JP7471940B2 - Sealing resin sheet - Google Patents

Description

The present invention relates to an encapsulating resin sheet, more specifically, to an encapsulating resin sheet for encapsulating elements.

It has been known that a sealing sheet containing a thermosetting resin is used to seal semiconductor elements or electronic components mounted on a substrate by pressing, and then the thermosetting resin is thermally cured to form a cured body from the sealing sheet (see, for example, Patent Document 1 below).

JP 2016-162909 A

In recent years, as electronic devices have become more sophisticated, there has been a demand for the miniaturization of the semiconductor elements and electronic components used in them. Accordingly, there is a demand for improved dimensional accuracy during curing of the resin (cured body) that protects the semiconductor elements and electronic components. Specifically, there is a demand to further reduce the amount of intrusion of the cured body that intrudes between the semiconductor elements and electronic components and the substrate from the side edges of the semiconductor elements and electronic components.

The present invention provides an encapsulating resin sheet that can reduce the intrusion of the cured body between elements, such as semiconductor elements and electronic components, and substrates.

The present invention [1] is an encapsulating resin sheet for encapsulating an element, which contains a thermosetting resin, a layered silicate compound, and a thermoplastic resin, and the thermoplastic resin includes an acrylic resin, the acrylic resin has a carboxyl group, and the acid value of the acrylic resin is 18 or more.

The present invention [2] includes the sealing resin sheet described in [1] above, in which the number of functional groups of the acrylic resin is 300 or more.

The present invention [3] includes the sealing resin sheet according to the above [1] or [2], in which the mass ratio of the acrylic resin to the layered silicate compound (acrylic resin/layered silicate compound) is 0.1 or more and 2 or less.

In the sealing resin sheet of the present invention, the thermoplastic resin contains an acrylic resin having a carboxyl group, and the acid value of the acrylic resin is 18 or more.

As a result, when this sealing resin sheet is placed on an element and heated to form a hardened body, the amount of hardened body that penetrates between the element and the substrate can be reduced.

1A to 1D are cross-sectional views showing the process of manufacturing an electronic element package by encapsulating multiple electronic elements using a first embodiment of the encapsulating resin sheet of the present invention, where FIG. 1A shows the process of preparing an encapsulating resin sheet, FIG. 1B shows the process of preparing electronic elements, FIG. 1C shows the process of pressing the encapsulating resin sheet to form an encapsulated body, and FIG. 1D shows the process of heating the encapsulated body to form a hardened body. 2A to 2D are schematic diagrams showing the change in morphology of a layered silicate compound in a sealing resin sheet, in which FIG. 2A shows the morphology of the layered silicate compound in a dry state, FIG. 2B shows the morphology of the layered silicate compound in a step of preparing a sealing resin sheet, FIG. 2C shows the morphology of the layered silicate compound in a step of pressing the sealing resin sheet to form a sealing body, and FIG. 2D shows the morphology of the layered silicate compound in a step of heating the sealing body to form a hardened body. 3A to 3D are cross-sectional views showing the process of manufacturing an electronic element package by encapsulating a plurality of electronic elements using a second embodiment of the encapsulating resin sheet of the present invention, in which FIG. 3A shows the process of preparing an encapsulating multilayer resin sheet, FIG. 3B shows the process of preparing electronic elements, FIG. 3C shows the process of pressing the encapsulating multilayer resin sheet to form an encapsulated body, and FIG. 3D shows the process of heating the encapsulated body to form a hardened body. 4A to 4D are cross-sectional views of steps in a method for measuring the penetration length Y of the cured body in an embodiment, in which FIG. 4A shows a step of preparing an encapsulating multilayer resin sheet (Step A), FIG. 4B shows a step of preparing an electronic element (dummy element) (Step B), FIG. 4C shows a step of pressing the encapsulating multilayer resin sheet to form an encapsulated body (Step C), and FIG. 4D shows a step of heating the encapsulated body to form a cured body (Step D). FIG. 5 is a chart showing the results of viscoelasticity measurement of the sealing resin sheet. 6A and 6B are photographs showing AFM images of encapsulating resin sheets, in which FIG. 6A is an AFM image of the encapsulating resin sheet of Preparation Example 1 and FIG. 6B is an AFM image of the encapsulating resin sheet of Comparative Preparation Example 1. FIG. 7 is a chart showing the results of infrared absorption spectrum of the sealing resin sheet.

The first embodiment of the encapsulating resin sheet of the present invention (one-layer encapsulating resin sheet) will be described.

The sealing resin sheet is a resin sheet for sealing elements, and has a roughly plate shape (film shape) that extends in a plane direction perpendicular to the thickness direction.

The material of the sealing resin sheet contains a thermosetting resin, a layered silicate compound, and a thermoplastic resin. In other words, this material is a silicate-resin composition that contains a thermosetting resin, a layered silicate compound, and a thermoplastic resin.

Examples of thermosetting resins include epoxy resins, silicone resins, urethane resins, polyimide resins, urea resins, melamine resins, and unsaturated polyester resins.

Thermosetting resins can be used alone or in combination of two or more types.

The thermosetting resin is preferably an epoxy resin. The epoxy resin is prepared as an epoxy resin composition containing a base resin, a curing agent, and a curing accelerator.

Examples of the base agent include bifunctional epoxy resins such as bisphenol A type epoxy resin, bisphenol F type epoxy resin, modified bisphenol A type epoxy resin, modified bisphenol F type epoxy resin, and biphenyl type epoxy resin, and multifunctional epoxy resins having three or more functional groups such as phenol novolac type epoxy resin, cresol novolac type epoxy resin, trishydroxyphenylmethane type epoxy resin, tetraphenylolethane type epoxy resin, and dicyclopentadiene type epoxy resin. These base agents can be used alone or in combination of two or more types. As the base agent, preferably, bifunctional epoxy resins are used, and more preferably, bisphenol F type epoxy resins are used.

The lower limit of the epoxy equivalent of the base agent is, for example, 10 g/eq., preferably 100 g/eq. The upper limit of the epoxy equivalent of the base agent is, for example, 300 g/eq., preferably 250 g/eq.

The lower limit of the softening point of the base agent is, for example, 50°C, preferably 70°C, more preferably 70°C, and even more preferably 75°C. The upper limit of the softening point of the base agent is, for example, 130°C, preferably 110°C, and more preferably 90°C.

If the softening point of the base resin is equal to or higher than the lower limit described above, the sealing resin sheet 1 can flow in the process shown in FIG. 1C. This allows the time required for the process shown in FIG. 1C to be shortened, and one surface in the thickness direction of the sealing resin sheet 1 to be flattened in the process shown in FIG. 3C.

The lower limit of the proportion of the main agent in the material is, for example, 1 mass %, preferably 2 mass %. The upper limit of the proportion of the main agent in the material is, for example, 30 mass %, preferably 15 mass %. The lower limit of the proportion of the main agent in the epoxy resin composition is, for example, 30 mass %, preferably 50 mass %. The upper limit of the proportion of the main agent in the epoxy resin composition is, for example, 80 mass %, preferably 70 mass %.

The curing agent is a latent curing agent that cures the base agent by heating. Examples of the curing agent include phenolic resins such as phenol novolac resin. If the curing agent is a phenolic resin, the phenolic resin and the base agent together form a cured product that has high heat resistance and high chemical resistance. Therefore, the cured product has excellent sealing reliability.

The ratio of the curing agent is set to the following equivalent ratio. Specifically, the lower limit of the total of hydroxyl groups in the phenolic resin relative to 1 equivalent of epoxy groups in the base agent is, for example, 0.7 equivalents, preferably 0.9 equivalents. The upper limit of the total of hydroxyl groups in the phenolic resin relative to 1 equivalent of epoxy groups in the base agent is, for example, 1.5 equivalents, preferably 1.2 equivalents. Specifically, the lower limit of the number of parts of the curing agent contained per 100 parts by mass of the base agent is, for example, 20 parts by mass, preferably 40 parts by mass. The upper limit of the number of parts of the curing agent contained per 100 parts by mass of the base agent is, for example, 80 parts by mass, preferably 60 parts by mass.

The curing accelerator is a catalyst (thermal curing catalyst) that accelerates the curing of the base agent by heating. Examples of the curing accelerator include organic phosphorus compounds, such as imidazole compounds such as 2-phenyl-4,5-dihydroxymethylimidazole (2PHZ-PW). Imidazole compounds are preferred. The lower limit of the number of parts of the curing accelerator per 100 parts by mass of the base agent is, for example, 0.05 parts by mass. The upper limit of the number of parts of the curing accelerator per 100 parts by mass of the base agent is, for example, 5 parts by mass.

The content of thermosetting resin in the material will be described later.

The layered silicate compound is dispersed in the thermosetting resin and thermoplastic resin (resin matrix) in the material (sealing resin sheet). The layered silicate compound is also a flow regulator when forming an encapsulant and a cured body (described later) from the sealing resin sheet. Specifically, the layered silicate compound is a curing flow reducer that reduces the fluidity of the cured body when the sealing resin sheet is heated to form the cured body.

A layered silicate compound is, for example, a silicate having a structure (three-dimensional structure) in which layers extending two-dimensionally (in the plane direction) are stacked in the thickness direction, and is called a phyllosilicate.

Specific examples of layered silicate compounds include smectites such as montmorillonite, beidellite, nontronite, saponite, hectorite, sauconite, and stevensite, kaolinite, halloysite, talc, and mica. As layered silicate compounds, smectite is preferred from the viewpoint of improving mixability with thermosetting resins, and montmorillonite is more preferred.

The layered silicate compound may be an unmodified compound whose surface is not modified, or may be a modified compound whose surface is modified with an organic component. Preferably, the layered silicate compound is surface-modified with an organic component from the viewpoint of obtaining excellent affinity with thermosetting resins and thermoplastic resins. Specifically, examples of the layered silicate compound include organo-modified smectite whose surface is modified with an organic component, and more preferably, organo-modified bentonite whose surface is modified with an organic component.

Organic components include organic cations (onium ions) such as ammonium, imidazolium, pyridinium, and phosphonium.

Examples of ammonium include dimethyl distearyl ammonium, distearyl ammonium, octadecyl ammonium, hexyl ammonium, octyl ammonium, 2-hexyl ammonium, dodecyl ammonium, trioctyl ammonium, etc. Examples of imidazolium include methyl stearyl imidazolium, distearyl imidazolium, methyl hexyl imidazolium, dihexyl imidazolium, methyl octylimidazolium, dioctylimidazolium, methyl dodecyl imidazolium, didodecyl imidazolium, etc. Examples of pyridinium include stearyl pyridinium, hexyl pyridinium, octyl pyridinium, dodecyl pyridinium, etc. Examples of phosphonium include dimethyl distearyl phosphonium, distearyl phosphonium, octadecyl phosphonium, hexyl phosphonium, octyl phosphonium, 2-hexyl phosphonium, dodecyl phosphonium, and trioctyl phosphonium. The organic cations can be used alone or in combination of two or more. Ammonium is preferred, and dimethyl distearyl ammonium is more preferred.

As the organically modified layered silicate compound, preferably, organically modified smectite whose surface is modified with ammonium, more preferably, organically modified bentonite whose surface is modified with dimethyl distearyl ammonium, can be mentioned.

The lower limit of the average particle size of the layered silicate compound is, for example, 1 nm, preferably 5 nm, and more preferably 10 nm. The upper limit of the average particle size of the layered silicate compound is, for example, 100 μm, preferably 50 μm, and more preferably 10 μm. The average particle size of the layered silicate compound is determined as the D50 value (cumulative 50% median size) based on the particle size distribution determined by, for example, a particle size distribution measurement method in a laser scattering method.

As the layered silicate compound, commercially available products can be used. For example, the Esben series (manufactured by Hojun Co., Ltd.) is a commercially available organic bentonite product.

The content of the layered silicate compound will be described later.

The thermoplastic resin contains acrylic resin as an essential component.

Acrylic resin also has a carboxyl group.

Examples of such acrylic resins include (meth)acrylic acid ester copolymers obtained by polymerizing monomer components including (meth)acrylic acid alkyl esters having linear or branched alkyl groups, carboxyl group-containing monomers, and other monomers (excluding carboxyl group-containing monomers).

Examples of the alkyl group of the (meth)acrylic acid alkyl ester include alkyl groups having 1 to 6 carbon atoms, such as methyl, ethyl, propyl, isopropyl, n-butyl, t-butyl, isobutyl, pentyl, and hexyl.

Examples of carboxyl group-containing monomers include acrylic acid, methacrylic acid, carboxyethyl acrylate, carboxypentyl acrylate, itaconic acid, maleic acid, fumaric acid, and crotonic acid.

The carboxyl group-containing monomers can be used alone or in combination of two or more types.

Other monomers (excluding carboxyl group-containing monomers) include, for example, glycidyl group-containing monomers such as glycidyl acrylate and glycidyl methacrylate, acid anhydride monomers such as maleic anhydride and itaconic anhydride, and monomers such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, and 12-hydroxy (meth)acrylate. Examples of monomers containing hydroxyl groups include lauryl or (4-hydroxymethylcyclohexyl)-methyl acrylate; monomers containing sulfonic acid groups include styrene sulfonic acid, allyl sulfonic acid, 2-(meth)acrylamido-2-methylpropanesulfonic acid, (meth)acrylamidopropanesulfonic acid, sulfopropyl (meth)acrylate, and (meth)acryloyloxynaphthalenesulfonic acid; monomers containing phosphoric acid groups include 2-hydroxyethyl acryloyl phosphate; and monomers containing styrene groups, such as acrylonitrile.

The other monomers can be used alone or in combination of two or more.

The lower limit of the acid value of the acrylic resin is 18, preferably 25. The upper limit of the acid value of the acrylic resin is, for example, 50, preferably 40.

If the acid value is equal to or greater than the lower limit, the fluidity of the encapsulating resin sheet can be reduced when the encapsulating resin sheet is heated to form a cured body (the curing step described below). As a result, when the encapsulating resin sheet is heated to form a cured body (the curing step described below), the amount of penetration of the cured body between the element and the substrate can be reduced to within a predetermined range.

On the other hand, if the acid value is less than the lower limit, the fluidity of the encapsulating resin sheet cannot be reduced when the encapsulating resin sheet is heated to form a cured body (the curing step described below). As a result, when the encapsulating resin sheet is heated to form a cured body (the curing step described below), the cured body penetrates between the element and the substrate to a greater extent than a predetermined extent, and the desired element and substrate cannot be obtained.

Furthermore, if the acid value is equal to or less than the upper limit, when the encapsulating resin sheet is heated to form a cured body (the curing step described below), the fluidity of the encapsulating resin sheet can be appropriately reduced, and an element or substrate can be obtained in which the penetration amount of the cured body falls within a predetermined range.

The acid value can be measured using the conventional indicator titration method using potassium hydroxide.

The lower limit of the glass transition temperature Tg of the acrylic resin is, for example, -70°C, preferably -50°C, and more preferably -30°C. The upper limit of the glass transition temperature Tg of the thermoplastic resin is, for example, 0°C, preferably 5°C, and more preferably -5°C. The glass transition temperature Tg is a theoretical value calculated, for example, by the Fox formula, and a specific calculation method thereof is described, for example, in JP 2016-175976 A.

The lower limit of the weight average molecular weight of the acrylic resin is, for example, 100,000, preferably 300,000, more preferably 1,000,000, and even more preferably 1,100,000. The upper limit of the weight average molecular weight of the thermoplastic resin is, for example, 1,400,000. The weight average molecular weight is measured by gel permeation chromatography (GPC) based on a standard polystyrene equivalent value.

The lower limit of the number of functional groups of the acrylic resin is, for example, 300 or more, preferably 500 or more. The upper limit of the number of functional groups of the acrylic resin is, for example, 1500 or less, preferably 1000 or less.

If the number of functional groups of the acrylic resin is equal to or greater than the lower limit, the fluidity of the encapsulating resin sheet can be reduced when the encapsulating resin sheet is heated to form a cured body (the curing step described below), and an element or substrate can be obtained in which the penetration amount of the cured body falls within a predetermined range.

In addition, if the number of functional groups of the acrylic resin is equal to or less than the upper limit, when the encapsulating resin sheet is heated to form a cured body (the curing step described below), the fluidity of the encapsulating resin sheet can be appropriately reduced, and an element or substrate can be obtained in which the penetration amount of the cured body falls within a predetermined range.

The number of functional groups of the acrylic resin can be calculated by the following formula (1).
Number of functional groups of acrylic resin=(weight average molecular weight of acrylic resin×acid value of acrylic resin)/56110 (1)
The thermoplastic resin may also contain, as an optional component, other thermoplastic resins such as natural rubber, butyl rubber, isoprene rubber, chloroprene rubber, ethylene-vinyl acetate copolymer, ethylene-acrylic acid copolymer, ethylene-acrylic acid ester copolymer, polybutadiene resin, polycarbonate resin, thermoplastic polyimide resin, polyamide resin (such as 6-nylon and 6,6-nylon), phenoxy resin, saturated polyester resin (such as PET), polyamideimide resin, fluororesin, and styrene-isobutylene-styrene block copolymer.

The other thermoplastic resins can be used alone or in combination of two or more types.

The thermoplastic resin preferably does not contain other thermoplastic resins and is made of acrylic resin (acrylic resin having a carboxyl group).

The content of the thermoplastic resin is adjusted to a level that allows a hardened body to be produced from the sealing resin sheet, as described below.

<Contents of thermosetting resin, layered silicate compound, and thermoplastic resin>
The lower limit of the content of the thermosetting resin in the material (sealing resin sheet) is, for example, 5 mass%, preferably 10 mass%, more preferably 15 mass%, and further preferably 17 mass%. The upper limit of the content of the thermosetting resin in the material (sealing resin sheet) is, for example, 30 mass%, preferably 25 mass%, and more preferably 20 mass%.

The lower limit of the content of the thermosetting resin relative to 100 parts by mass of the total of the thermosetting resin, the layered silicate compound, and the thermoplastic resin is, for example, 50 parts by mass, preferably 55 parts by mass, and more preferably 60 parts by mass. The upper limit of the content of the thermosetting resin relative to 100 parts by mass of the total of the thermosetting resin, the layered silicate compound, and the thermoplastic resin is, for example, 80 parts by mass, and preferably 70 parts by mass.

The lower limit of the content of the layered silicate compound in the material (sealing resin sheet) is, for example, 0.1 mass%, preferably 1 mass%, more preferably 2 mass%, and even more preferably 4 mass%. The upper limit of the content of the layered silicate compound in the material (sealing resin sheet) is, for example, 15 mass%, preferably 10 mass%, and more preferably 5 mass%.

The lower limit of the content of the layered silicate compound relative to 100 parts by mass of the total of the thermosetting resin, layered silicate compound, and thermoplastic resin is, for example, 5 parts by mass, preferably 8 parts by mass. The upper limit of the content of the layered silicate compound relative to 100 parts by mass of the total of the thermosetting resin, layered silicate compound, and thermoplastic resin is, for example, 40 parts by mass, preferably 20 parts by mass.

The lower limit of the proportion of thermoplastic resin in the material (sealing resin sheet) is, for example, 1 mass%, preferably 3 mass%. The upper limit of the proportion of thermoplastic resin in the material is, for example, 10 mass%, preferably 5 mass%.

The lower limit of the content of the thermoplastic resin relative to 100 parts by mass of the total of the thermosetting resin, layered silicate compound, and thermoplastic resin is, for example, 5 parts by mass, preferably 10 parts by mass. The upper limit of the content of the thermoplastic resin relative to 100 parts by mass of the total of the thermosetting resin, layered silicate compound, and thermoplastic resin is, for example, 30 parts by mass, preferably 20 parts by mass.

The lower limit of the proportion of thermoplastic resin relative to the total amount of thermoplastic resin and thermosetting resin is, for example, 10% by mass, preferably 13% by mass. The upper limit of the proportion of thermoplastic resin relative to the total amount of thermoplastic resin and thermosetting resin is, for example, 30% by mass, preferably 20% by mass.

The lower limit of the mass ratio of the acrylic resin to the layered silicate compound (acrylic resin/layered silicate compound) is, for example, 0.1, preferably 0.5. The upper limit of the mass ratio of the acrylic resin to the layered silicate compound is, for example, 5, preferably 3, more preferably 2, and even more preferably 1.

If the above mass ratio is equal to or greater than the lower limit, the fluidity of the encapsulating resin sheet can be reduced when the encapsulating resin sheet is heated to form a cured body (the curing step described below). As a result, when the encapsulating resin sheet is heated to form a cured body (the curing step described below), the amount of penetration of the cured body between the element and the substrate can be reduced to within a predetermined range.

If the mass ratio is equal to or less than the upper limit, the fluidity of the encapsulating resin sheet can be reduced when forming an encapsulated body from the encapsulating resin sheet (the encapsulating process described below). As a result, when forming an encapsulated body from the encapsulating resin sheet (the encapsulating process described below), the amount of encapsulated body penetration between the element and the substrate can be reduced to within a predetermined range (the encapsulated body penetration length X described below can be reduced).

<Other ingredients>
The material may further contain inorganic fillers other than the layered silicate compound, pigments, silane coupling agents, and other additives.

Examples of inorganic fillers include silicate compounds other than layered silicate compounds, such as orthosilicates, sorosilicates, and inosilicates, and silicon compounds (silicon compounds other than layered silicate compounds) such as quartz (silicic acid), silica (anhydrous silicic acid), and silicon nitride. Examples of inorganic fillers include alumina, aluminum nitride, and boron nitride. These can be used alone or in combination of two or more. Preferably, silicon compounds other than layered silicate compounds are used, and more preferably, silica is used.

The shape of the inorganic filler is not particularly limited, and examples include an approximately spherical shape, an approximately plate shape, an approximately needle shape, and an irregular shape. An approximately spherical shape is preferable.

The upper limit of the average value of the maximum length of the inorganic filler (synonymous with the average particle diameter if the filler is approximately spherical) is, for example, 50 μm, preferably 20 μm, and more preferably 10 μm. The lower limit of the average value of the maximum length of the inorganic filler is, for example, 0.1 μm, and preferably 0.5 μm. The average particle diameter of the inorganic filler is determined as the D50 value (cumulative 50% median diameter) based on the particle size distribution determined by, for example, a particle size distribution measurement method in a laser scattering method.

The inorganic filler may also include a first filler and a second filler having an average maximum length that is smaller than the average maximum length of the first filler.

The lower limit of the average maximum length of the first filler is, for example, 1 μm, preferably 3 μm. The upper limit of the average maximum length of the first filler is, for example, 50 μm, preferably 30 μm.

The upper limit of the average value of the maximum length of the second filler is, for example, 0.9 μm, preferably 0.8 μm. The lower limit of the average value of the maximum length of the second filler is, for example, 0.01 μm, preferably 0.1 μm.

The lower limit of the ratio of the average maximum length of the first filler to the average maximum length of the second filler is, for example, 2, preferably 5. The upper limit of the ratio of the average maximum length of the first filler to the average maximum length of the second filler is, for example, 50, preferably 20.

The materials of the first and second fillers may be the same or different.

Furthermore, the surface of the inorganic filler may be partially or entirely treated with a silane coupling agent or the like.

The lower limit of the inorganic filler content in the material (sealing resin sheet) is, for example, 40% by mass, preferably 50% by mass. The upper limit of the inorganic filler content in the material (sealing resin sheet) is, for example, 75% by mass.

The lower limit of the number of parts of the layered silicate compound contained per 100 parts by mass of the inorganic filler is, for example, 1 part by mass, preferably 5 parts by mass. The upper limit of the number of parts of the layered silicate compound contained per 100 parts by mass of the inorganic filler is, for example, 20 parts by mass, preferably 15 parts by mass, more preferably 10 parts by mass.

If the content ratio and/or the number of parts of the inorganic filler is equal to or greater than the above-mentioned lower limit, the sealing resin sheet 1 can flow in the process shown in FIG. 1C.

When the inorganic filler includes a first filler and a second filler, the lower limit of the content ratio of the first filler in the material (sealing resin sheet) is, for example, 20 mass%, preferably 30 mass%. The upper limit of the content ratio of the first filler in the material (sealing resin sheet) is, for example, 50 mass%. The lower limit of the content ratio of the second filler in the material (sealing resin sheet) is, for example, 10 mass%, preferably 15 mass%. The upper limit of the content ratio of the second filler in the material (sealing resin sheet) is, for example, 30 mass%. The lower limit of the number of parts of the second filler relative to 100 parts by mass of the first filler is, for example, 30 parts by mass, preferably 40 parts by mass, more preferably 50 parts by mass. The upper limit of the number of parts of the second filler relative to 100 parts by mass of the first filler is, for example, 70 parts by mass, preferably 60 parts by mass, more preferably 55 parts by mass.

The pigment may be, for example, a black pigment such as carbon black. The lower limit of the pigment particle diameter is, for example, 0.001 μm. The upper limit of the pigment particle diameter is, for example, 1 μm. The pigment particle diameter is the arithmetic mean diameter obtained by observing the pigment under an electron microscope. The lower limit of the pigment ratio to the material is, for example, 0.1% by mass. The upper limit of the pigment ratio to the material is, for example, 2% by mass.

Examples of the silane coupling agent include silane coupling agents containing an epoxy group. Examples of the silane coupling agent containing an epoxy group include 3-glycidoxydialkyldialkoxysilanes such as 3-glycidoxypropylmethyldimethoxysilane and 3-glycidoxypropylmethyldiethoxysilane, and 3-glycidoxyalkyltrialkoxysilanes such as 3-glycidoxypropyltrimethoxysilane and 3-glycidoxypropyltriethoxysilane. Preferably, 3-glycidoxyalkyltrialkoxysilane is used. The lower limit of the content of the silane coupling agent in the material is, for example, 0.1% by mass, preferably 0.5% by mass. The upper limit of the content of the silane coupling agent in the material is, for example, 10% by mass, preferably 5% by mass, more preferably 2% by mass.

To obtain this sealing resin sheet, the above-mentioned components are mixed in the above-mentioned ratios to prepare a material. Preferably, the above-mentioned components are thoroughly stirred to uniformly disperse the layered silicate compound in the thermosetting resin and the thermoplastic resin.

If necessary, a solvent (such as a ketone such as methyl ethyl ketone) is further added to prepare a varnish. The varnish is then applied to a release sheet (not shown) and then dried by heating to produce a sealing resin sheet having a sheet shape. On the other hand, it is also possible to form a sealing resin sheet from the material by kneading and extrusion without preparing a varnish.

The encapsulating resin sheet that is formed is in the B stage (semi-cured state), specifically, a state before the C stage. In other words, it is in a state before it is completely cured. The encapsulating resin sheet is formed into a B stage sheet from the A stage material by heating during the drying process and heating during the extrusion kneading process described above.

The lower limit of the thickness of the encapsulating resin sheet is, for example, 10 μm, preferably 25 μm, and more preferably 50 μm. The upper limit of the thickness of the encapsulating resin sheet is, for example, 3000 μm, preferably 1000 μm, more preferably 500 μm, and even more preferably 300 μm.

Next, a method for manufacturing an electronic element package 50 by encapsulating an electronic element, which is an example of an element, with an encapsulating resin sheet will be described with reference to Figures 1A to 1D.

In this method, as shown in FIG. 1A, first, a sealing resin sheet 1 is prepared (preparation step). The sealing resin sheet 1 has one side and the other side in the thickness direction that face each other in the thickness direction.

Separately, prepare an electronic element 21 as shown in FIG. 1B.

The electronic elements 21 include electronic components, and are mounted, for example, in multiples on a substrate 22. The multiple electronic elements 21 and substrate 22 are provided on an element mounting substrate 24 together with bumps 23. In other words, this element mounting substrate 24 includes multiple electronic elements 21, a substrate 22, and bumps 23.

The substrate 22 has a generally flat plate shape extending in the planar direction. One surface 25 in the thickness direction of the substrate 22 is provided with a terminal (not shown) that is electrically connected to an electrode (not shown) of the electronic element 21.

Each of the electronic elements 21 has a generally flat plate shape (chip shape) extending in the planar direction. The electronic elements 21 are arranged at intervals in the planar direction. The other thickness direction surfaces 28 of the electronic elements 21 are parallel to the one thickness direction surface 25 of the substrate 22. An electrode (not shown) is provided on the other thickness direction surface 28 of each of the electronic elements 21. The electrode of the electronic element 21 is electrically connected to the terminal of the substrate 22 via the bump 23 described next. The other thickness direction surface 28 of the electronic element 21 is separated from the one thickness direction surface 25 of the substrate 22 by a gap (space) 26.

The lower limit of the spacing between adjacent electronic elements 21 is, for example, 50 μm, preferably 100 μm, and more preferably 200 μm. The upper limit of the spacing between adjacent electronic elements 21 is, for example, 10 mm, preferably 5 mm, and more preferably 1 mm. If the spacing between adjacent electronic elements 21 is equal to or less than the above upper limit, more electronic elements 21 can be mounted on the substrate 22, thereby saving space.

The bumps 23 electrically connect the electrodes (not shown) of the multiple electronic elements 21 to the terminals of the substrate 22. The bumps 23 are disposed between the electrodes of the electronic elements 21 and the terminals of the substrate 22. Examples of materials for the bumps 23 include solder and metals such as gold. The thickness of the bumps 23 corresponds to the thickness (height) of the gaps 26. The thickness of the bumps 23 is set appropriately depending on the application and purpose of the element mounting substrate 24.

Next, as shown in FIG. 1B, the encapsulating resin sheet 1 is placed on the multiple electronic elements 21 (placement process). Specifically, the other thickness-wise surface of the encapsulating resin sheet 1 is brought into contact with one thickness-wise surface of the multiple electronic elements 21.

Next, as shown in FIG. 1C, the encapsulating resin sheet 1 and the element mounting board 24 are pressed (encapsulation process). Preferably, the encapsulating resin sheet 1 and the element mounting board 24 are heat-pressed.

For example, the sealing resin sheet 1 and the element mounting substrate 24 are sandwiched in the thickness direction and pressed by a press 27 having two flat plates. The flat plates of the press 27 are equipped with, for example, a heat source (not shown).

The pressing conditions (pressure, time, temperature, etc.) are not particularly limited, and conditions are selected that allow the sealing resin sheet 1 to penetrate between the multiple electronic elements 21 while not damaging the element mounting substrate 24. More specifically, the pressing conditions are set so that the sealing resin sheet 1 flows and penetrates between adjacent electronic elements 21, covering the peripheral side surfaces of each of the multiple electronic elements 21, while contacting one thickness-wise surface 25 of the substrate 22 that does not overlap the electronic elements 21 in a plan view.

Specifically, the lower limit of the pressing pressure is, for example, 0.01 MPa, preferably 0.05 MPa. The upper limit of the pressing pressure is, for example, 10 MPa, preferably 5 MPa. The lower limit of the pressing time is, for example, 0.3 minutes, preferably 0.5 minutes. The upper limit of the pressing time is, for example, 10 minutes, preferably 5 minutes.

Specifically, the lower limit of the heating temperature is, for example, 40°C, preferably 60°C. The upper limit of the heating temperature is, for example, 100°C, preferably 95°C.

When the sealing resin sheet 1 is pressed, the sealing resin sheet 1 is plastically deformed to correspond to the external shape of the electronic elements 21. The other surface in the thickness direction of the sealing resin sheet 1 is deformed into a shape that corresponds to one surface in the thickness direction and the peripheral side surfaces of the multiple electronic elements 21.

The sealing resin sheet 1 undergoes plastic deformation while maintaining the B stage.

As a result, the sealing resin sheet 1 covers the peripheral side surfaces of each of the multiple electronic elements 21 while contacting one thickness-wise surface 25 of the substrate 22 that does not overlap with the electronic elements 21 in a plan view.

As a result, the sealing body 31 that seals the electronic element 21 is formed (produced) from the sealing resin sheet 1. One side in the thickness direction of the sealing body 31 becomes a flat surface.

At this time, the sealing body 31 is permitted to slightly penetrate into the gap 26 (the gap between the electronic element 21 and the substrate 22). Specifically, the sealing body 31 is permitted to have a sealing body penetration length X (see FIG. 4C) that the sealing body 31 penetrates into the gap 26, based on the side edge 75 of the electronic element 21.

Specifically, the upper limit of the sealing body penetration length X is, for example, 30 μm, preferably 20 μm, more preferably 10 μm, even more preferably 5 μm, particularly preferably 3 μm, and most preferably 1 μm.

Then, as shown in FIG. 1D, the sealing body 31 is heated to form a hardened body 41 from the sealing body 31 (hardening process).

Specifically, the sealing body 31 and the element mounting board 24 are removed from the press 27, and then the sealing body 31 and the element mounting board 24 are heated in a dryer under atmospheric pressure.

The lower limit of the heating temperature (cure temperature) is, for example, 100°C, preferably 120°C. The upper limit of the heating temperature (cure temperature) is, for example, 200°C, preferably 180°C. The lower limit of the heating time is, for example, 10 minutes, preferably 30 minutes. The upper limit of the heating time is, for example, 180 minutes, preferably 120 minutes.

By heating the sealing body 31 as described above, a C-stage (fully cured) hardened body 41 is formed from the sealing body 31. One side in the thickness direction of the hardened body 41 is an exposed surface.

The edge of the sealing body 31 that has been allowed to slightly penetrate into the gap is allowed to penetrate even further into the gap 26 to become the hardened body 41, but the extent of this is kept as small as possible. Specifically, the hardened body 41 can be formed by subtracting the sealing body penetration length X from the hardened body penetration length Y (see FIG. 4D) of the hardened body 41 penetrating into the gap 26, based on the side edge 75 of the electronic element 21 (hereinafter referred to as the sealing body penetration amount (Y-X)).

Specifically, the upper limit of the hardened body penetration length Y is, for example, 60 μm, preferably 45 μm, more preferably 25 μm, even more preferably 15 μm, particularly preferably 10 μm, most preferably 5 μm, and even more preferably 1 μm. The lower limit of the hardened body penetration length Y is, for example, -40 μm, preferably -25 μm, more preferably -10 μm, and even more preferably -5 μm.

The upper limit of the amount of penetration of the sealing body (Y-X) is, for example, 40 μm, preferably 30 μm, more preferably 15 μm, even more preferably 10 μm, particularly preferably 5 μm, most preferably 3 μm, or even 1 μm.

The thermoplastic resin of this encapsulating resin sheet 1 contains an acrylic resin having a carboxyl group, and the acid value of the acrylic resin is 18 or more. Therefore, when this encapsulating resin sheet 1 is placed on the electronic element 21 and the encapsulating resin sheet 1 (sealing body 31) is heated to form a cured body 41 as shown in FIG. 1D, the amount of the cured body 41 penetrating into the gap 26 between the electronic element 21 and the substrate 22 can be reduced.

In more detail, if the acid value of the acrylic resin is 18 or more, the sealing resin sheet 1 has thixotropic properties, that is, it shows high viscosity when the shear force (shear rate) is low and shows low viscosity when the shear force (shear rate) is high.

Due to this thixotropy, the viscosity of the sealing resin sheet 1 can be reduced in the sealing process (when the shear force (shear rate) is high), allowing the sealing resin sheet 1 to penetrate between multiple electronic elements 21, while the viscosity of the sealing resin sheet 1 can be increased in the curing process (when the shear force (shear rate) is low), reducing the amount of penetration of the cured body 41 into the gap 26 between the electronic element 21 and the substrate 22.

More specifically, in the viscoelasticity measurement shown in Figure 5 (described in detail in the Examples below), the thixotropy described above improves as the degree (absolute value of the slope) of the decrease in the logarithm of viscosity (Pa·sec) with respect to the increase in the logarithm of shear rate (log D) (i.e., the slope (a) of the linear function (logarithm of viscosity = a × logarithm of shear rate + b) in Figure 5) increases.

The above slope (a) refers to the "decrease in the logarithm of viscosity (Pa·sec) with an increase in the logarithm of shear rate (log D)" in Table 3.

The lower limit of the above slope (a) is, for example, -250000, preferably -200000. The upper limit of the above slope (a) is, for example, -100000, preferably -140000, more preferably -160000.

If the degree is equal to or greater than the lower limit (particularly if it is equal to or greater than the lower limit and equal to or less than the upper limit), the thixotropy can be improved, and as described above, in the sealing process, the sealing resin sheet 1 can penetrate between the multiple electronic elements 21 within a predetermined range, while in the curing process, the amount of penetration of the cured body 41 into the gap 26 between the electronic elements 21 and the substrate 22 can be reduced.

More specifically, this thixotropy is achieved by the interaction between an acrylic resin having an acid value of 18 or more and a layered silicate compound.

Therefore, the interaction between the acrylic resin and the layered silicate compound will be explained with reference to Figures 2A to 2D along with the change in the morphology of the layered silicate compound in the sealing resin sheet 1.

First, in a dry state, as shown in FIG. 2A, the layered silicate compound 80 is in the form of aggregated plates (with interplanar spacing of 2 nm to 4 nm). At this time, each layer 81 in the layered silicate compound is bonded by hydrogen bonds.

Next, in the preparation step (see FIG. 1A), the layered silicate compound 80 swells as shown in FIG. 2B. Preferably, the layered silicate compound 80 swells by the above-mentioned solvent penetrating between the layers of the layered silicate compound 80.

Next, in the sealing process (see FIG. 1C), as shown in FIG. 2C, each layer 81 in the layered silicate compound 80 is collapsed by pressing, and the layered silicate compound 80 temporarily becomes dispersed (each layer 81 in the layered silicate compound 80 is separated). After that, as shown in FIG. 2D, each layer 81 of the separated layered silicate compound 80 is bonded to the acrylic resin 82 via hydrogen bonds. It is presumed that this causes the above-mentioned thixotropic property to be expressed.

In this case, if the acid value of the acrylic resin is 18 or more, it can exhibit sufficient thixotropy to achieve the above-mentioned effects.

The morphology shown in Figure 2D can be confirmed by atomic force microscope measurements, as described in detail in the examples below.

Furthermore, the morphology shown in FIG. 2D can be confirmed by a band (wavelength 3200 cm ⁻¹ to 3600 cm ⁻¹ ) attributed to hydrogen bonds in an infrared absorption spectrum, as will be described in detail in the Examples below.

Next, we will explain the second embodiment of the encapsulating resin sheet of the present invention (multilayer encapsulating resin sheet).

In the second embodiment, as shown in Figures 3A to 3D, an electronic element 21 is encapsulated by an encapsulating multilayer resin sheet 11 having an encapsulating resin sheet 1 and a second encapsulating resin sheet 12 in that order on one side in the thickness direction, and then a cured body 41 is formed.

The encapsulating multilayer resin sheet 11 includes an encapsulating resin sheet 1 and a second encapsulating resin sheet 12 arranged on the entire surface of one side in the thickness direction of the encapsulating resin sheet 1. Preferably, the encapsulating multilayer resin sheet 11 includes only the encapsulating resin sheet 1 and the second encapsulating resin sheet 12.

The material of the second sealing resin sheet 12 is the same as the material of the sealing resin sheet 1 (thermosetting resin composition) except that it does not contain a layered silicate compound. The lower limit of the ratio of the thickness of the second sealing resin sheet 12 to the thickness of the sealing resin sheet 1 is, for example, 0.5, preferably 1, and more preferably 2. The upper limit of the ratio of the thickness of the second sealing resin sheet 12 to the thickness of the sealing resin sheet 1 is, for example, 10, and preferably 5.

A method for manufacturing an electronic element cured body package 50 by encapsulating multiple electronic elements 21 with an encapsulating multilayer resin sheet 11 and then forming a cured body 41 is described with reference to Figures 3A to 3D.

As shown in FIG. 3A, a sealing multilayer resin sheet 11 is prepared. Specifically, the sealing resin sheet 1 and the second sealing resin sheet 12 are bonded together.

As shown in FIG. 3B, a number of electronic elements 21 are prepared to be mounted on a substrate 22.

Next, the sealing multilayer resin sheet 11 is placed on the electronic element 21 so that the other thickness-wise surface of the sealing resin sheet 1 contacts one thickness-wise surface of the electronic element 21.

Then, as shown in FIG. 3C, the sealing resin sheet 1 and the element mounting substrate 24 are pressed.

When pressed, the sealing resin sheet 1 flows and penetrates between the adjacent electronic elements 21. On the other hand, since the second sealing resin sheet 12 does not contain a layered silicate compound, its fluidity does not change significantly even when pressed, but remains low, and penetration between the adjacent electronic elements 21 is suppressed.

As a result, an encapsulant 31 that encapsulates multiple electronic elements 21 is formed from the encapsulating multilayer resin sheet 11.

If the sealing resin sheet 1 contains a filler at a ratio equal to or greater than the above-mentioned lower limit, and the second sealing resin sheet 12 contains a filler at a ratio equal to or greater than the above-mentioned lower limit, the sealing resin sheet 1 and the second sealing resin sheet 12 can flow by pressing as shown in FIG. 3C.

At this time, the sealing resin sheet 1 is in contact with the electronic element 21, while the second sealing resin sheet 12 is located on the opposite side of the electronic element 21 with respect to the sealing resin sheet 1. In other words, the edge of the sealing body 31 that faces the gap 26 is formed from the sealing resin sheet 1. On the other hand, one surface in the thickness direction of the sealing body 31 is formed from the second sealing resin sheet 12.

Then, as shown in FIG. 3D, the sealing body 31 is heated to form a hardened body 41 from the sealing body 31.

The sealing multilayer resin sheet 11 includes the sealing resin sheet 1 described above, so that the amount of the hardened body 41 that penetrates into the gap 26 can be reduced.

In particular, if the sealing resin sheet 1 and the second sealing resin sheet 12 contain a base resin of epoxy resin having a softening point of 50°C or more and 130°C or less, the sealing resin sheet 1 and the second sealing resin sheet 12 can flow in the process shown in Figure 3C. This allows the time for the process shown in Figure 3C to be shortened, and one surface in the thickness direction of the second sealing resin sheet 12 to be flattened in the process shown in Figure 3C.

Furthermore, if the sealing resin sheet 1 and the second sealing resin sheet 12 contain a phenolic resin as a curing agent together with the epoxy resin as the main agent, the cured body 41 has high heat resistance and high chemical resistance. Therefore, the cured body 41 has excellent sealing reliability.

3C, the second sealing resin sheet 12 is fluidized by the pressure, and one surface in the thickness direction becomes flat. In addition, in the process shown in FIG. 3C, in the sealing multilayer resin sheet 11, as described above, the sealing resin sheet 1, together with the second sealing resin sheet 12, is softened and fluidized by the pressure, and deforms to follow the external shape of the electronic element 21. In the process shown in FIG. 3C, the sealing resin sheet 1 is allowed to enter the gap 26 slightly.

In the following modified examples, the same reference numerals are used for the same components and steps as those in the first and second embodiments, and detailed descriptions thereof will be omitted. In addition, each modified example can achieve the same effects as those in the first and second embodiments, unless otherwise specified. Furthermore, the first and second embodiments and their modified examples can be appropriately combined.

In the first embodiment, the electronic element 21 is sealed with one layer of sealing resin sheet 1. However, although not shown, the electronic element 21 can also be sealed with multiple sealing resin sheets 1 (laminate sheets).

The second sealing resin sheet 12 in the sealing multilayer resin sheet 11 may also be multilayered.

As an example of an element, an electronic element 21 is provided that is disposed across a gap 26 from one surface 25 of the substrate 22 in the thickness direction, and is sealed with the sealing resin sheet 1. However, for example, although not shown, an electronic element 21 that contacts one surface 25 of the substrate 22 in the thickness direction can be provided, and this can be sealed with the sealing resin sheet 1.

Although electronic element 21 is given as an example of an element, a semiconductor element can also be given. Specific examples of electronic elements include surface acoustic wave filters (SAW filters).

The present invention will be described in more detail below with reference to the following Preparation Examples, Comparative Preparation Examples, Examples, and Comparative Examples. Note that the present invention is not limited to the Preparation Examples, Comparative Preparation Examples, Examples, and Comparative Examples. In addition, the specific numerical values of the blending ratio (content ratio), physical property values, parameters, etc. used in the following description can be replaced with the upper limit (a numerical value defined as "equal to or less than") or lower limit (a numerical value defined as "equal to or more than" or "exceeding") of the corresponding blending ratio (content ratio), physical property value, parameter, etc. described in the above "Form for carrying out the invention".

The ingredients used in the preparation examples and comparative preparation examples are listed below.

Layered silicate compound: Esben NX manufactured by Hojun Co., Ltd. (organic bentonite whose surface is modified with dimethyl distearyl ammonium)
Base resin: YSLV-80XY manufactured by Nippon Steel Chemical Co., Ltd. (bisphenol F type epoxy resin, high molecular weight epoxy resin, epoxy equivalent 200 g/eq., solid, softening point 80° C.)
Hardener: LVR-8210DL manufactured by Gun-ei Chemical Industry Co., Ltd. (novolac type phenolic resin, latent hardener, hydroxyl equivalent: 104 g/eq., solid, softening point: 60° C.)
Acrylic resin 1: HME-2006M manufactured by Negami Chemical Industrial Co., Ltd., acrylic acid ester copolymer (acrylic resin) containing a carboxyl group, acid value: 32, number of functional groups: 736, weight average molecular weight: 1,290,000, glass transition temperature (Tg): -13.9°C, methyl ethyl ketone solution with a solid content of 20% by mass. Acrylic resin 2: HME-2000M manufactured by Negami Chemical Industrial Co., Ltd., acrylic acid ester copolymer (acrylic resin) containing a carboxyl group, acid value: 20, number of functional groups: 367, weight average molecular weight: 1,030,000, glass transition temperature (Tg): 3.7°C, methyl ethyl ketone solution with a solid content of 20% by mass. Acrylic resin 3: HME-2004M manufactured by Negami Chemical Industrial Co., Ltd., acrylic acid ester copolymer (acrylic resin), acid value: 0, number of functional groups: 0, weight average molecular weight: 1,180,000, glass transition temperature (Tg): -3°C, methyl ethyl ketone solution with a solid content of 20% by mass. Silane coupling agent: KBM-403 (3-glycidoxypropyltrimethoxysilane) manufactured by Shin-Etsu Chemical Co., Ltd.
First filler: FB-8SM (spherical fused silica powder (inorganic filler), average particle size 7.0 μm)
Second filler: Inorganic filler (amorphous silica and surface-treated amorphous silica) obtained by surface-treating SC220G-SMJ (average particle size 0.5 μm) manufactured by Admatechs with 3-methacryloxypropyltrimethoxysilane (product name: KBM-503 manufactured by Shin-Etsu Chemical Co., Ltd.), inorganic particles surface-treated with 1 part by mass of a silane coupling agent per 100 parts by mass of inorganic filler. Curing accelerator: 2PHZ-PW (2-phenyl-4,5-dihydroxymethylimidazole) manufactured by Shikoku Chemical Industry Co., Ltd.
Solvent: methyl ethyl ketone (MEK)
Carbon black: #20 manufactured by Mitsubishi Chemical Corporation, particle size 50 nm
Preparation Examples 1 to 6 and Comparative Preparation Examples 1 to 4
A varnish of the material was prepared according to the formulation shown in Table 1. The varnish was applied to the surface of a release sheet and then dried at 120° C. for 2 minutes to produce a 65 μm-thick encapsulating resin sheet 1. The encapsulating resin sheet 1 was in the B stage.

Preparation Example 7
A varnish of the material was prepared according to the formulation shown in Table 2. The varnish was applied to the surface of a release sheet and then dried at 120° C. for 2 minutes to prepare a second sealing resin sheet 12 having a thickness of 195 μm. The second sealing resin sheet 12 was in a B-stage.

Examples 1 to 6 and Comparative Examples 1 and 2
In the combination of preparation examples shown in Table 3, the encapsulating resin sheet and the second encapsulating resin sheet were laminated together to prepare an encapsulating multilayer resin sheet having a thickness of 260 μm.

Evaluation <Measurement of hardened body penetration length>
The following steps A to E were carried out to measure the penetration length Y of the hardened body.

Step A: As shown in FIG. 4A, a sample sheet 61 measuring 10 mm in length, 10 mm in width, and 260 μm in thickness is prepared from the encapsulating multilayer resin sheet 11 of each example and comparative example.

Step B: As shown in Figure 4B, prepare a dummy element mounting substrate 74 in which a dummy element 71 measuring 3 mm in length, 3 mm in width, and 200 μm in thickness is mounted on a glass substrate 72 via a bump 23 with a thickness of 20 μm.

Step C: As shown in FIG. 4C, the sample sheet 61 is used to seal the dummy elements 71 on the dummy element mounting substrate 74 using a vacuum platen press at a temperature of 65°C, a pressure of 0.1 MPa, a degree of vacuum of 1.6 kPa, and a press time of 1 minute, forming a sealant 31 from the sample sheet 61.

Step D: As shown in FIG. 4D, the sealing body 31 is thermally cured by heating at 150° C. under atmospheric pressure for 1 hour to form a cured body 41 from the sealing body 31.

Step E: As shown in the enlarged view of Figure 4D, using the side edge 75 of the dummy element 71 as a reference, measure the penetration length Y of the hardened body 41 from the side edge 75 into the gap 26 between the dummy element 71 and the glass substrate 72.

The hardened body penetration length Y was evaluated according to the following criteria. The results are shown in Table 3.
⊚: The hardened body penetration length Y was 0 μm or more and 25 μm or less.
◯: The hardened body penetration length Y was more than 25 μm and 45 μm or less, or less than 0 μm and −25 μm or more.
Δ: The hardened body penetration length Y was more than 45 μm and 60 μm or less, or less than −25 μm and −40 μm or more.
×: The hardened body penetration length Y was more than 60 μm or less than −40 μm.

In the evaluation, "minus" means that a space (see the thick dashed line in FIG. 2D) is formed that protrudes outward from the side edge 75 of the dummy element 71. The absolute value of the "minus" corresponds to the protruding length of that space.

<Measurement of Encapsulation Intrusion Length>
For the encapsulating multilayer resin sheet 11 of each of the Examples and Comparative Examples, the following step F was further carried out between the above-mentioned steps C and D to measure the encapsulant penetration length X. The results are shown in Table 3.

Step F: Using the side edge 75 of the dummy element 71 as a reference, the penetration length X of the sealing body 31 from the side edge 75 into the gap 26 between the dummy element 22 and the glass substrate 72 was measured. The results are shown in Table 3.
⊚: The sealing body penetration length X was 0 μm or more and 10 μm or less.
Good: The sealing body penetration length X was more than 10 μm and 20 μm or less.
Δ: The sealing body penetration length X was more than 20 μm and 30 μm or less.
×: The penetration length X of the sealing body exceeded 30 μm.

<Amount of encapsulant penetration>
The penetration length of the plugged body (Y-X) was calculated by subtracting the penetration length of the plugged body obtained by the above-mentioned method from the penetration length of the hardened body obtained by the above-mentioned method. The results are shown in Table 3.
⊚: The amount of penetration of the sealing body (YX) was 0 μm or more and 15 μm or less.
◯: The amount of penetration of the sealing body (Y-X) was more than 15 μm and 30 μm or less.
Δ: The amount of penetration of the sealing body (Y-X) was more than 30 μm and 40 μm or less.
×: The amount of penetration of the sealing body (Y-X) exceeded 40 μm.

<Viscoelasticity measurement>
With respect to the sealing resin sheets 1 (B stage) of Example 1, Example 2, Comparative Example 1 and Comparative Example 2, the viscoelasticity was measured.

Specifically, the viscoelasticity measurements were performed using a rheometer (Mars III) (measurement conditions: 8 mm diameter plate, temperature 85°C, strain 0.005%). The results are shown in Figure 5. Table 3 shows the degree of decrease in the logarithm of viscosity (Pa sec) with respect to the increase in the logarithm of shear rate (log D) (i.e., the slope (a) of the linear function (logarithm of viscosity = a × logarithm of shear rate + b) in Figure 5).

<Atomic force microscope measurement>
AFM images (500 nm×500 nm) were measured with an atomic force microscope (contact mode) for the encapsulating resin sheets 1 of Example 1 and Comparative Example 1. The results are shown in FIG.

<Infrared absorption spectrum measurement>
Infrared absorption spectra were measured for the encapsulating resin sheets 1 of Example 1, Example 2, and Comparative Examples 1 to 4. The results are shown in Fig. 7 (wavelengths 3050 cm ^-1 to 3800 cm ^-1 ).

Observation 1) Measurement of the penetration length of the hardened body and the penetration length of the sealing body It can be seen that Examples 1 to 6, which contain an acrylic resin and a layered silicate compound with an acid value of 18 or more, have smaller penetration lengths of the hardened body and the sealing body than Comparative Example 1, which uses an acrylic resin with an acid value of less than 18, and Comparative Example 2, which does not use a layered silicate compound. This shows that the inclusion of an acrylic resin and a layered silicate compound with an acid value of 18 or more can reduce the amount of penetration of the hardened body between the element and the substrate.
2) Viscoelasticity Measurement According to Table 3, Preparation Examples 1 and 2, in which the acid value of the acrylic resin is 18 or more, have a higher degree of the above than Comparative Preparation Example 1, in which the acid value of the acrylic resin is less than 18. This shows that if the acid value of the acrylic resin is 18 or more, the thixotropy is high. And, according to Examples 1 and 2, in which the sealing resin sheets 1 of Preparation Examples 1 and 2 are used, it is found that the amount of the cured body penetrating between the element and the substrate can be reduced.
3) Atomic Force Microscope Measurement According to a comparison between FIG. 6A and FIG. 6B, in Preparation Example 1 in which the acid value of the acrylic resin is 18 or more, the periphery of the layered silicate compound 80 has a higher elastic modulus than in Comparative Preparation Example 1 in which the acid value of the acrylic resin is less than 18. From this, as shown in FIG. 2D, it can be seen that each layer of the layered silicate compound is bonded via hydrogen bonds with the acrylic resin. It is also presumed that this causes thixotropy. From this, it can be seen that according to Example 1 and Example 2 using the sealing resin sheets 1 of Preparation Examples 1 and 2, the amount of intrusion of the cured body between the element and the substrate can be reduced.
4) Infrared absorption spectrum measurement According to FIG. 7, it can be seen that Preparation Example 1 and Preparation Example 2 containing an acrylic resin having an acid value of 18 or more and a layered silicate compound have a broader band (wavelength 3200 cm ^-1 to 3600 cm ^-1 ) attributed to hydrogen bonds than Preparation Example 1 containing an acrylic resin having an acid value of less than 18 and a layered silicate compound, and Comparative Preparation Examples 2 to 4 not containing a layered silicate compound. From this, it can be seen that if an acrylic resin having an acid value of 18 or more and a layered silicate compound are included, as shown in FIG. 2D, each layer of the layered silicate compound is bonded through a hydrogen bond with the acrylic resin. It is also presumed that this causes the thixotropic property to be expressed. And, according to Example 1 and Example 2 using such sealing resin sheets 1 of Preparation Examples 1 and 2, it can be seen that the amount of intrusion of the cured body between the element and the substrate can be reduced.

1 Sealing resin sheet 21 Electronic element

Claims (3)

A sealing resin sheet containing a thermosetting resin, a layered silicate compound, and a thermoplastic resin for sealing an element,
The thermoplastic resin includes an acrylic resin,
The acrylic resin has a carboxyl group,
The acrylic resin has an acid value of 18 or more. The sealing resin sheet according to claim 1, characterized in that the number of functional groups of the acrylic resin is 300 or more. 3. The sealing resin sheet according to claim 1, wherein a mass ratio of the acrylic resin to the layered silicate compound (acrylic resin/layered silicate compound) is 0.1 or more and 2 or less.

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