Production process of nickel-plated phosphor bronze wire

Abstract

The production process comprises the following steps that S1, a copper wire is subjected to acid pickling and water washing in sequence, and a first copper wire is obtained; s2, nickel plating and water washing are conducted on the first copper wire, and a second copper wire is obtained; s3, carrying out pre-tinning treatment on the second copper wire, and washing to obtain the second copper wire; s4, the second copper wire is subjected to tin-cobalt alloy plating treatment and washed, and a third copper wire is obtained; and S5, tinning the third copper wire, and sequentially washing with water and hot water to obtain a nickel-plated phosphor bronze wire finished product. According to the production process of the nickel-plated phosphor bronze wire, the tin-cobalt alloy step is arranged between nickel plating and tin plating, a compact tin-cobalt alloy layer is introduced between a nickel plating layer and a tin plating layer, and the mechanical property of the nickel-plated phosphor bronze wire and the bonding firmness of a phosphor bronze surface plating layer are improved while the weldability and the oxidation weldability of the surface nickel layer are maintained.

Description

Technical Field

[0001] The invention relates to the technical field of wire electroplating, and in particular to a production process of a nickel-plated phosphor bronze wire. Background Art

[0002] Nickel-plated phosphor bronze wire is widely used as a conductor in the fields of electronic devices, motors, and instruments. The basic structure of nickel-plated phosphor bronze wire is: copper wire core material, nickel-plated layer and tin-plated layer plated on the copper wire surface in sequence.

[0003] The nickel plating layer acts as a barrier layer and intermediate plating layer between the copper wire substrate and tin, blocking the reaction between copper and tin to form an interface metal alloy and improving the bonding strength of the tin plating layer. The tin plating layer provides the copper wire with good solderability, corrosion resistance, wear resistance and appearance. In practical applications, such as when used for motor lead wires and electric heating cables, nickel-plated phosphor bronze wires must have higher mechanical strength to meet the tension and bending during use. In addition, further reducing circuit resistance, improving conductivity and circuit working efficiency is also one of the main directions for optimizing nickel-plated phosphor bronze wire products. Summary of the invention

[0004] The purpose of the present invention is to overcome the defects in the prior art, provide a production process for nickel-plated phosphor bronze wire, and further improve the mechanical properties of the nickel-plated phosphor bronze wire and the bonding firmness of the phosphor bronze surface coating.

[0005] To achieve the above technical effects, the technical solution of the present invention is: a production process of nickel-plated phosphor bronze wire, comprising the following steps:

[0006] S1: The copper wire is degreased, pickled, and washed in turn to obtain the first copper wire;

[0007] S2: nickel-plating the first copper wire, and washing with water to obtain a second copper wire;

[0008] S3: The second copper wire is plated with tin-cobalt alloy and then washed to obtain the third copper wire;

[0009] S4: The third copper wire is tinned, and then washed with water and hot water to obtain a finished nickel-plated phosphor bronze wire.

[0010] The preferred technical solution is that the thickness of the nickel plating layer on the surface of the second copper wire is 1 to 2 μm;

[0011] The ratio of the thickness of the tin-cobalt alloy coating on the surface of the third copper wire to the thickness of the tin coating on the surface of the finished nickel-plated phosphor bronze wire is (0.15-0.35):1, and the sum of the thickness of the tin-cobalt alloy coating and the tin coating is 5-10 μm. The preferred technical solution is that the composition of the tin-cobalt alloy plating solution in S3 includes stannous chloride, cobalt chloride, potassium pyrophosphate, polyethyleneimine and water, the pH value is 9.6-10.4, and the current density is 0.7-1.4 A / dm 2, the plating solution temperature is 50-60° C., the molar ratio of total cobalt ions to total stannous ions in the plating solution is (0.45-0.7):1; the molar ratio of total cobalt ions to total stannous ions in the plating solution can be specifically selected as 0.45:1, 0.48:1, 0.5:1, 0.53:1, 0.55:1, 0.6:1, 0.65:1, 0.7:1, and further preferably (0.45-0.6):1.

[0012] The preferred technical solution is that the main components of the pickling solution in S1 include sulfuric acid, copper sulfate, hydrogen peroxide, an organic acid hydrogen peroxide protective agent and water, the volume fraction of the sulfuric acid is 3% to 5.5%; the volume fraction of 30% hydrogen peroxide is 1% to 4.5%, and the concentration of copper ions is 7 to 10 g / L; the pickling temperature is room temperature, and the pickling time is 3 to 7 s.

[0013] The preferred technical solution is that the concentration of stannous chloride in the tin-cobalt alloy plating solution is 23-50 g / L, the concentration of potassium pyrophosphate is 180-250 g / L, the concentration of polyethyleneimine is 15-22 g / L, and the degree of polymerization of polyethyleneimine is 500-2000.

[0014] The preferred technical solution is that the tin-cobalt alloy plating solution further includes a mercapto lower alcohol additive, the mercapto lower alcohol additive is at least one selected from mercaptoethanol, mercaptopropanol, and mercaptopropylene glycol, and the concentration of the mercapto lower alcohol additive in the tin-cobalt alloy plating solution is 15 to 30 g / L, specifically 15, 17, 20, 23, 25, 28, 30 g / L points and the above two points as the maximum and minimum intervals. Furthermore, the concentration of the mercapto lower alcohol additive is 17 to 25 g / L.

[0015] The preferred technical solution is that the composition of the S2 nickel plating solution includes nickel sulfate, nickel chloride, boric acid 20-30 g / L, N, N-diethyl propargylamine 7-10 mg / L, sodium allyl sulfonate 4-9 mg / L, and the total nickel ion content is 72-86 g / L; the pH value is 4.2-5, and the current density is 9-11 A / dm 2 ; The plating solution temperature is 55~65℃.

[0016] The preferred technical solution is that the tin-cobalt alloy plating solution also includes 15 to 25 mL / L of tin plating brightener.

[0017] The preferred technical solution is that the acidic plating solution for tin plating in S4 comprises 32-47 g / L stannous methanesulfonate, 200-250 g / L methanesulfonic acid, 42-58 mL / L tin plating brightener, the plating solution temperature is 20-30 ° C, the current density is 3.5-5 A / dm 2 .

[0018] The preferred technical solution is that the tin plating brightener is a combination of cinnamaldehyde and at least one selected from acrylic acid and methacrylic acid, and the volume percentage of cinnamaldehyde in the tin plating brightener is 90% to 96%. Cinnamaldehyde in the tin plating brightener is used as the main brightener, and its volume percentage can be selected from 90%, 91%, 92%, 93%, 94%, 95%, 96% point values ​​and the above two point values ​​as the maximum and minimum intervals. Further, its volume percentage can be selected from 92% to 96%.

[0019] The advantages and beneficial effects of the present invention are:

[0020] The production process of the nickel-plated phosphor bronze wire arranges a tin-cobalt alloy step between nickel plating and tin plating, and introduces a dense tin-cobalt alloy layer between the nickel plating layer and the tin plating layer, while maintaining the solderability and oxidation solderability of the surface nickel layer, improving the mechanical properties of the nickel-plated phosphor bronze wire and the bonding firmness of the phosphor bronze surface plating. DETAILED DESCRIPTION

[0021] The specific implementation of the present invention is further described below in conjunction with the examples. The following examples are only used to more clearly illustrate the technical solutions of the present invention, and cannot be used to limit the protection scope of the present invention.

[0022] The phosphor bronze wire (hereinafter referred to as copper wire) of the embodiment has the following specifications: wire diameter 0.9±0.01 mm, hardness 3H, and material PB wire;

[0023] Example

[0024] The production process of nickel-plated phosphor bronze wire includes the following steps:

[0025] Annealing: The copper wire is heated to 400℃ in a protective atmosphere and then slowly cooled;

[0026] Cleaning: Degreasing with chemical degreasers;

[0027] Pickling: The copper wire is introduced into the pickling solution for etching. The volume fraction of sulfuric acid in the pickling solution is 3.5%; the volume fraction of 30% hydrogen peroxide is 2.1%, and the concentration of copper ions is 9.5g / L; the pickling temperature is room temperature, the unwinding and rewinding speed of the copper wire is adjusted, and the pickling time is controlled to be 4s;

[0028] The copper wire discharged from the pickling liquid is washed with water and dried to obtain a first copper wire having a corroded rough area on the surface;

[0029] Nickel plating: The first copper wire is introduced into a nickel plating solution, the composition of which is nickel sulfate 200g / L, nickel chloride 38g / L, boric acid 26g / L, N,N-diethylpropargylamine 8mg / L, sodium allyl sulfonate 7mg / L, and the total nickel ion content is 95g / L; the pH value is adjusted to 4.2 by acid and alkali, and the current density is 10A / dm 2; The plating solution temperature is 60°C; A 1.3 μm thick nickel layer is plated on the surface of the first copper wire;

[0030] Washing and drying to obtain a second copper wire with a nickel-plated layer;

[0031] Tin-cobalt alloy plating: the second copper wire is introduced into the tin-cobalt alloy plating solution, and stannous chloride and cobalt chloride are weighed according to the molar ratio of total cobalt ions to total stannous ions in the plating solution of 0.53:1; the composition of the tin-cobalt alloy plating solution is 42.5 g / L stannous chloride, 15.4 g / L cobalt chloride, 200 g / L potassium pyrophosphate, 18.5 g / L polyethyleneimine and water, and the pH value is adjusted to 9.8 with sodium hydroxide solution, and the current density is 1.2 A / dm 2 , the plating solution temperature is 55±2°C; a 1.8 μm thick tin-cobalt alloy layer is plated on the surface of the second copper wire;

[0032] Wash and dry to obtain the third copper wire;

[0033] Tin plating: The third copper wire is introduced into the acidic tin plating solution. The composition of the tin plating solution includes 44g / L stannous methanesulfonate, 245g / L methanesulfonic acid, 40mL / L cinnamaldehyde (main brightener), 2.1mL / L glutaraldehyde (auxiliary brightener), the plating temperature is 25±2℃, and the current density is 4A / dm 2 ; A tin layer with a thickness of 8 μm is plated on the surface of the third copper wire.

[0034] The third copper wire is treated by washing with normal temperature water and 95°C hot water in sequence, and then dried to obtain a finished nickel-plated phosphor bronze wire.

[0035] Example 2-3: Molar ratio of total cobalt ions to total stannous ions

[0036] Based on Example 1, the difference lies in the tin-cobalt alloy plating step:

[0037] Example 2 Tin-cobalt alloy plating: The second copper wire is introduced into a tin-cobalt alloy plating solution, and stannous chloride and cobalt chloride are weighed according to a molar ratio of total cobalt ions to total stannous ions in the plating solution of 0.42:1; the composition of the tin-cobalt alloy plating solution is 42.5 g / L stannous chloride, 12.2 g / L cobalt chloride, 200 g / L potassium pyrophosphate, 18.5 g / L polyethyleneimine and water, and the pH value is adjusted to 9.8 with sodium hydroxide solution, and the current density is 1.2 A / dm 2 , the plating solution temperature is 55±2°C; a 1.8 μm thick tin-cobalt alloy layer is plated on the surface of the second copper wire.

[0038] Example 3 Tin-cobalt alloy plating: The second copper wire is introduced into a tin-cobalt alloy plating solution, and stannous chloride and cobalt chloride are weighed according to a molar ratio of total cobalt ions to total stannous ions in the plating solution of 0.63:1; the composition of the tin-cobalt alloy plating solution is 42.5 g / L stannous chloride, 18.3 g / L cobalt chloride, 200 g / L potassium pyrophosphate, 18.5 g / L polyethyleneimine and water, and the pH value is adjusted to 9.8 with sodium hydroxide solution, and the current density is 1.2 A / dm 2 , the plating solution temperature is 55±2°C; a 1.8 μm thick tin-cobalt alloy layer is plated on the surface of the second copper wire.

[0039] Example 4-5: About mercapto lower alcohol additives

[0040] Example 4 Tin-cobalt alloy plating: The second copper wire is introduced into a tin-cobalt alloy plating solution, and stannous chloride and cobalt chloride are weighed according to a molar ratio of total cobalt ions to total stannous ions in the plating solution of 0.53:1; the composition of the tin-cobalt alloy plating solution is 42.5 g / L stannous chloride, 15.4 g / L cobalt chloride, 200 g / L potassium pyrophosphate, 18.5 g / L polyethyleneimine, 17.5 g / L mercaptoethanol and water, and the pH value is adjusted to 9.8 with sodium hydroxide solution; the current density is 1.2 A / dm 2 , the plating solution temperature is 55±2°C; a 1.8 μm thick tin-cobalt alloy layer is plated on the surface of the second copper wire;

[0041] Example 5 Tin-cobalt alloy plating: The second copper wire is introduced into a tin-cobalt alloy plating solution, and stannous chloride and cobalt chloride are weighed according to a molar ratio of total cobalt ions to total stannous ions in the plating solution of 0.53:1; the composition of the tin-cobalt alloy plating solution is 42.5 g / L stannous chloride, 15.4 g / L cobalt chloride, 200 g / L potassium pyrophosphate, 18.5 g / L polyethyleneimine, 33 g / L mercaptoethanol and water, and the pH value is adjusted to 9.8 with sodium hydroxide solution; the current density is 1.2 A / dm 2 , the plating solution temperature is 55±2°C; a 1.8 μm thick tin-cobalt alloy layer is plated on the surface of the second copper wire;

[0042] Example 6: Tin plating brightener in tin-cobalt alloy plating solution

[0043] Based on Example 4, Example 6 Tin-Cobalt Alloy Plating: The second copper wire is introduced into the tin-cobalt alloy plating solution, and stannous chloride and cobalt chloride are weighed according to the molar ratio of total cobalt ions to total stannous ions in the plating solution of 0.53:1; the composition of the tin-cobalt alloy plating solution is 42.5 g / L stannous chloride, 15.4 g / L cobalt chloride, 200 g / L potassium pyrophosphate, 18.5 g / L polyethyleneimine, 17.5 g / L mercaptoethanol, 18.6 mL / L cinnamaldehyde (main brightener), 1.2 mL / L acrylic acid (auxiliary brightener) and water, and the pH value is adjusted to 9.8 with sodium hydroxide solution; the current density is 1.2 A / dm 2, the plating solution temperature is 55±2°C; a 1.8 μm thick tin-cobalt alloy layer is plated on the surface of the second copper wire.

[0044] Example 7: About tin plating brightener in tin plating solution

[0045] Based on Example 6, Example 7 Tinning: The third copper wire is introduced into an acidic tinning solution, the composition of the tinning solution includes 44 g / L stannous methanesulfonate, 245 g / L methanesulfonic acid, 40 mL / L cinnamaldehyde (primary brightener), 2.1 mL / L acrylic acid (auxiliary brightener), the plating solution temperature is 25 ± 2 ° C, the current density is 4 A / dm 2 ; A tin layer with a thickness of 8 μm is plated on the surface of the third copper wire.

[0046] Comparative Example

[0047] Comparative Example The nickel-plated phosphor bronze wire production process includes sequential annealing, cleaning, pickling, nickel plating and tin plating steps: a 1.3 μm thick nickel plating layer is plated on the surface of the first copper wire to obtain a second copper wire; and a 9.8 μm thick tin plating layer is plated on the surface of the second copper wire.

[0048] The nickel-plated phosphor bronze wires obtained in the examples and comparative examples were tested as follows:

[0049] 1. Tensile strength: Take a wire of about 30cm in length, and use the 25cm mark as the test section. Pull the wires back and forth on the tensile testing machine, and measure the breaking force (breaking beyond 25cm or breaking at the supporting points at both ends is invalid), and calculate the tensile strength (ratio of breaking force to cross-sectional area, unit: kg / mm 2 , π is taken as 3.1416);

[0050] 2. Elongation: The elongation is the percentage of the length increase after the test (the difference between the length after breaking and the length before the test) to the length before the test;

[0051] 3. Solderability test: Adjust the temperature of the tin pot to 420℃, take a wire of about 10 cm long, straighten it, hold one end of the sample with your hand, slowly immerse the other end into the tin pot (3-5s), draw a triangle, and then slowly move away from the tin pot vertically. Qualification requirements: The appearance must be smooth and flat, with tin tips; visual inspection of the percentage of tin adhesion surface to tin immersion surface.

[0052] Heat the oxidized wire at 170℃ for 4h, take it out and quickly immerse it in water, then wipe it dry with a cloth, and then conduct the above weldability test after it is naturally dried.

[0053] 4. Wire winding test: Take a 20 cm long wire as the sample, and another wire of the same diameter as the core material. Wind the sample tightly around the core material for 6 turns. Observe the sample coating at 40 times magnification to see if there are cracks, breakages and other defects. There are 10 samples, and there are 4 observation points per turn.

[0054] The test results of the samples of Examples 1-6 and Comparative Examples are shown in the following table:

[0055] <![CDATA[Tensile strength / kg / mm 2 > Elongation / % Winding test Example 1 81.92 0.51 No cracks Example 2 81.06 0.49 A total of 3 cracks Example 3 78.13 0.44 A total of 5 cracks Example 4 86.74 0.58 No cracks Example 5 86.78 0.57 No cracks Example 6 88.32 0.62 No cracks Example 7 89.87 0.63 No cracks Comparative Example 72.34 0.42 A total of 1 crack

[0056] In the solderability test of the samples of Examples 1-7 and the comparative example, the percentage of tin-attached surface to tin-immersed surface was greater than 95%, with tin tips, and the wire solderability test after oxidation was qualified (the percentage of tin-immersed surface was greater than 95%, with tin tips), indicating that the solderability of the samples mainly depends on the tin-plated layer on the surface of the copper wire, and the above thickness difference (8μm / 9.8μm) has no obvious effect on the solderability of the samples.

[0057] Example 1 and Comparative Example: The tin-cobalt alloy plating layer is partially substituted for the tin plating layer, and the tin-cobalt alloy plating layer is sandwiched between the tin plating layer and the nickel plating layer, indicating that the tin-cobalt alloy layer electroplated under the process conditions of Example 1 has good elongation, tensile strength and plating bonding strength;

[0058] Example 1, Example 2, and Example 3: The total cobalt ion content of the tin-cobalt alloy plating solution is relatively small, the cobalt content in the tin-cobalt alloy is relatively low, the coating is bright and white, the toughness of the tin-cobalt alloy coating is reduced, and the coating bonding strength is reduced compared with Example 1. When the total cobalt ion content of the tin-cobalt alloy plating solution is too high, a mist coating is likely to appear, the density of the coating decreases, the brittleness increases, resulting in a deterioration of the tensile strength and elongation, among which the decrease in elongation is more obvious, and the coating bonding strength decreases.

[0059] Example 1 and Examples 4 and 5: Polyethyleneimine acts as a primary brightener and grain refiner in the tin-cobalt alloy plating solution, and forms a complex with metal ions to improve the dispersion of metal ions in the plating solution. Mercaptoethanol is used to further adjust the viscosity of the tin-cobalt alloy plating solution, and the brightness of the tin-cobalt alloy coating is higher, and the tensile strength, elongation and bonding strength of the coating are further improved. Compared with Example 4, the mercaptoethanol concentration of Example 5 is further increased, and the brightness of the plated tin-cobalt alloy coating does not change significantly, and the tensile strength and elongation are equivalent to those of Example 4.

[0060] Example 4 and Examples 6 and 7 show that the preferred brightener combination is more conducive to improving the tensile strength and elongation of the tin-cobalt alloy coating and the tin coating.

[0061] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A production process for nickel-plated phosphor bronze wire, characterized in that: The following steps are involved: S1: The copper wire is degreased, pickled, and washed in turn to obtain the first copper wire; S2: nickel-plating the first copper wire, and washing with water to obtain a second copper wire; S3: The second copper wire is plated with tin-cobalt alloy and then washed to obtain the third copper wire; S4: The third copper wire is tinned, and then washed with water and hot water to obtain a finished nickel-plated phosphor bronze wire.

2. The production process of nickel-plated phosphor bronze wire according to claim 1, characterized in that: The nickel plating layer on the surface of the second copper wire has a thickness of 1 to 2 μm; The ratio of the thickness of the tin-cobalt alloy coating on the surface of the third copper wire to the thickness of the tin coating on the surface of the finished nickel-plated phosphor bronze wire is (0.15-0.35):1, and the sum of the thickness of the tin-cobalt alloy coating and the tin coating is 5-10 μm.

3. The production process of nickel-plated phosphor bronze wire according to claim 1, characterized in that: The composition of the tin-cobalt alloy plating solution in S3 includes stannous chloride, cobalt chloride, potassium pyrophosphate, polyethyleneimine and water, the pH value is 9.6-10.4, and the current density is 0.7-1.4A / dm 2 , the plating solution temperature is 50-60°C, and the molar ratio of total cobalt ions to total stannous ions in the plating solution is (0.45-0.7):

1.

4. The production process of nickel-plated phosphor bronze wire according to claim 1, characterized in that: The main components of the pickling solution in S1 include sulfuric acid, copper sulfate, hydrogen peroxide, an organic acid hydrogen peroxide protective agent and water. The volume fraction of the sulfuric acid is 3% to 5.5%; the volume fraction of 30% hydrogen peroxide is 1% to 4.5%, and the concentration of copper ions is 7 to 10 g / L; the pickling temperature is room temperature, and the pickling time is 3 to 7 s.

5. The production process of nickel-plated phosphor bronze wire according to claim 3, characterized in that: The concentration of stannous chloride in the tin-cobalt alloy plating solution is 23-50 g / L, the concentration of potassium pyrophosphate is 180-250 g / L, the concentration of polyethyleneimine is 15-22 g / L, and the degree of polymerization of polyethyleneimine is 500-2000.

6. The production process of nickel-plated phosphor bronze wire according to claim 5, characterized in that: The tin-cobalt alloy plating solution also includes a mercapto lower alcohol additive, which is at least one selected from mercaptoethanol, mercaptopropanol, and mercaptopropylene glycol. The concentration of the mercapto lower alcohol additive in the tin-cobalt alloy plating solution is 15-30 g / L.

7. The production process of nickel-plated phosphor bronze wire according to claim 1, characterized in that: The composition of the S2 nickel plating solution includes nickel sulfate, nickel chloride, boric acid 20-30 g / L, N,N-diethylpropargylamine 7-10 mg / L, sodium allyl sulfonate 4-9 mg / L, and the total nickel ion content is 72-86 g / L; the pH value is 4.2-5, and the current density is 9-11 A / dm 2 ; The plating solution temperature is 55~65℃.

8. The production process of nickel-plated phosphor bronze wire according to claim 3, characterized in that: The tin-cobalt alloy plating solution also includes 15 to 25 mL / L of tin plating brightener.

9. The production process of nickel-plated phosphor bronze wire according to claim 1, characterized in that: The acidic plating solution composition of tin plating in S4 includes 32-47 g / L stannous methanesulfonate, 200-250 g / L methanesulfonic acid, 42-58 mL / L tin plating brightener, the plating temperature is 20-30 ° C, the current density is 3.5-5 A / dm 2 .

10. The production process of nickel-plated phosphor bronze wire according to claim 8 or 9, characterized in that: The tin plating brightener is a combination of cinnamaldehyde and at least one selected from acrylic acid and methacrylic acid, and the volume percentage of cinnamaldehyde in the tin plating brightener is 90% to 96%.