JP7600111B2 - Multi-layer resin sheet for sealing - Google Patents

Description

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

It has been known to use a sealing sheet containing a thermosetting resin to encapsulate semiconductor elements or electronic components mounted on a substrate by pressing, and then to thermally cure the thermosetting resin 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 semiconductor elements and electronic components used in them to be made smaller. Accordingly, there is a demand for improved dimensional accuracy when cured for the resin (cured body) that protects the semiconductor elements and electronic components. Specifically, there is a demand to further reduce the amount of cured body that penetrates 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 a multilayer resin sheet for sealing that can reduce the penetration of the cured body between elements, such as semiconductor elements and electronic components, and substrates.

The present invention [1] is a sealing multilayer resin sheet comprising a first sealing resin sheet and a second sealing resin sheet in order in one direction of the thickness direction, the first sealing resin sheet containing a layered silicate compound and a first inorganic filler, the second sealing resin sheet containing a second inorganic filler, the content ratio (B) of the first inorganic filler relative to the first sealing resin sheet is 50% by mass or more, the content ratio (A) of the second inorganic filler relative to the second sealing resin sheet is 60% by mass or more, and the content ratio (B) of the first inorganic filler relative to the first sealing resin sheet and the content ratio (A) of the second inorganic filler relative to the second sealing resin sheet satisfy the following formula (1).

0.4A+1.7B<160 (1)
The present invention [2] relates to the above-mentioned [1], wherein the thickness of the first sealing resin sheet is 30 μm or more and 100 μm or less, and the thickness of the second sealing resin sheet is 50 μm or more and 500 μm or less. The encapsulating multilayer resin sheet according to the present invention includes the encapsulating multilayer resin sheet according to the present invention.

The present invention [3] includes the encapsulating multilayer resin sheet described in [1] or [2] above, in which the linear expansion coefficient of the first encapsulating resin sheet is 80 ppm/°C or less, and the linear expansion coefficient of the second encapsulating resin sheet is 50 ppm/°C or less.

In the sealing multilayer resin sheet of the present invention, the first sealing resin sheet contains a layered silicate compound and a first inorganic filler, and the second sealing resin sheet contains a second inorganic filler.

In addition, the content ratio (B) of the first inorganic filler in the first sealing resin sheet and the content ratio (A) of the second inorganic filler in the second sealing resin sheet are predetermined ratios.

In addition, the content ratio (B) of the first inorganic filler in the first sealing resin sheet and the content ratio (A) of the second inorganic filler in the second sealing resin sheet have a predetermined relationship.

Therefore, when this encapsulating multilayer 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 a process of producing an electronic element package by encapsulating a plurality of electronic elements using one embodiment of the encapsulating multilayer resin sheet of the present invention, in which FIG. 1A shows a process of preparing an encapsulating multilayer resin sheet, FIG. 1B shows a process of preparing electronic elements, FIG. 1C shows a process of pressing the encapsulating multilayer resin sheet to form an encapsulated body, and FIG. 1D shows a process of heating the encapsulated body to form a cured body. FIG. 2 is a graph showing the relationship between the content ratio (B) of the first inorganic filler in the first sealing resin sheet 1 and the content ratio (A) of the second inorganic filler in the second sealing resin sheet 12. 3 to 3D 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. 3A shows a step of preparing an encapsulating multilayer resin sheet (Step A), FIG. 3B shows a step of preparing an electronic element (dummy element) (Step B), FIG. 3C shows a step of pressing the encapsulating multilayer resin sheet to form an encapsulated body (Step C), and FIG. 3D shows a step of heating the encapsulated body to form a cured body (Step D). FIG. 4 is a graph showing the relationship between the content ratio (B) of the first inorganic filler relative to the first material and the content ratio (A) of the second inorganic filler relative to the second material in Examples 1 to 33 and Comparative Examples 1 to 23.

The encapsulating multilayer resin sheet of the present invention is a resin sheet for encapsulating elements and has an approximately plate shape (film shape) extending in a planar direction perpendicular to the thickness direction.

This sealing multilayer resin sheet comprises a first sealing resin sheet and a second sealing resin sheet arranged in sequence toward one side of the thickness direction.

In detail, the encapsulating multilayer resin sheet includes a first encapsulating resin sheet and a second encapsulating resin sheet formed on one surface in the thickness direction of the first encapsulating resin sheet. Preferably, the encapsulating multilayer resin sheet includes a first encapsulating resin sheet and a second encapsulating resin sheet.

The first sealing resin sheet has an approximately plate shape (film shape) extending in a planar direction perpendicular to the thickness direction.

The material of the first sealing resin sheet (hereinafter referred to as the first material) includes a layered silicate compound and a first inorganic filler.

When the first material contains a first resin component (resin matrix) described later, the layered silicate compound is dispersed in the first resin component. The layered silicate compound is also a flow regulator when forming a sealing body and a cured body (described later) from the first sealing resin sheet. Specifically, it is a curing flow reducer that reduces the flowability of the cured body when the first 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 the 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. Preferred is ammonium, and more preferred is dimethyl distearyl ammonium.

As the organically modified layered silicate compound, preferably, an organically modified smectite whose surface is modified with ammonium, and more preferably, an organically modified bentonite whose surface is modified with dimethyl distearyl ammonium, is used.

The lower limit of the average particle diameter of the layered silicate compound is, for example, 1 nm, preferably 5 nm, more preferably 10 nm. The upper limit of the average particle diameter of the layered silicate compound is, for example, 100 μm, preferably 50 μm, more preferably 10 μm. The average particle diameter of the layered silicate compound 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.

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 lower limit of the content of the layered silicate compound in the first material is, for example, 1 mass%, preferably 3 mass%. The upper limit of the content of the layered silicate compound in the first material is, for example, 15 mass%, preferably 10 mass%.

The first inorganic filler is an inorganic filler other than a layered silicate compound, and examples thereof include silicate compounds other than layered silicate compounds such as orthosilicates, sorosilicates, and inosilicates, and silicon compounds such as quartz (silicic acid), silica (anhydrous silicic acid), and silicon nitride (silicon compounds other than layered silicate compounds). Examples of the first inorganic filler 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.

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

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

The first 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.

If the above ratio is within the above range, the amount of hardened body penetrating between the element and the substrate can be further reduced.

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

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

The content ratio (B) of the first inorganic filler relative to the first material will be described later.

In addition, as described in more detail below, the content ratio (B) of the first inorganic filler relative to the first material and the content ratio (A) of the second inorganic filler relative to the second material (described later) have a predetermined relationship.

The lower limit of the number of parts of the first inorganic filler per 100 parts by mass of the layered silicate compound is, for example, 1000 parts by mass, preferably 1050 parts by mass, more preferably 1100 parts by mass, even more preferably 1150 parts by mass, particularly preferably 1200 parts by mass, and most preferably 1250 parts by mass. The upper limit of the number of parts of the first inorganic filler per 100 parts by mass of the layered silicate compound is, for example, 1500 parts by mass, preferably 1450 parts by mass, more preferably 1400 parts by mass, and even more preferably 1350 parts by mass.

If the content of the first inorganic filler is within the above range (e.g., 1000 to 1500 parts by mass) per 100 parts by mass of the layered silicate compound, the amount of the hardened body penetrating between the element and the substrate can be further reduced. Also, if the content of the first inorganic filler is within the above range (e.g., 1000 to 1500 parts by mass) per 100 parts by mass of the layered silicate compound, the amount of the hardened body penetrating between the element and the substrate can be controlled to an appropriate value.

When the first inorganic filler includes a first filler and a second filler, the lower limit of the content ratio of the first filler in the first material is, for example, 32.5 mass%, preferably 33 mass%, more preferably 36 mass%, and even more preferably 40 mass%. The upper limit of the content ratio of the first filler in the first material is, for example, 52 mass%, preferably 50 mass%, more preferably 47 mass%, and even more preferably 43 mass%. The lower limit of the content ratio of the second filler in the first material is, for example, 1 mass%, preferably 18 mass%, more preferably 20 mass%, and even more preferably 22 mass%. The upper limit of the content ratio of the second filler in the first material is, for example, 26.5 mass%, preferably 25 mass%, and more preferably 24 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, and even more preferably 50 parts by mass. The upper limit of the number of parts of the second filler contained per 100 parts by mass of the first filler is, for example, 70 parts by mass, preferably 60 parts by mass, and more preferably 55 parts by mass.

The first material preferably comprises a first resin component as a resin matrix.

The first resin component includes a thermosetting resin and a thermoplastic resin. Preferably, the first resin component is composed of a thermosetting resin 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.

As the thermosetting resin, an epoxy resin is preferably used. 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, dicyclopentadiene type epoxy resin, and glycidylamine type epoxy resin (e.g., triglycidylaminophenol). These base agents can be used alone or in combination of two or more types. As the base agent, preferably, bifunctional epoxy resins, more preferably, bisphenol F type epoxy resins, can be used.

The lower limit of the epoxy equivalent of the base agent is, for example, 10 g/eq., preferably 80 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 72°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 encapsulating resin sheet 1 can flow in the process shown in Figure 1C. Therefore, one surface in the thickness direction of the encapsulating resin sheet 1 can be flattened in the process shown in Figure 1C.

The lower limit of the proportion of the main agent in the first material is, for example, 1 mass%, preferably 2 mass%. The upper limit of the proportion of the main agent in the first 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 phenolic novolac resin and trishydroxyphenylmethane 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.

These hardeners can be used alone or in combination of two or more. As hardeners, phenol novolac resin and trishydroxyphenylmethane type novolac resin are preferably used in combination.

When phenol novolac resin and trishydroxyphenylmethane type novolac resin are used in combination, the lower limit of the content ratio of phenol novolac resin to a total of 100 parts by mass of phenol novolac resin and trishydroxyphenylmethane type novolac resin is, for example, 10 parts by mass. The upper limit of the content ratio of phenol novolac resin to a total of 100 parts by mass of phenol novolac resin and trishydroxyphenylmethane type novolac resin is, for example, 30 parts by mass. The lower limit of the content ratio of trishydroxyphenylmethane type novolac resin to a total of 100 parts by mass of phenol novolac resin and trishydroxyphenylmethane type novolac resin is, for example, 70 parts by mass. The upper limit of the content ratio of trishydroxyphenylmethane type novolac resin to a total of 100 parts by mass of phenol novolac resin and trishydroxyphenylmethane type novolac resin is, for example, 90 parts by mass.

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). Preferably, an imidazole compound is used. 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 lower limit of the content of the thermosetting resin in the first material is, for example, 10 mass%, preferably 13 mass%, more preferably 16 mass%, and even more preferably 20 mass%. The upper limit of the content of the thermosetting resin in the first material is, for example, 37 mass%, preferably 33 mass%, more preferably 30 mass%, and even more preferably 25 mass%.

Examples of thermoplastic resins include 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, acrylic resin, saturated polyester resin (such as PET), polyamideimide resin, fluororesin, styrene-isobutylene-styrene block copolymer, etc. These thermoplastic resins can be used alone or in combination of two or more types.

As a thermoplastic resin, preferably, an acrylic resin is used from the viewpoint of improving dispersibility with the thermosetting resin.

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

Examples of alkyl groups 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 other monomers include carboxyl group-containing monomers such as acrylic acid, methacrylic acid, carboxyethyl acrylate, carboxypentyl acrylate, itaconic acid, maleic acid, fumaric acid, and crotonic acid; glycidyl group-containing monomers such as glycidyl acrylate and glycidyl methacrylate; acid anhydride monomers such as maleic anhydride and itaconic anhydride; 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, and the like. ) 10-hydroxydecyl acrylate, 12-hydroxylauryl (meth)acrylate, or (4-hydroxymethylcyclohexyl)-methyl acrylate or other hydroxyl group-containing monomers, for example, styrene sulfonic acid, allyl sulfonic acid, 2-(meth)acrylamido-2-methylpropanesulfonic acid, (meth)acrylamidopropanesulfonic acid, sulfopropyl (meth)acrylate, (meth)acryloyloxynaphthalenesulfonic acid or other sulfonic acid group-containing monomers, 2-hydroxyethylacryloylphosphate or other phosphoric acid group-containing monomers, for example, styrene monomers, and for example, acrylonitrile. These may be used alone or in combination of two or more.
Preferably, a carboxyl group-containing monomer or a hydroxyl group-containing monomer is used, and more preferably, a carboxyl group-containing monomer is used.

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

More preferably, the thermoplastic resin is an acrylic resin containing a carboxyl group, and even more preferably, the thermoplastic resin is an acrylic resin containing a carboxyl group.

The lower limit of the glass transition temperature Tg of the thermoplastic 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 2016-1976 A.

The lower limit of the weight average molecular weight of the thermoplastic 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 proportion of the thermoplastic resin in the first material is, for example, 1 mass%, preferably 2 mass%, more preferably 3 mass%. The upper limit of the proportion of the thermoplastic resin in the first material is, for example, 7 mass%, preferably 6 mass%, more preferably 5 mass%.

In the first sealing resin sheet, the lower limit of the proportion of the thermoplastic resin with respect to the total amount of the thermoplastic resin and the thermosetting resin is, for example, 5 mass %, or preferably 10 mass %.
In the first sealing resin sheet, the upper limit of the proportion of the thermoplastic resin with respect to the total amount of the thermoplastic resin and the thermosetting resin is, for example, 30 mass %, or preferably 20 mass %.

The first material may further contain pigments, silane coupling agents, and other additives.

Examples of pigments include black pigments 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 ratio of the pigment to the first material is, for example, 0.1% by mass. The upper limit of the ratio of the pigment to the first 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 first 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 first material is, for example, 10% by mass, preferably 5% by mass, more preferably 2% by mass.

The lower limit of the glass transition temperature of the first material is, for example, 100°C, preferably 120°C, more preferably 145°C, and even more preferably 150°C. The upper limit of the glass transition temperature of the first material is, for example, 180°C, preferably 160°C.

The second sealing resin sheet has an approximately plate shape (film shape) extending in a planar direction perpendicular to the thickness direction.

The second sealing resin sheet is adhered to the first sealing resin sheet so that the entire surface of one thickness direction of the first sealing resin sheet is in contact with the entire surface of the other thickness direction of the second sealing resin sheet.

The material of the second sealing resin sheet (hereinafter referred to as the second material) does not contain a layered silicate compound but contains a second inorganic filler.

The second inorganic filler may be the same as the first inorganic filler described above, and preferably, silica.

The average maximum length of the second inorganic filler (if it is approximately spherical, the average particle diameter; similar) is the same as the average maximum length of the first inorganic filler described above.

Similarly, the second inorganic filler, like the first inorganic filler, may contain a first filler and a second filler having an average maximum length that is smaller than the average maximum length of the first filler.

In the second inorganic filler, the average value of the maximum length of the first filler and the average value of the maximum length of the second filler are the same as the average value of the maximum length of the first filler and the average value of the maximum length of the second filler in the first inorganic filler.

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

The content ratio (A) of the second inorganic filler relative to the second material will be described later.

In addition, as described in more detail below, the content ratio (B) of the first inorganic filler relative to the first material and the content ratio (A) of the second inorganic filler relative to the second material have a predetermined relationship.

When the second inorganic filler contains a first filler and a second filler, the lower limit of the content ratio of the first filler in the second material is, for example, 38 mass%, preferably 40 mass%, more preferably 50 mass%, even more preferably 52 mass%, and particularly preferably 54 mass%. The upper limit of the content ratio of the first filler in the second material is, for example, 60 mass%, preferably 56 mass%. The lower limit of the content ratio of the second filler in the second material is, for example, 20 mass%, preferably 22 mass%, more preferably 25 mass%, and even more preferably 28 mass%. The upper limit of the content ratio of the second filler in the second material is, for example, 35 mass%, preferably 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, and more preferably 50 parts by mass. The upper limit of the number of parts of the second filler contained per 100 parts by mass of the first filler is, for example, 70 parts by mass, preferably 60 parts by mass, and more preferably 55 parts by mass.

The second material preferably comprises a second resin component as a resin matrix.

The second resin component includes a thermosetting resin and a thermoplastic resin. Preferably, the second resin component is made of a thermosetting resin and a thermoplastic resin.

The thermosetting resin may be any of the thermosetting resins exemplified in the first resin component described above, and 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. The thermosetting resin may be used alone or in combination of two or more types.

Examples of base agents include those exemplified in the first resin component described above.

The base agent can be used alone or in combination of two or more types. Preferably, a difunctional epoxy resin and a multifunctional epoxy resin having three or more functionalities are used in combination, more preferably, a difunctional epoxy resin and a trifunctional epoxy resin are used in combination, and even more preferably, a bisphenol F type epoxy resin and a glycidyl amine type epoxy resin are used in combination.

When a bifunctional epoxy resin and a trifunctional epoxy resin are used in combination as the base resin, the lower limit of the ratio of the bifunctional epoxy resin to 100 parts by mass of the total amount of the bifunctional epoxy resin and the trifunctional epoxy resin is, for example, 40 parts by mass. The upper limit of the ratio of the bifunctional epoxy resin to 100 parts by mass of the total amount of the bifunctional epoxy resin and the trifunctional epoxy resin is, for example, 60 parts by mass. The lower limit of the ratio of the trifunctional epoxy resin to 100 parts by mass of the total amount of the bifunctional epoxy resin and the trifunctional epoxy resin is, for example, 40 parts by mass. The upper limit of the ratio of the trifunctional epoxy resin to 100 parts by mass of the total amount of the bifunctional epoxy resin and the trifunctional epoxy resin is, for example, 60 parts by mass.

The epoxy equivalent and softening point of the base resin are the same as the ranges exemplified for the first resin component above.

The lower limit of the proportion of the main agent in the second material is, for example, 4 mass%, preferably 6 mass%. The upper limit of the proportion of the main agent in the second material is, for example, 20 mass%, preferably 15 mass%, more preferably 10 mass%, and even more preferably 8 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%.

Examples of hardeners include the hardeners exemplified in the first resin component described above, and preferably phenol novolac resin.

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, more preferably 60 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, 85 parts by mass.

Examples of the thermoplastic resin include the thermoplastic resins exemplified in the first resin component described above, preferably acrylic resin, and more preferably acrylic resin containing a carboxyl group.

The lower limit of the proportion of thermoplastic resin in the second material is, for example, 0.1 mass%, preferably 0.6 mass%. The upper limit of the proportion of thermoplastic resin in the second material is, for example, 1.5 mass%, preferably 5 mass%.

In the second sealing resin sheet, the lower limit of the proportion of the thermoplastic resin relative to the total amount of the thermoplastic resin and the thermosetting resin is, for example, 1 mass%, preferably 5 mass%. In the second sealing resin sheet, the upper limit of the proportion of the thermoplastic resin relative to the total amount of the thermoplastic resin and the thermosetting resin is, for example, 20 mass%, preferably 10 mass%.

The second material may further contain pigments, silane coupling agents, and other additives.

Examples of pigments include the pigments exemplified in the first material above.

The particle size of the pigment is the same as the range exemplified for the first material above.

The lower limit of the ratio of the pigment to the second material is, for example, 0.1% by mass. The upper limit of the ratio of the pigment to the second material is, for example, 2% by mass.

Examples of the silane coupling agent include the silane coupling agents exemplified in the first material described above, and preferably 3-glycidoxyalkyltrialkoxysilane. The lower limit of the content of the silane coupling agent in the second 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 second material is, for example, 10% by mass, preferably 5% by mass, more preferably 2% by mass.

The glass transition temperature of the second material is lower than the glass transition temperature of the first material, and the lower limit of the glass transition temperature of the second material is, for example, 100°C, preferably 130°C. The upper limit of the glass transition temperature of the second material is, for example, 160°C, preferably 150°C.

Then, to obtain the encapsulating multilayer resin sheet, a first encapsulating resin sheet and a second encapsulating resin sheet are separately manufactured.

To manufacture the first sealing resin sheet, the above-mentioned components are mixed in the above-mentioned ratio to prepare the first material. Preferably, the above-mentioned components are thoroughly stirred to uniformly disperse the layered silicate compound in the first resin component (thermosetting resin and 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 first sealing resin sheet having a sheet shape. On the other hand, the first sealing resin sheet can also be formed from the first material by kneading extrusion without preparing a varnish.

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

To produce the second sealing resin sheet, the above-mentioned components are mixed in the above-mentioned ratios to prepare the second material.

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 second sealing resin sheet having a sheet shape. On the other hand, the second sealing resin sheet can also be formed from the second material by kneading extrusion without preparing a varnish.

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

Next, to obtain a sealing multilayer resin sheet, a second sealing resin sheet is placed (transferred) on one side in the thickness direction of the first sealing resin sheet.

This results in a multilayer resin sheet for sealing.

In such a sealing multilayer resin sheet, the lower limit of the thickness of the first sealing resin sheet is, for example, 10 μm, preferably 25 μm, and more preferably 30 μm. The upper limit of the thickness of the first sealing resin sheet is, for example, 3000 μm, preferably 1000 μm, more preferably 500 μm, even more preferably 300 μm, and particularly preferably 100 μm.

The lower limit of the thickness of the second sealing resin sheet is, for example, 10 μm, preferably 30 μm, and more preferably 50 μm. The upper limit of the thickness of the second sealing resin sheet is, for example, 3000 μm, preferably 1000 μm, and more preferably 500 μm.

The lower limit of the ratio of the thickness of the second sealing resin sheet to the thickness of the first sealing resin sheet is, for example, 0.5, preferably 1, and more preferably more than 1. The upper limit of the ratio of the thickness of the second sealing resin sheet to the thickness of the first sealing resin sheet is, for example, 20, preferably 10, and more preferably 5.

The lower limit of the thickness of such a sealing multilayer resin sheet is, for example, 20 μm, preferably 30 μm, and more preferably 50 μm. The upper limit of the thickness of the sealing multilayer resin sheet is, for example, 6000 μm, preferably 3000 μm, more preferably 1500 μm, even more preferably 1000 μm, particularly preferably 500 μm, and most preferably 300 μm.

Preferably, the thickness of the first sealing resin sheet is within a specific range within the range described above, and the thickness of the second sealing resin sheet is within a specific range within the range described above.

Specifically, the thickness of the second sealing resin sheet is greater than the thickness of the first sealing resin sheet. Specifically, when the lower limit of the thickness of the first sealing resin sheet is, for example, 30 μm, preferably 40 μm, and the upper limit of the thickness of the first sealing resin sheet is, for example, 100 μm, preferably 70 μm, the lower limit of the thickness of the second sealing resin sheet is, for example, 50 μm, and the upper limit of the thickness of the second sealing resin sheet is 500 μm, preferably 300 μm. The lower limit of the thickness of the sealing multilayer resin sheet is, for example, 80 μm, preferably 100 μm, more preferably 200 μm. The upper limit of the thickness of the sealing multilayer resin sheet is, for example, 600 μm, preferably 300 μm.

In such a case, warping of the sealing multilayer resin sheet can be suppressed. In addition, the first inorganic filler can be suppressed from being discharged from the first sealing resin sheet.

The upper limit of the linear expansion coefficient of the first sealing resin sheet is 90 ppm/°C, preferably 80 ppm/°C, more preferably 75 ppm/°C, even more preferably 70 ppm/°C, and particularly preferably 60 ppm/°C. The upper limit of the linear expansion coefficient of the first sealing resin sheet is preferably low. If the upper limit of the linear expansion coefficient of the first sealing resin sheet is too low, the amount of the first inorganic filler becomes too large, and the moldability of the sheet decreases. The lower limit of the linear expansion coefficient of the first sealing resin sheet may be, for example, 20 ppm/°C.

The upper limit of the linear expansion coefficient of the second sealing resin sheet is, for example, 50 ppm/° C., preferably 40 ppm/° C., and more preferably 20 ppm/° C. The upper limit of the linear expansion coefficient of the second sealing resin sheet is preferably low. If the upper limit of the linear expansion coefficient of the second sealing resin sheet is too low, the amount of the second inorganic filler becomes too large, and the moldability of the sheet is reduced.
The lower limit of the linear expansion coefficient of the second sealing resin sheet may be, for example, 5 ppm/°C.

If the linear expansion coefficient of the first sealing resin sheet is equal to or less than the upper limit and the linear expansion coefficient of the second sealing resin sheet is equal to or less than the upper limit, warping of the sealing multilayer resin sheet can be suppressed.

The method for measuring the linear expansion coefficient will be described in detail in the examples described below.

Next, a method for encapsulating an electronic element, as an example of an element, with an encapsulating multilayer resin sheet to manufacture an electronic element package 50 will be described with reference to Figures 1A to 1D.

In this method, as shown in Fig. 1A, first, a sealing multilayer resin sheet 11 is prepared, which includes a first sealing resin sheet 1 and a second sealing resin sheet 12 arranged in order in one direction in the thickness direction (preparation step). The sealing multilayer resin sheet 11 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 Figure 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 the substrate 22 are provided on an element mounting substrate 24 together with bumps 23. In other words, the element mounting substrate 24 includes the multiple electronic elements 21, the substrate 22, and the 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 from one another in the planar direction. The other thickness direction surfaces 28 of the electronic elements 21 are parallel to 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 a terminal of the substrate 22 via a bump 23, which will be 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.

1B, the encapsulating multilayer resin sheet 11 is placed on the multiple electronic elements 21 (placement process). Specifically, the other thickness-wise surface (the first encapsulating resin sheet 1 side) of the encapsulating multilayer resin sheet 11 is brought into contact with one thickness-wise surface of the multiple electronic elements 21.

Next, as shown in FIG. 1C, the encapsulating multilayer resin sheet 11 and the element mounting substrate 24 are pressed (encapsulating process). Preferably, the encapsulating multilayer resin sheet 11 and the element mounting substrate 24 are heat-pressed.

For example, the sealing multilayer resin sheet 11 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).

By pressing the sealing multilayer resin sheet 11, the first sealing resin sheet 1 is plastically deformed to correspond to the external shape of the electronic elements 21. The other thickness-wise surface of the first sealing resin sheet 1 is deformed into a shape corresponding to one thickness-wise surface and the peripheral side surfaces of the multiple electronic elements 21.

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

As a result, the first 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 planar view.

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

The pressing conditions (pressure, time, temperature, etc.) are not particularly limited, and conditions are selected that allow the first 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 first sealing resin sheet 1 flows and penetrates between the adjacent electronic elements 21, covering the peripheral side surfaces of each of the multiple electronic elements 21, while contacting one thickness direction surface 25 of the substrate 22 that does not overlap with 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.

As a result, a sealing body 31 that seals the multiple electronic elements 21 is formed (produced) from the sealing multilayer resin sheet 11. One surface 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 (the gap between the electronic element 21 and the substrate 22) 26. Specifically, the sealing body 31 is permitted to have a sealing body penetration length X (see FIG. 3C ) by which the sealing body 31 penetrates into the gap 26, based on the side edge of the electronic element 21.

Specifically, the upper limit of the sealing body penetration length X can be set appropriately depending on the desired upper limit of the hardened body penetration length Y. Specifically, for example, the upper limit of the sealing body penetration length X may be 50 μm, preferably 30 μm. It is important that the lower limit of the sealing body penetration length X is, for example, -15 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 surface 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 since the content ratio (B) of the first inorganic filler relative to the first sealing resin sheet 1 and the content ratio (A) of the second inorganic filler relative to the second sealing resin sheet 12 are a predetermined ratio and a predetermined relationship, as will be described in detail later, the extent of penetration is suppressed as small as possible. Specifically, the hardened body 41 can be made small in value (Y-X) (hereinafter referred to as the sealing body penetration amount (Y-X)) obtained by subtracting the sealing body penetration length X from the hardened body penetration length Y (see FIG. 3D) of the hardened body 41 penetrating into the gap 26 based on the side edge of the electronic element 21.

When the chip is used for a SAW filter, the upper limit of the hardened body penetration length Y can be set appropriately within a range that does not touch the wiring on the back surface of the chip. Specifically, the upper limit of the hardened body penetration length Y may be, for example, 30 μm, and preferably 25 μm. It is important that the lower limit of the hardened body penetration length Y is, for example, -10 μm.

In this encapsulating multilayer resin sheet 11, the content ratio (B) of the first inorganic filler relative to the first encapsulating resin sheet 1 and the content ratio (A) of the second inorganic filler relative to the second encapsulating resin sheet 12 are a predetermined ratio and have a predetermined relationship. Therefore, when this encapsulating multilayer resin sheet 11 is placed on the electronic element 21 and this encapsulating multilayer resin sheet 11 (encapsulant 31) is heated to form a cured body 41 as shown in FIG. 1D, the amount of penetration of the cured body 41 into the gap 26 between the electronic element 21 and the substrate 22 can be reduced.

Specifically, the lower limit of the content ratio (B) of the first inorganic filler relative to the first material is 50% by mass, preferably 52% by mass, more preferably 55% by mass, even more preferably 57% by mass, particularly preferably 60% by mass, and most preferably 62% by mass. The upper limit of the content ratio (B) of the first inorganic filler relative to the first material is, for example, 80% by mass, preferably 75% by mass, more preferably 72% by mass, even more preferably 70% by mass, and particularly preferably 68% by mass.

If the content ratio (B) of the first inorganic filler relative to the first material is equal to or greater than the above-mentioned lower limit, the sealing resin sheet 1 can flow in the process shown in Figure 1C.

The lower limit of the content ratio (A) of the second inorganic filler relative to the second material is 60% by mass, preferably 65% by mass, more preferably 70% by mass, even more preferably 82% by mass. The upper limit of the content ratio (A) of the second inorganic filler relative to the second material is, for example, 95% by mass, preferably 90% by mass, more preferably 87% by mass, even more preferably 86% by mass.

If the content ratio (A) of the second inorganic filler relative to the second material is equal to or greater than the above-mentioned lower limit, the second sealing resin sheet 12 can flow in the process shown in Figure 1C.

In addition, the content ratio (B) of the first inorganic filler relative to the first sealing resin sheet 1 and the content ratio (A) of the second inorganic filler relative to the second sealing resin sheet 12 satisfy the following formula (1).

0.4A+1.7B<160 (1)
From the above, the content ratio (B) of the first inorganic filler relative to the first sealing resin sheet 1 and the content ratio (A) of the second inorganic filler relative to the second sealing resin sheet 12 are set to a predetermined value. The ratio and the predetermined relationship are that the lower limit of the content ratio (B) of the first inorganic filler is equal to or greater than the lower limit, and the lower limit of the content ratio (A) of the second inorganic filler is equal to or greater than the lower limit. is equal to or greater than the lower limit, and the content ratio (B) of the first inorganic filler and the content ratio (A) of the second inorganic filler satisfy the above formula (1), Specifically, the content ratio (B) of the first inorganic filler relative to the first sealing resin sheet 1 and the content ratio (A) of the second inorganic filler relative to the second sealing resin sheet 12 are This means the range of the shaded area in FIG.

If the content ratio (B) of the first inorganic filler relative to the first sealing resin sheet 1 and the content ratio (A) of the second inorganic filler relative to the second sealing resin sheet 12 are within such ranges, when the cured body 41 is formed, the amount of penetration of the cured body 41 into the gap 26 between the electronic element 21 and the substrate 22 can be reduced. Furthermore, the amount of penetration of the cured body between the electronic element 21 and the substrate 22 can be controlled to an appropriate value.

On the other hand, if the content ratio (B) of the first inorganic filler relative to the first material is less than the above-mentioned lower limit (more specifically, area A in Figure 2), the reliability decreases.

Furthermore, if the lower limit of the content ratio (A) of the second inorganic filler relative to the second material is less than the above-mentioned lower limit (more specifically, region B in Figure 2), reliability decreases.

In addition, when the content ratio (B) of the first inorganic filler relative to the first sealing resin sheet 1 and the content ratio (A) of the second inorganic filler 12 relative to the second sealing resin sheet 12 satisfy the following formula (2) (more specifically, region C in Figure 2), the moldability of the first sealing resin sheet 1 and the second sealing resin sheet 12 decreases.

0.4A+1.7B≧160 (2)
In particular, when the encapsulating resin sheet 1 and the second encapsulating resin sheet 12 contain a base material of an epoxy resin having a softening point of 50° C. or more and 130° C. or less, in the step shown in FIG. 1C, The resin sheet 1 and the second sealing resin sheet 12 can flow. This can shorten the time required for the step shown in FIG. 1C and can flatten one surface in the thickness direction of the second sealing resin sheet 12 in the step shown in FIG. 1C. can be done.

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.

1C, the second sealing resin sheet 12 is fluidized by the pressing force, and one surface in the thickness direction becomes flat. Also, in the process shown in FIG. 1C, 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 pressing force, and deforms to follow the external shape of the electronic element 21. In the process shown in FIG. 1C, the sealing resin sheet 1 is allowed to enter the gap 26 slightly.

In the following modifications, the same reference numerals are used for the same components and steps as those in the above-described embodiment, and detailed descriptions thereof will be omitted. In addition, each modification can achieve the same effects as those in the embodiment, unless otherwise specified. Furthermore, the embodiment and its modifications can be appropriately combined.

The first sealing resin sheet 1 and/or the second sealing resin sheet 12 in the sealing multilayer resin sheet 11 may be multilayer.

As an example of an element, there is given an electronic element 21 arranged across a gap 26 from one thickness-wise surface 25 of the substrate 22, which is sealed with a sealing multilayer resin sheet 11; however, for example, although not shown, there can also be given an electronic element 21 in contact with one thickness-wise surface 25 of the substrate 22, which can be sealed with a sealing multilayer resin sheet 11.

Although electronic element 21 has been given as an example of an element, a semiconductor element may also be used. 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 Preparation Examples, Comparative Preparation Examples, Examples, and Comparative Examples. However, the present invention is not limited to these Preparation Examples, Comparative Preparation Examples, Examples, and Comparative Examples.
In addition, specific numerical values such as blending ratios (content ratios), physical property values, parameters, etc. used in the following description can be replaced with the upper limit (a numerical value defined as "not more than" or "less than") or lower limit (a numerical value defined as "not less than" or "exceeding") of the corresponding blending ratios (content ratios), physical property values, parameters, etc. described in the above "Form for implementing the invention."

The components used in the preparation examples and comparative preparation examples are shown below.

Layered silicate compound: Esben NX manufactured by Hojun Co., Ltd. (organic bentonite whose surface is modified with dimethyl distearyl ammonium)
Epoxy resin 1: 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) Epoxy resin 2: JER630 manufactured by Mitsubishi Chemical Corporation (triglycidylaminophenol (glycidylamine type epoxy resin)), epoxy equivalent 90 g/eq. to 105 g/eq., liquid Phenol resin 1: LVR-8210DL manufactured by Gun-ei Chemical Co., Ltd. (novolac type phenol resin, latent hardener, hydroxyl equivalent: 104 g/eq., solid, softening point: 60°C)
Phenol resin 2: TPM-100 (trishydroxyphenylmethane type novolak resin) manufactured by Gun-ei Chemical Industry Co., Ltd., hydroxyl group equivalent: 98 g/eq.
Acrylic resin 1: HME-2006M manufactured by Negami Chemical Industries, a carboxyl group-containing acrylic acid ester copolymer (acrylic resin), 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 Silane coupling agent: KBM-403 (3-glycidoxypropyltrimethoxysilane) manufactured by Shin-Etsu Chemical Co., Ltd.
First filler: FB-8SM (spherical fused silica powder), 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 of First Sealing Resin Sheet>
Preparation Examples 1 to 10
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 50 μm-thick sealing resin sheet 1. The first sealing resin sheet 1 was in the B stage.
<Preparation of second sealing resin sheet>
Preparation Examples 11 to 17
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 precursor for the second sealing resin sheet 12 having a thickness of 52.5 μm, and four sheets of the precursor for the second sealing resin sheet 12 were laminated to prepare a second sealing resin sheet 12 having a thickness of 210 μm. The second sealing resin sheet 12 was in the B stage.

Examples 1 to 33 and Comparative Examples 1 to 23
In a combination of preparation examples as shown in Table 3, a second sealing resin sheet 12 was disposed on one side in the thickness direction of a first sealing resin sheet 1, to prepare a sealing multilayer resin sheet 11 having a thickness of 260 μm.

Comparative examples 22 and 23 had low reliability and could not be used from the viewpoint of characteristics other than the penetration amount.

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 Figure 3A, a sample sheet 61 having a length of 10 mm, a width of 10 mm and a thickness of 260 μm is prepared from the sealing multilayer resin sheet 11 of each embodiment and each comparative example.

Step B: As shown in Figure 3B, 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 having a thickness of 20 μm.

Step C: As shown in FIG. 3C, the sample sheet 61 is used to seal the dummy element 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 to form an encapsulant 31 from the sample sheet 61.

Step D: As shown in FIG. 3D, the sealing body 31 is thermally cured by heating at 150° C. under atmospheric pressure for 1 hour to form a hardened body 41 from the sealing body 31.

Step E: As shown in the enlarged view of Figure 3D, using the side edge of the dummy element 71 as a reference, measure the hardened body penetration length Y, the penetration length of the hardened body 41 from the side edge into the gap 26 between the dummy element 71 and the glass substrate 72.

The obtained hardened body penetration length Y is shown in Table 3.

In the evaluation, "minus" means that a space (see the thick dashed line in FIG. 1D) is formed that protrudes outward from the side edge of the dummy element 71. The absolute value of the "minus" corresponds to the protruding length of that space.

<Measurement of Glass Transition Temperature>
The glass transition temperatures of the first sealing resin sheet 1 and the second sealing resin sheet 12 in each of the Examples and Comparative Examples were measured from the maximum value of the loss tangent (tan δ) measured using a dynamic viscoelasticity measuring device (DMA, frequency 1 Hz, tensile mode, heating rate 10° C./min).
The results are shown in Table 3.

<Measurement of Linear Expansion Coefficient>
The linear expansion coefficients of the first encapsulating resin sheet 1 and the second encapsulating resin sheet 12 of each of the examples and comparative examples were measured under the following conditions using a thermomechanical measurement device (TMA). The results are shown in Table 3.
(Measurement conditions)
Thermomechanical measurement apparatus (TMA): TMA (manufactured by TA Instruments Japan, sample size: 4.5 mm x 20 mm
Mode: Tensile mode Heating rate: 5°C/min Measurement temperature range: 25°C to 260°C
Discussion FIG. 4 shows a graph showing the relationship between the content ratio (B) of the first inorganic filler relative to the first material and the content ratio (A) of the second inorganic filler relative to the second material in Examples 1 to 33 and Comparative Examples 1 to 23.

At this time, it was found that the range (shaded area in Figure 4) between the content ratio (B) of the first inorganic filler that can reduce the penetration length of the hardened body and the content ratio (A) of the second inorganic filler relative to the second material is determined by the relationship in Figure 4 (B ≧ 50, A ≧ 60, 0.4A + 1.7B < 160).

In detail, in Examples 1 to 33 which fall within the above range, the obtained electronic element packages are molded with an appropriate hardened body penetration length, compared to Comparative Examples 1 to 23 which do not fall within the above range.

The above invention is provided as an exemplary embodiment of the present invention, but this is merely an example and should not be interpreted as being limiting. Modifications of the present invention that are obvious to a person skilled in the art are intended to be included in the scope of the claims below.

Multilayer resin sheets for encapsulation are used to encapsulate elements.

1 First sealing resin sheet 11 Sealing multilayer resin sheet 12 Second sealing resin sheet

Claims (3)

A first sealing resin sheet and a second sealing resin sheet are provided in this order in one direction in a thickness direction,
the first sealing resin sheet contains a layered silicate compound and a first inorganic filler,
the second sealing resin sheet does not contain a layered silicate compound and contains a second inorganic filler,
A content ratio (B) of the first inorganic filler with respect to the first sealing resin sheet is 50 mass% or more,
A content ratio (A) of the second inorganic filler with respect to the second sealing resin sheet is 60 mass% or more,
a content ratio (B) of the first inorganic filler relative to the first sealing resin sheet and a content ratio (A) of the second inorganic filler relative to the second sealing resin sheet satisfy the following formula (1):
0.4A+1.7B<160 (1) The first sealing resin sheet has a thickness of 30 μm or more and 100 μm or less,
The encapsulating multilayer resin sheet according to claim 1 , wherein the second encapsulating resin sheet has a thickness of 50 μm or more and 500 μm or less. the first sealing resin sheet has a linear expansion coefficient of 80 ppm/° C. or less;
The encapsulating multilayer resin sheet according to claim 1 , wherein the second encapsulating resin sheet has a linear expansion coefficient of 50 ppm/° C. or less.

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