Phenolic resin glue solution, high-thermal-conductivity phenolic copper-clad plate and preparation method of phenolic resin glue solution

Abstract

The invention provides a phenolic resin glue solution, a high-thermal-conductivity phenolic copper-clad plate and a preparation method thereof, and relates to the technical field of copper-clad plates. According to the composite system of the linear phenolic resin and the low-bromine epoxy resin, a high-crosslinking network is formed through the curing agent and the accelerant, and excellent heat resistance and mechanical strength are provided. Meanwhile, the modified polyethersulfone (PES) powder is added to further toughen the glue solution, and nano-silver attached to the surface of the PES powder not only improves the antibacterial property, but also can optimize the interface bonding force, so that the dispersity and thermal conductivity of the glue solution are synergistically enhanced. Furthermore, the heat-conducting filler is preferably compounded from boron nitride (high heat conductivity), graphene nanosheets (ultrahigh heat conductivity, electric conductivity and electric conductivity) and silicon dioxide (dielectric regulation), the dosage is optimized, and a multi-dimensional heat-conducting network is formed: boron nitride and graphene provide efficient heat conduction, and boron nitride and silicon dioxide are compounded to reduce the dielectric constant, so that the heat-conducting property is ensured while the dielectric property is ensured; and the copper-clad plate is especially suitable for high-frequency and high-power scenes.

Description

Technical Field

[0001] This invention relates to the field of copper clad laminate technology, and in particular to a phenolic resin adhesive, a high thermal conductivity phenolic copper clad laminate, and a method for preparing the same. Background Technology

[0002] In the printed circuit board (PCB) manufacturing industry, copper-clad laminates (CCLs) are widely used to provide electrical conductivity and mechanical support. As electronic devices increasingly demand high performance and reliability, the performance requirements for CCLs are also rising. High thermal conductivity and high strength are two key aspects affecting the performance of CCLs.

[0003] Phenolic resins are an ideal substrate for copper-clad laminates due to their excellent insulation properties, mechanical strength, and chemical resistance. However, to meet the higher requirements of modern electronic devices for thermal conductivity and strength, a novel phenolic resin and its preparation method are needed.

[0004] Traditional copper-clad laminates made of phenolic resin have some problems: improving thermal conductivity may reduce the mechanical strength of the resin, or improving mechanical strength may reduce thermal conductivity. In addition, phenolic resin is relatively brittle and is prone to microcracks and / or low peel strength during drilling or thermal cycling. Summary of the Invention

[0005] To address the technical problem that phenolic copper-clad laminates in the prior art are difficult to simultaneously possess high thermal conductivity, mechanical strength, and toughness, this application provides a phenolic resin adhesive, a high thermal conductivity phenolic copper-clad laminate, and a method for preparing the same.

[0006] In a first aspect, this application provides a phenolic resin adhesive, comprising the following components by weight:

[0007] 28-35 parts linear phenolic resin, 8-10 parts phenolic curing agent, 0.06-0.5 parts phenolic accelerator, 23-30 parts epoxy resin, 4-5 parts coupling agent, 60-80 parts thermally conductive filler, 5-20 parts modified polyethersulfone (PES) powder, and 70-90 parts solvent.

[0008] The modified polyethersulfone (PES) powder has 0.1-3 wt% nano-silver adhering to its surface.

[0009] Furthermore, the thermally conductive filler includes any one or a combination of several of the following: silicon dioxide, zinc oxide, aluminum oxide, magnesium oxide, boron nitride, aluminum nitride, and silicon carbide.

[0010] Furthermore, the thermally conductive filler is a composition of boron nitride, graphene nanosheets, and silicon dioxide in a mass ratio of 5-8:0.5-2:0.3-1.

[0011] Furthermore, the silicon dioxide and boron nitride have a particle size of 2-8 μm; the graphene nanosheets have a thickness of 1-10 nm, a lateral dimension of 0.1-50 μm, and a specific surface area of ​​200-400 m² / g.

[0012] Furthermore, the coupling agent is an aminosilane coupling agent, which includes one of 3-aminopropyltriethoxysilane, N-(2-amino-ethyl)-3-aminopropanetriethoxysilane, 3-aminopropanetrimethoxysilane, and N-(2-amino-ethyl)-3-aminopropanetrimethoxysilane.

[0013] Furthermore, the phenolic curing agent is one of dicyandiamide, acid anhydride, or amine phenolic curing agents; the phenolic accelerator is an imidazole phenolic accelerator; the solvent is a ketone organic solvent; and the nano-silver adhering to the surface of the modified polyethersulfone PES powder is less than 3 wt%.

[0014] Secondly, this application provides a method for preparing a phenolic resin adhesive, including the preparation of modified polyethersulfone (PES) powder, comprising the following steps:

[0015] Surface treatment: The polyethersulfone (PES) powder is subjected to plasma treatment and / or chemical treatment to enhance the active groups on the surface of the PES powder;

[0016] Silver ion adsorption: Surface-treated polyethersulfone (PES) powder is impregnated in a silver ion solution with a concentration of 0.5-2 wt% and stirred and dispersed for 1-4 hours at 50-70°C.

[0017] In-situ reduction: A reducing agent is added to the solution obtained in the silver ion adsorption step to carry out reduction. Silver is deposited on the surface of polyethersulfone (PES) powder to form modified PES powder. After centrifugation, washing, and drying, it is ready for use.

[0018] The reducing agent includes one or more of sodium citrate, NaBH4, tannic acid, gallic acid, ethanolamine, and ascorbic acid.

[0019] After mixing the raw materials for phenolic resin solution, the mixture is heated to 55-65℃ and stirred to obtain phenolic resin solution.

[0020] Furthermore, the solution pH in the in-situ reduction step is 7-8.

[0021] Preferably, a method for preparing modified polyethersulfone (PES) powder includes the following preparation steps:

[0022] 1) PES surface activation

[0023] Chemical surface treatment: PES powder (average particle size 10-50 μm) is immersed in a concentrated H2SO4 / HNO3 mixture and treated at room temperature for 1-4 hours to enhance the active groups on the surface, such as -COOH and -OH. Then it is washed until neutral.

[0024] 2) Silver ion adsorption

[0025] Place 10g of the PES powder obtained in step 1) into 50mL of a 0.5-2 wt% AgNO3 aqueous solution, add 0.1-0.5g of PVP (stabilizer), and ultrasonically disperse at 50-70℃ for 1-3 hours to allow the AgNO3 to disperse. + It is fully adsorbed onto the PES surface.

[0026] Step 3: Restore in situ

[0027] Add NaOH solution to the solution obtained in step 2) to adjust the pH to 7-8; then add 8-15 mL of 0.01-0.03 g / mL ascorbic acid aqueous solution dropwise to the solution obtained in the silver ion adsorption step, stir at room temperature (20-40℃) for 0.4-2 hours, and the solution gradually turns gray-black (Ag NPs are generated).

[0028] The solid was washed, centrifuged to separate it, washed again, and vacuum dried to obtain modified polyethersulfone (PES) powder.

[0029] Thirdly, this application provides a method for preparing a high thermal conductivity phenolic copper-clad laminate, comprising the following preparation steps:

[0030] S1. Impregnate fiberglass cloth in the resin solution according to any one of claims 1-6, and then bake at 160-190°C for 5-20 minutes to obtain a semi-cured sheet, controlling the resin content to be 45-55%;

[0031] S2. Take several prepreg sheets, stack them together, cut them, cover them with copper foil on both sides or one side, and hot press them at 190-220℃ for 2-4 hours to obtain a high thermal conductivity phenolic copper-clad laminate.

[0032] Fourthly, this application provides a high thermal conductivity phenolic copper-clad laminate, which is obtained by using the phenolic resin adhesive described in this application, or the phenolic resin adhesive obtained by the method described in this application, or by the preparation method of the high thermal conductivity phenolic copper-clad laminate described in this application.

[0033] Beneficial effects: 1. The composite system of linear phenolic resin and low-bromine epoxy resin in this application forms a highly cross-linked network through curing agent and accelerator, providing excellent heat resistance and mechanical strength; at the same time, the addition of modified polyethersulfone (PES) powder further toughens the adhesive, while the nano silver (0.5-2 wt%) attached to the surface not only improves antibacterial properties, but also optimizes interfacial bonding force, thereby synergistically enhancing the dispersibility and thermal conductivity of the adhesive.

[0034] 2. Furthermore, the thermally conductive filler is preferably a combination of boron nitride (high thermal conductivity), graphene nanosheets (ultra-high thermal, electrical, and conductive conductivity), and silicon dioxide (dielectric modulation), with optimized dosage to form a multi-dimensional thermally conductive network: boron nitride and graphene provide efficient heat conduction, and the combination of boron nitride and silicon dioxide improves the problem of increased dielectric constant after silver modification of graphene nanosheets and polyethersulfone (PES) powder, reducing the dielectric constant. While ensuring insulation, it significantly improves the heat dissipation capacity of copper-clad laminate, which is especially suitable for high-frequency and high-power scenarios.

[0035] 3. Furthermore, the amino groups in the aminosilane coupling agent (such as KH-550) are chemically bonded to the silver in the modified polyethersulfone (PES) powder, effectively reducing the interfacial thermal resistance between the thermally conductive filler and the modified polyethersulfone (PES) powder and the resin matrix, improving the toughness of the adhesive layer, and improving the dispersibility of the filler; ultimately achieving a comprehensive balance of the adhesive in terms of thermal conductivity, mechanical properties, dielectric properties and processability. Detailed Implementation

[0036] To make the technical solution of the present invention clearer, the present invention will be further described in detail below with reference to specific embodiments.

[0037] Preparation Example 1: A method for preparing modified polyethersulfone (PES) powder, comprising the following preparation steps:

[0038] 1) PES surface activation

[0039] Chemical surface treatment: Immerse polyethersulfone (PES) powder (average particle size 10-50 μm) in a concentrated H2SO4 / HNO3 mixture and treat at room temperature for 1-4 hours to enhance the active groups on the surface, such as -COOH and -OH. Then wash until neutral.

[0040] 2) Silver ion adsorption

[0041] Place 10g of the polyethersulfone (PES) powder obtained in step 1) into 50mL of a 0.5-2 wt% AgNO3 aqueous solution, add 0.1-0.5g of PVP (stabilizer), and ultrasonically disperse the powder while stirring at 50-70℃ for 1-3 hours to allow the AgNO3 to disperse. + It is fully adsorbed onto the PES surface.

[0042] 3) In-situ restoration

[0043] Add NaOH solution to the solution obtained in step 2) to adjust the pH to 7-8; then add 8-15 mL of 0.01-0.03 g / mL ascorbic acid aqueous solution dropwise to the solution obtained in the silver ion adsorption step, stir at room temperature (20-40℃) for 0.4-2 hours, and the solution gradually turns gray-black (Ag NPs are generated).

[0044] The solid was washed, centrifuged to separate it, washed again, and vacuum dried to obtain modified polyethersulfone (PES) powder.

[0045] Preparation Example 2: A method for preparing modified polyethersulfone (PES) powder, comprising the following preparation steps:

[0046] 1) PES surface activation

[0047] Chemical surface treatment: PES powder (average particle size 30 μm) was immersed in a concentrated H2SO4 / HNO3 mixture (3:1) and treated at room temperature for 1 hour to enhance the active groups on the surface, such as -COOH and -OH. Then it was washed until neutral.

[0048] 2) Silver ion adsorption

[0049] 10 g of the polyethersulfone (PES) powder obtained in step 1) was placed in 50 mL of a 1 wt% AgNO3 aqueous solution, and 0.1 g of PVP (stabilizer) was added. The mixture was ultrasonically dispersed for 30 minutes and stirred at 60°C for 2 hours to allow the AgNO3 to disperse. + It is fully adsorbed onto the PES surface.

[0050] Step 3: Restore in situ

[0051] Add NaOH solution (0.1 M) to adjust the pH from acidic to 7.5; then add 10 mL of 0.02 g / mL ascorbic acid aqueous solution dropwise to the solution obtained in the silver ion adsorption step, stir at room temperature (25℃) for 1 hour, and the solution gradually turns grayish-black (Ag NPs are generated).

[0052] The solid was washed and centrifuged to separate it. It was washed three times with alternating ethanol and water to remove free Ag NPs. It was then vacuum dried at 60°C for 12 hours to obtain modified polyethersulfone (PES) powder for later use.

[0053] Example 1: A method for preparing a high thermal conductivity phenolic copper-clad laminate, using raw materials as shown in Table 1, including the following preparation steps:

[0054] 1) Add epoxy resin (420g / eq, bromine content 20%wt) and linear phenolic resin (hydroxyl equivalent 260g / eq) to a mixing tank, heat to 65℃ and stir at 300rpm until uniformly mixed. After standing for 20 minutes, add other raw materials and stir at 600rpm until uniformly mixed to obtain phenolic resin solution for later use.

[0055] 2) Preparation of high thermal conductivity phenolic copper clad laminate:

[0056] Impregnate the resin solution obtained in step 2) with E-type glass fiber cloth for 12 minutes, and dry at 180°C for 10 minutes to obtain a semi-cured sheet, with the resin content controlled at 50%.

[0057] Eight prepreg sheets were stacked together, cut, and coated with copper foil on both sides. They were then hot-pressed to obtain a high thermal conductivity phenolic copper-clad laminate. The hot-pressing process involved a pressure of 350 PSI, a temperature of 200℃, and a time of 2 hours.

[0058] In this embodiment, the silica particles have a diameter of 6 μm and the boron nitride particles have a diameter of 8 μm; the graphene nanosheets have a thickness of 5 nm, a lateral dimension of 20 μm, and a specific surface area of ​​300 m² / g.

[0059] Examples 2 and 3 describe a method for preparing a high thermal conductivity phenolic copper-clad laminate, which differs from Example 1 in that the weight and type of raw materials used are different, as detailed in Table 1.

[0060] Table 1. List of raw materials and their weights used in the preparation methods of Examples 1 to 3.

[0061]

[0062] Example 4, a method for preparing a high thermal conductivity phenolic copper clad laminate, differs from Example 1 in that the thermally conductive filler is a composition of boron nitride, graphene nanosheets and silicon dioxide in a mass ratio of 5:1:0.8.

[0063] Example 5, a method for preparing a high thermal conductivity phenolic copper clad laminate, differs from Example 1 in that the thermally conductive filler is a composition of boron nitride, graphene nanosheets and silicon dioxide in a mass ratio of 6:2:1.

[0064] Example 6, a method for preparing a high thermal conductivity phenolic copper clad laminate, differs from Example 1 in that the thermally conductive filler is a composition of boron nitride, graphene nanosheets and silicon dioxide in a mass ratio of 5:2:0.8.

[0065] Example 7, a method for preparing a high thermal conductivity phenolic copper clad laminate, differs from Example 1 in that the thermally conductive filler is a composition of boron nitride and graphene nanosheets in a mass ratio of 5:1.

[0066] Example 8, a method for preparing a high thermal conductivity phenolic copper clad laminate, differs from Example 1 in that the thermally conductive filler is a composition of graphene nanosheets and silicon dioxide with a mass ratio of 5:0.8.

[0067] Example 9, a method for preparing a high thermal conductivity phenolic copper clad laminate, differs from Example 1 in that 3-aminopropyltriethoxysilane is replaced by an equal amount of 3-glycidyl etheroxypropyltrimethoxysilane.

[0068] Comparative Example 1, a method for preparing a high thermal conductivity phenolic copper-clad laminate, differs from Example 1 in that polyethersulfone (PES) powder (average particle size 30 μm) is used to replace the modified PES powder in an equal amount.

[0069] Comparative Example 2, a method for preparing a high thermal conductivity phenolic copper-clad laminate, differs from Example 1 in that modified polyethersulfone (PES) powder is not used.

[0070] Performance testing results are shown in Table 2:

[0071] 1. Glass transition temperature Tg: The Tg of the adhesive used in copper clad laminates was tested in accordance with GB / T 40396-2021.

[0072] 2. Dielectric constant Dk: The dielectric constant (Dk) of the copper-clad laminate sample was tested at a frequency of 10 GHz, in accordance with IPC-TM-6502.5.5.5 and ASTM D790.

[0073] 3. Peel strength: The copper-clad laminate was tested in accordance with GB / T 4722-2017.

[0074] 4. Bending strength: The copper-clad laminate was tested in accordance with GB / T 2567-2021. The bending strength specimen size was 4.0 mm thick, 100 mm long and 15 mm wide. The test speed was 10 mm / min, the number of specimens was 5, the test temperature was 23℃, the relative humidity was 50%, and the specimen conditioning time was 30 h.

[0075] 5. Thermal conductivity: Test reference standard / method: ASTM D5470-2006 standard, using a thermal conductivity meter to test the copper-clad laminate.

[0076] Table 2. Performance list of resin solutions or copper-clad laminates obtained by the preparation methods of Examples 1 to 9 and Comparative Examples 1 to 2.

[0077]

[0078] As can be seen from Table 2:

[0079] In Examples 4-5, the thermally conductive filler was made of boron nitride, graphene nanosheets and silicon dioxide, and the dosage was optimized. The resulting copper-clad laminate had good comprehensive properties such as bending, peeling, thermal conductivity, dielectric and heat resistance.

[0080] Compared to Example 4, Example 6 showed improved bending, peeling, thermal conductivity, and heat resistance, but also increased dielectric constant. This may be because, compared to boron nitride, the graphene nanosheets used in Example 6 have more polar groups on their surface, leading to an increase in dielectric constant.

[0081] Compared to Example 4, Example 7 did not use silica, and the performance of each test item deteriorated, possibly because the lack of silica resulted in poorer dispersibility.

[0082] Compared to Examples 4 and 1, Example 8 uses graphene nanosheets and silicon dioxide with more polar groups on their surface as thermally conductive fillers, resulting in an increase in DK.

[0083] Compared to Example 1, Example 9 shows that the use of 3-glycidyl etheroxypropyltrimethoxysilane as the silane coupling agent resulted in a decrease in the toughness and thermal conductivity of the adhesive layer. This may be due to the deterioration of the interfacial thermal conductivity and the weakening of the interaction force between the thermally conductive filler, the modified polyethersulfone (PES) powder, and the resin matrix.

[0084] The experimental results of Example 1 and Comparative Example 1 show that the use of modified polyethersulfone (PES) powder toughens the adhesive, optimizes the interfacial bonding force, enhances the dispersibility and thermal conductivity of the adhesive, and thus improves the overall performance of the copper clad laminate.

[0085] The experimental results of Example 1 and Comparative Example 2 show that without the use of modified polyethersulfone (PES) powder, the toughness and heat resistance of the adhesive are poor.

[0086] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A phenolic resin adhesive, characterized in that, By weight, it includes the following components: 28-35 parts linear phenolic resin, 8-10 parts phenolic curing agent, 0.06-0.5 parts phenolic accelerator, 23-30 parts epoxy resin, 4-5 parts coupling agent, 60-80 parts thermally conductive filler, 5-20 parts modified polyethersulfone (PES) powder, and 70-90 parts solvent. The modified polyethersulfone (PES) powder has nano-silver adhering to its surface.

2. The phenolic resin adhesive according to claim 1, characterized in that, The thermally conductive filler includes any one or a combination of several of the following: silicon dioxide, zinc oxide, aluminum oxide, magnesium oxide, boron nitride, aluminum nitride, and silicon carbide.

3. The phenolic resin adhesive according to claim 2, characterized in that, The thermally conductive filler is a composition of boron nitride, graphene nanosheets and silicon dioxide in a mass ratio of 5-8:0.5-2:0.3-1.

0.

4. A phenolic resin adhesive according to any one of claims 3, characterized in that, The silicon dioxide and boron nitride have a particle size of 2-8 μm; the graphene nanosheets have a thickness of 1-10 nm, a lateral dimension of 0.1-50 μm, and a specific surface area of ​​200-400 m² / g.

5. A phenolic resin adhesive according to any one of claims 1-4, characterized in that, The coupling agent is an aminosilane coupling agent, which includes one of 3-aminopropyltriethoxysilane, N-(2-amino-ethyl)-3-aminopropanetriethoxysilane, 3-aminopropanetrimethoxysilane, and N-(2-amino-ethyl)-3-aminopropanetrimethoxysilane.

6. The phenolic resin adhesive according to claim 1, characterized in that, The phenolic curing agent is one of dicyandiamide, acid anhydride, or amine phenolic curing agents; the phenolic accelerator is an imidazole phenolic accelerator; the solvent is a ketone organic solvent; and the nano-silver adhering to the surface of the modified polyethersulfone (PES) powder is less than 3 wt%.

7. A method for preparing the phenolic resin adhesive according to any one of claims 1-6, characterized in that, The preparation of modified polyethersulfone (PES) powder includes the following steps: Surface treatment: The polyethersulfone (PES) powder is subjected to plasma treatment and / or chemical treatment to enhance the active groups on the surface of the PES powder; Silver ion adsorption: Surface-treated polyethersulfone (PES) powder is impregnated in a silver ion solution with a concentration of 0.5-2 wt% and stirred and dispersed for 1-4 hours at 50-70℃. In-situ reduction: A reducing agent is added to the solution obtained in the silver ion adsorption step to carry out reduction. Silver is deposited on the surface of polyethersulfone (PES) powder to form modified PES powder. After centrifugation, washing, and drying, it is ready for use. The reducing agent includes one or more of sodium citrate, NaBH4, tannic acid, gallic acid, ethanolamine, and ascorbic acid. After mixing the raw materials for phenolic resin solution, the mixture is heated to 55-65℃ and stirred to obtain phenolic resin solution.

8. A method for preparing the phenolic resin adhesive according to claim 7, characterized in that, The solution pH in the in-situ reduction step is 7-8.

9. A method for preparing a high thermal conductivity phenolic copper-clad laminate, characterized in that, The preparation steps include the following: S1. Impregnate fiberglass cloth with the resin solution according to any one of claims 1-6, or with the resin solution obtained by the method according to claims 7-8, and then bake at 160-190°C for 5-20 minutes to obtain a semi-cured sheet, controlling the resin content to be 45-55%; S2. Take several prepreg sheets, stack them together, cut them, cover them with copper foil on both sides or one side, and hot press them at 190-220℃ for 2-4 hours to obtain a high thermal conductivity phenolic copper-clad laminate.

10. A high thermal conductivity phenolic copper-clad laminate, characterized in that, It is obtained by using the phenolic resin solution according to any one of claims 1-6, or by the preparation method according to claim 9.

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