Film-like adhesive, laminated lens provided with cured film of the same, and dope for film-like adhesive

Abstract

To provide: a film-like adhesive which has low transmittance and reflectance of light when formed into a cured film; a film-like adhesive which is capable of simultaneously satisfying bonding properties before curing, low water absorption rate in a cured state, and adhesive force at high temperatures; a laminated lens which is provided with a cured film of the same; and a dope for a film-like adhesive.SOLUTION: A film-like adhesive contains an epoxy resin (A), an epoxy resin curing agent (B), a polymer component (C), an inorganic filler (D), and a coloring agent (E). The polymer component (C) contains a phenoxy resin. The film-like adhesive contains a specific amount of the inorganic filler (D), a specific amount of the epoxy resin (A), a specific amount of the epoxy resin curing agent (B), and a specific amount of the coloring agent (E).SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a film adhesive, a laminated lens having a cured film thereof, and a dope for the film adhesive. [Background technology]

[0002] Film-type adhesives are used in a variety of industrial fields. For example, they are used to bond a wide variety of components in various electronic devices. For example, in wafer-level lenses used in cameras and video cameras for mobile devices, when the lenses are stacked, film-type adhesives are used to bond and fix each lens. Alternatively, substrate-attached pressure-sensitive adhesive sheets having a light-blocking pressure-sensitive adhesive layer containing a pigment are used for the purposes of preventing light leakage from light sources such as backlight modules in liquid crystal display devices and self-luminous elements such as organic electroluminescence (EL) displays, and for preventing reflection. Specifically, Patent Document 1 discloses a pressure-sensitive adhesive composition that uses an acrylic pressure-sensitive adhesive polymer, a terpene phenolic resin as a tackifying resin, an isocyanate crosslinking agent as a crosslinking agent, and carbon black. The adhesive strength, shear adhesive strength, and hiding power of this pressure-sensitive adhesive composition at room temperature under conditions of a peel angle of 180° were evaluated. Patent Document 2 discloses a pressure-sensitive adhesive composition that blends benzotriazole and terpene phenolic resin, an isocyanate crosslinking agent, an epoxy crosslinking agent, etc. with an acrylic polymer, and carbon black particles as a light-blocking material. The total light transmittance of this pressure-sensitive adhesive composition and peel strength at 180° at room temperature were evaluated. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6945090 specification [Patent Document 2] Japanese Patent Application Publication No. 2023-112140 Summary of the Invention [Problem to be solved by the invention]

[0004] FIG. 1 is a cross-sectional view schematically illustrating the structure of a laminated lens. The laminated lens 10 of this embodiment employs a structure in which three layers of lenses 1 are stacked above an image sensor 2. A cured film 3 of a film-like adhesive is used as a means for fixing these three layers of lenses 1, 1, 1 in their respective positions. Conventionally, colorless film-like adhesives have been used in laminated lenses, but this allows light to penetrate through the film-like adhesive. Furthermore, light diverging from the interior to the exterior is reflected rather than absorbed by the film-like adhesive. This light transmission and reflection cause flare and ghosting in photographs during development. Furthermore, the adhesive's ability to bond with lenses and other components, and its adhesive strength at high temperatures when cured, have not been given much attention, and it cannot be said that a film-like adhesive with high performance has necessarily been provided.

[0005] Therefore, an object of the present invention is to provide a film-like adhesive that has low light transmittance and low reflectance when formed into a cured film. Another object of the present invention is to provide a film-like adhesive that exhibits excellent lamination properties before curing and that, when cured, has low water absorption and high adhesive strength at high temperatures, a laminated lens comprising such a cured film, and a dope (slip) for the film-like adhesive. [Means for solving the problem]

[0006] As a result of extensive research conducted by the inventors in response to the above technical problems, it was discovered that the above multiple problems can be solved all at once by providing a film-like adhesive comprising a curable resin composition containing a polymer component (phenoxy resin) as a base agent, and further containing an epoxy resin and its curing agent, an inorganic filler, and a colorant, in which the blending amounts of each component are specified. That is, the present invention comprises the following means.

[0007] (1) A film-like adhesive containing an epoxy resin (A), an epoxy resin curing agent (B), a polymer component (C), an inorganic filler (D), and a colorant (E), the polymer component (C) contains a phenoxy resin, the inorganic filler (D) is 70 parts by mass to 720 parts by mass relative to 100 parts by mass of the polymer component (C), the epoxy resin (A) is 70 parts by mass to 350 parts by mass relative to 100 parts by mass of the polymer component (C), the epoxy resin curing agent (B) is 1.4 parts by mass or more per 100 parts by mass of the epoxy resin (A), A film-like adhesive in which the colorant (E) is 10 parts by mass or more, based on 100 parts by mass of the total of the epoxy resin (A) and the polymer component (C). (2) The film adhesive according to (1), wherein a cured film cured at 120°C to 180°C has a transmittance of less than 10% for light in the range of 400 nm to 1100 nm when the film has a thickness of 10 μm to 125 μm. (3) The film adhesive according to (1) or (2), wherein the cured film cured at 120°C to 180°C has a reflectance of less than 7% for light in the range of 400 nm to 1100 nm when the film has a thickness of 10 μm to 125 μm. (4) The film adhesive according to any one of (1) to (3), characterized in that the thickness is in the range of 5 μm or more and 150 μm or less. (5) A film-like adhesive according to any one of (1) to (4), which has a melt viscosity at 70°C in the range of 6,000 to 65,000 Pa·s when heated from 25°C at a heating rate of 5°C / min. (6) The film adhesive according to any one of (1) to (5), wherein the colorant (E) contains carbon black. (7) The film-like adhesive according to any one of (1) to (6), wherein the phenoxy resin is a thermoplastic resin having a molecular weight of 10,000 to 100,000, obtained by reacting a bisphenol compound with a glycidyl group-containing compound. (8) The film-like adhesive according to any one of (1) to (7), which is used for bonding lenses used in a laminated lens. (9) A laminated lens in which the film adhesive according to any one of (1) to (8) is applied to adhere the lens, and a cured film obtained by curing the film adhesive is incorporated so as to adhere at the adhesive portion. (10) a phenoxy resin (C'); 70 to 350 parts by mass of the epoxy resin (A) relative to 100 parts by mass of the phenoxy resin (C'); an epoxy resin curing agent (B) in an amount of 1.4 parts by mass or more per 100 parts by mass of the epoxy resin (A); 70 to 720 parts by mass of the inorganic filler (D) relative to 100 parts by mass of the phenoxy resin (C'); a colorant (E) in an amount of 10 parts by mass or more relative to 100 parts by mass of the total of the epoxy resin (A) and the phenoxy resin (C'); A dope for a film adhesive comprising the above in a solvent. [Effects of the Invention]

[0008] According to the present invention, it is possible to suppress light transmission and reflection in a cured film obtained by curing the film-like adhesive. In addition, the film-like adhesive has excellent lamination properties, and the cured film exhibits low water absorption and high adhesive strength at high temperatures. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a cross-sectional view schematically illustrating an embodiment of a laminated lens structure. [Figure 2] 1 is a process diagram illustrating the preparation and application process of a film adhesive according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0010] The film-like adhesive of the present invention contains an epoxy resin (A), an epoxy resin curing agent (B), a polymer component (C), an inorganic filler (D), and a colorant (E). Preferred embodiments will be described below in the order of the above components.

[0011] <Epoxy resin (A)> The epoxy resin can be appropriately selected from curable resins suitable for this type of product and used. Examples include cycloalkane-containing epoxy resins, novolac-type epoxy resins, and bisphenol-type epoxy resins. The bisphenol may be bisphenol A or bisphenol F, with bisphenol A-type epoxy resins being more preferred. Examples of epoxy resins include those having the following structure: n is a natural number, preferably 1 to 10, more preferably 1 to 4, and particularly preferably 1 or 2. [ka] The film adhesive of the present invention can ensure adhesive strength and reliability by incorporating an epoxy resin and an inorganic filler, and can be cured by heat by incorporating an epoxy resin curing agent. The amount of epoxy resin blended is preferably adjusted to a suitable range, taking into consideration the blending of other additives such as curing agents. Specifically, the amount of the epoxy resin (A) is 70 parts by mass or more, preferably 90 parts by mass or more, and more preferably 100 parts by mass or more, per 100 parts by mass of the polymer component (C) described below. The upper limit is 350 parts by mass or less, preferably 300 parts by mass or less, and more preferably 270 parts by mass or less. One type of epoxy resin may be used, or two or more types may be used. When two or more types are used, the total amount falls within the above range. The molecular weight of the epoxy resin (A) is not particularly limited, but is preferably not more than 2,000, more preferably not more than 1,500, and even more preferably not more than 1,000. The lower limit is not particularly limited, but a practical value is 300 or more.

[0012] <Epoxy resin hardener (B)> The epoxy resin curing agent is preferably a compound that can suitably cure the above-mentioned epoxy resin. The epoxy resin may be cured by photocuring or heat curing, but heat curing is preferred in the present invention. Examples of epoxy resin curing agents include organic amine-based curing agents and imidazole-based (imidazole cyanide, imidazole hydroxymethyl) curing agents. Examples of epoxy resin curing agents include those having the following structure: [C2] (CH3O)3SiC3H6NHC2H4NH2(d) [ka] [ka] The amount of epoxy resin curing agent (B) may be appropriately selected depending on the amount of epoxy resin (A), but is preferably 1.4 parts by mass or more, more preferably 1.8 parts by mass or more, and even more preferably 2 parts by mass or more, of epoxy resin curing agent (B) per 100 parts by mass of epoxy resin (A). While there is no particular upper limit, from the viewpoint of resin component bloom and the like, an amount that is too high is undesirable, and it is preferably 30 parts by mass or less, more preferably 20% by mass or less, and even more preferably 10 parts by mass or less. One or more types of epoxy resin curing agents may be used. When two or more types of components are included, the total amount is defined.

[0013] <Polymer component (C)> In the present invention, a phenoxy resin is used as the polymer component. The phenoxy resin is preferably an amorphous thermoplastic resin obtained by polymerizing a bisphenol compound (such as bisphenol A or bisphenol F) and a glycidyl group-containing low molecular weight compound (such as epichlorohydrin). Here, "low molecular weight" refers to a compound with a molecular weight of less than 500. The structural formula of an example of a phenoxy resin is shown below. In the formula, n is a natural number, preferably 30 or more and 300 or less, more preferably 45 or more and 250 or less, and even more preferably 60 or more and 200 or less. * in the formula represents a bond. [ka] The use of a phenoxy resin in the film adhesive of the present invention can ensure higher adhesive strength than that of an acrylic resin. Furthermore, the use of a phenoxy resin can improve film properties (handleability). Phenoxy resin is preferably a resin that is amorphous and thermoplastic due to an increase in the repeating unit of the polymer. By using phenoxy resin as the polymer component, high adhesive strength can be ensured. Furthermore, by using phenoxy resin, film properties (handling ease) can be ensured. The amount of polymer component (C) can be determined taking into consideration the stability of the shape of the uncured (pre-cured) film-like adhesive. The amount of polymer component (C) can be determined in relation to the other components.

[0014] The molecular weight of the polymer component (C) is not particularly limited, but is preferably 10,000 or more, more preferably 15,000 or more, and even more preferably 20,000 or more in weight average molecular weight. The upper limit is preferably 100,000 or less, more preferably 80,000 or less, and even more preferably 75,000 or less. In the present invention, unless otherwise specified, the term "molecular weight" refers to the weight average molecular weight in terms of polystyrene determined by gel permeation chromatography (GPC). The carrier may be appropriately selected, and examples thereof include THF (tetrahydrofuran).

[0015] <Inorganic filler (D)> The inorganic filler can be selected from those applicable to this type of product and used appropriately. Examples include silicon compounds, such as silicic acid, calcium silicate, silica gel, glass fiber, and vinylsilane-treated silica. Other than silicon compounds, examples include calcium carbonate, molybdenum oxide, barium sulfate, carbon fiber, various ferrites, alumina, AlN, BN, BeO, mica, graphite, iron powder, lead, talc, titanium oxide, antimony oxide, aluminum hydroxide, magnesium hydroxide, and zinc oxide. Among these, silicon compounds are preferred in the present invention, and vinylsilane-treated silica is preferred. The amount of inorganic filler to be used is preferably adjusted to a suitable range, taking into consideration its advantages and disadvantages. Specifically, the inorganic filler (D) is 70 parts by mass or more, preferably 100 parts by mass or more, and more preferably 130 parts by mass or more, per 100 parts by mass of the polymer component (C). The upper limit is 720 parts by mass or less, preferably 650 parts by mass or less, and more preferably 500 parts by mass or less. When two or more types of inorganic filler are contained, the total amount is defined as the total amount.

[0016] <Colorant (E)> The colorant is important in determining the optical properties of the film adhesive. Specifically, a colorant with low light transmittance and low light reflectance is preferred. From this perspective, a black colorant is preferred, and carbon black is more preferred. Adding a colorant (such as carbon black) to the film can reduce the light transmittance and reflectance. The colorant (E) is 10 parts by mass or more, preferably 12 parts by mass or more, and more preferably 14 parts by mass or more, based on 100 parts by mass of the total of the epoxy resin (A) and the polymer component (C). There is no particular upper limit, but considering problems such as blooming, it is preferable that the amount is not too high, and it is preferably 50 parts by mass or less, more preferably 45 parts by mass or less, and even more preferably 40 parts by mass or less. When the colorant contains two or more components, the total amount is specified.

[0017] <Solvent> The solvent used in producing the film-like adhesive of the present invention is not particularly limited, but examples include alcohols, ketones, ethers, aryls, aldehydes, esters, etc. Among these, in the present invention, ketones are preferred, and MEK (methyl ethyl ketone) is more preferred. The amount of solvent used is an amount that dissolves and disperses the above-mentioned blended components and is thoroughly mixed, while it is preferable to use an amount that can volatilize during production and be formed into a film.

[0018] <Manufacturing and application methods of film adhesives> FIG. 2 is a process diagram illustrating the preparation and application process of the film adhesive of this embodiment. The film adhesive of this embodiment is prepared by first dissolving and dispersing the epoxy resin (A), epoxy resin curing agent (B), polymer component (C), inorganic filler (D), and colorant (E) in a solvent to prepare a dope for molding the film adhesive. This dope for molding the film adhesive is poured into a predetermined mold as needed, and the solvent is removed at a predetermined temperature to form the adhesive. The temperature is not particularly limited, but a preferred range is 70°C to 130°C (preferably 80°C to 120°C). The heating time is preferably 1 minute or longer, more preferably 3 minutes or longer, and even more preferably 5 minutes or longer. There is no particular upper limit, but a practical range is 10 minutes or shorter. The film adhesive in this state has not undergone a curing reaction by the epoxy groups inside it, and can be said to be in a provisionally cured state. The formed film adhesive can be used as is, or it can be further molded into a desired shape by laser processing or the like. The molded film-like adhesive cures at a temperature of, for example, 100°C to 210°C (preferably 120°C to 180°C), and the epoxy groups of the blended epoxy resin react with the epoxy resin curing agent to irreversibly harden into a cured film. The heating time is preferably 30 minutes or more, more preferably 1 hour or more, and even more preferably 2 hours or more. There is no particular upper limit, but 5 hours or less is practical.

[0019] <Laminated Lens Manufacturing Method> FIG. 1 is a cross-sectional view of an apparatus schematically illustrating one embodiment of the structure of a laminated lens. The film-like adhesive in the provisionally cured state described above is placed and bonded to at least a portion of the adhesive joint 12 where the lenses 1 are laminated, preferably by dicing, to form sidewalls 11. In this embodiment, three layers of lenses 1 are laminated. The film-like adhesive is placed at each adhesive joint to form sidewalls 11. In this state, the semiconductor element is exposed to high temperatures (e.g., 150°C), causing the epoxy resin blended as described above to react with the epoxy resin curing agent to form a fully cured cured film 3. This fixes the shape, and the lens is diced as necessary to produce a highly durable and strong laminated lens 10. In this embodiment, the lens before dicing is called a wafer-level lens (wafer-level optical component), but the lens that has been diced into individual pieces is called a laminated lens (lens laminate).

[0020] The shape of the laminated lens is not particularly limited, but the spacer between the image sensor and the lens is preferably approximately 125 μm thick to ensure sufficient focal length. The spacer between the lenses is preferably approximately 10 μm thick to allow for inter-lens adhesion. Even if a spacer is made from a paste-like resin, it is difficult to create one with a thickness of 100 μm or more. This can be conveniently achieved by providing the film-like adhesive of the present invention with both adhesive and spacer functions. From this perspective, the thickness of the film-like adhesive of the present invention is preferably 4 μm or more, more preferably 5 μm or more, and even more preferably 7 μm or more. The upper limit is preferably 200 μm or less, more preferably 150 μm or less, and even more preferably 130 μm or less. The film-like adhesive of this embodiment does not generally shrink or expand when cured to form a cured film, and maintains its shape. Therefore, the preferred thickness ranges described above also apply to the cured film.

[0021] <Characteristics of film adhesive and cured film> The film-like adhesive of the present invention is in a provisionally cured state, and when fully cured (at 100 to 210°C, preferably 120 to 180°C, and more preferably 180°C) to form a cured film, the film has a thickness of 10 μm to 125 μm and a light transmittance of preferably less than 10%, more preferably less than 8%, and even more preferably less than 5% in the range of 400 nm to 1100 nm. There is no particular lower limit, but it is preferable that the film does not transmit light at all. Regarding reflectance, when a cured film is formed by main curing (at 100°C to 210°C, preferably 120 to 180°C, and more preferably 180°C), the reflectance in the range of 400 nm to 1100 nm at a thickness of 10 μm to 125 μm is preferably less than 15%, more preferably less than 10%, and even more preferably less than 7%. There is no particular lower limit, but it is preferable that the film does not reflect light at all. By reducing the light transmittance and light reflectance specified here, ghosts and flares can be suppressed during development. Flare is the phenomenon in which light leaks into dark areas of a photograph and occurs when strong light is reflected inside the camera or lens. Ghosts are the phenomenon in which light reflected inside the lens appears as balls or bands. The film-like adhesive of the present invention, in the form of a fully cured film, preferably has an adhesive strength of 5 MPa or more at 260°C, more preferably 6 MPa or more, and even more preferably 7 MPa or more. There is no particular upper limit, but a practical value is 25 MPa or less. The films in Patent Documents 1 and 2 are designed to be peelable, and have weak adhesive strength. Furthermore, they are not designed to be heated to 260°C, and even if they are heated to 260°C, it is understood that the viscosity would be too low to maintain the stability of the shape. When the film-like adhesive of the present invention is heated from 25°C at a heating rate of 5°C / min, the melt viscosity at 70°C is preferably in the range of 6,000 to 65,000 Pa·s, more preferably in the range of 8,000 to 50,000 Pa·s, even more preferably in the range of 10,000 to 40,000 Pa·s, and particularly preferably in the range of 12,000 to 35,000 Pa·s. The water absorption rate of the film-like adhesive of the present invention is preferably 2% or less, more preferably 1.5% or less, even more preferably less than 1.3%, even more preferably 1.2% or less, and even more preferably 1.1% or less. There is no particular lower limit, but a practical value is 0.3% or more.

[0022] Up to this point, the embodiments of the present invention have been described, focusing on the application to laminated lenses. However, the film adhesive of the present invention is not necessarily limited to this use, and can also be used as a sealant for light sources such as backlight modules in liquid crystal display devices, a sealant for self-luminous elements such as organic EL, and automotive LiDAR. [Example]

[0023] <Composition ingredients> [Epoxy resin (A)] RE-310S Bisphenol A epoxy resin (manufactured by Nippon Kayaku Co., Ltd.) ZX-1059 Liquid BPA / BPF high-purity epoxy resin (manufactured by Nippon Steel Chemical & Material Co., Ltd.) XD-1000 Nippon Kayaku Co., Ltd. Weight average molecular weight: 1,200 [ka] LX1 Bisphenol A epoxy resin manufactured by Daiso Chemical Co., Ltd. JER1002 A bisphenol A epoxy resin produced by the condensation reaction of bisphenol A and epichlorohydrin. Manufactured by Mitsubishi Chemical Corporation. [ka] EOCN-102 Novolac epoxy resin [ka] Manufactured by Nippon Kayaku Co., Ltd. [Epoxy resin hardener (B)] 2PHZ-PW 2-phenyl-4,5-dihydroxymethylimidazole (Shikoku Chemicals Corporation) [ka] 2PZ-CN [ka] DICY15 Powder Grade Dicyandiamide Finely Ground Product, Mitsubishi Chemical Corporation [Polymer component (C)] YP50-EK35: Phenoxy resin, Nippon Steel Chemical & Materials, weight average molecular weight 57,000 SG-P3: Acrylate ester polymer with epoxy functionality, manufactured by Nagase ChemteX Corporation Weight average molecular weight 850,000 [Inorganic filler (D)] SC2050-MNU Vinylsilane-treated silica MEK slurry (manufactured by Admatechs Co., Ltd.) SC5050-MLC ADMAFINE SO-C5 MEK slurry RY-200 Dimethylpolysiloxane-treated silica K180SV-CM2 MEK slurry of vinyltrimethoxysilane-treated silica [Colorant (E)] #30L Carbon Black A903 Carbon Black ET6N109 Bisphenol A epoxy resin 50-60% by mass Carbon black 15-25% by mass

[0024] Example 1 (Preparation of dope for film adhesive) 50 parts by mass of the RE-310S, 20 parts by mass of the JER1002, 1 part by mass of 2PHZ-PW, 100 parts by mass of YP50-EK35, 200 parts by mass of SC2050-MNU, and 25 parts by mass of A903 were weighed and mixed, and the mixture was stirred in a sufficient amount of MEK (methyl ethyl ketone) for 1 hour to dissolve and disperse these components, thereby preparing dope (sludge) s1 of Example 1.

[0025] (Preparation of film adhesive: temporary curing) The dope s1 was placed in a mold of a predetermined thickness and allowed to stand in a thermostatic chamber at 110°C for 3 minutes to remove the solvent, yielding a film-like adhesive s1 of Example 1 with a stable shape. The size was 10 mm x 10 mm. A release sheet had been placed in the mold beforehand.

[0026] (Film adhesive hardening: Main hardening) The resulting film-like adhesive s1 with the release sheet attached was processed into the desired shape by laser processing. This was then bonded to a dummy silicon wafer that would become an image sensor. The release sheet was then peeled off. A dummy silicon wafer that would become a lens was then bonded via the film-like adhesive s1. This was repeated to obtain a silicon wafer stack having three layers of substrates. Next, heat treatment was performed at 180°C for 1 hour to obtain a wafer stack s1 with a cured film s1 (the first layer of film-like adhesive had a thickness of 125 μm, and the other film-like adhesives had thicknesses of 10 μm) interposed therebetween. This was then diced to obtain a dummy silicon wafer structure s1 that simulated the individual lenses of the structure shown in Figure 1.

[0027] <Example 2 and onwards> From Example 2 onwards, dopes (slips), film adhesives and cured films were prepared in the same manner as Example 1, except that the blending ingredients and thickness of the film adhesive were changed as shown in Tables 1, 2 and 3. The temperature and time for curing the film adhesive (main curing) were 180°C and 1 hour in each example.

[0028] <Measurement method> (Method for measuring the thickness of the cured film) The thickness of the release film was measured with a micrometer and set to 0 μm. Then, the overlapping portion of the release film and the film-like adhesive was measured, and the difference was taken as the thickness of the film-like adhesive. Nine points were measured for each sample, and the average value (arithmetic mean) was taken as the thickness of that sample. The average thickness was calculated for five samples, and this average value (arithmetic mean) was used as the thickness. It was confirmed that there was no significant difference in thickness between the film-like adhesive and the cured film obtained by curing it.

[0029] (Method for measuring water absorption rate) Samples with a thickness of 40 μm or less were laminated with a hand roller at a stage temperature of 90°C to a thickness of 40 μm or more. Samples cut to 50 mm x 50 mm were dried at 180°C for 60 minutes, cooled in a desiccator, and then weighed after drying. They were then immersed in distilled water and removed after 24 hours for weight measurement. The weight after water absorption was measured. The water absorption rate was calculated using the formula: weight difference before and after water absorption / weight after drying x 100. Measurements were performed on five samples, and the average (arithmetic mean) was used as the water absorption rate. Water droplets adhering to the sample surface were wiped off immediately after removal from the distilled water. For detailed experimental procedures, including this, please refer to JIS K7209:2000.

[0030] (Method for measuring transmittance and reflectance) A glass slide was placed on a hot plate heated to 90°C. A film adhesive was applied to the glass slide using a hand roll. After peeling off the release film attached to one side of the film adhesive, it was heated in a dryer at 180°C for 1 hour to form a cured film. A Hitachi U-4100 tester was used to measure the transmittance and total reflectance in the range of 400 nm to 1100 nm from the cured film side. The measured values ​​were the average (arithmetic mean) of the entire range from 400 nm to 1100 nm. Nine measurements were taken for one sample, and the arithmetic mean values ​​were used as the transmittance and reflectance of that sample. Measurements were performed on five samples, and the arithmetic mean values ​​were used.

[0031] (Method for measuring adhesive strength) Adhesive strength (Si:MPa): 260℃ The film-like adhesive with release film obtained in each Example and Comparative Example was first adhered to one side of a dummy silicon wafer (8 inch size, 350 μm thick) using a manual laminator (trade name: FM-114, manufactured by Technovision) at a temperature of 90°C and a pressure of 0.3 MPa. After the release film was peeled off from the film-like adhesive, a dicing tape (trade name: K-13, manufactured by Furukawa Electric Co., Ltd.) and a dicing frame (trade name: DTF2-8-1H001, manufactured by DISCO) were adhered to the side of the film-like adhesive opposite the dummy silicon wafer using the same manual laminator at room temperature and a pressure of 0.3 MPa. Next, using a dicing machine (trade name: DFD-6340, manufactured by DISCO) equipped with a two-axis dicing blade (Z1: NBC-ZH2050 (27HEDD), manufactured by DISCO; Z2: NBC-ZH127F-SE (BC), manufactured by DISCO), dicing was performed from the dummy silicon wafer side to obtain dummy chips with a size of 2 mm x 2 mm. In addition, a dicing tape (trade name: K-13, manufactured by Furukawa Electric Co., Ltd.) and a dicing frame (trade name: DTF2-8-1H001, manufactured by DISCO) were attached to the ground surface of a dummy silicon wafer (8 inch size, 350 μm thick) for use as a base using the same manual laminator at room temperature and a pressure of 0.3 MPa. Next, using a dicing machine (product name: DFD-6340, manufactured by DISCO) equipped with a two-axis dicing blade (Z1: NBC-ZH2050 (27HEDD), manufactured by DISCO / Z2: NBC-ZH127F-SE (BC), manufactured by DISCO), dicing was performed from the dummy silicon wafer side to a size of 12 mm × 12 mm, to obtain a base. Next, the dummy chip with film-like adhesive was picked up from the dicing tape using a die bonder (product name: DB-800, manufactured by Hitachi High-Technologies Corporation), and the film-like adhesive side of the dummy chip with film-like adhesive was thermocompressed to the opposite side of the ground surface of the base (silicon wafer, 12 mm square) under conditions of 120°C, pressure 0.1 MPa (load 400 gf), and time 1.0 second.The film-like adhesive was then thermally cured into a cured film by heating it in a dryer at a temperature of 180°C for 1 hour. The dummy chips with cured film attached to the substrate were measured for shear peel strength (adhesion strength) of the attached chips to the lead frame substrate at 260°C using a universal bond tester (product name: Series 4000PXY, Nordson Advanced Technologies Co., Ltd.) Ten samples were used, and the average value (arithmetic mean) was used.

[0032] (Method for measuring lamination properties) The film-like adhesive with release film obtained in each example and comparative example was first bonded to one side of a dummy silicon wafer (8 inch size, 100 μm thick) at a temperature of 60°C and a pressure of 0.3 MPa using a manual laminator (product name: FM-114, manufactured by Technovision) so that the film-like adhesive was in contact with the wafer. The wafer lamination properties were evaluated based on the following evaluation criteria: In this test, an evaluation rank of "○" is a level required for practical use. - Evaluation Criteria - ◯: The film adhesive is in close contact with the entire dummy silicon wafer. ×: The film adhesive was not able to adhere to the dummy silicon wafer. Or there are areas that are not tightly adhered.

[0033] (Measurement of melt viscosity before curing) A square measuring 5.0 cm long x 5.0 cm wide was cut from the film-like adhesive with release film obtained in each Example and Comparative Example, and the film-like adhesive cut out with the release film peeled off was laminated. This laminate was then laminated with a hand roller on a stage at 90°C to obtain a test piece with a thickness of approximately 1.0 mm. The change in viscous resistance of this test piece was measured using a rheometer (RS6000, manufactured by Haake) over a temperature range of 25 to 250°C at a heating rate of 5°C / min. The melt viscosity (Pa·s) of the film-like adhesive at 70°C before curing was calculated from the obtained temperature-viscous resistance curve. The numerical values ​​in the rows of each component in Tables 1 to 4 indicate the content (parts by mass) of the corresponding component.

[0034] [Table 1]

[0035] [Table 2]

[0036] [Table 3] (Note) Examples 16 and 17 contain epoxy resin in the colorant (see ET6N109).

[0037] [Table 4]

[0038] Examples 1 to 21 contain specific amounts of epoxy resin (A), epoxy resin curing agent (B), polymer component (C), inorganic filler (D), and colorant (E), and when cured into films, they exhibited excellent optical properties, such as low total light transmittance and low total light reflectance. They also exhibited excellent high-temperature adhesive strength and film adhesive lamination. They also exhibited low water absorption, demonstrating favorable properties. In contrast, in Comparative Examples 1 and 2, the epoxy resin and inorganic filler were below the specified amount, and no colorant was included. The amount of curing agent was also below the specified value. As a result, the total light transmittance and total light reflectance showed extremely high values. The water absorption rate was also high. Furthermore, the adhesive strength at 260°C was also low. In Comparative Examples 3 and 4, the amounts of epoxy resin and inorganic filler exceeded the specified amounts, resulting in poor lamination properties of the film adhesive. No inorganic filler was contained in Comparative Examples 5 and 6. As a result, the water absorption rate was high. In Comparative Example 7, the amount of epoxy resin was below the specified amount. Furthermore, an acrylic resin other than phenoxy resin was used as the polymer component. As a result, the adhesive film was found to have poor adhesion. Furthermore, the total light transmittance was somewhat high. In Comparative Example 8, the amount of colorant was less than the specified amount, resulting in a high total light reflectance value.

[0039] From the above results, it can be seen that according to the present invention, it is possible to suppress light transmission and reflection in the cured film obtained by curing the film-like adhesive, and that the film-like adhesive before curing exhibits excellent bonding properties, and further that the cured film exhibits low water absorption and high adhesive strength at high temperatures. [Explanation of symbols]

[0040] 1 lens 2. Image sensor 3 Hardening film 10. Stacked Lenses 11 Side wall 12 Adhesive part

Claims

1. A film-like adhesive comprising an epoxy resin (A), an epoxy resin curing agent (B), a polymer component (C), an inorganic filler (D), and a colorant (E), the polymer component (C) contains a phenoxy resin, the inorganic filler (D) is 70 parts by mass to 720 parts by mass per 100 parts by mass of the polymer component (C); the epoxy resin (A) is 70 parts by mass to 350 parts by mass per 100 parts by mass of the polymer component (C); the epoxy resin curing agent (B) is 1.4 parts by mass or more per 100 parts by mass of the epoxy resin (A), A film-like adhesive in which the colorant (E) is 10 parts by mass or more, based on 100 parts by mass of the total of the epoxy resin (A) and the polymer component (C).

2. 2. The film adhesive according to claim 1, wherein a cured film cured at 120°C to 180°C has a transmittance of less than 10% for light in the range of 400 nm to 1100 nm when the film has a thickness of 10 μm to 125 μm.

3. 2. The film adhesive according to claim 1, wherein a cured film cured at 120°C to 180°C has a reflectance of less than 7% for light in the range of 400 nm to 1100 nm when the film has a thickness of 10 μm to 125 μm.

4. 2. The film adhesive according to claim 1, wherein the thickness is in the range of 5 μm to 150 μm.

5. 2. The film-like adhesive according to claim 1, which has a melt viscosity at 70°C in the range of 6,000 to 65,000 Pa·s when heated from 25°C at a heating rate of 5°C / min.

6. 2. The film adhesive according to claim 1, wherein the colorant (E) contains carbon black.

7. 2. The film-like adhesive according to claim 1, wherein the phenoxy resin is a thermoplastic resin having a molecular weight of 10,000 to 100,000, which is obtained by reacting a bisphenol compound with a glycidyl group-containing compound.

8. 2. The film adhesive according to claim 1, which is used for bonding lenses used in laminated lenses.

9. A laminated lens in which the film adhesive according to any one of claims 1 to 8 is applied to adhere the lens, and a cured film obtained by curing the film adhesive is incorporated so as to adhere at the adhesive portion.

10. a phenoxy resin (C'); 70 to 350 parts by mass of the epoxy resin (A) relative to 100 parts by mass of the phenoxy resin (C'); an epoxy resin curing agent (B) in an amount of 1.4 parts by mass or more per 100 parts by mass of the epoxy resin (A); 70 to 720 parts by mass of the inorganic filler (D) relative to 100 parts by mass of the phenoxy resin (C'); a colorant (E) in an amount of 10 parts by mass or more relative to 100 parts by mass of the total of the epoxy resin (A) and the phenoxy resin (C'); A dope for a film adhesive comprising the above in a solvent.

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