JPH07123130B2 - Bonding device - Google Patents

Description

TECHNICAL FIELD The present invention relates to a bonding apparatus used when, for example, an electrode of an IC chip and a lead of a TAB tape are bonded.

[Conventional technology]

Various methods are used to connect the electrodes of the IC chip to the external leads.

There is also a method of connecting using an ultrafine wire for wiring (bonding wire), but a method of sandwiching a fine metal piece (hereinafter referred to as a bump) between an IC chip electrode and a lead and performing thermocompression bonding is also widely used. It is like this.

The TAB (Tape Automated Bonding) method is drawing attention as a representative of the latter. In this method, bumps are formed in advance either on the electrodes of the IC chip or on the lead tips on the TAB tape, and then the electrodes of the IC chip and the TAB tape having the leads are superposed via the bumps. To join the two. In the TAB method, since a large number of electrodes and leads can be joined at once, a quick bonding operation becomes possible.

By the way, in order to evenly and accurately join a large number of electrodes and leads arranged in a substantially square shape, the pressing surface of the bonding tool that presses these electrodes at the time of joining is a plane including the surface of the electrodes of the IC chip (hereinafter, It must abut parallel to the joint surface). However, in reality, the pressure surface of the bonding tool and the bonding surface of the IC chip should always be parallel because the tilting of the IC chip and the deviation of the mounting surface of the mounting table from the pressure surface of the bonding tool cause deviation. It is difficult to keep. Some of the commercially available bonding devices have a means for adjusting the parallelism, but since this adjusting work must be performed frequently, the adjusting work takes time and the overall work efficiency decreases. There's a problem.

As a solution to this problem, Japanese Patent Laid-Open No. 63-111633 (invention title "Chip Bonding Method") discloses that an IC chip is mounted on a mounting table rotatably supported via spherical bearings. There has been proposed a method of performing bonding by means of bonding. According to this method, even when the IC chip or the bonding tool is tilted at the time of bonding and the bonding tool is only partially contacted with a part of the IC chip, the mounting table can be freely rotated through the spherical bearing due to the pressing force of the bonding tool. To do. As a result, the bonding surface of the IC chip follows the pressing surface of the bonding tool and automatically becomes parallel to the pressing surface of the bonding tool.

[Problems to be Solved by the Invention]

However, even when a spherical bearing is used, there are the following disadvantages.

First, the load applied to the IC chip during bonding is about 4 kgf.
However, because the IC chip itself is at most 1 cm square, the moment that the mounting tool rotates the mounting table when the bonding tool hits the IC chip is not so large. On the other hand, a spherical bearing generally has a considerable sliding resistance, and in order to rotate the mounting table via the spherical bearing, it is necessary to apply a force larger than this sliding resistance.

For this reason, the mounting table does not always rotate quickly when the bonding tool hits the IC chip one-sided. In addition, even if the IC chip is bonded to all the bumps, the load applied to the bonding surface of the IC chip is not uniform, so that the bonding is insufficient, which may cause a failure later.

The present invention has been made based on the above circumstances, and an object of the present invention is to provide a bonding apparatus capable of improving work efficiency, performing reliable bonding, and improving yield.

[Means for Solving the Problems]

The present invention for achieving the above object is a bonding apparatus having a pressing means and a mounting table which is arranged so as to face a pressing surface of the pressing means and on which a pressed body is mounted. Is configured to be supported via an elastic member, which is a deformable tube filled with fluid inside, which maintains parallelism between the pressing surface of the pressing means and the joint surface of the pressed body. It is a thing.

[Action]

According to the present invention, when the joint surface of the pressed body and the pressing surface of the pressing means are deviated from parallel with each other, first, the pressing surface of the pressing means is part of the pressed body as the pressing means descends. Abut. When the pressing means is further lowered, the elastic force provided in the lower part of the mounting table is elastically deformed by the pressing force, so that the joining surface of the pressed body mounted on the mounting table automatically becomes the pressing surface of the pressing means. Change the angle so that they are parallel. When the pressing means continues to descend, a load is applied to the pressed body while the joint surface of the pressed body and the pressing surface of the pressing means remain parallel.

By using a deformable tube filled with fluid such as liquid or gas as the elastic member, the tube is deformed during pressing so that the joint surface of the body to be pressed and the pressure surface of the pressing means are parallel to each other. The angle of the face changes.
When the pressing means is further lowered, the pressure inside the tube is constant, so that a uniform force can be applied to the pressed body.

By using a plurality of springs that have appropriate and equal spring constants as elastic members, the difference in the amount of contraction between each spring due to the change in the angle of the joint surface of the pressed body during pressing (this value is (Equal to the deviation of parallelism) can be suppressed to a negligibly small value for the amount of contraction of each spring. Therefore, a uniform force is applied to the pressed bodies, and the joining is reliably performed.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 and 2. FIG. 1 is a schematic cross-sectional view of a bonding apparatus which is an embodiment of the present invention, and FIG. 2 is a view showing a state in which deviation of parallelism is corrected by the bonding apparatus, and FIG.
The figure is a diagram showing the positional relationship of the IC chips when the deviation of the parallelism is corrected. In this embodiment, a case will be described in which a fine metal ball (hereinafter referred to as a bump) is bonded to an IC chip by a TAB tape thermocompression bonded to the lead tip.

The bonding apparatus shown in FIG. 1 has a bonding tool 2 which is a pressing means, a pressure head 4 which holds the bonding tool, and a bonding receiving portion 6. The bonding tool 2 has a built-in heater (not shown) for heating the tip portion to a temperature of around 500 ° C. The bonding receiving portion 6 includes a mounting table 12 facing the pressing surface 2a of the bonding tool 2 for mounting the IC chip 22, a receiving table 14 for fixing the mounting table 12, and a supporting table 16 for supporting the receiving table 14. An annular tube 18 provided between the receiving table 14 and the holding table 16 is provided. Generally, the mounting table 12 and the receiving table 14 may be integrally formed. Annular tube 18
Is provided so as to surround the bottom of the pedestal 14, and as the material of the annular tube 18, a deformable material such as rubber is used. Further, an incompressible liquid is contained in the annular tube. Above the IC chip 22 is a TAB that moves horizontally.
The tape 24 is placed, and the IC chip 22 and the TAB are placed on the receiving stand 14.
Clamping mechanism 20 to prevent the relative position of tape 24 from shifting
Is provided.

To bond the electrode 23 of the IC chip 22 and the lead 26 of the TAB tape 24, the pressure head 4 is lowered, and the electrode 23 of the IC chip 22 and the TAB are bonded via the bump 28 by the bonding tool 2.
The lead 26 of the tape 24 is thermocompression bonded. In this way, many leads 26 provided on one frame of the TAB tape 24
The electrodes 23 of the IC chip 22 are collectively bonded.
When one IC chip 22 is bonded, the frame of the next TAB tape is moved directly below the bonding tool 2 by the TAB tape feeding mechanism (not shown).
Another IC chip is carried by the transfer means (not shown) onto the mounting table 12, and the next bonding operation is performed.

By the way, if there is an inclination of the IC chip or a deviation from parallel between the mounting surface of the mounting table and the pressing surface of the bonding tool (these are collectively referred to as “parallelism deviation”), the pressing head 4 is moved. When lowering and performing bonding, the pressure surface 2a may first contact only a part of the IC chip 22. This is exaggeratedly shown in FIG.

At this time, in the bonding apparatus of this embodiment, the deviation of the parallelism is compensated as follows. Initially, the pressing surface of the bonding tool 2 as the pressing head 4 descends
2a abuts on a part of the IC chip 22, but when the pressure head 4 further descends, the annular tube 18 corresponding to the part where the bonding tool 2 first abuts is compressed, and the part on the opposite side expands. Since the inside of the annular tube 18 is filled with incompressible liquid, the volume of the entire tube does not change. Therefore, as shown in FIG. 2, the center of gravity of the IC chip 22 is higher than the bottom surface of the support base 16. The height h does not change, and the pedestal rotates about the center of gravity of the IC chip 22. For this reason,
In the cradle 14, the bonding surface of the IC chip 22 is the bonding tool 2
The angle is changed so as to follow the pressure surface 2a. As a result, the deviation of the parallelism between the electrode 23 of the IC chip 22 and the lead 26 of the TAB tape 24 is compensated. Even if the pressure head 4 is further lowered, the pressure inside the annular tube 18 is the same at any position in the circumferential direction, so the pressure applied to each part of the IC chip 22 by the pressure surface 2a becomes uniform, and the bonding is ensured. Can be done.

Since the TAB tape 24 is clamped on the pedestal 14 by the clamp mechanism 20 when performing bonding,
Even when the angle of the pedestal 14 changes, there is no concern that the relative positions of the leads 26 of the TAB tape 24 and the electrodes 23 of the IC chip 22 will shift. Therefore, the IC chip 22 is surely bonded to the lead.

Further, when the above-described operation is performed, the pedestal 14 is rotated to shift the horizontal position of the IC chip 22, that is, the relative position between the IC chip 22 and the bonding tool 2 is shifted, and thus the accuracy is improved. There is also a possibility that proper joining may not be possible. However, as shown in FIG. 3, the IC chip 22 changes from the state before correction (the state before the pedestal follows) shown by the broken line to the state after the correction (state after the pedestal follows) shown by the solid line. Even if the center of the IC chip 22 is rotated by an angle θ, the IC chip 22
The gap is not so problematic. Actually, the electrode position of the IC chip 22 is vertically displaced by about δ _V = 10 μm due to the rotation, but since the size of the IC chip 22 is as small as about 1 cm square, the horizontal displacement is only about δ _H = 0.02 μH. Therefore, the horizontal displacement of the IC chip 22 during bonding can be ignored. Further, since the displacement of the IC chip can be ignored in this way, it is possible to perform the bonding with high accuracy without providing the clamp mechanism.

In the bonding apparatus of the present embodiment, the load applied during bonding is received by the annular tube, so compared to the sliding resistance that is a problem when using a spherical bearing, it is between the pedestal and the support pedestal. Since the working sliding resistance is reduced to such an extent that there is no problem, even a slight deviation in parallelism can be reliably compensated for. In addition, the force applied between each electrode of the IC chip and the bump becomes uniform, and the bonding of these becomes reliable, so that the yield at the time of bonding can be improved. Further, it is not necessary to adjust the parallelism between the pressing surface of the bonding tool and the mounting surface of the mounting table, and the work efficiency can be improved.

In the above embodiment, the case where the annular tube is used as the elastic member provided in the lower part of the pedestal has been described, but the present invention is not limited to this, and a spring, a circular tube or the like is used. May be. FIG. 4 is a schematic sectional view of a bonding receiving portion when a spring is used as the elastic member. When the spring 30 is used as described above, when the pressure head is lowered and the bonding tool comes into contact with a part of the IC chip, the pedestal 16 is elastically deformed by the contraction of the spring and the pedestal 16 is joined to the bonding surface of the IC chip 22. The angle is changed so that the pressing surface of the bonding tool 2 and the pressing surface of the bonding tool 2 are parallel to each other.

Now, how the load from the bonding tool 2 works on the bonding surface of the IC chip 22 will be considered. Here, for the sake of simplicity, only two springs 30a and 30b arranged in the lateral direction and having the same spring constant are dealt with. The bonding surface of the IC chip 22 on the mounting table 6 is inclined with respect to the pressing surface 2a, and as shown in FIG. 4, the electrode 23 on the side of the IC chip 22 where the spring 30a is located
Let us consider a case where is displaced by δ with respect to the electrode 23 on the side where the spring 30b is located. Bonding tool 2
Springs 30a, 3 when IC chip 22 is pressed by
The contraction of 0b (displacement from the balance) is x _a ,
Let x _b be the force _acting on them, and F _a and F _b , respectively, then we have the following relationship.

F _a = k · x _a F _b = k · x _b x _b −x _a = δ Especially if the deviation δ of parallelism is much smaller than the contraction of the spring 30 (x _a , x _b >> δ), F _{a / F c = kx a / kx} b = x a / x b = x a / (x a + δ) = (1 + δ / x a) -1 = 1-δ / x a + (δ / x a) 2 - · From the above, it can be considered that F _a ≈ F _b . Therefore, a substantially uniform force acts on the two springs 30a and 30b, and a uniform load is applied to the joint surface of the IC chip 22. Actually, the parallelism deviation δ is about 20 μm, and the load applied to the IC chip 22 at the time of bonding is about 4 kgf, so a spring having a spring constant that shrinks about 0.5 mm at a load of 1 kgf is used. it allows the above-described force F _a, the difference between F _b rose to about 1%, with a practical accuracy without problems. Although the two springs 30a and 30b have been considered in the above, the same applies to the two springs (not shown) arranged in the direction perpendicular to the drawing.

Further, FIG. 5 is a schematic cross-sectional view of the bonding receiving portion when a circular tube filled with a liquid is used as the elastic member. The action and effect in this case are the same as in the case of using the annular tube. If such a circular tube 40 is easier to manufacture than an annular tube, the circular tube 40 may be used.

Further, in the above embodiment, the case where the leads of the TAB tape on which the bumps are already formed and the electrodes of the IC chip are joined has been described, but the present invention is not limited to this, and the leads of the TAB tape are not limited to this. The present apparatus can also be used in the case of collectively thermocompression bonding a large number of fine metal balls to be bumps at the tip. Therefore, this bonding equipment is used for the manufacturing process of TAB tape with bumps and TAB tape.
It can be used twice in the process of joining with an IC chip. Needless to say, the present device can also be used for bonding with a TAB tape when bumps are formed on the electrode side of an IC chip.

〔The invention's effect〕

As described above, according to the present invention, even if the joint surface of the pressed body and the pressure surface of the pressing means are not parallel, a uniform load is applied to the joint surface of the pressed body without performing adjustment work. Therefore, for example, when joining the IC chip and the TAB tape via bumps, reliable joining can be performed,
It is possible to provide a bonding apparatus that can improve the yield and the work efficiency at the time of bonding.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view of a bonding apparatus according to an embodiment of the present invention, FIG. 2 is a view showing a state in which deviation of parallelism is corrected by the bonding apparatus, and FIG. 3 is this deviation of parallelism. Diagram showing the positional relationship of the IC chip when correcting
FIG. 4 is a schematic sectional view of a bonding receiving portion when a spring is used as an elastic member, and FIG. 5 is a schematic sectional view of a bonding receiving portion when a liquid filled circular tube is used as an elastic member. 2 ... Bonding tool, 2a ... Pressure surface, 4 ... Pressure head, 6 ... Bonding receiving part, 12 ... Mounting table, 14 ... Receiving table, 16 ... Supporting table, 18 ... Annular tube, 20 …… Clamp mechanism, 22 …… IC chip, 23 …… Electrode, 24 …… TAB tape, 26 …… Lead, 28 …… Bump, 30 …… Spring, 40 …… Circular tube.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yasuhide Ono 1618 Ida, Nakahara-ku, Kawasaki-shi, Kanagawa Inside Nippon Steel Co., Ltd. 1st Technology Research Laboratory (72) Inventor Tadakatsu Maruyama 1618 Ida, Nakahara-ku, Kawasaki-shi, Kanagawa Address: Nippon Steel & Steel Co., Ltd., Technical Research Institute No. 1 (56) References Japanese Patent Laid-Open No. 229727/1988

Claims (1)

[Claims] 1. A bonding apparatus having a pressing means and a mounting table which is arranged so as to face a pressing surface of the pressing means and on which a body to be pressed is mounted, wherein the mounting table is added to the pressing means. A bonding apparatus, which is configured to be supported via an elastic member, which is a deformable tube filled with a fluid, which maintains parallelism between the pressure surface and the joint surface of the pressed body.