An epoxy resin prepreg, adhesive film, copper foil substrate, and method for preparing a prepreg

Abstract

The present application relates to the technical field of printed circuit board, and particularly relates to an epoxy resin prepreg, adhesive film, copper foil substrate and a preparation method of the prepreg. The epoxy resin prepreg comprises an epoxy resin polymer glue solution, and the preparation method of the epoxy resin polymer glue solution is as follows: a premix is obtained by first stirring an epoxy resin, a small-molecule anhydride curing agent and an accelerator; the weight ratio of the epoxy resin, the anhydride curing agent and the accelerator is 100:50-100:1-3; ethyl acetate is added to the premix, and second stirring reaction is carried out at 40-80 DEG C for 4-24 hours, and the molecular weight of the epoxy resin polymer glue solution is controlled to be 6000-15000. The prepared epoxy resin prepreg has good heat resistance, a high Tg value and good electrical properties, is suitable for manufacturing semi-cured adhesive film and copper foil substrate, and can be applied to printed circuit boards in general or high-frequency fields.

Description

Technical Field

[0001] This invention relates to the field of printed circuit board technology, specifically to an epoxy resin prepreg, adhesive film, copper foil substrate, and a method for preparing the prepreg. Background Technology

[0002] Epoxy resin-based prepregs are crucial adhesive materials in copper foil substrate manufacturing due to their excellent insulation, processability, and strong adhesion to reinforcing materials and copper foil. With the rapid development of industries such as 5G communications, data centers, and automotive electronics, the market demand for high-frequency copper foil substrates is constantly increasing. To meet the performance requirements of high-frequency applications, new demands are placed on the performance of epoxy resins. The prepared copper foil substrates must have a Dk value ≤ 4.2 and a Df value ≤ 0.015 at 1 GHz, and the material must also possess high glass transition temperature and heat resistance.

[0003] Epoxy and phenolic resin curing systems have high glass transition temperatures but poor dielectric properties. To improve the dielectric properties of epoxy resins, existing dielectric loss epoxy resin systems mainly include phenolic reactive ester-epoxy resin curing copolymers, cyanate ester-epoxy resin-styrene-maleic anhydride multi-component curing copolymers, and benzoxazine-phenolic resin-epoxy resin-styrene-maleic anhydride multi-component curing copolymers. Among these, phenolic reactive ester-epoxy resin curing copolymers undergo transesterification, resulting in high material costs and low glass transition temperatures. Cyanate ester-epoxy resin-styrene-maleic anhydride multi-component curing copolymers are also costly, and cyanate esters easily generate aryl imine carbonates during curing, leading to poor moisture absorption and heat resistance. Benzoxazine-phenolic resin-epoxy resin-styrene-maleic anhydride multi-component curing copolymers have poor compatibility. Summary of the Invention

[0004] In view of the shortcomings of the prior art, the purpose of this invention is to provide an epoxy resin prepreg, a film, a copper foil substrate, and a method for preparing the prepreg. The epoxy resin prepreg prepared by this invention meets the requirements of Dk value ≤ 4.2 and Df ≤ 0.015, and also has good heat resistance and a high Tg value.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] According to one aspect of the present invention, an epoxy resin prepreg is provided, comprising an epoxy resin polymer solution, wherein the epoxy resin polymer solution is prepared by:

[0007] An epoxy resin, a small molecule acid anhydride curing agent, and an accelerator are first stirred to obtain a premix; the weight ratio of the epoxy resin, the small molecule acid anhydride curing agent, and the accelerator is 100:90 to 100:1 to 3.

[0008] Ethyl acetate was added to the premix, and a second stirring reaction was carried out at 40℃~80℃ for 4h~24h, controlling the molecular weight of the epoxy resin polymer solution to be 6000~15000.

[0009] The reaction mechanism for preparing epoxy resin polymer solutions is as follows:

[0010] The anhydride group on phthalic anhydride reacts with the hydroxyl group on epoxy resin first in a monoester reaction, opening the anhydride group to form a monoester bond with a monocarboxylic acid; the monocarboxylic acid after the anhydride group is opened reacts with the epoxy group to form an ester bond with a hydroxyl group (hydroxy ester).

[0011]

[0012] This invention involves mixing epoxy resin, a small-molecule anhydride curing agent, and an accelerator in a specific ratio, followed by esterification and etherification reactions in the presence of ethyl acetate. By controlling the reaction conditions, an epoxy resin with a specific molecular weight and narrow distribution is obtained. This preparation process increases the crosslinking density of the material, reduces the formation of secondary hydroxyl groups, and lowers the Dk and Df values ​​of the material. Simultaneously, it exhibits good heat resistance and a high Tg value, resulting in excellent overall performance. It is suitable for fabricating semi-cured films and copper foil substrates, meeting the material requirements of printed circuit boards in high-frequency applications.

[0013] This invention adds ethyl acetate to the premix. On the one hand, ethyl acetate can control the esterification and etherification process of epoxy resin in the above reaction system, which is beneficial to obtaining epoxy resin polymer liquid with a certain molecular weight and a narrow molecular weight distribution. In this invention, the selection of reaction conditions is very critical. The reaction temperature selected in this invention is 40℃~80℃. If the reaction temperature is too low, the prepolymerization process of the above system will basically not occur. If the reaction temperature is too high, the epoxy resin will be cured in a short time. On the other hand, the addition of ethyl acetate to the reaction system of this invention can dilute the viscosity, which is beneficial to the subsequent glass fiber impregnation process.

[0014] According to a further technical solution, the epoxy equivalent of the epoxy resin is 100 to 200;

[0015] Preferably, the epoxy resin is selected from at least one of bisphenol A epoxy resin and alicyclic epoxy resin;

[0016] Preferably, the epoxy resin comprises 65% to 75% bisphenol A epoxy resin and 25% to 35% alicyclic epoxy resin.

[0017] According to a further technical solution, the first stirring uses a stirring speed of 300 rpm to 600 rpm. Using a higher stirring speed facilitates thorough mixing and dispersion of the epoxy resin, small molecule anhydride curing agent, and accelerator, improving dispersion efficiency. The second stirring uses a stirring speed of 50 rpm to 100 rpm. After the first stirring process, thorough mixing of the epoxy resin, small molecule anhydride curing agent, and accelerator has been achieved. After adding ethyl acetate, using a stirring speed of 50 rpm to 100 rpm ensures uniform mixing of the materials and avoids excessively rapid stirring, which could adversely affect the formation of the epoxy resin polymer.

[0018] According to a further technical solution, the small molecule anhydride curing agent is selected from at least one of tetrahydrophthalic anhydride and methylhexahydrophthalic anhydride.

[0019] According to a further technical solution, the accelerator is selected from at least one of dimethylimidazole, diphenylimidazole, 2-ethyl-4-methylimidazole, and 4-dimethylaminopyridine. The use of the above-mentioned accelerator can catalyze the epoxy functional group reaction, which is beneficial to the cross-linking reaction.

[0020] According to a further technical solution, the ethyl acetate is 30% to 50% of the weight of the epoxy resin polymer solution;

[0021] Preferably, the ethyl acetate is 35% to 45% of the weight of the epoxy resin polymer solution.

[0022] According to a further technical solution, the molecular weight of the epoxy resin polymer solution is 6000-13000.

[0023] According to a further technical solution, the prepreg further includes filler, wherein the filler comprises 20% to 40% of the epoxy resin polymer liquid by weight;

[0024] Preferably, the filler is selected from at least one of organic fillers and inorganic fillers;

[0025] Preferably, the inorganic filler is selected from at least one of crystalline silica, fused silica, spherical silica, and hollow silica. The organic filler may be selected from one or more of polytetrafluoroethylene powder, polyphenylene sulfide, and polyethersulfone powder.

[0026] According to a further technical solution, the particle size of the filler is 0.01μm to 50μm;

[0027] Preferably, the particle size of the filler is 0.01 μm to 20 μm;

[0028] Preferably, the particle size of the filler is 0.01 μm to 10 μm.

[0029] If necessary, this invention may also contain flame retardants to provide the cured resin with flame-retardant properties, meeting UL94V-0 requirements. There are no particular limitations on the flame retardants added as needed; they can be bromine-containing or halogen-free flame retardants, halogenated flame retardants, silicone-containing flame retardants, nitrogen-containing flame retardants, etc., preferably without affecting dielectric properties. Optional commercial materials include bromine-based flame retardants such as Albemarle's BT-93, BT-93W, HP-8010, and HP-3010; and halogen-free flame retardants such as SP-100, PX-200, PX-202, FR-700, OP-930, and OP-935. The amount of flame retardant used depends on achieving the UL94V-0 level requirement of the cured product and is not particularly limited.

[0030] According to another aspect of the present invention, a method for preparing the above-mentioned epoxy resin prepreg is provided, wherein the filler is added to the epoxy resin polymer solution and mixed evenly.

[0031] According to another aspect of the present invention, a semi-cured adhesive film is provided, wherein the semi-cured adhesive film is obtained by impregnating the reinforcing material in the above-mentioned epoxy resin prepreg, controlling the amount of adhesive to be 45% to 55%, and drying to remove the solvent.

[0032] According to another aspect of the present invention, a copper foil substrate is provided, wherein the copper foil substrate is obtained by laminating the above-mentioned semi-cured adhesive film with copper foil and then hot-pressing and curing it;

[0033] Preferably, the hot-press curing temperature is 80℃~250℃, and the curing pressure is 8Kg / cm. 2 ~60Kg / cm 2 .

[0034] Compared with existing technologies, the beneficial effects of this invention are as follows: This invention mixes epoxy resin, small molecule anhydride curing agent, and accelerator in a certain proportion, and carries out esterification and etherification reactions in the presence of ethyl acetate. By controlling the reaction conditions, an epoxy resin with a certain molecular weight and narrow distribution is obtained. The above preparation process can increase the crosslinking density of the material, reduce the formation of secondary hydroxyl groups, and lower the Dk and Df values ​​of the material. It also possesses good heat resistance and a high Tg value, resulting in excellent overall performance. It is suitable for making semi-cured films and copper foil substrates, and can meet the material requirements of printed circuit boards in high-frequency applications. Attached Figure Description

[0035] Figure 1 The infrared spectrum of the epoxy resin prepreg obtained in Example 1;

[0036] Figure 2 The image shows the infrared spectrum of the epoxy resin adhesive obtained in Comparative Example 1. Detailed Implementation

[0037] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. 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.

[0038] The raw materials used in the following embodiments and comparative examples of the present invention are as follows:

[0039] Bisphenol A type epoxy resin (supplier: Nan Ya Plastics, Taiwan; model: NPEL-128; epoxy equivalent: 187);

[0040] Phenolic resin (supplier: Nan Ya Plastics, Taiwan; model: NPEH-710HA65; hydroxyl equivalent: 100);

[0041] The alicyclic epoxy resin is 3,4-epoxycyclohexyl carboxylate (supplier: Tetel; model: TTA-21; molecular weight: 252.31).

[0042] Tetrahydrophthalic anhydride (Supplier: Puyang Huicheng; Model: B1001; Molecular weight: 152.16);

[0043] Methylhexahydrophthalic anhydride (Supplier: Puyang Huicheng; Model: B1013; Molecular weight: 168.19);

[0044] Accelerator dimethylimidazole (supplier: Shikoku Kasei; model: 2-PI; molecular weight: 82.10);

[0045] 99% high-purity silica (supplier: Jiangsu Lianrui; model: NF-2038A; average particle size: 3μm);

[0046] Ethyl acetate (supplier: Sigma Aldrich; boiling point: 77°C);

[0047] Fiberglass cloth (supplier: Nan Ya Plastics, Taiwan; model: 2116; treatment agent: I-700W);

[0048] Reverse copper foil (supplier: Nan Ya Plastics, Taiwan; model: KSHD; thickness: 18μm);

[0049] Unless otherwise specified, all methods described herein are conventional methods, and all raw materials described herein are available from publicly available commercial sources.

[0050] Example 1

[0051] 100g of bisphenol A type epoxy resin, 100g of tetrahydrophthalic anhydride, and 2g of accelerator were placed in a mixing tank and stirred at 500 rpm for 15 minutes to ensure uniform mixing. The mixture was then heated to 50°C and ethyl acetate was added. The mixture was dispersed and stirred at 80 rpm for 6 hours until the materials were uniformly mixed to form epoxy resin prepreg A (ethyl acetate comprised 40% of the weight of epoxy resin prepreg A). Epoxy resin prepreg A was then poured into a glue container and evenly coated onto 2116 glass fiber cloth, maintaining a glue content of 50%. The mixture was then placed in an oven and baked at 170°C for 3 minutes to evaporate the solvent and form a semi-cured film.

[0052] Two semi-cured adhesive films are stacked together with copper coating on both sides and then fed into a hot press at 170℃ and 30Kg / cm². 2 Curing time was 60 minutes, and samples were taken for testing after curing.

[0053] Example 2

[0054] 70g of bisphenol A epoxy resin, 30g of alicyclic epoxy resin, 100g of tetrahydrophthalic anhydride, and 2g of accelerator were placed in a mixing tank and stirred at 500rpm for 15 minutes to ensure uniform mixing. The mixture was then heated to 50℃ and ethyl acetate was added. The mixture was then dispersed and stirred at 80rpm for 6 hours until the materials were uniformly mixed to form epoxy resin prepreg B (ethyl acetate comprised 40% of the weight of epoxy resin prepreg B). Epoxy resin prepreg B was then poured into a glue container and evenly coated onto 2116 glass fiber cloth, maintaining a glue content of 50%. The mixture was then placed in an oven and baked at 170℃ for 3 minutes to evaporate the solvent and form a semi-cured film.

[0055] Two semi-cured adhesive films are stacked together with copper coating on both sides and then fed into a hot press at 170℃ and 30Kg / cm². 2 Curing time was 60 minutes, and samples were taken for testing after curing.

[0056] Example 3

[0057] 70g of bisphenol A epoxy resin, 30g of alicyclic epoxy resin, 100g of methylhexahydrophthalic anhydride, and 2g of accelerator were placed in a mixing tank and stirred at 500rpm for 15 minutes to ensure uniform mixing. The mixture was then heated to 50℃ and ethyl acetate was added. The mixture was then dispersed and stirred at 80rpm for 6 hours until the materials were uniformly mixed to form epoxy resin prepreg C (ethyl acetate comprised 40% of the weight of epoxy resin prepreg C). Epoxy resin prepreg C was then poured into a glue container and evenly coated onto 2116 glass fiber cloth, maintaining a glue content of 50%. The mixture was then placed in an oven and baked at 170℃ for 3 minutes to evaporate the solvent and form a semi-cured film.

[0058] Two semi-cured adhesive films are stacked together with copper coating on both sides and then fed into a hot press at 170℃ and 30Kg / cm². 2Curing time was 60 minutes, and samples were taken for testing after curing.

[0059] Example 4

[0060] Take 100g of epoxy resin prepreg A (preparation method is the same as in Example 1), add 35g of filler to it, mix and stir evenly, pour the epoxy resin prepreg into the glue basin, coat it evenly on 2116 glass fiber cloth, and control the glue content to 50% before sending it into the oven. Bake at 170℃ for 3 minutes to evaporate the solvent and form a semi-cured glue film.

[0061] Two semi-cured adhesive films are stacked together with copper coating on both sides and then fed into a hot press at 170℃ and 30Kg / cm². 2 Curing time was 60 minutes, and samples were taken for testing after curing.

[0062] Example 5

[0063] Take 100g of epoxy resin prepreg B (preparation method is the same as in Example 2), add 35g of filler to it, mix and stir evenly, pour the epoxy resin prepreg into the glue basin and evenly coat it on 2116 glass fiber cloth, and control the glue content to 50% before sending it into the oven and drying at 170℃ for 3 minutes to evaporate the solvent and form a semi-cured glue film.

[0064] Two semi-cured adhesive films are stacked together with copper coating on both sides and then fed into a hot press at 170℃ and 30Kg / cm². 2 Curing time was 60 minutes, and samples were taken for testing after curing.

[0065] Example 6

[0066] Take 100g of epoxy resin prepreg C (preparation method is the same as in Example 3), add 35g of filler to it, mix and stir evenly, pour the epoxy resin prepreg into the glue basin and evenly coat it on 2116 glass fiber cloth, and control the glue content to 50% before sending it into the oven and drying at 170℃ for 3 minutes to evaporate the solvent and form a semi-cured glue film.

[0067] Two semi-cured adhesive films are stacked together with copper coating on both sides and then fed into a hot press at 170℃ and 30Kg / cm². 2 Curing time was 60 minutes, and samples were taken for testing after curing.

[0068] Comparative Example 1

[0069] Add 70g of bisphenol A epoxy resin, 30g of alicyclic epoxy resin, 100g of methylhexahydrophthalic anhydride, and 2g of accelerator to a mixing tank. Stir at 500rpm for 15 minutes to ensure uniform mixing. Then, disperse and stir at 80rpm for 6 hours until the materials are uniformly mixed. Pour the adhesive into a glue container and evenly coat it onto 2116 fiberglass cloth, controlling the adhesive content to 50%. Place the container in an oven and bake at 170℃ for 3 minutes to evaporate the solvent and form a semi-cured adhesive film.

[0070] Two semi-cured adhesive films are stacked together with copper coating on both sides and then fed into a hot press at 170℃ and 30Kg / cm². 2 Curing time was 60 minutes, and samples were taken for testing after curing.

[0071] Comparative Example 2

[0072] Add 70g of bisphenol A type epoxy resin, 30g of alicyclic epoxy resin, 100g of tetrahydrophthalic anhydride, and 2g of accelerator to a mixing tank. Stir at 500rpm until homogeneous, then disperse and stir at 80rpm for 6 hours until the materials are thoroughly mixed. Pour the adhesive into a glue container and evenly coat it onto 2116 fiberglass cloth, controlling the adhesive content to 50%. Place the container in an oven and bake at 170℃ for 3 minutes to evaporate the solvent and form a semi-cured adhesive film.

[0073] Two semi-cured adhesive films are stacked together with copper coating on both sides and then fed into a hot press at 170℃ and 30Kg / cm². 2 Curing time was 60 minutes, and samples were taken for testing after curing.

[0074] Comparative Example 3

[0075] 70g of bisphenol A epoxy resin, 30g of alicyclic epoxy resin, 100g of tetrahydrophthalic anhydride, and 2g of accelerator were placed in a mixing tank and stirred at 500rpm for 15 minutes to ensure uniform mixing. The mixture was then dispersed and stirred at 80rpm for 6 hours at a set temperature of 40℃ until the materials were uniformly mixed. The adhesive was then poured into a glue container and evenly coated onto 2116 fiberglass cloth, maintaining an adhesive content of 50%. The cloth was then placed in an oven and baked at 170℃ for 3 minutes to evaporate the solvent and form a semi-cured film.

[0076] Two semi-cured adhesive films are stacked together with copper coating on both sides and then fed into a hot press at 170℃ and 30Kg / cm². 2 Curing time was 60 minutes, and samples were taken for testing after curing.

[0077] Comparative Example 4

[0078] 70g of bisphenol A epoxy resin, 30g of alicyclic epoxy resin, 100g of methylhexahydrophthalic anhydride, and 2g of accelerator were placed in a mixing tank and stirred at 500rpm for 15 minutes to ensure uniform mixing. The mixture was then stirred at 80rpm for 6 hours at a set temperature of 40℃ until the materials were thoroughly mixed. The adhesive was then poured into a glue container and evenly coated onto 2116 fiberglass cloth, maintaining an adhesive content of 50%. The cloth was then placed in an oven and baked at 170℃ for 3 minutes to evaporate the solvent and form a semi-cured film.

[0079] Two semi-cured adhesive films are stacked together with copper coating on both sides and then fed into a hot press at 170℃ and 30Kg / cm². 2 Curing time was 60 minutes, and samples were taken for testing after curing.

[0080] Comparative Example 5

[0081] 70g of bisphenol A epoxy resin, 30g of alicyclic epoxy resin, 100g of tetrahydrophthalic anhydride, and 2g of accelerator were placed in a mixing tank and stirred at 500rpm for 15 minutes to ensure uniform mixing. The mixture was then dispersed and stirred at 80rpm for 6 hours at 50℃ until homogeneous. After the reaction was complete and cooled to room temperature, ethyl acetate was added and stirred until homogeneous. The adhesive was then poured into a glue container and evenly coated onto 2116 fiberglass cloth, maintaining an adhesive content of 50%. The mixture was then placed in an oven to evaporate the solvent and form a semi-cured film.

[0082] Two semi-cured adhesive films were stacked with copper coating on both sides and then placed in a hot press for curing. After curing, samples were taken for testing.

[0083] Comparative Example 6

[0084] 100g of bisphenol A epoxy resin, 82g of phenolic resin, and 2g of accelerator were placed in a mixing tank and stirred at 500rpm for 15 minutes to ensure uniform mixing. Ethyl acetate was then added at room temperature and the mixture was dispersed and stirred at 80rpm for 6 hours until the materials were uniformly mixed to form an adhesive. The adhesive was then poured into a glue container and evenly coated onto 2116 fiberglass cloth, maintaining an adhesive content of 50%. The cloth was then placed in an oven and baked at 170℃ for 3 minutes to evaporate the solvent and form a semi-cured adhesive film.

[0085] Two semi-cured adhesive films are stacked together with copper coating on both sides and then fed into a hot press at 170℃ and 30Kg / cm². 2 Curing time was 60 minutes, and samples were taken for testing after curing.

[0086] Comparative Example 7

[0087] 100g of bisphenol A epoxy resin, 82g of phenolic resin, 61g of filler, and 2g of accelerator were placed in a mixing tank and stirred at 500rpm for 15 minutes to ensure uniform mixing. Ethyl acetate was then added at room temperature and the mixture was dispersed and stirred at 80rpm for 6 hours until the materials were uniformly mixed to form an adhesive. The adhesive was then poured into a glue container and evenly coated onto 2116 fiberglass cloth, maintaining an adhesive content of 50%. The cloth was then placed in an oven and baked at 170℃ for 3 minutes to evaporate the solvent and form a semi-cured adhesive film.

[0088] Two semi-cured adhesive films are stacked together with copper coating on both sides and then fed into a hot press at 170℃ and 30Kg / cm². 2 Curing time was 60 minutes, and samples were taken for testing after curing.

[0089] Infrared spectroscopy was performed on the epoxy resin prepreg in Example 1 and the epoxy resin adhesive in Comparative Example 1 to detect the epoxy resin prepreg in Example 1. Figure 1 and Figure 2 It can be seen that the epoxy resin premix prepared in Example 1 shows 1720 ester bonds after curing reaction, while in Comparative Example 1, unreacted C=O bonds are found in 1860 acid anhydride and 1780 acid anhydride. This indicates that the epoxy resin under the conditions of Example 1 underwent a prepolymerization reaction, while no prepolymerization reaction occurred under the conditions of Comparative Example 1.

[0090] The epoxy resin prepreg / semi-cured film / copper foil substrate prepared in the above embodiments and comparative examples were tested, wherein (1) to (4) were tested using copper foil substrate, (5) were tested using epoxy resin prepreg, and (6) were tested using semi-cured film. The specific test methods are as follows:

[0091] (1) The DSC-Tg test shall be performed in accordance with the method specified in IPC-TM650 2.4.25C;

[0092] (2) The testing of T-288 (containing copper) shall be carried out in accordance with the method specified in IPC-TM650 2.4.24.1;

[0093] (3) The DK@1GHz test shall be performed in accordance with the method specified in IPC-TM-650 2.5.5.15;

[0094] (4) The Df@1GHz test shall be performed in accordance with the method specified in IPC-TM-650 2.5.5.15;

[0095] (5) The degree of polymerization (molecular weight) of GPC was tested using a gel permeation chromatography instrument, brand Waters, with THF as the mobile phase and a concentration of 0.275%;

[0096] (6) The test method and conditions for tackiness are as follows: at room temperature of 23℃ / RH60%, two semi-cured adhesive films are bonded together and then separated. If they do not come off, they are judged to be non-tacky; if they come off after separation, they are judged to be tacky / very tacky.

[0097] The performance test results of samples from Examples 1 to 6 are shown in Table 1, and the performance test results of samples from Comparative Examples 1 to 7 are shown in Table 2 below:

[0098] Table 1: Performance test results of samples from Examples 1 to 6

[0099]

[0100] Table 2: Performance test results of Comparative Examples 1–7

[0101]

[0102] Combining Examples 1 and 2, the results show that selecting alicyclic epoxy resin and bisphenol A epoxy resin to compound can increase the Tg value of epoxy resin prepreg, and reduce Dk and Df. The overall performance of Example 2 is better than that of Example 1.

[0103] Combined with Examples 1, 2, 4 and 5, the results show that the Dk of the prepared epoxy resin prepreg is increased by the filler. While meeting the Dk requirement, Df decreases after the addition of filler, and the Tg value increases.

[0104] Combining Examples 3 and 6, the results show that using methylhexahydrophthalic anhydride as a curing agent can achieve similar effects, but the Tg value is slightly lower than that of epoxy resin prepreg prepared using tetrahydrophthalic anhydride as a curing agent.

[0105] Combining Examples 2-3 and Comparative Examples 1-2, the results show that in the absence of a prepolymerization reaction, the semi-cured adhesive film of Comparative Examples 1-2 exhibits a very sticky feel, and Tg and T-288 decrease significantly, with poor dielectric properties. This indicates that the method of Examples 2-3 of this application, by first preparing epoxy resin prepreg, can significantly improve the various properties of the samples.

[0106] Combined with Examples 2-3 and Comparative Examples 3-4, the results show that, without the addition of ethyl acetate as a solvent and at a low reaction temperature, and with insufficient prepolymerization, the GPC samples of Comparative Examples 3-4 have a low degree of polymerization, the semi-cured film still exhibits stickiness, Tg and T-288 decrease significantly, and the dielectric properties are also poor.

[0107] Combining Example 2 and Comparative Example 5, the results show that without the addition of ethyl acetate during the prepolymerization process, the semi-cured film of Comparative Example 5 exhibits a sticky texture, the GPC of the sample has a wide molecular weight distribution of polymerization degree, Tg and T-288 are significantly reduced, and the dielectric properties are also poor.

[0108] Combined with Examples 1-6 and Comparative Examples 6-7, the results show that the epoxy resin prepregs prepared in Examples 2, 3, 5 and 6 of the present invention can achieve the same effect as the Tg values ​​of the adhesives in Comparative Examples 6-7. The T-288, Df and Dk values ​​of the epoxy resin prepregs prepared in Examples 1-6 are significantly better than those in Comparative Examples 6-7.

[0109] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application and not to limit them; although this application has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications can still be made to the specific implementation of this application or equivalent substitutions can be made to some technical features, all of which should be covered within the scope of the technical solutions claimed in this application.

Claims

1. An epoxy resin prepreg, characterized in that, The epoxy resin polymer adhesive includes an epoxy resin polymer solution, and the preparation method of the epoxy resin polymer adhesive is as follows: An epoxy resin, a small molecule acid anhydride curing agent, and an accelerator are first stirred to obtain a premix; the weight ratio of the epoxy resin, the small molecule acid anhydride curing agent, and the accelerator is 100:90 to 100:1 to 3. Ethyl acetate was added to the premix, and a second stirring reaction was carried out at 40℃~80℃ for 4h~24h, controlling the molecular weight of the epoxy resin polymer solution to be 6000~15000.

2. The epoxy resin prepreg according to claim 1, characterized in that, The epoxy equivalent of the epoxy resin is 100 to 200.

3. An epoxy resin prepreg according to claim 2, characterized in that, The epoxy resin is selected from at least one of bisphenol A epoxy resin and alicyclic epoxy resin.

4. The epoxy resin prepreg according to claim 2, characterized in that, The epoxy resin comprises 65% to 75% bisphenol A epoxy resin and 25% to 35% alicyclic epoxy resin.

5. The epoxy resin prepreg according to claim 1, characterized in that, The first stirring is carried out at a stirring speed of 300 rpm to 600 rpm; The second stirring is carried out at a stirring speed of 50 rpm to 100 rpm.

6. The epoxy resin prepreg according to claim 1, characterized in that, The small molecule anhydride curing agent is selected from at least one of tetrahydrophthalic anhydride and methylhexahydrophthalic anhydride; And / or the promoter is selected from at least one of dimethylimidazole, diphenylimidazole, 2-ethyl-4-methylimidazole, and 4-dimethylaminopyridine.

7. The epoxy resin prepreg according to claim 1, characterized in that, The ethyl acetate is 30% to 50% of the weight of the epoxy resin polymer solution.

8. The epoxy resin prepreg according to claim 7, characterized in that, The ethyl acetate is 35% to 45% of the weight of the epoxy resin polymer solution.

9. An epoxy resin prepreg according to claim 1, characterized in that, The molecular weight of the epoxy resin polymer solution is 6000 to 13000.

10. An epoxy resin prepreg according to claim 1, characterized in that, The prepreg further includes fillers, which constitute 20% to 40% of the weight of the epoxy resin polymer solution.

11. An epoxy resin prepreg according to claim 10, characterized in that, The filler is selected from at least one of organic fillers and inorganic fillers.

12. The epoxy resin prepreg according to claim 11, characterized in that, The inorganic filler is selected from at least one of crystalline silica, fused silica, spherical silica, and hollow silica.

13. The epoxy resin prepreg according to claim 10, characterized in that, The particle size of the filler is 0.01μm to 50μm.

14. An epoxy resin prepreg according to claim 10, characterized in that, The particle size of the filler is 0.01μm to 20μm.

15. An epoxy resin prepreg according to claim 10, characterized in that, The particle size of the filler is 0.01 μm to 10 μm.

16. The method for preparing an epoxy resin prepreg according to claim 10, characterized in that, The filler is added to the epoxy resin polymer solution and mixed evenly.

17. A semi-cured adhesive film, characterized in that, The semi-cured adhesive film is obtained by impregnating the reinforcing material in an epoxy resin prepreg as described in claim 1, controlling the adhesive content to be 45% to 55%, and then drying to remove the solvent.

18. A copper foil substrate, characterized in that, The copper foil substrate is obtained by laminating the semi-cured adhesive film of claim 17 with copper foil and then hot-pressing and curing it.

19. A copper foil substrate according to claim 18, characterized in that, The hot-press curing temperature is 80℃~250℃, and the curing pressure is 8Kg / cm. 2 ~60Kg / cm 2 .

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