Preparation method and application of flexible substrate chemical plating catalytic solution
The catalytic solution formed by the coordination of sodium hyaluronate with metal ions solves the pretreatment problem of flexible polymer substrates, and realizes a chemically coated layer with high adhesion, which is suitable for flexible electronic devices and biomedical sensors.
Patent Information
- Application Number
- CN202511052558.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-29
- Publication Date
- 2025-10-28
AI Technical Summary
Traditional chemical plating processes for surface pretreatment of flexible polymer substrates suffer from problems such as harsh conditions, low efficiency, easy corrosion, and environmental pollution, making it difficult to achieve metallization with high adhesion.
A catalytic solution using sodium hyaluronate as the core component forms a highly stable metal nanoparticle activation layer by coordinating its hydroxyl and carboxyl groups with metal ions. Combined with metal salt solution and ammonia, a chemical plating catalytic solution for flexible substrates is prepared, achieving a uniform and dense activation layer with high adhesion.
A uniform and dense activation layer is formed on the surface of a flexible substrate, which significantly improves the adhesion between the metal coating and the substrate, simplifies the process steps, is environmentally friendly, suitable for industrial production, and can be applied to flexible electronic devices and biomedical sensors.
Smart Images
Figure CN120844065A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of electroless plating technology, specifically relating to a method for preparing a catalytic solution for electroless plating of flexible substrates and its application. Background Technology
[0002] Electroless plating is a highly efficient and flexible technology for preparing surface metallization composite materials, attracting widespread attention due to its reliability and economy. This technology uses a strong reducing agent to induce an autocatalytic reduction reaction of metal ions in solution, ultimately forming a uniform metal deposition layer on the substrate surface. The core of electroless plating lies in the reducing agent providing electrons to reduce metal ions, causing them to deposit on the substrate surface in atomic form, thus achieving surface metallization without an applied current. This characteristic gives it significant advantages over traditional electroplating techniques, including simpler processes, no need for complex current control, simultaneous deposition in multiple areas, and deposition layers exhibiting excellent corrosion resistance, wear resistance, and high bonding strength with the substrate.
[0003] Traditional electroless plating processes mainly consist of three key steps: substrate surface pretreatment, catalyst layer preparation, and metal particle deposition. During electroless plating, metals such as Pd, Ag, and Cu are typically introduced as active sites. After adsorption on the substrate surface, these metals undergo autocatalytic reduction in the plating solution, causing the metal cations to deposit and form a coating. Substrate surface pretreatment is a crucial step in this process, primarily enhancing the adsorption and stability of the catalyst sites on the substrate surface. Currently, commonly used pretreatment methods include acid etching and strong oxidants (such as the HNO3 / H2SO4 etching system). Through etching, hollow structures and hydrophilic groups (such as -OH and -COOH) can be formed on the substrate surface. These groups not only facilitate the adhesion of catalyst particles to the substrate through coordination bonds and physical adsorption but also significantly improve the adhesion between the substrate and the coating. However, for flexible polymer substrates, traditional etching methods suffer from harsh conditions and low efficiency, and the substrate is prone to corrosion and deformation after long-term exposure to the etching solution. Furthermore, acid etching and strong oxidant systems are also controversial in terms of environmental protection, potentially causing environmental pollution and generating carcinogenic risks, making it difficult to regard them as a sustainable green process.
[0004] Therefore, how to develop a new catalytic solution that can achieve good adhesion to flexible polymer substrates after surface pretreatment, avoid the chemical corrosion risks of traditional sulfonation, and simultaneously achieve substrate modification and catalytic site introduction has become an urgent problem to be solved. Summary of the Invention
[0005] To address the problems existing in the background technology, the present invention aims to provide a method for preparing a catalytic solution for electroless plating of flexible substrates and its application. This catalytic solution uses sodium hyaluronate as the core component, combined with a metal salt solution and ammonia to form a unique catalytic solution system. By utilizing the coordination of the hydroxyl and carboxyl groups in the sodium hyaluronate molecules with metal ions, highly stable metal nanoparticles are generated, forming a uniform and dense activation layer on the surface of the flexible substrate. This activation layer not only provides a high density of active sites for subsequent electroless plating but also significantly improves the adhesion between the metal coating and the substrate, thereby optimizing the metallization performance of the flexible substrate.
[0006] To achieve the above objectives, the technical solution of the present invention is as follows:
[0007] A method for preparing a chemical plating catalytic solution for flexible substrates includes the following steps:
[0008] Step 1. Place sodium hyaluronate in a glass container, add solvent, and stir at a certain temperature until the mixture is homogeneous;
[0009] Step 2. Add the metal salt solution to the mixed solution obtained in Step 1, and then stir at a certain temperature until the mixture is homogeneous;
[0010] Step 3. Add ammonia water dropwise to adjust the pH to 9-10, and stir at a certain temperature until the mixture is homogeneous to obtain a chemical plating catalytic solution for flexible substrates containing metal particles.
[0011] Furthermore, in step 1, the solvent is any one or a mixture of two of the following in any proportion: deionized water, ethanol, and ethylene glycol.
[0012] Furthermore, the temperature in step 1 is 50-60℃; the temperature in step 2 is 40-60℃; and the temperature in step 3 is 30-40℃.
[0013] Furthermore, in step 1, the concentration of sodium hyaluronate in the mixed solution is 7.5-9 g / L; in step 2, the concentration of the metal salt in the mixed solution is 3-5 g / L.
[0014] Furthermore, in step 3, the metal particles are Ag, Pb, etc.
[0015] Furthermore, in step 2, the preferred metal salt solution is silver nitrate (AgNO3) or palladium chloride (PbCl2).
[0016] This invention also provides applications based on the above-mentioned catalytic solution, the specific process of which is as follows:
[0017] S1. Cleaning the flexible substrate: First, ultrasonically clean and dry the flexible substrate, then treat it with air plasma.
[0018] S2. Perform surface pretreatment on the cleaned flexible substrate:
[0019] The cleaned flexible substrate is coated with a catalytic solution and left at room temperature for 10-15 minutes to promote initial solvent evaporation and liquid layer stabilization, and enhance the interfacial bonding between the substrate and the catalytic solution. The substrate is then placed in an oven at 40-50℃ and dried for 1-2 hours to completely remove residual solvent and fix the catalytic layer structure. The flexible substrate is then soaked in deionized water to remove the catalytic solution with poor adhesion, and then taken out and dried.
[0020] S3. Chemical copper plating:
[0021] The pretreated flexible substrate is placed in a chemical copper plating solution to deposit copper. During the chemical copper plating process, air is introduced into the plating solution and magnetic stirring is performed. The solution is heated in a water bath and after a period of reaction, a substrate product with copper deposited on the surface is obtained.
[0022] S4. Rinse the substrate product obtained in S3 with deionized water to remove the residual chemical copper plating solution on the surface, and then dry it to obtain a flexible substrate with copper plating on the surface.
[0023] Furthermore, the flexible substrate is a PEEK film, a PI film, or an FR-4 epoxy glass cloth laminate.
[0024] Furthermore, in S1, the processing power of the air plasma treatment is 100-150W, and the processing time is 10-20min.
[0025] Furthermore, the formulation of the electroless copper plating solution is as follows: 32-36 g / L potassium sodium tartrate tetrahydrate, 2.5-2.8 g / L disodium ethylenediaminetetraacetate dihydrate, 12.5-13 g / L copper sulfate pentahydrate, 3-3.5 g / L nickel sulfate hexahydrate, 10-10.5 mg / L 2,2'-bipyridine, 25-28 mg / L potassium ferrocyanide trihydrate, 10-12 g / L sodium hydroxide, and 6-8 ml / L formaldehyde solution; the air flow rate blown into the plating solution during the electroless copper plating process is 1.5-3.5 cm. 3 The copper plating solution temperature is controlled between 30 and 36°C, and the chemical copper plating time is 20-25 minutes.
[0026] The advantages of the catalytic solution formulation of this invention stem from the molecular structural characteristics of sodium hyaluronate and the multiple synergistic mechanisms it constructs in the system: the flexible polymer chains of sodium hyaluronate have excellent physicochemical compatibility with flexible substrates such as PEEK, PI, and PET, and can achieve uniform dispersion and spreading on the substrate surface, forming a stable interface environment without phase separation; at the same time, the high-density carboxyl and hydroxyl groups in the molecule construct a three-dimensional network through polar hydrogen bonding, which can selectively capture metal cations and inhibit the aggregation of metal particles through the negative charge repulsion effect, and also promote the nanoscale uniform dispersion of active metal particles in the catalytic solution, ensuring its high uniformity loading on the substrate surface. Building upon this foundation, sodium hyaluronate forms a uniform and dense adsorption layer on the substrate surface through its molecular chain film-forming properties. Its polar groups interact strongly with the substrate functional groups, significantly enhancing the adhesion of metal particles and creating a highly active catalytic interface for the electroless plating reaction. Meanwhile, the metal particles, acting as catalytic sites, are embedded between the hyaluronic acid chains. Combined with the high viscosity of the solution and the negative charge effect generated by molecular chain ionization, this dually inhibits particle agglomeration and deactivation, giving the catalytic solution both stable particle control and dispersion capabilities and long-term protective performance. This multi-dimensional synergistic effect ultimately achieves the core advantages of the catalytic solution: precise anchoring of active sites, uniform regulation of nucleation sites, and long-term maintenance of catalytic activity. It ensures strong adhesion and dense growth of the electroless plating layer on the flexible substrate surface, while overcoming the coating quality defects caused by particle agglomeration and poor interfacial compatibility in traditional catalytic solutions. This provides a scientifically sound and engineering-valued solution for the surface functionalization of flexible electronic devices.
[0027] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:
[0028] Sodium hyaluronate in this invention, due to its natural polymer structure, possesses excellent film-forming properties and flexibility, making it compatible with various flexible substrates. The catalytic solution can form a uniform catalytic layer on the substrate surface through a simple coating process, providing an ideal active basis for subsequent electroless nickel or copper plating processes. Compared with traditional catalytic solutions, the catalytic solution of this invention does not require the use of toxic or hazardous chemicals during preparation, is simple to operate, and is environmentally friendly, making it suitable for industrial-scale production. During the electroless plating process, sodium hyaluronate not only effectively stabilizes metal nanoparticles but also prevents particle aggregation through its steric hindrance effect, thereby ensuring the uniformity and density of the coating. Flexible substrate metallized materials treated with this catalytic solution exhibit excellent stability and mechanical stability, and can be widely used in flexible electronic devices and biomedical sensors. Attached Figure Description
[0029] Figure 1 This is a schematic diagram of the preparation process of the chemical plating catalytic solution for a flexible substrate containing silver particles in Example 1 of the present invention.
[0030] Figure 2 This is a physical image of the catalytic solution prepared in Example 1 of the present invention.
[0031] Figure 3 This is a SEM image of Ag particles in the catalytic solution prepared in Example 1 of the present invention.
[0032] Figure 4 This is a metallographic microscope image of the flexible substrate coated with the catalytic solution in Example 2 of the present invention.
[0033] Figure 5 This is a SEM image of the surface of the electroless copper plating layer prepared in Example 2 of the present invention.
[0034] Figure 6 The image shows the adhesion test results of the chemically plated copper layer prepared in Example 2 of this invention.
[0035] Figure 7 This is a physical image of the catalytic solution prepared in Example 3 of the present invention. Detailed Implementation
[0036] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the embodiments and accompanying drawings.
[0037] Example 1
[0038] A method for preparing a chemical plating catalytic solution for a flexible substrate containing silver particles, the process flow diagram of which is shown below. Figure 1 As shown, it includes the following steps:
[0039] Step 1. Place 0.15g of sodium hyaluronate (HA) in a glass bottle, add 20ml of deionized water, and stir magnetically at 60℃ for 4 hours until the mixture is homogeneous.
[0040] Step 2. Add 0.06 g AgNO3 solution to the mixed solution obtained in Step 1, and then stir at 60 °C for 2 h until the mixture is homogeneous;
[0041] Step 3. Add ammonia water dropwise and stir at 40°C for 1 hour until the mixture is homogeneous to obtain a chemical plating catalytic solution for flexible substrates containing metal particles.
[0042] A physical image of the catalytic solution prepared in this embodiment is shown below. Figure 2 As shown in the figure, the catalyst solution exhibits a uniform and stable yellow transparent solution state. This appearance effectively indicates that the silver nanoparticles have been synthesized in a controllable manner in the solution and have achieved good dispersion stability, forming a uniform nanoparticle dispersion system without obvious agglomeration.
[0043] SEM images of Ag particles in the catalytic solution are shown below. Figure 3As shown in the figure, the silver particles are nanoscale in size, with a particle size distribution ranging from 50 to 150 nm. The morphology is mainly ellipsoidal, and the overall dispersion is good. The particle boundaries are clear, with no obvious sintering and fusion phenomenon, showing good size uniformity and structural integrity.
[0044] The catalyst layer prepared by this invention already contains metal nanoparticles that can serve as catalytic sites. Compared with the traditional "catalytic layer containing metal complexes with catalytic active sites", the catalyst layer prepared by the latter cannot be directly used as an active site. Other methods (such as plasma treatment, laser activation, wet chemical reducing agent method, etc.) are required to reduce the metal complex to elemental metal as a metal active site. Therefore, the preparation method of this invention also has the advantage of simplifying the preparation process.
[0045] Example 2
[0046] The copper plating method for flexible substrates based on catalytic solutions is as follows:
[0047] S1. Cleaning the flexible substrate: Place the PEEK film in a beaker containing anhydrous ethanol for ultrasonic cleaning, then rinse with deionized water to remove residual ethanol on the substrate surface, and then dry it in an oven to obtain a clean PEEK film.
[0048] The clean PEEK film is then placed in a plasma cleaner for air plasma treatment at a power of 150W for 10 minutes.
[0049] S2. Perform surface pretreatment on the cleaned PEEK film:
[0050] The cleaned PEEK film was coated with a catalytic solution and left at room temperature for 15 minutes; then the substrate was placed in an oven and dried at 50°C for 2 hours; then the flexible substrate was soaked in deionized water to remove the catalytic solution with poor adhesion, and then taken out and dried.
[0051] Metallographic micrograph of the substrate coated with the catalytic solution as shown in the figure. Figure 4 As shown in the figure, the substrate coated with the catalytic solution exhibits a typical porous network structure, forming an open three-dimensional network structure. This structural feature indicates that the catalytic solution forms a uniform dispersed phase on the substrate surface. The high-density distribution and connectivity of the pores are beneficial for increasing the contact area between the catalyst and the reactants, thereby improving mass transport efficiency. Its porous characteristics have a positive effect on adsorption, mass transfer, and exposure of active sites in the catalytic reaction. The overall structural integrity and uniformity are good, with no obvious cracking or agglomeration observed, demonstrating the effectiveness of the coating process and the suitability of the catalyst support.
[0052] S3. Chemical copper plating:
[0053] The pretreated PEEK film was placed in a chemical copper plating solution to deposit copper. The chemical copper plating solution was formulated as follows: 32 g / L potassium sodium tartrate tetrahydrate, 2.5 g / L disodium ethylenediaminetetraacetate dihydrate, 12.5 g / L copper sulfate pentahydrate, 3.5 g / L nickel sulfate hexahydrate, 10 mg / L 2,2'-bipyridine, 25 mg / L potassium ferrocyanide trihydrate, 10 g / L sodium hydroxide, and 8 ml / L formaldehyde solution.
[0054] In the electroless copper plating process, air is introduced into the plating solution at a flow rate of 2 cm³. 3 The mixture is stirred magnetically at a constant rate of 1 min, heated in a water bath at a temperature controlled at 35°C, and after 25 min of reaction, a substrate product with copper deposited on the surface is obtained.
[0055] S4. Rinse the substrate product obtained in S3 with deionized water to remove the residual chemical copper plating solution on the surface, then place it in an oven and dry it at 60°C to obtain a flexible substrate with copper plating on the surface.
[0056] The SEM image of the copper plating layer prepared in this embodiment is shown below. Figure 5 As shown, the copper layer consists of a large number of relatively uniform particles that are dispersed from each other without obvious agglomeration. The surface is relatively smooth overall, and the density and uniformity of the plating are very good.
[0057] The surface adhesion test diagram of the copper plating layer prepared in this embodiment is shown below. Figure 6 As shown in the three figures, the complete process and results of the electroless copper plating adhesion test are presented: the first figure is the original copper layer before testing, the second figure is the copper layer after testing by the tape peeling method, and the third figure is the peeled tape. It can be seen that there was no large-area peeling during the peeling process, and there was no large amount of copper layer falling off the tape, indicating that the coating obtained by electroless plating after treatment with the catalytic solution of the present invention has good adhesion.
[0058] Example 3
[0059] A method for preparing a chemical plating catalytic solution for a flexible substrate containing palladium particles includes the following steps:
[0060] Step 1. Place 0.3g of sodium hyaluronate (HA) in a glass bottle, add 20ml of deionized water, and magnetically stir at 60℃ for 4 hours until the mixture is homogeneous;
[0061] Step 2. Add 0.02g of PbCl2 solution to the mixed solution obtained in Step 1, and then stir at 40℃ for 2 hours until the mixture is homogeneous;
[0062] Step 3. Add HCl dropwise and stir at 40°C for 1 hour until the mixture is homogeneous to obtain a chemical plating catalytic solution for flexible substrates containing metal particles.
[0063] A physical image of the catalytic solution prepared in this embodiment is shown below. Figure 7 As shown, the catalyst solution exhibits a uniform and stable yellow transparent liquid state. This characteristic indicates that palladium nanoparticles have been synthesized in a controllable manner in solution, and its dispersion system has good stability, forming a uniform nanoparticle dispersion phase without obvious agglomeration.
[0064] The above description is merely a specific embodiment of the present invention. Any feature disclosed in this specification may be replaced by other equivalent or similar features unless otherwise specified. All disclosed features, or steps in all methods or processes, may be combined in any way except for mutually exclusive features and / or steps.
Claims
1. A method for preparing a chemical plating catalytic solution for a flexible substrate, characterized in that, Includes the following steps: Step 1. Place sodium hyaluronate in a glass container, add solvent, and stir at a certain temperature until the mixture is homogeneous; Step 2. Add the metal salt solution to the mixed solution obtained in Step 1, and then stir at a certain temperature until the mixture is homogeneous; Step 3. Add ammonia water dropwise to adjust the pH to 9-10, and stir at a certain temperature until the mixture is homogeneous to obtain a chemical plating catalytic solution for flexible substrates containing metal particles.
2. The method for preparing the flexible substrate chemical plating catalytic solution as described in claim 1, characterized in that, In step 1, the solvent is any one or a mixture of two of the following: deionized water, ethanol, and ethylene glycol, in any proportion.
3. The method for preparing the flexible substrate electroless plating catalytic solution as described in claim 1, characterized in that, The temperature in step 1 is 50-60℃; the temperature in step 2 is 40-60℃; and the temperature in step 3 is 30-40℃.
4. The method for preparing the flexible substrate electroless plating catalytic solution as described in claim 1, characterized in that, In step 1, the concentration of sodium hyaluronate in the mixed solution is 7.5-9 g / L; in step 2, the concentration of the metal salt in the mixed solution is 3-5 g / L.
5. The method for preparing the flexible substrate chemical plating catalytic solution as described in claim 1, characterized in that, In step 3, the metal particles are Ag or Pb.
6. The method for preparing the flexible substrate electroless plating catalytic solution as described in claim 1, characterized in that, In step 2, the metal salt solution is silver nitrate or palladium chloride.
7. An application of a catalytic solution prepared by the method for preparing a flexible substrate chemical plating catalytic solution according to any one of claims 1-6, characterized in that, The specific application process is as follows: S1. Cleaning the flexible substrate: First, ultrasonically clean and dry the flexible substrate, then treat it with air plasma. S2. Perform surface pretreatment on the cleaned flexible substrate: The cleaned flexible substrate is coated with a catalytic solution and left at room temperature for 10-15 minutes. Then, the substrate is placed in an oven at 40-50°C and dried for 1-2 hours. After that, the flexible substrate is soaked in deionized water, taken out and blown dry. S3. Chemical copper plating: The pretreated flexible substrate is placed in a chemical copper plating solution to deposit copper. During the chemical copper plating process, air is introduced into the plating solution and magnetic stirring is performed. The solution is heated in a water bath and after a period of reaction, a substrate product with copper deposited on the surface is obtained. S4. Rinse the substrate product obtained in S3 with deionized water to remove the residual chemical copper plating solution on the surface, and then dry it to obtain a flexible substrate with copper plating on the surface.
8. The application as described in claim 7, characterized in that, The flexible substrate is a PEEK film, a PI film, or an FR-4 epoxy glass cloth laminate.
9. The application as described in claim 7, characterized in that, In S1, the processing power of air plasma treatment is 100-150W, and the processing time is 10-20min.
10. The application as described in claim 7, characterized in that, The formula for the electroless copper plating solution is as follows: 32-36 g / L potassium sodium tartrate tetrahydrate, 2.5-2.8 g / L disodium ethylenediaminetetraacetate dihydrate, 12.5-13 g / L copper sulfate pentahydrate, 3-3.5 g / L nickel sulfate hexahydrate, 10-10.5 mg / L 2,2'-bipyridine, 25-28 mg / L potassium ferrocyanide trihydrate, 10-12 g / L sodium hydroxide, and 6-8 ml / L formaldehyde solution. During the electroless copper plating process, the air flow rate blown into the plating solution is 1.5–3.5 cm. 3 The copper plating solution temperature is controlled between 30 and 36°C, and the chemical copper plating time is 20-25 minutes.