Method for producing individualized film, individualized film, method for producing connection structure, and connection structure

Abstract

The present invention provides a method for producing an individualized film in which a curing reaction is prevented and which makes it possible to achieve excellent shape precision. The present invention also provides an individualized film, a method for producing a connection structure, and a connection structure. A curable resin film is irradiated with an ultrashort pulse laser beam so as to be subjected to lithography and individualized to an individualized film having a prescribed shape. The pulse width of the ultrashort pulse laser beam is preferably 10-1,000 fs, and the fluence of 1 pulse of the ultrashort pulse laser beam is preferably 0.1-1 J / cm2. This makes it possible to prevent a curing reaction and achieve excellent shape precision.

Description

Method for manufacturing individual film pieces, individual film pieces, and method for manufacturing connection structure and connection structure

[0001] This technology relates to a method for manufacturing a film segment that processes a curable resin film such as a conductive film, an anisotropic conductive film (ACF), or a non-conductive film (NCF), as well as a method for manufacturing a connection structure using the film segment. This application claims priority based on Japanese Patent Application No. 2023-193155, filed in Japan on November 13, 2023, which is incorporated herein by reference.

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

[0003] Methods for connecting micro LEDs to display wiring boards include soldering and eutectic methods, but ACF connection methods are also being developed. For example, Patent Document 1 describes a method in which laser light is irradiated from the substrate side to generate shock waves at the interface between the substrate and a curable resin film, which peels and removes part of the curable resin from the substrate, thereby forming multiple pieces made of the curable resin film on the substrate.

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

[0005] Japanese Patent Application Laid-Open No. 2022-151818

[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 achieve excellent shape accuracy, as well as a method for manufacturing a connection structure and a connection structure.

[0007] The method for producing a film piece according to the present technology involves irradiating a curable resin film with ultrashort pulse laser light to form an image, and dividing the curable resin film into film pieces of predetermined shapes.

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

[0009] The manufacturing method of the 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 containing a curable resin and having 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 together using 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 that connects the first electronic component and the second electronic component, wherein the cured film contains a curable resin and is formed by curing an individual film piece whose side surface has an angle of 70° or more relative to a first surface.

[0011] According to this technology, it is possible to suppress the hardening reaction during processing, and to obtain excellent shape accuracy.

[0012] FIG. 1 is a cross-sectional view schematically showing a state in which an ultrashort pulse laser beam is irradiated onto a curable resin film. FIG. 2 is a cross-sectional view schematically showing an example of an individual film processed with an ultrashort pulse laser. FIG. 3 is a plan view schematically showing an example of the end shape of an individual film. FIG. 4 is a plan view schematically showing a first example of the shape of an individual film, where FIG. 4(A) shows a rectangular individual film, FIG. 4(B) shows a square individual film, FIG. 4(C) shows an oval individual film, and FIG. 4(D) shows a circular individual film. FIG. 5 is a plan view schematically showing a second example of the shape of an individual film, where FIG. 5(A) shows a rectangular individual film, FIG. 5(B) shows a square individual film, FIG. 5(C) shows an oval individual film, and FIG. 5(D) shows a circular individual film. Fig. 6 is a plan view schematically showing a first example of a method for producing conductive film pieces, where Fig. 6(A) shows the conductive film before processing and Fig. 6(B) shows the film pieces after processing. Fig. 7 is a plan view schematically showing a second example of a method for producing conductive film pieces, where Fig. 7(A) shows the curable resin film before processing, Fig. 7(B) shows the curable resin film after processing, Fig. 7(C) shows a conductive particle transfer mold, and Fig. 7(D) shows the film pieces after transfer. FIG. 8 is a plan view schematically showing a third example of a method for producing conductive film pieces, where FIG. 8(A) shows a first curable resin film before processing, FIG. 8(B) shows the first curable resin film after processing, FIG. 8(C) shows a conductive particle transfer mold, FIG. 8(D) shows the first individual film after transfer, FIG. 8(E) shows a second curable resin film before processing, FIG. 8(F) shows the second curable resin film after processing, FIG. 8(G) shows a conductive particle transfer mold, and FIG. 8(H) shows the second individual film after transfer. FIG. 9 is a diagram schematically showing an example of a laser lift-off device. FIG. 10 is a cross-sectional view schematically showing a state in which an individual film and a wiring substrate are opposed to each other. FIG. 11 is a cross-sectional view schematically showing a state in which laser light is irradiated from the substrate side, and conductive film pieces are transferred to predetermined positions on the wiring substrate and arranged. Fig. 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. Fig. 13 is a micrograph showing pieces with defective shapes, which have been insufficiently processed, chipped, and turned over.FIG. 14 is a micrograph of a piece film obtained by singulating a conductive film in Example 1. FIG. 15 is a micrograph of a piece film transferred to a substrate using a laser lift-off apparatus in Example 1. FIG. 16 is a micrograph of a piece film obtained by singulating a conductive film in Example 2. FIG. 17 is a micrograph of a piece film transferred to a substrate using a laser lift-off apparatus in Example 2. FIG. 18 is a micrograph of a piece film obtained by singulating a conductive film in Comparative Example 1. FIG. 19 is a micrograph of a piece film transferred to a substrate using a laser lift-off apparatus in Comparative Example 1. FIG. 20 is a micrograph of a piece film obtained by singulating a conductive film in Comparative Example 2. FIG. 21 is a micrograph of a piece film transferred to a substrate using a laser lift-off apparatus in Comparative Example 2. FIG. 22 is a micrograph of a piece film obtained by singulating a conductive film in Comparative Example 3. FIG. 23 is a micrograph of a piece film transferred to a substrate using a laser lift-off apparatus in Comparative Example 3. Fig. 24 is an enlarged microscope photograph of a film piece in Example 1. Fig. 25 is a binarized image of the enlarged microscope photograph shown in Fig. 24. Fig. 26 is an enlarged microscope photograph of a film piece in Comparative Example 1. Fig. 27 is a binarized image of the enlarged microscope photograph shown in Fig. 26.

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

[0014] <1. Method for manufacturing individual film and individual film> The method for manufacturing individual film according to the present embodiment involves irradiating an ultrashort pulse laser beam onto a curable resin film to form an image, and then dividing the curable resin film into individual film pieces of a predetermined shape. This makes it possible to suppress the curing reaction of the individual film pieces, thereby achieving excellent shape accuracy. In this specification, "individual film pieces" are also referred to simply as "pieces." Furthermore, "shape accuracy" refers to the degree of fit between an actual geometric shape and an ideal geometric shape.

[0015] Fig. 1 is a cross-sectional view schematically illustrating a state in which a curable resin film is irradiated with ultrashort pulse 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 pulse laser LD is irradiated onto the curable resin film 2 to form an image, 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] (Substrate) 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). Furthermore, the substrate 1 may preferably be one in which at least the surface on the curable resin film 2 side has been subjected to a release treatment, for example, with a silicone resin (a release-treated substrate). Furthermore, when irradiating the substrate 1 with ultrashort pulsed laser light from the substrate 1 side, the substrate 1 may be any material that is transparent to the laser light, and in particular, quartz glass or borosilicate glass, which have high light transmittance across all wavelengths, are preferred (a substrate transparent to 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 combined heat and light curable binder, etc. Examples of thermosetting binders include a thermal anionic polymerization resin composition containing an epoxy compound and a thermal anionic polymerization initiator, a thermal cationic polymerization resin composition containing an epoxy compound and a thermal cationic polymerization initiator, and a thermal radical polymerization resin composition containing a (meth)acrylate compound and a thermal radical polymerization initiator. Examples of photocurable binders include a photocationic polymerization resin composition containing an epoxy compound and a photocationic polymerization initiator, and a thermal radical polymerization resin composition containing a (meth)acrylate compound and a photoradical polymerization initiator. Examples of combined heat and light curable binders include a thermal and photocationic polymerization resin composition containing an epoxy compound and a thermal and photocationic polymerization initiator. The (meth)acrylate compound includes both acrylic monomers (oligomers) and methacrylic monomers (oligomers).

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

[0019] From the viewpoint of film-forming properties, examples of the film-forming resin include various resins such as phenoxy resin, polyester resin, polyurethane resin, polyesterurethane resin, acrylic resin, polyimide resin, and butyral resin, each having a weight-average molecular weight of preferably about 10,000 to 80,000. These may be used alone or in combination of two or more. Among these, phenoxy resin is preferred from the viewpoint of film formation state, connection reliability, and the like. A specific example of a phenoxy resin is "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, per 100 parts by mass of the thermosetting binder, 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.

[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. For example, it may be a bisphenol A type epoxy resin, a bisphenol F type epoxy resin, or a urethane-modified epoxy resin. A specific example of a bisphenol A type epoxy resin is "YD-019" manufactured by Nippon Steel Chemical & Material Co., Ltd. A specific example of a high-purity bisphenol A type epoxy resin is "YL980" manufactured by Mitsubishi Chemical Corporation. A specific example of a hydrogenated bisphenol A glycidyl ether is "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, per 100 parts by mass of the thermosetting binder.

[0021] As the thermal cationic polymerization initiator, known initiators for thermal cationic polymerization of epoxy compounds can be used. For example, known initiators that generate an acid capable of cationic polymerization of a cationic polymerizable compound by heat can be used, such as iodonium salts, sulfonium salts, phosphonium salts, and ferrocenes. Among these, aromatic sulfonium salts that exhibit good temperature latency can be preferably used. A specific example of an aromatic sulfonium salt-based polymerization initiator is "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, and 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, per 100 parts by mass of the thermosetting binder.

[0022] Other additives that may be blended into 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 also 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). It is preferable that the conductive particles in the conductive film are aligned in the plane direction. In other words, it is preferable that the conductive film is regularly arranged. Aligning the conductive particles in the plane direction makes it easier to design a uniform particle surface density, thereby improving conductivity and insulation. Examples of a state in which the conductive particles are aligned in the plane direction include 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, such as an oblique lattice, a hexagonal lattice, a square lattice, a rectangular lattice, and a parallelepiped lattice. "Aligning the conductive particles in the plane direction" can also be expressed as the conductive particles being arranged in a planar view of the film. The arrangement of the conductive particles in the plane direction may also be random, or may have multiple 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 they may also form units consisting of multiple particles that are intentionally in contact with each other.

[0024] The particle surface density of the anisotropic conductive film can be appropriately designed depending on 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 Above, 20,000 pieces / mm ２ More than 40,000 pieces / mm ２ More than 50000 pieces / mm ２ The upper limit of the particle surface density is 1,500,000 particles / mm ２ Below, 1,000,000 pieces / mm ２ Below, 500,000 pieces / mm ２ Below, 100,000 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 film is formed during production. When calculating the particle number density from multiple pieces, the particle surface density can be calculated from the area including the pieces and spaces, excluding the spaces between the pieces, 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, metal particles containing 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), or tin alloy solder may be used. Furthermore, the metal particles may be metal-coated metal particles coated with a metal such as nickel, copper, silver, gold, palladium, tin, nickel boride, or ruthenium, or an alloy such as solder. Further, metal-coated resin particles may be used, 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, or ruthenium, or an alloy such as solder. Furthermore, metal-coated inorganic particles may be used, 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, or ruthenium, or an alloy such as solder. Furthermore, 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 multiple layers of different metals. Furthermore, insulating-coated conductive particles may be used, in which these conductive particles are subjected to an insulating coating treatment by coating with, for example, a resin layer, resin particles, inorganic particles, or other insulating particles.

[0026] 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. The conductive particles may also have protrusions on their surfaces 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 substrate 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 micro LED elements, 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 measured using an imaging particle size distribution analyzer (e.g., FPIA-3000, manufactured by Malvern Instruments). The number is preferably 1,000 or more, preferably 2,000 or more. When determining the particle diameter from a film, it may be determined by observing images using an electron microscope such as a SEM. The number of particles measured is 50 or more, preferably 200 or more. These particle diameters can be considered average particle diameters.

[0028] (Measurement of the reaction rate of individual pieces) In the case of a curable resin film utilizing the reaction of an epoxy compound, for example, the reaction rate of the methyl group (2930 cm ) in the IR spectrum is measured using FT-IR. －１ around 914 cm －１ The peak heights of the epoxy groups (around 1000 nm) were measured, and the reaction rate was calculated as 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, as shown in the following formula: Reaction 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. Note that if the epoxy group peak overlaps with other peaks, the peak height of the sample that has been completely cured (reaction rate 100%) can be set to 0%.

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

[0031] Furthermore, when the peak height of the (meth)acryloyl group is small or when an alicyclic epoxy group or oxetanyl group is present, the reaction rate may be determined, for example, by HPLC (High Performance Liquid Chromatography). The reaction rate of individual pieces can be calculated from the chromatogram obtained by HPLC using the decay rate of the reactive component before and after the reaction (before and after laser irradiation) using 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] 1 , an ultrashort pulse laser LD is irradiated onto a 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 pulse widths of femtoseconds (fs) to several picoseconds (ps), and are also known as femtosecond lasers, picosecond lasers, etc. Because the pulse width of an ultrashort pulse laser is shorter than the time required for heat conduction, ablation processing using an ultrashort pulse laser can dramatically reduce thermal effects and suppress the hardening reaction of individual pieces compared to YAG or excimer lasers with nanosecond (ns) pulse widths. Furthermore, ablation processing using an ultrashort pulse laser can be performed with high precision without causing thermal deformation or heat-affected zones, thereby improving the fit between the actual geometric shape of the individual pieces and the ideal geometric shape, and achieving excellent shape precision.

[0035] As a specific example of an ultrashort pulse laser, a femtosecond laser with a pulse width of 10 to 1000 fs is preferably used, and the pulse width can be appropriately selected depending on the material of the curable resin film. The wavelength can also be appropriately selected depending on the material of the curable resin film to be processed, such as UV (ultraviolet), green (visible), or IR (infrared). Among these, ultraviolet (UV) light has a shallow penetration depth, a small focal spot diameter, and a large focal depth, making it advantageous for processing small shapes and allowing for a narrow pitch between individual pieces. This allows for a larger effective area on the substrate where individual pieces can be used, improving yield and enabling the angle of the side surface of each individual piece relative to the first surface to approach 90°.

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

[0037] (Shape of Individual Film) FIG. 2 is a cross-sectional view schematically illustrating an 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 relative to the first surface 3A of the individual film 3 is preferably 70° or more. In other words, it is preferable that the angle β of the slope of the side surface 3C relative to the perpendicular to the second surface 3B of the individual film 3 is 20° or less, and the taper angle (2β) of the cross section of the individual film 3 is 40° or less. Here, the taper angle is the extent (opening angle) of the slope of both side surfaces of the cross section of the individual film 2. The upper limit of the angle α of the side surface 3C relative to the first surface 3A of the individual film 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 relative to the first surface 3A of the individual film 3 can be measured using, for example, a three-dimensional measuring machine.

[0038] By setting the angle α of the side surface 3C relative to the first surface 3A of the chip 3 to 70° or more, the difference between the area of ​​the top surface and the area of ​​the bottom surface is not too large, improving the landing performance during laser lift-off (LLO) transfer and improving the transfer rate. This also improves the transmittance of micro LED displays using the chips. Furthermore, when the chips are made of conductive film or anisotropic conductive film, the particle capture rate at the edges of the chips can be improved.

[0039] Furthermore, by ablating the curable resin film using an ultrashort pulse laser to form the individual pieces 3, the occurrence of defective pieces such as insufficient processing, chipping, and peeling 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 nanosecond (ns) pulse width. The yield rate of the individual pieces is preferably 90% or higher, and more preferably 95% or higher. Here, "insufficient processing" refers to, for example, an excess area of ​​the predetermined shape being 20% ​​or more (120% or more when the area of ​​the predetermined shape is 100%), "chips" refers to, for example, an excess area of ​​80% or less of the area of ​​the predetermined shape (80% or less when the area of ​​the predetermined shape is 100%), and "peeling" refers to, for example, the film overlapping at a portion of the edge. In other words, it is preferable that the individual pieces be more than 80% but less than 120% of the area of ​​the predetermined shape. Even if the individual pieces have insufficient processing, chips, peeling, etc., they may be used as is if they are suitable for 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 it is preferable that the angle of the side surface of each piece 3 with respect to the first surface is 70° or more. For example, when the substrate 3 is glass, it may be circular, rectangular, or square. Furthermore, when the substrate 2 is 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 schematically showing an example of the end shape of a film piece. When a curable resin film is ablated linearly using an ultrashort pulse laser, as shown in FIG. 3, the straightness measured at 10 positions 2 μm apart 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 linear portions of the pieces straighter and sharper, improving the design of the pieces and improving the fit between the actual geometric shape of the pieces and the ideal geometric shape, thereby achieving excellent shape accuracy. It is believed that this also contributes to productivity, as it makes it easier to reflect the design concept in the actual product and improves analysis accuracy.

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

[0043] JIS B0621 defines straightness as "the size of a target from a geometrically correct straight line of a linear body." In this specification, 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 by the least squares method.

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

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

[0046] The shape of the pieces is not particularly limited, and can be formed into 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 form rectangular pieces of several tens of micrometers square as shown in Figure 4(A) or square pieces as shown in Figure 4(B) in accordance with the element size of the micro LED. Alternatively, elliptical pieces as shown in Figure 4(C) or circular pieces as shown in Figure 4(D) may be formed.

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

[0048] In the first example shown in Figure 4, all of the curable resin other than the individual pieces was removed, but as in the second example shown in Figure 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 to the shape of the individual pieces. According to the second example, the curable resin in the spaces between the individual pieces is not removed, thereby shortening the processing time for the individual pieces.

[0049] 6A and 6B are plan views schematically illustrating a first example of a method for producing conductive film pieces, in which Fig. 6A shows the conductive film before processing, and Fig. 6B shows the film pieces after processing. As shown in Fig. 6A and 6B, in the first example of the method, an ultrashort pulse laser beam is irradiated onto a conductive film containing conductive particles 4 in a curable resin film 2 to form an image, and the conductive film is divided into pieces 3 of a predetermined shape.

[0050] (Second example of manufacturing method for individual pieces of conductive film) Figure 7 is a plan view schematically showing a second example of manufacturing method for 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 the conductive particle transfer mold, and Figure 7(D) shows the individual piece film after transfer.

[0051] In the second manufacturing method example, first, as shown in FIGS. 7(A) and 7(B), an ultrashort pulse laser beam is irradiated onto a curable resin film 2 to form an image, thereby dividing the curable resin film into pieces 3 of a predetermined shape. Next, as shown in FIG. 7(C), a conductive particle transfer mold 5 having conductive particles 4 arranged thereon is prepared. The pieces 3 formed on the substrate 1 and the conductive particle transfer mold 5 are brought into opposition and pressed together, thereby transferring the conductive particles 4 to the pieces 3, as shown in FIG. 7(D). Here, the conductive particle transfer mold 5 can be designed to match the pieces 3, thereby reducing the cost of the conductive particles. Furthermore, in the second manufacturing method example, because 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.

[0052] Figure 8 is a plan view schematically showing a third example of a method for manufacturing individual pieces of conductive film, where Figure 8(A) shows the 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, in the first cycle, as shown in FIGS. 8(A) and 8(B), an ultrashort pulse laser beam is irradiated onto the curable resin film 2 to create an image, 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 and pressed together, thereby transferring the conductive particles 4 to the pieces 3, as shown in FIG. 8(D). Then, in the second cycle, as shown in FIGS. 8(E) and 8(F), an ultrashort pulse laser beam is irradiated onto the curable resin film 2 to create an image, 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 cycle is prepared, and the pieces 3 formed on the substrate 1 and the conductive particle transfer mold 5 are opposed and pressed together, thereby transferring the conductive particles 4 to the pieces 3, as shown in FIG. 8(H). Here, as shown in Figures 8(A) and 8(F), when singulating, the pitch between the individual pieces and the space is set to 1:1 or more, and as shown in Figures 8(C) and 8(G), during the second round of conductive particle transfer, the individual pieces 3 and the conductive particle transfer mold 5 are placed opposite each other with a one-pitch offset. This allows the same conductive particle transfer mold 6 to be used in the first and second rounds, thereby reducing costs. Furthermore, 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. Note that 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 Manufacturing Connection Structure and Connection Structure The method for manufacturing a connection structure according to the present embodiment includes an arrangement step of arranging a first electronic component and a second electronic component via a film piece, and a curing step of crimping the first electronic component and the second electronic component using a crimping tool and curing the film piece. Here, crimping may be replaced with reflow.

[0055] Furthermore, the connection structure according to this embodiment comprises 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 film pieces whose side faces are at an angle of 70° or more relative to the first surface, and therefore can improve the transmittance of the display when, for example, a micro LED is mounted. Also, when the film pieces are ACFs, the particle capture rate at the ends of the film pieces can be improved.

[0057] The first electronic component and the second electronic component are not particularly limited and can be appropriately selected depending on the purpose. Examples of the first electronic component include wiring substrates and printed wiring boards (PWBs) for display applications such as LCD (Liquid Crystal Display) panels, organic electroluminescent (OLED) displays, 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, a glass epoxy substrate such as an FR-4 substrate, or plastics such as thermoplastic resins and ceramics. Examples of the wiring substrate include glass substrates and plastic substrates. Examples of the second electronic component include LEDs (including micro LEDs), integrated circuits (ICs), flexible printed circuits (FPCs), tape carrier package (TCP) substrates, and chip-on-film (COF) substrates in which an IC is mounted on an FPC. The number of second electronic components relative to the first electronic component does not need to be in a 1:1 correspondence; multiple second electronic components may be mounted on the first electronic component. The second electronic component may be stacked on the first electronic component.

[0058] A manufacturing method of a display device using a film chip will be described below. The manufacturing method of a display device shown as an example includes a transfer step (A) in which a laser lift-off device is used to transfer chips of a predetermined shape to a predetermined position on a wiring board, and a mounting step (B) in which the laser lift-off device is used to arrange light-emitting elements at predetermined positions on the wiring board and mount the light-emitting elements on the wiring board. The chips are the same as those described above, so a description thereof will be omitted here.

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

[0060] 9 is a diagram schematically illustrating an example of a laser lift-off apparatus. As shown in FIG. 9, the laser lift-off apparatus 10 includes a laser scanner 11 that scans the optical axis of a laser beam, a mask 12 having a plurality of openings of a predetermined shape arranged at a predetermined pitch, a projection lens 13 that reduces and projects the laser beam onto a donor substrate, a donor stage that holds the donor substrate, and a receptor stage that holds a receptor substrate. In the transfer of the individual film, an individual substrate 20 having a plurality of individual pieces 22 formed on a base material 21 is held on the donor stage as a donor substrate, and individual pieces 23 separated from the individual substrate 20 are landed on a wiring substrate that serves as a receptor substrate.

[0061] 10 is a cross-sectional view schematically illustrating a state in which a film piece and a wiring substrate are placed opposite each other. As shown in FIG. 10, in the transfer step (A), first, the substrate piece 30 and the wiring substrate 40 are placed opposite each other.

[0062] Substrate piece 30 includes a base material 31 and pieces 33 made of a conductive film containing conductive particles 32, with the pieces 33 arranged in units of light-emitting elements on the surface of base material 31. Base material 31 may be any material as long as it 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 substrate 40 includes a first-conductivity-type circuit pattern and a second-conductivity-type circuit pattern on a base material 41. The wiring substrate 40 has a first electrode 42 and a second electrode 43 at positions corresponding to, for example, 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) constituting one pixel. The wiring substrate 40 also includes circuit patterns such as matrix wiring data lines and address lines, enabling the light-emitting elements corresponding to each sub-pixel constituting one pixel to be turned on and off. 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.

[0064] Furthermore, when the wiring substrate 40 is used for a transparent display, it is preferable that the wiring substrate 40 is a light-transmitting substrate, 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 thereof.

[0065] 11 is a cross-sectional view schematically illustrating a state in which laser light is irradiated from the substrate side, and conductive film pieces are transferred and arranged at predetermined positions on a wiring substrate. As shown in FIG. 11 , in the transfer step (A), laser light is irradiated from the substrate 31 side using the laser lift-off device described above, and conductive film pieces 33 are transferred and arranged at predetermined positions on a wiring substrate 40. The distance between the pieces 33 and the wiring substrate 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 pieces 33 can be arranged in subpixel units on the wiring board 40. Furthermore, if the size of the wiring board 40 is larger than the size of the base material 31, the pieces 33 can be arranged in subpixel units in the screen area of ​​the wiring board 40 by aligning the base material 31 multiple times and transferring the pieces 33.

[0067] The reaction rate of the conductive film pieces 33 after the transfer step (A) is preferably 25% or less, more preferably 20% or less, and even more preferably 15% or less. Having a reaction rate of 25% or less of the conductive film pieces 33 after the transfer step (A) enables the light-emitting element to be thermocompression-bonded in the subsequent mounting step (B). The reaction rate can be measured, for example, using FT-IR, as described above.

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

[0069] The light emitting element 50 includes a main 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 main 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-type layer and a second-conductivity-type cladding layer made of, for example, p-GaN. A first-conductivity-type electrode 52 is formed on a portion of the first-conductivity-type cladding layer using a passivation layer, and a second-conductivity-type electrode 53 is formed on a portion 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 concentrate in the active layer and recombine, generating light emission.

[0070] The light-emitting elements 50 are arranged on the wiring substrate 40 in correspondence with the sub-pixels that make up one pixel, thereby 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] Examples of subpixel arrangement methods for RGB include a stripe arrangement, a mosaic arrangement, and a delta arrangement. The stripe arrangement arranges RGB in vertical stripes, which allows for higher resolution. The mosaic arrangement arranges the same RGB colors diagonally, which allows for a more natural image than the stripe arrangement. The delta arrangement arranges RGB in a triangular shape, with each dot shifted by half a pitch for each field, allowing 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 substrate 40 using the laser lift-off apparatus described above. In the laser lift-off apparatus described above, the light emitting element 50, which is a donor substrate, is held on a donor stage, and the wiring substrate 40, which is a receptor substrate, is held on a receptor stage. The distance between the light emitting element and the wiring substrate is preferably 10 to 1000 μm, more preferably 50 to 500 μm, and even more preferably 80 to 200 μm.

[0073] The light-emitting element 50 can be connected to the wiring substrate 40 by any suitable method, such as thermocompression bonding, photocompression bonding, or thermo-photocompression bonding, which are commonly used in known anisotropic conductive films. Furthermore, when the conductive particles are solder particles, for example, reflow bonding may be used. Thermocompression bonding conditions include, for example, a temperature of 150°C to 260°C, a pressure of 1 MPa to 60 MPa, and a time of 5 seconds to 300 seconds. When the conductive film hardens, a cured film is formed, and the light-emitting element 50 can be anisotropically connected to the wiring substrate 40 with no cured film between the light-emitting elements 50, leaving the wiring substrate 40 exposed. Furthermore, by using a light-transmitting substrate as the wiring substrate 40, superior light transmittance can be achieved compared to when a conductive film is attached to the entire surface of the wiring substrate 50.

[0074] 3. First Example In the first example, an anisotropic conductive film was produced as a conductive film, and the anisotropic conductive film was diced into pieces of a predetermined size. Then, the gradient angle of the piece ends, the yield of the pieces, the space between the pieces, the reaction rate of the pieces, and the transfer rate of the pieces 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 to 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-plated 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 produce an anisotropic conductive film in which conductive particles were aligned to a thickness of 4 μm on the base film.

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

[0078] [Evaluation of the yield rate of individual pieces] Figure 13 is a micrograph including pieces with poor shape due to insufficient processing, chipping, and peeling. The appearance of 100 pieces on the base film was observed using a microscope, and the number of pieces with poor shape (insufficient processing, chipping, peeling, etc.) was counted. The yield rate of the individual pieces was evaluated according to the following criteria depending on the number of pieces with poor shape. The yield rate of the individual pieces is preferably rated B or higher. Here, "insufficient processing" refers to a surplus area of ​​the predetermined shape of 20% or more (120% or more when the area of ​​the predetermined shape is 100%). "Chips" refers to a surplus area of ​​80% or less of the area of ​​the predetermined shape (80% or less when the area of ​​the predetermined shape is 100%). "Picking" refers to a surplus area of ​​80% or less of the area of ​​the predetermined shape. "Picking" refers to a surplus area of ​​the film overlapping at a portion of the edge. A: 1pcs or less 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 Pieces] The space between pieces on the base film was measured using a microscope. The space between pieces was evaluated according to the following criteria depending on the number of defective pieces. The evaluation of the space between pieces is preferably C or higher. A: 10 μm or less B: More than 10 μm and 20 μm or less C: More than 20 μm and 30 μm or less D: More than 30 μm

[0080] [Evaluation of Reaction Rate of Individual Pieces] Samples of the anisotropic conductive film before singulation and the individual piece samples were taken, and each sample was irradiated with infrared light to measure the IR spectrum. －１ around 914 cm －１ The peak heights of the epoxy groups (near singulation) were measured, and the reaction rate was calculated as the ratio of the peak height of the epoxy groups to the peak height of the methyl groups before and after singulation, as shown in the following formula: Reaction rate (%) = {1 - (a / b) / (A / B)} x 100 In the above formula, A is the peak height of the epoxy groups of the anisotropic conductive film sample before singulation, B is the peak height of the methyl groups of the anisotropic conductive film sample before singulation, a is the peak height of the epoxy groups of the individual sample, and b is the peak height of the methyl groups 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 30% or less C: More than 30% and 50% or less D: More than 50%

[0082] [Evaluation of Transfer Rate of Pieces] The pieces separated 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) to the substrate, and the 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: 248 nm Pulse width: 30,000 ps Pulse energy: 600 mJ Fluence: 150 mJ / cm ２ Repetition frequency: 0.01 kHz Number of laser irradiations: 1

[0083] Example 1 A femtosecond laser was used to irradiate the anisotropic conductive film with laser light from the film side to draw a straight line, and the anisotropic conductive film was singulated into square pieces of 60 μm × 60 μm. The irradiation conditions of the laser device were as follows: Wavelength: 343 nm Pulse width: 500 fs Output: 0.245 to 0.38 W Pulse energy: 0.081 to 0.127 J Irradiation spot area: φ10 μm (78.5 μm ２ Fluence: 0.21 to 0.32 J / cm ２ Repetition frequency: 3000 kHz Laser scanning speed: 3000 mm / sec Number of laser irradiations: 20 times

[0084] As shown in Table 1, in Example 1, the gradient of the side surface of each piece 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, when an area of ​​100 mm x 100 mm was singulated, the number of pieces was approximately 2 million, and the singulation time was approximately 40 minutes.

[0085] FIG. 14 is a micrograph of an individual film obtained by singulating an 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 in Example 1, the space between the individual pieces can be narrowed. It can also be seen that the outlines of the individual pieces are more linear, resulting in excellent shape accuracy. It can also be seen that in Example 1, the outlines of the individual pieces after transfer are more linear. Note that in this specification, the magnification of the micrographs is approximately the same for comparison objects.

[0086] Example 2 was the same as 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%. Furthermore, when singulating an area of ​​100 mm × 100 mm, the number of pieces was approximately 4 million, and the singulation time was approximately 50 minutes.

[0087] FIG. 16 is a micrograph of an individual film obtained by singulating an 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 of the individual pieces are more linear, resulting in excellent shape accuracy. It can also be seen that in Example 2, the outlines of the individual pieces after transfer are more linear.

[0088] Comparative Example 1: Using an excimer laser lift-off device, laser light was irradiated from the substrate film side to remove portions 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: 248 nm, pulse width: 30,000 ps, ​​pulse energy: 4 J, fluence: 1 J / cm. ２Repetition frequency: 0.01 kHz 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 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 97%. Furthermore, when an area of ​​100 mm x 100 mm was singulated, the number of pieces 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 singulating 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 in Comparative Example 1, the spaces between the individual pieces are large. It can also be seen that the outlines of the individual pieces are not linear, and good shape accuracy is not achieved. Furthermore, 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 outlines of the transferred individual pieces are not linear.

[0091] Comparative Example 2 was the same as 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%. Furthermore, when singulating an area of ​​100 mm × 100 mm, the number of pieces 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 singulating 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 in Comparative Example 2, the spaces between the individual pieces are large. It can also be seen that the outlines of the individual pieces are not linear, and good shape accuracy is not achieved. Furthermore, 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 outlines of the transferred individual pieces are not linear.

[0093] Comparative Example 3 was the same as Comparative Example 1, except that the anisotropic conductive film was singulated into rectangular pieces of 30 μm × 40 μm. 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 singulating 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 in Comparative Example 3, the spacing between the individual pieces is large. It can also be seen that the outlines of the individual pieces are not linear, and good shape accuracy is not achieved. Furthermore, as shown in FIG. 23 , in Comparative Example 3, there are gaps and misaligned areas where the individual pieces do not land on the substrate during transfer, and the outlines of the transferred individual pieces are not linear.

[0095] Comparative Example 4: A YAG laser was used to irradiate the anisotropic conductive film with laser light from the anisotropic conductive film side to draw a line, and the anisotropic conductive film was singulated into square pieces of 30 μm × 30 μm. The irradiation conditions of the laser device were as follows: wavelength: 266 nm, pulse width: 8000 ps, ​​energy intensity: 10%, number of laser irradiations: 10 times.

[0096] As shown in Table 1, in Comparative Example 4, the gradient of the side surface of each piece was evaluated as A, the yield of each piece was evaluated as A, the space between each piece was evaluated as A, and the reaction rate of each piece was evaluated 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 into 150 μm × 150 μm square pieces using a dicer used for dicing wafers. As shown in Table 1, the gradient of the side surface of each piece in Comparative Example 5 was evaluated as C, the yield of each piece was evaluated as C, the spacing between pieces was evaluated as C, and the reaction rate of each piece was evaluated as A. Because dicing involves physical cutting, there is a limit to the size of the pieces that can be cut without blocking (peeling off from the substrate) the adhesive film, making it difficult to produce pieces smaller than 100 μm. Furthermore, the edge shape of the pieces was distorted due to the cutting edge.

[0098]

[0099] In Comparative Examples 1 to 3, the portions removed by laser lift-off were large, and the spaces between pieces were large, so the evaluation of the space between pieces and the evaluation of the yield of pieces were not good. Furthermore, 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. Furthermore, in Comparative Example 4, the laser pulse width was on the order of nanoseconds, so the hardening reaction of the pieces progressed, making it difficult for the anisotropic conductive film to function. Furthermore, 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 pieces were not good.

[0100] On the other hand, in Examples 1 and 2, the anisotropic conductive film was singulated using a femtosecond laser, which allowed for a narrower inter-piece pitch, resulting in favorable evaluations of the yield and inter-piece spacing. Furthermore, in Examples 1 and 2, the effective area available for the individual pieces was increased, resulting in approximately five times more individual pieces than in Comparative Examples 1 and 2 when the same area was processed. Furthermore, in Examples 1 and 2, excellent shape accuracy was achieved, and the evaluation of the gradient of the individual piece side surface and the individual piece transfer rate were favorable. Furthermore, in Examples 1 and 2, the curing reaction was suppressed, resulting in favorable evaluations of the individual piece reaction rate.

[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, a contour was extracted from the binarized image. 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 calculated using the least squares method from the positions (x, y) of the 10 measurement points, and the correction value Y for the 10 measurement points was calculated from this quadratic function. Then, for each of 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 and minimum difference values ​​was taken as the straightness. The straightness was calculated for each of 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. Furthermore, for the 10 arbitrary pieces whose straightness was determined in Example 1, the straightness of all four sides 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 outlines of the pieces in Example 1 is better than that of Comparative Example 1.

[0104]

[0105] 1 Substrate, 2 Curable resin film, 3 Piece, 3A First surface, 3B Second surface, 3A Side, 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 conductivity type electrode, 53 Second conductivity type electrode

Claims

1. A method for producing individual films, in which 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 films of a predetermined shape.

2. The method for producing individual film pieces 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. A method for producing individual film pieces as described in claim 1 or 2, in which 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. A method for producing individual film pieces 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, and 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. An individual film containing a curable resin, the angle of a side surface relative to the first surface being 70° or more.

8. The individual film according to claim 7, which has a shape in which the straightness measured at 10 positions spaced 2 μm apart is 1.5 μm or less.

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

10. A method for manufacturing a connection structure, comprising: an arrangement step of arranging a first electronic component and a second electronic component via an individual film containing a curable resin and having a side angle of 70° or more relative to a first surface; and a hardening step of crimping the first electronic component and the second electronic component with a crimping tool and hardening the individual film.

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

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

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

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

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