Curable resin composition, adhesive, cured product, camera module, and electronic device

Abstract

The purpose of the present invention is to provide a curable resin composition that cures rapidly and can reduce the occurrence of bleed.　That is, this curable resin composition comprises an epoxy resin, a latent curing agent, and an imidazole derivative having a melting point of not more than 180°C.

Description

Curable resin composition, adhesive, cured product, camera module, and electronic device

[0001] The present invention relates to a curable resin composition, an adhesive, a cured product, a camera module, and an electronic device.

[0002] In recent years, electronic devices such as mobile terminals and home appliances equipped with camera modules have come into use. When manufacturing electronic devices equipped with camera modules, flip-chip mounting is used as one method for arranging components at high density. The flip-chip mounting method includes, for example, a step of fixing the camera module to a substrate with an adhesive or the like.

[0003] Adhesives used in flip-chip mounting are required to cure quickly in order to improve work efficiency. To meet this requirement, adhesives containing epoxy resins and curing agents have been devised (see, for example, Patent Documents 1 and 2).

[0004] JP 2014-156519 A JP 2010-111711 A

[0005] In flip-chip mounting, an adhesive is used to fill the gap between a semiconductor chip and a substrate, for example. In this case, a phenomenon known as bleeding may occur in which the liquid component of the adhesive (i.e., a curable resin composition) seeps out. When bleeding occurs, the adhesive may adhere to wiring that is not intended to be bonded by the adhesive. For example, if bleeding occurs during the fabrication of a camera module, the adhesive spreads and seeps from under a semiconductor chip, such as a sensor, onto a microlens. As a result, the liquid component of the adhesive seeps onto the microlens and the pads on the substrate, causing the camera module to malfunction.

[0006] Conventional electronic devices are often relatively large, with components spaced far apart. Therefore, even if bleeding occurs, it is difficult for the adhesive components to reach components other than the intended bonding location. Meanwhile, with the demand for smaller electronic devices in recent years, it is becoming increasingly important to consider the effects of bleeding.

[0007] An object of the present invention is to provide a curable resin composition that cures quickly and reduces the occurrence of bleeding, as well as an adhesive, a cured product, a camera module, and an electronic device that use the same.

[0008] In order to achieve the above object, one embodiment of the present invention is as follows. (1) A curable resin composition containing an epoxy resin, a latent curing agent, and an imidazole derivative having a melting point of 180°C or less. (2) The curable resin composition according to (1) above, in which the melting point of the imidazole derivative is 160°C or less. (3) The curable resin composition according to (1) or (2) above, in which the melting point of the imidazole derivative is less than 100°C. (4) An adhesive containing the curable resin composition according to any one of (1) to (3) above. (5) A cured product obtained from the curable resin composition according to any one of (1) to (3) above. (6) A camera module having the cured product according to (5) above. (7) An electronic device having the camera module according to (6) above.

[0009] ==Cross-reference to related literature== This application claims priority based on Japanese Patent Application No. 2022-031853, filed on March 2, 2022, and the basic application is incorporated herein by reference.

[0010] According to the present invention, it is possible to provide a curable resin composition that cures quickly and can reduce the occurrence of bleeding, as well as an adhesive, a cured product, a camera module, and an electronic device that use the same.

[0011] Fig. 1 is a schematic diagram showing an example of a manufacturing process for a camera module according to an embodiment of the present invention, and Fig. 2 is a schematic cross-sectional view showing an example of a camera module according to an embodiment of the present invention.

[0012] (Summary) The occurrence of bleeding during the manufacture of a camera module will be described using Figure 1. For example, when manufacturing a camera module, a heated curable resin composition 70 is supplied into the gap between a substrate 40 and an image sensor 50. The substrate 40 and the image sensor 50 are then heated to cure the curable resin composition.

[0013] The curable resin composition is heated when it is supplied in order to reduce the viscosity of the curable resin composition and make it easier to supply the curable resin composition. Therefore, during the time until the curable resin composition is heated and completely cured, the curable resin composition seeps out onto the substrate 40 from the opening in the gap between the substrate 40 and the image sensor 50, causing bleeding.

[0014] The inventors have investigated the cause of bleeding and found that the components that seep out onto the substrate from the openings are low-molecular-weight components contained in the curable resin composition.

[0015] Therefore, the inventors have investigated a composition that can be cured before low-molecular-weight components bleed out from a curable resin composition with reduced viscosity. As a result of this investigation, they have found that the use of a specific imidazole derivative in combination with a latent curing agent can accelerate curing and further reduce the occurrence of bleeding, which has led to the completion of the present invention.

[0016] (Curable Resin Composition) The curable resin composition according to the embodiment contains an epoxy resin, a latent curing agent, and an imidazole derivative, and preferably contains a filler, and further contains other components as necessary.

[0017] <Epoxy Resin> The epoxy resin is contained to impart curability, heat resistance, and adhesiveness, and to impart durability to the cured product of the curable resin composition. The epoxy resin is not particularly limited as long as it is one of various epoxy resins generally used in semiconductors, and can be appropriately selected depending on the purpose.

[0018] Examples of epoxy resins include bisphenol A epoxy resins, brominated bisphenol A epoxy resins, bisphenol F epoxy resins, bisphenol A / bisphenol F epoxy resins, naphthalene epoxy resins, biphenyl epoxy resins, novolac epoxy resins, aminophenol epoxy resins, alicyclic epoxy resins, ether or polyether epoxy resins, oxirane ring-containing epoxy resins, and polyfunctional epoxy resins. These may be used alone or in combination of two or more. Among these, bisphenol A / bisphenol F epoxy resins, naphthalene epoxy resins, and polyfunctional epoxy resins are preferred from the viewpoints of reducing the viscosity of the curable resin composition and improving moisture resistance reliability.

[0019] The epoxy resin may be synthesized or commercially available. Examples of commercially available products include YD-128, YD-825GS (bisphenol A type epoxy resins, manufactured by Nippon Steel Chemical Co., Ltd.), YDF8170, YDF870GS (bisphenol F type epoxy resins, manufactured by Nippon Steel Chemical Co., Ltd.), EPICLON (registered trademark) EXA 835LV (bisphenol A type / bisphenol F type epoxy resin, manufactured by DIC Corporation), EPICLON (registered trademark) HP 4032D (naphthalene type epoxy resin, manufactured by DIC Corporation), and JER (registered trademark) 630D (multifunctional epoxy resin, manufactured by Mitsubishi Chemical Corporation).

[0020] The content of the epoxy resin is not particularly limited and can be appropriately selected depending on the purpose. However, from the viewpoints of viscosity and workability, the content of the epoxy resin is preferably 40% by mass to 95% by mass, more preferably 45% by mass to 90% by mass, and even more preferably 50% by mass to 88% by mass, based on the curable resin composition excluding the filler.

[0021] <Latent Curing Agent> The latent curing agent is contained in order to promote the curing of the curable resin composition. The latent curing agent is a curing agent that is an insoluble solid at room temperature and softens and reacts when heated. Examples of the latent curing agent include microencapsulated curing agents in which a curing agent is filled in microcapsules.

[0022] The latent curing agent may be a synthesized one or a commercially available product. Commercially available non-microencapsulated latent curing agents include the Fujicure series FXE-1000, Fujicure FXB-1050, FXR1121, and FXR1020 (all manufactured by T&K TOKA Corporation). Commercially available microencapsulated latent curing agents include the Novacure (registered trademark) series HXA9322HP, HX3721, HX3088, HXA3932HP, HXA3922HP, HXA5945HP, and HXA5911HP (all manufactured by Asahi Kasei Corporation). These may be used alone or in combination of two or more. Among these, Novacure HXA9322HP is preferred because of its improved curing rate.

[0023] The content of the latent curing agent is not particularly limited and can be appropriately selected depending on the purpose. From the viewpoints of viscosity and moisture resistance reliability, the content is preferably 2% by mass to 30% by mass, and more preferably 5% by mass to 25% by mass, of the curable resin composition excluding the filler.

[0024] <Imidazole Derivative> The imidazole derivative is contained to promote curing of the curable resin composition. In the present invention, the imidazole derivative is an insoluble solid at room temperature, and is solubilized by heating, thereby promoting curing of the curable resin composition.

[0025] The melting point of the imidazole derivative is 180°C or lower, preferably 160°C or lower, and more preferably lower than 100°C. The imidazole derivative having a melting point of lower than 100°C means that the imidazole derivative is liquid at 100°C. When the imidazole derivative has a melting point of 180°C or lower, the occurrence of bleeding can be reduced. The melting point of the imidazole derivative is preferably 10°C or higher.

[0026] Examples of imidazole derivatives having a melting point of 180°C or less include 2-methylimidazole (melting point: 142°C), 2-undecylimidazole (melting point: 71-75°C), 2-heptadecylimidazole (melting point: 89°C), 2-ethyl-4-methylimidazole (melting point: 47-54°C), 2-phenylimidazole (melting point: 142-148°C), 2-phenyl-4-methylimidazole (melting point: 180°C), 2-phenyl-4-methyl-1H-imidazole (melting point: 174-184°C), 2,3-dihydro-1H-pyrrolo[1,2-a]benzimidazole (melting point: 115°C), (1-[([1 ,1'-biphenyl]-2-yl)oxy]-3-(2-methyl-1H-imidazole-1-yl)propan-2-ol (melting point: 160°C). These may be used alone or in combination of two or more. Among these, 2-undecylimidazole, 2-heptadecylimidazole, and (1-[([1,1'-biphenyl]-2-yl)oxy]-3-(2-methyl-1H-imidazole-1-yl)propan-2-ol are preferred from the viewpoints of the temperature during use, the curing temperature, the curing rate, and the viscosity stability of the paste.

[0027] The content of the imidazole derivative is not particularly limited and can be appropriately selected depending on the purpose. From the viewpoints of the curing rate and the viscosity stability of the paste, the content is preferably 2% by mass to 30% by mass, more preferably 3% by mass to 25% by mass, and even more preferably 3% by mass to 20% by mass, relative to the curable resin composition excluding the filler.

[0028] The ratio of the content of the imidazole derivative to the content of the latent curing agent (imidazole derivative / latent curing agent) is preferably 0.02 to 5, and more preferably 0.05 to 3. When the ratio (imidazole derivative / latent curing agent) falls within this range, the occurrence of bleeding can be reduced.

[0029] <Filler> The filler is contained to adjust the properties (mainly the linear expansion coefficient, elastic modulus, and water absorption) of the cured product of the curable resin composition. The type of filler is not particularly limited and can be appropriately selected depending on the purpose. Examples of fillers include silica such as fused silica and crystalline silica; calcium carbonate, clay, alumina, silicon nitride, silicon carbide, boron nitride, calcium silicate, potassium titanate, aluminum nitride, beryllia, zirconia, zircon, fosterite, steatite, spinel, mullite, titania, aluminum hydroxide, magnesium hydroxide, zinc borate, and zinc molybdate. These may be used alone or in combination of two or more. Among these, silica fillers are preferred from the viewpoints of stability and heat resistance.

[0030] The filler may be surface-treated. The surface treatment agent is not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include silane coupling agents.

[0031] The silane coupling agent is not particularly limited and can be appropriately selected depending on the purpose. Examples include epoxy-based, methacrylic-based, amino-based, vinyl-based, glycidoxy-based, and mercapto-based silane coupling agents.

[0032] The volume average particle size of the filler is not particularly limited and can be appropriately selected depending on the purpose, and is, for example, preferably 0.03 μm to 10 μm, more preferably 0.05 μm to 5 μm, and even more preferably 0.05 μm to 2 μm. In this embodiment, the volume average particle size refers to the particle size at which the cumulative volume particle size distribution measured by laser diffraction method is 50%.

[0033] The shape of the filler is not particularly limited and can be appropriately selected depending on the purpose. Examples include spherical, irregular, and flaky shapes, with spherical shapes being preferred.

[0034] The content of the filler is not particularly limited and can be appropriately selected depending on the purpose.

[0035] <Other Components> The other components are not particularly limited as long as they are contained in a typical curable resin composition and can be appropriately selected depending on the purpose, and examples thereof include colorants such as carbon black and titanium black, ion trapping agents, leveling agents, antioxidants, antifoaming agents, thixotropic agents, viscosity modifiers, flame retardants, solvents, etc. These may be used alone or in combination of two or more.

[0036] The contents of other components are not particularly limited and can be appropriately selected depending on the purpose.

[0037] The curable resin composition according to the present invention can suppress bleeding for the following two reasons. First, by including an imidazole derivative that is solid at room temperature, the curable resin composition can easily adhere to the unevenness of the substrate, thereby suppressing the exudation of the curable resin composition. Second, by including a latent curing agent, the latent curing agent dissolves when heated, thereby accelerating curing. In other words, the curable resin composition can be cured before it exudes.

[0038] -Method for Producing Curable Resin Composition- The method for producing the curable resin composition is not particularly limited and can be appropriately selected depending on the purpose. For example, the method includes mixing and stirring the above components.

[0039] The components may be mixed simultaneously, or some of the components may be mixed first and the remaining components may be mixed later.If it is difficult to uniformly disperse the filler in the epoxy resin, the epoxy resin and the filler may be mixed first and the remaining components may be mixed later.

[0040] The device used for mixing and stirring is not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include a roll mill.

[0041] (Adhesive) The adhesive according to this embodiment contains the above-described curable resin composition.

[0042] (Cured Product) The cured product according to this embodiment is obtained by curing the curable resin composition described above. The shape and thickness of the cured product are not particularly limited and can be appropriately selected depending on the purpose.

[0043] The curable resin composition can be cured, for example, by heating. The heating temperature is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 80° C. to 150° C., and more preferably 100° C. to 130° C. The heating time is not particularly limited and can be appropriately selected depending on the purpose, and can be, for example, 1 minute to 2 hours.

[0044] (Camera Module) The camera module according to this embodiment has the cured product described above. Here, the camera module according to this embodiment will be described with reference to FIG. 2. The camera module shown in FIG. 2 has a lens barrel 10, a housing 20, an IR filter 30, a substrate 40, an image sensor 50, and a microlens 55. The lens barrel 10 is a member that holds a plurality of lenses 11. The lens barrel 10 is fixed to the housing 20. The lower end of the housing 20 is fixed to the upper surface of the substrate 40. The housing 20 is provided with an IR filter 30 that filters light that has passed through the lenses 11. The substrate 40 is connected to the image sensor 50 via bumps 51. A cured product 60 obtained by curing the curable composition described above is provided between the substrate 40 and the image sensor 50.

[0045] During the manufacture of the camera module, the curable resin composition is supplied through the gap between the substrate 40 and the image sensor 50. The camera module is then heated to harden the curable resin composition. The hardening of the curable resin composition seals the gap between the substrate 40 and the image sensor 50. The curable resin composition according to the present invention can reduce the occurrence of bleeding, thereby preventing contamination of the microlens 55 and pads (not shown) on the substrate 40.

[0046] The method for supplying the curable resin composition is not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include a jet dispenser and an air dispenser. Furthermore, when supplying the curable resin, the curable resin composition may be heated to reduce the viscosity of the curable resin composition. The temperature at which the curable resin composition is heated is not particularly limited as long as the curable resin composition does not cure, and can be appropriately selected depending on the purpose, and examples thereof include 40°C to 60°C.

[0047] (Electronic Device) The electronic device according to this embodiment includes the camera module described above, and further includes other components as necessary. The other components are not particularly limited and can be selected appropriately depending on the purpose. Examples of the electronic device include mobile terminals and home appliances.

[0048] (Examples 1 to 14, Comparative Examples 1 to 4) Curable resin compositions were obtained by mixing and homogenizing the ingredients in the formulations shown in Tables 1 to 4 using a triple roll mill. Note that the numerical values ​​in the tables represent parts by mass unless otherwise specified.

[0049]

[0050]

[0051]

[0052]

[0053] The epoxy resins used in the examples and comparative examples are as follows: Bis A / Bis F type (EPICLON (registered trademark) EXA 835LV, manufactured by DIC Corporation) Naphthalene type (EPICLON (registered trademark) HP 4032D, manufactured by DIC Corporation) Multifunctional type (Jer (registered trademark) 630D, manufactured by Mitsubishi Chemical Corporation)

[0054] The latent curing agents used in the examples and comparative examples are as follows. Latent curing agents 1-6 each contain approximately 67% by mass of epoxy resin, and latent curing agent 7 contains approximately 50% by mass of epoxy resin. The value for the latent curing agent in the table is the total amount including the epoxy resin. Latent curing agent 1 (Novacure (registered trademark) HXA9322HP, manufactured by Asahi Kasei Corporation) Latent curing agent 2 (Novacure (registered trademark) HX3721, manufactured by Asahi Kasei Corporation) Latent curing agent 3 (Novacure (registered trademark) HX3088, manufactured by Asahi Kasei Corporation) Latent curing agent 4 (Novacure (registered trademark) HXA3932HP, manufactured by Asahi Kasei Corporation) Latent curing agent 5 (Novacure (registered trademark) HXA3922HP, manufactured by Asahi Kasei Corporation) Latent curing agent 6 (Novacure (registered trademark) HXA5945HP, manufactured by Asahi Kasei Corporation) Latent curing agent 7 (Novacure (registered trademark) HXA5911HP, manufactured by Asahi Kasei Corporation)

[0055] The imidazole derivatives used in the examples and comparative examples are as follows: Imidazole derivative 1 (2-undecylimidazole, Curazole C11Z, manufactured by Shikoku Chemical Industry Corporation) Imidazole derivative 2 (2-heptadecylimidazole, Curazole C17Z, manufactured by Shikoku Chemical Industry Corporation) Imidazole derivative 3 (2-phenylimidazole, Curazole 2PZ, manufactured by Shikoku Chemical Industry Corporation) Imidazole derivative 4 (2-phenyl-4-methyl-1H-imidazole, Curazole 2P4MZ, manufactured by Shikoku Chemical Industry Corporation) Imidazole derivative 5 (1-[([1,1'-biphenyl]-2-yl)oxy]-3-(2-methyl-1H-imidazole-1-yl)propan-2-ol, OPPG-2MZ, synthesized according to the synthesis method for (Compound 1) in the pamphlet of WO 2021 / 201060) Imidazole derivative 6 (2,4-diamino-6-(2'-methylimidazolyl)ethyl-1,3,5-triazine, Curesol 2MZA, manufactured by Shikoku Chemical Industry Corporation) Imidazole derivative 7 (2,4-diamino-6-[2'-undecylimidazolyl-(1')]-ethyl-s-triazine, Curesol C11Z-A, manufactured by Shikoku Chemical Industry Corporation) Imidazole derivative 8 (2,4-diamino-6-(2'-methylimidazolyl)ethyl-1,3,5-triazine, Curesol 2MZA-PW, manufactured by Shikoku Chemicals Corporation)

[0056] The fillers and other components (thixotropic agents) used in the examples and comparative examples are as follows: Filler (silica, SO-E5, particle size: 1.3 to 1.7 μm, manufactured by Admatechs Co., Ltd.) Thixotropic agent (silica nanofiller, Aerosil (registered trademark) R805, particle size: 12 nm, manufactured by Nippon Aerosil Co., Ltd.) Note that the filler and the thixotropic agent have different particle sizes. The particle size of the filler is several hundred nanometers to several tens of μm, while the particle size of the thixotropic agent is approximately several tens of nanometers.

[0057] The DSC peak temperature and exudation distance of the obtained curable resin composition were measured, and the presence or absence of bleeding and curability were evaluated. The measurement results and evaluation results are shown in Tables 1 to 4.

[0058] <Seepage distance, presence or absence of bleeding> Ceramic substrate, O ２ Plasma treatment (300 W, 1 minute) was performed. ２ 1 mg of each curable resin composition filled in a syringe was dispensed and potted onto the plasma-treated ceramic substrate, and the substrate was left at 60°C for 3 hours. After leaving the substrate, the distance the curable resin composition had exuded (exudation distance, i.e., bleed length) was measured using an optical microscope. The occurrence of bleeding (presence or absence of bleeding) was evaluated based on the following evaluation criteria. -Evaluation criteria- ◎: Exudation distance was 0 mm to less than 0.1 mm; ○: Exudation distance was 0.1 mm to less than 1 mm; ×: Exudation distance was 1 mm or more

[0059] <DSC Peak Temperature, Curability (Short-time Curing at 150°C)> Approximately 5 mg of each curable resin composition was dropped onto an aluminum pan. This aluminum pan was set in a DSC (DSC204F1 Phoenix, manufactured by Bruker Japan Co., Ltd.) and heated from 25°C to 250°C at a temperature increase rate of 10°C / min to obtain a DSC chart. The DSC exothermic peak temperature was read from the obtained DSC chart. The DSC exothermic peak temperature was evaluated as curability (short-time curing at 150°C) based on the following evaluation criteria. Note that if the DSC exothermic peak temperature is less than 125°C, it can be cured in a short time at 150°C. -Evaluation Criteria- ◯: DSC exothermic peak temperature is less than 125°C; ×: DSC exothermic peak temperature is 125°C or higher

[0060] As shown in Tables 1 to 4, the curable resin compositions of the Examples had good curability and were evaluated as "Good" or better in terms of the occurrence of bleeding. This clearly shows that all of the curable resin compositions of the Examples were able to cure quickly and reduce the occurrence of bleeding. On the other hand, Comparative Example 1, which did not contain an imidazole derivative, had good curability but did cause bleeding. Furthermore, Comparative Examples 2 to 4, which contained an imidazole derivative having a melting point of over 180°C, were able to reduce the occurrence of bleeding but took a long time to cure. These results clearly show that curable resin compositions containing both a latent curing agent and an imidazole derivative having a melting point of 180°C or less can cure quickly and reduce the occurrence of bleeding.

[0061] Although the embodiments and examples of the present invention have been described, they are presented as examples and are not intended to limit the scope of the invention. The embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. The embodiments and their modifications are included within the scope and spirit of the invention, as well as the inventions described in the claims and their equivalents.

Claims

1. A curable resin composition comprising an epoxy resin, a latent curing agent, and an imidazole derivative having a melting point of 180°C or less.

2. The curable resin composition according to claim 1, wherein the imidazole derivative has a melting point of 160°C or lower.

3. The curable resin composition according to claim 1, wherein the imidazole derivative has a melting point of less than 100°C.

4. An adhesive comprising the curable resin composition according to claim 1 .

5. A cured product obtained from the curable resin composition according to claim 1 .

6. A camera module comprising the cured product according to claim 5 .

7. An electronic device comprising the camera module according to claim 6.