Corrosion-resistant chromium-free passivator special for copper and copper alloy and preparation method of corrosion-resistant chromium-free passivator

Abstract

The invention belongs to the field of corrosion inhibition of metal materials, and discloses a special corrosion-resistant chromium-free passivator for copper and copper alloy and a preparation method thereof, and the passivator comprises the following components: borax, sodium phosphate, benzotriazole, ethanol, sodium ethylene diamine tetracetate, anhydrous sodium molybdate, a strong oxidant, a silane coupling agent and water. Under the synergistic effect of all the components, the chromium-free passivator can form a composite passivation film on the surfaces of copper and copper alloy, oxidation discoloration of the copper and copper alloy is effectively prevented, the conductivity and welding performance of the copper and copper alloy are not affected, and the chromium-free passivator is low in cost, stable in performance and convenient and fast to use.

Description

Technical Field

[0001] The present invention belongs to the field of corrosion inhibition of metal materials, and in particular relates to a special corrosion-resistant chromium-free passivating agent for copper and copper alloys and a preparation method thereof. Background Art

[0002] In electronic products, the copper coating has good electrical conductivity, thermal conductivity, solderability, stability, and reliable adhesion to the substrate. Therefore, electroplated copper is widely used in industries such as electronics, communications, electrical engineering, and decoration. In particular, it is often subjected to copper plating in the manufacturing process of electronic connectors, semiconductors (LEDs), integrated circuit lead frames (IC load frames), and filters. During the production, transportation, installation, and use of these electronic components, when exposed to gases such as H2S, SO2, CO2, and NO in the environment, or even when exposed to ultraviolet light, corresponding corrosion products are easily generated on the surface of the copper coating, causing it to discolor and blacken, which greatly damages the original electrical properties of the copper coating. Therefore, it is necessary to perform an anti-corrosion treatment on the copper coating to prevent copper and its alloys from being oxidized, discolored, or corroded in the environment of use, thereby preventing the occurrence of problems such as increased contact resistance, decreased solderability, and reduced service life of electronic products.

[0003] At present, chemical passivation, electrolytic passivation, and solvent-based passivation can all be used to improve the corrosion and discoloration of the copper coating to varying degrees. However, the existing chemical passivation and electrolytic passivation methods are prone to Cr pollution due to the use of chromate as an inorganic passivator, and although solvent-based passivation avoids the addition of Cr, the solvents therein can pollute the air and worsen the operating environment, and most solvents are carcinogenic. In addition, the protective film layer formed on the surface of the copper coating by the above-mentioned methods is relatively thick, which can affect the conductivity of the copper coating and reduce its solderability. Therefore, it is necessary to study a corrosion-resistant chromium-free passivator for copper and copper alloys to overcome the defects of the prior art. Summary of the Invention

[0004] In response to the deficiencies in the above-mentioned prior art, the present invention provides a special corrosion-resistant chromium-free passivator for copper and copper alloys and a preparation method thereof, aiming to significantly improve the corrosion resistance of copper and copper alloy surfaces by regulating the formula of the passivator, effectively prevent oxidation and discoloration of copper and its alloys without affecting their electrical conductivity and welding properties.

[0005] In order to solve the technical problem, the present invention adopts the following technical solutions: The present invention first provides a special corrosion-resistant chromium-free passivating agent for copper and copper alloys. The passivating agent comprises the following components in parts by weight: 40-90 parts of borax, 70-150 parts of sodium phosphate, 40-80 parts of benzotriazole, 30-90 parts of ethanol, 80-150 parts of sodium ethylenediaminetetraacetate, 90-170 parts of anhydrous sodium molybdate, 20-70 parts of a strong oxidizing agent, 20-70 parts of a silane coupling agent, and 500-1000 parts of water.

[0006] As a further improvement of the present invention, the corrosion-resistant chromium-free passivator specifically for copper and copper alloys comprises the following components in parts by weight: 60 parts of borax, 90 parts of sodium phosphate, 60 parts of benzotriazole, 60 parts of ethanol, 80 parts of sodium ethylenediaminetetraacetate, 130 parts of anhydrous sodium molybdate, 40-70 parts of a strong oxidant, 40 parts of a silane coupling agent, and 700 parts of water.

[0007] As a further improvement of the present invention, the special corrosion-resistant chromium-free passivator for copper and copper alloys includes the following components in parts by weight: 60 parts of borax, 90 parts of sodium phosphate, 60 parts of benzotriazole, 60 parts of ethanol, 80 parts of sodium ethylenediaminetetraacetic acid, 130 parts of anhydrous sodium molybdate, 70 parts of a strong oxidant, 40 parts of a silane coupling agent, and 700 parts of water.

[0008] As a further improvement of the present invention, the silane coupling agent is γ-(2,3-epoxypropoxy)propyltrimethoxysilane or γ-aminopropyltriethoxysilane.

[0009] As a further improvement to the present invention, the strong oxidant is sodium nitrite, potassium permanganate or hydrogen peroxide.

[0010] The present invention further provides a preparation method of the special corrosion-resistant chromium-free passivator for copper and copper alloys, comprising the following steps: adding 200 to 300 parts of water into a closed reactor, uniformly mixing borax, sodium phosphate, benzotriazole, anhydrous sodium molybdate, a strong oxidant and a silane coupling agent, and then adding the mixture into the reactor, maintaining the temperature of the reactor at 40 to 70° C., stirring and reacting for 0.5 to 1 hour, then adding ethanol and sodium ethylenediaminetetraacetic acid and stirring evenly, cooling, adding the remaining water and stirring evenly, thereby obtaining the special corrosion-resistant chromium-free passivator for copper and copper alloys.

[0011] As a further improvement to the present invention, the temperature of the reactor is maintained at 60°C.

[0012] The method for using the special corrosion-resistant chromium-free passivator for copper and copper alloys of the present invention is as follows: a copper sheet is placed in the passivator and soaked for 5 to 10 minutes, and then placed in a 60 to 80° C. oven for drying for 0.5 to 1 hour.

[0013] The beneficial effects of the present invention are embodied in: The chromium-free passivator of the present invention can significantly reduce the external corrosion of copper and copper alloys. Among its components: benzotriazole can prevent the reaction between oxygen in the air and the passivator; the strong oxidant oxidizes copper into an ionic state to promote the formation of a passivation film; the silane coupling agent hydrolyzes to generate silanol and OH - The silane film is combined to further seal the passivation film and improve the density of the film layer; borax can play a bactericidal and antibacterial role; sodium phosphate and anhydrous sodium molybdate can react with copper surface oxides to form heteropolyacid metal salts, which play an inorganic passivation role on copper and its alloys; ethanol as a cosolvent can improve the dispersibility of each component in the passivator; sodium ethylenediaminetetraacetic acid as a chelating agent, chelates with copper surface ions, and further passivates them. Under the synergistic effect of each component, the chromium-free passivator of the present invention can form a composite passivation film on the surface of copper and its alloys, effectively preventing copper and its alloys from oxidizing and discoloring, and the present invention adopts a chemical immersion method, and the protective layer formed is relatively thin, which does not affect the conductivity and welding performance of copper and its alloys. The chromium-free passivator of the present invention is low in cost, stable in performance, can be stored at room temperature, is convenient and quick to use, and basically does not change the color of the metal. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a Tafel plot of the copper sheet treated with passivator-1 in Example 1 in 3.5% salt water.

[0015] Figure 2 The copper sheet treated with the passivator-1 in Example 1 ( Figure 2 (b)) and blank copper sheet ( Figure 2 (a) SEM image after nitric acid spot etching.

[0016] Figure 3 It is a Tafel plot of the copper sheet treated with passivator-2 in Example 2 in 3.5% salt water.

[0017] Figure 4 The copper sheet treated with the passivator-2 in Example 2 ( Figure 4 (b)) and blank copper sheet ( Figure 4 (a) SEM image after nitric acid spot etching.

[0018] Figure 5 It is a Tafel plot of the copper sheet treated with passivator-3 in Example 3 in 3.5% salt water.

[0019] Figure 6 The copper sheet treated with the passivator-3 in Example 3 ( Figure 6 (b)) and blank copper sheet ( Figure 6 (a) SEM image after nitric acid spot etching.

[0020] Figure 7It is a Tafel plot of the copper sheet treated with passivator-4 in Example 4 in 3.5% salt water.

[0021] Figure 8 It is a Tafel plot of the copper sheet treated with passivator-5 in Example 5 in 3.5% salt water.

[0022] Figure 9 It is a Tafel plot of the copper sheet treated with passivator-6 in Example 6 in 3.5% salt water. DETAILED DESCRIPTION

[0023] In order to make the above-mentioned objects, features and advantages of the present invention more clearly understood, the following detailed description of the specific embodiments of the present invention is given in conjunction with the accompanying drawings. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0024] Example 1 This embodiment provides a corrosion-resistant, chromium-free passivating agent specifically for copper and copper alloys, comprising the following components, measured by weight: 60 parts borax, 90 parts sodium phosphate, 60 parts benzotriazole, 60 parts ethanol, 80 parts sodium ethylenediaminetetraacetic acid, 130 parts anhydrous sodium molybdate, 40 parts strong oxidizing agent, 40 parts silane coupling agent, and 700 parts water. The silane coupling agent is γ-aminopropyltriethoxysilane, and the strong oxidizing agent is sodium nitrite.

[0025] The preparation method of the above-mentioned corrosion-resistant chromium-free passivator for copper and copper alloys comprises the following steps: adding 250 parts of water into a closed reactor, then uniformly mixing borax, sodium phosphate, benzotriazole, anhydrous sodium molybdate, a strong oxidant and a silane coupling agent, adding the mixture into the reactor, maintaining the reactor temperature at 60°C, and stirring for 40 minutes; then adding ethanol and sodium ethylenediaminetetraacetic acid and stirring evenly, cooling, adding the remaining water and stirring evenly, thereby obtaining a corrosion-resistant chromium-free passivator for copper and copper alloys, which is recorded as Passivator-1.

[0026] The method of using the special corrosion-resistant chromium-free passivator for copper and copper alloys obtained in this embodiment is as follows: soak the copper sheet in the passivator for 10 minutes, and then dry the copper sheet in a 70° C. oven for 45 minutes.

[0027] Figure 1 The Tafel curve of the copper sheet treated with the passivator-1 in this example in 3.5% salt water is shown in Table 1. The corresponding electrochemical parameters are detailed in Table 1. The results show that the corrosion potential of the copper sheet treated with the passivator-1 is 0.133°C compared with the blank copper sheet without passivation treatment. E corr The current density of the cathode curve and the anodic curve decreased significantly. I corrCompared with the blank copper sheet, it has dropped by an order of magnitude, indicating that the electrochemical activity of the copper sheet surface is significantly reduced, that is, the electrochemical corrosion of the copper sheet in salt water is significantly inhibited, and the corrosion inhibition efficiency is significantly reduced. η Reaching 77.4%.

[0028] Nitric acid and water were mixed in a volume ratio of 3:10 to obtain a nitric acid solution, which was then dropped onto the surface of the copper sheet treated with passivator-1. A nitric acid droplet corrosion test was performed with a droplet time of 15 s. A blank copper sheet was used as a comparison. Figure 2 This is the SEM picture of the sample after nitric acid spot etching. Figure 2 (a) corresponds to a blank copper sheet, and (b) corresponds to a copper sheet treated with Passivator-1. As shown in the figure, after nitric acid spot etching, the metal film on the copper sheet treated with Passivator-1 is smoother and less susceptible to acid attack than the unpassivated copper sheet. In contrast, the blank copper sheet has a rough surface with scaly protrusions, exhibiting severe corrosion and damage to the metal film. This demonstrates that the passivator of this example significantly improves copper's corrosion resistance.

[0029] Example 2 This embodiment provides a corrosion-resistant, chromium-free passivating agent specifically for copper and copper alloys, comprising the following components, by weight: 60 parts borax, 90 parts sodium phosphate, 60 parts benzotriazole, 60 parts ethanol, 80 parts sodium ethylenediaminetetraacetate, 130 parts anhydrous sodium molybdate, 40 parts strong oxidizing agent, 40 parts silane coupling agent, and 700 parts water. The silane coupling agent is γ-(2,3-epoxypropyloxy)propyltrimethoxysilane, and the strong oxidizing agent is hydrogen peroxide.

[0030] The chromium-free passivator of this embodiment is recorded as passivator-2, and its preparation and use methods are the same as those in Example 1.

[0031] Figure 3 The following is a Tafel curve of the copper sheet treated with passivator-2 in 3.5% salt water. The corresponding electrochemical parameters are detailed in Table 1. The results show that the corrosion current density of the copper sheet treated with passivator-2 is 2.33°C compared with the blank copper sheet without passivation treatment. I corr The Tafel curve has a lower current density and a larger polarization resistance. R p , corrosion inhibition efficiency η It reaches 74.2%, indicating that the corrosion resistance of the copper sheet is significantly improved after passivation treatment.

[0032] Figure 4 This is the SEM picture of the sample after nitric acid drop etching. Figure 4(a) corresponds to a blank copper sheet, and (b) corresponds to a copper sheet treated with Passivator-2. As shown in the figure, after nitric acid spot etching, the metal film layer on the surface of the copper sheet treated with Passivator-2 is smoother than that of the unpassivated copper sheet, showing no significant acid attack. This demonstrates that the passivator of this example can significantly improve the corrosion resistance of copper.

[0033] Example 3 This embodiment provides a special corrosion-resistant chromium-free passivator for copper and copper alloys, including the following components in parts by weight: 60 parts of borax, 90 parts of sodium phosphate, 60 parts of benzotriazole, 60 parts of ethanol, 80 parts of sodium ethylenediaminetetraacetate, 130 parts of anhydrous sodium molybdate, 40 parts of a strong oxidant, 40 parts of a silane coupling agent, and 700 parts of water.

[0034] The silane coupling agent is γ-aminopropyltriethoxysilane, and the strong oxidant is potassium permanganate.

[0035] The chromium-free passivator of this embodiment is designated as Passivator-3, and its preparation and use methods are the same as those of Example 1. Figure 5 The Tafel curve of the copper sheet treated with passivator-3 in 3.5% salt water is shown in Table 1. The corresponding electrochemical parameters are detailed in Table 1. Compared with the blank copper sheet, the cathode curve and the anodic curve of the copper sheet treated with passivator-3 are significantly negatively shifted, and the corrosion current density is I corr Significantly reduced corrosion inhibition efficiency η It reaches 70.8%, indicating that the corrosion resistance of the copper sheet treated with passivator-3 is significantly improved.

[0036] Figure 6 This is the SEM picture of the sample after nitric acid spot etching. Figure 6 (a) corresponds to a blank copper sheet, and (b) corresponds to a copper sheet treated with Passivator-3. As shown in the figure, after nitric acid spot etching, the metal film layer on the surface of the copper sheet treated with Passivator-3 is smoother than that of the unpassivated copper sheet, showing no significant acid attack. This demonstrates that the passivator of this example can significantly improve the corrosion resistance of copper.

[0037] Example 4 This embodiment provides a corrosion-resistant, chromium-free passivating agent specifically for copper and copper alloys, comprising the following components, measured by weight: 60 parts borax, 90 parts sodium phosphate, 60 parts benzotriazole, 60 parts ethanol, 80 parts sodium ethylenediaminetetraacetic acid, 130 parts anhydrous sodium molybdate, 70 parts strong oxidizing agent, 40 parts silane coupling agent, and 700 parts water. The silane coupling agent is γ-aminopropyltriethoxysilane, and the strong oxidizing agent is sodium nitrite.

[0038] The chromium-free passivator of this embodiment is designated as Passivator-4, and its preparation and use methods are the same as those of Example 1.

[0039] Figure 7 The following is a comparison of the Tafel curves of the copper sheet treated with Passivator-4 in this example and the copper sheet treated with Passivator-1 in Example 1 in 3.5% salt water. The corresponding electrochemical parameters are detailed in Table 1. The results show that the copper sheet treated with Passivator-4 has a negative shift in both the cathode and anodic curves compared to the copper sheet treated with Passivator-1, and the copper sheet treated with Passivator-4 has a lower corrosion current density. I corr and higher polarization resistance R p , corrosion inhibition efficiency η It can reach 90.5%. It can be seen that passivator-4 has a greater degree of inhibition on the electrochemical corrosion of the copper surface, indicating that increasing the amount of strong oxidant sodium nitrite can improve the corrosion resistance of the passivator on the copper.

[0040] The conductivity of the copper sheet treated with passivator-4 was tested against a blank copper sheet of the same area (using a Recto resistivity meter, FT-361). The results showed that the conductivity of the blank copper sheet (22438.9 S / mm) was similar to that of the copper sheet treated with passivator-4 (23915.8 S / mm), indicating that passivator-4 had no significant effect on the conductive properties of the copper sheet.

[0041] Example 5 This embodiment provides a corrosion-resistant, chromium-free passivating agent specifically for copper and copper alloys, comprising the following components, by weight: 60 parts borax, 90 parts sodium phosphate, 60 parts benzotriazole, 60 parts ethanol, 80 parts sodium ethylenediaminetetraacetate, 130 parts anhydrous sodium molybdate, 70 parts strong oxidizing agent, 40 parts silane coupling agent, and 700 parts water. The silane coupling agent is γ-(2,3-epoxypropyloxy)propyltrimethoxysilane, and the strong oxidizing agent is hydrogen peroxide.

[0042] The chromium-free passivator of this embodiment is designated as Passivator-5, and its preparation and use methods are the same as those of Example 1.

[0043] Figure 8 The following is a comparison of the Tafel curves of the copper sheet treated with Passivator-5 in this example and the copper sheet treated with Passivator-2 in Example 2 in 3.5% salt water. The corresponding electrochemical parameters are detailed in Table 1. The results show that the cathode and anodic curves of the copper sheet treated with Passivator-5 have different degrees of negative shift compared with the copper sheet treated with Passivator-2, and the copper sheet treated with Passivator-5 has a lower current density. I corr and higher polarization resistance R p , corrosion inhibition efficiency ηIt reaches 85.4%, which shows that passivator-5 has a greater degree of inhibition on the electrochemical corrosion of the copper surface.

[0044] The resistivity of the copper sheet treated with passivator-5 was tested against a blank copper sheet of the same area (using a Ruike resistivity meter, FT-361). The results showed that the conductivity of the blank copper sheet (22438.9 S / mm) was similar to that of the copper sheet treated with passivator-5 (23409.7 S / mm), indicating that passivator-5 had no significant effect on the conductive properties of the copper sheet.

[0045] Example 6 This embodiment provides a special corrosion-resistant chromium-free passivator for copper and copper alloys, including the following components in parts by weight: 60 parts of borax, 90 parts of sodium phosphate, 60 parts of benzotriazole, 60 parts of ethanol, 80 parts of sodium ethylenediaminetetraacetate, 130 parts of anhydrous sodium molybdate, 70 parts of a strong oxidant, 40 parts of a silane coupling agent, and 700 parts of water.

[0046] The silane coupling agent is γ-aminopropyltriethoxysilane, and the strong oxidant is potassium permanganate.

[0047] The chromium-free passivator of this embodiment is designated as Passivator-6, and its preparation and use methods are the same as those of Example 1.

[0048] Figure 9 This is a comparison of the Tafel plots of the copper sheet treated with Passivator-6 of this example and the copper sheet treated with Passivator-3 in Example 3 in 3.5% salt water. Details of the corresponding electrochemical parameters are shown in Table 1. The results show that the cathode curve of the copper sheet treated with Passivator-6 has a certain negative shift compared to the copper sheet treated with Passivator-3, while the anodic curve does not change significantly. Increasing the amount of potassium permanganate, a strong oxidant, does not significantly improve the passivation ability of the passivator.

[0049] Table 1 Electrochemical parameters of copper sheets treated with passivating agents in various examples The above description is merely a preferred embodiment of the present invention, and its description is relatively specific and detailed, but it should not be construed as limiting the scope of the invention. It should be noted that those skilled in the art may make various improvements and equivalent substitutions without departing from the principles of the present invention, and such improvements and substitutions should also be considered within the scope of protection of the present invention.

Claims

1. A corrosion-resistant chromium-free passivating agent for copper and copper alloys, characterized in that: The invention comprises the following components in parts by weight: 40-90 parts of borax, 70-150 parts of sodium phosphate, 40-80 parts of benzotriazole, 30-90 parts of ethanol, 80-150 parts of sodium ethylenediaminetetraacetate, 90-170 parts of anhydrous sodium molybdate, 20-70 parts of a strong oxidant, 20-70 parts of a silane coupling agent, and 500-1000 parts of water.

2. The corrosion-resistant chromium-free passivator for copper and copper alloys according to claim 1, characterized in that: The invention comprises the following components in parts by weight: 60 parts of borax, 90 parts of sodium phosphate, 60 parts of benzotriazole, 60 parts of ethanol, 80 parts of sodium ethylenediaminetetraacetate, 130 parts of anhydrous sodium molybdate, 40-70 parts of a strong oxidant, 40 parts of a silane coupling agent and 700 parts of water.

3. The corrosion-resistant chromium-free passivating agent for copper and copper alloys according to claim 2, characterized in that: The invention comprises the following components in parts by weight: 60 parts of borax, 90 parts of sodium phosphate, 60 parts of benzotriazole, 60 parts of ethanol, 80 parts of sodium ethylenediaminetetraacetate, 130 parts of anhydrous sodium molybdate, 70 parts of a strong oxidant, 40 parts of a silane coupling agent and 700 parts of water.

4. The corrosion-resistant chromium-free passivating agent for copper and copper alloys according to claim 1, 2 or 3, characterized in that: The silane coupling agent is γ-(2,3-epoxypropoxy)propyltrimethoxysilane or γ-aminopropyltriethoxysilane.

5. The corrosion-resistant chromium-free passivating agent for copper and copper alloys according to claim 1, 2 or 3, characterized in that: The strong oxidant is sodium nitrite, potassium permanganate or hydrogen peroxide.

6. A method for preparing the corrosion-resistant chromium-free passivating agent for copper and copper alloys according to any one of claims 1 to 5, characterized in that: The method comprises the following steps: adding 200-300 parts of water into a closed reactor, uniformly mixing borax, sodium phosphate, benzotriazole, anhydrous sodium molybdate, a strong oxidant and a silane coupling agent, and then adding the mixture into the reactor, maintaining the temperature of the reactor at 40-70 DEG C, stirring and reacting for 0.5-1 hour, then adding ethanol and sodium ethylenediaminetetraacetate and stirring evenly, cooling, adding the remaining water and stirring evenly, thereby obtaining a special corrosion-resistant chromium-free passivating agent for copper and copper alloys.

7. The preparation method according to claim 6, characterized in that The reactor temperature was maintained at 60°C.

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