An electro-assisted passivation solution, its preparation method, and passivation method

Abstract

This invention discloses an electro-assisted passivation solution and its preparation and passivation methods. The raw materials of the electro-assisted passivation solution include the following components: 0.1-1 wt.% alkali-soluble mercapto compound, 0.1-1 wt.% amphoteric oxide, 1-5 wt.% inorganic alkali, 0.5-1.5 wt.% nonionic surfactant, and the balance being water. The components do not contain toxic substances. The passivation solution is suitable for electro-assisted passivation processes. The film formation process on copper parts is very fast, and the formed film layer is dense and uniform, resulting in good corrosion resistance, high protection effect, and environmental friendliness for the copper parts.

Description

Technical Field

[0001] This invention relates to the field of metal surface treatment technology, and in particular to an electro-assisted passivation liquid, its preparation method, and passivation method. Background Technology

[0002] Due to its excellent electrical and thermal conductivity and resistance to carburization, electroplated copper is widely used in industries such as electronics, communications, electrical engineering, and aerospace manufacturing. However, during production, transportation, and use, when it comes into contact with corrosive media in the environment, its surface is prone to the formation of corresponding corrosion products. This leads to discoloration and rust on the surface of the copper-plated parts, significantly damaging their original electrical properties and appearance, and affecting the use of the products. This problem is particularly serious for aerospace components with strict dimensional requirements.

[0003] The current aviation industry standards for the protection of copper and copper alloys include HB / Z 5082-78 copper and copper alloy oxidation process and HB / Z 5081-1978 copper and copper alloy chemical passivation process. Among them, HB / Z 5082-78 has a thick oxide film and large color variation, which is not suitable for the treatment of electroplated copper layers. At present, the aviation manufacturing industry generally uses the chromic anhydride and chromate passivation process in HB / Z 5081-1978. Although the copper plating layer meets the usage requirements after passivation treatment, the passivation process contains highly toxic hexavalent chromium, which seriously endangers the health of operators and causes significant environmental pollution. To replace chromium passivation, passivation processes using BTA and other corrosion inhibitors as the main components have developed rapidly. As early as 1993, Wang Chao Chromium introduced a passivation solution and process for copper and copper alloy parts (Wang Chao Chromium. BTA•H passivation of copper and copper alloy parts, Material Protection, 1993, 26(1): 40-41). Its main components are 2-4 g / L BTA, 3-4 g / L sulfosalicylic acid, and 0.3-0.5 g / L sodium dodecyl sulfate. The operating conditions are: pH 2-3, temperature 50-60℃, and time 2-4 minutes. BTA reacts with Cu on the copper surface. +The formation of a BTA-Cu(I) complex film prevents copper corrosion. While a complete complex film provides good protection, defects or damage to the film can actually accelerate copper discoloration. Thiol-containing compounds such as 2-mercaptobenzothiazole, 2-mercaptobenzoxazole, 2-mercaptobenzimidazole, 2-amino-5-mercapto-1,3,4-thiadiazole, and 1-phenyl-5-mercaptetrazolium, due to their rapid adsorption of copper, quickly establish equilibrium, resulting in a more stable film. Therefore, passivating copper with thiol-containing compounds can significantly improve protective performance. For example, Chinese patent application CN101974758A discloses a water-soluble copper protectant and its preparation and application methods. The water-soluble copper protectant is obtained by dispersing benzotriazole, 5-phenyltetrazazole, 1-phenyl-5-mercaptotetrazazole, 2-mercaptoimidazole, 2-mercaptobenzimidazole, 2-mercaptobenzothiazole, and 2-amino-5-mercapto-1,3,4-thiadiazole using an emulsifier. In application, the water-soluble copper protectant needs to be heated to 60–70°C and immersed for 5–10 minutes.

[0004] Existing research has demonstrated that electro-assisted passivation technology can also promote the rapid formation of thiol compounds on metal surfaces, shortening processing time, and has been applied to metal surfaces such as Au, Ag, Ti, Ni, and Cu. However, existing reports primarily use organic solutions of organothiols, such as dodecyl mercaptan / ethanol solutions and tetradecyl mercaptan / DMF solutions. The toxicity and harmfulness of organic solvents limit the practical industrial application of this technology. Furthermore, existing reports utilize functionally active molecules such as dodecyl mercaptan and tetradecyl mercaptan, which can only form monomolecular films, thus limiting their protective effect. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide an electro-assisted passivation liquid with good film-forming properties, non-toxicity and corrosion resistance, as well as its preparation method and passivation method.

[0006] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0007] An electro-assisted passivation solution comprises the following components by mass fraction: 0.1–1 wt.% alkali-soluble mercapto compound, 0.1–1 wt.% amphoteric oxide, 1–5 wt.% inorganic base, 0.5–1.5 wt.% nonionic surfactant, and the balance being water.

[0008] As a further improvement to the above technical solution:

[0009] The alkali-soluble thiol compound is one or more of 2-mercaptobenzothiazole, 2-mercaptobenzoxazole, and 2-mercaptobenzimidazole. The amphoteric oxide is one or two of aluminum oxide, zinc oxide, and beryllium oxide.

[0010] The inorganic base is one or more of sodium hydroxide and potassium hydroxide.

[0011] The nonionic surfactant is one or more of the following: polyoxyethylene sorbitan hexaoleate, polyoxyethylene dehydrated sorbitan oleate, fatty alcohol polyoxyethylene ether, and polyethylene glycol octylphenyl ether.

[0012] As a general inventive concept, the present invention also provides a method for preparing the aforementioned electro-assisted passivation solution, comprising the following steps:

[0013] S1. Under stirring conditions, the inorganic base and amphoteric oxide are added to water at a temperature of 40-60 °C according to their mass percentages to prepare a transparent mixed solution.

[0014] S2. Under stirring conditions, the nonionic surfactant and the alkali-soluble thiol compound are added sequentially to the transparent mixed solution to obtain the electro-assisted passivation solution.

[0015] As a general inventive concept, the present invention also provides a passivation method for an electro-assisted passivation solution, comprising the following steps: using an inert material as the anode and an electroplated copper part as the cathode, placing the anode and cathode in the electro-assisted passivation solution for electro-assisted passivation treatment.

[0016] Preferably, during the electro-assisted passivation treatment, the cathode current density is 50~300 mA / dm. 2 The thickness of the passivation film after passivation treatment at room temperature for 1-3 minutes is between tens of nanometers and hundreds of nanometers.

[0017] Compared with the prior art, the advantages of the present invention are as follows:

[0018] The electro-assisted passivation solution of this invention comprises the following components: 0.1–1 wt.% alkali-soluble thiol compound, 0.1–1 wt.% amphoteric oxide, 1–5 wt.% inorganic alkali, 0.5–1.5 wt.% nonionic surfactant, and the balance being water. The alkali-soluble thiol compound forms a passivation film on the metal surface. The amphoteric oxide and alkali-soluble thiol compound complex together to increase the thickness of the passivation film. The inorganic alkali provides an alkaline environment to dissolve the alkali-soluble thiol compound and the amphoteric oxide. The nonionic surfactant improves the stability of the solution. The passivation solution does not contain toxic substances and is suitable for electro-assisted passivation processes. The film formation process on copper parts is very rapid, resulting in a dense and uniform film layer with good corrosion resistance, high protective effect, and environmental friendliness.

[0019] This invention discloses a method for preparing an electro-assisted passivation solution, which involves first dissolving an amphoteric oxide under the action of an inorganic alkali, and then dissolving an alkali-soluble thiol compound. The preparation process is simple.

[0020] The present invention discloses a passivation method for an electrically assisted passivation solution, wherein the thickness of the film layer is controlled by current density and processing time, which solves the shortcomings of existing methods that promote passivation film growth by heating. The passivation method of the present invention can more conveniently control the film layer thickness and can effectively improve the protective effect. Detailed Implementation

[0021] The present invention will be further described in detail below. Unless otherwise specified, the instruments or materials used in the present invention are commercially available.

[0022] Example 1

[0023] The electro-assisted passivation solution for electroplated copper parts in this embodiment has the following raw material components and contents: 0.5 wt.% 2-mercaptobenzoxazole, 0.1 wt.% zinc oxide, 2 wt.% potassium hydroxide, 1.5 wt.% AEO-7 (fatty alcohol polyoxyethylene ether), and the balance is water.

[0024] The method for preparing the electro-assisted passivation solution for electroplated copper parts in this embodiment includes the following steps:

[0025] S1. Under stirring conditions, potassium hydroxide and zinc oxide are added to water at a temperature of 40-60 ℃ according to their mass percentages to obtain a transparent mixed solution; in this embodiment, the water temperature is 40 ℃.

[0026] S2. Under stirring conditions, nonionic surfactants AEO-7 and 2-mercaptobenzoxazole are added sequentially to the transparent mixed solution to obtain the electro-assisted passivation solution.

[0027] The passivation method of the electro-assisted passivation solution in this embodiment includes the following steps: using an inert material (stainless steel plate) as the anode and an electroplated copper part as the cathode, the anode and cathode are placed in the electro-assisted passivation solution of this embodiment for electro-assisted passivation, and the cathode current density is 50 mA / dm². 2 Passivation treatment at room temperature for 2 min.

[0028] Example 2

[0029] The electro-assisted passivation solution for electroplated copper parts in this embodiment has the following raw material components and contents: 1 wt.% 2-mercaptobenzimidazole, 1 wt.% beryllium oxide, 4 wt.% sodium hydroxide, 1 wt.% OP-9 (octylphenol polyoxyethylene ether), and the balance is water.

[0030] The method for preparing the electro-assisted passivation solution for electroplated copper parts in this embodiment includes the following steps:

[0031] S1. Under stirring conditions, sodium hydroxide and beryllium oxide are added to water at a temperature of 40-60°C according to their mass percentages to obtain a transparent mixed solution; in this embodiment, the water temperature is 40°C.

[0032] S2. Under stirring conditions, nonionic surfactants OP-9 and 2-mercaptobenzimidazole are added sequentially to the transparent mixed solution to obtain an electro-assisted passivation solution.

[0033] The passivation method of the electro-assisted passivation solution in this embodiment includes the following steps: using an inert material (stainless steel plate) as the anode and an electroplated copper part as the cathode, the anode and cathode are placed in the electro-assisted passivation solution of this embodiment for electro-assisted passivation, and the cathode current density is 200 mA / dm². 2 Treat at room temperature for 1 min.

[0034] Example 3

[0035] The electro-assisted passivation solution for electroplated copper parts in this embodiment has the following raw material components and contents: 0.1 wt.% 2-mercaptobenzothiazole, 0.2 wt.% alumina, 2 wt.% sodium hydroxide, 0.5 wt.% Tween 40 (polyoxyethylene sorbitan monopalmitate), and the balance being water.

[0036] The method for preparing the electro-assisted passivation solution for electroplated copper parts in this embodiment includes the following steps:

[0037] S1. Under stirring conditions, sodium hydroxide and aluminum oxide are added to water at a temperature of 40-60°C according to their mass percentages to obtain a transparent mixed solution; in this embodiment, the water temperature is 60°C.

[0038] S2. Under stirring conditions, nonionic surfactants Tween 40 and 2-mercaptobenzothiazole are added sequentially to the transparent mixed solution to obtain an electro-assisted passivation solution.

[0039] The passivation method of the electro-assisted passivation solution in this embodiment includes the following steps: using an inert material (stainless steel plate) as the anode and an electroplated copper part as the cathode, the anode and cathode are placed in the electro-assisted passivation solution of this embodiment for electro-assisted passivation, and the cathode current density is 150 mA / dm². 2 Treat at room temperature for 1 min.

[0040] Example 4

[0041] The electro-assisted passivation solution for electroplated copper parts in this embodiment has the following raw material components and contents: 1 wt.% 2-mercaptobenzoxazole, 1 wt.% beryllium oxide, 4 wt.% sodium hydroxide, 1 wt.% Tween 40, and the balance is water.

[0042] The method for preparing the electro-assisted passivation solution for electroplated copper parts in this embodiment includes the following steps:

[0043] S1. Under stirring conditions, sodium hydroxide and beryllium oxide are added to water at a temperature of 40-60°C according to their mass percentages to obtain a transparent mixed solution; in this embodiment, the water temperature is 60°C.

[0044] S2. Under stirring conditions, nonionic surfactants Tween 40 and 2-mercaptobenzoxazole are added sequentially to the transparent mixed solution to obtain an electro-assisted passivation solution.

[0045] The passivation method of the electro-assisted passivation solution in this embodiment includes the following steps: using an inert material (stainless steel plate) as the anode and an electroplated copper part as the cathode, the anode and cathode are placed in the electro-assisted passivation solution of this embodiment for electro-assisted passivation, and the cathode current density is 100 mA / dm². 2 Treat at room temperature for 3 min.

[0046] Example 5

[0047] The electro-assisted passivation solution for electroplated copper parts in this embodiment has the following raw material components and contents: 0.1 wt.% 2-mercaptobenzoxazole, 0.2 wt.% aluminum oxide, 3 wt.% potassium hydroxide, 0.5 wt.% OP-9, and the balance is water.

[0048] The method for preparing the electro-assisted passivation solution for electroplated copper parts in this embodiment includes the following steps:

[0049] S1. Under stirring conditions, potassium hydroxide and aluminum oxide are added to water at a temperature of 40-60°C according to their mass percentages to obtain a transparent mixed solution; in this embodiment, the water temperature is 60°C.

[0050] S2. Under stirring conditions, nonionic surfactants OP-9 and 2-mercaptobenzoxazole are added sequentially to the transparent mixed solution to obtain an electro-assisted passivation solution.

[0051] The passivation method of the electro-assisted passivation solution in this embodiment includes the following steps: using an inert material (stainless steel plate) as the anode and an electroplated copper part as the cathode, the anode and cathode are placed in the electro-assisted passivation solution of this embodiment for electro-assisted passivation, and the cathode current density is 150 mA / dm². 2 Treat at room temperature for 2 min.

[0052] Comparative Example 1

[0053] A commercially available copper self-assembly protective solution has the following formulation in 1L of solution: 0.5g 2-mercaptobenzothiazole, 300ml glacial acetic acid, 0.1g citric acid, and the remainder is water.

[0054] The preparation method of the copper self-assembly protective solution in this comparative example includes the following steps: 0.5g of 2-mercaptobenzothiazole is added to 300ml of glacial acetic acid, then 0.1g of citric acid is added, stirred until dissolved, and then diluted with sufficient water to 1L to obtain the copper self-assembly protective solution.

[0055] The processing conditions are as follows: Clean the electroplated copper parts and immerse them in the copper self-assembly protective solution in this comparative example for 15 minutes at room temperature.

[0056] Comparative Example 2

[0057] A commercially available copper surface treatment solution has the following raw material formula by mass percentage: 12.5% ​​concentrated sulfuric acid, 15% benzotriazole, 0.4% p-hydroxybenzenesulfonic acid, 0.1% polyethylene glycol, and the balance being water.

[0058] The processing conditions are as follows: Clean the electroplated copper parts and immerse them in the copper surface treatment solution of this comparative example at 50°C for 10 minutes.

[0059] Comparative Example 3

[0060] A commercially available water-soluble copper protectant has the following raw material formulation: 0.24 wt.% 5-phenyltetrazazole, 0.16 wt.% 2-mercaptoimidazole, 0.4 wt.% 2-amino-5-mercapto-1,3,4-thiadiazole, 16 wt.% n-propanol, 3.6 wt.% sodium dodecylbenzenesulfonate, with the balance being water.

[0061] The processing conditions are as follows: First, heat the water-soluble copper protectant to 60°C, then immerse the clean and dry electroplated copper parts in the solution and soak them at 60°C for 10 minutes.

[0062] Comparative Example 4

[0063] The electro-assisted passivation solution of this comparative example has the following raw material components and contents: 0.5 wt.% 2-mercaptobenzoxazole, 2 wt.% potassium hydroxide, and the balance being water.

[0064] The preparation method of the electro-assisted passivation solution in this comparative example includes the following steps:

[0065] S1. Under stirring conditions, potassium hydroxide was added to water at a temperature of 40-60 ℃ according to the mass percentage to obtain a transparent mixed solution; in this comparative example, the water temperature was 40 ℃.

[0066] S2. Under stirring conditions, 2-mercaptobenzoxazole is added to the transparent mixed solution to obtain the electro-assisted passivation solution.

[0067] The passivation method of the electro-assisted passivation solution in this comparative embodiment is the same as that in Example 1.

[0068] Comparative Example 5

[0069] The electro-assisted passivation solution for electroplated copper parts in this comparative example has the following raw material components and contents: 0.5 wt.% 2-mercaptobenzoxazole, 2 wt.% potassium hydroxide, 1.5 wt.% AEO-7 (fatty alcohol polyoxyethylene ether), and the balance is water.

[0070] The preparation method of the electro-assisted passivation solution in this embodiment includes the following steps:

[0071] S1. Under stirring conditions, potassium hydroxide was added to water at a temperature of 40-60 ℃ according to the mass percentage to obtain a transparent mixed solution; in this comparative example, the water temperature was 40 ℃.

[0072] S2. Under stirring conditions, nonionic surfactants AEO-7 and 2-mercaptobenzoxazole are added sequentially to the transparent mixed solution to obtain an electro-assisted passivation solution.

[0073] The passivation method of the electro-assisted passivation solution in this comparative example is the same as that in Example 1.

[0074] Neutral salt spray test: The test was conducted according to QB / T 3826-1999, "Test Method for Corrosion Resistance of Metal Coatings for Light Industrial Products". The coated parts prepared in the five examples and five comparative examples were placed in a neutral salt spray test chamber, and the time it took for their surfaces to begin discoloration was observed and recorded. The results are shown in Table 1. The table shows that the shortest discoloration time for comparative examples 1, 2, 3, 4, and 5 was 8 hours, and the longest was 16 hours. However, no discoloration occurred in any of the embodiments of the present invention within this timeframe, indicating that the corrosion resistance of the present invention is superior to that of comparative examples 1, 2, 3, 4, and 5, and the film layer is thicker and more uniform.

[0075] Table 1. Corrosion resistance test results of each embodiment and comparative example.

[0076]

[0077] Note: In Table 1, √ indicates no color change and × indicates color change.

[0078] While the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the invention. Any person skilled in the art can make many possible variations and modifications to the technical solutions of the present invention, or modify them into equivalent embodiments, without departing from the scope of the present invention. Therefore, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention, without departing from the scope of the present invention, should fall within the protection scope of the present invention.

Claims

1. A passivation method using an electro-assisted passivation solution, characterized in that, Includes the following steps: Using an inert material as the anode and an electroplated copper part as the cathode, the anode and cathode are placed in an electro-assisted passivation solution for electro-assisted passivation treatment; the raw material of the electro-assisted passivation solution includes the following components by mass fraction: 0.1–1 wt.% alkali-soluble mercapto compound, 0.1–1 wt.% amphoteric oxide, 1–5 wt.% inorganic base, 0.5–1.5 wt.% nonionic surfactant, balance water; The alkali-soluble thiol compound is one or more of 2-mercaptobenzothiazole, 2-mercaptobenzoxazole, and 2-mercaptobenzimidazole; The amphoteric oxide is one or more of aluminum oxide and zinc oxide; The cathode current density is 50-300 mA / dm 2 at room temperature for 1-3 min.

2. The passivation method according to claim 1, characterized in that, The inorganic base is one or both of sodium hydroxide and potassium hydroxide.

3. The passivation method according to claim 1, characterized in that, The nonionic surfactant is one or more of the following: polyoxyethylene sorbitan hexaoleate, polyoxyethylene dehydrated sorbitan oleate, fatty alcohol polyoxyethylene ether, and polyethylene glycol octylphenyl ether.

4. The passivation method according to any one of claims 1 to 3, characterized in that, The preparation of the electro-assisted passivation solution includes the following steps: S1. Under stirring conditions, the inorganic base and amphoteric oxide are added to water at a temperature of 40-60℃ according to their mass fractions to obtain a transparent mixed solution. S2. Under stirring conditions, the nonionic surfactant and the alkali-soluble thiol compound are added sequentially to the transparent mixed solution to obtain the electro-assisted passivation solution.

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