JPH0665786A - Method for plating wire with copper - Google Patents

Abstract

PURPOSE:To plate a wire with copper, excellent in the plating uniformity by electrodeposition and adhesiveness with high productivity. CONSTITUTION:A wire is traveled, electrolytically pickled and then plated with copper. In this case, the wire is electroplated with copper pyrophosphate and then with copper sulfate. The wire is traveled at the speed of >=5m/min or preferably at the speed of 20-350m/min. The copper pyrophosphate electroplating is carried out at the node current density of <=5A/dm<2> and the cathode current density of 1-40A/dm<2>, and the anode current density/cathode current density is preferably controlled to <=0.5. The copper sulfate electroplating time and electrolytic picking time are preferably made shorter than the copper pyrophosphate electro-plating time. The wire is traveled successively through plural electrolytic cells and repeatedly pickled.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for copper-plating a wire material such as a continuously running wire or steel strip.

[0002]

2. Description of the Related Art Wires, strips, and other filament materials often include a copper plating step in their manufacturing process (for example, welding wire).
The electroplating method, the displacement plating method, etc. are adopted. Each of these plating methods is a method in which a filament material is dipped in a plating solution for traveling, or a coil-shaped filament material is immersed in a plating solution.

Among the electroplating methods, the cyan bath plating method has excellent plating uniformity and adhesion,
In the past, it was often used, but in recent years, from the viewpoint of cost including pollution control, a copper sulfate bath electroplating method or a copper sulfate displacement plating method as a replacement method has come to be used.

[0004]

In the steps of these plating methods, in the case of running the wire rod, as shown in FIG. 1, the wire rod 21 wound on the bobbin 22 is drawn out by a payout device. , Pickling tank 23, water washing tank 24
The surface of the plating bath is pickled to remove the scale, etc. to activate the wire surface, and then the plating bath 2 filled with the plating solution
5 is immersed and run in 5 to plate, rinsed in a rinse tank 26,
It is generally wound up after drying.

However, the copper sulfate plating method (electroplating, displacement plating) is superior to the cyan bath plating method.
There is a problem that unevenness in plating adhesion, plating film thickness, etc. tends to occur, and various proposals have been made in the past to solve this problem. In the progressing situation, an adequate solution has not yet been found.

For example, in Japanese Patent Publication No. 62-33313,
It has been proposed to specify the plating conditions to achieve uniform electrodeposition and adhesion of plating. However, although this proposal has considerably improved the plating quality as compared with the copper sulfate electroplating method before that, a better quality is currently required.

The present invention has been made in order to meet the above-mentioned requirements, and its object is a method capable of ensuring uniform electrodeposition and adhesion of a plating with good plating efficiency in copper plating of wire material. To provide.

[0008]

As a result of various investigations by the present inventors to solve the above-mentioned problems of the prior art, the high productivity is ensured here, and the excellent electrodeposition and adhesion of plating are excellent. The present invention has been completed by discovering a plating method that was used.

That is, according to the present invention, when the traveling linear material is subjected to pickling treatment and then copper plating, electrolytic pickling treatment is applied as pickling and copper pyrophosphate copper electroplating is used as copper plating. The present invention is directed to a method for copper-plating a linear material, which is characterized by further performing copper sulfate electroplating after performing the above.

The present invention will be described in more detail below.

[0011]

[Action]

As described above, one feature of the present invention is that copper pyrophosphate electroplating and copper sulfate electroplating are performed in combination.

[0013] Copper pyrophosphate electroplating has a slow plating speed. Therefore, when it is applied to a running wire material and the productivity is to be maintained, the plating tank must be lengthened to secure the plating time. For this reason, it has been considered that it is not a good idea to apply it to the plating of running linear material.

However, the present inventors have paid attention to the fact that copper pyrophosphate electroplating has excellent adhesion to the steel base material, and apply this characteristic to a wire rod material continuously traveling at a high speed to secure it. As a result of various studies, it was made possible by performing electrolytic pickling in the preceding step of copper pyrophosphate electroplating and performing copper sulfate electroplating in the subsequent step.

That is, by electroplating the electrolytically pickled filamentous material with copper pyrophosphate, a copper plating layer having good adhesion can be uniformly formed in a short time. this is,
It is considered that the application of electrolytic pickling can provide a surface condition suitable for copper pyrophosphate electroplating in a short time.

By applying the electrolytic pickling treatment, it is possible to form a copper plating film having good adhesion to the steel substrate in a short time in the copper pyrophosphate electroplating step which is a post-step, but it is necessary as it is. Because it is not possible to obtain the required plating thickness,
Further, it is necessary to perform copper sulfate electroplating. Copper sulfate electroplating has a high plating rate, and copper plating of a predetermined thickness can be obtained in a short time. Moreover, since plating is already performed on the copper pyrophosphate plating layer, there is no problem with the adhesion, which is a drawback of copper sulfate electroplating.

In such a copper plating method, the treatment conditions are not particularly limited, but the following conditions are preferable.

Running speed of the filament material: If the traveling speed of the filament material becomes too low, the current efficiency becomes low. On the other hand, if it is too high, the current density must be increased in order to obtain a constant film thickness, but burns are likely to occur in the plating. Therefore, the running speed of the wire is 5 m / min or more, especially 20
It is preferably set to 350 m / min.

The pyrophosphate electroplating conditions: anode current density is liable to lower the anodic current efficiency exceeds 5A / dm ^2, so that the take Cu concentration balance in the bath becomes difficult, 5A / dm ² or less and It is desirable to do. The cathode current density is preferably in the range of 1-40 A / dm ² .
If it is less than 1 A / dm ² , the plating efficiency is poor, and it is 40 A.
If it exceeds / dm ² , burns are likely to occur in the plating. If the ratio of the anode current density / cathode current density becomes too large, the adhesion tends to deteriorate, so it is 0.5 or less, and particularly not more than 0.5.
It is preferably 2 or less.

In the electrolytic pickling, as shown in FIG. 2, a linear material is sequentially run in a plurality of electrolytic cells to perform electrolytic pickling repeatedly (repeated electrolytic pickling method). The adhesion of copper pyrophosphate electroplating can be further improved,
In addition, the entire device can be made compact.

This repeated electrolytic pickling method can be carried out under the conditions previously described in JP-A-1-136997.
The number of electrolysis cells is preferably 6 or more, and in the illustrated case, 8 electrolysis cells 1 are sequentially arranged and arranged. The arrangement of electrode polarities is such that (+) (-) (+) (-) is a combination of (+) and (-) alternately, and (+) (+) (-) (-) …, (−) (+)
Combinations such as (−) (+) ..., and other combinations may be used, and may be appropriately selected according to the purpose. Each electrolysis cell 1
Is provided with an insoluble electrode 3 (material: carbon material, etc., shape: plate shape, ring shape, half ring shape, U-shape, box shape, etc.) and is connected to an electrode cable (not shown).
The electrode 3 is preferably arranged so as to surround the traveling wire W. A method is also possible in which the traveling wire inlet 4 and the outlet 5 are not provided and introduced into and out of the electrolytic pickling solution along the side wall of each electrolytic cell.

Further, in order to more effectively bring out the effect of copper pyrophosphate electroplating, it is desirable that the electrolytic pickling time and the copper sulfate electroplating time are each set to be equal to or shorter than the copper pyrophosphate electroplating time. Of course, it is needless to say that the target linear material can have various materials and diameters.

Next, examples of the present invention will be described.

[0024]

Example 1 A mild steel wire rod having a diameter of 4.0 mm was electrolytically pickled,
After washing with water, electroplating with copper pyrophosphate was carried out, followed by washing with water, then electroplating with copper sulfate, washing again with water, drying and winding on a bobbin to obtain a plated mild steel wire.

During the above process, all the wire rods were continuously run. The processing conditions of each step were as follows.

Electrolytic pickling: As shown in FIG. 2, eight electrolytic cells were arranged, and a wire was sequentially run through the electrolytic cells to repeatedly perform electrolytic pickling. As the electrolytic pickling solution, HCl with a concentration of 20% was used, and the bath temperature was 60 ° C. The current density was 500 A / dm ² .

Copper pyrophosphate electroplating: Anode current density: 0.2 A / dm ² Cathode current density: 15 A / dm ² Anode current density / Cathode current density ratio: 0.01 Bath temperature: 60 ° C. Bath composition: Pyrophosphate Copper 95g / l, potassium pyrophosphate 364g / l, ammonia 4ml / l

Copper sulfate electroplating: Anode current density: 2 A / dm ² Cathode current density: 50 A / dm ² Bath temperature: 25 ° C. Bath composition: Copper sulfate 240 g / l, sulfuric acid 20 g / l

The obtained plated steel wire has no plating burn and
There was no peeling at all, and the plating adhesion was very good.
The plating adhesion was evaluated by visually observing the state of plating separation on the surface of the wound wire with a sample wire wound as shown in FIG.

[0030]

Example 2 The ratio of anode current density / cathode current density in copper pyrophosphate electroplating was variously changed, plating was performed under the same conditions as in Example 1 under other conditions, and the effect on plating adhesion was investigated. The result

[Table 1] Shown in. The plating adhesion was examined in the same manner as in Example 1 by examining the plating peeling condition. When there was no peeling, ◎ (very good), when there was a trace of peeling, ○ (good), when there was slight peeling △ (slightly bad), if there is a lot of peeling × (bad)
Was evaluated. As shown in Table 1, it is understood that the ratio of anode current density / cathode current density is preferably 0.5 or less.

[0031]

[Comparative Example] In Example 1, the copper pyrophosphate electroplating step was omitted, and a plated wire rod obtained in the order of electrolytic pickling → water washing → copper sulfate electroplating → water washing → drying → bobbin winding,
Adhesion of plating was investigated for each of the plated wire rods obtained by performing hydrochloric acid immersion pickling instead of electrolytic pickling in Example 1 and performing plating treatment in the subsequent steps under the same conditions as in Example 1. , The adhesion of plating is x (poor) to △
It was (somewhat bad).

[0032]

As described in detail above, according to the present invention,
It is possible to provide a plating method in which both plating adhesion and plating efficiency are extremely good.

[Brief description of drawings]

FIG. 1 is a diagram illustrating a general method for running a wire rod by a copper sulfate plating method (electroplating, displacement plating).

FIG. 2 is a diagram showing an arrangement example of electrolytic cells in electrolytic pickling.

FIG. 3 is a diagram showing a sample wire used for evaluation of plating adhesion.

[Explanation of symbols]

 1 Electrolytic Cell 2 Electrolytic Pickling Solution 3 Electrode 4 Traveling Wire Inlet 5 Traveling Wire Outlet W Wire Strip (Wire)

Claims (7)

[Claims] 1. When the traveling linear material is subjected to pickling and then copper plating, electrolytic pickling is applied as pickling and copper pyrophosphate copper electroplating is applied as copper plating. And a copper plating method for a wire material, which further comprises electroplating copper sulfate. 2. The copper plating method according to claim 1, wherein the running speed of the filament material is 5 m / min or more. 3. The traveling speed of the filament material is 20 to 350 m / min.
The copper plating method according to claim 2, wherein 4. The copper pyrophosphate electroplating is carried out under the following conditions: anode current density: 5 A / dm ² or less, cathode current density: 1-40 A / dm ² anode current density / cathode current density: 0.5 or less. 1. The copper plating method described in 1. 5. The copper plating method according to claim 1, wherein in the electrolytic pickling, the linear member is sequentially run through a plurality of electrolytic cells to repeatedly perform electrolytic pickling. 6. The copper plating method according to claim 1, wherein the time for copper sulfate electroplating is set to be equal to or less than the time for copper pyrophosphate electroplating. 7. The copper plating method according to claim 1, wherein the electrolytic pickling time is equal to or less than the copper pyrophosphate electroplating time.