Epoxy adhesive and its preparation method and application

Abstract

The present invention relates to an epoxy adhesive and a preparation method and application thereof. The raw materials for preparing the epoxy adhesive include a combination of a phenolic epoxy resin, an alicyclic epoxy resin, an active diluent, a curing agent and a curing accelerator; the curing accelerator includes an amine compound with a specific structure. The present invention uses a phenolic epoxy resin and an alicyclic epoxy resin as the main resin, and combines a curing accelerator with a specific structure, thereby reducing the amount of active diluent, greatly improving the high-temperature shear strength and interface bonding ability of the solid crystal adhesive, and solving the problem that the epoxy adhesive is difficult to balance between high thermal conductivity, excellent operating performance and high reliability.

Description

Technical Field

[0001] The present invention relates to the technical field of adhesives, and in particular to an epoxy adhesive and a preparation method and application thereof. Background Art

[0002] As a new generation of semiconductor solid-state light-emitting devices, light-emitting diodes (LEDs) are widely used in various lighting and display fields due to their high luminous efficiency and long service life. With the continuous improvement of lighting brightness and luminous flux requirements, LEDs are gradually developing towards high power density and multi-chip integration. They generate a lot of heat in the electro-optical conversion process, causing the device temperature to rise rapidly, seriously affecting the luminous performance and long-term reliability of high-power LED devices. The problem of reduced device reliability due to junction temperature of high-power LEDs has always been a major problem that has plagued the industry and related research fields.

[0003] The development of highly reliable thermally conductive chip bonding materials is the key to solving this problem. The heat generated by the chip is mainly transferred from the bonding layer to the metal heat sink and finally to the air. The bulk thermal resistance and interface thermal resistance of the bonding layer greatly affect the heat dissipation effect of the chip, so the bonding glue is required to have a high thermal conductivity and stable interface bonding ability under extreme environments (no interface defects). Chip thermal conductive bonding materials usually use highly heat-resistant and low-hygroscopic resins to enhance the temperature and humidity resistance and reliability of the thermal conductive bonding glue. For example, polyphenyl ring epoxy resin (MAR), bismaleimide (BMI), and polyimide (PI) resins are used, but these resins are mostly solid powders or high-viscosity fluids. The bonding glue prepared from them has a very high viscosity, and it is often necessary to add a large amount of active diluent (about 20~40 wt% of the resin content) to improve the working performance of the bonding glue.

[0004] For example, CN109593500A discloses a highly filled epoxy conductive silver glue for LED solid crystal, which is made of the following raw materials in weight ratio: 100 parts of epoxy resin, 20-100 parts of curing agent, 0.1-3 parts of accelerator, 0.5-15 parts of coupling agent, 0-10 parts of fumed silica, 20-200 parts of diluent, and 400-2800 parts of silver powder; the epoxy resin is composed of 70-90 parts of bisphenol A epoxy resin and 10-30 parts of special epoxy resin; the special epoxy resin is one or a combination of multiple of glycidyl ether, glycidyl amine and alicyclic epoxy resin; the conductive silver glue has high thixotropy and good storage stability. However, the low heat-resistant active diluent reduces the high temperature resistance and bonding performance of the solid crystal glue, which is the short board that affects the "barrel effect" of the comprehensive performance of the solid crystal glue.

[0005] In summary, how to strike a balance between excellent operating performance and high reliability of epoxy thermal conductive die-bonding adhesive has become a difficult problem that technicians in this field need to solve urgently. Summary of the invention

[0006] In order to solve the above technical problems, the present invention provides an epoxy adhesive and a preparation method and application thereof. By adopting a phenolic epoxy resin and an alicyclic epoxy resin as the main resin and introducing a curing accelerator with a specific structure, an epoxy adhesive with high high-temperature shear strength, no interface defects, low stress and high reliability is obtained, which meets the application needs in the field of LED / IC (Integrated Circuit) chip mounting solid crystal adhesive.

[0007] To achieve this object, the present invention adopts the following technical solutions:

[0008] In a first aspect, the present invention provides an epoxy adhesive, wherein the raw materials for preparing the epoxy adhesive include a phenolic epoxy resin, an alicyclic epoxy resin, a reactive diluent, a curing agent and a curing accelerator;

[0009] The curing accelerator includes any one or a combination of at least two of the compounds having the structures shown in Formula I and Formula II:

[0010]

[0011] Formula I Formula II;

[0012] Wherein, R1 is selected from a single bond, an alkylene group of C1-C6 (e.g., C2, C3, C4, C5);

[0013] R2 is selected from an amide group or a sulfonamide group;

[0014] R3 is selected from hydrogen, substituted or unsubstituted C1-C10 (e.g., C2, C4, C6, C8, etc.) straight chain or branched alkyl, substituted or unsubstituted C3-C12 (e.g., C4, C5, C6, C8, C10, etc.) cycloalkyl, substituted or unsubstituted C6-C30 (e.g., C8, C10, C12, C16, C20, C24, C28, etc.) aryl, secondary amine group;

[0015] R4 is selected from hydrogen, C1-C10 (e.g., C2, C4, C6, C8, etc.) straight or branched alkyl;

[0016] n=0-2, for example, can be 0, 1 or 2.

[0017] In the present invention, by adopting a combination of alicyclic epoxy resin and phenolic epoxy resin, the high temperature resistance and thermal shock resistance of epoxy glue can be enhanced, and the amount of heat-sensitive active diluent added can be reduced. While ensuring the excellent operability of chip solid crystal glue, the high temperature shear strength and interface bonding ability of solid crystal glue are greatly improved, solving the problem that epoxy thermal conductive solid crystal glue is difficult to balance between excellent operating performance and high reliability, and filling the short board of high temperature resistance for chip mounting. In addition, the present invention uses amide or sulfonamide compounds with nitrogen heterocyclic alkyl as a curing accelerator, which can specifically catalyze the ring-opening reaction of alicyclic epoxy resin, so that the heat resistance of the cured product can be greatly improved, and the interface bonding performance is excellent and the interface is defect-free. Although acid anhydride can also catalyze the ring opening of alicyclic epoxy resin, it itself contains ester bonds that are easily hydrolyzed, has poor moisture and heat resistance, and has poor high temperature bonding performance.

[0018] The R2 is selected from an amide group or a sulfonamide group, and the group connected to R3 may be a carbonyl group or a sulfonyl group, or an amino group.

[0019] The substituents in the substituted C1-C10 straight or branched alkyl, substituted C3-C12 cycloalkyl or substituted C6-C30 aryl are each independently selected from C1-C6 (for example, C2, C3, C4, C5) straight or branched alkyl, C1-C6 (for example, C2, C3, C4, C5) alkoxy, C6-C30 (for example, C8, C10, C12, C16, C20, C24, C28, etc.) aryl, amino, amide or sulfonyl.

[0020] Preferably, in the structure of Formula I or Formula II, R1 is selected from -(CH2)2- or -(CH2)3-.

[0021] Preferably, the R3 is selected from the following groups:

[0022] , , , , ,

[0023] Among them, * is the connection site.

[0024] Preferably, the curing accelerator includes any one of N-(3-aminophenyl)pyrrolidine-1-carboxamide (CAS: 702638-74-2), (9ci)-4-methyl-n-3-pyrrolidine-benzenesulfonamide (CAS: 185057-53-8), N,N'-(4-methyl-1,3-phenylene)bis(1-pyrrolidinecarboxamide) (CAS: 60006-11-3), N-[(1-methyl-2-pyrrolidine)methyl]-2-methoxy-4-amino-5-sulfonamidobenzamide (CAS: 63031-48-1) or N-(diphenylmethyl)-1-pyrrolidineacetamide (CAS: 37390-27-5) or a combination of at least two thereof.

[0025] Preferably, in parts by weight, the epoxy adhesive includes 15-55 parts of phenolic epoxy resin (for example, 18 parts, 20 parts, 25 parts, 30 parts, 35 parts, 40 parts, 45 parts, 50 parts, etc.), 25-63 parts of alicyclic epoxy resin (for example, 30 parts, 35 parts, 40 parts, 45 parts, 50 parts, 55 parts, 60 parts, etc.), 10-25 parts of reactive diluent (for example, 12 parts, 14 parts, 15 parts, 16 parts, 18 parts, 20 parts, 22 parts, 24 parts, etc.), 5-12 parts of curing agent (for example, 6 parts, 7 parts, 8 parts, 9 parts, 10 parts, 11 parts, etc.) and 0.5-5 parts of curing accelerator (for example, 0.8 parts, 1 parts, 1.5 parts, 2 parts, 3 parts, 4 parts, etc.).

[0026] The epoxy adhesive provided by the present invention significantly improves the interfacial bonding ability of the epoxy adhesive, increases the residual adhesive rate at room temperature and high temperature, and improves reliability by combining phenolic epoxy resin, alicyclic epoxy resin with active diluent, curing agent and curing accelerator in a specific ratio.

[0027] The “parts” and “parts by weight” involved in the present invention are all calculated based on solid content and do not include solvents, dispersants, etc.

[0028] Preferably, the mass of the alicyclic epoxy resin is 25-65% of the total mass of the phenolic epoxy resin, the alicyclic epoxy resin and the reactive diluent, for example, it can be 28%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 62%, etc.

[0029] The epoxy adhesive provided by the present invention further improves the high temperature resistance, high temperature shear strength and interface bonding ability of the epoxy adhesive by adopting a specific ratio of phenolic epoxy resin and alicyclic epoxy resin, reduces the amount of active diluent added, and enables the epoxy adhesive to have both excellent operating performance and high reliability.

[0030] Preferably, the epoxy equivalent of the phenolic epoxy resin is 160-250 g / Eq, for example, 170 g / Eq, 180 g / Eq, 190 g / Eq, 200 g / Eq, 210 g / Eq, 220 g / Eq, 230 g / Eq, 240 g / Eq, etc.

[0031] Preferably, the viscosity of the phenolic epoxy resin at 25° C. is 20,000-65,000 mPa·s, for example, 25,000 mPa·s, 30,000 mPa·s, 35,000 mPa·s, 40,000 mPa·s, 45,000 mPa·s, 50,000 mPa·s, 55,000 mPa·s, 60,000 mPa·s, etc.

[0032] The present invention ensures that the epoxy adhesive has excellent processability by compounding a phenolic epoxy resin with a specific epoxy equivalent and a specific viscosity with other components. When the epoxy equivalent is too large, the resin molecular weight is large, close to a solid state, difficult to dissolve and disperse, and the epoxy adhesive obtained has poor workability. When the epoxy equivalent is too small, although the resin viscosity is reduced, the raw material cost is high, which is not conducive to large-scale commercial application.

[0033] For example, the phenolic epoxy resin in the present invention may be N770 (DIC of Japan), N740 (DIC of Japan), N730A (DIC of Japan), etc., which are well known to those skilled in the art.

[0034] Preferably, the epoxy equivalent of the alicyclic epoxy resin is 100-190 g / Eq, for example, 110 g / Eq, 120 g / Eq, 130 g / Eq, 140 g / Eq, 150 g / Eq, 160 g / Eq, 170 g / Eq, 180 g / Eq, etc.

[0035] The present invention uses a cycloaliphatic epoxy resin with a specific epoxy equivalent to prepare an epoxy adhesive with excellent heat resistance and processability. When the epoxy equivalent is too large, the cycloaliphatic epoxy resin is difficult to dilute, and a large amount of active diluent still needs to be added to reduce the viscosity, resulting in reduced reliability of the epoxy adhesive; when the epoxy equivalent is too small, the cycloaliphatic epoxy resin has low functionality and high reactivity, making it difficult to improve the high temperature resistance and room temperature storage performance of the epoxy adhesive.

[0036] For example, the alicyclic epoxy resin described in the present invention may be TTA800 (Jiangsu Taitel), UVR6103 (Hubei Xinjing New Materials), 2021P (Japan Daicel), S186 (Hubei Xinjing New Materials), TTA21P (Jiangsu Taitel), TTA26 (Jiangsu Taitel), TTA28 (Jiangsu Taitel), etc., which are well known to those skilled in the art.

[0037] Preferably, the reactive diluent comprises a difunctional epoxy diluent.

[0038] The bifunctional epoxy diluent of the present invention is used to improve the viscosity and rheological properties of the adhesive, and the epoxy groups in the diluent participate in the curing reaction.

[0039] Preferably, the reactive diluent comprises a diglycidyl ether (ester) of an aliphatic diol.

[0040] Preferably, the reactive diluent comprises a diglycidyl ether of a saturated aliphatic diol.

[0041] Preferably, the reactive diluent comprises any one of butanediol diglycidyl ether, neopentyl alcohol diglycidyl ether, polypropylene glycol diglycidyl ether or dimer acid glycidyl ester, or a combination of at least two thereof.

[0042] For example, the reactive diluent in the present invention can be a commercially available product well known to those skilled in the art, such as any one or a combination of at least two of the difunctional epoxy diluents of model numbers XY748, XY205, XY207 and XY678.

[0043] Preferably, the curing agent comprises an amine curing agent.

[0044] Preferably, the curing agent includes any one of m-phenylenediamine, 4,4'-diaminodiphenylmethane (DDM), 4,4'-diaminodiphenyl sulfone (DDS) or dicyandiamide, or a combination of at least two thereof.

[0045] Preferably, the curing accelerator further includes a latent curing accelerator.

[0046] Exemplarily, the latent curing accelerator of the present invention can be any one of Ajinomoto PN-23, PN-23J, MY-24, MY-25, 2E4MZ, 2E4MZ-CN, 4-methyl-2-phenylimidazole or 2MA-OK of Shikoku Chemical, or a combination of at least two thereof.

[0047] Preferably, the raw materials for preparing the epoxy adhesive also include fillers.

[0048] Preferably, the filler includes any one of metal powder, silicon powder or fumed silicon dioxide, or a combination of at least two of them.

[0049] Preferably, the filler comprises flake silver powder and / or spherical silver.

[0050] As the conductive epoxy adhesive for chip mounting, the filler is preferably silver powder. The present invention has no special restriction on the source of the silver powder, and commercially available products known to those skilled in the art can be used, such as EA-0295PH from Metalor and SF-125 from TECHNIC Inc.

[0051] Preferably, the raw materials for preparing the epoxy adhesive also include auxiliary agents.

[0052] Preferably, the auxiliary agent includes any one of an adhesion promoter, a thixotropic agent or a colorant, or a combination of at least two of them.

[0053] Preferably, the weight portion of the adhesion promoter is 0.2-3 parts, for example, it can be 0.5 parts, 0.8 parts, 1 parts, 1.2 parts, 1.5 parts, 1.8 parts, 2 parts, 2.2 parts, 2.5 parts, 2.8 parts, etc.

[0054] In a second aspect, the present invention provides a method for preparing the epoxy adhesive as described in the first aspect, the preparation method comprising the following steps:

[0055] The epoxy adhesive is obtained by mixing phenolic epoxy resin, alicyclic epoxy resin, reactive diluent, curing agent and curing accelerator.

[0056] Preferably, the preparation method comprises the following steps:

[0057] (1) Evenly mixing a phenolic epoxy resin, an alicyclic epoxy resin, a reactive diluent, a curing agent and a curing accelerator to obtain a resin mother solution;

[0058] (2) Grinding the resin mother liquid obtained in step (1), heating, cooling, adding fillers and additives, mixing evenly, and degassing to obtain the epoxy adhesive.

[0059] Preferably, the grinding in step (2) is carried out in a three-roll mill.

[0060] Preferably, the heating temperature in step (2) is 50-80°C, for example, 55°C, 60°C, 65°C, 70°C, 75°C, etc.

[0061] Preferably, the heating time in step (2) is 5-40 min, for example, 10 min, 15 min, 20 min, 25 min, 30 min, 35 min, etc.

[0062] Preferably, the cooling temperature in step (2) is 15-30°C, for example, 18°C, 20°C, 22°C, 25°C, 28°C, etc.

[0063] Preferably, the uniform mixing in step (2) is carried out in a double planetary hybrid stirring tank.

[0064] Preferably, the vacuum degree of the degassing in step (2) is ≤-0.095 MPa, for example, it can be -0.1 MPa, -0.11 MPa, -0.12 MPa, -0.15 MPa, -0.18 MPa, -0.2 MPa, etc.

[0065] Preferably, the degassing time in step (2) is 15-25 min, for example, it can be 16 min, 17 min, 18 min, 19 min, 20 min, 21 min, 22 min, 23 min, 24 min, etc.

[0066] Preferably, the preparation method comprises the following steps:

[0067] (1) Evenly mixing a phenolic epoxy resin, an alicyclic epoxy resin, a reactive diluent, a curing agent and a curing accelerator to obtain a resin mother solution;

[0068] (2) Grinding the resin mother liquid obtained in step (1), heating at 50-80° C. for 5-40 min, cooling to 15-30° C., adding fillers and additives, mixing evenly, and degassing at a vacuum degree of ≤-0.095 MPa for 15-25 min to obtain the epoxy adhesive.

[0069] The epoxy adhesive preparation method provided by the invention has simple process, mild conditions, easy control and good process adaptability.

[0070] In a third aspect, the present invention provides a use of the epoxy adhesive as described in the first aspect in chip mounting.

[0071] Compared with the prior art, the present invention has at least the following beneficial effects:

[0072] The present invention reduces the absolute amount of active diluent added in the resin system by compounding alicyclic epoxy resin with phenolic epoxy resin, while ensuring the excellent operability of the chip bonding adhesive, greatly improving the high-temperature shear strength and interface bonding ability of the bonding adhesive, solving the problem that it is difficult to strike a balance between excellent operating performance and high reliability of the epoxy thermal conductive bonding adhesive; on the other hand, the present invention uses an amine compound of a specific structure as a curing accelerator to specifically catalyze the ring-opening reaction of the alicyclic epoxy resin, solving the problem of low reaction activity between the alicyclic epoxy resin and the curing agent, thereby greatly improving the heat resistance of the cured product, and at the same time, the interface bonding performance is excellent and the interface is defect-free. The prepared epoxy adhesive has excellent temperature resistance and low internal stress, and the chip does not delaminate after hot and cold shocks, and has high reliability. DETAILED DESCRIPTION

[0073] For the convenience of understanding the present invention, the present invention lists the following embodiments. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0074] In the following specific implementations of the present invention, the materials involved are shown in Table 1:

[0075] Table 1

[0076]

[0077] Examples 1-7, Comparative Examples 1-4

[0078] An epoxy adhesive, the types and amounts of the components are shown in Table 2, and the units of the amounts of the components are all "parts by mass".

[0079] The epoxy adhesive is prepared by the following method:

[0080] 1) Weigh phenolic epoxy resin, alicyclic epoxy resin, reactive diluent, curing agent and curing accelerator according to the proportion, stir evenly to obtain resin mother solution;

[0081] 2) The resin mother solution obtained in step (1) is ground by three rollers, then stirred and mixed, heated at 60° C. for 10 min until it becomes clear and transparent, cooled to room temperature, and finally fillers and adhesion promoters are added, stirred evenly, and degassed at a vacuum degree of ≤-0.095 MPa for 20 min before discharging the material to obtain the epoxy adhesive for chip mounting.

[0082] Table 2

[0083]

[0084] The epoxy adhesives obtained in the examples and comparative examples were tested as follows:

[0085] 1) Chip thrust: Die-Shear Strength test method refers to "HG / T 5912-2021 Conductive Adhesives", silicon wafer size: 2mm×2mm; substrate is silver-plated copper sheet, curing conditions are blast oven 175℃×1.0h; test equipment DAGE-4000P multi-function push-pull test machine, Nordson DAGE Precision Industries LTD, USA, shear strength is thrust size (unit is kgF); 10 samples of each glue, take the average value. When measuring high-temperature thrust, set the temperature of the temperature-controlled heating table, stabilize for 5 minutes after reaching the target temperature, and then start measuring the thrust.

[0086] 2) Evaluation of chip residual glue rate: Observe the residual glue on the substrate after thrust damage through an optical microscope, evaluate the area ratio of the residual glue part (percentage relative to the chip area), and take the arithmetic mean of 10 samples.

[0087] 3) Viscosity: Use a Brookfield rotational viscometer with a 51# rotor and a rotation speed of 5 rpm to test the viscosity of the sample at 25°C.

[0088] 4) The temperature cycle test (TCT) test method refers to JESD22-A104, -55℃ to 150℃, 1000 cycles, use ultrasonic microscope SAT ultrasonic scanning (T-Scan mode) to observe the delamination. If the chip is delaminated, it is considered to have failed the test.

[0089] The test results are summarized in Table 3.

[0090] Table 3

[0091]

[0092] It can be seen from the test results that the present invention adopts phenolic epoxy resin and alicyclic epoxy resin as the main resin, and cooperates with an amine compound of a specific structure as a curing accelerator to prepare an epoxy adhesive for chip mounting, which reduces the amount of heat-labile active diluent, greatly improves the high-temperature shear strength and interface bonding ability of the solid crystal adhesive, maintains the viscosity at 8000-15000 cps, and the thrust of a 2 mm×2 mm chip at 260°C is greater than 1.4 kgF. The chip residual glue rate is high, the interface is defect-free, there is no delamination after TCT, and the low stress reliability is high, which solves the problem that it is difficult to strike a balance between high thermal conductivity, excellent operating performance and high reliability of epoxy thermal conductive solid crystal adhesive.

[0093] Compared with Example 2, when the viscosity is similar, when the proportion of alicyclic epoxy resin is higher, the room temperature and high temperature thrust are reduced; compared with Example 4, when the proportion of alicyclic epoxy resin is lower, the chip residual glue rate becomes worse, and the room temperature and high temperature thrust are also reduced.

[0094] Compared with Example 1, Comparative Example 1 did not add low-viscosity alicyclic epoxy resin. As a result, at the same viscosity (reflecting excellent operating performance), 35.3% of reactive diluent with poor heat resistance was added, resulting in a low chip residual glue rate, delamination after TCT, and poor high-temperature shear strength and interface bonding ability.

[0095] Compared with Example 1, Comparative Example 2 did not add alicyclic epoxy resin, but added the same proportion of active diluent, resulting in the epoxy adhesive viscosity exceeding the range (EEEE) and extremely poor operating performance. In addition, due to the excessive viscosity, the wettability to the silver-plated frame was poor, resulting in a poor residual adhesive rate.

[0096] Compared with Example 1, the main resin of Comparative Example 3 only includes alicyclic epoxy resin, and the chip thrust at room temperature and high temperature is relatively low, which is difficult to meet the strength and reliability requirements of the wire bonding process.

[0097] Compared with Example 1, Comparative Example 4 only uses a latent curing accelerator but does not use a curing accelerator with a specific structure. The prepared epoxy adhesive has lower shear strength at room temperature and high temperature, and the chip residual adhesive rate is low and the interface bonding ability is poor.

[0098] The applicant declares that the above is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention are within the protection scope and disclosure scope of the present invention.

Claims

1. An epoxy adhesive, characterized in that: The raw materials for preparing the epoxy adhesive include a combination of phenolic epoxy resin, alicyclic epoxy resin, reactive diluent, curing agent and curing accelerator; The curing accelerator includes any one or a combination of at least two of the compounds having the structures shown in Formula I and Formula II: ； Formula I Formula II; wherein R1 is selected from -(CH2)2- or -(CH2)3-; R2 is selected from an amide group or a sulfonamide group; R3 is selected from the following groups: , , , , , * is the connection site; R4 is selected from hydrogen, C1-C10 straight chain or branched alkyl; n=an integer from 0 to 2.

2. The epoxy adhesive according to claim 1, characterized in that: The curing accelerator includes any one or a combination of at least two of N-(3-aminophenyl)pyrrolidine-1-carboxamide, (9ci)-4-methyl-n-3-pyrrolidine-benzenesulfonamide, N,N'-(4-methyl-1,3-phenylene)bis(1-pyrrolidinecarboxamide), N-[(1-methyl-2-pyrrolidine)methyl]-2-methoxy-4-amino-5-sulfonamidobenzamide or N-(diphenylmethyl)-1-pyrrolidineacetamide.

3. The epoxy adhesive according to claim 1, characterized in that: In parts by weight, the epoxy adhesive comprises 15-55 parts of phenolic epoxy resin, 25-63 parts of alicyclic epoxy resin, 10-25 parts of reactive diluent, 5-12 parts of curing agent and 0.5-5 parts of curing accelerator; The mass of the alicyclic epoxy resin is 25-65% of the total mass of the phenolic epoxy resin, the alicyclic epoxy resin and the reactive diluent.

4. The epoxy adhesive according to claim 1, characterized in that: The epoxy equivalent of the phenolic epoxy resin is 160-250 g / Eq; The viscosity of the phenolic epoxy resin at 25° C. is 20,000-65,000 mPa·s; The epoxy equivalent of the alicyclic epoxy resin is 100-190 g / Eq; The reactive diluent includes a difunctional epoxy diluent; The curing agent includes an amine curing agent; The curing accelerator also includes a latent curing accelerator.

5. The epoxy adhesive according to claim 1, characterized in that: The raw materials for preparing the epoxy adhesive also include fillers; The filler comprises any one of metal powder, silicon powder or fumed silicon dioxide or a combination of at least two thereof; The raw materials for preparing the epoxy adhesive also include auxiliary agents; The auxiliary agent includes any one or a combination of at least two of an adhesion promoter, a thixotropic agent or a colorant; The weight portion of the adhesion promoter is 0.2-3 parts.

6. A method for preparing the epoxy adhesive according to any one of claims 1 to 4, characterized in that: The preparation method comprises the following steps: The epoxy resin is mixed with a phenolic epoxy resin, an alicyclic epoxy resin, a reactive diluent, a curing agent and a curing accelerator to obtain the epoxy adhesive; The curing accelerator includes any one or a combination of at least two of the compounds having the structures shown in Formula I and Formula II: ； Formula I Formula II; wherein R1 is selected from -(CH2)2- or -(CH2)3-; R2 is selected from an amide group or a sulfonamide group; R3 is selected from the following groups: , , , , , * is the connection site; R4 is selected from hydrogen, C1-C10 straight chain or branched alkyl; n=an integer from 0 to 2.

7. The preparation method according to claim 6, characterized in that: The preparation method comprises the following steps: (1) Evenly mixing a phenolic epoxy resin, an alicyclic epoxy resin, a reactive diluent, a curing agent and a curing accelerator to obtain a resin mother solution; (2) grinding the resin mother solution obtained in step (1), heating it, adding fillers and additives after cooling, mixing them evenly, and then degassing to obtain the epoxy adhesive; The grinding in step (2) is carried out in a three-roll grinder; The heating temperature in step (2) is 50-80°C; The heating time in step (2) is 5-40 min; The cooling temperature in step (2) is 15-30°C; The vacuum degree of degassing in step (2) is ≤-0.095 MPa; The degassing time in step (2) is 15-25 min.

8. Use of the epoxy adhesive according to any one of claims 1 to 5 in chip mounting.

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