Chemical and electrochemical combined alkaline copper plating method
By combining chemical and electrochemical methods in alkaline copper plating, the reactive sites generated by electrochemical reduction and nickel ion complexing agents are utilized to solve the problems of low efficiency and weak adhesion in alkaline copper plating. This achieves efficient copper deposition and a smooth copper layer, avoids blistering, simplifies the process, and improves environmental friendliness.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-03
- Publication Date
- 2026-03-03
AI Technical Summary
Existing alkaline copper plating methods suffer from low copper plating efficiency and weak copper layer adhesion, especially during high-speed copper plating, which can easily lead to copper layer bulging.
An alkaline copper plating method combining chemical and electrochemical processes is adopted. By adding copper salt, a first complexing agent, nickel salt, and diethylenetriaminepentaacetic acid (DICA), a strong nickel ion complexing agent, to an aqueous electrolyte, the pH value is adjusted to above 7.5, and intermittent electrolysis is performed. The reactive sites generated by electrochemical reduction promote chemical copper deposition, omitting the sensitization and activation steps.
It improves the copper plating rate, strengthens the adhesion between the copper layer and the substrate, avoids copper layer bulging, simplifies the process, and is environmentally friendly.
Smart Images
Figure CN121593045A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to a copper plating method, specifically an alkaline copper plating method combining chemical and electrochemical processes, belonging to the field of chemical copper plating technology. Background Technology
[0002] Alkaline copper plating does not damage substrates sensitive to acidic environments and can suppress various side reactions, such as displacement reactions, thereby enhancing the adhesion between the substrate and the plating layer. Compared to acidic copper plating, it is irreplaceable in specific applications. Existing alkaline copper plating methods include chemical and electrochemical methods. Chemical methods mainly use formaldehyde, sodium hypophosphite, etc., as reducing agents, while electrochemical methods use electrons as reducing agents. Chemical methods require pre-treatment steps such as sensitization and activation to create active sites on the substrate that are conducive to the reduction of copper ions. Electrochemical methods have many limitations on the choice of complexing agents. Previously, cyanide copper plating was used; now, non-cyanide copper plating has been developed. However, due to the limitation of the chelating agent on the stability constant of copper ions, the limiting current density for copper plating is relatively low, resulting in low plating efficiency. Other alkaline electroplating copper processes, such as pyrophosphate copper plating, also have the same problem. In summary, low plating efficiency is the main problem currently restricting alkaline copper plating processes. Forcibly increasing the plating speed will lead to a sharp decline in copper layer quality, with very obvious blistering. In addition, the traditional alkaline copper plating method mentioned above also has the problem of weak coating adhesion and easy copper layer bulging under high-speed copper plating conditions. Summary of the Invention
[0003] The main objective of this invention is to provide an alkaline copper plating method that combines chemical and electrochemical processes to overcome the shortcomings of existing technologies.
[0004] To achieve the above-mentioned objectives, the present invention adopts the following technical solution:
[0005] This invention provides an alkaline copper plating method combining chemical and electrochemical processes, comprising:
[0006] An aqueous electrolyte is provided, the aqueous electrolyte comprising a copper salt, a first complexing agent, a nickel salt, and a second complexing agent, wherein the second complexing agent is a strong nickel ion complexing agent;
[0007] Adjust the pH of the aqueous electrolyte to above 7.5 and add a reducing agent;
[0008] A copper plating system is constructed by using a conductive substrate as the cathode, a counter electrode, and an aqueous electrolyte with added reducing agent. Intermittent energizing is then applied to deposit a copper layer on the surface of the conductive substrate.
[0009] In some embodiments, the second complexing agent comprises diethylenetriaminepentaacetic acid.
[0010] In some embodiments, the conditions for depositing the copper layer include: an electrolyte temperature of 25°C to 70°C and a current density of 5 A / m. 2 ~1000 A / m 2 For every 10 minutes of power-on and 1 to 2 minutes of power-off, the copper layer growth rate is 0.1 μm / min to 5 μm / min.
[0011] Compared with existing alkaline copper plating processes, the advantages of this invention are as follows:
[0012] This invention employs an alkaline copper plating method that organically combines two traditionally completely different copper plating technologies: chemical copper plating and electrochemical copper plating. This addresses the low efficiency of alkaline copper plating by utilizing electrochemical reduction to rapidly generate reactive sites, allowing chemical copper plating to occur simultaneously. This results in a higher copper plating rate than either chemical or electrochemical copper plating alone. Furthermore, at this higher plating rate, the resulting copper layer exhibits excellent adhesion to the substrate (tested using the cross-cut adhesion method, achieving a surface peel strength of 5B), reducing the likelihood of copper layer blistering. Simultaneously, it eliminates the sensitization and activation steps required in traditional chemical copper plating, simplifying the copper plating process. Attached Figure Description
[0013] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0014] Figure 1 This is a reaction mechanism diagram of a rapid alkaline copper plating process combining chemical and electrochemical methods in a typical embodiment of the present invention.
[0015] Figure 2 A photograph of the copper plating layer on the surface of a sample obtained under the conditions of Example 1 of the present invention;
[0016] Figure 3 A photograph of the copper plating layer on the surface of the sample obtained under the conditions of Example 2 of the present invention;
[0017] Figure 4 A photograph of the copper plating layer on the surface of the sample obtained under the conditions of Example 3 of the present invention;
[0018] Figure 5 A photograph of the copper plating layer on the surface of the sample obtained under the conditions of Example 4 of the present invention;
[0019] Figure 6 A photograph of the copper plating layer on the surface of the sample obtained under the conditions of Example 5 of the present invention;
[0020] Figure 7 The image shows the actual copper plating layer on the surface of the sample obtained under the conditions of Comparative Example 1.
[0021] Figure 8 The image shows the actual copper plating layer on the sample surface obtained under the conditions of Comparative Example 2.
[0022] Figure 9 The image shows the actual copper plating layer on the surface of the sample obtained under the conditions of Comparative Example 3.
[0023] Figure 10 The image shows the actual copper plating layer on the sample surface obtained under the conditions of Comparative Example 4.
[0024] Figure 11 The image shows the actual copper plating layer on the surface of the sample obtained under the conditions of Comparative Example 5.
[0025] Figure 12 The image shows the actual copper plating layer on the surface of the sample obtained under the conditions of Comparative Example 6.
[0026] Figure 13 The image shows the actual copper plating layer on the surface of the sample obtained under the conditions of Comparative Example 7.
[0027] Figure 14 This is a photograph of the copper plating layer on the surface of the sample obtained under the conditions of Comparative Example 8. Detailed Implementation
[0028] Given the generally low efficiency of alkaline copper plating, and the fact that applicable copper ion reduction methods are mostly simple chemical reducing agents or electrochemical reduction, the inventors of this invention, through long-term research and extensive practice, have proposed the technical solution of this invention. This solution primarily combines chemical and electrochemical methods, utilizing electrochemical reduction to rapidly generate reactive sites, allowing chemical copper plating to occur simultaneously, resulting in higher efficiency than either chemical or electrochemical copper plating alone. The resulting copper layer exhibits good adhesion to the substrate and is less prone to copper layer blistering.
[0029] The following will further explain the technical solution, its implementation process, and its principles. However, it should be understood that within the scope of this invention, the above-mentioned technical features of this invention and the technical features specifically described below (in embodiments) can be combined with each other to form new or preferred technical solutions. Due to space limitations, they will not be described in detail here.
[0030] As one aspect of the technical solution of this invention, a combined chemical and electrochemical alkaline copper plating method includes:
[0031] An aqueous electrolyte is provided, the aqueous electrolyte comprising a copper salt, a first complexing agent, a nickel salt, and a second complexing agent, wherein the second complexing agent is a strong nickel ion complexing agent;
[0032] Adjust the pH of the aqueous electrolyte to above 7.5 and add a reducing agent;
[0033] A copper plating system is constructed by using a conductive substrate as the cathode, a counter electrode, and an aqueous electrolyte with added reducing agent. Intermittent energizing is then applied to deposit a copper layer on the surface of the conductive substrate.
[0034] In some embodiments, the present invention employs a combination of chemical and electrochemical methods for alkaline copper plating, with the main components of the plating bath including a small amount of ionic additives, such as copper salts and nickel salts, which provide copper ions.
[0035] In some embodiments, the first complexing agent added to the aqueous electrolyte of the present invention may include one or more combinations of urea, sodium citrate, disodium ethylenediaminetetraacetate (EDTA-2Na), potassium sodium tartrate, and boric acid, but is not limited thereto. Compared with the traditional alkaline copper plating process, the copper plating efficiency of the present invention is significantly improved. Furthermore, in the selection of the electrolyte complexing agent, there is no need to consider traditional pyrophosphates, cyanides, and other hydrogen-free copper plating complexing agents that still have significant polluting properties, thus greatly improving the environmental friendliness of the process.
[0036] In some embodiments, the second complexing agent added to the aqueous electrolyte of the present invention is diethylenetriaminepentaacetic acid (DTA). Because DTA has an extremely high stability constant for nickel ions and exhibits stability under alkaline conditions, as well as excellent selectivity for nickel ions, a strong nickel ion complexing agent, DTA, is additionally added. This ensures that the trace amounts of nickel ions promote copper ion deposition without being diminished by the formation of inert nickel oxides through side reactions, thereby guaranteeing the stability of the reaction.
[0037] Please see Figure 1 As shown, with the conductive substrate to be plated with copper as the cathode, the following reaction occurs on the substrate surface when energized:
[0038] Cu 2+ + 2e → Cu↓
[0039] Ni 2+ + 2e → Ni↓
[0040] The tiny copper crystals produced by electrochemical reduction, due to their mesoscopic characteristics, have many defects and high surface energy, which become active sites for chemical copper plating. This makes it easier for chemical copper plating to occur at these sites through chemical reactions, greatly improving the copper plating efficiency.
[0041] However, another problem typically exists in the copper deposition process after energization: the resulting nickel metal crystals, due to cathodic protection, have increased difficulty in undergoing a displacement reaction with copper ions. Normally, in a conventional electroless plating process, the following reaction occurs:
[0042] Ni + Cu 2+ →Ni 2+ + Cu↓
[0043] This reaction can significantly improve the reduction efficiency of copper ions and enhance the compactness of the resulting copper layer. To maintain Ni... 2+ The electrochemical process in this invention is optimized to promote the copper deposition process. Specifically, the current is briefly stopped during the electrodeposition process, allowing nickel ions to fully react with copper ions in the electrolyte and enhancing the effect.
[0044] In general, this invention employs two methods for reducing copper ions: electrochemical reduction and chemical reduction, using electrons and formaldehyde and sodium hypophosphite as reducing agents, respectively. Simultaneously, this invention contains two active sites that promote copper deposition: extremely small copper crystals generated by electrochemical reduction, and displacement-active sites generated by nickel deposition. This makes the copper plating efficiency of this invention superior to traditional alkaline copper plating methods. Furthermore, the abundance of active sites helps improve the adhesion between the copper layer and the substrate, preventing copper layer bulging during high-speed copper plating.
[0045] In some preferred embodiments, the concentration of disodium ethylenediaminetetraacetate in the aqueous electrolyte is 2 g / L to 80 g / L, the concentration of potassium sodium tartrate is 1 g / L to 50 g / L, the concentration of sodium citrate is 0.5 g / L to 60 g / L, the concentration of urea is 8 g / L to 46 g / L, and the concentration of boric acid is 5 g / L to 60 g / L.
[0046] In some preferred embodiments, the copper salt in the aqueous electrolyte contains Cu 2+ The concentration ranges from 1 g / L to 90 g / L.
[0047] Furthermore, the copper salt can be copper sulfate, copper chloride, copper nitrate, etc., but is not limited to these.
[0048] In some preferred embodiments, the nickel salt in the aqueous electrolyte contains Ni 2+ The concentration ranges from 0.1 g / L to 10 g / L.
[0049] Furthermore, the nickel salt can be nickel sulfate, nickel chloride, nickel nitrate, etc., but is not limited to these.
[0050] In some preferred embodiments, the concentration of the strong nickel ion complexing agent is 5 g / L to 50 g / L.
[0051] In some preferred embodiments, the alkaline copper plating method specifically includes adjusting the pH value of the aqueous electrolyte to be between 7.5 and 13.
[0052] In some embodiments, the reducing agent may include one or a combination of two of formaldehyde, sodium hypophosphite, etc., but is not limited thereto.
[0053] In some preferred embodiments, the amount of formaldehyde added is 1 mL / L to 50 mL / L, compared to an aqueous electrolyte.
[0054] In some preferred embodiments, the concentration of sodium hypophosphite in the aqueous electrolyte containing the reducing agent is 1 g / L to 60 g / L.
[0055] In some preferred embodiments, the conditions for depositing the copper layer include: an electrolyte temperature of 25°C to 70°C and a current density of 5 A / m. 2 ~1000 A / m 2 For every 10 minutes of power-on and 1 to 2 minutes of power-off, the copper layer growth rate is 0.1 μm / min to 5 μm / min.
[0056] Furthermore, the conductive substrate includes, but is not limited to, a metal substrate or a carbon substrate.
[0057] Furthermore, the counter electrode includes, but is not limited to, lead plates or titanium-coated anodes.
[0058] Furthermore, the copper layer is dense and flat, and it is firmly bonded to the conductive substrate without any bulging.
[0059] In some more specific implementation schemes, an alkaline copper plating method combining chemical and electrochemical processes includes the following steps:
[0060] Step 1: Prepare the aqueous electrolyte for the chemical-electrochemical combined alkaline copper plating technology of the present invention, wherein the electrolyte contains Cu. 2+ The concentration is 1 g / L to 90 g / L. The complexing agent used is one or more of the following: disodium ethylenediaminetetraacetate (concentration 2 g / L to 80 g / L), potassium sodium tartrate (concentration 1 g / L to 50 g / L), sodium citrate (concentration 0.5 g / L to 60 g / L), urea (concentration 8 g / L to 46 g / L), and boric acid (concentration 5 g / L to 60 g / L). Nickel ions (concentration 0.1 g / L to 10 g / L) are added, along with diethylenetriaminepentaacetic acid (concentration 5 g / L to 50 g / L).
[0061] Step 2: Adjust the pH of the electrolyte to a value between 7.5 and 13;
[0062] Step 3: Before copper plating, add a reducing agent, which can be formaldehyde (1 mL / L~50 mL / L) or sodium hypophosphite (1 g / L~60 g / L).
[0063] Step 4: Use the conductive metal or carbon substrate to be copper-plated as the cathode, and a lead plate or titanium-coated anode as the counter electrode. During copper plating, control the electrolyte temperature between 25°C and 70°C. The current density should be between 5 A / m². 2 ~1000 A / m 2 The copper plating process involves applying power for 10 minutes and then de-energizing for 1 to 2 minutes. The copper plating time can be adjusted as needed without a specific limit. The copper layer growth rate varies from 0.1 μm / min to 5 μm / min depending on the current and reducing agent concentration. The resulting copper layer is dense and smooth, firmly bonded to the substrate, and free from blistering.
[0064] Compared to electroless copper plating, this invention features intermittent energization; compared to electrochemical copper plating, this invention uses reducing agents such as formaldehyde and sodium hypophosphite, which are not used in electroplating; furthermore, compared to alkaline cyanide-free copper plating, this invention contains nickel ion additives.
[0065] In summary, compared with existing alkaline copper plating processes, whether it is pyrophosphate, cyanide or cyanide-free electroplating copper, or simple chemical copper plating, all have a higher copper deposition rate. Moreover, at a higher copper deposition rate, the copper layer can still have better and stronger adhesion to the substrate and is less prone to blistering.
[0066] To facilitate understanding of the present invention, it will be described in more detail below. However, it should be understood that the present invention can be implemented in many different forms and is not limited to the embodiments or examples described herein. Rather, these embodiments or examples are provided to make the disclosure of the present invention more thorough and complete.
[0067] 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 invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments or examples only and is not intended to be limiting of the invention.
[0068] Unless otherwise specified, the raw materials and reagents used in the embodiments of this application were all purchased commercially.
[0069] Example 1
[0070] Prepare an aqueous electrolyte for alkaline copper plating using a combination of chemical and electrochemical methods, containing copper chloride (Cu).2+ The electrolyte concentration was 1 g / L. The complexing agents used were disodium ethylenediaminetetraacetate (2 g / L), potassium sodium tartrate (1 g / L), sodium citrate (0.5 g / L), urea (8 g / L), and boric acid (5 g / L). Nickel chloride (nickel ions) (0.1 g / L) and diethylenetriaminepentaacetic acid (5 g / L) were added. The pH of the electrolyte was adjusted to 7.5. Before copper plating, sodium hypophosphite (60 g / L) was added as a reducing agent. The conductive metal to be plated with copper was used as the cathode, and a lead plate as the counter electrode. During copper plating, the electrolyte temperature was controlled at 70℃, and the current density was 5 A / m. 2 With power off for 2 minutes every 10 minutes, the copper layer growth rate was 0.1 μm / min. The resulting copper layer was dense and smooth, firmly bonded to the substrate, and showed no bulging. Figure 2 This is a photograph of the copper plating layer on the surface of the sample obtained in this embodiment.
[0071] Example 2
[0072] Prepare an aqueous electrolyte for alkaline copper plating using a combination of chemical and electrochemical methods, containing copper chloride (Cu). 2+ The electrolyte concentration was 45 g / L. The complexing agents used were disodium ethylenediaminetetraacetate (80 g / L) and sodium citrate (60 g / L), with nickel chloride (nickel ions) added (10 g / L) and diethylenetriaminepentaacetic acid (50 g / L). The pH of the electrolyte was adjusted to between 7.5 and 13. Before copper plating, formaldehyde (50 mL / L) was added as a reducing agent. The conductive metal to be plated with copper was used as the cathode, and the titanium-coated anode as the counter electrode. During copper plating, the electrolyte temperature was controlled at 25℃, and the current density was 1000 A / m. 2 With power cut-off for 1 second every 10 minutes, the copper layer growth rate was 5 μm / min. The resulting copper layer was dense and smooth, firmly bonded to the substrate, and showed no bulging. Figure 3 This is a photograph of the copper plating layer on the surface of the sample obtained in this embodiment.
[0073] Example 3
[0074] Prepare an aqueous electrolyte for alkaline copper plating using a combination of chemical and electrochemical methods, containing copper sulfate (Cu). 2+The electrolyte concentration was 90 g / L. The complexing agents used were disodium ethylenediaminetetraacetate (20 g / L), potassium sodium tartrate (50 g / L), sodium citrate (10 g / L), urea (46 g / L), and boric acid (60 g / L). Nickel sulfate (nickel ions) (6 g / L) and diethylenetriaminepentaacetic acid (20 g / L) were added. The pH of the electrolyte was adjusted to 13. Before copper plating, formaldehyde (1 mL / L) was added as a reducing agent. A conductive carbon substrate to be plated with copper was used as the cathode, and a titanium-coated anode as the counter electrode. During copper plating, the electrolyte temperature was controlled between 25°C and 70°C, and the current density was 500 A / m³. 2 With power off for 30 seconds every 10 minutes, the copper layer growth rate was 2.7 μm / min. The resulting copper layer was dense and smooth, firmly bonded to the substrate, and showed no bulging. Figure 4 This is a photograph of the copper plating layer on the surface of the sample obtained in this embodiment.
[0075] Example 4
[0076] Prepare an aqueous electrolyte for alkaline copper plating using a combination of chemical and electrochemical methods, containing copper sulfate (Cu). 2+ The electrolyte concentration was 30 g / L. The complexing agent used was urea (30 g / L), with the addition of nickel sulfate (nickel ions) (0.1 g / L) and diethylenetriaminepentaacetic acid (5 g / L). The pH of the electrolyte was adjusted to 9. Before copper plating, sodium hypophosphite (20 g / L) was added as a reducing agent. The conductive metal substrate to be plated with copper was used as the cathode, and a lead plate as the counter electrode. During copper plating, the electrolyte temperature was controlled at 40℃, and the current density was 150 A / m. 2 With power off for 1 minute every 10 minutes, the copper layer growth rate was 0.8 μm / min. The resulting copper layer was dense and smooth, firmly bonded to the substrate, and showed no bulging. Figure 5 This is a photograph of the copper plating layer on the surface of the sample obtained in this embodiment.
[0077] Example 5
[0078] Prepare an aqueous electrolyte for alkaline copper plating using a combination of chemical and electrochemical methods, containing copper nitrate (Cu). 2+ The electrolyte concentration was 30 g / L. The complexing agents used were potassium sodium tartrate (15 g / L), sodium citrate (10 g / L), and boric acid (12 g / L). Nickel nitrate (nickel ions) (0.5 g / L) and diethylenetriaminepentaacetic acid (8 g / L) were added. The pH of the electrolyte was adjusted to 10.2. Before copper plating, sodium hypophosphite (25 g / L) was added as a reducing agent. The conductive metal substrate to be plated with copper was used as the cathode, and the titanium-coated anode as the counter electrode. During copper plating, the electrolyte temperature was controlled at 50℃, and the current density was between 200 A / m². 2With power cut-off for 20 seconds every 10 minutes, the copper layer growth rate was 1.3 μm / min. The resulting copper layer was dense and smooth, firmly bonded to the substrate, and showed no bulging. Figure 6 This is a photograph of the copper plating layer on the surface of the sample obtained in this embodiment.
[0079] Comparative Example 1
[0080] The difference between this comparative example and Example 1 is that nickel ions and diethylenetriaminepentaacetic acid were not added, while other conditions remained the same as in Example 1. In this case, copper ions could not be densely deposited, and the copper plating on the surface of the resulting sample could not adequately cover the substrate, such as... Figure 7 As shown.
[0081] Comparative Example 2
[0082] The difference between this comparative example and Example 1 is that nickel ions were added, but diethylenetriaminepentaacetic acid was not added; all other conditions were the same as in Example 1. In this case, the nickel ions were still less effective, and the copper plating layer on the surface of the resulting sample remained loose and could not completely cover the substrate. Figure 8 As shown.
[0083] Comparative Example 3
[0084] The difference between this comparative example and Example 1 is that the concentration of nickel ions is less than 0.1 g / L, while other conditions are the same as in Example 1. In this case, the effect of nickel ions is smaller, resulting in a denser copper plating layer on the sample surface, but it still cannot completely cover the substrate. Figure 9 As shown.
[0085] Comparative Example 4
[0086] The difference between this comparative example and Example 1 is that the concentration of nickel ions is greater than 10 g / L, while other conditions are the same as in Example 1. In this case, nickel ions will compete with copper ions for reduction, but nickel is more difficult to reduce than copper, leading to poisoning of active sites. The copper plating process becomes difficult, making it hard to completely cover the substrate, such as... Figure 10 As shown.
[0087] Comparative Example 5
[0088] The difference between this comparative example and Example 1 is that the concentration of diethylenetriaminepentaacetic acid is less than 5 g / L, while other conditions are the same as in Example 1. In this case, nickel ions are also less effective, and the copper plating layer cannot completely cover the substrate. Figure 11 As shown.
[0089] Comparative Example 6
[0090] The difference between this comparative example and Example 1 is that the concentration of diethylenetriaminepentaacetic acid (DTA) is greater than 50 g / L, while other conditions are the same as in Example 1. In this case, excessive DTA will coordinate with copper ions, leading to a decrease in the copper plating rate, poorer uniformity, and the inability of the copper plating layer to completely cover the substrate. Figure 12 As shown.
[0091] Comparative Example 7
[0092] The difference between this comparative example and Example 1 is that the power was not interrupted during the electroplating process, while other conditions remained the same as in Example 1. In this case, the coating adhesion is poor, resulting in some peeling on the surface, and the copper layer exhibits uneven local appearance, such as... Figure 13 As shown.
[0093] Comparative Example 8
[0094] The difference between this comparative example and Example 1 is that a power outage was performed during the electroplating process, with the power outage time being 3 minutes every 10 minutes; other conditions were the same as in Example 1. In this case, the copper layer was too thin, the surface copper layer became passivated under the excessively long power outage time, and the copper layer growth was poor. Figure 14 As shown.
[0095] In addition, the inventors of this case also conducted experiments with other raw materials, process operations, and process conditions described in this specification, referring to the aforementioned embodiments, and obtained relatively ideal results in all cases.
[0096] Obviously, the embodiments of the present invention shown above are only intended to illustrate the principles of the invention and not to limit its implementation. Those skilled in the art can make other modifications or alterations to the invention based on the above description. While it is impossible to list all embodiments exhaustively, any obviously deducible changes to the technical solutions still fall within the protection scope of the present invention.
Claims
1. A chemical-electrochemical combined alkaline copper plating method, characterized in that, include: An aqueous electrolyte is provided, the aqueous electrolyte comprising a copper salt, a first complexing agent, a nickel salt, and a second complexing agent, wherein the second complexing agent is a strong nickel ion complexing agent; Adjust the pH of the aqueous electrolyte to above 7.5 and add a reducing agent; A copper plating system is constructed by using a conductive substrate as the cathode, a counter electrode, and an aqueous electrolyte with added reducing agent. Intermittent energizing is then applied to deposit a copper layer on the surface of the conductive substrate.
2. The alkaline copper plating method according to claim 1, characterized in that: The first complexing agent includes one or more combinations of urea, sodium citrate, disodium EDTA, potassium sodium tartrate, and boric acid.
3. The alkaline copper plating method according to claim 1, characterized in that: The second complexing agent includes diethylenetriaminepentaacetic acid.
4. The alkaline copper plating method according to claim 2, characterized in that: The aqueous electrolyte contains disodium ethylenediaminetetraacetate at a concentration of 2 g / L to 80 g / L, potassium sodium tartrate at a concentration of 1 g / L to 50 g / L, sodium citrate at a concentration of 0.5 g / L to 60 g / L, urea at a concentration of 8 g / L to 46 g / L, and boric acid at a concentration of 5 g / L to 60 g / L.
5. The alkaline copper plating method according to claim 1, characterized in that: The copper salt in the aqueous electrolyte contains Cu 2+ The concentration ranges from 1 g / L to 90 g / L; And / or, the Ni salt contained in the aqueous electrolyte 2+ The concentration is 0.1 g / L to 10 g / L; And / or, the concentration of the strong nickel ion complexing agent is 5 g / L to 50 g / L.
6. The alkaline copper plating method according to claim 1, characterized in that, include: The pH value of the aqueous electrolyte is adjusted to be between 7.5 and 13.
7. The alkaline copper plating method according to claim 1, characterized in that: The reducing agent includes one or a combination of two of formaldehyde and sodium hypophosphite.
8. The alkaline copper plating method according to claim 7, characterized in that: Compared to aqueous electrolytes, the amount of formaldehyde added is 1 mL / L to 50 mL / L; and / or, the concentration of sodium hypophosphite in aqueous electrolytes with added reducing agent is 1 g / L to 60 g / L.
9. The alkaline copper plating method according to claim 1, characterized in that, The conditions for copper deposition include: electrolyte temperature of 25℃~70℃ and current density of 5 A / m. 2 ~1000 A / m 2 For every 10 minutes of power-on and 1 to 2 minutes of power-off, the copper layer growth rate is 0.1 μm / min to 5 μm / min.
10. The alkaline copper plating method according to claim 1, characterized in that: The conductive substrate includes a metal substrate or a carbon substrate; and / or, the counter electrode includes a lead plate or a titanium-coated anode. And / or, the copper layer is dense and flat, and is firmly bonded to the conductive substrate.