Anisotropic conductive material and preparation method and application thereof

Abstract

The invention provides an anisotropic conductive material and a preparation method and application thereof.The anisotropic conductive material comprises a matrix layer and conductive particles existing in the matrix layer, the conductive particles are arranged in a single layer, the density of the conductive particles is larger than or equal to 20000 pcs / mm < 2 >, and the density of the conductive particles is larger than or equal to 20000 pcs / mm < 2 >. And meanwhile, the conductive particles are arranged in a single layer, so that the transverse insulativity is improved, and the transverse short circuit risk is reduced.

Description

Technical Field

[0001] The present invention relates to an anisotropic conductive material, a preparation method and an application thereof, and belongs to the technical field of conductive materials. Background Art

[0002] Conductive particles are distributed in the anisotropic conductive material, which is a commonly used material for connecting different electronic components. However, in the related art, when the density of the conductive particles is small, the conductivity in the vertical direction (longitudinal direction) is easily affected; while when the density of the conductive particles is high, these conductive particles are usually distributed in multiple layers in the anisotropic conductive material, resulting in poor transverse insulation when the anisotropic conductive material is applied to electrically connect different components. Summary of the Invention

[0003] The present invention provides an anisotropic conductive material, a preparation method and an application thereof, which can achieve a single-layer arrangement of high-density conductive particles, taking into account the improvement of the vertical conductivity and transverse insulation of the anisotropic conductive material, and effectively overcoming the defects existing in the prior art.

[0004] In one aspect of the present invention, there is provided an anisotropic conductive material, including a matrix layer and conductive particles present in the matrix layer, the conductive particles being arranged in a single layer, and the density of the conductive particles being greater than or equal to 20000 pcs / mm 2 .

[0005] According to an embodiment of the present invention, the density of the conductive particles is less than or equal to 280000 pcs / mm 2 .

[0006] According to an embodiment of the present invention, the particle size of the conductive particles is 0.5 μm to 50 μm.

[0007] According to an embodiment of the present invention, the matrix layer includes a first surface, and the distance between the conductive particles and the first surface is 1 to 5 μm.

[0008] According to an embodiment of the present invention, the matrix layer further includes a second surface opposite to the first surface, and the distance between the conductive particles and the second surface is 1 to 5 μm.

[0009] According to an embodiment of the present invention, the matrix layer includes a first resin layer, and the glass transition temperature or melting point of the first resin layer is greater than or equal to 20 °C.

[0010] According to an embodiment of the present invention, the matrix layer includes a first resin layer, and the first resin layer includes one or more of polyurethane, acrylic resin, epoxy resin, and copolymer resin, and the copolymer resin includes a copolymer of at least two of polyurethane, acrylate, and epoxy resin.

[0011] According to an embodiment of the present invention, it further includes an insulating layer provided on at least one surface of the substrate layer.

[0012] According to an embodiment of the present invention, the insulating layer includes a non-conductive adhesive.

[0013] On the other hand, the present invention also provides a method for preparing the above anisotropic conductive material, including the following steps: providing a first mixed solution for forming the substrate layer; coating the first mixed solution into a first wet film; drying the first wet film to obtain a first dry film; recoating the first mixed solution on the first dry film to form a second wet film; coating conductive particles on the second wet film and arranging the conductive particles in a single layer; then recoating the first mixed solution on the side of the second wet film coated with the conductive particles to form a third wet film on the side of the second wet film coated with the conductive particles; drying the third wet film to obtain a precursor film; performing biaxial stretching on the precursor film to obtain the anisotropic conductive material.

[0014] According to an embodiment of the present invention, it further includes: forming an insulating layer on at least one surface of the precursor film after the biaxial stretching to obtain the anisotropic conductive material.

[0015] On yet another aspect, the present invention also provides a connector including the above anisotropic conductive material.

[0016] According to an embodiment of the present invention, the connector includes a first electronic component and a second electronic component, and the first electronic component is connected to the second electronic component through the anisotropic conductive material.

[0017] According to an embodiment of the present invention, the first electronic component includes a display component, and the second electronic component includes an integrated circuit component.

[0018] In the anisotropic conductive material provided by the present invention, the density of the conductive particles is greater than or equal to 20000 pcs / mm 2 , which is beneficial to improving the vertical conductivity of the anisotropic conductive material. At the same time, these conductive particles are arranged in a single layer, which is beneficial to improving the lateral insulation and reducing the risk of lateral short circuit. Thus, the present invention can realize the single-layer arrangement of high-density conductive particles in the anisotropic conductive material, taking into account improving the vertical conductivity and lateral insulation of the anisotropic conductive material. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic cross-sectional structure diagram of the anisotropic conductive material in the x direction according to an embodiment of the present invention;

[0020] Figure 2Schematic cross-sectional structure diagram of the anisotropic conductive material according to an embodiment of the present invention in the y direction;

[0021] Figure 3 Schematic structure diagram of the connecting member according to an embodiment of the present invention;

[0022] Figure 4 SEM image of the precursor film in Example 1;

[0023] Figure 5 SEM image of the precursor film after biaxial stretching in Example 1;

[0024] Figure 6 SEM image of the precursor film after biaxial stretching in Example 2.

[0025] Explanation of reference numerals:

[0026] 1: Substrate layer;

[0027] 11: First region;

[0028] 12: Second region;

[0029] 13: Conductive particle layer;

[0030] 131: Conductive particle;

[0031] 2: Insulating layer;

[0032] 101: First surface;

[0033] 102: Second surface;

[0034] H0: Thickness of the conductive particle layer;

[0035] H1: Distance between the conductive particle and the first surface;

[0036] H2: Distance between the conductive particle and the second surface;

[0037] 3: First electronic component;

[0038] 31: First electrode;

[0039] 4: Second electronic component;

[0040] 41: Second electrode;

[0041] 10: Insulating filling part. Detailed implementation manners

[0042] To enable those skilled in the art to better understand the solution of the present invention, the present invention will be further described in detail below. The following specific embodiments are only used to describe the principles and features of the present invention, and the examples are only used to explain the present invention, not to limit the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0043] Conductive particles are distributed in the anisotropic conductive material, which is a commonly used material for connecting different electronic components. However, in the related art, when the density of conductive particles is small, it is easy to affect the conductivity in the vertical direction, which is not conducive to the conductive connection in the vertical direction; when the density of conductive particles is high, these conductive particles are usually distributed in multiple layers in the anisotropic conductive material, so that when the anisotropic conductive material is applied to electrically connect different components, the lateral insulation is poor, and short circuits and other phenomena are likely to occur.

[0044] Specifically, an anisotropic conductive film (ACF) is a common anisotropic conductive material, which can be mainly formed by a curable resin adhesive and conductive particles dispersed in the curable resin adhesive, and can be used to connect electronic components (such as a circuit board). These electronic components usually have multiple terminals, and the anisotropic conductive film (or anisotropic conductive adhesive) can electrically connect different electronic components through the terminals of each electronic component.

[0045] For example, the methods of mounting a driver integrated circuit (driver IC) on a liquid crystal or organic light-emitting diode display panel (glass panel) can be roughly divided into a chip-on-glass (COG) mounting method and a chip-on-flex (COF) mounting method. Among them, in the COG mounting method, an anisotropic conductive adhesive containing conductive particles is mainly used to directly bond the driver IC to the display panel. In the COF mounting method, the driver IC is mainly bonded to a flexible carrier with metal wiring, and then an anisotropic conductive adhesive containing conductive particles is used to bond it to the display panel.

[0046] In recent years, electronic products (such as mobile display devices, etc.) have been developing towards miniaturization and high resolution, requiring the reduction of the connection area of each terminal in electronic components, and at the same time, the number of terminals per unit area of electronic components increases, that is, the distance between adjacent terminals in electronic components is reduced. In order to join circuit components with such narrow line widths between adjacent terminals to each other through anisotropic conductive adhesive, and ensure conductivity by having a sufficient amount of conductive particles in between, it is necessary to increase the addition density of conductive particles in the anisotropic conductive adhesive. However, if the density of conductive particles in the anisotropic conductive adhesive is increased, particle aggregation is likely to occur between adjacent terminals, resulting in a risk of short circuit and poor lateral insulation.

[0047] In view of this, an embodiment of the present invention provides an anisotropic conductive material, including a matrix layer 1 and conductive particles 131 existing in the matrix layer 1. The conductive particles 131 are arranged in a single layer, and the density of the conductive particles 131 is greater than or equal to 20000 pcs / mm 2 .

[0048] The anisotropic conductive material of the embodiment of the present invention has the characteristics of high density of conductive particles 131, single-layer arrangement, uniform and single dispersion (the single-particle dispersion rate of the conductive particles 131 can be greater than 90%). The high-density conductive particles 131 are beneficial to improving the vertical conductivity of the anisotropic conductive material. At the same time, these conductive particles 131 are arranged in a single layer and evenly distributed, which can improve the capture rate and lateral insulation, and reduce the risk of lateral short circuit.

[0049] Thus, the embodiment of the present invention can achieve the single-layer arrangement of high-density conductive particles 131 in the anisotropic conductive material, taking into account the improvement of the vertical conductivity and lateral insulation of the anisotropic conductive material. This anisotropic conductive material can be used for electrical connection between electronic components, such as connecting a driving IC to a display panel through a COG mounting method, or connecting a flexible carrier tape with metal wiring joined with a driving IC to a display panel through a COF mounting method, etc. In particular, it can be applied to the connection of electronic components with narrow line widths between adjacent terminals, which is beneficial to the high resolution, fine circuit and miniaturization of electronic products such as mobile display devices.

[0050] Specifically, as Figure 1 and Figure 2 shown, a plurality of conductive particles 131 are distributed in the matrix layer 1. These conductive particles 131 are dispersed in the matrix layer 1 and arranged in a single layer in the matrix layer 1, that is, arranged in a layer on the x-y plane (hereinafter referred to as this layer as the conductive particle layer 13, and the plane where the conductive particle layer 13 is located is parallel to the x-y plane), and do not overlap with each other in the z-axis direction.

[0051] Refer to Figure 1 and Figure 2, the x-y plane direction is parallel to the x direction and the y direction and perpendicular to the z direction (i.e., the z-axis direction), and the z direction can be the thickness direction of the base layer 1.

[0052] Among them, "anisotropic" means that conductivity is brought about in the z-axis direction (vertical direction) through the conductive particles 131, and it is insulated in the x-y plane direction (lateral direction). That is, the anisotropic conductive material is a material in which conductive particles (conductive grains) 131 are dispersed, conductive in the z-axis direction, and insulated in the x-y plane direction.

[0053] Reference Figures 1 to 3 , in specific implementation, the anisotropic conductive material can be placed between two electronic components, and then the two electronic components are pressurized in the z-axis direction (i.e., the two electronic components are pressed together), specifically, it can be thermally pressed, so as to electrically connect the two electronic components through the anisotropic conductive material. Both of the two electronic components have a plurality of terminals (electrode bumps). After the connection is completed, the terminals of the two electronic components correspond one by one, and the terminals of one electronic component and the terminals of the other electronic component are connected through the conductive particles 131, and the material of the base layer 1 fills the gaps between the terminals, so as to insulate adjacent two terminals (or circuits) in the lateral direction, maintain the lateral insulation property, and avoid phenomena such as short circuit.

[0054] By using the anisotropic conductive material of the embodiment of the present invention, the capture rate of the conductive particles 131 can reach more than 30% to 90% after pressing. Even when the pitch between adjacent terminals of the electronic component is reduced, more conductive particles can be pressed between the electrode bumps to achieve good conductivity in the vertical direction, and at the same time, reduce the situation that the conductive particles 131 under the electrode bumps move to between the two electrode bumps in the lateral direction during the pressing process, thereby improving the lateral insulation performance.

[0055] After further research, in the above anisotropic conductive material, the density of the conductive particles 131 is lower than 280000 pcs / mm 2 , which is beneficial to further taking into account improving the lateral insulation and longitudinal conductivity of the anisotropic conductive material.

[0056] In addition, the particle size of the conductive particles 131 can be 0.5 μm to 50 μm, such as 0.5 μm, 1 μm, 3 μm, 5 μm, 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm or the range composed of any two of them, which is beneficial to realizing the single-layer close-packed and equal-distribution state of the conductive particles 131 in the base layer 1 and further optimizing the performance of the anisotropic conductive material.

[0057] Specifically, the conductive particles 131 may include a metal, such as one or more of gold (Au), silver (Ag), nickel (Ni), copper (Cu), lead (Pb), etc., but are not limited thereto, and may also be other conventional conductive particles in the art.

[0058] Generally, the above-mentioned anisotropic conductive material may include an anisotropic conductive adhesive, specifically an anisotropic conductive film. The matrix layer 1 is mainly formed of an insulating adhesive. During the process of pressing two electronic components, the insulating adhesive will fill the gaps between the terminals to maintain lateral insulation.

[0059] Generally, the matrix layer 1 includes a first resin layer, and the glass transition temperature (Tg) or melting point (Tm) of the first resin layer is greater than or equal to 20 °C, specifically greater than or equal to room temperature.

[0060] Specifically, the first resin layer includes a first resin material, and the first resin material may specifically include a resin adhesive, which enables the anisotropic conductive material (anisotropic conductive adhesive) to have adhesive properties and is conducive to the bonding between electronic components.

[0061] Among them, the glass transition temperature (Tg) or melting point (Tm) of the first resin material is greater than or equal to 20 °C, specifically greater than or equal to room temperature, so that the glass transition temperature (Tg) or melting point (Tm) of the first resin layer is greater than or equal to 20 °C, specifically greater than or equal to room temperature. Using this first resin material as the material of the matrix layer 1 is conducive to further improving the performance of the anisotropic conductive material, and at the same time facilitates the preparation of the anisotropic conductive material. For example, the anisotropic conductive material can be prepared by a stretching method (such as a biaxial stretching method). By using this first resin material, it is convenient for shaping after stretching, improving the preparation efficiency and performance of the anisotropic conductive material.

[0062] Specifically, the first resin layer (first resin material) may include one or more of polyurethane, acrylic resin, epoxy resin, and copolymer resin, that is, one of them can be selected, or a mixture of at least two of them can be selected. The glass transition temperature or melting point of these resin materials is greater than or equal to 20 °C, specifically greater than or equal to room temperature.

[0063] Among them, the copolymer resin may include a copolymer of at least two of polyurethane, acrylate, and epoxy resin, that is, the copolymer resin may be a hybrid resin material prepared based on at least two of polyurethane, acrylate, epoxy resin, etc. For example, the copolymer resin may include one or more of polyurethane acrylate resin, epoxy acrylate resin, and polyurethane epoxy resin.

[0064] Generally, the above-mentioned polyurethane can be synthesized from long-chain diols and diisocyanates, and it has a soft segment composed of long-chain diols and a hard segment composed of diisocyanates. Among them, the soft segment can be composed of long-chain diols with crystallinity and / or long-chain diols without crystallinity. Examples of long-chain diols with crystallinity include one or more of polyester diols, polycarbonate diols, and polyolefin diols. Examples of long-chain diols without crystallinity include polyester diols, polyether diols, etc. The diisocyanates can include one or more of toluene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, diphenylmethane diisocyanate, etc.

[0065] In addition, the above-mentioned acrylic resin can include homopolymers and / or copolymers. Homopolymers, for example, include homopolymers of methacrylate or acrylate (i.e., homopolymers can be formed by homopolymerization of methacrylate or acrylate monomers). Copolymers, for example, include copolymers of ester monomers and styrene monomers (i.e., copolymers can be formed by copolymerization of monomer components containing at least these two types of monomers). Ester monomers can include methacrylate and / or acrylate, and styrene monomers can include styrene and / or methylstyrene, etc.

[0066] In addition, the above-mentioned epoxy resin can include high-molecular-weight epoxy resins synthesized from polyamine materials and epoxy resin materials (such as bisphenol A epoxy resin, etc.). It has a soft segment formed by polyamine materials and a hard segment formed by conventional epoxy resin materials. The properties of the synthesized epoxy resin are regulated by these two materials. For example, the soft segment can make the synthesized epoxy resin have good tensile properties, and the hard segment can control the tensile strength of the epoxy resin, etc. Among them, the polyamine materials can include polyetheramine and / or polyesteramine.

[0067] In some specific embodiments, the first resin material includes polyurethane and / or acrylic resin. The first resin material also includes low-molecular-weight epoxy resin and / or polyurethane prepolymer. That is, at this time, the first resin material is a mixture of multiple polymers, such as a mixture of polyurethane and low-molecular-weight epoxy resin, or a mixture of acrylic resin and polyurethane prepolymer, etc.

[0068] In the above-mentioned anisotropic conductive material, the conductive particles 131 are embedded in the matrix layer 1 and arranged in a single layer within the matrix layer 1. Refer to Figure 1 and Figure 2 , the matrix layer 1 (the first resin layer) includes a first region 11, a conductive particle layer 13, and a second region 12 that are sequentially stacked. The first region 11 and the second region 12 are regions of the matrix layer 1 where the conductive particles 131 are not distributed.

[0069] Specifically, the first region 11 is a first resin layer formed of a first resin material, the second region 12 is a first resin layer formed of a first resin material, and the conductive particle layer 13 includes a first resin layer formed of a first resin material and conductive particles 131 embedded in the first resin layer. That is, in the conductive particle layer 13, the first resin material (first resin layer) fills the gaps between every two adjacent conductive particles, and the thickness H0 of the conductive particle layer 13 is substantially equal to the particle diameter (diameter) of the conductive particles 131.

[0070] Among them, the first resin materials in the first region 11 and the conductive particle layer 13 may be the same or different, the first resin materials in the second region 12 and the conductive particle layer 13 may be the same or different, and the first resin materials in the first region 11 and the second region 12 may be the same or different. Exemplarily, the first resin materials in the first region 11, the conductive particle layer 13, and the second region 12 are all the same.

[0071] Specifically, the substrate layer 1 has opposite first surface 101 and second surface 102. The direction from the first surface 101 to the second surface 102 is parallel to the thickness direction of the substrate layer 1. The first surface 101 is the side of the first region 11 facing away from the second region 12, and the second surface 102 is the side of the second region 12 facing away from the first region 11.

[0072] Among them, the distance between the conductive particles 131 and the first surface 101 (i.e., the thickness of the first region 11) H1 can be 1 to 5 μm, such as 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, or any range composed of any two of them.

[0073] In addition, the distance between the conductive particles 131 and the second surface 102 (i.e., the thickness of the second region 12) H2 can be 1 to 5 μm, such as 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, or any range composed of any two of them. Among them, the distance H1 between the conductive particles 131 and the first surface 101 and the distance H2 between the conductive particles 131 and the second surface 102 can be equal or unequal.

[0074] Continue to refer to Figure 1 and Figure 2 ., the above anisotropic conductive material may further include an insulating layer 2 provided on at least one side surface of the substrate layer 1, which can further improve the performance such as the lateral insulation of the anisotropic conductive material. Among them, the substrate layer 1 and the insulating layer 2 are stacked, and the direction from the substrate layer 1 to the insulating layer 2, the thickness direction of the substrate layer 1, the thickness direction of the insulating layer 2, the thickness direction of the anisotropic conductive material, and the direction from the first region 11 to the second region 12 are parallel to each other.

[0075] Specifically, the insulating layer 2 may include a second resin layer formed of a second resin material. The second resin material in the insulating layer has adhesiveness with the first resin material in the base layer (ACF layer), so that the insulating layer and the base layer have good adhesiveness. Specifically, the insulating layer 2 may include a non-conductive film (NCF), that is, the insulating layer 2 may be an NCF layer that does not contain conductive particles 131, and it may be formed of conventional materials in the art.

[0076] An embodiment of the present invention also provides a method for preparing the above anisotropic conductive material, including the following steps: providing a first mixed solution for forming the base layer 1; coating the first mixed solution into a first wet film; drying the first wet film to obtain a first dry film; coating the first mixed solution again on the first dry film to form a second wet film; coating conductive particles 131 on the second wet film and arranging the conductive particles 131 in a single layer; then coating the first mixed solution again on the side of the second wet film coated with the conductive particles 131 to form a third wet film on the side of the second wet film coated with the conductive particles 131; drying the third wet film to obtain a precursor film; and performing biaxial stretching on the precursor film to obtain the anisotropic conductive material.

[0077] During specific implementation, the conductive particles 131 can be dispersed in an organic solvent to prepare a coating solution, and then it is coated on the second wet film, generally coated at least twice, so that there is basically no gap between the conductive particles 131, and the conductive particles 131 are arranged in a single layer.

[0078] Specifically, the thickness of the second wet film may be less than the particle size of the conductive particles 131.

[0079] Specifically, the thickness of the precursor film may be 5 - 100 μm, such as 5 μm, 10 μm, 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm or the range composed of any two of them.

[0080] Generally, when performing biaxial stretching on the precursor film, the stretching ratio (that is, the ratio of the length of the precursor film after biaxial stretching to the length of the precursor film before stretching) may be greater than or equal to λ, λ = D / d, d represents the particle size of the conductive particles 131, and D represents the average spacing of the conductive particles 131 in the precursor film after biaxial stretching.

[0081] Specifically, when performing biaxial stretching on the precursor film, the stretching ratio may be 1.5 - 4, such as 1.5, 1.7, 1.9, 2, 2.3, 2.5, 2.8, 3, 3.3, 3.5, 3.8, 4 or the range composed of any two of them. That is, the precursor film can be stretched by 50% - 300%.

[0082] In addition, when the precursor film is biaxially stretched, the stretching rate can be 15% / s to 25% / s, such as 15% / s, 18% / s, 20% / s, 23% / s, 25% / s, or a range composed of any two of them. Herein, the stretching rate refers to the ratio of the length stretched per second to the length before stretching. For example, a stretching rate of 20% means that 20% of the length is stretched per second.

[0083] In the embodiment of the present invention, by biaxially stretching the precursor film having the conductive particles 131 arranged in a single layer, the spacing between the conductive particles 131 can be controlled by the stretching ratio, so as to realize the single-layer controllable arrangement of the conductive particles 131 by the biaxial stretching method, and an anisotropic conductive material is prepared. The preparation method of the embodiment of the present invention can realize the single-layer close arrangement and single-particle dispersion state of the conductive particles 131 in the matrix layer 1, and can avoid phenomena such as the absence and multi-layer distribution of the conductive particles 131, so that the anisotropic conductive material has both good vertical conductivity and lateral insulation.

[0084] Specifically, biaxial stretching is performed above the glass transition temperature or melting point of the first resin material (that is, the temperature during stretching is greater than the glass transition temperature or melting point of the first resin material), which is beneficial to ensuring a high stretching ratio and facilitating biaxial stretching. After stretching, the temperature is lowered below the glass transition temperature for crosslinking and shaping.

[0085] Generally, the matrix layer 1 can have a crosslinked structure formed by components such as the first resin material, which is beneficial to improving the capture rate of the conductive particles 131 when the anisotropic conductive material is applied.

[0086] Specifically, the first resin material has good crosslinking performance to facilitate the formation of a crosslinked structure. As described above, the first resin material may specifically include one or more of polyurethane, acrylic resin, epoxy resin, copolymer resin, etc.

[0087] When a copolymer resin is used, the crosslinking after stretching can be achieved by introducing an appropriate amount (usually a small amount) of crosslinking groups that can undergo subsequent reactions into the resin, which is beneficial to resin crosslinking and forms a matrix layer 1 with a crosslinked structure. Among them, the crosslinking groups include, for example, one or more of carboxyl group, hydroxyl group, epoxy group, amino group, etc.

[0088] When an epoxy resin (such as the aforementioned high molecular weight epoxy resin) is used, the crosslinking after stretching can be achieved through paths such as synthesizing terminal epoxy groups, forming hydroxyl groups after ring opening of epoxy groups, and crosslinking through hydroxyl groups.

[0089] When an acrylic resin is used, post-stretching crosslinking can be achieved by introducing an appropriate amount (usually a small amount is sufficient) of functional monomers into the acrylic resin. Examples of the functional monomers used include one or more of acrylic acid, methacrylic acid, hydroxyethyl acrylate, glycidyl methacrylate, glycidyl acrylate, and isocyanate-containing acrylates, etc.

[0090] When a polyurethane resin is used, post-stretching crosslinking can be achieved by means such as the reaction of a curing agent containing carboxyl and / or epoxy groups introduced into the synthesized polyurethane, the moisture curing reaction of terminal isocyanate, and the water curing reaction after being capped with a silane coupling agent, etc.

[0091] When a mixture of polyurethane and / or acrylic resin with low molecular weight epoxy resin and / or polyurethane prepolymer is used, the polyurethane and / or acrylic resin can provide film-forming and stretching properties, and the low molecular weight epoxy resin and / or polyurethane prepolymer can control the viscosity of the mixture, stretching properties, and crosslinking reaction sites after stretching. The crosslinking after stretching can be achieved by the low molecular weight epoxy resin and / or polyurethane prepolymer.

[0092] In some embodiments, the first resin material includes a polyurethane resin, and its preparation process may include: melting polyethylene adipate glycol (PBA) (specifically, it can be melted at about 60°C ± 2°C), then mixing it with hexamethylene diisocyanate (HDI) and a catalyst, and then reacting at 55°C to 65°C (such as 60°C) for 0.8 h to 1.2 h (such as 1 h), then adding dimethylacrylamide (DMF) thereto, and then raising the temperature to 75°C to 85°C (such as 80°C) and continuing to react for 3.5 h to 4.5 h (such as 4 h), and then cooling to room temperature to obtain the polyurethane resin.

[0093] Among them, the mass ratio of PBA to HDI can be 40:(3 - 3.5), for example, about 40:3.2; the mass ratio of PBA to DMF can be 40:(19 - 20), for example, about 40:19.8.

[0094] Among them, the catalyst can include dibutyltin dilaurate catalyst. Specifically, a drop of dibutyltin dilaurate catalyst can be added to the system to catalyze the above reaction.

[0095] In addition, the preparation process of the above anisotropic conductive material may further include: forming an insulating layer on at least one surface of the precursor film after biaxial stretching to obtain the anisotropic conductive material.

[0096] Among them, the second resin material for forming the insulation can be dissolved in an organic solvent to prepare a second mixed solution, then coated on the surface of the precursor film after biaxial stretching, and then after drying and other treatments, an insulating layer (second resin layer) is formed.

[0097] In specific implementation, the material for forming the insulating layer (such as the second resin material) can be mixed with a solvent to prepare an NCF coating solution. Then, the NCF coating solution is coated on the surface of the pre-stretched precursor film, and after drying and other treatments, an insulating layer is formed on the surface of the precursor film to obtain an anisotropic conductive material. Or, an insulating layer (or insulating film or NCF film) is first prepared, and then the insulating layer is laminated with the pre-stretched precursor film to obtain an anisotropic conductive material.

[0098] In some embodiments, the preparation process of the insulating film is as follows: A phenoxy resin, an alicyclic epoxy, and a solvent are mixed to obtain a mixed solution. Then, the mixed solution is coated on a release film (such as a polyethylene terephthalate (PET) film treated with release treatment), and then dried. Specifically, drying can be carried out at 70°C to 90°C (such as 80°C) to form an insulating film on the release film.

[0099] Specifically, in the above preparation process of the insulating film, the solvent used can include organic solvents, specifically including toluene and / or methyl ethyl ketone.

[0100] In addition, in the above preparation process of the insulating film, the mass ratio of the phenoxy resin to the alicyclic epoxy can be 1:(0.8 - 1.2), for example, 1:1.

[0101] In addition, in the above preparation process of the insulating film, a catalyst can also be introduced into the mixed solution (that is, the phenoxy resin, the alicyclic epoxy, the catalyst, and the solvent are mixed to obtain a mixed solution). Specifically, a cationic catalyst can be introduced, and the mass of the catalyst can be 3% - 7% (such as 5%) of the sum of the masses of the phenoxy resin and the alicyclic epoxy.

[0102] An embodiment of the present invention also provides a connector, including the above anisotropic conductive material.

[0103] Specifically, as Figure 3 shown, the connector includes a first electronic component 3 and a second electronic component 4, and the first electronic component 3 is connected to the second electronic component 4 through the anisotropic conductive material.

[0104] Specifically, the first electronic component 3 includes a first electrode 31 (electrode bump), the second electronic component 4 includes a second electrode 41 (electrode bump), and the first electrode 31 of the first electronic component 3 is electrically connected to the second electrode 41 of the second electronic component 4 through the conductive particles 131 in the anisotropic conductive material.

[0105] Generally, the first electronic component 3 has a plurality of first electrodes 31, the second electronic component 4 has a plurality of second electrodes 41, and the first electrodes 31 of the first electronic component 3 and the first electrodes 31 of the second electronic component 4 are in one-to-one correspondence, that is, one first electrode 31 is connected to one second electrode 41.

[0106] Continue to refer to Figure 3 The above-mentioned connecting member further includes an insulating filling portion 10 filled in the gap between the first electronic component 3 and the second electronic component 4. The insulating filling portion 10 is mainly formed of an insulating material in the anisotropic conductive material (such as the first resin material forming the base layer 1, the second resin material forming the insulating layer 2, etc.), which can prevent lateral conduction between multiple first electrodes 31 on the first electronic component 3 and lateral conduction between multiple second electrodes 41 on the second electronic component 4, etc.

[0107] Specifically, the first electronic component 3 includes a display component (display module), and the second electronic component 4 includes an integrated circuit component (driver IC).

[0108] Exemplarily, the above-mentioned connecting member can be a display device such as a display panel (display).

[0109] The present invention will be further introduced below through specific embodiments.

[0110] In the following embodiments, the NCF film used was prepared according to the following process: 50 g of phenoxy resin, 50 g of alicyclic epoxy, and 5 g of cationic catalyst were placed in a mixed solvent of toluene and methyl ethyl ketone (mixing ratio 1:1) to obtain a mixed solution with a solid content of 50%; the mixed solution was coated on a PET film that had been subjected to release treatment, and then dried into a film at 80 °C to obtain the NCF film.

[0111] In the following embodiments, the particle size of the conductive particles was 3.5 μm.

[0112] Example 1

[0113] 1. Synthesis of polyurethane resin

[0114] 40 g of polyethylene adipate glycol (PBA) was added to a flask and melted at 60 °C. Then, 3.2 g of hexamethylene diisocyanate (HDI) and one drop of dibutyltin dilaurate catalyst were added thereto. After reacting at 60 °C for 1 h, 19.8 g of dimethylacrylamide (DMF) was added thereto, and then the temperature was raised to 80 °C and the reaction was continued for 4 h. After cooling to room temperature, polyurethane resin was synthesized (the whole system was a polyurethane resin solution).

[0115] 2. Preparation of precursor film

[0116] On a release-treated polyethylene terephthalate (PET) film, the polyurethane resin solution was coated to form a first wet film with a thickness of 20 μm;

[0117] The first wet film was dried at 80 °C to form a first dry film;

[0118] A layer of polyurethane resin solution is further coated on the first dry film to form a second wet film with a thickness of 2 μm;

[0119] Conductive particles are coated on the second wet film in a single layer, and the coating is repeated twice so that there are basically no gaps between the conductive particles and the conductive particles are arranged in a single layer;

[0120] The polyurethane resin solution is coated again on the side of the second wet film coated with conductive particles to form a third wet film with a thickness of 20 μm; then it is dried at 80 °C to obtain a precursor film (the scanning electron microscope (SEM) image of this precursor film is shown in Figure 4 , the conductive particles are closely arranged in a single layer, where the density of the conductive particles is 91,200 pcs / mm 2 , the theoretical density is 94,600 pcs / mm 2 , and the vacancy rate (the area ratio of the area where the conductive particles do not exist) is about 3.6%);

[0121] A two-way stretcher is used to perform two-way stretching on the precursor film at a rate of 20% / s, and the stretching ratio is 1.7 to obtain a precursor film after two-way stretching (i.e., the ACF film, and its SEM image is shown in Figure 5 , where the conductive particles are arranged in a single layer, and the density of the conductive particles is 31,300 pcs / mm 2 );

[0122] The NCF film is bonded to the precursor film after two-way stretching to obtain an anisotropic conductive material.

[0123] Example 2

[0124] The difference between this Example 2 and Example 1 is that when the precursor film is subjected to two-way stretching, the stretching ratio is 1.9; the other conditions are the same as those in Example 1.

[0125] In this Example 2, the SEM image of the precursor film (ACF film) after two-way stretching is shown in Figure 6 , where the conductive particles are arranged in a single layer, and the density of the conductive particles is 21,200 pcs / mm 2 .

[0126] In the above embodiments, conductive particles with a smaller particle size are used to achieve a single-layer arrangement with a high density of conductive particles. This can improve the capture rate of conductive particles when applying anisotropic conductive materials, ensure that a sufficient number of conductive particles are pressed by the electrode bumps in the case of a small pitch, and achieve good vertical conductivity. At the same time, the conductive particles are arranged in a single layer and are uniformly and singly dispersed in the matrix layer (ACF film) (the single-particle dispersion rate of the conductive particles 131 is greater than 90%). This can reduce the usage amount of conductive particles and lower the cost. At the same time, during the pressing process, the situation where the conductive particles under the electrode bumps move to the gap between the two electrode bumps in the lateral direction can be reduced, thereby improving the lateral insulation performance and reducing the risk of lateral conduction caused by the connection of the two electrode bumps in the lateral direction through the conductive particles.

[0127] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. An anisotropic conductive material, characterized in that, It includes a substrate layer and conductive particles present in the substrate layer. The conductive particles are arranged in a single layer, and the density of the conductive particles is greater than or equal to 20000 pcs / mm 2 .

2. The anisotropic conductive material according to claim 1, wherein The density of the conductive particles is less than or equal to 280000 pcs / mm 2 .

3. The anisotropic conductive material according to claim 1, wherein The particle size of the conductive particles is 0.5 μm to 50 μm.

4. The anisotropic conductive material according to claim 1, characterized in that, The substrate layer includes a first surface, and the distance between the conductive particles and the first surface is 1 to 5 μm.

5. The anisotropic conductive material according to claim 4, wherein The substrate layer further includes a second surface opposite to the first surface, and the distance between the conductive particles and the second surface is 1 to 5 μm.

6. The anisotropic conductive material according to claim 1, wherein The substrate layer includes a first resin layer, and the glass transition temperature or melting point of the first resin layer is greater than or equal to 20 °C.

7. The anisotropic conductive material according to any one of claims 1-6, characterized in that, The substrate layer includes a first resin layer, and the first resin layer includes one or more of polyurethane, acrylic resin, epoxy resin, and copolymer resin. The copolymer resin includes a copolymer of at least two of polyurethane, acrylate, and epoxy resin.

8. The anisotropic conductive material according to any one of claims 1-6, characterized in that An insulating layer is further provided on at least one side surface of the substrate layer.

9. The anisotropic conductive material according to claim 8, wherein The insulating layer includes non-conductive glue.

10. A method for preparing an anisotropic conductive material according to any one of claims 1-9, characterized in that, It includes the following steps: Providing a first mixed solution for forming the substrate layer; Coating the first mixed solution into a first wet film; Drying the first wet film to obtain a first dry film; Coating the first mixed solution again on the first dry film to form a second wet film; Coating conductive particles on the second wet film and arranging the conductive particles in a single layer; Then coating the first mixed solution again on the side of the second wet film coated with the conductive particles to form a third wet film on the side of the second wet film coated with the conductive particles; Drying the third wet film to obtain a precursor film; Biaxially stretching the precursor film to obtain the anisotropic conductive material.

11. The preparation method according to claim 10, characterized in that, It further includes: Forming an insulating layer on at least one side surface of the precursor film after the biaxial stretching to obtain the anisotropic conductive material.

12. A connecting piece, characterized in that, It includes the anisotropic conductive material according to any one of claims 1-9.

13. The connector according to claim 12, characterized in that, The connector includes a first electronic component and a second electronic component, and the first electronic component is connected to the second electronic component through the anisotropic conductive material.

14. The connecting member according to claim 13, characterized in that, The first electronic component includes a display component, and the second electronic component includes an integrated circuit component.

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