Nickel-plated steel strip lead wire processing method

Abstract

The application discloses a nickel-plated steel strip lead processing method and belongs to the technical field of metal material surface treatment. The method aims to solve the problems of poor plating layer adhesion, large internal stress and easy peeling of the existing nickel-plated steel strip lead. The process steps include: S1, steel strip oil removal treatment; S2, composite activation treatment: the oil-removed steel strip is immersed in a composite activation solution containing sodium citrate to remove the surface oxide layer and form an active adsorption film; S3, nickel plating: the activated steel strip is immersed in a sulfate plating solution containing saccharin and 1,4-butynediol as composite additives for electroplating to form a low-stress and high-density nickel plating layer; S4, post-treatment: cleaning and drying; S5, slitting and packaging. The application cooperates sodium citrate activation with a plating solution system containing stress relieving agents, significantly improves the adhesion between the substrate and the plating layer, reduces the internal stress of the plating layer, and the obtained product has no peeling and falling of the plating layer after repeated bending, low porosity and excellent comprehensive performance, and is particularly suitable for the manufacturing of high-performance electronic component leads.

Description

Technical Field

[0001] This invention relates to the field of metal material surface treatment technology, specifically to a processing method for nickel-plated steel strip leads, and particularly to a method for preparing nickel-plated steel strip leads by optimizing the plating solution formula and activation process to improve the adhesion of the plating layer. Background Technology

[0002] Nickel-plated steel strip leads are widely used in electronic components, battery connectors, and other fields due to their excellent conductivity and solderability. Existing nickel plating processes for steel strips, such as those described in the application with application number [original rejected application number], typically include degreasing, activation, electroplating, and slitting steps. This process mainly focuses on improving the uniformity of the plating layer through pulse electroplating technology.

[0003] However, in actual production, it has been found that the adhesion between the plating layer and the steel strip substrate is a key factor affecting the final product quality. Insufficient adhesion easily leads to plating peeling and flaking during subsequent slitting, punching, or use. The original process only used simple sulfuric acid activation, which was insufficient for microscopic adjustment of the substrate surface and did not optimize for the internal stress of the plating solution, resulting in high internal stress in the plating layer and affecting long-term reliability. Therefore, there is an urgent need for a nickel-plated steel strip lead processing method that can significantly improve plating adhesion and reduce internal stress in the plating layer. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preparing high-adhesion nickel-plated steel strip leads, so as to solve the problems of insufficient coating adhesion and high internal stress mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides a method for processing nickel-plated steel strip leads, characterized in that a synergistic effect is formed between the surface treatment of the steel strip substrate and the electroplating solution formulation, and the coating adhesion is significantly improved by improving the composition of the activating solution and the nickel plating solution additive system.

[0006] The specific technical solution is as follows: A method for processing nickel-plated steel strip leads includes the following steps: S1. Steel strip degreasing treatment: Select steel strips, use alkaline degreasing agents for chemical degreasing, and then perform electrolytic degreasing. S2. Steel strip composite activation treatment: First, immerse the steel strip in a composite activation solution containing sodium citrate to remove the surface oxide layer and perform pre-complexation; then rinse it clean with water. S3, Electroplated Nickel Layer: The activated steel strip is immersed in a modified nickel sulfate electroplating solution, and nickel ions are deposited using electroplating technology to form a low-stress nickel plating layer. S4. Post-treatment: Clean and dry the nickel-plated steel strip; S5. Cutting and Packaging.

[0007] As a further technical solution of the present invention, the composite activation solution in S2 is composed of sulfuric acid and sodium citrate. By introducing sodium citrate, while removing the oxide layer, citrate ions are adsorbed onto the surface of the steel strip, forming an active layer. The protective film prevents secondary oxidation of the surface after activation, and at the same time provides denser crystal nucleus growth points for subsequent electroplating deposition.

[0008] As a further technical solution of the present invention, the improved nickel sulfate electroplating solution in S3 includes nickel sulfate as the main salt, nickel chloride as the anodic activator, boric acid as the buffer, and saccharin and 1,4-butynediol as composite additives; saccharin, as a primary brightener and stress reliever, can reduce the internal stress of the coating and increase the ductility of the coating, so that it is not easy to chip during cutting; 1,4-butynediol, as a secondary brightener, refines the crystals, making the coating more dense and forming a good lattice match with the substrate surface activated by sodium citrate.

[0009] As a further technical solution of the present invention, the concentrations of each component in the electroplating solution are as follows: nickel sulfate 250-320 g / L, nickel chloride 40-55 g / L, boric acid 35-45 g / L, saccharin 0.5-2.0 g / L, and 1,4-butynediol 0.2-0.6 g / L.

[0010] As a further technical solution of the present invention, the electroplating in S3 adopts DC or pulse electroplating, the current density is controlled at 2-5A / dm², the electroplating temperature is controlled at 50-60℃, and the pH value is controlled at 4.0-4.8.

[0011] As a further technical solution of the present invention, the thickness of the steel strip in S1 is 0.1-0.5mm, and the width is set according to the requirements.

[0012] The present invention has the following beneficial effects: 1. Significantly improves coating adhesion: By introducing sodium citrate in the activation step, the problem of surface passivation or secondary oxidation caused by traditional sulfuric acid activation is solved, so that the substrate surface is in the optimal active state.

[0013] 2. Reduced internal stress in the plating layer: By introducing saccharin as a stress reliever into the plating bath, combined with the leveling effect of 1,4-butynediol, the resulting plating layer exhibits low internal stress and good toughness. Bending tests show that the plating layer does not peel or flake off, making it particularly suitable for lead wire products requiring repeated bending.

[0014] 3. Good process compatibility: The improvements of this invention are mainly focused on the plating solution formulation and activation step. It can significantly improve product quality without large-scale equipment modification of the original production line and is easy to promote in industry. Detailed Implementation

[0015] The technical solutions in the embodiments of the present invention will be clearly and completely described below.

[0016] Example 1 S1. Degreasing treatment: Select a steel strip with a width of 50mm and a thickness of 0.2mm, immerse it in an alkaline degreasing agent at a temperature of 60℃ for 3 minutes, and then perform cathodic electrolysis for 1 minute with a current density of 10A / dm².

[0017] S2. Composite Activation Treatment: Immerse the degreased steel strip in a composite activation solution consisting of 10% sulfuric acid and 30g / L sodium citrate for 2 minutes at room temperature. After removal, rinse thoroughly with deionized water.

[0018] S3. Nickel plating: The steel strip is immersed in an electroplating bath with the following composition: nickel sulfate 280 g / L, nickel chloride 45 g / L, boric acid 40 g / L, saccharin 1.0 g / L, and 1,4-butynediol 0.4 g / L. The plating bath temperature is 55℃, pH value is 4.5, direct current electroplating is used, current density is 3 A / dm², and plating time is 8 minutes to obtain nickel-plated steel strip.

[0019] S4. Post-treatment: Clean and dry after removal from the tank.

[0020] S5. Slitting and Packaging: Slitting the nickel-plated steel strip into 3mm wide lead wires and vacuum packaging them.

[0021] Example 2 This embodiment is basically the same as Embodiment 1, except that: the S2 composite activation solution is composed of 10% sulfuric acid and 20g / L sodium citrate; the S3 plating solution has a saccharin concentration of 1.5g / L and a 1,4-butynediol concentration of 0.3g / L.

[0022] Comparative Example 1 S1. Degreasing treatment: Select a steel strip with a width of 50mm and a thickness of 0.2mm, immerse it in an alkaline degreasing agent at a temperature of 60℃ for 3 minutes, and then perform cathodic electrolysis for 1 minute with a current density of 10A / dm².

[0023] S2. Activation treatment: Immerse the degreased steel strip in 10% sulfuric acid at room temperature for 2 minutes. After removal, rinse thoroughly with deionized water.

[0024] S3. Nickel plating: The steel strip is immersed in an electroplating bath with the following composition: nickel sulfate 280 g / L, nickel chloride 45 g / L, and boric acid 40 g / L. The plating bath temperature is 55℃, pH value is 4.5, direct current electroplating is used, current density is 3 A / dm², and plating time is 8 minutes to obtain nickel-plated steel strip.

[0025] S4. Post-treatment: Clean and dry after removal from the tank.

[0026] S5. Slitting and Packaging: Slitting the nickel-plated steel strip into 3mm wide lead wires and vacuum packaging them.

[0027] Performance testing: The performance of the nickel-plated steel strips obtained in Examples 1-2 and Comparative Example 1 was tested, and the test results are shown in the table below: The test results show that the present invention significantly improves the adhesion and density of the coating by optimizing the formulation of the activation solution and the plating solution, and its overall performance is superior to that of the existing process.

[0028] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for processing nickel-plated steel strip leads, characterized in that, Includes the following steps: S1. Steel strip degreasing treatment: Chemical degreasing and electrolytic degreasing of steel strip; S2. Composite activation treatment: The degreased steel strip is immersed in a composite activation solution containing sodium citrate to remove the surface oxide layer and form an active adsorption film on the surface of the steel strip. S3, Electroplated Nickel Layer: The activated steel strip is used as the cathode and immersed in a sulfate electroplating solution containing saccharin and 1,4-butynediol as composite additives to form a nickel plating layer on the surface of the steel strip. S4. Post-treatment: Clean and dry the nickel-plated steel strip; S5. Slitting and Packaging: Slit the nickel-plated steel strip to the required width and package it.

2. The method for processing nickel-plated steel strip leads according to claim 1, characterized in that, The composite activation solution in S2 contains sulfuric acid and sodium citrate, wherein the mass concentration of sulfuric acid is 5%-15% and the mass concentration of sodium citrate is 20-50 g / L.

3. The method for processing nickel-plated steel strip leads according to claim 1, characterized in that, The sulfate electroplating solution in S3 contains: 250-320 g / L nickel sulfate, 40-55 g / L nickel chloride, 35-45 g / L boric acid, 0.5-2.0 g / L saccharin, and 0.2-0.6 g / L 1,4-butynediol.

4. A method for processing nickel-plated steel strip leads according to claim 1 or 3, characterized in that, The electroplating temperature in S3 is 50-60℃, the current density is 2-5A / dm², and the pH value is controlled between 4.0 and 4.

8.

5. The method for processing nickel-plated steel strip leads according to claim 1, characterized in that, Before the degreasing process, the steel strip in S1 undergoes pickling pretreatment to remove the initial thick oxide scale.

6. The method for processing nickel-plated steel strip leads according to claim 1, characterized in that, The width of the cut in S5 is 2-10mm.

7. A nickel-plated steel strip lead wire, characterized in that, It is prepared by the processing method described in any one of claims 1-6.

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