JPS6217856B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a wire bonding device for connecting electrodes of a semiconductor element and external leads using electrically conductive wires in the assembly of semiconductor devices and the like.

Wire bonding using the nail head method involves re-extracting a wire with good electrical conductivity from the tip of a capillary, melting the tip of the wire protruding from the capillary to form a ball, and lowering this ball with the capillary to press it onto the electrode of a semiconductor chip. Then, bonding is performed on the chip side, then the capillary is raised, and the capillary is moved onto the lead, which is the next bonding point, to perform bonding. Bonding is performed before the capillary can be pulled up properly and the capillary does not come into close contact with the capillary. As a result, after bonding, short circuits with other wiring layers or poor strength occur, and good bonding cannot be performed.

Various proposals have been made as means for solving such technical problems. One method is to pull out a wire wound around a rotatably supported spool of a wire supply source, guide it into a capillary, and apply tension to the wire by blowing air from the side of the wire between the spool and the capillary. By pulling up in the opposite direction to the feeding direction,
There is a method in which the ball at the end of the wire is brought into close contact with the capillary, and various devices have been devised as air blowing methods and wire feeder means. However, with this technology, the mass of the spool, the mass of the wire at the air blowing part, the air blowing force, etc. constitute the vibration system, so there is almost no vibration damping effect, and the wire position is not constant with respect to the blowing air. The tension changes become significant, and the wire may break, the capillary and the ball do not follow each other, resulting in short-circuit failures, and other various bonding failures due to the unstable tension.

In contrast to the above, cylinders supported by air bearings so as to be rotatable in opposite directions are arranged in parallel near both sides of the wire extending between the capillary and the spool, and the wire is held between the outer peripheries of both cylinders, and the wire is connected to the spool. Something that provides resistance to the wire is being considered.

Although this improved technique eliminates the disadvantages of simple air blowing, the cylinder acts as an inertial force and may unnecessarily bias the wire as it accelerates or decelerates. In addition, air bearings require strict machining precision, and require a considerable amount of space along with their supporting means since they are juxtaposed with two cylinders.

The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a wire bonding device that can simply and reliably prevent balls from hanging down from a capillary in wire bonding using the nail head method. It is something.

In the present invention, a wire pulled out from a spool is inserted into a main pipe of a wire guide, which has a narrow opening extending inside and outside the pipe on the side of the main pipe, which is provided with a branch pipe to generate an upward gas flow. It is something that guides.

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an explanatory diagram of the bonding apparatus of the present invention.

The wire 1 is usually a gold wire and is used as an electric path to connect the electrode of the semiconductor element 2 and the lead 3.
A spool 5, which is used as a supply source of the wire 1 by winding the wire 1 around a fixed shaft 4, is rotatably supported.

The wire 1 drawn out from the spool 5 is passed through a wire guide 6, passes between wire clamps 7 which can grasp the wire 1 at a suitable time, and the tip thereof passes through a capillary 8 and comes out downward. The capillary 8 is movable up and down above the semiconductor element 2 and the leads 3, and is also movable horizontally between them.
0 is set.

FIG. 2 is an enlarged longitudinal sectional view of the wire guide 6. Although the wire guide 6 is made of glass in this embodiment, it may also be made of other materials, such as ceramics, sintered metal, etc.

The wire guide 6 has a cylindrical main pipe 11 and a branch pipe gas cylinder 12 integrally provided on the side thereof. The gas cylinder 12 may be attachable to the side of the main body 11.
The gas cylinder 12 is connected at a gas inlet 13 to a pipe from a gas source (not shown). Gas cylinder 1
2 is inclined from the gas inlet 13 and descends toward the main pipe 11, but this part is not limited, and may be in a straight line, for example, in line with the opening 14 to be described next. The vicinity of the opening 14 of the gas cylinder 12 to the main pipe 11 faces diagonally upward rather than downward. The location of the opening 14 in the main pipe 11 is the lower outlet 18 of the main pipe 11.
The mounting angle is selected to prevent the inlet gas from leaking out. The wall surface of the main pipe 11 facing the opening 14 is provided with a pore 15 that penetrates the inside and outside of the pipe.

The function of the wire bonding apparatus of the present invention is that after the pre-process, the wire clamp 7 is opened, the capillary 8 is lowered and comes into contact with the ball 9, and the ball 9 is bonded to the electrode of the semiconductor element 2 by pulling the wire 1. The capillary 8 then rises, moves horizontally above the lead 3, and descends to bond onto the lead 3. Thereafter, the wire clamp 7 is closed, the wire 1 is raised together with the capillary 8, and the wire 1 is separated by a tensile force near the bonding on the lead 3.
As described above, an electric path is formed by the wire loop 16 between the semiconductor element 2 and the lead 3.

When wire bonding is performed as described above, gas is supplied from the gas inlet 13 of the gas cylinder 12 of the wire guide 6.

When the capillary 8 descends into close contact with the ball 9 formed at the end of the wire 1, the wire 1 is exposed to gas in the main pipe 11 of the wire guide 6 which is blown into the main pipe 11 through the gas cylinder 12 through the opening 14. The gas creates an upward flow in the main pipe 11 against the feeding direction of the wire 1 and reaches the outlet 17 of the main pipe 11.
escape into the atmosphere. The wire 1 inserted through the main pipe 11 is inserted into the narrow opening 15 at the narrow opening 15 of the main pipe 11.
5 and is discharged from the inside of the main pipe 11 into the atmosphere, which causes the inner wall of the main pipe 11 to receive a force that sticks to it. According to this, the wire 1 in the main pipe 11 is brought to the gas outlet narrow port 15 side. Almost no gas fed into the main pipe 11 from the gas cylinder 12 flows through the lower outlet 18 of the main pipe 11. Therefore wire 1
is urged upward in the main pipe 11 in the opposite direction to the feeding direction of the wire 1, and also contacts the inner wall of the main pipe 11 and has frictional resistance, and when the capillary 8 descends, the wire 1 is forced to Since the resistance is applied, the ball 9 comes into close contact with the tip of the capillary 8.

A constant pressure of gas is fed into the wire guide 6, and the wire 1 produces a constant resistance to its movement, so the tension on the wire 1 is constant and the wire loop 16 does not become too long and sag. In this case, the ball does not get close to the end of the capillary and is not bonded, so short circuit failure does not occur. Furthermore, since the gas rises in the thin main pipe 11, there is no risk of the wire vibrating, and since the wire tension does not increase rapidly, there is no risk of the wire being cut.

The wire guide 6 is located at a position that has conventionally been placed as a mere wire guide, and does not require a special installation space, is simple, and has no risk of failure.

The present invention is not limited to the shape shown in the embodiments, and the inside of the main pipe 11 of the wire guide 6 may be triangular, square, or spiral shaped with a large lead angle, in addition to the circular shape of the above embodiments. . In addition, the opening 14 may be circular, rectangular, diverging, etc. in order to provide an appropriate upward flow, and if the main pipe 11 is circular or spiral-shaped, the opening 14 may be in the diagonal upward direction as well as in the diagonal upward direction. Gas may be allowed to flow in from the tangential direction.

As described above, the bonding apparatus of the present invention has a simple structure and is capable of applying tension to a wire with reliable operation, and is therefore not only suitable for high-speed automatic bonding apparatuses, but also suitable for applying tension to wires in conventional manual low-speed bonding apparatuses. Also suitable for giving.

The bonding is good, there is no breakage of the wire, a constant tension is applied stably, and the wire follows the capillary easily, eliminating the conventional defects and making it possible to use highly reliable and high quality electrodes for semiconductor devices. A good wire loop can be obtained between the leads.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of a bonding device according to the present invention.
FIG. 2 is a partially enlarged view of FIG. 1. DESCRIPTION OF SYMBOLS 1... Wire, 2... Semiconductor element, 3... Lead, 4... Shaft, 5... Spool, 6... Wire guide, 7... Wire clamp, 8... Capillary, 9... Ball, 10... ...torch, 11...main pipe, 12...gas cylinder, 13...gas inlet, 14...
...opening, 15...pore, 16...wire loop,
17...exit, 18...downward exit.

Claims (1)

[Claims] 1. In a wire bonding device that connects a semiconductor element and a lead with a thin wire, a wire guide through which the wire is inserted is disposed between a spool and a capillary, and the wire guide is a tubular main body through which the wire is inserted. It is equipped with a gas cylinder, which is a branch pipe, with an opening diagonally in the opposite direction to the wire feeding direction, in the middle of the pipe.
The main pipe wall facing the opening is provided with a narrow opening that communicates with the inside and outside of the pipe, and by feeding gas into the gas cylinder, the wire is energized in the opposite direction to the feeding direction, and by being attached to the inner wall of the main pipe, the wire is A wire bonding device characterized by applying tension to. 2. The wire bonding apparatus according to claim 1, wherein the wire guide is made of glass.