JP2001271198A - Copper-coated aluminum wire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a copper-coasted aluminum wire in which generation of fine crackings due to the stress put on a copper film are prevented at the time of drawing, the aluminum wire is hardly exposed at the time of coiling, and sufficient reliability is obtained at the time of soldering and which makes an assembly lighten, thin and shorten. SOLUTION: A mat copper plating layer (3a) is firstly formed by copper electroplating on the periphery of a zinc thin film (2) formed on the surface of an aluminum wire (1) by zincate conversion. Then a thiourea derivatives, etc., are added when the periphery is electroplated with copper to form a semi gloss copper plating layer (3b). Thus the copper-coated aluminum wire (10) is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wire such as a coil used in electronic equipment, and more particularly, to a copper-coated aluminum wire in which aluminum or an aluminum alloy is used as a main conductor and the outer periphery of the main conductor is coated with copper. It is about.

[0002]

2. Description of the Related Art In recent years, as electronic devices and electronic components have become lighter, thinner and smaller, conductors such as coil components used in these devices have also been reduced in diameter. Aluminum or aluminum alloy conductor (hereinafter, abbreviated as aluminum conductor) whose copper content is 1/3 or less of copper.

However, an aluminum conductor has an electrochemically low electric potential. For example, when a new metal surface formed by plastic working such as drawing is exposed to air, the surface is instantaneously oxidized. It is a metal material that is difficult to attach. When an aluminum conductor is used as a wire for an electronic device component, when connecting the aluminum conductor to the terminal of the electronic device component, dissolve the oxide film on the surface with a heated alkaline solution, neutralize with an acid, wash with hot water, Furthermore, after ultrasonic cleaning, it was necessary to connect with aluminum solder, and the terminal connection work was complicated. In addition, due to the lack of mechanical strength of the aluminum conductor itself, a special connection technique was required to maintain sufficient reliability at the connection points.

As described above, since the aluminum conductor has a problem of terminal connection, its specific gravity is slightly larger than that of the aluminum conductor. However, a zinc thin film is formed on the outer periphery of the aluminum conductor, and the outer periphery is continuously coated with electrolytic copper plating. A copper-coated aluminum wire that has been subjected to a drawing process to the size described above has been put on the market as a lighter electric wire that can be soldered.

[0005]

However, in the case of the copper-coated aluminum wire having the above-mentioned structure, a copper-plated layer obtained by electrolytic copper plating having a matte surface has large surface irregularities, and the copper-coated aluminum wire has a large surface unevenness. The stress (resistance) on the die is locally concentrated to form fine cracks, and the aluminum conductor base is easily exposed when adjusting to a desired diameter at the time of coil winding or the like. On the other hand, those having a glossy copper plating layer have no surface irregularities, but the copper coating of the copper plating layer is hard, so that a large stress is applied to the die at the time of the drawing process, resulting in fine cracks. In addition, since the copper film has no ductility, fine cracks are liable to be generated even when winding a step roll, a capstan, or the like with a curvature (for example, 50 mm). Is easily exposed. When the aluminum conductor is exposed on these surfaces, the solder is not wetted only at that portion in the soldering joint, causing a problem that sufficient reliability cannot be maintained.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned various problems of the prior art, and prevents the occurrence of minute cracks due to the stress applied to a copper film during drawing, and prevents the occurrence of aluminum conductors during coil winding. It is an object of the present invention to provide a copper-coated aluminum wire that can solve the problem that the aluminum wire is easily exposed and that can obtain sufficient reliability in soldering and joining and that is suitable for reduction in size and weight.

[0007]

As a first aspect, the present invention relates to a zinc thin film (1) formed by zinc substitution on the surface of a conductor made of aluminum or aluminum alloy (hereinafter abbreviated as aluminum conductor) (1). 2) A copper-coated aluminum wire in which a copper plating layer (3) is continuously coated by electrolytic copper plating on an outer periphery of the copper-coated aluminum wire, wherein the copper plating layer (3) has a matte copper plating layer (3a) and a semi-bright copper plating. In the copper-coated aluminum wire consisting of layer (3b). As the aluminum conductor (1), wrought aluminum having an aluminum purity of 99.0% or more, or an aluminum alloy having an aluminum purity of 99% or more, for example, an Al-Mg alloy or an Al-Mg-Si alloy is used. The outer diameter of the aluminum conductor (1) is not particularly limited, but is preferably φ1.00 mm or less, more preferably 0.10 mm or more and 0.90 mm or less.

[0008] In the copper-coated aluminum wire of the first aspect, the copper plating layer is composed of a matte copper plating layer and a semi-glossy copper plating layer. No. Therefore, the stress applied to the copper film during the drawing process is reduced, and the occurrence of fine cracks can be prevented. Then, the aluminum conductor is not exposed during coil winding. Therefore, sufficient reliability can be obtained in soldering. When the hardness of the copper plating layer (3) was measured by a Vickers hardness tester, on average, the matte copper plating layer was 80 Hv, and the semi-gloss copper plating layer was 100 Hv.
v, the bright copper plating layer was 150 Hv, and it was found that there was considerable correlation between the appearance and hardness of the copper plating layer surface.

According to a second aspect of the present invention, the semi-bright copper plating layer (3b) is formed by adding a thiourea-based additive, a gelatin-based additive, or a polyethylene glycol-based additive alone during electrolytic copper plating. It is a copper-coated aluminum wire formed by adjusting the physical properties by adding it in combination. In the copper-coated aluminum wire according to the second aspect, the semi-bright copper plating layer (3b) is formed by adjusting the physical properties by adding a thiourea-based additive or the like alone or in combination during electrolytic copper plating.

According to a third aspect of the present invention, there is provided a copper-coated aluminum wire in which the amount of the thiourea-based additive, the gelatin-based additive or the polyethylene glycol-based additive is 10 to 50 ppm. In the copper-coated aluminum wire according to the third aspect, a semi-bright copper plating layer having good characteristics can be obtained by adjusting the amount of the additive such as the thiourea-based additive to 10 to 50 ppm. In addition, more preferably, 1
5 to 40 ppm.

As a fourth aspect, the present invention provides a method for producing a matte copper plating layer (3a) and a semi-glossy copper plating layer (3b) by electrolytic copper plating.
After being continuously coated with a copper plating layer (3) made of, the copper-coated aluminum wire which has been further subjected to plastic working and processed to a predetermined size. As the plastic working, cold or hot drawing (drawing) is usually used. In the copper-coated aluminum wire according to the fourth aspect, since the surface of the copper coating of the copper-coated aluminum wire according to the first to third aspects is semi-glossy, the copper-coated aluminum wire having a predetermined size is further subjected to plastic working. Since it is easy to process the material, it is suitable for further weight reduction.

According to a fifth aspect of the present invention, the copper-coated aluminum wire according to the first to fourth aspects has a copper coverage of 20%.
The following are the copper-coated aluminum wires. In the copper-coated aluminum wire according to the fifth aspect, since the copper-coated aluminum wire according to the first to fourth aspects has a copper coverage of 20% or less, the weight reduction of the aluminum conductor is sufficiently maintained, and Since the outer periphery is a copper film, soldering can be easily performed. It should be noted that a wire having a copper coverage of more than 20% is easy to solder, but is not suitable for reducing the weight due to the specific gravity of copper, and is not suitable for reducing the size and weight.

As a sixth aspect, the present invention resides in a copper-coated aluminum wire in which an insulation coating (4) is further provided on the outer periphery of the copper-coated aluminum wire according to the first to fifth aspects. In the copper-coated aluminum wire according to the sixth aspect, the outer periphery of the copper-coated aluminum wire according to the first to fifth aspects is covered with an insulating coating.
Is suitable as a wire material such as a coil used for electronic device parts.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The contents of the present invention will be described below in more detail with reference to an embodiment shown in the drawings. Note that the present invention is not limited by this. FIG. 1 is a sectional view showing an example of the copper-coated aluminum wire of the present invention. FIG. 2 is a sectional view showing another example of the copper-coated aluminum wire of the present invention, which is a copper-coated aluminum wire provided with an insulating coating. In addition, FIG. 1 and FIG. 2 are also referred to for the description of the copper-coated aluminum wire of the comparative example. 1 and 2, 1 is an aluminum or aluminum alloy conductor (aluminum conductor), 2 is a zinc thin layer, 3 is a copper plating layer, 3a is a matte copper plating layer, 3b is a semi-glossy copper plating layer, 4 is Insulation coating, 1
0 is a copper-coated aluminum wire, 10a is a copper-coated aluminum wire (bus wire), and 20 is a copper-coated aluminum wire provided with an insulating coating (hereinafter abbreviated as an insulated copper-coated aluminum wire).

Embodiment 1 (Example 1) As an aluminum conductor (1), an aluminum wire having an outer diameter of 0.90 mm and an aluminum purity of 99.7% was used, and the surface of the aluminum conductor (1) was degreased and etched. Then, a zinc thin film (2) having a thickness of 0.2 μm was formed by zinc substitution. Subsequently, copper pyrophosphate 50 g / l, potassium pyrophosphate 36
The strike copper plating was dipped in a plating solution under the conditions of ^{2 A} / dm ² and 1 minute by a copper pyrophosphate plating bath having a bath temperature of 0 g / l and a bath temperature of 40 ° C. to form a 2 μm thick matte copper plating layer (3a). The outer periphery of the zinc thin film (2) was continuously coated. Subsequently, copper sulfate 100 g / l, sulfuric acid 10
20 g of thiourea was added as an additive to a copper sulfate plating bath having a bath temperature of 0 g / l and a bath temperature of 40 ° C., and 10 A / dm 2
Electric current was applied for 18 minutes under the conditions of ² to provide a semi-bright copper plating layer (3b) having a thickness of 40 μm, thereby forming a copper-coated aluminum wire (bus) (10a) having a diameter of 0.98 mm. Subsequently, cold drawing was performed by a wire drawing machine to produce a copper-coated aluminum wire (10) having a finished outer diameter of 0.155 mm. Further, a polyurethane insulating paint was applied to the outer periphery of the copper-coated aluminum wire (10) and baked to provide an insulating coating (4) having a thickness of 5 μm, thereby producing an insulated copper-coated aluminum wire (20).

Embodiment 2 (Example 2) An aluminum conductor (1) having the same outer diameter as that of Example 1 was used.
Using a 90 mm aluminum wire, the outer periphery of the conductor (1) was continuously coated with a zinc thin film (2) having a thickness of 0.2 μm and a matte copper plating layer (3a) having a thickness of 2 μm in the same manner as in Example 1. . Subsequently, the aluminum conductor (1) provided up to the matte copper plating layer (3a) was coated with copper sulfate 100 g / l and sulfuric acid 100 g / l.
1, 20 ppm of gelatin-based glue was added as an additive to a copper sulfate plating bath having a bath temperature of 40 ° C.
A current of 0 A / dm ² was applied for 18 minutes to provide a semi-bright copper plating layer (3b) having a thickness of 40 μm, thereby forming a copper-coated aluminum wire (bus) (10a) having a diameter of 0.98 mm. Subsequently, the copper-coated aluminum wire bus bar was subjected to cold drawing by a wire drawing machine to produce a copper-coated aluminum wire (10) having a finished outer diameter of 0.155 mm. Further, in the same manner as in Example 1, a polyurethane insulating paint was applied to the outer periphery of the copper-coated aluminum wire (10) and baked to provide an insulating coating (4) having a thickness of 5 μm. Manufactured.

Embodiment 3 (Example 3) As an aluminum conductor (1), an Al-Mg alloy for processing having an aluminum component of 99% or more was used, and the outer periphery of the conductor (1) was formed in the same manner as in Example 1. 0.2 μm thick zinc thin films (2) and 2
A matte copper plating layer (3a) having a thickness of μm was continuously coated. Subsequently, the aluminum conductor (1) provided up to the matte copper plating layer (3a) was coated with copper sulfate 100 g / l, sulfuric acid 100 g / l,
20 ppm of polyethylene glycol was added as an additive to a copper sulfate plating bath having a bath temperature of 40 ° C., and 10 A / d
Electric current was applied for 18 minutes under the condition of m ² to provide a semi-bright copper plating layer (3b) having a thickness of 40 μm, thereby forming a copper-coated aluminum wire (bus) (10a) having a diameter of 0.98 mm. Subsequently, the copper-coated aluminum wire bus bar was subjected to cold drawing by a wire drawing machine to produce a copper-coated aluminum wire (10) having a finished outer diameter of 0.155 mm. Further, in the same manner as in Example 1, a polyurethane insulating paint was applied to the outer periphery of the copper-coated aluminum wire (10) and baked to provide an insulating coating (4) having a thickness of 5 μm.
An insulated copper coated aluminum wire (20) was produced.

Comparative Example Comparative Example 1 An aluminum conductor (1) having the same outer diameter as that of Example 1 was used.
Using a 90 mm aluminum wire, the outer periphery of the conductor (1) was continuously coated with a zinc thin film (2) and a 2 μm thick matte copper plating layer (3a) in the same manner as in Example 1. Subsequently, the aluminum conductor (1) provided up to the matte copper plating layer (3a) was added to a copper sulfate plating bath consisting of copper sulfate 100 g / l, sulfuric acid 100 g / l, and a bath temperature of 40 ° C., without adding any additives. 10A /
Electric current was supplied for 18 minutes under the condition of dm ² to provide a 40 μm thick matte copper plating layer (3b portion) to form a copper-coated aluminum wire (bus) of φ0.98 mm (corresponding to 10a). Subsequently, the copper-coated aluminum wire bus bar was subjected to cold drawing by a wire drawing machine to produce a copper-coated aluminum wire (equivalent to 10) having a finished outer diameter of 0.155 mm. Example 1
In the same manner as described above, an insulating coating (4) having a thickness of 5 μm was provided on the outer periphery of the copper-coated aluminum wire (corresponding to 10) to produce an insulated copper-coated aluminum wire (corresponding to 20).

Comparative Example 2 The same aluminum conductor (1) as in Example 1 was used, except that the outer diameter was 0.1 mm.
Using a 90 mm aluminum wire, the outer periphery of the conductor (1) was continuously coated with a zinc thin film (2) and a 2 μm thick matte copper plating layer (3a) in the same manner as in Example 1. Subsequently, copper sulfate 100 g / l, sulfuric acid 100 g / l, bath temperature 40
100 ppm of thiourea was added as an additive to a copper sulfate plating bath having a temperature of 10 ° C., and a current was applied for 18 minutes under the condition of 10 A / dm ² to provide a 40 μm thick bright copper plating layer (3b portion). Copper-coated aluminum wire (bus bar)
(Equivalent to 10a). Subsequently, cold drawing was performed by a wire drawing machine to produce a copper-coated aluminum wire (equivalent to 10) having a finished outer diameter of 0.155 mm. Further, in the same manner as in Example 1, an insulating coating (4) having a thickness of 5 μm was provided on the outer periphery of the copper-coated aluminum wire (corresponding to 10) to produce an insulated copper-coated aluminum wire (corresponding to 20).

Characteristic test An air-core coil was wound on each of the insulated copper-coated aluminum wires obtained in Examples 1 to 3 and Comparative Examples 1 and 2, and 100 coils were used as test samples. And the back) of the exposed aluminum conductor base (exposed aluminum) were observed with a microscope of 20 times magnification. The results are shown in Table 1 below. FIG. 3 shows an electron micrograph (SEM) of the surface of the copper plating layer. FIG. 3 (a) shows the matte copper plating layer of Comparative Example 1, and FIG. 3 (b) shows the semi-glossy copper plating of Example 1. FIG. 3C shows the bright copper plating layer of Comparative Example 2. Further, when the hardness of the copper plating layer was measured with a Vickers hardness tester, the semi-glossy copper plating layers of Examples 1 to 3 were found to have a hardness of 90%.
~ 110Hv, 70 ~ 8 for the matte copper plating layer of Comparative Example 1
5Hv, and the bright copper plating layer of Comparative Example 2 was 90 to 160
Hv.

[0021]

[Table 1] Aluminum exposure condition test results

As apparent from Table 1, it was confirmed that the copper-coated aluminum wires of Examples 1 to 3 of the present invention did not have aluminum exposure even after coil winding. In addition, in the test sample of Comparative Example 2, the aluminum exposure could be confirmed visually. In addition, as is apparent from the photograph of FIG. 3, the appearance of the semi-glossy copper plating layer of the present invention is clearly different from that of the matte copper plating layer or the bright copper plating layer.

[0023]

The copper-coated aluminum wire of the present invention has a surface unevenness because the copper plating layer formed by electrolytic plating on the outer periphery of the zinc thin film is composed of a matte copper plating layer and a semi-gloss copper plating layer. None compared to matte copper plating layer. Therefore, the stress at the time of drawing is reduced, and the aluminum conductor base is not exposed. Therefore, the reliability of connection at the time of soldering can be obtained. In addition, copper coverage is 20%
Due to the following, the lightness of the aluminum conductor is sufficiently exhibited, and as a result, it is possible to reduce the weight and thickness of the conductor used as a coil wire for electronic device parts and the like. Therefore, the present invention has an extremely large effect of contributing to industry.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an example of a copper-coated aluminum wire of the present invention.

FIG. 2 is a sectional view showing another example of the copper-coated aluminum wire of the present invention, which is a copper-coated aluminum wire provided with an insulating coating.

3 is an electron micrograph (SEM) of the surface of a copper plating layer. FIG. 3 (a) is a matte copper plating layer of Comparative Example 1, FIG. 3 (b) is a semi-glossy copper plating layer of Example 1, In addition, FIG.
Denotes a bright copper plating layer of Comparative Example 2.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Aluminum or aluminum alloy conductor (aluminum conductor) 2 Zinc thin layer 3 Copper plating layer 3a Matte copper plating layer 3b Semi-gloss copper plating layer 4 Insulation coating 10 Copper-coated aluminum wire 10a Copper-coated aluminum wire (bus wire) 20 Insulation coating Provided copper-coated aluminum wire (insulated copper-coated aluminum wire)

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C25D 5/30 C25D 5/30 H01B 5/02 H01B 5/02 A 5/04 5/04 F term (reference 4E096 EA05 EA13 EA26 GA03 KA04 KA09 4K023 AA19 BA06 BA12 CA04 CB05 CB40 4K024 AA09 AB02 AB17 BA06 BB09 BC03 CA02 DA08 DB06 GA14 4K044 AA06 AB04 BA21 BB04 BC08 CA53 5G307 BA04 BB03 BC03 BC07

Claims (6)

[Claims] 1. A copper coated with a copper plating layer (3) by electrolytic copper plating on the outer periphery of a zinc thin film (2) formed by zinc substitution on the surface of a conductor (1) made of aluminum or an aluminum alloy. A copper-coated aluminum wire, wherein the copper plating layer (3) comprises a matte copper plating layer (3a) and a semi-glossy copper plating layer (3b). 2. The semi-bright copper plating layer (3b) is adjusted in physical properties by adding a thiourea-based additive, a gelatin-based additive, or a polyethylene glycol-based additive alone or in combination during electrolytic copper plating. The copper-coated aluminum wire according to claim 1, wherein the wire is formed. 3. The copper-coated aluminum wire according to claim 1, wherein an amount of said thiourea-based additive, gelatin-based additive or polyethylene glycol-based additive is 10 to 50 ppm. 4. A matte copper plating layer formed by electrolytic copper plating.
2. The method according to claim 1, wherein after the copper plating layer (3) comprising the (3a) and the semi-bright copper plating layer (3b) is continuously coated, plastic working is further performed to obtain a predetermined size. The copper-coated aluminum wire according to claim 3. 5. A copper-coated aluminum wire according to claim 1, wherein the copper-coated aluminum wire according to claim 1 has a copper coverage of 20% or less. 6. A copper-coated aluminum wire, characterized in that an insulating coating (4) is further applied to the outer periphery of the copper-coated aluminum wire according to claim 1.