Anisotropic conductive adhesive film with low modulus after curing and a preparation method thereof

Abstract

This invention relates to the field of electronic component packaging materials technology, and discloses an anisotropic conductive film with low elastic modulus after curing and its preparation method. The conductive film comprises the following components by weight: 35-80 parts of compounded epoxy resin; 50-90 parts of compounded acrylate monomers; 1-10 parts of conductive particles; 10-20 parts of fumed silica; 1-10 parts of phosphate methacrylate; 1-8 parts of silane coupling agent; 1-10 parts of surface leveling agent; and 3-15 parts of initiator. The compounded epoxy resin is a blend of hydrogenated bisphenol A type epoxy resin and bisphenol F type epoxy resin; the compounded acrylate monomers are a blend of hydroxyethyl methacrylate, trimethylolpropane triacrylate, and ethylene glycol diacrylate. The conductive film of this invention has a low elastic modulus after curing, which can directly reduce the internal stress generated during cooling and shrinkage, resulting in better reliability of the ACF and stable performance in environmental testing.

Description

Technical Field

[0001] This invention relates to the field of electronic component packaging materials technology, specifically to an anisotropic conductive film with low elastic modulus after curing and its preparation method, particularly an anisotropic conductive film with an elastic modulus of less than 1.5 MPa after curing and its preparation method. Background Technology

[0002] Anisotropic conductive films are an indispensable material for screen packaging in the electronics industry today. As a special type of electronic adhesive, anisotropic conductive films provide conductivity while also ensuring their adhesive strength and reliability.

[0003] Current anisotropic conductive films have a high elastic modulus after curing. Based on σ = E × α × ΔT (stress = elastic modulus × coefficient of thermal expansion × temperature difference), a large E value results in greater internal stress during cooling and shrinkage, leading to higher interfacial shear stress. This reduces the reliability of anisotropic conductive films, especially after environmental testing, where adhesive strength decreases significantly, increasing the risk of adhesive failure.

[0004] Therefore, there is an urgent need to develop an anisotropic conductive film with low elastic modulus after curing, low internal stress generated by ACF during cooling and shrinkage, good reliability, and stable environmental performance. Summary of the Invention

[0005] To address the aforementioned problems, the present invention aims to provide an anisotropic conductive film with low elastic modulus after curing and its preparation method. The conductive film of the present invention has an elastic modulus of less than 1.5 MPa after curing, exhibits low internal stress during cooling and shrinkage of the ACF, and demonstrates good reliability, stably passing environmental tests.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: An anisotropic conductive adhesive film with low elastic modulus after curing, comprising the following components in parts by weight: 35-80 parts of compounded epoxy resin; 50-90 parts of compounded acrylate monomers; 1 to 10 parts of conductive particles; 10-20 parts of fumed silica; Phosphate methacrylate, 1-10 parts; 1-8 parts of silane coupling agent; 1-10 parts of surface leveling agent; Initiator 3-15 parts; The compounded epoxy resin is a blend of hydrogenated bisphenol A type epoxy resin and bisphenol F type epoxy resin; the compounded acrylate monomer is a blend of hydroxyethyl methacrylate, trimethylolpropane triacrylate and ethylene glycol diacrylate.

[0007] The anisotropic conductive adhesive film of the present invention has an elastic modulus of less than 1.5 MPa after curing.

[0008] Preferably, the compounded epoxy resin comprises the following components by weight: 20-45 parts of hydrogenated bisphenol A type epoxy resin; 15-35 parts of bisphenol F type epoxy resin.

[0009] Preferably, the compounded acrylate monomers comprise the following components by weight: 18-35 parts of hydroxyethyl methacrylate; 15-25 parts of trimethylolpropane triacrylate; 17-30 parts of ethylene glycol diacrylate.

[0010] This invention applies to all conductive particles in the prior art, such as metal particles and polymer plastic spheres coated with metal. Preferably, the conductive particles are resin particles with an outer nickel-plated layer.

[0011] Preferably, the silane coupling agent is one of γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, and vinyltrimethoxysilane.

[0012] Preferably, the surface leveling agent is an organosilicon leveling agent.

[0013] Preferably, the initiator is one of tert-butyl peroxide, dicumyl peroxide, and benzoyl peroxide.

[0014] Preferably, the conductive adhesive film comprises the following components in parts by weight: 20-45 parts of hydrogenated bisphenol A type epoxy resin; 15-35 parts of bisphenol F type epoxy resin; 18-35 parts of hydroxyethyl methacrylate; 15-25 parts of trimethylolpropane triacrylate; 17-30 parts of ethylene glycol diacrylate; 1 to 10 parts of conductive particles; 10-20 parts of fumed silica; Phosphate methacrylate, 1-10 parts; 1-8 parts of silane coupling agent; 1-10 parts of surface leveling agent; Initiator 3-15 parts.

[0015] This invention also provides a method for preparing anisotropic conductive adhesive film with low elastic modulus after curing, comprising the following steps: (1) Mix all components in the compounded epoxy resin evenly, add an appropriate amount of solvent, and heat to 70°C until the solid dissolves; (2) After mixing all the components in the compound acrylate monomer evenly, add them to the reaction solution in step (1), and then add conductive particles, fumed silica, methacrylate phosphate, silane coupling agent, surface leveling agent, and initiator. Stir and disperse evenly to obtain the coating solution. (3) The coating liquid is evenly coated onto the release film, and after baking in an oven, an anisotropic conductive film is produced.

[0016] The solvent is merely one method of treating the resin, and all solvents must be dried during the coating process. Preferably, the solvent is propylene glycol methyl ether, and the mass ratio of solvent to resin is 5:5.

[0017] Preferably, in step (3), the coating liquid is uniformly coated on a 30-100μm PET release film, and after baking in an oven, an anisotropic conductive film of 10-25μm is formed.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention uses a compound of hydrogenated bisphenol A type epoxy resin and bisphenol F type epoxy resin. Using a compound of two epoxy resins makes it easier to control the elastic modulus of the final anisotropic conductive film, ensuring a low elastic modulus is achieved. Simultaneously, it guarantees good reliability of the anisotropic conductive film.

[0019] This invention uses a compound of hydroxyethyl methacrylate, trimethylolpropane triacrylate, and ethylene glycol diacrylate. When using acrylates with different functionalities for compounding, the appropriate reaction rate and crosslinking strength can be achieved by adjusting the proportion of acrylates with different functionalities, while ensuring that the elastic modulus is not too high, so that the anisotropic conductive film has excellent adhesion and reliability.

[0020] The present invention adds phosphate methacrylate. The phosphoric hydroxyl group (P-OH) in the phosphate ester group can form a dense and strong chemical bonding layer on the metal surface. This not only enhances the adhesion, but also provides excellent anti-corrosion performance, further ensuring the reliability of the anisotropic conductive film. Detailed Implementation

[0021] The present invention will be further described below with reference to specific embodiments, but the embodiments do not limit the present invention in any way. Unless otherwise specified, the reagents and instruments used in the embodiments are all commercially available conventional products. Unless otherwise specified, the experimental methods used in the embodiments are all conventional experimental methods or techniques in the art.

[0022] Embodiments of the present invention provide an anisotropic conductive adhesive film with low elastic modulus after curing, comprising the following components in parts by weight: 35-80 parts of compounded epoxy resin; 50-90 parts of compounded acrylate monomers; 1 to 10 parts of conductive particles; 10-20 parts of fumed silica; Phosphate methacrylate, 1-10 parts; 1-8 parts of silane coupling agent; 1-10 parts of surface leveling agent; Initiator 3-15 parts; The compounded epoxy resin is a blend of hydrogenated bisphenol A type epoxy resin and bisphenol F type epoxy resin; the compounded acrylate monomer is a blend of hydroxyethyl methacrylate, trimethylolpropane triacrylate and ethylene glycol diacrylate.

[0023] In some embodiments, the compounded epoxy resin comprises the following components by weight: 20-45 parts of hydrogenated bisphenol A type epoxy resin; 15-35 parts of bisphenol F type epoxy resin.

[0024] In some embodiments, the compounded acrylate monomers include the following components by weight: 18-35 parts of hydroxyethyl methacrylate; 15-25 parts of trimethylolpropane triacrylate; 17-30 parts of ethylene glycol diacrylate.

[0025] This invention applies to all conductive particles in the prior art, such as metal particles and polymer plastic spheres coated with metal. In some embodiments, the conductive particles are resin particles with an outer nickel-plated layer.

[0026] In some embodiments, the silane coupling agent is one of γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, and vinyltrimethoxysilane.

[0027] In some embodiments, the surface leveling agent is a silicone-based leveling agent.

[0028] In some embodiments, the initiator is one of tert-butyl peroxide, dicumyl peroxide, and benzoyl peroxide.

[0029] In some embodiments, the method for preparing the above-mentioned anisotropic conductive adhesive film includes the following steps: (1) Mix all components in the compounded epoxy resin evenly, add an appropriate amount of solvent, and heat to 70°C until the solid dissolves; (2) After mixing all the components in the compound acrylate monomer evenly, add them to the reaction solution in step (1), and then add conductive particles, fumed silica, methacrylate phosphate, silane coupling agent, surface leveling agent, and initiator. Stir and disperse evenly to obtain the coating solution. (3) The coating liquid is evenly coated onto the release film, and after baking in an oven, an anisotropic conductive film is produced.

[0030] The solvent is merely one method of treating the resin, and all solvents must be dried during the coating process. In some embodiments, the solvent is propylene glycol methyl ether, and the mass ratio of solvent to resin is 5:5.

[0031] In some embodiments, in step (3), the coating liquid is uniformly coated on a 30-100 μm PET release film, and after baking in an oven, an anisotropic conductive film of 10-25 μm is formed.

[0032] The present invention will be further described below through Examples 1-6 and Comparative Examples 1-6.

[0033] Example 1 An anisotropic conductive adhesive film, by weight, comprises the following raw materials: 40 parts hydrogenated bisphenol A oxygen-type epoxy resin, 25 parts bisphenol F type epoxy resin, 28 parts hydroxyethyl methacrylate, 17 parts trimethylolpropane triacrylate, 25 parts ethylene glycol diacrylate, 15 parts fumed silica, 6 parts conductive particles (resin particles with an outer nickel plating), 5 parts vinyltrimethoxysilane coupling agent, 6 parts phosphate methacrylate, 7 parts initiator (tert-butyl peroxide), and 3 parts organosilicon leveling agent.

[0034] The preparation method of the above-mentioned anisotropic conductive adhesive film includes the following steps: (1) Mix all components in the compounded epoxy resin evenly, add propylene glycol methyl ether as a solvent, and heat to 70°C until the epoxy resin solid dissolves. (2) After mixing all the components in the compound acrylate monomer evenly, add them to the reaction solution in step (1), and then add conductive particles, fumed silica, methacrylate phosphate, silane coupling agent, surface leveling agent, and initiator. Stir and disperse evenly to obtain the coating solution. (3) The coating liquid is evenly coated on a 30-100μm PET release film and baked in an oven to make an anisotropic conductive film of 10-25μm.

[0035] Example 2 Example 2 is the same as Example 1, except that the compounded epoxy resin consists of 35 parts hydrogenated bisphenol A oxygen type epoxy resin and 30 parts bisphenol F type epoxy resin.

[0036] Example 3 Example 3 is the same as Example 1, except that the compounded epoxy resin consists of 45 parts hydrogenated bisphenol A oxygen type epoxy resin and 20 parts bisphenol F type epoxy resin.

[0037] Example 4 Example 4 is the same as Example 1, except that the compounded acrylate monomers are 25 parts hydroxyethyl methacrylate, 15 parts trimethylolpropane triacrylate, and 30 parts ethylene glycol diacrylate.

[0038] Example 5 Example 5 is the same as Example 1, except that the compounded acrylate monomers are 23 parts hydroxyethyl methacrylate, 17 parts trimethylolpropane triacrylate, and 30 parts ethylene glycol diacrylate.

[0039] Example 6 Example 6 is the same as Example 1, except that the compounded acrylate monomers are 23 parts hydroxyethyl methacrylate, 20 parts trimethylolpropane triacrylate, and 27 parts ethylene glycol diacrylate.

[0040] Comparative Example 1 Comparative Example 1 is the same as Example 1, except that the epoxy resin was not compounded and only 65 parts of hydrogenated bisphenol A oxygen type epoxy resin were used.

[0041] Comparative Example 2 Comparative Example 2 is the same as Example 1, except that the epoxy resin was not compounded and only 65 parts of bisphenol F oxygen type epoxy resin were used.

[0042] Comparative Example 3 Comparative Example 3 is the same as Example 1, except that the compounded acrylate monomers are 30 parts of trimethylolpropane triacrylate and 40 parts of ethylene glycol diacrylate.

[0043] Comparative Example 4 Comparative Example 4 is the same as Example 1, except that the acrylate monomers are not compounded, and only 70 parts of trimethylolpropane triacrylate are used.

[0044] Comparative Example 5 Comparative Example 5 is the same as Example 1, except that the acrylate monomers are not compounded, and only 70 parts of hydroxyethyl methacrylate are used.

[0045] Comparative Example 6 Comparative Example 6 is the same as Example 1, except that phosphate methacrylate was not used.

[0046] The anisotropic conductive films prepared in Examples 1-6 and Comparative Examples 1-3 were tested respectively, and the results are shown in Table 1: Table 1 Performance data of anisotropic conductive films before and after environmental testing

[0047] As shown in Table 1, Comparative Example 1 used only hydrogenated bisphenol A epoxy resin without using bisphenol F epoxy resin for compounding. The elastic modulus after curing was much larger than that of Example 1. Although the adhesion strength showed an upward trend before reliability testing, the adhesion strength decreased significantly after environmental testing. At the same time, the conduction resistance also increased significantly compared with that before environmental testing, and the reliability was not as good as that of Example 1. In Comparative Example 2, only bisphenol F-oxygen epoxy resin was used without hydrogenated bisphenol A-type epoxy resin for compounding. Although the elastic modulus after curing was smaller than that of Example 2, which had the smallest elastic modulus in the examples, the strength of the single-component bisphenol F-oxygen epoxy resin itself was insufficient. As a result, the adhesion before and after the environmental test was not as good as that of Example 1, and the conduction resistance also increased significantly compared to before the reliability test.

[0048] In Comparative Example 3, only trifunctional trimethylolpropane triacrylate and difunctional ethylene glycol diacrylate were used. After curing, the anisotropic conductive film had a high crosslinking density and a large adhesion before reliability. However, the elastic modulus also increased as a result, leading to a significant decrease in adhesion after environmental testing and a slightly higher conduction resistance.

[0049] In Comparative Example 4, only trifunctional trimethylolpropane triacrylate was used. At this time, the crosslinking density of the cured anisotropic conductive film was further increased compared with Comparative Example 3. Similarly, due to the increase in elastic modulus, the adhesion after environmental testing decreased significantly, and the conduction resistance was also slightly higher.

[0050] In Comparative Example 5, only monofunctional hydroxyethyl methacrylate was used. The cured elastic modulus was close to that of the example, and the adhesion and conductivity before environmental testing were also good. However, using only monofunctional acrylate monomers resulted in insufficient crosslinking density of the anisotropic conductive film, making it unable to withstand the impact of environmental testing. This led to a decrease in adhesion and an increase in conductivity after environmental testing.

[0051] In Comparative Example 6, phosphate methacrylate was not used. Due to the lack of phosphorus hydroxyl groups (P-OH) in phosphate methacrylate, the adhesion strength before and after curing was not as good as in Example 1, and the conductivity after environmental testing was also slightly higher.

[0052] In summary, the anisotropic conductive adhesive film with low elastic modulus after curing, as described in this invention, allows the anisotropic conductive adhesive film to maintain a low elastic modulus after curing, thus avoiding the risk of a significant decrease in adhesive strength and adhesive failure after environmental testing.

[0053] The technical solutions provided by the embodiments of the present invention have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of the embodiments of the present invention. The descriptions of the embodiments above are only for helping to understand the principles of the embodiments of the present invention. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the embodiments of the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. An anisotropic conductive adhesive film with low elastic modulus after curing, characterized in that, Includes the following ingredients by weight: 35-80 parts of compounded epoxy resin; 50-90 parts of compounded acrylate monomers; 1 to 10 parts of conductive particles; 10-20 parts of fumed silica; Phosphate methacrylate, 1-10 parts; 1-8 parts of silane coupling agent; 1-10 parts of surface leveling agent; Initiator 3-15 parts; The compounded epoxy resin is a blend of hydrogenated bisphenol A type epoxy resin and bisphenol F type epoxy resin; the compounded acrylate monomer is a blend of hydroxyethyl methacrylate, trimethylolpropane triacrylate and ethylene glycol diacrylate.

2. The anisotropic conductive adhesive film with low elastic modulus after curing according to claim 1, characterized in that, The compounded epoxy resin comprises the following components by weight: 20-45 parts of hydrogenated bisphenol A type epoxy resin; 15-35 parts of bisphenol F type epoxy resin.

3. The anisotropic conductive adhesive film with low elastic modulus after curing according to claim 1, characterized in that, The compounded acrylate monomers comprise the following components by weight: 18-35 parts of hydroxyethyl methacrylate; 15-25 parts of trimethylolpropane triacrylate; 17-30 parts of ethylene glycol diacrylate.

4. The anisotropic conductive adhesive film with low elastic modulus after curing according to claim 1, characterized in that, The conductive particles are resin particles with an outer nickel plating.

5. The anisotropic conductive adhesive film with low elastic modulus after curing according to claim 1, characterized in that, The silane coupling agent is one of γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, and vinyltrimethoxysilane.

6. The anisotropic conductive adhesive film with low elastic modulus after curing according to claim 1, characterized in that, The surface leveling agent is an organosilicon-based leveling agent.

7. The anisotropic conductive adhesive film with low elastic modulus after curing according to claim 1, characterized in that, The initiator is one of tert-butyl peroxide, dicumyl peroxide, and benzoyl peroxide.

8. The anisotropic conductive adhesive film with low elastic modulus after curing according to claim 1, characterized in that, Includes the following ingredients by weight: 20-45 parts of hydrogenated bisphenol A type epoxy resin; 15-35 parts of bisphenol F type epoxy resin; 18-35 parts of hydroxyethyl methacrylate; 15-25 parts of trimethylolpropane triacrylate; 17-30 parts of ethylene glycol diacrylate; 1 to 10 parts of conductive particles; 10-20 parts of fumed silica; Phosphate methacrylate, 1-10 parts; 1-8 parts of silane coupling agent; 1-10 parts of surface leveling agent; Initiator 3-15 parts.

9. A method for preparing an anisotropic conductive adhesive film with low elastic modulus after curing, as described in any one of claims 1 to 8, characterized in that, Includes the following steps: (1) Mix all components in the compounded epoxy resin evenly, add an appropriate amount of solvent, and heat to 70°C until the solid dissolves; (2) After mixing all the components in the compound acrylate monomer evenly, add them to the reaction solution in step (1), and then add conductive particles, fumed silica, methacrylate phosphate, silane coupling agent, surface leveling agent, and initiator. Stir and disperse evenly to obtain the coating solution. (3) The coating liquid is evenly coated onto the release film, and after baking in an oven, an anisotropic conductive film is produced.

10. The method for preparing an anisotropic conductive adhesive film with low elastic modulus after curing according to claim 9, characterized in that, In step (3), the coating liquid is evenly coated on a 30-100μm PET release film, and after baking in an oven, an anisotropic conductive film of 10-25μm is produced.

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