Manufacturing method of individual film, individual film, manufacturing method of connection structure and connection structure

Abstract

To provide a manufacturing method of an individual film capable of obtaining excellent shape accuracy by suppressing a curing reaction, an individual film, a manufacturing method of a connection structure and a connection structure.SOLUTION: Drawing is performed by irradiating a curable resin film with an ultrashort pulse laser beam, and the curable resin film is individualized into individual films in a predetermined shape. It is preferable that a pulse width of the ultrashort pulse laser beam is from 10 to 1,000 fs and it is preferable that fluence of one pulse of the ultrashort pulse laser beam is from 0.1 to 1 J / cm2. Thus, excellent shape accuracy can be obtained by suppressing a curing reaction.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present technology relates to a manufacturing method for individual film pieces for processing curable resin films such as conductive films, anisotropic conductive films (ACFs), and non-conductive films (NCFs), as well as a manufacturing method for a connection structure using individual film pieces and the connection structure. [Background technology]

[0002] In recent years, micro LED (Light Emitting Diode) displays have been attracting attention as the next generation of displays. Applications of micro LED displays include smart watches, smartphones, large displays (TVs (television), signage, etc.), and they are also being considered for use in transparent displays, smart glasses, and other VR (Virtual Reality) / AR (Augmented Reality) devices.

[0003] There are methods for connecting micro LEDs to display wiring boards, such as soldering and eutectic, but the development of connection methods using ACF is also progressing. For example, Patent Document 1 describes a method in which laser light is irradiated from the substrate side, shock waves are generated at the interface between the substrate and the curable resin film, and part of the curable resin is peeled off and removed from the substrate, forming multiple pieces made of the curable resin film on the substrate.

[0004] However, in the technology of Patent Document 1, the removed portion of the curable resin film is blown off from the substrate by shock waves, which restricts the space between pieces (the area to be removed for individualization), resulting in a limit to the yield of the pieces. In addition, in the technology of Patent Document 1, although it is possible to reduce the space between pieces by increasing the laser energy, the curing reaction of the pieces advances. Furthermore, in the technology of Patent Document 1, the removed portion is blown off to form the pieces, which makes the shapes of the pieces non-uniform, making it difficult to obtain excellent shape precision of the pieces. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent Publication No. 2022-151818 Summary of the Invention [Problem to be solved by the invention]

[0006] The present technology has been proposed in consideration of the current situation, and provides a method for manufacturing an individual film and an individual film that can suppress the curing reaction and obtain excellent shape accuracy, as well as a method for manufacturing a connection structure and a connection structure. [Means for solving the problem]

[0007] In the method for producing an individual film according to the present technology, an ultrashort pulse laser light is irradiated onto a curable resin film to form an image, and the curable resin film is divided into individual film pieces having a predetermined shape.

[0008] The film piece according to the present technology contains a curable resin, and the angle of the side surface with respect to the first surface is 70° or more.

[0009] A manufacturing method for a connection structure according to the present technology includes an arrangement step of arranging a first electronic component and a second electronic component via an individual film that contains a curable resin and has a side angle of 70° or more relative to a first surface, and a curing step of crimping the first electronic component and the second electronic component with a crimping tool and curing the individual film.

[0010] The connection structure according to the present technology comprises a first electronic component, a second electronic component, and a cured film connecting the first electronic component and the second electronic component, the cured film containing a curable resin and formed by curing an individual film having a side surface at an angle of 70° or more relative to a first surface. Effect of the Invention

[0011] According to the present technology, it is possible to suppress the hardening reaction during processing, and to obtain excellent shape accuracy. [Brief description of the drawings]

[0012] [Figure 1] FIG. 1 is a cross-sectional view that illustrates a state in which a curable resin film is irradiated with ultrashort pulsed laser light. [Diagram 2] FIG. 2 is a cross-sectional view that illustrates an example of an individual film processed by an ultrashort pulse laser. [Diagram 3] FIG. 3 is a plan view illustrating a schematic example of an end shape of a film piece. [Figure 4] Figure 4 is a plan view showing a first example of the shape of an individual film, where Figure 4(A) shows a rectangular individual film, Figure 4(B) shows a square individual film, Figure 4(C) shows an oval individual film, and Figure 4(D) shows a circular individual film. [Diagram 5] Figure 5 is a plan view showing a second example of the shape of an individual film, where Figure 5(A) shows a rectangular individual film, Figure 5(B) shows a square individual film, Figure 5(C) shows an oval individual film, and Figure 5(D) shows a circular individual film. [Figure 6] 6A and 6B are plan views showing a schematic diagram of a first example of a method for producing individual pieces of conductive film, where FIG. 6A shows the conductive film before processing, and FIG. 6B shows the individual film pieces after processing. [Figure 7] Figure 7 is a plan view showing a schematic diagram of a second example of a method for producing individual pieces of conductive film, where Figure 7(A) shows the curable resin film before processing, Figure 7(B) shows the curable resin film after processing, Figure 7(C) shows a conductive particle transfer mold, and Figure 7(D) shows an individual piece of film after transfer. [Figure 8]Figure 8 is a plan view showing a schematic diagram of a third example method for manufacturing individual pieces of conductive film, where Figure 8(A) shows a first curable resin film before processing, Figure 8(B) shows the first curable resin film after processing, Figure 8(C) shows a conductive particle transfer mold, Figure 8(D) shows the first individual film after transfer, Figure 8(E) shows the second curable resin film before processing, Figure 8(F) shows the second curable resin film after processing, Figure 8(G) shows the conductive particle transfer mold, and Figure 8(H) shows the second individual film after transfer. [Figure 9] FIG. 9 is a diagram illustrating an example of a laser lift-off apparatus. [Figure 10] FIG. 10 is a cross-sectional view that typically shows a state in which a film piece and a wiring board are opposed to each other. [Figure 11] FIG. 11 is a cross-sectional view that shows a schematic state in which laser light is irradiated from the base material side, and individual pieces of the conductive film are transferred and arranged at predetermined positions on the wiring board. [Figure 12] FIG. 12 is a cross-sectional view that typically shows a state in which light-emitting elements are mounted on pieces that are arranged at predetermined positions on a wiring board. [Figure 13] FIG. 13 is a micrograph including pieces with poor shapes due to insufficient processing, chipping, and curling. [Figure 14] FIG. 14 is a micrograph of an individual film obtained by dividing the conductive film in Example 1. As shown in FIG. [Figure 15] FIG. 15 is a micrograph of the film piece transferred to the substrate using the laser lift-off apparatus in Example 1. As shown in FIG. [Figure 16] FIG. 16 is a micrograph of an individual film obtained by dividing the conductive film in Example 2. As shown in FIG. [Figure 17] FIG. 17 is a micrograph of an individual film piece transferred to a substrate using a laser lift-off apparatus in Example 2. As shown in FIG. [Figure 18] FIG. 18 is a micrograph of an individual film obtained by cutting the conductive film in Comparative Example 1. As shown in FIG. [Figure 19]FIG. 19 is a micrograph of an individual film piece transferred to a substrate using a laser lift-off apparatus in Comparative Example 1. As shown in FIG. [Figure 20] FIG. 20 is a micrograph of an individual film obtained by cutting the conductive film in Comparative Example 2. As shown in FIG. [Figure 21] FIG. 21 is a micrograph of a film piece transferred to a substrate using a laser lift-off apparatus in Comparative Example 2. As shown in FIG. [Figure 22] FIG. 22 is a micrograph of an individual film obtained by cutting the conductive film in Comparative Example 3. As shown in FIG. [Figure 23] FIG. 23 is a micrograph of a film piece transferred to a substrate using a laser lift-off apparatus in Comparative Example 3. As shown in FIG. [Figure 24] FIG. 24 is an enlarged microscope photograph of the film piece in Example 1. [Diagram 25] FIG. 25 is a binarized image of the magnified micrograph shown in FIG. [Figure 26] FIG. 26 is an enlarged microscope photograph of the film piece in Comparative Example 1. [Figure 27] FIG. 27 is a binarized image of the magnified micrograph shown in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, embodiments of the present technology will be described in detail with reference to the drawings in the following order. 1. Manufacturing method of individual film and individual film 2. Method for manufacturing connection structure and connection structure 3. First Example 4. Second Example

[0014] <1. Manufacturing method of individual film and individual film> The method for producing an individual film according to the present embodiment involves irradiating an ultrashort pulse laser light onto a curable resin film to draw an image thereon, and dividing the curable resin film into individual films of a predetermined shape. This makes it possible to suppress the curing reaction of the individual film, and to obtain excellent shape accuracy. In this specification, the "individual film" is also referred to simply as "individual piece". Furthermore, "shape accuracy" refers to the degree of conformity between an actual geometric shape and an ideal geometric shape.

[0015] Fig. 1 is a cross-sectional view showing a schematic state of a curable resin film irradiated with ultrashort pulsed laser light. As shown in Fig. 1, first, a curable resin film 2 is formed on a substrate 1. The curable resin film 2 can be formed by using a known method such as mixing, coating, and drying. Then, an ultrashort pulsed laser LD is irradiated onto the curable resin film 2 to draw, and the material of the curable resin film 2 is explosively scattered and evaporated (laser ablation), thereby forming individual pieces of a predetermined shape on the substrate 1.

[0016] (base material) The substrate 1 is not particularly limited, and examples thereof include glass, PET (Poly Ethylene Terephthalate), OPP (Oriented Polypropylene), PMP (Poly-4-methylpentene-1), and PTFE (Polytetrafluoroethylene). The substrate 1 may preferably be one in which at least the surface on the side of the curable resin film 2 is subjected to a release treatment with, for example, a silicone resin (a substrate subjected to a release treatment). When the ultrashort pulse laser light is irradiated from the substrate 1 side, the substrate 1 may be any substrate that is transparent to the laser light, and is preferably made of quartz glass or borosilicate glass that has a high light transmittance over the entire wavelength range (a substrate that is transparent to the laser light, a glass substrate).

[0017] (curable resin film) The curable resin film 2 is not particularly limited as long as it is cured by energy such as heat or light, and can be appropriately selected from, for example, a thermosetting binder, a photocurable binder, a thermo- and photo-curable binder, and the like. Examples of the thermosetting binder include a thermo-anionic polymerization resin composition containing an epoxy compound and a thermo-anionic polymerization initiator, a thermo-cationic polymerization resin composition containing an epoxy compound and a thermo-cationic polymerization initiator, and a thermo-radical polymerization resin composition containing a (meth)acrylate compound and a thermo-radical polymerization initiator. Examples of the photocurable binder include a photo-cationic polymerization resin composition containing an epoxy compound and a photo-cationic polymerization initiator, and a thermo-radical polymerization resin composition containing a (meth)acrylate compound and a photo-radical polymerization initiator. Examples of the thermo- and photo-curable binder include a thermo- and photo-cationic polymerization resin composition containing an epoxy compound and a thermo- and photo-cationic polymerization initiator. The (meth)acrylate compound is meant to include both acrylic monomers (oligomers) and methacrylic monomers (oligomers).

[0018] Among these, it is preferable to use a thermosetting binder from the viewpoint of suppressing a curing reaction caused by laser light. In the following, a specific example will be described using a thermal cationic polymerization type resin composition containing a film-forming resin, an epoxy compound, and a thermal cationic polymerization initiator.

[0019] Examples of the film-forming resin include various resins such as phenoxy resin, polyester resin, polyurethane resin, polyester urethane resin, acrylic resin, polyimide resin, butyral resin, etc., preferably having a weight average molecular weight of about 10,000 to 80,000 from the viewpoint of film-forming properties, and these may be used alone or in combination of two or more. Among these, it is preferable to use phenoxy resin from the viewpoint of film formation state, connection reliability, etc. A specific example of the phenoxy resin is, for example, the product name "YP-50" manufactured by Nippon Steel Chemical & Material Co., Ltd. The content of the film-forming resin is preferably 20 parts by mass or more, more preferably 25 parts by mass or more, and even more preferably 35 parts by mass or more, and is preferably 50 parts by mass or less, more preferably 45 parts by mass or less, and even more preferably 40 parts by mass or less, relative to 100 parts by mass of the thermosetting binder.

[0020] The epoxy compound is not particularly limited as long as it is an epoxy compound having one or more epoxy groups in the molecule, and may be, for example, a bisphenol A type epoxy resin, a bisphenol F type epoxy resin, or a urethane-modified epoxy resin. A specific example of the bisphenol A type epoxy resin is, for example, a product name "YD-019" manufactured by Nippon Steel Chemical & Material Co., Ltd. A specific example of the high-purity bisphenol A type epoxy resin is, for example, a product name "YL980" manufactured by Mitsubishi Chemical Corporation. A specific example of the hydrogenated bisphenol A glycidyl ether is, for example, a product name "YX8000" manufactured by Mitsubishi Chemical Corporation. The content of the epoxy compound is preferably 30 parts by mass or more, more preferably 35 parts by mass or more, and preferably 60 parts by mass or less, more preferably 55 parts by mass or less, and even more preferably 45 parts by mass or less, relative to 100 parts by mass of the thermosetting binder.

[0021] As the thermal cationic polymerization initiator, a known initiator for thermal cationic polymerization of an epoxy compound can be used. For example, it is an initiator that generates an acid capable of cationic polymerization of a cationic polymerization type compound by heat, and known iodonium salts, sulfonium salts, phosphonium salts, ferrocenes, etc. can be used. Among these, aromatic sulfonium salts that show good latency against temperature can be preferably used. A specific example of an aromatic sulfonium salt-based polymerization initiator is the product name "SI-60L" manufactured by Sanshin Chemical Industry Co., Ltd. The content of the thermal cationic polymerization initiator is preferably 1 part by mass or more, more preferably 2 parts by mass or more, even more preferably 3 parts by mass or more, preferably 10 parts by mass or less, more preferably 8 parts by mass or less, and even more preferably 6 parts by mass or less, relative to 100 parts by mass of the thermosetting binder.

[0022] Other additives that may be added to the thermosetting binder, if necessary, include inorganic fillers, rubber components, silane coupling agents, diluting monomers, bulking agents, softeners, colorants, flame retardants, and thixotropic agents.

[0023] The curable resin film 2 may be a conductive film containing conductive particles. The conductive film may be anisotropic or isotropic (it may be an anisotropic conductive film or a non-anisotropic conductive film). The conductive film preferably has conductive particles aligned in the plane direction. In other words, the conductive film is preferably regularly arranged. By aligning the conductive particles in the plane direction, it becomes easier to design a uniform particle surface density, and the conductivity and insulation properties can be improved. The state in which the conductive particles are aligned in the plane direction includes, for example, a planar lattice pattern having one or more arrangement axes in which the conductive particles are arranged in a predetermined direction at a predetermined pitch, and examples of such patterns include an oblique lattice, a hexagonal lattice, a square lattice, a rectangular lattice, and a parallelepiped lattice. The fact that the conductive particles are aligned in the plane direction may be rephrased as the conductive particles being aligned in the plane view of the film. The arrangement of the conductive particles in the plane direction may be random, or may have a plurality of regions with different planar lattice patterns. It is preferable that 95% or more of the conductive particles are not in contact with each other, but the conductive particles may intentionally form a unit consisting of a plurality of particles in contact with each other.

[0024] The particle surface density of the anisotropic conductive film can be appropriately designed according to the size of the electrode to be connected. There is no particular lower limit to the particle surface density, but it is preferably 30 particles / mm 2 More than 500 pieces / mm 2 More than 20000 pieces / mm 2 More than 40000 pieces / mm 2 More than 50000 pieces / mm 2 or more, and the upper limit of the particle surface density is 1,500,000 particles / mm 2 Below, 1000000 pieces / mm 2 Below 500000 pieces / mm 2 Below 100000 pieces / mm 2 The particle surface density can be as follows. This makes it possible to obtain excellent conductivity and insulation even when the size of the electrode to be connected is small. The particle surface density of the conductive film is that of the arranged portion of the conductive particles when the conductive particles are formed into a film during production. When calculating the particle number density from a plurality of individual pieces, the particle surface density can be calculated from the area obtained by excluding the spaces between the individual pieces from the area including the individual pieces and the spaces, and the number of particles.

[0025] (Conductive particles) The conductive particles may be appropriately selected from those used in known anisotropic conductive films. For example, the conductive particles may be metal particles including alloy particles 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), ruthenium (melting point: 2334°C), and solder, which is a tin alloy. The metal particles may be metal-coated metal particles coated with metals such as nickel, copper, silver, gold, palladium, tin, nickel boride, and ruthenium, or alloys such as solder. In addition, the surface of resin particles such as polymers containing at least one monomer selected from polyamide, polybenzoguanamine, styrene, and divinylbenzene as a monomer unit may be coated with a metal such as nickel, copper, silver, gold, palladium, tin, nickel boride, ruthenium, or an alloy such as solder. In addition, 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 may be coated with a metal such as nickel, copper, silver, gold, palladium, tin, nickel boride, ruthenium, or an alloy such as solder. In addition, the metal coating layer in the metal-coated metal particles, metal-coated resin particles, and metal-coated inorganic particles may be a single layer or may be formed from a multilayer of different metals. In addition, the conductive particles may be insulating-coated conductive particles that have been subjected to an insulating coating treatment by coating them with insulating particles such as resin layers, resin particles, and inorganic particles.

[0026] The conductive particles may have a spherical, ellipsoidal, spike-like, irregular shape, etc. Among these, spherical conductive particles are preferred because the particle size and particle size distribution can be easily controlled. The conductive particles may have protrusions on the surface to improve connectivity.

[0027] The particle diameter of the conductive particles is appropriately selected depending on the area of ​​the electrodes and bumps of the optical element or wiring board to be mounted, and is preferably 1 to 30 μm, more preferably 1 to 10 μm, and particularly preferably 1 to 3 μm. When used to mount a micro LED element, the area of ​​the electrodes and bumps is small, so the particle diameter of the conductive particles is preferably 1 to 2.5 μm, more preferably 1 to 2.2 μm, and particularly preferably 1 to 2 μm. The particle diameter of the conductive particles can be a value measured by an image type particle size distribution meter (for example, FPIA-3000: manufactured by Malvern Instruments). The number is preferably 1000 or more, preferably 2000 or more. When the particle diameter is obtained from a film, it may be obtained from image observation of an electron microscope such as SEM. The number of particles to be measured is 50 or more, preferably 200 or more. These particle diameters may be considered as average particle diameters.

[0028] (Measurement of individual piece reaction rate) In the case of a curable resin film that utilizes the reaction of an epoxy compound, for example, the methyl group (2930 cm) in the IR spectrum is detected using FT-IR. -1 near 914cm -1 The peak heights of the epoxy groups (near the methyl group peak) are measured, and the ratio of the peak height of the epoxy groups before and after the reaction (for example, before and after laser irradiation) to the peak height of the methyl groups can be calculated as shown in the following formula. Response rate (%) = {1-(a / b) / (A / B)} x 100

[0029] In the above formula, A is the peak height of the epoxy group before the reaction, B is the peak height of the methyl group before the reaction, a is the peak height of the epoxy group after the reaction, and b is the peak height of the methyl group after the reaction. If the epoxy group peak overlaps with other peaks, the peak height of the completely cured sample (100% reaction rate) should be taken as 0%.

[0030] In the case of a curable resin film using the reaction of a (meth)acrylate compound, similarly to an epoxy compound, for example, the methyl group in the infrared absorption spectrum (2930 cm -1(Meth)acryloyl group (around 1635cm -1 The peak heights of the (meth)acryloyl groups before and after the reaction can be measured and the ratio of the peak height of the (meth)acryloyl group to the peak height of the methyl group can be calculated.

[0031] In addition, when the peak height of the (meth)acryloyl group is small or when an alicyclic epoxy group or an oxetanyl group is present, the reaction rate may be determined, for example, by HPLC (High Performance Liquid Chromatography). The reaction rate of each piece can be calculated from the attenuation rate of the reactive component before and after the reaction (before and after laser irradiation) from the chromatogram obtained by HPLC, as shown in the following formula. Reaction rate (%) = {1-c / C} x 100

[0032] In the above formula, C is the peak height or area of ​​the reactive component before the reaction, and c is the peak height or area of ​​the reactive component after the reaction.

[0033] (Ultrashort pulse laser) As shown in Fig. 1, the ultrashort pulse laser LD is irradiated onto the curable resin film 2, causing the material of the curable resin film 2 to explode and evaporate (laser ablation). The ultrashort pulse laser LD may be irradiated from either the substrate 1 side or the curable resin film 2 side. Considering the influence of the substrate 1, it is preferable to irradiate the ultrashort pulse laser LD from the curable resin film 2 side.

[0034] Ultrashort pulse lasers are lasers with a pulse width of femtoseconds (fs) to several picoseconds (ps), and are also called femtosecond lasers or picosecond lasers. Since the pulse width of ultrashort pulse lasers is shorter than the time required for heat conduction, ablation processing using ultrashort pulse lasers can dramatically reduce the thermal effects and suppress the hardening reaction of individual pieces compared to YAG or excimer lasers with nanosecond (ns) pulse widths. In addition, ablation processing using ultrashort pulse lasers can be performed with high precision without causing thermal deformation or heat-affected zones, improving the degree of conformity between the actual geometric shape of the individual pieces and the ideal geometric shape, and achieving excellent shape precision.

[0035] As a specific ultrashort pulse laser, it is preferable to use a femtosecond laser with a pulse width of 10 to 1000 fs, and the pulse width can be appropriately selected according to the material of the curable resin film. In addition, the wavelength can be appropriately selected according to the material of the curable resin film to be processed, such as UV (Ultraviolet), Green (Visible), and IR (Infrared). Among these, ultraviolet light (UV) has a shallow penetration depth, a small focal spot diameter, and a large focal depth, which is advantageous for processing small shapes, and allows the pitch between pieces to be narrowed. Therefore, the effective area on the substrate where the pieces can be used can be increased, the yield can be improved, and the angle of the side surface of the piece relative to the first surface can be brought close to 90°.

[0036] Preferred conditions for femtosecond laser irradiation for dividing the curable resin film into individual pieces include, for example, the following conditions. Wavelength: 180~550nm Pulse energy: 0.01~0.2J Irradiation spot area: 3~1000μm 2 Fluence: 0.1~1J / cm 2 Repetition frequency: 50~5000kHz Laser scanning speed: 200~4000mm / sec Number of laser irradiations: 1 to 50

[0037] (Shape of individual film) FIG. 2 is a cross-sectional view showing a schematic example of an individual film processed with an ultrashort pulse laser. When a curable resin film is ablated using an ultrashort pulse laser, as shown in FIG. 2, the angle α of the side surface 3C with respect to the first surface 3A of the individual piece 3 is preferably 70° or more. In other words, it is preferable that the angle β of the gradient of the side surface 3C with respect to the perpendicular line of the second surface 3B of the individual piece 3 is 20° or less, and the taper angle (2β) of the cross section of the individual piece 3 is 40° or less. Here, the taper angle is the spread (opening angle) of the gradient of both side surfaces of the cross section of the individual piece 2. The upper limit of the angle α of the side surface 3C with respect to the first surface 3A of the individual piece 3 is preferably 90° or less, more preferably less than 90°, and even more preferably less than 88°. The angle α of the side surface 3C with respect to the first surface 3A of the individual piece 3 can be measured using, for example, a three-dimensional measuring machine.

[0038] By making the angle α of the side surface 3C with respect to the first surface 3A of the piece 3 70° or more, the difference between the area of ​​the top surface and the area of ​​the bottom surface does not become too large, so that the landing property during laser lift-off (LLO) transfer can be improved and the transfer rate can be improved. In addition, the transmittance of a micro LED display using the piece can be improved. Furthermore, when the piece is a conductive film or anisotropic conductive film, the particle capture rate at the end of the piece can be improved.

[0039] In addition, by ablating the curable resin film using an ultrashort pulse laser to form the individual pieces 3, the occurrence of defective individual pieces such as insufficient processing, chipping, and turning over can be prevented and the yield rate of the individual pieces can be improved compared to processing using a YAG or excimer laser with a pulse width of nanoseconds (ns). The yield rate of the individual pieces is preferably 90% or more, and more preferably 95% or more. Here, "insufficient processing" refers to, for example, an excess area of ​​a predetermined shape being 20% ​​or more (120% or more when the area of ​​the predetermined shape is 100%), "chip" refers to, for example, an excess area of ​​a predetermined shape being 80% or less (80% or less when the area of ​​the predetermined shape is 100%), and "turning" refers to, for example, an overlap of the film at a part of the end. In other words, it is preferable that the individual pieces are more than 80% and less than 120% of the area of ​​a predetermined shape. Even if the individual pieces have insufficient processing, chipping, turning over, etc., they may be used as they are if they can withstand practical use. For example, the film pieces may be landed and attached so that only good portions of the film pieces are used for connection.

[0040] The film structure includes a substrate 1 and a plurality of pieces 3 made of a curable resin arranged on the substrate 1, and the angle of the side surface of each of the pieces 3 with respect to the first surface is preferably 70° or more. For example, when the substrate 3 is made of glass, it may be circular or rectangular, or may be square. Also, when the substrate 2 is made of PET or the like, the film structure may be wound around a reel to form a roll, or the film structure may be cut into sheets.

[0041] FIG. 3 is a plan view showing a schematic example of an end shape of a film piece. When a curable resin film is ablated into a straight line using an ultrashort pulse laser, as shown in FIG. 3, the straightness measured at 10 points every 2 μm with one side in the x direction is preferably 1.5 μm or less, more preferably 1.2 μm or less, and even more preferably 0.8 μm or less. This makes the straight line part of the piece straighter and sharper, improving the design of the piece and improving the degree of conformity between the actual geometric shape of the piece and the ideal geometric shape, thereby obtaining excellent shape accuracy. It is believed that this also contributes to productivity, as it makes it easier to reflect the concept at the time of design in the actual product and improves the accuracy of analysis.

[0042] In addition, when the curable resin film is linearly ablated using an ultrashort pulse laser and diced into rectangular pieces, the straightness of all four sides is preferably 1.5 μm. In addition, when diced into rectangular pieces, the pitch between pieces can be narrowed to 10 μm or less, so that the effective area on the substrate where the pieces can be used can be increased, thereby improving the yield.

[0043] The straightness is defined in JIS B0621 as "straightness is the size of a target from a geometrically correct straight line of a linear body." In this specification, the straightness is defined as the maximum and minimum difference in the difference between the actual measurement value when measuring 10 positions at 2 μm intervals with one side in the x direction and the corrected value obtained by correcting the actual measurement value with a straight line using the least squares method.

[0044] Specifically, a planar micrograph of the piece is converted into a binary image, and a contour is extracted from the binary image. For example, as shown in FIG. 3, one side of the piece is set as the x direction, and the positions (x, y) of 10 measurement points are obtained at 2 μm intervals for the contour of one side (total 18 μm). Next, a quadratic function (Y=aX+b) is obtained from the positions (x, y) of the 10 measurement points by the least squares method, and a correction value Y of the 10 measurement points is calculated from this quadratic function. Then, for the 10 measurement points, the difference between the actual measurement value y and the correction value Y is calculated, and the difference between the maximum difference value and the minimum difference value (MAX-MIN) is taken as the straightness. Note that the interval and number of points to be observed may be changed depending on the length of one side of the piece, and it is preferable to have 10 or more observation points.

[0045] Figure 4 is a plan view showing a first example of the shape of an individual film, where Figure 4(A) shows a rectangular individual film, Figure 4(B) shows a square individual film, Figure 4(C) shows an oval individual film, and Figure 4(D) shows a circular individual film.

[0046] The shape of the piece is not particularly limited, and can be a desired shape by drawing with an ultrashort pulse laser. For example, in the case of pieces for mounting micro LEDs, it is preferable to make the pieces rectangular with several tens of μm square as shown in FIG. 4(A) or square as shown in FIG. 4(B) according to the element size of the micro LED. Also, it may be an elliptical piece as shown in FIG. 4(C) or a circular piece as shown in FIG. 4(D).

[0047] Figure 5 is a plan view showing a second example of the shape of an individual film, where Figure 5(A) shows a rectangular individual film, Figure 5(B) shows a square individual film, Figure 5(C) shows an oval individual film, and Figure 5(D) shows a circular individual film.

[0048] In the first example shown in FIG. 4, all of the curable resin other than that of the individual pieces is removed, but as in the second example shown in FIG. 5, the curable resin may be left in the spaces between the individual pieces, and the outer shape and outer frame of the curable resin film of the individual pieces may remain. When only the individual pieces are peeled off from the substrate by laser lift-off, it is sufficient that the curable resin film is ablated into the shape of the individual pieces. According to the second example, the curable resin in the spaces between the individual pieces is not removed, so that the processing time for the individual pieces can be shortened.

[0049] (First manufacturing method example of conductive film pieces) Fig. 6 is a plan view showing a first example of a method for producing individual pieces of a conductive film, Fig. 6(A) shows the conductive film before processing, and Fig. 6(B) shows the individual pieces of the film after processing. As shown in Fig. 6(A) and Fig. 6(B), in the first example of the method, an ultrashort pulse laser light is irradiated onto a conductive film containing conductive particles 4 in a curable resin film 2 to perform drawing, and the conductive film is divided into individual pieces 3 of a predetermined shape.

[0050] (Second manufacturing method example of conductive film pieces) Figure 7 is a plan view showing a schematic diagram of a second example of a method for producing individual pieces of conductive film, where Figure 7(A) shows the curable resin film before processing, Figure 7(B) shows the curable resin film after processing, Figure 7(C) shows a conductive particle transfer mold, and Figure 7(D) shows an individual piece of film after transfer.

[0051] In the second manufacturing method example, first, as shown in FIG. 7(A) and FIG. 7(B), a curable resin film 2 is irradiated with ultrashort pulsed laser light to draw, and the curable resin film is divided into pieces 3 of a predetermined shape. Next, as shown in FIG. 7(C), a conductive particle transfer mold 5 on which conductive particles 4 are arranged is prepared, and the pieces 3 formed on the substrate 1 and the conductive particle transfer mold 5 are opposed to each other and pressed, so that the conductive particles 4 are transferred to the pieces 3 as shown in FIG. 7(D). Here, the conductive particle transfer mold 5 can be designed according to the pieces 3 to reduce the cost of the conductive particles. In addition, in the second manufacturing method example, since the conductive particles are not affected by the ultrashort pulsed laser, conductive particles containing, for example, resin or metal with a low melting point can be used.

[0052] Figure 8 is a plan view showing a schematic diagram of a third example method for manufacturing individual pieces of conductive film, where Figure 8(A) shows a first curable resin film before processing, Figure 8(B) shows the first curable resin film after processing, Figure 8(C) shows a conductive particle transfer mold, Figure 8(D) shows the first individual film after transfer, Figure 8(E) shows the second curable resin film before processing, Figure 8(F) shows the second curable resin film after processing, Figure 8(G) shows the conductive particle transfer mold, and Figure 8(H) shows the second individual film after transfer.

[0053] In the third manufacturing method example, as shown in FIG. 8(A) and FIG. 8(B), in the first round, the curable resin film 2 is irradiated with ultrashort pulse laser light to draw, and the curable resin film is divided into pieces 3 of a predetermined shape. Next, as shown in FIG. 8(C), a conductive particle transfer mold 6 having conductive particles 4 arranged on one side is prepared, and the pieces 3 formed on the substrate 1 and the conductive particle transfer mold 5 are opposed to each other and pressed, so that the conductive particles 4 are transferred to the pieces 3 as shown in FIG. 8(D). Then, as the second round, as shown in FIG. 8(E) and FIG. 8(F), the curable resin film 2 is irradiated with ultrashort pulse laser light to draw, and the curable resin film is divided into pieces 3 of a predetermined shape. Next, as shown in FIG. 8(G), the conductive particle transfer mold 6 used in the first round is prepared, and the pieces 3 formed on the substrate 1 are opposed to the conductive particle transfer mold 5 and pressed, so that the conductive particles 4 are transferred to the pieces 3 as shown in FIG. 8(H). Here, as shown in FIG. 8(A) and FIG. 8(F), the pitch of the pieces and the space is set to 1:1 or more when singulating, and as shown in FIG. 8(C) and FIG. 8(G), the pieces 3 and the conductive particle transfer mold 5 are opposed to each other by shifting by one pitch when transferring the conductive particles in the second round of FIG. This allows the same conductive particle transfer mold 6 to be used in the first and second rounds, thereby reducing costs. In addition, in the third manufacturing method example, since the conductive particles are not affected by the ultrashort pulse laser, conductive particles containing, for example, resin or a metal with a low melting point can be used. In addition, in the present invention, the method of arranging the conductive particles is not limited to the method of transferring the conductive particles 4 to the curable resin film 2 using a transfer mold.

[0054] <2. Method for producing connection structure and connection structure> The method for manufacturing the connection structure according to the present embodiment includes a placement step of placing a first electronic component and a second electronic component via a film strip, and a curing step of compressing the first electronic component and the second electronic component with a compression tool and curing the film strip. Here, the compression may be replaced with reflow.

[0055] Moreover, the connection structure according to the present embodiment includes a first electronic component, a second electronic component, and a cured film to which the first electronic component and the second electronic component are bonded, and the cured film is formed by curing an individual film containing a curable resin.

[0056] The connection structure and the method for manufacturing the connection structure according to the present embodiment use a film piece with a side surface angle of 70° or more relative to the first surface, so that when a micro LED is mounted, for example, the transmittance of the display can be improved. Also, when the piece is an ACF, the particle capture rate at the end of the piece can be improved.

[0057] The first electronic component and the second electronic component are not particularly limited and can be appropriately selected according to the purpose. Examples of the first electronic component include wiring boards and printed wiring boards (PWBs) for display applications such as LCD (Liquid Crystal Display) panels, organic electroluminescence (OLED), and LED displays, light source applications, and touch panel applications. The material of the printed wiring board is not particularly limited, and may be, for example, glass epoxy such as FR-4 base material, plastic such as thermoplastic resin, ceramic, etc. Examples of the wiring board include glass substrates and plastic substrates. Examples of the second electronic component include, for example, LEDs (including micro LEDs), ICs (Integrated Circuits), flexible printed circuits (FPCs), tape carrier package (TCP) substrates, and COFs (Chip On Films) in which ICs are mounted on FPCs. The number of second electronic components relative to the first electronic components does not need to correspond 1:1, and a large number of second electronic components may be mounted on the first electronic component. The second electronic components may be stacked on the first electronic component.

[0058] A manufacturing method of a display device using an individual film will be described below. The manufacturing method of a display device shown as an example includes a transfer process (A) in which an individual piece of a predetermined shape is transferred to a predetermined position on a wiring board using a laser lift-off device, and a mounting process (B) in which light-emitting elements are arranged at predetermined positions on the wiring board using the laser lift-off device and the light-emitting elements are mounted on the wiring board. Note that the individual pieces are the same as those described above, so a description thereof will be omitted here.

[0059] [Laser lift-off equipment] A laser lift-off device irradiates a material layer formed on a substrate with laser light to peel the material layer off from the substrate. An example of a laser lift-off device is the product name "Invisi LUM-XTR" manufactured by Shin-Etsu Chemical Co., Ltd.

[0060] Fig. 9 is a diagram showing an example of a laser lift-off apparatus. As shown in Fig. 9, the laser lift-off apparatus 10 includes a laser scanner 11 for scanning the optical axis of a laser beam, a mask 12 in which a plurality of openings of a predetermined shape are arranged at a predetermined pitch, a projection lens 13 for reducing and projecting the laser beam onto a donor substrate, a donor stage for holding the donor substrate, and a receptor stage for holding a receptor substrate. In the transfer of the piece film, a piece substrate 20 in which a plurality of pieces 22 are formed on a base material 21 is held on the donor stage as a donor substrate, and pieces 23 separated from the piece substrate 20 are landed on a wiring substrate as a receptor substrate.

[0061] [Transfer process (A)] 10 is a cross-sectional view that typically shows a state in which an individual film and a wiring board are opposed to each other. As shown in FIG 10, first, in the transfer step (A), individual board 30 and wiring board 40 are opposed to each other.

[0062] The individual substrate 30 includes a base material 31 and individual pieces 33 made of a conductive film containing conductive particles 32, and the individual pieces 33 are arranged in units of light-emitting elements on the surface of the base material 31. The base material 31 may be any material that is transparent to laser light, and is preferably made of quartz glass or borosilicate glass, which have high light transmittance over all wavelengths.

[0063] The wiring board 40 includes a circuit pattern for a first conductivity type and a circuit pattern for a second conductivity type on a base material 41, and has a first electrode 42 and a second electrode 43 at positions corresponding to the p-side first conductivity type electrode and the n-side second conductivity type electrode, respectively, so that light-emitting elements are arranged in units of subpixels (sub-pixels) constituting one pixel. The wiring board 40 also forms circuit patterns such as data lines and address lines of matrix wiring, for example, to enable turning on and off light-emitting elements corresponding to each subpixel constituting one pixel. One pixel may be composed of three subpixels of R (red), G (green), and B (blue), four subpixels of RGBW (white) and RGBY (yellow), or two subpixels of RG and GB.

[0064] Furthermore, when the wiring board 40 is used for a transparent display, it is preferable that the wiring board 40 is a light-transmitting board, and the base material 41 is preferably glass, PET (Polyethylene Terephthalate), or the like. The first electrode 42 and the second electrode 43 are preferably transparent conductive films such as ITO (Indium-Tin-Oxide), IZO (Indium-Zinc-Oxide), ZnO (Zinc-Oxide), and IGZO (Indium-Gallium-Zinc-Oxide). The first electrode 42 and the second electrode 43 may contain a metal such as Au, Cu, Ag, Ni, Cr, Al, Ti, Mo, Ta, or Nd, or may be an alloy.

[0065] Fig. 11 is a cross-sectional view showing a schematic state in which laser light is applied from the substrate side, and conductive film pieces are transferred to and arranged at predetermined positions on a wiring board. As shown in Fig. 11, in the transfer step (A), laser light is applied from the substrate 31 side using the above-mentioned laser lift-off device, and conductive film pieces 33 are transferred to and arranged at predetermined positions on a wiring board 40. The distance between pieces 33 and wiring board 40 is preferably 10 to 20,000 µm, more preferably 50 to 1,500 µm, and even more preferably 80 to 1,000 µm.

[0066] By aligning and transferring the base material 31 and the wiring board 40, the individual pieces 33 can be arranged in subpixel units on the wiring board 40. Furthermore, when the size of the wiring board 40 is larger than the size of the base material 31, by aligning the base material 31 multiple times and transferring the individual pieces 33, the individual pieces 33 can be arranged in subpixel units in the screen area of ​​the wiring board 40.

[0067] The reaction rate of the conductive film piece 33 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 conductive film piece 33 after the transfer step (A) is 25% or less, the light-emitting element can be thermocompression-bonded in the next mounting step (B). The reaction rate can be measured, for example, by using FT-IR, as described above.

[0068] [Mounting process (B)] 12 is a cross-sectional view showing a state in which light-emitting elements are mounted on pieces arranged at predetermined positions on a wiring board. As shown in FIG. 12, in the mounting process (B), light-emitting elements 50 are mounted on pieces 33 arranged at predetermined positions on wiring board 40.

[0069] The light emitting element 50 includes a body 51, a first conductivity type electrode 52, and a second conductivity type electrode 53. The first conductivity type electrode 52 and the second conductivity type electrode 53 are arranged on the same side in a horizontal structure. The body 51 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, including 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 52 is formed on a part of the first-conductivity-type cladding layer by a passivation layer, and a second-conductivity-type electrode 53 is formed on a part of the second-conductivity-type cladding layer. When a voltage is applied between the first-conductivity-type electrode 52 and the second-conductivity-type electrode 53, carriers are concentrated in the active layer and recombine to generate light emission.

[0070] The light emitting elements 50 are arranged on the wiring substrate 40 corresponding to the sub-pixels constituting one pixel, forming a light emitting element array. One pixel may be composed of, for example, 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.

[0071] For example, in the case of RGB, the sub-pixel arrangement may be a stripe arrangement, a mosaic arrangement, a delta arrangement, etc. The stripe arrangement is an arrangement in which RGB is arranged in vertical stripes, which allows for high definition. The mosaic arrangement is an arrangement in which the same RGB colors are arranged diagonally, which allows for a more natural image than the stripe arrangement. The delta arrangement is an arrangement in which RGB is arranged in a triangle, with each dot shifted by half a pitch for each field, which allows for a more natural image display.

[0072] In the mounting step (B), the light emitting element 50 can be disposed at a predetermined position on the wiring board 40 using the above-mentioned laser lift-off apparatus. In the above-mentioned laser lift-off apparatus, the light emitting element 50, which is a donor substrate, is held on a donor stage, and the wiring board 40, which is a receptor substrate, is held on a receptor stage. The distance between the light emitting element and the wiring board is preferably 10 to 1000 μm, more preferably 50 to 500 μm, and further preferably 80 to 200 μm.

[0073] As a method for connecting the light emitting element 50 to the wiring board 40, a connection method such as thermocompression bonding, photocompression bonding, and thermo-photocompression bonding, which are used in known anisotropic conductive films, can be appropriately selected and used. In addition, when the conductive particles are solder particles, for example, the connection may be made by reflow. The conditions for thermocompression bonding are, for example, a temperature of 150°C to 260°C, a pressure of 1MPa to 60MPa, and a time of 5 seconds to 300 seconds. When the conductive film is cured, a cured film is formed, and the light emitting element 50 can be anisotropically connected to the wiring board 40 in a state where the cured film does not exist between the light emitting elements 50 and the wiring board 40 is exposed. In addition, by using the wiring board 40 as a light-transmitting board, superior light transmittance can be obtained compared to the case where a conductive film is attached to the entire surface of the wiring board 50. EXAMPLES

[0074] <3. First Example> In the first example, an anisotropic conductive film was prepared as the conductive film, and the anisotropic conductive film was diced into pieces of a predetermined size. Then, the gradient angle of the end of each piece, the yield of each piece, the space between each piece, the reaction rate of each piece, and the transfer rate of each piece were evaluated.

[0075] [Preparation of anisotropic conductive film] A binder was prepared by mixing 40 parts by mass of phenoxy resin (product name: YP-50, manufactured by Nippon Steel Chemical & Material Co., Ltd.), 20 parts by mass of bisphenol A type epoxy resin (product name: YD-019, manufactured by Nippon Steel Chemical & Material Co., Ltd.), 10 parts by mass of liquid epoxy resin (product name: YL980, manufactured by Mitsubishi Chemical Corporation), 10 parts by mass of high-purity hydrogenated epoxy resin (product name: YX8000, manufactured by Mitsubishi Chemical Corporation), 10 parts by mass of fumed silica fine particles (product name: RY200, manufactured by Nippon Aerosil Co., Ltd.), and 10 parts by mass of a cationic polymerization initiator (product name: SI-60L, manufactured by Sanshin Chemical Industry Co., Ltd.).

[0076] The binder was applied onto a 50 μm thick PET (Poly Ethylene Terephthalate) film as a base film, and dried to form a resin film. 2 The conductive particles (average particle size 2.2 μm, resin core metal coated microparticles, Ni plating 0.1 μm thick, manufactured by Sekisui Chemical Co., Ltd.) were attached to an arrangement sheet in which they were arranged in a hexagonal lattice pattern, and the conductive particles were pressed into the resin film and transferred to it, producing an anisotropic conductive film in which conductive particles were aligned to a thickness of 4 μm on the base film.

[0077] [Evaluation of gradient on side of individual piece] The angle α of the side surface of the piece end relative to the first surface (substrate film surface) was measured using a three-dimensional measuring machine. The gradient of the piece side surface was evaluated according to the average value of the angle α of 10 pieces, based on the following criteria. The gradient of the piece side surface is preferably evaluated as B or higher. A: 70° or more B: 50° to 70° C: Less than 50°

[0078] [Evaluation of the yield rate of individual pieces] FIG. 13 is a micrograph including pieces with defective shapes that have been insufficiently processed, chipped, and turned over. The appearance of 100 pieces of pieces on the base film was observed using a microscope, and pieces with defective shapes (insufficient processing, chipped, turned over, etc.) were counted. The yield rate of the pieces was evaluated according to the following criteria depending on the number of pieces with defective shapes. The yield rate of the pieces is preferably evaluated as B or higher. Here, "insufficient processing" refers to a surplus area of ​​the specified shape being 20% ​​or more (120% or more when the area of ​​the specified shape is 100%). Furthermore, "chip" refers to an area that is 80% or less of the specified shape (80% or less when the area of ​​the specified shape is 100%). Furthermore, "turned over" refers to a film overlapping at a part of the end. A: Less than 1pcs B: 2pcs or more and 5pcs or less C: 6pcs or more and 10pcs or less D: 11pcs or more

[0079] [Evaluation of space between individual pieces] The space between the pieces on the base film was measured using a microscope. The space between the pieces was evaluated according to the following criteria, depending on the number of defective pieces. The space between the pieces is preferably evaluated as C or higher. A: 10μm or less B: More than 10μm and less than 20μm C: More than 20μm and less than 30μm D: More than 30μm

[0080] [Evaluation of individual piece reaction rate] The anisotropic conductive film sample before singulation and the individual pieces were sampled, and each sample was irradiated with infrared light to measure the IR spectrum. -1 near 914cm -1 The peak heights of the epoxy groups (near the peak height of the methyl group) were measured and calculated as the ratio of the peak height of the epoxy group to the peak height of the methyl group before and after singulation, as shown in the following formula. Response rate (%) = {1-(a / b) / (A / B)} x 100 In the above formula, A is the peak height of the epoxy group of the anisotropic conductive film sample before singulation, B is the peak height of the methyl group of the anisotropic conductive film sample before singulation, a is the peak height of the epoxy group of the individual sample, and b is the peak height of the methyl group of the individual sample.

[0081] The reaction rate of each piece was evaluated according to the following criteria depending on the reaction rate. The reaction rate of each piece is preferably evaluated as B or higher. A: 10% or less B: More than 10% and less than 30% C: More than 30% and less than 50% D: More than 50%

[0082] [Evaluation of transcription rate of individual pieces] The individual pieces on the base film were transferred to a substrate using a laser lift-off device. Laser light was irradiated from the base film side to transfer 10 x 10 pieces (total 100 pieces) of individual pieces to the substrate, and the individual pieces after transfer were observed under a microscope to calculate the transfer rate. The irradiation conditions of the laser lift-off device were as follows. Laser type: Excimer laser Wavelength: 248nm Pulse width: 30000ps Pulse energy: 600mJ Fluence: 150mJ / cm 2 Repetition frequency: 0.01kHz Number of laser shots: 1

[0083] [Example 1] A femtosecond laser was used to irradiate the anisotropic conductive film with laser light from the anisotropic conductive film side to draw straight lines, and the anisotropic conductive film was divided into individual square pieces of 60 μm × 60 μm. The irradiation conditions of the laser device were as follows. Wavelength: 343nm Pulse width: 500fs Output: 0.245~0.38W Pulse energy: 0.081~0.127J Irradiation spot area: φ10μm (78.5μm 2 ) Fluence: 0.21~0.32J / cm 2 Repetition frequency: 3000kHz Laser scanning speed: 3000mm / sec Number of laser shots: 20

[0084] As shown in Table 1, the gradient of the side surface of each piece in Example 1 was evaluated as A, the yield of each piece was evaluated as A, the space between each piece was evaluated as A, the reaction rate of each piece was evaluated as B, and the transcription rate of each piece was 99%. Furthermore, the number of pieces required to singulate an area of ​​100 mm x 100 mm was approximately 2 million, and the singulation time was approximately 40 minutes.

[0085] FIG. 14 is a micrograph of an individual film obtained by dividing the anisotropic conductive film in Example 1, and FIG. 15 is a micrograph of an individual film transferred to a substrate using a laser lift-off device in Example 1. As shown in FIG. 14, it can be seen that the space between the individual pieces can be narrowed in Example 1. It can also be seen that the contours bordering the individual pieces are more linear, and excellent shape accuracy can be obtained. It can also be seen that the contours bordering the individual pieces after transfer are more linear in Example 1. Note that in this specification, the magnification of the micrograph is approximately the same for comparison objects.

[0086] [Example 2] The same procedure was followed as in Example 1, except that the anisotropic conductive film was singulated into 40 μm×40 μm square pieces. As shown in Table 1, in Example 2, the gradient of the side surface of each piece was evaluated as A, the yield of the pieces was evaluated as A, the space between the pieces was evaluated as A, the reaction rate of the pieces was evaluated as B, and the transcription rate of the pieces was 98%. In addition, the number of pieces when an area of ​​100 mm×100 mm was singulated was approximately 4 million, and the singulation time was approximately 50 minutes.

[0087] FIG. 16 is a micrograph of an individual film obtained by dividing the anisotropic conductive film in Example 2, and FIG. 17 is a micrograph of an individual film transferred to a substrate using a laser lift-off device in Example 2. As shown in FIG. 16, it can be seen that in Example 2, the space between the individual pieces can be narrowed. It can also be seen that the outlines bordering the individual pieces are more linear, and excellent shape accuracy can be obtained. It can also be seen that in Example 2, the outlines bordering the individual pieces after transfer are more linear, as shown in FIG. 17.

[0088] [Comparative Example 1] Using an excimer laser lift-off device, laser light was irradiated from the base film side to remove part of the anisotropic conductive film by shock waves, forming spaces between the pieces, and singulating into 60 μm × 60 μm square pieces. The irradiation conditions of the laser device were as follows. Wavelength: 248nm Pulse width: 30000ps Pulse Energy: 4J Fluence: 1J / cm 2 Repetition frequency: 0.01kHz Number of laser irradiations: 1

[0089] As shown in Table 1, in Comparative Example 1, the gradient of the side surface of each piece was rated as C, the yield of each piece was rated as D, the space between each piece was rated as D, the reaction rate of each piece was rated as B, and the transcription rate of each piece was 97%. Furthermore, the number of pieces required to singulate an area of ​​100 mm x 100 mm was approximately 400,000, and the singulation time was 60 minutes or more.

[0090] FIG. 18 is a micrograph of an individual film obtained by dividing an anisotropic conductive film in Comparative Example 1, and FIG. 19 is a micrograph of an individual film transferred to a substrate using a laser lift-off device in Comparative Example 1. As shown in FIG. 18, it can be seen that the space between the individual pieces is large in Comparative Example 1. It can also be seen that the outline of the individual pieces is not linear, and good shape accuracy is not obtained. Also, as shown in FIG. 19, in Comparative Example 1, there are gaps where the individual pieces do not land on the substrate during transfer, and the outline of the transferred individual pieces is not linear.

[0091] [Comparative Example 2] The same procedure was followed as in Comparative Example 1, except that the anisotropic conductive film was singulated into 40 μm×40 μm square pieces. As shown in Table 1, in Comparative Example 2, the gradient of the side surface of each piece was evaluated as C, the yield of the pieces was evaluated as D, the space between the pieces was evaluated as D, the reaction rate of the pieces was evaluated as B, and the transcription rate of the pieces was 95%. In addition, the number of pieces required to singulate an area of ​​100 mm×100 mm was approximately 400,000, and the singulation time was 60 minutes or more.

[0092] FIG. 20 is a micrograph of an individual film obtained by dividing an anisotropic conductive film in Comparative Example 2, and FIG. 21 is a micrograph of an individual film transferred to a substrate using a laser lift-off device in Comparative Example 2. As shown in FIG. 20, it can be seen that the space between the individual pieces is large in Comparative Example 2. It can also be seen that the outline of the individual pieces is not linear, and good shape accuracy is not obtained. Also, as shown in FIG. 21, in Comparative Example 2, there are gaps where the individual pieces do not land on the substrate during transfer, and the outline of the transferred individual pieces is not linear.

[0093] [Comparative Example 3] Except for the fact that the anisotropic conductive film was singulated into rectangular pieces of 30 μm × 40 μm, the comparative example was the same as comparative example 1. As shown in Table 1, in comparative example 3, the gradient of the side surface of each piece was evaluated as C, the yield of each piece was evaluated as D, the space between each piece was evaluated as D, the reaction rate of each piece was evaluated as B, and the transcription rate of each piece was 93%.

[0094] FIG. 22 is a micrograph of an individual film obtained by dividing an anisotropic conductive film in Comparative Example 3, and FIG. 23 is a micrograph of an individual film transferred to a substrate using a laser lift-off device in Comparative Example 3. As shown in FIG. 22, it can be seen that the space between the individual pieces is large in Comparative Example 3. It can also be seen that the outline of the individual pieces is not linear, and good shape accuracy is not obtained. Also, as shown in FIG. 23, in Comparative Example 3, there are missing parts and misaligned parts where the individual pieces do not land on the substrate during transfer, and the outline of the transferred individual pieces is not linear.

[0095] [Comparative Example 4] A YAG laser was used to irradiate the anisotropic conductive film from the side thereof to draw straight lines, and the anisotropic conductive film was divided into individual pieces of 30 μm × 30 μm squares. The irradiation conditions of the laser device were as follows: Wavelength: 266nm Pulse width: 8000ps Energy Intensity: 10% Number of laser shots: 10

[0096] As shown in Table 1, in Comparative Example 4, the gradient of the side surface of each piece was rated as A, the yield of each piece was rated as A, the space between each piece was rated as A, and the reaction rate of each piece was rated as D. In Comparative Example 4, a nanosecond laser was used, and therefore the reaction rate of hardening the pieces was high.

[0097] [Comparative Example 5] The anisotropic conductive film was cut using a dicer used for dicing wafers, and was divided into individual pieces of 150 μm×150 μm squares. As shown in Table 1, the gradient of the side surface of the individual pieces in Comparative Example 5 was evaluated as C, the yield of the individual pieces was evaluated as C, the space between the individual pieces was evaluated as C, and the reaction rate of the individual pieces was evaluated as A. Since dicing is a physical cut, there is a limit to the size of the individual pieces in order to cut the adhesive film without blocking (peeling off from the substrate), and it was difficult to produce individual pieces of a size of 100 μm or less. In addition, the blade entered the cutter, so the shape of the edge of the individual pieces was also distorted.

[0098] [Table 1]

[0099] In Comparative Examples 1 to 3, the portion removed by the laser lift-off was large, and the space between the pieces was large, so the evaluation of the space between the pieces and the evaluation of the yield of the pieces were not good. In Comparative Examples 1 to 3, the shape accuracy of the pieces was not good, and the evaluation of the gradient of the side surface of the pieces and the transfer rate of the pieces were not good. In Comparative Example 4, the pulse width of the laser was on the order of nanoseconds, so the hardening reaction of the pieces progressed, making it difficult to exhibit the function of the anisotropic conductive film. In Comparative Example 5, the anisotropic conductive film was cut using a dicer, so the evaluation of the gradient of the side surface of the pieces, the evaluation of the yield of the pieces, and the evaluation of the space between the pieces were not good.

[0100] On the other hand, in Examples 1 and 2, the anisotropic conductive film was singulated using a femtosecond laser, so that the pitch between pieces could be narrowed, and the evaluation of the yield of the pieces and the evaluation of the space between the pieces were good. In addition, in Examples 1 and 2, the effective area in which the pieces can be used could be increased, and the number of pieces when the same area was processed could be about 5 times or more compared to Comparative Examples 1 and 2. In addition, in Examples 1 and 2, excellent shape accuracy was obtained, and the evaluation of the gradient of the side surface of the pieces and the transfer rate of the pieces were good. In addition, in Examples 1 and 2, the hardening reaction could be suppressed, and the evaluation of the reaction rate of the pieces was also good.

[0101] <4. Second Example> In the second example, the square pieces in Example 1 and Comparative Example 1 were evaluated for straightness of the lines (contours) forming the outer shapes of the pieces.

[0102] First, the contour was extracted from the binarized image, and for example, as shown in FIG. 3, one side of the piece was set as the x direction, and the positions (x, y) of 10 measurement points were obtained at 2 μm intervals for the contour of one side (total 18 μm). Next, a quadratic function (Y=aX+b) was obtained from the positions (x, y) of the 10 measurement points by the least square method, and the correction value Y of the 10 measurement points was calculated from this quadratic function. Then, for the 10 measurement points, the difference between the actual measurement value y and the correction value Y was calculated, and the difference between the maximum difference value and the minimum difference value was taken as the straightness. The straightness was obtained for each of the 10 arbitrary pieces, and the average value was calculated. As shown in Table 2, the average straightness of Example 1 was 0.70 μm, and the average straightness of Comparative Example 1 was 1.92 μm. In addition, the straightness of all four sides of the arbitrary 10 pieces for which the straightness was obtained in Example 1 was 1.5 μm or less.

[0103] Fig. 24 is an enlarged micrograph of the film piece in Example 1, and Fig. 25 is a binarized image of the enlarged micrograph shown in Fig. 24. Fig. 26 is an enlarged micrograph of the film piece in Comparative Example 1, and Fig. 27 is a binarized image of the enlarged micrograph shown in Fig. 26. It can also be seen from the binarized images shown in Figs. 24 and 26 that the straightness of the contours of the pieces is better in Example 1 than in Comparative Example 1.

[0104] [Table 2] [Explanation of symbols]

[0105] REFERENCE SIGNS LIST 1 substrate, 2 curable resin film, 3 piece, 3A first surface, 3B second surface, 3A side surface, 4 conductive particles, 5 conductive particle transfer mold, 6 conductive particle transfer mold, 10 laser lift-off device, 11 laser scanner, 12 mask, 13 projection lens, 20 piece substrate, 21 substrate, 22 piece, 23 piece, 30 piece substrate, 31 substrate, 32 conductive particles, 33 piece, 40 wiring substrate, 41 substrate, 42 first electrode, 43 second electrode, 50 light emitting element, 51 main body, 52 first conductive type electrode, 53 second conductive type electrode

Claims

1. A method for producing individual films, comprising irradiating a curable resin film with ultrashort pulsed laser light to form an image on the film, and dividing the curable resin film into individual films having a predetermined shape.

2. The method for producing an individual film according to claim 1 , wherein the curable resin film is divided into individual film pieces each having a side surface at an angle of 70° or more relative to the first surface.

3. The method for producing an individual film according to claim 1 or 2, wherein the curable resin film is divided into individual film pieces having a shape in which the straightness when measured at 10 positions spaced 2 μm apart is 1.5 μm or less.

4. The method for producing a film piece according to claim 1 or 2, wherein the curable resin film is a conductive film containing conductive particles.

5. The method for producing a film piece according to claim 1 or 2, further comprising transferring conductive particles to the film piece to obtain a conductive film.

6. the pulse width of the ultrashort pulse laser light is 10 to 1000 fs; The fluence of one pulse of the ultrashort pulse laser light is 0.1 to 1 J / cm ２ The method for producing an individual film according to claim 1 or 2,

7. A film piece comprising a curable resin, the angle of a side surface relative to the first surface being 70° or more.

8. 8. The film according to claim 7, wherein the straightness of the film is 1.5 μm or less when measured at 10 positions spaced 2 μm apart.

9. The film piece according to claim 7 or 8, wherein the curable resin film is a conductive film containing conductive particles.

10. a placement step of placing a first electronic component and a second electronic component via an individual film that contains a curable resin and has a side surface that has an angle of 70° or more with respect to the first surface; a hardening step of hardening the individual film while bonding the first electronic component and the second electronic component together with a bonding tool; A method for manufacturing a connection structure having the above structure.

11. The method for producing a connection structure according to claim 10 , wherein the individual film pieces are conductive films containing conductive particles.

12. A first electronic component; A second electronic component; a cured film connecting the first electronic component and the second electronic component, The cured film contains a curable resin, and the connection structure is formed by curing an individual film piece having a side surface at an angle of 70° or more relative to the first surface.

13. The connection structure according to claim 12 , wherein the individual film pieces are conductive films containing conductive particles.

14. A substrate and a plurality of individual films made of a curable resin disposed on the substrate, A film structure, wherein an angle of a side surface of the individual film relative to the first surface is 70° or more.

15. The film structure according to claim 14 , wherein the individual film occupies more than 80% and less than 120% of the area of ​​a predetermined shape.

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