Preparation method of anisotropic conductive adhesive film and anisotropic conductive adhesive film

Abstract

The application provides a preparation method of an anisotropic conductive adhesive film and the anisotropic conductive adhesive film. Array distributed conductive microspheres are obtained through a preparation route of a microporous template, the obtained array distributed conductive microspheres are transferred to a first layer of a photo-thermal dual-cured resin adhesive film, a second layer of resin adhesive film is laminated on the first layer of resin adhesive film, the first layer of resin adhesive film is subjected to ultraviolet light pre-curing treatment, pre-curing ensures that the array form of the conductive microspheres is preliminarily fixed in the resin adhesive film, and the particle array type anisotropic conductive adhesive film is obtained. Heat curing is used to further ensure that the adhesive film obtains good bonding strength and conductive performance in the bonding process. Compared with the anisotropic conductive adhesive film of a single curing agent system, the obtained particle array type anisotropic conductive adhesive film has better particle array arrangement, conductive performance and bonding strength when applied to a bonded electrode assembly.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of new materials, in particular to a preparation method of an anisotropic conductive adhesive film and the anisotropic conductive adhesive film. BACKGROUND

[0002] Anisotropic conductive film (ACF) is widely used in the connection of circuit boards in display panels, camera modules and other devices. Its most notable feature is that it is conductive in the vertical direction and insulating in the horizontal direction, while also having the function of gluing and fixing. The main components of ACF film are insulating resin and conductive particles. According to the distribution characteristics of conductive particles in the resin, ACF film can be divided into particle random distribution type and particle array type. The conductive particles of traditional ACF film are randomly distributed, which can be easily realized through mixing and coating processes. Particle array type ACF film has more advantages in the demand for bonding of ultra-fine pitch electrodes, which can effectively reduce the risk of short circuit. However, the preparation process of particle array type ACF needs to realize the array distribution of particles at the microscale, and the array form of particles needs to remain basically unchanged during the preparation and bonding process of the film, which poses great challenges in the preparation process and resin formula selection.

[0003] The resin of ACF film is generally epoxy resin or acrylic resin, and a single thermal curing system is generally used. Epoxy resin can provide high bonding strength and can withstand long-term reliability tests, so it is widely used. However, the thermal compression temperature of epoxy resin is generally high (180-250℃) and the thermal compression time is relatively long (5-10s), which can generate a large thermal stress on the electrodes of thermal compression. The acrylic resin solution can better solve this problem, such as the patent JP2010037539A of Japan Diyihe Electronic Materials Co., Ltd., which uses an acrylic compound to prepare ACF film, and can achieve good bonding strength and conduction reliability under the condition of thermal compression at 130℃ for 3s. In addition, the acrylic resin system can be better compatible with the light curing method.

[0004] Compared with the traditional single thermal curing system, in recent years, people have begun to study the resin formula of the dual curing system to further optimize the ACF film. For example, the patent CN111100562A of Shenzhen Sabic Technology Co., Ltd. uses segmented thermal curing and magnetic force curing to prepare a dual-curing ACF film, mainly to solve the problems of electrode connection reliability and repair difficulty. The patent CN102634286B of Shenzhen Feisier Industry Co., Ltd. uses light-thermal dual curing technology to prepare an ACF film, and the purpose of introducing light curing is to avoid the use of solvents and protect the environment. The patent CN104673113A of Donghua University proposes a light-thermal dual-curing ACF film to solve the problems of incomplete curing by single light curing, high curing temperature and long curing time by single thermal curing. However, the above dual-curing resins are all used for traditional ACF films with random distribution of particles. The advantages of dual-curing are expected to solve the preparation problems of particle array type ACF films. SUMMARY

[0005] Therefore, it is necessary to provide an anisotropic conductive adhesive film with excellent particle array arrangement, conductive performance and bonding strength and a preparation method thereof in view of the defects in the prior art.

[0006] To solve the above problems, the technical scheme adopted by the present application is as follows:

[0007] One of the objects of the present application is to provide a preparation method of an anisotropic conductive adhesive film, comprising the following steps:

[0008] obtaining array-distributed conductive microspheres;

[0009] obtaining a first layer of resin film with array-distributed conductive microspheres;

[0010] coating a second layer of resin film on the first layer of resin film;

[0011] pre-curing the first layer of resin film to obtain the anisotropic conductive adhesive film.

[0012] In some embodiments, the step of obtaining array-distributed conductive microspheres specifically comprises the following steps:

[0013] preparing a micropore array template;

[0014] modifying the surface of the micropore array template with a fluorine-containing organic surface modifier to obtain a micropore array template with low surface energy;

[0015] filling conductive microspheres into each micropore of the micropore array template with low surface energy to obtain array-distributed conductive microspheres.

[0016] In some embodiments, the step of preparing the micropore array template specifically comprises the following steps:

[0017] The micropore array template is prepared by photolithography or laser etching or soft lithography or screen printing or electron beam lithography, wherein the substrate used in the preparation of the micropore array template is a pure silicon substrate or a metal substrate or a ceramic substrate or an organic substrate, the substrate is in the shape of a flat plate or a roller that can be used for continuous preparation, the micropore diameter D1 of the micropore array template is 150 nm to 150 μm, and the pore depth H is 50 nm to 150 μm.

[0018] In some embodiments, the step of modifying the surface of the micropore array template with a fluorine-containing organic surface modifier to obtain a micropore array template with low surface energy specifically comprises the following steps:

[0019] In some embodiments, the step of filling conductive microspheres into each micropore of the micropore array template with low surface energy to obtain array-distributed conductive microspheres specifically comprises the following steps:

[0020] In some embodiments, the particle size D2 of the conductive microspheres is 100 nm to 100 μm, and D2 < D1, 0.5H < D2 < 1.5H.

[0021] In some embodiments, the step of obtaining a first layer of resin adhesive film with array-distributed conductive microspheres specifically comprises the following steps:

[0022] The acrylic resin is coated on the release film to obtain an acrylic resin adhesive film;

[0023] The acrylic resin adhesive film is laminated to the micropore array template, and the conductive microspheres are transferred to the acrylic resin adhesive film by peeling off the adhesive film to obtain a first layer of resin adhesive film with array-distributed conductive microspheres.

[0024] In some embodiments, the acrylic resin comprises 0.5 to 20 parts by mass of a photoinitiator, 0.5 to 20 parts by mass of a thermal initiator, and 5 to 200 parts by mass of an acrylic resin; wherein:

[0025] The photoinitiator comprises one or a mixture of several of alkyl phenone, benzoin, acyl phosphine oxide, benzoin and derivatives, benzoin, benzophenone, thioxanthone, aryl iodonium salt, alkyl iodonium salt, and cumene hexafluorophosphate.

[0026] The thermal initiator includes one or a mixture of several of the following: persulfate, hydrogen peroxide, di-tert-alkyl peroxide, acyl peroxide, carboxylic acid ester peroxide, dicarbonate peroxide, azocyano, azonitro, azo ester, and azo hydroxy.

[0027] The acrylic resins mentioned include one or a mixture of several types of epoxy acrylates, phosphate acrylates, polyester acrylates, polyurethane acrylates, polyether acrylates, monofunctional acrylates, difunctional acrylates, trifunctional acrylates, or polyfunctional acrylates.

[0028] In some embodiments, the thickness of the first resin film is 500 nm to 20 μm.

[0029] In some embodiments, the step of coating the second resin film onto the first resin film specifically includes the following steps:

[0030] The second resin film is coated onto the first resin film, and the release film on one side of the first resin film is peeled off.

[0031] In some embodiments, the second resin film is prepared by coating a release film with a resin film to obtain the second resin film.

[0032] In some embodiments, the release force of the release film on the first resin film side is less than the release force of the release film on the second resin film side.

[0033] In some embodiments, the thickness of the second resin film is 1 μm to 100 μm.

[0034] In some embodiments, the second resin film comprises a thermosetting resin, wherein the thermosetting resin comprises epoxy resin or acrylic resin; wherein:

[0035] The epoxy resin includes one or more of the following: bisphenol A type epoxy resin, bisphenol F type epoxy resin, polyphenol type glycidyl ether epoxy resin, aliphatic glycidyl ether epoxy resin, glycidyl ester type epoxy resin, glycidyl amine type epoxy resin, epoxidized olefin compound, or heterocyclic and mixed type epoxy resin; the thermosetting agent of the epoxy resin includes conventional curing agents or latent curing agents, wherein the conventional curing agent includes one or more combinations of imidazole compounds, boron trifluoride complexes, organic acid anhydrides, polyamides, tertiary amines, aliphatic polyamines, alicyclic polyamines, aromatic polyamines, or their modifiers; the latent curing agent includes one or more combinations of melamine, microencapsulated imidazole, boron trifluoride amine, or modified amines; the epoxy resin is present in a mass fraction of 5 to 200 parts, and the thermosetting agent of the epoxy resin is present in a mass fraction of 0.5 to 20 parts.

[0036] The acrylic resin includes one or a mixture of several of the following: epoxy acrylate, phosphate acrylate, polyester acrylate, polyurethane acrylate, polyether acrylate, monofunctional acrylate, difunctional acrylate, trifunctional acrylate, or polyfunctional acrylate; the thermosetting agent of the acrylic resin includes one or a mixture of several of the following: organic peroxide, inorganic peroxide, or azo compound; the acrylic resin is present in a mass fraction of 5 to 200 parts, and the thermosetting agent of the acrylic resin is present in a mass fraction of 0.5 to 20 parts.

[0037] In some embodiments, the step of pre-curing the first resin film to obtain the anisotropic conductive film specifically includes the following steps:

[0038] The first resin film is pre-cured by irradiating it with ultraviolet light from one side of the second resin film to obtain the desired particle array-type anisotropic conductive film.

[0039] In some embodiments, the ultraviolet light intensity is 0.1–50 mW / cm². -2 The curing time is 1 second to 10 minutes.

[0040] A second objective of this application is to provide an anisotropic conductive adhesive film, which is prepared by the aforementioned method for preparing anisotropic conductive adhesive films.

[0041] The present application adopts the above technical solution, and its beneficial effects are as follows:

[0042] The anisotropic conductive adhesive film preparation method and the anisotropic conductive adhesive film provided in this application involve obtaining an array of conductive microspheres through a microporous template preparation route, transferring the obtained array of conductive microspheres to a first layer of photothermal dual-curing resin film, and then coating the first layer of resin film onto the first layer of resin film. The first layer of resin film is then subjected to ultraviolet light pre-curing treatment. Pre-curing ensures that the array morphology of the conductive microspheres is initially fixed in the resin film, thereby obtaining the particle array type anisotropic conductive adhesive film. The use of thermal curing further ensures that the adhesive film obtains good adhesion strength and conductivity during the bonding process. Compared with anisotropic conductive adhesive films with a single curing agent system, the obtained particle array type anisotropic conductive adhesive film exhibits superior particle array arrangement, conductivity, and adhesion strength when applied to bonding electrode components. Attached Figure Description

[0043] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the description of the embodiments of this application or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0044] Figure 1 a A flowchart illustrating the steps of the method for preparing anisotropic conductive adhesive film provided in the embodiments of this application;

[0045] Figure 1 b A schematic diagram illustrating the principle of the anisotropic conductive adhesive film provided in the embodiments of this application;

[0046] Figure 2 Optical micrographs of the micropore array template provided in the embodiments of this application;

[0047] Figure 3 Three-dimensional laser confocal micrographs of the micropore array template provided in the embodiments of this application;

[0048] Figure 4 The contact angles of the silicon wafer before and after surface modification provided in the embodiments of this application;

[0049] Figure 5 Optical micrographs of conductive microspheres filled in a microporous array template, provided in the embodiments of this application;

[0050] Figure 6 Three-dimensional laser confocal micrograph of conductive microspheres filled in a microporous array template, provided in an embodiment of this application;

[0051] Figure 7 A scanning electron microscope image taken at a 45° angle of the conductive microspheres transferred onto the first resin film provided in the embodiments of this application;

[0052] Figure 8 Optical micrograph of a particle array-type anisotropic conductive film provided in an embodiment of this application;

[0053] Figure 9 The thermal analysis curves (DSC) and curing rates of the acrylic resin before and after light and heat curing are provided in the embodiments of this application.

[0054] Figure 10 The photothermal dual-curing particle array anisotropic conductive film (experimental group) provided in the embodiments of this application is used to bond an LCD module and light up the screen (the red frame indicates the bonding area).

[0055] Figure 11 Optical micrographs of the photothermal dual-cured particle array anisotropic conductive film (experimental group) bonded to FPC and ITO in the embodiments of this application;

[0056] Figure 12 Optical micrograph of an anisotropic conductive adhesive film (control group A) with a single thermosetting agent bonded to FPC and ITO in an embodiment of this application;

[0057] Figure 13 Optical micrograph of an anisotropic conductive adhesive film (control group B) with a single photocurable agent bonded to FPC and ITO in an embodiment of this application;

[0058] Figure 14 The resistance values ​​of the anisotropic conductive adhesive film bonding FPC and ITO in the experimental group and control group provided in the embodiments of this application;

[0059] Figure 15 Peel force test curves and peel strength of anisotropic conductive adhesive films bonding FPC and ITO in the experimental and control groups provided in the embodiments of this application. Detailed Implementation

[0060] The embodiments of this application are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this application, and should not be construed as limiting this application.

[0061] In the description of this application, it should be understood that the terms "upper", "lower", "horizontal", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0062] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0063] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments.

[0064] Please see Figure 1 a and Figure 1 b The following is a flowchart of a method for preparing an anisotropic conductive adhesive film provided in this embodiment, specifically including the following steps S110 to S140. The specific implementation of each step is described in detail below.

[0065] Step S110: Obtain the array-distributed conductive microspheres.

[0066] In this embodiment, the step of obtaining the array-distributed conductive microspheres specifically includes the following steps S111 to S113, and the implementation of each step is described in detail below.

[0067] Step S111: Prepare a microporous array template.

[0068] In this embodiment, the step of preparing the microporous array template specifically includes the following steps: preparing the microporous array template by photolithography, laser etching, soft photolithography, screen printing, or electron beam lithography, wherein: the substrate used in preparing the microporous array template is a pure silicon substrate, a metal substrate, a ceramic substrate, or an organic substrate, the substrate is in the shape of a flat plate or a roller shape that can be used for continuous preparation, the micropore diameter D1 of the microporous array template is 150nm~150μm, and the pore depth H is 50nm~150μm.

[0069] In some specific embodiments, planar single-crystal silicon is used as the template substrate, and a microvia array is obtained using an industry-standard photolithography process. The microvia array has a hexagonal periodic pattern, with a pore diameter of 4 μm and a pore depth of 4 μm.

[0070] Step S112: Modify the surface of the microporous array template with a fluorine-containing organic surface modifier to obtain a microporous array template with low surface energy.

[0071] In this embodiment, the fluorinated organic surface modifier is a perfluorosilane, a perfluoropolyether, a perfluoropolyether alcohol, a perfluoropolyester, or an anti-fingerprint liquid, and the modification includes dip coating, spray coating, or scraping coating.

[0072] In some specific embodiments, the modifier used is a commercially available anti-fingerprint liquid, model H005 (Shenzhen Guanhong Technology Co., Ltd.), and a surface modification method of dip coating is adopted.

[0073] Step S113: Fill the micropores of the low surface energy micropore array template with conductive microspheres to obtain an array of conductive microspheres.

[0074] In this embodiment, the conductive microspheres include pure metal microspheres, carbon material microspheres, or organic microspheres with a metal layer coated on their surface. The filling method of the conductive microspheres includes scraping, spraying, or solution self-assembly.

[0075] Furthermore, the particle size D2 of the conductive microspheres is 100nm to 100μm, and D2 < D1, 0.5H < D2 < 1.5H, to ensure that the microspheres can fill the micropores and can be transferred from the micropores to the first resin film.

[0076] In some specific embodiments, the conductive microspheres used are gold-plated microspheres on the surface of organic microspheres with a particle size of about 3 μm. The microspheres are filled into the microporous template by a scraping method.

[0077] Step S120: Obtain the first layer of resin film with conductive microspheres distributed in the array.

[0078] In some embodiments, the step of obtaining the first layer of resin film with conductive microspheres distributed in an array specifically includes the following steps S121 to S122, and the implementation of each step is described in detail below.

[0079] Step S121: Coat the release film with acrylic resin to obtain an acrylic resin film.

[0080] In some embodiments, the acrylic resin comprises 0.5 to 20 parts by weight of a photoinitiator, 0.5 to 20 parts by weight of a thermal initiator, and 5 to 200 parts by weight of acrylate; wherein: the photoinitiator comprises one or a mixture of several alkyl benzophenones, benzoin derivatives, acylphosphides, benzoin and its derivatives, benzoin derivatives, benzophenones, thioxanthones, aromatic iodonium salts, alkyl iodonium salts, and cumeneferrocene hexafluorophosphate; the thermal initiator comprises... The acrylic resin includes one or a mixture of several of the following: persulfate, hydrogen peroxide, di-tert-alkyl peroxide, acyl peroxide, carboxylic acid ester, dicarbonate peroxide, azocyano, azonitro, azo ester, and azo hydroxyl; the acrylic resin includes one or a mixture of several of the following: epoxy acrylate, phosphate ester acrylate, polyester acrylate, polyurethane acrylate, polyether acrylate, monofunctional acrylate, difunctional acrylate, trifunctional acrylate, or polyfunctional acrylate.

[0081] Step S122: The acrylic resin film is coated onto the microporous array template. The conductive microspheres are transferred onto the acrylic resin film by peeling off the film, thereby obtaining a first layer of resin film with conductive microspheres distributed in an array.

[0082] In some embodiments, the thickness of the first resin film is 500 nm to 20 μm.

[0083] Step S130: Apply the second resin film onto the first resin film. In some embodiments, the step of applying the second resin film onto the first resin film specifically includes the following steps: applying the second resin film onto the first resin film and peeling off the release film on one side of the first resin film.

[0084] Specifically, the second resin film is prepared by coating a release film with a resin film. The thickness of the second resin film is 1 μm to 100 μm.

[0085] Furthermore, the release force of the release film on the first resin film side is less than the release force of the release film on the second resin film side.

[0086] In some specific embodiments, the release force of the release film on the first resin film side is 5-10g, and the release force of the release film on the second resin film side is 15-20g.

[0087] In some embodiments, the second resin film comprises a thermosetting resin, which includes epoxy resin or acrylic resin; wherein: the epoxy resin includes one or more of bisphenol A type epoxy resin, bisphenol F type epoxy resin, polyphenolic glycidyl ether epoxy resin, aliphatic glycidyl ether epoxy resin, glycidyl ester type epoxy resin, glycidyl amine type epoxy resin, epoxidized olefin compound, or heterocyclic and mixed type epoxy resin; the thermosetting agent of the epoxy resin includes conventional curing agents or latent curing agents, wherein the conventional curing agent includes one or more combinations of imidazole compounds, boron trifluoride complexes, organic acid anhydrides, polyamides, tertiary amines, aliphatic polyamines, alicyclic polyamines, aromatic polyamines, or their modified forms, and the latent curing agent includes melamine, microencapsulated imidazole, boron trifluoride amine, or modified amines. The acrylic resin comprises one or more combinations thereof, wherein the epoxy resin comprises 5 to 200 parts by weight, and the thermosetting agent of the epoxy resin comprises 0.5 to 20 parts by weight; the acrylic resin comprises one or more mixtures of epoxy acrylate, phosphate acrylate, polyester acrylate, polyurethane acrylate, polyether acrylate, monofunctional acrylate, difunctional acrylate, trifunctional acrylate, or polyfunctional acrylate; the thermosetting agent of the acrylic resin comprises one or more mixtures of persulfate, hydrogen peroxide, ditert-alkyl peroxide, acyl peroxide, carboxylic acid peroxide, dicarbonate peroxide, azocyanate, azonitro, azo ester, and azo hydroxyl groups, wherein the acrylic resin comprises 5 to 200 parts by weight, and the thermosetting agent of the acrylic resin comprises 0.5 to 20 parts by weight.

[0088] Step S140: Pre-curing treatment is performed on the first layer of resin film to obtain the anisotropic conductive film.

[0089] In some embodiments, the step of pre-curing the first layer of resin film to obtain the anisotropic conductive film specifically includes the following steps: irradiating the first layer of resin film with ultraviolet light from one side of the second layer of resin film to pre-cur the first layer of resin film and obtain the desired particle array type anisotropic conductive film.

[0090] Furthermore, the ultraviolet light intensity is 0.1–50 mW / cm². -2 The curing time is 1 second to 10 minutes.

[0091] The anisotropic conductive adhesive film preparation method and the anisotropic conductive adhesive film provided in this application involve obtaining an array of conductive microspheres, obtaining a first resin film containing the array of conductive microspheres, attaching a second resin film onto the first resin film, and pre-curing the first resin film to obtain the anisotropic conductive adhesive film. Pre-curing ensures that the array morphology of the conductive microspheres is initially fixed in the resin film. Thermal curing further ensures that the adhesive film achieves good bonding strength and conductivity during the bonding process. Compared with anisotropic conductive adhesive films using a single curing agent system, the obtained particle array-type anisotropic conductive adhesive film exhibits superior particle array arrangement, conductivity, and bonding strength when applied to bonding electrode components.

[0092] The technical solutions described above in this application will be explained in detail below with reference to specific embodiments.

[0093] Table 1. Resin composition and mass fraction of anisotropic conductive adhesive films

[0094]

[0095]

[0096] Example 1

[0097] This embodiment is the experimental group, namely the particle array type ACF film prepared based on photo- and heat-cured acrylic resin.

[0098] A microvia array was obtained using planar single-crystal silicon as the template substrate and industrial-standard photolithography and etching processes. The microvia array has a hexagonal periodic pattern, with microvia diameters of 4 μm and depths of 4 μm. Figure 2 and Figure 3 As shown, a microporous template was dipped in an anti-fingerprint liquid (model H005, Shenzhen Guanhong Technology Co., Ltd.) and its surface was modified to obtain a silicon-based template with a superhydrophobic surface. Figure 4 Then, the microspheres are filled into the microporous template using a scraping method. Figure 5 and Figure 6 The first layer of acrylic resin film was prepared according to the formulation of Example 1 in Table 1. This resin film contains both light and heat curing agents. The film was applied to the surface of a microporous template, and an array of conductive microspheres was transferred onto the first layer of acrylic resin film. Figure 7 The epoxy resin film was prepared according to the second layer resin film formulation of Example 1 in Table 1, and then laminated onto the first layer resin film. Finally, the acrylic resin film was pre-cured using ultraviolet light at an intensity of 20 mW cm⁻² for a curing time of 30–60 s. The final particle array type ACF film based on photo- and heat-cured acrylic resin was obtained. Figure 8 ).

[0099] Example 2

[0100] This example is control group A, which is an ACF film prepared based on a single thermosetting acrylic resin.

[0101] A microporous array was obtained using planar single-crystal silicon as the template substrate and industrial-standard photolithography and etching processes. The microporous array was a hexagonal periodic pattern with a pore diameter of 4 μm and a pore depth of 4 μm. The microporous template was coated with an anti-fingerprint liquid (model H005, Shenzhen Guanhong Technology Co., Ltd.) to modify its surface, resulting in a silicon-based template with a superhydrophobic surface. Microspheres were then filled into the microporous template using a blade coating method. A first layer of acrylic resin film containing a single thermosetting agent was prepared according to the formulation of Example 2 in Table 1. The film was applied to the surface of the microporous template, and the arrayed conductive microspheres were transferred onto the first layer of acrylic resin film. An epoxy resin film was prepared according to the formulation of the second layer of resin film in Example 2 in Table 1, and then coated onto the first layer of resin film. An ACF film based on a single thermosetting acrylic resin was obtained.

[0102] Example 3

[0103] This example is control group B, which is an ACF film prepared based on a single photocurable acrylic resin.

[0104] A microporous array was obtained using planar single-crystal silicon as the template substrate and industrial-standard photolithography and etching processes. The microporous array was a hexagonal periodic pattern with a pore diameter of 4 μm and a pore depth of 4 μm. The microporous template was coated with an anti-fingerprint liquid (model H005, Shenzhen Guanhong Technology Co., Ltd.) to modify its surface, resulting in a silicon-based template with a superhydrophobic surface. Microspheres were then filled into the microporous template using a blade coating method. A first layer of acrylic resin film containing a single photocuring agent was prepared according to the formulation of Example 3 in Table 1. The film was applied to the surface of the microporous template, and the arrayed conductive microspheres were transferred onto the first layer of acrylic resin film. An epoxy resin film was prepared according to the formulation of the second layer of resin film in Example 3 in Table 1 and then coated onto the first layer of resin film. Finally, the acrylic resin film was pre-cured using ultraviolet light at an intensity of 20 mW cm⁻² for a curing time of 30–60 s. An ACF film based on a single photocurable acrylic resin was obtained.

[0105] Example 4

[0106] A microporous array was obtained using a metal substrate as the template material and industrial-standard screen printing. The microporous array had a triangular periodic pattern, with a pore size of 150 nm and a pore depth of 50 nm. The microporous template was then impregnated with perfluorosilane and its surface modified to obtain a silicon-based template with a superhydrophobic surface. Microspheres were then sprayed into the microporous template.

[0107] An acrylic resin was prepared by mixing 0.5 parts by weight of an alkyl phenyl ketone, 0.5 parts by weight of an organic peroxide, and 5 parts by weight of an epoxy acrylate. The resin film was then applied to the surface of a microporous template, and an array of conductive microspheres was transferred onto the acrylic resin film to obtain a first resin film. A second resin film was prepared by mixing 5 parts by weight of bisphenol A epoxy resin and 0.5 parts by weight of an imidazole compound, and then coated onto the first resin film. Finally, the acrylic resin film was pre-cured using ultraviolet light at an intensity of 50 mW / cm². -2 The curing time is 1 second, based on a particle array type anisotropic conductive adhesive film with photothermal dual curing.

[0108] Example 5

[0109] A microporous array was fabricated using a ceramic substrate as the template material and employing industry-standard electron beam lithography. The microporous array has a triangular periodic pattern, with micropores having a diameter of 150 μm and a depth of 150 μm. The microporous template was then coated with perfluoropolyether and surface-modified to obtain a silicon-based template with a superhydrophobic surface. Microspheres were then filled into the microporous template using a solution self-assembly method.

[0110] An acrylic resin was prepared by mixing 20 parts by weight of benzoyl groups, 20 parts by weight of inorganic peroxides, and 200 parts by weight of phosphate ester-type acrylates. A film was then applied to the surface of a microporous template, and an array of conductive microspheres was transferred onto the acrylic resin film to obtain a first resin film. A second resin film was prepared by mixing 200 parts by weight of bisphenol F epoxy resin and 20 parts by weight of melamine, and then coated onto the first resin film. Finally, the acrylic resin film was pre-cured using ultraviolet light at an intensity of 0.1 mW / cm². -2 The curing time is 10 minutes. It is a particle array type anisotropic conductive adhesive film based on photothermal dual curing.

[0111] Example 6

[0112] Micropore arrays were fabricated using an organic substrate as the template material via industrial-standard electron beam lithography. The micropore arrays were square periodic patterns with pore diameters of 100 μm and depths of 100 μm. The micropore template was then coated with perfluoropolyether alcohol for surface modification, resulting in a silicon-based template with a superhydrophobic surface. Microspheres were then filled into the micropore template using a solution self-assembly method.

[0113] An acrylic resin was prepared by mixing 10 parts by weight of acylphosphide oxide, 10 parts by weight of azo compound, and 100 parts by weight of polyester acrylate. A film was then applied to the surface of a microporous template, and an array of conductive microspheres was transferred onto the acrylic resin film to obtain a first resin film. A second resin film was prepared by mixing 100 parts by weight of polyphenolic glycidyl ether epoxy resin and 10 parts by weight of microencapsulated imidazole, and then coated onto the first resin film. Finally, the acrylic resin film was pre-cured using ultraviolet light at an intensity of 10 mW / cm². -2 The curing time is 5 minutes. It is a particle array type anisotropic conductive adhesive film with photothermal dual curing.

[0114] Evaluation of the effects of the embodiments

[0115] Example 1 (experimental group) is a particle array-type ACF film prepared based on photo- and heat-cured acrylic resin. The use of photo- and heat-cured acrylic resin allows for stepwise curing of the acrylic acid. Pre-curing with ultraviolet light initially fixes the arrayed conductive particles onto the resin film, preventing damage to the particle array distribution due to resin melting and flow during subsequent heat pressing. Figure 9 The stepwise curing of the photothermal dual-curing acrylic resin was analyzed using DSC. The enthalpy change and curing rate data show that the acrylic resin in this formulation cured to varying degrees after both UV irradiation and heating.

[0116] The ACF film prepared in the examples was actually applied to the bonding of LCD modules, such as... Figure 10 The fact that the LCD screen can be lit up normally indicates that the prepared ACF film has good conductivity and adhesion properties.

[0117] The morphology of the ACF film bonded to the FPC and ITO electrodes was observed, such as... Figure 11 In Example 1 (experimental group), after hot pressing, thanks to the pre-curing effect of ultraviolet light irradiation, the particle array morphology was still maintained, and raised marks on the ITO were observed, indicating that the hot curing process provided good adhesion. Figure 12Example 2 (Control Group A): An ACF film prepared based on a single thermosetting acrylic resin. Because the array of conductive particles was not pre-cured, although thermosetting provided good adhesion (particle protrusions) after hot pressing, the orderly array pattern of the particles was destroyed, i.e., the particles were randomly distributed. This ACF film is not a particle array type ACF film. Figure 13 Example 3 (Control Group B): An ACF film prepared based on a single photocurable acrylic resin. UV pre-curing helps the array particles maintain their array shape after hot pressing, but no obvious particle protrusions were observed.

[0118] like Figure 14 and Figure 15 The resistance and peel strength of the ACF film after bonding in the embodiment were tested. The resistance was measured using the four-probe method. Figure 14 (As shown in the inset). The resistance of Example 1 (experimental group) and Example 2 (control group A) was 1.5–2.0 Ω, while the resistance of Example 3 (control group B) was approximately 3 Ω. The peel strength of Example 1 (experimental group) was approximately 9 N / cm, while the peel strength of Example 2 (control group A) and Example 3 (control group B) was approximately 4 N / cm. It can be seen that, compared with the control groups Example 2 and Example 3, the particle array type ACF film prepared by Example 1 (experimental group) based on photo- and heat-cured acrylic resin, when applied to the bonding experiment, achieved better conductivity and adhesive strength.

[0119] In summary, this invention provides a particle array-type anisotropic conductive adhesive film based on photothermal dual curing and its preparation method. The use of a photothermal dual-curing acrylic resin formulation firstly ensures the initial fixation of the conductive particle array morphology within the resin film through ultraviolet pre-curing, and then further ensures good adhesive strength and conductivity during the bonding process using thermal curing. Compared to anisotropic conductive adhesive films with a single curing agent system, the photothermal dual-curing ACF adhesive film exhibits superior particle array arrangement, conductivity, and adhesive strength.

[0120] It is understood that the technical features of the above embodiments can be combined arbitrarily. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0121] The above are merely preferred embodiments of this application, and only specifically describe the technical principles of this application. These descriptions are only for explaining the principles of this application and should not be construed as limiting the scope of protection of this application in any way. Based on this explanation, any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application, as well as other specific embodiments of this application that can be conceived by those skilled in the art without creative effort, should be included within the scope of protection of this application.

Claims

1. A method for preparing an anisotropic conductive adhesive film, characterized in that, Includes the following steps: Obtain an array of conductive microspheres; Obtain the first resin film in which conductive microspheres are distributed in an array; The second resin film is coated onto the first resin film; The first layer of resin film is pre-cured to obtain the anisotropic conductive film. The steps for obtaining the array-distributed conductive microspheres specifically include the following: Preparation of microporous array templates; The surface of the microporous array template is modified with a fluorine-containing organic surface modifier to obtain a microporous array template with low surface energy. Conductive microspheres are filled into each micropore of the low surface energy micropore array template to obtain an array of conductive microspheres. The steps for obtaining the first layer of resin film with conductive microspheres distributed in an array specifically include the following steps: Acrylic resin is coated onto a release film to obtain an acrylic resin film; The acrylic resin film is coated onto a microporous array template. By peeling off the film, conductive microspheres are transferred onto the acrylic resin film to obtain a first layer of resin film in which conductive microspheres are distributed in an array. The acrylic resin comprises 0.5 to 20 parts by weight of a photoinitiator, 0.5 to 20 parts by weight of a thermal initiator, and 5 to 200 parts by weight of an acrylic resin; wherein: The photoinitiators include one or a mixture of several of the following: alkyl phenyl ketones, benzoyl ketones, acyl phosphorus oxides, benzoin and its derivatives, benzoyl ketones, thioxanthones, aromatic iodonium salts, alkyl iodonium salts, and cumeneferrocene hexafluorophosphate. The thermal initiator includes one or a mixture of several of the following: persulfate, hydrogen peroxide, di-tert-alkyl peroxide, acyl peroxide, carboxylic acid ester peroxide, dicarbonate peroxide, azocyano, azonitro, azo ester, and azo hydroxy. The acrylic resins mentioned include one or a mixture of several types of epoxy acrylates, phosphate acrylates, polyester acrylates, polyurethane acrylates, polyether acrylates, monofunctional acrylates, or polyfunctional acrylates. The second resin film includes a thermosetting resin, which includes epoxy resin or acrylic resin. The step of pre-curing the first resin film to obtain the anisotropic conductive film specifically includes the following steps: The first layer of resin film is pre-cured by irradiating it with ultraviolet light from one side of the second layer of resin film to obtain the desired particle array anisotropic conductive film. The ultraviolet light intensity is 0.1–50 mW / cm². -2 The curing time is 1 second to 10 minutes.

2. The method for preparing the anisotropic conductive film as described in claim 1, characterized in that, The steps involved in preparing the microporous array template include the following: The microporous array template is prepared by photolithography, laser etching, soft photolithography, screen printing, or electron beam lithography. The substrate used in preparing the microporous array template is a pure silicon substrate, a metal substrate, a ceramic substrate, or an organic substrate. The substrate is in the shape of a flat plate or a roller shape that can be used for continuous preparation. The micropore diameter D1 of the microporous array template is 150 nm to 150 μm, and the pore depth H is 50 nm to 150 μm.

3. The method for preparing the anisotropic conductive adhesive film as described in claim 1, characterized in that, In the step of modifying the surface of the microporous array template with a fluorinated organic surface modifier to obtain a microporous array template with low surface energy, the fluorinated organic surface modifier is a perfluorosilane, a perfluoropolyether, a perfluoropolyether alcohol, a perfluoropolyester, or an anti-fingerprint liquid, and the modification includes dip coating, spray coating, or scraping coating.

4. The method for preparing the anisotropic conductive adhesive film as described in claim 1, characterized in that, In the step of filling conductive microspheres into the micropores of the low surface energy micropore array template to obtain an array of conductive microspheres, the conductive microspheres include pure metal microspheres, carbon material microspheres, or organic microspheres with a metal layer coated on their surface, and the filling method of the conductive microspheres includes scraping, spraying, or solution self-assembly.

5. The method for preparing the anisotropic conductive film as described in claim 2, characterized in that, The particle size D2 of the conductive microspheres is 100 nm to 100 μm, and D2 < D1, 0.5H < D2 < 1.5H.

6. The method for preparing the anisotropic conductive adhesive film as described in claim 1, characterized in that, The thickness of the first resin film is 500 nm to 20 μm.

7. The method for preparing the anisotropic conductive film as described in claim 1, characterized in that, The step of coating the second resin film onto the first resin film specifically includes the following steps: The second resin film is coated onto the first resin film, and the release film on one side of the first resin film is peeled off.

8. The method for preparing the anisotropic conductive adhesive film as described in claim 7, characterized in that, The second resin film is prepared by coating a release film with a resin film to obtain the second resin film.

9. The method for preparing the anisotropic conductive film as described in claim 8, characterized in that, The release force of the release film on the first resin film side is less than the release force of the release film on the second resin film side.

10. The method for preparing the anisotropic conductive adhesive film as described in claim 8, characterized in that, The thickness of the second resin film is 1μm to 100μm.

11. The method for preparing the anisotropic conductive film as described in claim 8, characterized in that, The epoxy resin includes one or more of the following: bisphenol A type epoxy resin, bisphenol F type epoxy resin, polyphenol type glycidyl ether epoxy resin, aliphatic glycidyl ether epoxy resin, glycidyl ester type epoxy resin, glycidyl amine type epoxy resin, epoxidized olefin compound, or heterocyclic and mixed type epoxy resin; the thermosetting agent of the epoxy resin includes conventional curing agents or latent curing agents, wherein the conventional curing agent includes one or more combinations of imidazole compounds, boron trifluoride complexes, organic acid anhydrides, polyamides, tertiary amines, aliphatic polyamines, alicyclic polyamines, aromatic polyamines, or their modifiers; the latent curing agent includes one or more combinations of melamine, microencapsulated imidazole, boron trifluoride amine, or modified amines; the epoxy resin is present in a mass fraction of 5 to 200 parts, and the thermosetting agent of the epoxy resin is present in a mass fraction of 0.5 to 20 parts. The acrylic resin includes one or a mixture of several of the following: epoxy acrylate, phosphate acrylate, polyester acrylate, polyurethane acrylate, polyether acrylate, monofunctional acrylate, or polyfunctional acrylate; the thermosetting agent of the acrylic resin includes one or a mixture of several of the following: organic peroxide, inorganic peroxide, or azo compound; the acrylic resin is present in a mass fraction of 5 to 200 parts, and the thermosetting agent of the acrylic resin is present in a mass fraction of 0.5 to 20 parts.

12. An anisotropic conductive adhesive film, characterized in that, It is prepared by the method for preparing anisotropic conductive adhesive film according to any one of claims 1 to 11.

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