JP3740260B2 - Bump bonder - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a bump bonder for forming a bump for electrical connection on an electrode portion of an IC chip by wire bonding technology.
[0002]
[Prior art]
Various bonders that electrically connect the electrodes of the IC chip and the package conductors by wire bonding technology are introduced in "Semiconductor Handbook (2nd edition)" (issued by Ohm Corporation). Even with such a conventional bonder for wire bonding, it is possible to form bumps for electrical connection on the electrode portion of the IC chip depending on the use thereof, which has already been proposed in, for example, Japanese Patent Application No. 8-249724.
[0003]
As shown in FIG. 5, the bump bonder includes an IC chip supply unit 33 that sequentially supplies a tray 32 containing IC chips 31 to a predetermined position, a bonding unit 34 that forms bumps by ball bonding, and bumps. IC chip discharge unit 36 for sequentially storing and taking out IC chips 31 in tray 35, and transfer means 37 for transferring IC chip 31 between IC chip supply unit 33, bonding unit 34, and IC chip discharge unit 36. Configured. The bonding part 34 is provided with a bonding stage 38 incorporating a heating means for bonding by ultrasonic thermocompression bonding and a bonding head 39 at the rear part thereof.
[0004]
As shown in FIG. 6, the bonding head 39 includes a bonding head main body 39a supported so as to be movable in the XY2 direction at the rear of the bonding stage 38, and a front side of the bonding head main body 39a so as to face the upper surface of the bonding stage 38. A bonding work mechanism 41 and a recognition camera 42 are provided so as to extend .
[0005]
Next, the operation will be described. The IC chip 31 is sequentially taken out from the tray 32 of the IC chip supply unit 33 by the transfer means 37, and one of the plurality of bonding positions 40a and 40b provided on the bonding stage 38 is selected. For example, it is supplied to 40a, and the IC chip 31 is accurately positioned and fixed by suction by a positioning means (not shown). In the meantime, bumps are formed by the bonding head 39 on the IC chip 31 adsorbed and fixed to the other bonding position 40b. When the bump formation is completed, the bonding head 39 moves to the bonding position 40a newly supplied and positioned and fixed by suction, and starts to form bumps on the IC chip 31. In the meantime, the IC chip 31 on which the bump is formed is taken out from the bonding stage 38 by the transfer means 37, transferred and stored in the tray 35 of the IC chip discharge section 36, and further supplied to the bonding position 40b. The IC chip 31 is supplied from the section 33, positioned, and fixed by suction. By repeating the above operation, bumps are formed on the IC chip 31 with high productivity.
[0006]
[Problems to be solved by the invention]
However, in the above-described conventional configuration, the bonding stage 38 is heated to, for example, about 350 ° C. at the maximum, so that the bonding work mechanism 41 and the recognition camera 42 positioned on the upper part are affected by the heat, and There is a problem in that a thermal deformation occurs due to a difference in coefficient of thermal expansion, and a positional deviation occurs in the formed bump. The positional deviation of the bump due to this thermal deformation reaches ± 10 to 15 μm, and when the bump is formed on the IC chip 31 with a minute pitch on the order of several tens of micrometers, the positional deviation is serious.
[0007]
In view of the above-described conventional problems, an object of the present invention is to provide a bump bonder capable of suppressing a bump position shift due to a thermal influence from a stage.
[0008]
[Means for Solving the Problems]
The bump bonder of the present invention includes a stage on which an IC chip is positioned and fixed on an upper surface thereof heated to a predetermined temperature, and a bonding head that forms a bump by bonding a ball formed on a wire tip to an electrode of the IC chip. In the bump bonder provided, the bonding head includes a bonding head main body arranged to be movable in the horizontal direction at the rear part of the stage, and a bonding work mechanism extending forward from the bonding head main body so as to be opposed to the upper surface of the stage. It is equipped with a recognition camera, and at the middle position in the front-rear direction between the bonding head body and the stage, a number of air outlets are formed to blow air forward and form an air flow that flows substantially parallel along the upper surface of the stage. The air blowing pipe is arranged.
[0009]
According to the present invention, it is possible to suppress the heat of the stage from affecting the bonding head side due to the air flow, and it is possible to reduce the bump position deviation due to thermal deformation. For example, what was conventionally ± 10-15 μm can be made ± 5 μm or less. In addition , it is possible to prevent the stage heat from affecting the bonding work mechanism located on the stage and the recognition camera due to the air flow blown out from the air outlet, and the air heated through the stage is the bonding head body side. Because it flows to the opposite side, the influence of heat can be reliably suppressed, and it is only necessary to provide an air blowing tube at the intermediate position in the front-rear direction between the bonding head body and the stage. Can be reduced.
[0010]
Moreover, it is preferable to set the flow velocity of the air blown out from the air outlet to 3 to 10 m / sec, preferably 4 to 6 m / sec. That is, the effect of suppressing the influence of heat is reduced at 3 m / sec or less, and conversely, at 10 m / sec or more, the spark for forming a ball on the wire tip due to the air flow is adversely affected. Balls may not be formed.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a bump bonder according to an embodiment of the present invention will be described with reference to FIGS.
[0012]
1 and 2, reference numeral 1 denotes an IC chip, which is supplied onto the stage 2 by a conveying means (not shown), positioned at a predetermined position by a positioning means (not shown), and then fixed by suction. In addition, the bumps are discharged by the conveying means after forming. The stage 2 has heating means built therein so as to bond by ultrasonic thermocompression bonding, and the maximum temperature is controlled to a predetermined temperature of about 350 ° C. The stage 2 is configured so that the IC chip 1 is positioned and fixed at two positions, and the IC chip 1 can be supplied to and discharged from the other position while the bump is formed at one position. Yes. A bonding head main body 3a mounted on an XY table 4 that can be moved and positioned at an arbitrary position in the X direction and the Y direction is disposed at the rear portion of the stage 2.
[0013]
As shown in FIG. 3, the bonding head 3 having the bonding head main body 3a has a wire reel 21 mounted on a wire reel mounting portion 20 and a wire 10 from the wire reel 21 passed through from above, and the stage 2 A bonding work mechanism 5 for bonding the IC chip 1 is provided. Between the wire reel 21 and the bonding work mechanism 5, a first wire tensioner 17 that applies tension to the wire 10 by blowing the air 10 in an upward curved state with the air 16, and a clamper 6 in the bonding work mechanism 5. A second wire tensioner 19 is disposed directly above the wire guide 6a so as to expose the wire 10 to the upward air 18 and apply an upward tension to the wire 10. The wire 10 from the wire reel 21 is supplied with air 16, 18 is configured to be able to supply the bonding work mechanism 5 without difficulty while floating and supporting so as to maintain a predetermined supply path and tension.
[0014]
As shown in FIGS. 3 and 4, the bonding work mechanism 5 has a clamper 6 that holds and fixes the wire 10, a capillary 7 through which the wire 10 is inserted, and a ball formed at the tip of the wire 10. A horn 8 for applying ultrasonic vibration through a capillary 7 and a discharge torch 9 for forming a ball are provided. Further, a recognition camera 11 for visually recognizing the state of the bonding work is disposed on the upper part of the bonding head 3 and displays a recognition image on a recognition monitor (not shown) and a recognition signal to a data processing device (not shown). To process data.
[0015]
As shown in FIGS. 1 and 4, the clamper 6 and the horn 8 are attached to the front portion of the swinging member 12 that is supported by the horizontal support shaft 13 so as to be swingable up and down, and immediately after the horizontal support shaft 13. A vertical movement electromagnetic drive means 14 is disposed at the position, and a vertical position detection means 15 is disposed at the rear end of the swing member 12. Reference numeral 22 denotes a vertical pivot that pivotally supports an intermediate portion of the clamper 6 so that the intermediate portion can be opened and closed.
[0016]
As shown in FIG. 1 and FIG. 2, the stage 2 and the bonding head main body 3a flow substantially in parallel along the upper surface of the stage 2 toward the front side opposite to the bonding head main body 3a , as shown in FIGS. An air blowing pipe 25 having a large number of air blowing ports 24 is disposed so as to form an air flow. The air outlets 24 are composed of pores having a diameter of about 1 mm, and a large number are formed at a pitch of several mm. The air blowing pipe 25 is connected to an air pressure source via a flow rate adjusting valve (not shown), and has a flow rate of about 3 to 10 m / sec, preferably about 4 to 6 m / sec from each air blowing port 24. It is configured to blow out air.
[0017]
Next, the operation of the bump bonder having the above configuration will be described.
[0018]
When the IC chip 1 is positioned and fixed at a predetermined position on the stage 2, bump formation is performed by the bonding head 3. In this bonding operation, first, the clamper 6 and the capillary 7 are positioned at a predetermined height in the initial state, and the tip of the wire 10 protrudes from the tip of the capillary 7 by a predetermined length. Each time the bonding head 3 moves to a position facing the electrode, the tip is melted by a spark current from the torch 9 to form a ball. The facing position between the capillary 7 and each electrode is controlled with high accuracy based on the visual recognition of the recognition camera 11.
[0019]
Next, after the clamper 6 is opened, the swinging member 12 is swung by the vertically moving electromagnetic drive means 14 to lower the clamper 6 and the capillary 7 toward the IC chip 1. After descending to the lower limit, the ball at the tip of the wire 10 is pressed onto the electrode of the IC chip 1 by the capillary 7 and ultrasonic vibration is applied via the capillary 7 by the horn 8, Are joined by thermocompression bonding and ultrasonic vibration. Pressing force at this time is preferably about 30G～50g, ultrasonic vibration is applied horizontally, amplitude 0.5 [mu] m, is to be about (63.5KH _Z Specific examples) frequency 60～70KH _Z Is preferred.
[0020]
After bonding, the vertical movement electromagnetic drive means 14 is operated to raise the clamper 6 and the capillary 7 by an appropriate distance, and after the wire 10 protrudes from the tip of the capillary 7 by a predetermined length, the open / close electromagnetic drive unit 23 is operated to operate the clamper 6. Is closed and the wire 24 is held and fixed. Thereafter, the up-and-down electromagnetic driving means 14 is actuated again, and the clamper 6 and the capillary 7 enter the ascending process. At the beginning of the ascending process, the wire 10 is cut at the boundary with the heat affected zone, and the ball part and 30 μm are placed on the electrode. A bump having a protruding length of about 60 μm is formed, which is composed of a wire portion protruding to a height of about 40 μm. Thereafter, the clamper 6 and the capillary 7 are raised to a predetermined height position in the initial state. Thereafter, the bump forming operation is repeated.
[0021]
At the time of the above bonding operation, an air flow that flows substantially in parallel along the upper surface of the stage 2 is formed from the numerous air outlets 24 of the air outlet pipe 25 toward the side opposite to the bonding head body 3a. The air flow can suppress the thermal expansion of the heat of the stage 2 by affecting the capillary 7 and the horn 8 and the recognition camera 11 of the bonding head 3, and the air heated through the stage 2 is directed to the bonding head body 3a side. There is no thermal effect due to flow, and the bump position deviation due to thermal deformation can be reduced. By forming the air flow in this way, the bump position error, which is conventionally ± 10 to 15 μm, can be suppressed to ± 5 μm or less.
[0022]
Moreover, since the flow velocity of the air blown out from the air outlet 24 is set to 3 to 10 m / sec, preferably 4 to 6 m / sec, the influence of heat can be effectively suppressed, Therefore, an appropriate ball can be formed without adversely affecting the spark from the torch 9, and a highly accurate bump can be formed.
[0023]
【The invention's effect】
According to the bump bonder of the present invention, as is clear from the above description, an IC chip is fixed on a stage heated to a predetermined temperature, and a ball at the tip of the wire is bonded to the electrode with a bonding head. In the bump bonder to be formed, means for forming an air flow that flows substantially parallel along the upper surface of the stage is provided, so that it is possible to suppress the heat of the stage from affecting the bonding head side due to the air flow. Bump position deviation can be reduced.
[0024]
Further, since the disposed air blowout pipe forming a plurality of air outlet for blowing toward the front of the opposite side of the bonding head air in the front-rear direction intermediate position between the bonding head and the stage, from the air outlet The blown air flow can block the stage's heat from affecting the bonding work mechanism and recognition camera located on the stage, and the air heated through the stage flows to the opposite side of the bonding head body. The effect of the heat of the stage can be reliably suppressed, and it is only necessary to provide an air blowing tube at the intermediate position in the front-rear direction between the bonding head body and the stage. Can be reduced.
[0025]
Moreover, the influence of heat can be effectively suppressed by setting the flow velocity of the air blown out from the air outlet to 3 to 10 m / sec, preferably 4 to 6 m / sec, and forming a ball at the wire tip The ball can be properly formed without adversely affecting the spark.
[Brief description of the drawings]
FIG. 1 is a side view of a stage and a bonding head in a bump bonder according to an embodiment of the present invention.
FIG. 2 is a perspective view schematically showing a stage and a bonding head in the same embodiment.
FIG. 3 is a perspective view of a wire supply mechanism in the bonding head of the same embodiment.
FIG. 4 is a perspective view showing a configuration of a main part of the bonding head of the same embodiment.
FIG. 5 is a perspective view schematically showing a schematic configuration of a conventional bump bonder.
FIG. 6 is a perspective view schematically showing a stage and a bonding head in the conventional example.
[Explanation of symbols]
1 IC chip 2 Stage 3 Bonding head
3a Bonding head body 5 Bonding work mechanism 10 Wire 11 Recognition camera 24 Air outlet 25 Air outlet pipe

Claims (2)

It is heated to a predetermined temperature, a stage on which the IC chip on the upper surface is positioned and fixed in the bump bonder having a bonding head by bonding a ball formed on the wire tip to the electrode of the IC chip to form bumps, ball The bonding head includes a bonding head main body that is disposed at the rear of the stage so as to be movable in the horizontal direction, a bonding work mechanism that extends forward from the bonding head main body so as to face the upper surface of the stage, and a recognition camera. And an air blowing tube having a number of air blowing ports that form air flow that blows air forward and flows substantially parallel along the upper surface of the stage at the middle position in the front-rear direction between the bonding head body and the stage. Bump bonder characterized by having been installed. The bump bonder according to claim 1 , wherein a flow velocity of air blown out from the air blowing port is set to 3 to 10 m / sec, preferably 4 to 6 m / sec.

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