Oxygen-containing graphene dispersion liquid as well as preparation method and application thereof

Abstract

The invention discloses oxygen-containing graphene dispersion liquid as well as a preparation method and application thereof, and belongs to the technical field of printed circuit boards. The preparation method of the oxygen-containing graphene dispersion liquid provided by the invention comprises the following steps: S1, carrying out ultrasonic treatment on a mixed aqueous dispersion liquid formed by expanded graphite oxide and a modifier; the modifier is a saccharide modifier; the saccharide modifier comprises at least one of glucose and fructose; s2, freeze-drying the mixture obtained in the step S1; s3, in an oxygen-isolated environment, performing gamma irradiation on the mixture obtained in the step S2; and S4, dispersing the irradiation product obtained in the step S3 in water. In the prepared oxygen-containing graphene dispersion liquid, the number of oxygen-containing graphene layers is small, and dispersion is uniform and stable. The invention also provides an application of the oxygen-containing graphene dispersion liquid in preparation of a PCB (Printed Circuit Board).

Description

Technical Field

[0001] This invention relates to the field of printed circuit board technology, and in particular to an oxygen-containing graphene dispersion, its preparation method, and its application. Background Technology

[0002] In the fabrication of printed circuit boards (PCBs), copper plating is required on an insulating substrate. Traditional techniques typically involve sequentially depositing a copper oxide layer and a chemical copper plating layer on the substrate to lay the foundation for the electroplated copper layer. While this traditional process is mature and stable, it is complex, costly, and causes significant environmental pollution. To overcome these drawbacks, researchers have attempted to replace the two steps of depositing the copper oxide and chemical copper plating layers with a single step of depositing a conductive layer. The conductive layer materials chosen are mostly carbon-based materials such as graphite and carbon black; however, conductive layers prepared from graphite and carbon black suffer from unstable quality, relatively high resistance, and difficulty in application to rigid boards and other applications.

[0003] In recent years, graphene has attracted much attention due to its unique two-dimensional structure and excellent conductivity, film-forming properties, and chemical stability. It has significant advantages over traditional carbon black and graphite powders in the preparation of conductive layers for PCBs. However, conductive layers prepared from graphene still suffer from drawbacks such as poor uniformity, poor density, and poor adhesion; consequently, they may still exhibit high resistivity. Summary of the Invention

[0004] This invention aims to at least solve one of the technical problems existing in the prior art. To this end, this invention proposes a method for preparing an oxygen-containing graphene dispersion, which can effectively reduce the number of graphene layers to improve the uniformity and stability of the dispersion, thereby improving the uniformity and density of the conductive layer prepared from graphene. Simultaneously, this preparation method can also perform graft modification on the graphene, improving the bonding strength between graphene and the PCB substrate, and also improving the thickness uniformity and density of graphene on the substrate.

[0005] The present invention also provides an oxygen-containing graphene dispersion prepared by the above preparation method.

[0006] This invention also provides applications of the above-mentioned oxygen-containing graphene dispersion, specifically its application in the preparation of PCB boards.

[0007] According to an embodiment of the first aspect of the present invention, a method for preparing an oxygen-containing graphene dispersion is provided, the preparation method comprising the following steps: S1. Ultrasonication of the mixed aqueous dispersion formed by expanded graphite oxide and modifier; The modifier is a carbohydrate modifier; the carbohydrate modifier includes at least one of glucose and fructose; S2. The mixture obtained from freeze-drying step S1; S3. Irradiate the mixture obtained in step S2 with gamma in an oxygen-free environment; S4. Disperse the irradiated product obtained in step S3 in water.

[0008] The preparation method according to embodiments of the present invention has at least the following beneficial effects: In step S1, expanded graphite oxide is used. Compared with conventional graphite, it has a higher interlayer spacing, which makes it easier for modifiers and other reagents to migrate to the interlayer of expanded graphite oxide, thus providing a basis for the subsequent interlayer exfoliation of expanded graphite oxide assisted by modifiers.

[0009] In step S1, on the one hand, the shearing effect of ultrasound can be used to initially peel off the expanded graphite oxide; on the other hand, the ultrasound process is also a process of increasing the mass transfer rate, which can significantly promote the migration of the modifier into the interlayer of expanded graphite oxide.

[0010] In step S2, during the freeze-drying process, the water in the mixed aqueous dispersion expands in volume, further exfoliating the expanded graphene oxide. Compared to drying, freeze-drying is more effective in preserving the structure of the expanded graphene oxide, preventing the reduction of interlayer spacing that occurred in the previous step.

[0011] In step S3, during gamma irradiation, specific types of modifiers react to generate a large amount of gases such as hydrogen, reducing free radicals, and oxygen-containing free radicals. Among these, the gases generated between the expanded graphene oxide layers can further increase the interlayer spacing of the expanded graphene oxide, thus having the effect of interlayer expansion and exfoliation. The reducing free radicals can reduce the oxidizing groups on the expanded graphene oxide to obtain reduced graphene oxide, thereby improving the conductivity of the final oxygen-containing graphene dispersion. The oxygen-containing free radicals may modify the expanded graphene oxide, laying the foundation for improving the bonding force between the oxygen-containing graphene and the PCB substrate.

[0012] In step S4, through the effects of the previous three steps, the interlayer distance of expanded graphite is large and the interlayer force is significantly reduced. Therefore, during the dispersion process in water, the expanded graphite undergoes natural interlayer exfoliation to form reduced graphene oxide with a small number of layers and uniform thickness. After dispersion in aqueous solution, it forms an oxygen-containing graphene dispersion with good conductivity, good dispersibility and storage stability.

[0013] According to some embodiments of the present invention, in step S1, the method for synthesizing expanded graphite oxide includes the following steps: A1. Hummers process for treating flake graphite; A2. The product obtained from the high-temperature puffing step A1.

[0014] Therefore, the interlayer spacing of the resulting expanded graphite oxide is ≥700nm, which is sufficient to accommodate the entry of modifiers such as glucose or fructose.

[0015] Furthermore, the expanded graphene oxide prepared by this method is rich in oxygen-containing groups, which improves its dispersibility in water, thereby improving the uniformity of the distribution of the modifier between the expanded graphene oxide layers, and ultimately improving the uniformity of the number of oxygen-containing graphene layers in the obtained oxygen-containing graphene dispersion.

[0016] According to some embodiments of the present invention, in step A1, the flake graphite can pass through a 300-mesh sieve.

[0017] According to some embodiments of the present invention, in step A2, the high-temperature puffing is carried out under conditions in the absence of water and oxygen.

[0018] According to some embodiments of the present invention, in step A2, the temperature of the high-temperature puffing is 950~1050°C. For example, it can be about 1000°C.

[0019] According to some embodiments of the present invention, in step A2, the duration of the high-temperature puffing is 0.5 to 10 minutes. For example, it can be about 1 minute or about 2 minutes. This duration refers to the duration at the highest constant temperature.

[0020] According to some embodiments of the present invention, in step S1, the mass percentage of the expanded graphite oxide in the mixed aqueous dispersion is 1-5%. For example, it may be about 2%, 3%, or about 4%.

[0021] According to some embodiments of the present invention, in step S1, the sugar modifier is selected from glucose. The G value for generating gases such as hydrogen under Gamma irradiation is approximately twice that of fructose; therefore, selecting glucose is more beneficial for the interlayer exfoliation of the expanded graphene oxide.

[0022] According to some embodiments of the present invention, in step S1, the mass ratio of the expanded graphite oxide to the sugar modifier is 1:1 to 5. Specifically, it can be about 1:2, 1:3, or about 1:4. Thus, sufficient sugar modifier fills the interlayer of the expanded graphite oxide in the mixed aqueous dispersion, laying the foundation for gamma irradiation-induced gas exfoliation in step S3.

[0023] According to some embodiments of the present invention, in step S1, the modifier further includes an amino modifier; and the amino modifier includes at least one of p-phenylenediamine and o-phenylenediamine.

[0024] According to some embodiments of the present invention, in step S1, the mass ratio of the expanded graphene oxide to the amino modifier is 1:5 to 15. Specifically, it can be about 1:6, 1:7, 1:8, 1:10, or about 1:12. Therefore, sufficient amino modifier is available to modify the expanded graphene oxide, thereby improving the bonding strength between the oxygen-containing graphene in the resulting oxygen-containing graphene dispersion and the PCB substrate, and enhancing the adhesion stability of the black-pore film.

[0025] According to some embodiments of the present invention, in step S1, the ultrasound includes cyclic positive and negative pressure environments. The positive pressure environment has a pressure of 3-8 MPa, specifically approximately 4 MPa, 5 MPa, 6 MPa, or approximately 7 MPa. The negative pressure environment has a pressure of -0.1 to -0.05 MPa, specifically approximately -0.09 MPa, -0.08 MPa, -0.07 MPa, or approximately -0.06 MPa.

[0026] The cyclic positive and negative pressure environments can significantly promote the migration of the modifier into the interlayer of expanded graphene oxide and, to some extent, improve the interlayer spacing of expanded graphene oxide.

[0027] The duration of a single positive or negative pressure application is 3 to 8 minutes; for example, it can be approximately 5 minutes.

[0028] According to some embodiments of the present invention, in step S1, the duration of the ultrasound is 20-80 minutes. For example, it can be about 30 minutes, 40 minutes, 50 minutes, 60 minutes, or about 70 minutes. This enables the initial exfoliation of the expanded graphite oxide, and the product obtained in this step has 10-20 layers of expanded graphite oxide.

[0029] According to some embodiments of the present invention, in step S1, the conditions for ultrasound are performed in a sequential cycle: negative pressure for 3-8 minutes, normal pressure for 3-8 minutes, and positive pressure for 3-8 minutes.

[0030] According to some embodiments of the present invention, in step S3, the dose rate of the gamma irradiation is 30~100 Gy / min. For example, it can be about 40 Gy / min, 50 Gy / min, 60 Gy / min, 70 Gy / min, 80 Gy / min or about 90 Gy / min.

[0031] According to some embodiments of the present invention, in step S3, the duration of gamma irradiation is 1 to 10 hours. For example, it can be approximately 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, or approximately 9 hours.

[0032] It should be noted that during gamma irradiation, the environment in which the expanded graphene oxide exists (inert gas, water, or organic solvent) and the irradiation dose rate will affect the morphology of the irradiated product to a certain extent. Under the conditions defined in this invention, ultrathin, well-dispersed oxygen-containing graphene can be obtained instead of forming hydrogels or other products that are difficult to disperse.

[0033] Within the range of irradiation duration and dose rate mentioned above, almost all the modifiers have reacted completely, and at this dose rate, the generation rate of gases such as hydrogen is also relatively fast, which can meet the requirements of gas expansion stripping.

[0034] According to some embodiments of the present invention, in step S4, the dispersion method includes either ultrasonic dispersion or dispersion using a high-speed blender. In actual production, a high-speed blender is preferred for dispersion to obtain greater shear force, improve the exfoliation effect of oxygen-containing graphene, and shorten the time required for exfoliation.

[0035] According to some embodiments of the present invention, in step S4, the dispersion time is 10 to 30 minutes. For example, it can be about 15 minutes, 20 minutes, or about 25 minutes.

[0036] According to some embodiments of the present invention, in step S4, the dispersion concentration of the irradiated product in water (based on the obtained dispersion, by mass percentage) is 3-10%. For example, it can be about 4%, 5%, 6%, 7%, 8%, or about 9%. Thus, the viscosity of the obtained oxygen-containing graphene dispersion meets the requirements of subsequent processing such as impregnation; and the concentration of the obtained oxygen-containing graphene dispersion can also ensure that a uniform and highly conductive black film is obtained in the subsequent black pore formation.

[0037] According to some embodiments of the present invention, step S4 further includes sieving after dispersion. The sieving mesh size is 325 mesh or 400 mesh. This removes lumpy material caused by agglomeration and also helps to defoam to some extent.

[0038] According to an embodiment of a second aspect of the present invention, an oxygen-containing graphene dispersion is provided, which is prepared by the preparation method provided in the first aspect of the present invention.

[0039] Since the oxygen-containing graphene dispersion adopts all the technical solutions of the preparation method of the above embodiments, it has at least all the beneficial effects brought about by the technical solutions of the above embodiments.

[0040] Furthermore, the oxygen-containing graphene dispersion provided by this invention does not require the addition of an additional dispersant. Stable suspension can be achieved solely through the repulsive force of the modifying groups on the graphene itself. Therefore, after black hole treatment of PCB boards, the oxygen-containing graphene in the resulting film has higher purity and better conductivity. Moreover, the oxygen-containing graphene dispersion contains fewer and more uniform layers of oxygen-containing graphene, resulting in a more uniform film prepared by black hole treatment.

[0041] According to an embodiment of a third aspect of the present invention, a PCB board is provided, wherein the raw materials for preparing the PCB board include the oxygen-containing graphene dispersion provided in the second aspect of the present invention.

[0042] Since the raw materials used in the preparation of the PCB board employ all the technical solutions of the oxygen-containing graphene dispersion described in the above embodiments, it possesses at least all the beneficial effects brought about by the technical solutions of the above embodiments. Specifically, the conductivity, density, and adhesion of the black film inside the holes of the PCB board after blackening are superior, making it more conducive to subsequent copper plating operations.

[0043] According to some embodiments of the present invention, the method for manufacturing the PCB board includes the following steps: D1. Soak the PCB board after drilling in the hole-clearing solution and then clean it; D2. Immerse the PCB board semi-finished product obtained in step D1 in the oxygen-containing graphene dispersion.

[0044] According to some embodiments of the present invention, in step D1, the soaking temperature is 30~40°C; specifically, it can be about 35°C.

[0045] According to some embodiments of the present invention, in step D1, the soaking time is 40-50 seconds. For example, it can be approximately 45 seconds.

[0046] PCB boards are typically made of polymer materials. After drilling with a metal drill, the hole walls will carry a negative charge. Therefore, it is necessary to perform a hole-clearing process to give the hole walls a positive charge, which will facilitate the subsequent adsorption and anchoring of oxygen-containing graphene on the hole walls.

[0047] According to some embodiments of the present invention, in step D2, the immersion temperature is 30~40°C. For example, it can be about 32°C, 35°C, or about 38°C.

[0048] According to some embodiments of the present invention, in step D2, the soaking time is 40-60 seconds. For example, it can be about 45 seconds, 50 seconds, or about 55 seconds.

[0049] According to some embodiments of the present invention, step D2 further includes removing the floating liquid from the surface of the PCB board after soaking, and the specific removal method may be sponge absorption and removal.

[0050] Unless otherwise specified, the term "about" in this invention actually means that the error is allowed to be within ±2%, for example, about 100 is actually 100 ± 2% × 100.

[0051] Unless otherwise specified, "between" in this invention includes the number itself, for example, "between 2 and 3" includes the endpoint values ​​2 and 3.

[0052] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. Detailed Implementation

[0053] The following will describe the concept and technical effects of the present invention clearly and completely with reference to embodiments, so as to fully understand the purpose, features and effects of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are all within the scope of protection of the present invention.

[0054] In the description of this invention, the terms "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0055] The specific steps of the Hummers method used in the detailed implementation are as follows: Pre-cool the mixed acid solution in an ice bath (0-5℃), add concentrated sulfuric acid (about 42 parts by weight of 98% concentration) to the reaction vessel; add 1 part by weight of flake graphite and 0.5 parts by weight of sodium nitrate, and continue stirring for 30 minutes until uniformly dispersed.

[0056] Then, slowly add 3 parts by weight of potassium permanganate to the resulting mixture in portions, controlling the temperature to not exceed 20°C (to avoid violent exothermic reactions), and stir for 2 hours.

[0057] Maintain ice bath conditions and continue stirring for 2 hours to form a dark green, viscous paste.

[0058] Remove the ice bath, raise the temperature to 35±3℃, stir the reaction for 1 hour, and the solution turns brownish-brown.

[0059] Slowly add 46 parts by weight of deionized water (control the temperature <50℃) and stir for 15 minutes.

[0060] Add 140 parts by weight of deionized water, heat to 90-98℃, and react for 30 minutes.

[0061] Finally, add about 5.6 parts by weight of hydrogen peroxide (30%), and the solution turns bright yellow. Let it stand and cool to room temperature.

[0062] Centrifuge (8000 rpm, 10 min) to remove the supernatant acid, wash repeatedly with deionized water until neutral (pH≈7), and then dry.

[0063] Example 1 This example demonstrates the preparation of an oxygen-containing graphene dispersion, with the specific steps as follows: S1. Ultrasonication of the mixed aqueous dispersion formed by expanded graphite oxide and modifier; Among them, expanded graphite oxide is prepared by using commercially available 300-mesh flake graphite through the Hummers method and then expanding it in a muffle furnace at 1000°C for 1 minute.

[0064] The modifiers are glucose and p-phenylenediamine; The mass percentage of expanded graphite oxide in the mixed aqueous dispersion is 3%. The mass ratio of expanded graphite oxide to glucose is 1:3; The mass ratio of expanded graphene oxide to p-phenylenediamine is 1:7; The ultrasound duration was 30 minutes, with the ambient pressures sequentially at -0.08 MPa / 5 min, 0 MPa / 5 min, and 6 MPa / 5 min; this cycle was repeated. Here, 0 MPa refers to atmospheric pressure (this interpretation is used elsewhere), which is the air pressure in a natural experimental environment without pressurization or negative pressure treatment.

[0065] S2. The mixture obtained from freeze-drying step S1; S3. Irradiate the mixture obtained in step S2 with gamma in an oxygen-free environment; The gamma irradiation dose rate was 40 Gy / min, and the duration was 8 h.

[0066] S4. Disperse the irradiated product obtained in step S3 in water, and finally pass it through a 325-mesh sieve. The sieve-passing material is the oxygen-containing graphene dispersion.

[0067] In the resulting dispersion, the mass percentage of the irradiated product obtained in step S3 is 5%; The dispersion method is to use a high-speed blender for 15 minutes.

[0068] Example 2 This example prepares an oxygen-containing graphene dispersion. The specific steps differ from those in Example 1 in that: In step S1, ultrasound is performed for 30 minutes under normal pressure.

[0069] Example 3 This example prepares an oxygen-containing graphene dispersion. The specific steps differ from those in Example 1 in that: In step S1, the sugar modifier is fructose.

[0070] Comparative Example 1 This example prepares an oxygen-containing graphene dispersion. The specific steps differ from those in Example 1 in that: In step S1, the sugar modifier is replaced with an equal mass of sucrose.

[0071] Comparative Example 2 This example prepares an oxygen-containing graphene dispersion. The specific steps differ from those in Example 1 in that: The irradiation conditions in step S3 are omitted, i.e., the same temperature and other conditions are applied for the same amount of time as in Example 1.

[0072] Application examples This example uses the oxygen-containing graphene dispersion obtained in the examples and comparative examples as raw materials to perform black hole treatment on a PCB board (epoxy resin material). The specific steps are as follows: D1. The PCB board after drilling is immersed in a hole-clearing solution and then cleaned; the immersion temperature is 30℃ and the immersion time is 45s; the hole-clearing solution is purchased from Guangzhou Huike High-tech Materials Technology Co., Ltd., model WT-37; the cleaning method is rinsing with deionized water.

[0073] D2. Immerse the PCB board semi-finished product obtained in step D1 in a black hole liquid at 32°C for 45 seconds; the black hole liquid is the oxygen-containing graphene dispersion obtained in the examples and comparative examples; after taking it out, use a sponge roller to remove the excess oxygen-containing graphene dispersion.

[0074] Test case The first aspect of this example tested the thickness (number of layers) of oxygen-containing graphene in the oxygen-containing graphene dispersions obtained in the examples and comparative examples. The test method was HRTEM, observing the number of layers at the edge of the oxygen-containing graphene. Statistical analysis was performed on 100 samples within the field of view. After removing the maximum and minimum values, the average number of layers was calculated and rounded down.

[0075] The second aspect of this example tested the stability of the oxygen-containing graphene dispersions obtained in the examples and comparative examples. Specifically, the transmittance of the oxygen-containing graphene dispersions at 600 nm was tested after being stored at room temperature (approximately 25°C) and at 60°C under air-isolated conditions for 2 hours, respectively; and the transmittance at 600 nm was tested after being stored naturally at room temperature under air-isolated conditions for 2 months. The testing instrument was a UV-Vis spectrophotometer.

[0076] The third aspect of this example tested the flatness of the black hole film on the PCB board obtained from the application example. The test methods were SEM and AFM. Specifically, a height difference >6nm was evaluated as unevenness.

[0077] The fourth aspect of this example tested the adhesion of the oxygen-containing graphene dispersion obtained in the example to an epoxy resin board. The specific test method was as follows: first, the surface of the epoxy resin board was rubbed with a metal grinding wheel, and then it was immersed in the pore-forming liquid and the oxygen-containing graphene dispersion in sequence using the same method as in the application example; finally, the adhesion was tested according to the standard ISO 2409-2013 "Paints and varnishes - Cross-section test".

[0078] The fifth aspect of this example tested the resistance of the PCB board obtained from the application example. Specifically, the resistance was tested using an RTS-9 dual-electrical-measurement four-probe tester. Three test points were randomly selected on the PCB board, and the average value of the test results was taken.

[0079] The test results are shown in Tables 1 and 2.

[0080] Table 1. Physicochemical properties of oxygen-containing graphene obtained in the examples and comparative examples. Comparing the thickness results of Examples 1, 3, and Comparative Example 1, it can be seen that, under the same irradiation conditions, glucose has a higher G value than fructose, and significantly higher than sucrose (larger molecules, making it difficult to penetrate the interlayer). Therefore, the degree of graphene exfoliation by the generated gas is better in Example 1 than in Example 2, which is better than in Comparative Example 1. Thus, in the oxygen-containing graphene dispersion obtained in Example 1, the number of oxygen-containing graphene layers is the thinnest (in reality, it is mostly single or double-layer graphene), followed by Example 3, and the thickest is Comparative Example 1. Comparing the thickness results of Examples 1 and 2, it can be seen that the cyclic positive and negative pressure process has a certain positive effect on the exfoliation of expanded graphene oxide, but even without this condition, the obtained oxygen-containing graphene dispersion still meets the usage requirements. Comparing the thickness results of Examples 1 and Comparative Example 2, it can be seen that gamma irradiation can indeed produce physicochemical changes, significantly improving the exfoliation process of expanded graphene oxide.

[0081] Regarding the relationship between stability and transmittance in Table 1: In dispersions of the same mass concentration, if oxygen-containing graphene aggregates and settles, or if the number of layers is too high, its dispersion in the dispersion is not uniform enough, leaving sufficient channels for light transmission, and the transmittance will significantly increase. Therefore, the initial results of stability are basically consistent with the trend of its layer number results; in addition, high temperature promotes the aggregation of colloids, so when stored for the same time, the product obtained by high-temperature storage has higher transmittance. Furthermore, specific modifiers and specific gamma irradiation conditions can graft oxygen-containing graphene. The type and density of grafting groups also affect the dispersion stability of oxygen-containing graphene in water to some extent. Based on this, comparing Example 1 and Comparative Examples 1-2, it can be seen that under the same irradiation conditions, sucrose as a modifier either cannot graft oxygen-containing graphene, or because the sucrose molecules are too large, the positive effect on dispersibility after grafting is small. In short, the storage stability of the oxygen-containing graphene dispersion obtained in Comparative Example 1 is significantly reduced; while without grafting (Comparative Example 2), its storage stability is the worst.

[0082] Table 2 shows the black hole effect of the PCB board obtained from the application example. The smoothness is related to both the number of oxygen-containing graphene layers and their arrangement on the PCB substrate. In Examples 1-3, due to the smaller number of oxygen-containing graphene layers and the grafting of the modifier onto the graphene, the grafted groups guide the arrangement of the graphene on the PCB substrate (by combining with the positive and negative charges or chemical groups on the PCB substrate after hole filling), resulting in better smoothness. In Comparative Examples 1-2, not only are the layers thicker, but there are also no grafted groups or the grafted groups are unsuitable, resulting in poorer smoothness. It is precisely because of the aforementioned effect of the grafted groups that the adhesion of Examples 1-3 is significantly better than that of Comparative Examples 1-2. Finally, there is a certain relationship between resistance and the uniformity of oxygen-containing graphene adhesion on the PCB substrate, as well as the conductivity of the oxygen-containing graphene itself. Specifically, when the concentration of the oxygen-containing graphene dispersion is the same, if its uniformity is poor, the density of conductive pathways formed on the PCB substrate decreases, and the conductivity decreases. This is the main reason for the difference in conductivity in Examples 1-3. In Comparative Examples 1-2, the main reason for the significant decrease in conductivity is that the oxygen-containing groups in graphene oxide destroy its structure (sp²→sp³) and produce physical defects, so the conductivity of graphene oxide itself is poor. Therefore, if both conductivity and water dispersibility of graphene are required, graphene oxide needs to be further reduced to obtain reduced graphene oxide. In Comparative Examples 1-2, due to improper selection of modifiers or the lack of a gamma irradiation environment, the modifiers cannot reduce graphene oxide, that is, the oxygen-containing graphene in the oxygen-containing graphene dispersion is mainly graphene oxide.

[0083] In summary, the oxygen-containing graphene dispersion provided by this invention, due to limitations in the preparation process, contains reduced graphene oxide with a small number of layers and grafted groups that can anchor groups on the PCB substrate. Therefore, after being used for black hole treatment of PCB boards, the resulting film layer exhibits excellent flatness, adhesion, and conductivity. It is expected that the PCB board semi-finished product after black hole treatment using the oxygen-containing graphene dispersion provided by this invention, the subsequent electroplated copper layer, and the final PCB board will all have excellent performance.

[0084] The embodiments of the present invention have been described in detail above. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention. Furthermore, the embodiments of the present invention and the features thereof can be combined with each other unless otherwise specified.

Claims

1. A method for preparing an oxygen-containing graphene dispersion, characterized in that, The preparation method includes the following steps: S1. Ultrasonication of the mixed aqueous dispersion formed by expanded graphite oxide and modifier; The modifier is a carbohydrate modifier; the carbohydrate modifier includes at least one of glucose and fructose; S2. The mixture obtained from freeze-drying step S1; S3. Irradiate the mixture obtained in step S2 with gamma in an oxygen-free environment; S4. Disperse the irradiated product obtained in step S3 in water.

2. The preparation method according to claim 1, characterized in that, In step S1, the mass percentage of the expanded graphite oxide in the mixed aqueous dispersion is 1-5%.

3. The preparation method according to claim 1, characterized in that, In step S1, the mass ratio of the expanded graphite oxide to the sugar modifier is 1:1~5.

4. The preparation method according to claim 1, characterized in that, In step S1, the modifier further includes an amino modifier; and the amino modifier includes at least one of p-phenylenediamine and o-phenylenediamine.

5. The preparation method according to claim 4, characterized in that, In step S1, the mass ratio of the expanded graphite oxide to the amino modifier is 1:5~15.

6. The preparation method according to any one of claims 1 to 5, characterized in that, In step S1, the ultrasound includes cyclic positive and negative pressure environments.

7. The preparation method according to any one of claims 1 to 5, characterized in that, In step S3, the dose rate of the gamma irradiation is 30~100 Gy / min.

8. The preparation method according to any one of claims 1 to 5, characterized in that, In step S3, the duration of gamma irradiation is 1 to 10 hours.

9. An oxygen-containing graphene dispersion prepared by the preparation method according to any one of claims 1 to 8.

10. A PCB board, characterized in that, The raw materials for preparing the PCB board include the oxygen-containing graphene dispersion as described in claim 9.

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