Water-resistant anisotropic conductive adhesive film and preparation method thereof
By introducing water-resistant polyurethane prepolymer into anisotropic conductive films, a hydrophobic barrier and cross-linking network are formed, solving the water absorption problem of the films in high temperature and high humidity environments, and improving conductivity stability and adhesion reliability, making them suitable for electronic packaging.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-09
- Publication Date
- 2026-04-07
AI Technical Summary
Existing anisotropic conductive films are prone to absorbing water in high temperature and high humidity environments, leading to conductivity decay and interface delamination, which affects the long-term reliability of electronic components. Existing improvement methods, such as adding hydrophobic fillers or chemical modification, have problems such as increased viscosity or increased cost.
A water-resistant polyurethane prepolymer is used to enhance the water resistance and flexibility of the film by forming a hydrophobic barrier and a dense cross-linked network on the film surface, combined with a flexible polyolefin structure. The preparation method includes mixing reactive monomers, resins, fillers and conductive particles to form a water-resistant anisotropic conductive film.
It significantly reduces the water absorption rate of the adhesive film, maintains conductivity stability and interfacial adhesion, improves reliability in humid and hot environments, exhibits small changes in conduction resistance, and maintains high adhesion strength, thus solving the performance degradation problem of traditional adhesive films in high humidity environments.
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Figure CN121801520A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of anisotropic conductive adhesive film, in particular to a water-resistant anisotropic conductive adhesive film and a preparation method thereof. BACKGROUND
[0002] Anisotropic conductive adhesive film (ACF) is a key material for electronic packaging, and its performance directly affects the reliability of microcircuit connection. The poor water resistance of ACF film is a key problem affecting the long-term reliability of electronic components.
[0003] Traditional ACF films are mainly based on epoxy resin or acrylate as the main resin, which can easily cause resin matrix swelling and water absorption under high temperature and humidity environment (such as 85℃ / 85%RH), and the distance between conductive particles increases, thereby causing conductivity decay; at the same time, water molecules invade the bonding interface, causing interface delamination and peel strength decrease, thereby causing conductivity decay.
[0004] To improve water resistance, the existing technology mainly adopts two schemes: (1) Physical shielding method: adding hydrophobic fillers (such as silicon dioxide, calcium fluoride), but it will cause the viscosity to rise, which will affect the uniformity of coating; (2) Chemical modification method: such as epoxy resin grafted long-chain alkyl (such as glycidyl stearate), its water absorption rate is still >2.5%; such as acrylate copolymerization of fluorine-containing monomers (such as methacrylic acid dodecafluoroheptyl ester), the cost increases by 3~5 times and the flexibility deteriorates.
[0005] Therefore, it is urgent to develop a kind of anisotropic conductive adhesive film with water resistance and structural flexibility and a preparation method thereof. SUMMARY
[0006] In view of the deficiencies of the prior art, the present application provides a water-resistant anisotropic conductive adhesive film and a preparation method thereof.
[0007] To achieve the above-mentioned purpose, the following technical solutions are adopted: A water-resistant anisotropic conductive adhesive film, comprising the following components by weight fraction: 1-60 parts of reactive monomer; 1-60 parts of reactive resin; 5-60 parts of film-forming resin; 1-40 parts of water-resistant polyurethane prepolymer; 1-35 parts of filler; 0.1-10 parts of initiator; 0.1-10 parts of polymerization inhibitor; 1-40 parts of conductive particles; 20-70 parts of solvent.
[0008] Preferably, the sum of the mass of the reactive monomer, the reactive resin, the film-forming resin accounts for 20-75% of the total mass of the adhesive film.
[0009] Preferably, the reactive monomer is one or a combination of acrylate, methacrylate, hydroxy acrylate, carboxyl acrylate, and vinyl ether.
[0010] Preferably, the reactive resin is a mixture of two or more of polyurethane acrylate, epoxy acrylate resin.
[0011] Preferably, the film-forming resin is a mixture of two or more of phenoxy resin, phenolic resin, polyurethane resin, and poly(meth)acrylate resin.
[0012] Preferably, the filler is one or a combination of inorganic mineral filler, functional filler, and organic filler.
[0013] Preferably, the initiator is organic peroxide or azo.
[0014] Preferably, the polymerization inhibitor is phenol, quinone, nitrobenzene, hindered amine, or inorganic salt.
[0015] Preferably, the solvent is one or a combination of toluene, acetone, ethanol, propylene glycol methyl ether acetate, cyclopentane, isopentane, and n-pentane. More preferably, the solvent is a combination of cyclopentane and toluene.
[0016] Preferably, the conductive particle is a nickel-gold double-layer coated polystyrene microsphere with a particle size of 1-10 um.
[0017] Preferably, the water-resistant polyurethane prepolymer is prepared by the following steps: (1) The raw materials of component A are weighed into a reaction kettle in proportion, stirred at 60°C for 1-3h, and a premix is obtained. The component A includes the following raw materials in mass percentage: Polyorganosiloxane diol 5-80%; Hydroxyl-terminated polyolefin diol 5-80%; Cashew nut shell oil diol 10-80%; Hydroxy acrylate 1-20%; Hardener 3-15%; Polymerization inhibitor 0.01-1%; (2) The polycarbonate diol and polyether diol in component B are weighed into a reaction kettle in proportion, vacuumed at 120-200°C for 2h, cooled to 60-80°C, and then a metering catalyst is added and uniformly dispersed, a metering diisocyanate is added, and the mixture is incubated for 10-36h, and the 2260-1 stop the reaction when the content of NCO groups is unchanged, to obtain a prepolymer 1; The B component comprises the following raw materials by mass percentage: Polycarbonate diol 10-80%; Polyether diol 10-80%; Diisocyanate 20-60%; Catalyst 0.01%-5%; (3) 10-60wt% of the premix, 30-60wt% of the prepolymer 1, and 0.01-5wt% of the catalyst are added to a reaction kettle, and reacted at 60-80℃ for 12-36h, until the NCO groups completely disappear, to obtain a water-resistant polyurethane prepolymer. -1 (3) 10-60wt% of the premix, 30-60wt% of the prepolymer 1, and 0.01-5wt% of the catalyst are added to a reaction kettle, and reacted at 60-80℃ for 12-36h, until the NCO groups completely disappear, to obtain a water-resistant polyurethane prepolymer.
[0018] Preferably, the terminal hydroxyl polyolefin diol is one or a combination of terminal hydroxyl polybutadiene-acrylonitrile, terminal hydroxyl butadiene styrene rubber, and terminal hydroxyl polyisoprene.
[0019] Preferably, the hydroxyl acrylate is one or a combination of hydroxyethyl methacrylate and 4-hydroxybutyl acrylate.
[0020] Preferably, the hardener is one or a combination of small molecule diols, diamines, and ethanolamines.
[0021] Preferably, the polymerization inhibitor is one or a combination of hindered amines and hindered phenols.
[0022] Preferably, the polyether diol is one or a combination of polyoxypropylene glycol and polyoxybutylene glycol.
[0023] Preferably, the diisocyanate is one or a combination of toluene diisocyanate (TDI), isophorone diisocyanate (IPDI), diphenylmethane diisocyanate (MDI), dicyclohexylmethane diisocyanate (HMDI), hexamethylene diisocyanate (HDI), and lysine diisocyanate (LDI).
[0024] Preferably, the catalyst is one or a combination of organic tertiary amines, organometallics, and composite catalysts.
[0025] Preferably, the sum of the mass fractions of the polyorganosiloxane diol and the terminal hydroxyl polyolefin diol in the A component is ≥20%.
[0026] Preferably, the molar ratio of isocyanate groups to hydroxyl groups of the polyols in the B component is 2-3:1.
[0027] The application also discloses a preparation method of the water-resistant anisotropic conductive adhesive film. (1) The reactive resin, film-forming resin, water-resistant polyurethane prepolymer are mixed uniformly in a solvent, then the filler and conductive particles are mixed uniformly, finally the reactive monomer, initiator and polymerization inhibitor are added, and the coating liquid is obtained after uniform stirring at room temperature; (2) The coating liquid is scraped on the release film, pre-dried at 40 DEG C for 2-3 min, and main dried at 60 DEG C for 2-3 min, to obtain a water-resistant anisotropic conductive adhesive film.
[0028] Compared with the prior art, the present application has the following beneficial effects: The present application modifies the base resin, i.e. modifies the surface of the base resin and the base resin itself, so as to improve the water resistance of the ACF adhesive film.
[0029] The breakthrough value of the water-resistant polyurethane prepolymer in the present application lies in that it can realize the synergism of film surface water resistance + intrinsic water resistance + structural flexibility through molecular design: - Hydrophobic chain segment directional enrichment: polyorganosilicon diol (surface energy < 22 mN / m) and polypropylene oxide diol (—CH3 side chain shielding water molecules) form a dynamic hydrophobic barrier on the surface of the adhesive film; - Dense crosslinking network: polycarbonate diol (—O—C(=O)—O— group resistant to hydrolysis) and 1,4-butanediol chain extension form a hard segment microcrystalline region to inhibit water molecule diffusion; - Polyolefin flexible buffer: the carbon chain structure (—[CH2—CH2] n ) of the hydroxyl-terminated polyolefin diol offsets internal stress, and the adhesive strength retention rate is > 85% after hygrothermal cycling. BRIEF DESCRIPTION OF DRAWINGS
[0030] Figure 1 is the infrared spectrum of the prepolymer 1 of the present application; Figure 2 is the infrared spectrum of the water-resistant polyurethane prepolymer of the present application; Figure 3 is the surface contact angle test diagram of the ACF adhesive film prepared in Example 1 of the present application (WCA = 113.48°); Figure 4 is the surface contact angle test diagram of the ACF adhesive film prepared in Example 2 of the present application (WCA = 116.67°); Figure 5 is the surface contact angle test diagram of the ACF adhesive film prepared in Example 3 of the present application (WCA = 109.23°); Figure 6 is the surface contact angle test diagram of the ACF adhesive film prepared in Comparative Example 1 of the present application (WCA = 86.57°); Figure 7is the ACF adhesive film surface contact angle test figure (WCA = 85.971 °) of the ACF adhesive film prepared by the present application comparative example 2; Figure 8 is the ACF adhesive film surface contact angle test figure (WCA = 73.04 °) of the ACF adhesive film prepared by the present application comparative example 3. DETAILED DESCRIPTION
[0031] The present application will be further described in conjunction with examples, but it should be noted that the examples do not constitute a limitation on the scope of protection required by the present application.
[0032] Unless otherwise defined, the technical terms or scientific terms used in the present application shall be understood as the usual meaning understood by persons having ordinary skills in the art to which the present application belongs.
[0033] A water-resistant anisotropic conductive adhesive film, comprising the following components in parts by weight: 1-60 parts of reactive monomer; 1-60 parts of reactive resin; 5-60 parts of film-forming resin; 1-40 parts of water-resistant polyurethane prepolymer; 1-35 parts of filler; 0.1-10 parts of initiator; 0.1-10 parts of polymerization inhibitor; 1-40 parts of conductive particles; 20-70 parts of solvent.
[0034] In some embodiments, the sum of the mass of the reactive monomer, the reactive resin, and the film-forming resin accounts for 20-75% of the total mass of the adhesive film.
[0035] In some embodiments, the reactive monomer is one or a combination of acrylate, methacrylate, hydroxy acrylate, carboxyl acrylate, and vinyl ether. The reactive resin is a mixture of two or more of polyurethane acrylate, epoxy acrylate resin. The film-forming resin is a mixture of two or more of phenoxy resin, phenolic resin, polyurethane resin, and poly(meth)acrylate resin. The filler is one or a combination of inorganic mineral filler, functional filler, and organic filler. The initiator is organic peroxide or azo. The polymerization inhibitor is phenol, quinone, nitrobenzene, hindered amine, or inorganic salt. The solvent is one or a combination of toluene, acetone, ethanol, propylene glycol methyl ether acetate, cyclopentane, isopentane, and n-pentane. Preferably, the solvent is a combination of cyclopentane and toluene. The conductive particles are nickel-gold double-layer coated polystyrene microspheres with a particle size of 1-10 um.
[0036] In some embodiments, the water-resistant polyurethane prepolymer is prepared by the following steps: (1) The raw materials of A component are weighed into the reactor in proportion, stirred at 60℃ for 1-3h to obtain a premix; The A component includes the following raw materials by mass percentage: Polyorganosiloxane diol 5-80%; Hydroxyl-terminated polyolefin diol 5-80%; Cashew nut shell oil diol 10-80%; Hydroxyl acrylate 1-20%; Hardener 3-15%; Polymerization inhibitor 0.01-1%; (2) The polycarbonate diol and polyether diol in B component are weighed into the reactor in proportion, vacuumed at 120-200℃ for 2h, cooled to 60-80℃, added with a measured amount of catalyst, dispersed uniformly, added with a measured amount of diisocyanate, and incubated for 10-36h. The reaction is stopped when the NCO group content remains unchanged, as determined by infrared measurement at 2260 -1 cm-1, to obtain prepolymer 1; The B component includes the following raw materials by mass percentage: Polycarbonate diol 10-80%; Polyether diol 10-80%; Diisocyanate 20-60%; Catalyst 0.01%-5%; (3) 10-60wt% of the premix, 30-60wt% of prepolymer 1, and 0.01-5wt% of catalyst are added into the reactor, and reacted at 60-80℃ for 12-36h until the NCO group completely disappears, as determined by infrared measurement at 2260 -1 cm-1, to obtain water-resistant polyurethane prepolymer.
[0037] The hydroxyl-terminated polyolefin diol is one or a combination of hydroxyl-terminated polybutadiene-acrylonitrile, hydroxyl-terminated butadiene styrene rubber, and hydroxyl-terminated polyisoprene. The hydroxyl acrylate is one or a combination of hydroxyethyl methacrylate and 4-hydroxybutyl acrylate. The hardener is one or a combination of small molecule diol, diamine, and ethanolamine. The polymerization inhibitor is one or a combination of hindered amine and hindered phenol. The polyether diol is one or a combination of polyoxypropylene diol and polyoxybutylene diol. The diisocyanate is one or a combination of toluene diisocyanate (TDI), isophorone diisocyanate (IPDI), diphenyl methane diisocyanate (MDI), dicyclohexyl methane diisocyanate (HMDI), hexamethylene diisocyanate (HDI), and lysine diisocyanate (LDI). The catalyst is one or a combination of organic tertiary amine, organic metal, and composite catalyst.
[0038] In some embodiments, the sum of the mass fractions of the polyorganosiloxane diol and the hydroxyl-terminated polyolefin diol in the A component is ≥ 20%.
[0039] In some embodiments, the molar ratio of isocyanate groups to hydroxyl groups of the polyol in the B component is 2-3:1.
[0040] The preparation method of the water-resistant anisotropic conductive adhesive film comprises the following steps: (1) The reactive resin, film-forming resin, water-resistant polyurethane prepolymer are uniformly mixed in a solvent, then the filler and conductive particles are uniformly mixed, and finally the reactive monomer, initiator and polymerization inhibitor are added, and the mixture is uniformly stirred at room temperature to obtain a coating liquid; (2) The coating liquid is scraped onto a release film, pre-dried at 40°C for 2-3 minutes, and main dried at 60°C for 2-3 minutes to obtain a water-resistant anisotropic conductive adhesive film.
[0041] In order to better illustrate the advantages of the present application, the following examples 1-3 and comparative examples 1-3 are compared: Example 1 A water-resistant anisotropic conductive adhesive film is prepared by the following method: (1) 15g of 2-ethylhexyl acrylate, 5g of polyurethane acrylate, 5g of phenoxy resin, 18g of water-resistant polyurethane prepolymer, 3g of silicon dioxide, and 2g of 10um nickel-gold double-layer coated polystyrene microspheres are uniformly dispersed in 40g of toluene and 10g of n-pentane, then 1g of benzoyl peroxide and 1g of p-methoxyphenol are uniformly dispersed to obtain a coating liquid with a solid content of 50%.
[0042] (2) The coating liquid is scraped onto a release film, pre-dried at 40°C for 3 minutes, and main dried at 60°C for 3 minutes to obtain a water-resistant anisotropic conductive adhesive film.
[0043] The preparation method of the water-resistant polyurethane prepolymer is as follows: ① 10g of polyorganosiloxane diol, 10g of hydroxyl-terminated polyolefin diol, 70g of cashew nut shell oil diol, 1g of hydroxy acrylate, 8g of 1,4-butanediol, and 1g of p-hydroxyanisole are weighed into a reaction kettle, stirred at 60°C for 1h to obtain a premix.
[0044] ② 19.5g of polycarbonate diol and 19.5g of polyether diol are weighed into a reaction kettle, vacuumed at 150°C for 2h, cooled to 80°C, 1g of 4,4'-dimethyl diethanolamine is uniformly dispersed, 28g of diphenylmethane diisocyanate is added, and the reaction is kept at 80°C for 24h. -1 The reaction is stopped when the NCO group content remains unchanged, and a prepolymer 1 is obtained, and its infrared spectrum is shown in Figure 1
[0045] ③Take the above 35.5g premix, 32g prepolymer 1, 0.5g 4,4'-dimethyl diethanolamine in the reaction kettle, 80℃ for 24h, to infrared measurement 2260 -1 NCO group completely disappeared, obtained water resistance polyurethane prepolymer, its infrared spectrum as shown in Figure 2 .
[0046] Example 2: A water resistance anisotropic conductive adhesive film, the preparation method is as follows: (1) 15g of 2-ethylhexyl acrylate, 5g of polyurethane acrylate, 5g of phenoxy resin, 18g of water resistance polyurethane prepolymer, 3g of silicon dioxide, 2g of 10um nickel gold double layer coated polystyrene microspheres, in 40g of toluene and 10g of n-pentane, after uniform dispersion, 1g of benzoyl peroxide, 1g of p-methoxyphenol is uniformly dispersed, to obtain a coating liquid with a solid content of 50%.
[0047] (2) the coating liquid is coated on the release film, pre-drying: 40℃, 3min, main drying: 60℃, 3min, to obtain a water resistance anisotropic conductive adhesive film.
[0048] Among them, the preparation method of water resistance polyurethane prepolymer is as follows: ① polyorganosiloxane diol 15g, hydroxyl polyolefin diol 5g, cashew nut shell oil diol 70g, hydroxy acrylate 1g, 1,4-butanediol 8g, p-hydroxyanisole 1g; the above raw materials are weighed into the reaction kettle in proportion, stirred at 60℃ for 1h, to obtain a premix.
[0049] ② 19.5g polycarbonate diol, 19.5g polyether diol is weighed into the reaction kettle, 150℃ vacuum for 2h, the temperature is lowered to 80℃, 1g of 4,4'-dimethyl diethanolamine is added and uniformly dispersed, 28g of diphenyl methane diisocyanate is added, and the reaction is kept for 24h. When the infrared measurement 2260 -1 NCO group content does not change, the reaction is stopped, to obtain prepolymer 1, its infrared spectrum as shown in Figure 1 .
[0050] ③Take the above 35.5g premix, 32g prepolymer 1, 0.5g 4,4'-dimethyl diethanolamine in the reaction kettle, 80℃ for 24h, to infrared measurement 2260 -1 NCO group completely disappeared, obtained water resistance polyurethane prepolymer, its infrared spectrum as shown in Figure 2 .
[0051] Example 3: A water resistance anisotropic conductive adhesive film, the preparation method is as follows: (1) 15 g of 2-ethylhexyl acrylate, 5 g of polyurethane acrylate, 5 g of phenoxy resin, 18 g of water-resistant polyurethane prepolymer, 3 g of silicon dioxide, and 2 g of 10 um nickel-gold double-layer coated polystyrene microspheres were uniformly dispersed in 40 g of toluene and 10 g of n-pentane, 1 g of benzoyl peroxide and 1 g of p-methoxyphenol were uniformly dispersed to obtain a coating liquid with a solid content of 50%.
[0052] (2) The coating liquid was blade-coated on a release film, pre-dried at 40°C for 3 min, and main-dried at 60°C for 3 min to obtain a water-resistant anisotropic conductive adhesive film.
[0053] The preparation method of the water-resistant polyurethane prepolymer is as follows: ① 5 g of polyorganosiloxane diol, 15 g of hydroxyl-terminated polyolefin diol, 70 g of cashew nut shell oil diol, 1 g of hydroxy acrylate, and 8 g of 1,4-butanediol, and 1 g of p-hydroxyanisole were weighed into a reaction kettle, stirred at 60°C for 1 h to obtain a premix.
[0054] ② 19.5 g of polycarbonate diol and 19.5 g of polyether diol were weighed into a reaction kettle, vacuumized at 150°C for 2 h, cooled to 80°C, 1 g of 4,4'-dimethyl diethanolamine was uniformly dispersed, 28 g of diphenylmethane diisocyanate was added, and the mixture was incubated for 24 h. The reaction was stopped when the NCO group content remained unchanged, as determined by infrared spectroscopy, to obtain a prepolymer 1, the infrared spectrum of which is shown in -1 . Figure 1
[0055] ③ 35.5 g of the above premix, 32 g of prepolymer 1, and 0.5 g of 4,4'-dimethyl diethanolamine were taken into a reaction kettle, and the mixture was reacted at 80°C for 24 h. The reaction was stopped when the NCO group completely disappeared, as determined by infrared spectroscopy, to obtain a water-resistant polyurethane prepolymer, the infrared spectrum of which is shown in -1 . Figure 2
[0056] Comparative Example 1 A water-resistant anisotropic conductive adhesive film was prepared as follows: (1) 15 g of 2-ethylhexyl acrylate, 5 g of polyurethane acrylate, 5 g of phenoxy resin, 18 g of water-resistant polyurethane prepolymer, 3 g of silicon dioxide, and 2 g of 10 um nickel-gold double-layer coated polystyrene microspheres were uniformly dispersed in 40 g of toluene and 10 g of n-pentane, 1 g of benzoyl peroxide and 1 g of p-methoxyphenol were uniformly dispersed to obtain a coating liquid with a solid content of 50%.
[0057] (2) The coating liquid was blade-coated on a release film, pre-dried at 40°C for 3 min, and main-dried at 60°C for 3 min to obtain a water-resistant anisotropic conductive adhesive film.
[0058] The preparation method of the water-resistant polyurethane prepolymer is as follows: ① 10 g of polyorganosiloxane diol, 80 g of cashew nut shell oil diol, 1 g of hydroxy acrylate, 8 g of 1,4-butanediol, and 1 g of p-hydroxyanisole are weighed into a reaction kettle in proportion, stirred at 60°C for 1 h, and a premix is obtained.
[0059] ② 19.5 g of polycarbonate diol and 19.5 g of polyether diol are weighed into a reaction kettle in proportion, vacuumized at 150°C for 2 h, cooled to 80°C, 1 g of 4,4'-dimethyl diethanolamine is added and uniformly dispersed, 28 g of diphenyl methane diisocyanate is added, and incubated for 24 h. The reaction is stopped when the NCO group content is determined to be 2260 -1 cm-1.
[0060] ③ The above 35.5 g of premix, 32 g of prepolymer 1, and 0.5 g of 4,4'-dimethyl diethanolamine are taken into a reaction kettle, reacted at 80°C for 24 h, and the NCO group is determined to be completely disappeared by infrared measurement at 2260 -1 cm-1, and a water-resistant polyurethane prepolymer is obtained.
[0061] Comparative Example 2: A water-resistant anisotropic conductive adhesive film is prepared by the following method: (1) 15 g of 2-ethylhexyl acrylate, 5 g of polyurethane acrylate, 5 g of phenoxy resin, 18 g of water-resistant polyurethane prepolymer, 3 g of silicon dioxide, and 2 g of 10 um nickel-gold double-layer coated polystyrene microspheres are uniformly dispersed in 40 g of toluene and 10 g of n-pentane, 1 g of benzoyl peroxide and 1 g of p-methoxyphenol are added and uniformly dispersed, and a coating liquid with a solid content of 50% is obtained.
[0062] (2) The coating liquid is coated on a release film, pre-dried at 40°C for 3 min, and main dried at 60°C for 3 min, and a water-resistant anisotropic conductive adhesive film is obtained.
[0063] The preparation method of the water-resistant polyurethane prepolymer is as follows: ① 10 g of polyorganosiloxane diol, 80 g of cashew nut shell oil diol, 1 g of hydroxy acrylate, 8 g of 1,4-butanediol, and 1 g of p-hydroxyanisole are weighed into a reaction kettle in proportion, stirred at 60°C for 1 h, and a premix is obtained.
[0064] ② 19.5 g of polycarbonate diol and 19.5 g of polyether diol are weighed into a reaction kettle in proportion, vacuumized at 150°C for 2 h, cooled to 80°C, 1 g of 4,4'-dimethyl diethanolamine is added and uniformly dispersed, 28 g of diphenyl methane diisocyanate is added, and incubated for 24 h. The reaction is stopped when the NCO group content is determined to be 2260-1 The reaction is stopped when the NCO group content is unchanged to obtain the prepolymer 1.
[0065] The 35.5 g of the premix, 32 g of the prepolymer 1 and 0.5 g of 4,4'-dimethyl diethanolamine are taken into a reaction kettle, and reacted at 80°C for 24 h. When the NCO group content is unchanged, the reaction is stopped, and the prepolymer 1 is obtained. -1 The reaction is stopped when the NCO group content is unchanged to obtain the prepolymer 1.
[0066] Comparative Example 3: A water-resistant anisotropic conductive adhesive film is prepared by the following method: (1) 15 g of 2-ethylhexyl acrylate, 5 g of polyurethane acrylate, 5 g of phenoxy resin, 18 g of water-resistant polyurethane prepolymer, 3 g of silicon dioxide, and 2 g of 10 um nickel-gold double-layer coated polystyrene microspheres are uniformly dispersed in 40 g of toluene and 10 g of n-pentane, 1 g of benzoyl peroxide and 1 g of p-methoxyphenol are added and uniformly dispersed to obtain a coating liquid with a solid content of 50%.
[0067] (2) The coating liquid is coated on a release film, pre-dried at 40°C for 3 min, and main dried at 60°C for 3 min to obtain a water-resistant anisotropic conductive adhesive film.
[0068] The water-resistant polyurethane prepolymer is prepared by the following method: (1) 90 g of cashew nut shell oil diol, 1 g of hydroxy acrylate, 8 g of 1,4-butanediol, and 1 g of p-hydroxyanisole are weighed into a reaction kettle, stirred at 60°C for 1 h to obtain a premix.
[0069] (2) 19.5 g of polycarbonate diol and 19.5 g of polyether diol b are weighed into a reaction kettle, vacuumized at 150°C for 2 h, cooled to 80°C, 1 g of 4,4'-dimethyl diethanolamine is added and uniformly dispersed, 28 g of diphenylmethane diisocyanate is added, and the temperature is kept for 24 h. When the NCO group content is unchanged, the reaction is stopped, and the prepolymer 1 is obtained. -1 The reaction is stopped when the NCO group content is unchanged to obtain the prepolymer 1.
[0070] The 35.5 g of the premix, 32 g of the prepolymer 1 and 0.5 g of 4,4'-dimethyl diethanolamine are taken into a reaction kettle, and reacted at 80°C for 24 h. When the NCO group content is unchanged, the reaction is stopped, and the prepolymer 1 is obtained. -1 The reaction is stopped when the NCO group content is unchanged to obtain the prepolymer 1.
[0071] After hot-pressing and curing, the interfacial adhesion, conduction resistance and water absorption of each sample were tested. Among them: the interfacial adhesion was measured by welding thrust machine, the conduction resistance was measured by four-probe method, and the water absorption was obtained by calculating the ratio of weight gain to initial mass (dry weight) after the sample was placed in 100℃ water for 2h. The specific data are shown in Table 1: Table 1 Test data of ACF adhesive obtained from examples 1-3 and comparative examples 1-3
[0072] Figures 3-8 is the test diagram of the surface contact angle of the ACF adhesive film obtained from examples 1-3 and comparative examples 1-3.
[0073] According to the comparison of experimental data of examples 1-3 and comparative examples 1-3, the following conclusions can be drawn: 1. Formulation optimization significantly improves comprehensive performance Examples 1-3 significantly improve the water resistance, conductive stability and bonding reliability of anisotropic conductive adhesive film (ACF) by simultaneously introducing polyorganosiloxane diol and hydroxyl-terminated polyolefin diol (total content of both is fixed at 20g, different proportions) into the water-resistant polyurethane prepolymer. Among them, examples 2 and 3 perform best in water absorption.
[0074] 2. Water resistance is the key The water absorption of examples is much lower than that of comparative examples, and the contact angle of examples is much higher than that of comparative examples, indicating that the hydrophobicity of polyorganosiloxane diol and the synergistic effect of the molecular chain of hydroxyl-terminated polyolefin diol effectively block the penetration of water, thereby ensuring the stability of the adhesive film in a humid environment.
[0075] 3. More stable conductive and adhesive performance After the "double 85" reliability test, the conduction resistance of examples changes less, and the adhesion strength retention rate is more than 85%. While the resistance of comparative examples increases significantly after humid heat aging, the adhesion strength decreases significantly, and the retention rate is less than 70%. This shows that the formulation of examples can better resist the performance degradation caused by humid heat aging.
[0076] 4. Lack of components leads to performance decline (1) The water absorption of comparative example 1 (without hydroxyl-terminated polyolefin diol) and comparative example 2 (without polyorganosiloxane diol) is more than 1.3%, and the resistance increases to more than 1.2Ω after reliability, indicating that the two components are indispensable.
[0077] (2) Comparative example 3 (both are absent) has the worst performance, further verifying that the synergistic effect of polyorganosiloxane and polyolefin diol is the key to improving water resistance and reliability.
[0078] 5. Conclusion The water-resistant polyurethane prepolymer compounded by polyorganosiloxane diol and hydroxyl-terminated polyolefin diol can significantly reduce the water absorption of ACF adhesive film, improve the conductive stability and interfacial adhesion in humid heat environment, and the comprehensive performance is optimal when the proportion of polyorganosiloxane diol is 75% (Example 2). The formulation design provides an effective way for the development of high-reliability anisotropic conductive adhesive film for electronic packaging.
[0079] Finally, it should be noted that: the above examples are only used to illustrate the technical solutions of the present application rather than limit it, although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that: the technical solutions of the present application can still be modified or replaced by equivalents, and these modifications or equivalent replacements cannot make the modified technical solutions deviate from the spirit and scope of the technical solutions of the present application.
Claims
1. A water-resistant anisotropic conductive adhesive film, characterized in that, Includes the following components by weight: 1-60 parts of reactive monomer; 1-60 parts of reactive resin; 5-60 parts of film-forming resin; 1-40 parts of water-resistant polyurethane prepolymer; 1-35 parts of filler; Initiator 0.1-10 parts; Polymerization inhibitor 0.1-10 parts; 1-40 parts of conductive particles; Solvent 20-70 parts.
2. The water-resistant anisotropic conductive film according to claim 1, characterized in that, The total mass of the reactive monomer, reactive resin, and film-forming resin accounts for 20-75% of the total mass of the film.
3. The water-resistant anisotropic conductive film according to claim 1, characterized in that, The reactive monomer is one or a combination of acrylates, methacrylates, hydroxyacrylates, carboxyacrylates, and vinyl ethers; The reactive resin is a mixture of two or more of polyurethane acrylate and epoxy acrylate resins; The film-forming resin is a mixture of two or more of the following: phenoxy resin, phenolic resin, polyurethane resin, and poly(meth)acrylate resin.
4. The water-resistant anisotropic conductive film according to claim 1, characterized in that, The packing material is one or a combination of inorganic mineral packing, functional packing, and organic packing. The initiator is an organic peroxide or azo compound; The polymerization inhibitor is a phenol, quinone, nitrobenzene, hindered amine, or inorganic salt; The solvent is one or a combination of toluene, acetone, ethanol, propylene glycol methyl ether acetate, cyclopentane, isopentane, and n-pentane.
5. The water-resistant anisotropic conductive film according to claim 1, characterized in that, The conductive particles are nickel-gold double-layer coated polystyrene microspheres with a particle size of 1-10 μm.
6. The water-resistant anisotropic conductive film according to claim 1, characterized in that, The water-resistant polyurethane prepolymer is prepared by the following steps: (1) Weigh the raw materials of component A into the reactor according to the proportion, and stir at 60°C for 1-3 hours to obtain the premix; Component A comprises the following raw materials by mass percentage: Polysilicon diol 5-80%; Hydroxyl-terminated polyolefin diols: 5-80%; Cashew shell oil diol content: 10-80%; Hydroxyacrylates 1-20%; Hardener 3-15%; Polymerization inhibitor 0.01-1%; (2) Weigh the polycarbonate diol and polyether diol from component B into the reactor according to the ratio, vacuum at 120-200℃ for 2 hours, cool to 60-80℃, add the metered catalyst, disperse evenly, add the metered diisocyanate, keep warm for 10-36 hours, and measure 2260 nm using infrared spectroscopy. -1 The reaction was stopped when the NCO group content remained unchanged, and prepolymer 1 was obtained. Component B comprises the following raw materials by mass percentage: Polycarbonate diol 10-80%; Polyether diol 10-80%; Diisocyanate 20-60%; Catalyst 0.01%-5%; (3) Add 10-60 wt% of the premix, 30-60 wt% of the prepolymer 1, and 0.01-5 wt% of the catalyst to the reactor, and react at 60-80℃ for 12-36 h, until the infrared spectroscopy reaches 2260. -1 The NCO groups completely disappear, resulting in a water-resistant polyurethane prepolymer.
7. The water-resistant anisotropic conductive film according to claim 6, characterized in that, The hydroxyl-terminated polyolefin diol is one or a combination of hydroxyl-terminated polybutadiene-acrylonitrile, hydroxyl-terminated styrene-butadiene rubber, and hydroxyl-terminated polyisoprene. The hydroxy acrylate is one or a combination of hydroxyethyl methacrylate and 4-hydroxybutyl acrylate; The hardening agent is one or a combination of small molecule diols, diamines, and ethanolamines; The polymerization inhibitor is one or a combination of hindered amines and hindered phenols; The polyether diol is one or a combination of polyoxypropylene glycol and polyoxybutene glycol. The diisocyanate is one or a combination of toluene diisocyanate (TDI), isophorone diisocyanate (IPDI), diphenylmethane diisocyanate (MDI), dicyclohexylmethane diisocyanate (HMDI), hexamethylene diisocyanate (HDI), and lysine diisocyanate (LDI). The catalyst is one or a combination of organic tertiary amines, organometallic catalysts, and composite catalysts.
8. The water-resistant anisotropic conductive film according to claim 6, characterized in that, The sum of the mass fractions of polyorganosilicon diol and hydroxyl-terminated polyolefin diol in component A is ≥20%.
9. The water-resistant anisotropic conductive film according to claim 6, characterized in that, The molar ratio of isocyanate groups to hydroxyl groups of polyols in component B is (2-3):
1.
10. The method for preparing a water-resistant anisotropic conductive film according to any one of claims 1 to 9, characterized in that, Includes the following steps: (1) After mixing the reactive resin, film-forming resin and water-resistant polyurethane prepolymer evenly in a solvent, add filler and conductive particles and mix evenly. Finally, add reactive monomer, initiator and polymerization inhibitor, stir evenly at room temperature to obtain coating liquid. (2) Apply the coating liquid to the release film, pre-dry: 40℃, 2-3 min, main drying: 60℃, 2-3 min, to obtain a water-resistant anisotropic conductive film.