JPS5944396B2 - Manufacturing method of tinned copper wire - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a highly productive method for manufacturing tinned copper wire of excellent quality.

Coating copper or copper alloy wire with tin or solder, which is an alloy of tin and lead, for the purpose of improving the quality of the copper or copper alloy wire, such as its corrosion resistance and solderability, and to prevent the deterioration of the rubber or plastic insulation coating. It has been practiced since ancient times.

Generally, the thickness of the coating layer is as thin as 0.5 to 2μ, and these are coated by passing copper or copper alloy wire through a bath of molten tin or tin alloy at a high temperature. It has been manufactured using the dip method. Although this is a traditional method that has been industrialized at a relatively high speed using simple equipment, various drawbacks have been pointed out as follows. That is, with the hot dip method, it is difficult to precisely adjust the tin coating thickness;
Because deflection is likely to occur, more tin than necessary is consumed in the coating layer,
Furthermore, high-temperature molten tin oxidizes and becomes ash-like slag, resulting in the loss of a large amount of tin, which is uneconomical. Also, because this method involves high-temperature treatment,
Copper and tin react to form cu6sn5 (
Compound layers such as η phase) and Cu3Sn (ε phase) are formed, and the pure silver coating layer becomes thinner, and the solder jointability is also poor, resulting in a decrease in quality. Furthermore, since it is difficult to produce a coating layer with a thickness of 2 μm or more, it is impossible to produce a coating layer with a thickness of about 10 μm, which requires high quality solder bonding. In place of the above-mentioned dipping method, which has drawbacks in terms of quality and consumption of tin, electroplating methods (hereinafter referred to as plating methods) have been increasingly used.

The plating method allows coating by precisely adjusting the tin layer to a uniform thickness, and eliminates the reduction in the thickness of the pure silver coating layer due to the formation of compounds and the large loss of tin amount due to embrittlement and oxidation, reducing the consumption of tin. is about half or less compared to the dip method. Although the plating method is superior in terms of quality and tin consumption, it requires special equipment compared to the dipping method, and when making thin plated wire, it is difficult to draw the wire to the desired wire diameter. Since the processed thin wire is plated, the plating speed is not much different from the coating speed by the dip method, and it is difficult to say that it is necessarily significantly superior to the dip method in terms of production cost. For this reason, there is a method of plating with thick wire and drawing it to the required size. Since the plating efficiency, ie, the amount of plating processed per unit weight of copper wire, is generally proportional to the wire diameter, this method is particularly suitable for manufacturing fine wires. However, when a thick tinned wire is drawn, a compound forms and develops between the coated tin layer and the copper wire, and as a result, the tin layer is taken up by the compound, resulting in the pure tin layer becoming extremely thin, resulting in a decrease in quality. It turned out that there was a problem with this. The phenomenon of compound formation due to this wire drawing process is
The chemical reaction, that is, the mechanochemical reaction, occurs at a higher rate than the compound formation due to the thermal diffusion reaction in the case of the dipping method, and the tinned wire undergoing wire drawing undergoes a chemical reaction caused by the compressive force from the die and the metal deformation stress. It has been found that this phenomenon sometimes occurs. The present invention was made primarily for the purpose of preventing the above-mentioned mechanochemical reactions and producing a tin-plated copper wire of excellent quality by a highly productive method.
That is, a copper or copper alloy wire is plated with lead or a lead alloy with a thickness of 0.1 to 10μ, then tin or a tin alloy is plated on the outer periphery of the wire, and then the wire is drawn to the desired wire diameter. This is a method for manufacturing tinned copper wire characterized by the following. More detailed description is as follows.

Plating lead or lead alloy on copper wire or copper alloy wire before tin plating prevents the copper and tin from coming into direct contact because there is an intervening layer of lead between the copper and tin. The so-called barrier effect, which prevents the diffusion of copper and tin, has the effect of preventing the generation of copper-tin compounds due to mechanochemical reactions during wire drawing. Plating thickness of lead or lead alloy is 0
．． If it is less than 1μ, there is no prevention effect, and if it exceeds 10μ, the plating layer becomes soft and there is a risk of cracking in the lead layer during wire drawing. The thickness is preferably 1 to 10μ, preferably 0.2 to 5μ. The thickness of tin plating is 0.5 to the thickness of the tin layer of the finished wire diameter.
It can be determined by counting backwards from 2μ, but 1 to 15μ is usually appropriate.Plated strands with a wire diameter of 2 to 3 times are drawn at a drawing speed of 100 to 3,000 m/Mt'n using a regular wire drawing machine. 0.1m
Can be processed into fine wires of n or less. Copper may be plated with lead by a conventional method using a known plating bath mainly containing borofluoride, silicofluoride, or sulfamate, and lead alloy plating may be carried out using, for example, JP-A No. 48-48-3. Plating may be performed by the lead plating method described in No. 80437, and tin and tin alloy plating may also be performed using borofluoride, lead silicate, sulfamate, halide, or organic acid salt as the main components. Plating may be carried out using a known plating bath, and the effects of the present invention can be achieved with any plating method.

Wire drawing may be carried out using the usual equipment and conditions for copper and copper alloys.

That is, a good effect can be obtained by drawing the wire with a high-speed wire drawing machine using an aqueous emulsion containing rapeseed oil and soap as the main ingredients as a lubricant. In addition, when producing soft tin-plated copper wire according to the present invention, the generation of copper-tin compounds due to thermal diffusion will occur even when current annealing is performed through a wire roller connected to the wire drawing process. This is prevented by the barrier action of the intervening layer. Next, an example will be described as follows. Example 1 An annealed copper wire with a wire diameter of 2 m was degreased by alkaline electrolysis, pickled with borohydrofluoric acid, and then soaked in a borofluoride lead bath (lead 4009/T.pH).
1) to a thickness of 2μ, followed by tin plating to a thickness of 3.5μ in a tin borofluoride bath (Tin 3009/t).

This tin-plated wire is drawn using a high-speed wire drawing machine (drawing speed 1,200
A tin-plated hard copper wire was produced by drawing the wire to a diameter of 0.35 m1. When this product was tested by the ammonium persulfate method according to JISC-3002, no blueing due to copper elution was observed, and the uniformity of the plated film was good. The compound layer was measured by a constant current anodic dissolution method, but its presence was not recognized. As a comparative example, a diameter of 0.351 was made by omitting the lead plating in Example 1 and following the same steps as in Example 1! When a tin-plated hard copper wire was subjected to the same test as in the example, it turned blue in 5 minutes and the results were poor. In addition, when the compound layer was measured by the same test as in the example, the η phase of the compound was 0.3
1μ, and the ε phase was 0.05μ. From these results, the effect of this invention on lead plating was confirmed. Example 2 The tinned wire obtained in Example 1 above was used in Example 1.
The wire was drawn using the same high-speed wire drawing machine, but during the wire drawing, it was passed through an annealer to produce tinned annealed copper wire with a diameter of 0.35 mm.

As in Example 1, the test results according to the JIS method were good, confirming the uniformity of the plating layer. Example 3 To the lead plating bath used in Example 1 above, 1 part copper in the form of copper borofluoride was added.
The same process as in Example 1 was carried out except that 9/t was added, and a tinned hard copper wire with a diameter of 0.35 mm was prepared. I made it.

The results of the same test as in Example 1 were good, confirming the uniformity of the plating layer. Example 4 A tin-plated phosphor bronze wire was obtained in the same manner as in Example 1 except that a phosphor bronze wire was used instead of the copper wire in Example 1, and the same good results as in Example 1 were obtained. Obtained.

Example 5 In Example 1 above, instead of tin plating, lead borofluoride 2
The wire was drawn to a diameter of 0.5r1tn in the same manner as in Example 1, except that it was soldered to a thickness of 4μ using a solder plating bath of 0f1/t and 1109/t of tin borofluoride.

When this tin-plated copper wire was subjected to the same test as in Example 1, the results were good, confirming the uniformity of the plating layer. Example 6 In the above Example 1, a diameter of 0.2
The wire was drawn to a thickness of 2 m, and then passed through an annealer to produce tinned annealed copper wire.

This annealed copper wire was tested in the same manner as in Example 1, and the results were good, confirming the uniformity of the plating layer. Example 7 In Example 1 above, the lead plating thickness was set to 0.75μ,
A tin-plated annealed copper wire was produced in the same manner as in Example 1 except that the tin plating thickness was 1.5 μm, and the wire was drawn to a diameter of 1.0 μm and annealed.

When this annealed copper wire was subjected to the same test as in Example 1, the results were good, confirming the uniformity of the plating layer. As described above, the method for manufacturing tin-plated copper wire according to the present invention satisfies conditions such as improved production efficiency, reduced tin consumption, and improved quality, and has extremely high industrial value.

Claims (1)

[Claims] 1. A copper or copper alloy wire is plated with lead or lead alloy with a thickness of 0.1 to 10μ, then plated with tin or a tin alloy, and then wire-drawn to a desired wire diameter. A manufacturing method for tin-plated copper wire.