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

Abstract

[Problem] A purpose of the present invention is to provide a film-like adhesive which has low transmittance and reflectance of light when formed into a cured film. Another purpose of the present invention is to provide: 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] Disclosed is a film-like adhesive which 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, and 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).

Description

Film-like adhesive, laminated lens having the cured film thereof, and dope for the film-like adhesive

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

[0002] Film-like 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-like 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 of liquid crystal display devices and self-luminous elements such as organic electroluminescence (EL) devices, as well as for anti-reflection. Specifically, Patent Document 1 discloses a pressure-sensitive adhesive composition containing 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 adhesion strength, and hiding power of this pressure-sensitive adhesive composition at room temperature under a peel angle of 180° were evaluated. Patent Document 2 discloses a pressure-sensitive adhesive composition containing an acrylic polymer blended with benzotriazole, a terpene phenolic resin, an isocyanate crosslinking agent, an epoxy crosslinking agent, and the like, 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.

[0003] Patent No. 6945090 Specification JP 2023-112140 A

[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 properties 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, 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.

[0006] As a result of extensive research conducted by the present 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), wherein the polymer component (C) comprises a phenoxy resin, the inorganic filler (D) is 70 to 720 parts by mass per 100 parts by mass of the polymer component (C), the epoxy resin (A) is 70 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), and the colorant (E) is 10 parts by mass or more per 100 parts by mass of the epoxy resin (A) and the polymer component (C). (2) The film-like 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 400 nm to 1100 nm range at a thickness of 10 μm to 125 μm. (3) The film-like adhesive according to (1) or (2), wherein a cured film cured at 120°C to 180°C has a reflectance of less than 7% for light in the 400 nm to 1,100 nm range at a thickness of 10 μm to 125 μm. (4) The film-like adhesive according to any one of (1) to (3), characterized in that the thickness is in the range of 5 μm to 150 μm. (5) The film-like adhesive according to any one of (1) to (4), wherein the melt viscosity at 70°C is 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-like 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 and a glycidyl group-containing compound. (8) The film 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 for bonding lenses, and a cured film obtained by curing the film adhesive is incorporated so as to bond at the adhesive portion.(10) A dope for a film-like adhesive, comprising in a solvent: a phenoxy resin (C'); an epoxy resin (A) in an amount of 70 to 350 parts by mass 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 relative to 100 parts by mass of the epoxy resin (A); an inorganic filler (D) in an amount of 70 to 720 parts by mass relative to 100 parts by mass of the phenoxy resin (C'); and 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').

[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.

[0009] 1 is a cross-sectional view schematically illustrating an embodiment of the structure of a laminated lens. FIG. 2 is a process explanatory diagram illustrating the preparation and application process of a film adhesive of this embodiment.

[0010] The film 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. 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. The inclusion of an epoxy resin and an inorganic filler in the film-like adhesive of the present invention ensures adhesive strength and adhesive reliability. Furthermore, the inclusion of an epoxy resin curing agent enables thermal curing. The amount of epoxy resin is preferably adjusted to a suitable range, taking into consideration the incorporation of other additives such as curing agents. Specifically, the epoxy resin (A) is present in an amount of 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 or more epoxy resins 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 2,000 or less, more preferably 1,500 or less, and even more preferably 1,000 or less. The lower limit is not particularly limited, but a practical value is 300 or more.

[0012] <Epoxy Resin Curing Agent (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 the epoxy resin curing agent include organic amine-based curing agents and imidazole-based (imidazole cyanide, imidazole hydroxymethyl) curing agents. Examples of the epoxy resin curing agent include those having the following structure: [Chemical Formula 2] (CH ３ O) ３ SiC ３ H ６ NHC ２ H ４ NH ２ (d) 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 more preferably 2 parts by mass or more, of epoxy resin curing agent (B) per 100 parts by mass of epoxy resin (A). There is no particular upper limit, but from the viewpoint of resin component bloom, etc., an excessive amount is not preferable, 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 type of epoxy resin curing agent or two or more types 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. n in the formula 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. By using a phenoxy resin in the film-like adhesive of the present invention, higher adhesive strength can be ensured than with an acrylic resin. Furthermore, by using a phenoxy resin, film properties (handling ease) can be improved. Phenoxy resins are preferably resins that are amorphous and thermoplastic due to an increase in the repeating unit of the polymer. By using a phenoxy resin as the polymer component, high adhesive strength can be ensured. Furthermore, by using a 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 in weight average molecular weight, more preferably 15,000 or more, and even more preferably 20,000 or more. 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, "molecular weight" refers to the weight average molecular weight in terms of polystyrene determined by gel permeation chromatography (GPC). The carrier may be selected appropriately, and examples thereof include THF (tetrahydrofuran).

[0015] <Inorganic Filler (D)> Inorganic fillers 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, with vinylsilane-treated silica being more preferred. The amount of inorganic filler is preferably adjusted to a suitable range, taking into account its advantages and disadvantages. Specifically, the inorganic filler (D) is used in an amount of 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 the inorganic filler contains two or more components, 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 having 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 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 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 defined as the total amount.

[0017] <Solvent> The solvent used in producing the film-like adhesive of the present invention is not particularly limited, and examples thereof 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 thoroughly mixes them, while it is preferable to use an amount that can volatilize during production and be formed into a film.

[0018] <Manufacturing Method and Application Method of Film-Like Adhesive> FIG. 2 is a process diagram illustrating the preparation and application process of the film-like adhesive of this embodiment. The film-like 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-like adhesive. This dope for molding the film-like 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 10 minutes or less is practical. The film-like adhesive in this state has not undergone a curing reaction due to the epoxy groups inside, and can be considered to be in a provisionally cured state. The formed film-like adhesive can be used as is, or it can be further molded into a desired shape using laser processing or other techniques. The molded film-like adhesive cures, for example, at a temperature of 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] <Method for Manufacturing a Laminated Lens> 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 the sidewall 11. In this embodiment, three layers of lenses 1 are laminated. The film-like adhesive is placed at each adhesive joint to form the sidewall 11. In this state, by exposing the semiconductor element to a high temperature (e.g., 150°C), the epoxy resin blended as described above reacts 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 laminated lens 10 with high durability and strength. Note that in this embodiment, the lens before dicing is called a wafer-level lens (wafer-level optical component), but the lens obtained by dicing and dividing 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 lenses is preferably approximately 10 μm thick to provide 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 above preferred thickness ranges also apply to cured films.

[0021] <Characteristics of Film-Like 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-like adhesive has a thickness of 10 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 it does not transmit light at all. Regarding reflectance, 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-like adhesive has a thickness of 10 to 125 μm and a light transmittance of preferably less than 15%, more preferably less than 10%, and even more preferably less than 7% in the range of 400 nm to 1100 nm. There is no particular lower limit, but it is preferable that it does not reflect light at all. By suppressing the light transmittance and light reflectance specified herein, ghosting and flare during development can be suppressed. Flare is a phenomenon in which light leaks into dark areas of a photograph, occurring when strong light is reflected inside a camera or lens. Ghosting is a phenomenon in which light reflected inside a lens appears as a ball or band. The film-like adhesive of the present invention, in the fully cured film state, preferably has an adhesive strength of 5 MPa or more, more preferably 6 MPa or more, and even more preferably 7 MPa or more, at 260°C. There is no particular upper limit, but a practical value is 25 MPa or less. Note that the films in Patent Documents 1 and 2 are designed to be peelable and have weak adhesive strength. Furthermore, heating to 260°C is not assumed, and even if it is deliberately heated to 260°C, it is understood that the viscosity will be too low and the stability of the shape will not be maintained. When the film-like adhesive of the present invention is heated from 25°C at a heating rate of 5°C / min, it preferably has a melt viscosity at 70°C 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 of liquid crystal display devices, a sealant for self-luminous elements such as organic EL, and LiDAR for automobiles.

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

[0024] Example 1 Preparation of a dope for a film-like adhesive 50 parts by mass of the above RE-310S, 20 parts by mass of the above 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 out 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. This prepared dope (sludge) s1 of Example 1.

[0025] (Preparation of film-like 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, thereby obtaining 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] (Curing of film-like adhesive: Main curing) The obtained film-like adhesive s1 with the release sheet attached was processed into the desired shape by laser processing. This was adhered to a dummy silicon wafer that would become an image sensor. At this point, the release sheet was peeled off. Furthermore, a dummy silicon wafer that would become a lens was adhered 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 (first layer film-like adhesive thickness 125 μm, other film-like adhesive thicknesses 10 μm) interposed therebetween. This was then diced to obtain a dummy silicon wafer structure s1 that simulates the individual lenses of the structure shown in FIG. 1.

[0027] <Example 2 and onwards> In Examples 2 and onwards, dopes (slips), film adhesives and cured films were prepared in the same manner as in Example 1, except that the blending components 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) in each Example were 180°C and 1 hour.

[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 the sample. The average thickness was determined for five samples, and the 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) 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. The samples were then immersed in distilled water, removed after 24 hours, and weighed to determine the weight after water absorption. The value calculated from the formula: weight difference before and after water absorption / weight after drying x 100 was used as the water absorption rate. Measurements were performed on five samples, and the average value (arithmetic mean) was used as the water absorption rate. Water droplets adhering to the sample surface were wiped off immediately after the test specimen was removed 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 U-4100 tester (manufactured by Hitachi) 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 of 400 nm to 1100 nm. Nine measurements were made for one sample, and the arithmetic mean values ​​were used as the transmittance and reflectance of that sample. Measurements were made for five samples, and the arithmetic mean values ​​were used.

[0031] (Method for measuring adhesive strength) Adhesive strength (Si: MPa): 260°C 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, thickness 350 μm) using a manual laminator (trade name: FM-114, manufactured by Technovision Co., Ltd.) at a temperature of 90°C and a pressure of 0.3 MPa. Thereafter, the release film was peeled from the film-like adhesive, and then 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 Corporation) were adhered to the surface 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 carried out from the dummy silicon wafer side to a size of 2 mm x 2 mm, to obtain a dummy chip. In addition, a dummy silicon wafer (8 inch size, thickness 350 μm) was used as a base, and 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 the dummy silicon wafer at room temperature and a pressure of 0.3 MPa using the same manual laminator. Next, dicing was performed from the dummy silicon wafer side to a size of 12 mm x 12 mm using a dicing machine (trade name: DFD-6340, manufactured by DISCO Corporation) equipped with a two-axis dicing blade (Z1: NBC-ZH2050 (27HEDD), manufactured by DISCO Corporation / Z2: NBC-ZH127F-SE (BC), manufactured by DISCO Corporation), to obtain a base.Next, the dummy chip with the film-like adhesive was picked up from the dicing tape using a die bonder (trade name: DB-800, manufactured by Hitachi High-Technologies Corporation). The film-like adhesive side of the dummy chip with the film-like adhesive was bonded 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, and then heat-pressed to a temperature of 180 ° C in a dryer for 1 hour to thermally cure the film-like adhesive into a cured film. For the dummy chip with the cured film bonded to the substrate, a universal bond tester (trade name: Series 4000PXY, Nordson Advanced Technologies Co., Ltd.) was used to measure the shear peel strength (adhesion strength) of the bonded chip to the lead frame substrate at 260 ° C. 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 adhered to one side of a dummy silicon wafer (8 inch size, 100 μm thick) using a manual laminator (product name: FM-114, manufactured by Technovision Co., Ltd.) at a temperature of 60°C and a pressure of 0.3 MPa so that the film-like adhesive came into contact with the wafer. Wafer lamination properties were evaluated based on the following evaluation criteria. In this test, an evaluation rank of "○" represents a level required for practical use. - Evaluation criteria - ○: The film-like adhesive is in close contact with the entire dummy silicon wafer. ×: The film-like adhesive is not in close contact with the dummy silicon wafer, or there are areas where it is not in close contact.

[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. For this test piece, the change in viscous resistance was measured using a rheometer (RS6000, manufactured by Haake Co., Ltd.) over a temperature range of 25 to 250°C at a heating rate of 5°C / min. From the obtained temperature-viscous resistance curve, the melt viscosity (Pa s) of the film-like adhesive at 70°C before curing was calculated. Note that the numerical value in the row for each component in Tables 1 to 4 indicates the content (parts by mass) of the corresponding component.

[0034]

[0035]

[0036] (Note) In Examples 16 and 17, epoxy resin is blended into the colorant (see the ET6N109 section).

[0037]

[0038] Examples 1 to 21 contained specific amounts of epoxy resin (A), epoxy resin curing agent (B), polymer component (C), inorganic filler (D), and colorant (E). When cured, the films exhibited excellent optical properties, including low total light transmittance and low total light reflectance. At the same time, the films also exhibited excellent high-temperature adhesive strength and film-like adhesive lamination. They also exhibited low water absorption, demonstrating favorable properties. In contrast, Comparative Examples 1 and 2 contained less than the specified amounts of epoxy resin and inorganic filler, and no colorant was included. Furthermore, the amount of curing agent was also below the specified value. As a result, the films exhibited extremely high values ​​for total light transmittance and total light reflectance. The water absorption rate also increased. 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. As a result, the film-like adhesive exhibited poor lamination. Comparative Examples 5 and 6 did not contain inorganic filler. As a result, the water absorption rate increased. In Comparative Example 7, the amount of epoxy resin was less than the specified amount. In addition, an acrylic resin other than phenoxy resin was used as the polymer component. As a result, it was found that the lamination properties of the film-like adhesive were poor. In addition, the total light transmittance value was somewhat high. In Comparative Example 8, the amount of colorant was less than the specified amount. As a result, the total light reflectance value was high.

[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.

[0040] REFERENCE SIGNS LIST 1 Lens 2 Image sensor 3 Hardened film 10 Laminated lens 11 Side wall 12 Adhesive part

Claims

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), wherein the polymer component (C) contains a phenoxy resin, the inorganic filler (D) is 70 to 720 parts by mass per 100 parts by mass of the polymer component (C), the epoxy resin (A) is 70 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), and the colorant (E) is 10 parts by mass or more per 100 parts by mass of the epoxy resin (A) and the polymer component (C).

2. The film adhesive according to claim 1, wherein the 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 is 10 μm to 125 μm thick.

3. The film adhesive according to claim 1, 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 is 10 μm to 125 μm thick.

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

5. 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. The film adhesive according to claim 1, wherein the colorant (E) includes carbon black.

7. 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. The film adhesive according to claim 1, which is used to bond 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 dope for a film-like adhesive, comprising in a solvent: a phenoxy resin (C'); an epoxy resin (A) in an amount of 70 to 350 parts by mass per 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); an inorganic filler (D) in an amount of 70 to 720 parts by mass per 100 parts by mass of the phenoxy resin (C'); and a colorant (E) in an amount of 10 parts by mass or more per 100 parts by mass of the total of the epoxy resin (A) and the phenoxy resin (C').

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