Display device

Abstract

A display device capable of providing an LED display with high production efficiency comprises: wiring that has a layer including an upper surface and formed by a first material, and that is electrically connected to a transistor of a pixel circuit; a connection electrode that is electrically connected to the wiring and has a layer including an upper surface and formed by a second material; and an LED element that is mounted on the connection electrode. The infrared absorptance of the first material is smaller than the infrared absorptance of the second material. This display device may further comprise an insulation layer that covers the upper surface of the wiring and is provided with an opening reaching the wiring.

Description

[Technical field]

[0001] An embodiment of the present invention relates to a display device, and more particularly to a display device equipped with LED (Light Emitting Diode) elements. [Background technology]

[0002] In recent years, LED displays, in which tiny LED elements are mounted on each pixel, have been developed as the next generation of display devices. Normally, LED displays have a structure in which multiple LED elements are mounted on a circuit board that constitutes a pixel array. The circuit board has drive circuits for emitting light from the LEDs at positions corresponding to each pixel. These drive circuits are electrically connected to each LED element.

[0003] The drive circuit and the LED element are electrically connected via a connection electrode. Specifically, a connection electrode provided on the drive circuit side and a terminal electrode provided on the LED element side are electrically connected to each other. For example, Patent Document 1 describes a technique for joining an LED element and a circuit board using a conductive material. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2020-67626 A Summary of the Invention [Problem to be solved by the invention]

[0005] As in the above-mentioned conventional technology, when an LED element is mounted on a substrate on which a drive circuit is provided, the connection electrode and the terminal electrode are joined by irradiating a laser beam from the LED element side while the connection electrode and the terminal electrode are in contact with each other. Since the laser beam is irradiated onto the connection electrode and the terminal electrode through the semiconductor substrate on which the LED element is provided, infrared light, for example, is used as the laser beam. The infrared laser beam is absorbed by the metal used as the wiring included in the drive circuit. Therefore, heat is generated in the wiring irradiated with the laser beam, and the drive circuit may be destroyed by the heat.

[0006] In order to solve the above problem, in the past, when performing laser irradiation, it was necessary to take measures such as covering the wiring of the drive circuit with a mask so that the laser light would not be irradiated onto the wiring. However, when performing laser irradiation using a mask, a process of aligning the mask with the drive circuit is required. As a result, there is a problem that production efficiency is reduced.

[0007] An object of the present invention is to provide an LED display that can be produced with high production efficiency. [Means for solving the problem]

[0008] A display device according to one embodiment of the present invention includes a layer including an upper surface formed of a first material, wiring electrically connected to a transistor of a pixel circuit, a layer including an upper surface formed of a second material, a connection electrode electrically connected to the wiring, and an LED element mounted on the connection electrode, the infrared ray absorptance of the first material being lower than the infrared ray absorptance of the second material.

[0009] A display device in one embodiment of the present invention has an aluminum layer as a layer including an upper surface, wiring electrically connected to a transistor of a pixel circuit, an insulating layer having an opening and covering the upper surface of the aluminum layer in an area other than the area in which the opening is provided, a connection electrode provided on the insulating layer, including a first conductive layer, a second conductive layer, and a third conductive layer, and electrically connected to the wiring through the opening, and an LED element mounted on the connection electrode, wherein the second conductive layer has barrier properties that suppress diffusion of materials contained in the first conductive layer and materials contained in the third conductive layer. [Brief description of the drawings]

[0010] [Figure 1] 1 is a plan view showing a schematic configuration of a display device according to an embodiment of the present invention. [Diagram 2] 1 is a block diagram showing a circuit configuration of a display device according to an embodiment of the present invention. [Diagram 3] 1 is a circuit diagram showing a configuration of a pixel circuit of a display device according to an embodiment of the present invention. [Figure 4] 1 is a cross-sectional view showing a configuration of a pixel of a display device according to one embodiment of the present invention. [Diagram 5] FIG. 5 is a partially enlarged view of FIG. [Figure 6] 1 is a planar layout diagram showing a configuration of a pixel of a display device according to an embodiment of the present invention. [Figure 7] 1 is a planar layout diagram showing a configuration of a pixel of a display device according to an embodiment of the present invention. [Figure 8] 1 is a cross-sectional view showing a configuration of a pixel of a display device according to one embodiment of the present invention. [Figure 9] FIG. 9 is a partially enlarged view of FIG. 8. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. However, the present invention can be implemented in various forms without departing from the gist of the present invention. The present invention is not interpreted as being limited to the description of the embodiments exemplified below. In order to clarify the explanation, the drawings may be schematic in terms of the width, thickness, shape, etc. of each part compared to the actual form. However, the drawings are merely examples and do not limit the interpretation of the present invention.

[0012] When describing the embodiments of the present invention, the direction from the substrate toward the LED element is referred to as "upper", and the opposite direction is referred to as "lower". However, the expressions "upper" and "lower" merely describe the upper-level relationship of each element. For example, the expression that the LED element is disposed on the substrate includes the case where another member is interposed between the substrate and the LED element. Furthermore, the expressions "upper" and "lower" include not only the case where the elements overlap in a planar view, but also the case where they do not overlap. The expressions "directly above" and "directly below" refer to the case where the elements overlap in a planar view.

[0013] In this specification and claims, multiple structures formed by subjecting a film to processing such as etching may be described as structures having different functions or roles. These multiple structures are described as structures that are made of the same layer structure and the same material and are in the same layer. Multiple structures formed by different processes are provided on top of and in contact with the same other structure.

[0014] In this specification, unless otherwise specified, expressions such as "α includes A, B, or C," "α includes any one of A, B, and C," and "α includes one selected from the group consisting of A, B, and C" do not exclude cases where α includes multiple combinations of A to C. Furthermore, these expressions do not exclude cases where α includes other elements.

[0015] When describing the embodiments of the present invention, elements having the same functions as elements already described are indicated by the same reference numerals or the same reference numerals with a symbol such as an alphabet, and the description may be omitted. For example, when a plurality of elements with a certain reference numeral are present in a drawing, they may be distinguished by adding "a", "b", etc. to the reference numerals. On the other hand, when it is not necessary to distinguish between the elements, only the reference numerals indicating the elements may be used for the description. Similarly, when it is necessary to distinguish between the respective colors of RGB for a certain element, the reference numerals indicating the element may be followed by the symbols R, G, or B for the element. On the other hand, when it is not necessary to distinguish between the respective colors of RGB for the element, only the reference numerals indicating the element may be used for the description.

[0016] First Embodiment [Display device configuration] The configuration of a display device 10 according to one embodiment of the present invention will be described with reference to FIGS.

[0017] Fig. 1 is a plan view showing a schematic configuration of a display device 10 according to a first embodiment of the present invention. As shown in Fig. 1, the display device 10 has a circuit board 100, a flexible printed circuit board 160 (FPC 160), and an IC element 170. The display device 10 is divided into a display area 112, a peripheral area 114, and a terminal area 116.

[0018] The display area 112 is an area in which a plurality of pixels 110, each including an LED element 200, are arranged in a row direction (D1 direction) and a column direction (D2 direction). Specifically, in this embodiment, a red pixel 110R including a red LED element 200R, a green pixel 110G including a green LED element 200G, and a blue pixel 110B including a blue LED element 200B are arranged in the display area 112. The display area 112 functions as an area for displaying an image according to a video signal (data signal).

[0019] The peripheral region 114 is a region surrounding the display region 112. The peripheral region 114 is a region where driver circuits (the data driver circuit 130 and the gate driver circuit 140 shown in FIG. 2) for controlling pixel circuits (the pixel circuits 120R, 120G, and 120B shown in FIG. 2) provided in each pixel 110 are provided.

[0020] The terminal area 116 is an area where a plurality of wirings connected to the driver circuit described above are gathered together. The flexible printed circuit board 160 is electrically connected to the plurality of wirings in the terminal area 116. A video signal or a control signal output from an external device (not shown) is input to the IC element 170 via wirings (not shown) provided on the flexible printed circuit board 160. The IC element 170 generates various signal processes for the video signal and control signals required for display control. The video signal and the control signal output from the IC element 170 are input to the display device 10 via the flexible printed circuit board 160.

[0021] [Circuit configuration of display device] Fig. 2 is a block diagram showing a circuit configuration of the display device 10 according to the first embodiment of the present invention. As shown in Fig. 2, a pixel circuit 120 is provided in the display region 112 in correspondence with each pixel 110. In this embodiment, a pixel circuit 120R, a pixel circuit 120G, and a pixel circuit 120B are provided in correspondence with the pixel 110R, the pixel 110G, and the pixel 110B, respectively. That is, a plurality of pixel circuits 120 are arranged in the row direction (D1 direction) and the column direction (D2 direction) in the display region 112.

[0022] 3 is a circuit diagram showing a configuration of a pixel circuit 120 in the display device 10 of the first embodiment of the present invention. The pixel circuit 120 is disposed in an area surrounded by a data line 121, a gate line 122, an anode power line 123, and a cathode power line 124. The pixel circuit 120 of this embodiment includes a selection transistor 126, a drive transistor 127, a storage capacitor 128, and an LED 129. The LED 129 corresponds to the LED element 200 shown in FIG. 1. Of the pixel circuit 120, the circuit elements other than the LED 129 correspond to a drive circuit 125 (see FIG. 4) provided on the circuit board 100. In other words, the pixel circuit 120 is completed by mounting the LED element 200 on the drive circuit 125.

[0023] 3, the source electrode, gate electrode, and drain electrode of the selection transistor 126 are connected to the data line 121, the gate line 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 line 123, the drain electrode of the selection transistor 126, and the LED 129, respectively. A storage capacitor 128 is connected between the gate electrode and drain electrode of the drive transistor 127. That is, the storage capacitor 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 of the drive transistor 127 and the cathode power line 124, respectively.

[0024] A grayscale signal that determines the light emission intensity of the LED 129 is supplied to the data line 121. A gate signal for selecting a selection transistor 126 to which the grayscale signal is written is supplied to the gate line 122. When the selection transistor 126 is turned on, the grayscale signal is stored in a storage capacitor 128. After that, when the drive transistor 127 is turned on, a drive current corresponding to the grayscale 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 grayscale signal.

[0025] 2, a data driver circuit 130 is disposed adjacent to the display area 112 in the column direction (direction D2). A gate driver circuit 140 is disposed adjacent to the display area 112 in the row direction (direction D1). In the present embodiment, a configuration in which two gate driver circuits 140 are provided on both sides of the display area 112 is exemplified, but a configuration in which only one of the gate driver circuits 140 is provided may also be used.

[0026] The data driver circuit 130 and the gate driver circuit 140 are both arranged in the peripheral region 114. However, the region in which the data driver circuit 130 is arranged is not limited to the peripheral region 114. For example, the data driver circuit 130 may be arranged on a flexible printed circuit board 160.

[0027] 3 extends in the column direction from the data driver circuit 130 and is connected to the source electrode of the selection transistor 126 in each pixel circuit 120. The gate line 122 extends in the row direction from the gate driver circuit 140 and is connected to the gate electrode of the selection transistor 126 in each pixel circuit 120.

[0028] A terminal portion 150 is disposed in the terminal region 116. The terminal portion 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. Furthermore, the terminal portion 150 is connected to a flexible printed circuit board 160.

[0029] [Cross-sectional structure of pixel] 4 is a cross-sectional view showing the configuration of a pixel 110 in the display device 10 of the first embodiment of the present invention. The pixel 110 has a drive transistor 127 provided on an insulating substrate 11. As the insulating substrate 11, a substrate having an insulating layer provided on a glass substrate, a resin substrate, a ceramic substrate, or a metal substrate is used. When a resin substrate is used as the insulating substrate 11, flexibility can be imparted to the display device 10.

[0030] 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 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. 3. The source electrode 16 is electrically connected to the anode power line 123 by a connection wiring 20 provided on the planarization layer 19. The planarization layer 19 is a transparent resin layer using a resin material such as polyimide or acrylic.

[0031] The source electrode 16, the drain electrode 17, and the connection wiring 20 are made of a metal material including tantalum (Ta), tungsten (W), molybdenum (Mo), titanium (Ti), or aluminum (Al). For example, the source electrode 16 and the drain electrode 17 are made of wiring having a laminated structure in which an aluminum layer is sandwiched between titanium layers (hereinafter, referred to as "Ti / Al / Ti"). The connection wiring 20 is made of wiring having a laminated structure of titanium (lower layer) and aluminum (upper layer) (hereinafter, referred to as "Al / Ti"). However, the structures of the source electrode 16, the drain electrode 17, and the connection wiring 20 are not limited to the above example. These structures do not have to be laminated structures, and materials other than those mentioned above may be used. For example, the connection wiring 20 may be made of a transparent conductive layer using a metal oxide material such as ITO.

[0032] An insulating layer 21 made of silicon oxide, silicon nitride, or the like is provided on the connection wiring 20. An anode wiring 22 and a cathode wiring 23 are provided on the insulating layer 21. These wirings are made of metal materials. The anode wiring 22 is connected to the drain electrode 17 through an opening provided in the planarization layer 19 and the insulating layer 21. The cathode wiring 23 is connected to the wiring 18 through an opening provided in the planarization layer 19 and the insulating layer 21. In other words, the anode wiring 22 is electrically connected to the drive transistor 127.

[0033] The anode wiring 22 and the cathode wiring 23 are made of a metal material containing tantalum, tungsten, molybdenum, titanium, or aluminum, as described above. For example, a laminated structure of "Al / Ti" is used for the anode wiring 22 and the cathode wiring 23. The materials and physical properties required for the anode wiring 22 and the cathode wiring 23 will be described in detail later.

[0034] As described above, the anode wiring 22 and the cathode wiring 23 are formed to complete the drive circuit 125. Although not shown in Fig. 4, in addition to the drive transistor 127, elements such as a selection transistor 126 and a storage capacitor 128 are also formed.

[0035] An insulating layer 24 is provided on the anode wiring 22 and the cathode wiring 23. The insulating layer 24 is in contact with the aluminum layer, which is the top layer of each of the anode wiring 22 and the cathode wiring 23. An opening is provided in the insulating layer 24. As the insulating layer 24, an inorganic insulating material such as silicon oxide, silicon nitride, aluminum oxide, or aluminum nitride is used. Alternatively, as the insulating layer 24, a transparent resin layer using a resin material such as polyimide or acrylic may be used. As the insulating layer 24, these materials may be used in a single layer or in a laminated layer. Although details will be described later, the insulating layer 24 covers the upper surfaces of the anode wiring 22 and the cathode wiring 23 and suppresses the progression of oxidation of the surfaces of these wirings.

[0036] The connection electrodes 103a and 103b are provided on the insulating layer 24 and in an opening provided in the insulating layer 24. The connection electrodes 103a and 103b are connected to the anode wiring 22 and the cathode wiring 23 through the openings provided in the insulating layer 24. The connection electrode 103a functions as an intermediate layer that electrically connects the driving transistor 127 and the LED element 200. The connection electrode 103b functions as an intermediate layer that electrically connects the LED element 200 and the cathode wiring 23. The connection electrodes 103a and 103b are made of a metal material including gold (Au), silver (Ag), copper (Cu), tin (Sn), titanium (Ti), or nickel (Ni). As will be described in detail later, a laminated structure of "Sn / Cu / Ti" is used as the connection electrodes 103a and 103b. The materials and physical properties required for the connection electrodes 103a and 103b will be described in detail later.

[0037] An LED element 200 is mounted on the connection electrodes 103a and 103b. The LED element 200 includes a semiconductor layer 202 and terminal electrodes 203a and 203b. The semiconductor layer 202 functions as a photoelectric conversion layer including an n-type semiconductor layer and a p-type semiconductor layer. In this embodiment, the semiconductor layer 202 is made of a semiconductor material including gallium nitride, but is not limited to this example.

[0038] In this embodiment, as shown in FIG. 3, the anode of the LED 129 is connected to the drive transistor 127. In FIG. 4, the terminal electrode 203a of the LED element 200 is connected to the anode wiring 22 connected to the drain electrode 17 of the drive transistor 127. The terminal electrode 203b of the LED element 200 is connected to the cathode wiring 23. The cathode wiring 23 is electrically connected to the cathode power supply line 124 shown in FIG. 3. Therefore, the terminal electrode 203a is connected to the p-type semiconductor layer of the semiconductor layer 202 and is connected to the connection electrode 103a. On the other hand, the terminal electrode 203b is connected to the n-type semiconductor layer of the semiconductor layer 202 and is connected to the connection electrode 103b.

[0039] In this embodiment, gold (Au) is used as the terminal electrode 203. Although details will be described later, the connection electrode 103 and the terminal electrode 203 are joined by laser light irradiation. Therefore, an alloy layer (eutectic alloy containing tin and gold) (not shown) exists between the connection electrode 103 and the terminal electrode 203.

[0040] Fig. 5 is a partially enlarged view of Fig. 4. Fig. 5 is an enlarged view of the structures of the anode wiring 22, the connection electrode 103a, and the terminal electrode 203a in Fig. 4. As shown in Fig. 5, the anode wiring 22 includes a first conductive layer 221 and a second conductive layer 222. The connection electrode 103a includes a first conductive layer 231, a second conductive layer 232, and a third conductive layer 233.

[0041] The second conductive layer 222 is a layer including the upper surface of the anode wiring 22. The second conductive layer 222 is formed of a first material. The third conductive layer 233 is a layer including the upper surface of the connection electrode 103a. The third conductive layer 233 is formed of a second material. The infrared absorptance of the first material is lower than the infrared absorptance of the second material. In other words, when comparing the absorptance of light with a wavelength of 1 μm, the absorptance of the first material is lower than that of the second material. The thickness of the second conductive layer 222 can be 1 μm or more.

[0042] The first conductive layer 221 is made of a material that has higher heat resistance than the second conductive layer 222, high adhesion to the lower layer (insulating layer 21), low contact resistance with the conductive layer provided under the insulating layer 21, and low contact resistance with the second conductive layer 222. For example, the first conductive layer 221 is made of tantalum, tungsten, molybdenum, or titanium.

[0043] The materials for the third conductive layer 233 and the terminal electrode 203 may be materials that form a eutectic alloy by heat generated by irradiation with infrared laser light. As described above, in this embodiment, a configuration in which tin (Sn) is used for the third conductive layer 233 and gold (Au) is used for the terminal electrode 203 is exemplified, but the materials are not limited to the above as long as they form a eutectic alloy. Furthermore, a tin alloy containing tin, silver, and copper may be used for the third conductive layer 233. In addition to gold, tin or a tin alloy may be used for the terminal electrode 203.

[0044] The second conductive layer 232 suppresses mutual diffusion of the first conductive layer 231 and the third conductive layer 233 due to heat generated by infrared laser light irradiation. For example, nickel is used as the second conductive layer 232. The second conductive layer 232 may be called a barrier layer.

[0045] The first conductive layer 231 is a layer for ensuring contact with the second conductive layer 222 of the connection electrode 103a, and functions as a base for the second conductive layer 232. For example, when the second conductive layer 232 is formed of copper by electrolytic plating, the first conductive layer 231 functions as a seed layer for the second conductive layer 232, which is a plating layer. The first conductive layer 231 may be made of titanium, nickel, copper, or a laminated structure of copper and titanium.

[0046] In this embodiment, titanium is used as the first conductive layer 221, and aluminum is used as the second conductive layer 222. Titanium is used as the first conductive layer 231, copper is used as the second conductive layer 232, and tin is used as the third conductive layer. In other words, the above-mentioned "first material" corresponds to aluminum, and the "second material" corresponds to tin. The infrared absorption rate of aluminum as the first material is lower than the infrared absorption rate of tin as the second material. The infrared absorption rate of aluminum is about 13%, and the infrared absorption rate of tin is about 40%.

[0047] When mounting the LED element 200 on the circuit board 100, as shown in FIG. 4, the terminal electrode 203 is disposed on the connection electrode 103, and the terminal electrode 203 and the connection electrode 103 are irradiated with infrared laser light from above the LED element 200 (see the arrow in FIG. 5). The infrared laser light passes through the semiconductor layer 202 of the LED element 200 and is absorbed by gold provided as the terminal electrode 203 and tin provided as the third conductive layer 233 of the connection electrode 103. When the laser light is absorbed by the terminal electrode 203 and the third conductive layer 233, the temperatures of the terminal electrode 203 and the third conductive layer 233 rise, and a eutectic alloy of gold and tin is formed. As described above, the terminal electrode 203 and the third conductive layer 233 are bonded by the laser irradiation.

[0048] During the above-mentioned bonding by laser irradiation, if the metal other than the terminal electrode 203 and the connection electrode 103 is irradiated with laser light, heat is generated at the irradiated portion, which may adversely affect the transistor element and the capacitance element constituting the display device. Therefore, it is desired to suppress heat generation due to laser irradiation as much as possible at the portions other than the above-mentioned bonding portion. In this embodiment, the second conductive layer 222 has a lower infrared absorption rate than the third conductive layer 233. In other words, the second conductive layer 222 has a higher infrared reflectance than the third conductive layer 233. Therefore, even if the laser irradiation is performed without using a mask, it is possible to suppress heat generation by the second conductive layer 222 (anode wiring 22), and to suppress adverse effects on the transistor element and the capacitance element. By making the thickness of the second conductive layer 222 1 μm or more, even if the second conductive layer 222 generates heat due to the laser irradiation, it is possible to suppress the heat from being transferred to the transistor element and the like provided below the anode wiring 22 and the cathode wiring 23.

[0049] In this embodiment, a semiconductor material containing gallium nitride that transmits near-infrared light is used as the semiconductor layer 202, and therefore, light (wavelength: approximately 1064 nm) emitted from a YAG laser or a YVO4 laser is used as the laser light used for the above laser irradiation.

[0050] The insulating layer 24 covers the upper surface of the second conductive layer 222, thereby suppressing the progress of oxidation of the upper surface of the second conductive layer 222. A natural oxide film may be formed on the upper surface of the second conductive layer 222 before the insulating layer 24 is formed, but no oxide film is formed after the insulating layer 24 is formed. As described above, the infrared absorption rate of aluminum is about 13%, but the infrared absorption rate of aluminum oxide formed on the surface of aluminum is about 40%. In other words, when the surface of the second conductive layer 222 is oxidized, the infrared absorption rate increases suddenly. Therefore, when aluminum is used as the second conductive layer 222, as the oxidation of the surface progresses, the second conductive layer 222 (anode wiring 22) generates heat due to the absorption of infrared rays by the aluminum oxide. In order to suppress such heat generation, the insulating layer 24 is formed on the second conductive layer 222. The infrared absorption rate of the insulating layer 24 is sufficiently smaller than the infrared absorption rate of aluminum.

[0051] In this embodiment, an opening is provided in the insulating layer 24, and the first conductive layer 231 is provided in the opening, thereby conducting the second conductive layer 222 and the first conductive layer 231. In order to ensure good conduction between the second conductive layer 222 and the first conductive layer 231, after the opening is formed, reverse sputtering is performed immediately before the deposition of the first conductive layer 231. By the reverse sputtering, a natural oxide film or the like formed on the surface of the second conductive layer 222 exposed by the opening is removed, and good conduction between the second conductive layer 222 and the first conductive layer 231 is obtained.

[0052] [Pixel Plane Layout] Fig. 6 and Fig. 7 are planar layout diagrams showing the configuration of a pixel of a display device according to one embodiment of the present invention. Fig. 6 is a diagram showing the positional relationship between the anode wiring 22 and the cathode wiring 23 of the LED element 200 and the LED element 200. Fig. 7 is a diagram showing the positional relationship between the members shown in Fig. 6 and the connection wiring 20.

[0053] As shown in FIG. 6, the cathode wiring 23 has a lattice shape expanding in the D1 and D2 directions. An opening 204 is provided in the lattice-shaped cathode wiring 23. The anode wiring 22 is provided in the opening 204. A plurality of anode wirings 22 are provided in one opening 204. The LED element 200 is provided so as to bridge the cathode wiring 23 and the anode wiring 22. In the layout of FIG. 6, the connection electrode 103a and the terminal electrode 203a shown in FIG. 4 are provided in an area overlapping both the anode wiring 22 and the LED element 200. The connection electrode 103b and the terminal electrode 203b shown in FIG. 4 are provided in an area overlapping both the cathode wiring 23 and the LED element 200.

[0054] The anode wiring 22 is provided for each LED element 200. On the other hand, the cathode wiring 23 is provided in common to the multiple LED elements 200. With this configuration, the light emission intensity of the LED element 200 is determined according to the drive current output from the drive transistor 127.

[0055] 7, the connection wiring 20 has an opening 205 that exposes the anode wiring 22. The area in which the opening 205 is provided is located inside the area in which the anode wiring 22 is provided. In other words, the outer edge of the opening 205 is surrounded by the outer edge of the anode wiring 22. In other words, in a plan view, the connection wiring 20 covers the cathode wiring 23 and the gap provided between the anode wiring 22 and the cathode wiring 23 (the area not overlapping with the anode wiring 22 and the cathode wiring 23 in FIG. 6), and further overlaps with the outer edge of the anode wiring 22.

[0056] The patterns of the anode wiring 22 and the cathode wiring 23 shown in Fig. 6 and the pattern of the connection wiring 20 shown in Fig. 7 can prevent the laser light from being irradiated to components in layers below these patterns. In other words, of the laser light irradiated to the entire surface, the laser light irradiated to areas other than the terminal electrode 203 and the connection electrode 103 is blocked by either the anode wiring 22, the cathode wiring 23, or the connection wiring 20. Since the anode wiring 22, the cathode wiring 23, and the connection wiring 20 all have a structure of "Al / Ti," the laser light is reflected by the aluminum on the top surface, and therefore, adverse effects on the transistor elements and the capacitance elements due to heat generation caused by laser irradiation can be prevented.

[0057] <Second embodiment> [Cross-sectional structure of pixel] The configuration of a display device 10 according to one embodiment of the present invention will be described with reference to Figures 8 and 9. The display device according to the second embodiment is similar to the display device according to the first embodiment, but differs from the display device according to the first embodiment in that a conductive layer 25 is provided between the anode wiring 22 and the cathode wiring 23 and the connection electrode 103. In the following description, a description of the parts common to the first embodiment will be omitted, and differences from the first embodiment will be mainly described.

[0058] FIG. 8 is a cross-sectional view showing the configuration of a pixel of a display device according to an embodiment of the present invention. As shown in FIG. 8, a conductive layer 25a is provided between the anode wiring 22 and the connection electrode 103a. Similarly, a conductive layer 25b is provided between the cathode wiring 23 and the connection electrode 103b. The conductive layer 25a is connected to the anode wiring 22 through an opening provided in the insulating layer 24. The conductive layer 25b is connected to the cathode wiring 23 through the opening. An insulating layer 27 is provided on the conductive layers 25a and 25b. The connection electrodes 103a and 103b are provided on the insulating layer 27. The connection electrode 103a is connected to the conductive layer 25a through an opening provided in the insulating layer 27. The connection electrode 103b is connected to the conductive layer 25b through the opening. Parts of the conductive layers 25a and 25b are exposed from the connection electrodes 103a and 103b. That is, in a plan view, parts of the conductive layers 25a and 25b do not overlap with the connection electrodes 103a and 103b.

[0059] FIG. 9 is a partial enlarged view of FIG. 8. FIG. 9 is an enlarged view of the structures of the anode wiring 22, the conductive layer 25a, the connection electrode 103a, and the terminal electrode 203a in FIG. 8. As shown in FIG. 9, the conductive layer 25a includes a first conductive layer 241, a second conductive layer 242, and a third conductive layer 243. The first conductive layer 241 is connected to the second conductive layer 222 of the anode wiring 22 through an opening provided in the insulating layer 24. A part of the third conductive layer 243 is exposed through an opening provided in the insulating layer 27 and is in contact with the first conductive layer 231 of the connection electrode 103a. The second conductive layer 242 is provided between the first conductive layer 241 and the third conductive layer 243.

[0060] The third conductive layer 243 is formed of a third material. The third conductive layer 243 is a layer including the upper surface of the conductive layer 25a. The infrared absorptance of the third material is greater than that of the above-mentioned second material (third conductive layer 233). As described above, the infrared absorptance of the first material (second conductive layer 222) is less than that of the second material, and therefore the infrared absorptance of the third material is the greatest among the first to third materials.

[0061] The first conductive layer 241 is made of a material that has higher heat resistance than the second conductive layer 242, has high adhesion to the lower layer (insulating layer 24), has low contact resistance with the second conductive layer 222 provided under the insulating layer 24, and has low contact resistance with the second conductive layer 242. For example, the first conductive layer 241 is made of tantalum, tungsten, molybdenum, or titanium. The second conductive layer 242 is made of a material that has lower resistance than the first conductive layer 241. For example, aluminum is used for the second conductive layer 242. The third conductive layer 243 is made of a material that satisfies the above characteristics. For example, titanium is used for the third conductive layer 243. The infrared ray absorptance of tin used for the third conductive layer 233 of the connection electrode 103a is about 40%, while the infrared ray absorptance of titanium used for the third conductive layer 243 is about 55%.

[0062] As shown in FIG. 9, when the terminal electrode 203a is placed on the connection electrode 103a and the LED element 200 is irradiated with a laser from above, the laser light is absorbed by the tin provided as the third conductive layer 233 of the connection electrode 103a and the titanium provided as the third conductive layer 243 of the conductive layer 25a. Since the infrared absorption rate of titanium is higher than that of tin, the amount of heat generated per unit area is larger in the conductive layer 25a than in the connection electrode 103a. The conductive layer 25a is prevented from becoming hotter than the connection electrode 103a due to the laser irradiation, or from diffusing heat generated by the connection electrode 103a to the conductive layer 25a due to the temperature rise of the conductive layer 25a. Therefore, the connection electrode 103a and the terminal electrode 203a can be efficiently heated, and the connection electrode 103a and the terminal electrode 203a can be firmly joined.

[0063] In this embodiment, the conductive layer 25a has a laminated structure, but is not limited to this structure. The conductive layer 25a may be a single layer. In this case, if the conductive layer 25a is thin, the heat capacity is small, and the conductive layer 25a may be excessively heated by heat generated by laser irradiation, and the conductive layer 25a may be destroyed. Therefore, when the conductive layer 25a is a single layer, it is necessary to make the film thickness sufficient to increase the heat capacity. For example, when the conductive layer 25a is a single layer, the film thickness may be 1000 nm or more.

[0064] The above-mentioned embodiments (including modifications) of the present invention can be combined as appropriate as long as they are not mutually inconsistent. Those in which a person skilled in the art appropriately adds or removes components or modifies designs, or adds or omits steps or modifies conditions based on the embodiments, are also included in the scope of the present invention as long as they include the gist of the present invention.

[0065] Furthermore, even if there are other effects and advantages different from those brought about by the aspects of each of the above-mentioned embodiments, those that are clear from the description in this specification or that can be easily predicted by a person skilled in the art are naturally understood to be brought about by the present invention. [Explanation of symbols]

[0066] 10: display device, 11: insulating substrate, 12: semiconductor layer, 13: gate insulating layer, 14: gate electrode, 15: insulating layer, 16: source electrode, 17: drain electrode, 18: wiring, 19: planarization layer, 20: connection wiring, 21, 24, 27: insulating layer, 22: anode wiring, 23: cathode wiring, 25: conductive layer, 29: capacitance wiring, 100: circuit board, 103: connection electrode, 110: pixel, 112: display area, 114: peripheral area, 116: terminal area, 120: pixel circuit, 121: data line, 122: gate line, 123: anode power line, 124: cathode power line, 125: drive circuit, 126: selection transistor, 127: drive transistor, 128: storage capacitance, 130: data driver circuit, 140: gate driver circuit, 150: terminal portion, 151, 152: connection wiring, 160: flexible printed circuit board, 170: IC element, 200: LED element, 202: semiconductor layer, 203: terminal electrode, 204, 205: opening, 221, 231, 241: first conductive layer, 222, 232, 242: second conductive layer, 233, 243: third conductive layer

Claims

1. A layer including an upper surface is formed of a first material, and a wiring electrically connected to a transistor of a pixel circuit; a connection electrode, the layer including the upper surface of which is made of a second material and electrically connected to the wiring; an LED element mounted on the connection electrode; an insulating layer covering an upper surface of the wiring and having an opening reaching the wiring; absorptivity of the first material to infrared rays is lower than absorptivity of the second material to infrared rays; the connection electrode is electrically connected to the wiring through the opening, A display device in which the insulating layer has a lower infrared absorptance than the oxide of the first material.

2. the first material is aluminum; The display device according to claim 1 , wherein the insulating layer includes a silicon oxide layer or a silicon nitride layer.

3. A layer including an upper surface is formed of a first material, and wiring electrically connected to a transistor of a pixel circuit; a connection electrode, the layer including the upper surface of which is made of a second material and electrically connected to the wiring; an LED element mounted on the connection electrode; a conductive layer provided under the connection electrode, the conductive layer including an upper surface of the conductive layer being made of a third material; absorptivity of the first material to infrared rays is lower than absorptivity of the second material to infrared rays; When viewed from above, a portion of the conductive layer does not overlap with the connection electrode, A display device in which the third material has a higher infrared absorptivity than the second material.

4. The display device of claim 3 , wherein the third material is titanium.

5. A layer including a top surface is an aluminum layer, a wiring electrically connected to a transistor of a pixel circuit, an insulating layer having an opening and covering an upper surface of the aluminum layer in a region other than the region in which the opening is provided; a connection electrode provided on the insulating layer, the connection electrode including a first conductive layer, a second conductive layer, and a third conductive layer, the connection electrode being electrically connected to the wiring through the opening; an LED element mounted on the connection electrode; The second conductive layer has a barrier property that suppresses diffusion of a material contained in the first conductive layer and a material contained in the third conductive layer.

6. The display device according to claim 5 , wherein the insulating layer includes a silicon oxide layer or a silicon nitride layer.

7. 6. The display device according to claim 5, wherein the aluminum layer has a thickness of 1 [mu]m or more.

8. a conductive layer provided under the connection electrode, the conductive layer including an upper surface being a titanium layer; The display device according to claim 5 , wherein a portion of the titanium layer is exposed from the connection electrode when viewed from above.

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