Lifting and joining methods

Abstract

The invention relates to a method for producing a display device capable of reducing the production time. This method comprises: a displacement step for arranging an anisotropic conductive adhesive layer placed on a transparent substrate material with respect to laser light and a junction board facing each other, and the projection of laser light from the substrate material such that individual portions of the anisotropic conductive adhesive layer are displaced and positioned at predetermined positions on the junction board; and a mounting step for attaching the luminescent elements to the individual portions positioned at predetermined positions on the junction board. Individual portions of the anisotropic conductive adhesive layer can be displaced and positioned with high precision and high efficiency by laser light projection.

Description

Display device manufacturing method

[0001] The present technology relates to a method for manufacturing a display device having an array of light-emitting elements. In particular, the present technology relates to a method for manufacturing a display device having an array of LED elements such as mini LEDs and micro LEDs. This application claims priority based on Japanese Patent Application No. 2021-054138, filed in Japan on March 26, 2021, which is incorporated herein by reference.

[0002] Conventionally, display devices have been proposed in which a plurality of light-emitting elements such as LEDs (Light Emitting Diodes) are arranged to form a light-emitting element array. Patent Document 1 discloses a construction method in which the LEDs are bonded with an anisotropic conductive adhesive such as an ACF (Anisotropic Conductive Film).

[0003] In the method described in Patent Document 1, the ACF is attached to the element mounting surface of the substrate all at once, so the adhesive resin and conductive particles of the ACF remain between the LED pitches. Therefore, when light transmission is required for the light-emitting element array, the light transmission is hindered, and excellent light transmission cannot be achieved.

[0004] On the other hand, if the ACF is attached only directly below the LED, a considerable amount of time is required just for attachment, which worsens the takt time.

[0005] US Patent Application Publication No. 2015 / 0255505

[0006] The present technology has been proposed in view of the above-described conventional situation, and provides a manufacturing method for a display device that can shorten the takt time.

[0007] The manufacturing method of the display device according to the present technology includes a transfer process in which an anisotropic conductive adhesive layer provided on a substrate that is transparent to laser light is placed opposite a wiring board, and laser light is irradiated from the substrate side to transfer and arrange pieces of the anisotropic conductive adhesive layer at predetermined positions on the wiring board, and an implementation process in which light-emitting elements are mounted on the pieces arranged at predetermined positions on the wiring board.

[0008] The manufacturing method of the display device according to the present technology includes a transfer step in which an anisotropic conductive adhesive layer provided on a substrate that is transparent to laser light is opposed to light-emitting elements arranged on a transfer substrate, and laser light is irradiated from the substrate side to transfer pieces of the anisotropic conductive adhesive layer onto the light-emitting elements arranged on the transfer substrate; a re-transfer step in which the light-emitting elements to which the pieces have been transferred are re-transferred onto the wiring substrate; and an implementation step in which the light-emitting elements arranged at predetermined positions on the wiring substrate are mounted via the pieces.

[0009] According to this technology, individual pieces of anisotropic conductive adhesive layers can be transferred and arranged with high precision and efficiency by irradiating them with laser light, thereby shortening the takt time.

[0010] FIG. 1 is a cross-sectional view schematically showing a state in which an anisotropic conductive adhesive layer provided on a substrate and a wiring substrate are opposed to each other. FIG. 2 is a cross-sectional view schematically showing a state in which laser light is irradiated from the substrate side, and individual pieces of the anisotropic conductive adhesive layer are transferred and arranged at predetermined positions on the wiring substrate. FIG. 3 is a cross-sectional view schematically showing a state in which light-emitting elements are mounted on the individual pieces arranged at predetermined positions on the wiring substrate. FIG. 4 is a cross-sectional view schematically showing a state in which laser light is irradiated from the substrate side, and individual pieces of the anisotropic conductive adhesive layer are transferred and arranged at electrode positions on the wiring substrate. FIG. 5 is a cross-sectional view schematically showing a state in which light-emitting elements are mounted on individual pieces arranged on a wiring substrate in electrode units. FIG. 6 is a cross-sectional view schematically showing a state in which an anisotropic conductive adhesive layer provided on a substrate and light-emitting elements arranged on a transfer substrate are opposed to each other. FIG. 7 is a cross-sectional view schematically showing an anisotropic conductive adhesive layer provided on a substrate. Fig. 8 is a cross-sectional view showing a state in which laser light is irradiated from the substrate side to transfer pieces of the anisotropic conductive adhesive layer onto light-emitting elements arranged on a transfer substrate. Fig. 9 is a cross-sectional view showing a state in which the light-emitting elements to which the pieces have been transferred are re-transferred onto a wiring substrate. Fig. 10 is a metallurgical microscope photograph showing pieces of the anisotropic conductive adhesive layer arranged on raw glass. Fig. 11 is an enlarged photograph of the metallurgical microscope photograph shown in Fig. 4.

[0011] Hereinafter, embodiments of the present technology will be described in detail with reference to the drawings in the following order: 1. Display device manufacturing method 2. Examples

[0012] 1. Display Device Manufacturing Method> [First Embodiment] A display device manufacturing method according to a first embodiment includes a transfer step of arranging an anisotropic conductive adhesive layer provided on a laser-transparent substrate and a wiring board opposite each other, and irradiating laser light from the substrate side to transfer and arrange pieces of the anisotropic conductive adhesive layer at predetermined positions on the wiring board, and a mounting step of mounting light-emitting elements on the pieces arranged at the predetermined positions on the wiring board. Because the laser light irradiation allows the pieces of the anisotropic conductive adhesive layer to be transferred and arranged with high precision and high efficiency, it is possible to shorten the takt time.

[0013] Below, with reference to Figures 1 to 3, we will explain the transfer process (A) in which individual pieces of the anisotropic conductive adhesive layer are transferred and arranged at predetermined positions on the wiring board, and the mounting process (B) in which light-emitting elements are mounted on the individual pieces arranged at predetermined positions on the wiring board.

[0014] [Transfer step (A)] Fig. 1 is a cross-sectional view showing a state in which an anisotropic conductive adhesive layer provided on a substrate and a wiring substrate are opposed to each other. As shown in Fig. 1, first, in the transfer step (A), an anisotropic conductive adhesive layer substrate 10 and a wiring substrate 20 are opposed to each other.

[0015] The anisotropic conductive adhesive layer substrate 10 includes a base material 11 and an anisotropic conductive adhesive layer 12, with the anisotropic conductive adhesive layer 12 provided on the surface of the base material 11. The substrate 11 may be any material that is transparent to laser light, and is preferably made of quartz glass, which has high light transmittance over all wavelengths.

[0016] The anisotropic conductive adhesive layer 12 contains, for example, conductive particles 13 in a binder. Furthermore, from the viewpoint of laser transferability, the anisotropic conductive adhesive layer 12 is preferably configured so that the conductive particles 13 are aligned in the plane direction, thereby capturing the particles to achieve electrical continuity and avoiding short circuits. The conductive particles are preferably aligned in a regular array. One example is Japanese Patent No. 6119718. Examples of binders include epoxy adhesives and acrylic adhesives. Among these, epoxy adhesives containing resins with a maximum absorption wavelength in the 180 nm to 360 nm range and high-purity bisphenol A epoxy resins are preferred. A specific example of a high-purity bisphenol A epoxy resin is "YL980" manufactured by Mitsubishi Chemical Corporation. Furthermore, examples of epoxy resin curing agents contained in epoxy adhesives include cationic polymerization initiators and anionic polymerization initiators, such as aromatic sulfonium salts. A specific example of an aromatic sulfonium salt-based cationic polymerization initiator is "SI-60L" manufactured by Sanshin Chemical Industry Co., Ltd. Furthermore, acrylic adhesives utilize radical polymerization reactions and contain, for example, a radically polymerizable substance such as a (meth)acrylate compound and a radical polymerization initiator such as a peroxide. From the perspective of the heat resistance and adhesiveness required during use of the display device, epoxy adhesives are preferred. While a thermosetting anisotropic conductive adhesive layer has been described here, a photocurable anisotropic conductive adhesive layer may also be used if heat exposure in subsequent processes is desired. In this case, a photopolymerization initiator may be used instead of the thermal polymerization initiator described above.

[0017] The conductive particles 13 may be appropriately selected from those used in known anisotropic conductive films, such as nickel (melting point 1455°C), copper (melting point 1085°C), silver (melting point 961.8°C), gold (melting point 1064°C), palladium (melting point 1555°C), tin (melting point 231.9°C), nickel boride (melting point 1230°C), and ruthenium (melting point 1064°C). Examples include metal particles such as tin alloy solder (2334 ° C), metal-coated resin particles in which the surface of resin particles such as polymers containing at least one monomer selected from polyamide, polybenzoguanamine, styrene, and divinylbenzene as a monomer unit is coated with a metal such as nickel, copper, silver, gold, palladium, tin, nickel boride, and ruthenium, and metal-coated inorganic particles in which the surface of inorganic particles such as silica, alumina, barium titanate, zirconia, carbon black, silicate glass, borosilicate glass, lead glass, soda-lime glass, and alumina silicate glass is coated with a metal such as nickel, copper, silver, gold, palladium, tin, nickel boride, and ruthenium. The metal particles may be coated with the above-mentioned metal. Furthermore, the metal layer in the metal-coated resin particles and metal-coated inorganic particles may be a single layer or may be formed from multiple layers of different metals.

[0018] These conductive particles can be coated with insulating particles such as a resin layer, resin particles, or inorganic particles to provide an insulating coating. The particle diameter of the conductive particles 13 varies depending on the area of ​​the electrodes or bumps of the optical element or wiring substrate to be mounted, but is preferably 1 to 30 μm, more preferably 1 to 10 μm, and particularly preferably 1 to 3 μm. When used to mount micro LED elements, the area of ​​the electrodes and bumps is small, so the particle diameter is preferably 1 to 2.5 μm, more preferably 1 to 2.2 μm, and particularly preferably 1 to 2 μm. The particle diameter can be determined by measuring 200 or more particles under a microscope (optical microscope, metallurgical microscope, electron microscope, etc.) and averaging the measurements.

[0019] In addition, in the conductive particles in which the resin particles or inorganic particles are coated with a metal as described above, the metal coating thickness is preferably 0.005 μm or more, more preferably 0.01 μm or more, and preferably 10 μm or less, more preferably 1 μm or less, and even more preferably 0.3 μm or less. When the metal coating is a multi-layer, this coating thickness is the thickness of the entire metal coating. When this coating thickness is above the above lower limit and below the above upper limit, sufficient conductivity is easily obtained, and the conductive particles do not become too hard, making it easy to utilize the properties of the resin particles or inorganic particles described above.

[0020] The coating thickness can be measured, for example, by observing the cross section of the conductive particle using a transmission electron microscope (TEM). The coating thickness is preferably calculated by averaging the coating thickness at five arbitrary locations, and more preferably by averaging the thickness of the entire coating. The coating thickness is preferably determined by calculating the average coating thickness of each of 10 arbitrary conductive particles.

[0021] The conductive particles may have a spherical, ellipsoidal, spike-like, or irregular shape. Among these, spherical conductive particles are preferred because they are easy to control the particle size and particle size distribution. These conductive particles may have protrusions on their surfaces to improve connectivity.

[0022] The thickness of the anisotropic conductive adhesive layer is preferably 1 to 30 μm, more preferably 1 to 10 μm, depending on the height of the electrodes and bumps of the mounted optical element and wiring board, and is preferably 1 to 6 μm, more preferably 1 to 5 μm, and particularly preferably 1 to 4 μm, when used to mount micro LED elements, since the height of the electrodes and bumps is low.

[0023] The anisotropic conductive adhesive layer is preferably formed into a film, and from the viewpoint of ease of handling, the anisotropic conductive adhesive layer is preferably provided with a release film such as a polyethylene terephthalate film on one or both sides thereof.

[0024] The anisotropic conductive adhesive layer can be laminated on the substrate by transferring the anisotropic conductive adhesive layer of these film-like anisotropic conductive adhesive layers to the substrate, or the anisotropic conductive adhesive layer can be laminated on the substrate by producing the anisotropic conductive adhesive layer on the substrate. Methods for producing an anisotropic conductive adhesive layer on a substrate include, for example, a method of applying a solution of an anisotropic conductive adhesive to the substrate and drying it, and a method of forming an adhesive layer that does not contain conductive particles on the substrate and then fixing conductive particles to the resulting adhesive layer.

[0025] The wiring substrate 20 includes a first-conductivity-type circuit pattern and a second-conductivity-type circuit pattern on a base material 21, and has, for example, a first electrode 22 and a second electrode 23 at positions corresponding to a p-side first-conductivity-type electrode and an n-side second-conductivity-type electrode, respectively, so that light-emitting elements are arranged in units of subpixels (sub-pixels) that constitute one pixel. The wiring substrate 20 also includes circuit patterns such as matrix wiring data lines and address lines, which enable the light-emitting elements corresponding to each sub-pixel that constitutes one pixel to be turned on and off. One pixel may be configured, for example, with three sub-pixels of R (red), G (green), and B (blue), four sub-pixels of RGBW (white) and RGBY (yellow), or two sub-pixels of RG and GB. Furthermore, the wiring substrate 20 is preferably a light-transmitting substrate, the base material 21 is preferably glass, PET (Polyethylene Terephthalate), or the like, and the circuit pattern, the first electrode 22, and the second electrode 23 are preferably transparent conductive films such as ITO (Indium-Tin-Oxide), IZO (Indium-Zinc-Oxide), ZnO (Zinc-Oxide), and IGZO (Indium-Gallium-Zinc-Oxide).

[0026] 2 is a cross-sectional view showing a state in which laser light is irradiated from the substrate side, and individual pieces of the anisotropic conductive adhesive layer are transferred and arranged at predetermined positions on the wiring substrate 21. As shown in FIG. 2, in the transfer step (A), laser light is irradiated from the substrate 11 side, and individual pieces 12a of the anisotropic conductive adhesive layer 12 are transferred and arranged at predetermined positions on the wiring substrate 21.

[0027] Here, in order to efficiently transfer the individual pieces of the anisotropic conductive adhesive layer from the substrate, the anisotropic conductive adhesive layer provided on the substrate may be pretreated to form the individual pieces arranged in a matrix. Such pretreatment may involve, for example, forming a grid-like incision in the anisotropic conductive adhesive layer, in which multiple vertical and horizontal incisions intersect. The incisions may be formed mechanically or chemically. Of course, the incisions may also be formed by burning them with laser light. By performing such treatment, multiple individual pieces of the anisotropic conductive adhesive layer can be arranged in a matrix on the substrate, facilitating transfer of the individual pieces with laser light. The incisions do not necessarily need to be deep enough to expose the substrate; even if the incisions are deep enough not to expose the substrate, transferability with laser light is improved. Such pretreatment may be performed after forming the anisotropic conductive adhesive layer on the substrate, or before forming the anisotropic conductive adhesive layer on the substrate, i.e., at the stage of forming the film-like anisotropic conductive adhesive layer.

[0028] In the transfer process (A), the pieces 12a of the anisotropic conductive adhesive layer 12 can be arranged in units of one pixel (for example, one pixel consisting of one set of RGB), or in units of subpixels (for example, any RGB) that make up one pixel. This makes it possible to accommodate light-emitting element arrays with high PPI (Pixels Per Inch) and light-emitting element arrays with low PPI.

[0029] In the transfer step (A), the pieces 12a of the anisotropic conductive adhesive layer 12 are preferably arranged in units of one pixel or multiple pixels. For example, in the case of RGB, the light-emitting elements are arranged in sets of three pixels, or in sets of six pixels including three pixels of the RGB redundant circuit. Therefore, the anisotropic conductive film may be transferred to a set of six pixels, or may be transferred in units of one pixel, or may even be arranged in units of electrodes. On the other hand, to increase productivity, the anisotropic conductive film may be transferred within an area that does not impair transparency, for example, within an area of ​​1 mm x 1 mm.

[0030] In addition, when the individual pieces of the anisotropic conductive adhesive layer are arranged in units of one pixel, the film-shaped anisotropic conductive adhesive layer is made into a tape shape with a width of one pixel, so that the above-mentioned cut can be made in only one direction (the width direction of the tape). This tape width for one pixel does not mean a length equal to the size of one pixel, although it depends on the spacing between pixels, but means a length that does not interfere with adjacent pixels.

[0031] Furthermore, the distance between the pieces arranged at predetermined positions on the wiring board 20 is preferably 3 μm or more, more preferably 5 μm or more, and even more preferably 10 μm or more. The upper limit of the distance between the pieces is preferably 3000 μm or less, more preferably 1000 μm or less, and even more preferably 500 μm or less. If the distance between the pieces is too small, a method of attaching an anisotropic conductive film to the entire surface of the wiring board 20 is preferred, and if the distance between the pieces is too large, a method of attaching an anisotropic conductive film to predetermined positions on the wiring board 20 is preferred. The distance between the pieces can be measured using a microscope (optical microscope, metallurgical microscope, electron microscope, etc.).

[0032] To transfer the individual pieces 12a of the anisotropic conductive adhesive layer 12, for example, a laser induced forward transfer (LIFT) device can be used. The lift device includes, for example, a telescope that collimates pulsed laser light emitted from a laser device, a shaping optical system that uniformly shapes the spatial intensity distribution of the pulsed laser light that has passed through the telescope, a mask that passes the pulsed laser light shaped by the shaping optical system in a predetermined pattern, a field lens positioned between the shaping optical system and the mask, and a projection lens that reduces and projects the laser light that has passed through the mask pattern onto a donor substrate. The anisotropic conductive adhesive layer substrate 10, which serves as the donor substrate, is held on the donor stage, and the wiring substrate 21, which serves as the receptor substrate, is held on the receptor stage. The distance between the anisotropic conductive adhesive layer 12 and the wiring substrate 20 is preferably 10 to 1000 μm, more preferably 50 to 500 μm, and even more preferably 80 to 200 μm.

[0033] The laser device may be, for example, an excimer laser that emits laser light with a wavelength of 180 nm to 360 nm. The oscillation wavelength of the excimer laser is, for example, 193, 248, 308, or 351 nm, and a wavelength can be suitably selected from these depending on the light absorption properties of the material of the anisotropic conductive adhesive layer 12.

[0034] The mask uses a pattern in which an array of windows of a predetermined size is formed at a predetermined pitch so that the desired array of laser light is projected onto the interface between the substrate 11 and the anisotropic conductive adhesive layer 12. The mask has a pattern formed on the substrate 11 by, for example, chrome plating, and the window portions that are not chrome plated transmit the laser light, while the chrome plated portions block the laser light.

[0035] The light emitted from the laser device enters the telescope optical system and then propagates to the shaping optical system. The laser light just before entering the shaping optical system is adjusted by the telescope optical system so that it becomes approximately parallel light at any position within the X-axis movement range of the donor stage, so it always enters the shaping optical system at approximately the same size and angle (perpendicular).

[0036] The laser light that passes through the shaping optical system is incident on the mask via a field lens that, in combination with the projection lens, constitutes an image-side telecentric reduction projection optical system. The laser light that passes through the mask pattern is changed in its propagation direction to vertically downward by an epi-mirror and then incident on the projection lens. The laser light emitted from the projection lens is incident on the substrate 11 side and is accurately projected at a reduced size of the mask pattern onto a predetermined position on the anisotropic conductive adhesive layer 12 formed on the surface (bottom surface) of the substrate 11.

[0037] The pulse energy of the focused laser light irradiated onto the interface between the anisotropic conductive adhesive layer and the substrate is preferably 0.001 to 2 J, more preferably 0.01 to 1.5 J, and even more preferably 0.1 to 1 J. The fluence is preferably 0.001 to 2 J / cm. ２ and more preferably 0.01 to 1 J / cm ２and more preferably 0.05 to 0.5 J / cm ２ The pulse width (irradiation time) is preferably 0.01 to 1×10 ９ picoseconds, more preferably 0.1 to 1×10 7 picoseconds, and more preferably 1 to 1×10 ５ The pulse frequency is preferably 0.1 to 10,000 Hz, more preferably 1 to 1,000 Hz, and even more preferably 1 to 100 Hz. The number of irradiation pulses is preferably 1 to 30,000,000.

[0038] By using such a lifting device, a shock wave is generated in the anisotropic conductive adhesive layer 12 irradiated with laser light at the interface between the substrate 11 and the anisotropic conductive adhesive layer 12, causing the plurality of pieces 12 a to peel off from the substrate 11 and lift toward the wiring substrate 20, and the plurality of pieces 12 a to land at predetermined positions on the wiring substrate 20. This type of transfer method is called laser lift-off, and is a method that uses, for example, laser ablation. This allows the pieces 12 a of the anisotropic conductive adhesive layer 12 to be transferred and arranged on the wiring substrate 20 with high precision and high efficiency, thereby shortening the takt time.

[0039] The reaction rate of the pieces 12a of the anisotropic conductive adhesive layer 12 after the transfer step (A) is preferably 25% or less, more preferably 20% or less, and even more preferably 15% or less. When the reaction rate of the pieces 12a is 25% or less, it becomes possible to thermocompression bond the light-emitting element in the mounting step (B). The reaction rate can be measured using, for example, FT-IR.

[0040] 3 is a cross-sectional view showing a state in which light-emitting elements 30 are mounted on pieces 12a arranged at predetermined positions on a wiring substrate 20. As shown in FIG. 3, in the mounting step (B), light-emitting elements 30 are mounted on pieces 12a arranged at predetermined positions on a wiring substrate 20.

[0041] The light emitting element 30 includes a body 31, a first conductivity type electrode 32, and a second conductivity type electrode 33. The body 31 has a horizontal structure in which the first conductivity type electrode 32 and the second conductivity type electrode 33 are arranged on the same side. The body 31 includes a first conductivity type cladding layer made of, for example, n-GaN, and a second conductivity type cladding layer made of, for example, In. ｘ Al ｙ Ga １－ｘ－ｙ The device has a so-called double heterostructure, comprising an active layer made of an N layer and a second-conductivity-type cladding layer made of, for example, p-GaN. A first-conductivity-type electrode 32 is formed on a portion of the first-conductivity-type cladding layer by a passivation layer, and a second-conductivity-type electrode 33 is formed on a portion of the second-conductivity-type cladding layer. When a voltage is applied between the first-conductivity-type electrode 32 and the second-conductivity-type electrode 33, carriers concentrate in the active layer and recombine, generating light emission.

[0042] The method for mounting the light-emitting element 30 on the wiring substrate 20 is not particularly limited, but examples include a method in which the light-emitting element 30 is directly transferred and disposed on the wiring substrate 20 from a wafer substrate using a laser lift-off (LLO) method, or a method in which the light-emitting element 30 is previously attached to a transfer substrate and then transferred and disposed on the wiring substrate 20 from the transfer substrate. The method for thermocompression bonding the light-emitting element 30 to the wiring substrate 20 can be appropriately selected from connection methods used in known anisotropic conductive films. This allows the light-emitting element 30 to be anisotropically connected to the wiring substrate 20 with the wiring substrate 20 exposed and no anisotropic conductive adhesive layer present between the light-emitting elements 30. Furthermore, by using a light-transmitting substrate as the wiring substrate 20, superior light transmittance can be obtained compared to when an anisotropic conductive film is attached to the entire surface of the wiring substrate 20.

[0043] As described above, according to the manufacturing method of the display device according to the first embodiment, the pieces 12a of the anisotropic conductive adhesive layer 12 can be transferred and arranged on the wiring substrate 20 with high precision and high efficiency by irradiating with laser light, thereby shortening the takt time. In the above-described embodiment, the manufacturing method of the display device as a display is given as an example, but the present technology is not limited thereto and can also be applied to, for example, a manufacturing method of a light-emitting device as a light source.

[0044] [Variation of the first embodiment] In the transfer process (A) in the first embodiment described above, as shown in FIG. 2, the pieces 12a of the anisotropic conductive adhesive layer 12 are arranged on the wiring substrate 21 in units of multiple pixels, in units of one pixel, or in units of subpixels that make up one pixel, but this is not limited to these, and they may also be arranged, for example, in units of electrodes.

[0045] Figure 4 is a cross-sectional view showing the state in which laser light is irradiated from the substrate side, and individual pieces of the anisotropic conductive adhesive layer are transferred and arranged at electrode positions on a wiring substrate, and Figure 5 is a cross-sectional view showing the state in which light-emitting elements are mounted on the individual pieces arranged on the wiring substrate in electrode units.

[0046] 4, in the transfer step (A), first pieces 14 and second pieces 15 are transferred to first electrodes 22 and second electrodes 23 corresponding to, for example, p-side first conductivity type electrodes 32 and n-side second conductivity type electrodes 33 of the light emitting element 30, respectively, and in the mounting step (B), the light emitting element 30 may be mounted on the pieces arranged in electrode units on the wiring substrate 20, as shown in FIG. This can improve the transparency of the display device.

[0047] [Second embodiment] A manufacturing method of a display device according to a second embodiment includes a transfer step of arranging an anisotropic conductive adhesive layer provided on a substrate transparent to laser light and light emitting elements arranged on a transfer substrate opposite each other, and irradiating laser light from the substrate side to transfer pieces of the anisotropic conductive adhesive layer onto the light emitting elements arranged on the transfer substrate, a retransfer step of retransferring the light emitting elements to which the pieces have been transferred onto a wiring substrate, and a mounting step of mounting the light emitting elements arranged at predetermined positions on the wiring substrate via the pieces. Since the pieces of the anisotropic conductive adhesive layer can be transferred and arranged with high precision and high efficiency by irradiating laser light, it is possible to shorten the takt time.

[0048] 6 to 9, the transfer step (A1) of transferring the individual pieces of the anisotropic conductive adhesive layer onto the light emitting elements arranged on the transfer substrate, the re-transfer step (A2) of re-transferring the light emitting elements onto the wiring substrate, and the mounting step (BB) of mounting the light emitting elements arranged at predetermined positions on the wiring substrate via the individual pieces will be described. Note that the same components as those in the first embodiment are designated by the same reference numerals, and their description will be omitted.

[0049] [Transfer step (A1)] Fig. 6 is a cross-sectional view showing a state in which an anisotropic conductive adhesive layer provided on a base material and light-emitting elements arranged on a transfer substrate are opposed to each other, and Fig. 7 is a cross-sectional view showing a state in which an anisotropic conductive adhesive layer provided on a base material is opposed to each other. As shown in Fig. 6, first, in the transfer step (A1), an anisotropic conductive adhesive layer substrate 10 and a transfer substrate 40 are opposed to each other.

[0050] The transfer substrate 40 includes a base material 41 and light-emitting elements 30 arranged on the base material 41. The base material 41 is appropriately selected depending on the transfer method used in the re-transfer step (A2) described below. For example, when using a transfer method that utilizes laser ablation, the base material 41 may be any material that is transparent to laser light, and is preferably quartz glass, which has high light transmittance over all wavelengths. Furthermore, when the transfer substrate 40 is attached to the wiring substrate 20 to transfer the light-emitting elements 30, for example, a silicone rubber layer may be provided.

[0051] In the transfer step (A1), a transfer method using laser ablation, known as laser lift-off, can be used, as in the first embodiment described above. When ablation is used, it is preferable that no conductive particles are present in a region X of the anisotropic conductive adhesive layer 12 that is 0 to 0.05 μm in the thickness direction from the surface on which the base material 11 is provided, as shown in FIG.

[0052] A region X of the anisotropic conductive adhesive layer 12 that is 0 to 0.05 μm in the thickness direction from the surface on which the substrate 11 is provided is strongly affected by ablation. Therefore, it is preferable that no conductive particles are present in this region X. In other words, it is preferable that all conductive particles are present in the part of the anisotropic conductive adhesive layer 12 excluding the region X without protruding. Here, a state in which no conductive particles are present in a certain region means, for example, not only a state in which the entire conductive particles are not present in that region, but also a state in which no part of the conductive particles are present.

[0053] From the viewpoint of productivity of the anisotropic conductive adhesive layer, if conductive particles are mixed into region X, the number of conductive particles mixed into region X is preferably 5% or less of the total number of conductive particles contained in the anisotropic conductive adhesive layer, and more preferably 1% or less.

[0054] Here, the thickness t of region X of the anisotropic conductive adhesive layer 12 may be 0 to 0.05 μm in the thickness direction from the surface on which the substrate 11 is provided. To more reliably suppress conductive particle deterioration due to ablation, this thickness t is preferably 0 to 0.1 μm, more preferably 0 to 0.15 μm, and particularly preferably 0 to 0.2 μm, and conductive particles are preferably not present in this region. In other words, it is preferable that all conductive particles are present in the portions of the anisotropic conductive adhesive layer excluding these regions without protruding. Similarly, from the viewpoint of productivity of the anisotropic conductive adhesive layer, if conductive particles are mixed into these regions, the number of conductive particles mixed into these regions is preferably 5% or less, more preferably 1% or less, of the total number of conductive particles contained in the anisotropic conductive adhesive layer.

[0055] Furthermore, in order to enhance the ablation resistance of the conductive particles, it is preferable that the conductive particles are made of a metal containing a metal having a melting point of 1400° C. or higher, among the metals constituting the conductive particles described above. From the viewpoint of availability, the upper limit of the melting point is preferably about 3500° C. From the same viewpoint, it is preferable that the metal constituting the conductive particles contains nickel, palladium, or ruthenium.

[0056] When using metal-coated resin particles in which the surfaces of resin particles are coated with a metal, or metal-coated inorganic particles in which the surfaces of inorganic particles are coated with a metal, in order to minimize the influence of abrasion on the resin particles or inorganic particles, the thickness of the metal coating is preferably 0.08 μm or more, more preferably 0.1 μm or more, particularly preferably 0.15 μm or more, and most preferably 0.2 μm or more. The upper limit of this coating thickness depends on the diameter of the conductive particles, but is preferably 20% of the conductive particle diameter or about 0.5 μm.

[0057] Such an anisotropic conductive adhesive layer can be applied not only to the second embodiment but also to the first embodiment, its modifications, and other embodiments.

[0058] 8 is a cross-sectional view showing a state in which laser light is irradiated from the substrate side and pieces of the anisotropic conductive adhesive layer are transferred onto light-emitting elements 30 arranged on a transfer substrate. As shown in Fig. 8, in the transfer step (A1), laser light is irradiated from the substrate 11 side, and pieces 16 of the anisotropic conductive adhesive layer 12 are transferred and arranged at predetermined positions on the wiring substrate 21. Laser light is irradiated from the substrate 11 side, and pieces 16 of the anisotropic conductive adhesive layer 12 are transferred onto light-emitting elements 30 arranged on the transfer substrate.

[0059] As in the first embodiment described above, a lifting device, for example, can be used to transfer the pieces 16 of the anisotropic conductive adhesive layer 12. By using the lifting device, a shock wave is generated in the anisotropic conductive adhesive layer 12 irradiated with laser light at the interface between the substrate 11 and the anisotropic conductive adhesive layer 12, and the pieces 16 are peeled off from the substrate 11 and lifted toward the light-emitting elements 30 arranged on the transfer substrate, allowing the pieces 16 to land on the light-emitting elements 30 with high precision, thereby shortening the takt time.

[0060] [Retransfer Step (A2)] Fig. 9 is a cross-sectional view schematically illustrating a state in which the light-emitting element to which the individual pieces 16 have been transferred is retransferred onto a wiring substrate. As shown in Fig. 9, in the retransfer step (A2), the light-emitting element 30 to which the individual pieces 16 have been transferred is retransferred onto the wiring substrate. The retransfer method is not particularly limited, but examples include a method of directly transferring and arranging the light-emitting element 30 to which the individual pieces 16 have been transferred from a transfer substrate 40 to a wiring substrate 20 using a laser lift-off method (LLO method), and a method of transferring and arranging the light-emitting element 30 from a transfer substrate 40 to a wiring substrate 20 using a transfer substrate to which the light-emitting element 30 to which the individual pieces 16 have been transferred has been previously adhered.

[0061] In the retransfer step (A2), it is preferable to transfer the light-emitting elements 30 in units of subpixels that constitute one pixel, which makes it possible to accommodate light-emitting element arrays with a wide range of PPI (Pixels Per Inch) from high to low.

[0062] [Mounting Process (BB)] In the mounting process (BB), the light emitting elements 30 arranged at predetermined positions on the wiring substrate 20 are mounted via the individual pieces 16. The mounted state of the light emitting elements 30 is the same as that shown in FIG. 3. The method for mounting the light emitting elements 30 on the wiring substrate 20 can be appropriately selected and used from a connection method such as thermocompression bonding used in known anisotropic conductive films. This allows the light emitting elements 30 to be anisotropically connected to the wiring substrate 20 in a state where the wiring substrate 20 is exposed without an anisotropic conductive adhesive layer being present between the light emitting elements 30. Furthermore, by using a light-transmitting substrate as the wiring substrate 20, superior light transmittance can be obtained compared to when an anisotropic conductive film is attached to the entire surface of the wiring substrate 20.

[0063] As described above, according to the manufacturing method of the display device of the second embodiment, the individual pieces 16 of the anisotropic conductive adhesive layer 12 can be transferred and arranged on the light-emitting element 30 with high precision and efficiency by irradiating with laser light, thereby shortening the takt time.

[0064] [Modification of the Second Embodiment] In the transfer step (A1) in the second embodiment described above, as shown in Fig. 8, the pieces 16 of the anisotropic conductive adhesive layer 12 are transferred onto the light-emitting element 30. However, this is not limited to this, and for example, the pieces of the anisotropic conductive adhesive layer may be transferred onto the light-emitting element on an electrode-by-electrode basis. That is, the first piece and the second piece may be transferred onto, for example, the p-side first conductivity-type electrode 32 and the n-side second conductivity-type electrode 33 of the light-emitting element 30, respectively. This can improve the transparency of the display device.

[0065] 2. Example In this example, an anisotropic conductive adhesive layer provided on quartz glass was placed opposite a raw glass, and laser light was irradiated from the substrate side to transfer and arrange pieces of the anisotropic conductive adhesive layer at predetermined positions on the raw glass. The pieces arranged on the raw glass were then visually evaluated using a metallurgical microscope. However, this example is not limited to these examples.

[0066] [Preparation of Anisotropic Conductive Adhesive Layer] An anisotropic conductive adhesive layer substrate was prepared by laminating an anisotropic conductive adhesive layer having aligned conductive particles with an average particle size of 2.2 μm onto quartz glass, and providing a 4 μm-thick anisotropic conductive adhesive layer on the quartz glass. The binder for the anisotropic conductive adhesive layer was a mixture of 42 parts by weight of phenoxy resin (product name: PKHH, manufactured by Tomoe Chemical Industry Co., Ltd.), 40 parts by weight of high-purity bisphenol A epoxy resin (product name: YL-980, manufactured by Mitsubishi Chemical Corporation), 10 parts by weight of hydrophobic silica (product name: R202, manufactured by Nippon Aerosil Co., Ltd.), 3 parts by weight of acrylic rubber (product name: SG80H, manufactured by Nagase ChemteX Corporation), and 5 parts by weight of cationic polymerization initiator (product name: SI-60L, manufactured by Sanshin Chemical Industry Co., Ltd.). The mixture was applied to a 50 μm-thick PET film and dried to prepare a resin layer. Conductive particles (average particle size 2.2 μm, resin core metal-coated fine particles, Ni-plated 0.2 μm thick, manufactured by Sekisui Chemical Co., Ltd.) were aligned from the resulting resin layer so that one interface of the resin layer and the conductive particles were approximately aligned by the method described in Patent No. 6187665. The conductive particles were aligned in a hexagonal lattice arrangement in a planar view of the anisotropic conductive adhesive layer so that the distance between conductive particles was twice the particle diameter.

[0067] [Transfer of anisotropic conductive adhesive layer] Using a lifting device (MT-30C200), individual pieces of the anisotropic conductive adhesive layer were transferred to raw glass. As described above, the lifting device includes a telescope that converts pulsed laser light emitted from a laser device into parallel light, a shaping optical system that uniformly shapes the spatial intensity distribution of the pulsed laser light that has passed through the telescope, a mask that passes the pulsed laser light shaped by the shaping optical system in a predetermined pattern, a field lens located between the shaping optical system and the mask, and a projection lens that reduces and projects the laser light that has passed through the mask pattern onto a donor substrate. The anisotropic conductive adhesive layer substrate, which is the donor substrate, is held on the donor stage, and the raw glass, which is the receptor substrate, is held on the receptor stage. The distance between the anisotropic conductive adhesive layer and the raw glass is 100 μm.

[0068] The laser device used was an excimer laser with an oscillation wavelength of 248 nm. The pulse energy of the laser light was 600 J and the fluence was 150 J / cm. ２ The pulse width (irradiation time) was 30,000 picoseconds, the pulse frequency was 0.01 kHz, and the number of irradiation pulses was one pulse per small piece of ACF. The pulse energy of the focused laser light irradiated onto the interface between the anisotropic conductive adhesive layer and the substrate was 0.001 to 2 J, and the fluence was 0.001 to 2 J / cm. ２ and the pulse width (irradiation time) is 0.01 to 1 × 10 ９ The pulse duration was picoseconds, the pulse frequency was 0.1 to 10,000 Hz, and the number of irradiation pulses was 1 to 30,000,000.

[0069] The mask used was a pattern in which an array of windows of a predetermined size was formed at a predetermined pitch so that the projection of laser light onto the interface between the anisotropic conductive adhesive layer of the anisotropic conductive adhesive layer substrate, which is the donor substrate, and the quartz glass would result in an array of laser light of 30 μm vertical x 40 μm horizontal with a vertical pitch of 120 μm and a horizontal pitch of 160 μm.

[0070] [Transfer Evaluation] The reaction rate of the individual pieces of the anisotropic conductive adhesive layer arranged on the raw glass was measured and found to be 17.4%. The reaction rate was determined using FT-IR as the reduction rate of epoxy groups in the individual pieces of the anisotropic conductive adhesive layer. That is, the reduction in the epoxy groups in the individual pieces before transfer due to transfer by laser light was measured by measuring the 914 cm －１ The absorption was measured.

[0071] Fig. 10 is a metallurgical microscope photograph showing individual pieces of the anisotropic conductive adhesive layer arranged on the raw glass, and Fig. 11 is an enlarged photograph of the metallurgical microscope photograph shown in Fig. 10. As shown in Fig. 10 and Fig. 11, it was confirmed that the individual pieces of the anisotropic conductive adhesive layer were transferred onto the raw glass according to the mask pattern. In other words, it was found that the individual pieces of the anisotropic conductive adhesive layer could be transferred and arranged with high precision and high efficiency by irradiating laser light, and that the takt time could be shortened.

[0072] While the embodiments of the present invention have been described in detail above, the present invention can be expressed from different perspectives as follows: (1) to (29) and (U1) to (U18). (1) A method for manufacturing a display device, comprising: a transfer step in which an anisotropic conductive adhesive layer provided on a substrate transparent to laser light is placed opposite a wiring board, and laser light is irradiated from the substrate side to transfer and arrange pieces of the anisotropic conductive adhesive layer at predetermined positions on the wiring board; and a mounting step in which light-emitting elements are mounted on the pieces arranged at predetermined positions on the wiring board. (2) The method for manufacturing a display device according to (1), in which the transfer step arranges the pieces of the anisotropic conductive adhesive layer in units of one pixel. (3) The method for manufacturing a display device according to (1), in which the transfer step arranges the pieces of the anisotropic conductive adhesive layer in units of subpixels that constitute one pixel. (4) The method for manufacturing a display device according to (1), in which the transfer step arranges the pieces of the anisotropic conductive adhesive layer in units of multiple pixels. (5) The method for manufacturing a display device according to (1), wherein, in the transfer step, the pieces of the anisotropic conductive adhesive layer are arranged in units of electrodes of the light-emitting elements. (6) The method for manufacturing a display device according to any one of (1) to (5), wherein the distance between the pieces arranged at predetermined positions on the wiring substrate is 3 μm or more. (7) The method for manufacturing a display device according to any one of (1) to (6), wherein a reaction rate of the pieces after the transfer step is 25% or less. (8) The method for manufacturing a display device according to any one of (1) to (7), wherein the wavelength of the laser light is 180 nm to 360 nm, and the anisotropic conductive adhesive layer contains a resin having a maximum absorption wavelength in the wavelength range of 180 nm to 360 nm. (9) The method for manufacturing a display device according to any one of (1) to (8), wherein the anisotropic conductive adhesive layer contains conductive particles. (10) The method for manufacturing a display device according to any one of (1) to (9), wherein the anisotropic conductive adhesive layer is configured such that the conductive particles are aligned in a surface direction. (11) The method for manufacturing a display device according to (9) or (10), wherein the conductive particles are not present in a region of the anisotropic conductive adhesive layer that is 0 to 0.05 μm in the thickness direction from the surface on which the substrate is provided.(12) The method for manufacturing a display device according to any one of (9) to (11), wherein the conductive particles are metal-coated resin particles obtained by coating the surfaces of resin particles with a metal, or metal-coated inorganic particles obtained by coating the surfaces of resin inorganic particles with a metal, and the metal coating thickness is 0.15 μm or more. (13) The method for manufacturing a display device according to any one of (9) to (12), wherein the metal constituting the conductive particles includes a metal having a melting point of 1400° C. or more. (14) The method for manufacturing a display device according to any one of (9) to (12), wherein an anisotropic conductive adhesive layer provided on a base material that is transparent to laser light is opposed to light-emitting elements arranged on a transfer substrate, and laser light is irradiated from the base material side to transfer pieces of the anisotropic conductive adhesive layer onto the light-emitting elements arranged on the transfer substrate, a re-transfer step of re-transferring the light-emitting elements to which the pieces have been transferred onto the wiring substrate, and a mounting step of mounting the light-emitting elements arranged at predetermined positions on the wiring substrate via the pieces. (15) The method for manufacturing a display device according to (14), wherein the transfer step involves transferring the pieces of the anisotropic conductive adhesive layer onto the light-emitting elements on an electrode-by-electrode basis. (16) The method for manufacturing a display device according to (14) or (15), wherein the re-transfer step involves transferring the light-emitting elements on a subpixel-by-subpixel basis, each of which constitutes one pixel. (17) A method for manufacturing a wiring board with an anisotropic conductive adhesive layer, comprising the steps of: arranging an anisotropic conductive adhesive layer provided on a substrate opposite a wiring board; and irradiating laser light from the substrate side to transfer the pieces of the anisotropic conductive adhesive layer to predetermined positions on the wiring board. (18) A method for manufacturing a light-emitting element with an anisotropic conductive adhesive layer, comprising the steps of: arranging an anisotropic conductive adhesive layer provided on a substrate opposite light-emitting elements arranged on a transfer substrate; and irradiating laser light from the substrate side to transfer the pieces of the anisotropic conductive adhesive layer onto the light-emitting elements arranged on the transfer substrate. (19) A film-like anisotropic conductive adhesive layer used for transfer by laser lift-off. (20) The film-shaped anisotropic conductive adhesive layer according to (19), which contains conductive particles. (21) The film-shaped anisotropic conductive adhesive layer according to (20), which is free of the conductive particles in a region of 0 to 0.05 μm in the thickness direction from the surface on the substrate side that is provided during transfer by laser lift-off.(22) The film-shaped anisotropic conductive adhesive layer according to (20) or (21), wherein the conductive particles are metal-coated resin particles in which the surfaces of resin particles are coated with a metal, or metal-coated inorganic particles in which the surfaces of resin inorganic particles are coated with a metal, and the thickness of the metal coating is 0.15 μm or more. (23) The film-shaped anisotropic conductive adhesive layer according to any one of (20) to (22), wherein the metal constituting the conductive particles includes a metal having a melting point of 1400° C. or more. (24) The film-shaped anisotropic conductive adhesive layer according to any one of (20) to (23), wherein the metal constituting the conductive particles includes nickel, palladium, or ruthenium. (25) A substrate laminated with an anisotropic conductive adhesive layer used for transfer by laser lift-off. (26) Application of the anisotropic conductive adhesive layer to an anisotropic conductive adhesive layer for laser lift-off transfer. (27) Application of the anisotropic conductive adhesive layer for producing an anisotropic conductive adhesive layer for laser lift-off transfer. (28) Application of an anisotropic conductive adhesive layer to the manufacture of a substrate on which an anisotropic conductive adhesive layer is laminated, the substrate being used for transfer by laser lift-off. (29) Application of an anisotropic conductive adhesive layer to laser lift-off. (U1) A display device manufacturing system comprising: a transfer mechanism that places an anisotropic conductive adhesive layer provided on a substrate that is transparent to laser light opposite a wiring substrate, and irradiates laser light from the substrate side to transfer and arrange pieces of the anisotropic conductive adhesive layer at predetermined positions on the wiring substrate; and a mounting mechanism that mounts light-emitting elements on the pieces arranged at predetermined positions on the wiring substrate. (U2) The display device manufacturing system described in (U1), in which the transfer mechanism arranges the pieces of the anisotropic conductive adhesive layer in units of one pixel. (U3) The display device manufacturing system described in (U1), in which the transfer mechanism arranges the pieces of the anisotropic conductive adhesive layer in units of subpixels that make up one pixel. (U4) The display device manufacturing system according to (U1), wherein the transfer mechanism arranges the pieces of the anisotropic conductive adhesive layer in units of multiple pixels. (U5) The display device manufacturing system according to (U1), wherein the transfer mechanism arranges the pieces of the anisotropic conductive adhesive layer in units of electrodes of the light-emitting elements. (U6) The display device manufacturing system according to any one of (U1) to (U5), wherein the distance between the pieces arranged at predetermined positions on the wiring substrate is 3 μm or more.(U7) The display device manufacturing system according to any one of (U1) to (U6), wherein a reaction rate of the individual pieces after transfer by the transfer mechanism is 25% or less. (U8) The display device manufacturing system according to any one of (U1) to (U7), wherein the wavelength of the laser light is 180 nm to 360 nm, and the anisotropic conductive adhesive layer contains a resin having a maximum absorption wavelength in the wavelength range of 180 nm to 360 nm. (U9) The display device manufacturing system according to any one of (U1) to (U8), wherein the anisotropic conductive adhesive layer contains conductive particles. (U10) The display device manufacturing system according to (U9), wherein the anisotropic conductive adhesive layer is configured by aligning the conductive particles in a surface direction. (U11) The display device manufacturing system according to (U9) or (U10), wherein the conductive particles are not present in a region of the anisotropic conductive adhesive layer that is 0 to 0.05 μm in a thickness direction from the surface on which the base material is provided. (U12) The display device manufacturing system according to any one of (U9) to (U11), wherein the conductive particles are metal-coated resin particles in which the surfaces of resin particles are coated with a metal, or metal-coated inorganic particles in which the surfaces of inorganic particles are coated with a metal, and wherein the metal coating thickness is 0.15 μm or more. (U13) The display device manufacturing system according to any one of (U9) to (U12), wherein the metal constituting the conductive particles includes a metal having a melting point of 1400° C. or more. (U14) A display device manufacturing system comprising: a transfer mechanism that positions an anisotropic conductive adhesive layer provided on a base material that is transparent to laser light opposite light-emitting elements arranged on a transfer substrate, and irradiates laser light from the base material side to transfer pieces of the anisotropic conductive adhesive layer onto the light-emitting elements arranged on the transfer substrate; a re-transfer mechanism that re-transfers the light-emitting elements to which the pieces have been transferred onto the wiring substrate; and a mounting mechanism that mounts the light-emitting elements arranged at predetermined positions on the wiring substrate via the pieces. (U15) The display device manufacturing system according to (U14), wherein the transfer mechanism transfers the individual pieces of the anisotropic conductive adhesive layer onto the light-emitting element on an electrode-by-electrode basis. (U16) The display device manufacturing system according to (U14) or (U15), wherein the retransfer mechanism transfers the light-emitting element on a subpixel-by-subpixel basis, which constitutes one pixel.(U17) A manufacturing system for a wiring board with an anisotropic conductive adhesive layer, the system having a mechanism for opposing an anisotropic conductive adhesive layer provided on a substrate to a wiring board and irradiating laser light from the substrate side to transfer pieces of the anisotropic conductive adhesive layer to predetermined positions on the wiring board. (U18) A manufacturing system for a light-emitting element with an anisotropic conductive adhesive layer, the system having a transfer mechanism for opposing an anisotropic conductive adhesive layer provided on a substrate to light-emitting elements arranged on a transfer substrate and irradiating laser light from the substrate side to transfer pieces of the anisotropic conductive adhesive layer onto the light-emitting elements arranged on the transfer substrate.

[0073] Each of the constituent elements in the many embodiments described above can be subdivided, and the subdivided constituent elements can be introduced into these (1) to (29) and (U1) to (U18) either alone or in combination.

[0074] REFERENCE SIGNS LIST 10 Substrate, 11 Base material, 12 Anisotropic conductive adhesive layer, 12a Piece, 13 Conductive particles, 20 Wiring substrate, 21 Base material, 22 First electrode, 23 Second electrode, 30 Light-emitting element, 31 , 32 First conductivity type electrode, 33 Second conductivity type electrode, 40 Transfer substrate, 41 Base material

Claims

1. A method for manufacturing a display device, comprising: a transfer step in which an anisotropic conductive adhesive layer provided on a substrate that is transparent to laser light is placed opposite a wiring board, and laser light is irradiated from the substrate side to transfer and arrange pieces of the anisotropic conductive adhesive layer at predetermined positions on the wiring board; and a mounting step in which light-emitting elements are mounted on the pieces arranged at the predetermined positions on the wiring board.

2. The method for manufacturing a display device according to claim 1, wherein in the transferring step, the individual pieces of the anisotropic conductive adhesive layer are arranged in units of one pixel.

3. The method for manufacturing a display device according to claim 1, wherein in the transferring step, the individual pieces of the anisotropic conductive adhesive layer are arranged in units of subpixels that make up one pixel.

4. The method for manufacturing a display device according to claim 1, wherein in the transferring step, the individual pieces of the anisotropic conductive adhesive layer are arranged in units of a plurality of pixels.

5. The method for manufacturing a display device according to claim 1, wherein in the transferring step, the individual pieces of the anisotropic conductive adhesive layer are arranged in units of electrodes of the light-emitting elements.

6. The method for manufacturing a display device according to any one of claims 1 to 5, wherein the distance between the pieces arranged at predetermined positions on the wiring board is 3 µm or more.

7. The method for manufacturing a display device according to any one of claims 1 to 6, wherein the reaction rate of the individual pieces after the transfer step is 25% or less.

8. A method for manufacturing a display device according to any one of claims 1 to 7, wherein the wavelength of the laser light is 180 nm to 360 nm, and the anisotropic conductive adhesive layer contains a resin having a maximum absorption wavelength in the wavelength range of 180 nm to 360 nm.

9. A method for manufacturing a display device according to any one of claims 1 to 8, wherein the anisotropic conductive adhesive layer contains conductive particles.

10. The method for manufacturing a display device according to claim 9, wherein the anisotropic conductive adhesive layer is configured such that the conductive particles are aligned in the surface direction.

11. The method for manufacturing a display device according to claim 9 or 10, wherein the conductive particles are not present in a region of the anisotropic conductive adhesive layer that is 0 to 0.05 μm in the thickness direction from the surface on which the substrate is provided.

12. A method for manufacturing a display device according to any one of claims 9 to 11, wherein the conductive particles are metal-coated resin particles in which the surface of resin particles is coated with metal, or metal-coated inorganic particles in which the surface of inorganic particles is coated with metal, and the thickness of the metal coating is 0.15 μm or more.

13. The method for manufacturing a display device according to any one of claims 9 to 12, wherein the metal constituting the conductive particles includes a metal having a melting point of 1400°C or higher.

14. A method for manufacturing a display device, comprising: a transfer step in which an anisotropic conductive adhesive layer provided on a substrate transparent to laser light is placed opposite light emitting elements arranged on a transfer substrate, and laser light is irradiated from the substrate side to transfer pieces of the anisotropic conductive adhesive layer onto the light emitting elements arranged on the transfer substrate; a retransfer step in which the light emitting elements to which the pieces have been transferred are retransferred onto the wiring substrate; and a mounting step in which the light emitting elements arranged at predetermined positions on the wiring substrate are mounted via the pieces.

15. The method for manufacturing a display device according to claim 14, wherein in the transferring step, the individual pieces of the anisotropic conductive adhesive layer are transferred onto the light-emitting element in units of electrodes.

16. The method for manufacturing a display device according to claim 14 or 15, wherein in the retransfer step, the light-emitting elements are transferred in units of subpixels that constitute one pixel.

17. A method for manufacturing a wiring board with an anisotropic conductive adhesive layer, comprising the steps of: arranging an anisotropic conductive adhesive layer provided on a substrate opposite a wiring board; and irradiating laser light from the substrate side to transfer individual pieces of the anisotropic conductive adhesive layer to predetermined positions on the wiring board.

18. A method for manufacturing a light-emitting element with an anisotropic conductive adhesive layer, comprising a transfer step in which an anisotropic conductive adhesive layer provided on a substrate is placed opposite light-emitting elements arranged on a transfer substrate, and laser light is irradiated from the substrate side to transfer individual pieces of the anisotropic conductive adhesive layer onto the light-emitting elements arranged on the transfer substrate.

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