Method for manufacturing insulating-filled films, insulating-filled composite sheets, and electronic components.

Abstract

The present invention provides an insulating filler film that exhibits excellent filling properties for recesses formed on the surface of a member, and a method for manufacturing an electronic component using the insulating filler film. [Solution] The insulating filler film of the present invention is an insulating filler film used to fill recesses in a member having recesses formed on its surface, wherein the complex viscosity at 80°C is 15,000 Pa·s or less.

Description

Technical Field

[0001] The present invention relates to an insulating filling film, an insulating filling composite sheet, and a method for manufacturing an electronic component.

Background Art

[0002] In recent years, demands for downsizing and higher performance of electronic devices have been increasing, and various technologies have been developed. In such technologies, recesses may be formed on the surface of a member constituting an electronic component for various purposes.

[0003] For example, Patent Document 1 describes that in an Insulated Gate Bipolar Transistor (IGBT), a trench is formed on the wafer surface, and the inside thereof is filled with a trench filling insulating film, whereby the effective drift length is extended and the on-resistance is reduced.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of Invention

Problems to be Solved by the Invention

[0005] Here, in Patent Document 1, the trench filling insulating film is formed by a CVD (Chemical Vapor Deposition) method. However, the CVD method has problems such as requiring a special apparatus or taking a relatively long time for film formation, and there has been a demand for a method capable of forming an insulating portion inside a recess formed on the surface of a member constituting an electronic component more simply and quickly. Therefore, the inventors investigated a method for forming an insulating portion by filling the inside of recesses formed on the surface of a component using a film-like resin composition that is easy to handle and can be easily attached to the surface of a component.

[0006] The present invention aims to provide an insulating filler film having high filling capacity for recesses formed on the surface of a component, an insulating filler composite sheet using the insulating filler film, and a method for manufacturing electronic components. [Means for solving the problem]

[0007] The present invention provides the following [1] to [6]. [1] An insulating filling film used to fill recesses in a member having recesses formed on its surface, An insulating filler film having a complex viscosity of 15,000 Pa·s or less at 80°C. [2] The insulating filler film according to [1], wherein the recess satisfies at least one of the following requirements (I) to (IV). Requirement (I): When the cross-section of the recess is taken along the thickness direction of the member, the cross-section does not reach (i) the outer edge of the surface on which the recess is formed and (ii) the back surface of the surface on which the recess is formed. Requirement (II): The difference between the deepest and shallowest points in the recess is 30 μm or more. Requirement (III): When the recess is viewed from above, at least a portion of it is composed of a curve. Requirement (IV): When the cross-section of the recess is taken along the thickness direction of the member, the aspect ratio of the shape of the cross-section is 3 or greater. [3] The insulating filler film according to [2], wherein the recess satisfies at least requirement (I). [4] Furthermore, the insulating filler film according to any one of [1] to [3], wherein the complex viscosity at 130°C is 50 Pa·s or more. [5] An insulating filling composite sheet comprising a support sheet in addition to the insulating filling film according to any one of claims 1 to 4. [6] A method for manufacturing an electronic component, comprising a step of filling a recess formed on a surface of a member with the insulating filling film according to any one of claims 1 to 4, and a step of heating. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide an insulating filling film having high filling property for recesses formed on the surface of a member, an insulating filling composite sheet using the insulating filling film, and a method for manufacturing an electronic component. [Brief Description of the Drawings]

[0009] [Figure 1] It is a schematic cross-sectional view showing an example of the embodiment of the composite sheet of the present embodiment. [Figure 2] It is a schematic cross-sectional view showing another example of the embodiment of the composite sheet of the present embodiment. [Figure 3] It is a schematic cross-sectional view showing still another example of the embodiment of the composite sheet of the present embodiment. [Figure 4] It is a schematic plan view and a schematic cross-sectional view showing an example of the recess of the present embodiment. [Figure 5] It is a schematic cross-sectional view showing another example of the recess of the present embodiment. [Figure 6] It is a schematic plan view showing still another example of the recess of the present embodiment. [Figure 7] It is a schematic cross-sectional view showing still another example of the recess of the present embodiment. [Figure 8] It is a schematic plan view and a schematic cross-sectional view showing an example of step (S1). [Figure 9] It is a schematic cross-sectional view showing an example of step (S21). [Figure 10] It is a schematic cross-sectional view showing an example of step (S22). [Figure 11] It is a schematic cross-sectional view showing an example of step (S23).

Mode for Carrying Out the Invention

[0010] In the present specification, the weight average molecular weight (Mw) and the number average molecular weight (Mn) are values in terms of standard polystyrene measured by a gel permeation chromatography (GPC) method, and specifically are values measured based on the methods described in Examples.

[0011] In the present specification, for preferred numerical ranges (for example, ranges such as content), the lower limit values and upper limit values described stepwise can be independently combined. For example, from the description of "preferably 10 to 90, more preferably 30 to 60", the "preferred lower limit (10)" and the "more preferred upper limit (60)" can be combined to make "10 to 60".

[0012] In the present specification, "energy ray" means an electromagnetic wave or a charged particle beam that has an energy quantum. Examples of energy rays include ultraviolet rays, radiation, electron beams and the like. Ultraviolet rays can be irradiated using an electrodeless lamp, a high-pressure mercury lamp, a metal halide lamp, a xenon lamp, a black light, an LED lamp or the like. Electron beams can be irradiated with those generated by an electron beam accelerator or the like.

[0013] In the present specification, "energy ray curable" means the property of being cured by irradiation with an energy ray. Further, in the present specification, "thermosetting" means the property of being cured by heating, and "non-curable" means the property of not being cured by heating, energy ray irradiation, or the like.

[0014] In the present specification, for example, "(meth)acrylic acid" indicates both "acrylic acid" and "methacrylic acid", and the same applies to other similar terms.

[0015] In this specification, "protruding electrode" refers to a protruding electrode of a shape commonly used on the circuit formation surface of semiconductor wafers, semiconductor chips, etc., such as ball bumps and pillar electrodes.

[0016] In this specification, the "thickness" of an object means the total thickness of the object as a whole. For example, if the object consists of multiple layers, it means the total thickness of all the layers that make up the object. In this specification, unless otherwise specified, the "thickness" of an object refers to the average value of the thickness measured at five randomly selected locations on the object, and can be obtained using a constant-pressure thickness measuring instrument in accordance with JIS K 7130:1999.

[0017] In this specification, "solid content" or "active ingredient" refers to the components of the composition in question, excluding diluting solvents such as water and organic solvents.

[0018] In this specification, "filling" preferably means that the insulating filling film occupies 100% of the volume of the recess, but it is also permissible for there to be bubbles or voids of less than 4.5% of the volume of the recess.

[0019] In this specification, "insulation" means electrical insulation unless otherwise specified.

[0020] In this specification, "plan view" means viewing the member of this embodiment in a planar direction from the side having the recess (surface side).

[0021] The mechanism of action described herein is speculative and does not limit the mechanism by which the present invention achieves its effects.

[0022] In order to make the features of the present invention easier to understand, the drawings may show enlarged versions of key parts for convenience, and the dimensional ratios of each component may not be the same as in reality.

[0023] [Insulating Filling Film of the Present Embodiment] The insulating filler film of this embodiment is an insulating filler film used to fill recesses in a member having recesses formed on its surface, and has a complex viscosity of 15,000 Pa·s or less at 80°C. The inventors of the present invention conducted diligent research to solve the above problems. As a result, they found that the above problems can be solved by adjusting the complex viscosity of the insulating filler film used to fill the recesses of a member having recesses on its surface to a specific range at 80°C. In other words, by adjusting the complex viscosity of the insulating filler film at 80°C to a specific range, the flexibility of the material is improved when heated, making it easier for the insulating filler film to fill the recesses. As a result, it was found that the film has high filling capacity into the recesses without leaving any air inside.

[0024] <Structure of insulating filler film> The insulating filler film is used to fill recesses in a member having recesses formed on its surface. The insulating filler film has a complex viscosity of 15,000 Pa·s or less at 80°C, and possesses viscosity suitable for filling recesses. Therefore, when the insulating filler film is applied to the surface of a component with recesses and heated and pressurized, the insulating filler film easily penetrates the recesses, making it possible to form insulating areas without leaving air trapped within the recesses.

[0025] The insulating filler film may consist of only one layer or two or more layers. If the insulating filler film consists of multiple layers, these layers may be identical or different, and there are no particular limitations on the combination of these layers.

[0026] The thickness of the insulating filler film is adjusted as appropriate, taking into consideration the thickness of the insulating filler portion formed by curing the insulating filler film, the number and depth of recesses on the surface of the component, or the number and height of protrusions. The thickness of the insulating filler film is preferably 5 to 70 μm, more preferably 10 to 60 μm, and even more preferably 20 to 50 μm. When the thickness of the insulating filler film is greater than or equal to the lower limit mentioned above, it is easier to produce a film with high in-plane uniformity. Conversely, when the thickness of the insulating filler film is less than or equal to the upper limit mentioned above, it is prevented from becoming excessively thick.

[0027] (Complex viscosity of insulating filler film) The insulating filler film of this embodiment has a complex viscosity of 15,000 Pa·s or less at 80°C. As mentioned above, the fact that the complex viscosity of the insulating filler film at 80°C is within an appropriate range (15,000 Pa·s or less) makes it easier for the insulating filler film to penetrate into the recesses of the material.

[0028] From the viewpoint of improving the filling ability of the insulating filler film into recesses, the upper limit of the complex viscosity at 80°C is preferably 15,000 Pa·s or less, more preferably 13,500 Pa·s or less, even more preferably 12,000 Pa·s or less, even more preferably 10,500 Pa·s or less, even more preferably 10,000 Pa·s or less, even more preferably 8,000 Pa·s or less, even more preferably 6,000 Pa·s or less, even more preferably 4,000 Pa·s or less, and even more preferably 2,000 Pa·s or less. Furthermore, the lower limit of the complex viscosity at 80°C is preferably 100 Pa·s or higher, more preferably 200 Pa·s or higher, even more preferably 300 Pa·s or higher, even more preferably 400 Pa·s or higher, and still more preferably 500 Pa·s or higher, from the viewpoint of suppressing excessive fluidity and contamination of the table during application. In other words, the insulating filler film of this embodiment has a complex viscosity at 80°C that is preferably 100 to 15,000 Pa·s, more preferably 200 to 13,500 Pa·s, even more preferably 300 Pa·s to 12,000 Pa·s, even more preferably 400 to 10,500 Pa·s, still more preferably 500 to 10,000 Pa·s, even more preferably 500 to 8,000 Pa·s, even more preferably 500 to 6,000 Pa·s, even more preferably 500 to 4,000 Pa·s, and even more preferably 500 to 2,000 Pa·s.

[0029] Furthermore, if the complex viscosity of the insulating filler film at 130°C is within an appropriate range (50 Pa·s or higher), it becomes easier to prevent the insulating filler film from repelling during application. From the viewpoint of making it easier to prevent the insulating filler film from repelling when it is applied, the lower limit of the complex viscosity of the insulating filler film at 130°C is preferably 50 Pa·s or more, more preferably 100 Pa·s or more, even more preferably 200 Pa·s or more, and even more preferably 400 Pa·s or more. Furthermore, from the viewpoint of facilitating the processing of the insulating-filled portion formed by curing the insulating-filled film, the upper limit of the complex viscosity of the insulating-filled film at 130°C is preferably 25,000 Pa·s or less, more preferably 20,000 Pa·s or less, even more preferably 15,000 Pa·s or less, and even more preferably 12,000 Pa·s or less. In other words, the insulating filler film of this embodiment has a complex viscosity at 130°C that is preferably 50 to 25,000 Pa·s, more preferably 100 to 20,000 Pa·s, even more preferably 200 Pa·s to 15,000 Pa·s, and even more preferably 400 to 12,000 Pa·s.

[0030] Furthermore, the complex viscosity of an insulating filler film can be easily adjusted by adjusting one or both of the types and content of the components contained in the insulating filler film. To do this, one or both of the types and content of the components contained in the composition for forming the insulating filler film should be adjusted. For example, the complex viscosity of an insulating filler film can be easily adjusted by adjusting one or both of the types and content of the main components, such as polymer components (A) and fillers (D), and by adjusting one or both of the types and content of one or more additives (G) selected from rheology control agents, surfactants, and silicone oils. For example, increasing the content of one or both of the filler (D) and additive (G) in the insulating filler film makes it easier to adjust the complex viscosity of the insulating filler film to a larger value, and as a result, it becomes easier to adjust the complex viscosity to an appropriate value.

[0031] In this embodiment, the complex viscosity of the insulating filler film can be measured specifically by the dynamic viscoelasticity measurement described in the examples below.

[0032] <Composition of insulating filler film>

[0033] The insulating filler film of this embodiment contains a polymer component (A) and a thermosetting component (B). The insulating filler film is formed, for example, from a thermosetting resin composition (x1) containing a polymer component (A) and a thermosetting component (B). Polymeric component (A) is a component that can be considered to have been formed by a polymerization reaction of polymerizable compounds. Thermosetting component (B) is a component that can undergo a curing (polymerization) reaction triggered by heat. This curing (polymerization) reaction includes polycondensation reactions.

[0034] (Polymer component (A)) The insulating filler film and thermosetting resin composition (x1) of this embodiment contain a polymer component (A). Polymer component (A) is a polymer compound used to impart film-forming properties, flexibility, and other characteristics to the insulating filler film. Polymer component (A) may be used alone or in combination of two or more types. When using two or more types of polymer component (A) in combination, the combination and ratio can be arbitrarily selected.

[0035] Examples of polymer components (A) include acrylic resins, polyarylate resins, acetal resins, polyesters, urethane resins (resins having urethane bonds), acrylic urethane resins, silicone resins (resins having siloxane bonds), rubber resins (resins having a rubber structure), phenoxy resins, and thermosetting polyimides. Among these, acrylic resins, polyarylate resins, and acetal resins are preferred, with acetal resins being more preferred.

[0036] Examples of acrylic resins include well-known acrylic polymers. The weight-average molecular weight (Mw) of the acrylic resin is preferably 10,000 to 2,000,000, more preferably 300,000 to 1,500,000, and even more preferably 500,000 to 1,000,000. Having a weight-average molecular weight of acrylic resin above the lower limit mentioned above makes it easier to improve the shape stability (stable over time during storage) of the insulating filler film. Furthermore, having a weight-average molecular weight of acrylic resin below the upper limit makes it easier for the insulating filler film to conform to the uneven surface of the component, thus suppressing the formation of voids between the component and the insulating filler film. Therefore, it is also easier to improve the ability to fill depressions formed on the surface of the component.

[0037] The glass transition temperature (Tg) of the acrylic resin is preferably -60 to 70°C, more preferably -40 to 50°C, and even more preferably -30 to 30°C, from the viewpoint of the adhesiveness and handling properties of the insulating filler film.

[0038] Examples of acrylic resins include polymers of one or more (meth)acrylic acid esters; copolymers of two or more monomers selected from (meth)acrylic acid, itaconic acid, vinyl acetate, acrylonitrile, styrene, and N-methylolacrylamide, etc.

[0039] Examples of (meth)acrylic acid esters that constitute acrylic resins include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, sec-butyl (meth)acrylate, tert-butyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, n-octyl (meth)acrylate, n-nonyl (meth)acrylate, and (meth) Alkyl methacrylates such as isononyl acrylate, decyl (meth)acrylate, undecyl (meth)acrylate, dodecyl ((meth)acrylate) (lauryl (meth)acrylate), tridecyl (meth)acrylate, tetradecyl ((meth)acrylate) (myristyl (meth)acrylate), pentadecyl (meth)acrylate, hexadecyl ((meth)acrylate) (palmityl (meth)acrylate), heptadecyl (meth)acrylate, and octadecyl ((meth)acrylate) (stearyl (meth)acrylate), in which the alkyl group constituting the alkyl ester has a chain structure with 1 to 18 carbon atoms; Cycloalkyl esters of (meth)acrylates, such as isobornyl (meth)acrylate and dicyclopentanyl (meth)acrylate; (meth)acrylate aralkyl esters such as benzyl (meth)acrylate; (meth)acrylate dicyclopentenyl ester and other cycloalkenyl (meth)acrylates; (meth)acrylate cycloalkenyloxyalkyl esters such as (meth)acrylate dicyclopentenyloxyethyl ester; (meth)acrylimide; Glycidyl group-containing (meth)acrylic acid esters such as glycidyl (meth)acrylate; Hydroxymethyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate, and other hydroxyl group-containing (meth)acrylate esters; Examples include (meth)acrylic acid esters containing substituted amino groups, such as N-methylaminoethyl (meth)acrylate. In this specification, "substituted amino group" means a group in which one or two hydrogen atoms of an amino group are replaced by a group other than a hydrogen atom. Among these, from the viewpoint of film-forming properties of the insulating filler film and the adherence of the insulating filler film to the surface of the material, it is preferable that the alkyl group constituting the alkyl ester is a copolymer of (meth)acrylate alkyl ester having a chain structure with 1 to 18 carbon atoms, glycidyl group-containing (meth)acrylate ester, and hydroxyl group-containing (meth)acrylate ester. It is more preferable that the alkyl group constituting the alkyl ester is a copolymer of (meth)acrylate alkyl ester having a chain structure with 1 to 4 carbon atoms, glycidyl group-containing (meth)acrylate ester, and hydroxyl group-containing (meth)acrylate ester. It is even more preferable that it is a copolymer of butyl acrylate, methyl acrylate, glycidyl acrylate, and 2-hydroxyethyl acrylate.

[0040] The acrylic resin may be obtained by copolymerizing one or more monomers selected from, for example, (meth)acrylic acid ester, (meth)acrylic acid, itaconic acid, vinyl acetate, acrylonitrile, styrene, and N-methylolacrylamide, in addition to (meth)acrylic acid ester.

[0041] The monomers that make up the acrylic resin may be used individually or in combination of two or more. When the monomers that make up the acrylic resin are two or more, their combination and ratio can be arbitrarily selected.

[0042] Examples of polyarylate resins in polymer component (A) include known resins, such as those whose basic structure is the polycondensation of a divalent phenol with a dibasic acid such as phthalic acid or a carboxylic acid. Among these, polycondensates of bisphenol A and phthalic acid, poly-4,4'-isopropylidenediphenylene terephthalate / isophthalate copolymers, and their derivatives are preferred.

[0043] Examples of the acetal resin in polymer component (A) include those that are well known. Among these, preferred acetal resins include, for example, polyvinyl formal and polyvinyl butyral, with polyvinyl butyral being the most preferred. Examples of polyvinyl butyral include those having constituent units represented by the following formulas (i)-1, (i)-2, and (i)-3.

[0044] [ka]

[0045] (In the formula, l, m, and n are each an independent integer greater than or equal to 1.)

[0046] The weight-average molecular weight (Mw) of the polyvinyl acetal resin (preferably polyvinyl butyral) is preferably 5,000 to 200,000, and more preferably 8,000 to 100,000. Having a weight-average molecular weight of the polyvinyl acetal resin (preferably polyvinyl butyral) above the lower limit makes it easier to improve the shape stability (stable over time during storage) of the insulating filler film. Furthermore, having a weight-average molecular weight of the polyvinyl acetal resin (preferably polyvinyl butyral) below the upper limit makes it easier for the insulating filler film to conform to the uneven surface of the component, for example, making it easier to suppress the generation of voids between the component and the insulating filler film. Therefore, it is also easier to improve the ability to fill depressions formed on the surface of the component.

[0047] The glass transition temperature (Tg) of polyvinyl acetal resin (preferably polyvinyl butyral) is preferably 40 to 80°C, and more preferably 50 to 70°C, from the viewpoint of film-forming properties of insulating filler films.

[0048] The ratio of three or more monomers that make up the polyvinyl acetal resin (preferably polyvinyl butyral) can be arbitrarily selected.

[0049] In the insulating filler film and thermosetting resin composition (x1), the content of polymer component (A) is preferably 2 to 30% by mass, more preferably 3 to 25% by mass, and even more preferably 3 to 15% by mass, based on the total amount of active ingredients.

[0050] Polymer component (A) may also correspond to thermosetting component (B). In this embodiment, if the insulating filler film and thermosetting resin composition (x1) contain components that correspond to both polymer component (A) and thermosetting component (B), the insulating filler film and thermosetting resin composition (x1) are considered to contain both polymer component (A) and thermosetting component (B).

[0051] (Thermosetting component (B)) The insulating filler film and thermosetting resin composition (x1) contain a thermosetting component (B). Thermosetting component (B) is a component that hardens the insulating filler film to form a hard, cured resin film. The thermosetting component (B) may be used alone or in combination of two or more types. If there are two or more types of thermosetting component (B), their combination and ratio can be arbitrarily selected.

[0052] Examples of thermosetting component (B) include epoxy thermosetting resins, thermosetting polyimides, polyurethanes, unsaturated polyesters, and silicone resins. Among these, epoxy thermosetting resins are preferred. When thermosetting component (B) is an epoxy thermosetting resin, the protective properties of the insulation filling area are enhanced, and warping of the insulation filling area can be suppressed.

[0053] Epoxy thermosetting resins consist of an epoxy resin (B1) and a thermosetting agent (B2). Epoxy thermosetting resins may be used individually or in combination of two or more types. When two or more epoxy thermosetting resins are used, their combination and ratio can be arbitrarily selected.

[0054] -Epoxy resin (B1)- The epoxy resin (B1) is not particularly limited, but from the viewpoint of making it easier to exhibit the effects of the present invention, it is preferable to use a combination of an epoxy resin that is solid at room temperature (hereinafter also referred to as a solid epoxy resin) and an epoxy resin that is liquid at room temperature (hereinafter also referred to as a liquid epoxy resin). In this specification, "room temperature" refers to 5 to 35°C, preferably 15 to 25°C.

[0055] The liquid epoxy resin is not particularly limited as long as it is liquid at room temperature. Examples include bisphenol A type epoxy resin, bisphenol F type epoxy resin, novolac type epoxy resin, glycidyl ester type epoxy resin, biphenyl type epoxy resin, and phenylene skeleton type epoxy resin. Among these, bisphenol A type epoxy resin is preferred. Liquid epoxy resin may be used alone or in combination of two or more types. When two or more types of liquid epoxy resin are used, their combination and ratio can be arbitrarily selected.

[0056] The epoxy equivalent of the liquid epoxy resin is preferably 200 to 600 g / eq, more preferably 250 to 550 g / eq, and even more preferably 300 to 500 g / eq. The epoxy equivalent in this embodiment can be measured in accordance with JIS K 7236:2009.

[0057] The solid epoxy resin is not particularly limited as long as it is solid at room temperature. Examples include biphenyl-type epoxy resin, bisphenol A-type epoxy resin, bisphenol F-type epoxy resin, orthocresol novolac epoxy resin, dicyclopentadiene-type epoxy resin, naphthalene-type epoxy resin, anthracene-type epoxy resin, and fluorene-based epoxy resin. Among these, naphthalene-type epoxy resin, dicyclopentadiene-type epoxy resin, and fluorene-based epoxy resin are preferred, with dicyclopentadiene-type epoxy resin being more preferred. Solid epoxy resins may be used individually or in combination of two or more types. If two or more types of solid epoxy resins are used, their combination and ratio can be arbitrarily selected.

[0058] The epoxy equivalent of the solid epoxy resin is preferably 150 to 450 g / eq, and more preferably 150 to 400 g / eq.

[0059] The ratio of liquid epoxy resin (xe) to solid epoxy resin (ye) [(xe) / (ye)] is preferably 0.01 to 10.0 by mass, more preferably 0.02 to 8.0, and even more preferably 0.03 to 6.0. When the above ratio [(xe) / (ye)] is within the above range, it is possible to suppress the generation of cutting chips and the like when processing the insulation filling area after curing, thereby improving processability.

[0060] The number-average molecular weight of the epoxy resin (B1) is not particularly limited, but from the viewpoint of the curability of the insulating filler film and the strength and heat resistance of the insulating filler portion after curing, it is preferably 300 to 30,000, more preferably 400 to 10,000, and even more preferably 500 to 3,000.

[0061] -Thermosetting agent (B2)- The thermosetting agent (B2) functions as a curing agent for the epoxy resin (B1). Examples of the thermosetting agent (B2) include compounds having two or more functional groups capable of reacting with epoxy groups in one molecule. Examples of the above functional groups include phenolic hydroxyl groups, alcoholic hydroxyl groups, amino groups, carboxyl groups, and groups in which an acid group has been converted into an anhydride. It is preferable that the functional group is a phenolic hydroxyl group, an amino group, or a group in which an acid group has been converted into an anhydride, and it is more preferable that the functional group is a phenolic hydroxyl group or an amino group.

[0062] Examples of thermosetting agents (B2) that include phenolic curing agents having phenolic hydroxyl groups include polyfunctional phenolic resins, biphenols, novolac-type phenolic resins, dicyclopentadiene-based phenolic resins, and aralkylphenolic resins. Among the thermosetting agents (B2), examples of amine-based curing agents having an amino group include dicyandiamide (hereinafter sometimes abbreviated as "DICY"). Among these, phenolic curing agents having phenolic hydroxyl groups are preferred, and novolac-type phenolic resins are more preferred.

[0063] Among the thermosetting agents (B2), the number average molecular weight of the resin components, such as polyfunctional phenolic resins, novolac-type phenolic resins, dicyclopentadiene-based phenolic resins, and aralkylphenolic resins, is preferably 300 to 30,000, more preferably 400 to 10,000, and even more preferably 500 to 3,000. The molecular weight of the non-resin component of the thermosetting agent (B2), such as biphenol or dicyandiamide, is not particularly limited, but is preferably 60 to 500.

[0064] The thermosetting agent (B2) may be used alone or in combination of two or more types. If there are two or more types of thermosetting agent (B2), their combination and ratio can be arbitrarily selected.

[0065] In the insulating filler film and thermosetting resin composition (x1), the content of the thermosetting agent (B2) is preferably 0.010 to 200 parts by mass, more preferably 0.020 to 150 parts by mass, even more preferably 0.050 to 100 parts by mass, and even more preferably 0.10 to 77 parts by mass, based on the content of 100 parts by mass of epoxy resin (B1). When the content of the thermosetting agent (B2) is above the lower limit, the curing of the insulating filler film proceeds more easily. Furthermore, when the content of the thermosetting agent (B2) is below the upper limit, the moisture absorption rate of the insulating filler film is reduced, and the reliability of electronic components and the like obtained using the insulating filler film is further improved.

[0066] In the insulating filler film and thermosetting resin composition (x1), the content of the thermosetting component (B) (total content of epoxy resin (B1) and thermosetting agent (B2)) is preferably 200 to 10,000 parts by mass, more preferably 300 to 5,000 parts by mass, and even more preferably 400 to 1,000 parts by mass, per 100 parts by mass of the polymer component (A), from the viewpoint of enhancing the protectiveness of the insulating filler portion.

[0067] -Curing accelerator (C)- The insulating filler film and the thermosetting resin composition (x1) may contain a curing accelerator (C). The curing accelerator (C) is an ingredient used to adjust the curing speed of the insulating filler film. Preferred curing accelerators (C) include, for example, tertiary amines such as triethylenediamine, benzyldimethylamine, triethanolamine, dimethylaminoethanol, and tris(dimethylaminomethyl)phenol; imidazoles such as 2-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 2-phenyl-4,5-dihydroxymethylimidazole, and 2-phenyl-4-methyl-5-hydroxymethylimidazole (imidazoles in which one or more hydrogen atoms are substituted with groups other than hydrogen atoms); organophosphines such as tributylphosphine, diphenylphosphine, and triphenylphosphine (phosphines in which one or more hydrogen atoms are substituted with organic groups); and tetraphenylboron salts such as tetraphenylphosphonium tetraphenylborate and triphenylphosphine tetraphenylborate. Among these, imidazoles are preferred, and 2-phenyl-4,5-dihydroxymethylimidazole is more preferred, from the viewpoint of making it easier to exhibit the effects of the present invention.

[0068] The curing accelerator (C) may be used alone or in combination of two or more types. If there are two or more types of curing accelerator (C), their combination and ratio can be arbitrarily selected.

[0069] In the insulating filler film and thermosetting resin composition (x1), when a curing accelerator (C) is used, the content of the curing accelerator (C) is preferably 0.001 to 10 parts by mass, and more preferably 0.01 to 5 parts by mass, per 100 parts by mass of the content of the thermosetting component (B). When the content of the curing accelerator (C) is above the lower limit, the effects of using the curing accelerator (C) are more easily obtained. Furthermore, when the content of the curing accelerator (C) is below the upper limit, for example, the effect of suppressing the migration and segregation of highly polar curing accelerators (C) to the adhesive interface side with the component in the insulating filler film under high temperature and high humidity conditions is enhanced, and the reliability of electronic components etc. obtained using the insulating filler film is further improved.

[0070] -Filling material (D)- The insulating filler film and the thermosetting resin composition (x1) may contain a filler (D). By including filler (D) and satisfying the above parameters, it is possible to improve the chipping suppression of the insulating filled portion obtained by curing the insulating filled film. Furthermore, by including the filler (D), it becomes easier to adjust the thermal expansion coefficient of the insulating filled portion obtained by curing the insulating filled film to an appropriate range, thereby further improving the reliability of electronic components and the like obtained using the insulating filled film. In addition, by including the filler (D) in the insulating filled film, it is also possible to reduce the moisture absorption rate of the insulating filled portion, improve heat dissipation, and improve electrical insulation.

[0071] The filler (D) may be either an organic filler or an inorganic filler, but it is preferably an inorganic filler or an organic / inorganic hybrid filler. Preferred inorganic fillers include, for example, powders such as silica, talc, calcium carbonate, and boron nitride; beads formed from these inorganic fillers in a spherical shape; surface modified products of these inorganic fillers; single crystal fibers of these inorganic fillers; and glass fibers. Preferred organic / inorganic hybrid fillers include, for example, component-mixed fillers such as silica-acrylic composite particles (e.g., Soliostar manufactured by Nippon Shokubai); and composite fillers incorporating inorganic fine particles with organic materials. Among these, inorganic fillers are preferred, and among inorganic fillers, silica is preferred.

[0072] The filler (D) may be used alone or in combination of two or more types. If there are two or more types of filler (D), their combination and ratio can be selected arbitrarily.

[0073] In the insulating filler film and thermosetting resin composition (x1), when a filler (D) is used, the content of the filler (D) is preferably 5 to 50% by mass, more preferably 7 to 45% by mass, even more preferably 10 to 40% by mass, even more preferably 12 to 35% by mass, and still more preferably 15 to 25% by mass, based on the total amount of the active ingredient, from the viewpoint of adjusting the complex viscosity of the insulating filler film to an appropriate range and suppressing the peeling of the cured resin film from the chip due to thermal expansion and contraction.

[0074] The average particle size of the filler (D) is preferably 500 nm or less, more preferably 5 to 300 nm, and particularly preferably 10 to 100 nm. In this specification, the particle size of the filler (D) refers to the arithmetic mean particle size obtained by randomly selecting and measuring the particle sizes of multiple primary particles of the filler (D) observed with an electron microscope, and then calculating the average value of these measurements.

[0075] -Energy ray curable resin (E)- The insulating filler film and thermosetting resin composition (x1) may contain an energy ray curable resin (E). The insulating filler film contains an energy-ray curable resin (E), allowing its properties to be altered by irradiation with energy rays.

[0076] Energy-ray curable resin (E) is obtained by polymerizing (curing) an energy-ray curable compound. Examples of energy-ray curable compounds include a polymer (e1) having energy-ray curable groups and a weight-average molecular weight of 80,000 to 2,000,000, and a compound (e2) having energy-ray curable groups and a molecular weight of 100 to 80,000. The polymer (e1) may be at least partially crosslinked with a crosslinking agent, or it may not be crosslinked.

[0077] (A polymer (e1) having energy-ray curable groups and a weight-average molecular weight of 80,000 to 2,000,000) Examples of polymers (e1) having energy ray curable groups and a weight-average molecular weight of 80,000 to 2,000,000 include acrylic resins (e1-1) formed by an addition reaction between an acrylic polymer (e11) having a functional group that can react with a group of another compound, and an energy ray curable compound (e12) having a group that reacts with the functional group and an energy ray curable group such as an energy ray curable double bond.

[0078] Examples of functional groups that can react with groups of other compounds include hydroxyl groups, carboxyl groups, amino groups, substituted amino groups (groups in which one or two hydrogen atoms of an amino group are replaced by a group other than a hydrogen atom), and epoxy groups. However, in terms of preventing corrosion of circuits such as semiconductor wafers and semiconductor chips, it is preferable that the functional group is a group other than a carboxyl group. Among these, the functional group is preferably a hydroxyl group.

[0079] • Acrylic polymer having functional groups (e11) Examples of the acrylic polymer (e11) having the functional group include those obtained by copolymerizing an acrylic monomer having the functional group with an acrylic monomer not having the functional group, and those obtained by copolymerizing monomers other than acrylic monomers (non-acrylic monomers) in addition to these monomers. Furthermore, the acrylic polymer (e11) may be a random copolymer or a block copolymer.

[0080] Examples of acrylic monomers having the aforementioned functional groups include hydroxyl group-containing monomers, carboxyl group-containing monomers, amino group-containing monomers, substituted amino group-containing monomers, epoxy group-containing monomers, and the like.

[0081] Examples of the hydroxyl group-containing monomers include hydroxyalkyl (meth)acrylates such as hydroxymethyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate; and non-(meth)acrylic unsaturated alcohols such as vinyl alcohol and allyl alcohol (unsaturated alcohols that do not have a (meth)acryloyl skeleton).

[0082] Examples of the carboxyl group-containing monomers include ethylenically unsaturated monocarboxylic acids (monocarboxylic acids having an ethylenically unsaturated bond) such as (meth)acrylic acid and crotonic acid; ethylenically unsaturated dicarboxylic acids (dicarboxylic acids having an ethylenically unsaturated bond) such as fumaric acid, itaconic acid, maleic acid, and citraconic acid; anhydrides of the ethylenically unsaturated dicarboxylic acids; and carboxyalkyl esters of (meth)acrylic acid such as 2-carboxyethyl methacrylate.

[0083] The acrylic monomer having the aforementioned functional group is preferably a hydroxyl group-containing monomer or a carboxyl group-containing monomer, and more preferably a hydroxyl group-containing monomer.

[0084] The acrylic polymer (e11) may consist of only one acrylic monomer having the functional group, or two or more monomers. If there are two or more monomers, their combination and ratio can be arbitrarily selected.

[0085] Examples of acrylic monomers that do not have the aforementioned functional groups include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, sec-butyl (meth)acrylate, tert-butyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, n-octyl (meth)acrylate, n-nonyl (meth)acrylate, and methyl (meth)acrylate. Examples of alkyl esters include isononyl, decyl (meth)acrylate, undecyl (meth)acrylate, dodecyl ((meth)acrylate) (lauryl (meth)acrylate), tridecyl (meth)acrylate, tetradecyl ((meth)acrylate) (myristyl (meth)acrylate), pentadecyl (meth)acrylate, hexadecyl ((meth)acrylate) (palmityl (meth)acrylate), heptadecyl (meth)acrylate, octadecyl ((meth)acrylate) (stearyl (meth)acrylate), etc., in which the alkyl group constituting the alkyl ester has a chain structure with 1 to 18 carbon atoms.

[0086] Furthermore, examples of acrylic monomers that do not have the aforementioned functional groups include alkoxyalkyl group-containing (meth)acrylic acid esters such as methoxymethyl (meth)acrylate, methoxyethyl (meth)acrylate, ethoxymethyl (meth)acrylate, and ethoxyethyl (meth)acrylate; aromatic group-containing (meth)acrylic acid esters such as aryl (meth)acrylate such as phenyl (meth)acrylate; non-crosslinked (meth)acrylamide and its derivatives; and non-crosslinked (meth)acrylic acid esters having a tertiary amino group such as N,N-dimethylaminoethyl (meth)acrylate and N,N-dimethylaminopropyl (meth)acrylate.

[0087] The acrylic polymer (e11) may consist of only one acrylic monomer that does not have the functional group, or it may consist of two or more monomers. If there are two or more monomers, their combination and ratio can be arbitrarily selected.

[0088] Examples of the non-acrylic monomers include olefins such as ethylene and norbornene; vinyl acetate; and styrene. The non-acrylic monomers constituting the acrylic polymer (e11) may consist of only one type or two or more types, and if there are two or more types, their combination and ratio can be arbitrarily selected.

[0089] In the acrylic polymer (e11), the ratio (content) of the amount of constituent units derived from the functional group-containing acrylic monomer to the total amount of constituent units is preferably 0.1 to 50% by mass, more preferably 1 to 40% by mass, and particularly preferably 3 to 30% by mass. Having this ratio within this range allows the content of energy-ray-curable groups in the acrylic resin (e1-1) obtained by copolymerization of the acrylic polymer (e11) and the energy-ray-curable compound (e12) to easily adjust the degree of curing of the protective film within a preferred range.

[0090] The acrylic polymer (e11) constituting the acrylic resin (e1-1) may consist of only one type or two or more types, and if there are two or more types, their combination and ratio can be arbitrarily selected.

[0091] In the energy-ray curable resin (E), the content of the acrylic resin (e1-1) is preferably 1 to 40% by mass, more preferably 2 to 30% by mass, and particularly preferably 3 to 20% by mass.

[0092] • Energy ray curable compound (e12) The energy ray curable compound (e12) preferably has one or more groups selected from the group consisting of isocyanate groups, epoxy groups, and carboxyl groups as groups that can react with the functional groups of the acrylic polymer (e11), and more preferably has an isocyanate group as such. For example, if the energy ray curable compound (e12) has an isocyanate group as such, this isocyanate group readily reacts with the hydroxyl group of the acrylic polymer (e11) having a hydroxyl group as such as a functional group.

[0093] The energy ray curable compound (e12) preferably has 1 to 5 energy ray curable groups per molecule, and more preferably 1 to 2.

[0094] Examples of the energy-ray curable compound (e12) include 2-methacryloyloxyethyl isocyanate, meta-isopropenyl-α,α-dimethylbenzyl isocyanate, methacryloyl isocyanate, allyl isocyanate, and 1,1-(bisacryloyloxymethyl)ethyl isocyanate; Acryloyl monoisocyanate compounds obtained by the reaction of a diisocyanate compound or polyisocyanate compound with hydroxyethyl (meth)acrylate; Examples include acryloyl monoisocyanate compounds obtained by the reaction of a diisocyanate compound or polyisocyanate compound with a polyol compound and hydroxyethyl (meth)acrylate. Among these, the energy ray curable compound (e12) is preferably 2-methacryloyloxyethyl isocyanate.

[0095] The energy ray curable compound (e12) constituting the acrylic resin (e1-1) may consist of only one type or two or more types, and if there are two or more types, their combination and ratio can be arbitrarily selected.

[0096] In the acrylic resin (e1-1), the ratio of the content of energy-ray-curable groups derived from the energy-ray-curable compound (e12) to the content of the functional groups derived from the acrylic polymer (e11) is preferably 20 to 120 mol%, more preferably 35 to 100 mol%, and particularly preferably 50 to 100 mol%. Having the content within this range increases the adhesive strength of the protective film after curing. Note that if the energy-ray-curable compound (e12) is a monofunctional compound (having one of the groups in one molecule), the upper limit of the content ratio is 100 mol%, but if the energy-ray-curable compound (e12) is a polyfunctional compound (having two or more of the groups in one molecule), the upper limit of the content ratio may exceed 100 mol%.

[0097] The weight-average molecular weight (Mw) of the polymer (e1) is preferably 100,000 to 2,000,000, and more preferably 300,000 to 1,500,000. Here, "weight-average molecular weight" is as explained earlier.

[0098] If the polymer (e1) is crosslinked with a crosslinking agent in at least a portion thereof, the polymer (e1) may be a monomer that does not fall under any of the above-described monomers that constitute the acrylic polymer (e11) and has a group that reacts with the crosslinking agent, which is polymerized and crosslinked at the group that reacts with the crosslinking agent, or it may be a group that reacts with the functional group derived from the energy ray curable compound (e12).

[0099] The polymer (e1) contained in the insulating filler film and thermosetting resin composition (x1) may be one type or two or more types, and if there are two or more types, their combination and ratio can be arbitrarily selected.

[0100] (Compounds with energy-ray curable groups and a molecular weight of 100 to 80000 (e2)) Examples of energy-ray curable groups in compounds (e2) having a molecular weight of 100 to 80000 include groups containing energy-ray curable double bonds, and preferred examples include (meth)acryloyl groups and vinyl groups.

[0101] The compound (e2) is not particularly limited as long as it satisfies the above conditions, but examples include low molecular weight compounds having energy ray curable groups, epoxy resins having energy ray curable groups, and phenolic resins having energy ray curable groups.

[0102] Among the compounds (e2) mentioned above, examples of low molecular weight compounds having an energy-ray curable group include polyfunctional monomers or oligomers, and acrylate compounds having a (meth)acryloyl group are preferred. Examples of the acrylate compounds include 2-hydroxy-3-(meth)acryloyloxypropyl methacrylate, polyalkylene glycol (meth)acrylates such as polyethylene glycol di(meth)acrylate, propoxylated ethoxylated bisphenol E di(meth)acrylate, 2,2-bis[4-((meth)acryloxypolyethoxy)phenyl]propane, ethoxylated bisphenol A di(meth)acrylate, 2,2-bis[4-((meth)acryloxydiethoxy)phenyl]propane, 9,9-bis[4-(2-(meth)acryloyloxyethoxy)phenyl]fluorene, 2,2-bis[4-((meth)acryloxypolypropoxy)phenyl]propane, tricyclodecanedimethanol di(meth)acrylate, 1,10-decanediol di(meth)acrylate, and 1,4-butylene glycoside. Difunctional (meth)acrylates such as di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, dipropylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, polytetramethylene glycol di(meth)acrylate, ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, 2,2-bis[4-(meth)acryloxyethoxy)phenyl]propane, neopentyl glycol di(meth)acrylate, ethoxylated polypropylene glycol di(meth)acrylate, 2-hydroxy-1,3-di(meth)acryloxypropane, and dicyclopentanyl di(meth)acrylate; Tris(2-(meth)acryloxyethyl) isocyanurate, ε-caprolactone modified tris-(2-(meth)acryloxyethyl) isocyanurate, ethoxylated glycerin tri(meth)acrylate, pentaerythritol tri(meth)acrylate, trimethylolpropane tri(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, tetramethylolmethane tetra(meth)acrylate, ethoxylated pentaerythritol tetra( Polyfunctional (meth)acrylates such as meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol monohydroxypenta(meth)acrylate, dipentaerythritol monohydroxypenta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, dipentaerythritol poly(meth)acrylate, and dipentaerythritol hexa(meth)acrylate; Oligoester (meth)acrylate; urethane (meth)acrylate oligomer; epoxy-modified (meth)acrylate; polyether (meth)acrylate other than the above polyalkylene glycol (meth)acrylate; Examples include polyfunctional (meth)acrylate oligomers such as urethane (meth)acrylate oligomers; and itaconic acid oligomers.

[0103] Of the compounds (e2) mentioned above, epoxy resins having energy-ray curable groups and phenolic resins having energy-ray curable groups may also be resins constituting thermosetting component (B), but in the present invention they are treated as compounds (e2).

[0104] The compound (e2) preferably has a weight-average molecular weight of 100 to 30,000, and more preferably 300 to 10,000.

[0105] The compound (e2) contained in the insulating filler film and thermosetting resin composition (x1) may be one type or two or more types, and if there are two or more types, their combination and ratio can be arbitrarily selected.

[0106] The energy-curable compounds used in polymerization may be used individually or in combination of two or more. When two or more energy-curable compounds are used in polymerization, their combination and ratio can be arbitrarily selected. For example, the polymer (e1) and the compound (e2) may be used individually or in combination.

[0107] In the insulating filler film and thermosetting resin composition (x1), when an energy ray curable resin (E) is used, the content of the energy ray curable resin (E) is preferably 1 to 95% by mass, more preferably 5 to 90% by mass, and even more preferably 10 to 85% by mass, based on the total amount of active ingredients in the thermosetting resin composition (x1).

[0108] -Photopolymerization initiator (F)- If the insulating filler film and thermosetting resin composition (x1) contain an energy ray curable resin (E), the insulating filler film and thermosetting resin composition (x1) may also contain a photopolymerization initiator (F) in order to efficiently advance the polymerization reaction of the energy ray curable resin (E).

[0109] Examples of photopolymerization initiators (F) include benzophenone, acetophenone, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, benzoin benzoic acid, benzoin methyl benzoate, benzoin dimethyl ketal, 2,4-diethylthioxanthone, 1-hydroxycyclohexyl phenyl ketone, benzyl diphenyl sulfide, tetramethylthiuram monosulfide, azobisisobutyronitrile, benzyl, dibenzyl, diacetyl, 1,2-diphenylmethane, 2-hydroxy-2-methyl-1-[4-(1-methylvinyl)phenyl]propanone, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, and 2-chloroanthraquinone.

[0110] The photopolymerization initiator (F) may be used alone or in combination of two or more types. If there are two or more types of photopolymerization initiator (F), their combination and ratio can be arbitrarily selected.

[0111] In the insulating filler film and thermosetting resin composition (x1), when a photopolymerization initiator (F) is used, the content of the photopolymerization initiator (F) is preferably 0.1 to 20 parts by mass, more preferably 1 to 10 parts by mass, and even more preferably 2 to 5 parts by mass, based on 100 parts by mass of the energy ray curable resin (E).

[0112] -Additive (G)- The insulating filler film and thermosetting resin composition (x1) may contain additive (G) as long as it does not impair the effects of the present invention. Additive (G) may be any known additive and can be arbitrarily selected depending on the purpose, and is not particularly limited. Preferred additives (G) include, for example, rheology control agents, coupling agents, crosslinking agents, surfactants, plasticizers, antistatic agents, antioxidants, leveling agents, gettering agents, and silicone oils.

[0113] Additive (G) may be used alone or in combination of two or more types. If there are two or more types of additive (G), their combination and ratio can be arbitrarily selected. The amount of additive (G) is not particularly limited and should be selected as appropriate depending on the purpose.

[0114] -solvent- The thermosetting resin composition (x1) preferably further contains a solvent. The thermosetting resin composition (x1) containing the solvent has good handling properties. The solvent is not particularly limited, but preferred solvents include, for example, hydrocarbons such as toluene and xylene; alcohols such as methanol, ethanol, 2-propanol, isobutyl alcohol (2-methylpropan-1-ol), and 1-butanol; esters such as ethyl acetate; ketones such as acetone and methyl ethyl ketone; ethers such as tetrahydrofuran; and amides (compounds having an amide bond) such as dimethylformamide and N-methylpyrrolidone. The solvent may be used alone or in combination of two or more types. If two or more solvents are used, their combination and ratio can be arbitrarily selected. The solvent is preferably methyl ethyl ketone or the like, as it allows for more uniform mixing of the components in the thermosetting resin composition (x1).

[0115] -Method for preparing a thermosetting resin composition (x1)- A thermosetting resin composition (x1) is prepared by blending the components that make it up. The order in which each component is added during formulation is not particularly limited, and two or more components may be added simultaneously. When using a solvent, the solvent may be used after pre-diluting the formulation by mixing it with any of the other components, or the solvent may be used by mixing it with the other components without pre-diluting them. The method of mixing each component during formulation is not particularly limited; it can be appropriately selected from known methods such as mixing by rotating a stirring bar or impeller, mixing using a mixer, or mixing by applying ultrasonic waves. The temperature and time during the addition and mixing of each component are not particularly limited as long as the components do not deteriorate, and can be adjusted as appropriate, but a temperature of 15 to 30°C is preferred.

[0116] (Fabrication of insulating filler film) The insulating filler film can be manufactured, for example, by coating the surface to be formed with the thermosetting resin composition (x1) of this embodiment and drying it as necessary. The thermosetting resin composition (x1) may be applied by known methods, such as using various coaters including an air knife coater, blade coater, bar coater, gravure coater, roll coater, roll knife coater, curtain coater, die coater, knife coater, screen coater, Meyer bar coater, and kiss coater. The drying conditions after applying the thermosetting resin composition (x1) are not particularly limited, but for example, the drying temperature can be set to 70 to 130°C and the drying time to 10 seconds to 5 minutes.

[0117] [Configuration of the insulating composite sheet of this embodiment] The insulating filler film of this embodiment may be a single-layer film or may be formed on the release surface of a release film, but from the viewpoint of improving handling and other aspects, it is preferable to be a composite sheet with a support sheet. The following describes the configuration examples of the composite sheet of this embodiment, specifically the first to third embodiments. However, the configuration examples of the composite sheet of this embodiment are not limited to the first to third embodiments. For example, the first to third embodiments may of course have other layers, as long as they do not significantly impair the effects of the present invention. Furthermore, the insulating filler film will also be referred to as insulating filler film (x) below.

[0118] (First aspect) Figure 1 shows a first embodiment of the composite sheet of this embodiment. The composite sheet 1a shown in Figure 1 comprises a base material 10 and an insulating filler film (x). In the first embodiment, the support sheet is the base material 10. Although not shown, a release film or the like may be provided on the side of the insulating filler film (x) opposite to the base material 10.

[0119] (Second aspect) A second embodiment of the composite sheet of this embodiment is shown in Figure 2. The composite sheet 1b shown in Figure 2 has a base material 10, a buffer layer 11, and an insulating filler film (x) in that order. In the second embodiment, the support sheet is a laminate of the base material 10 and the buffer layer 11. Although not shown, a release film or the like may be provided on the side of the insulating filler film (x) opposite to the buffer layer 11.

[0120] (Third aspect) A third embodiment of the composite sheet of this embodiment is shown in Figure 3. The composite sheet 1c of the third embodiment has an intermediate release layer between the buffer layer 11 and the insulating filler film (x) in the composite sheet of the second embodiment. That is, as shown in Figure 3, the composite sheet 1c of the third embodiment has a base material 10, a buffer layer 11 laminated on one side 10a of the base material 10, an intermediate release layer 13 laminated on the side of the buffer layer 11 opposite to the base material 10, and an insulating filler film (x) laminated on the side of the intermediate release layer 13 opposite to the buffer layer 11. In the second embodiment, the support sheet is a laminate of the base material 10, the buffer layer 11, and the intermediate release layer 13. Although not shown, a release film or the like may be provided on the side of the insulating filler film (x) opposite to the intermediate release layer 13.

[0121] (buffer layer) As described above, the composite sheet of this embodiment may have a buffer layer between the substrate and the insulating filler film. The buffer layer is a layer that has a buffering effect against forces applied to the buffer layer and layers directly or indirectly adjacent to it. Here, "layers directly or indirectly adjacent to the buffer layer" mainly refers to the insulating filler film of this embodiment.

[0122] The buffer layer may consist of only one layer or two or more layers. If the buffer layer consists of multiple layers, these layers may be identical or different from each other, and there are no particular limitations on the combination of these layers.

[0123] The thickness of the buffer layer can be appropriately adjusted according to the depth of the recesses and the height of the protrusions on the surface of the member, but even if relatively tall protrusions are provided, from the viewpoint of making it easier to exert the effects of the present invention, it is preferably 50 to 1,000 μm, more preferably 100 to 800 μm, and even more preferably 150 to 600 μm.

[0124] -Storage modulus (G') of the buffer layer at 80°C- In the composite sheet of this embodiment, the storage modulus (G') of the buffer layer at 80°C is preferably 0.08 MPa or higher. If the storage modulus (G') of the buffer layer at 80°C is 0.08 MPa or higher, it becomes easier to ensure that the insulating filler film fills the recesses. Here, from the viewpoint of making it easier to ensure that the insulating filler film fills the recesses, the storage modulus (G') of the buffer layer at 80°C is more preferably 0.10 MPa or higher, even more preferably 0.12 MPa or higher, even more preferably 0.14 MPa or higher, and still more preferably 0.16 MPa or higher. Furthermore, the storage modulus (G') of the buffer layer at 80°C is preferably 0.4 MPa or less, from the viewpoint of making it easier to adjust the loss tangent (tanδ) of the buffer layer at 80°C (described later) to 1.02 or more, thereby making it easier to ensure the filling of the recesses of the insulating filler film.

[0125] -Loss tangent (tanδ) of the buffer layer at 80°C- In the composite sheet of this embodiment, the loss tangent (tanδ) of the buffer layer at 80°C is preferably 1.02 or greater. If the loss tangent (tanδ) of the buffer layer at 80°C is 1.02 or higher, it is easier to ensure that the insulating filler film fills the recesses. Here, from the viewpoint of making it easier to ensure the filling of the recesses of the insulating filler film, the loss tangent (tanδ) of the buffer layer at 80°C is more preferably 1.05 or higher, even more preferably 1.08 or higher, even more preferably 1.12 or higher, and still most preferably 1.16 or higher. Furthermore, the loss tangent (tanδ) of the buffer layer at 80°C is preferably 2.00 or less, from the viewpoint of making it easier to adjust the storage modulus (G') of the buffer layer at 80°C to 0.08 or higher, thereby making it easier to ensure the filling of the recesses of the insulating filler film.

[0126] The storage modulus (G') and loss tangent (tanδ) of the buffer layer at 80°C can be measured, for example, by the following method. The sample size to be measured is 8 mm in diameter and 1 mm thick (5 layers of 200 μm buffer layers stacked together). Using a rheometer (Anton Paar MCR302), the sample, with the release film removed, is sandwiched between parallel plates from above and below. Shear stress is applied to the sample at a measurement temperature of 0 to 100 °C, a gap of 1 mm, a strain of 0.05 to 0.5%, and an angular frequency of 1 Hz, and the shear storage modulus G' and loss tangent tanδ at 80 °C are calculated.

[0127] In this embodiment, the storage modulus (G') and loss tangent (tanδ) of the buffer layer at 80°C can be appropriately adjusted by adjusting the composition of the buffer layer, etc. The details of the buffer layer will be explained below, taking into account the method for adjusting the storage modulus (G') and loss tangent (tanδ) of the buffer layer at 80°C.

[0128] -Urethane (meth)acrylate- Urethane (meth)acrylate is a compound having at least a (meth)acryloyl group and a urethane bond, and has the property of polymerizing upon energy ray irradiation. By using urethane (meth)acrylate, flexibility can be provided to the buffer layer, and the storage modulus (G') and loss tangent (tanδ) of the buffer layer at 80°C can be easily adjusted to the above range. The urethane (meth)acrylate may be monofunctional or polyfunctional. In this embodiment, polyfunctional urethane (meth)acrylate is preferred, and bifunctional urethane (meth)acrylate is preferred from the viewpoint of easily adjusting the storage modulus (G') and loss tangent (tanδ) of the buffer layer at 80°C to the above range. The urethane (meth)acrylate may be an oligomer, a polymer, or a mixture thereof. In this embodiment, a urethane (meth)acrylate oligomer is preferred. Urethane (meth)acrylate can be obtained, for example, by reacting a terminal isocyanate urethane prepolymer, which is obtained by reacting a polyol compound with a polyvalent isocyanate compound, with a (meth)acrylate having a hydroxyl group. Note that one or more types of urethane (meth)acrylate may be used. From the viewpoint of easily adjusting the storage modulus (G') and loss tangent (tanδ) of the buffer layer at 80°C to the above range, the content of urethane (meth)acrylate in the buffer layer forming composition is preferably 20% by mass or more, more preferably 25% by mass or more, and even more preferably 30% by mass or more. Furthermore, the content of urethane (meth)acrylate in the buffer layer forming composition is preferably 70% by mass or less, more preferably 65% ​​by mass or less, and even more preferably 50% by mass or less.

[0129] -Polymerizable monomer- The polymerizable monomer is preferably a polymerizable compound other than the urethane (meth)acrylate mentioned above, and is a compound that can be polymerized with other components by irradiation with energy rays. Specifically, the polymerizable monomer is preferably a compound having at least one (meth)acryloyl group. Examples of polymerizable monomers include (meth)acrylates having alkyl groups with 1 to 30 carbon atoms; (meth)acrylates having functional groups such as hydroxyl groups, amide groups, amino groups, and epoxy groups; (meth)acrylates having an alicyclic structure; (meth)acrylates having an aromatic structure; (meth)acrylates having a heterocyclic structure; and vinyl compounds such as styrene, hydroxyethyl vinyl ether, hydroxybutyl vinyl ether, N-vinylformamide, N-vinylpyrrolidone, and N-vinylcaprolactam. Examples of (meth)acrylates having alkyl groups with 1 to 30 carbon atoms include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, n-pentyl (meth)acrylate, n-hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, nonyl (meth)acrylate, decyl (meth)acrylate, undecyl (meth)acrylate, dodecyl (meth)acrylate, tridecyl (meth)acrylate, tetradecyl (meth)acrylate, hexadecyl (meth)acrylate, octadecyl (meth)acrylate, and eicosyl (meth)acrylate. Examples of functional group-containing (meth)acrylates include hydroxyl group-containing (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate; (meth)acrylamide, N,N-dimethyl (meth)acrylamide, N-butyl (meth)acrylamide, and N-methylol (meth)acrylamide. Examples include amide group-containing compounds such as lylamide, N-methylolpropane(meth)acrylamide, N-methoxymethyl(meth)acrylamide, and N-butoxymethyl(meth)acrylamide; amino group-containing (meth)acrylates such as primary amino group-containing (meth)acrylates, secondary amino group-containing (meth)acrylates, and tertiary amino group-containing (meth)acrylates; and epoxy group-containing (meth)acrylates such as glycidyl(meth)acrylate, methylglycidyl(meth)acrylate, and allylglycidyl ether. Examples of (meth)acrylates having an alicyclic structure include isobornyl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentanyl (meth)acrylate, dicyclopentenyloxy (meth)acrylate, cyclohexyl (meth)acrylate, trimethylcyclohexyl (meth)acrylate, and adamantane (meth)acrylate. Examples of (meth)acrylates having an aromatic structure include phenylhydroxypropyl (meth)acrylate, benzyl (meth)acrylate, and 2-hydroxy-3-phenoxypropyl (meth)acrylate. Examples of (meth)acrylates having a heterocyclic structure include tetrahydrofurfuryl(meth)acrylate and morpholine(meth)acrylate. In this embodiment, the polymerizable monomer preferably includes (meth)acrylates having an alkyl group with 1 to 30 carbon atoms and (meth)acrylates having an alicyclic structure. From the viewpoint of easily adjusting the storage modulus (G') and loss tangent (tanδ) of the buffer layer at 80°C to the above range, (meth)acrylates having an alkyl group with 4 to 14 carbon atoms are preferred, and as (meth)acrylates having an alicyclic structure, isobornyl (meth)acrylate and trimethylcyclohexyl (meth)acrylate are preferred. Furthermore, if a buffer layer-forming composition contains a crosslinking agent, (meth)acrylates having functional groups that can react with the crosslinking agent are undesirable. This is because the crosslinked structure formed by the crosslinking reaction may increase the residual stress in the buffer layer. For example, a buffer layer-forming composition containing a polyisocyanate-based crosslinking agent and a (meth)acrylate having hydroxyl groups is undesirable. The content of polymerizable monomers in the buffer layer forming composition is preferably 20% by mass or more, and more preferably 30% by mass or more, from the viewpoint of easily adjusting the storage modulus (G') and loss tangent (tanδ) of the buffer layer at 80°C to the above range. Furthermore, the content of polymerizable monomers in the buffer layer forming composition is preferably 80% by mass or less, and more preferably 70% by mass or less. Furthermore, the mass ratio of urethane (meth)acrylate to polymerizable monomer (urethane (meth)acrylate / polymerizable monomer) in a total of 100 parts by mass of urethane (meth)acrylate and polymerizable monomer is preferably 20 / 80 to 80 / 20, and more preferably 30 / 70 to 70 / 30, from the viewpoint of easily adjusting the storage modulus (G') and loss tangent (tanδ) of the buffer layer at 80°C to the above range.

[0130] -Photopolymerization initiator- When the buffer layer forming composition contains the above-mentioned urethane (meth)acrylate and polymerizable monomer, it is preferable that the buffer layer forming composition also contains a photopolymerization initiator. By including a photopolymerization initiator, polymerization proceeds reliably, and the storage modulus (G') and loss tangent (tanδ) of the buffer layer at 80°C can be easily adjusted to the above range. Examples of photopolymerization initiators include benzoin compounds, acetophenone compounds, acylphosphine oxide compounds, titanocene compounds, thioxanthone compounds, and peroxide compounds, as well as photosensitizers such as amines and quinones. Specifically, examples include 1-hydroxycyclohexylphenyl ketone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, and 2,2-dimethoxy-1,2-diphenylethane-1-one. These photopolymerization initiators may be used individually or in combination of two or more. The amount of photopolymerization initiator added is preferably 0.05 parts by mass or more and 15 parts by mass or less, and more preferably 0.5 parts by mass or more and 10 parts by mass or less, based on 100 parts by mass of the total of urethane (meth)acrylate and polymerizable monomer.

[0131] -Chain Transfer Agent- The buffer layer forming composition preferably contains a chain transfer agent. The chain transfer agent can induce a chain transfer reaction and regulate the progress of the curing reaction of the buffer layer forming composition. By including a chain transfer agent, components with relatively short molecular chains can remain even after curing, so that the cured polymer has a relatively flexible structure. As a result, the storage modulus (G') and loss tangent (tanδ) of the buffer layer at 80°C can be easily adjusted to the above range. Examples of chain transfer agents include thiol group-containing compounds. Examples of thiol group-containing compounds include nonyl mercaptan, 1-dodecanethiol, 1,2-ethanedithiol, 1,3-propanedithiol, triazinethiol, triazinedithiol, triazinetrithiol, 1,2,3-propanetrithiol, tetraethylene glycol-bis(3-mercaptopropionate), trimethylolpropanetris(3-mercaptopropionate), pentaerythritoltetrakis(3-mercaptopropionate), and pentaerythritol. Examples include thritol tetrakisthioglucolate, dipentaerythritol hexakis(3-mercaptopropionate), tris[(3-mercaptopropionyloxy)-ethyl]-isocyanurate, 1,4-bis(3-mercaptobutyryloxy)butane, pentaerythritol tetrakis(3-mercaptobutyrate), and 1,3,5-tris(3-mercaptobutyloxyethyl)-1,3,5-triazine-2,4,6-(1H,3H,5H)-trione. The chain transfer agent may be used individually or in combination of two or more types. From the viewpoint of easily adjusting the storage modulus (G') and loss tangent (tanδ) of the buffer layer at 80°C to the above range, the amount of chain transfer agent is preferably 1.0 to 2.5 parts by mass, more preferably 1.2 to 2.0 parts by mass, and even more preferably 1.3 to 1.8 parts by mass, per 100 parts by mass of the total of urethane (meth)acrylate and polymerizable monomer.

[0132] -Other ingredients- The buffer layer may contain other components. These other components are not particularly limited and can be appropriately selected depending on the purpose.

[0133] -Preparation of a buffer layer- As a composition for forming a buffer layer, for example, a buffer layer-forming composition containing the above-mentioned components, or a composition obtained by diluting the buffer layer-forming composition with a solvent or the like, can be prepared. Examples of solvents include organic solvents such as methyl ethyl ketone, acetone, ethyl acetate, tetrahydrofuran, dioxane, cyclohexane, n-hexane, toluene, xylene, n-propanol, and isopropanol. Then, a buffer layer-forming composition or the like is applied to a release film or substrate by a known method such as spin coating, spray coating, bar coating, knife coating, roll coating, blade coating, die coating, or gravure coating to form a coating film, and this coating film is cured to form a buffer layer on the substrate. In this embodiment, it is preferable to cure the coating film by irradiation with energy rays. Examples of energy rays include ultraviolet rays and electron beams, with ultraviolet rays being preferred. Furthermore, in this embodiment, it is preferable to cure the coating film by irradiating it with energy rays multiple times. By doing so, the degree of curing of the buffer layer can be controlled, and the storage modulus (G') and loss tangent (tanδ) of the buffer layer at 80°C can be easily adjusted to the above range. If the energy source is ultraviolet light, the ultraviolet irradiation conditions are preferably such that the ultraviolet irradiance is 30-500 mW / cm². 2 More preferably 50-340 mW / cm² 2 The ultraviolet radiation dose (cumulative light dose) is preferably 100 to 2,500 mJ / cm². 2 More preferably 150 to 2,000 mJ / cm² 2 That is the case. When irradiating with ultraviolet light multiple times, it is preferable that the illuminance and irradiation dose are greater than those of the previous irradiation. Alternatively, the coated film may be exposed to oxygen and irradiated with energy rays, and then the coated film may be shielded from oxygen and irradiated with energy rays again.

[0134] (Intermediate delamination layer) As described above, the composite sheet of this embodiment may have an intermediate release layer between the buffer layer and the insulating filler film. The intermediate release layer is provided to easily peel the support sheet from the insulating filler film after the insulating filler film has been applied to the surface of the member where the recess is formed.

[0135] The intermediate delamination layer is in the form of a sheet or film, and its constituent material is not particularly limited. The intermediate peeling layer may contain, for example, a (meth)acrylic acid ester polymer or an ethylene vinyl acetate copolymer (EVA), but it is preferable that it contains an ethylene-vinyl acetate copolymer (EVA). The intermediate peeling layer may contain other components besides those mentioned above. These other components are not particularly limited and can be appropriately selected depending on the purpose.

[0136] The interdebris layer may be a single layer or a multi-layer structure of two or more layers. If the interdebris layer consists of multiple layers, these layers may be identical or different from each other, and there are no particular limitations on the combination of these layers.

[0137] The thickness of the interlayer is not particularly limited, but is preferably 5 to 30 μm, more preferably 6 to 25 μm, and even more preferably 7 to 20 μm.

[0138] (base material) The base material is in the form of a sheet or film, and its constituent materials include, for example, the following various resins. Examples of resins constituting the base material include polyethylene such as low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), and high-density polyethylene (HDPE); polyolefins other than polyethylene such as polypropylene, polybutene, polybutadiene, polymethylpentene, and norbornene resin; ethylene-based copolymers such as ethylene-vinyl acetate copolymer, ethylene-(meth)acrylic acid copolymer, ethylene-(meth)acrylic acid ester copolymer, and ethylene-norbornene copolymer (polymers obtained using ethylene as a monomer); and vinyl chloride-based resins such as polyvinyl chloride and vinyl chloride copolymer (using vinyl chloride as a monomer). Examples of resins obtained from this process include: polystyrene; polycycloolefin; polyesters such as polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, polyethylene isophthalate, polyethylene-2,6-naphthalenedicarboxylate, and all aromatic polyesters having aromatic cyclic groups as all constituent units; copolymers of two or more of the above polyesters; poly(meth)acrylic acid esters; polyurethane; polyurethane acrylate; polyimide; polyamide; polycarbonate; fluororesin; polyacetal; modified polyphenylene oxide; polyphenylene sulfide; polysulfone; polyether ketone; and the like. Furthermore, examples of resins constituting the base material include polymer alloys such as mixtures of the above-mentioned polyester and other resins. It is preferable that the polymer alloy of polyester and other resins contains a relatively small amount of the resin other than polyester. Furthermore, examples of resins constituting the base material include crosslinked resins obtained by crosslinking one or more of the above-mentioned resins; and modified resins such as ionomers using one or more of the above-mentioned resins. The resins that make up the base material may be used individually or in combination of two or more types.

[0139] The base material may consist of only one layer or two or more layers. If the base material consists of multiple layers, these layers may be identical or different from each other, and there are no particular limitations on the combination of these layers.

[0140] The thickness of the substrate is not particularly limited, but is preferably 5 to 1,000 μm, more preferably 10 to 500 μm, even more preferably 15 to 300 μm, and even more preferably 20 to 150 μm.

[0141] The base material is preferably one with high thickness accuracy, that is, one in which thickness variation is suppressed regardless of the location. Among the constituent materials mentioned above, examples of materials with high thickness accuracy that can be used to construct such a base material include polyethylene, polyolefins other than polyethylene, polyethylene terephthalate, polybutylene terephthalate, polyesters other than polyethylene terephthalate and polybutylene terephthalate, and ethylene-vinyl acetate copolymers.

[0142] In addition to the main constituent materials such as the resin mentioned above, the base material may also contain various known additives such as fillers, colorants, antioxidants, organic lubricants, catalysts, and plasticizers.

[0143] The substrate may be transparent or opaque, may be colored depending on the purpose, or may have other layers deposited on it. Furthermore, if the insulating filler film has energy ray curing properties, it is preferable that the substrate is one that transmits energy rays.

[0144] The substrate can be manufactured by known methods. For example, a substrate containing a resin can be manufactured by molding a resin composition containing the above-mentioned resin.

[0145] (Method of manufacturing composite sheets) The composite sheet of this embodiment can be manufactured by sequentially stacking the above-mentioned layers in corresponding positional relationships. For example, a composite sheet having a laminated structure of a substrate and an insulating filler film can be manufactured by the method shown below. The thermosetting resin composition (x1) of this embodiment is applied to the release surface of the release film, and an insulating filler film is formed on the release film by drying as necessary. Next, the substrate and the exposed side of the insulating filler film opposite to the release film are bonded together. This results in a composite sheet having a laminated structure of the substrate and the insulating filler film. The release film provided on the insulating filler film within the composite sheet can be removed at any stage between the time of manufacture and the time of use of the composite sheet. Furthermore, a composite sheet having a laminated structure of a substrate and an insulating filler film can also be manufactured by coating one side of the substrate with a thermosetting resin composition (x1) and drying it as necessary.

[0146] Furthermore, for example, a composite sheet having a base material, a buffer layer, and an insulating filler film in this order can be manufactured by the method shown below. A buffer layer is formed on a release film by coating one surface of a substrate with a buffer layer-forming composition and curing it. A first laminated sheet is obtained by laminating the substrate and the buffer layer. A release film may be provided on the surface of the buffer layer in the first laminated sheet opposite to the substrate, if necessary. Separately, the thermosetting resin composition (x1) of this embodiment is applied to the release surface of the release film and dried as necessary to form the thermosetting resin composition (x1) on the release film. Next, the exposed surface of the buffer layer in the first laminated sheet opposite to the substrate and the exposed surface of the insulating filler film opposite to the release film are bonded together. This results in a composite sheet having a structure in which the substrate, buffer layer, insulating filler film, and release film are laminated in this order. The release film provided on the insulating filler film within the composite sheet can be removed at any stage between the time of manufacture and the time of use of the composite sheet.

[0147] A composite sheet comprising layers other than those described above can be manufactured by adding or omitting steps as appropriate in the manufacturing method described above, so that the stacking positions of each layer are at desired positions.

[0148] [Applications of the insulating filler film of this embodiment] The insulating filler film of this embodiment is used to fill recesses in a member having recesses formed on its surface. The recesses and components will be described in detail below.

[0149] In this specification, "recess" refers to a portion of a material that is thinner than its surroundings. Examples of recesses include grooves or holes sandwiched between flat surfaces.

[0150] (recess) In this embodiment, the recess formed on the surface of the member is not particularly limited, but preferably satisfies at least one of the following requirements (I) to (IV). Requirement (I): When the cross-section of the recess is taken along the thickness direction of the member, the cross-section does not reach (i) the outer edge of the surface on which the recess is formed and (ii) the back surface of the surface on which the recess is formed. Requirement (II): The difference between the deepest and shallowest points in the recess is 30 μm or more. Requirement (III): When the recess is viewed from above, at least a portion of it is composed of a curve. Requirement (IV): When the cross-section of the recess is taken along the thickness direction of the member, the aspect ratio of the shape of the cross-section is 3 or greater. The insulating filler film of this embodiment exhibits excellent filling properties not only for recesses that are straight when viewed from above, have a constant depth, and allow air to escape, such as so-called half-cut recesses, but also for recesses that are difficult to fill without introducing air bubbles or the like, satisfying at least one of the above requirements (I) to (IV).

[0151] A recess that satisfies requirement (I) is one in which, when an insulating filling film is applied to the surface of the member in which the recess is formed and pressurized, there is no escape route for air within the recess. Furthermore, "the recess is formed without reaching the back surface of the member" means that, if the member is composed of multiple members, it does not penetrate at least all of the members. The recesses that satisfy requirement (I) are not particularly limited, but examples include straight groove-shaped recesses, hole-shaped recesses, and recesses that surround flat areas. Figure 4 shows a hole-shaped recess that has a rectangular shape when viewed from above.

[0152] A recess that satisfies requirement (II) is one that has variations in depth, i.e., a recess that is not of a constant depth. In requirement (II), the difference between the deepest and shallowest points in the depth of the recess is preferably 30 μm or more, more preferably 60 μm or more, and even more preferably 100 μm or more. Furthermore, the difference between the deepest and shallowest points is preferably 500 μm or less, more preferably 400 μm or less, and even more preferably 300 μm or less. Furthermore, in this specification, "depth of recess" means the distance in the thickness direction between the opening surface of the recess and the bottom of the recess. Furthermore, if multiple recesses are formed on the surface of the component, "having depth variations" includes cases where the depth of each recess is not the same. The recesses that satisfy requirement (II) are not particularly limited, but examples include recesses with a sloping bottom surface, recesses with an uneven bottom surface, recesses with a flat bottom surface but an uneven groove opening, and multiple recesses of different depths. Figure 5 shows a recess with an uneven bottom surface.

[0153] A recess that satisfies requirement (III) may consist solely of curves when viewed from above, or it may be a combination of curves and other elements. There are no particular limitations on the type of recess that satisfies requirement (III), but examples include recesses that are partially straight and partially curved when viewed from above, wavy recesses, dot-shaped recesses, recesses with circles or rings arranged in a row, concentric recesses, and recesses with endpoints on only one side of the member. Figure 6 shows a recess whose shape when viewed from above is ring-shaped.

[0154] A recess that satisfies requirement (IV) is an elongated recess in which, when the cross-section of the recess is taken along the thickness direction of the member, the shape of the cross-section has a high aspect ratio, that is, the depth of the recess is large relative to the opening width of the recess. In this specification, "aspect ratio" refers to the maximum value expressed as D / W, where W is the opening width of the recess and D is the depth of the recess. For example, an aspect ratio of 3 or greater indicates a high aspect ratio. Furthermore, in requirement (IV), the upper limit of the aspect ratio of the recess is preferably 9 or less, more preferably 8 or less, and even more preferably 7 or less. Furthermore, in requirement (IV), the lower limit of the aspect ratio of the recess is preferably 3 or more, more preferably 3.5 or more, even more preferably 4 or more, and even more preferably 4.5 or more. In this specification, "opening width of the recess" means, for example, the length of the minor axis if the shape of the opening of the recess is a circle or ellipse when viewed from above, the length of the short side if it is a rectangle, the diameter of the inscribed circle if it is a regular polygon, and the shortest distance between the outer edge and the inner edge if it is an annular shape. Furthermore, in this specification, "depth of recess" means the distance in the thickness direction between the opening surface of the recess and the bottom of the recess, as described above. The recess that satisfies requirement (IV) is not particularly limited, but examples include elongated groove-shaped recesses and elongated hole-shaped recesses. Figure 7 shows an elongated hole-shaped recess.

[0155] In this embodiment, the recess formed on the surface of the member is particularly preferably one that satisfies at least the above requirement (I).

[0156] (Component) In this embodiment, the material is not particularly limited, but it is preferably a material used in the manufacture of electronic components, and more preferably a material used in the manufacture of semiconductor devices.

[0157] Electronic components are not particularly limited, but examples include not only semiconductor devices such as integrated circuits, but also components mounted on electronic circuits such as capacitors, resistors, transformers, inductors, switches, touch panels, connectors, speakers and other acoustic components, various sensors, actuators, batteries and other power supplies, attenuators and other high-frequency components, and cables.

[0158] (A component with recesses formed on its surface) In this embodiment, the member having recesses formed on its surface is not particularly limited, but examples include a semiconductor wafer on which the aforementioned IGBT is provided and a semiconductor wafer with deeper trenches than conventional ones, known as a deep trench capacitor, in order to increase capacitance by increasing the surface area.

[0159] [Method for manufacturing electronic components of this embodiment] The details of each step in the manufacturing method of the electronic component according to this embodiment will be described below. In the following explanation, we will use the example of forming an isolated recess on a semiconductor wafer that satisfies the aforementioned requirement (i), as shown in Figure 8, but the necessary steps will differ depending on the electronic component in question. For example, for a component that already has a recess formed therefrom, the subsequent step (S1) is unnecessary. In other words, the method for manufacturing an electronic component according to this embodiment includes at least the steps of filling the recesses of a member having recesses formed on its surface using the insulating filling film of this embodiment, and heating.

[0160] (Process (S1): Recess formation process) Figure 8 is a schematic plan view and cross-sectional view illustrating the recess formation process. In the recess formation process, for example, as shown in Figure 8, a recess 21 is formed in the semiconductor wafer 20. The method for forming the recess is not particularly limited, but known methods such as dry etching, wet etching, and lasers may be used. Furthermore, the following explanation will use the case where composite sheet 1b is used as an example, but composite sheet 1a or 1c may also be used, and it is also possible to directly apply the insulating filler film as a single layer.

[0161] (Process (S21): Pasting process) Figure 9 is a schematic cross-sectional view illustrating the application process. In the bonding process, for example, first, as shown in Figure 9(a), the composite sheet 1b is positioned so that the insulating filler film (x) faces the recess-forming surface (α) of the semiconductor wafer 20. Next, the insulating filler film (x) is brought into contact with the recess-forming surface (α) on the semiconductor wafer 20, and the composite sheet 1d is pressed against the semiconductor wafer 20. By pressing, the insulating filler film (x) is sequentially pressed onto the recess-forming surface (α) of the semiconductor wafer 20. When the composite sheet 1b is pressed onto the semiconductor wafer 20, the insulating filler film (x) deforms due to the pressure through the buffer layer 11 and enters the recess 21. Finally, as shown in Figure 9(b), the recess 21 is filled with the insulating filler film (x). Furthermore, from the viewpoint of increasing the degree of filling of the recesses by the insulating filling film (x), as described above, it is preferable that the storage modulus (G') of the buffer layer at 80°C be 0.10 MPa or higher. Also, from the viewpoint of making it easier to ensure the filling of the recesses by the insulating filling film, as described above, it is preferable that the loss tangent (tanδ) of the buffer layer at 80°C be 1.05 or higher.

[0162] As a method for pressing the composite sheet 1b onto the semiconductor wafer 20, known methods for pressing and attaching various sheets to an object can be applied, such as using a roller-type laminator. The heating temperature when pressing the composite sheet 1b onto the semiconductor wafer 20 is not particularly limited and may be, for example, 70 to 100°C, and preferably 75 to 90°C. The pressure applied when pressing the composite sheet 1b onto the semiconductor wafer 20 is not particularly limited and may be, for example, 0.1 to 1.5 MPa, and preferably 0.3 to 1 MPa. The speed at which the composite sheet 1b is attached to the semiconductor wafer 20 is not particularly limited, and is usually around 2 to 3 mm / s.

[0163] After the bonding process, the side of the semiconductor wafer 20 opposite to the recess-forming surface (α) (the back surface) may be ground as needed, and another sheet (not shown) may be attached to the back surface after grinding.

[0164] (Step (S22): Removal step) When applying an insulating filler film (x) using a composite sheet, a removal step (S22) is required. Figure 10 is a schematic cross-sectional view illustrating the removal step. After the bonding process, as shown in Figure 10, layers other than the insulating filler film (x) (support sheet) are removed from the composite sheet 1b to obtain a semiconductor wafer 30 with an insulating filler film, which comprises a semiconductor wafer 20 and an insulating filler film (x) provided on the recess-forming surface (α) of the semiconductor wafer 20. Layers other than the insulating filler film (support sheets) can be removed by known methods.

[0165] (Process (S23): hardening process) After the above process, as shown in Figure 11, the insulating filler film is heat-cured to form a cured resin film (x)' on the recess-forming surface (α) of the semiconductor wafer 20. This results in a semiconductor wafer 40 with a cured resin film (x)' on the recess-forming surface (α) of the semiconductor wafer 20. The conditions for thermosetting the insulating filler film (x) are not particularly limited and can be appropriately adjusted and determined depending on the type of material constituting the insulating filler film (x). [Examples]

[0166] The present invention will be specifically described by the following examples, but the present invention is not limited to these examples. If the measuring instruments used in the examples are difficult to obtain due to discontinuation or other reasons, measurements can be taken using other instruments with equivalent performance.

[0167] [Manufacturing of composite sheets with insulating filler film] A composite sheet containing an insulating filler film was manufactured using the method described below.

[0168] <Raw materials for thermosetting resin composition (x1)> The raw materials used in the production of the thermosetting resin composition (x1) are shown below. "Polymer component (A)" (A)-1: Polyvinyl butyral having constituent units represented by the following formulas (i)-1, (i)-2, and (i)-3 (Sekisui Chemical Co., Ltd. "S-Lec BL-10", mass-average molecular weight 25,000, glass transition temperature 59°C). [ka] (In the formula, l is approximately 28, m is between 1 and 3, and n is an integer between 68 and 74.) "Epoxy resin (B1)" (B1)-1: Liquid modified bisphenol A type epoxy resin (DIC Corporation's "Epiclon EXA-4860", number average molecular weight 900, epoxy equivalent 410 g / eq) (B1)-2: Dicyclopentadiene type epoxy resin (DIC Corporation's "Epiclon HP-7200HH", epoxy equivalent 254-264 g / eq) "Thermosetting agent (B2)" (B2)-1: O-cresol type novolac resin (DIC Corporation's "Phenolite KA-1160") "Curing accelerator (C)" (C)-1:2-phenyl-4,5-dihydroxymethylimidazole (Shikoku Chemicals Co., Ltd. "Curesol 2PHZ-PW") "Filling material (D)" (D)-1: Spherical silica modified with epoxy groups (Admanano YA050C-MKK, manufactured by Admatex, with an average particle size of 50 nm)

[0169] <Manufacturing Example 1: Fabrication of insulating filler film-1 and composite sheet (X)-1> (Preparation of insulating filler film-1) Polymer component (A)-1 (100 parts by mass), epoxy resin (B1)-1 (290 parts by mass), epoxy resin (B1)-2 (220 parts by mass), (B2)-1 (170 parts by mass), curing accelerator (C)-1 (1 part by mass), and filler (D)-1 (200 parts by mass) were blended, dissolved or dispersed in methyl ethyl ketone, and stirred at 23°C to obtain a thermosetting resin composition in which the total concentration of all components other than the solvent was 45% by mass. Note that all amounts of components other than the solvent shown herein are the amounts of the target product excluding the solvent. Next, a polyethylene terephthalate multilayer sheet (Lintec Corporation's "SP-PET502150", 50 μm thick) was used as the release film. The thermosetting resin composition obtained above was applied to the release surface and dried at 100°C for 2 minutes to produce an insulating filler film-1 with a thickness of 45 μm.

[0170] (Preparation of a buffer layer) A buffer layer-forming composition was obtained by blending 40 parts by mass of aliphatic urethane acrylate (CN966J75 NS, manufactured by Arkema), 40 parts by mass of isobornyl acrylate (IBXA), and 20 parts by mass of dodecyl acrylate, totaling 100 parts by mass, with 3.0 parts by mass of a photopolymerization initiator (Irgacure 1173 (2-hydroxy-2-methyl-1-phenyl-propan-1-one), manufactured by BASF) and 1.5 parts by mass of a chain transfer agent (Kalenz MT PE1 (pentaerythritol tetrakis (3-mercaptobutyrate)), manufactured by Resonaq). The obtained buffer layer-forming composition was coated onto one side of a polyethylene terephthalate film (Toray Industries, Ltd., "Polyester Film "Lumirror" U34", 75 μm thick) using a knife method to form a buffer layer-forming composition layer with a thickness of 200 μm. Next, the formed buffer layer-forming composition layer was laminated with a PET release film (Lintec Corporation, SP-PET381130, 38 μm thick) to isolate the buffer layer-forming composition layer from oxygen. Subsequently, an illuminance of 80 mW / cm² was applied using a high-pressure mercury lamp. 2 , integrated light intensity 200 mJ / cm 2 After UV irradiation under these conditions, a metal halide lamp was used to achieve an illuminance of 330 mW / cm². 2 , irradiation amount 1260mJ / cm 2 The buffer layer-forming composition layer was cured by ultraviolet irradiation under these conditions, forming a buffer layer with a thickness of 200 μm. As a result, a laminated sheet (hereinafter also referred to as the "first laminated sheet") was obtained, in which the base material, the buffer layer, and the release film were laminated in this order in the thickness direction.

[0171] (Preparation of the intermediate delamination layer) At room temperature, an ethylene-vinyl acetate copolymer (weight-average molecular weight 55,000, VA content 20% by mass) was dissolved in toluene to prepare a toluene solution with a solid content concentration of 12% by mass, which was used as the composition for forming the intermediate peel layer. Then, the intermediate release layer formation composition obtained above was applied to the release treatment surface of a newly prepared release film (Lintec Corporation, product name "SP-PET381031", thickness 38 μm), and heated and dried at 100°C for 2 minutes to form an intermediate release layer with a thickness of 10 μm.

[0172] (Creation of composite sheets) In the first laminated sheet obtained as described above, the release film was removed, and the exposed surface of the intermediate release layer obtained as described above was bonded to the exposed surface of the buffer layer resulting from this process, thereby obtaining a laminated sheet in which the first laminated sheet and the intermediate release layer were laminated together. Next, the release film was removed from the intermediate release layer after lamination, and the exposed surface of the insulating filler film-1 with single-sided release film obtained above was laminated to the exposed surface of the intermediate release layer resulting from this. As a result, a composite sheet (X)-1 was obtained, which was constructed by laminating a substrate (thickness 75 μm), a buffer layer (thickness 200 μm), an intermediate release layer (thickness 10 μm), and an insulating filler film-1 (thickness 45 μm) in this order in the thickness direction.

[0173] <Manufacturing Example 2: Fabrication of insulating filler film-2 and composite sheet (X)-2> An insulating filler film-2 with a thickness of 45 μm and a composite sheet (X)-2 comprising the insulating filler film-2 were prepared using the same method as in Production Example 1, except that the amount of filler (D)-1 was changed to 640 parts by mass.

[0174] <Comparative Manufacturing Example 1: Fabrication of insulating filled film-3 and composite sheet (X)-3> An insulating filler film-3 with a thickness of 45 μm and a composite sheet (X)-3 comprising the insulating filler film-3 were prepared using the same method as in Production Example 1, except that the amount of filler (D)-1 was changed to 1170 parts by mass.

[0175] <Formation of recess 1> Using a dicing machine (Disco, product name "DFD6363"), a mirror wafer (8 inches, 750 μm thick) was half-cut to create a 6 mm x 6 mm square on its mirror surface, with a groove depth of 200 μm and a groove width of 55 μm.

[0176] <Formation of recess 2> Using a laser marker (manufactured by Keyence Corporation, product name "MD-U1000C"), a recess was created on the mirror surface of an 8-inch, 750 μm thick mirror wafer under the following conditions, with a depth of 200 μm, an aperture width of 30 μm, and a shape as shown in Figure 8, such that the outer edge forms a 1 mm square when viewed from above. Furthermore, recess 2 satisfies the aforementioned requirements (I) and (IV). • Frequency: 40 kHz Output: 1.9 W ·Irradiation speed: 10 mm / sec

[0177] <Formation of recess 3> Using the same equipment and wafer as when creating recess 2, the shape of recess 2 was created, and then, under the same conditions, laser irradiation was performed again on a portion of the created groove (specifically, a pair of opposing sides of a 1 mm square), with the focus on the bottom of the groove. This created a recess with varying depths, with sections at depths of 200 μm and 400 μm. Furthermore, recess 3 satisfies the aforementioned requirements (I), (II), and (IV).

[0178] <Formation of recess 4> Using the same equipment and wafer as when recess 2 was created, laser irradiation was performed under the same conditions to print the letter "Q" with a depth of 200 μm and a line width of 30 μm. This created recess 4 with a curved shape, a depth of 200 μm, and a line width of 30 μm. Furthermore, recess 4 satisfies the aforementioned requirements (I), (III), and (IV).

[0179] [Examples 1-2 and Comparative Example 1] In Examples 1 and 2 and Comparative Example 1, the composite sheets shown in Table 1 were used, and the measurements and evaluations described later were performed.

[0180] [Measurement of complex viscosity of insulating filler film at 80°C and 130°C] A 1 mm thick insulating filler film layer was formed by laminating multiple insulating filler films. A cylindrical evaluation sample with a diameter of 25 mm and a thickness of 1 mm was prepared from this insulating filler film layer, and this sample was placed in a shear viscosity measuring device (Anton Paar "MCR301"). At this time, the sample was placed on the installation location of the measuring device, and the sample was fixed in place by pressing a measuring jig against the top surface of the sample. The complex viscosity was measured at intervals from room temperature to 150°C under the following measurement conditions, and the complex viscosity at 80°C and 130°C was determined. • Frequency: 11Hz • Heating rate: 10℃ / min • Applied strain: 0.1%

[0181] [evaluation] The ability to fill recesses and repel materials were evaluated using the method described below.

[0182] <Evaluation of recess-filling properties> A roller-type laminator (Lintec Corporation, product name "RAD-3520 F / 12") was used as the lamination device, and under the following lamination conditions, the insulating filler film side of a composite sheet (X) was attached to the mirror surface having recesses 1 or 2 of a mirror wafer (8 inches, 250 μm thick) with recesses 1 or 2 formed thereon, and the support sheet (a laminate of the substrate, buffer layer, and intermediate release layer) was peeled off. (Attachment conditions) • Table temperature: 80℃ • Application speed: 2mm / s • Adhesion pressure: 0.5 MPa • Roller application height: 0 μm Next, the insulating film was heat-cured by heating it at 130°C for 4 hours. Next, the cross-section of each recess was observed using a digital microscope (Keyence Corporation, product name "VX-7800"), and the recess-filling properties were evaluated according to the following criteria. Evaluation A: No air bubbles remained, and the recesses were filled with resin. Evaluation B: Although some air bubbles with a diameter of 15 μm or less remained, the product was generally filled. Evaluation C: Bubbles larger than 15 μm in diameter remained. A grade of A or B was considered a passing grade.

[0183] <Evaluation of repellency> A roller-type laminator (Lintec Corporation, product name "RAD-3520 F / 12") was used as the lamination device, and under the following lamination conditions, the insulating filler film side of a composite sheet (X) was attached to the mirror surface having recesses 1 or 2 of a mirror wafer (8 inches, 250 μm thick) with recesses 1 or 2 formed thereon, and the support sheet (a laminate of the substrate, buffer layer, and intermediate release layer) was peeled off. (Lamination Conditions) ·Table temperature: 80°C ·Lamination speed: 2mm / s ·Lamination pressure: 0.5MPa ·Roller lamination height: 0μm Next, the surface of each wafer after lamination of the insulating filling film was observed to check whether repellency of the filling resin occurred inside and at the edges of the recesses, and the repellency was evaluated according to the following criteria. Evaluation A: No repellency Evaluation B: With repellency It should be noted that Evaluation A was regarded as acceptable.

[0184] The results are shown in Table 1.

[0185]

Table 1

[0186] It can be seen from Table 1 that Examples 1 and 2, in which the complex viscosity at 80°C of the insulating filling film is 15,000 Pa·s or less, exhibit excellent filling properties for all of the recesses 1 to 4.

Description of Reference Signs

[0187] (α) Recess-formed surface (x) Insulating filling film (x)' Cured resin film 1a, 1b, 1c Composite sheet 10 Base material 11 Buffer layer 13 Intermediate release layer 20 Semiconductor wafer 21 Recess 30 Semiconductor wafer with insulating filling film 40 Semiconductor wafer with cured resin film

Claims

1. An insulating filling film used to fill recesses in a member having recesses formed on its surface, An insulating filler film having a complex viscosity of 15,000 Pa·s or less at 80°C.

2. The insulating filler film according to claim 1, wherein the recess satisfies at least one of the following requirements (I) to (IV). Requirement (I): When the cross-section of the recess is taken along the thickness direction of the member, the cross-section does not reach (i) the outer edge of the surface on which the recess is formed and (ii) the back surface of the surface on which the recess is formed. Requirement (II): The difference between the deepest and shallowest points in the recess is 30 μm or more. Requirement (III): When the recess is viewed from above, at least a portion of it is composed of a curve. Requirement (IV): When the cross-section of the recess is taken along the thickness direction of the member, the aspect ratio of the shape of the cross-section is 3 or more.

3. The insulating filler film according to claim 2, wherein the recess is a recess that satisfies at least requirement (I).

4. Furthermore, the insulating filler film according to any one of claims 1 to 3, wherein the complex viscosity at 130°C is 50 Pa·s or more.

5. An insulating-filled composite sheet comprising an insulating-filled film according to any one of claims 1 to 3, in addition to a support sheet.

6. A method for manufacturing an electronic component, comprising the steps of filling a recess in a member having a recess formed on its surface using an insulating filling film according to any one of claims 1 to 3, and heating the member.

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