CN115975595A - Antistatic conductive adhesive for circuit board - Google Patents
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Abstract
The invention discloses an antistatic conductive adhesive for a circuit board, which comprises the following components in parts by weight: 50-85 parts of nano-silver/functionalized graphene hybrid conductive filler, 10-40 parts of siloxane resin, 0.1-0.8 part of catalyst, 0.1-0.8 part of reinforcing agent, 0.1-0.5 part of inhibitor and 0.1-0.5 part of cross-linking agent. The nano silver/functionalized graphene hybridized conductive filler is prepared by taking perylene diimide-based nitrogen oxide obtained through preparation as a surfactant to carry out non-covalent functionalization on graphene nanosheets and then hybridizing the graphene nanosheets with silver acetate. The non-covalent bonding enhances the connection between the graphene and the metal silver particles, so that the conductivity can be enhanced, the mechanical property of the conductive adhesive can be improved by adding the graphene, and the performance tends to be more stable when the temperature changes.
Description
Technical Field
The invention relates to the technical field of adhesives, in particular to an antistatic conductive adhesive for a circuit board.
Background
The rapid progress of electronic information technology leads electronic products applied to aerospace, medical agriculture, chemical industry and daily life of people to be miniaturized and integrated, which puts higher requirements on the performance of packaging materials. Tin-lead solder has been used as a traditional packaging material for hundreds of years, but has the following disadvantages: the welding temperature of the tin-lead solder is higher than 200 ℃, and the tin-lead solder is easy to cause thermal deformation damage to electronic devices; the minimum solder pitch of the tin-lead solder is 650 microns. The packaging requirements of micro electronic products cannot be met, so that the development of tin-lead solder is limited; lead is a heavy metal causing irreversible damage and pollution to human bodies and the environment. With the increasing emphasis on health and environment, the use of lead-containing materials is limited or even prohibited in the world, and related measures are taken in various countries, and with the successive promulgation of the commands such as WEEE/RoHS, the lead-free packaging material is promoted to be a certain development trend. Since Henry Wolfso issued the first conductive adhesive in 1956, henry Wolfso has the advantages of high linear resolution, convenient operation process, environmental protection and the like, and becomes an ideal substitute product for tin-lead solder.
The conductive adhesive is a material having both conductivity and adhesiveness after being cured or dried. Which bonds the conductive filler together primarily by adhesive action to form a continuous conductive path. The conductive adhesives are mainly classified into four types according to structure, conductive direction, curing temperature, and resin type. The method is divided into the following steps according to the structure: intrinsic and composite conductive adhesives. The intrinsic conductive adhesive is a conjugated polymer with self conductive performance, such as polythiophene, polyacetylene, polyaniline and the like. The intrinsic conductive adhesive has high resistivity, but poor stability and higher cost. Is currently in the laboratory research 23428. The composite conductive adhesive is prepared by using resin as a matrix and providing conductive performance by using metal particles such as tin, lead, gold, silver, copper and the like, and is widely used in industry in the traditional sense. (2) The conductive direction is classified into ACA (anisotropic conductive adhesive) and ICA (isotropic conductive adhesive). ACA has a low content of conductive filler and is difficult to form a continuous conductive path. Insulating materials or conductive fillers with the outermost layer coated with the insulating materials are added, and certain pressure is applied to the Z-axis direction, so that the conductive material has conductivity in the Z-axis direction and does not have conductivity in X and Y axes. ACA is pressurized in the industrial production process, so that the process risk coefficient is large, the operation is difficult, and the ACA is not suitable for large-scale production. In contrast to ACA, ICA has the same conductivity in all directions. The conductive filler of ICA is mostly metal, polymer with metal plated on the surface, carbon material, or the like. The conductive filler of ICA has a large size and shape and a high content, and can form a continuous conductive path after the matrix resin is cured. The ICA is simple in preparation process, and the use temperature can be reduced by adjusting the curing agent, so that the loss of the electronic device caused by the temperature is reduced. (3) according to the curing temperature: low-temperature, medium-temperature and high-temperature types; the low-temperature (25-100 ℃) curing has low thermal damage to electronic devices, but has the defects of long curing time (18-20 h), unstable volume resistivity and the like, so that the conductivity is poor. The curing time is short (0.5-1 h) at medium temperature (100-150 ℃), the matching degree of the curing temperature and the temperature-resistant range of the electronic device is high, and the application is wide. The curing time at high temperature (150-300 ℃) is shortest, but the temperature is too high, so that metal particles are easy to oxidize, and the conductivity is reduced. (4) according to the matrix: thermoplastic and thermosetting conductive adhesives. The resin structure of the thermoplastic conductive adhesive is a long line type, and the cured thermoplastic conductive adhesive has good fluidity and reciprocatability, is beneficial to the disassembly of electronic devices, and can improve the reutilization rate of the electronic devices. But the adhesive has poor heat resistance and rigidity, has fluidity during curing, is easy to cause the displacement of electronic devices, reduces the precision of adhesive sites, and is not suitable for the adhesive requirements of microminiature integrated electronic devices. The resin of the thermosetting conductive adhesive and the curing agent are subjected to polymerization reaction to form a highly crosslinked network structure, and the thermosetting conductive adhesive has the characteristics of high temperature resistance, high hardness, high rigidity, difficulty in flowing and the like, and meets the development requirements of modern electronic devices.
At present, the conductive adhesive systems commonly used in the market are: epoxy systems, acrylic systems, silicone systems, etc., all have their own advantages and disadvantages. The epoxy resin has the advantages of good bonding performance and good bonding to different base materials. Good thermal stability and shear strength. However, epoxy resins have the disadvantage of a relatively high modulus and water absorption, which is generally possible, but when the epoxy system has a few micro-layers with the substrate, moisture can enter relatively easily, which in turn leads to a relatively high water absorption and a relatively high dielectric constant. The main advantage of acrylic resins is the variety of curing forms, since the reaction is a radical cure, which can be performed by light, heat, or photo-heat simultaneously. Acrylic resins generally have a relatively low viscosity, and the viscosity control range is relatively wide in the formulation. In addition, the tear strength of the adhesives made from acrylic resins is relatively high. However, the acrylic system is poor in weather resistance, is not particularly excellent in flame retardancy, and is likely to generate odor during use. The organosilicon system has the advantages of low stress, better stress resistance, flexibility, excellent high and low temperature resistance and weather resistance. Because the bond energy is comparatively large, the resin has good acid-base resistance and ultraviolet resistance. The disadvantage is that the adhesive strength is not as high as that of epoxy resin and acrylic resin.
Chinese patent 202010373987.7 discloses a single-end-capped propionyloxy organic silicon resin and a preparation method thereof, a conductive adhesive containing the organic silicon resin and a preparation method thereof, wherein the structural formula of the single-end-capped propionyloxy organic silicon resin is shown as formula (I), and the conductive adhesive comprises 10-30 parts of the single-end-capped propionyloxy organic silicon resin and also comprises the following raw materials in parts by weight: 0.5-5 parts of thermal initiator, 1-5 parts of thermoplastic powder filler, 60-80 parts of modified silver powder, 1-10 parts of solvent and 0.1-1 part of stabilizer; wherein the weight portion of the singly-terminated propionyloxy organic silicon resin is 10-30 portions. The conductive adhesive has excellent elongation of cured products, bonding strength, conductivity, flexibility and drop resistance, and can be widely applied to the electronic industry.
Chinese patent 201310148749.6 provides a preparation method of a high thermal and electrical conductivity adhesive containing graphene, which comprises the following steps: (1): surface functionalization of graphene: adding graphene into an acetone solution of an organic matter containing a conjugated ring, and performing intense ultrasonic oscillation for 6-48 h at 40-100 ℃ to form non-covalent modified graphene; (2): mixing epoxy resin and an epoxy diluent at room temperature for 3-30 minutes to obtain a mixture of the epoxy resin and the epoxy diluent, and sequentially adding metal powder and a coupling agent into the mixture; (3): adding the non-covalently modified graphene prepared in the step (1) into the mixture in the step (2); (4): and (4) adding a curing agent into the mixture obtained in the step (3) to prepare the uniform conductive adhesive. The invention has the advantages that: the graphene is subjected to surface functionalization through a non-covalent bond, so that the graphene is favorably dispersed in an epoxy system and enhanced in interface combination, and then is mixed with metal powder for use, so that the high-thermal-conductivity conductive adhesive is obtained, and the graphene has a prospect in application of high-power devices.
The liquid silicone rubber is non-conductive, a certain amount of conductive filler needs to be added to obtain the organic silicon conductive adhesive, and when the addition amount of the conductive filler reaches a percolation threshold value, the liquid silicone rubber can show the electrical property. At present, the conductive fillers of the organic silicon conductive adhesive are various, including metal conductive fillers, carbon conductive fillers, metal composite conductive fillers, and the like. Compared with metal conductive fillers, carbon conductive fillers have poor conductivity and are difficult to disperse in the preparation process. The metal conductive filler has higher price but outstanding conductivity, while the carbon conductive filler has poorer conductivity but can provide certain strength for the material to improve the overall performance. Therefore, hybrid materials formed between nanostructures such as metal nanoparticles and carbon-based materials have attracted attention. The connection between the metal nanoparticles and the graphene carrier and the effective control on the distribution and the structure of the metal nanoparticles are the difficulty and the key for preparing the metal nanoparticle/graphene hybrid structure. Generally, graphene needs to be functionalized, and the generation of metal nanoparticles on the surface of graphene is controlled by a functionalizing agent. Although the defect sites of graphene oxide or reduced graphene are active sites, they can be utilized to promote the growth of metal nanoparticles on the surface thereof. However, the defect positions are easy to cause the growth of the metal nanoparticles on the surface of the graphene to present uneven distribution. When pure graphene is used as a carrier, the graphene has poor stability in a solvent due to no organic groups on the surface, so that how to realize good preparation stability and effectively control the distribution and the structure of nanoparticles on the surface of the graphene is still a great problem.
Disclosure of Invention
In view of the above-mentioned defects in the prior art, the technical problem to be solved by the present invention is to provide a functionalized graphene with good dispersibility in a solvent, and hybridize the functionalized graphene with metal particles to obtain a novel conductive filler, and apply the novel conductive filler to the preparation of a conductive adhesive.
The graphene surface has no organic group and is poor in stability in a solvent, so that the graphene surface can be hybridized with metal nanoparticles well only by functionalization, and in the invention, the inventor prepares a non-covalent copolymer, namely perylene diimide nitrogen oxide, as a surfactant to perform functionalization modification on the graphene, the surfactant can have strong interaction with the graphene due to electron-deficient carbon atoms and large pi-pi interaction area in a framework structure, good support is improved for enhancing the dispersibility of the graphene in the solvent by a zwitter-ionic side chain group in a molecular structure, and the perylene diimide nitrogen oxide can realize high-efficiency functionalization and excellent dispersibility of the graphene by water and repulsion effects. Due to the functional modification of the graphene, the surface of the graphene can be well combined with the metal nanoparticles, and the combination property of the hybrid is further improved. The connection between the graphene and the metal silver particles is enhanced through non-covalent bonding, and the contact resistance is reduced through a conducting structure formed by bridging the surface nano silver particles and the graphene, so that the conductivity can be enhanced. The mechanical property of the conductive adhesive can be improved by adding the graphene, the shearing strength of the conductive adhesive is improved, and the performance tends to be more stable when the temperature changes.
The technical scheme of the invention is as follows:
an antistatic conductive adhesive for a circuit board mainly comprises the following components in parts by weight: 50-85 parts of nano silver/functionalized graphene hybrid conductive filler, 10-40 parts of siloxane resin, 0.1-0.8 part of catalyst, 0.1-0.8 part of reinforcing agent, 0.1-0.5 part of inhibitor and 0.1-0.5 part of cross-linking agent.
The preparation method of the nano-silver/functionalized graphene hybrid conductive filler comprises the following steps:
s1, weighing 30-50 parts by weight of 3,4,9, 10-tetracarboxylic anhydride and 7-10 parts by weight of N, N-dimethylethylenediamine, adding into 35-75 parts by weight of N-butanol, heating to 80-100 ℃, stirring for 4-6 h, and evaporating the solvent to dryness after the reaction is finished to obtain N, N' -bis [3- (dimethylamino) propyl ] perylene-3, 4,9, 10-tetracarboxylic diimide;
s2, weighing 10-20 parts by weight of N, N' -bis [3- (dimethylamino) propyl ] perylene-3, 4,9 and 10-tetracarboxylic acid diimide obtained in the step S1, adding the weighed 10-20 parts into 80-120 parts by weight of absolute ethanol, dropping 4.5-6.5 parts by weight of 30wt% hydrogen peroxide solution under the protection of argon, stirring for 1-4 hours at room temperature, heating to 60-90 ℃, refluxing for 3-9 hours, cooling to room temperature, removing the solvent under reduced pressure, and sequentially washing residues with acetone and N-hexane for three times to obtain perylene diimide nitrogen oxide;
s3, weighing 10-20 parts by weight of graphite and 2-8 parts by weight of potassium, mixing, and heating to 100-120 ℃ in a nitrogen atmosphere to react for 1-3 h to obtain potassium intercalated graphite;
s4, weighing 2-6 parts by weight of the potassium intercalated graphite in the step S3, adding the potassium intercalated graphite into 8-10 parts by weight of pyridine, carrying out cracking reaction at the temperature of-35 to-30 ℃ for 20-28 h, then adding 0.1-0.125 part by weight of perylene diimide-based nitrogen oxide in the step S2, stirring for 20-24 h, then carrying out ultrasonic dispersion for 1-2 h, and filtering to obtain non-covalent functionalized graphene;
and S5, adding the non-covalent functionalized graphene obtained in the step S4 into 70-100 parts by weight of methanol, adding 60-100 parts by weight of silver acetate, stirring until the silver acetate is dissolved, and removing the solvent through low-temperature reduced pressure concentration to obtain the nano-silver/functionalized graphene hybrid conductive filler.
Preferably, the silicone resin is formed by mixing vinyl silicone oil and vinyl MQ silicone resin in a mass ratio of 2-3.
Preferably, the catalyst is a platinum group catalyst.
Preferably, the reinforcing agent is fumed silica.
Preferably, the inhibitor is one of an acetylene compound, a double bond-containing dibasic acid ester or a nitrogen-containing compound.
Preferably, the cross-linking agent is hydrogen-containing silicone oil.
A preparation method of antistatic conductive adhesive for a circuit board comprises the following steps:
weighing siloxane resin and nano-silver/functionalized graphene hybrid conductive filler according to the formula ratio, uniformly stirring and dispersing, stirring for 0.5-1 h, grinding for 1-3 times, continuously adding a catalyst, a reinforcing agent, an inhibitor and a crosslinking agent, uniformly stirring, and vacuumizing and degassing to obtain the antistatic conductive adhesive.
Compared with the prior art, the invention has the following beneficial effects:
(1) In the invention, the inventor prepares a non-covalent copolymer, namely perylene diimide-based nitrogen oxide, as a surfactant to perform functional modification on graphene, wherein the surfactant can strongly interact with graphene due to the fact that a skeleton structure has electron-deficient carbon atoms and a large pi-pi interaction area, and a zwitterionic side chain group in a molecular structure of the surfactant improves good support for enhancing the dispersibility of the graphene in a solvent;
(2) The connection between the graphene and the metal silver particles is enhanced through non-covalent bonding, and the contact resistance is reduced through a conducting structure formed by bridging the surface nano silver particles and the graphene, so that the conductivity can be enhanced;
(3) The mechanical property of the conductive adhesive can be improved by adding the graphene, the shear strength of the conductive adhesive is improved, and the performance of the conductive adhesive tends to be more stable when the conductive adhesive faces temperature change.
Detailed Description
Hereinafter, the technical solution of the present invention will be described in detail by specific examples, but these examples should be explicitly proposed for illustration, but should not be construed as limiting the scope of the present invention.
The parameters of part of the raw materials in the embodiment of the invention are as follows:
200 mPas of vinyl silicone oil, 0.7 percent of vinyl mass fraction, ningbo Runzao high-new material science and technology company.
Vinyl MQ silicon resin, 6300 mPa.s, the vinyl mass fraction is 0.96 percent, and Ningbo Runzhugao new material.
Nano silver powder, goods number: PT-Ag-300nm, shanghai Pantian powder material.
Kaster catalyst, type: ACS-PT-50, 6000ppm, and commercial and trade of Guixiang in Jinan.
Fumed silica, type: a-200 with content not less than 99.8%, and scientific and technical for new material of Aloca and Bohai alkali chloride in Hebei.
Polymethylhydrosiloxane, 15-40mPa.s, and alatin.
Graphene, cat no: 100393 with a sheet diameter of 0.5-5 μm, a thickness of 0.8-1.2 nm and Nanjing Xiancheng nanometer.
Comparative example 1
A preparation method of antistatic conductive adhesive for circuit boards comprises the following steps:
weighing 2.5kg of vinyl silicone oil, 1kg of vinyl MQ silicon resin and 5.1kg of nano silver powder, uniformly stirring and dispersing, stirring for 1h, grinding for 2 times, continuously adding 10g of Cassier catalyst, 50g of fumed silica, 10g of ethynyl cyclohexanol and 10g of polymethylhydrosiloxane, uniformly stirring, and vacuumizing and degassing to obtain the antistatic conductive adhesive.
Example 1
A preparation method of antistatic conductive adhesive for a circuit board comprises the following steps:
weighing 2.5kg of vinyl silicone oil, 1kg of vinyl MQ silicon resin and 5.1kg of nano-silver/functionalized graphene hybrid conductive filler, uniformly stirring and dispersing, stirring for 1h, grinding for 2 times, continuously adding 10g of a Kaster catalyst, 50g of fumed silica, 10g of ethynyl cyclohexanol and 10g of polymethylhydrosiloxane, uniformly stirring, and vacuumizing and degassing to obtain the anti-static conductive adhesive.
The preparation method of the nano-silver/functionalized graphene hybrid conductive filler comprises the following steps:
s1, weighing 3,4,9, 10-tetracarboxylic anhydride 3.7kg and N, N-dimethylethylenediamine 0.8kg, adding into 4L of N-butanol, heating to 90 ℃, stirring for 5h, and after the reaction is finished, evaporating the solvent to dryness to obtain N, N' -bis [3- (dimethylamino) propyl ] perylene-3, 4,9, 10-tetracarboxylic diimide;
s2, weighing 2kg of N, N' -bis [3- (dimethylamino) propyl ] perylene-3, 4,9, 10-tetracarboxylic diimide obtained in the step S1, adding into 10L of anhydrous ethanol, dropwise adding 0.5kg of 30wt% aqueous hydrogen peroxide under the protection of argon gas, stirring for 3h at room temperature, heating to 80 ℃, refluxing for 6h, cooling to room temperature, decompressing to remove the solvent, and sequentially washing residues with acetone and N-hexane for three times to obtain perylene diimide-based nitric oxide;
s3, weighing 1kg of graphite and 0.4kg of potassium, mixing, heating to 110 ℃ in a nitrogen atmosphere, and reacting for 3 hours to obtain potassium intercalated graphite;
s4, weighing 0.6kg of potassium intercalated graphite in the step S3, adding the potassium intercalated graphite into 1L of pyridine, carrying out cracking reaction at the temperature of minus 30 ℃ for 24 hours, then adding 0.1kg of perylene diimide-based nitrogen oxide in the step S2, stirring for 24 hours, carrying out ultrasonic dispersion for 2 hours, and filtering to obtain non-covalent functionalized graphene;
and S5, adding the non-covalent functionalized graphene obtained in the step S4 into 10L of methanol, adding 4.5kg of silver acetate, stirring until the silver acetate is dissolved, and concentrating at 40 ℃ and-0.9 MPa to remove the solvent to obtain the nano-silver/functionalized graphene hybrid conductive filler.
Example 2
A preparation method of antistatic conductive adhesive for circuit boards comprises the following steps:
weighing 2.5kg of vinyl silicone oil, 1kg of vinyl MQ silicon resin and 5.1kg of graphene, uniformly stirring and dispersing, stirring for 1h, grinding for 2 times, continuously adding 10g of Cassier catalyst, 50g of fumed silica, 10g of ethynyl cyclohexanol and 10g of polymethylhydrosiloxane, uniformly stirring, and vacuumizing and degassing to obtain the antistatic conductive adhesive.
Example 3
A preparation method of antistatic conductive adhesive for a circuit board comprises the following steps:
weighing 2.5kg of vinyl silicone oil, 1kg of vinyl MQ silicone resin and 5.1kg of nano silver/graphene compound, uniformly stirring and dispersing, stirring for 1 hour, grinding for 2 times, continuously adding 10g of a Kaster catalyst, 50g of fumed silica, 10g of ethynyl cyclohexanol and 10g of polymethylhydrosiloxane, uniformly stirring, and vacuumizing and degassing to obtain the anti-static conductive adhesive.
The preparation method of the nano silver/graphene composite comprises the following steps:
dispersing 4.5kg of silver acetate into 10L of acetonitrile, then adding 0.6kg of graphene, stirring at room temperature until the silver acetate is dissolved, centrifuging the mixed solution, taking the lower layer precipitate, and drying to obtain the nano silver/graphene compound.
Test example 1
The volume resistivity of the conductive adhesive prepared in the control example and the example was tested, and the conductive adhesive prepared was cured at 110 ℃ for 2 hours, and the test results are shown in table 1. The test was performed using a dc resistance meter, and each sample was tested 3 times and averaged. Volume resistivity calculation formula ρ = R (W × t)/L, where ρ — volume resistivity (Ω · cm); r-test resistance value (Ω); w-sample width (cm); t-sample thickness (cm); l-the spacing (cm) of two copper wires.
Table 1 table of conductive colloid cumulative resistivity test results
| Experimental protocol | Volume resistivity/Ω · cm |
| Comparative example 1 | 1.2×10 ﹣3 |
| Example 1 | 0.8×10 ﹣3 |
| Example 2 | 2.5×10 ﹣3 |
| Example 3 | 2.1×10 ﹣3 |
The volume resistivity can well reflect the conductivity of the material, and it can be seen from the test results that the graphene used in example 2 has a higher volume resistivity due to poor conductivity, while the nano-silver used in comparative example 1 has a lower volume resistivity due to good conductivity, while in example 3, the nano-silver and the graphene are compounded, but the graphene cannot be well combined when being compounded due to poor dispersibility of the graphene in a solvent, which may cause the conductive adhesive to form an agglomeration inside the curing process, thereby affecting the electron transmission, and thus having a higher volume resistivity. In example 1, the covalent functionalization of graphene is achieved by van der waals attraction between the aromatic backbone and graphene, and a certain interaction exists between the prepared perylene diimide-based nitrogen oxide and graphene, so that the graphene is stably dispersed and the structure of the graphene is not affected. The covalent bonding enhances the connection between the graphene and the metal silver particles, and the contact resistance is reduced through the conducting structure of the surface nano silver particles and the graphene bridging, so that the conductivity can be enhanced.
Test example 2
The conductive adhesive prepared in the comparative example and the example was subjected to a shear strength test, and the conductive adhesive prepared was cured at 110 ℃ for 2 hours to test, and the specific test results are shown in table 2. The test of the tensile shear strength of the conductive adhesive refers to the test of determination of tensile shear strength of adhesives (rigid material to rigid material) (Al/Al lap joint) in GB/T7124-2008, which is specifically as follows. The overlap length of the test specimens is 12.5. + -. 0.5mm. And (3) putting the prepared sample piece into an oven, curing according to the set temperature and time, after the curing is finished, cooling the temperature of the sample piece to room temperature, testing the shear strength by using a testing machine, setting the testing speed to be 5mm/min, and finally taking the average value as the testing result of the shear strength. The tensile shear strength is shown in the formula: τ = P/B × L in the formula: τ -tensile shear strength (MPa); p-maximum tensile force (N); b-width of faying surface (mm); l is the length (mm) of the overlapping surface.
Table 2 table of test results of shear strength of conductive adhesive
| Experimental protocol | Shear strength/MPa |
| Comparative example 1 | 3.1 |
| Example 1 | 6.2 |
| Example 2 | 4.0 |
| Example 3 | 4.7 |
It can be seen from the shear strength test that the addition of graphene can actually improve the mechanical properties of the conductive adhesive to a certain extent, which is caused by the rigid structure of graphene itself, however, when the graphene is compounded with nano silver, the mechanical properties are influenced to a certain extent, which may be that the compatibility of graphene in combination cannot be well ensured due to poor dispersibility of graphene in a solvent when the graphene is compounded with metal particles, which also causes agglomeration in the colloid when the graphene is added into the conductive adhesive, which not only affects the conductivity, but also affects the toughness of the material, thereby causing the shear strength to be influenced to a certain extent, and therefore, the improvement of the mechanical properties in example 3 is limited. In the embodiment 1, the dispersibility of the graphene in the solution is improved by performing functional modification on the graphene, so that the agglomeration is reduced, and the active groups on the surface of the graphene can help the graphene to be combined with silver particles, so that the combination is favorable for improving the conductivity and can help the conductive adhesive to improve the mechanical property.
Test example 3
And (3) performing a cold and thermal shock test on the conductive adhesive prepared in the comparative example and the example, curing the prepared conductive adhesive at 110 ℃ for 2h, keeping the temperature at minus 40 ℃ for 30min, increasing the temperature to 100 ℃ for 2min, keeping the temperature for 30min, decreasing the temperature to minus 40 ℃ for 2min, keeping the temperature for 30min, performing 1 cycle above, performing 100 cycles every week, and testing the shear strength performance of the sample performance, wherein the test method for the shear strength refers to test example 2, and the specific test result is shown in table 3.
TABLE 3 shear strength Properties of conductive adhesive after Cold and Hot impact testing
| Experimental protocol | Shear strength/MPa |
| Comparative example 1 | 2.4 |
| Example 1 | 5.7 |
| Example 2 | 3.4 |
| Example 3 | 4.1 |
Since the use environment of the conductive adhesive is sensitive to temperature changes, the stability of the performance of the conductive adhesive under cold and hot shock is very important. It can be seen from the cold and thermal shock test that the conductive adhesive prepared in example 1 can still maintain good mechanical properties after undergoing 100 cold and thermal cycles, which may be because the non-covalent bonding between the graphene and the perylene diimide-based nitrogen oxide enhances the connection between the graphene and the metal silver particles, so that the performance of the conductive adhesive is not greatly affected when facing the temperature change.
Claims (8)
1. The antistatic conductive adhesive for the circuit board is characterized by comprising the following components in parts by weight: 50-85 parts of nano silver/functionalized graphene hybrid conductive filler, 10-40 parts of siloxane resin, 0.1-0.8 part of catalyst, 0.1-0.8 part of reinforcing agent, 0.1-0.5 part of inhibitor and 0.1-0.5 part of cross-linking agent;
the nano silver/functionalized graphene hybridized conductive filler is prepared by taking perylene diimide-based nitrogen oxide obtained through preparation as a surfactant to carry out non-covalent functionalization on graphene nanosheets and then hybridizing the graphene nanosheets with silver acetate.
2. The antistatic conductive adhesive as claimed in claim 1, wherein the preparation method of the nano silver/functionalized graphene hybrid conductive filler comprises the following steps:
s1, adding 3,4,9, 10-tetracarboxylic anhydride and N, N-dimethylethylenediamine into N-butanol, heating and stirring, and evaporating a solvent to dryness after the reaction is finished to obtain N, N' -bis [3- (dimethylamino) propyl ] perylene-3, 4,9, 10-tetracarboxylic diimide;
s2, weighing the N, N' -bis [3- (dimethylamino) propyl ] perylene-3, 4,9, 10-tetracarboxylic acid diimide obtained in the step S1, adding into absolute ethyl alcohol, dropwise adding a 30wt% hydrogen peroxide solution under the protection of argon, stirring at room temperature, heating for refluxing, cooling to room temperature, reducing pressure to remove a solvent, and sequentially washing residues with acetone and N-hexane for three times to obtain perylene diimide-based nitrogen oxides;
s3, mixing graphite and potassium, and heating to react in a nitrogen atmosphere to obtain potassium intercalated graphite;
s4, weighing the potassium intercalated graphite obtained in the step S3, adding the potassium intercalated graphite into pyridine, performing cracking reaction at low temperature, adding the perylene diimide-based nitrogen oxide obtained in the step S2, stirring, performing ultrasonic dispersion, and filtering to obtain non-covalent functionalized graphene;
and S5, dissolving the non-covalent functionalized graphene obtained in the step S4 in methanol, adding silver acetate, stirring until the silver acetate is dissolved, and removing the solvent through low-temperature reduced pressure concentration to obtain the nano-silver/functionalized graphene hybrid conductive filler.
3. The antistatic conductive adhesive as claimed in claim 1, wherein: the silicone resin is formed by mixing vinyl silicone oil and vinyl MQ silicone resin according to the mass ratio of 2-3.
4. The antistatic conductive adhesive as claimed in claim 1, wherein: the catalyst is a platinum group catalyst.
5. The antistatic conductive adhesive as claimed in claim 1, wherein: the reinforcing agent is fumed silica.
6. The antistatic conductive adhesive as claimed in claim 1, wherein: the inhibitor is one of an alkyne compound, a dibasic acid ester containing double bonds or a nitrogen-containing compound.
7. The antistatic conductive adhesive as claimed in claim 1, wherein: the cross-linking agent is hydrogen-containing silicone oil.
8. The preparation method of the antistatic conductive adhesive as claimed in any one of claims 1 to 7, characterized by comprising the following steps:
weighing siloxane resin and nano-silver/functionalized graphene hybrid conductive filler according to the formula ratio, uniformly stirring and dispersing, stirring for 0.5-1 h, grinding for 1-3 times, continuously adding a catalyst, a reinforcing agent, an inhibitor and a crosslinking agent, uniformly stirring, and vacuumizing and degassing to obtain the antistatic conductive adhesive.
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| CN102153976A (en) * | 2011-03-01 | 2011-08-17 | 华南理工大学 | Preparation method of graphene/nano silver epoxy conductive adhesive |
| CN103194165A (en) * | 2013-04-26 | 2013-07-10 | 中国电子科技集团公司第三十八研究所 | Method for preparing high-heat-conductivity conductive adhesive containing graphene |
| WO2020012236A1 (en) * | 2018-07-13 | 2020-01-16 | Bosch Car Multimedia Portugal S.a. | Carbon/metal hybrid fillers, electrically conductive adhesive, methods and uses thereof |
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Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102153976A (en) * | 2011-03-01 | 2011-08-17 | 华南理工大学 | Preparation method of graphene/nano silver epoxy conductive adhesive |
| CN103194165A (en) * | 2013-04-26 | 2013-07-10 | 中国电子科技集团公司第三十八研究所 | Method for preparing high-heat-conductivity conductive adhesive containing graphene |
| WO2020012236A1 (en) * | 2018-07-13 | 2020-01-16 | Bosch Car Multimedia Portugal S.a. | Carbon/metal hybrid fillers, electrically conductive adhesive, methods and uses thereof |
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