Anti-tilting high-reliability anisotropic conductive film and preparation method thereof

Abstract

The invention is suitable for the technical field of conductive films, and provides an anti-tilting high-reliability anisotropic conductive film and a preparation method thereof. The anisotropic conductive film is prepared from the following raw materials in parts by weight: 30 to 60 parts of polyurethane acrylic resin, 5 to 20 parts of non-acrylic functional polyurethane, 3 to 12 parts of XNBR, 2 to 12 parts of IBOA, 3 to 12 parts of M215, 1 to 6 parts of M340, 0.5 to 5 parts of phosphate, 0.2 to 3 parts of TiO2, 0.7 to 5 parts of organic peroxide initiator, 0.2 to 5 parts of modified nano silicon dioxide A and 2 to 28 parts of modified nano silicon dioxide B. According to the invention, modification treatment is carried out on two different kinds of nano silicon dioxide, so that the problems of tilting and bubbles in a COF terminal gap region in a crimping process are solved, synergistic improvement of low contact resistance and high tension is also realized, and the reliability, process tolerance and long-term use stability of the conductive film are remarkably enhanced.

Description

Technical Field

[0001] This invention relates to the field of conductive film technology, specifically to a high-reliability anisotropic conductive film with anti-warping properties and its preparation method. Background Technology

[0002] Anisotropic conductive film (ACF) is a functional material used for connecting electronic components, especially in PWB-COF connections. It uses polyurethane acrylic resin as a matrix and employs a curing system to achieve both bonding and conductivity. However, in actual mass production processes, the bond head tip is often a long strip structure, leading to uneven flatness and temperature distribution during pressing. This can easily cause problems such as localized low or excessive pressure / temperature, hindered escape of residual volatiles and free radical decomposition products, and mismatch in the flow / gelation sequence at the bonding interface. These factors combined cause ACF to easily blister / lift in the COF terminal gap area during the pressing and curing process due to free radical decomposition and residual gases, resulting in increased contact resistance and decreased tensile strength. This problem is particularly pronounced under harsh pressing conditions of 200℃ / 5MPa / 5s.

[0003] In existing technologies, attempts have been made to address the aforementioned problems by adjusting the resin system and optimizing the curing agent ratio, but the results have been unsatisfactory. Some solutions use nano-silica with a single particle size as a filler, which can improve mechanical properties to some extent, but it is difficult to balance gas expulsion and interfacial wetting, and cannot effectively suppress bubbling / lifting. Other solutions do not specifically modify the nano-silica, resulting in poor dispersibility in the matrix resin and easy agglomeration. This not only fails to exert a synergistic effect but also reduces the electrical and adhesive properties of the conductive film. In addition, existing preparation processes mostly use simple stirring or ultrasonic dispersion, which makes it difficult to achieve uniform mixing of the components, further affecting the performance stability of the conductive film.

[0004] Therefore, in view of the above situation, there is an urgent need to provide a high-reliability anisotropic conductive film with anti-warping properties and its preparation method to overcome the shortcomings in current practical applications. Summary of the Invention

[0005] The purpose of this invention is to provide a high-reliability anisotropic conductive film with anti-warping properties and its preparation method, effectively solving the problems in the background art.

[0006] This invention is achieved by providing a high-reliability, anti-warping anisotropic conductive film, comprising the following raw materials in parts by weight: The composition includes: 30-60 parts polyurethane acrylic resin, 5-20 parts non-acrylic functional polyurethane, 3-12 parts XNBR, 2-12 parts IBOA, 3-12 parts M215, 1-6 parts M340, 0.5-5 parts phosphate ester, 0.2-3 parts TiO2, 0.7-5 parts organic peroxide initiator, 0.2-5 parts modified nano silica A, and 2-28 parts modified nano silica B.

[0007] As a further embodiment of the present invention: the organic peroxide initiator is composed of BPO and LPO, wherein the weight parts of BPO are 0.5 to 3 parts and the weight parts of LPO are 0.2 to 2 parts.

[0008] As a further aspect of the present invention: the modification methods for modified nano-silica A and modified nano-silica B are the same, wherein the modification steps for modified nano-silica A are as follows: S1. Acid etching activation treatment: Place nano-silica in hydrochloric acid solution and immerse it at 30~35℃ for 20~30min, stirring continuously during the process. Use hydrochloric acid to etch the surface of nano-silica to form a porous and rough structure. After soaking, the solution is repeatedly washed with deionized water until the pH of the washing solution is 6.8~7.2, and then vacuum dried at 80~90℃ for 2~3 hours to obtain surface-activated pretreated nano-silica. S2. Dispersion modification treatment: The pretreated nano-silica was added to the ethanol aqueous solution at a solid-liquid ratio of 1g:20~30mL. The mixture was first stirred for 10min for initial dispersion, and then ultrasonically dispersed for 15~20min. During the ultrasonic process, the system temperature was controlled not to exceed 40℃. The nano-silica agglomerates were broken by the synergistic effect of mechanical stirring and ultrasonication to obtain a uniform and stable dispersion. S3. Grafting functionalization treatment: Add a surface treatment agent to the dispersion. The amount of surface treatment agent added is 5% to 10% of the mass of the pretreated nano-silica. Then heat the system to 60 to 70°C and stir the reaction at a rate of 400 to 450 r / min for 2 to 3 hours under a nitrogen protective atmosphere to allow the surface treatment agent molecules to be grafted onto the surface of the nano-silica through chemical bonds. After the reaction was completed, the solid particles were separated by centrifugation, and the ungrafted free surface treatment agent was removed by washing with anhydrous ethanol 3 to 4 times. Finally, the particles were vacuum dried at 100 to 110°C for 3 to 4 hours with a vacuum degree of -0.08 to -0.09 MPa to obtain modified nano-silica A.

[0009] As a further aspect of the present invention: the average particle size of the modified nano silica A is 12 nm, the average particle size of the modified nano silica B is 100 nm, and the ratio of the total weight of the modified nano silica B to that of the modified nano silica A and the modified nano silica B is 0.60~0.95.

[0010] As a further aspect of the present invention: in S2, the ultrasonic dispersion adopts an intermittent ultrasonic mode, that is, ultrasonication for 5 minutes is paused for 1 minute, and the cycle is repeated 3 to 4 times.

[0011] As a further aspect of the present invention: the surface treatment agent is a mixture of methacryloxysilane and phenylsilane, with a mass ratio of 1:1 to 2.

[0012] As a further embodiment of the present invention, the following raw materials are included in parts by weight: 45 parts of polyurethane acrylic resin, 12 parts of non-acrylic functional polyurethane, 7 parts of XNBR, 7 parts of IBOA, 8 parts of M215, 3 parts of M340, 2.5 parts of phosphate ester, 1.5 parts of TiO2, 1.8 parts of BPO, 1.1 parts of LPO, 1.8 parts of modified nano silica A, and 10 parts of modified nano silica B.

[0013] This invention also provides a method for preparing the anti-warping, high-reliability anisotropic conductive film as described above, comprising the following steps: S1. Raw material pretreatment: Place the polyurethane acrylic resin and non-acrylic functional polyurethane at 60~70℃ and vacuum dry for 4~6 hours to remove moisture from the raw materials. Grind TiO2 to a particle size ≤5μm; S2. Mixing the matrix resin: Weigh the pretreated polyurethane acrylic resin, non-acrylic functional polyurethane, XNBR, IBOA, M215, M340, phosphate ester, and ground TiO2 according to the weight parts, and add them to the high-speed mixer in sequence. Stir and mix at a rate of 350~400r / min for 30~40min under a nitrogen protective atmosphere at 50~60℃ to fully integrate the resin components and additives and form a uniform matrix resin mixture. S3. Initiator dispersion: Add the weighed organic peroxide initiator to the matrix resin mixture, cool to 40~45℃, maintain a stirring rate of 350~400r / min, and continue stirring for 15~20min; S4. Addition and dispersion of composite particles: Mix modified nano silica A and modified nano silica B evenly, and then slowly add them to the above system. First, stir at 400~450r / min for 10min for preliminary mixing, and then use 350~400W ultrasonic power to ultrasonically disperse in intermittent ultrasonic mode for 20~25min. During the ultrasonic process, control the system temperature to not exceed 50℃ to obtain a mixed slurry. S5. Coating and drying film formation: The mixed slurry is evenly coated onto the release film using a precision coating machine. Then, the coated release film is sent into a hot air drying oven and dried in sections at 80~90℃. After drying, the film is naturally cooled to room temperature to obtain a highly reliable anisotropic conductive film that is resistant to warping. S6. Post-processing and testing: After the conductive film is formed, it is trimmed and rolled up. Then, samples are taken to test its contact resistance, tensile strength and anti-warping performance. Qualified products are put into storage for later use.

[0014] As a further aspect of the present invention: in S4, the specific steps of segmented drying are as follows: First, dry at 80℃ for 5 minutes to remove most of the solvent, then raise the temperature to 90℃ and dry for 5~10 minutes to further remove the residual solvent. During the drying process, control the wind speed to be 1~2m / s.

[0015] As a further aspect of the present invention: in S5, the coating thickness of the mixed slurry is controlled to be 20~50μm.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention creatively modifies two nano-silica particles with different particle sizes, which not only solves the problem of dispersion of nano-silica in organic matrix, but also enhances its interfacial bonding with resin system through surface functionalization grafting, thus solving the core pain point in the prior art. This invention uses a composite system of methacryloxysilane and phenylsilane as a surface treatment agent, and works synergistically with a composite initiator of BPO and LPO to further improve the interfacial stability, curing uniformity and long-term environmental resistance of the conductive film. At the same time, the raw material pretreatment, nitrogen protection, intermittent ultrasonic dispersion and segmented drying processes effectively avoid the adverse effects of moisture, oxidation, agglomeration and solvent residue on the performance of the conductive film, ensuring the stability of product quality. The modification process and preparation method of this invention have significant inventiveness. Through multi-step synergistic optimization, it achieves a synergistic improvement in anti-warping, low contact resistance, high tensile strength, and high reliability. Moreover, the raw materials are readily available, the process is simple, and it is suitable for industrial production. It has strong tolerance to long strip-shaped pressure heads and processes with slight temperature and pressure inconsistencies, and has broad application prospects in the field of electronic component connection such as PWB-COF connection. Detailed Implementation

[0017] The technical solution of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0018] The present invention will be further explained below with reference to specific embodiments.

[0019] This invention provides a high-reliability anisotropic conductive film with anti-warping properties, comprising the following raw materials in parts by weight: 30-60 parts polyurethane acrylic resin, 5-20 parts non-acrylic functional polyurethane, 3-12 parts XNBR, 2-12 parts IBOA, 3-12 parts M215, 1-6 parts M340, 0.5-5 parts phosphate ester, 0.2-3 parts TiO2, 0.7-5 parts organic peroxide initiator, 0.2-5 parts modified nano-silica A, and 2-28 parts modified nano-silica B; wherein the average particle size of modified nano-silica A is 12 nm, the average particle size of modified nano-silica B is 100 nm, and the weight ratio of modified nano-silica B to the total weight of modified nano-silica A and modified nano-silica B is 0.60-0.95.

[0020] In a specific example, the organic peroxide initiator is composed of BPO and LPO, wherein the weight parts of BPO are 0.5 to 3 parts and the weight parts of LPO are 0.2 to 2 parts.

[0021] In the specific example, the modification methods for modified nano-silica A and modified nano-silica B are the same. Taking modified nano-silica A as an example, its modification steps are as follows: S1: Acid etching activation treatment: Nano-silica is placed in a 5% hydrochloric acid solution and immersed at 30~35℃ for 20~30min, during which it is continuously stirred at a rate of 300~350r / min. The hydrochloric acid is used to etch the surface of the nano-silica to form a porous and rough structure. After immersion, it is repeatedly washed with deionized water until the pH of the washing solution is 6.8~7.2. Then it is vacuum dried at 80~90℃ for 2~3h with a vacuum degree of -0.08~-0.09MPa to obtain surface-activated pretreated nano-silica. S2: Dispersion modification treatment: Add the pretreated nano-silica to an ethanol aqueous solution with a volume fraction of 60%~70% at a solid-liquid ratio of 1g:20~30mL. First, stir at 400~450r / min for 10min for initial dispersion, and then use ultrasonic power of 300~350W for ultrasonic dispersion for 15~20min. During the ultrasonic process, control the system temperature to not exceed 40℃. The nano-silica agglomerates are broken by the synergistic effect of mechanical stirring and ultrasonication to obtain a uniform and stable dispersion. S3: Grafting Functionalization Treatment: A surface treatment agent is added to the dispersion at a concentration of 5% to 10% of the mass of the pretreated nano-silica. The system is then heated to 60 to 70°C and stirred at a rate of 400 to 450 r / min for 2 to 3 hours under a nitrogen atmosphere to allow the surface treatment agent molecules to be grafted onto the surface of the nano-silica through chemical bonds. After the reaction, the solid particles are separated by centrifugation (8000 to 10000 r / min for 10 to 15 minutes). The particles are washed 3 to 4 times with anhydrous ethanol to remove ungrafted free surface treatment agent. Finally, the particles are vacuum dried at 100 to 110°C for 3 to 4 hours at a vacuum degree of -0.08 to -0.09 MPa to obtain modified nano-silica. The surface treatment agent is a mixture of methacryloyloxysilane and phenylsilane in a mass ratio of 1:1 to 2. The synergistic grafting of the two surface treatment agents balances the dispersibility and interfacial bonding of the nano-silica.

[0022] In a specific example, the ultrasonic dispersion in S2 adopts an intermittent ultrasonic mode, that is, ultrasonication for 5 minutes is paused for 1 minute, and the cycle is repeated 3 to 4 times to further improve the dispersion uniformity.

[0023] In a specific example, the composition is as follows: 45 parts polyurethane acrylic resin, 12 parts non-acrylic functional polyurethane, 7 parts XNBR, 7 parts IBOA, 8 parts M215, 3 parts M340, 2.5 parts phosphate ester, 1.5 parts TiO2, 1.8 parts BPO, 1.1 parts LPO, 1.8 parts modified nano silica A, and 10 parts modified nano silica B.

[0024] In a specific example, when PWB and COF were crimped at 200℃ / 5MPa / 5s, blistering / lifting in the COF gap area did not actually occur (≤0.5 blister / cm). 2 Furthermore, the contact resistance (four probes) is ≤0.05Ω, and the tensile force is ≥1000gf / cm.

[0025] In a specific example, after reliability testing, the change in contact resistance ΔR ≤ 0.06Ω and the tensile force ≥ 900gf / cm; The reliability test conditions are 85℃ / 85%RH / 1000h or HAST 113℃ / 0.2MPa / 96h.

[0026] This invention also provides a method for preparing the anti-warping, high-reliability anisotropic conductive film as described above, comprising the following steps: S1: Raw material pretreatment: The polyurethane acrylic resin and non-acrylic functional polyurethane are vacuum dried at 60~70℃ for 4~6h with a vacuum degree of -0.08~-0.09MPa to remove moisture from the raw materials and avoid moisture from having an adverse effect on the membrane performance; TiO2 is ground to a particle size ≤5μm to ensure that it is uniformly dispersed in the system. S2: Matrix Resin Mixing: Weigh the pretreated polyurethane acrylic resin, non-acrylic functional polyurethane, XNBR, IBOA, M215, M340, phosphate ester, and ground TiO2 according to the weight parts, and add them to the high-speed mixer in sequence. Stir and mix at a rate of 350~400r / min for 30~40min under a nitrogen protective atmosphere at 50~60℃ to fully integrate the resin components and additives and form a uniform matrix resin mixture. S3: Initiator dispersion: Add the weighed organic peroxide initiators (BPO and LPO) to the matrix resin mixture, cool to 40~45℃, maintain a stirring rate of 350~400r / min, and continue stirring for 15~20min to ensure that the initiator is evenly dispersed in the matrix resin and avoid uneven curing caused by excessively high local initiator concentration. S4: Addition and dispersion of composite particles: Mix modified nano silica A and modified nano silica B evenly, and then slowly add them to the above system. First, stir at 400~450 r / min for 10 min for initial mixing, and then use 350~400W ultrasonic power in intermittent ultrasonic mode (sonicate for 6 min, pause for 1 min, cycle 3~4 times) to ultrasonically disperse for 20~25 min. During the ultrasonic process, control the system temperature not to exceed 50℃. Through the synergistic effect of stirring and ultrasonication, the modified nano silica is uniformly dispersed in the matrix to obtain a stable mixed slurry. S5: Coating and Drying Film Formation: The mixed slurry is uniformly coated onto the release film using a precision coating machine, with the coating thickness controlled at 20~50μm. The coated release film is then sent into a hot air drying oven and dried in stages at 80~90℃: First, it is dried at 80℃ for 5 minutes to remove most of the solvent, and then the temperature is raised to 90℃ for 5~10 minutes to further remove the residual solvent. During the drying process, the air velocity is controlled at 1~2m / s to ensure uniform solvent evaporation and avoid the formation of bubbles. After drying, it is naturally cooled to room temperature to obtain a high-reliability anisotropic conductive film that is resistant to warping. S6: Post-processing and inspection: After the conductive film is formed, it is trimmed and rolled up. Then, samples are taken to test its contact resistance, tensile strength and anti-warping performance. Qualified products are put into storage for later use.

[0027] Example 1 A high-reliability anisotropic conductive film with anti-warping properties comprises the following raw materials in parts by weight: 30 parts polyurethane acrylic resin, 5 parts non-acrylic functional polyurethane, 3 parts XNBR, 2 parts IBOA, 3 parts M215, 1 part M340, 0.5 parts phosphate ester, 0.2 parts TiO2, 0.5 parts BPO, 0.2 parts LPO, 0.2 parts modified nano-silica A, and 2 parts modified nano-silica B.

[0028] The modification methods for modified nano-silica A and modified nano-silica B are as follows: S1: Acid etching activation treatment: Place nano-silica in a 5% hydrochloric acid solution and soak at 30°C for 20 min, stirring continuously at a rate of 300 r / min during the process; After soaking, the solution was repeatedly washed with deionized water until the pH of the washing solution was 6.8~7.2. Then, it was vacuum dried at 80℃ for 2 hours with a vacuum degree of -0.08MPa to obtain surface-activated pretreated nano-silica. S2: Dispersion modification treatment: Pretreated nano-silica was added to a 60% ethanol aqueous solution at a solid-liquid ratio of 1g:20mL. It was first initially dispersed by stirring at 400r / min for 10min. Then, it was ultrasonically dispersed for 15min using an intermittent ultrasonic power of 300W (ultrasonic 5min, pause 1min, cycle 3 times) while controlling the system temperature not to exceed 40℃ to obtain a uniform and stable dispersion. S3: Grafting functionalization treatment: Methacryloxysilane was added to the dispersion as a surface treatment agent. The amount of surface treatment agent added was 5% of the mass of the pretreated nano-silica. Then the system was heated to 60°C and stirred at a rate of 400 r / min for 2 h under a nitrogen protective atmosphere. After the reaction was completed, the solid particles were separated by centrifugation (8000 r / min, 10 min), washed three times with anhydrous ethanol, and finally dried under vacuum at 100 °C for 3 h with a vacuum degree of -0.08 MPa to obtain modified nano-silica.

[0029] The method for preparing this anisotropic conductive film includes the following steps: S1: Raw material pretreatment: Polyurethane acrylic resin and non-acrylic functional polyurethane are vacuum dried at 60℃ for 4 hours with a vacuum degree of -0.08MPa. Grind TiO2 to a particle size ≤5μm; S2: Matrix resin mixing: Weigh the above raw materials according to the weight parts, add them to the high-speed mixer in sequence, and stir and mix at a rate of 350r / min for 30min at 50℃ and under nitrogen protection atmosphere to form a matrix resin mixture. S3: Initiator dispersion: Add BPO and LPO to the matrix resin mixture, cool to 40℃, maintain a stirring rate of 350r / min, and continue stirring for 15min; S4: Addition and dispersion of composite particles: Mix modified nano silica A and modified nano silica B evenly and slowly add them to the above system. Stir at 400 r / min for 10 min, then use 350 W ultrasonic power and intermittent ultrasonic mode (sonicate for 6 min, pause for 1 min, cycle 3 times) to ultrasonically disperse for 20 min, controlling the system temperature not to exceed 50℃ to obtain a mixed slurry; S5: Coating and drying film formation: The mixed slurry is coated onto the release film using a precision coating machine to a coating thickness of 20μm. Then it is sent into a hot air drying oven and dried at 80℃ for 5min, and then the temperature is raised to 90℃ for 5min. The wind speed is controlled at 1m / s. After drying, allow it to cool naturally to room temperature; S6: Post-processing and inspection: After trimming and rewinding, sampling inspection is carried out, and qualified products are put into storage.

[0030] Example 2 A high-reliability anisotropic conductive film with anti-warping properties comprises the following raw materials in parts by weight: 60 parts polyurethane acrylic resin, 20 parts non-acrylic functional polyurethane, 12 parts XNBR, 12 parts IBOA, 12 parts M215, 6 parts M340, 5 parts phosphate ester, 3 parts TiO2, 3 parts BPO, 2 parts LPO, 5 parts modified nano silica A, and 28 parts modified nano silica B.

[0031] The modification methods for modified nano-silica A and modified nano-silica B are as follows: S1: Acid etching activation treatment: Place nano-silica in a 5% hydrochloric acid solution and soak at 35°C for 30 min, stirring continuously at a rate of 350 r / min during the process; After soaking, the solution was repeatedly washed with deionized water until the pH of the washing solution was 6.8~7.2, and then vacuum dried at 90℃ for 3h with a vacuum degree of -0.09MPa to obtain surface-activated pretreated nano-silica. S2: Dispersion modification treatment: Pretreated nano-silica was added to a 70% ethanol aqueous solution at a solid-liquid ratio of 1g:30mL. It was first initially dispersed by stirring at 450r / min for 10min. Then, it was ultrasonically dispersed for 20min using an intermittent ultrasonic power of 350W (ultrasonic 5min, pause 1min, cycle 4 times) while controlling the system temperature not to exceed 40℃ to obtain a uniform and stable dispersion. S3: Grafting functionalization treatment: Phenylsilane was added to the dispersion as a surface treatment agent. The amount of surface treatment agent added was 10% of the mass of the pretreated nano-silica. Then the system was heated to 70°C and stirred at a rate of 450 r / min for 3 h under a nitrogen protective atmosphere. After the reaction was completed, the solid particles were separated by centrifugation (10,000 r / min, 15 min), washed four times with anhydrous ethanol, and finally dried under vacuum at 110 °C for 4 h with a vacuum degree of -0.09 MPa to obtain modified nano-silica.

[0032] The method for preparing this anisotropic conductive film includes the following steps: S1: Raw material pretreatment: Polyurethane acrylic resin and non-acrylic functional polyurethane are vacuum dried at 70℃ for 6 hours with a vacuum degree of -0.09MPa. Grind TiO2 to a particle size ≤5μm; S2: Matrix resin mixing: Weigh the above raw materials according to the weight parts, add them to the high-speed mixer in sequence, and stir and mix at a rate of 400r / min for 40min under a nitrogen protective atmosphere at 60℃ to form a matrix resin mixture; S3: Initiator dispersion: Add BPO and LPO to the matrix resin mixture, cool to 45℃, maintain a stirring rate of 400r / min, and continue stirring for 20min; S4: Addition and dispersion of composite particles: Mix modified nano silica A and modified nano silica B evenly and slowly add them to the above system. Stir at 450 r / min for 10 min, then use 400 W ultrasonic power and intermittent ultrasonic mode (sonicate for 6 min, pause for 1 min, cycle 4 times) to ultrasonically disperse for 25 min, controlling the system temperature not to exceed 50℃ to obtain a mixed slurry; S5: Coating and drying film formation: The mixed slurry is coated onto the release film using a precision coating machine to a coating thickness of 50μm. Then it is sent into a hot air drying oven and dried at 80℃ for 5min, and then the temperature is raised to 90℃ for 10min. The wind speed is controlled at 2m / s. After drying, allow it to cool naturally to room temperature; S6: Post-processing and inspection: After trimming and rewinding, sampling inspection is carried out, and qualified products are put into storage.

[0033] Example 3 A high-reliability anisotropic conductive film with anti-warping properties comprises the following raw materials in parts by weight: 45 parts polyurethane acrylic resin, 12 parts non-acrylic functional polyurethane, 7 parts XNBR, 7 parts IBOA, 8 parts M215, 3 parts M340, 2.5 parts phosphate ester, 1.5 parts TiO2, 1.8 parts BPO, 1.1 parts LPO, 1.8 parts modified nano silica A, and 10 parts modified nano silica B.

[0034] The modification methods for modified nano-silica A and modified nano-silica B are as follows: S1: Acid etching activation treatment: Place nano-silica in a 5% hydrochloric acid solution and immerse it at 32°C for 25 min, stirring continuously at a rate of 320 r / min during the process; After soaking, the solution was repeatedly washed with deionized water until the pH of the washing solution was 6.8~7.2, and then vacuum dried at 85℃ for 2.5h with a vacuum degree of -0.085MPa to obtain surface-activated pretreated nano-silica. S2: Dispersion modification treatment: Pretreated nano-silica was added to a 65% ethanol aqueous solution at a solid-liquid ratio of 1g:25mL. It was first initially dispersed by stirring at 420r / min for 10min. Then, it was ultrasonically dispersed for 18min using an intermittent ultrasonic power of 320W (ultrasonication for 5min, pause for 1min, cycle 3 times) while controlling the system temperature not to exceed 40℃ to obtain a uniform and stable dispersion. S3: Grafting functionalization treatment: A mixture of methacryloyloxysilane and phenylsilane (mass ratio 1:1.5) was added to the dispersion as a surface treatment agent. The amount of surface treatment agent added was 8% of the mass of the pretreated nano-silica. Then the system was heated to 65°C and stirred at a rate of 420 r / min for 2.5 h under a nitrogen protective atmosphere. After the reaction was completed, the solid particles were separated by centrifugation (9000 r / min, 12 min), washed three times with anhydrous ethanol, and finally dried under vacuum at 105 °C for 3.5 h with a vacuum degree of -0.085 MPa to obtain modified nano-silica.

[0035] The method for preparing this anisotropic conductive film includes the following steps: S1: Raw material pretreatment: Polyurethane acrylic resin and non-acrylic functional polyurethane are vacuum dried at 65℃ for 5h with a vacuum degree of -0.085MPa. Grind TiO2 to a particle size ≤5μm; S2: Matrix resin mixing: Weigh the above raw materials according to the weight parts, add them to the high-speed mixer in sequence, and stir and mix at a rate of 380r / min for 35min at 55℃ under nitrogen protection atmosphere to form a matrix resin mixture. S3: Initiator dispersion: Add BPO and LPO to the matrix resin mixture, cool to 42℃, maintain stirring speed of 380r / min, and continue stirring for 18min; S4: Addition and dispersion of composite particles: Mix modified nano silica A and modified nano silica B evenly and slowly add them to the above system. Stir at 420 r / min for 10 min, then use 380 W ultrasonic power and intermittent ultrasonic mode (sonicate for 6 min, pause for 1 min, cycle 3 times) to ultrasonically disperse for 22 min, controlling the system temperature not to exceed 50℃ to obtain a mixed slurry; S5: Coating and drying film formation: The mixed slurry is coated onto the release film using a precision coating machine to a coating thickness of 35μm. Then it is sent into a hot air drying oven and dried at 80℃ for 5 minutes, and then the temperature is raised to 90℃ for 8 minutes. The wind speed is controlled at 1.5m / s. After drying, allow it to cool naturally to room temperature; S6: Post-processing and inspection: After trimming and rewinding, sampling inspection is carried out, and qualified products are put into storage.

[0036] Comparative Example 1 Unlike Example 3, no modification treatment was performed on nano-silica A and nano-silica B; unmodified nano-silica A and nano-silica B were used directly.

[0037] Comparative Example 2 Unlike Example 3, only modified nano silica B and modified nano silica A (average particle size 12 nm) of a single particle size were used, with a weight ratio of 11.8 parts.

[0038] Comparative Example 3 Unlike Example 3, only modified nano silica B and modified nano silica A (average particle size 100 nm) of a single particle size were used, with a weight ratio of 11.8 parts.

[0039] Comparative Example 4 Unlike Example 3, the ratio of the total weight of modified nano-silica B to modified nano-silica A and modified nano-silica B is 0.55.

[0040] Comparative Example 5 Unlike Example 3, the modified nano-silica was prepared without acid etching activation treatment.

[0041] Comparative Example 6 Unlike Example 3, the preparation method used continuous ultrasonic dispersion (without pause) and did not perform segmented drying (it was directly dried at 90°C for 13 min).

[0042] Performance testing: The anisotropic conductive films prepared in Examples 1-3 and Comparative Examples 1-6 were subjected to performance tests. The test conditions and results are shown in Table 1. Table 1 Performance Test Results The test results above show that the anisotropic conductive films prepared in Examples 1-3 of this invention exhibit no blistering / lifting under harsh pressing conditions, with an initial contact resistance ≤0.05Ω and an initial tensile force ≥1000gf / cm. After reliability testing, ΔR ≤0.06Ω and tensile force ≥900gf / cm, demonstrating excellent performance. However, Comparative Examples 1-6, due to reasons such as not using the modification process of this invention, improper compounding ratios, or unreasonable preparation processes, show inferior performance in terms of blistering / lifting suppression, contact resistance, and tensile force compared to the embodiments of this invention. Comparative Example 1, with poor dispersibility of unmodified nano-silica, exhibits the worst performance. Comparative Examples 2 and 3 showed poor anti-warping effects because single-particle-size nano-silica could not simultaneously achieve wetting and gas expulsion. Comparative Example 4 experienced a performance decrease because the compounding ratio exceeded the optimization range; Comparative Example 5 lacked an acid etching activation step, resulting in insufficient active sites on the surface of nano-silica and poor interfacial adhesion. Comparative Example 6, due to insufficient process optimization, resulted in uneven component dispersion and incomplete solvent evaporation, affecting the film performance. This fully demonstrates the inventiveness and technical superiority of the modification process and preparation method of this invention.

[0043] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions 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. A high-reliability anisotropic conductive film with anti-warping properties, characterized in that, The following raw materials are included by weight parts: polyurethane acrylic resin 30~60 parts, non-acrylic functional polyurethane 5~20 parts, XNBR 3~12 parts, IBOA 2~12 parts, M215 3~12 parts, M340 1~6 parts, phosphate 0.5~5 parts, TiO2 0.2~3 parts, organic peroxide initiator 0.7~5 parts, modified nano-silica A 0.2~5 parts, modified nano-silica B 2~28 parts.

2. The lift-off prevention high-reliability anisotropic conductive film according to claim 1, wherein The organic peroxide initiator is composed of BPO and LPO, wherein the weight parts of BPO is 0.5~3 parts and the weight parts of LPO is 0.2~2 parts.

3. The lift-off prevention high-reliability anisotropic conductive film according to claim 1, wherein The modification methods of the modified nano-silica A and the modified nano-silica B are the same, wherein the modification steps of the modified nano-silica A are: S1, acid etching activation treatment: placing nano-silica in a hydrochloric acid solution, soaking at 30~35℃ for 20~30min, continuously stirring during the process, using hydrochloric acid to etch the surface of nano-silica to form a porous rough structure; after soaking, washing repeatedly with deionized water until the pH value of the washing liquid is 6.8~7.2, then vacuum drying at 80~90℃ for 2~3h to obtain surface-activated pretreated nano-silica; S2, dispersion modification treatment: adding pretreated nano-silica to an ethanol aqueous solution according to a solid-liquid ratio of 1g:20~30mL, stirring for 10min for preliminary dispersion, then ultrasonic dispersion for 15~20min, controlling the system temperature not to exceed 40℃ during the ultrasonic process, breaking the nano-silica agglomerates through the synergistic effect of mechanical stirring and ultrasonic to obtain a uniform and stable dispersion liquid; S3, grafting functionalization treatment: adding a surface treatment agent to the dispersion liquid, the addition amount of the surface treatment agent being 5%~10% of the mass of the pretreated nano-silica, then heating the system to 60~70℃, stirring at a rate of 400~450r / min under a nitrogen protective atmosphere for 2~3h to graft the surface treatment agent molecules to the surface of nano-silica through chemical bonds; after the reaction, separating the solid particles by centrifugation, washing with anhydrous ethanol for 3~4 times to remove ungrafted free surface treatment agent, and finally vacuum drying at 100~110℃ for 3~4h at a vacuum degree of-0.08~-0.09MPa to obtain modified nano-silica A.

4. The lift-off prevention high-reliability anisotropic conductive film according to claim 1, wherein The average particle size of the modified nano-silica A is 12nm, the average particle size of the modified nano-silica B is 100nm, and the ratio of the modified nano-silica B to the total weight of the modified nano-silica A and the modified nano-silica B is 0.60~0.

95.

5. The lift-off prevention high-reliability anisotropic conductive film according to claim 3, wherein In S2, the ultrasonic dispersion adopts an intermittent ultrasonic mode, i.e. ultrasonic for 5min and pause for 1min, repeating 3~4 times.

6. The lift-off prevention high-reliability anisotropic conductive film according to claim 3, wherein The surface treatment agent is a mixture of methacryloyloxy silane and phenyl silane, and the mass ratio of the two is 1:1~2.

7. The lift-off prevention high-reliability anisotropic conductive film according to claim 1, wherein The following raw materials are included by weight: polyurethane acrylic resin 45 parts, non-acrylic functional polyurethane 12 parts, XNBR 7 parts, IBOA 7 parts, M215 8 parts, M340 3 parts, phosphate 2.5 parts, TiO2 1.5 parts, BPO 1.8 parts, LPO 1.1 parts, modified nano-silica A 1.8 parts, modified nano-silica B 10 parts.

8. A method for producing a highly reliable anisotropic conductive film against warpage according to any one of claims 1 to 7, characterized by, The following steps are included: S1, raw material pretreatment: polyurethane acrylic resin and non-acrylic functional polyurethane are placed in a vacuum dryer at 60-70°C for 4-6h to remove moisture from the raw materials; Grind TiO2 to a particle size of ≤5μm; S2, mixing of base resin: the pretreated polyurethane acrylic resin, non-acrylic functional polyurethane, and XNBR, IBOA, M215, M340, phosphate, and ground TiO2 are weighed and added to a high-speed mixer in sequence, stirred and mixed at 350-400r / min for 30-40min at 50-60°C in a nitrogen atmosphere, so that the resin components and additives are fully integrated to form a uniform base resin mixture; S3, initiator dispersion: add the weighed organic peroxide initiator to the base resin mixture, cool to 40-45°C, maintain stirring rate 350-400r / min, continue stirring for 15-20min; S4, addition and dispersion of composite particles: mix modified nano-silica A and modified nano-silica B uniformly, then slowly add to the above system, first stir at 400-450r / min for 10min for preliminary mixing, then use 350-400W ultrasonic power for ultrasonic dispersion in intermittent mode for 20-25min, control the system temperature not to exceed 50°C during ultrasonic process, to obtain a mixed slurry; S5, coating and drying to form a film: uniformly coat the mixed slurry on a release film by a precision coater, then send the coated release film into a hot air drying oven for stepwise drying at 80-90°C; After drying is completed, naturally cool to room temperature to obtain a high-reliability anti-warping anisotropic conductive film; S6, post-processing and detection: cut the edges of the conductive film after film formation, then roll it up, sample test its contact resistance, tensile strength and anti-warping performance, and qualified products are put into storage for future use.

9. The method of claim 8, wherein, In S4, the specific steps of stepwise drying are: First dry at 80°C for 5min to remove most of the solvent, then increase the temperature to 90°C for 5-10min to remove residual solvent, control the air speed to 1-2m / s during the drying process.

10. The method of claim 8, wherein, In S5, the coating thickness of the mixed slurry is controlled to be 20-50μm.

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