Anisotropic conductive adhesive film and preparation method thereof

Abstract

The invention discloses an anisotropic conductive adhesive film, which is prepared from the following raw materials in parts by weight: 10 to 30 parts of first matrix resin; 15 to 30 parts of second matrix resin; 20 to 60 parts of a solvent; 10 to 15 parts of an initiator; 0.1 to 0.5 part of a curing agent; 1 to 10 parts of large-particle conductive particles; and 2 to 20 parts of small conductive particles. According to the invention, two kinds of matrix resin are subjected to thermal initiation polymerization to generate a new polymer chain, and then the curing agent is used for in-chain curing to form secondary crosslinking, so that the obtained adhesive film has better adhesive property at normal temperature, and the adhesive film can be more easily positioned on an electronic device and is not easy to fall off in the construction process.

Description

Technical Field

[0001] The invention relates to the technical field of adhesive films, and in particular to an anisotropic conductive adhesive film and a preparation method thereof. Background Art

[0002] With the continuous upgrading of industrial structure and technology, conductive adhesives are increasingly used in electronic products, especially wearable devices. Among them, anisotropic adhesive films, as an important type of adhesive, have become a research hotspot. At present, most anisotropic adhesive films cannot meet the requirements of poking, bending, twisting and stretching in flexible electronic products under complex environments due to their unsatisfactory mechanical softness and toughness.

[0003] Anisotropic conductive film (ACF) is a special branch of conductive adhesive, which needs to meet the conditions of conductivity, mechanical properties, particle size and distribution. Among them, conductivity means that ACF must have good conductivity in the Z-axis direction and good insulation in the XY plane. The filling rate, particle size distribution and distribution uniformity of conductive particles will affect its anisotropic conductive properties; mechanical properties mean that ACF should maintain good mechanical properties under different loading rates, including Young's modulus, tensile strength and fracture strain.

[0004] The application number is: 202411092822.7, and the invention name is: An antistatic light-heat dual-curing conductive adhesive and its preparation method; the application number is: 202411008644.5, and the invention name is: Conductive adhesive for capacitors and its preparation method. Although the two published Chinese patents both provide conductive adhesives and their preparation methods, the conductive adhesives prepared by them cannot meet the performance requirements of anisotropic conductive adhesives, especially the conductivity and mechanical properties. Summary of the invention

[0005] In view of the deficiencies in the prior art, the present invention provides an anisotropic conductive adhesive film and a preparation method thereof, so as to solve the technical problem that the prior art cannot meet the performance requirements of the anisotropic conductive adhesive.

[0006] The present invention provides an anisotropic conductive adhesive film. The raw materials of the anisotropic conductive adhesive film include, in parts by weight:

[0007] The first base resin: 10-30 parts;

[0008] Second base resin: 15-30 parts;

[0009] Solvent: 20-60 parts;

[0010] Initiator: 10-15 parts;

[0011] Curing agent: 0.1-0.5 parts;

[0012] Large conductive particles: 1 to 10 parts;

[0013] Small conductive particles: 2 to 20 parts.

[0014] Furthermore, the first matrix resin is any one of acrylic resin, polyurethane resin and modified acrylic resin, or a mixture of at least two of them.

[0015] Furthermore, the second matrix resin is any one of ethylene-vinyl acetate copolymer, polyethylene octene copolymer, polyethylene elastomer, polyethylene copolymer, polyvinyl butyral, silane grafted ethylene copolymer, liquid butyl rubber, liquid styrene butadiene rubber, liquid nitrile rubber and polyurethane liquid rubber, or a mixture of two thereof.

[0016] Furthermore, the solvent is any one of toluene, xylene, ethyl acetate and butyl acetate, or a mixture of two of them.

[0017] Furthermore, the initiator is: dibenzoyl peroxide, di-tert-butyl peroxide, tert-butyl perbenzoate, di-tert-butyl peroxide isopropylbenzene, azobisisobutyronitrile, azobisisoheptanenitrile or triallyl isocyanurate.

[0018] Furthermore, the curing agent is: ethylenediamine, diethylenetriamine, triethylenetetramine, m-phenylenediamine, modified fatty amine, modified polyamine or tert-butyl peroxycarbonate-2-ethylhexyl ester.

[0019] Furthermore, the large conductive particles are nickel, silver, gold, copper or aluminum.

[0020] Furthermore, the diameter of the large conductive particles ranges from 5 μm to 100 μm.

[0021] Furthermore, the small insulating particles are aluminum oxide, aluminum nitride or boron nitride.

[0022] Furthermore, the diameter of the small insulating particles is in the range of 100 nm to 10 μm.

[0023] The present invention also provides a method for preparing anisotropic conductive adhesive film, which is suitable for preparing the above-mentioned anisotropic conductive adhesive film, and comprises the following steps:

[0024] Step 1: Add the first base resin, the second base resin and the solvent into a three-necked flask and heat to melt;

[0025] Step 2: Add an initiator to initiate polymerization under a nitrogen atmosphere. Due to the unstable nature of the initiator, the initiator undergoes homolytic cleavage to form primary free radicals, and then extracts hydrogen atoms from the molecular chain of the first matrix resin to form chain free radicals. After the reaction is completed, cool the mixture to obtain a synthetic resin.

[0026] Step 3: Add the curing agent, large conductive particles and small insulating particles to the obtained synthetic resin, disperse them evenly and let them stand;

[0027] Step 4: coating the synthetic resin with mixed components processed in step 3 on the release film, and obtaining anisotropic conductive adhesive film after curing.

[0028] Furthermore, the heating and melting temperature in step 1 is in the range of 90°C to 120°C.

[0029] Furthermore, in step 4, the coating method includes: blade coating, roller coating or slit coating.

[0030] Beneficial effects of the present invention:

[0031] The present invention firstly generates new polymer chains by thermally initiating polymerization of two base resins, and then uses a curing agent to perform intrachain curing to form secondary crosslinking, so that the obtained adhesive film has good bonding properties at room temperature, and can make the adhesive film easier to position on the electronic device and not easy to fall off during the construction process. In addition, the present invention has good breaking strength and high breaking elongation, so that the adhesive film has strong cohesion, adapts to changes in the external environment, and meets the performance requirements of application scenarios, thereby meeting the requirements of mechanical properties such as poking, bending, twisting and stretching in the application of flexible electronic products in complex environments, so that the anisotropic conductive adhesive film prepared by the present invention has important value in the flexible design and preparation of electronic equipment. In the preparation process of the present invention, because of the characteristics of the raw material combination and the precise coating method, the directional arrangement of conductive particles and insulating particles can be achieved, so that the adhesive film has good conductivity in the Z direction, as well as insulation in the X and Y directions. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described in combination with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0033] The present invention is further illustrated below in conjunction with specific embodiments. Those skilled in the art should understand that these embodiments are only used to illustrate the present invention and are not used to limit the scope of the present invention, and modifications to various equivalent forms of the present invention fall within the scope defined by the appended claims of this application.

[0034] The present invention provides several specific embodiments, which are as follows:

[0035] Embodiment 1:

[0036] The anisotropic conductive adhesive film of this embodiment includes the following components by weight percentage:

[0037] The first base resin: 51 parts;

[0038] Second base resin: 32 parts;

[0039] Solvent: 10 parts;

[0040] Initiator: 5 parts;

[0041] Curing agent: 2 parts;

[0042] 100μm silver conductive particles: 1 part;

[0043] 10μm aluminum oxide particles: 2 parts;

[0044] The first base resin is acrylic resin; the second base resin is ethylene-vinyl acetate copolymer; the solvent is xylene; the initiator is dibenzoyl peroxide; and the curing agent is diethylenetriamine.

[0045] The method for preparing the adhesive film of this embodiment comprises the following steps:

[0046] Step 1: First, add acrylic resin, ethylene-vinyl acetate copolymer and xylene into a three-necked flask, heat and melt, add benzoyl peroxide under nitrogen protection to initiate polymerization, and after the reaction is completed, cool to obtain a synthetic resin;

[0047] Step 2: Add diethyltriamine, silver conductive particles and alumina insulating particles to the obtained synthetic resin, disperse them evenly, let them stand, and finally scrape the resin that has been allowed to stand on the release film. After the resin is cured, the adhesive film is obtained.

[0048] Embodiment 2:

[0049] The anisotropic conductive adhesive film with toughened adhesiveness of this embodiment includes the following components by weight percentage:

[0050] The first base resin: 51 parts;

[0051] Second base resin: 32 parts;

[0052] Solvent: 10 parts;

[0053] Initiator: 5 parts;

[0054] Curing agent: 2 parts;

[0055] 5μm nickel conductive particles: 5 parts

[0056] 100nm aluminum oxide insulating particles: 15 parts;

[0057] The first base resin is polyurethane resin; the second base resin is polyethylene octene copolymer; the solvent is toluene; the initiator is azobisisobutyronitrile; and the curing agent is triethylenetetramine.

[0058] The method for preparing the adhesive film of this embodiment comprises the following steps:

[0059] Step 1: first add polyurethane resin, polyethylene octene copolymer and toluene into a three-necked flask, heat to melt, add azobisisobutyronitrile under nitrogen protection to initiate polymerization, and after the reaction is completed, cool to obtain a synthetic resin;

[0060] Step 2: Add triethylenetetramine, nickel conductive particles and aluminum oxide insulating particles to the obtained synthetic resin, disperse them evenly, let them stand, and finally apply the resin that has been allowed to stand on the release film with a wire rod. After the resin is cured, the adhesive film is obtained.

[0061] Example 3

[0062] The anisotropic conductive adhesive film with toughened adhesiveness of this embodiment includes the following components by weight percentage:

[0063] The first base resin: 51 parts;

[0064] Second base resin: 32 parts;

[0065] Solvent: 10 parts;

[0066] Initiator: 5 parts;

[0067] Curing agent: 2 parts;

[0068] 30μm copper conductive particles: 6 parts;

[0069] 3μm aluminum nitride insulating particles: 10 parts;

[0070] The first base resin is acrylic resin; the second base resin is liquid butyl rubber; the solvent is toluene; the initiator is di-tert-butyl peroxide isopropylbenzene; and the curing agent is diethylenetriamine.

[0071] The method for preparing the adhesive film of this embodiment comprises the following steps:

[0072] Step 1: First, add acrylic resin, liquid butyl rubber and toluene into a three-necked flask, heat to melt, add di-tert-butyl peroxide isopropylbenzene under nitrogen protection to initiate polymerization, and after the reaction is completed, cool to obtain a synthetic resin.

[0073] Step 2: Add diethylenetriamine, copper conductive particles and aluminum nitride insulating particles to the obtained synthetic resin, disperse them evenly, let them stand, and finally scrape the resin that has been allowed to stand on the release film. After the resin is cured, a toughened, adhesive, and anisotropic conductive film is obtained.

[0074] Example 4

[0075] The anisotropic conductive adhesive film with toughened adhesiveness of this embodiment includes the following components by weight percentage:

[0076] The first base resin: 51 parts;

[0077] Second base resin: 32 parts;

[0078] Solvent: 10 parts;

[0079] Initiator: 5 parts;

[0080] Curing agent: 2 parts;

[0081] 70μm copper conductive particles: 6 parts;

[0082] 5μm boron nitride insulating particles: 10 parts;

[0083] The first base resin is polyurethane resin; the second base resin is liquid butyl rubber; the solvent is toluene; the initiator is dibenzoyl peroxide; and the curing agent is ethylenediamine.

[0084] The method for preparing the adhesive film of this embodiment comprises the following steps:

[0085] Step 1: first add polyurethane resin, liquid butyl rubber and toluene into a three-necked flask, heat and melt, add dibenzoyl peroxide under nitrogen protection to initiate polymerization, and after the reaction is completed, cool to obtain a synthetic resin;

[0086] Step 2: Add ethylenediamine, copper conductive particles and boron nitride insulating particles to the obtained synthetic resin, disperse them evenly, let them stand, and finally coat the resin that has stood on the release film. After the resin is cured, the adhesive film is obtained.

[0087] Embodiment 5:

[0088] The anisotropic conductive adhesive film with toughened adhesiveness of this embodiment includes the following components by weight percentage:

[0089] The first base resin: 51 parts;

[0090] Second base resin: 32 parts;

[0091] Solvent: 10 parts;

[0092] Initiator: 5 parts;

[0093] Curing agent: 2 parts;

[0094] 60μm nickel conductive particles: 6 parts;

[0095] 3μm alumina insulating particles: 10 parts;

[0096] The first base resin is acrylic resin; the second base resin is polyethylene elastomer; the solvent is xylene; the initiator is azobisisobutyronitrile; and the curing agent is diethylenetriamine.

[0097] The method for preparing the adhesive film of this embodiment comprises the following steps:

[0098] Step 1: First, add acrylic resin, polyethylene elastomer and xylene into a three-necked flask, heat and melt, add azobisisobutyronitrile under nitrogen protection to initiate polymerization, and after the reaction is completed, cool to obtain a synthetic resin;

[0099] Step 2: Add diethylenetriamine, nickel conductive particles and alumina insulating particles to the obtained synthetic resin, disperse them evenly, let them stand, and finally coat the resin that has stood on the release film. After the resin is cured, the adhesive film is obtained.

[0100] Embodiment 6:

[0101] The anisotropic conductive adhesive film with toughened adhesiveness of this embodiment includes the following components by weight percentage:

[0102] The first base resin: 36 parts;

[0103] Second base resin: 20 parts;

[0104] Solvent: 10 parts;

[0105] Initiator: 5 parts;

[0106] Curing agent: 2 parts;

[0107] 30μm nickel conductive particles: 10 parts;

[0108] 1μm alumina insulating particles: 20 parts;

[0109] The first base resin is acrylic resin; the second base resin is polyethylene elastomer; the solvent is xylene; the initiator is azobisisobutyronitrile; and the curing agent is diethylenetriamine.

[0110] The method for preparing the adhesive film of this embodiment comprises the following steps:

[0111] Step 1: First, add acrylic resin, polyethylene elastomer and xylene into a three-necked flask, heat and melt, add azobisisobutyronitrile under nitrogen protection to initiate polymerization, and after the reaction is completed, cool to obtain a synthetic resin;

[0112] Step 2: Add diethylenetriamine, nickel conductive particles and alumina insulating particles to the obtained synthetic resin, disperse them evenly, let them stand, and finally coat the resin that has stood on the release film. After the resin is cured, the adhesive film is obtained.

[0113] The following is a comparative example, which is used to compare the effects with the above 6 examples, as follows:

[0114] Comparative Example 1:

[0115] The adhesive film of this embodiment includes the following components by weight percentage:

[0116] The first base resin: 88 parts;

[0117] Solvent: 10 parts;

[0118] Curing agent: 2 parts;

[0119] The first base resin is acrylic resin; the solvent is ethyl acetate; and the curing agent is toluene diisocyanate.

[0120] The method for preparing the anisotropic conductive adhesive film with toughened adhesiveness of this embodiment comprises:

[0121] First, acrylic resin, ethyl acetate and toluene diisocyanate are added into a container, dispersed evenly, and allowed to stand. Finally, the resin that has been allowed to stand is coated on a release film. After the resin is cured, the adhesive film is obtained.

[0122] Comparative Example 2:

[0123] The adhesive film of this embodiment includes the following components by weight percentage:

[0124] Second base resin: 88 parts;

[0125] Solvent: 10 parts;

[0126] Curing agent: 2 parts;

[0127] The second base resin is ethylene-vinyl acetate copolymer; the solvent is toluene; the initiator is azobisisobutyronitrile; and the curing agent is tert-butyl peroxycarbonate-2-ethylhexyl ester.

[0128] The method for preparing the anisotropic conductive adhesive film with toughened adhesiveness of this embodiment comprises:

[0129] First, ethylene-vinyl acetate copolymer and toluene are added into a three-necked flask, heated to melt, and then tert-butyl peroxycarbonate-2-ethylhexyl ester is taken, dispersed evenly, and allowed to stand. Finally, the resin that has been allowed to stand is coated on a release film, and the adhesive film is obtained after the resin is cured.

[0130] Comparative Example 3:

[0131] The adhesive film of this embodiment includes the following components by weight percentage:

[0132] The first base resin: 50 parts;

[0133] Second base resin: 38 parts;

[0134] Solvent: 10 parts;

[0135] Curing agent: 2 parts;

[0136] The first matrix resin is acrylic resin; the second matrix resin is ethylene-vinyl acetate copolymer; the solvent is toluene; and the curing agent is a mixture of tert-butyl peroxycarbonate-2-ethylhexyl ester and toluene diisocyanate.

[0137] The method for preparing the anisotropic conductive adhesive film with toughened adhesiveness of this embodiment comprises:

[0138] First, acrylic resin, ethylene-vinyl acetate copolymer and toluene are added into a three-necked flask, heated to melt, and then a mixture of tert-butyl peroxycarbonate-2-ethylhexyl ester and toluene diisocyanate is taken, dispersed evenly, and allowed to stand. Finally, the resin that has been allowed to stand is coated on a release film, and the adhesive film is obtained after the resin is cured.

[0139] Comparative Example 4:

[0140] The adhesive film of this embodiment includes the following components by weight percentage:

[0141] The first base resin: 36 parts;

[0142] Second base resin: 20 parts;

[0143] Solvent: 10 parts;

[0144] Initiator: 5 parts;

[0145] Curing agent: 2 parts;

[0146] 30μm nickel conductive particles: 10 parts;

[0147] The first base resin is acrylic resin; the second base resin is polyethylene elastomer; the solvent is xylene; the initiator is azobisisobutyronitrile; and the curing agent is diethylenetriamine.

[0148] The method for preparing the adhesive film of this embodiment comprises the following steps:

[0149] Step 1: First, add acrylic resin, polyethylene elastomer and xylene into a three-necked flask, heat and melt, add azobisisobutyronitrile under nitrogen protection to initiate polymerization, and after the reaction is completed, cool to obtain a synthetic resin;

[0150] Step 2: Add diethylenetriamine and nickel conductive particles to the obtained synthetic resin, disperse them evenly, let them stand, and finally coat the resin that has stood on the release film. After the resin is cured, the adhesive film is obtained.

[0151] The properties of the anisotropic conductive adhesive films with toughened adhesiveness obtained in Examples 1-6 and Comparative Examples 1-4 were tested, and the test results are shown in Table 1 below:

[0152]

[0153] Table 1

[0154] As can be seen from Table 1, in Comparative Example 1, the single adhesive resin has a relatively high peeling force at room temperature, but the breaking strength and elongation at break are low, which cannot meet the requirements of high toughness, and the weak cohesive strength is easy to leak in the phase change material packaging test. In Comparative Example 2, the single elastomer matrix resin has a significant improvement in its breaking strength and elongation at break, but the bonding strength is very low at room temperature. In Comparative Example 3, the two matrix resins are physically mixed, only cross-linked with a curing agent, and no initiator, tackifying resin and coupling agent are added. The peeling force is greatly improved, but the dynamic shear force cannot meet the use requirements. Comparative Example 4: The two matrix resins are initiated and polymerized under an initiator to form a synthetic resin. Under the interaction of different molecular chains, the bonding strength, breaking strength and elongation at break at room temperature are all improved. The 6 embodiments provided by the present invention, the prepared adhesive films all have excellent bonding properties, toughness and conductivity, so that the application ability on wearable devices has been greatly improved.

[0155] Although the embodiments of the present invention have been described, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations are all within the scope defined by the appended claims.

Claims

1. An anisotropic conductive film, characterized in that: In parts by weight, the raw materials of the anisotropic conductive adhesive film include: The first base resin: 10-30 parts; Second base resin: 15-30 parts; Solvent: 20-60 parts; Initiator: 10-15 parts; Curing agent: 0.1-0.5 parts; Large conductive particles: 1 to 10 parts; Small conductive particles: 2 to 20 parts.

2. The anisotropic conductive adhesive film according to claim 1, characterized in that: The first matrix resin is any one of acrylic resin, polyurethane resin and modified acrylic resin, or a mixture of at least two of them.

3. The anisotropic conductive adhesive film according to claim 1, characterized in that: The second matrix resin is any one of ethylene-vinyl acetate copolymer, polyethylene octene copolymer, polyethylene elastomer, polyethylene copolymer, polyvinyl butyral, silane grafted ethylene copolymer, liquid butyl rubber, liquid styrene butadiene rubber, liquid nitrile rubber and polyurethane liquid rubber, or a mixture of two thereof.

4. The anisotropic conductive adhesive film according to claim 1, wherein: The solvent is any one of toluene, xylene, ethyl acetate and butyl acetate or a mixture of two of them.

5. The anisotropic conductive adhesive film according to claim 1, wherein: The initiator is: dibenzoyl peroxide, di-tert-butyl peroxide, tert-butyl perbenzoate, di-tert-butyl peroxide isopropylbenzene, azobisisobutyronitrile, azobisisoheptanenitrile or triallyl isocyanurate.

6. The anisotropic conductive adhesive film according to claim 1, wherein: The curing agent is: ethylenediamine, diethylenetriamine, triethylenetetramine, m-phenylenediamine, modified fatty amine, modified polyamine or tert-butyl peroxycarbonate-2-ethylhexyl ester.

7. The anisotropic conductive adhesive film according to claim 1, characterized in that: The large conductive particles are nickel, silver, gold, copper or aluminum; the small insulating particles are aluminum oxide, aluminum nitride or boron nitride.

8. The anisotropic conductive adhesive film according to claim 7, characterized in that: The diameter range of the large conductive particles is 5 μm-100 μm; the diameter range of the small insulating particles is 100 nm-10 μm.

9. A method for preparing anisotropic conductive adhesive film, suitable for preparing the anisotropic conductive adhesive film as claimed in any one of claims 1 to 8, the method comprising the following steps: Step 1: Add the first base resin, the second base resin and the solvent into a three-necked flask and heat to melt; Step 2: Add an initiator to initiate polymerization under a nitrogen atmosphere. Due to the unstable nature of the initiator, the initiator undergoes homolytic cleavage to form primary free radicals, and then extracts hydrogen atoms from the molecular chain of the first matrix resin to form chain free radicals. After the reaction is completed, cool the mixture to obtain a synthetic resin. Step 3: Add the curing agent, large conductive particles and small insulating particles to the obtained synthetic resin, disperse them evenly and let them stand; Step 4: coating the synthetic resin with mixed components processed in step 3 on the release film, and obtaining anisotropic conductive adhesive film after curing.

10. The method for preparing anisotropic conductive adhesive film according to claim 9, characterized in that: The heating and melting temperature in step 1 is in the range of 90° C. to 120° C.; the coating methods include: blade coating, roller coating or slit coating.

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