TW202218537A - Manufacturing method for display device characterized by using a simple method to prevent an LED chip before bonding from a position shift while bonding an LED chip to a circuit structure - Google Patents

Abstract

The purpose of the present invention is to use a simple method to prevent an LED chip before bonding from position shifting while bonding the LED chip to a circuit structure. The manufacturing method for a display device includes the following steps: preparing a first substrate, wherein, the first substrate is provided with a driving circuit for driving an LED chip and a connecting electrode connected to the driving circuit, at each pixel; on the first substrate, forming a water-soluble adhesive layer covering the connecting electrode; for the water-soluble adhesive layer connected to the second substrate, the second substrate having a plurality of LED chips in a manner of each connecting electrode facing each LED chip; using the heat treatment to uniformly bond each connecting electrode and each LED chip; and removing the water-soluble adhesive layer by a water-washing treatment.

Description

Manufacturing method of display device

One embodiment of the present invention relates to a method of manufacturing a display device. In particular, it relates to a manufacturing method of a display device mounted with an LED (Light Emitting Diode) chip.

In recent years, as a next-generation display device, development of LED displays in which tiny LED chips are mounted on each pixel has progressed. Generally, an LED display has a structure in which a plurality of LED chips are mounted on a circuit substrate constituting a pixel array. The circuit substrate has a drive circuit for making the LED emit light at a position corresponding to each pixel. The driving circuits are respectively electrically connected to the LED chips.

The above-mentioned driving circuit and the LED chip are electrically connected via connecting electrodes. Specifically, the electrode pads arranged on the driving circuit side and the electrode pads arranged on the LED chip side are electrically connected to each other. For example, Patent Document 1 describes a technique of bonding an LED chip and a circuit board using an adhesive layer. In this technique, the LED chip and the circuit substrate are bonded by an adhesive layer. Therefore, the electrode pads on the LED chip side are provided with conductive protrusions. The protruding portion penetrates through the adhesive layer and is in contact with the electrode pad on the circuit substrate side, whereby the electrode pad on the LED chip side is electrically connected with the electrode pad on the circuit substrate side. [Prior Art Literature] [Patent Literature]

[Patent Document 1] US Patent Application Publication No. 2018/0031974

[Problems to be Solved by Invention]

As shown in the prior art, the final product in which the circuit substrate and the LED chip are bonded by the bonding layer is the bonding layer remaining between the circuit substrate and the LED chip. Since the adhesive layer is provided on the entire surface of the circuit board, the semiconductor elements constituting the circuit may be contaminated with alkali components contained in the organic substances constituting the adhesive layer, and there is a risk of malfunctioning.

One of the objects of the present invention is to bond the LED chip to the circuit board by a simple method while preventing the positional displacement of the LED chip before bonding. In addition, another object of the present invention is to remove the adhesive layer for preventing the positional displacement of the LED chip before mounting by a simple method. [Technical means to solve problems]

A method of manufacturing a display device according to an embodiment of the present invention includes the following steps: preparing a first substrate having a driver circuit for driving an LED chip in each pixel and a connection electrode connected to the driver circuit; 1. A water-soluble adhesive layer covering the connection electrodes is arranged on the substrate; a second substrate is attached to the water-soluble adhesive layer, and the second substrate has a plurality of LED chips in such a way that each connection electrode is opposite to each LED chip; by heating processing, bonding each of the above-mentioned connecting electrodes to each of the above-mentioned LED chips; and removing the above-mentioned water-soluble adhesive layer by washing with water.

Hereinafter, embodiments of the present invention will be described with reference to drawings and the like. However, the present invention can be implemented in various forms without departing from the gist of the present invention. The present invention is not to be construed as being limited to the description contents of the embodiments exemplified below. In the drawings, the width, thickness, shape, etc. of each part may be schematically shown in comparison with the actual state in order to explain more clearly. However, the drawings are only an example, and are not intended to limit the interpreter of the present invention.

In describing the embodiment of the present invention, the direction from the substrate toward the LED chip is referred to as "up", and the opposite direction is referred to as "down". Among them, the so-called "up" or "down" expression only describes the upper limit relationship of each element. For example, the expression of disposing the LED chip on the substrate also includes the case where other components are interposed between the substrate and the LED chip. Furthermore, the expression of the so-called "up" or "down" also includes the case where the elements do not overlap when viewed from above.

When describing the embodiment of the present invention, the elements having the same functions as those described above are sometimes given the same symbols or symbols such as the same symbols and English letters, and the description thereof is omitted. In addition, when it is necessary to distinguish each color of RGB (Red, Green, Blue: red, green, and blue) about a certain requirement for description, the symbol of R, G, or B is added after the symbol showing the requirement to distinguish it. However, with regard to this requirement, when it is not necessary to describe each color of RGB, only the symbol showing the requirement will be used for description.

<First Embodiment> [Manufacturing method of display device] FIG. 1 is a flow chart showing a method of manufacturing the display device 10 in one embodiment of the present invention. 2 to 10 are cross-sectional views showing a method of manufacturing the display device 10 in one embodiment of the present invention. Hereinafter, a method of manufacturing the display device 10 will be described with reference to FIG. 1 . At this time, the cross-sectional structure in each manufacturing process will be described with reference to FIGS. 2 to 10 .

First, in step S11 of FIG. 1 , a circuit substrate 100 is prepared, and the circuit substrate 100 has a driver circuit 102 for driving the LED chip and a connection electrode 103 connected to the driver circuit 102 in each pixel. The circuit substrate 100 has a plurality of regions corresponding to pixels. As shown in FIG. 2 , the circuit substrate 100 has a driving circuit 102 for driving an LED chip corresponding to each pixel on a support substrate 101 having an insulating surface. As the support substrate 101, for example, a glass substrate, a resin substrate, a ceramic substrate, or a metal substrate can be used. Each drive circuit 102 is composed of a plurality of thin film transistors (TFT: Thin Film Transistors). Each connection electrode 103 is arranged in each pixel, and is electrically connected to the driving circuit 102, respectively. The detailed structure of the circuit board 100 will be described later.

In the present embodiment, an example in which each of the driving circuits 102 and each of the connection electrodes 103 is formed on the support substrate 101 using a thin film formation technique is shown, but it is not limited to this example. For example, a substrate (a so-called active matrix substrate) in which the driving circuit 102 is formed on the support substrate 101 may be obtained as a product manufactured by a third party. In this case, it is sufficient to form the connection electrodes 103 on the obtained substrate. In this embodiment, for example, the circuit board 100 on which the flip-chip LED chip 202 (see FIG. 14 ) is mounted will be described. Among them, the LED chip 202 is not limited to the flip-chip type having two electrodes on the surface opposite to the circuit board 100 . For example, the LED chip 202 may also have an anode electrode (or cathode electrode) on the side close to the circuit substrate 100 and a cathode electrode (or anode electrode) on the far side from the circuit substrate 100 . That is, the LED chip 202 may be a face-up type LED chip having a structure in which the light-emitting layer is sandwiched between the anode electrode and the cathode electrode.

In this embodiment, an example in which nine connection electrodes 103 are arranged on the support substrate 101 is shown, but in this embodiment, a flip-chip LED chip 202 is mounted, and at least two connection electrodes are actually formed in each pixel. 103. The flip-chip LED chip has terminal electrodes connected to the N-type semiconductor and terminal electrodes connected to the P-type semiconductor. Therefore, in this embodiment, since one LED chip is arranged for each pixel, at least two connection electrodes 103 are arranged for each pixel. Here, when the above-mentioned face-up type LED chip is used as the LED chip 202 , it is sufficient to form one connection electrode 103 for each pixel on the support substrate 101 .

The connection electrode 103 is made of, for example, a conductive metal material. In the present embodiment, tin (Sn) is used as the metal material. However, it is not limited to this example, and other metal materials that can form an eutectic alloy with the terminal electrodes on the LED chip side, which will be described later, may be used. The thickness of the connection electrode 103 may be set within a range of, for example, 0.2 μm or more and 5 μm or less (preferably 1 μm or more and 3 μm or less).

Next, in step S12 of FIG. 1 , as shown in FIG. 3 , a water-soluble adhesive layer 104 covering the connection electrodes 103 is disposed on the circuit substrate 100 . The water-soluble adhesive layer 104 is a water-soluble layer composed of an adhesive material. "Adhesive" means having the property that the substance is easily attached and peeled off. That is, when other substances are brought into contact with the water-soluble adhesive layer 104, the other substances can be fixed on the water-soluble adhesive layer 104 in advance even if a weak force is applied. However, if a larger force is further applied, other substances can be easily peeled off from the water-soluble adhesive layer 104 .

In the present embodiment, as the water-soluble adhesive layer 104, a sheet-like (or film-like) member containing a resin or a flux that functions as a flux is used. In the present embodiment, an example of using a sheet-like member as the water-soluble adhesive layer 104 is shown, and the water-soluble adhesive layer 104 may also be formed by coating a liquid (or paste) material containing a resin or a flux with a fluxing effect. .

As a water-soluble member having a flux action, for example, the member described in International Publication No. 2020/116403 can be used. In addition, the water-soluble adhesive layer 104 is not limited to a member having a flux action, and a member composed of the composition described in Japanese Patent Laid-Open No. 5-209160, for example, may be used. Furthermore, as the water-soluble adhesive layer 104, for example, a water-soluble resin layer containing a polymerization inhibitor can also be used. When a polymerization inhibitor is mixed with a resin material, when hardening a resin, polymerization becomes insufficient. Since the insufficiently polymerized resin layer has adhesiveness on the surface, it can be used as the water-soluble adhesive layer 104 of this embodiment.

When a water-soluble member having a flux function is used as the water-soluble adhesive layer 104 , the flux component acts to remove the oxide film formed on the surface of the connection electrode 103 . Therefore, the surface of the connection electrode 103 can be activated, and stable bonding with the terminal electrode 203 described later can be obtained.

The thickness of the water-soluble adhesive layer 104 may be determined, for example, within a range of 5 μm or less (preferably 1 μm or more and 3 μm or less). As described below, the water-soluble adhesive layer 104 is a layer for temporarily fixing (temporarily fixing) the LED chip, and disappears by a water washing process. Therefore, in order to reduce the components of the water-soluble adhesive layer 104 remaining after the water washing treatment, it is preferably not more than 5 μm. In addition, the water-soluble adhesive layer 104 is preferably transparent. The reason for this is that, when the connection electrode 103 and the LED chip 202 are aligned to be described later, it is easy to visually observe the alignment mark placed on the circuit board 100 .

3, although the water-soluble adhesive layer 104 is only shown in contact with the upper surface of the plurality of connection electrodes 103, but this state is only an example. For example, in the case where the interval between the connection electrodes 103 is wide, or the film thickness of the water-soluble adhesive layer 104 is relatively thin, there may also be a sheet-like water-soluble adhesive layer 104 or between the connection electrodes 103 to the support substrate When the side 101 is bent, or in contact with the support substrate 101 (or the driving circuit 102 ). Furthermore, when the water-soluble adhesive layer 104 is disposed on the plurality of connection electrodes 103 , the water-soluble adhesive layer 104 can also be changed to conform to the shape of each connection electrode 103 by applying pressure to the water-soluble adhesive layer 104 .

Next, before step S13 in FIG. 1 , a carrier substrate 191 (refer to FIG. 6 ) on which a plurality of LED chips 202R are provided is prepared.

First, as shown in FIG. 4 , the element substrate 200 having a plurality of LED chips 202R emitting red light is arranged on the carrier substrate 181 . In this embodiment, as the carrier substrate 181, a sheet-like member made of silicon or acrylic is used. The carrier substrate 181 has adhesiveness. The adhesive force of the carrier substrate 181 can be adjusted by irradiation of laser light or the like. As such a carrier substrate 181, a known carrier substrate can be used.

The device substrate 200 shown in FIG. 4 is a substrate in which a plurality of LED chips 202R emitting red light are provided on a semiconductor substrate 201 . In this embodiment, although a sapphire substrate is used as the semiconductor substrate 201, it is not limited to this example. The LED chip 202R is composed of a semiconductor material including gallium nitride grown on a sapphire substrate. The combination of the material constituting the semiconductor substrate 201 and the material constituting the LED chip 202R may be appropriately determined according to the emission color.

Each LED chip 202R includes terminal electrodes 203R. The terminal electrode 203R functions as a terminal for electrically connecting the LED chip 202R and the plurality of connection electrodes 103 described above. In this embodiment, one terminal electrode 203R is shown in each LED chip 202R. However, since each LED chip 202R is a flip-chip LED in this embodiment, two electrodes are actually provided for one LED chip 202R. Terminal electrode 203R. In this embodiment, as shown in FIG. 4 , each terminal electrode 203R is attached to the surface of the carrier substrate 181 .

After the element substrate 200 is attached to the carrier substrate 181 , the semiconductor substrate 201 and each LED chip 202R are separated by irradiation with laser light (not shown). This process is called a laser ablation process. Specifically, each LED chip 202R is separated from the semiconductor substrate 201 by modifying the boundary portion between the semiconductor substrate 201 and each LED chip 202R by irradiating laser light. In this case, as the laser light, the laser light that is not absorbed by the semiconductor substrate 201 but absorbed by the LED chip 202R is selected. As the laser light, for example, ultraviolet light can be used, but it is only necessary to select a laser light of an appropriate wavelength according to the materials constituting the semiconductor substrate 201 and the LED chip 202R.

After the semiconductor substrate 201 is separated from each LED chip 202R through the above-mentioned process, as shown in FIG. In this embodiment, as the carrier substrate 191, a sheet-like member made of a silicon material is used. Before attaching the LED chips 202R to the carrier substrate 191 , preferably, the adhesive force of the carrier substrate 181 is weakened in advance by irradiating laser light or the like. By weakening the adhesive force of the carrier substrate 181 in advance, the carrier substrate 181 can be easily separated from each LED chip 202R.

After each LED chip 202R is attached to the carrier substrate 191 , the carrier substrate 181 is removed by peeling off the carrier substrate 181 . By removing the carrier substrate 181, the carrier substrate 191 provided with the plurality of LED chips 202R can be prepared.

Next, in step S13 of FIG. 1 , with respect to the water-soluble adhesive layer 104 , each connecting electrode 103 is opposite to each LED chip 202R, followed by a carrier substrate 191 having a plurality of LED chips 202R. Specifically, as shown in FIG. 6 , each of the LED chips 202R is attached to the water-soluble adhesive layer 104 in such a manner that each of the connection electrodes 103 and each of the terminal electrodes 203R face each other with the water-soluble adhesive layer 104 interposed therebetween. Thereby, each LED chip 202R can be temporarily fixed on the connection electrode 103 .

In this embodiment, to simplify the description, only one connection electrode 103 and one terminal electrode 203R are shown, but in reality, two connection electrodes 103 and two terminal electrodes 203R are provided for one LED chip 202R. However, when the above-mentioned face-up type LED chip is used as the LED chip 202R, a structure in which one connection electrode 103 is provided for each pixel may be employed.

The higher the fineness of the display device, the more the number of pixels disposed on the circuit substrate 100 is, and the smaller the size of each pixel is. When the size of each pixel becomes small, the size of the LED chip 202R arranged in each pixel also becomes small, so that the method for transporting the LED chip 202R also becomes difficult. Therefore, when the LED chip 202R is directly mounted on the connection electrode 103, there is a possibility that the position of the LED chip 202R and the position of the connection electrode 103 may become inconsistent due to slight vibration.

In this embodiment, in order to eliminate such inconvenience, a water-soluble adhesive layer 104 is provided on the connection electrode 103 . That is, in the example shown in FIG. 6, by adhering the terminal electrode 203R of the LED chip 202R to the water-soluble adhesive layer 104, the positional displacement of the LED chip 202R due to vibration can be prevented. In this case, it is not necessary to firmly adhere, as long as it is sufficient to secure the adhesive force to the extent that it can be temporarily fixed.

Next, in step S14 of FIG. 1 , as shown in FIG. 7 , the connection electrode 103 and the LED chip 202R are bonded by heat treatment by irradiating the laser light 40 . This process is a process of fusion bonding the connection electrode 103 and the terminal electrode 203R by irradiation of the laser light 40 .

As the laser light 40, the laser light that is not absorbed by the semiconductor material constituting the carrier substrate 191 and the LED chip 202R but is absorbed by the connection electrode 103 or the terminal electrode 203R is selected. In this embodiment, for example, as the laser light 40, infrared light or near-infrared light can be used. As the light source of the laser light 40, a solid-state laser such as a YAG (Yttrium Aluminum Garnate: yttrium aluminum garnate) laser or a YVO ₄ (Yttrium Vanadate: yttrium vanadate) laser can be used. Among them, the laser light 40 can be selected according to the material of the LED chip 202R and the like, and a laser light with an appropriate wavelength can be selected. For example, in the case of using a semiconductor material that absorbs laser light of shorter wavelength than infrared light, green laser light (green light) can also be used.

The alloy layer 105 composed of the eutectic alloy is formed between the connection electrode 103 and the terminal electrode 203R by the irradiation of the laser light 40 . As described above, in this embodiment, the connection electrode 103 is made of tin (Sn). On the other hand, the terminal electrode 203R is made of gold (Au). That is, in the present embodiment, as the alloy layer 105, a layer composed of a Sn-Au eutectic alloy is formed. Among them, as the connection electrode 103 and the terminal electrode 203R, other metal materials may be used as long as they are materials that can form an eutectic alloy with each other. For example, the connection electrode 103 and the terminal electrode 203R may be made of tin (Sn) in common.

The water-soluble adhesive layer 104 existing between the connection electrode 103 and the terminal electrode 203R disappears by the irradiation of the above-mentioned laser light 40 . At this time, the components of the water-soluble adhesive layer 104 may be dispersed in the eutectic alloy as carbon atoms. That is, inside the alloy layer 105 , around the alloy layer 105 , or around the connection electrode 103 , carbon may be present at a higher concentration than the connection electrode 103 and the terminal electrode 203R. For example, when the area of the connection electrode 103 is larger than that of the terminal electrode 203R, the area around the alloy layer 105 is formed in a plan view, exposing the surface of the connection electrode 103 . In this case, on the surface of the exposed connection electrode 103, carbon generated by the disappearance of the water-soluble adhesive layer 104 may exist in a higher concentration than that of the terminal electrode 203R. In this case, the carbon concentration of the exposed surface of the connection electrode 103 is higher than that of the back surface of the connection electrode 103 (the surface on the support substrate 101 side).

By forming the alloy layer 105 composed of the eutectic alloy between the connection electrode 103 and the terminal electrode 203R, the connection electrode 103 and the terminal electrode 203R are joined via the alloy layer 105 . As a result, the LED chip 202R can be firmly mounted on the connection electrode 103 . After bonding each connection electrode 103 to the terminal electrode 203R of each LED chip 202R, the carrier substrate 191 is removed to obtain the state shown in FIG. 8 . Through the above process, as shown in FIG. 8 , the red-emitting LED chip 202R can be mounted on the circuit substrate 100 .

After obtaining the state shown in FIG. 8 , steps S13 and S14 shown in FIG. 1 are repeated to sequentially mount the green-emitting LED chip 202G and the blue-emitting LED chip 202B on the circuit substrate 100 . Through these processes, the state shown in FIG. 9 can be obtained. In the state shown in FIG. 9 , the red light-emitting LED chip 202R, the green light-emitting LED chip 202G, and the blue light-emitting LED chip 202B are mounted on the circuit board 100 .

Next, in step S15 of FIG. 1 , the water-soluble adhesive layer 104 is removed by performing a water washing process. Through this process, the water-soluble adhesive layer 104 remaining between the LED chips 202 is uniformly removed. Therefore, as shown in FIG. 10 , the water-soluble adhesive layer 104 does not remain on the circuit board 100 on which the LED chips 202 are mounted. That is, according to this embodiment, the positional displacement of the LED chip before bonding can be prevented by a simple method. Furthermore, according to the present embodiment, the adhesive layer for preventing positional displacement can be removed by a simple method, and the semiconductor element constituting the circuit can be prevented from being contaminated by alkali components and the like.

[Configuration of Display Device] The configuration of the display device 10 according to one embodiment of the present invention will be described with reference to FIGS. 11 to 14 .

FIG. 11 is a plan view showing a schematic configuration of a display device 10 according to an embodiment of the present invention. As shown in FIG. 11 , the display device 10 includes a circuit board 100 , a flexible printed circuit board 160 (FPC (Flexible Printed Circuit) 160 ), and an IC (Integrated Circuit) chip 170 . The display device 10 is divided into a display area 112 , a peripheral area 114 , and a terminal area 116 .

The display area 112 is an area in which a plurality of pixels 110 including the LED chips 202 are arranged in the column direction (D1 direction) and the row direction (D2 direction). Specifically, in this embodiment, the pixel 110R including the LED chip 202R, the pixel 110G including the LED chip 202G, and the pixel 110B including the LED chip 202B are arranged. The display area 112 functions as an area for displaying an image corresponding to an image signal.

The peripheral area 114 is the area around the display area 112 . The peripheral area 114 is an area provided with driver circuits (the data driver circuit 130 and the gate driver circuit 140 shown in FIG. 14 ) for controlling the pixel circuits (the pixel circuit 120 shown in FIG. 14 ) provided in each pixel 110 .

The terminal area 116 is an area where a plurality of wirings connected to the above-mentioned driver circuit are collected. The flexible printed circuit board 160 is electrically connected to a plurality of wirings in the terminal area 116 . An image signal (data signal) or a control signal output from an external device (not shown) is input to the IC chip 170 through wiring provided on the flexible printed circuit board 160 . The IC chip 170 either performs various signal processing on the image signal, or generates control signals required for display control. The image signals and control signals output from the IC chip 170 are input to the display device 10 via the flexible printed circuit board 160 .

[Circuit Configuration of Display Device 10] FIG. 12 is a block diagram showing the circuit configuration of the display device 10 according to an embodiment of the present invention. As shown in FIG. 12 , in the display area 112 , pixel circuits 120 are provided corresponding to the respective pixels 110 . In this embodiment, a pixel circuit 120R, a pixel circuit 120G, and a pixel circuit 120B are provided corresponding to the pixel 110R, the pixel 110G, and the pixel 110B, respectively. That is, in the display area 112, the plurality of pixel circuits 120 are arranged in the column direction (D1 direction) and the row direction (D2 direction).

FIG. 13 is a circuit diagram showing the configuration of the pixel circuit 120 of the display device 10 according to one embodiment of the present invention. The pixel circuit 120 is disposed in a region surrounded by the data line 121 , the gate line 122 , the anode power line 123 and the cathode power line 124 . The pixel circuit 120 of this embodiment includes a selection transistor 126 , a drive transistor 127 , a holding capacitor 128 , and an LED 129 . The LED 129 corresponds to the LED chip 202 shown in FIG. 11 . The circuit elements other than the LED 129 in the pixel circuit 120 are equivalent to the driving circuit 102 provided on the circuit board 100 . That is, the pixel circuit 120 is completed in a state where the LED chip 202 is mounted on the circuit board 100 .

As shown in FIG. 13 , the source electrode, gate electrode and drain electrode of the select transistor 126 are respectively connected to the data line 121 , the gate line 122 , and the gate electrode of the drive transistor 127 . The source electrode, gate electrode and drain electrode of the driving transistor 127 are respectively connected to the anode power supply line 123 , the drain electrode of the selection transistor 126 and the LED 129 . The holding capacitor 128 is connected between the gate electrode and the drain electrode of the driving transistor 127 . That is, the holding capacitor 128 is connected to the drain electrode of the selection transistor 126 . The anode and cathode of the LED 129 are respectively connected to the drain electrode of the driving transistor 127 and the cathode power supply line 124 .

A grayscale signal for determining the luminous intensity of the LED 129 is supplied to the data line 121 . The gate line 122 is supplied with a gate signal of the selection transistor 126 for selecting the writing gray-scale signal. When the selection transistor 126 is turned ON, the grayscale signal is accumulated in the holding capacitor 128 . After that, when the driving transistor 127 is turned on, a driving current corresponding to the gray-scale signal flows to the driving transistor 127 . If the driving current output from the driving transistor 127 is input to the LED 129, the LED 129 emits light with a luminous intensity corresponding to the gray scale signal.

Referring to FIG. 12 again, the data driver circuit 130 is disposed at a position adjacent to the display area 112 in the row direction (D2 direction). In addition, the gate driver circuit 140 is disposed at a position adjacent to the display region 112 in the column direction (D1 direction). In this embodiment, the gate driver circuit 140 is provided on both sides of the display area 112, but it may be provided only on either side.

Either the data driver circuit 130 and the gate driver circuit 140 are disposed in the peripheral region 114 . However, the area where the data driver circuit 130 is configured is not limited to the peripheral area 114 . For example, the data driver circuit 130 may also be disposed on the flexible printed circuit substrate 160 .

The data line 121 shown in FIG. 13 extends from the data driver circuit 130 in the D2 direction, and is connected to the source electrode of the selection transistor 126 in each pixel circuit 120 . The gate line 122 extends from the gate driver circuit 140 in the D1 direction, and is connected to the gate electrode of the selection transistor 126 in each pixel circuit 120 .

A terminal portion 150 is arranged in the terminal region 116 . The terminal portion 150 is connected to the data driver circuit 130 via the connection wiring 151 . Likewise, the terminal portion 150 is connected to the gate driver circuit 140 via the connection wiring 152 . Furthermore, the terminal portion 150 is connected to the flexible printed circuit board 160 .

[Cross-sectional structure of the display device 10 ] FIG. 14 is a cross-sectional view showing the structure of the pixel 110 of the display device 10 according to an embodiment of the present invention. The pixel 110 has a driving transistor 127 disposed on the insulating substrate 11 . As the insulating substrate 11, a substrate in which an insulating layer is provided on a glass substrate or a resin substrate can be used.

The driving transistor 127 includes the semiconductor layer 12 , the gate insulating layer 13 and the gate electrode 14 . On the semiconductor layer 12 , the source electrode 16 and the drain electrode 17 are connected through the insulating layer 15 . Although not shown, the gate electrode 14 is connected to the drain electrode of the selection transistor 126 shown in FIG. 13 .

The wiring 18 is provided in the same layer as the source electrode 16 and the drain electrode 17 . The wiring 18 functions as the anode power supply line 123 shown in FIG. 13 . Therefore, the source electrode 16 and the wiring 18 are electrically connected by the connection wiring 20 provided on the planarization layer 19 . The planarization layer 19 is a transparent resin layer using resin materials such as polyimide and acrylic. The connection wiring 20 is a transparent conductive layer using a metal oxide material such as ITO. However, it is not limited to this example, and other metal materials may be used as the connection wiring 20 .

On the connection wiring 20, an insulating layer 21 made of silicon nitride or the like is provided. On the insulating layer 21, an anode electrode 22 and a cathode electrode 23 are provided. In this embodiment, the anode electrode 22 and the cathode electrode 23 are electrodes made of a light-shielding metal material. The anode electrode 22 is connected to the drain electrode 17 through openings provided in the planarization layer 19 and the insulating layer 21 .

The anode electrode 22 and the cathode electrode 23 are connected to the mounting pads 25a and 25b through the planarization layer 24, respectively. The mounting pads 25a and 25b are made of metal materials such as tantalum and tungsten, for example. Connection electrodes 103a and 103b are provided on the mounting pads 25a and 25b, respectively. The connection electrodes 103a and 103b correspond to the connection electrodes 103 shown in FIG. 1, respectively. That is, in this embodiment, electrodes made of tin (Sn) are arranged as the connection electrodes 103a and 103b.

Terminal electrodes 203a and 203b of the LED chip 202 are bonded to the connection electrodes 103a and 103b, respectively. As described above, in this embodiment, the terminal electrodes 203a and 203b are electrodes made of gold (Au). As described with reference to FIG. 7 , an alloy layer not shown (alloy layer 105 shown in FIG. 7 ) exists between the connection electrode 103 a and the terminal electrode 203 a . Here, the description will be made focusing on the connection electrode 103a and the terminal electrode 203a, but the same applies to the connection electrode 103b and the terminal electrode 203b.

The LED chip 202 is equivalent to the LED 129 in the circuit diagram shown in FIG. 13 . That is, the terminal electrode 203 a of the LED chip 202 is connected to the anode electrode 22 connected to the drain electrode 17 of the driving transistor 127 . The terminal electrode 203b of the LED chip 202 is connected to the cathode electrode 23 . The cathode electrode 23 is electrically connected to the cathode power supply line 124 shown in FIG. 13 .

The display device 10 of the present embodiment having the above-described structure has the advantage that the LED chip 202 is firmly mounted by fusion bonding by laser irradiation, and thus has a so-called high resistance to shock and the like.

<Second Embodiment> In the present embodiment, a method of manufacturing the display device 10 by a method different from that of the first embodiment will be described. Specifically, in the manufacturing method of the display device 10 of the present embodiment, a reflow process is used in the bonding of each LED chip 202 and each connection electrode 103 . In this embodiment, the part different from 1st Embodiment is demonstrated. Regarding the drawings used in the description of the present embodiment, the same components as those of the first embodiment are assigned the same reference numerals, and detailed descriptions are omitted.

15 and 16 are cross-sectional views showing a method of manufacturing a display device in a second embodiment of the present invention.

First, the circuit board 100 is prepared by the same process as that of the first embodiment, and thereafter, the carrier board 191 on which the plurality of LED chips 202R are provided is prepared. In this embodiment, the bonding member 204R is provided in advance to the terminal electrode 203R of each LED chip 202R. The joining member 204R is a member made of, for example, a low melting point metal such as solder.

In the present embodiment, as shown in FIG. 15 , the bonding member 204R is bonded to the water-soluble adhesive layer 104 . That is, each connection electrode 103 and each terminal electrode 203R are configured to face each other with the water-soluble adhesive layer 104 and the bonding member 204R interposed therebetween. Thereby, each LED chip 202R can be temporarily fixed on the connection electrode 103 .

Next, as shown in FIG. 16, the connection electrode 103 and the LED chip 202R are joined by heat processing. This process is a reflow process in which the bonding member 204R is melted by thermal annealing, and the connection electrode 103 and the terminal electrode 203R are bonded through the bonding member 204R. Thereby, the LED chip 202R can be firmly mounted on the connection electrode 103 .

As shown in the present embodiment, when the connection electrode 103 and the terminal electrode 203R are joined by a reflow process, it is preferable that the water-soluble adhesive layer 104 contains a material having a flux function. The flux component has the effect of removing oxides from the metal surface. Therefore, since the water-soluble adhesive layer 104 having the function of flux is provided between the connection electrode 103 and the bonding member 204R, the oxide formed on the surface of the connection electrode 103 or the terminal electrode 203R can be removed during the reflow process.

After the reflow process shown in FIG. 16, the process shown in FIG. 15 and FIG. 16 is repeated similarly to 1st Embodiment, and the LED chip 202G which emits green light and the LED chip 202B which emits blue light are mounted in this order. After the LED chips 202R, 202G and 202B are mounted, a water washing process is finally performed to remove the water-soluble adhesive layer 104 . Through this process, the water-soluble adhesive layer 104 remaining between the LED chips 202 is uniformly removed.

<Third Embodiment> In this embodiment, a display device 10 having a pixel having a structure different from that of the first embodiment will be described. Specifically, in the display device 10 of the present embodiment, the opening portion 30 is formed directly below the LED chip 202 in the pixel 110a. In this embodiment, the part different from 1st Embodiment is demonstrated. Regarding the drawings used in the description of the present embodiment, the same reference numerals are assigned to the same components as those of the first embodiment, and detailed descriptions are omitted.

17 is a cross-sectional view showing the structure of a pixel 110a of a display device according to a third embodiment of the present invention. As shown in FIG. 17 , in the pixel 110a of the present embodiment, an opening 30 is formed in the planarization layer 24a under the LED chip 202 . The side surface and the bottom surface of the opening 30 of the planarization layer 24 a are covered by the insulating layer 26 . As the insulating layer 26, for example, a thin film made of silicon nitride or the like can be used. The insulating layer 26 functions as a passivation layer that prevents moisture and the like from entering the inside of the circuit.

The opening 30 of the planarization layer 24a can simultaneously form a contact hole 31a for connecting the anode electrode 22 and the mounting pad 25a, and a contact hole 31b for connecting the cathode electrode 23 and the mounting pad 25b. In the inner sides of the contact holes 31 a and 31 b, openings 32 a and 32 b are also formed in the insulating layer 26 . The opening portion 32a is provided to electrically connect the anode electrode 22 and the mounting pad 25a. The opening portion 32b is provided to electrically connect the cathode electrode 23 and the mounting pad 25b. However, not limited to this example, the opening portion 32a or 32b may be provided as a whole including the contact hole 31a or 31b.

On the other hand, as shown in FIG. 17 , the insulating layer 26 inside the opening 30 remains without being etched. That is, the inside of the opening portion 30 has a structure to prevent the intrusion of moisture and the like by covering the side surfaces and the bottom surface with the insulating layer 26 .

As described above, the pixel 110a of this embodiment has the opening 30 under the LED chip 202, that is, between the connection electrode 103a and the connection electrode 103b. Thereby, a larger space than the pixels 110 in the display device 10 of the first embodiment is formed directly under the LED chip 202 . Therefore, when the water-soluble adhesive layer 104 used for mounting the LED chip 202 is removed, water can easily reach under the LED chip 202 , and the water-soluble adhesive layer 104 can be removed efficiently. Thereby, the inconvenience of the so-called water-soluble adhesive layer 104 remaining between the LED chip 202 and the circuit board 100 can be prevented.

<4th Embodiment> In the present embodiment, a method of manufacturing the display device 10 by a method different from that of the first embodiment will be described. Specifically, the manufacturing method of the display device 10 of the present embodiment uses the carrier substrate 196 made of a water-soluble adhesive sheet instead of the carrier substrate 191 . In this embodiment, the part different from 1st Embodiment is demonstrated. Regarding the drawings used in the description of the present embodiment, the same components as those of the first embodiment are assigned the same reference numerals, and detailed descriptions are omitted.

18 to 20 are cross-sectional views showing a method of manufacturing the display device 10 according to the second embodiment of the present invention.

First, the circuit board 100 is prepared by the same process as that of the first embodiment. In the first embodiment, the water-soluble adhesive layer 104 covering each of the connection electrodes 103 is disposed on the circuit board 100, but in this embodiment, the water-soluble adhesive layer 104 may not be disposed. However, it is not limited to this example, and the water-soluble adhesive layer 104 may be arranged on each of the connection electrodes 103 as in the first embodiment.

Next, by the process described using FIG. 4 in the first embodiment, the carrier substrate 181 on which the plurality of LED chips 202R are provided is prepared. After the carrier substrate 181 is prepared, as shown in FIG. 18 , the carrier substrate 181 having a plurality of LED chips 202R is then placed on the carrier substrate 196 . In this embodiment, as the carrier substrate 196, a water-soluble adhesive sheet (also referred to as a water-soluble adhesive film) is used. The water-soluble adhesive sheet is a member obtained by processing the same material as the water-soluble adhesive layer 104 described in the first embodiment into a sheet. That is, the carrier substrate 196 composed of the water-soluble adhesive sheet is soluble in water and has adhesiveness.

After each LED chip 202R is attached to the carrier substrate 196 , the carrier substrate 181 is removed by peeling off the carrier substrate 181 . By removing the carrier substrate 181, the carrier substrate 196 provided with the plurality of LED chips 202R can be prepared.

Next, as shown in FIG. 19, the carrier board 196 is arrange|positioned on the circuit board 100 so that each connection electrode 103 may oppose each LED chip 202R. Specifically, the carrier substrate 196 is arranged on the circuit board 100 so that the connection electrodes 103 and the terminal electrodes 203R face each other.

At this time, as shown in FIG. 20 , the end portion 196 a of the carrier substrate 196 is connected to the end portion of the circuit board 100 . Thereby, the position of the carrier substrate 196 can be fixed, and each LED chip 202R can be temporarily fixed on the connection electrode 103 . However, it is not limited to this example, and parts other than the end portion 196a of the carrier substrate 196 may be attached. For example, when the interval between the connection electrodes 103 is sufficiently wide, the carrier substrate 196 and the circuit substrate 100 can also be bonded in the space between the connection electrodes 103 .

After the substrate 196 is attached to the circuit board 100, the connection electrode 103 and the terminal electrode 203R are fused and joined by irradiating laser light in the same manner as in the process described using FIG. 7 in the first embodiment. Thereby, a plurality of LED chips 202R can be mounted on the circuit board 100 .

After the mounting of each LED chip 202R is completed, the carrier substrate 196 composed of the water-soluble adhesive sheet is removed by washing with water. As described above, in this embodiment, since the water-soluble carrier substrate 196 is used to transfer the plurality of LED chips 202R, the carrier substrate 196 can be removed by the water washing process. Therefore, when the carrier substrate 196 is removed, useless pressure is not applied to the circuit substrate 100 and each LED chip 202R.

After a plurality of LED chips 202R are mounted on the circuit board 100 through the above process, the processes described in FIGS. 18 to 20 are repeated in the same manner as in the first embodiment, and the green light-emitting LED chips 202G and the LED chips 202G are sequentially mounted. LED chip 202B for blue light. In this embodiment, when the LED chip 202G and the LED chip 202B are mounted on the circuit board 100, a water-soluble adhesive sheet is also used as the carrier substrate 196, so the LED chip 202G and the LED chip can be easily removed by washing with water. 202B is separated from the carrier substrate 196 .

(Variation example) In this embodiment, although the water-soluble adhesive sheet of a monomer is shown as the carrier substrate 196, it is not limited to this example. For example, a substrate in which a water-soluble adhesive sheet and a resin sheet are laminated can also be used as the carrier substrate 196 . In this case, since only one side of the carrier substrate 196 can have adhesiveness, there is an advantage that the handling of the carrier substrate 196 is easy after the carrier substrate 196 is attached to each LED chip 202 .

In the case of this modification, after the LED chips 202 are mounted on the circuit board 100, if the water rinsing process is performed, a part of the water-soluble adhesive sheet is dissolved, and thus the resin sheet is removed by stripping. Therefore, the carrier substrate 196 of the present modification can also be easily removed by washing with water.

As an embodiment of the present invention, each of the above-described embodiments can be appropriately combined and implemented as long as they do not contradict each other. Based on each embodiment, those skilled in the art can appropriately add, reduce, or change components, or perform additions, omissions, or changes in conditions, as long as the gist of the present invention is satisfied, all within the scope of the present invention. .

In addition, it should be understood that what is clear from the description of this specification, or can be easily predicted by those skilled in the art, even if there are other functions and effects different from the functions and effects obtained by the aspects of the above-mentioned embodiments, it is also a matter of course. be obtainable by the present invention.

10: Display device 11: Insulation substrate 12: Semiconductor layer 13: Gate insulating layer 14: Gate electrode 15: Insulation layer 16: Source electrode 17: Drain electrode 18: Wiring 19: Flattening layer 20: Connection wiring 21: Insulation layer 22: Anode electrode 23: Cathode electrode 24: Flattening layer 24a: Planarization layer 25a, 25b: Mounting pads 26: Insulation layer 30: Opening 31a, 31b: Contact holes 32a, 32b: Opening 40: Laser light 100: circuit substrate 101: Support substrate 102: Drive circuit 103, 103a, 103b: Connection electrodes 104: Water-soluble adhesive layer 105: Alloy layer 110, 110R, 100G, 110B: pixels 110a: Pixels 112: Display area 114: Surrounding area 116: Terminal area 120, 120R, 120G, 120B: pixel circuit 121: data line 122: gate line 123: Anode power cord 124: Cathode power cord 126: select transistor 127: drive transistor 128: Holding Capacitor 129: LED 130: Data driver circuit 140: Gate driver circuit 150: Terminal part 151, 152: Connection wiring 160: Flexible Printed Circuit Board 170: IC chip 181, 191, 196: Carrier Substrates 196a: Ends 200: Component substrate 201: Semiconductor substrate 202, 202R, 202G, 202B: LED chips 203, 203a, 203b, 203R, 203G, 203B: Terminal electrodes 204R: Joining Components D1: Direction D2: Direction S11~S15: Steps

FIG. 1 is a flowchart showing a method of manufacturing a display device in a first embodiment of the present invention. FIG. 2 is a cross-sectional view showing a method of manufacturing the display device in the first embodiment of the present invention. 3 is a cross-sectional view showing a method of manufacturing the display device according to the first embodiment of the present invention. 4 is a cross-sectional view showing a method of manufacturing the display device in the first embodiment of the present invention. 5 is a cross-sectional view showing a method of manufacturing the display device in the first embodiment of the present invention. FIG. 6 is a cross-sectional view showing a method of manufacturing the display device according to the first embodiment of the present invention. FIG. 7 is a cross-sectional view showing a method of manufacturing the display device according to the first embodiment of the present invention. 8 is a cross-sectional view showing a method of manufacturing the display device in the first embodiment of the present invention. 9 is a cross-sectional view showing a method of manufacturing the display device in the first embodiment of the present invention. 10 is a cross-sectional view showing a method of manufacturing the display device in the first embodiment of the present invention. FIG. 11 is a plan view showing a schematic configuration of the display device in the first embodiment of the present invention. FIG. 12 is a block diagram showing the circuit configuration of the display device according to the first embodiment of the present invention. FIG. 13 is a circuit diagram showing the configuration of the pixel circuit of the display device according to the first embodiment of the present invention. 14 is a cross-sectional view showing the structure of a pixel of the display device according to the first embodiment of the present invention. 15 is a cross-sectional view showing a method of manufacturing a display device in a second embodiment of the present invention. 16 is a cross-sectional view showing a method of manufacturing a display device in a second embodiment of the present invention. 17 is a cross-sectional view showing the structure of a pixel of a display device according to a third embodiment of the present invention. 18 is a cross-sectional view showing a method of manufacturing a display device in a fourth embodiment of the present invention. 19 is a cross-sectional view showing a method of manufacturing a display device in a fourth embodiment of the present invention. 20 is a cross-sectional view showing a method of manufacturing a display device in a fourth embodiment of the present invention.

S11~S15: Steps

Claims (9)

A method of manufacturing a display device, comprising the following steps: preparing a first substrate, wherein each pixel has a driver circuit for driving the LED chip and a connection electrode connected to the driver circuit; disposing a water-soluble adhesive layer covering the connecting electrodes on the first substrate; A second substrate is attached to the water-soluble adhesive layer, and the second substrate has a plurality of LED chips in a manner that each connecting electrode is opposite to each LED chip; bonding each of the above-mentioned connection electrodes to each of the above-mentioned LED chips by heat treatment; and The above-mentioned water-soluble adhesive layer is removed by washing with water. The manufacturing method of the display device as claimed in claim 1, comprising the following steps: The step of bonding each of the connection electrodes to each of the LED chips is to form an alloy layer containing the constituent materials of the connection electrodes and the terminal electrodes between the connection electrodes and the terminal electrodes of the LED chips. The method for manufacturing a display device as claimed in claim 1 or 2, wherein The above-mentioned heat treatment is performed by irradiation of laser light. The manufacturing method of the display device as claimed in claim 3, wherein The above-mentioned laser light is infrared light or near-infrared light. The method for manufacturing a display device as claimed in claim 1 or 2, wherein The above-mentioned heat treatment is a reflow treatment. As claimed in claim 1 or 2, the manufacturing method of the display device comprises the following steps: Between the above-mentioned heat treatment and the above-mentioned water washing treatment, the above-mentioned second substrate and the above-mentioned plurality of LED chips are separated. The method for manufacturing a display device as claimed in claim 1 or 2, wherein The above-mentioned water-soluble adhesive layer contains a resin or a flux having the function of a flux. The method for manufacturing a display device as claimed in claim 1 or 2, wherein At least two of the above-mentioned connecting electrodes are arranged in each pixel; and The method includes the step of forming an opening between at least two of the connection electrodes when the drive circuit is formed. The manufacturing method of the display device as claimed in claim 8, wherein The above-mentioned opening is formed by removing a part of the planarization layer.

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