JPH1022345A - Mounting method for work - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for mounting a work taking a level difference on an upper surface of a substrate into consideration. SOLUTION: A level difference h on an upper surface of a substrate 11 resulting from surface waviness is measured with use of a measurement means. When the level difference h is larger than a height H of bumps 28, all the bumps 28 can be made to have an identical level of height by pushing a flattening tool against the bumps 28. Next adhesive or bond 29 is coated on the substrate 11, a chip 21 is attracted to a die collect 22 by vacuum, and bumps 30 of the chip 21 are placed and mounted on the bumps 28 of the substrate 11. When the level difference h is smaller than the height h of the bumps 28, the bumps cannot be made to have an identical level of height even by flattening all the bumps 28. In this case, the mounting of the chip 21 is stopped and the substrate 11 is discharged out from the production line as a faulty part.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a work mounting method for mounting a work on a substrate via bumps.

[0002]

2. Description of the Related Art FIG. 11 is a side view showing a state where a chip is mounted on a conventional substrate. The electrode 2 is formed on the upper surface of the substrate 1. A bump 4 is provided on the lower surface of the chip 3 as a work.
Are formed. The chip 3 is mounted on the floating mechanism 6 of the pressure head 5 by vacuum suction and held, and the bump 4 is pressed against the electrode 2 to mount the chip 3 on the substrate 1.

[0003]

The substrate 1 is formed in a plate shape from glass epoxy resin, ceramics, or the like, but the top surface of the substrate 1 tends to have a height difference h due to undulation. Therefore, according to the conventional method, when the height difference h is small, the floating mechanism 6 swings and the tip 3
Is absorbed by making the upper surface of the substrate 1 flat, and all the bumps 4 can land on the electrode 2. However, when the height difference h increases, the floating mechanism 6
In this case, the height difference h cannot be completely absorbed, and as a result, all the bumps 4 cannot land on the electrode 2 (see the second and third bumps 4 from the left side in FIG. 11). There was a problem that became.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a work mounting method capable of mounting a work in response to a height difference due to a large undulation of the upper surface of a substrate.

[0005]

SUMMARY OF THE INVENTION The present invention comprises a step of measuring a height difference of an upper surface of a substrate by a measuring means, a step of comparing the measured height difference with a height of a bump by a control unit, A step of forming bumps on the individual electrodes, a step of pressing a flattening tool against these bumps to make the heights of the upper surfaces of these bumps the same level, and a step of attaching electrodes formed on the lower surface of the work to the bumps. The step of landing and mounting the work on the substrate constituted the method of mounting the work.

[0006]

According to the present invention, when the height difference of the upper surface of the substrate measured by the measuring means is smaller than the height of the bumps, a flattening tool is pressed against the bumps and the upper surface of all the bumps is pressed. The height is set to the same level, and all the electrodes of the work are landed on these bumps and mounted. If the height difference is larger than the height of the bumps, the electrodes of the work cannot land on the bumps even if the work is mounted on the substrate.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a front view of a work mounting apparatus according to a first embodiment of the present invention. 2, 3, 4, 5, 6, and 7 are mounting process diagrams of the work, and show a method of mounting the work in the order of processes. FIG. 8 is an explanatory diagram when the substrate is defective.

First, an overall configuration of a work mounting apparatus will be described with reference to FIG. The substrate 11 is pitch-fed to the right along the transport path 12. PSD above the transport path 12
A movable table 14 having a height measuring means 13 such as
A wire bonder 17 including a horn 15 and a capillary tool 16 and a flattening unit 1 including a flattening tool 18
9, a dispenser 20 as a bond applying means, a die bonder 23 having a die collet 22 for vacuum-sucking the chip 21, and the like are arranged in order. Reference numeral 25 denotes a computer, which is connected to each of the above units. As shown in FIG. 2, a large number of electrodes 24 are formed on the upper surface of the substrate 11. The height difference h is generated on the upper surface of the substrate 11 by undulation.

Next, a method of mounting a chip will be described with reference to FIGS. First, as shown in FIG.
Is stopped immediately below the measuring means 13. Therefore, while horizontally moving the measuring means 13, the upper surface of the substrate 11 is irradiated with the laser beam R and the reflected light is received to measure the height of the upper surface of the substrate 11. The measured value is input to the computer 25. Then, the computer 25 calculates the maximum height difference h of the upper surface of the substrate 11,
The height H of the bump formed in the next step is compared with this height difference h. When the height difference h is smaller than the height H of the bumps, the following operation is continued. However, when the height difference h is larger than the height H of the bumps, the following operation is stopped. Excluded from the line.

In the process shown in FIG. 2, the height difference h is smaller than the height H of the bump (FIG. 3). If the board 11 is determined to be non-defective, the board 11 is sent below the next wire bonder 17, The bumps 28 are sequentially formed on the electrodes 24 of the substrate 11 by wire bonding means.

FIG. 3 shows this state. The torch 26 is made to approach the lower end of the wire 27 led out from the lower end of the capillary tool 16, and a high voltage is applied to the torch 26 to lower the lower end of the wire 27. A ball 28 'is formed at the lower end of the wire 27 by generating an electrical spark between the wire 27 and the wire. Then, the ball 28 ′ is bonded to the electrode 24 by causing the capillary tool 16 to perform a descending / elevating operation to form a bump 28. Since the height H of the bump 28 is substantially constant and is previously input as a known value into the memory of the computer 25, the computer 25 can compare the height H with the above-described height difference h. Next, the substrate 11 is sent directly below the flattening means 19. Then, the flattening tool 18 is lowered and its flat lower surface is pressed against all the bumps 28 (see the flattening tool 18 shown by a dashed line in FIG. 4), and the height of all the bumps 28 becomes the same level L. (FIG. 5).

FIG. 8 shows a case where the height difference h is larger than the height H of the bump 28. In this case, since the planarization tool 18 cannot land on all the bumps 28, the heights of all the bumps 28 cannot be set to the same level L. It will not be possible to land on 28. Therefore, such a substrate 11 is removed from the line as described above as a defective product. In FIG. 8, the flattening tool 18 cannot land on the second bump 28 from the left and cannot flatten the bump 28.

The substrate 11 having the upper surface of the bump 28 flattened is sent directly below the dispenser 20. Then, the bond 29 is discharged from the dispenser 20 (FIG. 6). The bond 29 is applied to the upper surface of the substrate 11 so as to cover all the bumps 28. Next, the substrate 11 is sent to a position directly below the die bonder 23, and the chip 21 held by vacuum suction on the die collet 22 is mounted (FIG. 7). Chip 2
1 has a bump 30 protruding from the lower surface thereof.
Are landed on the bumps 28 on the substrate 11 and mounted. Next, the substrate 11 is sent to a heating furnace (not shown),
The entire process is completed by heating and curing 9.
As a method of curing the bond 29, a heater for heating may be attached to the die collet 22 or the substrate support block (not shown), and mounting and curing may be performed at once by the die bonder 23.

FIGS. 9 and 10 are process diagrams for mounting a workpiece according to the second embodiment of the present invention. FIG. 9 and FIG.
This corresponds to the step of FIG. 7 of the first embodiment. In the second embodiment, instead of applying the bond 29 by the dispenser 20 in the process of FIG. 6 of the first embodiment,
An anisotropic conductive tape (hereinafter, referred to as ACF) 32 is stuck on the flattened bumps 28. Then, as shown in FIG. 9, the electrodes 33 of the chip 21 are connected to the bumps 28 of the substrate 11.
The chip 21 is mounted on the substrate 11 while crushing the ACF 32 with the die collet 22 while applying heat by a heating means (not shown).
Is pressed against the bumps 28 on the substrate 11 (FIG. 10). Then, the ACF 32 is fluidized by heat and then hardened, and the chip 21 is bonded to the substrate 11. No bumps are formed on the electrodes 33 of the chip 21.

The present invention is not limited to the above embodiment. For example, the measuring means is incorporated in a wire bonder,
The height difference of the upper surface of the substrate may be measured immediately before the formation of the bump, or the bump may be formed by a screen printing method using cream solder, a construction method using conductive balls, or a plating method. .

[0016]

According to the present invention, prior to mounting a work such as a chip on a substrate, the height difference of the upper surface of the substrate is measured by a measuring means. If the height difference is smaller than the height of the bump, the bump is measured. Press the flattening tool to make the top surface of all the bumps the same level, then mount the work on the board.If the height difference is larger than the height of the bump, mount the work on the board. Also, since the electrodes of the work cannot land on the bumps, they are treated as defectives, so that only non-defective products can be produced, and wasteful production of defective products can be eliminated.

[Brief description of the drawings]

FIG. 1 is a front view of a work mounting apparatus according to a first embodiment of the present invention.

FIG. 2 is a mounting process diagram of a work according to the first embodiment of the present invention;

FIG. 3 is a mounting process diagram of the work according to the first embodiment of the present invention;

FIG. 4 is a process diagram for mounting a workpiece according to the first embodiment of the present invention;

FIG. 5 is a process diagram of mounting a workpiece according to the first embodiment of the present invention;

FIG. 6 is a mounting process diagram of the workpiece according to the first embodiment of the present invention.

FIG. 7 is a process diagram of mounting a workpiece according to the first embodiment of the present invention;

FIG. 8 is an explanatory diagram when the substrate according to the first embodiment of the present invention is a defective product;

FIG. 9 is a process diagram of mounting a work according to the second embodiment of the present invention.

FIG. 10 is a mounting process diagram of a work according to the second embodiment of the present invention.

FIG. 11 is a side view showing a state where a chip is mounted on a conventional substrate.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Substrate 13 Measuring means 17 Wire bonder 18 Flattening tool 19 Flattening means 20 Dispenser 21 Work 23 Die bonder 24 Electrode 28 Bump 29 Bond 30 Bump 32 ACF 33 Electrode

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical indication location H01L 21/92 604T

Claims (1)

[Claims] A step of measuring a height difference of an upper surface of a substrate by a measuring unit; a step of comparing the measured height difference with a height of a bump by a control unit; and forming a bump on a plurality of electrodes of the substrate. And pressing a flattening tool on these bumps to make the heights of the upper surfaces of these bumps the same level, and landing the electrodes formed on the lower surface of the work on the bumps to transfer the work to the substrate. A mounting method of a work, comprising: mounting.