Anisotropic conductive film based on porous metal conductive microspheres and method for manufacturing the same

Abstract

The application discloses an anisotropic conductive film based on porous metal conductive microspheres, which comprises the following raw materials: resin, latent curing agent or / and curing agent, defoaming agent and porous metal conductive microspheres. The conductive film comprises the following raw materials by weight: 100 parts of resin, 3-10 parts of latent curing agent, 1-10 parts of curing agent, 3-15 parts of defoaming agent and 4-25 parts of porous metal conductive microspheres; in particular, the porous gold conductive microspheres account for 7-20 wt% of the weight of the resin matrix. The preparation method comprises the following steps: 1) preparing alloy micro powder; 2) preparing alloy microspheres; 3) sorting the alloy microspheres; and 4) preparing porous metal conductive microspheres. Compared with the composite conductive microspheres widely used in the anisotropic conductive film at present, the porous metal conductive microspheres have a large compression deformation rate, guarantee a large contact area and good conductive performance, and can meet the wide application in the electronic packaging field.

Description

TECHNICAL FIELD

[0001] The present application relates to anisotropic conductive film for ultra-fine electrode connection and its preparation method, and belongs to the field of electronic packaging materials. BACKGROUND

[0002] Anisotropic conductive film (ACF for short) is widely used in the field of electrical connection between microelectrodes of electronic devices, which is mainly composed of insulating resin binder and conductive filler dispersed in the insulating resin binder. The anisotropic conductive function of the conductive film is closely related to the conductive filler existing therein, and the performance of the conductive filler determines the conductivity and durability of the anisotropic conductive film. From the development of the anisotropic conductive film, the conductive fillers that can be used include carbon particles such as carbon black and graphite, metal particles such as copper, nickel, silver, and gold, and polymer composite conductive microspheres with a metal layer plated on the surface. Carbon particles have very small deformation during hot pressing, and only point contact between electrodes, so the conductivity is poor. Metal particles are similar to carbon particles, except that they have small deformation during hot pressing and poor conductivity, and their large bulk density makes them prone to sinking and uneven distribution when mixed with the resin binder. The performance of the composite conductive microspheres is better than that of carbon particles and metal particles, and they are currently widely used, but still have some problems, mainly in the following aspects: 1) The conductivity of the composite conductive microspheres depends not only on the conductivity of the plated layer of the composite conductive microspheres themselves, but also on the compression deformation degree of the composite conductive microspheres during use. A large compression rate is beneficial to ensuring good conductivity. However, the toughness of the inner plastic ball is relatively poor, and large compression deformation will cause cracks or breakage, resulting in connection failure; 2) The ideal compression rate of the composite conductive microspheres is generally between 6% and 14%. Due to the narrow compression rate range, high consistency in the diameter of the composite conductive microspheres is required, which brings great difficulty to the sorting of the composite conductive microspheres; 3) With the increasing refinement of the connected circuit, the electrode gap is required to be smaller, and the diameter of the conductive particles used in the ACF is also required to be smaller. Due to the limitation of the deformation rate of the composite conductive microspheres, 3 microns of composite conductive microspheres have reached the limit of the minimum diameter. Therefore, it is very important to develop an anisotropic conductive film based on large compression rate, good conductivity, and small diameter conductive particles for high-precision connection of circuits. SUMMARY

[0003] The present application aims to provide an anisotropic conductive adhesive based on porous metal conductive microspheres (the adhesive is especially coated into a film to form a conductive film with anisotropic properties) and a preparation method.

[0004] The technical scheme of the present application is an anisotropic conductive film based on porous metal conductive microspheres (formed by conductive glue coating film for subsequent application), which comprises the following raw materials: resin (especially bisphenol A type epoxy resin), latent curing agent or / and curing agent, defoaming agent, and porous metal conductive microspheres.

[0005] The preparation of the porous metal conductive microspheres comprises the following steps: Step 1) preparing alloy micro powder. The alloy refers to an alloy formed by a less active metal and at least one more active metal, and the total atomic ratio of the more active atoms in the alloy is in the range of 30% to 95%. Specifically, it includes an alloy formed by gold and at least one of silver, copper, tin, and nickel, an alloy formed by silver and at least one of copper, zinc, and cadmium, an alloy formed by copper and at least one of zinc and cadmium, and an alloy formed by nickel and aluminum. The alloy micro powder can be prepared by chemical methods such as coprecipitation, sol-gel, spray drying (or spray freeze drying) + hydrogen reduction, or physical methods such as smelting + crushing, gas phase condensation, and atomization;

[0006] Step 2) preparing alloy microspheres. The alloy micro powder is uniformly mixed with ceramic powder or salt powder, and then annealed at a temperature higher than the melting point of the alloy. After cooling, the ceramic or salt powder is separated to obtain alloy spherical micro powder. The ceramic powder refers to high-melting-point oxides or nitrides and their mixtures, and the salt refers to chloride. The mass ratio of the alloy micro powder to the ceramic powder should satisfy that the alloy micro powder can be isolated by the ceramic powder or salt powder;

[0007] Step 3) sorting the alloy microspheres. The sorted alloy microspheres have an average diameter in the range of 1 μm to 80 μm;

[0008] Step 4) preparing porous metal conductive microspheres. Specifically, the sorted alloy microspheres are corroded in an acid or alkali solution to remove the more active metal, thereby obtaining gold, silver, copper, or nickel porous metal conductive microspheres with a porosity in the range of 30% to 95%.

[0009] Further, Step 3) of the preparation of the porous metal conductive microspheres, which is sorting the alloy microspheres, is to obtain alloy microspheres with the required average diameter and classification accuracy by liquid classification technology. The average diameter of the alloy microspheres is in the range of 1 μm to 80 μm, and the preferred average diameter is in the range of 1 μm to 40 μm. When the average diameter is less than or equal to 2 μm, the classification accuracy is less than or equal to 1 μm; when the average diameter is greater than 2 μm and less than or equal to 4 μm, the classification accuracy is less than or equal to 2 μm; when the average diameter is greater than 4 μm and less than or equal to 7 μm, the classification accuracy is less than or equal to 4 μm; and when the average diameter is greater than 7 μm, the classification accuracy is less than or equal to 6 μm.

[0010] Further, the conductive film comprises the following raw materials by weight: 100 parts of resin, 3-10 parts of latent curing agent, 1-10 parts of curing agent, 3-15 parts of defoaming agent, and 4-25 parts of porous metal conductive microspheres. A better range is that the porous gold conductive microspheres account for 7-20 wt% of the weight of the resin matrix.

[0011] Further, a preparation method of the anisotropic conductive film based on porous metal conductive microspheres comprises the following steps:

[0012] 1) The resin, latent curing agent, curing agent, defoaming agent, and non-active diluent are mechanically stirred and ultrasonically dispersed to be uniform, then the porous metal conductive microspheres are added, vacuum degassing is performed, and then mechanical stirring and ultrasonic dispersion are performed to obtain the anisotropic conductive adhesive.

[0013] 2) The anisotropic conductive adhesive is pre-cured at 60-80°C for 10-20 min, then degassing treatment is performed, and then film coating is performed with a film thickness of 3-150 μm. The obtained film is continuously cured at room temperature for 6-12 h to obtain the anisotropic conductive film.

[0014] Beneficial effects: The anisotropic conductive film has wide application in the field of electrical connection between microelectrodes of electronic devices, and is mainly composed of an insulating resin binder and conductive particles dispersed in the insulating resin binder. The anisotropic conductive function of the conductive film is closely related to the conductive particles present therein, and the performance of the conductive particles determines the conductivity and durability of the anisotropic conductive film. Compared with composite conductive microspheres, the porous metal conductive microspheres manufactured by the present application have the following advantages: large compression deformation rate, which ensures large contact area and good conductive performance; no breakage during crimping interconnection, which can increase the pressure range during crimping interconnection and reduce the operation difficulty during crimping interconnection (the electrical connection is in the direction of pressure, and the resin is insulating in the direction perpendicular to the pressure, i.e. the electrical conductivity is anisotropic); the large compression deformation rate reduces the requirement for the consistency of the microsphere diameter and the difficulty of microsphere sorting; and the chemical plating process is not required, which reduces the impact on the environment. The porous metal conductive microspheres manufactured by the present application have high sphericity, controllable average diameter and diameter distribution range, and the prepared anisotropic conductive film has obvious advantages in fine pitch line interconnection and can meet the wide application in the field of electronic packaging. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 The scanning electron microscope photograph of the gold-copper alloy spherical particles obtained by the liquid sorting method has a particle size distribution of 4.5-10.5 μm, and an average particle size of 7.53 μm;

[0016] Figure 2Scanning electron micrograph of porous gold microspheres after chemical dealloying of gold-copper alloy spherical particles (left a), and high magnification scanning electron micrograph (right b);

[0017] Figure 3 Optical micrograph of the surface of the conductive film 1 (left a) and that of the commercial AC-3514 anisotropic conductive film (right b);

[0018] Figure 4 Schematic diagram of four-terminal method for measuring the connection resistance of an anisotropic conductive film;

[0019] Figure 5 Pressure dependence curves of the connection resistance of three kinds of anisotropic conductive films measured by the four-terminal method;

[0020] Figure 6 Scanning electron micrographs of the conductive film 1 and the commercial AC-3514 conductive film after hot pressing at a bonding pressure of 0.1 MPa, 0.3 MPa, and 0.5 MPa: (A), (B), and (C) are the commercial AC-3514 conductive film, and (D), (E), and (F) are the conductive film 1. DETAILED DESCRIPTION

[0021] The present application will be further described in conjunction with specific examples, but is not limited to the contents of the specification. The reagents used below are all of analytical purity.

[0022] The raw material of the conductive film comprises: resin, latent curing agent, curing agent, defoaming agent, and porous metal conductive microspheres. The porous metal conductive microspheres in the present application are prepared by the following method. First, alloy powder is prepared, and then the alloy powder is uniformly mixed with ceramic or salt powder, and annealed at a temperature higher than the melting point of the alloy. The non-wetting property of alloy droplets at the interface of ceramic or salt solid is utilized to form alloy spherical droplets. After cooling, the ceramic or salt powder is removed to obtain alloy spherical micro powder. The desired diameter of the alloy spherical micro powder is obtained by liquid sorting. Finally, the alloy spherical micro powder is reacted with acid or alkali, and the active elements in the alloy are corroded away by dealloying to obtain porous metal conductive microspheres. The porous metal conductive microspheres are uniformly mixed with resin, latent curing agent, curing agent, and defoaming agent to prepare an anisotropic conductive adhesive. After pre-curing and defoaming of the anisotropic conductive adhesive at 60-80°C, film coating is performed. The obtained film is further cured at room temperature for 10-12 h to obtain an anisotropic conductive film.

[0023] Preparation of porous gold conductive microspheres with a porosity of 80% and an anisotropic conductive film according to Example 1

[0024] According to the atomic ratio of gold and copper 1:4, the chloroauric acid solution and copper nitrate solution are measured and mixed uniformly, and an appropriate amount of sodium chloride solid is added and fully ultrasonically dissolved and dispersed. The mixed solution is subjected to spray-freeze drying to obtain a uniformly distributed gold-copper mixture / sodium chloride precursor. The gold-copper mixture / sodium chloride precursor is placed in a 450°C muffle furnace for 15 minutes. Then the mixture precursor is placed in a hydrogen atmosphere tube furnace at 700°C for 40 minutes. After repeating the process 2-3 times, the irregular gold-copper alloy powder with a particle size distribution of 0.5-10 μm is obtained by cleaning. The irregular gold-copper alloy powder is mechanically mixed with boron nitride powder, and after annealing at 1180°C for 20 minutes in a hydrogen atmosphere tube furnace and cooling to room temperature in the furnace, the composition uniform gold-copper alloy spherical powder with a particle size distribution of 2-13 μm is obtained by cleaning and stripping the dispersant.

[0025] The prepared gold-copper alloy spherical powder is sorted by liquid classification technology, and the alloy spherical powder with a particle size of 4.5-10.5 μm is selected (as shown in Figure 1 ). The sorted alloy spherical powder is dispersed in a certain amount of deionized water, 20% wt (based on the mass of the powder) PVP is added, and ultrasonic is used to ensure that the particles are fully dispersed. Then an appropriate amount of concentrated nitric acid is added to the liquid, the concentration of nitric acid is adjusted to 7.5 mol / L, the temperature is adjusted to 50°C, and the sample is incubated for 24 hours. The porous gold spherical powder (as shown in Figure 2 ) is obtained by repeatedly washing the sample with deionized water. In order to remove stress and defects, the porous gold spherical powder is annealed at 300°C for 30 minutes, and the annealed porous gold spherical powder is used for the preparation of anisotropic conductive film.

[0026] Preparation of anisotropic conductive film: Step 1, mix E44, E51 epoxy resin in a ratio of 1:4, add an appropriate amount of absolute ethanol (10% wt of E44 / E55 resin matrix) to activate the epoxy resin matrix, then add an appropriate amount of defoaming agent (5% wt of E44 / E55 resin matrix) to remove bubbles, and mix thoroughly for use; Step 2, dissolve low molecular weight polyamide resin curing agent (9% wt of E44 / E55 resin matrix), 2-methylimidazole (3% wt of E44 / E55 resin matrix) in an appropriate amount of absolute ethanol (10% wt of E44 / E55 resin matrix) according to the proportion, and mix thoroughly for use; Step 3, place 5% wt (volume percentage about 1.17%) of porous gold spherical powder of E44 / E55 resin matrix in an appropriate amount of absolute ethanol, and mix thoroughly for use; Step 4, first slowly drop the mixed solution of Step 3 into the epoxy resin matrix of Step 1, and then after 30 minutes of vacuum degassing bubble treatment, add the mixed solution of Step 2 to the epoxy resin glue solution, and mechanically stir for 10-15 minutes for use; Step 5, place the mixed glue solution of Step 4 in a 60 degree oven for 20 minutes, then increase the temperature to 80 degrees, and after 2 minutes of curing, take out the glue solution for degassing treatment. Adjust the parameters of the wet film applicator, and manually coat the glue solution on the PET film at a speed of 5 cm / s. After cooling, place it at room temperature for 12 hours to obtain an anisotropic conductive film with a thickness of 20 μm, which is called conductive film 1. The optical microscope photograph of the surface of conductive film 1 is shown as the left photograph in FIG. 1. Figure 3

[0027] Preparation of porous conductive gold microspheres with a porosity of 90% and anisotropic conductive film: according to the atomic ratio of gold to copper 1:9, measure the chloroauric acid solution and copper nitrate solution and mix them evenly, add an appropriate amount of sodium chloride solid, and ultrasonically dissolve and disperse. The mixed solution is subjected to spray-freeze drying to obtain a relatively uniformly distributed gold-copper mixture / sodium chloride precursor. The gold-copper mixture / sodium chloride precursor is placed in a 450°C muffle furnace for 15 minutes. Then the mixture precursor is heated to 700°C in a hydrogen atmosphere tube furnace for 40 minutes. After repeating this process 2-3 times, the irregular gold-copper alloy powder with a particle size distribution of 0.5-10 μm is obtained by washing. The irregular gold-copper alloy powder is mechanically mixed with boron nitride powder, and after annealing at 1180°C for 20 minutes in a hydrogen atmosphere tube furnace and cooling to room temperature, the gold-copper alloy spherical micro-powder with uniform composition and a particle size distribution of 2-12 μm is obtained by washing and stripping the dispersant.

[0028] ​The prepared gold-copper alloy spherical micropowder is sorted by liquid classification technology, and the alloy spherical micropowder with a particle size of 5-10 μm is selected. The sorted alloy spherical micropowder is dispersed in a certain amount of deionized water, 30%wt (based on the mass of the powder) of PVP is added, and ultrasonic is used to ensure that the particles are fully dispersed. Then, a proper amount of concentrated nitric acid is added to the liquid, the acid concentration is adjusted to 4 mol / L, and the dealloying is performed at room temperature for 2 hours. Then, the concentration of nitric acid is increased to 7.5 mol / L, the temperature is increased to 50°C, and the sample is kept at constant temperature for 24 hours. The porous gold spherical powder is obtained by repeatedly washing the sample with deionized water. In order to remove stress and defects, the porous gold spherical powder is annealed at 300°C for 30 minutes. The annealed porous gold spherical micropowder is used for the preparation of anisotropic conductive film.

[0029] Preparation of anisotropic conductive film: Step 1, mix E44 and E51 epoxy resins in a ratio of 1:4, add a proper amount of anhydrous ethanol (10%wt of E44 / E55 resin matrix) to activate the epoxy resin matrix, then add a proper amount of defoaming agent (5%wt of E44 / E55 resin matrix) to remove bubbles, and fully stir to make it uniform for standby; Step 2, dissolve low molecular weight polyamide resin curing agent (9%wt of E44 / E55 resin matrix), 2-methyl imidazole (3%wt of E44 / E55 resin matrix) in a proper amount of anhydrous ethanol (10%wt of E44 / E55 resin matrix) according to the proportion, and fully stir to make it uniform for standby; Step 3, place 10%wt of porous gold conductive microspheres (based on the weight of E44 / E55 resin matrix) in a proper amount of anhydrous ethanol, and fully ultrasonic disperse for standby; Step 4, first slowly drop the mixed solution of Step 3 into the epoxy resin matrix of Step 1, then after vacuum degassing bubble treatment for 30 minutes, add the mixed solution of Step 2 to the above epoxy resin glue solution, and mechanically stir for 10-15 minutes for standby; Step 5, place the mixed glue solution of Step 4 in a 60-degree oven for curing for 20 minutes, then increase the temperature to 80 degrees, and take out the glue solution after curing for 2 minutes for bubble removal treatment. Adjust the parameters of the wet film device, and manually coat the above glue solution on the PET film at a speed of 15 cm / s. After cooling, place it at room temperature for 12 hours to obtain an anisotropic conductive film with a thickness of 30 μm, which is called conductive film 2.

[0030] Comparative example

[0031] The comparative conductive film is an anisotropic conductive film with polystyrene microspheres as the core layer, which is made by roughening, sensitization, activation and chemical plating of Ni / Au to form composite conductive microspheres as conductive fillers, and the brand is AC-3514 from Korea TELFORD. The diameter of the composite conductive microspheres is 5 μm. Figure 3 The right photo in FIG. is the optical microscope photo of the surface of the commercial AC-3514 anisotropic conductive film, and it can be seen that the number of conductive particles of the composite conductive microspheres in the AC-3514 conductive film is significantly higher than that of the porous gold conductive microspheres in the conductive film 1.

[0032] Conductivity test:

[0033] use Figure 4 The circuit connection shown was used to measure the connection resistance of the packaged sample (a PCB board with copper pads with a spacing of 1000μm (length*width: 9*8mm, thickness 0.8mm)) using the four-terminal method. Figure 5 The graph shows the relationship between the connection resistance of three different samples and pressure. It can be seen from the graph that the connection resistance of the commercial AC-3514 is highly sensitive to pressure changes. When the pressure is less than 0.2 MPa, the connection resistance is relatively high (greater than 100 mΩ). As the pressure increases, the resistance gradually decreases, reaching a minimum of 13.1 mΩ at 0.3 MPa. Afterward, with further increases in pressure, the resistance gradually increases again. Therefore, the actual applicable pressure range for the commercial AC-3514 is relatively narrow. The test results show that a lower connection resistance, below 20 mΩ, can be obtained in the range of 0.2–0.4 MPa. This test result is consistent with the packaging pressure range provided by the manufacturer.

[0034] Both conductive films 1 and 2 exhibit excellent conductivity. Their connection resistances are both below 20 mΩ, a value comparable to that of commercial AC-3514 packages with a normal pressure range (0.2–0.4 MPa). The number of conductive particles used in conductive films 1 and 2 is significantly less than that in commercial AC-3514; the lower connection resistance is primarily due to the large compressibility deformation of the porous gold microspheres. Figure 6 This results in a larger contact area and a shorter connection distance.

[0035] The lateral connection resistance of commercial AC-3514, conductive film 1, and conductive film 2 was measured using the two-end method, and the results are shown in Table 1. For commercial AC-3514, the connection resistance is greater than 10 ohms at pressures of 0.4 MPa and below. 9 Ω, when the pressure is equal to or higher than 0.5 MPa, the resistance is less than 10 Ω. 8 Ω, causing connection failure (lateral connection resistance < 10). 8 Ω considers the transverse connection to have failed, and some particles break under high pressure. Figure 6 C) is related. Within the measured pressure range, the lateral connection resistance of both conductive film 1 and conductive film 2 is greater than 10. 9 Ω ensures that there will be no connection failure.

[0036] Table 1. Variation of transverse bonding resistance of three anisotropic conductive films with pressure

[0037]

[0038] The above merely illustrates the preferred embodiments of the present application, and is not used to limit the present application, and any modification, improvement, etc. made by those skilled in the art within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. Anisotropic conductive film based on porous metal conductive microspheres, characterized in that: The anisotropic conductive film comprises the following raw materials: resin, latent curing agent or / and curing agent, defoaming agent, and porous metal conductive microspheres; the porous metal conductive microspheres are prepared by the following method: first, preparing alloy powder, then uniformly mixing the alloy powder with ceramic or salt powder, annealing at a temperature higher than the melting point of the alloy, forming alloy spherical droplets by using the non-wetting property of alloy droplets at the interface of ceramic or salt solid, removing the ceramic or salt powder after cooling to obtain alloy spherical micro powder; then obtaining alloy spherical micro powder with desired diameter, i.e. alloy microspheres, by liquid sorting; finally, reacting the alloy spherical micro powder with acid or alkali, and obtaining porous metal conductive microspheres by dealloying process to corrode the active elements in the alloy; The conductive film comprises the following raw materials by weight: 100 parts of resin, 3-10 parts of latent curing agent, 1-10 parts of curing agent, 3-15 parts of defoaming agent, and 4-25 parts of porous metal conductive microspheres; the content of porous metal conductive microspheres in the resin matrix is 7-20 wt%; The average diameter of the alloy microspheres is in the range of 1 μm to 40 μm; when the average diameter is less than or equal to 2 μm, the classification accuracy is less than or equal to 1 μm; when the average diameter is greater than 2 μm and less than or equal to 4 μm, the classification accuracy is less than or equal to 2 μm; when the average diameter is greater than 4 μm and less than or equal to 7 μm, the classification accuracy is less than or equal to 4 μm; when the average diameter is greater than 7 μm, the classification accuracy is less than or equal to 6 μm.

2. The method of claim 1, wherein the method is characterized by: The method comprises the following steps: Step 1) preparing alloy micro powder; the alloy refers to an alloy formed by a less active metal and at least one more active metal, and the total atomic ratio of the more active atoms in the alloy is in the range of 30% to 95%; specifically, the alloy is formed by gold and at least one of silver, copper, tin, and nickel, silver and at least one of copper, zinc, and cadmium, copper and at least one of zinc and cadmium, and nickel and aluminum; the alloy micro powder is prepared by co-precipitation, sol-gel, spray drying + hydrogen reduction, or smelting + crushing, gas phase condensation, and atomization physical method; Step 2) preparing alloy microspheres; the alloy micro powder is uniformly mixed with ceramic powder or salt powder, then annealed at a temperature higher than the melting point of the alloy, and the ceramic or salt powder is separated after cooling to obtain alloy spherical micro powder; the ceramic powder refers to high melting point oxides or nitrides and their mixtures, and the salt refers to chloride salt; the mass ratio of the alloy micro powder to the ceramic powder should satisfy that the alloy micro powder can be isolated by the ceramic powder or salt powder; Step 3) sorting the alloy microspheres; the average diameter of the sorted alloy microspheres is in the range of 1 μm to 80 μm; Step 4) preparing porous metal conductive microspheres; specifically, the sorted alloy microspheres are corroded in acid or alkali solution to remove the high active metals, and gold, silver, copper, or nickel porous metal conductive microspheres are obtained; the porosity of the porous metal conductive microspheres is in the range of 30% to 95%.

3. The method of claim 2, wherein: In step 3) of the preparation of the porous metal conductive microspheres, the sorting of the alloy microspheres is performed by liquid classification technology to obtain the alloy microspheres with the desired average diameter and classification accuracy; the average diameter of the alloy microspheres is in the range of 1 μm to 40 μm; when the average diameter is less than or equal to 2 μm, the classification accuracy is less than or equal to 1 μm; when the average diameter is greater than 2 μm and less than or equal to 4 μm, the classification accuracy is less than or equal to 2 μm; when the average diameter is greater than 4 μm and less than or equal to 7 μm, the classification accuracy is less than or equal to 4 μm; when the average diameter is greater than 7 μm, the classification accuracy is less than or equal to 6 μm.

4. The method of claim 2, wherein: The conductive film comprises the following raw materials by weight: 100 parts of resin, 3-10 parts of latent curing agent, 1-10 parts of curing agent, 3-15 parts of defoaming agent, and 4-25 parts of porous metal conductive microspheres.

5. The preparation method of the anisotropic conductive film based on the porous metal conductive microspheres according to any one of claims 2-4, characterized in that: comprising the following steps: 1) mechanically stirring and ultrasonic dispersing the resin, latent curing agent, curing agent, defoaming agent, and non-active diluent until uniform, then adding the porous metal conductive microspheres, vacuuming to remove bubbles, and then mechanically stirring and ultrasonic dispersing to obtain the anisotropic conductive adhesive; 2) pre-curing the anisotropic conductive adhesive at 60-80°C for 10-20 min, then defoaming, coating the film with a thickness of 3-150 μm, and continuously curing the obtained film at room temperature for 6-12 h to obtain the anisotropic conductive film.

Images