Highly uniform and ultra-thin electroless nickel plating solution and method for plating nickel

Abstract

The embodiment of the present application discloses a kind of high uniformity ultra-thin electroless nickel plating solution and its nickel plating method, the electroless nickel plating solution includes the following mass concentration component: nickel salt 10-20g / L, main complexing agent 10-20g / L, auxiliary complexing agent 5-10g / L, reducing agent 10-15g / L, stabilizer 0.01-0.05g / L, accelerator 0.05-0.1g / L, stress reliever 0.4-0.8g / L, uniform plating agent 0.1-0.5g / L.The present application can realize the high uniformity of excellent carrier plate chemical nickel palladium gold process, low porosity and low stress, and has excellent stability, bright and uniform, good binding force and other characteristics, suitable for substrate ultra-thin chemical nickel product.

Description

Technical Field

[0001] This invention relates to the field of electroless nickel plating technology, and in particular to a high-uniformity ultra-thin electroless nickel plating solution and its nickel plating method. Background Technology

[0002] As high-end IC packaging substrates evolve towards more refined circuitry, denser microvias, and ultra-thin plating layers, traditional electroless nickel plating solutions for nickel-palladium-gold processes are struggling to meet the demands of high-precision manufacturing. Existing conventional electroless nickel plating solutions often employ common organic acid complexation and inorganic salt stabilization systems, resulting in poor component compatibility. This leads to issues such as weak controllability of ion dissociation in the plating solution, significant differences in deposition rates between the substrate surface and microvias, and defects in ultra-thin nickel layers, including thicker plating at edges and corners, thinner plating at hole walls, and poor overall thickness uniformity.

[0003] Meanwhile, traditional plating solutions suffer from poor initial plating consistency, easily leading to delayed plating and micro-plating defects in delicate circuit areas. Furthermore, the plating layer exhibits loose grain structure, making it prone to pinholes and microscopic defects, resulting in poor adhesion of the subsequent palladium layer, color differences in the plating layer, and decreased packaging reliability. Conventional commercial plating solutions generally suffer from a technical bottleneck where stability and uniform plating are mutually exclusive, making them unsuitable for the precise deposition of ultra-thin, dense nickel layers ranging from 0.05 to 0.2 μm.

[0004] To address the shortcomings of the existing technologies, this invention proposes a high-uniformity ultra-thin electroless nickel plating solution. It employs a proprietary complexing, stabilizing, targeted plating initiation, and interface wetting compound system, which can significantly reduce the deposition differences between high and low regions of the substrate, improve the density and thickness uniformity of the coating, and meet the mass production requirements of high-end substrate nickel-palladium-gold precision processes. Summary of the Invention

[0005] The technical problem to be solved by the embodiments of the present invention is to provide a high-uniformity ultra-thin electroless nickel plating solution and a nickel plating method thereof, so as to achieve high uniformity, low porosity and low stress in the excellent substrate electroless nickel palladium gold process, and have excellent stability, bright and uniform, good adhesion and other characteristics, which are suitable for products such as ultra-thin electroless nickel substrates.

[0006] To address the aforementioned technical problems, this invention provides a high-uniformity ultra-thin electroless nickel plating solution, comprising the following components by mass concentration: nickel salt 10-20 g / L, main complexing agent 10-20 g / L, auxiliary complexing agent 5-10 g / L, reducing agent 10-15 g / L, stabilizer 0.01-0.05 g / L, accelerator 0.05-0.1 g / L, stress reliever 0.4-0.8 g / L, and leveling agent 0.1-0.5 g / L.

[0007] Furthermore, the primary complexing agent is lactic acid; the secondary complexing agent is 2,3-diaminopyridine.

[0008] Furthermore, the reducing agent is sodium hypophosphite; the nickel salt is nickel sulfate.

[0009] Furthermore, the accelerator is 8-amino-1,2,4-triazolo[4,3-a]pyrazine.

[0010] Furthermore, the stress reliever is 3-(cyclohexylamine)-2-hydroxy-1-propanesulfonic acid.

[0011] Furthermore, the stabilizer is imidazole[2,1-B]thiazol-6-methanol.

[0012] Furthermore, the plating agent is propargyl α-D-mannopyranoside.

[0013] Accordingly, embodiments of the present invention also provide a method for nickel plating using a high-uniformity, ultra-thin electroless nickel plating solution, comprising: Step 1: Use an alkaline degreasing solution to perform alkaline low-foaming precision degreasing on the nickel-plated workpiece; Step 2: Neutralize the residual alkaline degreasing solution with a dilute weak acid neutralization solution, and rinse thoroughly with pure water. Step 3: Perform micro-etching using a sodium persulfate / dilute sulfuric acid system; Step 4: Perform plasma interface lubrication pretreatment, followed by light plasma treatment with ambient pressure air. Step 5: Activate using colloidal palladium activating solution; Step 6: Preheat the plating solution and buffer the immersion process; Step 7: Perform electroless nickel plating in stages with controlled temperature.

[0014] Further, in step 1, the alkaline degreasing solution comprises the following components by mass concentration: sodium hydroxide 6-8 g / L, sodium metasilicate pentahydrate 10-14 g / L, diethanolamine 5-7 g / L, C12-C14 fatty alcohol polyoxyethylene polyoxypropylene ether 2.8-4.2 g / L, isotridecyl alcohol polyoxyethylene ether 1.2-2.0 g / L, aminotrimethylenephosphonic acid 1.5-2.8 g / L, sodium polyacrylate 1.0-2.2 g / L, with the remainder being deionized water.

[0015] Further, in step 5, the colloidal palladium activation solution comprises the following components by mass concentration: palladium chloride 0.25-0.4 g / L, tin dichloride 20-28 g / L, trisodium citrate 4-6 g / L, sodium gluconate 2.5-4 g / L, 2-methylimidazole 0.3-0.6 g / L, anhydrous ethanol 1.5-3 g / L, hydrochloric acid (37%) 18-25 g / L, with the remainder being deionized water.

[0016] The beneficial effects of this invention are as follows: 1) The accelerator 8-amino-1,2,4-triazolo[4,3-a]pyrazine of the present invention has a fused nitrogen heterocyclic structure, which can provide catalytic active sites, reduce the activation energy of the reduction reaction, and efficiently improve the deposition rate. The molecule selectively adsorbs onto the substrate surface, does not initiate nickel deposition in the plating bath, is suitable for ultra-thin plating, and has good thermal stability and strong compatibility with the system.

[0017] 2) This invention uses propargyl α-D-mannopyranoside as a leveling agent, which combines the hydrophilic groups of the glycoside with the hydrophobic structure of the alkyne group, thus rapidly reducing the surface tension of the plating solution. It can fully wet the micropores and fine lines of the carrier plate, eliminating defects such as missed plating and pitting caused by bubble adhesion. It can uniformly spread the plating solution components, improving the overall deposition consistency, and is suitable for the preparation of ultra-thin coatings, while not compromising the stability of the plating solution system, effectively optimizing the appearance of the coating and the overall uniform plating effect.

[0018] 3) This invention uses 2,3-diaminopyridine as an auxiliary complexing agent. Utilizing the dual-coordination structure of the pyridine ring and the ortho-amino group, it can stably and slowly release nickel ions, effectively improving the uniformity of the coating thickness on the plate surface and in the microporous area, making it suitable for ultra-thin nickel layer deposition. The conjugated molecular structure enhances the stability of the plating solution and reduces self-decomposition defects. Simultaneously, it can refine the coating grains, reduce internal stress, optimize the surface activity of the nickel layer, and facilitate the adhesion and bonding of the subsequent palladium layer. Compared with traditional complexing agents, the plating performance and process compatibility are significantly improved. 5,6-imidazolium[2,1-B]thiazol-6-methanol is selected as a stabilizer. Relying on the indole cyclic conjugated molecular structure, it can efficiently adsorb onto the active sites of the plating solution, inhibiting spontaneous decomposition of the nickel solution. It can regulate the nickel deposition rate, improve the uniformity of the ultra-thin coating, and effectively reduce pinholes and roughness defects. Simultaneously, it can optimize the micro-grain morphology of the coating, reduce internal stress, improve the surface condition of the nickel layer, and has excellent compatibility with the subsequent palladium layer, significantly improving the overall adhesion and process stability of the coating.

[0019] 4) This invention employs a series of refined pretreatment processes, from degreasing and micro-etching to plasma activation, to progressively optimize the surface condition of the substrate, combined with graded pre-activation and gradient temperature-controlled plating. This effectively improves the uniformity of nickel layer nucleation, significantly enhances the consistency of ultra-thin plating, reduces defects, and strengthens plating adhesion, making it suitable for the precision nickel-palladium-gold plating production needs of substrates. Detailed Implementation

[0020] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will be further described in detail below with reference to specific embodiments.

[0021] The high-uniformity ultra-thin electroless nickel plating solution of this invention comprises the following components by mass concentration: nickel salt 10-20 g / L, main complexing agent 10-20 g / L, auxiliary complexing agent 5-10 g / L, reducing agent 10-15 g / L, stabilizer 0.01-0.05 g / L, accelerator 0.05-0.1 g / L, stress reliever 0.4-0.8 g / L, and leveling agent 0.1-0.5 g / L. The pH is 4.8-5.4; the temperature is controlled at 58-64℃.

[0022] The primary complexing agent is lactic acid; the secondary complexing agent is 2,3-diaminopyridine. This invention uses 2,3-diaminopyridine as the secondary complexing agent. Due to its dual-coordination structure of the pyridine ring and the ortho-amino group, it can stably and slowly release nickel ions, effectively improving the uniformity of the plating thickness on the plate surface and in the microporous region. It is suitable for ultra-thin nickel layer deposition, and its molecular conjugated structure enhances the stability of the plating solution and reduces self-decomposition defects. Simultaneously, it can refine the plating grains, reduce internal stress, optimize the surface activity of the nickel layer, and facilitate the subsequent adhesion and bonding of the palladium layer. Compared with traditional complexing agents, its plating performance and process compatibility are significantly improved.

[0023] The reducing agent is sodium hypophosphite; the nickel salt is nickel sulfate.

[0024] The accelerator is 8-amino-1,2,4-triazolo[4,3-a]pyrazine. 8-amino-1,2,4-triazolo[4,3-a]pyrazine has a fused nitrogen heterocyclic structure, providing catalytically active sites, reducing the activation energy of the reduction reaction, and efficiently increasing the deposition rate. It selectively adsorbs onto the substrate surface, does not initiate nickel deposition in the plating bath, is suitable for ultra-thin plating, and exhibits good thermal stability and strong compatibility with the system.

[0025] The stress reliever is 3-(cyclohexylamine)-2-hydroxy-1-propanesulfonic acid. This stress reliever possesses multiple functional groups, including amine, hydroxyl, and sulfonic acid groups. It exhibits mild interfacial adsorption, can moderate grain growth stress, effectively reduce internal stress in ultrathin coatings, has good compatibility with plating solution components, does not affect plating rate or solution stability, optimizes coating microstructure, reduces microcracks and peeling, and is suitable for precision ultrathin electroless nickel plating processes.

[0026] The stabilizer is imidazole[2,1-B]-thiazol-6-methanol. This invention selects imidazole[2,1-B]-thiazol-6-methanol as the stabilizer. This substance has a fused heterocyclic structure, possessing both imidazole and thiazol bicyclic characteristics. It has strong coordination adsorption capacity, and can effectively passivate free nickel nuclei with low dosage, inhibiting plating solution decomposition, reducing nickel precipitation on the tank wall, exhibiting good thermal stability, stable activity under high-temperature conditions, minimal impact on deposition rate, and also refining the coating grains.

[0027] The plating leveling agent is propargyl α-D-mannopyranoside. This invention uses propargyl α-D-mannopyranoside as a leveling agent, which combines the hydrophilic groups of the glycoside with the hydrophobic structure of the alkyne group, rapidly reducing the surface tension of the plating solution. It can fully wet the micropores and fine lines of the carrier plate, eliminating defects such as missed plating and pitting caused by bubble adhesion. It can uniformly spread the plating solution components, improving the overall deposition consistency, adapting to the preparation of ultra-thin coatings, while not compromising the stability of the plating solution system, effectively optimizing the appearance of the coating and the overall plating uniformity.

[0028] This invention is the first to apply propargyl organic compounds (such as propargyl alcohol and sodium propargyl sulfonate) as leveling agents in electroless plating solutions, exhibiting selective inhibition of deposition in corner areas and acceptable deposition in groove areas. This invention discovers that in electroless plating systems without an external electric field, propargyl structures can selectively adsorb onto highly active areas (such as corners and sharp protrusions) on the workpiece surface. By locally inhibiting the autocatalytic reaction rate, it effectively reduces the deposition rate differences between different geometric locations, thereby significantly improving the uniformity of the coating thickness without compromising key properties such as internal stress and corrosion resistance.

[0029] The nickel plating method of the high-uniformity ultra-thin electroless nickel plating solution in this embodiment of the invention includes steps 1 to 7.

[0030] Step 1: Use an alkaline degreasing solution to perform alkaline low-foaming precision degreasing on the nickel-plated workpiece to remove grease, fingerprints, dust, and other organic contaminants from the workpiece surface. Temperature 45-50℃, time 4-6 minutes, overflow water rinse twice, 30 seconds each time, to ensure no chemical solution is carried over.

[0031] In step 1, the alkaline degreasing solution comprises the following components by mass concentration: sodium hydroxide 6-8 g / L, sodium metasilicate pentahydrate 10-14 g / L, diethanolamine 5-7 g / L, C12-C14 fatty alcohol polyoxyethylene polyoxypropylene ether 2.8-4.2 g / L, isotridecyl alcohol polyoxyethylene ether 1.2-2.0 g / L, aminotrimethylenephosphonic acid 1.5-2.8 g / L, sodium polyacrylate 1.0-2.2 g / L, with the remainder to be replenished with deionized water.

[0032] Step 2: Neutralize the residual alkaline degreasing solution with a dilute weak acid neutralization solution at room temperature for 2 minutes, and then rinse thoroughly with pure water.

[0033] Step 3: Low-damage gradient controllable micro-etching, micro-etching is carried out using a persulfate / dilute sulfuric acid system; temperature 28-32℃, etching rate controlled at 0.2-0.4μm / min, time 60-90s, followed by three-stage pure water rinsing.

[0034] Step 4: Perform plasma interface lubrication pretreatment, light plasma treatment with normal pressure air; power 150W, time 40-60s.

[0035] Step 5: Perform fractional micro-colloidal palladium pre-activation using colloidal palladium activation solution at room temperature for 90-120 seconds, followed by a gentle rinse with pure water for 60 seconds.

[0036] In step 5, the colloidal palladium activation solution comprises the following components by mass concentration: palladium chloride 0.25-0.4 g / L, tin dichloride 20-28 g / L, trisodium citrate 4-6 g / L, sodium gluconate 2.5-4 g / L, 2-methylimidazole 0.3-0.6 g / L, anhydrous ethanol 1.5-3 g / L, hydrochloric acid (37%) 18-25 g / L, with the remainder being deionized water.

[0037] Step 6: Preheat the plating solution and buffer the immersion; immerse the carrier plate in a 70℃ preheated pure water bath for 60 seconds.

[0038] Step 7: Gradient constant temperature dynamic electroless nickel plating, with segmented temperature control. Initially, heat to 65-67℃ for 3-5 minutes to enhance plating, then cool to the controlled temperature, with low-speed horizontal slight oscillation and no violent vibration.

[0039] This invention employs a series of refined pretreatment processes, progressively optimizing the substrate surface condition from degreasing and micro-etching to plasma activation, combined with graded pre-activation and gradient temperature-controlled plating. This effectively improves the uniformity of nickel layer nucleation, significantly enhances the consistency of ultra-thin plating, reduces defects, and strengthens plating adhesion, making it suitable for the precision nickel-palladium-gold plating production needs of substrates.

[0040] Example 1:

[0041] The electroless nickel plating solution of this invention comprises: nickel sulfate 15 g / L, lactic acid 15 g / L, 2,3-diaminopyridine 7.5 g / L, sodium hypophosphite 13 g / L, imidazole[2,1-B]thiazolyl-6-methanol 0.03 g / L, 8-amino-1,2,4-triazolo[4,3-a]pyrazine 0.075 g / L, 3-(cyclohexylamine)-2-hydroxy-1-propanesulfonic acid 0.6 g / L, and propargyl α-D-mannopyranoside 0.3 g / L.

[0042] The pH was 5.1; the initial temperature was raised to 66℃ for 1 minute, and then the temperature was lowered to the controlled temperature of 61℃ for 10 minutes.

[0043] The test results of Example 1 are as follows: stress test is excellent; appearance is excellent; stability is excellent; porosity is excellent; rate is excellent; P content is 10.5%.

[0044] Example 2:

[0045] The electroless nickel plating solution of this invention comprises: nickel sulfate 12 g / L, lactic acid 10 g / L, 2,3-diaminopyridine 5 g / L, sodium hypophosphite 10 g / L, imidazole[2,1-B]thiazolyl-6-methanol 0.05 g / L, 8-amino-1,2,4-triazolo[4,3-a]pyrazine 0.075 g / L, 3-(cyclohexylamine)-2-hydroxy-1-propanesulfonic acid 0.6 g / L, and propargyl α-D-mannopyranoside 0.3 g / L.

[0046] The pH was 5.1; the initial temperature was raised to 66℃ for 1 minute, and then the temperature was lowered to the controlled temperature of 61℃ for 10 minutes.

[0047] The test results for Example 2 are as follows: stress test is excellent; appearance is excellent; stability is excellent; porosity is excellent; rate is excellent; P content is 10.7%.

[0048] Example 3:

[0049] The electroless nickel plating solution of this invention comprises: nickel sulfate 20 g / L, lactic acid 20 g / L, 2,3-diaminopyridine 5 g / L, sodium hypophosphite 15 g / L, imidazole[2,1-B]thiazolyl-6-methanol 0.01 g / L, 8-amino-1,2,4-triazolo[4,3-a]pyrazine 0.05 g / L, 3-(cyclohexylamine)-2-hydroxy-1-propanesulfonic acid 0.8 g / L, and propargyl α-D-mannopyranoside 0.1 g / L.

[0050] The pH was 5.1; the initial temperature was raised to 66℃ for 1 minute, and then the temperature was lowered to the controlled temperature of 61℃ for 10 minutes.

[0051] The test results for Example 3 are as follows: stress test is excellent; appearance is excellent; stability is excellent; porosity is excellent; rate is excellent; P content is 10.3%.

[0052] Comparative Example 1: The electroless nickel plating solution of Comparative Example 1 includes: nickel sulfate 15 g / L, lactic acid 15 g / L, sodium hypophosphite 13 g / L, imidazole[2,1-B]-thiazolyl-6-methanol 0.03 g / L, 8-amino-1,2,4-triazolo[4,3-a]pyrazine 0.075 g / L, 3-(cyclohexylamine)-2-hydroxy-1-propanesulfonic acid 0.6 g / L, and propargyl α-D-mannopyranoside 0.3 g / L.

[0053] The pH was 5.1; the initial temperature was raised to 66℃ for 1 minute, and then the temperature was lowered to the controlled temperature of 61℃ for 10 minutes.

[0054] Compared with Example 1, Comparative Example 1 lacked an auxiliary complexing agent. The test results were as follows: stress test was good; appearance was good; stability was good; porosity was good; rate was excellent; and P content was 11.2%.

[0055] Comparative Example 2: The electroless nickel plating solution of Comparative Example 2 included: nickel sulfate 15 g / L, lactic acid 15 g / L, 2,3-diaminopyridine 7.5 g / L, sodium hypophosphite 13 g / L, 8-amino-1,2,4-triazolo[4,3-a]pyrazine 0.075 g / L, 3-(cyclohexylamine)-2-hydroxy-1-propanesulfonic acid 0.6 g / L, and propargyl α-D-mannopyranoside 0.3 g / L; The pH was 5.1; the initial temperature was raised to 66℃ for 1 minute, and then the temperature was lowered to the controlled temperature of 61℃ for 10 minutes.

[0056] Compared with Example 1, Comparative Example 2 lacked a stabilizer, and the test results obtained were as follows: stress test was good; appearance was good; stability was good; porosity was good; rate was excellent; and P content was 11.3%.

[0057] Comparative Example 3: The electroless nickel plating solution of Comparative Example 3 included: nickel sulfate 15 g / L, lactic acid 15 g / L, 2,3-diaminopyridine 7.5 g / L, sodium hypophosphite 13 g / L, imidazole[2,1-B]thiazolyl-6-methanol 0.03 g / L, 3-(cyclohexylamine)-2-hydroxy-1-propanesulfonic acid 0.6 g / L, and propargyl α-D-mannopyranoside 0.3 g / L; The pH was 5.1; the initial temperature was raised to 66℃ for 1 minute, and then the temperature was lowered to the controlled temperature of 61℃ for 10 minutes.

[0058] Compared with Example 1, Comparative Example 3 lacked an accelerator, and the test results obtained were as follows: stress test was good; appearance was good; stability was excellent; porosity was good; rate was poor; and P content was 7.4%.

[0059] Comparative Example 4: The electroless nickel plating solution of Comparative Example 4 included: nickel sulfate 15 g / L, lactic acid 15 g / L, 2,3-diaminopyridine 7.5 g / L, sodium hypophosphite 13 g / L, imidazole[2,1-β]thiazolyl-6-methanol 0.03 g / L, 8-amino-1,2,4-triazolo[4,3-a]pyrazine 0.075 g / L, and 3-(cyclohexylamine)-2-hydroxy-1-propanesulfonic acid 0.6 g / L; The pH was 5.1; the initial temperature was raised to 66℃ for 1 minute, and then the temperature was lowered to the controlled temperature of 61℃ for 10 minutes.

[0060] Compared with Example 1, Comparative Example 4 lacked a leveling agent, and the test results obtained were as follows: stress test was good; appearance was good; stability was excellent; porosity was good; rate was excellent; and P content was 10.4%.

[0061] Comparative Example 5: The electroless nickel plating solution of Comparative Example 5 included: nickel sulfate 15 g / L, lactic acid 15 g / L, 2,3-diaminopyridine 7.5 g / L, sodium hypophosphite 13 g / L, imidazole[2,1-β]thiazolyl-6-methanol 0.03 g / L, 8-amino-1,2,4-triazolo[4,3-α]pyrazine 0.075 g / L, 3-(cyclohexylamine)-2-hydroxy-1-propanesulfonic acid 0.6 g / L, and propargyl α-D-mannopyranoside 0.3 g / L; The pH was 5.1; the initial temperature was raised to 66℃ for 1 minute, and then the temperature was lowered to the controlled temperature of 61℃ for 10 minutes.

[0062] Compared with Example 1, Comparative Example 5 lacked a stress reliever, and the test results were as follows: poor stress test; good appearance; excellent stability; good porosity; excellent rate; and P content of 10.4%.

[0063] The judgment criteria are shown in Table 1:

[0064] This invention can achieve high uniformity, low porosity, and low stress in the excellent electroless nickel-palladium-gold process for substrates, and has excellent stability, bright and uniform finish, and good adhesion. It is suitable for products such as ultra-thin electroless nickel substrates.

[0065] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A high-uniformity, ultra-thin electroless nickel plating solution, characterized in that, It includes the following components in mass concentration: nickel salt 10-20 g / L, main complexing agent 10-20 g / L, auxiliary complexing agent 5-10 g / L, reducing agent 10-15 g / L, stabilizer 0.01-0.05 g / L, accelerator 0.05-0.1 g / L, stress reliever 0.4-0.8 g / L, and leveling agent 0.1-0.5 g / L.

2. The high-uniformity ultra-thin electroless nickel plating solution as described in claim 1, characterized in that, The primary complexing agent is lactic acid; the secondary complexing agent is 2,3-diaminopyridine.

3. The high-uniformity ultra-thin electroless nickel plating solution as described in claim 1, characterized in that, The reducing agent is sodium hypophosphite; the nickel salt is nickel sulfate.

4. The high-uniformity ultra-thin electroless nickel plating solution as described in claim 1, characterized in that, The accelerator is 8-amino-1,2,4-triazolo[4,3-a]pyrazine.

5. The high-uniformity ultra-thin electroless nickel plating solution as described in claim 1, characterized in that, The stress reliever is 3-(cyclohexylamine)-2-hydroxy-1-propanesulfonic acid.

6. The high-uniformity ultra-thin electroless nickel plating solution as described in claim 1, characterized in that, The stabilizer is imidazole[2,1-B]thiazole-6-methanol.

7. The high-uniformity ultra-thin electroless nickel plating solution as described in claim 1, characterized in that, The plating agent is propargyl α-D-mannopyranoside.

8. A method for nickel plating using a high-uniformity ultra-thin electroless nickel plating solution as described in any one of claims 1 to 7, characterized in that, include: Step 1: Use an alkaline degreasing solution to perform alkaline low-foaming precision degreasing on the nickel-plated workpiece; Step 2: Neutralize the residual alkaline degreasing solution with a dilute weak acid neutralization solution, and rinse thoroughly with pure water. Step 3: Perform micro-etching using a sodium persulfate / dilute sulfuric acid system; Step 4: Perform plasma interface lubrication pretreatment, followed by light plasma treatment with ambient pressure air. Step 5: Activate using colloidal palladium activating solution; Step 6: Preheat the plating solution and buffer the immersion; Step 7: Perform electroless nickel plating in stages with controlled temperature.

9. The nickel plating method using the high-uniformity ultra-thin electroless nickel plating solution as described in claim 8, characterized in that, In step 1, the alkaline degreasing solution comprises the following components by mass concentration: sodium hydroxide 6-8 g / L, sodium metasilicate pentahydrate 10-14 g / L, diethanolamine 5-7 g / L, C12-C14 fatty alcohol polyoxyethylene polyoxypropylene ether 2.8-4.2 g / L, isotridecyl alcohol polyoxyethylene ether 1.2-2.0 g / L, aminotrimethylenephosphonic acid 1.5-2.8 g / L, sodium polyacrylate 1.0-2.2 g / L, with the remainder to be replenished with deionized water.

10. The nickel plating method using the high-uniformity ultra-thin electroless nickel plating solution as described in claim 8, characterized in that, In step 5, the colloidal palladium activation solution comprises the following components by mass concentration: palladium chloride 0.25-0.4 g / L, tin dichloride 20-28 g / L, trisodium citrate 4-6 g / L, sodium gluconate 2.5-4 g / L, 2-methylimidazole 0.3-0.6 g / L, anhydrous ethanol 1.5-3 g / L, hydrochloric acid (37%) 18-25 g / L, with the remainder being deionized water.

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