TW202004933A - Transfer substrate, mounting method using the same, and method of manufacturing image display device - Google Patents

Abstract

The invention provides a transfer substrate, which is used for mounting chip components arranged in a dense state at a specific interval and mounting on a wiring substrate, and is surely mounted at a specific position without the chip components being damaged. Specifically, the present invention provides a transfer substrate for holding a plurality of wafer parts having bump electrodes from the side opposite to the surface on which the bump electrodes are formed, and transferring the wafer parts to the bumps Installed on the wiring substrate of the electrode to which the electrode is connected, and includes a base substrate and an adhesive layer formed on the base substrate and holding the wafer component, the material used for the base substrate satisfies the Young's modulus of 1 GPa or more and the softening temperature Conditions of 200°C or higher and thermal conductivity of 1 W/m, the melting point of the above bonding layer is 200°C or higher, and the Leeb hardness measured by a rebound hardness tester is 50% or more and 90% of the Leeb hardness of the base substrate the following.

Description

Transfer substrate and mounting method using the same, and manufacturing method of image display device

The invention relates to a transfer substrate for transferring wafer parts, and a mounting method for mounting the wafer parts to a wiring board using the transfer substrate.

The miniaturization of semiconductor chips obtained through the advancement of microfabrication technology, or the miniaturization of LED chips obtained through the improvement of the luminous efficiency of LEDs (light emitting diodes). Therefore, many wafer parts such as semiconductor chips or LED chips can be densely formed on one wafer substrate.

In recent years, as shown in FIG. 8(a), there are densely formed wafer parts C densely formed on the wafer substrate W and rearranged on the wiring board S at specific intervals, and mounted at high speed and high accuracy ( Figure 8(c)) Use. For example, in the manufacture of micro LED displays that are receiving much attention as image display devices, it is necessary to separate millions of LED chips at a specific position on a TFT (thin-film transistor) substrate.

8(b) showing the cross section of the wafer substrate W and FIG. 8(d) showing the cross section of the wiring substrate S are shown in FIGS. 9(a) and 9(b). The electrode (not shown) of the substrate S is surely bonded to the bump electrode B of the wafer component C, and requires an accuracy of about several μm.

Therefore, various studies have been conducted on the following process, that is, the chip parts C densely formed on the wafer substrate W as shown in FIG. 8(a) are separated by a certain interval as shown in FIG. 8(c) (FIG. 8(c) ) And mounted on the wiring board S with high accuracy.

Among them, a lot of research has been conducted on laser lift-off (hereinafter referred to as LLO method) (for example, Patent Document 1).

FIG. 10 shows an example in which the wafer component C is transferred from the wafer substrate W to the wiring substrate S by the LLO method. FIG. 10( a) shows a state where the laser light L is irradiated to the wafer component C at the left end and transferred to the wiring board S. FIG. Here, the wafer component C at the left end is aligned above the specific position of the wiring board S. In addition, the wavelength of the laser light L in FIG. 10(a) is selected from a range suitable for peeling off the wafer component C from the wafer W. For example, if the wavelength absorbed by the material of the chip component C is used, the chip component C is peeled from the wafer substrate W by the gas generated due to the decomposition of the material as the temperature rises.

FIG. 10( b) shows a state where the wafer component C at the left end peeled from the wafer substrate W by the irradiation of the laser light L has been transferred to the wiring substrate S. FIG. Here, the wafer component C at the left end is transferred directly below, and therefore is arranged at a specific position on the wiring board S. Furthermore, as long as the movement distance d of the wafer component accompanying the transfer to the lower side is set to be greater than the sum of the heights of the wafer component C and the bump B, even if the wafer component C is transferred to the wiring board S The wafer substrate W is moved in the horizontal direction.

FIG. 10(c) shows the state where the laser light L is irradiated after the specific positions of the wafer component C and the wiring board S to be transferred are arranged directly under the laser light L. FIG. By this laser irradiation, the wafer component C previously transferred is spaced apart, and the next wafer component C is transferred and arranged at a specific position on the wiring board S.

In the following, a specific position of the wafer part C to be transferred and the specific position of the wiring board S (the position where the wafer part C should be installed) can be arranged at any time directly under the laser light L, and the wafer part C can be transferred as shown in FIG. 8 (c) Transfer arrangement of the wafer component C shown to the wiring board S.

However, as shown in FIGS. 10( a) to 10 (b ), in order to peel off the wafer component C from the wafer substrate W, a large energy obtained from the laser light L is applied to the wafer component C. Therefore, between the moving distance d shown in FIG. 10(b), the wafer component C also reaches the wiring board S in an accelerated state. On the other hand, the electrode portion of the wiring board S is metal, and the bump electrode B of the accelerated wafer component C is impacted when it is in contact with the metal electrode, so the wafer component C may be damaged as shown in FIG. 11. In order to alleviate such impact, it is also considered to coat the bumps of the chip component C or the electrodes of the wiring board C with a thermosetting adhesive (uncured for sealing) in advance, but the coating thickness is 5 μm or less, which is insufficient to mitigate the impact.

As described above, when directly transferring from the wafer substrate W to the wiring substrate S, the impact applied to the wafer component C is large, and thus a transfer method using another transfer substrate is popularized. Prior technical literature Patent Literature

Patent Document 1: Japanese Patent Laid-Open No. 2010-161221

[Problems to be solved by the invention]

In the transfer method using a transfer substrate, first, as shown in FIG. 12(a), the first transfer substrate 1 is closely adhered to the wafer component C of the wafer substrate W, and the wafer component C is peeled off by laser light or the like And transferred to the first transfer substrate 1. In addition, the first transfer substrate 1 has adhesiveness on the side holding the wafer component C. Here, the wafer component C is transferred in a state of being in close contact with the first transfer substrate, so it is transferred onto the first transfer substrate 1 without acceleration.

In addition, as shown in FIG. 12(b), the bump B of the wafer component C is in close contact with the first transfer substrate 1, so even if the wafer component C is transferred to the wiring board S in this state, the bump cannot be made The block B is in contact with the electrode of the wiring board S. Therefore, as shown in FIG. 12( c ), the wafer component C of the first transfer substrate 1 is transferred to the second transfer substrate 2 again. Furthermore, the second transfer substrate 2 has adhesiveness on the side holding the wafer component C.

Through the above steps, as shown in FIG. 12( d ), the second transfer substrate 2 holds the wafer component C on the side opposite to the bump B. Here, by adjusting the adhesion between the second transfer substrate 2 and the chip component C, by replacing the wafer substrate W of FIG. 10 with the transfer substrate 2 holding the chip component C as shown in FIG. 12(d), Alleviate the impact of wafer part C during transfer.

However, it is difficult to fixedly manage the adhesive force of all the wafer components C and the second transfer substrate 2. On the other hand, it is necessary to set the intensity of the laser light L so that all the wafer components are reliably peeled from the second transfer substrate 2. Therefore, it is extremely difficult to transfer from the second transfer substrate 2 to the wiring substrate S without damage to all the wafer components C. It is assumed that when the adhesive force that can be peeled off even if the laser light L is of low intensity is to be assumed, the wafer component C may naturally peel off from the second transfer substrate 2, or there may be a positional deviation during transfer.

The present invention is made in view of the above-mentioned problems, and provides a method for reliably mounting chip components arranged in a dense state at a specific interval and mounting on a wiring board at a specific position without damage to the chip components Printed circuit board and transfer substrate, installation method using the same, and method for manufacturing image display device. [Technical means to solve the problem]

In order to solve the above problem, the invention described in claim 1 is a transfer substrate for holding a plurality of wafer parts having bump electrodes from the opposite side of the surface on which the bump electrodes are formed, and transferring It is printed and mounted on a wiring substrate having electrodes connected to the bump electrodes, and includes a base substrate and an adhesive layer formed on the base substrate and holding the wafer components. The material used for the base substrate satisfies the Young's mold The temperature is 1 GPa or more, softening temperature 200°C or more, and thermal conductivity 1 W/m. The melting point of the bonding layer is 200°C or more, and the Leeb Hardness measured by a rebound hardness tester is the base The Leeb hardness of the substrate is above 50% and below 90%.

The invention described in claim 2 is the transfer substrate described in claim 1, which uses a polysiloxane resin or an acrylic resin as the adhesive layer.

The invention described in claim 3 is a mounting method that transfers the diced wafer component with bump electrodes to the first transfer substrate holding the bump electrode side, and to the holding bump After the second transfer substrate on the opposite side of the electrode, it is transferred to a wiring substrate having an electrode connected to the bump electrode and mounted, and the transfer substrate described in claim 1 or claim 2 is used as the first 2 Transfer substrate, at the stage of transferring the wafer component from the first transfer substrate to the second transfer substrate, change the interval of the wafer component to the mounting interval on the wiring substrate, from the second After the transfer substrate is heated while being pressurized on the side opposite to the surface holding the wafer component, the transfer substrate is peeled from the wafer component.

The invention described in claim 4 is a method for manufacturing an image display device, which uses an LED wafer as the wafer component, a TFT substrate as the wiring board, and uses the mounting method described in claim 3 to produce an image Display device. [Effect of invention]

By performing the mounting using the transfer substrate of the present invention, the chip components arranged in a dense state can be reliably mounted on the wiring substrate at a certain interval, and the LED chip can be mounted by using the transfer substrate and the mounting method A high-quality image display device can be obtained on the TFT substrate.

The embodiment of the present invention will be described using drawings. FIG. 1 is a second transfer substrate 2 as a transfer substrate according to an embodiment of the present invention, and shows a state in which a wafer component C is held.

As shown in FIG. 1, the second transfer substrate 2 has a structure in which an adhesive layer 21 is laminated on the base substrate 20, and the adhesive layer 21 holds the surface of the wafer component C opposite to the bump B.

The base substrate 20 is the one that dominates the mechanical and thermal characteristics of the second transfer substrate 2, and it is ideal to have excellent dimensional stability, heat resistance, and high thermal conductivity. Specifically, it is desirable to satisfy the conditions of softening temperature of 200° C. or higher, Young’s modulus of 1 GPa or higher, and thermal conductivity of 1 W/m·K or higher. As long as it satisfies this condition, it can be glass, metal, ceramic, or resin, and no translucency is required.

Next, the layer 21 holds the wafer component C. In order to relieve the impact of the step of transferring the wafer component C from the first transfer substrate 1 (details will be described later), a softer material than the base substrate 20 is used. As an index of flexibility, the Leeb hardness determined by a rebound hardness tester is preferably 50% or more and 90% or less of the base substrate 20. Moreover, it is more preferable that the melting point is 200°C or higher. As a specific main component, it can be selected from polysiloxane resin or acrylic resin.

Hereinafter, an embodiment will be described with reference to FIGS. 2 to 5, that is, in the step until the wafer components on the wafer substrate W are mounted at a certain interval and mounted on the wiring substrate S, the first configuration of FIG. 1 is used. 2 Transfer substrate 2.

FIG. 2(a) and FIG. 2(b) explain the steps of transferring the wafer component C on the wafer substrate W to the first transfer substrate 1, but it is different from FIG. 12(a) and FIG. 12( b) The prior art shown is not different. Here, the chip part C is cut to a size of 1 mm or less on one side. In the description of this embodiment, it is assumed that it is a GaN-based LED chip, but it may also be a semiconductor integrated circuit chip (IC chip) including materials such as Si.

In GaN-based LEDs, LED chips are formed on the GaN layer deposited on the sapphire substrate. Therefore, by irradiating light energy from the side of the wafer substrate W where the chip component C is not formed, the GaN layer that is overheated due to the absorption of light is decomposed to generate nitrogen gas, so that the GaN side is at the interface with the sapphire substrate Peel off. At this time, since the first transfer substrate 1 is in close contact with the wafer component C, as long as the first transfer substrate 1 is fixed, no impact force is applied to the wafer component C.

7(a) shows a plan view of the wafer component C from the wafer substrate W to the first transfer substrate 1, and the interval between the wafer components C remains dense.

Thereafter, the step of transferring the wafer component C from the first transfer substrate 1 to the second transfer substrate 2 will be described using FIG. 3. In addition, unlike the example shown in FIG. 12(c), the present invention is characterized in that at the stage of transfer from the first transfer substrate 1 to the second transfer substrate 2, the interval of the wafer parts C is enlarged and set as Same as when mounted on the wiring board S. When the difference in the arrangement of the wafer component C on the first transfer substrate 1 and the second transfer substrate is shown in a plan view, it becomes as shown in FIG. 7(b). Here, the interval of the wafer component C on the second transfer substrate 2 is the same as that of the wiring substrate S. If the wafer component C of the second transfer substrate 2 is opposed to the electrode side of the wiring substrate S, all the wafer components At the same time, it is aligned to a specific position of the wiring substrate S.

FIG. 3(a) shows a state where the surface of the first transfer substrate 1 on which the wafer component C is arranged is opposed to the adhesive layer 21 of the second transfer substrate 2 with a gap therebetween. The wafer component C is irradiated with laser light and transferred onto the second transfer substrate 2. Here, the distance between the wafer component C (non-bump surface) on the first transfer substrate 1 and the adhesive layer 21 needs to be set larger than the height of the wafer component C including the bump B in advance. The reason is that, since the distance between the wafer components C is changed by the first transfer substrate 1 and the second transfer substrate 2, it is necessary to arrange the first transfer substrate 1 and the second transfer substrate 2 facing each other Change the relative position in the plane direction.

In FIG. 3(a), the laser light L is the one that heats the bump surface side of the wafer component C and is released from the second transfer substrate 2, preferably the wavelength absorbed by the GaN constituting the wafer component C. However, as the adhesive layer between the first transfer substrate 1 and the wafer component C, as long as a material that absorbs light and releases gas can be used, the wavelength of the laser light can be selected according to the material of the adhesive layer.

FIG. 3( b) shows a state where the wafer component C that has been irradiated with the laser light L is released from the first transfer substrate 1 and is held on the second transfer substrate 2. Here, although the wafer component C is slightly spaced, it is accelerated in the space between the first transfer substrate 1 and the second transfer substrate 2 and reaches the second transfer substrate 2. Therefore, the adhesive layer 21 of the second transfer substrate 2 needs to relax the impact when the wafer component C arrives. Therefore, the condition that the chip component C does not break when it reaches the second transfer substrate 2 is searched, and as a result, as described above, it is found that the Leeb hardness obtained by the rebound hardness tester is 50% or more of the base substrate 20 90 % Below this condition. When the value exceeds 90%, there are cases where the chip parts are damaged. On the other hand, in the case of less than 50%, although there is no damage to the wafer parts, there are cases where defects occur due to viscosity or the like during heating in the subsequent steps.

FIG. 3(c) shows the following state: the specific position of the next wafer part C to be transferred and the second transfer substrate 2 (with a specific distance from the previously transferred wafer part C) is arranged directly under the laser light After adjusting the relative positions of the first transfer substrate 1 and the second transfer substrate 2, the laser light L is irradiated. By this laser irradiation, the wafer component C of the previous transfer arrangement is spaced at a specific interval and the next wafer component C is transferred and arranged on the second transfer substrate 2 (FIG. 3( d )).

In the following, the specific position of the wafer component C and the second transfer substrate 2 to be transferred can be transferred at any time directly under the laser light L, and the wafer component C can be transferred. The wafer component C is obtained on the second transfer substrate 2 of the wafer component C.

The case where the wafer component C is mounted on the wiring board S using the second transfer substrate 2 will be described using FIGS. 4 and 5.

FIG. 4( a) shows a state where the second transfer substrate 2 is arranged in a state where the wafer mounting position on the wiring substrate S arranged on the stage 3 and the wafer component C are aligned. Here, as shown in the top view shown in FIG. 7(c), the placement of the wafer components on the second transfer substrate 2 and the mounting position of the wafer components on the wiring board S can be used to arrange all the wafer components on the second transfer substrate 2 At the same time, it is aligned with the mounting position of the wiring board S.

In this state, the thermocompression joint 4 is approached from the base substrate 20 side of the second transfer substrate 2, and the heat and pressure bonding is performed as shown in FIG. 4(b), whereby the chip component C and the electrode of the wiring substrate S can be connected Install by electrical or mechanical bonding. Moreover, as long as the thermosetting adhesive is placed between the wafer component C and the wiring board S in advance, the resin sealing of the wafer component C may be performed simultaneously.

Furthermore, the heating and pressure bonding is performed by sandwiching between the stage 3 and the thermocompression joint 4, so the stage 3 may also have a heating function.

In addition, if the second transfer substrate 2 is thermally deformed during the thermal compression bonding, the mounting accuracy of the wafer component C will be lowered. Therefore, the base substrate 20 constituting the second transfer substrate 2 is required to have a softening temperature of 200° C. or higher, a Young’s modulus of 1 GPa or higher, and a thermal conductivity of 1 W/m·K or higher. In addition, with regard to the adhesive layer 21, it is necessary to avoid fusion at the time of heat and pressure bonding, and therefore, a condition of a melting point of 200°C or higher is required.

FIG. 5(c) is the state after the heating and pressure bonding of FIG. 4(b) is completed, and the state where the thermocompression joint 4 has been raised, and thereafter, FIG. 5(d) shows that the wafer part C has been peeled off the second turn The state of the printed circuit board.

In FIGS. 4 and 5, an example in which the second transfer substrate 2 is arranged on the wiring board S and the thermocompression joint 4 is lowered to perform thermal compression bonding has been described. However, as a variation of this embodiment, FIG. 6 shows an example in which the thermocompression joint 4 suction-holds the second transfer substrate 2. FIG. 6(a) shows the state in which the thermocompression joint 4 adsorbs and holds the second transfer substrate 2, and shows the state in which it has been aligned with the wiring substrate S. FIG. 6(b) shows that after the thermocompression bonding is completed By raising the thermocompression joint 4, the second transfer substrate 2 can also be peeled from the wafer component C at the same time.

As described above, in the present invention, the transfer of the wafer component C from the second transfer substrate 2 to the wiring substrate S is not performed by the LLO method, but the transfer and mounting are simultaneously performed by heat and pressure bonding. Therefore, when the wafer component C is transferred from the second transfer substrate 2 to the wiring substrate S, no impact is caused to the wafer component C. Therefore, even if the material or electrodes of the wiring board S are hard, the chip component C can be prevented from being damaged. In addition, the LLO method is used for the transfer of the wafer component C from the first transfer substrate 1 to the second transfer substrate 2. However, by appropriately selecting the adhesive layer constituting the second transfer substrate 2, the transfer to the second 2 The impact of the transfer substrate 2 during transfer prevents damage to the wafer part C.

Therefore, in applications where many chip parts are spaced apart and installed, the chip breakage rate in the step can be suppressed to extremely low, and the cost required for repair can also be greatly reduced. Therefore, the present invention is suitable as a method of manufacturing an image display device using a TFT substrate as a wiring substrate and an LED wafer as a wafer component, and is extremely suitable as a method of manufacturing a high-quality image display device using millions of LEDs.

1‧‧‧The first transfer substrate 2‧‧‧Second transfer substrate 3‧‧‧ stage 4‧‧‧Hot-pressed connector 20‧‧‧ Base substrate 21‧‧‧Next layer B‧‧‧Bump C‧‧‧chip parts CC‧‧‧ Crack d‧‧‧Moving distance L‧‧‧Laser S‧‧‧Wiring board W‧‧‧wafer substrate

FIG. 1 is a diagram showing a state where a wafer component is held by a transfer substrate (second transfer substrate) according to an embodiment of the present invention. 2 is an embodiment of the present invention, and (a) is a diagram showing a step of transferring a wafer component from a wafer substrate to a first transfer substrate, and (b) is a representation that the wafer component has been transferred to the first A picture of the state on the transfer substrate. 3 is an embodiment of the present invention, and (a) is a diagram showing a step of peeling a wafer component from a first transfer substrate, and (b) is a diagram showing a state where the wafer component has been transferred onto the transfer substrate 2 , (C) is a diagram showing the step of peeling the next wafer component from the first transfer substrate, and (d) is a diagram showing the state where the next wafer component has been transferred onto the second transfer substrate. 4 is an embodiment of the present invention, and (a) is a view showing a state in which a second transfer substrate holding wafer components has been arranged on a wiring board, and (b) is a view showing that the second transfer substrate is held A diagram of the state where the chip parts are thermocompression bonded to the wiring board. FIG. 5 is an embodiment of the present invention, and (c) is a view showing a state after the thermal compression bonding of a wafer component to a wiring board is completed, and (d) is a drawing showing that the mounting of the second transfer substrate peeled off from the wafer component is completed Figure of the state. 6 is a modified example of the embodiment of the present invention, and (a) is a state where the thermocompression joint is arranged on the wiring board with the second transfer substrate held, (b) shows the wiring board to the wiring board Diagram of the state after the thermal compression bonding of the chip parts. 7 is an embodiment of the present invention, and (a) is a plan view showing the transfer of wafer components from the wafer substrate to the first transfer substrate, (b) shows the transfer of the wafer components from the first transfer substrate to the second The plan view of the transfer of the printed circuit board, (c) is a plan view showing the mounting of the wafer component to the wiring board using the second transfer substrate. 8(a) is a plan view of a wafer substrate and wafer components, FIG. 8(b) is a cross-sectional view, FIG. 8(c) is a plan view of a wiring substrate and wafer components, and FIG. 8(d) is a cross-sectional view. FIG. 9(a) is an enlarged view of a cross-section of a wafer substrate and a wafer component, and FIG. 9(b) is an enlarged view of a cross-section where the wafer component has been mounted on a wiring substrate. FIG. 10 illustrates the steps of directly transferring the wafer parts from the wafer substrate to the wiring substrate, and (a) is a diagram showing the steps of peeling the wafer parts from the wafer substrate, and (b) shows the wafer parts have been The figure of the state transferred to the wiring board, (c) shows the step of peeling the next wafer part from the wafer substrate, (d) shows the state of the next wafer part has been transferred to the wiring substrate Picture. FIG. 11 is a diagram illustrating a case where a chip part peeled from a wafer substrate is damaged due to an impact caused by a collision with a wiring substrate. 12 is a diagram illustrating the transfer of wafer parts using a transfer substrate, and is a diagram showing the steps of transferring the wafer parts from the wafer substrate to the first transfer substrate, (b) shows that the wafer parts have been transferred Figures showing the state of being transferred to the first transfer substrate, (c) shows the steps of transferring the wafer parts from the first transfer substrate to the second transfer substrate, (d) shows the wafer parts A diagram showing the state of being transferred onto the second transfer substrate.

2‧‧‧Second transfer substrate

3‧‧‧ stage

4‧‧‧Hot-pressed connector

20‧‧‧ Base substrate

21‧‧‧Next layer

B‧‧‧Bump

C‧‧‧chip parts

S‧‧‧Wiring board

Claims (4)

A transfer substrate for holding a plurality of wafer parts having bump electrodes from the opposite side of the surface on which the bump electrodes are formed, and transferring to a wiring substrate having electrodes connected to the bump electrodes Top installer, and Including a base substrate and an adhesive layer formed on the base substrate and holding the above-mentioned wafer parts, The material used for the above base substrate satisfies the conditions of Young's modulus of 1 GPa or more, softening temperature of 200°C or more, and thermal conductivity of 1 W/m, The melting point of the adhesive layer is 200° C. or higher, and the Leeb hardness measured by a rebound hardness tester is 50% or more and 90% or less of the Leeb hardness of the base substrate. The transfer substrate according to claim 1, wherein As the adhesive layer, polysiloxane resin or acrylic resin is used. A mounting method which transfers the cut wafer parts with bump electrodes to the first transfer substrate holding the bump electrode side, and to the second transfer holding the opposite side of the bump electrode After the substrate, it is transferred to a wiring substrate having electrodes connected to the bump electrodes and mounted, and Use the transfer substrate as in claim 1 or 2 as the second transfer substrate, At the stage of transferring the wafer component from the first transfer substrate to the second transfer substrate, the interval of the wafer component is changed to the mounting interval on the wiring substrate, After heating from the side of the second transfer substrate opposite to the surface holding the wafer component while heating, the transfer substrate is peeled from the wafer component. A method of manufacturing an image display device, which uses an LED wafer as the above-mentioned wafer component and a TFT substrate as the above-mentioned wiring substrate, and The image display device is manufactured using the installation method as in claim 3.

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