Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G75/00—Macromolecular compounds obtained by reactions forming a linkage containing sulfur with or without nitrogen, oxygen, or carbon in the main chain of the macromolecule
  • C08G75/02—Polythioethers
  • C08G75/04—Polythioethers from mercapto compounds or metallic derivatives thereof
  • C08G75/045—Polythioethers from mercapto compounds or metallic derivatives thereof from mercapto compounds and unsaturated compounds
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10H—INORGANIC LIGHT-EMITTING SEMICONDUCTOR DEVICES HAVING POTENTIAL BARRIERS
  • H10H20/00—Individual inorganic light-emitting semiconductor devices having potential barriers, e.g. light-emitting diodes [LED]
  • H10H20/80—Constructional details
  • H10H20/85—Packages

Definitions

• the present invention relates to a buffer composition, and more specifically, to a buffer composition that functions as a catch material for micro LED display elements.
• LCDs liquid crystal display elements
• OLED organic light-emitting diode display elements
• LCDs have already been fully mass-produced, and are inexpensive and can be made large.
• OLEDs are also excellent in flexibility, but there is an issue that their lifespan is shortened when the brightness of the display element is increased.
• micro LED display elements have been developed as a display element that can solve these shortcomings, in which inorganic light-emitting diodes are arranged on each pixel of an array substrate.
• Micro LED display elements use inorganic light-emitting diodes of micrometer size as the light source, so they can achieve higher brightness than LCDs and OLEDs, have high color purity, and have a long lifespan.
• LEDs are arranged for each pixel, each pixel can be made independent, and they are also excellent in flexibility.
• the LED elements that are the light source are supplied as small pieces by epitaxially growing a semiconductor layer on a sapphire substrate, forming electrodes, and then dicing.
• Micro LED display elements require a large number of tiny LED element pieces manufactured in this way to be arranged on an array substrate with high precision.
• the conventional pick-and-place method of arranging LED elements on an array substrate, in which each LED element is installed one by one, requires an enormous amount of takt time, so there has been active research into a mass transfer method that transfers a large number of LED elements onto an array substrate at once. In particular, for larger displays and other applications, high speed is required in addition to high precision, and the mass transfer method using the laser lift-off method (LLO method) is seen as promising.
• LLO method laser lift-off method
• the simplest process using the LLO method is to directly transfer the LED elements from the support substrate onto the array substrate, as proposed in Patent Document 1. To achieve this direct transfer, it is necessary to place the LED elements, which have been repelled by the laser, on the array substrate without any misalignment, and to achieve this, it is necessary to first provide a highly adhesive buffer film on the array substrate as a catch material.
• the electrode height of a micro LED element is no more than a few tens of micrometers.
• the LED element transferred to the substrate is then bonded to the substrate electrode, so the buffer film required for the above-mentioned laser mass transfer is also required to be no more than a few tens of micrometers thick.
• many shock-absorbing sheets that contain a foam layer known to be an excellent buffer material, tend to be several hundred micrometers thick (Patent Document 2).
• Patent Document 3 proposes a multi-step process in which an uncured thermosetting adhesive resin layer is provided on the bump electrode side of the LED.
• the present invention was developed in consideration of the above circumstances, and is an invention related to a transfer process for micro LED elements using the LLO method, and aims to provide a thin buffer film suitable for micro LEDs that functions as a catch material.
• the present invention relates to the following:
• the cured film according to 5 having a film thickness of 10 ⁇ m or less. 7.
• the cured film according to 6 having a restitution coefficient of 0.5 or less.
• a patterned cured film obtained by exposing and developing the composition according to any one of 1 to 4.
• An LED display element having the cured film according to any one of 5 to 8 as a catch material.
• composition of the present invention contains the following components (A), (B), and (C), and has a glass transition temperature (Tg) after curing of less than 0°C.
• Component (A) an aliphatic compound having a urethane structure and two or more crosslinkable functional groups
• the flexibility of the urethane structure contained in the compound of the present invention plays a role in absorbing the impact of the micro-LED chip being thrown away.
• the adhesiveness of the film which is due to its low Tg, allows the micro-LED held by the film to remain in the desired position without shifting out of place.
• Component (A) is an aliphatic compound having a urethane structure and two or more crosslinkable functional groups, and is characterized in that a cured film of the polymer has a glass transition temperature (Tg) of less than 0°C.
• the aliphatic compound constituting component (A) of the present invention preferably has two or more crosslinkable functional groups.
• the crosslinking sites if there are too many crosslinking sites, the flexibility of the cured film is impaired, resulting in a decrease in catching performance, so it is more preferable that the crosslinking sites have two functional groups.
• the crosslinkable functional group refers to a functional group that can form a chemical bond with other molecules.
• Specific examples include vinyl groups, acrylic groups, methacrylic groups, cyclic ether groups, carboxyl groups, and maleimide groups. From the viewpoint of reactivity, however, vinyl groups, acrylic groups, methacrylic groups, and epoxy groups are preferred, and acrylic groups and methacrylic groups are more preferred.
• Component (A) examples include aliphatic urethane acrylates such as EBECRYL230, EBECRYL270, EBECRYL4491, EBECRYL8411, and EBECRYL8413 (trade names manufactured by Daicel-Allnex Co., Ltd.), SU514, SU530, SU570, and SU5656 (trade names manufactured by Okajima Co., Ltd.), GENOMER4215, and GENOMER4269/M22 (trade names manufactured by RAHN AG), and aliphatic ester-based urethane acrylates.
• aliphatic urethane acrylates such as EBECRYL230, EBECRYL270, EBECRYL4491, EBECRYL8411, and EBECRYL8413 (trade names manufactured by Daicel-Allnex Co., Ltd.), SU514, SU530, SU570, and SU5656 (trade names manufactured by Okajima Co., Ltd.
• urethane acrylates examples include KAYARAD UX-3204 (product name, Nippon Kayaku Co., Ltd.), UN-350, UN-1255, UN-7700 (product name, Negami Chemical Industries Co., Ltd.), and UF-3003 (product name, Kyoeisha Chemical Co., Ltd.), and examples of such aliphatic ether urethane acrylates include KAYARAD UXF-4002 (product name, Nippon Kayaku Co., Ltd.), UN-6200, UN-6304 (product name, Negami Chemical Industries Co., Ltd.), UA-1138P, and UA-3573AB (product name, Shin-Nakamura Chemical Co., Ltd.), etc.
• the (B) component is a crosslinking agent that is contained for the purpose of assisting the crosslinking of the (A) component to form a cured film, and the type is not particularly limited. In order not to impair the catching performance expressed by the (A) component, it is preferable that the (B) component contributes to crosslinking promotion in a small amount. Examples of compounds that contribute to crosslinking promotion in a small amount include polyfunctional thiols and organic peroxides such as peroxyketals that also function as cationic initiators.
• component (B) is preferably 0.1 to 10 parts by mass, and more preferably 0.5 to 5 parts by mass, based on 100 parts by mass of component (A).
• Component (C) In order to accelerate the crosslinking reaction between components (A) and (B) by heat or light, a polymerization initiator can be used as component (C) as necessary.
• Radical initiators include thermal radical initiators and photoradical initiators.
• Thermal radical initiators include, for example, organic peroxides such as peroxyketals and azo compounds such as 2,2'-azobisbutyronitrile.
• Photoradical initiators generate radicals when irradiated with ultraviolet light or an electron beam, and examples of such initiators include oxime ester compounds and benzoin compounds.
• Cationic initiators generate cations when irradiated with heat or light energy, and examples of such initiators include sulfonium salts and iodonium salts.
• component (C) When component (C) is used, its content is usually 0.1 to 10 parts by mass, preferably 0.5 to 5 parts by mass, based on 100 parts by mass of component (A).
• the solvent used in the present invention dissolves the components (A) and (B) and also dissolves the components described below that are added as desired. As long as the solvent has such dissolving ability, there are no particular limitations on the type or structure of the solvent.
• solvents examples include ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, methyl cellosolve acetate, ethyl cellosolve acetate, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, propylene glycol, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, propylene glycol propyl ether acetate, toluene, xylene, methyl ethyl ketone, cyclopentanone, cyclohexanone, 2-butanone, 3-methyl-2-pentanone, ... methacrylate crosslinker, ...
• solvents may be used alone or in combination of two or more.
• solvents propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, 2-heptanone, propylene glycol propyl ether, propylene glycol propyl ether acetate, ethyl lactate, butyl lactate, etc. are preferred from the viewpoint of good film-forming properties and high safety.
• solvents are generally used as solvents for photoresist materials.
• composition of the present invention may further contain a silane coupling agent for the purpose of improving adhesion to a substrate.
• silane coupling agent examples include vinyltrimethoxysilane, vinyltriethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-glycidylpropyltrimethoxysilane, 3-glycidylpropyltriethoxysilane, 2-(3,4-epoxycyclohexyl)propyltrimethoxysilane, 2-(3,4-epoxycyclohexyl)propyltriethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane, 2-(3,4-epoxycyclohexyl)methyltrimethoxysilane, 2-(3,4-epoxycyclohexyl)methyltriethoxysilane, 3-aminopropyltrime
• silane coupling agent When a silane coupling agent is used, its content is usually 0.5 to 20 parts by mass, and preferably 2 to 10 parts by mass, based on 100 parts by mass of component (A).
• the composition of the present invention can be applied onto a semiconductor substrate (e.g., a silicon/silicon dioxide coated substrate, a silicon nitride substrate, a substrate coated with a metal such as aluminum, molybdenum, chromium, etc., a glass substrate, a quartz substrate, an ITO substrate, etc.) by spin coating, flow coating, roll coating, slit coating, spin coating followed by slit coating, inkjet coating, etc., and then pre-dried on a hot plate or in an oven, etc., to form a coating film. Then, the coating film is subjected to a heat treatment or irradiation with light such as ultraviolet light to form a cured film.
• a semiconductor substrate e.g., a silicon/silicon dioxide coated substrate, a silicon nitride substrate, a substrate coated with a metal such as aluminum, molybdenum, chromium, etc., a glass substrate, a quartz substrate, an ITO substrate, etc.
• the conditions for preliminary drying are a heating temperature and a heating time appropriately selected from the ranges of 70 to 130°C and 0.3 to 10 minutes.
• the heating temperature and heating time are preferably 80°C to 120°C and 0.5 to 5 minutes.
• the thickness of the coating film formed from the composition of the present invention is, for example, 0.1 to 30 ⁇ m, or, for example, 1 to 20 ⁇ m, or, for example, 5 to 15 ⁇ m.
• the conditions are a heating temperature and a heating time appropriately selected from the ranges of 120 to 180°C and 0.3 to 10 minutes.
• the heating temperature and heating time are preferably 140°C to 160°C and 0.5 to 5 minutes.
• the atmosphere for the heat treatment may be appropriately selected from air or an inert gas, but in order to more effectively express the function of the thermal radical generator, heat treatment in an inert gas such as nitrogen is preferred.
• the conditions are, for example, ultraviolet light having a wavelength of 365 nm and a light intensity of 100 to 5,000 mJ/ cm2 .
• a mask having a predetermined pattern is attached to the coating film obtained above, and the film is irradiated with light such as ultraviolet light and developed with an alkaline developer, whereby the exposed areas are washed out and a sharp pattern is obtained at the end faces.
• alkaline developers examples include aqueous solutions of alkali metal hydroxides such as potassium carbonate, sodium carbonate, potassium hydroxide, and sodium hydroxide; aqueous solutions of quaternary ammonium hydroxides such as tetramethylammonium hydroxide, tetraethylammonium hydroxide, and choline; and aqueous solutions of amines such as ethanolamine, propylamine, and ethylenediamine. Furthermore, surfactants and the like can also be added to these developers.
• alkali metal hydroxides such as potassium carbonate, sodium carbonate, potassium hydroxide, and sodium hydroxide
• quaternary ammonium hydroxides such as tetramethylammonium hydroxide, tetraethylammonium hydroxide, and choline
• amines such as ethanolamine, propylamine, and ethylenediamine.
• surfactants and the like can also be added to these developers.
• an aqueous solution of 0.1 to 2.38 mass % tetraethylammonium hydroxide is generally used as a developer for photoresists, and the photosensitive adhesive composition of the present invention can be developed well using this alkaline developer without causing problems such as swelling.
• the development method can be any of the following: puddle method, dipping method, and rocking immersion method.
• the development time is usually 15 to 180 seconds.
• the positive photosensitive adhesive film is washed with running water for, for example, 20 to 120 seconds, and then air-dried with compressed air or compressed nitrogen or by spinning to remove water from the substrate and obtain a patterned film.
• Tg Glass Transition Temperature
• Examples 1-2 to 1-5 and Comparative Examples 1-1 to 1--7 Compositions V2 to V5 and RV1 to RV7 having the compositions shown in Table 1 were prepared in the same manner as in Example 1-1, except that the resin components were changed to those shown in Table 1. However, composition RV7 had poor compatibility, and a homogeneous solution could not be obtained.
• composition V6 having the composition shown in Table 1.
• composition V8 having the composition shown in Table 1.
• Example 2-1 Preparation and evaluation of cured film>
• Composition V1 prepared in Example 1-1 was applied onto a 3 cm x 4 cm ITO substrate using a spin coater, and then the solvent was evaporated on a hot plate at a temperature of 100 ° C. for 120 seconds to form a coating film with a thickness of 10 ⁇ m.
• This coating film was irradiated with 3,000 mJ / cm 2 of ultraviolet light with a wavelength of 365 nm to prepare a cured film.
• the Tg of the obtained cured film was less than -20 ° C.
• the cushioning property of this cured film was evaluated by a finger touch method.
• the surface of the cured film was pressed with a finger at room temperature to form a press mark, and the press mark disappeared within 30 minutes, and the cushioning property was evaluated as "good”.
• the press mark continued to remain after 30 minutes, and the film curing property was insufficient, and the film did not return to its original state, so the cushioning property was evaluated as "poor 1".
• the press mark was not formed at all, and the film was difficult to elastically deform due to curing, so the cushioning property was evaluated as "poor 2".
• the results are shown in Table 2.
• the deformation of the film such that the impression formed by pressing with a finger returns to its original state is defined as elastic deformation.
• Example 2-2 to 2-6 and Comparative Examples 2-1 to 2-6) The Tg, cushioning properties, and resilience coefficient of the buffer compositions V2 to V6 and RV1 to RV6 prepared in Examples 1-2 to 1-6 and Comparative Examples 1-1 to 1-6 were evaluated in the same manner as in Example 2-1. The results are shown in Table 2.
• Example 2--7 The buffer composition V7 prepared in Example 1-7 was applied to a 3 cm x 4 cm ITO substrate using a spin coater, and then the solvent was evaporated on a hot plate at 150°C for 60 seconds under a nitrogen atmosphere to form a cured film with a thickness of 10 ⁇ m. The obtained cured film was evaluated for Tg, buffer properties, and restitution coefficient in the same manner as in Example 2-1. The results are shown in Table 2.
• Example 2-8 Composition V8 prepared in Example 1-8 was applied onto a 3 cm x 4 cm ITO substrate using a spin coater, and then the solvent was evaporated on a hot plate at a temperature of 100°C for 120 seconds to form a coating film with a thickness of 10 ⁇ m.
• This coating film was irradiated with 1,000 mJ/ cm2 of ultraviolet light with a wavelength of 365 nm to produce a cured film.
• the obtained cured film was evaluated for Tg, cushioning properties, and restitution coefficient in the same manner as in Example 2-1. The results are shown in Table 2.
• the cured film made from the composition of the example using a bifunctional aliphatic urethane acrylate resin had a Tg of less than 0°C, exhibited excellent curing and adhesion, and showed a low resilience coefficient of less than 0.5.
• a resin with a cured film Tg of 0°C or higher was used (Comparative Example 2-1 and Comparative Examples 2-3 to 2-6)
• the elastic deformation of the film was insufficient, and as a result, a high resilience coefficient of 0.7 or more was shown.
• a silicone diacrylate resin was used (Comparative Example 2-2)
• the curing was insufficient and the resilience coefficient could not be evaluated.
• Example 3-1 ⁇ Patterning evaluation>
• the buffer composition V6 prepared in Example 1-6 was applied onto a 5 cm x 5 cm glass substrate using a spin coater, and then the solvent was evaporated on a hot plate at a temperature of 100 ° C. for 120 seconds to form a coating film with a thickness of 1 ⁇ m.
• This coating film was irradiated through a mask with ultraviolet light having a light intensity of 3,000 mJ / cm 2 at a wavelength of 365 nm.
• the coating film was developed by immersing it in a 2.38 mass % tetramethylammonium hydroxide (hereinafter referred to as TMAH) aqueous solution for 60 seconds, and then washed with running ultrapure water for 30 seconds to produce a pattern film.
• TMAH tetramethylammonium hydroxide

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• 2024
  • 2024-03-28 JP JP2025511133A patent/JPWO2024204519A1/ja active Pending
  • 2024-03-28 WO PCT/JP2024/012605 patent/WO2024204519A1/ja not_active Ceased
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