Electroplating solution and preparation method thereof

Abstract

An electroplating solution suitable for electroplating processes, comprising: sodium citrate, tantalum tetrachloride, an inorganic acid, potassium chloride, and ammonium fluoride, wherein the molar concentration of sodium citrate is 0.025M, the molar concentration of tantalum tetrachloride is 0.15M, the molar concentration of the inorganic acid is 0.01M, the molar concentration of potassium chloride is 0.05M, and the molar concentration of ammonium fluoride is 0.02M. An electroplating solution is applied for an electroplating process. of the potassium chloride is 0.05M, and the molar concentration of ammonium fluoride is 0.02M.

Description

Technical Field

[0001] This invention relates to the technical field of electroplating solutions, and more particularly to a pollution-free electroplating solution and its preparation method. Prior Technology

[0002] As consumer electronics have evolved, consumers now consider aesthetics as well as functionality when making purchasing decisions. Most consumer electronics on the market today have casings made of metals such as aluminum alloy or aluminum-magnesium alloy. To achieve a decorative effect, the casings of electronic products such as mobile phones, computers, and digital cameras often undergo surface treatment. Among these, products treated with electroplating have a superior metallic texture and better wear resistance.

[0003] Electroplating is a common surface treatment method. The product to be electroplated is placed in an electroplating tank containing a chemical electroplating solution, and an electroplating layer is formed on the surface of the product using the principle of electrolysis. This prevents metal oxidation (such as rust) and creates a visually appealing effect on the metal product. However, pollutants generated during the electroplating process, such as ineffective (active) electroplating solutions, surface impurities, and metal deposits, can become a significant source of water pollution and severely harm the surrounding environment if not properly recycled and treated. Therefore, electroplating plants must first chemically neutralize the wastewater generated after electroplating before discharging it into a sludge tank for sedimentation and then undergo environmentally friendly recycling treatment.

[0004] Specifically, electroplating solutions can be broadly classified into two types: cyanide-based and non-cyanide-based. Due to their superior stability, cyanide-based electroplating solutions are the mainstream technology used in traditional industries. However, this method has a major drawback: cyanide-containing electroplating solutions are highly toxic. Therefore, electroplating workplaces must meet safety standards and have comprehensive wastewater treatment procedures to ensure the health of workers and prevent pollution of the working and ecological environments. The environmental hazards caused by electroplating are primarily due to the electroplating solutions themselves. These solutions contain heavy metals such as nickel, copper, and chromium, while the pre-plating processes involve strong acids and corrosive solutions like sulfuric acid and hydrochloric acid, all of which contribute to water and soil pollution. With increasing environmental awareness, the treatment of electroplating wastewater has become an urgent problem to solve. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the main purpose of this invention is to provide an environmentally friendly and pollution-free electroplating solution. The composition of the electroplating solution is non-toxic and the inorganic acid used is weakly acidic, which is relatively friendly to the working environment and ecological environment and will not cause pollution.

[0006] Another objective of this invention is that the metal coating formed by the pollution-free electroplating solution of this invention can prevent the surface of the workpiece from rusting, while retaining the metallic texture and luster. The composition of the electroplating solution is environmentally friendly and non-toxic, and will not cause toxic pollution to the environment.

[0007] Another objective of this invention is that it utilizes the adjustment of sodium citrate concentration in the electroplating solution to reset the electrical properties of the ineffective electroplating solution, allowing the reset electroplating solution to be reused. Accordingly, electroplating operators do not need to replace the ineffective (active) electroplating solution; they can simply increase the concentration of sodium citrate in the electroplating solution to restore it to an effective (active) electroplating solution, enabling reuse. At the same time, electroplating operators do not need to incur wastewater treatment costs for the wastewater generated after electroplating, thereby reducing their manufacturing costs.

[0008] To achieve the above objectives, this invention discloses an electroplating solution suitable for electroplating processes. The electroplating solution comprises: sodium citrate, tantalum tetrachloride, potassium chloride, an inorganic acid agent, and ammonium fluoride, wherein the molar concentration of sodium citrate is 0.097M, the molar concentration of tantalum tetrachloride is 0.15M, the molar concentration of the inorganic acid agent is 0.01M, the molar concentration of potassium chloride is 0.67M, and the molar concentration of ammonium fluoride is 0.54M.

[0009] In a preferred embodiment of the present invention, the inorganic acid is nitric acid (HNO3), boric acid (H3BO3), hydrobromic acid (HBr), or perchloric acid (HClO4).

[0010] The present invention also provides a metal coating formed using an electroplating solution, wherein the metal coating is deposited on the surface of the workpiece to be electroplated, and the metal coating is a potassium metal film.

[0011] The present invention also provides a method for preparing an electroplating solution, the method comprising: mixing sodium citrate and tantalum tetrachloride to form a first mixed solution, wherein the molar concentration of sodium citrate is 0.097M and the molar concentration of tantalum tetrachloride is 0.15M; adding an inorganic acid to the first mixed solution to form a second mixed solution, wherein the molar concentration of the inorganic acid is 0.01M; adding potassium chloride to the second mixed solution to form a third mixed solution, wherein the molar concentration of potassium chloride is 0.67M; and adding ammonium fluoride to the third mixed solution to form an electroplating solution, wherein the molar concentration of ammonium fluoride is 0.54M.

[0012] In a preferred embodiment of the present invention, the inorganic acid is nitric acid (HNO3), boric acid (H3BO3), hydrobromic acid (HBr), or perchloric acid (HClO4). Simple Explanation of the Diagram

[0013] Figure 1 is a flowchart illustrating an embodiment of the method for preparing the electroplating solution of the present invention, based on the technology disclosed herein. Figure 2 is a schematic diagram of the electroplating equipment used in the pollution-free electroplating solution of the present invention, according to the technology disclosed in the present invention. Figure 3 is a SEM image of a workpiece to be electroplated with a metal coating deposited according to the technology disclosed in this invention, obtained under a vacuum environment of 400°C with nitrogen gas and 5% hydrogen gas added. Figure 4 is a SEM image of a workpiece to be electroplated with a metal coating deposited according to the technology disclosed in this invention, obtained in a vacuum environment with oxygen supply and a temperature of 300°C. Implementation

[0014] To fully understand the purpose, features and effects of the present invention, the present invention will be described in detail below with reference to the following specific embodiments and accompanying drawings.

[0015] The electroplating solution disclosed in this invention is suitable for electroplating processes. The electroplating solution comprises: sodium citrate, tantalum tetrachloride, an inorganic acid agent, potassium chloride, and ammonium fluoride. The sodium citrate concentration is 5 g / 200 ml, which is equivalent to a molar concentration of 0.097 M; the tantalum tetrachloride concentration is 0.15 M; the inorganic acid agent concentration is 2 g / 200 ml, which is equivalent to a molar concentration of 0.01 M; the potassium chloride concentration is 10 g / 200 ml, which is equivalent to a molar concentration of 0.67 M; and the ammonium fluoride concentration is 4 g / 200 ml, which is equivalent to a molar concentration of 0.54 M.

[0016] Electroplating operators can achieve different surface treatment results on the workpiece 14 (as shown in Figure 2) by adjusting operating parameters such as the concentration of sodium citrate, the electroplating time, and the electroplating current. The inorganic acid is nitric acid (HNO3), boric acid (H3BO3), hydrobromic acid (HBr), or perchloric acid (HClO4). In this invention, the inorganic acid is weakly acidic. Compared to existing technologies using strong acid solutions such as sulfuric acid and / or hydrochloric acid, the electroplating solution of this invention has relatively lower environmental toxicity and will not cause environmental pollution.

[0017] Next, please refer to Figure 1. Figure 1 is a flowchart illustrating an embodiment of the method for preparing the electroplating solution according to the technology disclosed in this invention. Step S11: Sodium citrate and tantalum tetrachloride are mixed to form a first mixed solution, wherein the proportion of sodium citrate is 5 g / 200 ml, which is equivalent to a molar concentration of 0.097 M and the molar concentration of tantalum tetrachloride is 0.15 M. Step S12: An inorganic acid is added to the first mixed solution to form a second mixed solution, wherein the proportion of the inorganic acid is 2 g / 200 ml, which is equivalent to a molar concentration of 0.01 M. The inorganic acid can be nitric acid (HNO3), boric acid (H3BO3), hydrobromic acid (HBr), or perchloric acid (HClO4). In a preferred embodiment of this invention, boric acid is used as the inorganic acid. Step S13: Add potassium chloride to the second mixed solution to form a third mixed solution, wherein the proportion of potassium chloride is 10g / 200ml, which is equivalent to a molar concentration of 0.67M; Step S14: Add ammonium fluoride to the third mixed solution to form an electroplating solution, wherein the proportion of ammonium fluoride is 4g / 200ml, which is equivalent to a molar concentration of 0.54M.

[0018] Next, please refer to Figure 2. Figure 2 is a schematic diagram of the electroplating equipment used in the pollution-free electroplating solution disclosed in this invention. In Figure 3, the electroplating equipment 10 includes an electroplating tank 11, a pollution-free electroplating solution 12 contained in the electroplating tank 11, a target material 13 and a workpiece 14 to be electroplated placed in the electroplating tank 11, and a portion of the target material 13 and the workpiece 14 to be electroplated are immersed in the pollution-free electroplating solution 12. It should be noted that the pollution-free electroplating solution 12 in Figure 1 includes sodium citrate, tantalum tetrachloride, inorganic acid, potassium chloride, and ammonium fluoride, the concentrations or proportions of which are the same as described above and will not be repeated here.

[0019] The target material 13 and the workpiece 14 to be electroplated are electrically connected to the positive and negative terminals of the power supply 15, respectively. The target material 13 must be a conductive material; in this embodiment, the target material 13 is tantalum. When the power supply 15 is started, it provides DC power to the tantalum target material 13 and the workpiece 14 to be electroplated for the electroplating process. In the electroplating process, the half-reaction of the positive electrode is... The half-reaction at the negative electrode is: Specifically, the tantalum target 13 releases electrons. And become metal ions Dissolved in electroplating solution 12, while the metal ions to be plated in electroplating solution 12 Accepted electronic , reduction to form metal atoms And deposited on the surface of the workpiece 14 to be electroplated.

[0020] It should be noted that a pretreatment step is performed on the workpiece 14 to be electroplated before the electroplating process. The pretreatment step includes: first, polishing the surface of the workpiece 14 with sandpaper, or rinsing with diluted hydrochloric acid to remove rust spots. Next, the workpiece 14 with the rust removed is cleaned with sodium hydroxide to remove surface oil. Finally, the workpiece 14 is rinsed with distilled water to complete the pretreatment step. After the electroplating process is completed, the workpiece 14 is removed from the electroplating tank 11 and rinsed with distilled water to remove any residual electroplating solution 12. Further, the distilled water is removed with acetone, resulting in an electroplated workpiece with a deposited coating. It should be noted that the electroplating process of this invention can be performed at room temperature and does not require heating of the electroplating solution 12. In actual operation, a magnet can be placed in the electroplating solution and continuously rotated to uniformly stir the electroplating solution 12. In this operation, the rotational speed of the magnet is related to the internal stress of the electroplating film layer deposited on the surface of the workpiece 14 to be electroplated. Therefore, the faster the magnet rotates, the brighter the electroplating film layer formed on the surface of the workpiece 14 to be electroplated. In this embodiment, the rotational speed of the magnet is preferably between 300 rpm and 1,000 rpm.

[0021] In one embodiment, the operating temperature of the electroplating solution 12 is 70°C, the electroplating time is 2-3 hours, the current of the power supply 15 is controlled between 0.01A (Amperes) and 0.05A, and the voltage is controlled below 20V (Volts). After the electroplating operation is completed, the electroplated workpiece 14 with the deposited potassium metal coating is removed from the electroplating solution 12, and then subjected to a heat treatment step. In this invention, the heat treatment step involves placing the electroplated workpiece 14 with the deposited potassium metal coating in a vacuum environment with nitrogen and 5% hydrogen introduced, at a heat treatment temperature of 400°C, for a first heat treatment of 1 hour. Then, a second heat treatment is performed in a vacuum environment with pure oxygen introduced and a temperature of 300°C, for a heat treatment time of 1 hour. After the second heat treatment is completed and the temperature drops to room temperature, a metal film, a potassium metal film, formed by the electroplating solution disclosed in this invention can be obtained. This potassium metal film is deposited on the surface of the workpiece 14 to be electroplated. After the above heat treatment, a potassium tantalum nitride metal film is formed on the surface of the workpiece. The smoothness and smaller grain size of the electroplated layer, as well as the hardness, wear resistance, and corrosion resistance, all tend to be improved, thus improving the adhesion of the coating. Furthermore, the tantalum (Ta) metal coating with a larger atomic number is also beneficial for radiation protection (such as lead plate isolation in X-ray rooms). Moreover, tantalum is non-toxic and is itself an anti-wear material. A composite electroplating effect can be achieved using a single anode, for example, by using an electric field to allow metal ions in the plating solution to be adsorbed and deposited at the cathode under the action of the electric field.

[0022] Next, please refer to Figures 3 and 4. Figure 3 is a SEM image of a workpiece with a deposited metal coating, obtained according to the technology disclosed in this invention, under a vacuum environment at 400°C with nitrogen and 5% hydrogen added. Figure 4 is a SEM image of a workpiece with a deposited metal coating, obtained according to the technology disclosed in this invention, under a vacuum environment with oxygen and 300°C. From Figures 3 and 4, it can be seen that the metal coating on the electroplated workpiece has a nano-level crystalline ordered arrangement, and the surface mechanical and physical properties of the material will be affected differently by the presence of oxygen or nitrogen, resulting in varying hardness.

[0023] In summary, the pollution-free electroplating solution obtained by the preparation method of the present invention consists of non-toxic and environmentally friendly components. Furthermore, the inorganic acid used is weakly acidic, and its application in actual mass-production electroplating will not cause serious pollution to the working environment or the ecological environment. In addition, the electroplating solution of the present invention can have its electrical properties reset by adjusting the concentration of sodium citrate, allowing the solution to be recycled and reused. This reduces environmental pollution and saves electroplating companies on the cost of recycling and processing electroplating solutions.

[0024] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the invention. Anyone skilled in the art can make some modifications and refinements without departing from the spirit and scope of the invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

[0025] 10: Electroplating equipment 11: Electroplating bath 12: Electroplating solution 13: Target Material 14: Workpiece to be electroplated 15: Power Supply S11-S15: Preparation steps of electroplating solution

Claims

1. An electroplating solution suitable for an electroplating process, the electroplating solution comprising: Sodium citrate, with a molar concentration of 0.097 M; The following are components: tantalum tetrachloride with a molar concentration of 0.15 M; an inorganic acid with a molar concentration of 0.01 M; potassium chloride with a molar concentration of 0.67 M; and ammonium fluoride with a molar concentration of 0.54 M.

2. The electroplating solution as claimed in claim 1, wherein the inorganic acid is nitric acid (HNO3), boric acid (H3BO3), hydrobromic acid (HBr), or perchloric acid (HClO4).

3. A metal coating formed using the electroplating solution described in claim 1, the metal coating being deposited on a surface of a workpiece to be electroplated, and the metal coating being a potassium tantalum (KTa) coating.

4. A method for preparing an electroplating solution, the method comprising the following steps: mixing sodium citrate and tantalum tetrachloride to form a first mixed solution, wherein the molar concentration of sodium citrate is 0.097 M and the molar concentration of tantalum tetrachloride is 0.15 M; adding an inorganic acid to the first mixed solution to form a second mixed solution, wherein the molar concentration of the inorganic acid is 0.01 M; adding potassium chloride to the second mixed solution to form a third mixed solution, wherein the molar concentration of potassium chloride is 0.67 M; and adding ammonium fluoride to the third mixed solution to form the electroplating solution, wherein the molar concentration of ammonium fluoride is 0.54 M.

5. The method for preparing the electroplating solution as described in claim 4, wherein the inorganic acid is nitric acid (HNO3), boric acid (H3BO3), hydrobromic acid (HBr), or perchloric acid (HClO4).

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