Method for manufacturing light-emitting device and black transfer film

Abstract

A method for manufacturing a light-emitting device having a black matrix on at least a portion of the periphery of a light-emitting element disposed on a wiring substrate, the method for manufacturing the light-emitting device includes: (step a) a step of causing a black transfer film, in which a black transfer layer is formed on one surface of a translucent base material, to face the wiring substrate from the black transfer layer side before the light-emitting element is disposed; (step b) a step in which laser light is irradiated from the translucent base material side of the black transfer film, thereby transferring a single piece of the black transfer layer to a position on the wiring substrate where the light-emitting element is to be arranged; and (step c) arranging and mounting the light-emitting elements on the single piece of the black transfer layer transferred to the wiring substrate, thereby deforming the black transfer layer, forming a black matrix on at least a part of the periphery of the light-emitting elements, and connecting the light-emitting elements to the wiring substrate.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a light-emitting device such as an image display device or a lighting device using a light-emitting element such as a micro LED (Light Emitting Diode) and a black transfer film used in the manufacturing method. Background Art

[0002] In recent years, micro-LED displays have been developed to emit light by micro-LEDs with high luminous efficiency and long life, and thus are expected to have preferred characteristics such as high brightness, low power consumption, high contrast, and long life. In such micro-LED displays, red LEDs, green LEDs, and blue LEDs are arranged at predetermined intervals on a display substrate, and they emit light spontaneously, so color filters that use a black matrix to distinguish each color are sometimes not used. In this case, a black matrix needs to be formed between micro-LEDs to prevent color mixing (Patent Documents 1 and 2).

[0003] As methods for forming a black matrix in a micro-LED display, the following methods are known: (a) a method of applying a composition for forming a black transfer layer to the entire surface of one side of a display substrate before the micro-LED is installed, and removing the black transfer layer forming composition applied to the non-black matrix area of ​​the display substrate by etching or photolithography; (b) a method of aligning and bonding a black transfer film formed by screen printing on a carrier film to the display substrate before the micro-LED is installed, and peeling off the carrier film; (c) a method of covering a display substrate on which micro-LEDs are installed with a glass cover sheet on which a black matrix is ​​formed; and (d) a method of applying a black matrix ink composition between micro-LEDs on a display substrate on which micro-LEDs are installed by an inkjet method.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application No. 2021-506108

[0007] Patent document 2: WO2021 / 060832A1 publication Summary of the invention

[0008] Problems to be solved by the invention

[0009] However, in the method (a), it takes time to form the black matrix, in the methods (b) and (c), the positional accuracy of the black matrix cannot be said to be sufficient, and in the method (d), it is difficult to form the black matrix at a height sufficient to suppress the color mixing of the micro-LEDs. In addition, these methods require sufficient alignment accuracy when installing the micro-LEDs.

[0010] The purpose of the present invention is to eliminate the need for forming a black matrix when manufacturing a light-emitting device such as an image display device or a lighting device using micro LEDs, so that the position accuracy of the black matrix is ​​sufficient, the black matrix can be formed at a height sufficient to suppress the color mixing of the micro LEDs, and the alignment accuracy when installing the micro LEDs is sufficient.

[0011] Solutions for solving problems

[0012] The present inventors have found that the above-mentioned object can be achieved by utilizing a laser lift-off method known as one of the manufacturing technologies for semiconductor devices, thereby completing the present invention.

[0013] (First option)

[0014] That is, a first aspect of the present invention is a method for manufacturing a light emitting device having a black matrix at least partially around a light emitting element arranged on a wiring substrate, the method for manufacturing the light emitting device comprising the following steps a, b, and c.

[0015] (Process a)

[0016] A step of placing a black transfer film having a black transfer layer formed on one surface of a light-transmitting base material opposite to a wiring substrate before arranging light-emitting elements from the black transfer layer side.

[0017] (Process b)

[0018] Next, a step is performed in which a laser beam is irradiated from the light-transmitting base side of the black transfer film to transfer the single sheet of the black transfer layer to a position of the wiring board where the light-emitting element is to be arranged.

[0019] (Process c)

[0020] The light emitting element is arranged and mounted on a single piece of a black transfer layer transferred to a wiring substrate, thereby deforming the black transfer layer to form a black matrix around at least a portion of the light emitting element and connecting the light emitting element to the wiring substrate.

[0021] (Second Option)

[0022] A second aspect of the present invention is a method for manufacturing a light emitting device having a black matrix at least partially around a light emitting element disposed on a wiring substrate, the method comprising the following steps A1a and A1b.

[0023] (Process A1a)

[0024] A step of placing a black transfer film having a black transfer layer formed on one surface of a light-transmitting base material opposite to a wiring substrate on which a light-emitting element is arranged from the black transfer layer side.

[0025] (Process A1b)

[0026] Next, a step of irradiating the black transfer film with laser light from the light-transmitting base side to transfer the individual pieces of the black transfer layer to at least a portion of the periphery of the light-emitting element of the wiring board to form a black matrix is ​​performed.

[0027] (Third Option)

[0028] In addition, a third embodiment of the present invention is a method for manufacturing a light-emitting device having a black matrix at least partially around a light-emitting element arranged on a wiring substrate, the method for manufacturing the light-emitting device comprising the following steps A2a, A2b and B.

[0029] (Process A2a)

[0030] A step of placing a black transfer film having a black transfer layer formed on one surface of a light-transmitting base material opposite to a wiring substrate before arranging light-emitting elements from the black transfer layer side.

[0031] (Process A2b)

[0032] Next, a step of irradiating the black transfer film with laser light from the light-transmitting substrate side to transfer the individual pieces of the black transfer layer to at least a portion of the wiring board around the position where the light-emitting element is to be arranged, thereby forming a black matrix.

[0033] (Process B)

[0034] A step of placing light-emitting elements between black matrices transferred to a wiring substrate.

[0035] In the first to third embodiments of the present invention described above, the light-emitting element is preferably a micro-LED. As a black transfer film, a black transfer film in which a black transfer layer is provided on a single surface of a light-transmitting substrate in its entirety can be used. Preferably, the black transfer film is a single piece of a black transfer layer and at least a portion of the surroundings of a position where the light-emitting element should be arranged on a wiring substrate, preferably a black transfer film provided on a light-transmitting substrate corresponding to the entire surroundings. In addition, the black transfer layer of the black transfer film may contain conductive particles. By containing conductive particles, the black transfer layer can be given conductivity or anisotropic conductivity.

[0036] (Fourth Option)

[0037] A fourth aspect of the present invention is a black transfer film used in the first to third aspects of the present invention and for forming a black matrix by a laser lift-off method.

[0038] More specifically, the fourth scheme of the present invention is a black transfer film, which has a translucent substrate and a black transfer layer formed on a single surface of the translucent substrate. The black transfer layer contains a black pigment and a thermosetting composition, and the visible light transmittance of the black transfer layer according to JIS K7375 is less than 20%, and the viscosity according to JIS Z0237 is more than 0.1MPa. In the black transfer film, the black transfer layer can be provided on the translucent substrate in an entire surface, preferably in a monolithic manner on the translucent substrate corresponding to the black matrix to be formed. In addition, the black transfer layer of the black transfer film may also contain conductive particles as described above, and the black transfer layer containing conductive particles can show conductivity or anisotropic conductivity. Such a black transfer layer can be preferably used to obtain conduction between electrodes, so that the formation of the black matrix and the connection of the light-emitting element can be achieved simultaneously, which can simplify the manufacturing process and reduce the manufacturing cost.

[0039] Effects of the Invention

[0040] In the manufacturing method of the light-emitting device such as the image display device and the lighting device of the present invention, the so-called laser lift-off method is used, so there is no need to form a black matrix, the position accuracy of the black matrix is ​​sufficient, the black matrix can be formed at a height sufficient to suppress the color mixing of the micro-LED, and the alignment accuracy when installing the micro-LED can be sufficient. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1A This is a process diagram for explaining the first embodiment of the present invention.

[0042] Figure 1B This is a process diagram for explaining the first embodiment of the present invention.

[0043] Figure 1C This is a process diagram for explaining the first embodiment of the present invention.

[0044] Figure 1D This is a process diagram for explaining the first embodiment of the present invention.

[0045] Figure 1E This is a process diagram for explaining the first embodiment of the present invention.

[0046] Figure 2A It is a process explanation diagram of the second embodiment of the present invention.

[0047] Figure 2B It is a process explanation diagram of the second embodiment of the present invention.

[0048] Figure 2C It is a process explanation diagram of the second embodiment of the present invention.

[0049] Figure 3A It is a process explanation diagram of the third embodiment of the present invention.

[0050] Figure 3B It is a process explanation diagram of the third embodiment of the present invention.

[0051] Figure 3C It is a process explanation diagram of the third embodiment of the present invention.

[0052] Figure 3D It is a process explanation diagram of the third embodiment of the present invention.

[0053] Figure 3E It is a process explanation diagram of the third embodiment of the present invention. DETAILED DESCRIPTION

[0054] Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. It should be noted that in each of the drawings, the same reference numerals represent the same or equivalent components.

[0055] <First aspect of the present invention>

[0056] The first embodiment of the present invention is a method for manufacturing a light-emitting device, which is an image display device, a lighting device, etc., and has a black matrix around at least a portion of a light-emitting element arranged on a wiring substrate. The method for manufacturing the light-emitting device includes the following steps a, b, and c.

[0057] (Process a)

[0058] Step a is a step of placing the black transfer layer and the wiring substrate opposite to each other in order to transfer the single sheet of the black transfer layer to the wiring substrate. Specifically, Figure 1A As shown in FIG. 1 , a black transfer film 5 having a black transfer layer 4 formed on one side of a light-transmitting substrate 3 is placed opposite to a wiring substrate 2 having wiring 1 formed thereon before arranging light-emitting elements from the black transfer layer 4 side. Figure 1A In the embodiment, the black transfer layer 4 is formed monolithically on one side of the light-transmitting substrate 3, but may be formed entirely on one side of the light-transmitting substrate 3. As a method for providing the black transfer layer 4 monolithically on one side of the light-transmitting substrate 3, a known method such as a screen printing method, an etching method, and an inkjet method may be used.

[0059] (Process b)

[0060] Then, if Figure 1B As shown, by using the laser lift-off method, laser L is irradiated from the light-transmitting substrate 3 side of the black transfer film 5, thereby transferring a single piece of the black transfer layer 4 to the position where the light-emitting element should be arranged on the wiring substrate 2 (i.e., the position covering the wiring 1). As a laser lift-off device for implementing the laser lift-off method, a laser lift-off device (MT-30C200) can be used. It should be noted that even if the black transfer layer 4 is provided on the entire surface of the light-transmitting substrate 3, the black transfer layer can be transferred in a single piece by the laser lift-off method.

[0061] (Process c)

[0062] Step c is a step of forming a black matrix and mounting a light emitting element by thermal compression bonding, reflow soldering, etc. Specifically, Figure 1C As shown, the light emitting element 6 (R, G, B) is arranged on a single piece of the black transfer layer 4 transferred to the wiring substrate 2 from its electrode 6a side, as shown in FIG. Figure 1D As shown in FIG. 1 , a step of performing thermal compression bonding using a welding head 7 or the like, thereby deforming the black transfer layer 4. Figure 1E As shown, a black matrix 8 as a product of thermal curing of the deformed black transfer layer 4 can be formed around at least a portion of the light emitting element 6, preferably around the entire periphery, and the light emitting element 6 is connected to the wiring substrate 2 to obtain a light emitting device such as an image display device and a lighting device. When configuring the light emitting element 6, it can be configured as needed via the following layers: a layer formed by an adhesive film, a conductive adhesive film containing conductive particles, an anisotropic conductive adhesive film; or a layer formed by a low melting point metal such as solder (e.g., solder paste). The layer is preferably an adhesive layer containing conductive particles.

[0063] <Second aspect of the present invention>

[0064] A second embodiment of the present invention is a method for manufacturing a light-emitting device, wherein the light-emitting device is an image display device, a lighting device, etc., and has a black matrix around at least a portion of a light-emitting element disposed on a wiring substrate, and the method for manufacturing the light-emitting device includes the following steps A1a and A1b. The second embodiment is also an embodiment in which the black matrix is ​​transferred to the wiring substrate on which the light-emitting element is disposed using a laser lift-off method.

[0065] (Process A1a)

[0066] Step A1a is as follows Figure 2A As shown, a process is performed in which a black transfer film 25 having a black transfer layer 24 formed on one side of a light-transmitting substrate 23 is placed opposite to a wiring substrate 22 from the side of the black transfer layer 24, wherein the wiring substrate 22 is formed with wiring 21 and a light-emitting element 26 (R, G, B) is arranged on the wiring substrate 22 from the side of its electrode 26a. When arranging the light-emitting element 26, it can be arranged via the following layers as needed: a layer formed of an adhesive film, a conductive adhesive film containing conductive particles, an anisotropic conductive adhesive film; or a layer formed of a low melting point metal such as solder (e.g., solder paste). This layer is preferably a conductive adhesive layer 29 containing conductive particles.

[0067] (Process A1b)

[0068] Then, if Figure 2BAs shown, by irradiating the black transfer film 25 with laser light L from the light-transmitting substrate 23 side, a single piece of the black transfer layer 24 is transferred to at least a portion of the periphery of the light-emitting element 26 of the wiring substrate 22, and thermally cured as needed to form a black matrix 28. Figure 2C As shown, a light-emitting device such as an image display device or a lighting device can be obtained in which a cured black matrix 28 is formed around at least a portion of, preferably the entire periphery of, a light-emitting element 26 .

[0069] <Third aspect of the present invention>

[0070] The third scheme of the present invention is a method for manufacturing a light-emitting device, which is an image display device, a lighting device, etc., and has a black matrix on at least a portion of the periphery of a light-emitting element arranged on a wiring substrate. The method for manufacturing the light-emitting device includes the following steps A2a, A2b and B.

[0071] (Process A2a)

[0072] Step A2a is as follows Figure 3A As shown, a black transfer film 35 having a black transfer layer 34 formed on one surface of a light-transmitting base material 33 is placed opposite to a wiring substrate 32 having wirings 31 formed thereon before light-emitting elements are arranged from the black transfer layer 34 side.

[0073] (Process A2b)

[0074] Then, using laser lift-off method, such as Figure 3B As shown in FIG. 1 , the laser light L is irradiated from the light-transmitting substrate 33 side of the black transfer film 35, thereby Figure 3C As shown, a single piece of black transfer layer 34 is transferred to at least a portion, preferably the entire periphery of the location where the light emitting element is to be arranged on the wiring substrate 32, and thermally cured as needed to form a black matrix 38.

[0075] (Process B)

[0076] Step B is a step of mounting the light emitting element. Specifically, Figure 3D As shown in FIG. 1 , the light emitting element 36 is arranged between the black matrix 38 transferred to the wiring substrate 32 where no light emitting element is arranged from the electrode 36a side thereof by a known method. Figure 3EAs shown, a light-emitting device such as an image display device or a lighting device can be obtained in which a black matrix 38 is formed around at least a portion of, preferably the entire periphery of, the light-emitting element 36. When configuring the light-emitting element 36, it can be configured via the following layers as needed: a layer formed of an adhesive film, a conductive adhesive film containing conductive particles, an anisotropic conductive adhesive film; or a layer formed of a low melting point metal such as solder (e.g., solder paste). This layer is preferably a conductive adhesive layer 39 containing conductive particles.

[0077] (Light-emitting element)

[0078] In the first to third aspects of the present invention, the light emitting element is not particularly limited, but is preferably a micro-LED. The micro-LED preferably has a maximum length of 3 to 100 μm in a plan view.

[0079] (Black transfer film)

[0080] In addition, as the black transfer film, a black transfer film (not shown) in which a black transfer layer is provided on one side of a light-transmitting substrate as a whole can be used. Preferably, a black transfer film (see Figure 1A , Figure 2A , Figure 3A ). By processing the black transfer layer in the form of a single piece, the black transfer layer can be easily arranged at a specified position of the substrate, and productivity can be improved. In this case, the single piece of the black transfer layer and at least a portion of the surroundings of the position where the light-emitting element is to be arranged on the wiring substrate are preferably arranged on the light-transmitting substrate corresponding to the entire surroundings. In a black transfer film of such a structure, the black transfer layer can be formed to a thickness that can suppress the color mixing of the micro LED.

[0081] From the viewpoint of the operability of the black transfer film, the thickness of the light-transmitting substrate constituting the black transfer film is preferably 0.5 μm or more and 10 μm or less, more preferably 1 μm or more and 5 μm or less. In addition, the lower limit of the thickness of the black transfer layer can be the same as the particle size of the conductive particles, preferably 1.3 times or more of the conductive particle size or 3 μm or more. In addition, the upper limit of the thickness of the black transfer layer is preferably less than 2 times or less than 20 μm of the conductive particle size. In addition, the black transfer film can also be stacked with an adhesive layer or adhesive layer that does not contain conductive particles, and the number of layers and the stacking surface can be appropriately selected according to the object and purpose. In addition, as the insulating resin of the adhesive layer or adhesive layer, the same substance as the thermosetting composition of the black transfer layer can be used. The film thickness can be measured using a known micrometer or a digital thickness gauge. The film thickness can be obtained by, for example, measuring more than 10 places and averaging.

[0082] (Black transfer layer)

[0083] In addition, the black transfer layer of the black transfer film is transferred to other substrates by laser stripping, and a black matrix is ​​formed by heat curing as needed. The black transfer layer of the black transfer film is blackened by preferably containing 5 to 30 parts by mass of black pigments such as carbon black and titanium black relative to 100 parts by mass of an insulating thermosetting composition. Among them, titanium black having an extremely low content of impurity ions and being insulating in itself can be preferably used. The average particle size of these black pigments is 10 to 100 nm. Ideally, the average particle size of the black pigment is smaller than the average particle size of the conductive particles.

[0084] The black transfer layer preferably shows excellent cushioning properties (impact absorption) to show stable adhesion to the substrate. Thus, the occurrence of undesirable conditions such as chip component offset, deformation, damage, and falling off can be suppressed, and the transfer rate of chip components based on laser irradiation can be improved. Such cushioning properties can be evaluated by A-type durometer hardness and / or storage modulus as described later.

[0085] The A-type durometer hardness of the black transfer layer is preferably 20 to 40, more preferably 20 to 35, and particularly preferably 20 to 30. When the A-type durometer hardness is too high, the black transfer layer is too hard, and there is a tendency to easily cause undesirable conditions such as deformation and damage of chip components. When the A-type durometer hardness is too low, the black transfer layer is too soft, and there is a tendency to easily cause undesirable conditions such as displacement of chip components. The A-type durometer hardness of the black transfer layer can be measured by rubber hardness (Japanese Industrial Standard JIS-A hardness) using an A-type durometer in accordance with JIS K6253.

[0086] The storage modulus of the black transfer layer is preferably 60 MPa or less, more preferably 30 MPa or less, and particularly preferably 10 MPa or less. When the storage modulus is too high, there is a tendency that the impact of chip components ejected at high speed due to laser irradiation cannot be absorbed, and the transfer rate of chip components decreases. The storage modulus can be obtained by a dynamic viscoelasticity test using a press-in test device (at a temperature of 30°C and a frequency of 200 Hz, using a flat punch with a diameter of 100 μm, with a target press-in depth of 1 μm, and scanning the frequency range of 1 to 200 Hz).

[0087] In addition, regarding the black matrix formed by thermal curing of the black transfer layer, the storage modulus (30°C) measured in the tensile mode according to JIS K7244 is preferably 100 MPa or more, and more preferably 2000 MPa or more. When the storage modulus at a temperature of 30°C is too low, there is a tendency that good conductivity cannot be obtained and the connection reliability is also reduced. It should be noted that the storage modulus at a temperature of 30°C can be measured according to JIS K7244, in the tensile mode using a viscoelasticity tester (Rheovibron), for example, under the measurement conditions of a frequency of 11 Hz and a heating rate of 3°C / min.

[0088] The thermosetting composition constituting the black transfer layer preferably contains a rubber component, a film-forming resin, a thermosetting resin, a thermosetting agent, and an inorganic filler, and may contain other known additives as needed within a range that does not impair the effects of the invention.

[0089] (Rubber component)

[0090] The rubber component contained in the thermosetting composition is a component for imparting cushioning (impact absorption) to the black transfer layer. It is not particularly limited as long as it is an elastomer with good cushioning. As specific examples, for example, acrylic rubber, silicone rubber, butadiene rubber, polyurethane resin (polyurethane elastomer), etc. are listed. Among them, it is preferably one or more selected from acrylic rubber and silicone rubber. The content of the rubber component is preferably 1 mass part or more and 20 mass parts or less relative to the total of 100 mass parts of the rubber component, film-forming resin, thermosetting resin, thermosetting agent and inorganic filler, and more preferably 2 mass parts or more and 10 mass parts or less.

[0091] (Film-forming resin)

[0092] As film-forming resin, from the viewpoint of film formation, preferably various resins such as phenoxy resin, polyester resin, polyurethane resin, polyester urethane resin, acrylic resin, polyimide resin, butyral resin with a weight average molecular weight of about 10000 or more and 80000 or less can be listed, which can be used alone or in combination of two or more. Among them, from the viewpoints of film formation state, connection reliability, etc., phenoxy resin is preferably used. The content of film-forming resin is preferably 20 mass parts or more and 50 mass parts or less relative to 100 mass parts of the total of rubber component, film-forming resin, thermosetting resin, thermosetting agent and inorganic filler, more preferably 25 mass parts or more and 45 mass parts or less, and particularly preferably 35 mass parts or more and 45 mass parts or less.

[0093] (Thermosetting resin)

[0094] As the thermosetting resin, epoxy compounds, (meth) acrylate compounds, etc. can be listed, and epoxy compounds are particularly preferred. These compounds can also be monomers, oligomers, polymers. The content of the thermosetting resin is preferably 10 mass parts or more and 50 mass parts or less relative to 100 mass parts of the total of the rubber component, the film-forming resin, the thermosetting resin, the thermosetting agent, and the inorganic filler, more preferably 20 mass parts or more and 40 mass parts or less, and particularly preferably 25 mass parts or more and 35 mass parts or less.

[0095] As the epoxy compound that can be used as a thermosetting resin, there is no particular limitation as long as it is an epoxy compound having one or more epoxy groups in the molecule, and for example, it can be a bisphenol A type epoxy resin, a bisphenol F type epoxy resin, etc., or a carbamate-modified epoxy resin. Among them, high-purity bisphenol A type epoxy resin can be preferably used. As a specific example of a high-purity bisphenol A type epoxy resin, for example, the trade name "YL980" manufactured by Mitsubishi Chemical Corporation can be cited. In the case of using the epoxy compound as a thermosetting resin, the content of the epoxy compound is preferably 30 parts by mass or more and 60 parts by mass or less relative to a total of 100 parts by mass of the rubber component, the film-forming resin, the thermosetting resin, the thermosetting agent, and the inorganic filler, more preferably 35 parts by mass or more and 55 parts by mass or less, and particularly preferably 35 parts by mass or more and 45 parts by mass or less.

[0096] (Thermosetting agent)

[0097] The thermosetting agent is selected according to the thermosetting resin. For example, when the thermosetting resin is an epoxy compound, a thermal anionic polymerization initiator or a thermal cationic polymerization initiator can be preferably selected. A thermal cationic polymerization initiator that can suppress the curing reaction caused by laser and cure quickly by heat can be more preferably selected. The content of the thermosetting agent can be determined according to the type of the thermosetting agent, the type of the thermosetting resin, etc. The content of the thermosetting agent is preferably 1 mass part or more and 10 mass parts or less, more preferably 2 mass parts or more and 8 mass parts or less, and particularly preferably 3 mass parts or more and 6 mass parts or less relative to 100 mass parts of the total of the rubber component, the film-forming resin, the thermosetting resin, the thermosetting agent, and the inorganic filler.

[0098] It should be noted that as a thermal cationic polymerization initiator that can be preferably applied to epoxy compounds, it is a substance that generates an acid that can cause a cationic polymerization type compound to undergo cationic polymerization by heat, and known iodonium salts, sulfonium salts, phosphonium salts, ferrocenes, etc. can be used. Among them, aromatic sulfonium salts that show good latency to temperature can be preferably used. As a specific example of an aromatic sulfonium salt-based polymerization initiator, for example, the trade name "San-Aid SI-60L" manufactured by Sanshin Chemical Industry Co., Ltd. can be cited. The content of such a thermal cationic polymerization initiator is preferably 1 mass part or more and 15 mass parts or less relative to a total of 100 mass parts of rubber components, film-forming resins, thermosetting resins, thermosetting agents, and inorganic fillers, more preferably 1 mass part or more and 10 mass parts or less, and particularly preferably 3 mass parts or more and 8 mass parts or less.

[0099] (Inorganic filler)

[0100] The inorganic filler in the thermosetting composition is used for the purpose of adjusting the A-type durometer hardness of the black transfer layer, the storage modulus at a frequency of 200 Hz, and the storage modulus after curing. In addition to the black pigment, silica, talc, titanium oxide, calcium carbonate, magnesium oxide, silane coupling agent, diluent monomer, filler, softener, colorant, flame retardant, thixotropic agent, etc. can be used. The inorganic filler can be used alone or in combination of two or more.

[0101] The content of the inorganic filler is preferably 1 part by mass or more and 20 parts by mass or less, more preferably 5 parts by mass or more and 15 parts by mass or less, and particularly preferably 8 parts by mass or more and 12 parts by mass or less, relative to 100 parts by mass of the total of the rubber component, the film-forming resin, the thermosetting resin, the thermosetting agent, and the inorganic filler. In particular, when the content of the rubber component is 2 parts by mass or more and 10 parts by mass or less relative to 100 parts by mass of the total of the rubber component, the film-forming resin, the thermosetting resin, the thermosetting agent, and the inorganic filler, by setting the content of the inorganic filler to 8 parts by mass or more and 12 parts by mass or less, the desired A-type durometer hardness, the storage modulus at a frequency of 200 Hz, and the storage modulus after curing can be easily adjusted.

[0102] (Conductive particles)

[0103] In addition, the black transfer layer may further contain conductive particles. By containing conductive particles, the black transfer layer and the black matrix derived therefrom can function as a conductive layer or an anisotropic conductive layer. As conductive particles, conductive particles used in known conductive films and anisotropic conductive films can be appropriately selected and used. For example, metal particles such as nickel, copper, silver, gold, palladium, solder, etc.; metal-coated resin particles formed by coating the surfaces of resin particles such as polyamide and polybenzoguanamine with metals such as nickel and gold, etc. As a result, conduction can be achieved even when a connection portion such as a solder bump is not provided on the chip component. For example, in the first embodiment of the present invention, the light-emitting element can be electrically connected to the wiring substrate at the same time when the black matrix is ​​formed.

[0104] The average particle size of the conductive particles is usually not less than 1 μm and not more than 50 μm. From the viewpoint of the capture efficiency of the conductive particles in the connection structure, it is preferably not less than 1 μm and not more than 20 μm, and more preferably not less than 1.5 μm and not more than 15 μm. In order to be applied to electrodes of microscopic size, it can also be set to not less than 1.5 μm and less than 2.5 μm. It should be noted that the average particle size of the conductive particles can be measured by an image-type particle size distribution meter (for example, FPIA-3000, manufactured by Malvern Panalytical). In addition, the particle surface density in the black transfer layer of the conductive particles can be determined based on the electrode area of ​​the chip component, etc. For example, the lower limit of the particle surface density can preferably be set to 500 particles / mm 2 The upper limit can be preferably set to 200,000 pieces / mm 2 Below, more preferably set to 150000 pieces / mm 2 Below, particularly preferably set to 120000 pieces / mm 2 It should be noted that the size and number density of the conductive particles can be adjusted so as not to impair the effect of the black pigment.

[0105] In addition, the conductive particles are preferably configured independently of each other under the film surface field of the black transfer layer. In this case, it is preferred that more than 95% of the number of conductive particles is independent. Furthermore, the conductive particles are preferably not only configured independently of each other, but also arranged regularly. It is particularly preferred that the particles in each direction orthogonal to each other under the film surface field are periodically repeated. For example, lattice arrangements such as hexagonal lattices, rectangular lattices, orthorhombic lattices, square lattices, and other rectangular lattices can be listed. In addition, it is also possible to arrange the particle columns in which the conductive particles are arranged in a straight line at a specified interval in parallel at a specified interval. In this way, by arranging the conductive particles regularly under the film surface field, the surface density of the conductive particles can be made uniform, and the transfer rate of the chip components based on laser irradiation can be further improved.

[0106] (Ultraviolet absorbing resin)

[0107] The thermosetting composition constituting the black transfer layer may contain an ultraviolet absorbing resin (resins having a benzene skeleton or a naphthalene skeleton, such as aromatic epoxy resin, phenoxy resin, aromatic polyimide resin, aromatic polysulfone resin, etc.) to improve laser stripping properties. These components may also be repeated with rubber components, film-forming resins, etc.

[0108] <Fourth aspect of the present invention>

[0109] The fourth scheme of the present invention is a preferred scheme of the black transfer film used in the manufacturing method of the first to third schemes. Specifically, the black transfer film used to form a black matrix using a laser lift-off method has a translucent substrate such as a polyethylene terephthalate film and a black transfer layer formed on a single side of the translucent substrate. The black transfer layer contains a black pigment and a thermosetting composition as described above. The visible light transmittance of the black transfer layer according to JIS K7375 is less than 20%, preferably less than 10%, and the viscosity of the black transfer layer according to JIS Z0237 is greater than 0.1 MPa to ensure monolithic transferability. In addition, the cushioning property of the black transfer layer is as described above. It should be noted that the black transfer layer is preferably provided in a monolithic manner on the translucent substrate corresponding to the black matrix to be formed. In addition, the black transfer layer preferably contains conductive particles to impart conductivity or anisotropic conductivity to the black transfer film.

[0110] Example

[0111] Hereinafter, the present invention will be specifically described by way of examples.

[0112] <Making black transfer film>

[0113] The transfer layer forming compositions (i), (ii), (iii), (iv) and (v) in Table 1 were mixed respectively, and the obtained mixture was applied to a light-transmitting substrate, and dried at 60° C. for 3 min, thereby respectively obtaining black transfer films (i), (ii), (iii) and (iv) of the present invention having a black transfer layer with a thickness of 6 μm. It should be noted that a white transfer film (v) having a white transfer layer was obtained from the transfer layer forming composition (v).

[0114] Then, through paragraphs 0111 to 0112 of Japanese Patent No. 6187665 and Figure 1A The conductive particles described in the invention are arranged in a regular pattern so that the conductive particles (Micropearl AU, Sekisui Chemical Co., Ltd.) have a particle density of 58,000 particles / mm. 2After being regularly arranged in a manner, the conductive particles are transferred to a black transfer film or a white transfer film, thereby imparting anisotropic conductivity to the black transfer films (i), (ii), (iii) and the white transfer film (v). The black transfer film (iv) is an example in which conductive particles are not used.

[0115] [Table 1]

[0116] (parts by mass)

[0117]

[0118] From the perspective of making a black matrix, the following evaluation tests were performed on the obtained black transfer film and white transfer film according to the material composition and the temporary fixing method of the film, and the evaluation results are shown in Table 2. Specifically, Examples 1, 2 and 3 are examples of using black transfer films (i), (ii) and (iii) respectively and transferring the black transfer layer monolithically by laser stripping to make a black matrix. Comparative Example 1 is an example of using a white transfer film (v) and transferring the white transfer layer monolithically by laser stripping to make a white matrix. Comparative Examples 2 and 3 are examples of using black transfer films (i) and (iv) and laminating the entire surface of the black transfer layer by laser stripping.

[0119] <Film viscosity evaluation test>

[0120] The film viscosity of the black transfer films of Examples 1 to 3 and Comparative Example 1 was measured using a viscosity tester (TAC-II, RHESCA Corporation). The viscosity test was conducted with a probe diameter of 5.1 mm and an initial load of 40 gf / cm 2 The test was carried out under the conditions of 1 second pressurization time and 2 mm / sec test speed.

[0121] (Film viscosity evaluation)

[0122] Judgment: Benchmark

[0123] A: Above 0.4Mpa.

[0124] B: 0.2 MPa or more and less than 0.4 MPa.

[0125] C: 0.1Mpa or more and less than 0.2Mpa.

[0126] D (unqualified): less than 0.1Mpa.

[0127] <Film light-shielding property evaluation test>

[0128] In Examples 1 to 3 and Comparative Examples 2 and 3, the black transfer film and in Comparative Example 1, the white transfer film were bonded to a 5×5 cm, 0.5 mm thick glass substrate, and the transmittance was measured using a transmittance measuring device (USPM-CS01, Olympus Corporation) to evaluate the light shielding properties of the film. The visible light transmittance was calculated from the average transmittance at 400 to 700 nm.

[0129] (Evaluation of film light-shielding properties)

[0130] Judgment: Benchmark

[0131] A: Less than 10%.

[0132] B: 10% or more and less than 15%.

[0133] C: 15% or more and less than 20%.

[0134] D (unqualified): more than 20%.

[0135] <Single film landing performance evaluation test>

[0136] In Examples 1 to 3, a 30×40 μm single piece of the black transfer layer of the black transfer film and in Comparative Example 1, a 30×40 μm single piece of the white transfer layer of the white transfer film were transferred 1000 times onto glass blanks separated by 100 μm using a laser peeling device (MT-30C200) under the following conditions. The landing rate was calculated and the landing properties of the single film were evaluated.

[0137] Laser: Excimer laser with an oscillation wavelength of 248 nm.

[0138] Laser pulse energy: 600J.

[0139] Fluence: 150J / cm 2 .

[0140] Pulse width (irradiation time): 30,000 picoseconds.

[0141] Pulse frequency: 0.01kHz.

[0142] Number of irradiation pulses: one pulse for each small piece of transfer layer.

[0143] The pulse energy of the laser beam that is irradiated onto the interface between the black transfer layer and the light-transmitting substrate and forms an image is 0.001 to 2 J.

[0144] Fluence: 0.001~2J / cm 2 .

[0145] Pulse width (irradiation time): 0.01~1×10 9 Picoseconds.

[0146] Pulse frequency: 0.1~10000Hz.

[0147] Irradiation pulse number: 1 to 30,000,000 pulses.

[0148] Mask used: The following pattern is used: a pattern in which windows of a predetermined size are arranged at a predetermined pitch so that the projection at the interface between the black transfer layer and the glass blank becomes an arrangement of laser light with a pitch of 120 μm in length and a pitch of 160 μm in width and a length of 30 μm and a width of 40 μm.

[0149] (Evaluation of single film landing properties)

[0150] Judgment: Benchmark

[0151] A: More than 99.9%.

[0152] B: 99.0% or more and less than 99.9%.

[0153] C: 90.0% or more and less than 99.0%.

[0154] D (failure): less than 90.0%.

[0155] <Black area occupancy rate (%)>

[0156] In the case of the whole-surface laminated film of Comparative Examples 2 and 3, a sample in which the film was laminated to the entire surface of the glass substrate was prepared. In the case of each single film of Examples 1 to 3 and Comparative Example 1, a sample in which a single film was placed on the glass substrate at a spacing of 400 μm in length and 300 μm in width was prepared. The single film or laminated film that was placed on the glass substrate was confirmed using a metal microscope. The measurement area was observed within a range of 1 mm×1 mm, and a black area was confirmed.

[0157] <On-resistance>

[0158] The LED chip for evaluation was placed on an adherend with a black transfer film temporarily fixed thereon, and crimped at 200°C-10Mpa-30sec to obtain a mounted body. Two pairs of 10×10μm electrodes were set on the LED chip for evaluation, and the conduction resistance was measured through the conduction wiring on the substrate side. A total of 30 locations were measured to confirm the average conduction resistance.

[0159] (On-resistance evaluation)

[0160] Judgment: Benchmark

[0161] A: Less than 50Ω.

[0162] B: greater than 50Ω and less than 100Ω.

[0163] C: greater than 100Ω and less than 200Ω.

[0164] D (failure): greater than 200Ω.

[0165] [Table 2]

[0166]

[0167] <Results review>

[0168] Film viscosity affects the landing properties of the single film, but even in Example 3, which has the lowest viscosity, there is no practical problem with the black transfer film (iii) used. In addition, the black transfer films containing carbon black and titanium black used in Examples 1 to 3 and Comparative Examples 2 and 3 show good light shielding properties.

[0169] In addition, in Examples 1 to 3, a black anisotropic conductive transfer film is transferred monolithically to obtain a mounting body that takes into account both on-resistance and light-shielding properties as black matrix characteristics. Moreover, a black matrix can be selectively formed only in the required position. As a result, advantages such as good alignment properties for transparent displays and LED chips can be obtained.

[0170] When the single-sheet transfer was performed in the same manner as in Example 1 using a black transfer film (iv) that did not contain conductive particles and did not exhibit anisotropic conductive properties, the on-resistance tended to be high, but the other evaluation items were substantially the same as those in Example 1.

[0171] On the other hand, in the case of Comparative Example 1, a white transfer film was used, which was not suitable for preparing a black matrix. In the cases of Comparative Examples 2 and 3, a black transfer film was laminated on the entire surface, so the black transfer layer needed to be further patterned to prepare a black matrix.

[0172] In the above embodiments 1-3, a black transfer film using conductive particles is used. However, the bump condition specifications of the micro LED are changed to allow sufficient conduction without conductive particles. Even if the black transfer film does not use conductive particles, as long as it meets the evaluation requirements other than the conductive performance, it can be expected to become a practical black transfer film.

[0173] Industrial Applicability

[0174] In order to prevent color mixing of micro-LEDs, a black matrix needs to be formed between LEDs. However, unlike LCDs and OLEDs, no color filter is used, so a black matrix cannot be set in the color filter layer. In the present invention, a black matrix can be easily formed by laser lift-off technology. The black transfer film is a thermosetting film and can also serve as a conductive film for LEDs. According to this technology, the process of connecting LEDs and forming a black matrix can be shortened / cost reduced.

[0175] Description of Reference Numerals

[0176] 1, 21, 31: wiring; 2, 22, 32: wiring substrate; 3, 23, 33: light-transmitting substrate; 4, 24, 34: black transfer layer; 5, 25, 35: black transfer film; 6, 26, 36: light-emitting element; 6a, 26a, 36a: electrodes of the light-emitting element; 7: welding head; 8, 28, 38: black matrix; 29, 39: conductive adhesive layer; L: laser.

Claims

1. A method for manufacturing a light-emitting device, the light-emitting device having a black matrix at least partially around a light-emitting element arranged on a wiring substrate, the method comprising the following steps a, b and c: Step a: a step of placing a black transfer film having a black transfer layer formed on one side of a light-transmitting substrate opposite to a wiring substrate before arranging a light-emitting element from the black transfer layer side; Step b: a step of irradiating a black transfer film with laser light from the light-transmitting substrate side to transfer the single sheet of the black transfer layer to a position of the wiring substrate where the light-emitting element is to be arranged; and Step c: a step of arranging and mounting a light emitting element on a single piece of a black transfer layer transferred to a wiring substrate, thereby deforming the black transfer layer to form a black matrix at least partially around the light emitting element and connecting the light emitting element to the wiring substrate.

2. A method for manufacturing a light-emitting device, the light-emitting device having a black matrix around at least a portion of a light-emitting element disposed on a wiring substrate, the method comprising the following steps A1a and A1b: Step A1a: a step of placing a black transfer film having a black transfer layer formed on one surface of a light-transmitting base material opposite to a wiring substrate on which a light-emitting element is arranged from the black transfer layer side; and Step A1b: a step of irradiating a black transfer film with laser light from the light-transmitting substrate side to transfer a single piece of the black transfer layer to at least a portion of the periphery of the light-emitting element of the wiring board to form a black matrix.

3. A method for manufacturing a light-emitting device, the light-emitting device having a black matrix around at least a portion of a light-emitting element disposed on a wiring substrate, the method comprising the following steps A2a, A2b, and B: Step A2a: a step of placing a black transfer film having a black transfer layer formed on one surface of a light-transmitting substrate opposite to a wiring substrate before arranging light-emitting elements from the black transfer layer side; Step A2b: a step of irradiating a black transfer film with laser light from the light-transmitting substrate side to transfer a single piece of the black transfer layer to at least a portion of the wiring substrate around the position where the light-emitting element is to be arranged, thereby forming a black matrix; and Step B: a step of arranging light-emitting elements between black matrices transferred to a wiring substrate.

4. The production method according to any one of claims 1 to 3, wherein The light emitting element is a micro LED.

5. The production method according to any one of claims 1 to 3, wherein In the black transfer film, a black transfer layer is provided entirely on one surface of a light-transmitting substrate.

6. The production method according to any one of claims 1 to 3, wherein In the black transfer film, a single piece of the black transfer layer is provided on the light-transmitting base material corresponding to at least a portion of the periphery of the position where the light-emitting element is to be arranged on the wiring substrate.

7. The production method according to any one of claims 1 to 3, wherein The black transfer layer contains conductive particles, and the black transfer layer exhibits conductivity.

8. The manufacturing method according to claim 7, wherein: The black transfer layer exhibits anisotropic conductivity.

9. A black transfer film, which is used to form a black matrix using a laser lift-off method, wherein: The black transfer film comprises a light-transmitting substrate and a black transfer layer formed on one side of the light-transmitting substrate. The black transfer layer contains a black pigment and a thermosetting composition. The visible light transmittance of the black transfer layer according to JIS K7375 is less than 20%, and the adhesive force according to JIS Z0237 is 0.1 MPa or more.

10. The black transfer film according to claim 9, wherein: The type A durometer hardness of the black transfer layer is 20 or more and 40 or less.

11. The black transfer film according to claim 9, wherein: The storage modulus of the black transfer layer obtained by the dynamic viscoelasticity test is less than 60 MPa. The conditions of the dynamic viscoelasticity test are as follows: at a temperature of 30°C and a frequency of 200 Hz, a flat punch with a diameter of 100 μm is used, the target indentation depth is 1 μm, and the frequency range of 1 to 200 Hz is scanned.

12. The black transfer film according to claim 9, wherein: The black transfer layer is provided on the light-transmitting substrate in a single sheet corresponding to the black matrix to be formed.

13. The black transfer film according to any one of claims 9 to 12, wherein The black transfer layer contains conductive particles and exhibits conductivity.

14. The black transfer film according to claim 13, wherein: The black transfer layer exhibits anisotropic conductivity.

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