JPH0653220A - Ball-bump bonder - Google Patents

Abstract

PURPOSE:To provide a ball-bump bonder wherein an irregularity in the interval of bump electrodes is eliminated regarding the ball-bump bonder wherein a ball which has been formed at the tip of a wire is compression-bonded to a semiconductor pellet and each bump electrode is formed. CONSTITUTION:In a ball-bump bonder, the intermediate part of a horn 4 in which a capillary 5 is fixed to one end part and by which ultrasonic vibrations are given from the other end part is fixed to a holding block 6 which is turned and moved back and forth around a shaft 7, a wire 14 which is inserted into, and passed through, the capillary 5 and on which a ball has been formed at the tip is pressed onto a pellet, a bump electrode is formed and the rotation and movement of the holding block 6 is braked by an electromagnet 11. In the ball-bump bonder, a heat-conduction preventing means 17 which prevents the conduction of heat generated by the electromagnet is installed between the horn 4 and the electromagnet 11.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ball bump bonder for forming bump electrodes on a semiconductor pellet.

[0002]

2. Description of the Related Art Generally, in a semiconductor device, an electrode on a semiconductor pellet and an external lead are connected by a wire.

However, when the number of external leads is as large as several hundreds as in the case of a driving semiconductor device of a liquid crystal display device, the diameter and width of the electrodes and leads, and the arrangement interval become small, making it difficult to connect by wires.

Therefore, in a multi-lead semiconductor device, TAB is used.
Semiconductor devices using tapes are widely used.

On the other hand, in the semiconductor device using the TAB tape, it is necessary to provide a step between the electrode on the semiconductor pellet and the lead so that the lead does not contact an undesired portion on the semiconductor pellet. The electrode was protruding.

However, since the bump electrodes formed by plating have a problem that the diameter becomes large and the arrangement interval is restricted in order to secure a sufficient height. Therefore, the electrodes are arranged in a staggered manner to narrow the actual interval. There were limits.

Therefore, for example, a wire of 25 μm is inserted into the capillary, the tip of the wire protruding from the tip of the capillary is melted to form a ball, and the ball is pressed against the semiconductor pellet to form a bump.

An example of a ball bump bonder used for this purpose is shown in FIG. In the figure, 1 is an XY table,
Reference numeral 2 is a base block standing on the XY table 1, 3 is a support block arranged laterally of the base block 2 on the XY table 1 and having a bearing 3a in the horizontal direction, and 4 is one end from an intermediate large diameter portion 4a. Side, a horn having a smaller diameter toward the tip, a capillary 5 is fixed to the tip, and an ultrasonic transducer (not shown) is fixed to the other end, and 6 holds a large-diameter portion 4a of the horn 4. Then, a holding block rotatably supported on the bearing 3a of the support block 3 by the rotating shaft 7 is shown. 8 is a load coil (electromagnet) wound around the bobbin 9,
10 is a load yoke supported by the base block 2 and the lower end is inserted into the bobbin 9, 11 is a braking coil (electromagnet) wound around the bobbin 12, 13 is supported by the base block 2, and the lower end is inserted into the bobbin 12. Fig. 3 shows a brake yoke that has been removed. Reference numeral 14 denotes a wire inserted through the capillary 5. This device is provided with a mechanism for rotating the holding block 6 and moving the capillary 5 up and down, but it is not shown.

In this device, the capillary 5 is moved to a predetermined position on the XY table 1 with a ball formed at the tip of the wire 14, and the holding block 6 is turned around the turning shaft 7 by a vertical movement mechanism (not shown). Then, the horn 4 is moved up and down. At this time, the load of the capillary 5 at the time of forming the bump electrode is adjusted by the magnitude of the current flowing through the load coil 8.

When the bonding is completed, the wire 14 is cut and a ball is formed at the tip of the wire protruding from the capillary 5 at a ball forming position apart from the bonding position. A current is applied to the braking coil 8 so that the horn 4 is prevented from wobbling during the horizontal movement of the capillary 5 so that the amount of wire 14 fed out does not change.

[0011]

By the way, since the ball bump bonder originally corresponds to a semiconductor device having a large number of electrodes, the bonding time is longer than the normal wire bonder with respect to the rest time, and as a result, the load coil 8 and the braking coil are increased. Since the operating ratio of 11 is also higher than that of a normal wire bonder, the heat generation of the coils 8 and 11 is remarkable.

On the other hand, although the bump electrodes are formed along the periphery of the semiconductor pellet, the capillary position is set in advance to a constant value as the feed pitch of the XY table 1, whereas the progress from the start to the end of bonding is performed. The heat generated by the coils 8 and 11 is transmitted to the horn 4 over time, and the length, the mounting state, the position, etc. of the horn 4 are different between when the bonding is started and when the bonding is completed. As shown in FIG.
Upper bonding area (white circle at the corner in the example shown)
When the final bump electrode 16b is formed by sequentially bonding the first bump electrode 16a in the direction of the arrow shown in the figure, the position of the bump electrode (black circle shown in the figure) that is actually formed is displaced and deviated from the normal position electrode position by 5 to 10 microns. There was a problem.

For this reason, the positional deviation between the inner lead of the TAB tape and the pump electrode is locally increased, which may result in uncertain connection or complete connection failure.

[0014]

SUMMARY OF THE INVENTION The present invention has been proposed for the purpose of solving the above-mentioned problems, in which a capillary is fixed at one end and an intermediate portion of a horn to which ultrasonic vibration is applied from the other end is rotated. A wire fixed to a holding block that rotates back and forth around an axis and inserted through a capillary and having a ball formed at its tip is pressed onto a pellet to form a bump electrode, and the holding block is rotated by an electromagnet. Provided is a ball bump bonder, characterized in that heat transfer blocking means for blocking transfer of heat generated by an electromagnet is provided between the horn and the electromagnet.

[0015]

According to the above construction, since the heat generated in the coil is prevented from being transferred to the horn, the thermal expansion of the horn and the mounting portion can be ignored even if the operating time elapses, and the gap of the bonding interval does not occur.

[0016]

EXAMPLE An example of the present invention is applied to the ball bump bonder shown in FIG. 2 and described with reference to FIG. In the figure, the same reference numerals as those in FIG. In the present invention, the heat transfer blocking means 17 for blocking the transfer of heat generated by the coil between the coils 8 and 11 which generate a large amount of heat and the connection portion of the holding block 6 with the horn 4 is generated in the coil in the vicinity of the coil. It is characterized in that an air supply pipe 18 for removing heat is arranged.

The air supply pipe 18 is attached to the support block 3 fixed to the movable holding block 6, and its opening is arranged so that the heat taken from the coils 8 and 11 does not affect the horn 4. ing. Further, the air volume is set so as not to affect the braking of the horn 4 and the load of the capillary 5.

Thus, the temperature rise of the horn 4 and the mounting portion can be prevented, and the problem that the pitch is different between the bump electrodes having different positions on the same semiconductor pellet when the bump electrodes are formed can be solved.

Therefore, the semiconductor pellet and the inner lead of the TAB tape can be surely connected, and a highly reliable semiconductor device can be realized.

Although the load coil 8 and the braking coil 11 are separately provided in the above embodiment, the present invention can be applied to a case where one coil is used for both load adjustment and braking.

Further, the present invention can be applied to only the load coil 8 and the braking coil 11 which generate a large amount of heat.

Further, when the entire bonder is in the flowing air, heat radiation fins may be provided in the vicinity of the coils 8 and 11. In this case, the holding block 6 to which the coils 8 and 11 are fixed is provided. The heat dissipation fins may be formed directly.

Further, through holes may be formed in the holding block 6 to reduce the heat transfer cross-sectional area toward the horn 4.

It is also effective to minimize the amount of heat generated by the coil itself by allowing the coil capacity to have a sufficient margin.

[0025]

As described above, according to the present invention, the heat generated by the electromagnet can be prevented from being transferred to the horn, the temperature rise of the horn and the mounting portion due to the lapse of operating time can be prevented, and the same semiconductor pellets can be prevented. Even if a large number of bump electrodes are formed over a long period of time, there is no variation in the intervals between the bump electrodes, and the alignment with the inner leads of the TAB tape is ensured and the connection can be ensured.

[Brief description of drawings]

FIG. 1 is a side sectional view of an essential part of a ball bump bonder showing an embodiment of the present invention.

FIG. 2 is a side sectional view of a main part of a ball bump bonder which is a premise of the present invention.

FIG. 3 is a plan view of a semiconductor pellet showing an arrangement state of bump electrodes by the bonder.

[Explanation of symbols]

 4 Horn 5 Capillary 6 Holding Block 8 11 Electromagnet 14 Wire 17 Heat Transfer Blocking Means 18 Air Supply Pipe

Claims (4)

[Claims] 1. A capillary is fixed to one end and ultrasonic vibration is applied from the other end to an intermediate part of a horn fixed to a holding block which reciprocally rotates about a rotation axis, and is inserted into the capillary and has a ball at the tip. In the ball bump bonder that presses the wire formed with the wire onto the pellet to form the bump electrode and brakes the rotation of this holding block by the electromagnet, the heat transfer of the electromagnet generated between the horn and the electromagnet is performed. A ball bump bonder, characterized in that it is provided with heat transfer inhibiting means for inhibiting the heat transfer. 2. The ball bump bonder according to claim 1, wherein the heat transfer inhibiting means is an air blowing means. 3. The ball bump bonder according to claim 1, wherein the heat transfer prevention means is a heat dissipation fin. 4. The ball bump bonder according to claim 1, wherein a through hole is formed in the holding block to constitute heat transfer inhibiting means.