JPH06105731B2 - Bump transfer method and apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to the production of a TAB tape with bumps used in the TAB method, which is one of the methods of connecting electrodes of an IC chip and external leads. TECHNICAL FIELD The present invention relates to a bump transfer method and device for automatically aligning bumps according to a predetermined array pattern when transferring a metal to be a bump to a lead tip and further joining the bump to a lead tip of a TAB tape. .

[Conventional technology]

The TAB (Tape Automated Bonding) method is used to bond the lead wiring to the electrode part of the IC chip to the tip part of the lead formed by patterning on the TAB tape and the electrode part of the IC chip called bump. It is a method of joining through the metal projections. The bump is in advance on the lead side of the TAB tape,
Alternatively, it is attached to either the electrode side of the IC chip and placed, and the TAB tape and the IC chip are joined by being heated and pressed using a bonding machine.

The method of forming the bumps on the lead side of the TAB tape instead of on the IC chip side has become widely used in recent years because there is no concern of damaging the IC chip during bump bonding.
The method of manufacturing a TAB with bumps is to make the leads thick and leave only the parts that will become bumps, and then thin away the others by etching or the like. Is usually transferred to the tip of the lead. However, the TAB tape with bumps manufactured by these methods has a bump shape close to a rectangle, and it is not necessarily appropriate in terms of bonding with the electrodes of the IC chip.

The inventors of the present application previously filed Japanese Patent Application No. 1-234917 as a new method for forming a spherical bump on the tip of a lead of a TAB tape. In this method, the back side of the mold provided with through holes according to the positions where the bumps should be arranged is sucked into a vacuum, and the metal balls to be the bumps are sucked into the through holes and temporarily fixed, and then the TAB tape is used. The lead and the temporarily fixed metal ball are superposed and transferred and joined.

[Problems to be Solved by the Invention]

The spherical bump is easier to deform than the conventional rectangular bump formed by plating on a glass substrate or the like, and is advantageous in terms of bonding. However, in the case of forming by plating, it is possible to form a bump that specifies a predetermined position to be arranged from the beginning,
Since the spherical bumps are manufactured in a disjointed state, how to efficiently arrange them in a predetermined position, as well as TAB
A major problem is how to easily transfer to the lead portion on the tape.

An object of the present invention is to further develop the previous application and provide an efficient bump transfer method and apparatus suitable for mass production.

[Means for Solving the Problems]

The present invention provides (1) a vacuum suction chamber in which a flat plate having a plurality of through holes of a predetermined size formed in a predetermined pattern corresponding to the arrangement of bumps on the upper surface is provided at a position of a bonding cradle of a TAB bonding machine. Installed, sucking and temporarily fixing the bumps to the through holes of the upper flat plate by using the suction action of the vacuum suction chamber, and then transferring the bumps to the lead tips on the aligned TAB tape by thermocompression bonding. A bump transfer method characterized by the following.

(2) A vacuum suction chamber having a flat plate on which a plurality of through holes of a predetermined size are formed according to a predetermined pattern corresponding to the arrangement of bumps on the upper surface is provided at the position of the bonding cradle of the TAB bonding machine. After the vacuum suction chamber was temporarily removed from the bonding machine body, the bumps were suctioned and temporarily fixed to the through holes of the flat plate, and then the vacuum suction chamber was pulled back to a specific position above the bonding pedestal of the bonding machine and fixed. A bump transfer method characterized in that a series of steps up to the transfer of bumps by thermocompression bonding to the lead tips on the aligned TAB tape are repeated.

(3) It is possible to rotate a drum-shaped vacuum suction chamber in which a plurality of flat plates formed according to a predetermined pattern corresponding to bump positions where a plurality of through holes of a predetermined size are to be arranged are arranged on the circumference. And the upper surface is installed so as to be in a position corresponding to the bonding pedestal of the TAB bonding machine, and while each flat plate on the circumference of the rotating vacuum suction chamber passes through the lower part and reaches the upper part, After sucking and temporarily fixing the bumps to the through holes of the flat plate, when the vacuum suction chamber further rotates and the flat plate on which the bumps are temporarily fixed reaches the upward position, heat is applied to the lead tips on the aligned TAB tape. A bump transfer method characterized in that a series of steps up to the transfer of bumps by pressure bonding are repeated.

(4) A bonding tool having a heating and pressing unit,
A vacuum suction mechanism for generating a suction force for temporarily fixing the bumps to a flat plate on which a plurality of through holes of a predetermined size are formed according to a predetermined pattern corresponding to the array of bumps and which is on the front side of the through holes of the flat plate. Suction / temporary fixing part for bumps on the back side of the flat plate, bump supply mechanism part for arranging / temporarily fixing the bumps on the flat plate having through holes for suction / temporary fixing part of the bump, and lead of TAB tape A bump transfer device comprising a position adjusting mechanism for adjusting the position of the bump.

Is.

That is, the present invention provides a method and an apparatus for producing a TAB tape with bumps. However, the TAB tape with bumps produced by the method or apparatus according to the present invention is a TAB tape lead using a TAB bonding machine. The alignment between the IC chip and the IC chip is performed automatically or manually, and then heated and pressed by the bonding tool.
It is used to bond to the electrode part of the IC chip. The TAB tape itself has a structure in which a large number of frames are continuously formed on the tape, with one IC chip mounted portion as one frame. Usually, the leads are formed by plating copper with gold or tin, and these leads are formed side by side on an insulating tape such as polyimide in a certain pattern. Generally, this is obtained in the state of being wound on a reel, mounted on the bonding machine for each reel, and one frame of the tape rewound from the reel is placed on the bonding stage and aligned with the IC chip. The upper joint is designed to be performed.

In general, bumps are often formed on the IC chip side, so the lead portion of the TAB tape usually does not have bumps. On the other hand, the idea of TAB with bumps is to use one without bumps on the IC chip side.
This is to form bumps on the lead parts of the TAB tape in advance. The present invention relates to the production of a TAB tape with bumps, but the method of joining the bumps to the leads of the TAB tape is the same as the case of joining between the leads and the electrodes of the IC chip as described above. Since it is simple to use the thermocompression bonding effect by pressing the bonding tool, we decided to utilize it. That is, the TAB tape before bonding the bumps is mounted on the bonding machine as it is as a reel, and the spherical bumps are bonded to the lead tips at the bonding stage.

The bonding stage of the bonding machine is usually a bonding cradle on which the IC chip is temporarily placed and fixed,
It consists of a frame-shaped fixture that holds down the TAB tape, and is combined with a mechanism that corrects the relative displacement between the two.
In order to perform the work of bonding bumps on the TAB tape lead by effectively utilizing such a mechanism of the bonding machine, which is the aim of the present invention, the bonding stage part, particularly the bonding cradle on which the IC chip is mounted, is used. It is necessary to remove it and place bumps arranged here so as to match the lead pattern of the TAB tape. Conversely, if bumps arranged according to a certain pattern can be realized on this bonding cradle, the mechanism of the bonding machine can be used as it is to transfer and bond the bumps onto the leads of the TAB tape. It will be possible to do.

FIG. 1 is a schematic diagram for explaining the basic idea of the present invention. FIG. 1 (a) shows a vacuum suction chamber 1 corresponding to a bump suction / temporary fixing portion installed in a bonding pedestal portion. The upper surface of the vacuum suction chamber 1 has a thin flat plate 2 having through holes 3 at positions where bumps should be arranged. The through hole 3 passes through the vacuum suction chamber 1 and is connected to the vacuum port 4 as shown in the cross-sectional cutaway view in the figure. In the cutaway diagram, a tunnel in which only the through hole portion is hollowed is connected to the vacuum outlet, but if the flat plate provided with the through hole is thick and there is no fear of deformation during thermocompression bonding, the vacuum suction chamber 1 It does not matter if the inside of the box is literally hollowed out and a thin flat plate 2 having a through hole is attached to the upper surface thereof. The material of the flat plate 2 is required to be a material that can obtain a uniform flat surface, can process fine through holes, and is not easily affected by heat and pressure during bonding. A thin plate such as stainless steel or nickel, or ceramics is suitable.

Next, as shown in FIG. 1 (b), the vacuum suction chamber 1 which has been evacuated through the vacuum port 4 is set to a large number of bumps 6.
Is placed near the bump supply mechanism portion constituted by the tray 5 on which the bumps are placed, and the bumps are suctioned and temporarily fixed to the through holes 2 as shown in FIG. This process shows the method of sucking up the bumps by reversing the vacuum suction chamber and approaching it from the top in the schematic diagram, but the vacuum suction chamber is sprinkled on the place held in the upward or diagonal state. It is also possible to use the method.

The vacuum suction chamber 1 after sucking and temporarily fixing the bumps is shown in FIG. 1 (d) at the bonding pedestal portion of the bonding machine.
The lead 11 is formed on the film base 12 made of an insulating material such as polyimide by using the alignment adjusting mechanism which is installed as shown in FIG.
The alignment with the TAB tape 10 is performed. After the alignment is completed, a constant load is applied by the bonding tool 7 heated to an appropriate temperature to transfer the bumps temporarily fixed in the through hole of the vacuum suction chamber to the lead portion 11 of the TAB tape. -It is joined.

The vacuum suction chamber 1 on which the bumps are copied returns to the state of FIG. 1B where the bumps are sucked again, and at the same time, the TAB tape for one frame is sent on the bonding machine, and the bumps are transferred and joined as before. By the next frame of the tape to be placed at the standby position, the above process is rewound from the reel.
It can be seen that it provides an efficient method for joining bumps one after another for each frame of the TAB tape.

FIG. 2 schematically shows a more preferable embodiment of the present invention. A plurality of thin flat plates 2 having the through holes 3 are arranged on the circumference of the vacuum suction chamber 1 configured to have a polygonal shape to form bump suction / temporary fixing portions. Each one of the flat plates 2 serves as a bump fixing element responsible for suctioning and temporarily fixing one set of bumps to be arranged. The vacuum suction chamber 1 is attached to the bonding cradle part of the bonding machine, and its upper surface is replaced with the position where the original bonding cradle should be. Although the vacuum suction chamber 1 is shown as an example in which it is composed of eight bump fixing elements in the schematic diagram, this number can of course be freely increased or decreased as necessary. The polygonal vacuum suction chamber 1 is rotated about a shaft portion 4 which also serves as a vacuum suction port, so that the lower portion of the bump supply mechanism portion, in this example, the tray 5 on which the bumps 6 are placed and the automatic bumper replenisher 20. When passing through the configured part, the bumps are sucked into the through holes and temporarily fixed on the flat plate, and when the part reaches the upper bonding position by rotation, alignment with the TAB tape 10 is performed. , Bumps are transferred and joined to the leads 11. After the transfer / bonding of bumps for one frame of TAB tape is completed, the vacuum suction chamber rotates for one unit and the TAB tape is also sent for one frame. At the same time, by performing a series of continuous operations in which the bumps are supplied from the automatic supply device, the transfer / bonding of the bumps to the lead portion of the TAB tape can be performed extremely efficiently.

[Action]

In the method of the present invention, a vacuum suction chamber having a through hole is used in a portion where bumps necessary for one frame of the TAB tape are arranged in a predetermined pattern. A major feature of the soft metal spheres that are easily crushed or soiled to cause defects in the function as bumps is that they can be naturally arranged by the action of a vacuum. In addition, by utilizing the main part of the main body of the TAB bonding machine and replacing only the bonding cradle part with a vacuum suction chamber, the bumps can be bonded accurately and efficiently to the lead ends of the TAB tape. It has become possible.

Further, the device according to the present invention exerts an optimum function in properly performing the above-mentioned step of bonding the bump to the lead portion of the TAB tape.

〔Example〕

Example 1 A vacuum suction chamber as shown by 1 in FIG. 1 was made of stainless steel. The flat plate 2 having the through holes 3 attached to the upper surface of this box was made of stainless steel having a thickness of 30 μm, and the through holes were formed by the etching method. The diameter of the through hole is 60 μmφ
With 50 holes per side, total 200 holes on each side, about 10m
It is formed to be square.

As the bump 6, a gold ball having a diameter of 80 μmφ was used. A large number of gold balls were placed on the plate 5, the vacuum suction chamber was brought close to this plate, and the gold balls were sucked and temporarily fixed to the through hole portion.

The TAB tape 10 has lead tips positioned so as to match the arrangement of through holes in a flat plate.
A lead 11 made of copper plated with gold is formed on the surface 12. This tape is set in advance on the inner lead bonding machine for TAB,
One of the frames is set on the bonding stage. Next, the vacuum suction chamber 1 in which the bumps 6 were temporarily fixed in the through holes 3 was moved to the bonding pedestal portion of the bonding machine while continuously sucking the vacuum.
After adjusting so that the lead position of the TAB tape and the position of the gold ball on the vacuum suction chamber match, the bonding tool 7 heated to 450 ° C is lowered to 3 kgf (per lead).
Bonding was performed for 0.5 seconds with a load of 15 gf).

As a result, all the gold balls temporarily fixed in the through-holes of the flat plate were accurately transferred and bonded one by one to the lead tips of the TAB tape. With respect to the TAB tape after the bonding, the bonding strength of the gold ball was measured by the shear test method. It was found that each lead stably holds 1.5 g or more per lead, and that sufficient strength is imparted in terms of the function as a TAB tape with bumps.

Example 2 An octagonal vacuum suction chamber as shown by 1 in FIG. 2 was produced. The size and arrangement of the through holes 3 for each bump fixing element were all the same as in Example 1. However, the flat plate 2 having a through hole is 30μ made by the electroforming method.
It is made of nickel with a thickness of m. The vacuum suction chamber is incorporated into a bonding pedestal portion of an TAB inner lead bonding machine, and a vacuum port 4 which also serves as a rotary shaft is connected to a vacuum pump. There will be bumps at the bottom of the vacuum suction chamber
There is a plate 5 filled with a large number of 80 μmφ gold balls 6, and when the number of gold balls on this plate is used and the number decreases, the feeding device 20
The mechanism is automatically replenished from. The upper part of the vacuum suction chamber corresponds to the bonding pedestal part, and the angle
It rotates intermittently with 45 degrees as one pitch. The upper surface is adjusted so as to be exactly parallel to the plane of the tip of the bonding tool 7 no matter where it is rotated and stopped.

As in the case of the first embodiment, the bonding stage has leads 11 matching the array pattern of the through holes of the flat plate.
One frame of TAB tape 10 is set. The leads of the TAB tape used herein were copper leads plated with gold. When the vacuum suction chamber starts to be evacuated, the gold balls on the dish are attracted to the through hole portion at the bottom of the box and temporarily fixed. Next, the vacuum suction chamber is rotated by an angle of 45 degrees corresponding to one pitch, and the gold ball is sucked and temporarily fixed to the through hole portion of the second element. Similarly, a total of 4
When the pitch is rotated, the element that temporarily fixes the gold ball is sent to the regular position of the bonding pedestal.
In this state, align with the lead of the TAB tape and heat the bonding tool to 450 ℃.
When bonding was performed for 3 seconds with a load of 3 kgf, all the gold balls temporarily fixed in the through-holes of the flat plate were transferred / bonded to the predetermined positions of the leads of the TAB tape.

Also in this example, the bonding strength between the bonded gold ball and the lead was stably secured to be 1.5 gf or more, and the TAB with bumps was used.
It was found that the function as a tape was fully satisfied.

Example 3 In Example 2, a copper lead tin-plated was used as the TAB tape. The bonding conditions were all the same as in Example 2 except that the heating temperature of the bonding tool was 300 ° C.

Also in the case of this example, the gold ball was reliably transferred and joined to the lead tip of the TAB tape. The strength of the joint was slightly lower than that of the gold-plated tape, but a stable joint strength of 0.7 gf or more was obtained.

Example 4 A hexagonal vacuum suction chamber as shown by 1 in FIG. 3 was used. The material and size of the flat plate 2 and the size and arrangement of the through holes 3 for each bump fixing element were all the same as in Example 2.

The bump supply mechanism portion is different from that of any of the previous embodiments, and the bump supply port 8 and the bump receiving port 9 in FIG. 3 and the bump returning device 21 for returning the extra bump received by the bump receiving port 9 to the supply port 8 are provided. Composed by With these devices, the bumps can be sprinkled from the bump supply port 8 on a flat plate located diagonally above the vacuum suction chamber. The sprinkled bumps 6 are temporarily fixed by being supplemented by the through holes on the flat plate, but the extra bumps after the through holes are completely covered by the bumps flow down and are accommodated in the bump receiver 9 provided below. Then, these are delivered to the bump supply port 8 again.

When a large vacuum suction chamber having a polygonal shape is used as in the case of the present embodiment, in the method of the second embodiment described above, the open state is set between the transfer of the bump and the suction of the next bump. In addition, since the vacuum leak occurs from the through hole of the flat plate, the suction force of the bump may be weakened. Since the through hole is small, if the vacuum pump has a sufficient capacity, it is possible to generate a suction force that does not hinder the work in the bump suction portion even if the through hole is partially opened. However, when the capacity of the pump is small or the drum of the vacuum suction chamber is large, the vacuum leak from the open through hole cannot be ignored. In such a case, an elastic belt such as rubber 23
It is also effective to close the through-hole in the released state by using the and pulley 22 as shown in FIG. 4, but sufficient bump suction force can also be obtained by configuring the bump supply mechanism as shown in this embodiment. It was confirmed that it could be maintained.

〔The invention's effect〕

In the method of the present invention, an ideal spherical bump is
When bonding to the tip of the lead on the tape, the bump is temporarily fixed to the through hole of the flat plate by using the vacuum suction force, so that the bump is accurately and efficiently bonded to a predetermined position on the lead. It is suitable for mass production of bumped TAB tape with excellent performance. Further, the apparatus according to the present invention is optimal for continuously and efficiently producing the above-mentioned bumped TAB tape.

[Brief description of drawings]

FIG. 1 (a) is a diagram showing the concept of a vacuum suction chamber, FIGS. 1 (b) and (c) are diagrams showing a state in which metal particles to be bumps are temporarily fixed using the vacuum suction chamber, FIG. ) Is a diagram for explaining a situation in which a vacuum suction chamber in which bumps are temporarily fixed is set on an inner lead bonding machine for TAB and transfer / bonding is performed by a bonding tool, and FIG. 2 is a concept of a more preferable embodiment of the present invention. FIG. 1A is a schematic perspective view of a vacuum suction chamber having a polygonal shape, and FIG. 1B is a view showing the vacuum suction chamber incorporated in a TAB inner lead bonding machine for integration. As a result, as an example of a bonder for bump transfer / bonding of a TAB tape with bumps, FIG. 3 is a diagram showing an example of a more preferable embodiment of the present invention similar to FIG. Vacuum of fixed part Those for Hikitsukuri is always to have a mechanism to be stably maintained, FIG. 4 is a diagram showing an example of a mechanism that can stabilize the bump suction effect by combining the second drawing. 1 ... Vacuum suction chamber, 2 ... Plate with through holes, 3 ... Through holes for temporarily fixing bumps, 4 ... Vacuum suction ports, 5 ... Plates for storing bumps, 6 ... Bumps Metal particles, 7 ... Bonding tool, 8 ... Bump supply port,
9 …… Bump receiving, 10 …… TAB tape, 11 …… TAB tape lead, 12 …… TAB tape base film, 20 ……
Bump automatic replenisher, 21 …… Bump return device, 22 …… Pulley, 23 …… Belt.

Claims (4)

[Claims] 1. A vacuum suction chamber in which a flat plate having a plurality of through holes of a predetermined size formed according to a predetermined pattern corresponding to the arrangement of bumps on the upper surface is provided at the position of the bonding cradle of the TAB bonding machine. The feature is that after the bump is sucked and temporarily fixed to the through hole portion of the upper flat plate by utilizing the suction action of the vacuum suction chamber, the bump is transferred to the tip end of the lead on the aligned TAB tape by the thermocompression action. How to transfer bumps. 2. A vacuum suction chamber in which a flat plate having a plurality of through holes of a predetermined size formed in a predetermined pattern corresponding to the arrangement of bumps on the upper surface is provided at the position of the bonding cradle of the TAB bonding machine. After temporarily removing the vacuum suction chamber from the bonding machine body, the bumps are suctioned and temporarily fixed to the through holes of the flat plate, and then the vacuum suction chamber is pulled back to a specific position above the bonding cradle of the bonding machine. A bump transfer method characterized by repeating a series of steps of fixing and then transferring a bump to a tip of a lead on an aligned TAB tape by thermocompression bonding. 3. A drum-shaped vacuum suction chamber in which a plurality of flat plates, each of which has a plurality of through holes of a predetermined size and which are formed according to a predetermined pattern corresponding to a bump position to be arranged, is arranged on a circumference. Installed so that the upper surface is at the position corresponding to the bonding pedestal of the TAB bonding machine, and until each flat plate on the circumference of the rotating vacuum suction chamber passes through the lower part and reaches the upper part. After suctioning / temporarily fixing the bumps to the through holes of the flat plate, the vacuum suction chamber further rotated and the flat plate on which the bumps were temporarily fixed reached the upward position. A bump transfer method characterized in that a series of steps up to transferring bumps by thermocompression bonding are repeated. 4. A bonding tool having a heating and pressurizing portion, a flat plate having a plurality of through holes of a predetermined size formed according to a predetermined pattern corresponding to the arrangement of bumps, and bumps on the front side of the through holes of the flat plate. A bump suction / temporary fixing portion having a vacuum suction mechanism for generating a suction force for temporarily fixing the bump, and bumps arranged on a flat plate having a through hole for the bump suction / temporary fixing portion. A bump transfer device comprising a bump supply mechanism part for temporary fixing and a position adjustment mechanism part for adjusting the lead of the TAB tape and the bump.