A post-dipping cleaning solution for phosphorus acid type electroless nickel plating process and a preparation method thereof

Abstract

The application discloses a phosphoric acid type electroless nickel plating process post-dipping cleaning solution and a preparation method, relates to the technical field of post-dipping, and the post-dipping cleaning solution comprises the following raw materials in mass fractions: 30-60 parts of phosphoric acid; 0.1-1.5 parts of a complexing agent; 0.2-0.5 parts of a promoter; 3-8 parts of a solubilizing agent; 0.2-0.4 parts of a dissociation agent; 0.2-0.4 parts of a composite wetting agent; and 929.2-966.3 parts of deionized water. The promoter in the application attacks the active position of palladium ions, and when the palladium ions leave the active position, the palladium ions are quickly separated from the surface of the substrate under the adsorption of the dissociation agent with strong electronegativity. Meanwhile, the composite wetting agent can improve the dispersibility of the promoter and the dissociation agent, improve the uniform dispersion effect, and inhibit the re-adsorption of ruthenium ions, palladium ions and introduced impurity metal ions to the surface of the substrate.

Description

Technical Field

[0001] This invention relates to the field of post-immersion technology, and more specifically, to a post-immersion cleaning solution and its preparation method for a phosphoric acid-based electroless nickel plating process. Background Technology

[0002] As the lines on printed circuit boards and substrates become increasingly refined, burrs increase during normal activation, significantly impacting product quality. Patent CN107815671B discloses a special post-immersion agent for electroless nickel plating and a method for gold plating on printed circuit boards, comprising sodium dodecylbenzenesulfonate, potassium fatty acid, and ammonium triacetate. While the electroless nickel plating agent is a weakly alkaline reagent, it lacks a dissociation agent for activated ions, and due to the presence of numerous surfactant bubbles, a large amount of cleaning agent residue remains during production.

[0003] In addition, patent CN115478266B discloses an activated post-immersion solution for a carrier board and a method for electroless nickel-gold plating of the carrier board. The activated post-immersion solution for the carrier board includes the following components: passivating agent, complexing agent, dispersant, inorganic salt and water. It can be used to clean ink on high-precision circuits (such as carrier boards) and palladium ions adsorbed on PP sheet areas. It can achieve a good post-immersion effect and has a good removal effect on palladium ions. It can achieve no seepage or missed plating after nickel-gold plating. However, because sodium sulfide is used to complex palladium ions, black plating will occur in the production of high-end products as the amount added accumulates.

[0004] No effective solutions have yet been proposed to address the problems in the relevant technologies. Summary of the Invention

[0005] To address the problems in related technologies, this invention proposes a post-immersion cleaning solution and its preparation method for a phosphoric acid-based electroless nickel plating process, thereby overcoming the aforementioned technical problems existing in the prior art.

[0006] Therefore, the specific technical solution adopted by the present invention is as follows:

[0007] According to one aspect of the present invention, a post-immersion cleaning solution for a phosphoric acid-based electroless nickel plating process is provided, the post-immersion cleaning solution comprising the following raw materials in parts by weight:

[0008] 30-60 parts of phosphoric acid;

[0009] Complexing agent 0.1-1.5 parts;

[0010] Accelerator 0.2-0.5 parts;

[0011] 3-8 parts of solubilizer;

[0012] Dissociation agent 0.2-0.4 parts;

[0013] 0.2-0.4 parts of compound wetting agent;

[0014] 929.2-966.3 parts of deionized water.

[0015] Preferably, the complexing agent is 5-amino-2-pyrazinic acid.

[0016] Preferably, the promoter is 1,5-dimethyl-1H-imidazol-4-carboxylic acid.

[0017] Preferably, the solubilizer is glycerol α,α'-diallyl ether.

[0018] Preferably, the dissociation agent is 1-hexylpyridine trifluoromethanesulfonate.

[0019] Preferably, the composite wetting agent comprises sodium alkylnaphthalene sulfonate and o-aminoanisole-4-sulfonic acid, and the mass concentration ratio of sodium alkylnaphthalene sulfonate to o-aminoanisole-4-sulfonic acid is 1:1.

[0020] According to another aspect of the present invention, a method for preparing a post-immersion cleaning solution for a phosphoric acid-based electroless nickel plating process is provided, the method comprising the following steps:

[0021] S1. Dissolve the solubilizer and phosphoric acid in a predetermined volume of deionized water according to the mass ratio, then heat and stir until completely dissolved to obtain solution A;

[0022] S2. Dissolve the complexing agent, dissociating agent, and composite wetting agent in a predetermined volume of deionized water according to the mass ratio to obtain solution B;

[0023] S3. Mix solution A and solution B to obtain solution C, and then add deionized water to the predetermined final volume;

[0024] S4. When using the solution, first check for any precipitate, and then clean it by spraying.

[0025] Preferably, the heating temperature during the preparation of solution A is 45-55℃, and the magnetic stirring speed is 300-500 rpm.

[0026] During use, the spray temperature should be 30-40℃, and the spray pressure should be 1.0-2.0 kg / cm². 2 .

[0027] Preferably, during the preparation process, the pH of the solution is controlled between 0.5 and 1.5, and the operating temperature is 35-45℃. If the pH is too low, it is adjusted with 5% sodium hydroxide solution, and if the pH is too high, it is adjusted with 10% phosphoric acid.

[0028] Preferably, the test solution is checked for any precipitate. If precipitate is present, the pH is first measured to ensure it is normal.

[0029] If the pH is abnormal, adjust the pH to the normal range and then observe whether the precipitate dissolves. If precipitate still forms even when the pH is normal, the solution in the preparation tank needs to be replaced.

[0030] The beneficial effects of this invention are as follows:

[0031] 1. The accelerator in this invention is an alkylimidazolium carboxylic acid compound. Compared with the traditionally used aminothiazole compounds, this accelerator is more efficient. For activation times exceeding twice the normal usage time, this accelerator can promote the dissociation of the dissociating agent within a specified time. The accelerator will attack the active site of palladium ions. When palladium ions leave the active site, they will quickly detach from the substrate surface under the strong adsorption of the dissociating agent.

[0032] 2. The dissociation agent in this invention is an alkylpyridine heterocyclic polyfluorosulfonate compound, which has high electronegativity and excellent comprehensive effect on various activating ions such as palladium ions and ruthenium ions.

[0033] 3. The solubilizer in this invention can promote the dissolution of the accelerator, and the accelerator is also aggressive towards the active sites of impurity ions adsorbed on the substrate surface. When the dissociation agent combines with it, the solubilizer will also promote their detachment from the substrate surface.

[0034] 4. The composite wetting agent in this invention can improve the dispersibility of the accelerator and the dissociation agent, improve the uniform dispersion effect, and at the same time inhibit the re-adsorption of ruthenium ions, palladium ions and introduced impurity metal ions onto the substrate surface. Attached Figure Description

[0035] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0036] Figure 1 This is a flowchart of a method for preparing a post-immersion cleaning solution in a phosphoric acid-based electroless nickel plating process according to an embodiment of the present invention. Detailed Implementation

[0037] To further illustrate the various embodiments, the present invention provides accompanying drawings, which are part of the disclosure of the present invention. These drawings are mainly used to illustrate the embodiments and can be used in conjunction with the relevant descriptions in the specification to explain the operating principles of the embodiments. With reference to these drawings, those skilled in the art should be able to understand other possible implementation methods and the advantages of the present invention. The components in the drawings are not drawn to scale, and similar component symbols are generally used to represent similar components.

[0038] According to embodiments of the present invention, a post-immersion cleaning solution and its preparation method are provided for a phosphoric acid-based electroless nickel plating process.

[0039] The present invention will now be further described with reference to the accompanying drawings and specific embodiments. According to one embodiment of the present invention, a post-immersion cleaning solution for a phosphoric acid-based electroless nickel plating process is provided, the post-immersion cleaning solution comprising the following raw materials in parts by weight:

[0040] 30-60 parts of phosphoric acid;

[0041] Complexing agent 0.1-1.5 parts;

[0042] Accelerator 0.2-0.5 parts;

[0043] 3-8 parts of solubilizer;

[0044] Dissociation agent 0.2-0.4 parts;

[0045] 0.2-0.4 parts of compound wetting agent;

[0046] 929.2-966.3 parts of deionized water.

[0047] In a preferred embodiment, the complexing agent is 5-amino-2-pyrazinic acid.

[0048] It should be explained that 5-amino-2-pyrazine carboxylic acid is an organic compound with the chemical formula C5H5N3O2. It belongs to the pyrazine derivative class. Its structure consists of a pyrazine ring (a six-membered heterocycle containing two nitrogen atoms) with a carboxyl group (-COOH) at the 2-position and an amino group (-NH2) at the 5-position. This compound has both the acidity of carboxylic acids and the basicity of amino groups.

[0049] In a preferred embodiment, the accelerator is 1,5-dimethyl-1H-imidazol-4-carboxylic acid.

[0050] It should be explained that 1,5-dimethyl-1H-imidazol-4-carboxylic acid is a nitrogen-containing heterocyclic organic compound with the chemical formula C6H8N2O2. Its structural features include a methyl group (-CH3) attached to the 1 and 5 positions of the imidazolium ring (a five-membered diazonium heterocycle), and a carboxyl group (-COOH) at the 4 position. The carboxyl group in its molecule gives it acidity (pKa≈4.5), and the nitrogen atom of the imidazolium ring can participate in coordination reactions.

[0051] In a preferred embodiment, the solubilizer is glycerol α,α'-diallyl ether.

[0052] It should be noted that glycerol α,α'-diallyl ether is an allyl ether derivative of glycerol (glycerol), with the chemical formula C9H. 16 O3 is characterized by the substitution of two primary hydroxyl groups (α and α' positions) in the glycerol molecule by allyloxy groups (-O-CH2-CH=CH2), while retaining one secondary hydroxyl group. This compound combines the chemical stability of the ether bond with the reactivity of the allyl group (it can be functionalized through thiol-ene click chemistry or free radical polymerization).

[0053] In a preferred embodiment, the dissociating agent is 1-hexylpyridine trifluoromethanesulfonate.

[0054] It should be noted that 1-hexylpyridine trifluoromethanesulfonate is an ionic liquid with the chemical formula C1. 12 H 18 F3NO3S is composed of a 1-hexylpyridine cation and a trifluoromethanesulfonic acid anion. Its structural feature is that a hexyl chain (C6H) is attached to the 1-position of the pyridine ring. 13 ), trifluoromethanesulfonate (CF3SO3) - This compound offers high thermal stability and low coordination ability, and features a low melting point (<0°C), a wide electrochemical window (approximately 4.5 V), and hydrophobicity.

[0055] In a preferred embodiment, the composite wetting agent comprises sodium alkylnaphthalene sulfonate and o-aminoanisole-4-sulfonic acid, and the mass concentration ratio of sodium alkylnaphthalene sulfonate to o-aminoanisole-4-sulfonic acid is 1:1.

[0056] It should be noted that sodium alkylnaphthalene sulfonate is an anionic surfactant with the general chemical formula C2. 10 H7(SO3Na)(R) n Where R is C8-C 18 The compound is an alkyl group, characterized by the simultaneous attachment of a sulfonic acid group (-SO3Na) and a long-chain alkyl group to a naphthalene ring. This compound possesses both a hydrophilic sulfonate group and a hydrophobic alkylnaphthalene structure, and its critical micelle concentration (CMC) is approximately 10. -3 mol / L can significantly reduce the surface tension of water to 30-40 mN / m (25℃).

[0057] In addition, o-aminoanisole-4-sulfonic acid is an aromatic sulfonic acid organic compound with the chemical formula C7H9NO4S. Its structural feature is that three substituents, methoxy (-OCH3), amino (-NH2) and para-sulfonic acid (-SO3H), are present on the benzene ring. The sulfonic acid group in its molecule provides strong water solubility (solubility at 25℃ >200g / L).

[0058] like Figure 1 As shown, according to another aspect of the present invention, a method for preparing a post-immersion cleaning solution for a phosphoric acid-based electroless nickel plating process is provided. The method for preparing the post-immersion cleaning solution for a phosphoric acid-based electroless nickel plating process includes the following steps:

[0059] S1. Dissolve the solubilizer and phosphoric acid in a predetermined volume of deionized water according to the mass ratio, then heat and stir until completely dissolved to obtain solution A;

[0060] S2. Dissolve the complexing agent, dissociating agent, and composite wetting agent in a predetermined volume of deionized water according to the mass ratio to obtain solution B;

[0061] S3. Mix solution A and solution B to obtain solution C, and then add deionized water to the predetermined final volume;

[0062] S4. When using the solution, first check for any precipitate, and then clean it by spraying.

[0063] As a preferred embodiment, the heating temperature during the preparation of solution A is 45-55°C, and the magnetic stirring speed is 300-500 rpm.

[0064] During use, the spray temperature should be 30-40℃, and the spray pressure should be 1.0-2.0 kg / cm². 2 .

[0065] In a preferred embodiment, during the preparation process, the pH of the solution is controlled between 0.5 and 1.5, and the operating temperature is 35-45°C. If the pH is too low, it is adjusted with 5% sodium hydroxide solution, and if the pH is too high, it is adjusted with 10% phosphoric acid.

[0066] In a preferred embodiment, the step of checking whether there is any precipitation in the solution is to first measure whether the pH is normal.

[0067] If the pH is abnormal, adjust the pH to the normal range and then observe whether the precipitate dissolves. If precipitate still forms even when the pH is normal, the solution in the preparation tank needs to be replaced.

[0068] It should be explained that, when preparing in 1L increments: first, dissolve the solubilizer and phosphoric acid in approximately 200ml of deionized water according to the above mass ratio, and heat and stir until completely dissolved to obtain solution A; then, dissolve the complexing agent, dissociating agent, and composite wetting agent in 200ml of deionized water according to the above mass ratio for 1L to obtain solution B; finally, combine solution A and solution B to obtain solution C, and then add deionized water to a final volume of 1L. Example 1

[0069] A post-immersion cleaning solution for a phosphoric acid-based electroless nickel plating process, comprising the following raw materials at the following mass concentrations:

[0070] Phosphoric acid 45 ml / L;

[0071] 5-Amino-2-pyrazinic acid 1 g / L;

[0072] 1,5-Dimethyl-1H-imidazol-4-carboxylic acid 350 mg / L;

[0073] Glycerol α,α'-diallyl ether 6 g / L;

[0074] 1-Hexylpyridine trifluoromethanesulfonate 300 mg / L;

[0075] Sodium alkylnaphthalene sulfonate 150 mg / L;

[0076] o-Aminoanisole-4-sulfonic acid 150 mg / L;

[0077] The remainder is deionized water.

[0078] As a preferred embodiment, the pH is 1 and the operating temperature is 40°C. Example 2

[0079] A post-immersion cleaning solution for a phosphoric acid-based electroless nickel plating process, comprising the following raw materials at the following mass concentrations:

[0080] Phosphoric acid 30 ml / L;

[0081] 5-Amino-2-pyrazinic acid 0.1 g / L;

[0082] 1,5-Dimethyl-1H-imidazol-4-carboxylic acid 200 mg / L;

[0083] Glycerol α,α'-diallyl ether 3 g / L;

[0084] 1-Hexylpyridine trifluoromethanesulfonate 200 mg / L;

[0085] Sodium alkylnaphthalene sulfonate 100 mg / L;

[0086] o-Aminoanisole-4-sulfonic acid 100 mg / L;

[0087] The remainder is deionized water.

[0088] As a preferred embodiment, the pH is 0.5 and the operating temperature is 35°C. Example 3

[0089] A post-immersion cleaning solution for a phosphoric acid-based electroless nickel plating process, comprising the following raw materials at the following mass concentrations:

[0090] Phosphoric acid 60 ml / L;

[0091] 5-Amino-2-pyrazinic acid 1.5 g / L;

[0092] 1,5-Dimethyl-1H-imidazol-4-carboxylic acid 500 mg / L;

[0093] Glycerol α,α'-diallyl ether 8 g / L;

[0094] 1-Hexylpyridine trifluoromethanesulfonate 400 mg / L;

[0095] Sodium alkylnaphthalene sulfonate 200 mg / L;

[0096] o-Aminoanisole-4-sulfonic acid 200 mg / L;

[0097] The remainder is deionized water.

[0098] As a preferred embodiment, the pH is 1.5 and the operating temperature is 45°C.

[0099] Comparative Example 1

[0100] A post-immersion cleaning solution for a phosphoric acid-based electroless nickel plating process, comprising the following raw materials at the following mass concentrations:

[0101] Phosphoric acid 45 ml / L;

[0102] 5-Amino-2-pyrazinic acid 1 g / L;

[0103] Glycerol α,α'-diallyl ether 6 g / L;

[0104] 1-Hexylpyridine trifluoromethanesulfonate 300 mg / L;

[0105] Sodium alkylnaphthalene sulfonate 150 mg / L;

[0106] o-Aminoanisole-4-sulfonic acid 150 mg / L;

[0107] The remainder is deionized water.

[0108] As a preferred embodiment, the pH is 1 and the operating temperature is 40°C.

[0109] Comparative Example 2

[0110] A post-immersion cleaning solution for a phosphoric acid-based electroless nickel plating process, comprising the following raw materials at the following mass concentrations:

[0111] Phosphoric acid 45 ml / L;

[0112] 5-Amino-2-pyrazinic acid 1 g / L;

[0113] 1,5-Dimethyl-1H-imidazol-4-carboxylic acid 350 mg / L;

[0114] 1-Hexylpyridine trifluoromethanesulfonate 300 mg / L;

[0115] Sodium alkylnaphthalene sulfonate 150 mg / L;

[0116] o-Aminoanisole-4-sulfonic acid 150 mg / L;

[0117] The remainder is deionized water.

[0118] As a preferred embodiment, the pH is 1 and the operating temperature is 40°C.

[0119] Comparative Example 3

[0120] A post-immersion cleaning solution for a phosphoric acid-based electroless nickel plating process, comprising the following raw materials at the following mass concentrations:

[0121] Phosphoric acid 45 ml / L;

[0122] 5-Amino-2-pyrazinic acid 1 g / L;

[0123] 1,5-Dimethyl-1H-imidazol-4-carboxylic acid 350 mg / L;

[0124] Glycerol α,α'-diallyl ether 6 g / L;

[0125] Sodium alkylnaphthalene sulfonate 150 mg / L;

[0126] o-Aminoanisole-4-sulfonic acid 150 mg / L;

[0127] The remainder is deionized water.

[0128] As a preferred embodiment, the pH is 1 and the operating temperature is 40°C.

[0129] Comparative Example 4

[0130] Phosphoric acid 45 ml / L;

[0131] 5-Amino-2-pyrazinic acid 1 g / L;

[0132] 1,5-Dimethyl-1H-imidazol-4-carboxylic acid 350 mg / L;

[0133] Glycerol α,α'-diallyl ether 6 g / L;

[0134] 1-Hexylpyridine trifluoromethanesulfonate 300 mg / L;

[0135] The remainder is deionized water.

[0136] As a preferred embodiment, the pH is 1 and the operating temperature is 40°C.

[0137] Test case

[0138] The performance of the phosphate-based electroless nickel plating post-immersion cleaning solutions prepared by the above-described embodiments and comparative examples using the same method was tested. The test results are shown in Table 1 below.

[0139]

[0140] The evaluation criteria for the experimental tests are as follows:

[0141] 1. A linewidth of 1.2 mil with no plating penetration is considered excellent; a plating penetration rate greater than 0 and less than or equal to 5% is considered good; a rate greater than 5% and less than or equal to 15% is considered poor; and a rate greater than 15% is considered very poor.

[0142] 2. A 2mil linewidth with no plating defects is considered excellent; a plating defect rate greater than 0 and less than or equal to 5% is considered good; a rate greater than 5% and less than or equal to 15% is considered poor; and a rate greater than 15% is considered very poor.

[0143] 3. Criteria for judging the initial nickel plating: Excellent is when there are no abnormalities in nickel plating with a 2mil linewidth; Good is when the rate of poor initial plating is greater than 0 and less than or equal to 5%; Poor is when the rate is greater than 5% and less than or equal to 15%; and Very Poor is when the rate is greater than 15%.

[0144] The results above show that the experimental results of Example 1 are as follows: the plating penetration index is excellent, the plating leakage index is excellent, and the nickel plating start index is excellent; the experimental results of Example 2 are as follows: the plating penetration index is excellent, the plating leakage index is excellent, and the nickel plating start index is excellent; the experimental results of Example 3 are as follows: the plating penetration index is excellent, the plating leakage index is excellent, and the nickel plating start index is excellent.

[0145] Among them, Comparative Example 1 lacked an accelerator compared to Example 1, and the experimental results were: poor infiltration phenomenon index, excellent infiltration phenomenon index, and excellent in nickel plating initiation index; Comparative Example 2 lacked a solubilizer compared to Example 1, and the experimental results were: good infiltration phenomenon index, good infiltration phenomenon index, and good in nickel plating initiation index; Comparative Example 3 lacked a dissociating agent compared to Example 1, and the experimental results were: poor infiltration phenomenon index, excellent infiltration phenomenon index, and excellent in nickel plating initiation index; Comparative Example 4 lacked a composite wetting agent compared to Example 1, and the experimental results were: good infiltration phenomenon index, good infiltration phenomenon index, and excellent in nickel plating initiation index.

[0146] In summary, by utilizing the above-mentioned technical solutions of this invention, the accelerator used in this invention is an alkylimidazolium carboxylic acid compound. Compared with the traditionally used aminothiazole compounds, this accelerator is more efficient. For activation times exceeding twice the normal usage time, this accelerator can promote the dissociation of the dissociating agent within a specified time. The accelerator attacks the active sites of palladium ions. When palladium ions leave the active sites, they are rapidly detached from the substrate surface under the strong electronegativity of the dissociating agent. The dissociating agent in this invention is an alkylpyridine heterocyclic polyfluorosulfonate compound, which has high electronegativity and excellent comprehensive effects on various activated ions such as palladium and ruthenium ions. The solubilizer in this invention can promote the dissolution of the accelerator, and the accelerator also has an offensive effect on the active sites of impurity ions adsorbed on the substrate surface. When the dissociating agent combines with these sites, the solubilizer also promotes their detachment from the substrate surface. The composite wetting agent in this invention can improve the dispersibility of the accelerator and dissociating agent, enhance uniform dispersion, and simultaneously inhibit the re-adsorption of ruthenium ions, palladium ions, and introduced impurity metal ions onto the substrate surface.

[0147] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A post-immersion cleaning solution for a phosphoric acid-based electroless nickel plating process, characterized in that, The post-immersion cleaning solution comprises the following raw materials in parts by weight: 30-60 parts of phosphoric acid; Complexing agent 0.1-1.5 parts; Accelerator 0.2-0.5 parts; 3-8 parts of solubilizer; Dissociation agent 0.2-0.4 parts; 0.2-0.4 parts of compound wetting agent; 929.2-966.3 parts of deionized water; The complexing agent is 5-amino-2-pyrazine carboxylic acid; The accelerator is 1,5-dimethyl-1H-imidazol-4-carboxylic acid; The solubilizer is glycerol α,α'-diallyl ether; The dissociation agent is 1-hexylpyridine trifluoromethanesulfonate; The composite wetting agent comprises sodium alkylnaphthalene sulfonate and o-aminoanisole-4-sulfonic acid, and the mass concentration ratio of sodium alkylnaphthalene sulfonate to o-aminoanisole-4-sulfonic acid is 1:

1.

2. A method for preparing a post-immersion cleaning solution for a phosphoric acid-based electroless nickel plating process, used to prepare the post-immersion cleaning solution for a phosphoric acid-based electroless nickel plating process as described in claim 1, characterized in that, The preparation method of the post-immersion cleaning solution for the phosphoric acid-based electroless nickel plating process includes the following steps: S1. Dissolve the solubilizer and phosphoric acid in a predetermined volume of deionized water according to the mass ratio, then heat and stir until completely dissolved to obtain solution A; S2. Dissolve the complexing agent, dissociating agent, and composite wetting agent in a predetermined volume of deionized water according to the mass ratio to obtain solution B; S3. Mix solution A and solution B to obtain solution C, and then add deionized water to the predetermined final volume; S4. When using the solution, first check for any precipitate, and then clean it by spraying.

3. The method for preparing a post-immersion cleaning solution for a phosphoric acid-based electroless nickel plating process according to claim 2, characterized in that, The heating temperature during the preparation of solution A is 45-55℃, and the magnetic stirring speed is 300-500 rpm. During use, the spray temperature should be 30-40℃, and the spray pressure should be 1.0-2.0 kg / cm². 2 .

4. The method for preparing a post-immersion cleaning solution for a phosphoric acid-based electroless nickel plating process according to claim 2, characterized in that, During the preparation process, the pH of the solution is controlled between 0.5 and 1.5, and the operating temperature is 35-45℃. If the pH is too low, it is adjusted with 5% sodium hydroxide solution, and if the pH is too high, it is adjusted with 10% phosphoric acid.

5. The method for preparing a post-immersion cleaning solution for a phosphoric acid-based electroless nickel plating process according to claim 2, characterized in that, The test solution is checked for any precipitation. If precipitation occurs, the pH is first measured to ensure it is within normal limits. If the pH is abnormal, adjust the pH to the normal range and then observe whether the precipitate dissolves. If precipitate still forms even when the pH is normal, the solution in the preparation tank needs to be replaced.

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