A method for enhancing the interface bonding strength between an insulating substrate and a metal layer

Abstract

The application discloses a method for enhancing the interface bonding strength of an insulating substrate and a metal layer, characterized in that the method comprises the following steps: A. grafting a modifier to a silane coupling agent to obtain a modified silane coupling agent; and performing hydrolysis treatment on the modified silane coupling agent to obtain a modified silane coupling agent hydrolysate; B. mixing the modified silane coupling agent hydrolysate with a graphene solution to obtain a modified silane coupling agent-graphene composite liquid; C. coating the modified silane coupling agent-graphene composite liquid on the surface of the insulating substrate to obtain a silane coupling agent-graphene composite coating, and performing drying treatment to form an insulating substrate with a conductive layer; and D. performing electroplating on the insulating substrate with the conductive layer to obtain an insulating substrate with a metal layer. The method for enhancing the interface bonding strength of the insulating substrate and the metal layer improves the interface bonding strength of the insulating substrate and the metal layer by coating the modified silane coupling agent-graphene composite liquid on the surface of the insulating substrate.

Description

Technical Field

[0001] This invention relates to the field of electroplating technology, and in particular to a method for enhancing the bonding strength between an insulating substrate and a metal interface. Background Technology

[0002] Traditional processes for constructing metal layers on insulating substrates typically involve first depositing copper foil on the surface of the insulating substrate using chemical plating as a conductive interface, and then thickening the copper layer using electroplating to achieve the metal layer. Although chemical copper plating technology is relatively mature, it still has the following inherent drawbacks: (1) The reducing agents used in chemical copper plating are mostly toxic formaldehyde, which will cause serious environmental pollution; (2) The complexing agent in the plating solution is complex to handle, requiring a special complex-breaking process to reduce the impact on wastewater treatment, which brings huge challenges to environmental protection work; (3) Insufficient interfacial bonding strength with low surface energy substrates may affect the overall performance of the product.

[0003] To overcome the aforementioned shortcomings, researchers innovatively proposed a direct electroplating process. This process involves coating a conductive material onto the surface of an insulating substrate, providing the necessary conductive foundation for the electroplating operation. Graphene is composed of carbon atoms arranged in sp... 2 Two-dimensional carbon nanomaterials composed of hybrid orbitals, with a hexagonal honeycomb lattice structure, possess excellent electrical conductivity and mechanical strength, providing a working basis for direct electroplating technology using graphene as a conductive layer. For example, Chinese invention patent CN110351956A discloses a method for direct electroplating of circuit boards based on graphene film formation. This method forms a conductive layer on the circuit board through a graphene film formation process, successfully replacing the traditional chemical copper plating step and realizing direct electroplating on an insulating substrate. Furthermore, Chinese invention patent CN110158132A also proposes an electroplating method for insulating materials. This method constructs graphite nanosheet circuits on the surface of the insulating material, similarly achieving direct electroplating on an insulating substrate. However, both of these methods still suffer from weak adhesion between the metal layer and the surface of the insulating material.

[0004] To improve the interfacial bonding strength between the insulating substrate and the metal layer, existing technologies also add binding agents containing oligomers (molecular weight 400-4000) with sulfonic acid, sulfonyl, or carboxylic acid groups to the conductive layer. These binding agents enhance the covalent bonding between the conductive layer and the plated metal during electroplating and simultaneously generate hydrogen bonds with the surface of the insulating substrate, thereby strengthening the interfacial bonding strength between the insulating substrate and the metal layer. However, due to the limited covalent bonding between the conductive layer and the metal layer, as well as the limited hydrogen bonding between the conductive layer and the insulating substrate surface groups, the interfacial bonding strength between the insulating substrate and the metal layer remains insufficient to meet practical application requirements. Summary of the Invention

[0005] The purpose of this invention is to propose a method to enhance the interfacial bonding strength between an insulating substrate and a metal layer. By coating a modified silane coupling agent-graphene composite liquid onto the surface of the insulating substrate, the modified silane coupling agent and its hydrolysis products in the modified silane coupling agent-graphene composite liquid enhance the interfacial bonding strength between the conductive layer and the metal layer, as well as between the conductive layer and the insulating substrate, thereby greatly improving the interfacial bonding strength between the insulating substrate and the metal layer and overcoming the shortcomings of the prior art.

[0006] To achieve this objective, the present invention adopts the following technical solution:

[0007] A method for enhancing the interfacial bonding strength between an insulating substrate and a metal layer includes the following steps:

[0008] A. A modifier is grafted onto a silane coupling agent to obtain a modified silane coupling agent; the modified silane coupling agent is hydrolyzed to obtain a modified silane coupling agent hydrolysate; wherein the modifier contains unsaturated nitrogen or sulfur functional groups.

[0009] B. The modified silane coupling agent hydrolysate is mixed with a graphene solution to obtain a modified silane coupling agent-graphene composite solution; the graphene content in the modified silane coupling agent-graphene composite solution is 0.01-10% by mass percentage.

[0010] C. A modified silane coupling agent-graphene composite liquid is coated on the surface of an insulating substrate to obtain a silane coupling agent-graphene composite coating. After drying, an insulating substrate with a conductive layer is formed; wherein, the insulating substrate contains functional groups that can react with hydroxyl groups.

[0011] D. Electroplating is performed on an insulating substrate with a conductive layer to obtain an insulating substrate with a metal layer.

[0012] Further, in step A, the modifier includes any one of imidazole, 2-methylimidazolium, 2-phenylimidazolium, benzimidazole, benzotriazole, lysine, and thiourea.

[0013] Further, in step A, the silane coupling agent includes any one of vinyltriethoxysilane, vinyltrimethoxysilane, vinyltri(β-methoxyethoxy)silane, γ-aminopropyltriethoxysilane, 3-propylisocyanatetriethoxysilane, and anilinemethyltrimethylsilane.

[0014] Furthermore, in step A, the specific method for the hydrolysis treatment is as follows:

[0015] The first solvent and water are mixed evenly to obtain the first mixed solution;

[0016] The first mixed solution was stirred, and a modified silane coupling agent was added dropwise during the stirring process to obtain a second mixed solution;

[0017] The pH of the second mixed solution was adjusted to 1.5-6, and then the pH-adjusted second mixed solution was stirred until it was completely transparent to obtain the modified silane coupling agent hydrolysate.

[0018] The first solvent includes either isopropanol or ethanol.

[0019] Furthermore, in the hydrolysis process, the mixing ratio of the first solvent to water is (5-10):1, calculated by mass ratio.

[0020] Further, in step B, the graphene solution is prepared by:

[0021] Graphene is obtained by uniformly mixing graphite powder, surfactant and water, followed by ball milling, ultrasonication, filtration, washing and drying.

[0022] Graphene is mixed evenly with a second solvent to obtain a graphene solution.

[0023] Further, in step B, the mixing ratio of the modified silane coupling agent hydrolysate and the graphene solution is 1:(1-100) by mass.

[0024] Furthermore, step C specifically includes:

[0025] C1. The modified silane coupling agent-graphene composite liquid is coated on the surface of an insulating substrate to obtain a silane coupling agent-graphene composite base layer.

[0026] C2. Repeat step C1 4 to 20 times to obtain a silane coupling agent-graphene composite coating, and after drying, form an insulating substrate with a conductive layer.

[0027] Further, in step C2, the specific method of the drying treatment is to dry the upper surface of the silane coupling agent-graphene composite coating;

[0028] The drying process includes either high-energy laser scanning or high-temperature airflow baking.

[0029] Further, in step C, the insulating substrate is a glass substrate, and step C specifically involves: coating the modified silane coupling agent-graphene composite liquid onto the surface of the activated glass substrate to obtain a silane coupling agent-graphene composite coating, and then drying it to form a glass substrate with a conductive layer.

[0030] The technical solution provided by this invention may include the following beneficial effects:

[0031] 1. The modified silane coupling agent in the modified silane coupling agent-graphene composite solution can form silanol (Si-OH) after hydrolysis. Silanol can react with amine, carboxyl, and hydroxyl groups on the surface of the insulating substrate to form strong covalent bonds, thereby increasing the interfacial bonding strength between the modified silane coupling agent in the conductive layer and the insulating substrate. Furthermore, these covalent bonds can also act as a bridge, promoting the connection between graphene in the conductive layer and the insulating substrate, thus increasing the interfacial bonding strength between the graphene in the conductive layer and the insulating substrate. In other words, the condensation reaction between the hydrolysis products of the modified silane coupling agent in the conductive layer and the groups on the surface of the insulating substrate can improve the interfacial bonding strength between the conductive layer and the insulating substrate.

[0032] 2. Because the modifier contains unsaturated nitrogen or sulfur functional groups, the modified silane coupling agent also contains unsaturated nitrogen or sulfur functional groups. The lone pairs of electrons in the unsaturated nitrogen or sulfur functional groups can form stable coordinate bonds (-N-Me bonds or -S-Me bonds, where Me represents a metal atom) with the empty orbitals of metal atoms in the metal layer, thereby increasing the interfacial bonding strength between the modified silane coupling agent and the metal layer in the conductive layer. Furthermore, these coordinate bonds also act as a bridge, promoting the connection between graphene in the conductive layer and the metal layer, thus increasing the interfacial bonding strength between graphene in the conductive layer and the metal layer. In other words, the coordination effect between the unsaturated nitrogen or sulfur functional groups of the modified silane coupling agent in the conductive layer and the metal atoms in the metal layer can improve the interfacial bonding strength between the conductive layer and the metal layer. Detailed Implementation

[0033] This technical solution provides a method for enhancing the interfacial bonding strength between an insulating substrate and a metal layer, including the following steps:

[0034] A. A modifier is grafted onto a silane coupling agent to obtain a modified silane coupling agent; the modified silane coupling agent is hydrolyzed to obtain a modified silane coupling agent hydrolysate; wherein the modifier contains unsaturated nitrogen or sulfur functional groups.

[0035] B. The modified silane coupling agent hydrolysate is mixed with a graphene solution to obtain a modified silane coupling agent-graphene composite solution; the graphene content in the modified silane coupling agent-graphene composite solution is 0.01-10% by mass percentage.

[0036] C. A modified silane coupling agent-graphene composite liquid is coated on the surface of an insulating substrate to obtain a silane coupling agent-graphene composite coating. After drying, an insulating substrate with a conductive layer is formed; wherein, the insulating substrate contains functional groups that can react with hydroxyl groups.

[0037] D. Electroplating is performed on an insulating substrate with a conductive layer to obtain an insulating substrate with a metal layer.

[0038] To address the technical problem of insufficient interfacial bonding strength between the insulating substrate and the metal layer in existing technologies, this technical solution proposes a method to enhance the interfacial bonding strength between the insulating substrate and the metal layer. By coating the surface of the insulating substrate with a modified silane coupling agent-graphene composite liquid, the modified silane coupling agent and its hydrolysis products in the modified silane coupling agent-graphene composite liquid are used to enhance the interfacial bonding strength between the conductive layer and the metal layer, as well as between the conductive layer and the insulating substrate. This significantly improves the interfacial bonding strength between the insulating substrate and the metal layer, meeting practical application requirements.

[0039] Specifically, in existing technologies, to improve the interfacial bonding strength between the insulating substrate and the metal layer, oligomers (molecular weight 400-4000) with sulfonic acid groups, sulfonyl groups, or carboxyl groups are generally added to the conductive layer to enhance the interfacial bonding strength between the insulating substrate and the metal layer. However, the degree to which the above method improves the interfacial bonding strength between the insulating substrate and the metal layer is limited and cannot meet practical application requirements. Therefore, this technical solution cannot improve the interfacial bonding strength based on this principle.

[0040] To improve the interfacial bonding strength between the insulating substrate and the metal layer, this technical solution utilizes a modified silane coupling agent hydrolysate mixed with a graphene solution to obtain a modified silane coupling agent-graphene composite solution. This modified silane coupling agent-graphene composite solution is then coated onto the surface of the insulating substrate to form a silane coupling agent-graphene composite coating. After drying, an insulating substrate with a conductive layer is formed. The modified silane coupling agent in the modified silane coupling agent-graphene composite solution hydrolyzes to form silanol (Si-OH). The silanol can react with amine, carboxyl, and hydroxyl groups on the surface of the insulating substrate to form strong covalent bonds, thereby increasing the interfacial bonding strength between the modified silane coupling agent in the conductive layer and the insulating substrate. Furthermore, these covalent bonds also act as a bridge, promoting the connection between the graphene in the conductive layer and the insulating substrate, thus increasing the interfacial bonding strength between the graphene in the conductive layer and the insulating substrate. That is, the condensation reaction between the hydrolysis products of the modified silane coupling agent in the conductive layer and the groups on the surface of the insulating substrate can improve the interfacial bonding strength between the conductive layer and the insulating substrate.

[0041] In addition, because the modifier contains unsaturated nitrogen or sulfur functional groups, the modified silane coupling agent also contains unsaturated nitrogen or sulfur functional groups. The lone pairs of electrons in these unsaturated nitrogen or sulfur functional groups can form stable coordinate bonds (-N-Me or -S-Me bonds, where Me represents a metal atom) with the empty orbitals of metal atoms in the metal layer, thereby increasing the interfacial bonding strength between the modified silane coupling agent and the metal layer in the conductive layer. Furthermore, these coordinate bonds also act as a bridge, promoting the connection between graphene in the conductive layer and the metal layer, thus increasing the interfacial bonding strength between graphene in the conductive layer and the metal layer. In other words, the coordination effect between the unsaturated nitrogen or sulfur functional groups of the modified silane coupling agent in the conductive layer and the metal atoms in the metal layer can improve the interfacial bonding strength between the conductive layer and the metal layer.

[0042] Furthermore, the unsaturated nitrogen or sulfur functional groups in the modified silane coupling agent can further stabilize the interface between the conductive layer and the insulating substrate through physical adsorption, promoting the connection between the graphene in the conductive layer and the insulating substrate, thereby improving the interfacial bonding strength between the conductive layer and the insulating substrate.

[0043] Therefore, this technical solution utilizes modified silane coupling agents and their hydrolysis products to enhance the interfacial bonding strength between the conductive layer and the insulating substrate, and also utilizes modified silane coupling agents to enhance the interfacial bonding strength between the conductive layer and the metal layer, thus significantly improving the interfacial bonding strength between the insulating substrate and the metal layer. Furthermore, compared to using bonding aids to improve interfacial bonding strength, the hydrolysis product of the modified silane coupling agent, silanol, reacts with the amine, carboxyl, and hydroxyl groups on the surface of the insulating substrate to form stronger covalent bonds, and the lone pair electrons in the modified silane coupling agent form stronger coordination bonds with the metal atoms in the metal layer, thereby further enhancing the interfacial bonding strength between the insulating substrate and the metal layer.

[0044] Furthermore, the improved interfacial bonding strength between the insulating substrate and the metal layer allows for an increase in the design thickness of the metal layer. This increased thickness helps reduce resistance, resulting in higher conductivity of the metal circuits formed by etching the metal layer during subsequent use. Additionally, the improved interfacial bonding strength between the conductive layer and the insulating substrate allows the graphene in the conductive layer to fully utilize its excellent conductivity and mechanical strength, thereby enhancing the overall conductivity and mechanical properties of the structure.

[0045] Secondly, existing technologies typically use an immersion method to attach the conductive layer to an insulating substrate, but this method is time-consuming and makes it difficult to obtain a dense conductive layer.

[0046] In this technical solution, a coating method is used instead of an immersion method to coat the surface of an insulating substrate with a modified silane coupling agent-graphene composite liquid. This not only shortens the preparation time of the conductive layer, but also, because the modified silane coupling agent-graphene composite liquid used in the coating method has a high graphene content (since the thickness of the silane coupling agent-graphene composite coating obtained on the surface of the insulating substrate is at the nanometer level, only a very small amount of graphene is needed to achieve the above requirements; therefore, even if the graphene content in the modified silane coupling agent-graphene composite liquid is 0.01%, its content is still relatively high), the graphene in the modified silane coupling agent-graphene composite liquid can remain on the surface of the insulating substrate after drying. In addition, the interfacial bonding strength between graphene and the insulating substrate is high. The above two aspects are conducive to obtaining a denser and thicker conductive layer. Furthermore, due to the high concentration of graphene in the modified silane coupling agent-graphene composite solution (i.e., the high solid content of the modified silane coupling agent-graphene composite solution), the modified silane coupling agent-graphene composite solution can penetrate even if there are pores on the surface of the insulating substrate, which is beneficial to improving the completion of electroplating metal on the substrate surface and the conductivity and mechanical properties of the overall structure.

[0047] It should be noted that the electroplating method in this technical solution is a conventional method in the prior art and will not be described in detail here. Furthermore, the focus of this technical solution is to enhance the interfacial bonding between the insulating substrate and the metal layer; therefore, this technical solution does not describe the patterning process obtained using conventional etching techniques in the art before or after step D.

[0048] Preferably, the insulating substrate includes any one of a glass substrate, a polyamide substrate, and a glass fiber epoxy resin substrate.

[0049] Preferably, in step C, the thickness of the conductive layer is 10–50 nm.

[0050] (1) Due to the excellent conductivity of graphene, the conductive layer can provide efficient electron transport even with a thickness of 10-50 nm, ensuring that the conductive layer plays a good conductive role in electronic devices or circuits; (2) Although the high mechanical strength of graphene itself gives the conductive layer high mechanical strength, an excessively thin conductive layer may be easily damaged, affecting its stability and reliability in long-term use. When the thickness of the conductive layer is 10-50 nm, the conductive layer can balance conductivity and mechanical strength, ensuring its durability in various application scenarios; (3) When the thickness of the conductive layer is 10-50 nm, the bonding between the conductive layer and the insulating substrate is tighter; (4) An excessively thick conductive layer will increase material costs and production time. Therefore, based on the above reasons, this technical solution limits the thickness of the conductive layer to maximize cost-effectiveness while ensuring performance.

[0051] To further explain, in step A, the modifier includes any one of imidazole, 2-methylimidazolium, 2-phenylimidazolium, benzimidazole, benzotriazole, lysine, and thiourea.

[0052] This technical solution optimizes the type of modifier, which on the one hand helps ensure the performance of the modified silane coupling agent, and on the other hand allows for the selection of raw materials according to actual needs, thus improving the flexibility of the method.

[0053] To further explain, in step A, the silane coupling agent includes any one of vinyltriethoxysilane, vinyltrimethoxysilane, vinyltri(β-methoxyethoxy)silane, γ-aminopropyltriethoxysilane, 3-propylisocyanatetriethoxysilane, and anilinemethyltrimethylsilane.

[0054] Vinyltriethoxysilane, vinyltrimethoxysilane, vinyltri(β-methoxyethoxy)silane, γ-aminopropyltriethoxysilane, 3-isocyanatepropyltriethoxysilane, and anilinemethyltrimethylsilane can all be hydrolyzed to produce silanols. On the one hand, this helps to ensure the performance of the modified silane coupling agent, and on the other hand, it allows for the selection of raw materials according to actual needs, thus improving the flexibility of the method.

[0055] Preferably, the silane coupling agent includes any one of vinyltriethoxysilane, vinyltrimethoxysilane, and vinyltri(β-methoxyethoxy)silane.

[0056] Vinyltriethoxysilane, vinyltrimethoxysilane, and vinyltri(β-methoxyethoxy)silane all have short carbon chains, low steric hindrance, and relatively good hydrophilicity, which is beneficial for increasing the hydrolysis reaction rate of the modified silane coupling agent, thereby improving the interfacial bonding strength between the insulating substrate and the metal layer. Furthermore, these silane coupling agents exhibit good stability, simple preparation methods, readily available raw materials, and low production costs, thus contributing to reduced production costs.

[0057] To further explain, the specific method of hydrolysis treatment in step A is as follows:

[0058] The first solvent and water are mixed evenly to obtain the first mixed solution;

[0059] The first mixed solution was stirred, and a modified silane coupling agent was added dropwise during the stirring process to obtain a second mixed solution;

[0060] The pH of the second mixed solution was adjusted to 1.5-6, and then the pH-adjusted second mixed solution was stirred until it was completely transparent to obtain the modified silane coupling agent hydrolysate.

[0061] The first solvent includes either isopropanol or ethanol.

[0062] Since the silanols generated from the hydrolysis of modified silane coupling agents also undergo condensation reactions, the hydrolysis process of modified silane coupling agents involves both hydrolysis and condensation reactions simultaneously. These two reactions compete with each other. To ensure the silanol content in the system is as high as possible, the condensation reaction should be controlled. Water can promote the hydrolysis of modified silane coupling agents, while isopropanol and ethanol can reduce the condensation reaction of silanols. Therefore, this technical solution uses either isopropanol or ethanol mixed evenly with water to obtain a first mixed solution, thereby maximizing the generation of silanols.

[0063] In addition, when the pH of the second mixed solution is adjusted to 1.5-6, the difference between the hydrolysis reaction rate and the condensation reaction rate is large, which further increases the amount of silanol in the system, thereby improving the interfacial bonding strength between the conductive layer and the insulating substrate.

[0064] It should be noted that when the modified silane coupling agent is not completely hydrolyzed, the second mixed solution after pH adjustment is turbid; when the modified silane coupling agent is completely hydrolyzed, the second mixed solution after pH adjustment is completely transparent. Therefore, in order to ensure complete hydrolysis of the modified silane coupling agent, the second mixed solution after pH adjustment in this technical solution is stirred until completely transparent.

[0065] To further explain, in the hydrolysis process, the mixing ratio of the first solvent to water, calculated by mass ratio, is (5-10):1.

[0066] In this technical solution, the mixing ratio of the first solvent and water is limited to maximize the hydrolysis rate of the modified silane coupling agent, minimize the condensation reaction rate, and maximize the difference between the hydrolysis reaction rate and the condensation reaction rate. This further increases the silanol content in the modified silane coupling agent hydrolysate and enhances the interfacial bonding strength between the insulating substrate and the metal layer.

[0067] To further explain, in step B, the graphene solution is prepared as follows:

[0068] Graphene is obtained by uniformly mixing graphite powder, surfactant and water, followed by ball milling, ultrasonication, filtration, washing and drying.

[0069] Graphene is mixed evenly with a second solvent to obtain a graphene solution.

[0070] The principle of obtaining graphene in step B is as follows: Graphite powder, surfactant, and water are mixed. The surfactant helps to better disperse the graphite powder in water and prevents the graphite particles from agglomerating. Ball milling is used to further refine the graphite particles and increase their contact area with the surfactant and water, which is beneficial for subsequent dispersion and exfoliation. The ball-milled mixture is then ultrasonically treated to further exfoliate the graphite particles into thinner graphene. Simultaneously, ultrasonic treatment also promotes the adsorption of surfactant on the surface of the graphite particles, enhancing the dispersibility between graphene particles. After ultrasonic treatment, the graphene is separated from the mixture by filtration. The filtered graphene is then washed and dried to remove residual surfactant, moisture, and other impurities from the graphene surface, thereby improving the purity of the graphene.

[0071] In addition to being beneficial for the dispersion of graphite powder and graphene, surfactants also have long-chain alkyl groups in their molecular structure that can insert into the interlayer of graphite in graphite powder, weakening the interlayer interaction forces and promoting the exfoliation of graphite powder into graphene.

[0072] Preferably, the second solvent includes any one of ethanol, ethylene glycol, isopropanol, N-methylpyrrolidone, and dichloromethane.

[0073] The surfactant includes any one of sodium dodecyl sulfonate, sodium tetrapoly(propylene) sulfonate, sodium diisooctyl succinate sulfonate, sodium dibutylnaphthalene sulfonate, sodium dodecyl sulfate, and polyethylene glycol octylphenyl ether.

[0074] To further explain, in step B, the mixing ratio of the modified silane coupling agent hydrolysate and the graphene solution is 1:(1-100) by mass.

[0075] In this technical solution, by limiting the mixing ratio of the modified silane coupling agent hydrolysate and the graphene solution, the content of the modified silane coupling agent and its hydrolysis products is sufficient to enhance and improve the interfacial bonding strength between the conductive layer and the metal layer, as well as between the conductive layer and the insulating substrate, thereby helping to ensure the interfacial bonding strength between the insulating substrate and the metal layer.

[0076] To further explain, step C specifically includes:

[0077] C1. The modified silane coupling agent-graphene composite liquid is coated on the surface of an insulating substrate to obtain a silane coupling agent-graphene composite base layer.

[0078] C2. Repeat step C1 4 to 20 times to obtain a silane coupling agent-graphene composite coating, and after drying, form an insulating substrate with a conductive layer.

[0079] Modified silane coupling agents and their hydrolysis products enhance the bonding force between graphene and the insulating substrate, while graphene, due to its excellent electrical conductivity, is used to form a conductive layer. Applying the coating 4 to 20 times helps to ensure that graphene is uniformly distributed in the conductive layer, thereby forming a stable conductive layer with good electrical conductivity on the surface of the insulating substrate.

[0080] To further explain, in step C2, the specific method of the drying treatment is: drying the upper surface of the silane coupling agent-graphene composite coating;

[0081] The drying process includes either high-energy laser scanning or high-temperature airflow baking.

[0082] Existing technologies primarily involve placing an insulating substrate coated with a modified silane coupling agent-graphene composite solution in a vacuum drying oven. However, in a vacuum drying oven, the solvent evaporation rate is limited due to the vacuum environment, resulting in a relatively low drying rate. Furthermore, solvent evaporation in a vacuum drying oven is random and lacks specific directionality, which can easily cause stress concentration within the coating or lead to unevenness on the coating surface. In addition, while vacuum drying ovens are mainly used to remove solvent from the coating and allow it to dry and solidify, the coating may still retain a certain degree of porosity or loose structure after drying, affecting its density.

[0083] Furthermore, high-energy laser beams offer rapid drying, and precise laser control ensures uniform heating of the coating, preventing damage caused by localized overheating. High-temperature gas flow baking provides high drying efficiency, and the solvent evaporation path can be controlled by adjusting the gas flow speed and direction, which is beneficial for forming a uniform coating. Therefore, to overcome these shortcomings, this technical solution limits the drying method to either high-energy laser scanning or high-temperature gas flow baking. Both methods significantly accelerate solvent evaporation, thereby improving drying efficiency.

[0084] Furthermore, drying the upper surface of the silane coupling agent-graphene composite coating allows the solvent to escape sequentially from top to bottom. This directional evaporation helps form a more uniform coating structure, reducing porosity and loose structure, and improving the coating's density and conductivity. Moreover, as the solvent escapes from the coating surface, the surface tension of the residual liquid exerts a downward force on the graphene in the coating, causing it to adhere more tightly to the surface of the insulating substrate. This effect not only enhances the interfacial bonding strength between the graphene and the insulating substrate but also contributes to improving the overall stability and durability of the coating.

[0085] Preferably, the scanning energy of the high-energy laser scanning is 1 to 10 keV, and the scanning speed is 50,000 to 100,000 pts / s;

[0086] The high-temperature airflow baking temperature is 100-150℃, and the airflow velocity is 1-1.5m / s.

[0087] To further clarify, the insulating substrate is a glass substrate, and step C specifically includes:

[0088] A modified silane coupling agent-graphene composite liquid is coated onto the surface of an activated glass substrate to obtain a silane coupling agent-graphene composite coating. After drying, a glass substrate with a conductive layer is formed.

[0089] Activation treatment introduces more hydroxyl groups (-OH) onto the surface of the glass substrate, facilitating the condensation polymerization of silanols after hydrolysis of the silane coupling agent and the formation of chemical bonds. Simultaneously, activation treatment of the glass substrate surface can increase its roughness or create micro / nano structures, which helps the modified silane coupling agent form a stronger mechanical anchor on the glass substrate surface, further improving its adhesion and durability. Therefore, this technical solution, which activates the glass substrate, is beneficial for improving product performance.

[0090] It should be noted that the activation treatment can be carried out using existing technologies such as plasma cleaning, catalyst activation, and high-temperature activation, and is not limited here.

[0091] The technical solution of the present invention will be further illustrated below through specific embodiments.

[0092] Example 1

[0093] A. Imidazole is grafted onto vinyltriethoxysilane to obtain a modified silane coupling agent; isopropanol and water are mixed evenly at a mass ratio of 5:1 to obtain a first mixed solution; the first mixed solution is stirred, and the modified silane coupling agent is added dropwise during the stirring process to obtain a second mixed solution; the pH value of the second mixed solution is adjusted to 4, and then the pH-adjusted second mixed solution is stirred until it is completely transparent to obtain a modified silane coupling agent hydrolysate;

[0094] B. Graphite powder, sodium dodecyl sulfonate and water are mixed evenly, and graphene is obtained after ball milling, ultrasonication, filtration, washing and drying; graphene is mixed evenly with ethanol to obtain graphene solution; modified silane coupling agent hydrolysate with a mass ratio of 1:60 is mixed with graphene solution to obtain modified silane coupling agent-graphene composite solution with a graphene content of 5%.

[0095] C. The modified silane coupling agent-graphene composite liquid is coated onto the surface of an activated glass substrate to obtain a silane coupling agent-graphene composite base layer; the modified silane coupling agent-graphene composite liquid is coated onto the surface of the activated glass substrate 10 times to obtain a silane coupling agent-graphene composite coating; the upper surface of the silane coupling agent-graphene composite coating is dried using a high-energy laser with a scanning energy of 5 KeV and a scanning speed of 50000 pts / s to form a glass substrate with a conductive layer; wherein the thickness of the conductive layer is 20 nm.

[0096] D. Copper plating is performed on an insulating substrate with a conductive layer to obtain a glass substrate with a metallic layer; wherein the electroplating current density is 3 A / dm³. 2 The electroplating time is 40 minutes.

[0097] Example 2

[0098] A. Benzimidazole was grafted onto γ-aminopropyltriethoxysilane to obtain a modified silane coupling agent; ethanol and water were mixed evenly at a mass ratio of 8:1 to obtain a first mixed solution; the first mixed solution was stirred, and the modified silane coupling agent was added dropwise during the stirring process to obtain a second mixed solution; the pH value of the second mixed solution was adjusted to 5, and then the pH-adjusted second mixed solution was stirred until it was completely transparent to obtain a modified silane coupling agent hydrolysate;

[0099] B. Graphite powder, sodium dodecyl sulfate and water are mixed evenly, and graphene is obtained after ball milling, ultrasonication, filtration, washing and drying. Graphene is mixed evenly with N-methylpyrrolidone to obtain a graphene solution. Modified silane coupling agent hydrolysate with a mass ratio of 1:50 is mixed with the graphene solution to obtain a modified silane coupling agent-graphene composite solution with a graphene content of 8%.

[0100] C. A modified silane coupling agent-graphene composite liquid is coated onto the surface of a glass fiber epoxy resin substrate to obtain a silane coupling agent-graphene composite base layer; the modified silane coupling agent-graphene composite liquid is coated onto the surface of the glass fiber epoxy resin substrate eight times to obtain a silane coupling agent-graphene composite coating; the upper surface of the silane coupling agent-graphene composite coating is dried using a high-temperature nitrogen gas flow at 120℃ and a gas flow rate of 1.2m / s to form a glass fiber epoxy resin substrate with a conductive layer; wherein, the thickness of the conductive layer is 30nm.

[0101] D. A glass fiber epoxy resin substrate with a conductive layer is electroplated with copper to obtain a glass fiber epoxy resin substrate with a metal layer; wherein the electroplating current density is 2A / dm³. 2 The electroplating time is 35 minutes.

[0102] Example 3

[0103] A. Benzotriazole was grafted onto vinyltris(β-methoxyethoxy)silane to obtain a modified silane coupling agent; isopropanol and water were mixed evenly at a mass ratio of 10:1 to obtain a first mixed solution; the first mixed solution was stirred, and the modified silane coupling agent was added dropwise during the stirring process to obtain a second mixed solution; the pH value of the second mixed solution was adjusted to 3.5, and then the pH-adjusted second mixed solution was stirred until it was completely transparent to obtain a modified silane coupling agent hydrolysate;

[0104] B. Graphite powder, sodium dodecyl sulfate and water are mixed evenly, and graphene is obtained after ball milling, ultrasonication, filtration, washing and drying. Graphene is mixed evenly with N-methylpyrrolidone to obtain a graphene solution. Modified silane coupling agent hydrolysate with a mass ratio of 1:80 is mixed with the graphene solution to obtain a modified silane coupling agent-graphene composite solution with a graphene content of 10%.

[0105] C. The modified silane coupling agent-graphene composite liquid is coated onto the surface of a glass substrate to obtain a silane coupling agent-graphene composite base layer; the modified silane coupling agent-graphene composite liquid is coated onto the surface of the glass substrate 8 times to obtain a silane coupling agent-graphene composite coating; the upper surface of the silane coupling agent-graphene composite coating is dried using a high-temperature nitrogen gas flow at 150℃ and a gas flow rate of 1.1m / s to form a glass substrate with a conductive layer; wherein, the thickness of the conductive layer is 25nm;

[0106] D. A glass substrate with a conductive layer is electroplated with copper to obtain a glass substrate with a metallic layer; wherein the electroplating current density is 2.5 A / dm³. 2 The electroplating time is 30 minutes.

[0107] Comparative Example 1

[0108] Comparative Example 1 uses the same method and raw materials as Example 1, except that steps A and B are omitted in Comparative Example 1.

[0109] Comparative Example 2

[0110] Comparative Example 2 uses poly-2-acrylamide-2-methylpropanesulfonic acid instead of the modified silane coupling agent, and the remaining raw materials are the same as in Example 1, i.e., Comparative Example 2 is as follows:

[0111] A. Graphite powder, sodium dodecyl sulfonate, and water are mixed evenly, and graphene is obtained after ball milling, ultrasonication, filtration, washing, and drying. Graphene is mixed evenly with ethanol to obtain a graphene solution with a graphene content of 2%. Poly(2-acrylamide-2-methylpropanesulfonic acid) (a binding agent) at a mass ratio of 1:60 is mixed with the graphene solution to obtain a binding agent-graphene composite solution.

[0112] B. A binding agent-graphene composite liquid is coated onto the surface of an activated glass substrate to obtain a binding agent-graphene composite base layer; the above steps are repeated 10 times to obtain a binding agent-graphene composite coating; a high-energy laser with a scanning energy of 5 KeV and a scanning speed of 50000 pts / s is used to dry the binding agent-graphene composite coating to form a glass substrate with a conductive layer; wherein the thickness of the conductive layer is 20 nm.

[0113] C. Copper plating is performed on an insulating substrate with a conductive layer to obtain a glass substrate with a metallic layer; wherein the electroplating current density is 3 A / dm³. 2 The electroplating time is 40 minutes.

[0114] The surfaces of the insulating substrates with metal layers prepared in the examples and comparative examples were observed, and the peel strength between the insulating substrate and the metal layer was tested using a tensile testing machine. The test results are shown in the table below:

[0115] Example 1 flat and dense 308.12 Example 2 flat and dense 307.61 Example 3 flat and dense 304.25 Comparative Example 1 rough 213.81 Comparative Example 2 rough 262.44

[0116] As shown in the performance test results in the table above, the peel strength of both the insulating substrate and the metal layer in this embodiment is significantly higher than that in the comparative example. The peel strength between the insulating substrate and the metal layer is closely related to the interfacial bonding strength between them; a higher peel strength indicates a higher interfacial bonding strength, and vice versa. Therefore, the interfacial bonding strength between the insulating substrate and the metal layer in this embodiment is higher than that in traditional technologies where modified silane coupling agents are not used to improve the interfacial bonding strength, and also higher than in technical solutions that use bonding aids to improve the interfacial bonding strength but with poor results.

[0117] The technical principles of the present invention have been described above with reference to specific embodiments. These descriptions are merely for explaining the principles of the invention and should not be construed as limiting the scope of protection of the invention in any way. Based on this explanation, those skilled in the art can readily conceive of other specific embodiments of the invention without inventive effort, and these embodiments will all fall within the scope of protection of the present invention.

Claims

1. A method for enhancing the interfacial bonding strength between an insulating substrate and a metal layer, characterized in that, Includes the following steps: A. Grafting the modifier onto the silane coupling agent yields the modified silane coupling agent; The modified silane coupling agent is hydrolyzed to obtain a modified silane coupling agent hydrolysate; wherein the modifier contains unsaturated nitrogen or sulfur functional groups. B. The modified silane coupling agent hydrolysate is mixed with a graphene solution to obtain a modified silane coupling agent-graphene composite solution; the graphene content in the modified silane coupling agent-graphene composite solution is 0.01-10% by mass percentage. C. A modified silane coupling agent-graphene composite liquid is coated onto the surface of an insulating substrate to obtain a silane coupling agent-graphene composite coating. After drying, an insulating substrate with a conductive layer is formed. The insulating substrate contains functional groups that can react with hydroxyl groups. The specific drying method is as follows: the upper surface of the silane coupling agent-graphene composite coating is dried. The drying includes either high-energy laser scanning or high-temperature airflow baking. D. Electroplating an insulating substrate with a conductive layer yields an insulating substrate with a metal layer; In step A, the modifier includes any one of imidazole, 2-methylimidazolium, 2-phenylimidazolium, benzimidazole, benzotriazole, lysine, and thiourea; In step A, the silane coupling agent includes any one of vinyltriethoxysilane, vinyltrimethoxysilane, vinyltri(β-methoxyethoxy)silane, γ-aminopropyltriethoxysilane, 3-isocyanatetriethoxysilane, and anilinemethyltrimethylsilane.

2. The method for enhancing the interfacial bonding strength between an insulating substrate and a metal layer according to claim 1, characterized in that, In step A, the specific method of hydrolysis treatment is as follows: The first solvent and water are mixed evenly to obtain the first mixed solution; The first mixed solution was stirred, and a modified silane coupling agent was added dropwise during the stirring process to obtain a second mixed solution; The pH of the second mixed solution was adjusted to 1.5-6, and then the pH-adjusted second mixed solution was stirred until it was completely transparent to obtain the modified silane coupling agent hydrolysate. The first solvent includes either isopropanol or ethanol.

3. The method for enhancing the interfacial bonding strength between an insulating substrate and a metal layer according to claim 2, characterized in that, In the hydrolysis process, the mixing ratio of the first solvent to water is (5-10):1, calculated by mass ratio.

4. The method for enhancing the interfacial bonding strength between an insulating substrate and a metal layer according to claim 1, characterized in that, In step B, the graphene solution is prepared as follows: Graphene is obtained by uniformly mixing graphite powder, surfactant and water, followed by ball milling, ultrasonication, filtration, washing and drying. Graphene is mixed evenly with a second solvent to obtain a graphene solution.

5. The method for enhancing the interfacial bonding strength between an insulating substrate and a metal layer according to claim 4, characterized in that, In step B, the mixing ratio of the modified silane coupling agent hydrolysate and the graphene solution is 1:(1-100) by mass.

6. The method for enhancing the interfacial bonding strength between an insulating substrate and a metal layer according to claim 1, characterized in that, Step C specifically includes: C1. The modified silane coupling agent-graphene composite liquid is coated on the surface of an insulating substrate to obtain a silane coupling agent-graphene composite base layer. C2. Repeat steps C14 to 20 times to obtain a silane coupling agent-graphene composite coating, and after drying, form an insulating substrate with a conductive layer.

7. The method for enhancing the interfacial bonding strength between an insulating substrate and a metal layer according to claim 1, wherein in step C, the insulating substrate is a glass substrate, and step C specifically comprises: coating a modified silane coupling agent-graphene composite liquid onto the surface of a glass substrate that has undergone surface activation treatment to obtain a silane coupling agent-graphene composite coating, and drying the coating to form a glass substrate with a conductive layer.