JPS6124821B2 - - Google Patents

Description

[Detailed description of the invention] The present invention melts easily oxidized metal wire such as aluminum wire using electric spark to form a ball.
This invention relates to a method for bonding metal wires.

Previously, aluminum wire could not be used in nail head bonding. The reasons for this are that aluminum wire does not form a ball even when heated with a hydrogen torch, that it oxidizes when heated and contaminates the element surface, and that the torch does not ignite even if you try to heat it in a nitrogen atmosphere to prevent this. It will be done.

The present invention has been made to overcome the drawbacks of the conventional methods, and its object is to provide a method for forming a ball using aluminum wire, which allows nail head bonding using the aluminum wire.

The gist of the present invention to achieve such an object is to use a metal wire that is easily oxidized as a bonding metal wire, form a ball at the tip of this metal wire,
A metal wire bonding method in which the metal wire having a ball at the tip is connected to a predetermined region of a bonding target part, the metal wire for bonding that is easily oxidized is led out from a capillary, and at least the metal wire for bonding that is easily oxidized is led out from the capillary. The tip of the metal wire is placed in an inert gas atmosphere, and when forming the ball, an electrode is placed at a first position spaced apart from the tip of the metal wire by a predetermined distance in the direction in which the metal wire extends, and in this state, the metal wire and the Applying a voltage between the electrodes to generate a discharge between the spaced apart electrodes and the tip of the metal wire, forming a ball at the tip of the metal wire;
After the ball is formed, the electrode is moved to a second position farther from the first position with respect to the tip of the metal wire, and then the metal wire is connected to a predetermined area of the bonded portion. In the metal wire bonding method. Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a partially sectional and partially omitted front view of a ball forming apparatus used in carrying out the present invention. In the same figure, a capillary 1 for nail head bonding is connected to an aluminum wire 2 along the axis.
The aluminum wire 2 has a hole 3 through which the wire is passed.
It is wound around the bobbin 4 for a considerable length and is pulled out from the raw end of the capillary 1 through the hole 3 as required. In addition, a wire clamper 5 is arranged between the capillary 1 and the wire bobbin 4 to appropriately grip the aluminum wire 2, and
An inert gas supply pipe 6 is provided between these so as to extend to the butt of the capillary 1 so that an inert gas such as nitrogen (N ₂ ) can be supplied to the tip of the capillary 1 through the hole 3. Further, a bent electrode piece 7 is arranged near the capillary 1, and one end thereof is placed at a low position, for example, about 1 mm away from the tip of the capillary 1, and the other end is connected to a power source 8. An electric circuit is constructed between the electrode piece 7 and the aluminum wire 2 connected to the aluminum wire 2, so that a park is generated between the electrode piece 7 and the tip of the aluminum wire 2 due to discharge.

Moreover, the electrode piece 7 is attached to the aluminum wire 2 with a ball 9.
It is provided so that it can be moved so that it corresponds to the tip of the capillary 1 only when making the capillary.

Next, the method of forming a ball on an aluminum wire using this device will be explained with reference to FIG. 2. FIG. is capillary 1
It is in a position where it is moved so that it is in a position off the tip of the. From this state, move the electrode piece 7 closer to the capillary 1 as shown in FIG. ₂ ) While the gas is flowing through the hole 3 to the vicinity of the tip of the capillary 1, an arbitrary current is applied from the power source 8 to discharge from the tip of the electrode piece 7 toward the aluminum wire 2.
A spark is generated between these, and the spark melts the aluminum wire 2, forming a ball 9 at the tip.

Therefore, after moving the electrode piece 7 away from the capillary 1 again, nail head wire bonding is performed by moving the electrode piece 7 back and forth between the lead wire and the electrode on the side to be bonded (not shown). Each time the bonding between the electrode and the lead wire is completed, the electrode piece 7 is moved closer to the capillary 1 to form a ball 9 at the tip of the aluminum wire 2.

In the above embodiments, nitrogen (N ₂ ) gas was used as a gas for creating an inert atmosphere, but argon (Ar) gas may also be used. Alternatively, the entire apparatus may be placed in a nitrogen (N ₂ ) atmosphere. Further, the electrical connection between the power source 8 and the aluminum wire 2 is made using a wire bobbin 4 as shown in FIG.
Instead of connecting from the side, it is also possible to connect the aluminum wire 2 through the contact 10 between the wire bobbin 4 and the clamper 5, as shown in FIG.

As is clear from the above description, according to the present invention, the electrode piece 7 is brought close to the tip of the aluminum wire 2 so that the electrode piece 7 corresponds to the tip of the aluminum wire 2, and the aluminum wire 2
The aluminum wire 2 can be melted by the spark generated by discharging toward the tip of the aluminum wire 2, and a ball 9 of any size can be made at the tip of the aluminum wire 2, and the spark can be generated by nitrogen (N ₂ ) gas or the like. Since the vicinity is inactivated to prevent oxidation, nail head wire bonding of the aluminum wire 2, which was previously impossible, becomes possible. Therefore, it is possible to perform the desired wire bonding with inexpensive wire materials such as aluminum wire and gold (Au), and not only can it reduce costs, but it can also contribute to improving product reliability and efficiency. .

[Brief explanation of the drawing]

Fig. 1 is a ball forming apparatus used in carrying out the present invention, Figs. 2 a and b are explanatory diagrams showing a method of forming a ball using the apparatus of Fig. 1, and Fig. 3 is an illustration of a method for forming balls using the apparatus shown in Fig. 1. It is an explanatory diagram showing a connection method. 1... Capillary, 2... Aluminum wire, 3
... Hole, 4 ... Wire bobbin, 5 ... Wire
Clamper, 6... Inert gas supply pipe, 7... Electrode piece, 8... Power supply, 9... Ball, 10... Contact.

Claims (1)

[Claims] 1. A metal wire bonding method in which a metal wire that is easily oxidized is used as a bonding metal wire, a ball is formed at the tip of the metal wire, and the metal wire having the ball at the tip is connected to a predetermined area of a bonded part. , leading out the easily oxidized bonding metal wire from the capillary, placing at least the tip of the leading out bonding metal wire in an inert gas atmosphere, and arranging the metal wire in the direction in which the metal wire extends when forming the ball. An electrode is placed at a first position spaced a predetermined distance from the tip of the metal wire, and in this state, a voltage is applied between the metal wire and the electrode to generate a discharge between the separated electrode and the tip of the metal wire. a ball is formed at the tip of the metal wire, and after the ball is formed, the electrode is moved to a second position that is farther from the first position with respect to the tip of the metal wire, and then the bonded part A metal wire bonding method, characterized in that the metal wire is connected to a predetermined region of the metal wire.