JP7319070B2 - Mounting method and image display device manufacturing method - Google Patents

Description

The present invention relates to a mounting method for mounting a chip component on a wiring board by transfer, and a method for manufacturing an image display device using this mounting method.

Advances in microfabrication technology have led to miniaturization of semiconductor chips, and improvements in the luminous efficiency of LEDs have led to miniaturization of LED chips. For this reason, a large number of chip parts such as semiconductor chips and LED chips can be densely formed on a single wafer substrate. In recent years, as shown in FIG. There is an application in which chip parts C are rearranged and mounted on a wiring board at predetermined intervals. For example, in the manufacture of a micro LED display, which is attracting attention as an image display device, it is necessary to mount several million to tens of millions of LED chips at predetermined positions on a TFT substrate with a gap between them.

Therefore, various processes for mounting the chip components C densely formed on the wafer substrate W on the wiring board at predetermined intervals with high precision have been studied.

Among them, many studies have been made on the laser lift-off method (hereinafter referred to as the LLO method) (for example, Patent Document 1).

FIG. 7 shows an example in which a chip component C is transferred from a wafer substrate W to a wiring substrate S by the LLO method. FIG. 7(a) shows a state in which the chip part C on the left end is irradiated with the laser light L and transferred to the wiring substrate S. FIG. Here, the chip component C on the left end is positioned above the wiring board S at a predetermined position. Also, the wavelength of the laser light L in FIG. For example, if a wavelength that is absorbed by the material of the chip component is used, the chip component C is peeled off from the wafer substrate W by gas generated by decomposition of the material by the laser energy.

FIG. 7(b) shows a state in which the leftmost chip component C separated from the wafer substrate W by irradiation with the laser beam L is transferred to the wiring substrate S. FIG. Here, the chip component C on the left end is arranged at a predetermined position on the wiring board S because it is transferred directly below. It should be noted that if the movement distance d directly below the chip component accompanying the transfer is made larger than the sum of the heights of the chip component C and the bumps B (which are the electrodes of the chip component C), the chip component can be attached to the wiring board S. Even if C is transferred, the wafer substrate W can be moved in the horizontal direction.

FIG. 7(c) shows a state in which the laser light L is irradiated after the predetermined positions of the chip component C to be transferred next and the wiring board S are arranged directly under the laser light L. FIG. By this laser irradiation, the next chip component C is transferred and arranged at a predetermined position on the wiring board S with a gap from the previously transferred chip component C. As shown in FIG.

After that, the chip component C to be transferred and the predetermined position of the wiring board S (the position where the chip component C is to be mounted) are placed directly under the laser beam L as needed, and the chip component C is transferred to the wiring board S. It is possible to transfer and arrange the chip component C to the .

However, in order to separate the chip component C from the wafer substrate W as shown in FIGS. Therefore, the chip component C may reach the wiring board S in an accelerated state even during the moving distance d shown in FIG. 7(b), and may be damaged by the laser energy.

As described above, since direct transfer from the wafer substrate W to the wiring substrate S causes a large impact on the chip components C, a transfer method using a separate transfer substrate is commonly used.

JP 2010-161221 A Japanese Patent Application No. 2018-061743

In the transfer method using a transfer substrate, the first transfer substrate 1 is opposed to the chip components C of the wafer substrate W as shown in FIG. The chip component C is peeled off by L or the like and transferred to the first transfer substrate 1 . The first transfer substrate 1 includes a base substrate 10 and an adhesive layer 11 provided on the side of the base substrate 10 on which the chip component C is held. Here, since the chip component C is transferred in close contact with the first transfer substrate, it is transferred onto the adhesive layer 11 of the first transfer substrate 1 without being accelerated.

By the way, as shown in FIG. 8(b), since the bumps B, which are the electrodes of the chip component C, are in close contact with the first transfer substrate 1, even if the chip component C is transferred to the wiring board from this state, the bumps B cannot be brought into contact with the electrodes of the wiring board. That is, the electrodes of the chip component C and the electrodes of the wiring substrate S cannot be connected. Therefore, it is necessary to transfer the chip components C on the first transfer substrate 1 to the second transfer substrate 2 again.

At that time, as in Patent Document 2, the chip parts C may be transferred to the second transfer substrate 2 by widening the interval between them, but the array pitch is changed as in the transfer from the wafer substrate W to the first transfer substrate 1 . There is also a method of transferring without Since the chip components C are arranged on the second transfer substrate 2 in the same manner as on the wafer substrate W by not changing the arrangement pitch, the chip components C are directly laser lifted off from the wafer substrate W to the wiring substrate. can be used. By selecting the adhesive layer used for the second transfer substrate 2, it is possible to control the energy when the chip components C are lifted off. Yield is improved.

Therefore, as a method of transferring the chip components C from the first transfer substrate 1 to the second transfer substrate 2 without changing the arrangement, if the adhesive layer 11 of the first transfer substrate 1 is heat-cured and loses its adhesiveness, it can be used. , can be easily transferred to the second transfer substrate 2 . That is, from the state in which the second transfer substrate 2 having the adhesive layer 21 arranged on the surface of the base substrate 20 is placed facing each other as shown in FIG. After the adhesive layer 11 is heated and cured by the heating and pressurizing head 3 in a state in which the chips are in close contact with each other, the heating and pressurizing head 3 moves up while holding the first transfer substrate 1, and the chip component C is transferred to the second transfer substrate 2. can be transcribed to The adhesive layer 21 of the second transfer substrate 2 has heat resistance such that it does not harden at the temperature at which the adhesive layer 11 is cured and is not thermally deteriorated, and its adhesive strength is reduced by light of a specific wavelength. Therefore, if the base substrate 20 has the characteristic of transmitting this wavelength and gas is generated at the interface between the chip component C and the adhesive layer 21 by this wavelength, a specific light as shown in FIG. The chip component C can be transferred onto the wiring board S by the laser light L of the wavelength as shown in FIG. 10(b).

Therefore, the chip components C arranged on the second transfer substrate 2 as shown in FIG. 11A are aligned using the alignment marks P2, and are sequentially transferred to predetermined positions on the wiring substrate S for mounting. As a result, it was found that misalignment is more likely to occur than in the case of aligning the wafer substrate W shown in FIG. 6A using the alignment marks PW. In addition, since the amount of positional deviation is not constant, it has been difficult to apply it to applications in which millions of LED chips are mounted at predetermined positions on a TFT substrate with a gap between them. This problem is conspicuous even when chip parts C spaced at a predetermined pitch are simultaneously irradiated with laser light L, as shown in FIG.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems. and a manufacturing method of an image display device using this mounting method.

In order to solve the above problems, the invention according to claim 1 provides a large number of chip parts having electrodes separated from each other after being formed on a wafer,
Adhered from the electrode side to a first transfer substrate held via an adhesive layer having viscoelasticity , transferred, and then adhered from the opposite side of the electrode to a second transfer substrate held via an adhesive layer. After transferring the individual chip parts to the wiring board, the chip parts are irradiated with a laser beam through the second transfer board in a state of facing each other at a predetermined position on the wiring board, and the chip parts are transferred to the wiring board. A mounting method for transferring and mounting,
A mounting method in which the inside of the second transfer substrate is divided into a plurality of areas whose ranges are defined according to the allowable accuracy at the time of mounting , and the chip parts are transferred and arranged based on the position information corrected according to each area. is.

The invention according to claim 2 is the mounting method according to claim 1,
In the mounting method, position information for each area is set using data obtained by observing chip component placement on the second transfer substrate.

The invention according to claim 3 is the mounting method according to claim 1 or claim 2, comprising a step of applying pressure when transferring a large number of chip components from the first transfer substrate to the second transfer substrate. It is the implementation method.

According to a fourth aspect of the present invention, an LED chip is used as the chip component, a TFT substrate is used as the wiring substrate, and an image display device is manufactured using the mounting method according to any one of the first to third aspects. , an image display device manufacturing method.

According to the mounting method of the present invention, when a large number of chip components formed on a wafer substrate are transferred to predetermined positions on a wiring substrate via a transfer substrate and mounted, there is no misalignment regardless of the arrangement position within the transfer substrate. Mounting that suppresses the occurrence of such defects is possible, and the use of this mounting method makes it possible to manufacture a high-quality image display device.

In the mounting method according to the embodiment of the present invention, (a) is a diagram for explaining chip component arrangement and alignment marks on a second transfer substrate, and (b) is a diagram showing an example of dividing the inside of the second transfer substrate into areas. be. FIG. 10 is an example of a list showing the relationship between correction amounts during alignment for each divided area in the mounting method according to the embodiment of the present invention. FIG. FIG. 10 is a diagram showing another example of dividing the inside of the second transfer substrate into areas in the mounting method according to the embodiment of the present invention; FIG. 10 is a diagram showing a state of observing the arrangement of chip components in the second transfer substrate in the mounting method according to the embodiment of the present invention; FIG. 10 is a diagram for explaining the relationship between the design position and the actual measurement position of the chip component layout in the second transfer substrate in the mounting method according to the embodiment of the present invention; It is a top view for demonstrating the chip component and alignment mark on a wafer substrate, (b) sectional drawing. The process of directly transferring chip parts from a wafer substrate to a wiring board will be described. FIG. 10 is a diagram showing a step of peeling off the next chip component from the substrate, (d) showing a state in which the next chip component is transferred to the wiring board; 1A illustrates a step of transferring chip components, and (a) shows a state in which a wafer substrate and a first transfer substrate face each other, and (b) a step of transferring chip components from a wafer substrate to the first transfer substrate. (c) shows a state in which the chip component has been transferred to the first transfer substrate; 1A illustrates a step of transferring a chip component, and (a) shows a state in which the first transfer substrate and the second transfer substrate face each other; (b) the chip component is transferred from the first transfer substrate to the second transfer substrate It is a figure which shows the process to transfer, and (c) shows the state by which the chip component was transcribe|transferred by the 2nd transfer board|substrate. The process of transferring the chip parts from the second transfer board to the wiring board by laser lift-off will be explained, and (a) the step of peeling off the chip parts, (b) the state in which the chip parts are transferred to the wiring board. be. It is a top view for demonstrating the chip component and alignment mark on a 2nd transfer board|substrate, (b) sectional drawing. The process of simultaneously transferring a plurality of chip parts from the second transfer board to the wiring board by laser lift-off will be described. FIG. 4 is a diagram showing; The process of transferring the chip components from the first transfer substrate to the second transfer substrate by heating and pressurizing will be described. b) A diagram showing a state in which pressure is applied to the adhesive layer of the first transfer substrate.

As a result of investigating the cause of the positional deviation, it was found that the pressure exerted when transferring the chip component C from the first transfer substrate 1 to the second transfer substrate 2 shown in FIG. 9(b) has an effect. That is, after the chip components C of the first transfer substrate 1 and the second transfer substrate 2 as shown in FIG. This is because the adhesive layer 11 and the adhesive layer 21 are deformed and a lateral force is applied to the chip component C as shown in FIG. 13(b). In particular, since the adhesive layer 11 has flexibility and thickness for alleviating the energy when the chip components C are transferred from the wafer substrate W by laser lift-off, it has a condition that it is easily deformed by pressure. ing.

By the way, in the chip component C transferred to the second transfer substrate 2 shown in FIG. Although it is zero, the one-way ratio tends to increase as it approaches the periphery.

Therefore, it is also possible to grasp the positional deviation of the chip component C transferred to the second transfer substrate 2 from the arrangement position on the second transfer substrate 2 and set the positional deviation correction for each chip component. . However, the difference in the amount of positional deviation between adjacent chip components C is slight, and even if correction is performed with detailed settings including this slight difference, the mounting accuracy is hardly affected.

Therefore, a method of dividing the chip components C into areas in which the amount of positional deviation is within a predetermined range and performing the same positional correction on the chip components C within the areas is adopted. The mounting method of the present invention employs this method for alignment, transferring and mounting the chip component C at a predetermined position on the wiring board S. FIG.

For example, for a chip component C in an area where the amount of positional deviation ΔX (ΔY) in the X direction (Y direction) is “within δX (δY) ±1 μm”, the X direction (Y direction) is “−δX (−δY )”, it is possible to suppress the amount of positional deviation in the X direction (Y direction) within the same area to “within ±1 μm”.

Therefore, if areas are divided so that the amount of positional deviation (ΔX, ΔY) is (within δXn±1 μm and within δYn±1 μm) in area An (where n is 1, 2, . . . ), area An
By correcting (-.delta.Xn, -.delta.Yn) for the chip part C inside, the amount of positional deviation in each area can be set to (within ±1 μm, within ±1 μm). That is, it can be said that all areas An are divided as common accuracy areas.

An embodiment of the present invention will be described below with reference to FIGS. 1 and 2. FIG. FIG. 1(a) is a top view of the second transfer substrate 2 onto which the chip components C are transferred. Here, the in-plane coordinate system on the second transfer substrate 2 is set by the second transfer plate alignment marks P2 provided on the second transfer substrate 2, and the coordinate position of each chip component C is also determined.

FIG. 2 is a list of design positions, measured positions (actual arrangement positions), and correction amounts of the numbered chip components C. In FIG. Here, the design position is the arrangement when the chip components C are formed on the wafer W. As shown in FIG. FIG. 1(b) shows the area division shown in FIG.

In FIG. 2, the area division is performed so that the positional deviation amount is within ±1 μm in both the X and Y directions. may be In this case, the range of one area becomes large. On the other hand, when high accuracy is required, it becomes necessary to finely divide areas.

Although the areas are divided into grids in FIG. 1(b), the areas are not limited to this, and may be divided into areas as shown in FIG.

2 can be measured from above the second transfer substrate 2 using the imaging means 5 as shown in FIG. FIG. 5 shows the relationship between the measured position and the designed position. By comparing the actually measured position of the chip component C with the designed position IC of the same chip component, the amount of positional deviation can be obtained.

Here, when obtaining the actually measured positions of the chip components C, a device equipped with the imaging means 5 is required. good. Further, when each process from the wafer substrate W to the second transfer substrate 2 is stable, the area division in the second transfer substrate 2 and the correction amount for each area do not have a large difference. Therefore, it is possible to reduce the frequency of position measurement of each chip component.

As described above, according to the mounting method of the present invention, it is possible to transfer and mount a large number of chip components onto a wiring substrate with high accuracy. Therefore, the present invention is suitable as a method of manufacturing an image display device using a TFT substrate as a wiring substrate and LED chips as chip parts, and provides high-quality image display with millions of LEDs arranged at predetermined positions. It is extremely suitable as a manufacturing method of the device.

REFERENCE SIGNS LIST 1 first transfer substrate 2 second transfer substrate 3 heating and pressurizing head 5 imaging means 10 base substrate 11 adhesive layer (thermosetting)
20 base substrate 21 adhesive layer (photocurable)
B Bump (electrodes for chip parts)
C Chip component IC Chip component design position L Laser beam P2 Second transfer plate alignment mark PW Wafer substrate alignment mark S Wiring substrate W Wafer substrate

Claims (4)

a number of chip components having electrodes separated from each other after they are formed on a wafer;
After being brought into close contact with the first transfer substrate held from the electrode side via an adhesive layer having viscoelasticity and transferred,
Adhered to a second transfer substrate held via an adhesive layer from the opposite side of the electrode and transferred,
In a state in which individual chip parts are arranged facing each other at predetermined positions on a wiring board, the chip parts are irradiated with a laser beam through the second transfer board, and the chip parts are transferred and arranged on the wiring board and mounted. a method,
A mounting method in which the inside of the second transfer substrate is divided into a plurality of areas whose ranges are defined according to the allowable accuracy at the time of mounting , and the chip parts are transferred and arranged based on the position information corrected according to each area. . The mounting method according to claim 1,
A mounting method for setting position information for each of the areas using data obtained by observing chip component placement on the second transfer substrate. 3. The mounting method according to claim 1, further comprising the step of applying pressure when transferring a large number of chip components from the first transfer substrate to the second transfer substrate. Using an LED chip as the chip component and a TFT substrate as the wiring substrate,
A method for manufacturing an image display device, wherein the mounting method according to any one of claims 1 to 3 is used to manufacture an image display device.