Modified graphene coating solution for direct electroplating and preparation method and application thereof

Abstract

The application provides a modified graphene coating solution for direct electroplating and a preparation method and application thereof. The modified graphene coating solution for direct electroplating comprises edge-modified graphene, a high-molecular polymer, a condensation agent, a surface energy aid, an ultradispersion agent, a PH regulator and water, wherein the surface energy aid comprises a non-ionic gemini surfactant and an anionic surfactant. The modified graphene coating solution for direct electroplating has good dispersing capacity and good conductivity, and can be well adapted to the direct electroplating process of a printed circuit board.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of circuit board processing, in particular to a modified graphene coating solution for direct electroplating, a preparation method and application thereof. BACKGROUND

[0002] Hole metallization is one of the most important processes in printed circuit board manufacturing, and is also an important way to realize the interconnection between layers of multi-layer circuit boards. The traditional chemical copper plating process is poor in combination with high-frequency and high-speed materials, which makes it prone to poor backlight and even copper layer peeling, resulting in the risk of poor copper conduction in the hole in the subsequent process. In addition, the use of formaldehyde, EDTA, potassium sodium tartrate and other chemicals poses environmental hazards, and the wastewater treatment is complex, with great environmental pressure. Direct electroplating technology, as a new hotspot in hole metallization process, has the characteristics of low consumption, high efficiency and small environmental impact compared with chemical copper plating. The current direct electroplating technology mainly uses conductive carbon black, conductive graphite or graphene to achieve hole conduction by adsorption in the circuit board hole. After coating, post-processes such as micro-etching and electroplating are carried out. The use of conductive carbon black, conductive graphite or graphene as conductive medium to replace chemical copper plating has its technical limitations. Based on the material properties of the conductive medium used, the conductive ability is much lower than that of the chemical copper layer. To improve the conductive performance of the coating solution, it is necessary to increase the content of conductive agents in the coating solution or to go through multiple treatments, which leads to an increase in the thickness of the coating film and uneven dispersion of the conductive medium on the hole wall. In practical applications, the electroplated copper seed cannot penetrate the coating film and combine with the glass fiber, resin and inner copper layer on the hole wall due to poor combination ability, which leads to poor conduction between layers of the circuit board (as shown in Figure 12 ). After component soldering, the surface tension of the solder will peel off the copper layer in the hole due to high-temperature solder cooling (as shown in Figure 13 ). In other words, direct electroplating technology can better meet the application of medium and low-end products, but it cannot universally replace the chemical copper plating process, especially for high-aspect-ratio printed circuit boards.

[0003] The conductive coating solution (such as CN109811382A, CN113207243A, etc.) used in the general direct electroplating technology at present has graphene oxide as an outer layer wrapping an inner layer of graphene or has graphene oxide as a precursor to be reduced to graphene as a conductive additive dispersed in the solution. Although the graphene oxide has good water solution dispersibility, the conjugated structure of the graphene oxide is destroyed due to easy oxidation, and the graphene oxide contains irreversible lattice defects, reduces the unique electronic properties, and loses the conductivity. That is to say, although the conjugated structure and the electrical conductivity of the graphene oxide can be partially reduced through chemical reduction, thermal reduction or photocatalytic reduction, a large number of defects and oxygen-containing groups still exist in the reduced graphene oxide, and the conductivity is still poor. SUMMARY

[0004] The purpose of the present application is to overcome the deficiencies in the prior art, provide a modified graphene coating solution for direct electroplating with good dispersing ability and conductivity, which can better adapt to the direct electroplating process of printed circuit boards and its preparation method and application.

[0005] The purpose of the present application is achieved by the following technical solutions:

[0006] A modified graphene coating solution for direct electroplating, comprising edge-modified graphene, a high molecular polymer, a condensing agent, a surface energy additive, an ultra-dispersant, a pH adjuster and water.

[0007] The surface energy additive comprises a non-ionic gemini surfactant and an anionic surfactant.

[0008] In one embodiment, the modified graphene coating solution for direct electroplating comprises the following components by mass:

[0009]

[0010] In one embodiment, the edge-modified graphene comprises edge-carboxylated graphene.

[0011] The high molecular polymer comprises at least one of an amino-terminated hyperbranched polyester, an amino-terminated hyperbranched polyamide and a polyallylamine.

[0012] In one embodiment, the edge-carboxylated graphene has a particle size of 0.5-1.5 um and a layer number of 1-15 layers.

[0013] In one embodiment, the amino-terminated hyperbranched polyester has a molecular weight of 800-1200 and an amino group number of 7-11.

[0014] In one embodiment, the end-amino hyperbranched polyamide has a molecular weight of 800-1200 and an amino group number of 7-11.

[0015] In one embodiment, the polyallylamine has a molecular weight of 1500-5000.

[0016] In one embodiment, the edge-modified graphene includes edge-hydroxylated graphene.

[0017] The high-molecular polymer includes at least one of an end-carboxyl hyperbranched polyester, an end-carboxyl hyperbranched polyamide, and a double-end carboxyl polyethylene glycol.

[0018] In one embodiment, the edge-hydroxylated graphene has a particle size of 0.5-1.5 um and a layer number of 1-15.

[0019] In one embodiment, the end-carboxyl hyperbranched polyester has a molecular weight of 950-1200 and a carboxyl group number of 6-8.

[0020] In one embodiment, the end-carboxyl hyperbranched polyamide has a molecular weight of 950-1200 and a carboxyl group number of 6-8.

[0021] In one embodiment, the end-carboxyl polyethylene glycol has a molecular weight of 600-1000.

[0022] In one embodiment, the condensing agent is EDC·HCl or DCC.

[0023] In one embodiment, the hyperdispersant is at least one of polyvinylpyrrolidone, polyoxyethylene-polypropylene copolymer, polystyrene block polyethylene oxide, and polyoxyethylene stearate.

[0024] In one embodiment, the PH regulator is ammonia water or sodium carbonate solution.

[0025] In one embodiment, the non-ionic gemini surfactant is at least one of N,N'-bis(hydroxyethyl)-N,N'-bis(ethoxy)dodecylamide, N,N'-dialkyl-N,N'-bis[2-(lactose amino acid)-methylene]adipoyldiamine, Surfynol 420, Surfynol 440, Surfynol 465, and Surfynol 485W.

[0026] In one embodiment, the anionic surfactant is at least one of sodium dodecyl sulfate, sodium dodecylbenzenesulfonate, and potassium dodecyl phosphate.

[0027] A preparation method of a modified graphene coating solution for direct electroplating, for preparing the modified graphene coating solution for direct electroplating of any of the preceding embodiments, the preparation method of the modified graphene coating solution for direct electroplating comprising the following steps:

[0028] Obtaining edge-modified graphene and a high-molecular polymer;

[0029] Adding the edge-modified graphene and the high-molecular polymer into water for ultrasonic homogenization to obtain a homogenized liquid;

[0030] Adding a condensation agent to the homogenized liquid for mixing homogenization;

[0031] Drying the homogenized liquid after mixing homogenization to obtain modified graphene particles;

[0032] Adding the modified graphene particles, a surface energy aid, and a hyperdispersant into water for homogenization dispersion to obtain a dispersion liquid;

[0033] Adding a pH adjuster and water to the dispersion liquid for dilution adjustment to obtain the modified graphene coating solution for direct electroplating.

[0034] Application of the modified graphene coating solution for direct electroplating, applying the modified graphene coating solution for direct electroplating of any of the preceding embodiments to hole metallization of a printed circuit board.

[0035] Compared with the prior art, the present application has at least the following advantages:

[0036] 1. The modified graphene coating solution for direct electroplating of the present application enables the edge-modified graphene to serve as a conductive aid of the modified graphene coating solution for direct electroplating, and has a complete conjugated sp2 network compared with graphene oxide, so that the surface of the conductive layer formed by the modified graphene coating solution for direct electroplating on the hole wall surface of a printed circuit board is more complete, and has the characteristics of excellent dispersion stability and excellent conductivity, so that excellent conductivity can be achieved with less solid content of nano-modified graphene particles;

[0037] 2. The modified graphene coating solution for direct electroplating of the present application uses water as a dispersion medium, replacing organic solvents, avoiding the problems of high cost, high boiling point, and difficulty in removal of organic solvents, reducing the consumption of raw materials, and making the modified graphene coating solution for direct electroplating free of harmful substances, reducing the operation requirements of the modified graphene coating solution for direct electroplating, and simplifying the operation, while facilitating the maintenance of the tank solution on the production line;

[0038] 3. The modified graphene coating solution for direct electroplating of the present application uses a PH adjuster to achieve deprotonation of the modified graphene coating solution for direct electroplating, thereby enhancing the electrostatic interaction between the edge-modified graphene, reducing the mutual interaction of the edge-modified graphene, and effectively stabilizing the dispersion stability of the edge-modified graphene in the modified graphene coating solution for direct electroplating;

[0039] 4. The modified graphene coating solution for direct electroplating of the present application uses a high molecular polymer to disperse the edge-modified graphene, wherein the high molecular polymer has little effect on the viscosity of the edge-modified graphene coating solution for direct electroplating, making the solution have good fluidity, improving the through-hole capability of the bath solution for preparing high aspect ratio circuit boards, and the molecular chain of the high molecular polymer is not easy to entangle, and at the same time has many fulcrums and many hydrophilic functional group end groups to combine with graphene particles by electrostatic force, or further cooperate with a condensing agent to directly modify the edge-modified graphene, increase the steric hindrance between the edge-modified graphene, and better maintain the stable dispersion of the edge-modified graphene, achieving the effect of improving the dispersibility and solubility;

[0040] 5. The modified graphene coating solution for direct electroplating of the present application makes the surface energy aid include a non-ionic gemini surfactant and an anionic surfactant, effectively reduces the critical micelle concentration, reduces the total amount of surface energy aid, and still maintains excellent physical properties of graphene, enhances the wetting ability of the edge-modified graphene in water, is conducive to the rapid infiltration and dispersion of the edge-modified graphene, and is conducive to reducing the stirring time or stirring speed during the dispersion process of the edge-modified graphene, and reduces the air bubbles brought in during the coating of the circuit board, is conducive to increasing the dispersion stability of the edge-modified graphene, and makes the edge-modified graphene in the conductive layer formed on the inner wall of the hole by the modified graphene coating solution for direct electroplating be uniformly dispersed, and makes the conductive layer be light and thin in thickness. BRIEF DESCRIPTION OF DRAWINGS

[0041] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments. It should be understood that the following drawings only show some embodiments of the present application, and therefore should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can also be obtained without creative labor on the basis of these drawings.

[0042] Figure 1 Flow chart for the preparation method of the modified graphene coating solution for direct electroplating of an embodiment of the present application;

[0043] Figure 2 Particle size distribution graph of the modified graphene coating solution of Example 1;

[0044] Figure 3 Particle size distribution graph of the modified graphene coating solution of Example 1;

[0045] Figure 4 Particle size distribution graph of the modified graphene coating solution of Example 3;

[0046] Figure 5 Particle size distribution graph of the modified graphene coating solution of Example 4;

[0047] Figure 6 Particle size distribution graph of the modified graphene coating solution of Example 5;

[0048] Figure 7 SEM image of the coating layer formed on the hole wall of the circuit board by the modified graphene coating solution of Example 1;

[0049] Figure 8 SEM image of the coating layer formed on the hole wall of the circuit board by the modified graphene coating solution of Example 2;

[0050] Figure 9 SEM image of the coating layer formed on the hole wall of the circuit board by the modified graphene coating solution of Example 3;

[0051] Figure 10 SEM image of the coating layer formed on the hole wall of the circuit board by the modified graphene coating solution of Example 4;

[0052] Figure 11 SEM image of the coating layer formed on the hole wall of the circuit board by the modified graphene coating solution of Example 5;

[0053] Figure 12 Schematic diagram of the non-conduction between the layers of the circuit board;

[0054] Figure 13 Schematic diagram of the surface tension of the solder peeling off the copper layer in the hole. DETAILED DESCRIPTION

[0055] In order to facilitate the understanding of the present application, the present application will be described more fully below with reference to the accompanying drawings. The preferred embodiments of the present application are shown in the drawings. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, the purpose of providing these embodiments is to make the disclosure of the present application more thorough and comprehensive.

[0056] It should be understood that when an element as a means plus function is recited in the claims, any means plus function clause is intended to cover structures as well as materials that do not solely function in the recited manner and are not solely intended to achieve the recited function. The term "consisting of" is intended to mean the listed items are the only integral elements of the embodiment. The term "consisting essentially of" means the permitted elements of a claim can be integral as well as other integral elements not recited, that do not materially change the basic and novel properties of the claimed application. The use of the term "or" in the context of the term "comprising" is intended to mean an open transition such that it covers single or double options. The use of the term "comprising" is intended to mean the recited elements are integral, but the application is not limited to those elements. The terms "vertical", "horizontal", "left", "right", and similar terms are used for explanation only and are not intended to be limiting.

[0057] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the description herein is for describing particular embodiments only and is not intended to be limiting. As used in this application, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0058] The present application provides a modified graphene coating solution for direct plating. In order to better understand the modified graphene coating solution for direct plating of the present application, the following further explains the modified graphene coating solution for direct plating of the present application:

[0059] The modified graphene coating solution for direct plating of an embodiment includes edge-modified graphene, a macromolecular polymer, a condensation agent, a surface energy aid, an ultra dispersant, a pH adjuster, and water, wherein the surface energy aid includes a non-ionic gemini surfactant and an anionic surfactant.

[0060] The modified graphene coating solution for direct plating described above makes the edge-modified graphene serve as a conductive aid for the modified graphene coating solution for direct plating, has a complete conjugated structure sp2 network compared to graphene oxide, makes the conductive layer formed by the modified graphene coating solution for direct plating on the surface of the hole wall of the printed circuit board more complete, and has the characteristics of excellent dispersion stability and excellent conductivity, so that excellent conductivity can be achieved with less solid content of nano-modified graphene particles. Water is used as a dispersion medium to replace organic solvents, avoiding the problems of high cost, high boiling point and difficulty in removal of organic solvents, reducing the consumption of raw materials, and making the modified graphene coating solution for direct plating free of harmful substances, reducing the operation requirements of the modified graphene coating solution for direct plating, and simplifying the operation, while facilitating the maintenance of the tank solution on the production line. The use of a pH adjuster achieves deprotonation of the modified graphene coating solution for direct plating, thereby enhancing the electrostatic interaction between the edge-modified graphene and reducing the interaction between the edge-modified graphene itself, effectively stabilizing the dispersion stability of the edge-modified graphene in the modified graphene coating solution for direct plating. A high molecular polymer is used to disperse the edge-modified graphene, wherein the high molecular polymer has little effect on the viscosity of the edge-modified graphene coating solution for direct plating, making the solution have good fluidity, improving the through-hole capability of the tank solution for preparing high aspect ratio circuit boards, and the molecular chain of the high molecular polymer is not easily entangled, while having many hydrophilic functional group end groups to combine with graphene particles by electrostatic force, or further modifying the edge-modified graphene with a condensing agent to increase the steric hindrance between the edge-modified graphene, better maintaining the stable dispersion of the edge-modified graphene, achieving the effect of improving dispersion and solubilization. The surface energy aid includes non-ionic gemini surfactant and anionic surfactant, effectively reducing the critical micelle concentration, reducing the total amount of surface energy aid, making the graphene still maintain excellent physical properties, enhancing the wettability of the edge-modified graphene in water, facilitating the rapid infiltration and dispersion of the edge-modified graphene, and reducing the stirring time or stirring speed during the dispersion process of the edge-modified graphene, and reducing the air bubbles brought in during the coating of the circuit board, which is beneficial to increasing the dispersion stability of the edge-modified graphene, and making the dispersion of the edge-modified graphene in the conductive layer formed by the modified graphene coating solution for direct plating on the inner wall of the hole uniform, and making the thickness of the conductive layer uniform.

[0061] In one embodiment, the modified graphene coating solution for direct electroplating comprises the following components by mass fraction: edge-modified graphene 1-10 parts; high molecular polymer 1.0-7.5 parts; condensing agent 2.0-4.0 parts; surface energy aid 0.1-1.5 parts; hyperdispersant 0.5-1.8 parts; PH regulator 0.05-0.1 parts; and water 90-95 parts. It can be understood that when the edge-modified graphene 1-10 parts, high molecular polymer 1.0-7.5 parts, condensing agent 2.0-4.0 parts, surface energy aid 0.1-1.5 parts, hyperdispersant 0.5-1.8 parts, PH regulator 0.05-0.1 parts, and water 90-95 parts are combined to form the modified graphene coating solution for direct electroplating, the modified graphene coating solution for direct electroplating has high conductivity, and the high molecular polymer, surface energy aid, hyperdispersant, and PH regulator play a good promoting role in the stable dispersion of the edge-modified graphene, thereby effectively ensuring the conductivity and dispersion stability of the modified graphene coating solution for direct electroplating.

[0062] In one embodiment, the edge-modified graphene comprises edge-carboxylated graphene. Further, the high molecular polymer comprises at least one of an amino-terminated hyperbranched polyester, an amino-terminated hyperbranched polyamide, and a polyallylamine. It can be understood that when the edge-modified graphene comprises edge-carboxylated graphene, and the high molecular polymer comprises at least one of an amino-terminated hyperbranched polyester, an amino-terminated hyperbranched polyamide, and a polyallylamine, the edge-modified graphene and the high molecular polymer can undergo an amidation reaction, the high molecular polymer is grafted to the periphery of the edge-modified graphene, thereby improving the water solubility of the edge-modified graphene and better ensuring the dispersion stability of the edge-modified graphene in the modified graphene coating solution for direct electroplating.

[0063] In one embodiment, the edge-carboxylated graphene has a particle size of 0.5-1.5 um and a layer number of 1-15 layers.

[0064] In one embodiment, the amino-terminated hyperbranched polyester has a molecular weight of 800-1200 and an amino group number of 7-11, so that the amino-terminated hyperbranched polyamide has a smaller effect on the viscosity of the modified graphene coating solution for direct electroplating, and the amino group number of the amino-terminated hyperbranched polyamide is 7-11, so that the amino-terminated hyperbranched polyamide forms a denser network structure with the edge-modified graphene, thereby improving the dispersion stability of the edge-modified graphene.

[0065] In one of the embodiments, the molecular weight of the terminal amino hyperbranched polyester is 800-1200, and the amino group number is 7-11. It can be understood that the terminal amino hyperbranched polyester has a molecular weight of 800-1200, which makes the terminal amino hyperbranched polyester have a smaller influence on the viscosity of the modified graphene coating solution for direct electroplating, and the amino group number of the terminal amino hyperbranched polyester is 7-11, which makes the terminal amino hyperbranched polyester form a more dense network structure with the edge-modified graphene, thereby improving the dispersion stability of the edge-modified graphene.

[0066] In one of the embodiments, the molecular weight of the polyallylamine is 1500-5000, which makes the polyallylamine have a smaller influence on the viscosity of the modified graphene coating solution for direct electroplating, and makes the polyallylamine form a more dense network structure with the edge-modified graphene.

[0067] In one of the embodiments, the edge-modified graphene includes edge-hydroxylated graphene, and further, the high molecular polymer includes at least one of a terminal carboxyl hyperbranched polyester, a terminal carboxyl hyperbranched polyamide, and a double-terminal carboxylic acid polyethylene glycol. It can be understood that the edge-hydroxylated graphene has a lower preparation difficulty and a lower cost, and in order to further reduce the cost of the modified graphene coating solution for direct electroplating, the edge-hydroxylated graphene is further added to the modified graphene coating solution for direct electroplating, and the high molecular polymer further includes at least one of a terminal carboxyl hyperbranched polyester, a terminal carboxyl hyperbranched polyamide, and a double-terminal carboxylic acid polyethylene glycol, so that an esterification reaction can occur between the edge-hydroxylated graphene and the high molecular polymer, so that the high molecular polymer is grafted on the periphery of the edge-modified graphene, thereby improving the water solubility of the edge-modified graphene, and better ensuring the dispersion stability of the edge-modified graphene in the modified graphene coating solution for direct electroplating.

[0068] In one embodiment, the edge-modified graphene includes edge-hydroxylated graphene and edge-carboxylated graphene, and the mass ratio of the edge-hydroxylated graphene to the edge-carboxylated graphene is 0.5-0.9. It can be understood that when the edge-modified graphene includes both edge-carboxylated graphene and edge-hydroxylated graphene, the esterification reaction between the edge-carboxylated graphene and the edge-hydroxylated graphene will further intensify the connection and aggregation of the edge-carboxylated graphene and the edge-hydroxylated graphene when the carboxyl group is activated, which will affect the dispersibility of the edge-modified graphene. Therefore, the edge-hydroxylated graphene and the edge-carboxylated graphene are generally not selected to be dispersed in the high-molecular polymer to prepare the modified graphene coating solution for direct electroplating. However, based on the fact that the edge-carboxylated graphene is acidic when dissolved in water, the content of the edge-hydroxylated graphene is relatively high, which will cause the modified graphene coating solution for direct electroplating to be acidic and affect the subsequent electroplating. Therefore, in order to reduce the cost of the modified graphene coating solution for direct electroplating and to reduce the influence of the modified graphene coating solution for direct electroplating on electroplating, the edge-hydroxylated graphene and the edge-carboxylated graphene are simultaneously used to be dispersed in the high-molecular polymer to prepare the modified graphene coating solution for direct electroplating. Since the high-molecular polymer includes at least one of the amino-terminated hyperbranched polyester, the amino-terminated hyperbranched polyamide and the polyallylamine, when the edge-carboxylated graphene is activated by using a condensing agent, the reactivity of the edge-carboxylated graphene with the amino-terminated hyperbranched polyester, the amino-terminated hyperbranched polyamide and the polyallylamine is much higher than the esterification reaction between the edge-carboxylated graphene and the edge-hydroxylated graphene. That is, the mass ratio of the edge-hydroxylated graphene to the edge-carboxylated graphene is appropriate, which further enables the periphery of the edge-carboxylated graphene to be fully coated by the high-molecular polymer to block the contact reaction between the edge-carboxylated graphene and the edge-hydroxylated graphene. At this time, the high-molecular polymer will further react with the edge-hydroxylated graphene, which ensures the dispersion stability of the edge-hydroxylated graphene.

[0069] In one embodiment, the high-molecular polymer includes at least one of the amino-terminated hyperbranched polyester, the amino-terminated hyperbranched polyamide and the polyallylamine, and the high-molecular polymer further includes at least one of the carboxyl-terminated hyperbranched polyester, the carboxyl-terminated hyperbranched polyamide and the double-end carboxylic acid polyethylene glycol, and the mass ratio of the former high-molecular polymer to the latter high-molecular polymer is 1-1.5. It can be understood that the former high-molecular polymer is at least one of the amino-terminated hyperbranched polyester, the amino-terminated hyperbranched polyamide and the polyallylamine, and the latter high-molecular polymer is at least one of the carboxyl-terminated hyperbranched polyester, the carboxyl-terminated hyperbranched polyamide and the double-end carboxylic acid polyethylene glycol, which better realizes the graft dispersion of the edge-carboxylated graphene and the edge-hydroxylated graphene, that is, better ensures the dispersion stability of the edge-carboxylated graphene and the edge-hydroxylated graphene.

[0070] In one of the embodiments, the purity of the edge carboxylated graphene and the edge hydroxylated graphene is higher than 99%.

[0071] In one of the embodiments, the particle size of the edge hydroxylated graphene is 0.5um-1.5um, and the layer number is 1-15.

[0072] In one of the embodiments, the molecular weight of the end carboxylated hyperbranched polyester is 950-1200, and the carboxyl number is 6-8, which can fully esterify with the edge hydroxylated graphene to improve the dispersion stability of the edge modified graphene.

[0073] In one of the embodiments, the molecular weight of the end carboxylated hyperbranched polyester is 950-1200, and the carboxyl number is 6-8, which can fully esterify with the edge hydroxylated graphene to improve the dispersion stability of the edge modified graphene.

[0074] In one of the embodiments, the molecular weight of the end carboxylated hyperbranched polyester is 950-1200, and the carboxyl number is 6-8, which can fully esterify with the edge hydroxylated graphene to improve the dispersion stability of the edge modified graphene.

[0075] In one of the embodiments, the condensing agent is EDC·HCl or DCC. It should be noted that EDC·HCl is 1-ethyl-(3-dimethylaminopropyl) carbodiimide hydrochloride, and the molecular formula is C8H 17 N3·HCl; DCC is N,N'-dicyclohexyl carbodiimide, and the molecular formula is C 13 H 22 N2, which can better activate the carboxyl group and better ensure the full reaction of the edge modified graphene and the high molecular polymer in the modified graphene coating solution for direct electroplating, so that the high molecular polymer can be better grafted on the edge modified graphene, and then the dispersion of the modified graphene coating solution for direct electroplating is improved while ensuring the conductivity of the modified graphene coating solution for direct electroplating.

[0076] In one of the embodiments, the hyperdispersant is at least one of polyvinylpyrrolidone, polyoxyethylene-polypropylene copolymer, polystyrene block polyethylene oxide, and polyoxyethylene stearate, which can better realize the effect of promoting dispersion of the edge modified graphene under the action of the high molecular polymer.

[0077] In one of the embodiments, the PH regulator is ammonia water or sodium carbonate solution, both of which can deprotonate the modified graphene coating solution for direct electroplating, thereby enhancing the electrostatic effect of the edge-modified graphene and improving the dispersion stability of the edge-modified graphene in the modified graphene coating solution for direct electroplating.

[0078] In one of the embodiments, the mass ratio of the non-ionic gemini surfactant and the anionic surfactant is 2-4, which better realizes the uniform dispersion of the edge-modified graphene in the modified graphene coating solution for direct electroplating and better ensures the uniform thickness of the conductive layer formed by the modified graphene coating solution for direct electroplating on the inner wall of the hole.

[0079] In one of the embodiments, the non-ionic gemini surfactant is at least one of N,N'-bis(hydroxyethyl)-N,N'-bis(ethoxy)dodecylamide, N,N'-dialkyl-N,N'-bis[2-(lactose amino acid)-methylene]adipoyldiamine, Surfynol 420, Surfynol 440, Surfynol 465 and Surfynol 485W, which better ensures the uniform dispersion of the edge-modified graphene in the modified graphene coating solution for direct electroplating and better ensures the uniform thickness of the conductive layer formed by the modified graphene coating solution for direct electroplating on the inner wall of the hole.

[0080] In one of the embodiments, the anionic surfactant is at least one of sodium dodecyl sulfate, sodium dodecylbenzenesulfonate and potassium dodecyl phosphate, which better ensures the uniform dispersion of the edge-modified graphene in the modified graphene coating solution for direct electroplating and better ensures the uniform thickness of the conductive layer formed by the modified graphene coating solution for direct electroplating on the inner wall of the hole.

[0081] The application also provides a preparation method of the modified graphene coating solution for direct electroplating, which is used to prepare the modified graphene coating solution for direct electroplating in any of the above embodiments. The preparation method of the modified graphene coating solution for direct electroplating comprises the following steps: obtaining edge-modified graphene and a high molecular polymer; adding the edge-modified graphene and the high molecular polymer into water to perform ultrasonic homogenization operation to obtain a homogenized liquid; adding a condensing agent into the homogenized liquid to perform mixing homogenization treatment; drying the homogenized liquid after the mixing homogenization treatment to obtain modified graphene particles; adding the modified graphene particles, a surface energy aid and a hyperdispersant into water to perform homogenization dispersion operation to obtain a dispersion liquid; adding a PH regulator and water into the dispersion liquid to perform dilution adjustment operation to obtain the modified graphene coating solution for direct electroplating.

[0082] The preparation method of the modified graphene coating solution for direct electroplating provided by the application has the advantages that: the edge-modified graphene is obtained for preparing the modified graphene coating solution for direct electroplating, and the high-molecular polymer is used to promote the dispersion stability of the edge-modified graphene in the modified graphene coating solution for direct electroplating, so that the modified graphene coating solution for direct electroplating with good conductivity and dispersion stability can be obtained. Then, the edge-modified graphene is ultrasonically homogenized with part of the high-molecular polymer, so that the dispersion uniformity of the edge-modified graphene is better realized, and the hydrophilic modification of the edge-modified graphene is improved. Then, the edge-modified graphene is ultrasonically homogenized with part of the high-molecular polymer, so that the dispersion uniformity of the edge-modified graphene is better realized, and the hydrophilic modification of the edge-modified graphene is improved. In this way, the dispersion stability of the edge-modified graphene in the modified graphene coating solution for direct electroplating is better ensured. Then, the homogenized liquid containing the edge-modified graphene is dried to remove the condensing agent and other impurities, so that the impurities introduced into the modified graphene coating solution for direct electroplating are reduced, the influence of the modified graphene coating solution for direct electroplating on subsequent electroplating is reduced, and the dispersion stability of the edge-modified graphene in the modified graphene coating solution for direct electroplating is better ensured by using the surface energy additive, the hyperdispersant and the PH regulator.

[0083] In order to better understand the preparation method of the modified graphene coating solution for direct electroplating provided by the application, the preparation method of the modified graphene coating solution for direct electroplating provided by the application is further explained as follows:

[0084] The preparation method of the modified graphene coating solution for direct electroplating provided by an embodiment includes the following steps:

[0085] In S100, the edge-modified graphene and the high-molecular polymer are obtained. It can be understood that the edge-modified graphene has good conductivity, but the dispersion of the edge-modified graphene is poor. Therefore, in order to realize that the modified graphene coating solution for direct electroplating has good conductivity, the edge-modified graphene is obtained for preparing the modified graphene coating solution for direct electroplating, and the high-molecular polymer is used to promote the dispersion stability of the edge-modified graphene in the modified graphene coating solution for direct electroplating, so that the modified graphene coating solution for direct electroplating with good conductivity and dispersion stability can be obtained.

[0086] S200, the edge-modified graphene and the high molecular polymer are added to water for ultrasonic homogenization to obtain a homogenized liquid. It can be understood that the dispersibility of the edge-modified graphene is poor, and if the edge-modified graphene is directly added to water for dispersion, the edge-modified graphene is prone to agglomeration, and it is difficult to achieve effective dispersion. If the edge-modified graphene and the high molecular polymer are allowed to react without sufficient uniform dispersion of the edge-modified graphene, the surface of the edge-modified graphene cannot be uniformly grafted with the high molecular polymer due to the high rate of amidation reaction, thereby affecting the hydrophilicity of the edge-modified graphene, that is, the dispersibility of the edge-modified graphene in water is affected. Therefore, in order to improve the dispersibility of the edge-modified graphene, part of the high molecular polymer is first mixed with the edge-modified graphene by ultrasonic homogenization, which is conducive to improving the hydrophilicity of the edge-modified graphene and better ensuring the dispersion stability of the edge-modified graphene in the modified graphene coating solution for direct electroplating.

[0087] S300, a condensing agent is added to the homogenized liquid for mixing and homogenization. It can be understood that the condensing agent is a carboxyl activator, and after the edge-modified graphene and the high molecular polymer are homogeneously dispersed, the carboxyl activator is added for carboxyl activation, and then the edge-carboxylated graphene and the high molecular polymer are allowed to react to modify the edge-carboxylated graphene, thereby improving the dispersion stability of the edge-carboxylated graphene.

[0088] S400, the homogenized liquid after mixing and homogenization is dried to obtain modified graphene particles. It can be understood that after the graft modification of the edge-modified graphene is realized, the homogenized liquid containing the edge-modified graphene is further dried to remove the condensing agent and other impurities, thereby reducing the introduction of impurities in the modified graphene coating solution for direct electroplating and better reducing the influence of the modified graphene coating solution for direct electroplating on subsequent electroplating.

[0089] S500, the modified graphene particles, the surface energy aid, and the hyperdispersant are added to water for homogenization to obtain a dispersion liquid. It can be understood that the addition of the surface energy aid and the hyperdispersant to the grafted edge-modified graphene is conducive to better improving the dispersion stability of the edge-modified graphene in the modified graphene coating solution for direct electroplating.

[0090] S600, a PH adjuster and water are added to the dispersion liquid for dilution and adjustment to obtain a modified graphene coating solution for direct electroplating. It can be understood that the PH adjuster is used to deprotonate the modified graphene coating solution for direct electroplating, thereby enhancing the electrostatic effect of the edge-modified graphene and improving the dispersion stability of the edge-modified graphene in the modified graphene coating solution for direct electroplating.

[0091] The preparation method of the modified graphene coating solution for direct electroplating, the edge-modified graphene for preparing the modified graphene coating solution for direct electroplating, and the polymer used to promote the dispersion stability of the edge-modified graphene in the modified graphene coating solution for direct electroplating, are all conducive to obtaining a modified graphene coating solution for direct electroplating with good conductivity and dispersion stability. Then, the partial polymer is first ultrasonically homogenized with the edge-modified graphene to improve the dispersion uniformity of the edge-modified graphene and the hydrophilic modification of the edge-modified graphene. Then, the partial polymer is again ultrasonically homogenized with the edge-modified graphene to further improve the dispersion uniformity of the edge-modified graphene and the hydrophilic modification of the edge-modified graphene. In this way, the dispersion stability of the edge-modified graphene in the modified graphene coating solution for direct electroplating is better ensured. Then, the homogenized liquid containing the edge-modified graphene is dried to remove the condensing agent and other impurities, thereby reducing the introduction of impurities into the modified graphene coating solution for direct electroplating and reducing the influence of the modified graphene coating solution for direct electroplating on subsequent electroplating. Furthermore, the surface energy aid, the hyperdispersant, and the PH regulator are used to disperse the edge-modified graphene in the modified graphene coating solution for direct electroplating, thereby better ensuring the dispersion stability of the edge-modified graphene in the modified graphene coating solution for direct electroplating.

[0092] It should be noted that if the surface energy aid, the hyperdispersant, and the PH regulator are added to the edge-modified graphene together with the polymer, or the surface energy aid, the hyperdispersant, and the PH regulator are used to initially disperse the edge-modified graphene, the amount of the polymer distributed on the periphery of the edge-modified graphene will be less, and the polymer cannot form a network coating structure on the periphery of the edge-modified graphene. The dispersion effect of the surface energy aid, the hyperdispersant, and the PH regulator on the edge-modified graphene is mainly achieved by improving the surface energy, which greatly affects the edge-modified graphene in the subsequent dispersion system. If dilution or other processes are performed subsequently, the dispersion system of the edge-modified graphene will be easily destroyed, i.e., the dispersion stability of the edge-modified graphene will be poor. If the polymer is first fully grafted on the periphery of the edge-modified graphene to form a network structure, the edge-modified graphene is less affected by the dispersion system due to the generation of chemical bonds, thereby better ensuring the dispersion stability of the edge-modified graphene in the modified graphene coating solution for direct electroplating.

[0093] In one of the embodiments, the step of adding the edge-modified graphene and the high-molecular polymer into water to perform the ultrasonic homogenization operation is the step of adding the edge-hydroxylated graphene and the edge-carboxylated graphene together with the first high-molecular polymer into water to perform the ultrasonic homogenization operation. Further, before the step of drying the homogenized liquid after the mixing homogenization treatment and after the step of adding the condensing agent into the homogenized liquid to perform the mixing homogenization treatment, the method for preparing the modified graphene coating solution for direct electroplating further comprises the step of adding the second high-molecular polymer into the homogenized liquid after the mixing homogenization treatment to perform the grinding dispersion treatment. It can be understood that the first high-molecular polymer is allowed to react with the edge-carboxylated graphene first to graft the surface of the edge-carboxylated graphene with the high-molecular polymer sufficiently. At this time, the first high-molecular polymer still has a certain effect on promoting the dispersion of the edge-hydroxylated graphene, but the dispersion stability of the edge-hydroxylated graphene in the first high-molecular polymer will be affected after the first high-molecular polymer is consumed. Therefore, the second high-molecular polymer is further added to disperse the edge-hydroxylated graphene. Due to the presence of the first high-molecular polymer, the second high-molecular polymer can be quickly dispersed around the edge-hydroxylated graphene during the grinding dispersion process, and then further react with the second high-molecular polymer to enhance the dispersion stability of the edge-hydroxylated graphene, that is, the dispersion stability of the edge-modified graphene in the modified graphene coating solution for direct electroplating is effectively improved.

[0094] In one of the embodiments, the step of adding the second high-molecular polymer into the homogenized liquid after the mixing homogenization treatment to perform the grinding dispersion treatment comprises the following steps:

[0095] The step of adding the second high-molecular polymer into the homogenized liquid after the mixing homogenization treatment to perform the grinding treatment preferably realizes the quick dispersion of the second high-molecular polymer to react with the edge-hydroxylated graphene.

[0096] The step of stirring the homogenized liquid after the grinding treatment once preferably ensures the sufficiency of the amidation reaction between the high-molecular polymer and the edge-hydroxylated graphene.

[0097] In one of the embodiments, the edge-modified graphene and the high-molecular polymer are added into water to perform the ultrasonic homogenization operation by using the ultrasonic homogenization combined with the microjet high-pressure homogenizer. It can be understood that the edge-modified graphene is dispersed by using the ultrasonic homogenization combined with the microjet high-pressure homogenizer, which greatly reduces the time of the ultrasonic homogenization dispersion and prevents the graphene from being damaged by long-time ultrasonic homogenization to affect the conductivity, that is, the dispersion stability and the conductivity of the modified graphene coating solution for direct electroplating are preferably ensured.

[0098] In one of the embodiments, the time for adding the edge-modified graphene and the high-molecular polymer into water to perform the ultrasonic homogenization operation is 3h-6h.

[0099] In one embodiment, the condensing agent is added to the homogenate for mixing homogenization treatment, including the following steps:

[0100] The condensing agent is added to the homogenate for ultrasonic treatment, which preferably realizes the rapid dispersion of the condensing agent to promote the amidation reaction of the high molecular polymer and the edge carboxylated graphene.

[0101] Further, the homogenate after ultrasonic treatment is subjected to secondary stirring treatment, which preferably ensures the sufficiency of the amidation reaction of the high molecular polymer and the edge carboxylated graphene.

[0102] In one embodiment, the condensing agent is added to the homogenate for ultrasonic treatment for 0.8h-1.2h.

[0103] In one embodiment, the homogenate after ultrasonic treatment is subjected to stirring treatment for 1h-2h.

[0104] In one embodiment, the homogenate after ultrasonic treatment is subjected to stirring treatment for 1h-2h at a temperature of 30℃-60℃.

[0105] In one embodiment, before the step of drying the homogenate after mixing homogenization treatment, and after the step of secondary stirring treatment of the homogenate after ultrasonic treatment, the preparation method of the modified graphene coating solution for direct electroplating includes the following steps:

[0106] The homogenate after secondary stirring treatment is subjected to cleaning treatment to remove the condensing agent in the homogenate. It can be understood that the removal of the condensing agent reduces the catalytic occurrence of side reactions during the subsequent electroplating of the modified graphene coating solution for direct electroplating, thereby improving the stability of the modified graphene coating solution for direct electroplating. It can also be understood that the cleaning treatment of the homogenate after secondary stirring treatment is performed after the step of adding the subsequent high molecular polymer to the homogenate after mixing homogenization treatment for grinding and dispersing treatment, which preferably ensures the sufficient reaction of the subsequent high molecular polymer and the edge hydroxylated graphene.

[0107] In one embodiment, the homogenate after mixing homogenization treatment is subjected to drying operation, specifically: vacuum drying of the homogenate at 80℃-85℃.

[0108] The application also provides an application of the modified graphene coating solution for direct plating. The modified graphene coating solution for direct plating is applied to hole metallization of a printed circuit board. Further, the modified graphene coating solution for direct plating comprises edge-modified graphene, a high-molecular polymer, a condensing agent, a surface energy aid, an ultradispersant, a pH regulator and water. The surface energy aid comprises a non-ionic gemini surfactant and an anionic surfactant.

[0109] The application of the modified graphene coating solution for direct plating makes the edge-modified graphene uniformly dispersed in the conductive layer formed on the inner wall of the hole by the modified graphene coating solution for direct plating, and makes the thickness of the conductive layer uniform.

[0110] In one embodiment, the application method of the modified graphene coating solution for direct plating comprises the following steps:

[0111] Acid pickling oil removal: the circuit board is immersed in a mixed solution containing 3% (V / V) sulfuric acid (98%) and 5% (V / V) oil removal agent M404 at 30-40°C for 1 min of acid pickling oil removal and then cleaned with pure water;

[0112] Hole wall charge adjustment: the circuit board is treated in a solution containing 4.5% (V / V) M8701 charge adjusting agent for 50-70S and then cleaned with pure water.

[0113] The circuit board is immersed in the modified graphene coating solution for direct plating for 40-70S of coating;

[0114] After being immersed in M101S acid micro-etching liquid with an added corrosion inhibitor for 10-20S, the circuit board is cleaned with pure water;

[0115] The circuit board is taken out and dried with hot air, and then electroplating operation is performed.

[0116] The application method of the modified graphene coating solution for direct plating makes the edge-modified graphene uniformly dispersed in the conductive layer formed on the inner wall of the hole by the modified graphene coating solution for direct plating, and makes the thickness of the conductive layer uniform.

[0117] Compared with the prior art, the application has at least the following advantages:

[0118] The modified graphene coating solution for direct plating of the present application makes the edge modified graphene as the conductive additive of the modified graphene coating solution for direct plating have a complete conjugated structure sp2 network compared to graphene oxide, so that the conductive layer formed by the modified graphene coating solution for direct plating on the surface of the hole wall of the printed circuit board is more complete, and has the characteristics of excellent dispersion stability and excellent conductivity, so that excellent conductivity can be achieved with less solid content of nano modified graphene particles. Using water as the dispersion medium instead of organic solvents avoids the problems of high cost, high boiling point and difficulty in removal of organic solvents, reduces the consumption of raw materials, and makes the modified graphene coating solution for direct plating free of harmful substances, reduces the operation requirements of the modified graphene coating solution for direct plating, and simplifies the operation, while facilitating the maintenance of the tank solution on the production line. The use of a pH adjuster achieves deprotonation of the modified graphene coating solution for direct plating, thereby enhancing the electrostatic interaction between the edge modified graphene and reducing the interaction between the edge modified graphene itself, effectively stabilizing the dispersion stability of the edge modified graphene in the modified graphene coating solution for direct plating. A high molecular polymer is used to disperse the edge modified graphene, wherein the high molecular polymer has little effect on the viscosity of the edge modified graphene coating solution for direct plating, so that the solution has good fluidity, improves the through-hole capability of the tank solution for preparing high aspect ratio circuit boards, and the molecular chain of the high molecular polymer is not easily entangled, while having many hydrophilic functional group end groups to combine with graphene particles by electrostatic force, or further cooperating with a condensing agent to directly modify the edge modified graphene, increasing the steric hindrance between the edge modified graphene, and better maintaining the stable dispersion of the edge modified graphene, achieving the effect of improving dispersion and solubilization. The surface energy additive includes non-ionic gemini surfactant and anionic surfactant, which effectively reduces the critical micelle concentration and reduces the total amount of surface energy additive, so that the graphene still maintains excellent physical properties, enhances the wetting ability of the edge modified graphene in water, is conducive to the rapid infiltration and dispersion of the edge modified graphene, and reduces the stirring time or stirring speed during the dispersion process of the edge modified graphene, and reduces the air bubbles brought in during the coating of the circuit board, which is conducive to increasing the dispersion stability of the edge modified graphene, and makes the dispersion of the edge modified graphene in the conductive layer formed by the modified graphene coating solution for direct plating on the inner wall of the hole uniform, and makes the thickness of the conductive layer uniform.

[0119] Some specific examples are listed below. If % is mentioned, it means percentage by weight. It should be noted that the following examples do not exhaust all possible cases, and the materials used in the following examples can be obtained from commercial sources unless otherwise specified.

[0120] Example 1

[0121] A dispersion liquid containing edge-hydroxylated graphene was prepared by adding 6.0 kg of edge-hydroxylated graphene and 2.0 kg of amino-terminated hyperbranched polyester to 100 L of distilled water and performing ultrasonic dispersion for 3 h in an ultrasonic homogenizer combined with a microjet high-pressure homogenizer, followed by high-pressure homogenization twice at 85 MPa and a flow rate of 60 L / hr;

[0122] The dispersion liquid was transferred to 45°C after being ultrasonically dispersed for 1 h with 3.0 kg of EDC·HCl, and was magnetically stirred for 1 h. Then, 2.5 kg of carboxyl-terminated hyperbranched polyester was added, and the mixture was magnetically stirred for 12 h. The mixture was filtered, washed with distilled water, and dried at 80°C under vacuum to obtain edge-modified modified graphene powder;

[0123] The modified graphene powder was added to 100 L of distilled water together with 0.1 kg of amino-terminated hyperbranched polyester and 0.2 kg of amino-terminated hyperbranched polyester, and was subjected to high-speed grinding at 2700 rpm for 8 h. The ground dispersion liquid was added to a mixture of 0.8 wt% of a nonionic gemini surfactant (Surfynol 440 and Surfynol 465 in a mass ratio of 1:1) and 0.8 wt% of an anionic surfactant (sodium dodecylbenzenesulfonate) (mass ratio of nonionic gemini surfactant to anionic surfactant = 2), and then added to a mixture of 1.2 wt% of polyvinylpyrrolidone and 1.2 wt% of polyoxyethylene-polypropylene copolymer (mass ratio of polyvinylpyrrolidone to polyoxyethylene-polypropylene copolymer = 1:1). The mixture was stirred for 2 h to obtain a dispersion solution;

[0124] The dispersion solution was diluted with distilled water to twice the volume, and then ammonia water was added to adjust the pH of the aqueous solution to 9. The mixture was ultrasonically dispersed for 1 h to obtain a modified graphene coating solution.

[0125] Example 2

[0126] A dispersion liquid containing edge-hydroxylated graphene was prepared by adding 6.0 kg of edge-hydroxylated graphene and 2.0 kg of amino-terminated hyperbranched polyester to 100 L of distilled water and performing ultrasonic dispersion for 3 h in an ultrasonic homogenizer combined with a microjet high-pressure homogenizer, followed by high-pressure homogenization twice at 85 MPa and a flow rate of 60 L / hr;

[0127] The dispersion liquid was transferred to 45°C after being ultrasonically dispersed for 1 h with 3.0 kg of EDC·HCl, and was magnetically stirred for 1 h. Then, 2.5 kg of carboxyl-terminated hyperbranched polyester was added, and the mixture was magnetically stirred for 12 h. The mixture was filtered, washed with distilled water, and dried at 80°C under vacuum to obtain edge-modified modified graphene powder;

[0128] The modified graphene powder and 0.3 kg of an amino-terminated hyperbranched polyester were added to 100 L of distilled water and subjected to high-speed grinding at 2700 rpm for 8 h. The ground dispersion liquid was added with 0.8 wt% of a combination of non-ionic gemini surfactants Surfynol 440 and Surfynol 465 (mass ratio of Surfynol 440 to Surfynol 465 = 1:1), and an anionic surfactant sodium dodecylbenzenesulfonate (mass ratio of non-ionic gemini surfactant to anionic surfactant = 2), followed by 1.2 wt% of a combination of polyvinylpyrrolidone and polyoxyethylene-polypropylene copolymer (mass ratio of polyvinylpyrrolidone to polyoxyethylene-polypropylene copolymer = 1:1), and stirred for 2 h to obtain a dispersion solution;

[0129] The dispersion solution was diluted twice with distilled water, and ammonia water was added to adjust the pH of the aqueous solution to 9. After ultrasonic dispersion for 1 h, a modified graphene coating solution was obtained.

[0130] Example 3

[0131] A mixture of 8.0 kg of both edge-hydroxylated graphene and edge-carboxylated graphene (mass ratio of edge-hydroxylated graphene to edge-carboxylated graphene = 0.5-0.9), 2.0 kg of an amino-terminated hyperbranched polyester, and 2.0 kg of a polyallylamine were added to 100 L of distilled water, and after ultrasonic dispersion for 3 h in an ultrasonic homogenizer combined with a microfluidic high-pressure homogenizer, high-pressure homogenization was performed twice at 85 MPa and a flow rate of 60 L / hr to prepare a dispersion liquid containing edge-hydroxylated and carboxylated graphene;

[0132] The dispersion liquid was added with 4.0 kg of EDC·HCl and ultrasonically dispersed for 1 h, and then transferred to 50°C. After magnetic stirring for 2 h, 2.0 kg of a carboxyl-terminated hyperbranched polyamide was added, and magnetic stirring was performed for 8 h. After filtration and washing with distilled water, edge-modified modified graphene powder was obtained by vacuum drying at 85°C;

[0133] The modified graphene powder and 0.5 kg of an amino-terminated hyperbranched polyester were added to 100 L of distilled water and subjected to high-speed grinding at 2700 rpm for 9 h. The ground dispersion liquid was added to a combination of 1.0 wt% of a nonionic gemini surfactant Surfynol 440 and N,N'-dialkyl-N,N'-bis[2-(lactose amino acid)-methylene]adipamide (the mass ratio of Surfynol 440 to N,N'-dialkyl-N,N'-bis[2-(lactose amino acid)-methylene]adipamide was 1:1), and 3 wt% of an anionic surfactant sodium dodecylbenzenesulfonate (the mass ratio of the nonionic gemini surfactant to the anionic surfactant was 3), followed by 1.5 wt% of a combination of polyvinylpyrrolidone and polyoxyethylene-polypropylene copolymer (the mass ratio of polyvinylpyrrolidone to polyoxyethylene-polypropylene copolymer was 1:1), and stirred for 2 h to obtain a dispersion solution;

[0134] The dispersion solution was diluted twice with distilled water, and ammonia water was added to adjust the pH of the aqueous solution to 8. After ultrasonic dispersion for 2 h, a modified graphene coating solution was obtained.

[0135] Example 4

[0136] A mixture of 8.0 kg of both edge-hydroxylated graphene and edge-carboxylated graphene (the mass ratio of edge-hydroxylated graphene to edge-carboxylated graphene was 0.5-0.9), 2.0 kg of an amino-terminated hyperbranched polyester, and 2.0 kg of a polyallylamine were added to 100 L of distilled water, and after ultrasonic dispersion for 3 h in an ultrasonic homogenizer combined with a microfluidic high-pressure homogenizer, the mixture was subjected to high-pressure homogenization twice at 85 MPa and a flow rate of 60 L / hr to prepare a dispersion liquid containing edge-hydroxylated and carboxylated graphene;

[0137] The dispersion liquid was transferred to 50°C after ultrasonic dispersion for 1 h with 4.0 kg of EDC·HCl, and was subjected to magnetic stirring for 2 h. Then, 2.0 kg of a carboxyl-terminated hyperbranched polyester was added, and the mixture was subjected to magnetic stirring for 8 h. After filtration and washing with distilled water, the mixture was vacuum-dried at 80°C to prepare an edge-modified modified graphene powder.

[0138] The modified graphene powder and 0.5 kg of amino-terminated hyperbranched polyester were added to 100 L of distilled water and subjected to high-speed grinding at 2700 rpm for 9 h. The ground dispersion liquid was added to a combination of 1.0 wt% of non-ionic gemini surfactant Surfynol 440 and N,N'-dialkyl-N,N'-bis[2-(lactose amino acid)-methylene] adipic diamide (the mass ratio of Surfynol 440 and N,N'-dialkyl-N,N'-bis[2-(lactose amino acid)-methylene] adipic diamide was 1:1), and anionic surfactant sodium dodecylbenzenesulfonate (the mass ratio of non-ionic gemini surfactant and anionic surfactant was 4), followed by the addition of 1.5 wt% of a combination of polyvinylpyrrolidone and polyoxyethylene-polypropylene copolymer (the mass ratio of polyvinylpyrrolidone and polyoxyethylene-polypropylene copolymer was 1:1), and stirring for 2 h to obtain a dispersion solution.

[0139] The dispersion solution was diluted twice with distilled water, and ammonia water was added to adjust the pH of the aqueous solution to 8. After ultrasonic dispersion for 2 h, a modified graphene coating solution was obtained.

[0140] Example 5

[0141] A mixture of 8.0 kg of both edge-hydroxylated graphene and edge-carboxylated graphene (the mass ratio of edge-hydroxylated graphene and edge-carboxylated graphene was 0.5-0.9), 1.5 kg of amino-terminated hyperbranched polyester, and 1.5 kg of polyallylamine was added to 100 L of distilled water and subjected to ultrasonic dispersion for 3 h in an ultrasonic combined micro-jet high-pressure homogenizer, followed by high-pressure homogenization at 85 MPa and a flow rate of 60 L / hr twice to prepare a dispersion liquid containing edge-carboxylated graphene.

[0142] The dispersion liquid was added to 3.0 kg of DCC and ultrasonically dispersed for 1 h, and then transferred to 60°C. After magnetic stirring for 2 h, 2.0 kg of carboxyl-terminated hyperbranched polyester was added, and magnetic stirring was performed for 8 h. After filtration and washing with distilled water, edge-modified modified graphene powder was obtained by vacuum drying at 80°C.

[0143] The modified graphene powder and 0.5 kg of amino-terminated hyperbranched polyester were added to 100 L of distilled water and subjected to high-speed grinding at 2700 rpm for 9 h. The ground dispersion liquid was added to a combination of 0.9 wt% of non-ionic gemini surfactant Surfynol 440 and anionic surfactants sodium dodecyl sulfate and sodium dodecylbenzenesulfonate (the mass ratio of sodium dodecyl sulfate and sodium dodecylbenzenesulfonate was 1:1), (the mass ratio of non-ionic gemini surfactant and anionic surfactant was 4), followed by the addition of 1.6 wt% of a combination of polystyrene-block-polyethylene oxide and polyoxyethylene stearate (the mass ratio of polystyrene-block-polyethylene oxide and polyoxyethylene stearate was 1:1), and stirring for 2 h to obtain a dispersion solution.

[0144] The dispersion solution was diluted twice with distilled water, ammonia water was added to adjust the pH of the aqueous solution to 8, and ultrasonic dispersion was performed for 2 h to obtain a modified graphene coating solution.

[0145] 1. The particle size of the modified graphene coating solution obtained in Examples 1 to 5 was detected using a Malvern Panalytical Zetasizer Nano S90 nanoparticle size potential instrument, as shown in Table 1:

[0146] Table 1: Average particle size of the modified graphene coating solution of Examples 1 to 5

[0147] Serial number Particle size distribution Average particle size Example 1 As Figure 2 shown 211.9 nm Example 2 As Figure 3 shown 172.6 nm Example 3 As Figure 4 shown 162.9 nm Example 4 As Figure 5 shown 145.7 nm Example 5 As Figure 6 shown 140.5 nm

[0148] Figure 7 SEM image of the coating layer formed by the modified graphene coating solution of Example 1 on the hole wall of the circuit board; Figure 8 SEM image of the coating layer formed by the modified graphene coating solution of Example 2 on the hole wall of the circuit board; Figure 9 SEM image of the coating layer formed by the modified graphene coating solution of Example 3 on the hole wall of the circuit board; Figure 10 SEM image of the coating layer formed by the modified graphene coating solution of Example 4 on the hole wall of the circuit board; Figure 11 SEM image of the coating layer formed by the modified graphene coating solution of Example 5 on the hole wall of the circuit board; from Table 1 and Figures 2 to 11 It can be seen that the particle size of the conductive substance of the modified graphene coating solution of the present application is small and has high uniformity, and the coating layer formed on the circuit board is smooth and delicate.

[0149] 2. The modified graphene coating solution for direct electroplating prepared in Examples 1-5 was used for direct electroplating application treatment on a standard resistance sheet (specification 15 cm x 6 cm x 0.12 cm, FR-4 copper-clad plate, hole diameter 1000 um, surface hole number 561), and the steps were as follows:

[0150] Pickling oil removal: immerse the circuit board in a mixed solution containing 3% (V / V) sulfuric acid (98%) and 5% (V / V) oil removal agent M404 at 35°C, soak for 1 min, and then wash with pure water.

[0151] Hole wall charge adjustment: take the circuit board and treat it in a solution containing 4.5% (V / V) M8701 charge adjuster for 60 s, and then wash with pure water.

[0152] Immerse the circuit board in the modified graphene coating solution for direct electroplating and coat for 40-70 s;

[0153] After immersing in M101S acid micro-etching solution with added corrosion inhibitor for 15 s, wash with pure water.

[0154] The hot air drying was taken out to obtain the standard resistance sheet, and the resistance test was carried out on the standard resistance sheet using the modified graphene coating solution of direct electroplating of examples 1 to 5, and the results are shown in table 2:

[0155] Table 2: Resistance test results of standard resistance sheet using the modified graphene coating solution of direct electroplating of examples 1 to 5

[0156] Serial number Resistance / Ω Example 1 25.6 Example 2 13.4 Example 3 15.3 Example 4 6.9 Example 5 7.7

[0157] From the data in table 2 and in combination with the pictures and data in table 1, it can be seen that the conductive performance of the standard circuit board after the treatment of the modified graphene coating solution of the present application is good, which can meet the needs of the hole metallization of the high aspect ratio printed circuit board, and the wetting, penetration and dispersion of the hole wall after the treatment of the modified graphene coating solution are uniform.

[0158] The above examples only express several embodiments of the present application, and the description is more specific and detailed, but it cannot be understood as the limitation of the scope of the patent. It should be pointed out that for ordinary skilled in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application should be subject to the appended claims.

Claims

1. A modified graphene coating solution for direct electroplating, characterized by, The components include the following quality parts: The surface energy aid includes non-ionic gemini surfactant and anionic surfactant. The condensing agent is removed after catalyzing the reaction between the edge-modified graphene and the high molecular polymer. The edge-modified graphene includes edge carboxylated graphene. The high molecular polymer includes at least one of end-amino hyperbranched polyester, end-amino hyperbranched polyamide and polyallylamine; or, The edge-modified graphene includes edge hydroxylated graphene. The high molecular polymer includes at least one of end-carboxyl hyperbranched polyester, end-carboxyl hyperbranched polyamide and double-end carboxylic acid polyethylene glycol.

2. The modified graphene coating solution for direct electrodeposition according to claim 1, characterized by, The edge carboxylated graphene has a particle size of 0.5um-1.5um and a layer number of 1-15; and / or, The end-amino hyperbranched polyester has a molecular weight of 800-1200 and an amino number of 7-11; and / or, The end-amino hyperbranched polyamide has a molecular weight of 800-1200 and an amino number of 7-11; and / or, The polyallylamine has a molecular weight of 1500-5000.

3. The modified graphene coating solution for direct electrodeposition according to claim 1, characterized by, The edge hydroxylated graphene has a particle size of 0.5um-1.5um and a layer number of 1-15; and / or, The end-carboxyl hyperbranched polyester has a molecular weight of 950-1200 and a carboxyl number of 6-8; and / or, The end-carboxyl hyperbranched polyamide has a molecular weight of 950-1200 and a carboxyl number of 6-8; and / or, The end-carboxylic acid polyethylene glycol has a molecular weight of 600-1000.

4. The modified graphene coating solution for direct electrodeposition according to claim 1, characterized by, The condensing agent is EDC·HCl or DCC; and, The hyperdispersant is at least one of polyvinylpyrrolidone, polyoxyethylene-polypropylene copolymer, polystyrene block polyethylene oxide and polyoxyethylene stearate; and, The PH regulator is ammonia water or sodium carbonate solution.

5. The modified graphene coating solution for direct electrodeposition according to claim 1, characterized by, The non-ionic gemini surfactant is at least one of N,N'-bis(hydroxyethyl)-N,N'-bis(ethoxy)dodecylamide, N,N'-dialkyl-N,N'-bis[2-(lactose amino acid)-methylene]adipic diamide, Surfynol 420, Surfynol 440, Surfynol 465 and Surfynol 485W; and / or, The anionic surfactant is at least one of sodium dodecyl sulfate, sodium dodecyl benzene sulfonate and potassium dodecyl phosphate.

6. A method for preparing a modified graphene coating solution for direct electroplating, characterized by, The preparation method of the modified graphene coating solution for direct electroplating according to any one of claims 1-5 comprises the following steps: Obtaining edge-modified graphene and high molecular polymer; Adding the edge-modified graphene and the high molecular polymer into water for ultrasonic homogenization operation to obtain a homogenized liquid; Adding a condensing agent to the homogenized liquid for mixing homogenization treatment; Drying the homogenized liquid after mixing homogenization treatment to obtain modified graphene particles; Adding the modified graphene particles, surface energy aid and hyperdispersant into water for homogenization dispersion operation to obtain a dispersion liquid; and Obtaining the modified graphene coating solution for direct electroplating. A dilution adjustment operation is performed by adding a pH adjuster and water to the dispersion liquid, to obtain a modified graphene coating solution for direct plating.

7. Use of a modified graphene coating solution for direct electroplating, characterized in that, The modified graphene coating solution for direct plating according to any one of claims 1 to 5 is applied to hole metallization of a printed circuit board.

Images