KR-20260062101-A - PHOTODEGRADATION BASED NON-CONDUCTIVE ADHESIVE FOR MICRO-LED DISPLAY AND METHOD OF MANUFACTURING SAME

Abstract

A photodegradation-based nonconductive adhesive for micro LED displays and a method for manufacturing the same are disclosed. The present invention relates to an adhesive comprising a bisphenol-based epoxy resin having a plurality of epoxy groups; an ester-based epoxy; and an imidazole-based curing agent. Since it has bifunctionality so that it is introduced into the composition of a nonconductive film (NCF) to maintain strong adhesion and fixation characteristics after connection/curing, it is cross-linked to realize stable NCF characteristics. Subsequently, if device defects or connection failures occur, the adhesive strength can be reduced by photodegradation caused by local UV irradiation, thereby ultimately allowing the defective chip to be easily removed.

Inventors

• 신승한
• 권기옥
• 김지호
• 마이뜨완

Assignees

• 한국생산기술연구원

Dates

Publication Date

20260507

Application Date

20241016

Claims (19)

1. Bisphenol-based epoxy resin having multiple epoxy groups; Ester-based epoxy represented by structural formula 1; and Imidazole-based curing agent; adhesive containing: [Structural Formula 1] In structural formula 1, R1 is a hydrogen atom or a C1 to C3 alkyl group, and m is independently an integer from 0 to 3, and n is an integer from 0 to 3, each independently, and q is 0 or 1.
2. In paragraph 1, In structural formula 1, R1 is a hydrogen atom, and m is independently an integer from 1 to 3, and n is an integer from 1 to 3, each independently, and An adhesive characterized in that q is 0.
3. In paragraph 1, In structural formula 1, R1 is a hydrogen atom, and m is 1 and n is 1, and An adhesive characterized in that q is 0.
4. In paragraph 1, An adhesive characterized in that the above-mentioned bisphenol-based epoxy resin is a compound represented by structural formula 2: [Structural Formula 2] In structural formula 2, R2 and R3 are each independently a hydrogen atom or a C1 to C3 alkyl group, and r is the number of repetitions of the repetition unit, and s are each independently integers from 1 to 3, and t is independently an integer from 1 to 3, and The weight average molecular weight of the bisphenol-based epoxy resin is 1,000 to 1,000,000.
5. In paragraph 1, An adhesive characterized in that the above-mentioned imidazole-based curing agent is a compound represented by structural formula 3: [Structural Formula 3] In structural formula 3, R4 and R5 are each independently a hydrogen atom or a C1 to C5 alkyl group, and R6 is a hydrogen atom or a C1 to C5 alkyl group, and R7 is a hydrogen atom or a C1 to C5 alkyl group.
6. In paragraph 1, The above adhesive Based on 100 parts by weight of the above bisphenol-based epoxy resin 0.1 to 100 parts by weight of the above ester-based epoxy; and An adhesive characterized by comprising 1 to 15 parts by weight of the above-mentioned imidazole-based curing agent.
7. In paragraph 1, The above adhesive Based on 100 parts by weight of the above bisphenol-based epoxy resin 0.5 to 30 parts by weight of the above ester-based epoxy; and An adhesive characterized by comprising 3 to 10 parts by weight of the above-mentioned imidazole-based curing agent.
8. In paragraph 1, An adhesive characterized by further comprising one or more selected from the group consisting of cresol novolac epoxy resin and anhydride curing agent.
9. In paragraph 1, An adhesive characterized by further comprising (3-glycidyloxypropyl)trimethylsiloxane ((3-Glycidyloxypropyl)trimethoxysilane, GPTMS).
10. In paragraph 1, An adhesive characterized by the above adhesive additionally containing silica particles.
11. In paragraph 1, An adhesive characterized by the above adhesive further comprising methyl ethyl ketone (MEK).
12. In paragraph 1, An adhesive characterized by decomposing upon light irradiation after the adhesive has cured, thereby reducing its adhesive strength.
13. In Paragraph 12, An adhesive characterized in that the ester group of the ester-based epoxy is decomposed into a carboxyl group and an aldehyde group by the above light irradiation.
14. In Paragraph 12, An adhesive characterized in that the light is ultraviolet light with a wavelength of 200 to 400 nm.
15. In paragraph 1, An adhesive characterized in that the above adhesive is a non-conductive adhesive.
16. An electronic device module comprising an adhesive layer in which the adhesive according to claim 1 has been cured.
17. In Paragraph 16, An electronic device module characterized by comprising one or more types selected from the group consisting of light-emitting diodes (LEDs) and organic light-emitting diodes (OLEDs).
18. (a) a step of providing a plurality of electronic devices including a defective electronic device and a first substrate; (b) a step of manufacturing an electronic device module comprising a first substrate/cured adhesive layer/multiple electronic devices by placing the adhesive of claim 1 between the first substrate and the plurality of electronic devices and heat-curing it; (c) a step of reducing the adhesive strength of the cured adhesive layer by irradiating light onto the electronic device having the defect of the electronic device module and the cured adhesive layer in contact therewith; (d) a step of contacting the adhesive coating layer of a carrier substrate having an adhesive coating layer formed on its surface with the electronic element of the electronic element module; and (e) a step of moving the carrier substrate to which the electronic device having the defect is attached in a direction opposite to the direction facing the first substrate to separate the electronic device having the defect from the first substrate; A method for isolating an electronic device having a defect that includes.
19. In Paragraph 18, A method for separating an electronic device having defects, characterized in that the light of step (c) is ultraviolet light with a wavelength of 200 to 400 nm.

Description

Photodegradation-based non-conductive adhesive for micro-LED displays and method of manufacturing the same The present invention relates to a photodegradable-based non-conductive adhesive for micro LED displays and a method for manufacturing the same. Recently, Micro LED has been emerging as another next-generation display technology. Micro LED refers to a form cut directly from a wafer used for crystal growth, rather than a package type covered with molded resin. Micro LED displays utilize LED chips themselves, ranging in size from 1 to 100 micrometers (µm), as the light-emitting material. To apply Micro LED to displays, challenges must be addressed, including the development of customized microchips based on flexible materials and devices, as well as technologies for the transfer of micrometer-sized LED chips and precise mounting onto display pixel electrodes. Regarding the transfer of Micro LED chips, in order to carry out a stable LED chip transfer process, there is a technical feature that allows for easy transfer of micro-sized LED chips to a target device using an adhesive film with adhesive properties. However, when a common electrode is used, the light diffusion of the Micro LED may be limited, and a thermal compression process using a tip is carried out at high temperature (approx. 260°C) along with an anisotropic conductive film (ACF). Due to the high temperature and high pressure conditions of the process, damage such as the Micro LED layer breaking and the separation of the upper and lower layers of the Micro LED occurred. Meanwhile, if a defect occurs in any of the Micro LED chips mounted on a specific unit module substrate, a repair process is performed to remove the defective Micro LED chip and replace it with a good Micro LED chip. Conventionally, when a defect occurs in any of the Micro LED chips mounted on the unit module substrate, a high-energy laser is irradiated onto the defective Micro LED chip to remove the cured adhesive layer and the solder material of the defective Micro LED chip. Then, the adhesive coating layer of a carrier substrate, on which an adhesive coating layer is formed on the surface, is brought into contact with the defective electronic component of the electronic component module to remove the component. After applying solder material to that location, a temporary substrate containing a good Micro LED chip is positioned on the unit module substrate at a certain distance. Subsequently, a laser is irradiated to transfer the good Micro LED chip, and through a reflow process, the solder material is melted and bonded, and the adhesive layer is introduced and cured to mount the good Micro LED chip onto the unit module substrate. The conventional repair process described above is complex, and high-energy laser irradiation is essential to remove the cured adhesive layer, which can damage the module substrate and electrodes. Additionally, heat is applied to the remaining good Micro LED chips during the reflow process, and the good Micro LED chips may degrade due to thermal damage. Therefore, research is needed on a repair process that prevents damage to module substrates and electrodes caused by high-energy laser irradiation and enables the easy replacement of defective micro-LED chips. These drawings are for reference to explain exemplary embodiments of the present invention, and therefore, the technical concept of the present invention should not be interpreted as being limited to the attached drawings. FIG. 1 is a flowchart illustrating the method for separating electronic devices according to the present invention. Figure 2 is a schematic diagram showing a method of replacing a defective Micro LED chip using light irradiation in the Micro LED manufacturing method of the present invention. FIG. 3 is a diagram showing the process and yield of synthesizing NBE-a and NBE-b used in Examples 1 and 2 of the present invention. Figure 4 is a diagram showing the structural formulas of NBE-a and NBE-b (o-Nitro benzyl ester epoxy-a, b), 2-ethyl-4-methylimidazole, and bisphenol-based epoxy resin (Bisphenol F epoxy resin, BPF) of the present invention. FIG. 5a is a figure showing the 13 C-NMR and 1 H-NMR spectra of o-Nitro benzyl ester epoxy (NBE-a) of the present invention. FIG. 5b is a figure showing the 13 C-NMR and 1 H-NMR spectra of o-Nitro benzyl ester epoxy (NBE-b) of the present invention. Figure 6 is a drawing showing the P2-1 (by-product) product. Figure 7a is a diagram showing the DSC results of the o -Nitro benzyl ester epoxy (NBE-a) of the present invention. Figure 7b is a diagram showing the TGA results of the o -Nitro benzyl ester epoxy (NBE-a) of the present invention. FIG. 8a is a diagram showing the decomposition behavior of NBE-a used in Example 2 of the present invention and NBE-b used in Example 3. FIG. 8b is a diagram showing the thermal stability of NBE-a used in Example 2 of the present invention and NBE-b used in Example 3. FIG. 9a is a diagram showing the pho