Chemical nickel plating solution capable of improving uniformity of plating layer, preparation method and use method

Abstract

The invention discloses a chemical nickel-plating solution capable of improving the uniformity of a plating layer, a preparation method and a use method, and belongs to the technical field of chemical nickel-plating solutions. Each liter of the chemical nickel-plating solution comprises the following components: 18.3-33.2 g of nickel salt; 8.5 to 9.8 g of a reducing agent; 12.5 to 14.3 g of a composite complexing agent; 11.2 to 28.7 g of a buffer agent; 5.3 to 8.8 g of a colloid stabilizer; and the balance of deionized water. The composite complexing agent is prepared from TiO2, the complexing agent A and the complexing agent B, TiO2 absorbs ultraviolet light energy and generates electron-hole pairs, electrostatic repulsive force between particles is increased, agglomeration is reduced, dispersion of TiO2 is promoted, TiO2 is coated with the complexing agent A and the complexing agent B, and then component stability of the composite complexing agent is promoted; after the colloidal stabilizer is added subsequently, the colloidal stabilizer can be adsorbed on the surfaces of the TiO2 particles, and meanwhile, the colloidal stabilizer can form a layer of macromolecular protective film around the TiO2 particles, so that the particles are further prevented from getting close to one another, the nickel plating solution is promoted to be uniformly dispersed, and the uniformity of a subsequent nickel plating layer is further facilitated.

Description

Technical Field

[0001] The present invention relates to the technical field of electroless nickel plating solutions, and particularly to an electroless nickel plating solution capable of improving the uniformity of the plating layer, a preparation method and a usage method thereof. Background Art

[0002] The electroless nickel plating technology is a method of depositing a nickel layer on the surface of a metal or non-metal by using a chemical reaction without an external current. It is commonly used in fields such as the automotive industry, the electronics industry, aerospace, and mechanical manufacturing.

[0003] The components of an electroless nickel plating solution generally include nickel salts, reducing agents, complexing agents, buffering agents, surfactants, stabilizers, etc. Common nickel salts include nickel sulfate, nickel chloride, nickel acetate, etc. Reducing agents include sodium hypophosphite, sodium borohydride, etc. Complexing agents include citric acid, malic acid, etc. Buffering agents include acetic acid-sodium acetate buffer systems, etc. Surfactants include non-ionic surfactants such as polyethylene glycol, anionic surfactants, etc. Stabilizers include heavy metal salts (such as lead acetate), etc.

[0004] However, when using heavy metal salt type stabilizers, it is difficult to treat the wastewater containing heavy metals, and the environmental friendliness is poor. At the same time, it is necessary to further improve the dispersion ability of the plating solution so that a uniform plating layer can be obtained on the substrate.

[0005] Based on this, the present invention designs an electroless nickel plating solution, a preparation method and a usage method capable of improving the uniformity of the plating layer to solve the above problems. Summary of the Invention

[0006] In view of the above-mentioned drawbacks of the prior art, the present invention provides an electroless nickel plating solution, a preparation method and a usage method capable of improving the uniformity of the plating layer.

[0007] To achieve the above objectives, the present invention is realized through the following technical solutions: An electroless nickel plating solution capable of improving the uniformity of the plating layer, and each 1 liter of the electroless nickel plating solution includes the following components: Nickel salt: 18.3 - 33.2 g; Reducing agent: 8.5 - 9.8 g; Composite complexing agent: 12.5 - 14.3 g; Buffering agent: 11.2 - 28.7 g; Colloidal stabilizer: 5.3 - 8.8 g; The balance is deionized water; The pH value of the electroless nickel plating solution is 6.5 - 7.1; The composite complexing agent is formed by mixing complexing agent A, complexing agent B and TiO2; The preparation method of the composite complexing agent is: Step (1): Pre-irradiate TiO2 with ultraviolet light at a light intensity of 22 - 35 mW / cm² for 3 - 5 minutes; Step (2): Mix complexing agent A and complexing agent B and stir evenly to obtain a mixed solution; Step (3): Add TiO2 to the mixed solution and continue to irradiate the mixed solution with ultraviolet light at a light intensity of 40 - 45 mW / cm² for 8 - 12 minutes, then dry for standby.

[0008] Furthermore, the nickel salt is selected from nickel sulfate, nickel chloride or nickel acetate.

[0009] Furthermore, the reducing agent is selected from sodium hypophosphite.

[0010] Furthermore, the composite complexing agent is composed of complexing agent A, complexing agent B and TiO2 mixed in a mass ratio of 3 - 5:1 - 2:0.05 - 0.1.

[0011] Furthermore, complexing agent A is obtained by dissolving disodium ethylenediaminetetraacetate and tartaric acid in deionized water, and the mass ratio of disodium ethylenediaminetetraacetate, tartaric acid and deionized water is 1 - 2:2 - 5:6 - 10.

[0012] Furthermore, complexing agent B is obtained by dissolving carboxymethyl cellulose and magnesium ascorbyl phosphate in deionized water, and the mass ratio of carboxymethyl cellulose, magnesium ascorbyl phosphate and deionized water is 3 - 5:2 - 3:100 - 180.

[0013] Furthermore, in step (2), complexing agent A and complexing agent B are mixed and stirred evenly at 32 - 36 °C to obtain a mixed solution.

[0014] Furthermore, the colloid stabilizer is obtained by dissolving xylitol and potassium iodide in deionized water, and the mass ratio of xylitol, potassium iodide and deionized water is 3 - 5:10:10 - 12.

[0015] To better achieve the purpose of the present invention, the present invention also provides a preparation method of electroless nickel plating solution that can improve the uniformity of the plating layer, including the following steps: Step a: Add 80% by mass of deionized water to a container, then slowly add the nickel salt to the deionized water while stirring, and control the stirring speed at 130 - 150 revolutions per minute to make the nickel ions evenly distributed in the solution; Step b: Add the composite complexing agent to the container, also slowly add and stir, and control the stirring speed at 200 - 255 revolutions per minute to make the composite complexing agent fully complex with the nickel ions; Step c: Then add the reducing agent and stir for 25 - 30 minutes, and control the stirring speed at 180 - 220 revolutions per minute; Step d: Then add a colloid stabilizer and stir for 10 - 15 minutes, with the stirring speed controlled at 200 - 250 revolutions per minute; Step e: Pre - irradiate the obtained solution with ultraviolet light, with the light intensity being 40 - 45 mW / cm² and the irradiation time being 10 - 15 minutes; Step f: Adjust the pH value to 6.5 - 7.1 with a buffer, and add the remaining deionized water to obtain an electroless nickel plating solution that can improve the uniformity of the plating layer.

[0016] To better achieve the object of the present invention, the present invention also provides a method for using an electroless nickel plating solution that can improve the uniformity of the plating layer. Immerse the substrate to be plated in the above - mentioned electroless nickel plating solution, control the plating temperature at 85 - 90 °C, and take it out until the plating layer reaches the required thickness.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. The present invention uses a colloid stabilizer (xylitol and potassium iodide) to replace the heavy - metal - salt - type stabilizer, increasing the environmental friendliness.

[0018] 2. The uniformity of the nickel - plating layer of the present invention is good, and the appearance of the plating layer is uniform and flat. A composite complexing agent is prepared by using TiO2, complexing agent A, and complexing agent B. TiO2 absorbs the energy of ultraviolet light to generate electron - hole pairs, and the electrostatic repulsive force between particles increases, thereby reducing agglomeration and promoting the dispersion of TiO2. The outside of TiO2 is coated with complexing agent A and complexing agent B, which further promotes the stability of the components of the composite complexing agent and improves the complexing effect of the composite complexing agent; after adding the colloid stabilizer subsequently, the colloid stabilizer can be adsorbed on the surface of TiO2 particles, and at the same time, the colloid stabilizer can form a polymer protective film around the TiO2 particles, further preventing the particles from approaching each other, promoting the uniform dispersion of the electroless nickel plating solution, and thus being beneficial to the uniformity of the subsequent nickel - plating layer and also beneficial to enhancing the bonding force between the plating layer and the workpiece to be plated. Specific embodiments

[0019] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without making creative efforts shall fall within the protection scope of the present invention.

[0020] Example 1: A preparation method of an electroless nickel plating solution that can improve the uniformity of the plating layer, including the following steps: Step a: Prepare a composite complexing agent; Step (1): Pre - irradiate TiO2 with ultraviolet light, with the light intensity being 22 mW / cm² and the irradiation time being 3 minutes; Step (2): Chelating agent A is obtained by dissolving 10 g of disodium ethylenediaminetetraacetate and 50 g of tartaric acid in 100 ml of deionized water; Chelating agent B is obtained by dissolving 30 g of carboxymethyl cellulose and 20 g of magnesium ascorbyl phosphate in 1000 ml of deionized water; 30 g of chelating agent A and 10 g of chelating agent B are mixed and stirred evenly at 32 °C to obtain a mixed solution; Step (3): Add 0.5 g of TiO2 to the mixed solution, and continue to irradiate the mixed solution with ultraviolet light. The light intensity is 40 mW / cm2, and the irradiation time is 8 minutes. Then dry it for standby; Step b: Prepare a colloid stabilizer: Dissolve 30 g of xylitol and 100 g of potassium iodide in 100 ml of deionized water; Step c: Weigh the raw materials: Each liter of electroless nickel plating solution includes the following components: nickel salt: 18.3 g, nickel sulfate; reducing agent: 8.5 g, sodium hypophosphite; composite chelating agent: 12.5 g; buffer: 11.2 g, acetic acid-sodium acetate buffer system, composed of acetic acid (CH3COOH) and sodium acetate (CH3COONa); colloid stabilizer: 5.3 g; the balance is deionized water; Step d: Add 80% by mass of deionized water to the container, and then slowly add the nickel salt to the deionized water while stirring. The stirring speed is controlled at 130 revolutions per minute to make the nickel ions evenly distributed in the solution; Step e: Add the composite chelating agent to the container, and also add it slowly while stirring. The stirring speed is controlled at 200 revolutions per minute to make the composite chelating agent fully complex with the nickel ions; Step f: Then add the reducing agent and stir for 25 minutes. The stirring speed is controlled at 180 revolutions per minute; Step g: Then add the colloid stabilizer and stir for 10 minutes. The stirring speed is controlled at 200 revolutions per minute; Step h: Pre-irradiate the obtained solution with ultraviolet light. The light intensity is 40 mW / cm2, and the irradiation time is 10 minutes; Step i: Adjust the pH value to 7.1 with the buffer, and add the remaining deionized water to obtain the electroless nickel plating solution that can improve the coating uniformity.

[0021] Example 2: A preparation method of an electroless nickel plating solution that can improve the coating uniformity includes the following steps: Step a: Prepare a composite chelating agent; Step (1): Pre-irradiate TiO2 with ultraviolet light. The light intensity is 35 mW / cm2, and the irradiation time is 5 minutes; Step (2): Chelating agent A is obtained by dissolving 30 g of disodium ethylenediaminetetraacetate and 60 g of tartaric acid in 180 ml of deionized water; Chelating agent B is obtained by dissolving 50 g of carboxymethyl cellulose and 30 g of magnesium ascorbyl phosphate in 1800 ml of deionized water; 50 g of chelating agent A and 20 g of chelating agent B are mixed and stirred evenly at 36 °C to obtain a mixed solution; Step (3): Add 1 g of TiO2 to the mixed solution, and continue to irradiate the mixed solution with ultraviolet light. The light intensity is 45 mW / cm², and the irradiation time is 12 minutes. Then dry it for standby; Step b: Prepare a colloid stabilizer: Dissolve 50 g of xylitol and 100 g of potassium iodide in 120 ml of deionized water; Step c: Weigh the raw materials: Each liter of electroless nickel plating solution includes the following components: nickel salt: 33.2 g, nickel chloride; reducing agent: 9.8 g, sodium hypophosphite; composite chelating agent: 14.3 g; buffer: 28.7 g, acetic acid-sodium acetate buffer system, composed of acetic acid (CH3COOH) and sodium acetate (CH3COONa); colloid stabilizer: 8.8 g; the balance is deionized water; Step d: Add 80% by mass of deionized water to the container, and then slowly add the nickel salt to the deionized water while stirring. The stirring speed is controlled at 150 revolutions per minute to make the nickel ions evenly distributed in the solution; Step e: Add the composite chelating agent to the container, and also add it slowly while stirring. The stirring speed is controlled at 255 revolutions per minute to make the composite chelating agent fully complex with the nickel ions; Step f: Then add the reducing agent and stir for 30 minutes. The stirring speed is controlled at 220 revolutions per minute; Step g: Then add the colloid stabilizer and stir for 15 minutes. The stirring speed is controlled at 250 revolutions per minute; Step h: Pre-irradiate the obtained solution with ultraviolet light. The light intensity is 45 mW / cm², and the irradiation time is 15 minutes; Step i: Adjust the pH value to 6.5 with the buffer, and add the remaining deionized water to obtain the electroless nickel plating solution that can improve the uniformity of the coating.

[0022] Example 3: A preparation method of an electroless nickel plating solution that can improve the uniformity of the coating, including the following steps: Step a: Prepare a composite chelating agent; Step (1): Pre-irradiate TiO2 with ultraviolet light. The light intensity is 25 mW / cm², and the irradiation time is 4 minutes; Step (2): Chelating agent A is obtained by dissolving 20 g of disodium ethylenediaminetetraacetate and 50 g of tartaric acid in 100 ml of deionized water; Chelating agent B is obtained by dissolving 40 g of carboxymethyl cellulose and 30 g of magnesium ascorbyl phosphate in 1500 ml of deionized water; 40 g of chelating agent A and 15 g of chelating agent B are mixed and stirred evenly at 33 °C to obtain a mixed solution; Step (3): Add 0.8 g of TiO2 to the mixed solution, and continue to irradiate the mixed solution with ultraviolet light. The light intensity is 42 mW / cm², and the irradiation time is 10 minutes. Then dry it for standby; Step b: Prepare a colloid stabilizer: Dissolve 40 g of xylitol and 100 g of potassium iodide in 110 ml of deionized water; Step c: Weigh the raw materials: Each liter of electroless nickel plating solution includes the following components: nickel salt: 25.4 g, nickel acetate; reducing agent: 9.3 g, sodium hypophosphite; composite chelating agent: 12.8 g; buffer: 22.6 g, acetic acid-sodium acetate buffer system, composed of acetic acid (CH3COOH) and sodium acetate (CH3COONa); colloid stabilizer: 7.1 g; the balance is deionized water; Step d: Add 80% by mass of deionized water to the container, and then slowly add the nickel salt to the deionized water while stirring. The stirring speed is controlled at 140 revolutions per minute to make the nickel ions evenly distributed in the solution; Step e: Add the composite chelating agent to the container, and also add it slowly and stir. The stirring speed is controlled at 220 revolutions per minute to make the composite chelating agent fully complex with the nickel ions; Step f: Then add the reducing agent and stir for 28 minutes. The stirring speed is controlled at 200 revolutions per minute; Step g: Then add the colloid stabilizer and stir for 13 minutes. The stirring speed is controlled at 240 revolutions per minute; Step h: Pre-irradiate the obtained solution with ultraviolet light. The light intensity is 44 mW / cm², and the irradiation time is 13 minutes; Step i: Adjust the pH value to 7.0 with the buffer, and add the remaining deionized water to obtain an electroless nickel plating solution that can improve the uniformity of the coating.

[0023] Comparative Example 1: The difference from Example 3 is that step h is missing.

[0024] Comparative Example 2: The difference from Example 3 is that step h is carried out first, and then step g is carried out.

[0025] Comparative Example 3: The difference from Example 3 is that the preparation of the composite chelating agent in step a is replaced by: directly blending TiO2, chelating agent A and chelating agent B.

[0026] Experimental Example: The workpieces to be plated (aluminum) were respectively placed in the electroless nickel plating solutions of Examples 1-3 and Comparative Examples 1-3 at 88 °C for 40 min to obtain plated workpieces, and the properties of each plated workpiece were detected. The results are shown in Table 1.

[0027] Detection of coating uniformity: Use a magnetic thickness gauge to measure the thickness of at least 10 randomly selected coating test points, and calculate the average thickness as h 平均 , select the maximum thickness h max and the minimum thickness h min , calculate e = (h max- h min ) ÷ h 平均 . When e < 5%, it indicates that the coating uniformity is good.

[0028] Test of the adhesion between the coating and the workpiece to be plated: A coating adhesion scratch tester.

[0029] Table 1 Performance test results

[0030] The nickel plating layer of the present invention has good uniformity, and the appearance of the coating is uniform and flat. A composite complexing agent is prepared by using TiO2, complexing agent A and complexing agent B. TiO2 absorbs the energy of ultraviolet light to generate electron-hole pairs, and the electrostatic repulsion force between particles increases, thereby reducing agglomeration and promoting the dispersion of TiO2. The outside of TiO2 is coated with complexing agent A and complexing agent B, which further promotes the stability of the components of the composite complexing agent and improves the complexing effect of the composite complexing agent; after adding a colloid stabilizer subsequently, the colloid stabilizer can be adsorbed on the surface of TiO2 particles, and at the same time, the colloid stabilizer can form a polymer protective film around the TiO2 particles, further preventing the particles from approaching each other, promoting the uniform dispersion of the electroless nickel plating solution, and further being beneficial to the uniformity of the subsequent nickel plating layer, and at the same time being beneficial to enhancing the adhesion between the coating and the workpiece to be plated.

[0031] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than limiting them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements will not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. Electroless nickel plating solution capable of improving coating uniformity, characterized in that, Each 1 liter of electroless nickel plating solution contains the following components: Nickel salt: 18.3 - 33.2 g; Reducing agent: 8.5 - 9.8 g; Composite complexing agent: 12.5 - 14.3 g; Buffer: 11.2 - 28.7 g; Colloid stabilizer: 5.3 - 8.8 g; The balance is deionized water; The pH value of the electroless nickel plating solution is 6.5 - 7.1; The composite complexing agent is composed of complexing agent A, complexing agent B and TiO2; The preparation method of the composite complexing agent is as follows: Step (1), pre-irradiate TiO2 with ultraviolet light, the light intensity is 22 - 35 mW / cm², and the irradiation time is 3 - 5 minutes; Step (2), mix complexing agent A and complexing agent B and stir evenly to obtain a mixed solution; Step (3), add TiO2 to the mixed solution, and continue to irradiate the mixed solution with ultraviolet light, the light intensity is 40 - 45 mW / cm², and the irradiation time is 8 - 12 minutes, then dry for standby.

2. The electroless nickel plating solution capable of improving the uniformity of the plating layer according to claim 1, characterized in that, The nickel salt is selected from nickel sulfate, nickel chloride or nickel acetate.

3. The electroless nickel plating solution capable of improving the uniformity of the plating layer according to claim 1, wherein The reducing agent is selected from sodium hypophosphite.

4. The electroless nickel plating solution capable of improving the uniformity of the plating layer according to claim 1, characterized in that, The composite complexing agent is composed of complexing agent A, complexing agent B and TiO2 in a mass ratio of 3 - 5:1 - 2:0.05 - 0.

1.

5. The electroless nickel plating solution capable of improving the uniformity of the coating according to claim 1, wherein The complexing agent A is obtained by dissolving disodium ethylenediaminetetraacetate and tartaric acid in deionized water, and the mass ratio of disodium ethylenediaminetetraacetate, tartaric acid and deionized water is 1 - 2:2 - 5:6 - 10.

6. The electroless nickel plating solution capable of improving the uniformity of the plating layer according to claim 1, wherein, The complexing agent B is obtained by dissolving carboxymethyl cellulose and magnesium ascorbyl phosphate in deionized water, and the mass ratio of carboxymethyl cellulose, magnesium ascorbyl phosphate and deionized water is 3 - 5:2 - 3:100 - 180.

7. The electroless nickel plating solution capable of improving the uniformity of the plating layer according to claim 1, wherein, In step (2), complexing agent A and complexing agent B are mixed and stirred evenly at 32 - 36 °C to obtain a mixed solution.

8. The electroless nickel plating solution capable of improving the uniformity of the plating layer according to claim 1, wherein The colloid stabilizer is obtained by dissolving xylitol and potassium iodide in deionized water, and the mass ratio of xylitol, potassium iodide and deionized water is 3 - 5:10:10 - 12.

9. A method for preparing an electroless nickel plating solution capable of improving the uniformity of the coating according to any one of claims 1-8, characterized in that, It includes the following steps: Step a, add 80% by mass of deionized water to the container, then slowly add the nickel salt to the deionized water while stirring, and control the stirring speed at 130 - 150 revolutions per minute to make the nickel ions evenly distributed in the solution; Step b, add the composite complexing agent to the container, and also slowly add and stir, and control the stirring speed at 200 - 255 revolutions per minute to make the composite complexing agent fully complex with the nickel ions; Step c, then add the reducing agent and stir for 25 - 30 minutes, and control the stirring speed at 180 - 220 revolutions per minute; Step d, then add the colloid stabilizer and stir for 10 - 15 minutes, and control the stirring speed at 200 - 250 revolutions per minute; Step e, pre-irradiate the obtained solution with ultraviolet light, the light intensity is 40 - 45 mW / cm², and the irradiation time is 10 - 15 minutes; Step f, adjust the pH value to 6.5 - 7.1 with the buffer, and add the balance of deionized water to obtain the electroless nickel plating solution that can improve the uniformity of the coating.

10. A method for using an electroless nickel plating solution capable of improving the uniformity of the plating layer according to any one of claims 1-8, characterized in that, Immerse the substrate to be plated in the above-mentioned electroless nickel plating solution, control the plating temperature at 85 - 90 °C, and take it out until the coating reaches the required thickness.

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