Electric heating – Metal heating – Wire – rod – or bar bonding
Reexamination Certificate
2002-10-17
2004-08-31
Stoner, Kiley (Department: 1725)
Electric heating
Metal heating
Wire, rod, or bar bonding
C219S056210, C219S130400, C228S180500, C228S004500
Reexamination Certificate
active
06784394
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a ball formation method and ball forming device used in a wire bonding apparatus.
2. Prior Art
A wire bonding apparatus typically includes a step that causes a discharge to occur by way of applying a high voltage between an electric torch and a tip end of a wire that extends out of the lower end of a capillary, thus forming a ball at the tip end of the wire.
Japanese Patent Application Laid-Open (Kokai) No. 9-298215, for instance, discloses a ball forming device that performs a stable discharge by way of eliminating unstable elements during ball formation process in order to obtain a constant ball diameter. In this ball forming device, an electric torch is employed; and this electric torch is covered by a cover, that is made of a tubular insulating material, with a gap between the vicinity of the discharge portion of the electric torch and the insulating material. In other words, because of such a gap, there is no boundary between the electric torch and the cover; and as a result, the diameter of the formed balls can be constant.
The above-described prior art, however, merely eliminates the effects on the electric torch caused by the cover that covers the electric torch; and no alleviation of the effect of the atmosphere that surrounds the electric torch is taken into consideration. Though certain effects are recognized in this device, a constant formation of a small ball in particular is not sufficiently satisfied when it comes to ultra-fine-pitch bonding.
SUMMARY OF THE INVENTION
Accordingly, the object of the present invention is to provide a ball formation method and a ball forming device used in a wire bonding apparatus, in which the free electrons on the surface of an electric torch are activated, the atmosphere surrounding the electric torch is stabilized, and a stable electric discharge is provided so as to produce constant diameter balls at the end of a wire.
The above object is accomplished by a unique ball formation method of the present invention that is used in a wire bonding apparatus in which a discharge is caused to occur by applying a high voltage between an electric torch and a tip end of a wire that extends out of a lower end of a capillary so as to form a ball at a tip end of the wire; and in the present invention, the discharge is performed in a state in which a discharge portion of the electric torch is covered by an insulating member with a space formed between the discharge portion and the insulating member, and in a state in which the space is being heated by a heating means.
The above object is further accomplished by a unique ball forming device of the present invention that is used in a wire bonding apparatus in which a discharge is caused to occur by applying a high voltage between an electric torch and a tip end of a wire that extends out of a lower end of a capillary so as to form a ball at a tip end of the wire; and in the present invention, the ball forming device is comprised of: an insulating member which covers the electric torch with a space formed between the vicinity of a discharge portion of the electric torch and the insulating member, and a heater provided on the insulating member so as to heat the space.
REFERENCES:
patent: 3260890 (1966-07-01), Normando et al.
patent: 4513190 (1985-04-01), Ellett et al.
patent: 4950866 (1990-08-01), Kojima et al.
patent: 4976393 (1990-12-01), Nakajima et al.
patent: 5773780 (1998-06-01), Eldridge et al.
patent: 6234376 (2001-05-01), Wicen
patent: 9-298215 (1997-11-01), None
Kabushiki Kaisha Shinkawa
Kerns Kevin P.
Koda & Androlia
Stoner Kiley
LandOfFree
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