KR20230058520A - Ball mounting method and ball mounting device - Google Patents

Abstract

The present invention relates to a ball mounting method for mounting conductive balls on predetermined electrodes of a wafer (substrate). It has a flux printing process (step S1 - step S4) which prints flux on an electrode by the gravure offset printing method. It has a ball mounting process (step S5 to step S8) of mounting the ball on the flux. It is possible to provide a ball mounting method capable of mounting a ball with high precision.

Description

Ball mounting method and ball mounting device

The present invention relates to a ball mounting method and a ball mounting device for mounting conductive balls on a substrate.

BACKGROUND OF THE INVENTION Bumps provided on electrodes of substrates such as silicon wafers and printed wiring boards are formed by mounting conductive balls such as solder balls on electrodes and melting these balls. In mounting the conductive ball, as described in Patent Document 1 and Patent Document 2, flux is applied to the electrode by a screen printing method, and the ball is placed on the flux. Patent Literature 1 and Patent Literature 2 disclose a ball mounting device having a screen printing unit for printing flux onto electrodes of a substrate using a mask, and a ball mounting unit for placing balls on the flux.

On the other hand, as described in Patent Literature 3 and Patent Literature 4, as a technique of forming a wiring pattern on a substrate, a technique of printing a wiring material on a substrate by a gravure offset printing method is known. Patent Document 3 discloses a gravure offset printing method in which ink serving as a wiring material is transferred from a gravure offset plate to a substrate through a blanket roll. In Patent Document 4, a method for printing a fine wiring pattern according to a gravure offset printing method to which the technique of Patent Document 3 is applied is shown. As a wiring printing method, a flexographic printing method, an inkjet printing method, a gravure printing method, a screen printing method, and the like are used depending on the wiring pattern, production speed, and the like. A gravure offset printing method is employed when importance is placed on printing precision so as to be able to print fine wiring.

Patent Document 1: Japanese Unexamined Patent Publication No. 2019-67991 Patent Document 2: Japanese Unexamined Patent Publication No. 2008-288515 Patent Document 3: Japanese Unexamined Patent Publication No. 2014-73653 Patent Document 4: International Publication No. WO2014/112557

[0003] In recent years, as electronic components are miniaturized and high-density is increased, electrodes are formed smaller and the interval (pitch) between electrodes is further shortened. However, in the screen printing method, it is impossible to print flux so that fine balls can be placed in such a narrow pitch range. This reason is that there is a limit to increasing the accuracy of printing in the screen printing method. For this reason, in the ball mounting apparatus that prints flux by the screen printing method, there has been a problem that it causes trouble in manufacturing electronic parts aimed at miniaturization and high density.

An object of the present invention is to provide a ball mounting method and a ball mounting device capable of high-precision ball mounting.

In order to achieve this object, the ball mounting method according to the present invention is a ball mounting method for mounting a conductive ball on a predetermined electrode of a substrate, a flux printing process for printing flux on the electrode by a gravure offset printing method And, a ball mounting method having a ball mounting step of mounting the ball on the flux.

A ball mounting device according to the present invention is a ball mounting device that mounts a conductive ball on a predetermined electrode of a substrate, and uses a rotary transfer body in which flux is transferred from a concave plate for gravure offset. Gravure printing flux on the electrode A ball mounting device having an offset printing unit and a ball mounting unit for mounting the balls on the flux.

In the present invention, the flux is printed with high precision on the electrodes of the substrate by the gravure offset printing method. Therefore, according to the present invention, it is possible to provide a ball mounting method and a ball mounting device capable of high-precision ball mounting.

1 is a block diagram showing the configuration of a ball loading device for implementing a ball loading method according to the present invention.
Fig. 2 is a plan view showing the configuration of the ball mounting device.
Fig. 3 is a cross-sectional view showing the structure of the ball mounting portion.
Fig. 4 is a cross-sectional view showing a part of the ball mounting portion in an enlarged manner.
5A is a cross-sectional view for explaining the operation of a gravure offset printing unit.
5B is a cross-sectional view for explaining the operation of the gravure offset printing unit.
5C is a cross-sectional view for explaining the operation of the gravure offset printing unit.
6 is a flowchart for explaining the ball mounting method according to the present invention.
Fig. 7 is an enlarged plan view showing the flux after printing.

Hereinafter, an embodiment of a ball mounting method and a ball mounting device according to the present invention will be described in detail with reference to FIGS. 1 to 7 .

(Description of ball mount device)

The ball loading device 1 shown in Fig. 1 is a device for implementing the ball loading method according to the present invention, and has mainly three functional units. These functional units include a loading & unloading unit 2 located in the center of FIG. 1, a gravure offset printing unit 3 located on the left side in FIG. 1, and a ball mounting unit 4 located on the right side in FIG. am. Further, such a ball mount device 1 is installed in a clean room or an environment equivalent to a clean room.

The load & unload unit 2 has a function of taking out a substrate without balls as a work from the work storage container 6 or storing a substrate loaded with balls in the work storage container 6, and the gravure offset printing unit 3 and a function of sending and receiving a substrate to and from the ball mounting portion 4. The substrate is, for example, a silicon wafer or a printed wiring board. The ball mounting device 1 according to this embodiment uses a silicon wafer (hereinafter simply referred to as a wafer) as a substrate. As the work storage container 6 for storing wafers, a sealed cassette called a so-called FOUP (Front Opening Unify Pod) can be used. This work storage container 6 has a wafer entrance (not shown) near the load & unload section 2. The wafer port is arranged so as to face the load & unload section 2 . In this embodiment, as shown in FIG. 2 , a first work storage container 6A accommodating a plurality of ball-unmounted wafers 8 and a second work accommodating a plurality of ball-mounted wafers 9 The storage container 6B is used.

In the ball mounting device 1 according to the present embodiment, which will be described in detail later, flux 11 (see Figs. ) is printed, and a ball 12 (see Fig. 4) is mounted on the flux 11.

As shown in Fig. 2, the load & unload unit 2 includes a transfer robot 13 made of an articulated robot and a pre-aligner 14.

The transfer robot 13 has a first transfer arm 15 that holds the wafer 8 by adsorbing the lower surface of the wafer 8, and moves the first transfer arm 15 horizontally and vertically. to convey the wafer 8.

The pre-aligner 14 is for aligning the position of a flat cutout (not shown) formed on the outer periphery of the wafer 8 to a predetermined position, and includes a rotary table 14a that rotates while placing the wafer 8 on it, and A sensor 14b for detecting a cut is provided.

(Description of the gravure offset printing part)

As shown in FIG. 2, in the gravure offset printing unit 3, the first wafer mounting table 16 installed near the boundary with the load & unloading unit 2 and the first wafer mounting table 16 are within the operating range. a first wafer transfer device 17 positioned near the first wafer transfer device 17, a work table slider 18 installed near the first wafer transfer device 17 to hold the wafer 8 in a printing position, a blanket roll 19, a scraper ( 20), a plate slider 21, a dispenser 22, and the like. The first wafer mounting table 16 has three suction pins 16a. These suction pins 16a have a function of adsorbing the lower surface of the wafer 8 to hold the wafer 8 and a function of lifting the wafer 8 .

The first wafer transfer device 17 includes a second transport arm 17a holding the wafer 8 by adsorbing the lower surface of the wafer 8, and the second transport arm 17a in two horizontal directions. An X slider 17b and a Y slider 17c are provided for movement. The two directions of the horizontal direction as used herein are the X direction, which is the direction in which the gravure offset printing unit 3 and the ball mounting unit 4 are aligned (the left and right directions in FIG. 1), and the horizontal direction orthogonal to the X direction is in the Y direction. The X slider 17b moves the Y slider 17c and the second transport arm 17a in the X direction. The Y slider 17c moves the second transport arm 17a in the Y direction.

The worktable slider 18 has a flat support surface 18a for adsorbing and holding the wafer 8 and three elevating suction pins 18b, and is configured to move in the X and Y directions. A plurality of alignment cameras 23 are installed above the worktable slider 18 to capture images of the wafer 8 on the worktable slider 18 from above. The worktable slider 18 moves in the X and Y directions so that the wafer 8 is placed at a predetermined printing position based on the image of the wafer 8 captured by the alignment camera 23.

The blanket roll 19 is a roll around which a rubber blanket 19a is wound around its outer periphery, and has a function of rotating around an axis C1 extending in the X direction and a function of moving in the Y direction, It has a function to move up and down between a lowering position and an ascending position. In this embodiment, the blanket roll 19 corresponds to the 'rotary transfer member' referred to in the present invention. The lowering position of the blanket roll 19 is a position where the blanket roll 19 contacts the wafer 8 on the worktable slider 18 and the intaglio plate 24 for gravure offset printing on the plate slider 21 described later. The elevation position is a position where the blanket roll 19 is spaced upward from the wafer 8 and the intaglio plate 24 for gravure offset printing. The blanket roll 19 according to the present embodiment is disposed between the worktable slider 18 and the plate slider 21 described later.

The scraper 20 has a blade 20a made of a strip-shaped plate extending in the X direction. The blade 20a is capable of swinging about an axis C2 extending in the X direction as a center. This scraper 20 has a function of swinging the blade 20a, and is configured to move in the Y direction integrally with the blanket roll 19. In the scraper 20 according to the present embodiment, the lower end of the blade 20a moves in one direction in the Y direction (upper side in FIG. 2) in a state in which the lower end of the blade 20a is in contact with the upper surface of the intaglio plate 24 for gravure offset printing described later, and the blade The lower end of 20a moves to the other side (lower side in Fig. 2) of the Y direction in a state of being separated from the intaglio plate 24 for gravure offset printing.

The plate slider 21 positions and holds the intaglio plate 24 for gravure offset printing (hereinafter simply referred to as the intaglio plate 24) at a predetermined position. As shown in FIG. 5A , the concave plate 24 is a flat plate formed in a flat plate shape, and concave portions 25 are formed on the upper surface thereof at positions corresponding to the plurality of electrodes 8b of the wafer 8 . The concave portion 25 is formed in the print area 24a (see FIG. 2) of the intaglio plate 24. A material forming the intaglio plate 24 is glass, synthetic resin, metal or the like.

Above the plate slider 21, a dispenser 22 for supplying the flux 11 to the intaglio plate 24 is disposed.

(Description of the ball mounting part)

As shown in FIGS. 2 and 3 , the ball mounting unit 4 has a second wafer mounting table 31 installed near the boundary with the loading and unloading unit 2 and a motion range of the second wafer mounting table 31. a second wafer transfer device 32 located inside the second wafer transfer device 32, a wafer stage 33 installed near the second wafer transfer device 32 to hold the wafer 8 in a ball mounting position, and a mask 34 for arranging the balls , a ball insert 35, a brush squeegee 36, and the like. The second wafer mounting table 31 has the same configuration as the first wafer mounting table 16 and has three elevating suction pins 31a.

The second wafer transfer device 32 has the same configuration as the first wafer transfer device 17, and includes a third transfer arm 32a, an X slider 32b, and a Y slider 32c. The third transfer arm 32a adsorbs the lower surface of the wafer 8 and holds the wafer 8 therein. The X slider 32b moves the Y slider 32c and the third transport arm 32a in the X direction. The Y slider 32c moves the third transport arm 32a in the Y direction.

As shown in FIG. 3 , the wafer stage 33 has a flat top surface 33a and a plurality of air holes 41 opening to the top surface 33a. The air hole 41 communicates a suction chamber 42 provided below the wafer stage 33 with a space above the wafer stage 33 . An air suction device (not shown) is connected to the suction chamber 42 . In addition, the wafer stage 33 has a plurality of elevating types in order to receive the ball-unmounted wafer 8 from the third transfer arm 32a or pass the ball-loaded wafer 9 to the third transfer arm 32a. A suction pin (not shown) is provided.

As shown in FIG. 3 , the ball array mask 34 is shaped to cover the wafer stage 33 from above, is disposed above the wafer stage 33, and is configured to be movable in the vertical direction. . As shown in FIG. 4 , the ball array mask 34 has a plurality of through holes 43 into which the balls 12 are inserted. The through holes 43 are provided at positions corresponding to the plurality of electrodes 8b of the wafer 8 .

The hole diameter of the through hole 43 is a hole diameter into which only one ball 12 can be inserted. The thickness of the mask 34 for arraying balls is such that the upper end of the ball 12 inserted into the through hole 43 is located near the upper surface of the mask 34 for arraying balls. On the other hand, although not shown, a ball suction device for sucking and removing excess balls 12 on the mask 34 for ball alignment can be provided in the vicinity of the mask 34 for arraying the cheeks.

The ball inserting portion 35 is formed in a tubular shape and is connected to a ball feeding device (not shown). The balls 12 are supplied into the ball insertion section 35 from above from a ball feeder. The ball 12 is a conductive ball having conductivity such as a solder ball. Further, the ball insert 35 has a function of rotating about an axis line C3 extending in the vertical direction and a function of moving in the X direction, the Y direction, and the vertical direction. A brush squeegee 36 is installed at the lower end of the ball insert 35. The brush squeegee 36 is a cylindrical brush whose outer diameter gradually increases as it goes downward.

(Description of ball mounting method)

Next, the ball loading method according to the present invention will be explained using a flow chart shown in FIG. 6 together with an explanation of the operation of the ball loading device 1 described above.

In order to carry out the ball mounting method according to the present invention, first, the wafer 8 is carried into the gravure offset printing unit 3 (step S1). In this process, first, the wafer 8 is taken out of the first work storage container 6A by the transfer robot 13 and moved to the pre-aligner 14 . After the position of the wafer 8 in the circumferential direction is corrected by the pre-aligner 14, the wafer 8 is moved from the pre-aligner 14 by the transfer robot 13 to the first wafer mounting table 16. relocate to This transfer is performed by retracting the first transfer arm 15 of the transfer robot 13 with respect to the wafer 8 while holding the wafer 8 by the three suction pins 16a.

Next, the wafer 8 is transferred from the first wafer mounting table 16 to the second transfer arm 17a of the first wafer transfer device 17, and further, the second transfer arm 17a is moved to the worktable slider. 18 is moved upward to transfer the wafer 8 to the work table slider 18. When transferring the wafer 8 from the first wafer mounting table 16 to the second transport arm 17a, the second transport arm 17a is inserted under the wafer 8, and in this state, the three suction pins 16a ) is lowered to a state where adsorption is released. When the wafer 8 is transferred from the second transfer arm 17a to the worktable slider 18, the three suction pins 18b of the worktable slider 18 are raised to lift the wafer 8 to the second transfer arm ( 17a), and in this state, the second transfer arm 17a is retracted from the wafer 8. Then, the suction pin 18b is lowered so that the wafer 8 is placed on the upper surface of the worktable slider 18 while the wafer 8 is attracted to the suction pin 18b.

In this way, after the wafer 8 is carried into the gravure offset printing unit 3, the flux 11 is supplied to the intaglio plate 24 (step S2). In this step, first, a predetermined amount of flux 11 is dropped onto the intaglio plate 24 by the dispenser 22 . Then, as shown in FIG. 5A, the blade 20a of the scraper 20 is tilted so that the lower end contacts the concave plate 24, and the scraper 20 and the blanket roll 19 in the raised position are moved in the Y direction. It is moved to one side (the direction away from the work table slider 18 in the Y direction). At this time, the blade 20a is inclined so that the downstream side of the moving direction is located below. As the blade 20a crosses the concave plate 24 in the Y direction, the concave portion 25 is filled with the flux 11 .

After the scraper 20 moves to one end in the Y direction, the blade 20a is rocked to separate the lower end from the concave plate 24, while the blanket roll 19 is placed in the lowered position to move the blade 20a to the concave plate 24. While pushing, they are moved to the other side of the Y direction (direction toward the worktable slider 18). At this time, the blanket roll 19 rotates by moving in the Y direction while contacting the indented plate 24 . Then, as shown in Fig. 5B, the flux 11 in the concave portion 25 is transferred to the blanket roll 19 according to the rotation of the blanket roll 19 (step S3).

When the blanket roll 19 rolls on the concave plate 24 to the other end in the Y direction, the flux 11 is transferred from all the concave portions 25 to the blanket 19a of the blanket roll 19. Then, the blanket roll 19 continues to move in the Y direction and rolls on the wafer 8 as shown in FIG. 5C. As the blanket roll 19 rotates on the wafer 8 while being pushed against the wafer 8 and moves toward the other side of the Y direction, the flux 11 on the blanket roll 19 moves from the blanket 19a to the wafer 8 ) is transferred to the electrode 8b (step S4). In this embodiment, the steps shown in steps S1 to S4 correspond to the "flux printing step" of the ball mounting method of the present invention.

In this way, after the flux 11 is printed on the wafer 8 in the gravure offset printing unit 3, the wafer 8 is conveyed to the ball mounting unit 4 (step S5). In this step, first, the wafer 8 on the worktable slider 18 is transferred to the first wafer mounting table 16 by the first wafer transfer device 17, and the wafer 8 is transferred to the transfer robot ( 13) to transfer from the first wafer mounting table 16 to the pre-aligner 14. In the pre-aligner 14, the wafer 8 after flux printing is rotated to correct the position of the wafer 8 in the circumferential direction. Thereafter, such a wafer 8 is transferred from the pre-aligner 14 to the ball mounting unit 4 by the transfer robot 13 (step S5).

In this transfer, the wafer 8 is transferred from the pre-aligner 14 to the second wafer mounting table 31 by the transfer robot 13, and further, the wafer 8 is transferred to the second wafer transfer device 32. ), it enters the lower part of the ball array mask 34 and is transferred to the wafer stage 33. At this time, the inside of the suction chamber 42 of the wafer stage 33 is set to a negative pressure and air is sucked through the air hole 41 so that the wafer 8 is placed on the upper surface 33a of the wafer stage 33. adsorbed After the wafer 8 is placed on the wafer stage 33 in this way, the ball array mask 34 is lowered onto the upper surface of the wafer 8 and mounted (step S6).

Next, the ball insertion part 35 is transferred onto the ball array mask 34, and the ball 12 is supplied into the ball insertion part 35. Then, by rotating the ball insert 35, the ball insert 35 is transferred in the X direction and the Y direction along the ball array mask 34 in a state where the brush squeegee 36 sweeps the ball 12. let it By operating the ball insertion part 35 in this way, as shown in FIG. 4 , the ball 12 is inserted into the through hole 43 of the mask 34 for arranging the balls (step S7). After the ball 12 is inserted into the through hole 43, it is pressed with another ball 12 from above, and is lightly embedded in the flux 11 printed on the electrode 8b to the flux 11. attached After the balls 12 are inserted into all the through holes 43, the ball insertion part 35 is moved out of the ball array mask 34, and the surplus balls remaining on the ball array mask 34 ( 12) is removed, for example, by a suction device. Then, the mask 34 for arranging the balls is lifted upward from the wafer 8 (step S8).

Thereafter, the wafer 9 whose ball mounting has been completed on the wafer stage 33 is transferred to the third transfer arm 32a of the second wafer transfer device 32 and mounted by the second wafer transfer device 32. It moves to the second wafer mounting table 31 . Then, the wafer 8 is taken out of the bowl mounting unit 4 by the transfer robot 13 (step S9) and stored in the second work storage container 6B, so that a bowl ( The loading of 12) is completed. In the wafer 9 in the second work storage container 6B, the region where the ball 12 is mounted is hatched.

In the present embodiment, steps S5 to S8 correspond to the "ball mounting step" of the ball mounting method according to the present invention.

As a result of printing the flux 11 on the electrode 8b of the wafer 8 by the ball mounting method and the ball mounting device 1 according to the present embodiment, as shown in FIG. 7, the dot diameter of the flux 11 (D) could be made into 60 micrometers or less, and the dot-to-dot pitch (L) could be made into 100 micrometers or less.

According to the ball mounting method and ball mounting device 1 according to the present embodiment, the flux 11 is printed with high precision on the electrodes 8b of the wafer 8 by the gravure offset printing method. Therefore, it is possible to provide a ball mounting method and a ball mounting device capable of high-precision ball mounting.

The intaglio plate 24 for gravure offset according to the present embodiment is a flat plate. For this reason, the flux 11 transfers from the intaglio plate 24 to the blanket roll 19 with high precision without being deformed. Therefore, according to the present embodiment, the flux 11 can be printed on the wafer 8 so that the printing accuracy is further increased. According to the present embodiment, for a workpiece having an outer diameter Ф of the electrode of the wafer 8 of 30 µm, a pitch of 50 µm, and a total pitch of 295 mm (in the effective area of a 12-inch wafer Ф), the dot diameter φ is 20 μm, the flux 11 with a printing position accuracy of ±5 μm can be printed. That is, according to the present embodiment, printing with a dot diameter of 60 μm or less and a pitch of 100 μm or less, which is the maximum accuracy of conventional screen printing, can be realized.

The gravure offset printing unit 3 according to the above-described embodiment performs gravure offset printing using the intaglio plate 24 for gravure offset printing made of a flat plate. However, the present invention is not limited to these. That is, the gravure offset printing unit 3 may be another gravure offset printing method using an intaglio instead of a flat plate. Even in this case, the process of transferring the ink material (flux 11) to the surface of the transfer member while contacting and rotating the transfer member (blanket roll 19) on the printed pattern part of the intaglio plate, not the flat plate, and avoiding such a transfer member The ball mounting method of the present invention can be implemented by a process of pressing a printed matter (for example, a wafer 8) to transfer the printed pattern to an object to be printed, and a step of mounting the ball 12 on the object to be printed. .

1: ball mount
3: gravure offset printing unit
4: ball mount
8: wafer (substrate)
8b: electrode
11: Flux
12: ball
19: blanket roll (rotating transfer body)
24: intaglio for gravure offset
S1~S4: Flux printing process
S5 to S8: Ball mounting process

Claims (4)

As a ball mounting method for mounting a conductive ball on a predetermined electrode of a substrate,
A flux printing process of printing flux on the electrode by a gravure offset printing method;
A ball mounting method characterized in that it has a ball mounting step of mounting the ball on the flux. A ball mounting device for mounting a conductive ball on a predetermined electrode of a substrate,
A gravure offset printing unit for printing flux on the electrode using a rotary transfer member in which the flux is transferred from the concave plate for gravure offset;
A ball mounting device characterized in that it has a ball mounting portion for mounting the ball on the flux. According to claim 2,
The ball mounting device, characterized in that the concave plate for the gravure offset is a flat plate. According to claim 2 or 3,
The ball mounting device, characterized in that the dot diameter of the flux printed on the electrode is 60 μm or less, and the pitch is 100 μm or less.

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