2, and replaces the boron nitride-coated expanded plastic microspheres in step S1.3 with 10g of hydroxylated boron nitride and 40g of amino-modified expanded plastic microspheres. All other specific implementation methods are the same as in Example 1.
[0029] The copper-clad laminates prepared in Examples 1-3 and Comparative Example 1 were used as samples. The peel strength and heat resistance (solderability, 288℃) were tested according to GB / T4723-1992 standard. Each sample was tested 3 times, and the average value of the results was taken, as shown in Table 1.
[0030] Table 1: Peel strength and heat resistance of copper clad laminates
[0031] As can be seen from the data in Examples 1-3 in Table 1, the copper-clad laminate prepared in this application has high peel strength and high heat resistance. However, as can be seen from the data in Comparative Example 1, when the porous thermally conductive polyimide film is coated and modified without the addition of waterproof and heat-resistant modified benzoxazine monomer, both peel strength and heat resistance decrease significantly. Furthermore, the preparation of porous thermally conductive polyimide film without the addition of amino-modified expanded plastic microspheres also leads to a decrease in peel strength and heat resistance. This demonstrates that the waterproof and heat-resistant modified benzoxazine monomer can endow it with excellent high-temperature resistance and interfacial bonding properties.
[0032] The copper-clad laminates prepared in Examples 1-3 and Comparative Example 2 were used as samples, and their thermal conductivity was tested according to the standard GB / T4723-1992. Each sample was tested 3 times, and the average value of the results was taken, as shown in Table 2.
[0033] Table 2: Thermal conductivity of copper clad laminates
[0034] As can be seen from the data in Examples 1-3 in Table 2, the copper-clad laminate prepared in this application has high thermal conductivity and excellent heat dissipation performance. However, as can be seen from the data in Comparative Example 2, the thermal conductivity decreases when the amino-modified expanded plastic microspheres are coated with boron nitride powder without hydroxylation and uniformly embedded in the inner wall of the foam structure. This proves that preparing boron nitride-coated expanded plastic microspheres and then foaming polyimide can change the distribution structure of boron nitride in polyimide and improve the thermal conductivity of the polyimide film.
[0035] The semi-cured sheets prepared in Examples 1-3 and Comparative Example 1 were used as samples, and the water absorption rate was tested according to the standard GB / T13557-2017. Each sample was tested 3 times, and the average value of the results was taken, as shown in Table 3.
[0036] Table 3: Water Absorption Rate of Prepregs
[0037] As can be seen from the data of Examples 1-3 in Table 3, the semi-cured sheets prepared in this application have extremely low water absorption. In contrast, Comparative Example 1 did not combine the waterproof and heat-resistant modified benzoxazine monomer with the porous thermally conductive polyimide film, resulting in a significant increase in water absorption. This demonstrates that the waterproof and heat-resistant modified benzoxazine monomer can impart excellent moisture resistance and water resistance to polyimide materials.
[0038] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.
Claims
1. A high heat-resistant copper-clad laminate, characterized in that, The product comprises an inner layer of waterproof and heat-resistant prepreg and an outer layer of thermo-cured copper foil. The waterproof and heat-resistant prepreg is prepared by reacting gingerone, 2-amino-5-fluorotrifluorotoluene, and paraformaldehyde to obtain a waterproof and heat-resistant modified benzoxazine monomer, which is then dissolved in N,N-dimethylformamide to obtain a waterproof and heat-resistant modified adhesive. A porous thermally conductive polyimide film is then immersed in the waterproof and heat-resistant modified adhesive under vacuum impregnation and thermosetting. Finally, copper foil is applied to both sides of the obtained waterproof and heat-resistant prepreg, followed by thermo-curing to obtain a high heat-resistant copper-clad laminate.
2. A method for preparing a high heat-resistant copper-clad laminate according to claim 1, characterized in that, Includes the following steps: S1: Preparation of porous thermally conductive polyimide films Hydroxylated boron nitride and amino-modified expanded plastic microspheres were added to deionized water and ultrasonically mixed until homogeneous. After standing, the mixture was filtered, washed, and dried to obtain boron nitride-coated expanded plastic microspheres. The boron nitride-coated expanded plastic microspheres were added to N,N-dimethylacetamide, followed by the addition of 4,4'-diaminodiphenyl ether and pyromellitic dianhydride. The mixture was stirred and reacted, and then an imidizing agent was added to imidize the mixture, resulting in an imidized polyamic acid solution. The imidized polyamic acid solution was coated into a liquid film and then thermoset at high temperature to obtain a porous thermally conductive polyimide film. S2: Preparation of Waterproof and Heat-Resistant Prepreg Gingerone, 2-amino-5-fluorotrifluorotoluene, and paraformaldehyde were added to a container and subjected to a high-temperature reflux reaction using a toluene-ethanol mixture as a solvent. The resulting reaction solution was recrystallized, filtered, dried, and ground to obtain a waterproof and heat-resistant modified benzoxazine monomer. The waterproof and heat-resistant modified benzoxazine monomer was dissolved in N,N-dimethylformamide to obtain a waterproof and heat-resistant modified adhesive. A porous thermally conductive polyimide film was immersed in the waterproof and heat-resistant modified adhesive and vacuum impregnated, followed by thermosetting to obtain a waterproof and heat-resistant semi-cured sheet. S3: High heat-resistant copper-clad laminate, thermosetting curing Waterproof and heat-resistant semi-cured sheets are coated with copper foil on both sides and then subjected to hot-press curing to obtain high heat-resistant copper-clad laminate.
3. The method for preparing a high heat-resistant copper-clad laminate according to claim 2, characterized in that, Step S1, the preparation of the porous thermally conductive polyimide film, specifically includes the following steps: S1.1: Hexagonal boron nitride powder with a particle size of 1-2 μm was immersed in Piranha solution and stirred at 120-150 rpm for 1-1.5 h. Then, it was taken out, washed and dried thoroughly to obtain hydroxylated boron nitride. Expanded plastic microspheres 180DU25 with a particle size of 20-22 μm were immersed in anhydrous ethanol containing 3-aminopropyltriethoxysilane at 50-55℃. 0.2-0.3 wt% acetic acid was added dropwise and soaked for 4-5 h. After soaking, it was taken out and washed with anhydrous ethanol and deionized water for 4-5 min each. Then, it was dried at 80-85℃ to obtain amino-modified expanded plastic microspheres. S1.2: Add 10-15 parts by weight of hydroxylated boron nitride and 40-50 parts by weight of amino-modified expanded plastic microspheres to 200-250 parts by weight of deionized water, add 0.3-0.5 parts by weight of polyacrylic acid, then add 0.1 mol / L NaOH solution to adjust the pH to 8.5-9, sonicate at a frequency of 35-40 kHz for 10-15 min, let stand for 4-6 hours, filter, take the filter cake, rinse it with deionized water, and then dry it at 70-75℃ to obtain boron nitride-coated expanded plastic microspheres; S1.3: Boron nitride-coated expanded plastic microspheres are placed in N,N-dimethylacetamide and ultrasonically dispersed at a frequency of 30-35kHz. Then, 4,4'-diaminodiphenyl ether and pyromellitic dianhydride are added and stirred until completely dissolved. The mixture is stirred and reacted thoroughly at 40℃ to obtain a polyamic acid solution. The mass concentration of boron nitride-coated expanded plastic microspheres in the polyamic acid solution is 6-8wt%, and the mass concentration of polyamic acid is 35-40wt%. Then, 14-15wt% of imidizing agent is added, and the reaction is continued to obtain an imidized polyamic acid solution. The imidized polyamic acid solution is coated to form a liquid film, dried at 180-200℃, and then heated to 400-415℃ and held for 20-25 min to obtain a porous thermally conductive polyimide film with a thickness of 100-125μm.
4. The method for preparing a high heat-resistant copper-clad laminate according to claim 3, characterized in that, Step S2, the preparation of the waterproof and heat-resistant semi-cured sheet, specifically includes the following steps: S2.1: Add gingerone, 2-amino-5-fluorotrifluorotoluene and paraformaldehyde sequentially into a container, then add 3-4 times the mass of toluene-ethanol mixed solution, stir evenly, and reflux at 80-85℃ for 8 hours to obtain a reaction solution. Add excess n-hexane solution to the reaction solution and recrystallize until the solution is clear. Filter the solid, dry it to constant weight, grind it into powder, and obtain a waterproof and heat-resistant modified benzoxazine monomer. S2.2: Dissolve the waterproof and heat-resistant modified benzoxazine monomer in N,N-dimethylformamide at a solid-liquid ratio of 1:(1-1.5) g / mL, and then place it in an oven at 60-65℃ for 10-12 hours to obtain a waterproof and heat-resistant modified adhesive. Immerse a porous thermally conductive polyimide film in the waterproof and heat-resistant modified adhesive and vacuum impregnate it at 200-300 Pa for 35-40 minutes. After removing it, scrape off the excess waterproof and heat-resistant modified adhesive from the surface of the porous thermally conductive polyimide film so that the thickness of the liquid film formed by the waterproof and heat-resistant modified adhesive on the surface of the porous thermally conductive polyimide film is 20-25 μm. Then, heat-treat it at 80℃, 140℃, 180℃ and 220℃ for 1-1.2 hours each to obtain a waterproof and heat-resistant semi-cured sheet.
5. The method for preparing a high heat-resistant copper-clad laminate according to claim 3, characterized in that, In step S1.1, the piranha solution is prepared by mixing hydrogen peroxide and concentrated sulfuric acid in a volume ratio of 1:
3.
6. The method for preparing a high heat-resistant copper-clad laminate according to claim 3, characterized in that, In step S1.1, the concentration of 3-aminopropyltriethoxysilane in anhydrous ethanol is 0.4-0.8 mol / L.
7. The method for preparing a high heat-resistant copper-clad laminate according to claim 3, characterized in that, The imidizing agent in step S1.3 is prepared by mixing acetic anhydride and triethylamine in a molar ratio of 1:(0.8-1).
8. The method for preparing a high heat-resistant copper-clad laminate according to claim 4, characterized in that, In step S2.1, the ratio of the phenolic hydroxyl group in gingerone, the amino group in 2-amino-5-fluorotrifluorotoluene, and the aldehyde group in paraformaldehyde is 1:1:2, and the volume ratio of toluene to ethanol in the toluene-ethanol mixed solution is 1:(0.4-0.6).
9. The method for preparing a high heat-resistant copper-clad laminate according to claim 2, characterized in that, In step S3, the parameters for hot-press curing are 175-180℃ and 8-10MPa pressure for 3-4 hours.