JPH0316218B2 - - Google Patents

Description

[Detailed description of the invention]

FIELD OF THE INVENTION The present invention relates to a method for manufacturing fine aluminum alloy wire used, for example, as a winding conductor or bonding wire. Description of Prior Art With the advancement of technology in the technical field of electrical equipment, electronic equipment, semiconductor devices, etc., the conductors or bonding wires used in these products have improved in their softening resistance, high-temperature strength, and processability into fine wires. It's been requested. Conventionally, for example, when connecting a semiconductor chip to the outside, a thin metal-through wire containing gold as a main component has been used. However, recently, attention has been paid to the use of aluminum alloy thin wires in order to avoid the use of expensive solid metal thin wires. However, aluminum alloy thin wires have the following drawbacks. In other words, when connecting thin aluminum alloy wires by ball bonding, for example, a portion of the thin wire is first melted by arc discharge to form a ball using surface tension, and then this is bonded to an electrode using heat and ultrasonic waves. Connecting. In this case, the aluminum alloy thin wire is softened by heating,
As a result, the strength may be significantly reduced. For example, when an ultra-fine aluminum alloy wire with a diameter of 30 μm is melted by arc discharge, the parts near it are also heated to a temperature close to the melting point, which softens the wire and significantly reduces its strength, causing it to break at this neck. There were many cases where I ended up doing something wrong. Therefore, there is a need for an aluminum alloy thin wire that can guarantee softening resistance even when heated at high temperatures. However, with the conventional manufacturing method of obtaining fine aluminum alloy wire by processing a molten and cast ingot through multiple processes, it is difficult to obtain softening resistance, and it is difficult to obtain wire drawing processing to make fine wire. It was also difficult to improve sexual performance. Therefore, we heat and press rapidly cooled aluminum alloy powder,
Later, attempts were made to wire-draw this material. However, with this manufacturing method, even if it is possible to satisfy the softening resistance, it is extremely difficult to satisfy the processability into fine wires. OBJECT OF THE INVENTION Therefore, an object of the present invention is to provide a method for producing a thin aluminum alloy wire that can satisfy both softening resistance and workability into a thin wire. Structure of the Invention This invention rapidly cools an aluminum melt to which 0.3 to 5% by weight of Zr has been added by spouting it as a jet into a cooling liquid layer formed by centrifugal force on the inner wall of a rotating drum. This is a method for producing thin aluminum alloy wire, which is characterized by solidifying it into a wire rod with a diameter of 0.4 mm or less. By using "Zr-added aluminum melt", softening resistance is improved. Increasing the amount of Zr added improves heat resistance, that is, softening resistance. The basis for "0.3 to 5% by weight" is based on the following reasons. Metallurgically, the solid solubility limit of Zr in aluminum is 0.28% by weight, so if the aluminum melt contains less than 0.3% by weight of Zr,
It can be manufactured using normal manufacturing methods,
No further effects are observed with the manufacturing method according to the invention. Also, less than 0.3% by weight
If the amount of Zr added is high, it is difficult to obtain an aluminum alloy thin wire that exhibits sufficient softening resistance. On the other hand, 5
If the amount of Zr added is more than % by weight, the effect of improving the softening resistance is saturated, and there is a possibility that workability may be adversely affected. Further, the recommended range of the amount of Zr added is 0.3 to 3% by weight. The reason why the aluminum melt to which 0.3 to 5% by weight of Zr has been added is rapidly solidified by the so-called "rotating liquid spinning method" is as follows. The rotating liquid spinning method is a method suitable for producing continuous thin metal wires. In this method, a continuous thin metal wire is obtained by ejecting molten metal as a jet into a rotating cooling liquid layer, so that the molten material is rapidly cooled and solidified. In the normal cooling and solidification method, Zr added far beyond the solid solubility limit cannot be dissolved in aluminum, but if rapid solidification is performed using the rotating liquid spinning method, the solid solubility limit can be greatly reduced. The Zr added in excess is forcibly dissolved in the aluminum. Furthermore, since the solute element is uniformly dissolved in aluminum, processing into thin wires becomes easier. Furthermore, if the wire is produced by the rotary liquid spinning method, the cross-sectional shape of the obtained wire is likely to be close to a perfect circle. "Coagulating into a wire rod with a diameter of 0.4 mm or less" is
This is because if the diameter exceeds this, it will be difficult to obtain a continuous line. Furthermore, the cooling rate decreases, making it difficult to obtain the effect of improving characteristics by rapid cooling. Preferably, after solidification, at least the area reduction
Wire drawing processing of 20% or more is applied. This is because the cross section can be made uniform and the strength can be improved. "20%
The reason why it is set as "more than 20%" is because the above effect is insufficient if it is less than 20%. Preferably, as the aluminum melt Be,
A material containing a total of 0.001 to 0.3% by weight of one or more elements selected from the group consisting of B and Li is used. This makes it easy to obtain a line with a uniform cross-sectional shape and a shape close to a perfect circle when it is jetted from a molten state into a cooling liquid and rapidly solidified. Furthermore, when performing ball bonding as a bonding wire for wiring of a semiconductor device, the ability to form a ball can be improved. The basis for "0.001 to 0.3% by weight in total" is that if it is less than 0.001%, the above effect is insufficient, and if it exceeds 0.3%, the above effect is saturated. Preferably, the aluminum melt is one selected from the group consisting of Si, Mn, and Mg.
A material containing 3% by weight or less of more than one type of element in total is used. Thereby, the strength of the thin wire can be further improved. "3% or less by weight in total"
This is because if it exceeds 3%, there is a risk that workability will be adversely affected. In addition, Si, Mn,
In addition to Mg, it may contain elements such as Fe, Zn, Cu, and Ti. Preferably, the wire obtained by the method according to the present invention is used as a wiring conductor for a semiconductor device. DESCRIPTION OF EXAMPLES Example 1 An aluminum alloy having the composition shown in Table 1 was melted in a crucible 1 of a spinning submerged spinning apparatus schematically shown in FIG. This melting was performed by heating with a heater 2 placed around the crucible 1. Next, Ar gas is introduced into the crucible 1 from above the crucible 1, and the pressure causes the aluminum melt to be transferred to the rotating drum 3.
The liquid was ejected from a round hole at the bottom of the crucible 1 into a cooling liquid tank formed on the inner peripheral surface of the crucible 1. This allows the diameter
A thin aluminum alloy wire 4 of 0.25 mm was obtained. after that,
This aluminum alloy thin wire 4 was drawn until it had a diameter of 30 μm. For comparison, as a conventional method, an aluminum alloy having the composition shown in Table 1 was melted in a protective atmosphere, and then subjected to semi-continuous casting, hot extrusion, peeling, cold wire drawing, and intermediate annealing to a diameter of 30 μm. I tried wire drawing processing until it became . According to the manufacturing method according to the present invention, all the samples (numbers 1 to 5) could be wire-drawn to a diameter of 30 μm. In particular, for sample numbers 1 to 4, diameters of 30 μm can be easily obtained industrially.
It was possible to draw the wire until it reached m. on the other hand,
In the comparative conventional manufacturing method, it was difficult to wire-draw alloys other than sample number 1. In particular, sample numbers 4 and 5 could hardly be processed. Example 2 A 30 μm diameter wire produced by the production method described in Example 1 was evaluated for softening resistance and high temperature tensile strength. However, since it was not possible to process Samples Nos. 4 and 5 using the comparative conventional manufacturing method, a wire with a diameter of 1 mm was used for evaluation. The results are shown in Table 2. As is clear from the table, the wires obtained by the manufacturing method according to the invention are excellent in softening resistance and high temperature tensile strength. Example 3 Ball bonding was performed using alloy wires (30 μm) having the compositions of sample numbers 1 to 4 according to the method of the present invention. That is, in an Ar gas atmosphere, an arc was generated between the tip of the alloy wire fixed to the capillary and the electrode to melt it, to produce a ball, which was bonded to the electrode part of the semiconductor element. FIG. 2 is a diagram showing a state in which the alloy wire is connected to a semiconductor element. In the figure, 5 is an aluminum alloy thin wire, 6 is a ball bonding part, 7 is an electrode, 8 is a semiconductor element,
9 is a lead frame, 10 is a stitch bonding portion, and 11 is a wire center portion. When a strength test was conducted by pulling the thin aluminum alloy wire 5 as shown by arrow A in the figure from the connection state shown in FIG. It was cut around 11. For comparison, a tensile strength test was conducted using a thin wire made of a conventional Al-1% Si alloy, and the wire broke at the ball bonding portion 6 under a small load. Example 4 The shapes of wires solidified into wires with a diameter of 0.25 mm according to the method of the present invention were compared. Then, sample numbers 2 to 5
The wire was closer to a perfect circle and could be said to have better wire manufacturing properties. Effects of the Invention As described above, according to the present invention, aluminum melt to which 0.3 to 5% by weight of Zr has been added,
The liquid is jetted out as a jet into the cooling liquid layer formed by centrifugal force on the inner wall of the rotating drum, and is rapidly cooled.
Since it is solidified into a wire rod with a diameter of 0.4 mm or less, a thin wire with excellent softening resistance can be obtained, and it can be easily processed into thin wires. Excellent softening resistance occurs during solidification.
This is thought to be due to forced solid solution of Zr. Also,
Processing into thin wires is facilitated because the solute elements are uniformly dissolved in solid solution. The present invention can be applied to various aluminum alloy thin wires such as bonding wires for semiconductor devices such as ICs, fuse conductors, softening-resistant conductors, and conductors with high temperature strength.

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【table】 [Brief explanation of drawings]

FIG. 1 is a diagram schematically showing an example of an apparatus for implementing the present invention. FIG. 2 is a diagram showing an example of a state in which a thin aluminum alloy wire obtained by the manufacturing method according to the present invention is connected to a semiconductor element. In the figure, 1 is a crucible, 2 is a heater, 3 is a rotating drum, 4 is an aluminum alloy thin wire, 5 is an aluminum alloy thin wire, 6 is a ball bonding part, 7 is an electrode, 8
1 shows a semiconductor element, 9 a lead frame, 10 a stitch bonding part, and 11 a central part of a wire.

Claims (1)

[Claims] 1. An aluminum melt to which 0.3 to 5% by weight of Zr has been added is spouted as a jet into a cooling liquid layer formed by centrifugal force on the inner wall of a rotating drum, and is rapidly cooled. A method for producing thin aluminum alloy wire, which is characterized by solidifying it into a wire rod with a diameter of 0.4 mm or less. 2. The amount of Zr added is 0.3 to 3% by weight,
A method for producing a thin aluminum alloy wire according to claim 1. 3. The method for producing a fine aluminum alloy wire according to claim 1 or 2, wherein after solidifying the aluminum melt, wire drawing is performed with an area reduction rate of at least 20% or more. 4 As the aluminum melt, Be, B,
The aluminum alloy fine wire according to any one of claims 1 to 3, which contains a total of 0.001 to 0.3% by weight of one or more elements selected from the group consisting of Li. Production method. 5 As the aluminum melt, Si, Mn,
Manufacture of the aluminum alloy fine wire according to any one of claims 1 to 4, using a wire containing a total of 3% by weight or less of one or more elements selected from the group consisting of Mg. Method. 6. The method for manufacturing an aluminum alloy thin wire according to any one of claims 1 to 5, wherein the wire is used as a wiring conductor of a semiconductor device.