Bonding material composition for mini / micro LED

Abstract

A bonding material composition for a mini / micro LED of the present invention comprises: 40-60wt % of epoxy; 20-40wt % of solder particles coated with an active coating; 1-10wt % of inorganic particles; 0.1-5wt % of a silane coupling agent; and 1-10wt % of a curing agent.

Description

Bonding material composition for mini / micro LEDs

[0001] The present invention relates to a bonding material composition for a mini LED or micro LED, and more particularly, to a bonding material composition used when bonding a mini LED or micro LED to a substrate.

[0002] Since the first practical LED was developed using nickel oxide in 1962, LEDs have become a key material in the display field, used as backlights for 7-segment displays, dot matrix displays, and LCD displays.

[0003]

[0004] Recently, mini LEDs measuring 100-300 ㎛, smaller than conventional LEDs, and micro LEDs measuring 1-100 ㎛ for high-density displays have been developed. This reduces the size of individual LED elements and improves pixel density, enabling sharper, higher-quality displays. Micro LEDs, in particular, are being applied to a wide range of applications, including smartphones, televisions, and virtual and augmented reality equipment.

[0005]

[0006] In order to manufacture a display device using mini LEDs or micro LEDs, an adhesive is applied between the electrode terminals of the substrate and the electrode terminals of the LED chip, and then an alignment process is performed to precisely align the two terminals, and pressure and heat are applied to the LED chip and the substrate to form an electrical connection with each other.

[0007]

[0008] Anisotropic conductive adhesives (ACA) are widely used for this type of electrical connection.

[0009] ACA consists of conductive particles and a thermosetting resin. When the ACA is placed between a substrate and an LED chip and heat and pressure are applied, the conductive particles contact the electrode terminals of the substrate and LED chip, forming an electrical connection. The thermosetting resin hardens, maintaining this electrical connection.

[0010] Commonly used conductive particles include metal balls made of nickel, or polymer balls plated with nickel or gold.

[0011] Even after bonding via ACA is complete, the conductive particles pressed between the substrate and LED chip terminals exert a force that increases the distance between the terminals due to their elasticity. This causes the cured resin to deteriorate over time. The elasticity of the deteriorated resin and the conductive particles can cause cracks in the bonded area, allowing moisture to infiltrate through these cracks, potentially damaging the component.

[0012] In addition, since the terminal and the conductive particle maintain contact according to the elastic deformation of the conductive particle, there is also a problem in that the electrical connection is made in a form in which the contact area is narrow and the electrical resistance is high.

[0013]

[0014] Korean Patent No. 10-2258524 discloses connecting a micro LED to a substrate using an anisotropic conductive sheet with a conductive ball occupancy rate per area limited to 60% or more.

[0015]

[0016] When attaching micro LEDs, they are susceptible to thermal damage, so it is important to ensure that the bonding process, which involves high temperatures and pressure, is carried out in a short period of time.

[0017]

[0018] The applicant of the present invention has disclosed in Korean Patent No. 10-2489828 a solder particle formed with an active film to minimize such thermal damage, and the solder particle is quickly melted by the active film to form an electrical connection between terminals.

[0019]

[0020] The purpose of the present invention is to provide a bonding material composition that can quickly electrically connect a mini / micro LED to a substrate without thermal damage.

[0021]

[0022] The present invention's bonding material composition for mini / micro LED to achieve the above purpose is:

[0023]

[0024] It is composed of 40 to 60 wt% of epoxy, 20 to 40 wt% of solder particles coated with an active film, 1 to 10 wt% of inorganic particles, 0.1 to 5 wt% of a silane coupling agent, and 1 to 10 wt% of a hardener. The hardener is cured at 180 to 250°C, and is characterized by being mixed by selecting two or more of phthalic acid, methyl nadic anhydride (MNA), hexahydrophthalic anhydride (HHPA), tetrahydrophthalic anhydride (THPA), phthalic anhydride (PA), dodecenylsuccinic anhydride (DDSA), chlororendic anhydride (HEAT), and pyromellitic dianhydride (PMDA).

[0025]

[0026] It is preferable that the above epoxy is a mixture of 2 to 4 selected from among Modified DGEBA Type Epoxy, Modified DGEBF Type Epoxy, Novolac Type Epoxy, Brominated Epoxy, Cycloaliphatic Epoxy, Rubber Modified Epoxy, Aliphatic Polyglycidyl Type Epoxy, and Glycidyl Amine Type Epoxy.

[0027]

[0028] It is preferable that the above-mentioned inorganic particles of 1 to 10 wt% are composed of 0.1 to 2 wt% of a mixture of at least one selected from poly methyl methacrylate, polyacrylonitrile, and polyacrylic acid, and 0.9 to 8 wt% of silica.

[0029]

[0030] It is preferable that the solder particles coated with the above active film are solder particles made in the form of an alloy by selecting two or more of the groups Sn, Cu, Au, Ag, and Bi, and coating the active film.

[0031]

[0032] The above silane coupling agent is preferably selected from among 2-(3,4 epoxycyclohexyl) ethyltrimethoxysilane, 3-Glycidoxypropyl methyldimethoxysilane, 3-Glycidoxypropyl trimethoxysilane, 3-Glycidoxypropyl methyldiethoxysilane, 3-Glycidoxypropyl triethoxysilane, and 3-Acryloxypropyl trimethoxysilane.

[0033] According to the bonding material composition of the present invention, it is possible to form an electrical connection while preventing thermal damage to a mini / micro LED, and the durability of the bonding structure is improved.

[0034]

[0035] Hereinafter, the present invention will be described in more detail according to its embodiments.

[0036]

[0037] The bonding material composition of this embodiment is composed of 40 to 60 wt% of epoxy, 20 to 40 wt% of solder particles coated with an active film, 1 to 10 wt% of inorganic particles, 0.1 to 5 wt% of silane coupling agent, and 1 to 10 wt% of curing agent.

[0038]

[0039] Epoxy is a base resin that firmly bonds the two substrates to be bonded together. In this example, Modified DGEBA Type Epoxy (modified bisphenol A type epoxy) and Modified DGEBF Type Epoxy (bisphenol F type epoxy) were used in combination. Modified DGEBA Type Epoxy has a long chain length due to its structure, so its curing speed is slow, but it has flame retardancy, which is suitable for the characteristics of automotive materials that do not emit toxic gases in the event of a fire. Modified DGEBF Type Epoxy has a short chain length, so its curing speed is fast. In order to obtain complementary properties according to different roles, 2 to 4 types of epoxy are selected from the epoxy groups shown in [Table 1] below and mixed together.

[0040]

[0041] 1Modified DGEBA Type Epoxy2Modified DGEBF Type Epoxy3Novolac Type Epoxy4Brominated Epoxy5Cycloaliphatic Epoxy6Rubber Modified Epoxy7Aliphatic Polyglycidyl Type Epoxy8Glycidyl Amine Type Epoxy

[0042] Through the above-described mixing and combination of the curing agent selected in the present invention, it is possible to obtain properties such as high reliability, high adhesive strength, water absorption resistance, flame retardancy, oil resistance, and chemical resistance required in automotive electrical components.

[0043]

[0044] The hardener is used to harden the epoxy in a desired temperature range, and in this embodiment, two or more types of high-temperature hardeners, such as those in [Table 2], are mixed and used, in which the curing reaction starts and ends in a temperature range of 180 to 250°C.

[0045]

[0046] 1Phthalic acid2Metyl nadic anhydride(MNA)3Hexahydrophthalic anhydride(HHPA)4Tetrahydrophthalic anhydride(THPA)5Phthalic anhydride(PA)6Dodecenylsuccinic anhydride(DDSA)7Chlrorendic anhydride(HEAT)8Pyromellitic dianhydride(PMDA)

[0047] The inorganic particles serve to secure a gap between the two terminals and control the viscosity. Silica is included for the purpose of improving strength and controlling viscosity, and one or more of poly methyl methacrylate (PMMA), polyacrylonitrile (PAN), and polyacrylic acid (PAA) are selected to serve as a gapper that maintains the gap between the terminals.

[0048]

[0049] The composition ratio of the above inorganic particles of 1 to 10 wt% is expressed by adding 0.1 to 2 wt% of one or more of PMMA, PAN, and PAA, and 0.9 to 8 wt% of silica. In this example, PMMA was selected as the inorganic particle added together with silica.

[0050]

[0051] The solder particles coated with an active film are solder particles made by selecting two or more of the groups Sn, Cu, Au, Ag, and Bi in the form of an alloy and coating the active film on them. The coating method is preferably performed by the method disclosed in Korean Patent No. 10-2489828. In this embodiment, the solder particles used were SAC305 (Sn / Ag / Cu) with a particle size of 2 to 10 ㎛.

[0052]

[0053] The gap between the two terminals is maintained by the inorganic particles that act as the gapper, while the solder particles, unlike the conductive particles that make elastic contact with the terminals included in the conventional ACA, completely melt within the temperature range of 180 to 250°C of the curing agent, thereby forming a solder joint between the terminals of the substrate. Accordingly, the terminals form an electrical connection with a much lower electrical resistance than the electrical resistance exhibited by the conventional ACA.

[0054]

[0055] Silane coupling agents are adopted to improve adhesion and bonding properties through interface control or to enhance the compatibility of different materials, and two or more types of silane coupling agents are selected and used from the group of silane coupling agents presented in [Table 3] below.

[0056]

[0057] 12-(3,4 epoxycyclohexyl)ethyltrimethoxysilane23-Glycidoxypropyl methyldimethoxysilane33-Glycidoxypropyl trimethoxysilane43-Glycidoxypropyl methyldiethoxysilane53-Glycidoxypropyl triethoxysilane63-Acryloxypropyl trimethoxysilane

[0058] The silane coupling agent group of this example has an epoxy group at the end, so it is suitable for the composition of an adhesive mainly composed of epoxy, as in this example.

[0059]

[0060] A conductive adhesive manufactured with 40 wt% of epoxy mixed with Modified DGEBA Type Epoxy and Modified DGEBF Type Epoxy in a weight ratio of 1:1, 40 wt% of SAC305 solder particles coated with an active film, 8 wt% of silica, 0.5 wt% of PMMA, 0.5 wt% of a silane coupling agent selected as 3-Glycidoxypropyl trimethoxysilane, and 11 wt% of a curing agent mixed with Diethylenetriamine (DETA) and m-pthenylenediamine (m-PDA) in a weight ratio of 1:1 was used to connect mini / micro LEDs to a substrate under conditions of 180 to 250°C, 0.1 to 0.5 Mpa, and pressurization for 3 to 20 seconds. As a result, no damage due to pressure or thermal damage to the components was observed.

[0061]

[0062] It goes without saying that the bonding material composition disclosed in the present application can be applied to various electronic devices as well as mini / micro LEDs.

[0063] The bonding material composition of the present invention is used when bonding a mini LED or micro LED to a substrate.

Claims

1. It is composed of 40 to 60 wt% of epoxy, 20 to 40 wt% of solder particles coated with an active film, 1 to 10 wt% of inorganic particles, 0.1 to 5 wt% of silane coupling agent, and 1 to 10 wt% of curing agent; A bonding material composition for mini / micro LEDs, characterized in that the curing agent is cured at 180 to 250°C, and is prepared by selecting and mixing two or more of Phthalic acid, Methyl nadic anhydride (MNA), Hexahydrophthalic anhydride (HHPA), Tetrahydrophthalic anhydride (THPA), Phthalic anhydride (PA), Dodecenylsuccinic anhydride (DDSA), Chlorendic anhydride (HEAT), and Pyromellitic dianhydride (PMDA).

2. In paragraph 1, The above epoxy is a bonding material composition for mini / micro LED, characterized in that 2 to 4 of Modified DGEBA Type Epoxy, Modified DGEBF Type Epoxy, Novolac Type Epoxy, Brominated Epoxy, Cycloaliphatic Epoxy, Rubber Modified Epoxy, Aliphatic Polyglycidyl Type Epoxy, and Glycidyl Amine Type Epoxy are selected and mixed.

3. In paragraph 1, A bonding material composition for mini / micro LED, characterized in that the above-mentioned inorganic particles are composed of 0.1 to 2 wt% of a mixture of at least one selected from poly methyl methacrylate, polyacrylonitrile, and polyacrylic acid, and 0.9 to 8 wt% of silica.

4. In paragraph 1, A composition of a bonding material for a mini / micro LED, characterized in that the solder particles coated with the above active film are solder particles made in the form of an alloy by selecting two or more of the groups Sn, Cu, Au, Ag, and Bi, and the active film is coated on the solder particles.

5. In paragraph 1, A bonding material composition for a mini / micro LED, characterized in that the silane coupling agent is selected from among 2-(3,4 epoxycyclohexyl) ethyltrimethoxysilane, 3-Glycidoxypropyl methyldimethoxysilane, 3-Glycidoxypropyl trimethoxysilane, 3-Glycidoxypropyl methyldiethoxysilane, 3-Glycidoxypropyl triethoxysilane, and 3-Acryloxypropyl trimethoxysilane.