JP2022039212A - Manufacturing method for display device - Google Patents

Abstract

To bond an LED chip to a circuit board while preventing the displacement of the LED chip before bonding by a simple method.SOLUTION: A manufacturing method for a display device includes preparing a first substrate including a driving circuit for driving an LED chip and a connection electrode connected to the driving circuit in each pixel, forming a water-soluble adhesive layer covering the connection electrode on the first substrate, attaching a second substrate including a plurality of LED chips to the water-soluble adhesive layer so that each connection electrode and each LED chip face each other, boding each connection electrode and each LED chip collectively by heat treatment, and removing the water-soluble adhesive layer by water-washing treatment.SELECTED DRAWING: Figure 1

Description

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

In recent years, as a next-generation display device, the development of an LED display in which a minute LED chip is mounted on each pixel has been promoted. Usually, an LED display has a structure in which a plurality of LED chips are mounted on a circuit board constituting a pixel array. The circuit board has a drive circuit for causing the LED to emit light at a position corresponding to each pixel. Each of these drive circuits is electrically connected to each LED chip.

The drive circuit and the LED chip described above are electrically connected via a connection electrode. Specifically, the electrode pad provided on the drive circuit side and the electrode pad provided on the LED chip side are electrically connected to each other. For example, Patent Document 1 describes a technique for joining an LED chip and a circuit board using an adhesive layer. In this technique, the LED chip and the circuit board are bonded by an adhesive layer. Therefore, the electrode pad on the LED chip side is provided with a conductive protrusion. When this protrusion penetrates the adhesive layer and comes into contact with the electrode pad on the circuit board side, the electrode pad on the LED chip side and the electrode pad on the circuit board side are electrically connected.

U.S. Patent Application Publication No. 2018/0031974

In the final product manufactured by the technique described in Patent Document 1, an adhesive layer remains between the circuit board and the LED chip. Since the adhesive layer is provided on the entire surface of the circuit board, the semiconductor element constituting the circuit may be contaminated with the alkaline component contained in the organic substance or the like constituting the adhesive layer, which may cause a malfunction.

One of the problems of the present invention is to join the LED chip to the circuit board by a simple method while preventing the position shift of the LED chip before joining. Another object of the present invention is to remove the adhesive layer used for preventing the misalignment of the LED chip before mounting by a simple method.

In the method of manufacturing a display device according to an embodiment of the present invention, a first substrate having a drive circuit for driving an LED chip and a connection electrode connected to the drive circuit is prepared for each pixel, and the first substrate is on the first substrate. A water-soluble adhesive layer covering the connection electrode is arranged therein, and a second substrate having a plurality of LED chips is adhered to the water-soluble adhesive layer so that each connection electrode and each LED chip face each other, and heat treatment is performed. This includes joining the connection electrodes to the LED chips and removing the water-soluble adhesive layer by washing with water.

It is a flowchart which shows the manufacturing method of the display device in 1st Embodiment of this invention. It is sectional drawing which shows the manufacturing method of the display device in 1st Embodiment of this invention. It is sectional drawing which shows the manufacturing method of the display device in 1st Embodiment of this invention. It is sectional drawing which shows the manufacturing method of the display device in 1st Embodiment of this invention. It is sectional drawing which shows the manufacturing method of the display device in 1st Embodiment of this invention. It is sectional drawing which shows the manufacturing method of the display device in 1st Embodiment of this invention. It is sectional drawing which shows the manufacturing method of the display device in 1st Embodiment of this invention. It is sectional drawing which shows the manufacturing method of the display device in 1st Embodiment of this invention. It is sectional drawing which shows the manufacturing method of the display device in 1st Embodiment of this invention. It is sectional drawing which shows the manufacturing method of the display device in 1st Embodiment of this invention. It is a top view which shows the schematic structure of the display device in 1st Embodiment of this invention. It is a block diagram which shows the circuit structure of the display device which concerns on 1st Embodiment of this invention. It is a circuit diagram which shows the structure of the pixel circuit of the display device which concerns on 1st Embodiment of this invention. It is sectional drawing which shows the structure of the pixel of the display device which concerns on 1st Embodiment of this invention. It is sectional drawing which shows the manufacturing method of the display device in 2nd Embodiment of this invention. It is sectional drawing which shows the manufacturing method of the display device in 2nd Embodiment of this invention. It is sectional drawing which shows the structure of the pixel of the display device which concerns on 3rd Embodiment of this invention. It is sectional drawing which shows the manufacturing method of the display device in 4th Embodiment of this invention. It is sectional drawing which shows the manufacturing method of the display device in 4th Embodiment of this invention. It is sectional drawing which shows the manufacturing method of the display device in 4th Embodiment of this invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings and the like. However, the present invention can be carried out in various embodiments without departing from the gist thereof. The present invention is not construed as being limited to the description of the embodiments exemplified below. In order to clarify the explanation, the drawings may schematically represent the width, thickness, shape, etc. of each part as compared with the actual embodiment. However, the drawings are merely examples and do not limit the interpretation of the present invention.

In the description of the embodiment of the present invention, the direction from the substrate to the LED chip is referred to as "up", and the opposite direction is referred to as "down". However, the expressions "above" or "below" merely explain the upper limit of each element. For example, the expression that the LED chip is arranged on the substrate also includes the case where another member is interposed between the substrate and the LED chip. Further, the expression "above" or "below" includes not only the case where the elements are superimposed in the plan view but also the case where the elements are not superimposed.

When the embodiment of the present invention is described, the same reference numerals or the same reference numerals with symbols such as alphabets may be added to the elements having the same functions as the elements already described, and the description thereof may be omitted. When it is necessary to explain a certain element separately for each color of RGB, a symbol of R, G or B is added after the symbol indicating the element to distinguish them. However, when it is not necessary to explain the element separately for each color of RGB, only the reference numeral indicating the element will be described.

<First Embodiment>
[Manufacturing method of display device]
FIG. 1 is a flowchart showing a manufacturing method of the display device 10 according to the embodiment of the present invention. 2 to 10 are cross-sectional views showing a method of manufacturing the display device 10 according to the embodiment of the present invention. Hereinafter, a method of manufacturing the display device 10 will be described with reference to FIG. At that 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 board 100 having a drive circuit 102 for driving an LED chip and a connection electrode 103 connected to the drive circuit 102 is prepared for each pixel. The circuit board 100 has a region corresponding to a plurality of pixels. As shown in FIG. 2, the circuit board 100 has a drive circuit 102 that drives an LED chip corresponding to each pixel on a support board 101 having an insulating surface. As the support substrate 101, for example, a glass substrate, a resin substrate, a ceramics substrate, or a metal substrate can be used. Each drive circuit 102 is composed of a plurality of thin film transistors (TFTs). Each connection electrode 103 is arranged in each pixel and is connected to the drive circuit 102. The detailed structure of the circuit board 100 will be described later.

In the present embodiment, an example in which each drive circuit 102 and each connection electrode 103 are formed on the support substrate 101 by using the thin film forming technique is shown, but the present invention is not limited to this example. For example, a substrate (so-called active matrix substrate) in which the drive circuit 102 is formed on the support substrate 101 may be obtained from a third party as an off-the-shelf product. In this case, the connection electrode 103 may be formed on the acquired substrate. Further, in the present embodiment, for example, a circuit board 100 on which a flip-chip type LED chip 202 (see FIG. 14) is mounted will be described. However, the LED chip 202 is not limited to the flip chip type example having two electrodes on the surface facing the circuit board 100. For example, the LED chip 202 may have a structure having an anode electrode (or cathode electrode) on the side close to the circuit board 100 and a cathode electrode (or cathode electrode) on the side far from the circuit board 100. That is, the LED chip 202 may be a face-up type LED chip having a structure in which a light emitting layer between an anode electrode and a cathode electrode is sandwiched.

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

The connection electrode 103 is made of, for example, a conductive metal material. In this embodiment, tin (Sn) is used as the metal material. However, the present invention is not limited to this example, and other metal materials capable of forming a eutectic alloy with the terminal electrode on the LED chip side, which will be described later, can be used. The thickness of the connection electrode 103 may be determined within the range of 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 electrode 103 is arranged on the circuit board 100. The water-soluble adhesive layer 104 is a water-soluble layer made of a material having adhesiveness. By "having adhesiveness" is meant having the property of facilitating the adhesion and exfoliation of substances. That is, when another substance is brought into contact with the water-soluble adhesive layer 104, the other substance can be fixed on the water-soluble adhesive layer 104 even if a weak force is applied. However, when a larger force is 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 agent having a flux action is used. In the present embodiment, an example of using a sheet-shaped member is shown, but a liquid (or paste-like) material containing a resin or a flux agent having a flux action may be applied to form the water-soluble adhesive layer 104. good.

As the water-soluble member having a flux action, for example, the member described in International Publication No. 2020/116403 can be used. Further, the water-soluble adhesive layer 104 is not limited to a member having a flux action, and for example, a member composed of the composition described in JP-A-5-209160 may be used. Further, as the water-soluble adhesive layer 104, for example, a water-soluble resin layer containing a polymerization inhibitor may be used. When a polymerization inhibitor is mixed with the resin material, the polymerization becomes insufficient when the resin is cured. Since the resin layer with insufficient polymerization has adhesiveness on the surface, it can be used as the water-soluble adhesive layer 104 of the present embodiment.

When a water-soluble member having a flux action is used as the water-soluble adhesive layer 104, the flux component has an action of removing 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, which will be described later, can be obtained.

The thickness of the water-soluble adhesive layer 104 may be determined, for example, within the range of 5 μm or less (preferably 1 μm or more and 3 μm or less). As will be described later, the water-soluble adhesive layer 104 is a layer for temporarily fixing the LED chip, and disappears by washing with water. Therefore, in order to reduce the components of the water-soluble adhesive layer 104 remaining after the washing treatment, it is desirable that the thickness does not exceed 5 μm. Further, the water-soluble adhesive layer 104 is preferably transparent. This is because it is easy to visually recognize the alignment marker arranged on the circuit board 100 when the connection electrode 103 and the LED chip 202, which will be described later, are aligned.

Note that FIG. 3 shows an embodiment in which the water-soluble adhesive layer 104 is in contact with only the upper surfaces of the plurality of connection electrodes 103, but such an embodiment is only an example. For example, when the distance between the connection electrodes 103 is wide, or when the film thickness of the water-soluble adhesive layer 104 is thin, the sheet-like water-soluble adhesive layer 104 bends toward the support substrate 101 between the connection electrodes 103. However, it may come into contact with the support board 101 (or the drive circuit 102). Further, when the water-soluble adhesive layer 104 is arranged on the plurality of connection electrodes 103, the water-soluble adhesive layer 104 is deformed so as to follow the shape of each connection electrode 103 by applying pressure to the water-soluble adhesive layer 104. You may let me.

Next, prior to step S13 in FIG. 1, a carrier substrate 191 (see FIG. 6) provided with a plurality of LED chips 202R is prepared.

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

The element substrate 200 shown in FIG. 4 is a substrate on which a plurality of LED chips 202R that emit red light are provided on the semiconductor substrate 201. In the present embodiment, the sapphire substrate is used as the semiconductor substrate 201, but the present invention is not limited to this example. The LED chip 202R is made of a semiconductor material containing 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 a terminal electrode 203R. The terminal electrode 203R functions as a terminal for electrically connecting the LED chip 202R and the above-mentioned plurality of connection electrodes 103. In this embodiment, in order to illustrate a flip-chip type LED, actually, two terminal electrodes 203R are provided for one LED chip 202R. In this embodiment, as shown in FIG. 4, each terminal electrode 203R is adhered to the surface of the carrier substrate 181.

After the element substrate 200 is adhered to the carrier substrate 181, the semiconductor substrate 201 and each LED chip 202R are separated by irradiation with a laser beam (not shown). This process is called the laser lift-off process. Specifically, the boundary portion between the semiconductor substrate 201 and each LED chip 202R is denatured by irradiation with laser light, and each LED chip 202R is separated from the semiconductor substrate 201. In this case, as the laser light, the laser light that is not absorbed by the semiconductor substrate 201 and is absorbed by the LED chip 202R is selected. As the laser light, for example, ultraviolet light can be used, but laser light having an appropriate wavelength may be selected according to the materials constituting the semiconductor substrate 201 and the LED chip 202R.

After separating the semiconductor substrate 201 and each LED chip 202R by the above process, a carrier substrate 181 having a plurality of LED chips 202R is next bonded onto the carrier substrate 191 as shown in FIG. In this embodiment, a sheet member made of a silicon material is used as the carrier substrate 191. Before adhering each LED chip 202R to the carrier substrate 191, it is preferable to weaken the adhesive force of the carrier substrate 181 by irradiation with a laser beam or the like. By weakening the adhesive force of the carrier substrate 181, it is possible to easily separate the carrier substrate 181 from each LED chip 202R.

After each LED chip 202R is adhered to the carrier substrate 191, the carrier substrate 181 is removed by peeling off the carrier substrate 181. By removing the carrier substrate 181 it is possible to prepare a carrier substrate 191 provided with a plurality of LED chips 202R.

Next, in step S13 of FIG. 1, a carrier substrate 191 having a plurality of LED chips 202R is adhered to the water-soluble adhesive layer 104 so that each connection electrode 103 and each LED chip 202R face each other. Specifically, as shown in FIG. 6, each LED chip 202R is adhered to the water-soluble adhesive layer 104 so that each connection electrode 103 and each terminal electrode 203R face each other via the water-soluble adhesive layer 104. Ru. As a result, each LED chip 202R can be temporarily fixed on the connection electrode 103.

In the present embodiment, for the sake of brevity, only one connection electrode 103 and one terminal electrode 203R are shown, but in reality, two connection electrodes 103 and terminals are shown for one LED chip 202R. The electrode 203R is provided. However, when the above-mentioned face-up type LED chip is used as the LED chip 202R, the structure may be such that one connection electrode 103 is provided for each pixel.

The higher the definition of the display device, the larger the number of pixels provided on the circuit board 100 and the smaller the size of each pixel. As the size of each pixel becomes smaller, the size of the LED chip 202R arranged in each pixel also becomes smaller, so that the method of transporting the LED chip 202R becomes difficult. Therefore, when the LED chip 202R is placed directly on the connection electrode 103, the position of the LED chip 202R and the position of the connection electrode 103 may not match with a slight vibration.

In the present embodiment, the water-soluble adhesive layer 104 is provided on the connection electrode 103 in order to eliminate such a problem. 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, it is possible to prevent the position shift of the LED chip 202R due to vibration. In this case, it is not necessary to firmly bond the adhesive, and it is sufficient that the adhesive force can be secured to the extent that temporary fixing is possible.

Next, in step S14 of FIG. 1, as shown in FIG. 7, the connection electrode 103 and the LED chip 202R are joined by irradiating the laser beam 40 with heat treatment. This process is a process of melting and joining the connection electrode 103 and the terminal electrode 203R by irradiating the laser beam 40.

As the laser light 40, a laser light that is not absorbed by 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, infrared light or near-infrared light can be used as the laser light 40. As the light source of the laser light 40, a solid-state laser such as a YAG laser or a YVO ₄ laser can be used. However, as the laser light 40, it is possible to select a laser light having an appropriate wavelength according to the material or the like constituting the LED chip 202R. For example, when a semiconductor material that absorbs laser light having a shorter wavelength than infrared light is used, a green laser (green light) can also be used.

By irradiation with the laser beam 40, an alloy layer 105 made of a eutectic alloy is formed between the connection electrode 103 and the terminal electrode 203R. As described above, in the present 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, a layer made of Sn—Au eutectic alloy is formed as the alloy layer 105. However, as the connection electrode 103 and the terminal electrode 203R, other metal materials may be used as long as they can form eutectic alloys with each other. For example, the connection electrode 103 and the terminal electrode 203R may both be made of tin (Sn).

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

By forming an alloy layer 105 made of a 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 joining each connection electrode 103 and the terminal electrode 203R of each LED chip 202R, the carrier substrate 191 is removed to obtain the state shown in FIG. Through the above process, as shown in FIG. 8, the LED chip 202R that emits red light can be mounted on the circuit board 100.

After obtaining the state shown in FIG. 8, steps S13 and S14 shown in FIG. 1 are repeated to sequentially mount the LED chip 202G that emits green light and the LED chip 202B that emits blue light on the circuit board 100. Through these processes, the state shown in FIG. 9 can be obtained. In the state shown in FIG. 9, an LED chip 202R that emits red light, an LED chip 202G that emits green light, and an LED chip 202B that emits blue light 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 washing treatment with water. By this process, the water-soluble adhesive layer 104 remaining between the LED chips 202 is collectively removed. Therefore, as shown in FIG. 10, the water-soluble adhesive layer 104 does not remain in the display device 10 on which each LED chip 202 is mounted. That is, according to the present embodiment, it is possible to prevent the position shift of the LED chip before joining by a simple method. Further, according to the present embodiment, the adhesive layer used for preventing the misalignment can be removed by a simple method, and the semiconductor element constituting the circuit can be prevented from being contaminated by an alkaline component or the like.

[Display device configuration]
The configuration of the display device 10 according to the 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 (FPC160), and an IC 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 chip 202 are arranged in the row direction (D1 direction) and the column direction (D2 direction). Specifically, in the present 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 a video signal.

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

The terminal area 116 is an area in which a plurality of wirings connected to the above-mentioned driver circuit are integrated. The flexible printed circuit board 160 is electrically connected to a plurality of wirings in the terminal area 116. The video signal (data signal) or control signal output from the external device (not shown) is input to the IC chip 170 via the wiring (not shown) provided on the flexible printed circuit board 160. The IC chip 170 performs various signal processing on the video signal and generates a control signal necessary for display control. The video signal and the control signal 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 a circuit configuration of the display device 10 according to the embodiment of the present invention. As shown in FIG. 12, the display area 112 is provided with a pixel circuit 120 corresponding to each pixel 110. In the present embodiment, the pixel circuit 120R, the pixel circuit 120G, and the 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, a plurality of pixel circuits 120 are arranged in the row direction (D1 direction) and the column direction (D2 direction).

FIG. 13 is a circuit diagram showing the configuration of the pixel circuit 120 of the display device 10 according to the embodiment of the present invention. The pixel circuit 120 is arranged in an area surrounded by a data line 121, a gate line 122, an anode power supply line 123, and a cathode power supply line 124. The pixel circuit 120 of this embodiment includes a selection transistor 126, a drive transistor 127, a holding capacity 128, and an LED 129. The LED 129 corresponds to the LED chip 202 shown in FIG. In the pixel circuit 120, the circuit elements other than the LED 129 correspond to the drive circuit 102 provided on the circuit board 100. That is, the pixel circuit 120 is completed with the LED chip 202 mounted on the circuit board 100.

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

A gradation signal that determines the emission intensity of the LED 129 is supplied to the data line 121. A gate signal for selecting the selection transistor 126 for writing the gradation signal is supplied to the gate line 122. When the selection transistor 126 is turned on, the gradation signal is accumulated in the holding capacity 128. After that, when the drive transistor 127 is turned on, a drive current corresponding to the gradation signal flows through the drive transistor 127. When the drive current output from the drive transistor 127 is input to the LED 129, the LED 129 emits light with a light emission intensity corresponding to the gradation signal.

Referring to FIG. 12 again, the data driver circuit 130 is arranged at a position adjacent to the display area 112 in the column direction (D2 direction). Further, the gate driver circuit 140 is arranged at a position adjacent to the row direction (D1 direction) with respect to the display area 112. In the present embodiment, two gate driver circuits 140 are provided on both sides of the display area 112, but only one of them may be used.

Both the data driver circuit 130 and the gate driver circuit 140 are arranged in the peripheral region 114. However, the area where the data driver circuit 130 is arranged is not limited to the peripheral area 114. For example, the data driver circuit 130 may be arranged on the flexible printed circuit board 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. Similarly, the terminal portion 150 is connected to the gate driver circuit 140 via the connection wiring 152. Further, the terminal portion 150 is connected to the flexible printed circuit board 160.

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

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

Wiring 18 is provided on 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. Therefore, the source electrode 16 and the wiring 18 are electrically connected by the connection wiring 20 provided on the flattening layer 19. The flattening layer 19 is a transparent resin layer using a resin material such as polyimide or acrylic. The connection wiring 20 is a transparent conductive layer using a metal oxide material such as ITO. However, the present invention is not limited to this example, and other metal materials may be used as the connection wiring 20.

An insulating layer 21 made of silicon nitride or the like is provided on the connection wiring 20. An anode electrode 22 and a cathode electrode 23 are provided on the insulating layer 21. In the present 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 via the openings provided in the flattening 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 via the flattening layer 24, respectively. The mounting pads 25a and 25b are made of a metal material such as tantalum or tungsten. 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. 10, respectively. That is, in the present embodiment, electrodes composed of tin (Sn) are arranged as the connection electrodes 103a and 103b.

The terminal electrodes 203a and 203b of the LED chip 202 are bonded to the connection electrodes 103a and 103b, respectively. As described above, in the present embodiment, the terminal electrodes 203a and 203b are electrodes made of gold (Au). As described with reference to FIG. 7, an alloy layer 105 (not shown) exists between the connection electrode 103a and the terminal electrode 203a.

The LED chip 202 corresponds to the LED 129 in the circuit diagram shown in FIG. That is, the terminal electrode 203a of the LED chip 202 is connected to the anode electrode 22 connected to the drain electrode 17 of the drive 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.

The display device 10 of the present embodiment having the above structure has an advantage that it has high resistance to impact and the like because the LED chip 202 is firmly mounted by melt bonding by laser irradiation.

<Second Embodiment>
In this 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 a reflow process for joining each LED chip 202 and each connection electrode 103. In this embodiment, a part different from the first embodiment will be described. Regarding the drawings used for the description of the present embodiment, the same components as those of the first embodiment are designated by the same reference numerals, and detailed description thereof will be omitted.

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

First, the circuit board 100 is prepared by the same process as in the first embodiment, and then the carrier board 191 provided with the plurality of LED chips 202R is prepared. In the present embodiment, the joining member 204R is provided in advance for the terminal electrode 203R of each LED chip 202R. The joining member 204R is a member made of a low melting point metal such as solder.

In this embodiment, as shown in FIG. 15, the bonding member 204R is adhered to the water-soluble adhesive layer 104. That is, each connection electrode 103 and each terminal electrode 203R face each other via the water-soluble adhesive layer 104 and the bonding member 204R. As a result, 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 performing a heat treatment. This process is a reflow process in which the joining member 204R is melted by thermal annealing and the connection electrode 103 and the terminal electrode 203R are joined via the joining member 204R. As a result, the LED chip 202R can be firmly mounted on the connection electrode 103.

When the connection electrode 103 and the terminal electrode 203R are joined by reflow processing as in the present embodiment, it is desirable that the water-soluble adhesive layer 104 contains a material having a flux action. The flux component has the effect of removing oxides on the metal surface. Therefore, by having the water-soluble adhesive layer 104 having a flux action 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 is removed during the reflow process. can do.

After the reflow process shown in FIG. 16, the processes shown in FIGS. 15 and 16 are repeated in the same manner as in the first embodiment, and the LED chip 202G that emits green light and the LED chip 202B that emits blue light are sequentially mounted. do. After mounting the LED chips 202R, 202G and 202B, the water-soluble adhesive layer 104 is finally removed by washing with water. By this process, the water-soluble adhesive layer 104 remaining between the LED chips 202 is collectively removed.

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

FIG. 17 is a cross-sectional view showing the configuration of pixels 110a of the display device according to the 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 flattening layer 24a below the LED chip 202. The side surface and the bottom surface of the opening 30 of the flattening layer 24a are covered with 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 for preventing moisture or the like from entering the circuit.

The opening 30 of the flattening layer 24a is formed at the same time as the contact hole 31a for connecting the anode electrode 22 and the mounting pad 25a and the contact hole 31b for connecting the cathode electrode 23 and the mounting pad 26a. Can be done. Inside the contact holes 31a and 31b, openings 32a and 32b are also formed in the insulating layer 26. The opening 32a is provided to electrically connect the anode electrode 22 and the mounting pad 25a. The opening 32b is provided to electrically connect the cathode electrode 23 and the mounting pad 25b. However, not limited to this example, the opening 32a or 32b may be provided so as to include the entire contact hole 31a or 31b.

On the other hand, as shown in FIG. 17, the insulating layer 26 remains unetched inside the opening 30. That is, the inside of the opening 30 has a structure in which the side surface and the bottom surface are covered with the insulating layer 26 to prevent the intrusion of moisture and the like.

As described above, the pixel 110a of the present embodiment has an opening 30 below the LED chip 202, that is, between the connection electrode 103a and the connection electrode 103b. As a result, a space larger than the pixel 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 easily reaches below the LED chip 202, and the water-soluble adhesive layer 104 can be efficiently removed. This makes it possible to prevent the problem that the water-soluble adhesive layer 104 remains between the LED chip 202 and the circuit board 100.

<Fourth Embodiment>
In this 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 method for manufacturing the display device 10 of the present embodiment, a carrier substrate 196 composed of a water-soluble adhesive sheet is used instead of the carrier substrate 191. In this embodiment, a part different from the first embodiment will be described. Regarding the drawings used for the description of the present embodiment, the same components as those of the first embodiment are designated by the same reference numerals, and detailed description thereof will be 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 in the first embodiment. In the first embodiment, the water-soluble adhesive layer 104 covering each connection electrode 103 is arranged on the circuit board 100, but in the present embodiment, the water-soluble adhesive layer 104 may not be arranged. However, the present invention is not limited to this example, and the water-soluble adhesive layer 104 may be arranged on each connection electrode 103 as in the first embodiment.

Next, the carrier substrate 181 provided with the plurality of LED chips 202R is prepared by the process described with reference to FIG. 4 in the first embodiment. After preparing the carrier substrate 181, next, as shown in FIG. 18, the carrier substrate 181 having a plurality of LED chips 202R is bonded onto the carrier substrate 196. In this embodiment, a water-soluble adhesive sheet (also referred to as a water-soluble adhesive film) is used as the carrier substrate 196. The water-soluble pressure-sensitive adhesive sheet is a member obtained by processing the same material as the water-soluble pressure-sensitive adhesive layer 104 described in the first embodiment into a sheet shape. That is, the carrier substrate 196 made of the water-soluble adhesive sheet is soluble in water and has adhesiveness.

After each LED chip 202R is adhered to the carrier substrate 196, the carrier substrate 181 is removed by peeling off the carrier substrate 181. By removing the carrier substrate 181 it is possible to prepare a carrier substrate 196 provided with a plurality of LED chips 202R.

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

At this time, as shown in FIG. 20, the end portion 196a of the carrier substrate 196 is adhered to the end portion of the circuit board 100. As a result, the position of the carrier substrate 196 is fixed, and each LED chip 202R can be temporarily fixed on the connection electrode 103. However, the present invention is not limited to this example, and a portion other than the end portion 196a of the carrier substrate 196 may be adhered. For example, if the distance between the connection electrodes 103 is sufficiently wide, the carrier substrate 196 can be adhered to the space between the connection electrodes 103.

After the carrier substrate 196 is bonded to the circuit board 100, the connection electrode 103 and the terminal electrode 203R are melt-bonded by irradiating the laser beam in the same manner as in the process described with reference to FIG. 7 in the first embodiment. This makes it possible to mount a plurality of LED chips 202R on the circuit board 100.

When the mounting of each LED chip 202R is completed, the carrier substrate 196 composed of the water-soluble adhesive sheet is removed by a water washing treatment. As described above, in the present embodiment, since the water-soluble carrier substrate 196 is used for transferring the plurality of LED chips 202R, it is possible to remove the carrier substrate 196 only by washing with water. Therefore, when the carrier board 196 is removed, unnecessary stress is not applied to the circuit board 100 and each LED chip 202R.

After mounting a plurality of LED chips 202R on the circuit board 100 through the above process, the processes described with reference to FIGS. 18 to 20 are repeated in the same manner as in the first embodiment, and the LEDs sequentially emit green light. The LED chip 202G and the LED chip 202B that emits blue light are mounted. In this embodiment, since the water-soluble adhesive sheet is used as the carrier substrate 196 even when the LED chip 202G and the LED chip 202B are mounted on the circuit board 100, the LED chip 202G, the LED chip 202B, and the carrier substrate 196 are washed with water. And can be easily separated.

(Modification example)
In the present embodiment, an example in which a single water-soluble adhesive sheet is used as the carrier substrate 196 is shown, but the present invention is not limited to this example. For example, as the carrier substrate 196, it is also possible to use a substrate in which a water-soluble adhesive sheet and a resin sheet are laminated. In this case, since the adhesive can be given to only one side of the carrier substrate 196, there is an advantage that the carrier substrate 196 can be easily handled after the LED chips 202 are adhered to the carrier substrate 196.

In the case of this modification, when each LED chip 202 is mounted on the circuit board 100 and then washed with water, the portion of the water-soluble adhesive sheet is dissolved, so that the resin sheet is removed by lift-off. Therefore, the carrier substrate 196 of this modification can also be easily removed by washing with water.

Each of the above-described embodiments of the present invention can be appropriately combined and carried out as long as they do not contradict each other. Based on each embodiment, those skilled in the art who have added, deleted, or changed the design of components as appropriate, or those who have added, omitted, or changed the conditions of processes also have the gist of the present invention. To the extent, it is included in the scope of the present invention.

Further, even if the action / effect is different from the action / effect brought about by the embodiment of each of the above-mentioned embodiments, those which are clear from the description of the present specification or which can be easily predicted by those skilled in the art are referred to. Naturally, it is understood that it is brought about by the present invention.

10 ... Display device, 11 ... Insulated substrate, 12 ... Semiconductor layer, 13 ... Gate insulating layer, 14 ... Gate electrode, 15 ... Insulated layer, 16 ... Source electrode, 17 ... Drain electrode, 18 ... Wiring, 19 ... Flattening layer , 20 ... connection wiring, 21 ... insulating layer, 22 ... anode electrode, 23 ... cathode electrode, 24 ... flattening layer, 25a, 25b ... mounting pad, 30 ... opening, 31a, 31b ... contact hole, 32a, 32b ... Opening, 40 ... Laser light, 100 ... Circuit board, 101 ... Support board, 102 ... Drive circuit, 103, 103a, 103b ... Connection electrode, 103a, 103b ... Connection electrode, 104 ... Water-soluble adhesive layer, 105 ... Alloy layer , 110, 110R, 110G, 110B ... pixel, 112 ... display area, 114 ... peripheral area, 116 ... terminal area, 120, 120R, 120G, 120B ... pixel circuit, 121 ... data line, 122 ... gate line, 123 ... anode Power line, 124 ... cathode power line, 126 ... selection transistor, 127 ... drive transistor, 128 ... holding capacity, 129 ... LED, 130 ... data driver circuit, 140 ... gate driver circuit, 150 ... terminal, 151, 152 ... connection Wiring, 160 ... Flexible printed circuit board, 170 ... IC chip, 181, 191 ... 196 ... Carrier board, 200 ... Element board, 201 ... Semiconductor board, 202, 202R, 202G, 202B ... LED chip, 203, 203a, 203b, 203R, 203G, 203B ... Terminal electrode, 204R ... Joining member,

Claims (9)

A first substrate having a drive circuit for driving the LED chip and a connection electrode connected to the drive circuit is prepared for each pixel.
A water-soluble adhesive layer covering the connection electrode is placed on the first substrate.
A second substrate having a plurality of LED chips is adhered to the water-soluble adhesive layer so that each connection electrode and each LED chip face each other.
By heat treatment, the connection electrodes and the LED chips are joined to each other.
The water-soluble adhesive layer is removed by washing with water.
How to manufacture a display device. The first aspect of claim 1, wherein joining each of the connection electrodes and the LED chips includes forming an alloy layer containing both constituent materials between the connection electrodes and the terminal electrodes of the LED chips. The method of manufacturing the display device described. The method for manufacturing a display device according to claim 1 or 2, wherein the heat treatment is performed by irradiation with a laser beam. The method for manufacturing a display device according to claim 3, wherein the laser light is infrared light or near-infrared light. The method for manufacturing a display device according to claim 1 or 2, wherein the heat treatment is a reflow treatment. The method for manufacturing a display device according to any one of claims 1 to 5, which comprises separating the second substrate and the plurality of LED chips between the heat treatment and the water washing treatment. The method for manufacturing a display device according to any one of claims 1 to 6, wherein the water-soluble adhesive layer contains a resin or a flux agent having a flux action. At least two of the connection electrodes are arranged in each pixel.
The method for manufacturing a display device according to any one of claims 1 to 7, which comprises forming an opening between at least two of the connection electrodes when forming the drive circuit. The method for manufacturing a display device according to claim 8, wherein the opening is formed by removing a part of the flattening layer.

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