阅读说明：本技术 显示装置及其制造方法 (Display device and method for manufacturing the same ) 是由 山田一幸 浅田圭介 武政健一 于 2021-05-31 设计创作，主要内容包括：本发明提供显示装置以及显示装置的制造方法,目的在于通过简单的方法防止接合前的LED芯片的位置偏差并且将LED芯片与电路基板接合。本发明的显示装置的制造方法包括：准备包括将LED芯片进行驱动的驱动电路的电路基板；在上述电路基板之上形成连接电极；在上述连接电极之上形成粘附层；在上述粘附层之上粘接LED芯片的端子电极；通过激光的照射,将上述连接电极与上述端子电极接合。上述粘附层可以仅形成在上述连接电极的上表面。(The invention provides a display device and a method for manufacturing the display device, aiming to prevent the position deviation of an LED chip before bonding and bond the LED chip and a circuit substrate by a simple method. The method for manufacturing a display device of the present invention includes: preparing a circuit substrate including a driving circuit that drives the LED chip; forming a connection electrode on the circuit substrate; forming an adhesion layer on the connection electrode; bonding a terminal electrode of the LED chip on the adhesive layer; the connection electrode and the terminal electrode are joined by irradiation with laser light. The adhesive layer may be formed only on the upper surface of the connection electrode.)

1. A method of manufacturing a display device, characterized in that,

the method comprises the following steps:

preparing a circuit substrate including a driving circuit that drives the LED chip;

forming a connection electrode on the circuit substrate;

forming an adhesion layer on the connection electrode;

bonding a terminal electrode of the LED chip on the adhesive layer;

the connection electrode and the terminal electrode are joined by laser irradiation.

2. The method of manufacturing a display device according to claim 1,

the adhesive layer is formed only on the upper surface of the connection electrode.

3. The method of manufacturing a display device according to claim 1 or 2,

the adhesive layer is a layer formed by applying a resin containing a flux.

4. The method of manufacturing a display device according to claim 1 or 2,

the adhesion layer is a resin layer containing a polymerization inhibitor.

5. The method of manufacturing a display device according to claim 1 or 2,

the laser light is near infrared light.

6. The method of manufacturing a display device according to claim 1 or 2,

the laser light is light emitted from a solid-state laser.

7. A display device is characterized in that a display panel is provided,

the method comprises the following steps:

a circuit substrate including a driving circuit that drives the LED chip;

a connection electrode disposed on the circuit board; and

an LED chip including a terminal electrode to which the connection electrode is bonded;

carbon is present in a higher concentration than the connection electrode and the terminal electrode in the alloy layer or in the periphery of the alloy layer joining the connection electrode and the terminal electrode.

8. The display device of claim 7,

the alloy layer is formed of a eutectic alloy including a 1 st metal constituting the connection electrode and a 2 nd metal constituting the terminal electrode.

9. The display device of claim 8,

the 1 st metal is tin Sn;

the 2 nd metal is gold Au.

10. The display device of claim 8,

the 1 st metal and the 2 nd metal are tin Sn.

Technical Field

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 having an led (light Emitting diode) chip.

Background

In recent years, as a next-generation display device, development of an LED display in which a minute LED chip is mounted on each pixel has been advanced. In general, 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 board has a driving circuit for causing the LEDs to emit light at positions corresponding to the respective pixels. The driving circuits are electrically connected to the LED chips, respectively.

The driving circuit and the LED chip 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 of bonding an LED chip and a circuit board with an adhesive layer. In this technique, the LED chip and the circuit substrate are bonded by an adhesive layer. Therefore, the conductive protrusion is provided on the electrode pad on the LED chip side. The protrusion penetrates the adhesive layer and contacts the electrode pad on the circuit substrate side, thereby electrically connecting the electrode pad on the LED chip side and the electrode pad on the circuit substrate side.

Documents of the prior art

Patent document

Patent document 1: U.S. patent application publication No. 2018/0031974 specification

Disclosure of Invention

Problems to be solved by the invention

In the technique described in the above conventional technique, since the adhesive layer is provided on the entire surface of the circuit board, there is a possibility that the semiconductor element constituting the circuit is contaminated with an alkaline component contained in an organic substance or the like to cause an operation failure. Further, a complicated processing technique for forming a three-dimensional protrusion portion for the electrode pad on the LED chip side is required.

One of the objects of the present invention is to bond an LED chip to a circuit board while preventing positional deviation of the LED chip before bonding by a simple method.

Means for solving the problems

A method for manufacturing a display device according to an embodiment of the present invention includes: preparing a circuit substrate including a driving circuit that drives the LED chip; forming a connection electrode on the circuit substrate; forming an adhesion layer on the connection electrode; bonding a terminal electrode of the LED chip on the adhesive layer; the connection electrode and the terminal electrode are joined by irradiation of laser light.

A display device according to an embodiment of the present invention includes: a circuit substrate including a driving circuit that drives the LED chip; a connection electrode disposed on the circuit board; and an LED chip including a terminal electrode to which the connection electrode is bonded; carbon is present in a higher concentration than the connection electrode and the terminal electrode in the alloy layer or in the periphery of the alloy layer joining the connection electrode and the terminal electrode.

Drawings

Fig. 1 is a flowchart illustrating a method for manufacturing a display device according to an embodiment of the present invention.

Fig. 2 is a cross-sectional view showing a method of manufacturing a display device according to an embodiment of the present invention.

Fig. 3 is a cross-sectional view showing a method of manufacturing a display device according to an embodiment of the present invention.

Fig. 4 is a cross-sectional view showing a method of manufacturing a display device according to an embodiment of the present invention.

Fig. 5 is a sectional view showing a method of manufacturing a display device according to an embodiment of the present invention.

Fig. 6 is a cross-sectional view showing a method of manufacturing a display device according to an embodiment of the present invention.

Fig. 7 is a sectional view showing a method of manufacturing a display device according to an embodiment of the present invention.

Fig. 8 is a plan view showing a schematic configuration of a display device according to an embodiment of the present invention.

Fig. 9 is a block diagram showing a circuit configuration of a display device according to an embodiment of the present invention.

Fig. 10 is a circuit diagram showing a configuration of a pixel circuit of a display device according to an embodiment of the present invention.

Fig. 11 is a cross-sectional view showing a structure of a pixel of a display device according to an embodiment of the present invention.

Description of the reference numerals

11 … insulating substrate; 12 … a semiconductor layer; 13 … a gate insulating layer; 14 … a gate electrode; 15 … an insulating layer; 16 … source electrode; 17 … drain electrode; 18 … wiring; 19 … planarizing layer; 20 … connecting wiring; 21 … an insulating layer; 22 … an anode electrode; 23 … cathode electrode; 24 … planarization layer; 25 … mounting pads; 100 … display device; 101 … circuit substrate; 102. 102a, 102b … connecting the electrodes; 103 … adhesive layer; 106 … laser; 107 … alloy layer; 110. 110R, 110G, 110B … pixels; 112 … display area; 114 … peripheral region; 116 … terminal regions; 120. 120R, 120G, 120B … pixel circuits; 121 … data lines; 122 … gate lines; 123 … anode power supply line; 124 … cathode power supply line; 126 … select transistors; 127 … drive transistor; 128 … hold capacitance; 130 … data driver circuit; 140 … gate driver circuit; 150 … terminal portions; 151 … connection wiring; 152 … connection wiring; 160 … flexible printed circuit substrate; 170 … IC chip; 201. 201R, 201G, 201B … LED chips; 202. 202a, 202B, 202R, 202G, 202B … terminal electrode

Detailed Description

Hereinafter, embodiments of the present invention will be described with reference to the drawings and the like. However, the present invention can be implemented in various forms without departing from the scope of the present invention. The present invention is not limited to the description of the embodiments illustrated below. In the drawings, the width, thickness, shape, and the like of each portion are schematically shown in comparison with the actual form in order to clarify the description. However, the drawings are only examples and do not limit the explanation of the present invention.

In describing the embodiment of the present invention, the direction from the circuit board toward the LED chip is referred to as "up", and the opposite direction is referred to as "down". However, the expressions "upper" and "lower" merely indicate the upper and lower relationships of the respective elements. For example, the expression that the LED chip is disposed on the circuit board includes a case where another member is interposed between the circuit board and the LED chip. Further, the expression "upper" or "lower" includes not only a case where the respective elements overlap in a plan view but also a case where the elements do not overlap.

In describing the embodiments of the present invention, the same reference numerals are given to elements having the same functions as those of the elements already described, or reference numerals such as latin letters are given to the same reference numerals, and the description thereof may be omitted. When it is necessary to distinguish among the respective RGB colors, a reference numeral R, G or B is given to a certain element after the reference numeral indicating the element. However, when it is not necessary to distinguish the RGB colors from each other, the description will be given only by using reference numerals indicating the elements.

[ method for manufacturing display device ]

Fig. 1 is a flowchart illustrating a method for manufacturing a display device 100 according to an embodiment of the present invention. Fig. 2 to 7 are cross-sectional views showing a method of manufacturing the display device 100 according to the embodiment of the present invention. Hereinafter, a method for manufacturing the display device 100 will be described with reference to fig. 1. At this time, the cross-sectional structure in each manufacturing step will be described with reference to fig. 2 to 7 as necessary.

First, in step S11, the circuit substrate 101 including the driving circuit that drives the LED chip is prepared (step S11). The circuit board 101 is a so-called active matrix board. That is, the circuit substrate 101 has a partition corresponding to a plurality of pixels, and includes a plurality of Thin Film Transistors (TFTs) corresponding to the respective pixels. The driving circuit for driving the LED chip includes a plurality of circuit elements. Each circuit element is formed corresponding to each pixel. The detailed structure of the circuit board 101 will be described later.

In this embodiment, the circuit board 101 is prepared by forming a driver circuit including a thin film transistor over a glass substrate, a resin substrate, or the like. However, the present invention is not limited to this example, and the circuit board 101 may be prepared by obtaining an existing circuit board 101 from a third party. In the present embodiment, a circuit board 101 on which, for example, a flip chip type LED chip 201 (see fig. 11) is mounted will be described. However, the LED chip 201 is not limited to the flip chip type example in which 2 electrodes are provided on the surface facing the circuit board 101. For example, the LED chip 201 may have an anode (or cathode) on a side closer to the circuit board 101 and a cathode (or anode) on a side farther from the circuit board 101. That is, the LED chip 201 may be a face-up type LED chip having a structure in which a light-emitting layer is interposed between an anode electrode and a cathode electrode.

Next, in step S12, as shown in fig. 2, the connection electrode 102 is formed on the circuit substrate 101. In this embodiment, an example in which a flip-chip type LED chip 201 is mounted on 9 connection electrodes 102 is shown. In fig. 2, for convenience of explanation, an example in which 1 connection electrode 102 is arranged for each pixel is shown, but actually at least 2 connection electrodes 102 are formed for each pixel. The LED chip has a terminal electrode connected to the N-type semiconductor and a terminal electrode connected to the P-type semiconductor. Therefore, when 1 LED chip is disposed for each pixel, at least 2 connection electrodes 102 are required for each pixel. However, when the above-described face-up type LED chip is used as the LED chip 201, at least 1 connection electrode 102 may be formed for each pixel on the circuit substrate 101.

The connection electrode 102 is made of, for example, a conductive metal material. In the present embodiment, tin (Sn) is used as the metal material. However, the present invention is not limited to this example, and other metal materials that can form a eutectic alloy with the terminal electrode on the LED chip side described later may be used. The thickness of the connection electrode 102 may be, for example, in the range of 0.2 μm to 5 μm (preferably 1 μm to 3 μm).

After the connection electrode 102 is formed, in step S13, as shown in fig. 3, the adhesion layer 103 is formed over the connection electrode 102. The adhesive layer 103 is a layer composed of a material having adhesiveness. "having adhesiveness" means having a characteristic that adhesion and peeling of a substance are easy. That is, in the case where another substance is brought into contact with the adhesive layer 103, the other substance can be fixed onto the adhesive layer 103 even if a weak force is applied. However, if a larger force is applied, other substances can be easily peeled off from the adhesive layer 103.

In the present embodiment, a layer formed by applying a resin containing flux (flux) is used as the adhesive layer 103. When a resin containing a flux is used as the adhesive layer 103, the flux component functions to remove an oxide film formed on the surface of the connection electrode 102. Therefore, the surface of the connection electrode 102 can be activated, and stable bonding with the terminal electrode 202 described later can be obtained. However, the adhesive layer 103 is not limited to this example, and a resin layer containing a polymerization inhibitor, for example, may be used. When a polymerization inhibitor is mixed with a resin material, polymerization is insufficient when the resin is cured. The insufficiently polymerized resin layer has adhesiveness on the surface, and therefore can be used as the adhesive layer 103 of the present embodiment.

The thickness of the adhesive layer 103 may be set to, for example, 5 μm or less (preferably 1 μm to 3 μm). As described later, the adhesive layer 103 is used as a layer for temporarily fixing the LED chip, and disappears in the laser light irradiation step. Therefore, in order to reduce the composition of the adhesive layer 103 remaining after laser irradiation, it is desirable that the film thickness is not more than 5 μm.

In this embodiment mode, the adhesive layer 103 is formed only on the upper surface of the connection electrode 102. That is, the adhesive layer 103 is not in contact with the circuit substrate 101. In this embodiment, since the adhesive layer 103 is not disposed on the circuit board 101, the composition of the adhesive layer 103 does not adversely affect a semiconductor element such as a thin film transistor formed on the circuit board 101. As a method for forming the adhesive layer 103, a method capable of selectively forming the adhesive layer 103, such as a mask printing method or an ink jet method, is preferably used. However, the present invention is not limited to this example, and a material having adhesiveness such as flux may be applied to the entire surface by spin coating, slit coating, or the like, and then the adhesive layer 103 may be formed only on the upper surface of the connection electrode 102 by photolithography.

Next, in step S14, as shown in fig. 4, the LED chip 201R emitting red light is mounted on the circuit board 101. Specifically, first, the terminal electrode 202R of the LED chip 201R is adhered onto the adhesive layer 103. Thereby, the LED chip 201R can be temporarily fixed onto the connection electrode 102. In the present embodiment, for the sake of simplifying the description, only 1 connection electrode 102 and terminal electrode 202R are shown, but actually, 2 connection electrodes 102 and 2 terminal electrodes 202R are provided for 1 LED chip 201R. However, when the above-described face-up type LED chip is used as the LED chip 201, the structure may be such that 1 connection electrode 102 is provided for each pixel depending on the position of the terminal electrode of the LED chip 201.

As the fineness of the display device increases, the number of pixels provided on the circuit board 101 increases, and the size of each pixel decreases. When the size of each pixel is reduced, the size of the LED chip 201 arranged for each pixel is also reduced, and therefore, a method of conveying the LED chip 201 is also difficult. Thus, in the case where the LED chip 201 is directly mounted on the connection electrode 102 without using the adhesive layer 103, the LED chip 201 may be dropped from the connection electrode 102 by a slight vibration.

In the present embodiment, in order to solve such a problem, an adhesive layer 103 is provided on the connection electrode 102. That is, in the example shown in fig. 4, by adhering the terminal electrode 202R of the LED chip 201R to the adhesive layer 103, the LED chip 201R can be prevented from falling due to vibration. In this case, the LED chip 201R does not need to be firmly bonded, and the adhesive layer 103 may have a degree of adhesion to temporarily fix the LED chip. Therefore, after the LED chip 201R is bonded to the adhesive layer 103, if it is before irradiation of laser light described later, the LED chip 201R can be easily peeled off even if the LED chip 201R needs to be replaced.

After the bonding of the LED chip 201R is completed, in step S15, as shown in fig. 5, the connection electrode 102 and the terminal electrode 202R are bonded by irradiation of the laser light 106. This step is a step of fusion-bonding the connection electrode 102 and the terminal electrode 202R by irradiation of the laser beam 106.

As the laser light 106, laser light that is not absorbed by the LED chip 201R but absorbed by the connection electrode 102 or the terminal electrode 202R is selected. In the present embodiment, for example, infrared light or near-infrared light can be used as the laser light 106. As a light source of the laser light 106, a YAG laser or YVO can be used₄Solid-state lasers such as lasers. However, the laser light 106 can be a laser light having an appropriate wavelength selected according to the semiconductor material constituting the LED chip 201R.

By irradiation with the laser light 106, the adhesive layer 103 disappears. Instead, alloy layer 107 made of a eutectic alloy is formed between connection electrode 102 and terminal electrode 202R. As described above, in the present embodiment, the connection electrode 102 is made of tin (Sn). On the other hand, the terminal electrode 202R is made of gold (Au). That is, in the present embodiment, a layer made of an Sn — Au eutectic alloy is formed as alloy layer 107. However, as the connection electrode 102 and the terminal electrode 202R, other metal materials may be used as long as they can form a eutectic alloy with each other. For example, both the connection electrode 102 and the terminal electrode 202R may be made of tin (Sn).

Further, by irradiation with the laser beam 106, the adhesive layer 103 disappears, and a part of the connection electrode 102 and a part of the terminal electrode 202R melt to form a eutectic alloy. The composition of the adhesion layer 103 is dispersed as carbon atoms in the eutectic alloy. Namely, the following are the cases: carbon is present at a higher concentration than the connection electrode 102 and the terminal electrode 202R in the alloy layer 107, or the connection electrode 102 at the junction between the connection electrode 102 and the terminal electrode 202R.

For example, in the case where the area of connection electrode 102 is larger than the area of terminal electrode 202R of LED chip 201R, the area around alloy layer 107 in plan view exposes the surface of connection electrode 102. In this case, carbon generated by the disappearance of the adhesion layer 103 is present at a higher concentration on the exposed surface of the connection electrode 102 than the terminal electrode 202R. The exposed surface of the connection electrode 102 has a higher carbon concentration than the back surface of the connection electrode 102 (the surface on the circuit board 101 side). Further, there are cases where: when laser light 106 is irradiated, adhesive layer 103 does not completely disappear, and adhesive layer 103 remains around alloy layer 107, for example, on the surface of connection electrode 102 exposed as described above.

As described above, by forming alloy layer 107 made of a eutectic alloy between connection electrode 102 and terminal electrode 202R, connection electrode 102 and terminal electrode 202R are joined via alloy layer 107. As a result, the LED chip 201R can be firmly mounted to the connection electrode 102.

After the red-light-emitting LED chip 201R is mounted by the steps of fig. 4 and 5, a green-light-emitting LED chip 201G is mounted on the circuit board 101 as shown in fig. 6. In mounting the LED chip 201G, as described above, the laser light 106 is irradiated in a state where the terminal electrode 202G is bonded to the adhesive layer 103. Thereby, the connection electrode 102 and the terminal electrode 202G are firmly joined via the alloy layer 107.

Finally, as shown in fig. 7, an LED chip 201B emitting blue light is mounted on the circuit board 101. In mounting the LED chip 201B, as described above, the laser light 106 is irradiated in a state where the terminal electrode 202B is bonded to the adhesive layer 103. Thereby, the connection electrode 102 and the terminal electrode 202B are firmly joined via the alloy layer 107

In the present embodiment, the LED chip 201R, LED and the LED chip 201R are mounted on the circuit board 101 in this order. However, the present invention is not limited to this example, and the order of installation may be determined as appropriate as needed.

As described above, in the manufacturing method of the present embodiment, the connection electrode 102 on the circuit board 101 side and the terminal electrode 202 on the LED chip 201 side are connected by fusion bonding by irradiation of the laser beam 106. At this time, the adhesive layer 103 is formed in advance over the connection electrode 102, and the LED chip 201 is releasably adhered onto the connection electrode 102. This can maintain the LED chip 201 fixed on the connection electrode 102 until the laser light 106 is irradiated.

According to the present embodiment, since the LED chip 201 can be fixed until the laser light 106 is irradiated, positional displacement of the LED chip 201 can be prevented. In addition, when a resin containing flux is used as the adhesive layer 103 as described above, the oxide film on the surface of the connection electrode 102 can be removed, and therefore, the occurrence of poor bonding when the terminal electrode 202 is bonded to the connection electrode 102 can be reduced.

Further, in the present embodiment, since the adhesive layer 103 is provided only on the upper surface of the connection electrode 102, a component (for example, an alkali component) of the adhesive layer 103 does not remain on the circuit board 101, and a problem due to the component of the adhesive layer 103 can be prevented. In addition, when the adhesive layer 103 is provided only on the upper surface of the connection electrode 102, the light transmission performance of the display device 100 is not affected, and thus a transparent display can be realized.

As described above, according to the manufacturing method of the present embodiment, it is possible to prevent positional deviation of the LED chip and bond the LED chip to the circuit substrate by a simple method.

[ Structure of display device ]

The structure of the display device 100 according to an embodiment of the present invention will be described with reference to fig. 8 to 11.

Fig. 8 is a plan view schematically showing the configuration of a display device 100 according to an embodiment of the present invention. As shown in fig. 8, the display device 100 includes a circuit board 101, a flexible printed circuit board 160(FPC160), and an IC chip 170. The display device 100 is divided into a display region 112, a peripheral region 114, and a terminal region 116.

The display region 112 is a region in which a plurality of pixels 110 including the LED chip 201 are arranged in the row direction (D1 direction) and the column direction (D2 direction). Specifically, in the present embodiment, a pixel 110R including an LED chip 201R, a pixel 110G including an LED chip 201G, and a pixel 110B including an LED chip 201B are arranged. The display area 112 functions as an area for displaying an image corresponding to a video signal.

The peripheral region 114 is a region around the display region 112. The peripheral region 114 is a region where a driver circuit (the data driver circuit 130 and the gate driver circuit 140 shown in fig. 9) for controlling a pixel circuit (the pixel circuit 120 shown in fig. 9) provided for each pixel 110 is provided.

The terminal region 116 is a region in which a plurality of wirings connected to the driver circuit are concentrated. The flexible printed circuit board 160 is electrically connected to the plurality of wirings in the terminal region 116. A video signal (data signal) or a control signal output from an external device (not shown) is input to the IC chip 170 via a wiring (not shown) provided on the flexible printed circuit board 160. The IC chip 170 performs various signal processes on the video signal to generate 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 100 via the flexible printed circuit board 160.

[ Circuit Structure of display device 100 ]

Fig. 9 is a block diagram showing a circuit configuration of the display device 100 according to the embodiment of the present invention. As shown in fig. 9, in the display region 112, a pixel circuit 120 is provided corresponding to each pixel 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 region 112, a plurality of pixel circuits 120 are arranged in the row direction (D1 direction) and the column direction (D2 direction).

Fig. 10 is a circuit diagram showing a configuration of a pixel circuit 120 of a display device 100 according to an 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 supply line 123, and the cathode power supply line 124. The pixel circuit 120 of this embodiment includes a selection transistor 126, a driving transistor 127, a holding capacitor 128, and an LED 129. The LED129 corresponds to the LED chip 201 shown in fig. 8. Circuit elements other than the LEDs 129 in the pixel circuit 120 are provided on the circuit board 101. That is, each pixel circuit 120 corresponds to a plurality of circuit elements of a driving circuit for driving the LED chip 201. That is, the pixel circuit 120 is completed in a state where the LED chip 201 is mounted on the circuit substrate 101.

As shown in fig. 10, the source electrode, the gate electrode, and the drain electrode of the selection transistor 126 are connected to the data line 121, the gate line 122, and the gate electrode of the driving transistor 127, respectively. The source electrode, the gate electrode, and the drain electrode of the driving transistor 127 are connected to the anode power supply line 123, the drain electrode of the selection transistor 126, and the LED129, respectively. A storage capacitor 128 is connected between the gate electrode and the drain electrode of the driving transistor 127. That is, the holding capacitance 128 is connected to the drain electrode of the selection transistor 126. The anode and cathode of the LED129 are connected to the drain electrode of the driving transistor 127 and the cathode power supply line 124, respectively.

A gradation signal that determines the light emission intensity of the LED129 is supplied to the data line 121. To the gate line 122, a gate signal for selecting the selection transistor 126 for writing the gradation signal is supplied. If the selection transistor 126 is turned ON, the gradation signal is stored in the holding capacitor 128. Then, if the driving transistor 127 is turned ON, a driving current corresponding to the gradation signal flows in the driving transistor 127. If the driving current output from the driving transistor 127 is input to the LED129, the LED129 emits light with a light emission intensity corresponding to the gradation signal.

Referring again to fig. 9, the data driver circuit 130 is disposed at a position adjacent to the display area 112 in the column direction (direction D2). Further, the gate driver circuit 140 is disposed at a position adjacent to the display region 112 in the row direction (direction D1). In this embodiment, the gate driver circuits 140 are provided on both sides of the display region 112, but only one of them may be used.

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

The data line 121 shown in fig. 10 extends from the data driver circuit 130 in the direction D2, 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 direction D1, and is connected to the gate electrode of the selection transistor 126 in each pixel circuit 120.

Terminal portion 150 is disposed in terminal region 116. The terminal unit 150 is connected to the data driver circuit 130 via a connection wiring 151. Similarly, the terminal portion 150 is connected to the gate driver circuit 140 via a connection wiring 152. Further, the terminal portion 150 is connected to the flexible printed circuit board 160.

[ Cross-sectional Structure of display device 100 ]

Fig. 11 is a cross-sectional view showing the structure of a pixel 110 of a display device 100 according to an embodiment of the present invention. As described with reference to fig. 10, the pixel 110 includes the driving transistor 127 provided over the insulating substrate 11. As the insulating substrate 11, a substrate in which an insulating layer is provided over a glass substrate or a resin substrate can be used.

The driving transistor 127 includes a semiconductor layer 12, a gate insulating layer 13, and a gate electrode 14. The source electrode 16 and the drain electrode 17 are connected to the semiconductor layer 12 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. 10.

The wiring 18 is provided in the same layer as the source electrode 16 and the drain electrode 17. The wiring 18 functions as an anode power supply line 123 shown in fig. 10. Therefore, the source electrode 16 and the wiring 18 are electrically connected to the connection wiring 20 provided on the planarization layer 19. The planarizing layer 19 is a transparent resin layer made of 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. On the insulating layer 21, an anode electrode 22 and a cathode electrode 23 are provided. In the present embodiment, the anode electrode 22 and the cathode electrode 23 are transparent conductive layers made of a metal oxide material such as ITO. The anode electrode 22 is connected to the drain electrode 17 through an opening 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, respectively, via the planarization layer 24. The mounting pads 25a and 25b are made of a metal material such as tantalum or tungsten. On the mounting pads 25a and 25b, connection electrodes 102a and 102b are provided, respectively. The connection electrodes 102a and 102b correspond to the connection electrodes 102 shown in fig. 7, respectively. That is, in the present embodiment, electrodes made of tin (Sn) are disposed as the connection electrodes 102a and 102 b.

The connection electrodes 102a and 102b are respectively bonded to the terminal electrodes 202a and 202b of the LED chip 201. As described above, in the present embodiment, the terminal electrodes 202a and 202b are electrodes made of gold (Au). Here, if attention is paid to the connection electrode 102a and the terminal electrode 202a, as described with reference to fig. 5, an unillustrated alloy layer (alloy layer 107 shown in fig. 5) is present between the connection electrode 102a and the terminal electrode 202 a. In the present embodiment, carbon is present in a higher concentration in the alloy layer that is the junction between the connection electrode 102a and the terminal electrode 202a and in the periphery thereof (for example, in the surface of the connection electrode 102a exposed around the alloy layer) than in the interior of the connection electrode 102a, the back surface of the connection electrode 102a (the surface on the circuit board 101 side), and the terminal electrode 202 a. For example, the adhesive layer 103 may remain on the surface of the mounting pads 25a and 25b or on a part of the surface of the connection electrode 102a without being removed. Further, carbon may be present at a higher concentration on the surface of the mounting pads 25a and 25b than on the back surfaces (surfaces on the side of the planarizing layer 24) of the mounting pads 25a and 25 b. Although the description has been given with the connection electrode 102a and the terminal electrode 202a in mind, the same applies to the connection electrode 102b and the terminal electrode 202 b.

The LED chip 201 corresponds to the LED129 in the circuit diagram shown in fig. 10. That is, the terminal electrode 202a of the LED chip 201 is connected to the anode electrode 22 connected to the drain electrode 17 of the driving transistor 127. The terminal electrode 202b of the LED chip 201 is connected to the cathode electrode 23. The cathode electrode 23 is electrically connected to a cathode power supply line 124 shown in fig. 10.

The display device 100 of the present embodiment having the above-described structure has an advantage of high resistance to impact or the like because the LED chip 201 is firmly mounted by fusion bonding by laser irradiation. In addition, in the present embodiment, since the fusion bonding is performed in a state where the LED chip 201 is temporarily fixed on the connection electrodes 102a and 102b, there is also an advantage that the positional deviation of the LED chip 201 is extremely small.

(modification 1)

In the above-described embodiment, the adhesive layer 103 is disposed only on the upper surface of the connection electrode 102, but the present invention is not limited to this example. For example, the adhesive layer 103 may be formed larger than the connection electrode 102 in a plan view, and the adhesive layer 103 may be formed so as to cover the upper surface and the side surface of the connection electrode 102.

(modification 2)

In the above-described embodiment, the connection electrode 102 and the terminal electrode 202 are bonded by fusion bonding by laser irradiation, but the present invention is not limited to this example. For example, the connection electrode 102 and the terminal electrode 202 may be joined by liquid phase joining by soldering or the like. In this case, according to the present embodiment, the LED chip 201 can be temporarily fixed onto the connection electrode 102 during the process of liquid phase bonding. At this time, the adhesive layer 103 disappears by heat at the time of melting such as soldering, and therefore, the electrical connection between the connection electrode 102 and the terminal electrode 202 is not damaged.

The embodiments and the modifications described as the embodiments of the present invention can be combined and implemented as appropriate as long as they are not contradictory to each other. In the present invention, the configuration in which a person skilled in the art appropriately performs addition, deletion, or design change of a component or performs addition, deletion, or condition change of a process based on each embodiment and modification example is included in the scope of the present invention as long as the gist of the present invention is satisfied.

It is to be understood that the present invention includes other operational effects that are different from the operational effects obtained by the embodiments and the modifications described above, and that are obvious from the description of the present specification or can be easily predicted by a person skilled in the art.