JP5413774B2 - Aluminum alloy conductor - Google Patents

Description

  The present invention relates to an aluminum alloy conductor used in, for example, a power control unit (PCU) of a hybrid vehicle.

  Conventionally, alloy conductors have been used for bus bars, electric / electronic devices, etc. for PCUs of hybrid vehicles. As the alloy conductor, a copper alloy plate having high conductivity and electrolytic Ni plating is used. However, copper alloys and Ni plating have a problem of high cost and large weight. For this reason, development of alternative materials is demanded, and among these, inexpensive and lightweight aluminum alloys are promising.

The alloy conductor used for the above-described bus bar or the like is required to have characteristics such as strength and conductivity. Moreover, since the said alloy conductor is used by electrically connecting this alloy conductor and another member, the joining property with electroconductive connection members, such as an aluminum wire, is requested | required.
However, an aluminum alloy tends to produce an insulating film mainly composed of an oxide or hydroxide on its surface simply by leaving it in the air, and its contact resistance tends to increase. Therefore, the aluminum alloy conductor has a problem that the connectivity with the conductive connecting member is poor.
In order to improve the electrical connectivity of an aluminum alloy conductor, an alloy conductor having a Zn film, Cu plating layer, Sn or Ag plating layer formed on the surface has been developed (see Patent Documents 1 to 3).

JP-A-7-102356 JP-A-8-47793 Japanese Patent Laid-Open No. 11-302855

However, in the conventional aluminum alloy conductor, the plating film is easily damaged by sliding between the electrical connection surfaces. As a result, a battery is formed between the exposed aluminum alloy base material and a plated metal such as Cu or Ag, and there is a problem that corrosion proceeds rapidly particularly in a high temperature and high humidity environment.
Moreover, in the conventional aluminum alloy conductor, since the plating layers of Cu, Ag, Sn, etc. are formed in multiple layers, there is a problem that the cost for plating increases and it is difficult to produce at low cost.
In addition, an aluminum alloy conductor in which a Zn film is formed by a zinc substitution method has been proposed (see Patent Document 3), and this technique is relatively effective against the above-described problems of progress of corrosion and increase in cost. However, the effect was not yet sufficient.

  Moreover, in an aluminum alloy conductor, bondability (bondability) by ultrasonic bonding or the like with a conductive connecting member such as an aluminum wire is important. In particular, aluminum alloy conductors used in automotive parts such as bus bars, for example, must be used in environments with severe temperature changes, so not only the initial bonding strength but also the bonding strength after the thermal history, after the thermal cycle The bonding strength of the steel is required. However, there are few aluminum alloy conductors that satisfy these characteristics, and the development of aluminum alloy conductors suitable for bus bars and the like has been desired.

  The present invention has been made in view of such problems, and an object of the present invention is to provide an aluminum alloy conductor that can be manufactured at a low cost and has excellent bonding strength and corrosion resistance.

  In the present invention, both sides of an aluminum alloy substrate containing 0.3 to 0.7% (mass%, the same shall apply hereinafter) of Si and 0.35 to 0.8% of Mg, the balance being inevitable impurities and aluminum. Alternatively, the aluminum alloy conductor is characterized in that a high purity aluminum film having an aluminum purity of 99.0% or more is formed on one side with a thickness of 0.05 to 0.5 mm per side (Claim 1).

  The aluminum alloy conductor of the present invention contains 0.3 to 0.7% (mass%, hereinafter the same) of Si, 0.35 to 0.8% of Mg, and the balance of the above-mentioned aluminum composed of unavoidable impurities and aluminum. It has an alloy substrate. Therefore, the said aluminum alloy conductor can show the outstanding intensity | strength, for example, can be used suitably as a bus bar etc. of a hybrid vehicle.

  If the Si content is less than 0.3% by mass or the Mg content is less than 0.35% by mass, the strength may be insufficient. On the other hand, when the Si content exceeds 0.7% by mass or the Mg content exceeds 0.8% by mass, deformation resistance during hot rolling increases, and hot rolling may be difficult. is there.

The aluminum alloy conductor has a high-purity aluminum film having an aluminum purity of 99.0% or more on both sides or one side of the aluminum alloy substrate with a thickness of 0.05 to 0.5 mm per side.
Therefore, the aluminum alloy conductor can be bonded to a conductive connecting member such as an aluminum wire or an aluminum tape with sufficiently excellent bonding strength. Moreover, even if it heats and cools repeatedly, the fall of joining strength can be suppressed and the outstanding joining strength can be maintained. Furthermore, even if heating and cooling are repeated, the joint is hardly corroded and has excellent corrosion resistance.

  When the aluminum purity of the high-purity aluminum film is less than 99.0%, or when the thickness of the high-purity aluminum film is less than 0.05 mm, the bonding strength may be insufficient. Moreover, there exists a possibility that the said junction part may become easy to corrode. Further, even if the thickness is increased beyond 0.5 mm, it not only contributes almost to the effect of improving the bonding strength, but the cost may be increased. In this case, the strength of the entire aluminum alloy conductor may be reduced. The aluminum purity of the high-purity aluminum film is preferably 99.5% or more, more preferably 99.9% or more.

  The high-purity aluminum film does not need to be formed by plating or the like, and can be integrated with the aluminum alloy substrate by, for example, clad rolling. Therefore, the aluminum alloy conductor can be easily manufactured at low cost.

  As described above, according to the present invention, it is possible to provide an aluminum alloy conductor that can be manufactured at low cost and has excellent bonding strength and corrosion resistance.

Explanatory drawing which shows the cross-section of the aluminum alloy conductor concerning an Example. Explanatory drawing which shows the cross-section of the aluminum alloy conductor which joined the electroconductive connection member concerning an Example. Explanatory drawing (a) which shows a mode that the aluminum alloy conductor to which the aluminum wire joined concerning an Example was observed from the upper surface, explanatory drawing which shows a mode that a part of aluminum wire remained in the junction part after a shear tension test ( b).

Next, an embodiment of the present invention will be described.
The aluminum alloy conductor has the aluminum alloy base material and the high-purity aluminum film formed on the surface of the aluminum alloy base material.
Depending on the application of the aluminum alloy conductor, the high-purity aluminum film can be formed on both surfaces of the aluminum alloy substrate in the form of a plate, for example, but can also be formed on one surface.

  As described above, the aluminum alloy base material contains 0.3 to 0.7% (mass%, the same shall apply hereinafter) of Si and 0.35 to 0.8% of Mg, with the balance being inevitable impurities and aluminum. Become. That is, the aluminum alloy substrate is made of an Al—Mg—Si (6000) aluminum alloy.

The aluminum alloy base material is preferably made of a plate material having a thickness of 1.5 to 5 mm.
When the thickness is less than 1.5 mm, a practically sufficient strength cannot be exhibited, and the practicality of the aluminum alloy conductor may be reduced. On the other hand, if the thickness exceeds 5 mm, the press formability may be deteriorated in applications where press molding is performed.

The aluminum alloy conductor is preferably obtained by clad rolling in which the plate material for the aluminum alloy substrate and the plate material for the high-purity aluminum film are overlapped and pressure-bonded by rolling (Claim 3).
In this case, the aluminum alloy conductor can be easily manufactured at low cost. In this case, the high-purity aluminum film and the aluminum alloy substrate can be metal-bonded. Therefore, it is possible to prevent the high-purity aluminum film from peeling off.

Specifically, the aluminum alloy conductor is formed, for example, by laminating the plate material for the aluminum alloy base material and the plate material for the high-purity aluminum film, performing hot rolling to obtain a clad material, and further performing cold rolling. It can be manufactured by doing.
The aluminum alloy conductor is preferably a T6 material (JIS H 0001) that is further subjected to a solution treatment and then an age hardening treatment.
In this case, the strength can be improved and electrical conductivity can be ensured by the aging precipitation behavior of the 6000 series aluminum alloy material of the aluminum alloy base material.

The aluminum alloy conductor can be used by being connected to a conductive connecting member in the high-purity aluminum film.
As the conductive connecting member, for example, an aluminum wire or aluminum tape having an aluminum purity of 99.99% or more can be used.

Example 1
Next, an embodiment of the present invention will be described with reference to FIGS.
As shown in FIG. 1, the aluminum alloy conductor 1 of this example has a plate-shaped aluminum alloy base material 2 and a high-purity aluminum film 3 formed on both surfaces thereof.

The aluminum alloy substrate 2 contains 0.3 to 0.7% (mass%, hereinafter the same) of Si, 0.35 to 0.8% of Mg, and the balance is inevitable impurities and aluminum.
The high-purity aluminum film 3 is made of aluminum having a purity of 99.0% or more, and is formed with a thickness of 0.05 to 0.5 mm per side.
As shown in FIG. 2, the aluminum alloy conductor 1 can be used in a high purity aluminum film 3 by being joined to a conductive connecting member 4 such as an aluminum wire having an aluminum purity of 99.99% or more.

Next, the manufacturing method of the aluminum alloy conductor of this example will be described.
First, a plate material for an aluminum alloy substrate and a plate material for a high-purity aluminum alloy film having the composition shown in Table 1 described below were prepared. Then, these plate materials were stacked and subjected to hot rolling, and a plate material for a high-purity aluminum film was pressure-bonded to both surfaces of a plate material for an aluminum alloy substrate. Thereby, a clad material having a thickness of 3.2 mm was obtained. Next, the clad material was cold-rolled to a total thickness of 2 mm. Next, after solution treatment, aging heat treatment was performed to obtain a final aluminum alloy conductor (T6 material). In this example, as shown in Table 1, 12 types of aluminum alloy conductors (Sample E1 to Sample E6 and Sample C1 to Sample C6) were prepared by changing the composition of the aluminum alloy base material and the thickness of the high-purity aluminum film.

(Example 2)
In this example, the characteristics of the aluminum alloy conductors of Samples E1 to E6 and Samples C1 to C6 produced in Example 1 are evaluated.
First, as shown in FIG. 2, an aluminum wire 4 having an aluminum purity of 99.99% or more was joined to the high-purity aluminum film 3 in the aluminum alloy conductor 1 of each sample. Bonding was performed by ultrasonic bonding. And the joining strength in the junction part (wire bonding part) 45 was evaluated as follows.

"Initial bond strength"
As shown in FIG. 3 (a), until the aluminum wire 4 and the aluminum alloy conductor 1 are broken in the directions of arrows A and B in the test piece composed of the aluminum alloy conductor 1 and the aluminum wire 4 joined by the lap joint. Pull (shear tensile test). As shown in FIG. 3B, the area S ₁ of the region 40 where the aluminum wire 4 remains in the joint 45 after the fracture is obtained, the area of the joint 45 before the fracture is S ₀ , and the aluminum wire remaining rate S ( S (%) = S ₁ / S ₀ × 100) was calculated. And as joining strength, the case where an aluminum wire residual rate is 70% or more is evaluated as "(circle)", the case where it exceeds 30% and less than 70% is evaluated as "(triangle | delta)", and the case where it is 30% or less is " “×” was evaluated. The results are shown in Table 2.

"Joint strength after thermal history"
Each sample was heated at 150 ° C. for 3 hours and then cooled to room temperature. Thereafter, the bonding strength of the wire bonding portion was evaluated by the same method as the above-mentioned “initial bonding strength”. The results are shown in Table 2.

"Joint strength after cooling cycle"
Each sample was heated to a temperature of 150 ° C and then cooled to a temperature of -40 ° C for 3000 cycles. Thereafter, the bonding strength of the wire bonding portion was evaluated by the same method as the above-mentioned “initial bonding strength”. The results are shown in Table 2.

"Corrosiveness after thermal cycle"
Each sample was heated to a temperature of 150 ° C and then cooled to a temperature of -40 ° C for 3000 cycles. Then, the cross section of the wire bonding part was observed with the microscope, and the presence or absence of corrosion was observed. And the case where corrosion was not recognized was evaluated as "(circle)", and the case where corrosion was observed was evaluated as "*". The results are shown in Table 2.

  As can be seen from Table 2, it can be seen that Sample E1 to Sample E6 are excellent in initial bonding strength, bonding strength after thermal history, bonding strength after cooling cycle, and corrosion resistance after cooling cycle. On the other hand, Sample C1 to Sample C6 have a defect in any of the characteristics.

  Further, as shown in Example 1, the high-purity aluminum film 3 does not need to be formed by using plating or the like, and can be formed integrally with the aluminum alloy substrate 2 by, for example, clad rolling (FIG. 1) reference). Therefore, the aluminum alloy conductor of this example can be easily manufactured at low cost.

  Therefore, according to the present example, an aluminum alloy base containing 0.3 to 0.7% (mass%, the same shall apply hereinafter) of Si, 0.35 to 0.8% of Mg, and the balance being inevitable impurities and aluminum. Aluminum alloy conductors (sample E1 to sample E6) in which a high-purity aluminum film having an aluminum purity of 99.0% or more is formed on both sides of the material with a thickness of 0.05 to 0.5 mm per side are manufactured at a low cost. It can be seen that the joint strength and corrosion resistance are excellent.

1 Aluminum alloy conductor 2 Aluminum alloy substrate 3 High-purity aluminum coating

Claims (3)

  On both sides or one side of an aluminum alloy base material containing 0.3 to 0.7% (mass%, the same shall apply hereinafter) of Si and 0.35 to 0.8% of Mg, and the balance being inevitable impurities and aluminum, An aluminum alloy conductor characterized in that a high-purity aluminum film having an aluminum purity of 99.0% or more is formed with a thickness of 0.05 to 0.5 mm per side.   2. The aluminum alloy conductor according to claim 1, wherein the aluminum alloy base material is made of a plate material having a thickness of 1.5 to 5 mm.   3. The aluminum alloy conductor according to claim 1, wherein the aluminum alloy conductor is obtained by performing clad rolling in which the plate material for the aluminum alloy substrate and the plate material for the high-purity aluminum film are overlapped and pressure-bonded by rolling. Aluminum alloy conductor.

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