Substrate hole film forming method and application thereof

Abstract

The application discloses a substrate hole film forming method and application thereof, and the method comprises the following steps: (1) pre-treating the surface and hole structure of an insulating substrate; (2) coating a prepared graphene dispersion liquid on the surface and hole structure of the insulating substrate with adjusted electric charge in step (1), and simultaneously applying rotary drying with different rotating radii and different rotating speeds to the insulating substrate to form a conductive layer for metal electroplating; and (3) electroplating the insulating substrate with the conductive layer in step (2). The graphene dispersion liquid comprises water, graphene, a combination aid and a water-soluble conductive polymer; and the thickness-diameter ratio of the substrate and the hole structure thereof is 0.5-20:1. The graphene layer with uniform thickness is formed in the hole structure of the insulating substrate treated by the hole film forming method, so that the metal layer formed by subsequent electroplating also has uniform thickness, and the hole structure is prevented from being blocked.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of electroplating, and particularly relates to a substrate hole film forming method and application thereof. BACKGROUND

[0002] With the rapid development of electronic technology, 5G, Internet of Things, flexible wearable electronic devices and the like have put forward requirements of high wiring density, high precision, high frequency and high speed, high heat dissipation and the like for printed circuit boards (PCB). The preparation technology of PCB has become the focus of the scientific research and industrial circles. Hole metallization as a key link of PCB preparation is the basis for determining the electrical interconnection performance of PCB, and its research runs through the entire development history of PCB. The traditional hole metallization process is mainly based on chemical copper plating, which has high maturity, good stability and high reliability, but has the defects of heavy pollution (use of carcinogenic substances), high cost (use of noble metal palladium) and long process flow, which cannot be ignored. Therefore, it is urgent to develop a new generation of green hole metallization technology.

[0003] The graphene hole metallization process is a new hole metallization process developed on the basis of the black hole direct plating technology. Because graphene has super-high conductivity and thermal conductivity, the graphene hole metallization process is likely to overcome the defects of insufficient conductivity and heat dissipation of the traditional black hole direct plating technology, thereby promoting the great development of the direct plating field.

[0004] A Chinese patent with application number 201811009256.3 discloses a graphene metallization solution and a preparation method and application thereof. The graphene metallization solution is prepared from the following raw materials according to mass percentage: graphene or graphene oxide 0.5-5.0%; film forming agent 1-3%; dispersing agent 1-6%; anionic surfactant 0.01-0.2%; alkaline solution, adjusting pH value to 4-14; and the balance is water. The invention uses low-concentration graphene or low-oxidation-degree graphene oxide material as the basic conductive material. Through simple and efficient pretreatment, the graphene metallization solution can be effectively adsorbed on the surface or hole wall of the non-metallic substrate, and then subjected to simple drying treatment, and then directly electroplated with copper. However, the invention does not involve metallization in high aspect ratio holes.

[0005] In view of the above, the present application is proposed. SUMMARY

[0006] The technical problem solved by the present application is to overcome the deficiencies of the prior art and provide a substrate hole film forming method and application thereof. The special drying method combining revolution and rotation is used to make the graphene enriched in the substrate hole structure form a uniform graphene conductive layer under the action of different centrifugal forces generated by multiple rotations, and then the plating layer formed by subsequent electroplating has a uniform thickness, preventing the blockage of high aspect ratio substrate holes.

[0007] To solve the above technical problems, the basic idea of the technical solution of the present application is:

[0008] The present application provides a substrate hole film forming method, the substrate includes a surface and a hole structure recessed in the surface, comprising:

[0009] (1) pretreating the surface and hole structure of the insulating substrate;

[0010] (2) coating the prepared graphene dispersion liquid on the surface and hole structure of the insulating substrate with adjusted charge in step (1), and simultaneously applying rotary drying with different rotation radii and different rotation speeds to the insulating substrate to form a conductive layer for metal electroplating;

[0011] (3) electroplating the insulating substrate with the conductive layer in step (2);

[0012] The graphene dispersion liquid includes water, graphene, a binding aid and a water-soluble conductive polymer. The binding aid enhances the covalent connection between the conductive layer and the electroplated metal during electroplating treatment, and at the same time interacts with the groups of the pretreated surface and hole structure of the insulating substrate. The thickness-to-diameter ratio of the substrate and its hole structure is 0.5-20:1, preferably 10-20:1.

[0013] In the above scheme, the insulating substrate includes, but is not limited to, epoxy glass cloth reinforced material, polyimide glass cloth reinforced material, polytetrafluoroethylene glass cloth reinforced material, polyimide film, acrylic film, hydrocarbon resin, etc. According to the chemical composition and charge type of the substrate surface, such as the existence of hydroxyl on the surface of epoxy glass cloth, amino on the surface of imine, etc. Add corresponding types of binding aids in the graphene solution, such as binding aids containing sulfonic acid groups, amino groups, epoxy groups or isocyanate groups, which can produce hydrogen bond and covalent bond interaction with the above groups, and improve the interface energy between graphene and the substrate; The surface of the surface treated insulating material is negatively or positively charged, and the pH value of the graphene solution is adjusted accordingly, so that the graphene and the substrate form electrostatic interaction; In addition, such binding aids can also form covalent connection between the electroplated metal, and the multi-layer structure of graphene itself can form an interpenetrating network structure with the electroplated metal under certain physical method treatment and drying process, thereby enhancing the binding ability of the two. Specifically, the water-soluble conductive polymer is used for non-covalent surface modification of graphene, so that the water-soluble conductive polymer and graphene produce π-π interaction, and the functional groups of the water-soluble conductive polymer improve the surface activity of graphene, so that graphene can be uniformly dispersed in the dispersion system. The electroplating can be selected from the conventional electroplated metal types in the art, and copper is preferred.

[0014] According to the above method, the graphene dispersion liquid further comprises a binding aid selected from one or more of polyvinyl alcohol, polyvinylpyrrolidone, polyethyleneimine, polyethylene glycol, polyacrylate, water-based polyurethane, water-based epoxy, polymaleic anhydride, polyacrylic acid, polymethacrylic acid, polystyrene sulfonic acid, polyvinyl sulfonic acid, polyvinyl phosphoric acid, polyvinyl amine, and polyvinyl pyridine.

[0015] In the above scheme, the conjugated system generated between the binding aid, the water-soluble conductive polymer and the graphene improves the composite compatibility, maintains the performance of graphene in the formed conductive layer, enhances the conductivity of the conductive layer, and is beneficial to the formation of the electroplated metal layer.

[0016] According to the above method, the graphene dispersion liquid is prepared by the following method:

[0017] The binding aid and the water-soluble conductive polymer are dissolved in deionized water to form a mixed solution, and then graphene is added to the mixed solution, and a graphene dispersion liquid is obtained by physical method treatment;

[0018] The physical method is selected from one or both of grinding and ultrasonic treatment;

[0019] More preferably, the pH value of the graphene dispersion liquid is 3-12.

[0020] In the above scheme, the binding aid and water-soluble conductive polymer are first dissolved into a mixed solution and then graphene is added. Compared with adding the binding aid and graphene into the solution at the same time, the self-aggregation effect of graphene can be greatly avoided, so that the water-soluble conductive polymer is more likely to form non-covalent bond modification with the surface of graphene, thereby improving the dispersibility of graphene in water. The surface of the surface-treated insulating material is negatively or positively charged, and the pH value of the graphene solution is adjusted by using a pH adjuster known in the art. When the pH range of the graphene dispersion is 3-12, stronger electrostatic interaction can be formed between graphene and the substrate.

[0021] According to the above method, the average number of layers of graphene in the graphene dispersion is not more than 10, preferably 1-5 layers.

[0022] In the above scheme, the graphene is peeled off under physical action, so that the graphene in the dispersion remains in an interlayer open state, which makes the surface of the conductive layer after coating and drying have a number of voids that can form interpenetration with the plated metal, greatly improving the bonding strength of the plated metal and the conductive layer.

[0023] According to the above method, the mass ratio of graphene, binding aid and water-soluble conductive polymer is 1:0.05-20:0.01-20, preferably 1:0.1-3:0.05-3; the mass fraction of graphene in the graphene dispersion is 0.05-10%, preferably 0.1-5%, more preferably 5%; the water-soluble conductive polymer is one or more of water-soluble polyaniline, water-soluble polythiophene, polyepoxy chloropropane quaternary ammonium salt, etc.

[0024] According to the above method, the rotation speed of the grinding is 100-5000 rpm, preferably 1000-3000 rpm; the grinding time is 1 min-3 h, preferably 10 min-1 h.

[0025] According to the above method, the frequency of the ultrasonic is 25-100 kHz, preferably 40-75 kHz; the ultrasonic time is 30 min-24 h, preferably 4-12 h.

[0026] According to the above method, the grinding and ultrasonic are preferably performed simultaneously. When both are performed simultaneously, the running time of grinding and ultrasonic is selected to be longer in some implementation cases, and the grinding can be stopped after the grinding time ends and the ultrasonic continues.

[0027] According to the above method, in the step (2), the drying process comprises: drying the graphene dispersion liquid coated insulating substrate in the form of self-rotation and revolution at the same time, the drying temperature is 40-100℃, the self-rotation speed is 600-800rpm, the revolution speed is 850-1200rpm, the self-rotation is carried out around the straight line which passes through any point of the insulating substrate plane and is perpendicular to the insulating substrate plane, and the revolution is carried out around the line segment which extends outward from the geometric center of the insulating substrate along the insulating substrate plane; preferably, the self-rotation is carried out around the straight line which passes through the geometric center of the insulating substrate and is perpendicular to the insulating substrate plane.

[0028] In the above scheme, the high aspect ratio substrate hole structure has a certain capillary effect, and when graphene dispersion is used for coating and infiltration, the liquid will fill the inside of the hole structure, so that the traditional drying method may cause the components in the graphene dispersion liquid to block the substrate hole after drying due to uneven heating and other reasons. To this end, the related staff of the present application respectively use self-rotation and revolution drying for the substrate, and find that the graphene dispersion liquid in the hole structure is affected by the centrifugal force during the drying process, thereby avoiding the effect of blocking the plate hole. Further, the related staff of the present application further find that when the graphene dispersion liquid on the inner wall of the hole structure is simultaneously affected by centrifugal forces of different sizes during the drying process after combining the self-rotation and revolution of the substrate, a graphene layer with uniform thickness and certain micropore and gully structure is formed on the hole wall, so that the plating layer formed in the subsequent electroplating is more uniform, and has good combination effect with the graphene conductive layer.

[0029] According to the above method, in the step (1), the substrate is selected from hydrophilic materials or non-hydrophilic materials, wherein the non-hydrophilic materials are pre-treated to make the surface and / or hole structure hydrophilic; the pre-treatment comprises pre-washing and / or charge adjustment, and the charge adjustment comprises: carrying out plasma treatment on the surface and / or hole structure of the substrate, treating the surface and / or hole structure of the substrate with cationic surfactant or anionic surfactant, or rubbing the surface and / or hole structure of the substrate to make the surface and / or hole structure of the substrate have positive or negative charge.

[0030] In the above scheme, the rubbing treatment can be realized at the same time when drilling the surface of the substrate.

[0031] The hydrophilic material includes, but is not limited to, polyamide, polyvinyl acetate, epoxy resin, acrylate or their composite materials; the non-hydrophilic material includes, but is not limited to, polyimide, polycarbonate, polylactic acid, polyurethane, polycaprolactone, polymethyl methacrylate, polyhydroxyethyl methacrylate, poly-beta-hydroxybutyric acid, polybutylene terephthalate, polyethylene terephthalate, poly-2,6-naphthalene dicarboxylic acid diethylene, polystyrene, polypropylene, polyethylene, poly-1-butene, poly-4-methyl-1-pentene, or their composite materials; the substrate is preferably an epoxy resin / glass fiber composite, polyimide, polyethylene terephthalate, polyimide / glass fiber composite, acrylate, etc.

[0032] When the substrate is a hydrophilic material, the pre-washing includes ultrasonic cleaning of the substrate with 1% NaOH solution, and the pre-washing time is 0.5-5 min.

[0033] When the substrate is a non-hydrophilic material, the pre-washing includes soaking the substrate in 10% NaOH solution for 20-40 min, then removing the alkali and drying. The surface of the treated substrate is a hydrophilic surface.

[0034] According to the above surface treatment method, the coating in step (2) includes soaking, blade coating or spraying; the soaking includes soaking the substrate in the ultrasonically dispersed graphene dispersion liquid, and the soaking time is 5 s-5 min, preferably 30-60 s; the blade coating includes blade coating the substrate to be plated with the ultrasonically dispersed graphene dispersion liquid, and the film thickness of the blade coating is 0.05-100 μm, preferably 0.1-10 μm; the spraying includes spraying the substrate to be plated with the ultrasonically dispersed graphene dispersion liquid, and the film thickness of the spraying is 0.05-100 μm, preferably 0.1-10 μm; preferably, the blade coating or spraying is repeated on the substrate for multiple times; more preferably, the coating is stopped when the surface resistance of the substrate is lower than 100 Ω, preferably lower than 20 Ω.

[0035] In the above scheme, when the substrate itself is uneven, the spraying method is preferably used for coating.

[0036] The substrate surface treatment method specifically includes the following steps:

[0037] (1) substrate pretreatment: according to the material of the substrate, corresponding pre-washing and charge adjustment are carried out; when the substrate is a hydrophilic material, the pre-washing includes: ultrasonic cleaning the surface to be plated of the substrate with 1% NaOH solution, and the pre-washing time is 0.5-5 min; when the substrate is a non-hydrophilic material, the pre-washing includes: immersing the surface to be plated of the substrate in 10% NaOH solution for 20-40 min, then taking out and washing off the alkali solution and drying; the charge adjustment includes: treating the surface and pore structure of the substrate with plasma, treating the surface and pore structure of the substrate with cationic or anionic surfactant, or rubbing the surface and pore structure of the substrate to make the surface of the substrate carry positive or negative charge; the pretreatment makes the non-hydrophilic surface become a hydrophilic surface;

[0038] (2) preparation of graphene dispersion liquid: combine the adjuvant and water-soluble conductive polymer in deionized water to form a mixed solution, then add graphene into the mixed solution, and treat by physical method to obtain graphene dispersion liquid with mass ratio of graphene:adjuvant:water-soluble conductive polymer being 1:0.05-20:0.01-20, mass fraction of graphene in the graphene dispersion liquid being 0.05-10%, preferably 0.1-5%; the physical method is selected from one or both of grinding and ultrasonic treatment; the rotation speed of grinding is 100-5000 rpm, preferably 1000-3000 rpm; the grinding time is 1 min-3 h, preferably 10 min-1 h; the frequency of ultrasonic treatment is 25-100 kHz, preferably 40-75 kHz; the ultrasonic treatment time is 30 min-24 h, preferably 4-12 h;

[0039] (3) coating and acid treatment after electroplating: the graphene dispersion solution prepared in step (2) is coated on the surface and pore structure of the substrate pretreated in step (1) and dried, and then electroplating is performed on the insulating substrate with the conductive layer; the coating includes immersion, blade coating or spraying; the immersion includes: immersing the substrate in the ultrasonic dispersed graphene dispersion solution for 5s-5min; the blade coating includes: using the ultrasonic dispersed graphene dispersion solution to blade coat the surface of the substrate to be electroplated, and the film thickness is 0.05-100μm; preferably, the film thickness of the blade coating is 0.1-10μm; the spraying includes: using the ultrasonic dispersed graphene dispersion solution to spray the surface of the substrate to be electroplated, and the film thickness is 0.05-100μm; preferably, the film thickness of the spraying is 0.1-10μm; preferably, the substrate is repeatedly blade coated or sprayed, and drying is performed between each blade coating or spraying; the drying process includes: drying the insulating substrate coated with the graphene dispersion solution in the form of self-rotation and revolution, the drying temperature is 40-100℃, the self-rotation speed is 600-800rpm, and the revolution speed is 850-1200rpm, the self-rotation is performed with a straight line passing through any point of the insulating substrate plane and perpendicular to the insulating substrate plane as the axis, and the revolution is performed with a line segment extending outward from the geometric center of the insulating substrate as the radius; preferably, the self-rotation is performed with a straight line passing through the geometric center of the insulating substrate and perpendicular to the insulating substrate plane as the axis.

[0040] The application also provides an application of the above-mentioned basic in-pore film forming method in electroplating of a flexible circuit board, preferably for metalization of a flexible circuit board and a non-metal surface.

[0041] After the above technical solution is adopted, the application has the following beneficial effects compared with the prior art:

[0042] 1. The special drying method of multi-angle rotation provided by the application enables the graphene enriched in the pore structure of the substrate to form a uniform graphene conductive layer under the centrifugal force generated by multi-angle rotation, and then the plating layer formed by subsequent electroplating has a uniform thickness, preventing the blockage of the pores of the high thickness-to-diameter ratio substrate;

[0043] 2. The dispersion solution provided by the application uses graphene with a certain number of layers as the main raw material, partially separates the graphene layers by physical methods, and improves the drying process, so that the graphene coated and dried on the surface of the insulating substrate contains a large number of voids that can form interpenetration with the electroplated metal, greatly improving the bonding strength of the metal and the conductive layer after electroplating;

[0044] 3. The graphene dispersion liquid provided by the present application contains a binding aid, which enhances the covalent connection between the conductive layer and the electroplated metal during electroplating treatment, and at the same time interacts with the hydrogen bond of the surface group of the insulating substrate, greatly enhancing the interfacial bonding capacity of the conductive layer formed by the graphene dispersion liquid to the insulating substrate and the electroplated metal, so that the electroplated layer formed by subsequent surface treatment has good bonding performance and scratch resistance to the insulating substrate; in addition, the binding aid can also play a role in stabilizing the dispersed graphene;

[0045] 4. In the surface treatment method provided by the present application, the solvent used for preparing the dispersion liquid by physical methods such as grinding and / or ultrasonic is mainly water, and the solvent discards the organic reagents commonly used in the prior art, mainly using environmentally friendly water, reducing the environmental burden of the treatment method, and greatly reducing the treatment cost;

[0046] 5. The surface treatment method provided by the present application provides a feasible technical solution for obtaining a circuit by using an additive method electroplating for a flexible circuit board;

[0047] 6. The present application uses a graphene coating to replace a chemical plating coating, and graphene has higher conductivity and thermal conductivity, which can provide a new development direction for improving the use performance of the circuit board itself.

[0048] The specific embodiments of the present application will be further described in detail below. DETAILED DESCRIPTION

[0049] In order to make the purpose, technical scheme and advantages of the embodiments of the present application more clear, the technical scheme in the embodiments will be clearly and completely described below, and the following embodiments are used to illustrate the present application, but not to limit the scope of the present application.

[0050] Embodiment 1

[0051] In this embodiment, the following method is used for substrate surface treatment:

[0052] (1) Substrate pretreatment: the substrate is polyamide, and the surface and pore structure thereof are subjected to friction treatment, and then the surface to be electroplated and the drill hole of the substrate are ultrasonically cleaned with 1% NaOH solution, the pre-washing time is 0.5 min, and then it is taken out and dried for standby;

[0053] (2) Preparation of graphene dispersion liquid: combine the adjuvant polyacrylate and water-soluble conductive polymer polythiophene in deionized water, grind for 10 min at 3000 rpm to obtain a mixture, then add graphene to the mixture, and grind for 1 h at 2000 rpm to obtain a graphene dispersion liquid with a mass ratio of graphene: polyacrylate: water-soluble polythiophene of 1:0.05:0.05, a mass fraction of graphene in the graphene dispersion liquid of 10%, and a pH of the graphene dispersion liquid of 7.5;

[0054] (3) Coating to form a conductive layer: coat the graphene dispersion liquid prepared in step (2) on the surface of the pre-washed substrate in step (1) to form a conductive layer for direct electroplating; the coating is selected from immersion, in which the substrate is immersed in the ultrasonically dispersed graphene dispersion liquid for 5 s, and then taken out and dried; the drying includes simultaneously drying the graphene dispersion liquid-coated insulating substrate in the form of self-rotation and revolution, with a drying temperature of 60°C, a self-rotation speed of 800 rpm, a revolution speed of 1000 rpm, the self-rotation being performed about a straight line passing through the geometric center of the insulating substrate and perpendicular to the plane of the insulating substrate, and the revolution being performed about a line segment extending outward from the geometric center of the insulating substrate along the plane of the insulating substrate as a radius, and a drying time of 15 min.

[0055] In this embodiment, the thickness-to-diameter ratio of the insulating substrate and its pore structure is 20:1.

[0056] Example 2

[0057] In this embodiment, the surface of the substrate is treated by the following method:

[0058] (1) Substrate pretreatment: the substrate is polyethylene terephthalate, and the surface and pore structure thereof are subjected to plasma treatment, and then the surface to be electroplated of the substrate is immersed in a 10% NaOH solution for 20 min, after which the alkali solution is washed off and dried;

[0059] (2) Preparation of graphene dispersion liquid: combine the adjuvant polyacrylate and water-soluble conductive polymer polythiophene in deionized water, grind for 10 min at 3000 rpm to obtain a mixture, then add graphene to the mixture, and grind for 1 h at 2000 rpm to obtain a graphene dispersion liquid with a mass ratio of graphene: polyacrylate: water-soluble polythiophene of 1:0.05:0.05, a mass fraction of graphene in the graphene dispersion liquid of 10%, and a pH of the graphene dispersion liquid of 7.5;

[0060] (3) coating to form a conductive layer: coating the graphene dispersion prepared in step (2) on the surface of the pre-washed substrate in step (1) to form a conductive layer for direct electroplating; the coating is selected from blade coating, repeatedly coating the graphene dispersion dispersed by ultrasonic on the surface of the substrate several times, drying after each coating, and repeating the process several times, the thickness of the coating film is 10 μm each time, and the desired conductive layer is obtained after drying; the drying includes: drying the graphene dispersion coated insulating substrate in the form of revolution and rotation at the same time, the drying temperature is 70℃, the revolution speed is 600 rpm, and the rotation speed is 850 rpm, the revolution is performed along the straight line passing through the geometric center of the insulating substrate and perpendicular to the plane of the insulating substrate, the rotation is performed along the line segment extending outward from the geometric center of the insulating substrate along the plane of the insulating substrate, and the drying time is 10 min.

[0061] In this embodiment, the thickness-diameter ratio of the insulating substrate and its pore structure is 19:1.

[0062] Example 3

[0063] In this embodiment, the surface treatment of the substrate is performed by the following method:

[0064] (1) substrate pretreatment: the substrate is an epoxy resin / glass fiber composite, the surface thereof is washed with deionized water, and the surface to be plated of the substrate is ultrasonically cleaned with 1% NaOH solution, the pretreatment time is 5 min, and then the substrate is dried for standby;

[0065] (2) preparation of graphene dispersion: poly (maleic anhydride) and water-soluble conductive polymer poly (epoxy chloropropane quaternary ammonium salt) are dissolved in deionized water, and the mixture is ground at 500 rpm and treated by ultrasonic at 40 kHz for 1 h to obtain a mixed solution, then graphene is added to the mixed solution, and the mixture is ground at 5000 rpm and treated by ultrasonic at 100 kHz for 3 h to obtain a graphene dispersion with a mass ratio of graphene: poly (maleic anhydride): poly (epoxy chloropropane quaternary ammonium salt) of 1:3:0.01, the mass fraction of graphene in the graphene dispersion is 2%, and the pH of the graphene dispersion is adjusted to 12;

[0066] (3) coating to form a conductive layer: coating the graphene dispersion prepared in step (2) on the surface of the pre-washed substrate in step (1) to form a conductive layer for direct electroplating; the coating is selected from spraying, spraying a film liquid with a thickness of 0.5 μm on the surface of the substrate using the ultrasonic dispersed graphene dispersion, drying again, spraying a film liquid with a thickness of 0.5 μm and drying, repeating several times, and finally drying to form a conductive layer; the drying includes: drying the insulating substrate coated with the graphene dispersion simultaneously in the form of self-rotation and revolution, the drying temperature is 80℃, the self-rotation speed is 700 rpm, and the revolution speed is 1200 rpm, the self-rotation is performed with a straight line passing through the geometric center of the insulating substrate and perpendicular to the plane of the insulating substrate as the axis, the revolution is performed with a line segment extending outward from the geometric center of the insulating substrate along the plane of the insulating substrate as the radius, and the drying time is 5 min.

[0067] In this embodiment, the thickness-diameter ratio of the insulating substrate and its pore structure is 10:1.

[0068] Example 4

[0069] In this embodiment, the surface treatment of the substrate is performed by the following method:

[0070] (1) substrate pretreatment: the substrate is polyethylene terephthalate with a surface containing a concave pore structure, the surface to be electroplated of the substrate and the pore structure are soaked in a 10% NaOH solution for 30 min, then taken out, washed with alkali solution and dried;

[0071] (2) preparation of graphene dispersion: dissolving the combination aid water-based polyurethane and the water-soluble conductive polymer polyaniline in deionized water, grinding for 1 min at 100 rpm to obtain a mixed solution, then adding graphene into the mixed solution, and grinding for 30 min at 3000 rpm to obtain a graphene dispersion with a mass ratio of graphene, water-based polyurethane and water-soluble polyaniline of 1:10:3, the mass fraction of graphene in the graphene dispersion is 0.1%, and the pH of the graphene dispersion is adjusted to 8;

[0072] (3) coating to form a conductive layer: coating the graphene dispersion prepared in step (2) on the surface of the pre-washed substrate in step (1) to form a conductive layer for direct electroplating; the coating is selected from soaking, soaking the substrate in the ultrasonic dispersed graphene dispersion for 60 s, and then drying; the drying includes: drying the insulating substrate coated with the graphene dispersion simultaneously in the form of self-rotation and revolution, the drying temperature is 85℃, the self-rotation speed is 750 rpm, and the revolution speed is 1100 rpm, the self-rotation is performed with a straight line passing through the geometric center of the insulating substrate and perpendicular to the plane of the insulating substrate as the axis, the revolution is performed with a line segment extending outward from the geometric center of the insulating substrate along the plane of the insulating substrate as the radius, and the drying time is 4 min.

[0073] In this embodiment, the thickness-to-diameter ratio of the insulating substrate and its pore structure is 15:1.

[0074] Example 5

[0075] In this embodiment, the substrate surface is treated by the following method:

[0076] (1) Substrate pretreatment: the substrate is polyvinyl acetate, the surface and pore structure of the substrate are treated by plasma, and then the surface to be plated of the substrate is ultrasonically cleaned with 1% NaOH solution for 1 min, and then taken out and dried for standby;

[0077] (2) Preparation of graphene dispersion: polyvinylpyrrolidone and water-soluble conductive polymer polyaniline are dissolved in deionized water, and a mixed solution is obtained by ultrasonic treatment at 60 kHz for 1 h, then graphene is added to the mixed solution, and a graphene dispersion with a mass ratio of graphene: polyvinylpyrrolidone: water-soluble conductive polymer of 1:0.15:0.1 is obtained by ultrasonic treatment at 40 kHz for 10 h, the mass fraction of graphene in the graphene dispersion is 0.7%, and the pH of the graphene dispersion is adjusted to 5.5;

[0078] (3) Coating to form a conductive layer: the graphene dispersion prepared in step (2) is coated on the surface of the substrate pretreated in step (1) to form a conductive layer for direct plating; the coating is selected from blade coating, and the film thickness of the graphene dispersion solution coated on the surface of the substrate to be plated is 100 μm, and a conductive layer is obtained after drying; the drying includes simultaneously drying the insulating substrate coated with the graphene dispersion in the form of self-rotation and revolution, the drying temperature is 90°C, the self-rotation speed is 800 rpm, and the revolution speed is 1150 rpm, the self-rotation is performed along the straight line passing through the geometric center of the insulating substrate and perpendicular to the plane of the insulating substrate, the revolution is performed by rotating around the line segment extending outward from the geometric center of the insulating substrate along the plane of the insulating substrate, and the drying time is 3 min.

[0079] In this embodiment, the thickness-to-diameter ratio of the insulating substrate and its pore structure is 17:1.

[0080] Example 6

[0081] In this embodiment, the substrate surface is treated by the following method:

[0082] (1) Substrate pretreatment: the substrate is polyvinyl acetate, the surface and pore structure of the substrate are treated by plasma, and then the surface to be plated of the substrate is ultrasonically cleaned with 1% NaOH solution for 1 min, and then taken out and dried for standby;

[0083] (2) Preparation of graphene dispersion liquid: the combination aid polystyrene sulfonic acid and water-soluble conductive polymer polyaniline were dissolved in deionized water, and a mixed solution was obtained by grinding at 500 rpm and ultrasonic treatment at 40 kHz for 1 h. Then, graphene was added into the mixed solution, and a graphene dispersion liquid with a mass ratio of graphene, polystyrene sulfonic acid and water-soluble polyaniline of 1:1.5:1.5 was obtained by grinding at 5000 rpm and ultrasonic treatment at 100 kHz for 3 h and then ultrasonic treatment at 75 kHz for 1 h. The mass fraction of graphene in the graphene dispersion liquid was 5%, and the pH of the graphene dispersion liquid was adjusted to 9;

[0084] (3) Coating to form a conductive layer: the graphene dispersion liquid prepared in step (2) was coated on the surface of the pre-washed substrate in step (1) to form a conductive layer for direct electroplating. The coating was selected from immersion, in which the substrate was immersed in the ultrasonically dispersed graphene dispersion liquid for 5 min, and then taken out and dried. The drying included simultaneously drying the graphene dispersion liquid coated insulating substrate in the form of self-rotation and revolution, with a drying temperature of 90°C, a self-rotation speed of 700 rpm and a revolution speed of 1200 rpm. The self-rotation was performed with a straight line passing through the geometric center of the insulating substrate and perpendicular to the plane of the insulating substrate as the axis. The revolution was performed with a line segment extending outward from the geometric center of the insulating substrate along the plane of the insulating substrate as the radius. The drying time was 5 min.

[0085] In this embodiment, the thickness-diameter ratio of the insulating substrate and its pore structure was 16:1.

[0086] Example 7

[0087] In this embodiment, the substrate surface was treated by the following method:

[0088] (1) Substrate pretreatment: the substrate was polylactic acid. The inner wall of the pore structure and the surface to be electroplated of the substrate were immersed in a 10% NaOH solution for 30 min, and then taken out, washed to remove the alkali solution and dried;

[0089] (2) Preparation of graphene dispersion liquid: the combination aid water-based epoxy and polyvinyl alcohol (mass ratio of 1:1) and water-soluble conductive polymer polythiophene were dissolved in deionized water, and a mixed solution was obtained by grinding at 2000 rpm and ultrasonic treatment at 25 kHz for 30 min. Then, graphene was added into the mixed solution, and a graphene dispersion liquid with a mass ratio of graphene, combination aid and water-soluble polythiophene of 1:1:0.5 was obtained by grinding at 3500 rpm and ultrasonic treatment at 40 kHz for 2 h. The mass fraction of graphene in the graphene dispersion liquid was 4%, and the pH of the graphene dispersion liquid was adjusted to 7;

[0090] (3) coating to form a conductive layer: coating the graphene dispersion prepared in step (2) on the surface of the pre-washed substrate in step (1) to form a conductive layer for direct electroplating; the coating is selected from spraying, repeatedly spraying the graphene dispersion liquid on the surface of the substrate several times, the film thickness of each spraying is 1 μm, and then drying, repeating the spraying several times and drying to obtain the conductive layer; the drying includes: drying the graphene dispersion coated insulating substrate in the form of rotation and revolution at the same time, the drying temperature is 80℃, the rotation speed is 600 rpm, and the revolution speed is 950 rpm, the rotation is performed along the straight line passing through the geometric center of the insulating substrate and perpendicular to the plane of the insulating substrate, the revolution is performed by rotating along the line segment extending outward from the geometric center of the insulating substrate in the plane of the insulating substrate, and the drying time is 5 min.

[0091] In this embodiment, the thickness-diameter ratio of the insulating substrate and its hole structure is 5:1.

[0092] Example 8

[0093] In this embodiment, the surface treatment of the substrate is carried out by the following method:

[0094] (1) substrate pretreatment: the substrate is polypropylene, the surface and hole structure thereof are subjected to friction treatment, and then the surface to be electroplated and the drilled hole of the substrate are immersed in a 10% NaOH solution for 30 min, and then taken out, washed with alkali and dried;

[0095] (2) preparation of graphene dispersion: combine the adjuvants polyvinyl sulfonic acid and polyvinyl phosphonic acid (mass ratio 1:1) with water-soluble conductive polymer polyaniline in deionized water, grind at 1000 rpm and simultaneously treat with 75 kHz ultrasonic for 1 h to obtain a mixed solution, then add graphene to the mixed solution, grind at 4000 rpm and simultaneously treat with 100 kHz ultrasonic for 2 h, and then separately treat with 60 kHz ultrasonic for 22 h to obtain a graphene dispersion with a mass ratio of graphene, adjuvant and water-soluble polyaniline of 1:1.5:1.5, the mass fraction of graphene in the graphene dispersion is 5%, and the pH of the graphene dispersion is adjusted to 10.5;

[0096] (3) coating to form a conductive layer: coating the graphene dispersion prepared in step (2) on the surface of the pre-washed substrate in step (1) to form a conductive layer for direct electroplating; the coating is selected from immersion, immersing the substrate in the ultrasonically dispersed graphene dispersion for 30 s, and then taking it out to dry; the drying includes: drying the graphene dispersion coated insulating substrate in the form of simultaneous rotation and revolution, the drying temperature is 80℃, the rotation speed is 780 rpm, the revolution speed is 1060 rpm, the rotation is performed with a straight line passing through the geometric center of the insulating substrate and perpendicular to the plane of the insulating substrate as the axis, the revolution is performed with a line segment extending outward from the geometric center of the insulating substrate along the plane of the insulating substrate as the radius, and the drying time is 5 min.

[0097] In this embodiment, the thickness-to-diameter ratio of the insulating substrate and its pore structure is 14:1.

[0098] Example 9

[0099] In this embodiment, the substrate surface treatment is performed as follows:

[0100] (1) substrate pretreatment: the substrate is polyurethane, the inner wall of the pore structure and the surface to be plated of the substrate are immersed in a 10% NaOH solution for 25 min, then taken out, washed and dried;

[0101] (2) preparation of graphene dispersion: combine the adjuvants polyethyleneimine and polyethylene glycol (mass ratio 7:3) with water-soluble conductive polymer polythiophene in deionized water, grind at 300 rpm and treat with 25 kHz ultrasound simultaneously for 10 min to obtain a mixed solution, then add graphene to the mixed solution, grind at 1500 rpm and treat with 75 kHz ultrasound simultaneously for 1 h to obtain a graphene dispersion with a mass ratio of graphene, adjuvant and water-soluble polythiophene of 1:1.5:2, the mass fraction of graphene in the graphene dispersion is 5%, and the pH of the graphene dispersion is adjusted to 6.5;

[0102] (3) coating to form a conductive layer: coating the graphene dispersion prepared in step (2) on the surface of the pre-washed substrate in step (1) to form a conductive layer for direct electroplating; the coating is selected from blade coating, the film thickness of the graphene dispersion liquid coated on the surface of the substrate by ultrasonic dispersion is 0.5 μm, and then dried, repeated several times of blade coating and drying, and finally dried to obtain the conductive layer; the drying includes: drying the graphene dispersion coated insulating substrate in the form of revolution and rotation at the same time, the drying temperature is 95℃, the revolution speed is 620 rpm, and the rotation speed is 890 rpm, the revolution is performed along the straight line passing through the geometric center of the insulating substrate and perpendicular to the plane of the insulating substrate as the axis, the rotation is performed by rotating along the line segment extending outward from the geometric center of the insulating substrate as the radius, and the drying time is 5 min.

[0103] In this embodiment, the thickness-diameter ratio of the insulating substrate and its pore structure is 0.5:1.

[0104] Example 10

[0105] In this embodiment, the substrate surface treatment is performed by the following method:

[0106] (1) substrate pretreatment: the substrate is polyimide, the surface and pore structure of the substrate are washed with deionized water, and then the substrate pore structure inner wall and the surface to be plated are immersed in 10% NaOH solution for 30 min, and then taken out, washed with alkali and dried;

[0107] (2) preparation of graphene dispersion: polyvinylpyridine and water-soluble conductive polymer polythiophene are dissolved in deionized water, and the mixture is obtained by grinding at 300 rpm and ultrasonic treatment at 25 kHz for 10 min, then graphene is added to the mixture, and the graphene dispersion with a mass ratio of graphene, polyvinylpyridine and water-soluble polythiophene of 1:1.5:3 is obtained by grinding at 1000 rpm and ultrasonic treatment at 75 kHz for 4 h, the mass fraction of graphene in the graphene dispersion is 5%, and the pH of the graphene dispersion is adjusted to 11;

[0108] (3) coating to form a conductive layer: coating the graphene dispersion prepared in step (2) on the surface of the pre-washed substrate in step (1) to form a conductive layer for direct electroplating; the coating is selected from spraying, repeatedly spraying the graphene dispersion liquid on the surface of the substrate for multiple times using the graphene dispersion liquid dispersed by ultrasonic, the film thickness of each spraying is 10 μm, then drying, and repeatedly spraying and drying, and finally forming a conductive layer after drying; the drying includes: drying the graphene dispersion coated insulating substrate in the form of revolution and rotation at the same time, the drying temperature is 100℃, the revolution speed is 780 rpm, and the rotation speed is 1120 rpm, the revolution is performed along the straight line passing through the geometric center of the insulating substrate and perpendicular to the plane of the insulating substrate as the axis, the rotation is performed by rotating along the line segment extending outward from the geometric center of the insulating substrate as the radius, and the drying time is 5 min.

[0109] In this embodiment, the thickness-diameter ratio of the insulating substrate and its pore structure is 2:1.

[0110] Example 11

[0111] In this embodiment, the surface treatment of the substrate is performed by the following method:

[0112] (1) substrate pretreatment: the substrate is an epoxy resin / glass fiber composite, the surface and pore structure thereof are treated by rubbing, and then the surface to be plated of the substrate is ultrasonically cleaned with 1% NaOH solution, and the pre-washing time is 5 min;

[0113] (2) preparation of graphene dispersion: combine the adjuvants polyacrylic acid and polymethacrylic acid (mass ratio 2:3) with water-soluble conductive polymer polythiophene in deionized water, grind at 500 rpm and treat with ultrasonic at 25 kHz for 1 h to obtain a mixed solution, then add graphene to the mixed solution, grind at 5000 rpm and treat with ultrasonic at 60 kHz for 3 h to obtain a graphene dispersion with a mass ratio of graphene, adjuvant and water-soluble polythiophene of 1:3:1, the mass fraction of graphene in the graphene dispersion is 2%, and the pH of the graphene dispersion is adjusted to 8.5;

[0114] (3) coating to form a conductive layer: coating the graphene dispersion prepared in step (2) on the surface of the pre-washed substrate in step (1) to form a conductive layer for direct electroplating; the coating is selected from spraying, and the film thickness of the graphene dispersion liquid sprayed on the surface of the substrate is 0.5 μm, and the spraying and drying are repeated multiple times, and finally the dried conductive layer is formed; the drying includes: drying the graphene dispersion coated insulating substrate in the form of self-rotation and revolution at the same time, the drying temperature is 70°C, the self-rotation speed is 650 rpm, and the revolution speed is 850 rpm, the self-rotation is performed with a straight line passing through the geometric center of the insulating substrate and perpendicular to the plane of the insulating substrate as the axis, and the revolution is performed with a line segment extending outward from the geometric center of the insulating substrate along the plane of the insulating substrate as the radius, and the drying time is 10 min.

[0115] In this embodiment, the thickness-diameter ratio of the insulating substrate and its pore structure is 20:1.

[0116] Comparative Example 1

[0117] This comparative example is based on Example 1, and the drying method in step (3) is changed to natural drying at room temperature 25°C. The other embodiments of this comparative example are the same as Example 1.

[0118] The conductive layer of the substrate pore structure prepared in this comparative example is electroplated, and the current density of the electroplating is 2 A / dm 2 , and the electroplating time is 30 min. After the electroplating is completed, it is found that more than 70% of the pore structures on the substrate are blocked.

[0119] Comparative Example 2

[0120] This comparative example is based on Example 1, and the revolution of the substrate in the drying step in step (3) is removed. The other embodiments of this comparative example are the same as Example 1.

[0121] Experimental Example 1

[0122] In order to better illustrate the technical effect brought by the surface treatment effect of the present application, the conductive layers prepared in Examples 1-11 and Comparative Examples are electroplated with copper, and the electroplating conditions are: the current density of the electroplating is 2 A / dm 2 , and the electroplating time is 30 min. The related properties of the electroplated layer are tested, and the results are shown in the following table:

[0123]

[0124]

[0125] As can be seen from the above table, the full plating rate of the pore metallized substrate prepared by the self-rotation and revolution method is significantly higher than that of the substrate prepared without the self-rotation and revolution method.

[0126] The above merely describes preferred embodiments of the present application, and is not intended to limit the present application in any form. Although the present application has been disclosed with the preferred embodiments as above, it is not intended to limit the present application, and any person skilled in the art can make some changes or modifications to the above-mentioned technical content with the above-mentioned prompt without departing from the technical solution of the present application, and any simple modification, equivalent change and modification made to the above-mentioned embodiments according to the technical essence of the present application without departing from the technical solution of the present application still belong to the scope of the present application.

Claims

1. A method for forming a film within a hole in a substrate, the substrate comprising a surface and a hole structure recessed in the surface, characterized in that, The application relates to a method for preparing a conductive layer on an insulating substrate, comprising the following steps: (1) pre-treating the surface and hole structure of the insulating substrate; the pre-treatment comprises pre-washing and / or charge adjustment; (2) coating a prepared graphene dispersion liquid on the surface and hole structure of the insulating substrate which has been subjected to charge adjustment in step (1), and simultaneously applying rotary drying with different radii and speeds to the insulating substrate, so that the graphene forms a conductive layer for metal electroplating; (3) electroplating the insulating substrate with the conductive layer prepared in step (2). The drying process comprises: simultaneously drying the graphene dispersion liquid coated insulating substrate in the form of rotation and revolution, the drying temperature is 40-100 DEG C, the rotation speed is 600-800 rpm, the revolution speed is 850-1200 rpm, the rotation is performed along a straight line which passes through any point on the plane of the insulating substrate and is perpendicular to the plane of the insulating substrate, and the revolution is performed along a line segment which extends outward from the geometric center of the insulating substrate along the plane of the insulating substrate. The graphene dispersion liquid comprises water, graphene, a binding aid and a water-soluble conductive polymer, the mass ratio of the graphene, the binding aid and the water-soluble conductive polymer is 1:0.05-20:0.01-20, the mass fraction of the graphene in the graphene dispersion liquid is 0.05-10%, the binding aid enhances the covalent connection between the conductive layer and the electroplated metal during the electroplating process, and simultaneously interacts with the groups on the surface and hole structure of the pre-treated insulating substrate; the thickness-diameter ratio of the substrate and the hole structure thereof is 0.5-20:

1. The graphene dispersion liquid is prepared by the following method: dissolving the binding aid and the water-soluble conductive polymer in deionized water to form a mixed liquid, then adding the graphene into the mixed liquid, and treating the graphene dispersion liquid by a physical method; the pH value of the graphene dispersion liquid is 3-12; the average layer number of the graphene in the graphene dispersion liquid is not more than 10. The water-soluble conductive polymer is selected from one or more of water-soluble polyaniline, water-soluble polythiophene and polyepoxy chloropropane quaternary ammonium salt. The binding aid is selected from one or more of polyvinyl alcohol, polyvinyl pyrrolidone, polyethylene imine, polyethylene glycol, polyacrylate, water-based polyurethane, water-based epoxy, polymaleic anhydride, polyacrylic acid, polymethacrylic acid, polystyrene sulfonic acid, polyvinyl sulfonic acid, polyvinyl phosphoric acid, polyvinyl amine and polyvinyl pyridine. The physical method is selected from one or both of grinding and ultrasonic treatment. The average layer number of the graphene is 1-5 layers. The mass ratio of the graphene, the binding aid and the water-soluble conductive polymer is 1:0.1-3:0.05-3; the mass fraction of the graphene in the graphene dispersion liquid is 0.1-5%.

2. The method according to claim 1, wherein The rotation speed of the grinding is 100-5000 rpm; the grinding time is 1 min-3 h; the ultrasonic frequency is 25-100 kHz; and the ultrasonic time is 30 min-24 h.

3. The method according to claim 1, wherein The rotation speed of the grinding is 1000-3000 rpm.

4. The method according to claim 1, wherein The grinding time is 10 min-1 h.

5. The method according to claim 2, wherein The ultrasonic frequency is 40-75 kHz.

6. The method according to claim 5, wherein The ultrasonic time is 4-12 h.

7. The method according to claim 5, wherein ​ 8. The method according to claim 5, wherein ​ 9. The method according to claim 5, wherein ​ 10. The method according to claim 1, wherein In step (2), the rotation is performed around a straight line passing through the geometric center of the insulating substrate and perpendicular to the plane of the insulating substrate.

11. The method according to any one of claims 1 to 10, wherein In step (1), the substrate is selected from a hydrophilic material or a non-hydrophilic material, wherein the non-hydrophilic material is pre-treated to make the surface and / or pore structure hydrophilic; and the charge adjustment comprises: subjecting the surface and / or pore structure of the substrate to plasma treatment, treating the surface and / or pore structure of the substrate with a cationic surfactant or an anionic surfactant, or rubbing the surface and / or pore structure of the substrate to make the surface and / or pore structure of the substrate positively or negatively charged.

12. The method according to claim 11, wherein The hydrophilic material includes polyamide, polyvinyl acetate, epoxy resin, acrylate, or a composite material thereof.

13. The method according to claim 11, wherein The non-hydrophilic material includes polyimide, polycarbonate, polylactic acid, polyurethane, polycaprolactone, polymethyl methacrylate, polyhydroxyethyl methacrylate, poly-β-hydroxybutyric acid, polybutylene terephthalate, polyethylene terephthalate, poly-2,6-naphthalene diacid diethylene glycol, polystyrene, polypropylene, polyethylene, poly-1-butene, poly-4-methyl-1-pentene, or a composite material thereof.

14. The method according to claim 11, wherein The substrate is selected from an epoxy resin / glass fiber composite, polyimide, polyethylene terephthalate, polyimide / glass fiber composite, or acrylate.

15. The method according to claim 11, wherein When the substrate is a hydrophilic material, the pre-washing comprises: ultrasonic cleaning the substrate with a 1% NaOH solution, and the pre-washing time is 0.5-5 min.

16. The method according to claim 11, wherein When the substrate is a non-hydrophilic material, the pre-washing comprises: immersing the substrate in a 10% NaOH solution for 20-40 min, then removing the alkali solution and drying, so that the surface of the treated substrate is a hydrophilic surface.

17. The method according to any one of claims 1 to 10, wherein In step (2), the coating comprises immersion, blade coating, or spraying; the immersion comprises: immersing the substrate in an ultrasonically dispersed graphene dispersion liquid, and the immersion time is 5 s-5 min; the blade coating comprises: using an ultrasonically dispersed graphene dispersion liquid to perform blade coating on the surface of the substrate, and the film thickness of the blade coating is 0.05-100 μm; and the spraying comprises: using an ultrasonically dispersed graphene dispersion liquid to perform spraying on the surface of the substrate, and the film thickness of the spraying is 0.05-100 μm.

18. The method according to claim 17, wherein The blade coating or spraying is repeated multiple times on the substrate.

19. The method according to claim 17, wherein The immersion time is 30-60 s.

20. The method according to claim 17, wherein The film thickness of the blade coating is 0.1-10 μm.

21. The method according to claim 17, wherein The film thickness of the spraying is 0.1-10 μm.

22. The method according to claim 17, wherein The coating is stopped when the surface resistance of the substrate is lower than 100 Ω.

23. The method according to claim 17, wherein The coating is stopped when the surface resistance of the substrate is lower than 20 Ω.

24. Use of the method for forming a film in a hole of a substrate according to any one of claims 1-23 in electroplating technology.

25. The use according to claim 24, characterized in that, Metallization of hard boards, flexible circuit boards, and non-metallic surfaces.

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