Electrically-assisted passivation solution as well as preparation method and passivation method thereof

Abstract

The invention discloses an electrically-assisted passivation solution and a preparation method and a passivation method thereof.The electrically-assisted passivation solution is prepared from 0.1 wt%-1 wt% of an alkali-soluble sulfhydryl compound, 0.1 wt%-1 wt% of amphoteric oxide, 1 wt%-5 wt% of inorganic alkali, 0.5 wt%-1.5 wt% of a nonionic surfactant and the balance water, the components do not contain toxic substances, and the passivation solution is suitable for an electrically-assisted passivation technology. And the film forming process on the copper piece is very fast, the formed film layer is compact and uniform, and the copper piece is good in corrosion resistance effect, high in protection effect and environmentally friendly.

Description

Technical Field

[0001] The invention relates to the technical field of metal surface treatment, and in particular to an electric-assisted passivation solution and a preparation method and a passivation method thereof. Background Art

[0002] Due to its good electrical conductivity, thermal conductivity, and anti-carburization properties, electroplated copper is widely used in the electronics, communications, electrical engineering, and aviation manufacturing industries. However, when it comes into contact with corrosive media in the environment during production, transportation, and use, its surface is very likely to generate corresponding corrosion products, causing the surface of the copper-plated parts to change color and rust, greatly damaging its original electrical properties and appearance, and affecting the use of the products. This problem is particularly serious for aviation parts 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 is not suitable for the treatment of electroplated copper layers due to its thick oxide film and large color changes. Currently, the aviation manufacturing industry generally adopts the passivation process of chromic anhydride and chromate in HB / Z 5081-1978. Although the copper plating layer meets the use requirements after passivation treatment, the passivation process contains highly toxic hexavalent chromium, which seriously endangers the health of operators and causes great environmental pollution. In order to replace the chromium passivation process, the passivation process with BTA and other corrosion inhibitors as the main components has been rapidly developed. As early as 1993, Dynasty Chromium introduced a passivation solution and process for copper and copper alloy parts (Dynasty 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, 0.3-0.5 g / L sodium dodecyl sulfonate, and the operating process is pH 2-3, temperature 50-60℃, and time 2-4 minutes. BTA is a kind of passivation solution that reacts with the copper surface Cu +The BTA-Cu(I) complex film is formed to prevent copper corrosion. Although the complete complex film has good protective performance, once the complex film is defective or damaged, it will accelerate the discoloration of copper. Compounds containing thiol groups such as 2-mercaptobenzothiazole, 2-mercaptobenzoxazole, 2-mercaptobenzimidazole, 2-amino-5-mercapto-1,3,4-thiadiazole, and 1-phenyl-5-mercaptotetrazole can quickly establish a balance due to the fast adsorption of thiol and copper, and the formed film layer is more stable. Therefore, passivating copper with thiol-containing compounds can significantly improve the protective performance. For example, the patent application of Chinese patent publication number CN101974758A discloses a water-soluble copper protective agent and its preparation method and use method, which uses an emulsifier to disperse benzotriazole, 5-phenyltetrazolyl, 1-phenyl-5-mercaptotetrazolyl, 2-mercaptoimidazole, 2-mercaptobenzimidazole, 2-mercaptobenzothiazole, 2-amino-5-mercapto-1,3,4-thiadiazole, etc. to obtain a water-soluble copper protective agent. When using, the water-soluble copper protective agent needs to be heated to 60-70°C and immersed for 5-10 minutes.

[0004] Existing research proves that the electric assisted passivation technology can also promote the rapid formation of film layers of mercapto compounds on metal surfaces, shorten the processing time, and is applied on metal surfaces such as Au, Ag, Ti, Ni, Cu, etc. However, the existing reports that the treatment solution is mostly an organic solution of organic mercaptan, such as dodecanethiol / ethanol solution, tetradecanethiol / DMF solution, etc. Due to the toxicity and harmfulness of organic solvents, the application of this technology in actual industry is limited. In addition, the functional active molecules such as dodecanethiol and tetradecanethiol used in the existing reports can only form a monomolecular film layer, and its protective effect is equally limited. Summary of the invention

[0005] The technical problem to be solved by the present invention is to overcome the deficiencies of the prior art and provide an electrically assisted passivation solution with good film-forming property, non-toxicity and corrosion resistance, and a preparation method and a passivation method thereof.

[0006] In order to solve the above technical problems, the present invention adopts the following technical solutions: The invention discloses an electric-assisted passivation solution, wherein the raw materials include the following components by mass fraction: 0.1-1 wt.% of an alkali-soluble mercapto compound, 0.1-1 wt.% of an amphoteric oxide, 1-5 wt.% of an inorganic base, 0.5-1.5 wt.% of a nonionic surfactant, and the balance is water.

[0007] As a further improvement to the above technical solution: The alkali-soluble mercapto 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.

[0008] The inorganic base is one or more of sodium hydroxide and potassium hydroxide.

[0009] The nonionic surfactant is one or more of polyoxyethylene sorbitan hexaoleate, polyoxyethylene sorbitan oleate, fatty alcohol polyoxyethylene ether, and polyethylene glycol octylphenyl ether.

[0010] As a general inventive concept, the present invention also provides a method for preparing the electrically assisted passivation solution, comprising the following steps: S1. Under stirring, the inorganic base and the amphoteric oxide are added to water at a temperature of 40-60° C. according to mass percentage to prepare a transparent mixed solution; S2. Under stirring, the nonionic surfactant and the alkali-soluble mercapto compound are added to the transparent mixed solution in sequence to obtain the electrically assisted passivation solution.

[0011] As a general inventive concept, the present invention also provides a passivation method of an electrically assisted passivation solution, comprising the following steps: using an inert material as an anode and an electroplated copper part as a cathode, placing the anode and the cathode in the electrically assisted passivation solution for electrically assisted passivation treatment.

[0012] Preferably, during the electrically assisted passivation treatment, the cathode current density is 50-300 mA / dm 2 The thickness of the passivation film after passivation treatment for 1 to 3 minutes at room temperature is between tens of nanometers and hundreds of nanometers.

[0013] Compared with the prior art, the advantages of the present invention are: The raw materials of the electric-assisted passivation solution of the present invention include the following components: 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 is water, wherein the alkali-soluble mercapto compound is used to form a passivation film on the metal surface, the amphoteric oxide and the alkali-soluble mercapto compound are complexed to increase the thickness of the passivation film, the inorganic base provides an alkaline environment to dissolve the alkali-soluble mercapto compound and the amphoteric oxide, and the nonionic surfactant can improve the stability of the solution. The passivation solution does not contain toxic substances, the passivation solution is suitable for the electric-assisted passivation process, the film forming process on the copper parts is very fast, the formed film layer is dense and uniform, the copper parts have good corrosion resistance, high protection effect, and are environmentally friendly.

[0014] The invention discloses a method for preparing an electrically assisted passivation solution. The method comprises the following steps: firstly dissolving an amphoteric oxide under the action of an inorganic base, and then dissolving an alkali-soluble mercapto compound. The preparation process is simple.

[0015] The invention discloses a passivation method for an electrically assisted passivation liquid, in which the thickness of the film layer is controlled by current density and processing time, thereby solving the shortcomings of the existing method of promoting the growth of the passivation film by heating. The passivation method of the invention can more conveniently control the thickness of the film layer and can effectively improve the protective effect. DETAILED DESCRIPTION

[0016] The present invention will be described in further detail below. Unless otherwise specified, the instruments or materials used in the present invention are commercially available.

[0017] Example 1 The raw material components and contents of the electrically assisted passivation solution for electroplating copper parts in this embodiment are: 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.

[0018] The method for preparing the electric-assisted passivation solution for electroplating copper parts of this embodiment comprises the following steps: S1. Under stirring, potassium hydroxide and zinc oxide are added to water at a temperature of 40-60° C. according to mass percentage to prepare a transparent mixed solution; in this embodiment, the water temperature is 40° C.

[0019] S2. Add nonionic surfactant AEO-7 and 2-mercaptobenzoxazole to the transparent mixed solution in sequence under stirring to obtain the electrically assisted passivation solution.

[0020] The passivation method of the electric-assisted passivation solution of this embodiment comprises the following steps: using an inert material (stainless steel plate) as an anode and an electroplated copper piece as a cathode, placing the anode and the cathode in the electric-assisted passivation solution of this embodiment for electric-assisted passivation, and the cathode current density is 50 mA / dm 2 , passivation treatment was performed at room temperature for 2 min.

[0021] Example 2 The raw material components and contents of the electrically assisted passivation solution for electroplating copper parts in this embodiment are: 1 wt.% 2-mercaptobenzimidazole, 1 wt.% beryllium oxide, 4 wt.% sodium hydroxide, 1 wt.% OP-9 (octylphenol polyoxyethylene ether), and the balance is water.

[0022] The method for preparing the electric-assisted passivation solution for electroplating copper parts of this embodiment comprises the following steps: S1. Under stirring conditions, sodium hydroxide and beryllium oxide are added to water at a temperature of 40-60° C. according to mass percentage to prepare a transparent mixed solution; in this embodiment, the water temperature is 40° C.

[0023] S2. Add nonionic surfactant OP-9 and 2-mercaptobenzimidazole to the transparent mixed solution in sequence under stirring to prepare an electrically assisted passivation solution.

[0024] The passivation method of the electric-assisted passivation solution of this embodiment comprises the following steps: using an inert material (stainless steel plate) as an anode and an electroplated copper piece as a cathode, placing the anode and the cathode in the electric-assisted passivation solution of this embodiment for electric-assisted passivation, and the cathode current density is 200 mA / dm 2 , at room temperature for 1 min.

[0025] Example 3 The raw material components and contents of the electrically assisted passivation solution for electroplating copper parts in this embodiment are: 0.1 wt.% 2-mercaptobenzothiazole, 0.2 wt.% aluminum oxide, 2 wt.% sodium hydroxide, 0.5 wt.% Tween 40 (polyoxyethylene sorbitan monopalmitate), and the balance is water.

[0026] The method for preparing the electric-assisted passivation solution for electroplating copper parts of this embodiment comprises the following steps: S1. Under stirring conditions, sodium hydroxide and aluminum oxide are added to water at a temperature of 40-60° C. according to mass percentage to prepare a transparent mixed solution; in this embodiment, the water temperature is 60° C.

[0027] S2. Add nonionic surfactant Tween 40 and 2-mercaptobenzothiazole to the transparent mixed solution in sequence under stirring to prepare an electrically assisted passivation solution.

[0028] The passivation method of the electric-assisted passivation solution of this embodiment comprises the following steps: using an inert material (stainless steel plate) as an anode and an electroplated copper piece as a cathode, placing the anode and the cathode in the electric-assisted passivation solution of this embodiment for electric-assisted passivation, and the cathode current density is 150 mA / dm 2 , at room temperature for 1 min.

[0029] Example 4 The raw material components and contents of the electrically assisted passivation solution for electroplating copper parts of this embodiment are: 1 wt.% 2-mercaptobenzoxazole, 1 wt.% beryllium oxide, 4 wt.% sodium hydroxide, 1 wt.% Tween 40, and the balance is water.

[0030] The method for preparing the electric-assisted passivation solution for electroplating copper parts of this embodiment comprises the following steps: S1. Under stirring conditions, sodium hydroxide and beryllium oxide are added to water at a temperature of 40-60° C. according to mass percentage to prepare a transparent mixed solution; in this embodiment, the water temperature is 60° C.

[0031] S2. Add nonionic surfactant Tween 40 and 2-mercaptobenzoxazole to the transparent mixed solution in sequence under stirring to prepare an electrically assisted passivation solution.

[0032] The passivation method of the electric-assisted passivation solution of this embodiment comprises the following steps: using an inert material (stainless steel plate) as an anode and an electroplated copper piece as a cathode, placing the anode and the cathode in the electric-assisted passivation solution of this embodiment for electric-assisted passivation, and the cathode current density is 100 mA / dm 2 , at room temperature for 3 min.

[0033] Example 5 The raw material components and contents of the electrically assisted passivation solution for electroplating copper parts in this embodiment are: 0.1 wt.% 2-mercaptobenzoxazole, 0.2 wt.% aluminum oxide, 3 wt.% potassium hydroxide, 0.5 wt.% OP-9, and the balance is water.

[0034] The method for preparing the electric-assisted passivation solution for electroplating copper parts of this embodiment comprises the following steps: S1. Under stirring conditions, potassium hydroxide and aluminum oxide are added to water at a temperature of 40-60° C. according to mass percentage to prepare a transparent mixed solution; in this embodiment, the water temperature is 60° C.

[0035] S2. Add nonionic surfactant OP-9 and 2-mercaptobenzoxazole to the transparent mixed solution in sequence under stirring to prepare an electrically assisted passivation solution.

[0036] The passivation method of the electric-assisted passivation solution of this embodiment comprises the following steps: using an inert material (stainless steel plate) as an anode and an electroplated copper piece as a cathode, placing the anode and the cathode in the electric-assisted passivation solution of this embodiment for electric-assisted passivation, and the cathode current density is 150 mA / dm 2 , at room temperature for 2 min.

[0037] Comparative Example 1 A commercially available copper self-assembly protection solution has the following formula in 1L of solution: 0.5g 2-mercaptobenzothiazole, 300ml glacial acetic acid, 0.1g citric acid, and the rest is water.

[0038] The preparation method of the copper self-assembly protection liquid of this comparative example comprises the following steps: adding 0.5 g of 2-mercaptobenzothiazole to 300 ml of glacial acetic acid, then adding 0.1 g of citric acid, stirring until dissolved, and adding sufficient water to dilute to 1 L to obtain the copper self-assembly protection liquid.

[0039] The treatment conditions are as follows: the electroplated copper parts are cleaned and immersed in the copper self-assembly protection solution of this comparative example for 15 minutes at room temperature.

[0040] Comparative Example 2 A copper surface treatment liquid currently available on the market has a raw material formula of 12.5% ​​concentrated sulfuric acid, 15% benzotriazole, 0.4% p-hydroxybenzenesulfonic acid, 0.1% polyethylene glycol, and the balance water, calculated by mass percentage.

[0041] The treatment conditions are as follows: the electroplated copper parts are cleaned and immersed in the copper surface treatment solution of this comparative example at 50°C for 10 minutes.

[0042] Comparative Example 3 A commercially available water-soluble copper protective agent has the following raw material formula: 0.24 wt.% 5-phenyltetrazolyl, 0.16 wt.% 2-mercaptoimidazole, 0.4 wt.% 2-amino-5-mercapto-1,3,4-thiadiazole, 16 wt.% n-propanol, 3.6 wt.% sodium dodecylbenzene sulfonate, and the balance is water.

[0043] The treatment conditions are as follows: first heat the water-soluble copper protective agent to 60°C, then put the clean and dry electroplated copper parts in and immerse them at 60°C for 10 minutes.

[0044] Comparative Example 4 The raw material components and contents of the electrically assisted passivation solution of this comparative example are: 0.5 wt.% 2-mercaptobenzoxazole, 2 wt.% potassium hydroxide, and the balance is water.

[0045] The preparation method of the electric-assisted passivation solution of this comparative example comprises the following steps: S1. Under stirring, potassium hydroxide is added to water at a temperature of 40-60°C according to mass percentage to prepare a transparent mixed solution; in this comparative example, the water temperature is 40°C.

[0046] S2. Add 2-mercaptobenzoxazole to the transparent mixed solution under stirring to obtain an electrically assisted passivation solution.

[0047] The passivation method of the electrically assisted passivation solution of this comparative example is the same as that of Example 1.

[0048] Comparative Example 5 The raw material components and contents of the electric-assisted passivation solution for electroplating copper parts in this comparative example are: 0.5 wt.% 2-mercaptobenzoxazole, 2 wt.% potassium hydroxide, 1.5 wt.% AEO-7 (fatty alcohol polyoxyethylene ether), and the balance is water.

[0049] The method for preparing the electrically assisted passivation solution of this embodiment comprises the following steps: S1. Under stirring, potassium hydroxide is added to water at a temperature of 40-60°C according to mass percentage to prepare a transparent mixed solution; in this comparative example, the water temperature is 40°C.

[0050] S2. Add nonionic surfactant AEO-7 and 2-mercaptobenzoxazole to the transparent mixed solution in sequence under stirring to prepare an electrically assisted passivation solution.

[0051] The passivation method of the electric-assisted passivation solution in this comparative example is the same as that in Example 1.

[0052] Neutral salt spray test: The test was conducted in accordance with QB / T 3826-1999 Light Industry Product Metal Coating Corrosion Resistance Test Method. The plated parts prepared in the above five embodiments and five comparative examples were placed in a neutral salt spray test box, respectively, and the time when the surface began to change color was observed and recorded. The results are shown in Table 1. From the table, it can be seen that the shortest color change time of comparative examples 1, 2, 3, 4, and 5 is 8 hours, and the longest is 16 hours, while the embodiments of the present invention did not change color during this time, indicating that the corrosion resistance of the present invention is better than that of comparative examples 1, 2, 3, 4, and 5, and the film layer is thicker and more uniform.

[0053] Table 1 Corrosion resistance test results of various embodiments and comparative examples

[0054] Note: In Table 1, no color change is √, and color change is ×.

[0055] Although the present invention has been disclosed as above with preferred embodiments, it is not intended to limit the present invention. Any technician familiar with the art can make many possible changes and modifications to the technical solution of the present invention by using the technical content disclosed above without departing from the scope of the technical solution of the present invention, or modify it into an equivalent embodiment of equivalent changes. Therefore, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention should fall within the scope of protection of the technical solution of the present invention.

Claims

1. An electrically assisted passivation solution, characterized in that: The raw materials include 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 is water.

2. The electrically assisted passivation solution according to claim 1, characterized in that: The alkali-soluble mercapto compound is one or more of 2-mercaptobenzothiazole, 2-mercaptobenzoxazole, and 2-mercaptobenzimidazole.

3. The electrically assisted passivation solution according to claim 1, characterized in that: The amphoteric oxide is one or more of aluminum oxide, zinc oxide, and beryllium oxide.

4. The electrically assisted passivation solution according to claim 1, characterized in that: The inorganic base is one or both of sodium hydroxide and potassium hydroxide.

5. The electrically assisted passivation solution according to claim 1, characterized in that: The nonionic surfactant is one or more of polyoxyethylene sorbitan hexaoleate, polyoxyethylene sorbitan oleate, fatty alcohol polyoxyethylene ether, and polyethylene glycol octylphenyl ether.

6. A method for preparing the electrically assisted passivation solution according to any one of claims 1 to 5, characterized in that: The steps include: S1. Under stirring, the inorganic base and the amphoteric oxide are added to water at a temperature of 40-60° C. according to mass percentage to prepare a transparent mixed solution; S2. Under stirring, the nonionic surfactant and the alkali-soluble mercapto compound are added to the transparent mixed solution in sequence to obtain the electrically assisted passivation solution.

7. A passivation method using an electrically assisted passivation solution, characterized in that: The following steps are involved: An inert material is used as an anode and an electroplated copper part is used as a cathode, and the anode and the cathode are placed in the electrically assisted passivation solution according to any one of claims 1 to 5 for electrically assisted passivation treatment.

8. The passivation method according to claim 7, characterized in that: During the electric assisted passivation treatment, the cathode current density is 50-300 mA / dm 2 , passivation treatment was performed at room temperature for 1 to 3 min.

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