Super-hydrophobic anisotropic conductive adhesive film and preparation method thereof

Abstract

The invention discloses a super-hydrophobic anisotropic conductive adhesive film and a preparation method thereof.The super-hydrophobic anisotropic conductive adhesive film is prepared from, by mass, 100 parts of epoxy resin, 70-100 parts of thermoplastic polyurethane, 90-150 parts of conductive filler, 15-25 parts of curing agent, 1-1.5 parts of hexamethylenediamine, 1-2 parts of carboxyl-terminated liquid nitrile rubber and 5-10 parts of film forming additive. 1 to 2 parts of hydrogenated styrene-isoprene-styrene block copolymer; 2 to 5 parts of fumed silica; an epoxy-based precursor adhesive film is stretched and fixed, then a super-hydrophobic solution is sprayed to the surface of the stretched epoxy-based precursor adhesive film by adopting a spraying method to carry out super-hydrophobic modification treatment, the super-hydrophobic anisotropic conductive adhesive film is prepared, and a super-hydrophobic structure on the surface of the super-hydrophobic anisotropic conductive adhesive film effectively blocks erosion of moisture to the conductive adhesive film; the influence of a high-pollution environment on the conductivity is reduced, the conductivity is good and stable, and the technical problems that an existing anisotropic conductive adhesive film is short in service life and poor in pollution resistance in a humid or polluted environment are solved.

Description

Technical Field

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

[0002] The rapid development of electronic products toward miniaturization and high integration has placed higher demands on the connection materials between electronic devices. Among various connection methods, anisotropic conductive film (ACF) has become one of the most important functional materials in modern electronic packaging and interconnection technologies due to its anisotropic conductivity, high connection precision, and low processing temperature.

[0003] The basic structure of anisotropic conductive adhesive film typically consists of conductive particles uniformly dispersed in a resin matrix. This material conducts electricity vertically, enabling precise connections between devices such as chips, electrodes, and circuit boards. By keeping the volume fraction of the conductive particles within a certain range, a continuous conductive path is prevented between the particles in the horizontal direction, maintaining excellent insulation properties. This anisotropic conductive property of "conducting only in the vertical direction and shielding in the horizontal direction" significantly reduces the risk of short circuits.

[0004] However, with the rapid development of modern electronic technology, the operating environment of electronic equipment and its components is becoming increasingly complex, especially for electronic equipment serving in the field, aviation, ocean, coastal and other fields, where the operating environment is even more complex. Anisotropic conductive films are susceptible to contamination and moisture intrusion when used for a long time or exposed to complex environments such as moisture, dust, and oil, resulting in decreased conductivity, increased resistance, and even connection failure. This is particularly prominent in outdoor electronic equipment, medical equipment, and high-stability industrial control systems. Therefore, there is an urgent need for a conductive film material that maintains good anisotropic conductive properties while having hydrophobic and anti-fouling properties. By constructing a super-hydrophobic structure on the surface of the conductive film, its anti-fouling and environmental adaptability can be effectively improved, thereby extending its service life and improving the stability and reliability of the electrical connection. This technology will provide a new solution for the long-term and stable operation of electronic devices in complex or harsh environments.

[0005] Chinese patent application publication number CN118360005A discloses a flexible conductive adhesive and its preparation method. The conductive adhesive film is prepared using polyurethane-modified epoxy resin and Sn@Ni conductive microspheres as raw materials. However, the conductive adhesive film has not undergone any hydrophobic modification. When used for a long time or exposed to complex environments such as moisture, dust, and oil, it is easily contaminated and water intruded, resulting in decreased conductivity, increased resistance, and even connection failure. Summary of the Invention

[0006] In order to overcome the shortcomings of the above-mentioned prior art, the purpose of the present invention is to provide a super-hydrophobic anisotropic conductive adhesive film and a preparation method thereof. An epoxy precursor adhesive film is stretched to 100-180% of the original adhesive film and fixed. Then, a super-hydrophobic solution is sprayed onto the surface of the stretched epoxy precursor adhesive film by a spraying method to perform super-hydrophobic modification treatment. After drying, a super-hydrophobic anisotropic conductive adhesive film is obtained. The super-hydrophobic structure formed on the surface of the super-hydrophobic anisotropic conductive adhesive film effectively blocks the erosion of water on the conductive adhesive film, reduces the impact of the environment on the conductive performance, and solves the technical problems of the existing anisotropic conductive adhesive film having a short service life and poor anti-fouling ability in humid or polluted environments.

[0007] In order to achieve the above object, the technical solution adopted by the present invention is:

[0008] A super-hydrophobic anisotropic conductive adhesive film comprises the following components, calculated by weight: 100 parts of epoxy resin, 70-100 parts of thermoplastic polyurethane, 90-150 parts of conductive filler, 15-25 parts of curing agent, 1-1.5 parts of hexamethylenediamine, 1-2 parts of carboxyl-terminated liquid nitrile rubber, 5-10 parts of film-forming additive, 1-2 parts of hydrogenated styrene-isoprene-styrene block copolymer, and 2-5 parts of fumed silica.

[0009] The conductive filler is a silver-plated microsphere on the surface of silicon dioxide or a nickel-plated microsphere on the surface of silicon dioxide; the diameter of the silicon dioxide microsphere is 3-10 μm, and the diameter of the silver-plated silicon dioxide microsphere or the nickel-plated silicon dioxide microsphere is 5-13 μm.

[0010] The film-forming additive is one of nano silicon dioxide, nano montmorillonite and nano aluminum hydroxide; and the curing agent has a latent property of 3 to 6 months.

[0011] A method for preparing a super-hydrophobic anisotropic conductive adhesive film comprises the following steps:

[0012] Step 1: adding a film-forming additive, a curing agent, and a carboxyl-terminated liquid nitrile rubber to an epoxy resin solution and stirring, thereby obtaining a solution A; adding hexamethylenediamine and a conductive filler to a thermoplastic polyurethane solution and stirring, thereby obtaining a solution B; dispersing fumed silica in n-hexane and ultrasonically treating the solution; and then adding hydrogenated styrene-isoprene-styrene block copolymer and stirring, thereby obtaining a solution C;

[0013] Step 2: Mixing solution A and solution B to form a colloidal solution; coating the colloidal solution on a release film by a casting method, and drying to obtain a precursor film;

[0014] Step 3: stretching and fixing the precursor film, wherein the stretching rate of the precursor film is 100-180%; then spraying solution C evenly onto the precursor film, performing superhydrophobic modification on the precursor film, and drying to obtain a superhydrophobic anisotropic conductive film.

[0015] In step 1, the epoxy resin solution is prepared by dissolving 100 parts of epoxy resin in 400 parts of tetrahydrofuran; and the thermoplastic polyurethane solution is prepared by dissolving 70-100 parts of thermoplastic polyurethane in 300 parts of tetrahydrofuran.

[0016] In step one, the mass fractions of the film-forming additive, curing agent, carboxyl-terminated liquid nitrile rubber, hexamethylenediamine, conductive filler, fumed silica, n-hexane, and hydrogenated styrene-isoprene-styrene block copolymer are 5-10 parts, 15-25 parts, 1-2 parts, 1-1.5 parts, 90-150 parts, 2-5 parts, 80-120 parts, and 1-2 parts.

[0017] In step 1, the stirring speed is 300-500 rpm, and the time is 40-60 min; the ultrasonic treatment time is 90-120 min.

[0018] In step 2, the stirring process is: stirring at 20-30° C. and 300-500 rpm for 3-6 hours.

[0019] In step 2, the casting temperature is 15-30° C., and the thickness of the cast film is maintained at 10-40 μm.

[0020] In step 3, the nozzle diameter of the spray gun is 1.5 mm, and the spraying amount is 1-8 ml / cm 2 , the spraying distance is 5-15cm, and the spraying pressure is 0.2-0.5MPa.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] 1. The present invention constructs a super-hydrophobic structure on the surface of an epoxy-based anisotropic conductive film, which provides protection without interfering with the arrangement of conductive particles inside. The super-hydrophobic structure constructed on the surface serves as an insulating layer. During hot pressing, the conductive particles can penetrate the insulating layer to achieve a good electrical connection with the electrode, while maintaining its insulating properties in other areas not subjected to hot pressing, effectively preventing electrical short circuits.

[0023] 2. The present invention constructs a super-hydrophobic structure on the surface of the epoxy-based anisotropic conductive film, so that the contact angle of the anisotropic conductive film to water reaches 150°, effectively blocking the erosion of moisture on the conductive film, reducing the impact of the environment on the conductive performance, and significantly improving the reliability of the device in high-humidity environments.

[0024] 3. The present invention constructs a super-hydrophobic structure on the surface of the epoxy-based anisotropic conductive film, making it difficult for pollutants to adhere to the surface of the film. This not only reduces the frequency of cleaning and maintenance of the film, but also reduces the change in contact resistance caused by the accumulation of pollutants, thereby further ensuring the stability of electronic components in long-term operation.

[0025] 4. The super-hydrophobic anisotropic conductive adhesive film prepared by the present invention will undergo hot pressing curing in subsequent use. After curing, the bonding strength of the anisotropic conductive adhesive film with the micro-nano structure on the surface is greatly enhanced, achieving good bonding and giving it excellent wear resistance, thereby further ensuring the durability of electronic components in long-term operation.

[0026] In summary, the present invention forms a superhydrophobic structure on the surface of the anisotropic conductive film by performing a superhydrophobic modification treatment on the surface of the film, which effectively blocks the erosion of the conductive film by moisture, reduces the impact of the environment on the conductive performance, ensures that the conductive film has good and stable conductivity, and solves the technical problems of the existing anisotropic conductive film having a short service life and poor anti-fouling ability in humid or polluted environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a SEM image of the anisotropic conductive adhesive film provided by the present invention, wherein: Figure 1 (a) is comparative example 1, Figure 1 (b) is Example 1.

[0028] Figure 2 This is a comparison chart of the contact angle test of the anisotropic conductive film provided by the present invention, wherein: Figure 2 (a) is comparative example 1, Figure 2 (b) is comparative example 2, Figure 2 (c) is Example 1.

[0029] Figure 3 This is a comparison chart of the hydrophobic properties of the anisotropic conductive adhesive film provided by the present invention at different stretching rates.

[0030] Figure 4 This is a comparison chart of the shear properties of the anisotropic conductive adhesive film provided by the present invention before and after superhydrophobic modification.

[0031] Figure 5 Detailed frame diagram of a water droplet staying on the surface of the super-hydrophobic anisotropic conductive adhesive film prepared in Example 1.

[0032] Figure 6 This is a comparison chart of the anti-fouling performance of the anisotropic conductive film provided by the present invention before and after super-hydrophobic modification, wherein: Figure 6 (a) is the state diagram placed above the red ink, Figure 6 (b) is a state diagram placed in red ink, Figure 6 (c) is a diagram showing the state of the sample after being placed in red ink for 10 seconds and then taken out.

[0033] Figure 7 This is a self-cleaning performance test diagram of the super-hydrophobic anisotropic conductive film provided by the present invention, wherein: Figure 7 (a) is a diagram showing the state of carbon black powder being sprinkled on the surface of the conductive film. Figure 7 (b) is a state diagram of carbon black on the conductive film being rinsed with deionized water. Figure 7 (c) is the state diagram of the conductive film after rinsing for 10 seconds.

[0034] Figure 8 This is a test diagram of the hydrophobic performance of absorbent cotton, where: Figure 8 (a) is the state diagram placed above the red ink, Figure 8 (b) is a state diagram placed in red ink, Figure 8 (c) is a diagram showing the state of the sample after being placed in red ink for 10 seconds and then taken out.

[0035] Figure 9 This is a test diagram of the hydrophobicity of the absorbent cotton containing solution C provided by the present invention, wherein: Figure 9 (a) is the state diagram placed above the red ink, Figure 9 (b) is a state diagram placed in red ink, Figure 9 (c) is a diagram showing the state of the sample after being placed in red ink for 10 seconds and then taken out.

[0036] Figure 10 Schematic diagram of the wear resistance test of the anisotropic conductive adhesive film provided by the present invention. DETAILED DESCRIPTION

[0037] In order to have a clearer understanding of the technical features, purposes and effects of the present invention, the present invention will be further described in detail below with reference to examples. The examples are only used to explain the present invention and do not constitute a limitation on the scope of protection of the present invention.

[0038] A super-hydrophobic anisotropic conductive adhesive film comprises the following components, calculated by weight: 100 parts of epoxy resin, 70-100 parts of thermoplastic polyurethane, 90-150 parts of conductive filler, 15-25 parts of curing agent, 1-1.5 parts of hexamethylenediamine, 1-2 parts of carboxyl-terminated liquid nitrile rubber, 5-10 parts of film-forming additive, 1-2 parts of hydrogenated styrene-isoprene-styrene block copolymer, and 2-10 parts of fumed silica.

[0039] The epoxy resin has an epoxide value of 0.3-0.7 eq / 100g, preferably epoxy resin E51 or epoxy resin E54. The curing agent is a latent curing agent with a latency of 3-6 months. The curing agent model is 180MB and was purchased from Chuzhou Huisheng Electronic Materials Co., Ltd. The conductive filler is silver-plated silica microspheres or nickel-plated silica microspheres; the silica microspheres have a diameter of 3-10 μm, and the silver-plated silica microspheres or nickel-plated silica microspheres have a diameter of 5-13 μm. The film-forming additive is one of nano-silica, nano-montmorillonite, and nano-aluminum hydroxide.

[0040] The super-hydrophobic anisotropic conductive film adopts an epoxy resin matrix with conductive particles evenly dispersed therein, and then constructs a super-hydrophobic structure on its surface. This makes the conductive film not only have excellent waterproof, anti-fouling and self-cleaning properties, but also can form a stable conductive path in the vertical direction while maintaining insulation in the horizontal direction.

[0041] A method for preparing a super-hydrophobic anisotropic conductive adhesive film comprises the following steps:

[0042] Step 1: dissolving 100 parts of epoxy resin in 400 parts of tetrahydrofuran to obtain an epoxy resin solution; adding 5-10 parts of a film-forming additive, 15-25 parts of a curing agent, and 1-2 parts of a carboxyl-terminated liquid nitrile rubber to the epoxy resin solution and stirring at a speed of 300-500 rpm for 40-60 minutes to obtain a solution A, so that the subsequent colloidal solution has an appropriate viscosity and is neither viscous nor thin during casting;

[0043] Step 2: Dissolve 70-100 parts of thermoplastic polyurethane in 300 parts of tetrahydrofuran to obtain a thermoplastic polyurethane solution; add 1-1.5 parts of hexamethylenediamine and 90-150 parts of conductive filler to the thermoplastic polyurethane solution and stir at 300-500 rpm for 40-60 minutes to obtain solution B, so that the subsequent colloidal solution has an appropriate viscosity and is neither viscous nor thin during casting;

[0044] Step 3: Disperse 2-10 parts of fumed silica in 80-120 parts of n-hexane and ultrasonicate for 90-120 minutes to uniformly disperse the silica. Then, add 1-2 parts of hydrogenated styrene-isoprene-styrene block copolymer and stir at 300-500 rpm for 40-60 minutes to obtain solution C; the ultrasonic power is 300 W;

[0045] Step 4: Mix solution A and solution B at 20-30°C and 300-500 rpm for 3-6 hours to form a colloidal solution; apply the colloidal solution evenly on a release film by a casting method, and dry it at 35-40°C for 4-10 hours to obtain a precursor film; the casting temperature is 15-30°C, and the cast film thickness is maintained at 50-150 μm;

[0046] Step 5: Stretch and fix the precursor film, wherein the stretching rate of the precursor film is 100-180%; then use a spray gun to evenly spray solution C onto the precursor film, perform super-hydrophobic modification on the precursor film, and then dry it at 20-30°C for 1-5 hours to obtain a super-hydrophobic anisotropic conductive film, referred to as super-hydrophobic modified ACF; the nozzle diameter of the spray gun is 1.5mm, and the spraying amount is 1-8ml / cm 2 The present invention stretches the precursor film by at least 100% before spraying solution C, making it easier for solution C to penetrate the pores on the precursor film surface, resulting in more uniform coverage. After drying and curing, the anisotropic conductive film strengthens its bonding with the super-hydrophobic structure on its surface, reducing the risk of peeling.

[0047] Example 1

[0048] A method for preparing a super-hydrophobic anisotropic conductive adhesive film comprises the following steps:

[0049] Step 1: Dissolve 100 parts of epoxy resin E51 in 400 parts of tetrahydrofuran, then add 8 parts of nano-silica, 20 parts of curing agent and 2 parts of carboxyl-terminated liquid nitrile rubber, and stir at 300 rpm for 50 minutes to obtain solution A;

[0050] Step 2: Dissolve 70 parts of thermoplastic polyurethane in 300 parts of tetrahydrofuran, then add 1 part of hexamethylenediamine and 130 parts of conductive filler, and stir at 400 rpm for 50 minutes to obtain solution B; the conductive filler is silver-plated microspheres on the surface of silica;

[0051] Step 3: 2 parts of fumed silica were added to 100 parts of n-hexane and ultrasonically treated for 90 minutes, and then 2 parts of hydrogenated styrene-isoprene-styrene block copolymer were added and stirred at 500 rpm for 60 minutes to obtain solution C;

[0052] Step 4: Solution A and Solution B were mixed and stirred at 20°C and 300 rpm for 3 hours to form a colloidal solution; the colloidal solution was evenly coated on a release film by a casting method, and dried at 35°C for 4 hours to obtain a precursor film; the casting temperature was 25°C, and the cast film thickness was maintained at 150 μm;

[0053] Step 5: Stretch the precursor film 100% and fix it, then spray solution C evenly onto the precursor film at a distance of 5 cm from the precursor film at a pressure of 0.2 MPa. The spraying amount is 2 ml / cm 2 , and dried at 20℃ for 1h to obtain a super-hydrophobic anisotropic conductive adhesive film.

[0054] Example 2

[0055] A method for preparing a super-hydrophobic anisotropic conductive adhesive film comprises the following steps:

[0056] Step 1: Dissolve 100 parts of epoxy resin E51 in 400 parts of tetrahydrofuran, then add 9 parts of nano-montmorillonite, 20 parts of curing agent and 2 parts of carboxyl-terminated liquid nitrile rubber, and stir at 400 rpm for 50 minutes to obtain solution A;

[0057] Step 2: Dissolve 70 parts of thermoplastic polyurethane in 300 parts of tetrahydrofuran, then add 1 part of hexamethylenediamine and 130 parts of conductive filler, and stir at 400 rpm for 50 minutes to obtain solution B; the conductive filler is silver-plated microspheres on the surface of silica;

[0058] Step 3: Add 3 parts of fumed silica to 100 parts of n-hexane and ultrasonicate for 100 minutes, then add 1 part of hydrogenated styrene-isoprene-styrene block copolymer and stir at 400 rpm for 50 minutes to obtain solution C;

[0059] Step 4: Stirring solution A and solution B at 25°C and 400 rpm for 4 hours to form a colloidal solution; uniformly coating the colloidal solution on a release film by a casting method, and drying at 37°C for 5 hours to obtain a precursor film; the casting temperature is 15°C, and the cast film thickness is maintained at 130 μm;

[0060] Step 5: Stretch the precursor film 100% and fix it, then spray solution C evenly onto the precursor film at a distance of 10 cm from the precursor film at a pressure of 0.3 MPa. The spraying amount is 1 ml / cm 2 , and dried at 25℃ for 2h to obtain a super-hydrophobic anisotropic conductive adhesive film.

[0061] Example 3

[0062] A method for preparing a super-hydrophobic anisotropic conductive adhesive film comprises the following steps:

[0063] Step 1: Dissolve 100 parts of epoxy resin E51 in 400 parts of tetrahydrofuran, then add 8 parts of nano-montmorillonite, 20 parts of curing agent and 2 parts of carboxyl-terminated liquid nitrile rubber, and stir at 350 rpm for 45 minutes to obtain solution A;

[0064] Step 2: 80 parts of thermoplastic polyurethane were dissolved in 300 parts of tetrahydrofuran, and then 1 part of hexamethylenediamine and 130 parts of conductive filler were added and stirred at 350 rpm for 45 minutes to obtain solution B; the conductive filler was silver-plated microspheres on the surface of silica;

[0065] Step 3: 5 parts of fumed silica were added to 90 parts of n-hexane, and the mixture was ultrasonically treated for 95 minutes. Then, 2 parts of hydrogenated styrene-isoprene-styrene block copolymer were added and stirred at 350 rpm for 45 minutes to obtain a solution C.

[0066] Step 4: Stirring solution A and solution B at 25°C and 350 rpm for 5 hours to form a colloidal solution; uniformly coating the colloidal solution on a release film by a casting method, and drying at 33°C for 6 hours to obtain a precursor film; the casting temperature is 20°C, and the cast film thickness is maintained at 110 μm;

[0067] Step 5: Stretch the precursor film by 120% and fix it. Then spray solution C evenly onto the precursor film at a distance of 7 cm from the precursor film at a pressure of 0.4 MPa. The spraying amount is 3 ml / cm 2 , and dried at 25℃ for 3h to obtain a super-hydrophobic anisotropic conductive adhesive film.

[0068] Example 4

[0069] A method for preparing a super-hydrophobic anisotropic conductive adhesive film comprises the following steps:

[0070] Step 1: Dissolve 100 parts of epoxy resin E51 in 400 parts of tetrahydrofuran, then add 10 parts of nano-aluminum hydroxide, 20 parts of curing agent and 2 parts of carboxyl-terminated liquid nitrile rubber and stir at 450 rpm for 55 minutes to obtain solution A;

[0071] Step 2: Dissolve 90 parts of thermoplastic polyurethane in 300 parts of tetrahydrofuran, then add 1 part of hexamethylenediamine and 130 parts of conductive filler, and stir at 450 rpm for 55 minutes to obtain solution B; the conductive filler is silver-plated microspheres on the surface of silica;

[0072] Step 3: 5 parts of fumed silica were added to 110 parts of n-hexane, and the mixture was ultrasonically treated for 110 minutes. Then, 2 parts of hydrogenated styrene-isoprene-styrene block copolymer were added and stirred at 450 rpm for 55 minutes to obtain a solution C.

[0073] Step 4: Stirring solution A and solution B at 28°C and 450 rpm for 4 hours to form a colloidal solution; uniformly coating the colloidal solution on a release film by a casting method, and drying at 36°C for 7 hours to obtain a precursor film; the casting temperature is 30°C, and the cast film thickness is maintained at 100 μm;

[0074] Step 5: Stretch the precursor film by 140% and fix it. Then spray solution C evenly onto the precursor film at a distance of 12 cm and a pressure of 0.4 MPa. The spraying amount is 4 ml / cm 2, and dried at 27°C for 4 h to obtain a super-hydrophobic anisotropic conductive adhesive film.

[0075] Example 5

[0076] A method for preparing a super-hydrophobic anisotropic conductive adhesive film comprises the following steps:

[0077] Step 1: Dissolve 100 parts of epoxy resin E54 in 400 parts of tetrahydrofuran, then add 8 parts of nano-aluminum hydroxide, 20 parts of curing agent and 2 parts of carboxyl-terminated liquid nitrile rubber, and stir at 480 rpm for 58 minutes to obtain solution A;

[0078] Step 2: 90 parts of thermoplastic polyurethane were dissolved in 300 parts of tetrahydrofuran, and then 1 part of hexamethylenediamine and 130 parts of conductive filler were added and stirred at 480 rpm for 53 minutes to obtain solution B; the conductive filler was nickel-plated microspheres on the surface of silica;

[0079] Step 3: 5 parts of fumed silica were added to 120 parts of n-hexane, and the mixture was ultrasonically treated for 115 minutes. Then, 2 parts of hydrogenated styrene-isoprene-styrene block copolymer were added and stirred at 480 rpm for 58 minutes to obtain a solution C.

[0080] Step 4: Stirring solution A and solution B at 29°C and 480 rpm for 4 hours to form a colloidal solution; uniformly coating the colloidal solution on a release film by a casting method, and drying at 38°C for 8 hours to obtain a precursor film; the casting temperature is 18°C, and the cast film thickness is maintained at 90 μm;

[0081] Step 5: Stretch the precursor film by 160% and fix it. Then spray solution C evenly onto the precursor film at a distance of 14 cm from the precursor film at a pressure of 0.3 MPa. The spraying amount is 5 ml / cm 2 , and dried at 28°C for 5h to obtain a super-hydrophobic anisotropic conductive adhesive film.

[0082] Example 6

[0083] A method for preparing a super-hydrophobic anisotropic conductive adhesive film comprises the following steps:

[0084] Step 1: Dissolve 100 parts of epoxy resin E54 in 400 parts of tetrahydrofuran, then add 8 parts of nano-silica, 20 parts of curing agent and 2 parts of carboxyl-terminated liquid nitrile rubber, and stir at 500 rpm for 60 minutes to obtain solution A;

[0085] Step 2: Dissolve 70 parts of thermoplastic polyurethane in 300 parts of tetrahydrofuran, then add 1 part of hexamethylenediamine and 130 parts of conductive filler, and stir at 500 rpm for 60 minutes to obtain solution B; the conductive filler is nickel-plated microspheres on the surface of silica;

[0086] Step 3: 5 parts of fumed silica were added to 100 parts of n-hexane and ultrasonicated for 120 minutes, followed by adding 2 parts of hydrogenated styrene-isoprene-styrene block copolymer and stirring at 500 rpm for 60 minutes to obtain solution C;

[0087] Step 4: Stirring solution A and solution B at 30°C and 500 rpm for 6 hours to form a colloidal solution; uniformly coating the colloidal solution on a release film by a casting method, and drying at 40°C for 9 hours to obtain a precursor film; the casting temperature is 28°C, and the cast film thickness is maintained at 80 μm;

[0088] Step 5: Stretch the precursor film 180% and fix it. Then spray solution C evenly onto the precursor film at a distance of 15 cm and a pressure of 0.5 MPa. The spraying amount is 6 ml / cm 2 , and dried at 30℃ for 5h to obtain a super-hydrophobic anisotropic conductive adhesive film.

[0089] Example 7

[0090] A method for preparing a super-hydrophobic anisotropic conductive adhesive film comprises the following steps:

[0091] Step 1: Dissolve 100 parts of epoxy resin E54 in 400 parts of tetrahydrofuran, then add 8 parts of nano-silica, 20 parts of curing agent and 2 parts of carboxyl-terminated liquid nitrile rubber and stir at 310 rpm for 42 minutes to obtain solution A;

[0092] Step 2: Dissolve 70 parts of thermoplastic polyurethane in 300 parts of tetrahydrofuran, then add 1 part of hexamethylenediamine and 130 parts of conductive filler, and stir at 310 rpm for 42 minutes to obtain solution B; the conductive filler is nickel-plated microspheres on the surface of silica;

[0093] Step 3: 5 parts of fumed silica were added to 100 parts of n-hexane and ultrasonicated for 93 minutes, followed by addition of 2 parts of hydrogenated styrene-isoprene-styrene block copolymer and stirring at 310 rpm for 42 minutes to obtain solution C;

[0094] Step 4: Stirring solution A and solution B at 22°C and 310 rpm for 4 hours to form a colloidal solution; uniformly coating the colloidal solution on a release film by a casting method, and drying at 36°C for 10 hours to obtain a precursor film; the casting temperature is 25°C, and the cast film thickness is maintained at 70 μm;

[0095] Step 5: Stretch the precursor film by 140% and fix it. Then spray Solution C evenly onto the precursor film at a distance of 8 cm from the precursor film at a pressure of 0.2 MPa. The spraying amount is 7 ml / cm2 , and dried at 22°C for 5h to obtain a super-hydrophobic anisotropic conductive adhesive film.

[0096] Example 8

[0097] A method for preparing a super-hydrophobic anisotropic conductive adhesive film comprises the following steps:

[0098] Step 1: Dissolve 100 parts of epoxy resin E54 in 400 parts of tetrahydrofuran, then add 8 parts of nano-silica, 20 parts of curing agent and 2 parts of carboxyl-terminated liquid nitrile rubber, and stir at 320 rpm for 43 minutes to obtain solution A;

[0099] Step 2: Dissolve 70 parts of thermoplastic polyurethane in 300 parts of tetrahydrofuran, then add 1 part of hexamethylenediamine and 130 parts of conductive filler, and stir at 320 rpm for 43 minutes to obtain solution B; the conductive filler is nickel-plated microspheres on the surface of silica;

[0100] Step 3: 5 parts of fumed silica were added to 100 parts of n-hexane and ultrasonicated for 100 minutes, followed by addition of 2 parts of hydrogenated styrene-isoprene-styrene block copolymer and stirring at 340 rpm for 52 minutes to obtain solution C;

[0101] Step 4: Stirring solution A and solution B at 24°C and 420 rpm for 5 hours to form a colloidal solution; uniformly coating the colloidal solution on a release film by a casting method, and drying at 38°C for 10 hours to obtain a precursor film; the casting temperature is 25°C, and the cast film thickness is maintained at 50 μm;

[0102] Step 5: Stretch the precursor film 100% and fix it, then spray solution C evenly onto the precursor film at a distance of 9 cm from the precursor film at a pressure of 0.4 MPa. The spraying amount is 8 ml / cm 2 , and dried at 26°C for 5h to obtain a super-hydrophobic anisotropic conductive adhesive film.

[0103] Comparative Example 1

[0104] The processes and raw materials of Comparative Example 1 are the same as those of Example 1, with the only difference being that the C solution in step 3 is not prepared and the spraying process in step 5 is removed. Finally, an anisotropic conductive film that is not super-hydrophobically modified is obtained, referred to as ACF.

[0105] Since Solution C was not prepared, the film was not modified, resulting in a purely anisotropic conductive film with no superhydrophobic surface structure. As shown in Table 1, the contact angle is only 63°, indicating a lack of superhydrophobic properties. This lack of superhydrophobic properties does not provide effective protection against moisture erosion. Over time, the external environment can affect its conductivity, leading to increased resistance and even failure of electronic component connections. This lack of long-term stability guarantees for these components.

[0106] Comparative Example 2

[0107] The processes and raw materials of Comparative Example 2 are the same as those of Example 1. The only difference is that in step 5, the precursor film is stretched 90% and fixed to prepare a hydrophobic anisotropic conductive film, referred to as hydrophobically modified ACF.

[0108] The present invention uses solution C to directly modify ACF, but cannot obtain good hydrophobic properties, so the precursor film is stretched, such as Figure 2 (b) Figure 2 (c) and Figure 3 As shown, in Comparative Example 2, the contact angle is only 130° after the stretching rate of the precursor film reaches 90%, which cannot fill the pores of the original ACF well, cannot achieve superhydrophobic performance, and cannot effectively block the erosion of moisture on the conductive film; while in Example 1, when the stretching rate of the precursor film is 100%, its contact angle reaches 150°. At this stretching rate, solution C can more easily penetrate into the small pores of the ACF, so that solution C is more evenly attached to the surface of the film, and with the increase of the stretching amount, more pores are exposed and filled by solution C, so that the superhydrophobic modified ACF has obvious superhydrophobic properties; compared with Comparative Example 2, the superhydrophobic modified ACF prepared in Example 1 can effectively block the erosion of moisture on the conductive film, has excellent anti-fouling, moisture resistance and durability, reduces the impact of the environment on the conductive performance, and significantly improves the reliability of the device in a high humidity environment.

[0109] See also Figure 1 , Figure 1 (a) is the original ACF of comparative example 1, Figure 1 (b) is the super-hydrophobic modified ACF prepared in Example 1. It can be seen that compared with the original ACF, a large number of porous structures appear on the surface of the super-hydrophobic modified ACF, with many holes of different sizes, forming many micro-nano structures. The micro-nano structure can capture a large amount of air, so that its contact angle with water reaches more than 150°. The super-hydrophobic structure formed effectively blocks the erosion of moisture on the conductive adhesive film, reduces the impact of the environment on the conductive performance, and significantly improves the reliability of the device in a high-humidity environment.

[0110] See also Figure 2 , Figure 2 (a) is the contact angle test diagram of the original ACF of Comparative Example 1, Figure 2 (b) is the contact angle test diagram of the hydrophobically modified ACF prepared in Comparative Example 2. Figure 2 (c) is the contact angle test diagram of the super-hydrophobic modified ACF prepared in Example 1; it can be seen that the hydrophobic performance of the super-hydrophobic modified ACF is greatly improved, and as the stretching rate gradually increases to 100%, its contact angle with water reaches more than 150°, effectively blocking the erosion of moisture on the conductive adhesive film, reducing the impact of the environment on the conductive performance, and significantly improving the reliability of the device in a high-humidity environment.

[0111] See also Figure 3 , which is a test comparison chart of the effect of different stretching rates on the hydrophobic properties of super-hydrophobic modified ACF. It can be seen that: as the stretching rate gradually increases to 100%, its contact angle with water reaches more than 150°, greatly improving the hydrophobic properties of the conductive film, effectively blocking the erosion of water on the conductive film, reducing the impact of the environment on the conductive properties, and significantly improving the reliability of the device in high-humidity environments.

[0112] See also Figure 4 The shear strength of the superhydrophobic modified ACF only decreased by 0.1MPa. In this field, the shear strength change within 0.1MPa is within the normal error range. It can be seen that after the anisotropic conductive film is superhydrophobic modified, its shear strength is slightly affected and does not affect its normal use.

[0113] See also Figure 5 When the droplet is ≤6 μL, the water droplet cannot stay on the super-hydrophobic modified ACF surface prepared in Example 1; Figure 6 , Figure 6 (a) shows the super-hydrophobic modified ACF and the original ACF placed on top of the red ink. Figure 6 (b) shows the super-hydrophobic modified ACF and the original ACF placed in red ink. Figure 6 (c) shows that the super-hydrophobic modified ACF and the original ACF were placed in red ink for 10 seconds and then taken out. The super-hydrophobic modified ACF did not have any residual ink, while the original ACF had a lot of residual ink; see Figure 7 , Figure 7 (a) shows carbon black powder sprinkled on super hydrophobic modified ACF. Figure 7 (b) is to use deionized water in a rubber-tipped dropper to rinse the carbon black on the super-hydrophobic modified ACF. Figure 7 (c) in the figure shows the super-hydrophobic modified ACF after rinsing for 10 seconds. It can be seen that the carbon black is basically rinsed clean without any residue. In summary, it can be seen that water droplets and dirt are difficult to adhere to the super-hydrophobic modified ACF, which not only reduces the frequency of cleaning and maintenance, but also reduces the change in contact resistance caused by the accumulation of pollutants.

[0114] See also Figure 8 , Figure 8 (a) is the absorbent cotton placed on top of the red ink. Figure 8 (b) is to place the absorbent cotton into the red ink. Figure 8 (c) shows that the absorbent cotton was placed in the red ink and then taken out after 10 seconds. It can be seen that the ordinary absorbent cotton was fully absorbed by the red ink; see Figure 9 , Figure 9 (a) is a piece of absorbent cotton soaked in solution C prepared in step 3 of Example 1 for 3 hours, taken out and air-dried at 25°C for 5 hours, and placed on top of the red ink. Figure 9 (b) is to place the absorbent cotton soaked in solution C and then dried in the red ink. Figure 9 (c) in the figure is a piece of degreased cotton soaked in solution C and then dried. It is placed in red ink and taken out after 10 seconds. It can be seen that there is no ink residue on the cotton. In summary, it can be seen that solution C prepared in step 3 has excellent hydrophobic properties and can be used to prepare a superhydrophobic modified ACF with excellent hydrophobic properties.

[0115] See also Figure 10 Figure 1 shows a schematic diagram of a wear resistance cycle test. A super-hydrophobic modified ACF was fixed to a tabletop, a piece of sandpaper of equal size was placed on top, and a 50g weight was placed on top of the sandpaper. One cycle consisted of pushing and pulling the super-hydrophobic modified ACF from one end to the other and back again. Table 1 shows the contact angle changes after 800 wear resistance cycles. After the test, the contact angles of Comparative Example 2 and Examples 1-8 all decreased by less than 5°, a very small decrease. This demonstrates that the super-hydrophobic modified anisotropic conductive adhesive film has excellent wear resistance and can maintain excellent hydrophobic properties even in harsh environments, providing sufficient protection for the effective connection of electronic components.

[0116] As shown in Table 1, the Z-axis resistance variation of the superhydrophobic modified ACF is within 10% compared to both the original ACF and the hydrophobic modified ACF, and the X- and Y-axis resistances are both greater than 10^8Ω. A resistance variation within 10% is considered normal in this field. This indicates that the anisotropic conductivity of the anisotropic conductive film is not affected by the superhydrophobic modification. Furthermore, the Z-axis resistance variation of the superhydrophobic modified ACF is minimal, not affecting its normal use. Furthermore, the contact angle data in Table 1 demonstrates that the hydrophobicity of the superhydrophobic modified ACF is significantly enhanced. As the stretching rate gradually increases to 100%, the water contact angle reaches over 150°, forming a superhydrophobic structure. This significantly enhances the hydrophobicity of the superhydrophobic modified ACF, effectively blocking water erosion on the conductive film, reducing the impact of the environment on its conductivity, and significantly improving the reliability of the device in high-humidity environments.

[0117] Table 1 Comparison of various properties of the embodiments and comparative examples

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[0119]

[0120] In summary, the present invention provides a super-hydrophobic anisotropic conductive adhesive film and its preparation method, addressing issues such as the tendency of conventional conductive adhesive films to lose conductivity in humid and highly polluted environments, suffer from short service life, and are susceptible to dust or moisture adsorption. This film is widely applicable to flexible electronics, liquid crystal display modules, camera modules, touch screens, smart wearable devices, 5G communication modules, high-end sensors, and other fields. It is particularly well-suited for applications requiring extremely high moisture and dirt resistance and reliability, providing an innovative solution for advanced electronic packaging.

Claims

1. A super-hydrophobic anisotropic conductive adhesive film, characterized in that: The raw materials of the conductive adhesive film include the following components in parts by mass: 100 parts of epoxy resin, 70-100 parts of thermoplastic polyurethane, 90-150 parts of conductive filler, 15-25 parts of curing agent, 1-1.5 parts of hexamethylenediamine, 1-2 parts of terminal carboxyl liquid nitrile rubber, 5-10 parts of film-forming additive, 1-2 parts of hydrogenated styrene-isoprene-styrene block copolymer, and 2-5 parts of fumed silica.

2. The super-hydrophobic anisotropic conductive adhesive film according to claim 1, wherein: The conductive filler is a silver-plated microsphere on the surface of silicon dioxide or a nickel-plated microsphere on the surface of silicon dioxide; the diameter of the silicon dioxide microsphere is 3-10 μm, and the diameter of the silver-plated silicon dioxide microsphere or the nickel-plated silicon dioxide microsphere is 5-13 μm.

3. The super-hydrophobic anisotropic conductive adhesive film according to claim 1, wherein: The film-forming additive is one of nano silicon dioxide, nano montmorillonite and nano aluminum hydroxide; and the curing agent has a latent property of 3 to 6 months.

4. A method for preparing a super-hydrophobic anisotropic conductive adhesive film, characterized in that: The steps include: Step 1: adding a film-forming additive, a curing agent, and a carboxyl-terminated liquid nitrile rubber to an epoxy resin solution and stirring, thereby obtaining a solution A; adding hexamethylenediamine and a conductive filler to a thermoplastic polyurethane solution and stirring, thereby obtaining a solution B; dispersing fumed silica in n-hexane and ultrasonically treating the solution; and then adding hydrogenated styrene-isoprene-styrene block copolymer and stirring, thereby obtaining a solution C; Step 2: Mixing solution A and solution B to form a colloidal solution; coating the colloidal solution on a release film by a casting method, and drying to obtain a precursor film; Step 3: stretching and fixing the precursor film, wherein the stretching rate of the precursor film is 100-180%; then spraying solution C evenly onto the precursor film, performing superhydrophobic modification on the precursor film, and drying to obtain a superhydrophobic anisotropic conductive film.

5. The method for preparing a super-hydrophobic anisotropic conductive adhesive film according to claim 1, wherein: In step 1, the epoxy resin solution is prepared by dissolving 100 parts of epoxy resin in 400 parts of tetrahydrofuran; and the thermoplastic polyurethane solution is prepared by dissolving 70-100 parts of thermoplastic polyurethane in 300 parts of tetrahydrofuran.

6. The method for preparing a super-hydrophobic anisotropic conductive adhesive film according to claim 1, wherein: In step one, the mass fractions of the film-forming additive, curing agent, carboxyl-terminated liquid nitrile rubber, hexamethylenediamine, conductive filler, fumed silica, n-hexane, and hydrogenated styrene-isoprene-styrene block copolymer are 5-10 parts, 15-25 parts, 1-2 parts, 1-1.5 parts, 90-150 parts, 2-5 parts, 80-120 parts, and 1-2 parts.

7. The method for preparing a super-hydrophobic anisotropic conductive adhesive film according to claim 1, wherein: In step 1, the stirring speed is 300-500 rpm, and the time is 40-60 min; the ultrasonic treatment time is 90-120 min.

8. The method for preparing a super-hydrophobic anisotropic conductive adhesive film according to claim 1, wherein: In step 2, the stirring process is: stirring at 20-30° C. and 300-500 rpm for 3-6 hours.

9. The method for preparing a super-hydrophobic anisotropic conductive adhesive film according to claim 1, wherein: In step 2, the casting temperature is 15-30° C., and the thickness of the cast film is maintained at 10-40 μm.

10. The method for preparing a super-hydrophobic anisotropic conductive adhesive film according to claim 1, wherein: In step 3, the nozzle diameter of the spray gun is 1.5 mm, and the spraying amount is 1-8 ml / cm 2 , the spraying distance is 5-15cm, and the spraying pressure is 0.2-0.5MPa.

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