Resin Sheet for Sealing and Electronic Component Device

Abstract

To provide a sealing resin sheet for sealing an electronic component chip that is mounted on a substrate in the state of facing the substrate through a gap which is suitable for achieving both high heat dissipation property and good hollow sealing property, and an electronic component device.SOLUTION: A sealing resin sheet X has a sealing resin layer 11, and a sealing resin layer 12 in this order in a thickness direction H. The sealing resin layer 11 contains a first thermosetting resin, a laminar silicate compound, and a first inorganic filler other than the laminar silicate compound. The sealing resin layer 12 contains a second thermosetting resin and a second inorganic filler. The sealing resin sheet X has thermal conductivity of 2 W / m K or more after curing. An electronic component device Y includes a substrate S, an electronic component chip 21 that is mounted on a substrate S in the state of facing the substrate S through a gap G, and a cured resin part 10 which is formed of the sealing resin sheet X, and seals the electronic component chip 21 and the gap G.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a resin sheet for sealing and an electronic component device.

Background Art

[0002] Conventionally, a resin sheet for sealing for sealing an electronic component chip on a mounting substrate has been known. The resin sheet for sealing is a sheet-shaped sealing resin material containing a thermosetting resin.

[0003] On the other hand, as an electronic component chip, an electronic component chip mounted on the substrate in a state of facing the mounting substrate with a gap therebetween is known. Such an electronic component chip is sealed with a resin sheet for sealing, for example, as follows.

[0004] First, a resin sheet for sealing having a predetermined thickness is pressed against a plurality of electronic component chips (facing the substrate with a gap therebetween) that are bonded to the same surface of the mounting substrate and separated from each other by a flat press machine (pressing step). As a result, the resin sheet for sealing is heated and softened, plastically deformed, and covers each electronic component chip. Next, the resin sheet for sealing covering the electronic component chip is cured by heating at a high temperature (curing step). As a result, a cured resin portion is formed around each electronic component chip on the substrate, and each electronic component chip is sealed. Thereafter, for example, by blade dicing, the cured resin portion is cut together with the substrate to obtain an electronic component device as an individualized electronic component package (individualization step). Such a sealing technique for electronic component chips is described in, for example, Patent Document 1 below.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] In the above pressing step, the resin sheet for sealing is required to be sufficiently fluidized in a heat-softened state and the side (the first side) in contact with the electronic component chip is deformed following the outer shape of the chip. This is to form a cured resin part that appropriately covers the electronic component chip from the resin sheet for sealing. Also, on the side (the second side) opposite to the first side of the resin sheet for sealing, in the above pressing step and curing step, it is required to be sufficiently fluidized in a heat-softened state so that the exposed surface is flattened. This is for realizing appropriate laser marking on the exposed surface in a later step. In addition, on the first side of the resin sheet for sealing, in the above curing step, it is required that the thermosetting resin that is once softened by high-temperature heating does not enter too much into the gap between the mounting substrate and the electronic component chip. This is for realizing the sealing (hollow sealing) of the electronic component chip on the substrate in a state where the gap between the mounting substrate and the electronic component chip is secured. Thus, regarding the fluidity during heat softening, different characteristics are required for the resin sheet for sealing according to the stage in the process of sealing the electronic component chip and the part (the first side, the second side) within the sheet.

[0007] Also, heat dissipation is required for the encapsulating resin material of the electronic component chip. The higher the performance of the electronic component chip, the higher the heat dissipation required for the encapsulating resin material. Conventionally, a high thermal conductivity inorganic filler has been blended into the encapsulating resin material to ensure heat dissipation of the encapsulating resin material. However, blending the inorganic filler into the resin sheet for sealing as the encapsulating resin material affects the fluidity of the resin sheet for sealing in the process of sealing the electronic component chip. In the conventional resin sheet for sealing, the fluidity during heating tends to decrease as the blending amount of the inorganic filler increases.

[0008] The present invention provides a resin sheet for sealing an electronic component chip mounted on a substrate in a state of facing the substrate with a gap therebetween, which is suitable for achieving both heat dissipation and hollow sealing properties. The present invention also provides an electronic component device in which an electronic component chip is sealed with such a resin sheet for sealing.

Means for Solving the Problems

[0009] The present invention [1] relates to a resin sheet for sealing, which includes a first sealing resin layer and a second sealing resin layer in this order in the thickness direction. The first sealing resin layer contains a first thermosetting resin, a layered silicate compound, and a first inorganic filler other than the layered silicate compound. The second sealing resin layer contains a second thermosetting resin and a second inorganic filler, and has a thermal conductivity of 2 W / m·K or more after curing, including a resin sheet for sealing.

[0010] The resin sheet for sealing can be used to seal an electronic component chip mounted on a substrate in a state of facing the substrate with a gap therebetween through the following pressing process and curing process. In the pressing process, with the first sealing resin layer side of the resin sheet for sealing in contact with the electronic component chip on the substrate, the sheet is pressed toward the substrate while being heated and softened. In this process, the above gap is closed along the side surface of the electronic component chip by the first sealing resin layer that adheres to the substrate around the electronic component chip. In the curing process, the resin sheet for sealing covering the electronic component chip is further heated to be cured. Thereby, a cured resin portion is formed around the electronic component chip on the substrate, and the electronic component chip is sealed.

[0011] In the resin sheet for sealing, as described above, the first sealing resin layer on the side (the first side) in contact with the electronic component chip contains a layered silicate compound. In the first sealing resin layer, the layered silicate compound exhibits thixotropic properties such that its viscosity decreases when the first sealing resin layer is subjected to a pressing force compared to when it is not. Therefore, the configuration in which the first sealing resin layer contains a layered silicate compound is suitable for highly fluidizing the same layer in the pressing process where the first sealing resin layer is subjected to a pressing force, while suppressing the decrease in viscosity due to high-temperature heating of the first sealing resin layer and making the same layer less fluid in the curing process. The high fluidization of the first sealing resin layer in the pressing process helps to form a cured resin part that appropriately covers the electronic component chip from the resin sheet for sealing. The low fluidization of the first sealing resin layer in the curing process helps to prevent the sealing resin from excessively entering the gap between the base material and the electronic component chip (over-entry). The coexistence of such high fluidization and low fluidization in the first sealing resin layer is suitable for hermetically sealing the electronic component chip on the base material.

[0012] Also, as described above, the resin sheet for sealing has a thermal conductivity of 2 W / m·K or more after curing. Such a configuration is suitable for ensuring good heat dissipation as a sealing resin material in the resin sheet for sealing.

[0013] In addition, in the resin sheet for sealing, as described above, the first sealing resin layer contains a first inorganic filler in addition to the layered silicate compound, and the second sealing resin layer contains a second inorganic filler. Such a configuration is suitable for ensuring the thermal conductivity of the resin sheet for sealing, and thus helps to achieve a thermal conductivity of 2 W / m·K or more after curing of the same sheet.

[0014] The present invention [2] includes the resin sheet for sealing according to [1] above, in which the ratio of the melt viscosity of the first sealing resin layer at 90°C to the melt viscosity of the second sealing resin layer at 90°C is 4 or more.

[0015] Such a configuration is preferable for achieving both the low fluidity of the first sealing resin layer and the high fluidity of the second sealing resin layer in the sealing resin sheet that is once softened by high-temperature heating in the curing process. In the curing process, the high fluidity of the second sealing resin layer helps to flatten the exposed surface on the second sealing resin layer side of the sealing resin sheet.

[0016] The present invention [3] includes the sealing resin sheet according to [1] or [2] above, wherein the melt viscosity of the first sealing resin layer at 90 °C is 110 kPa·s or more and 500 kPa·s or less.

[0017] Such a configuration is preferable for suppressing the above-mentioned over-penetration in the curing process.

[0018] The present invention [4] includes the sealing resin sheet according to any one of [1] to [3] above, wherein the first inorganic filler and / or the second inorganic filler is at least one selected from the group consisting of aluminum oxide, aluminum nitride, boron nitride, silicon nitride, and silicon carbide.

[0019] Such a configuration is preferable for ensuring the thermal conductivity of the sealing resin sheet.

[0020] The present invention [5] includes the sealing resin sheet according to any one of [1] to [4] above, wherein the mass ratio of the amount of the layered silicate compound to the total amount of the layered silicate compound and the first inorganic filler in the first sealing resin layer is 0.01 or more and 0.1 or less.

[0021] Such a configuration is preferable for achieving both high fluidity in the pressing process and low fluidity in the curing process in the first sealing resin layer while ensuring the thermal conductivity of the sealing resin sheet.

[0022] The present invention [6] includes the sealing resin sheet according to any one of [1] to [5] above, wherein the content ratio of the inorganic filler in each sealing resin layer is 83% by mass or more.

[0023] Such a configuration is preferable for ensuring the thermal conductivity of the resin sheet for sealing. Further, such a configuration is preferable for suppressing the expansion and contraction due to temperature changes in the resin sheet for sealing.

[0024] The present invention [7] includes the resin sheet for sealing according to any one of [1] to [6] above, wherein the content ratio of the inorganic filler in each sealing resin layer is 90% by mass or less.

[0025] Such a configuration is preferable for ensuring the fluidity of the resin sheet for sealing in the pressing process.

[0026] The present invention [8] includes the resin sheet for sealing according to any one of [1] to [7] above, wherein the following entry length L shown in the entry length evaluation test in which the following first step to fourth step are performed is 0 μm or more and 50 μm or less.

[0027] Entry length evaluation test First step: Prepare a dummy chip mounting substrate including a glass substrate and a dummy chip having a size of 1 mm × 1 mm × 200 μm in thickness, wherein the dummy chip is bonded to the glass substrate via bumps in a state of facing the glass substrate with a gap therebetween, and the length from the glass substrate to the dummy chip in the gap is 50 μm. Second step: With the first sealing resin layer side of the resin sheet for sealing in contact with the dummy chip on the glass substrate, press the resin sheet for sealing toward the glass substrate under the conditions of a temperature of 70°C, a degree of vacuum of 1.6 kPa or less, a pressing force of 0.1 MPa, and a pressing time of 40 seconds by a vacuum flat press, and close the open edge of the gap with the first sealing resin layer that adheres to the glass substrate around the dummy chip. Third step: After the second step, cure the resin sheet for sealing by heating at 150°C for 1 hour under atmospheric pressure. Fourth step: After the third step, measure the entry length L into the gap in the resin sheet for sealing.

[0028] In the above-described entry length evaluation test, a configuration in which the entry length is 0 μm or more and 50 μm or less is preferable for suppressing over-entry of the encapsulating resin into the gap between the substrate and the electronic component chip in the electronic component chip encapsulation process including the above-described pressing process and curing process in which the encapsulating resin sheet is used.

[0029] The present invention [9] includes a base material, an electronic component chip mounted on the base material in a state of facing the base material with a gap therebetween, and a cured resin portion formed from the encapsulating resin sheet according to any one of the above [1] to [8] and encapsulating the electronic component chip and the gap.

[0030] In this electronic component device, since the electronic component chip is encapsulated by the cured resin portion formed from the above-described encapsulating resin sheet, it is suitable for achieving both heat dissipation and hollow encapsulation properties in the cured resin portion.

Brief Description of the Drawings

[0031]

Figure 1

Figure 2

Figure 3

Embodiments for Carrying Out the Invention

[0032] As a sealing resin sheet X as an embodiment of the sealing resin sheet of the present invention, it is a sheet-shaped sealing resin material for sealing electronic component chips such as semiconductor chips. As shown in FIG. 1, it includes a sealing resin layer 11 (first sealing resin layer) and a sealing resin layer 12 (second sealing resin layer) in order in the thickness direction H. Further, the sealing resin sheet X extends in a direction orthogonal to the thickness direction H.

[0033] The sealing resin layer 11 is a layer formed from a first thermosetting composition. The first thermosetting composition includes a first thermosetting resin, a layered silicate compound, and an inorganic filler other than the layered silicate compound (first inorganic filler). That is, the sealing resin layer 11 includes a first thermosetting resin, a layered silicate compound, and a first inorganic filler. The sealing resin layer 11 is in a semi-cured state (B-stage state).

[0034] Examples of the first thermosetting resin include epoxy resin, silicone resin, urethane resin, polyimide resin, urea resin, melamine resin, and unsaturated polyester resin. These first thermosetting resins may be used alone or in combination of two or more. The content ratio of the first thermosetting resin in the first thermosetting composition is preferably 3% by mass or more, more preferably 3.5% by mass or more. The content ratio of the first thermosetting resin in the first thermosetting composition is preferably 30% by mass or less, more preferably 25% by mass or less.

[0035] The first thermosetting resin preferably contains an epoxy resin. Examples of the epoxy resin include bifunctional epoxy resins and polyfunctional epoxy resins having three or more functional groups. Examples of the bifunctional epoxy resin include 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. Examples of the polyfunctional epoxy resin having three or more functional groups include phenol novolak type epoxy resin, cresol novolak type epoxy resin, trishydroxyphenylmethane type epoxy resin, tetraphenylol ethane type epoxy resin, and dicyclopentadiene type epoxy resin. These epoxy resins may be used alone or in combination of two or more. As the epoxy resin, a bifunctional epoxy resin is preferably used, and more preferably, bisphenol F type epoxy and / or bisphenol A type epoxy resin is used.

[0036] The epoxy equivalent of the epoxy resin is preferably 10 g / eq or more, more preferably 50 g / eq or more, and still more preferably 100 g / eq or more. The epoxy equivalent of the epoxy resin is preferably 650 g / eq or less, more preferably 600 g / eq or less, and still more preferably 550 g / eq or less. When the first thermosetting resin contains a plurality of epoxy resins, the weight average epoxy equivalent of the plurality of epoxy resins is preferably 10 g / eq or more, more preferably 50 g / eq or more, and still more preferably 100 g / eq or more. The same weight average epoxy equivalent is preferably 650 g / eq or less, more preferably 600 g / eq or less, and still more preferably 550 g / eq or less.

[0037] When an epoxy resin is used, the first thermosetting resin preferably contains a phenolic resin as a curing agent for the epoxy resin. Such a configuration is suitable for the resin sheet X for sealing to exhibit high heat resistance and high chemical resistance after curing, and thus is suitable for forming a sealing material having excellent sealing reliability. Examples of the phenolic resin preferably include novolak-type phenolic resins and triphenylmethane-type phenolic resins. Examples of the novolak-type phenolic resin include phenolic novolak resins, phenol aralkyl resins, trishydroxyphenylmethane novolak resins, cresol novolak resins, tert-butylphenol novolak resins, and nonylphenol novolak resins. These phenolic resins may be used alone or in combination of two or more.

[0038] In the first thermosetting composition, the amount of hydroxyl groups in the phenolic resin as a curing agent relative to 1 equivalent of epoxy groups of the epoxy resin is preferably 0.7 equivalent or more, more preferably 0.9 equivalent or more. In the first thermosetting composition, the amount of hydroxyl groups in the phenolic resin as a curing agent relative to 1 equivalent of epoxy groups of the epoxy resin is preferably 1.5 equivalents or less, more preferably 1.2 equivalents or less. Also, the blending amount of the phenolic resin as a curing agent relative to 100 parts by mass of the epoxy resin is preferably 20 parts by mass or more, more preferably 40 parts by mass or more. The blending amount of the phenolic resin as a curing agent relative to 100 parts by mass of the epoxy resin is preferably 80 parts by mass or less, more preferably 60 parts by mass or less.

[0039] The first thermosetting composition preferably contains a curing accelerator. The curing accelerator is a catalyst (thermosetting catalyst) that promotes the curing of the thermosetting resin by heating. Examples of the curing accelerator include imidazole compounds and organic phosphorus compounds. Examples of the imidazole compound include 2-phenyl-4,5-dihydroxymethylimidazole and 2-phenyl-4-methyl-5-hydroxymethylimidazole. Examples of the organic phosphorus compound include triphenylphosphine, tricyclohexylphosphine, tributylphosphine, and methyldiphenylphosphine. As the curing accelerator, an imidazole compound is preferably used, and 2-phenyl-4,5-dihydroxymethylimidazole is more preferably used. The blending amount of the curing accelerator with respect to 100 parts by mass of the first thermosetting resin is, for example, 0.05 parts by mass or more and, for example, 5 parts by mass or less.

[0040] The layered silicate compound is a component that thickens the first thermosetting composition while imparting thixotropic properties to the first thermosetting composition and is dispersed in the first thermosetting composition. Examples of the layered silicate compound include smectite, kaolinite, halloysite, talc, and mica. Examples of smectite include montmorillonite, beidellite, nontronite, saponite, hectorite, sauconite, and stevensite. As the layered silicate compound, smectite is preferably used because it is easy to mix with the thermosetting resin, and montmorillonite is more preferably used.

[0041] The layered silicate compound may be an unmodified product with an unmodified surface or a modified product with a surface modified by an organic component. For example, from the viewpoint of affinity with the first thermosetting resin, a layered silicate compound with a surface modified by an organic component is preferably used, an organically modified smectite with a surface modified by an organic component is more preferably used, and an organically modified bentonite with a surface modified by an organic component is even more preferably used.

[0042] Examples of the organic component include organic cations (onium ions) such as ammonium, imidazolium, pyridinium, and phosphonium. Examples of ammonium include dimethyldistearylammonium, distearylammonium, octadecylammonium, hexylammonium, octylammonium, 2-hexylammonium, dodecylammonium, and trioctylammonium. Examples of imidazolium include methylstearylimidazolium, distearylimidazolium, methylhexylimidazolium, dihexylimidazolium, methyloctylimidazolium, dioctylimidazolium, methyldodecylimidazolium, and didodecylimidazolium. Examples of pyridinium include stearylpyridinium, hexylpyridinium, octylpyridinium, and dodecylpyridinium. Examples of phosphonium include dimethyldistearylphosphonium, distearylphosphonium, octadecylphosphonium, hexylphosphonium, octylphosphonium, 2-hexylphosphonium, dodecylphosphonium, and trioctylphosphonium. The organic cation may be used alone or in combination of two or more. As the organic cation, ammonium is preferably used, and dimethyldistearylammonium is more preferably used.

[0043] As the organic layered silicate compound, an organic smectite having a surface modified with ammonium is preferably used, and an organic bentonite having a surface modified with dimethyldistearylammonium is more preferably used.

[0044] The average particle size of the layered silicate compound is preferably 1 nm or more, more preferably 5 nm or more, still more preferably 10 nm or more. The average particle size of the layered silicate compound is preferably 100 μm or less, more preferably 50 μm or less, still more preferably 10 μm or less. The average particle size of the layered silicate compound is the median diameter (the particle size at which the volume cumulative frequency reaches 50% from the smaller diameter side) in the particle size distribution based on volume, and is determined, for example, based on the particle size distribution obtained by the laser diffraction / scattering method (the same applies to the average particle size of other inorganic fillers).

[0045] As the layered silicate compound, commercially available products can be used. Examples of commercially available products of organophilic bentonite include the Esben series (manufactured by Hoejung).

[0046] The content ratio R1 of the layered silicate compound in the first thermosetting composition (that is, the content ratio R1 of the layered silicate compound in the sealing resin layer 11) is preferably 1% by mass or more, more preferably 1.5% by mass or more, still more preferably 2% by mass or more. Such a configuration is preferable for exhibiting thixotropic properties in which the sealing resin layer 11 thickens while having a lower viscosity when receiving a pressing force than when not receiving it. From the viewpoint of avoiding excessive thickening of the first thermosetting composition, the content ratio R1 is preferably 6% by mass or less, more preferably 5% by mass or less, still more preferably 4% by mass or less.

[0047] Examples of the first inorganic filler include aluminum oxide, aluminum nitride, aluminum hydroxide, magnesium oxide, magnesium hydroxide, aluminum borate whisker, and boron nitride. The first inorganic filler also includes silicon compounds other than layered silicate compounds. Examples of the silicon compound include silicon nitride, silicon carbide, and silica. These inorganic fillers may be used alone or in combination of two or more. From the viewpoint of ensuring the thermal conductivity of the sealing resin layer 11, the first inorganic filler is preferably at least one selected from the group consisting of aluminum oxide, aluminum nitride, boron nitride, silicon nitride, and silicon carbide.

[0048] Examples of the shape of the first inorganic filler include a substantially spherical shape, a substantially plate shape, a substantially needle shape, and an irregular shape, and the substantially spherical shape is preferred.

[0049] The average particle diameter of the first inorganic filler (when the first inorganic filler has a shape other than a substantially spherical shape, the average value of the maximum length of the inorganic filler) is preferably 0.1 μm or more, more preferably 0.5 μm or more. The average particle diameter is preferably 50 μm or less, more preferably 20 μm or less, and still more preferably 10 μm or less.

[0050] The surface of the first inorganic filler may be partially or entirely treated with a surface treatment agent such as a silane coupling agent.

[0051] The content ratio of the first inorganic filler in the first thermosetting composition (sealing resin layer 11) is preferably 75% by mass or more, more preferably 78% by mass or more, and still more preferably 80% by mass or more. Such a configuration is preferable for ensuring the thermal conductivity of the sealing resin layer 11. Further, such a configuration is preferable for suppressing expansion and contraction due to temperature change in the sealing resin layer 11. The content ratio is preferably 90% by mass or less, more preferably 85% by mass or less, and still more preferably 83% by mass or less. Such a configuration is preferable for avoiding excessive thickening of the first thermosetting composition and ensuring the fluidity of the sealing resin layer 11 in the pressing step described later.

[0052] The content ratio R2 of the inorganic fillers (layered silicate compound and the first inorganic filler) in the first thermosetting composition is preferably 83% by mass or more, more preferably 84% by mass or more, still more preferably 85% by mass or more. Such a configuration is preferable for ensuring the thermal conductivity of the resin sheet for sealing. Also, such a configuration is preferable for suppressing the expansion and contraction due to temperature change in the sealing resin layer 11. The content ratio R2 is preferably 90% by mass or less, more preferably 89% by mass or less, still more preferably 88% by mass or less. Such a configuration is preferable for avoiding excessive thickening of the first thermosetting composition and ensuring the fluidity of the sealing resin layer 11 in the pressing step described later.

[0053] The mass ratio (R1 / R2) of the amount of the layered silicate compound to the total amount of the layered silicate compound and the first inorganic filler in the sealing resin layer 11 is preferably 0.01 or more, more preferably 0.015 or more, still more preferably 0.02 or more, particularly preferably 0.03 or more, and is preferably 0.1 or less, more preferably 0.08 or less, still more preferably 0.07 or less. Such a configuration is preferable for achieving both high fluidization in the pressing step described later and low fluidization in the curing step described later in the sealing resin layer 11 while ensuring the thermal conductivity of the resin sheet X for sealing.

[0054] The first thermosetting composition may contain other components. Examples of the other components include a thermoplastic resin, a pigment, and a silane coupling agent.

[0055] Examples of the thermoplastic resin include acrylic resins, natural rubbers, butyl rubbers, isoprene rubbers, chloroprene rubbers, ethylene-vinyl acetate copolymers, ethylene-acrylic acid copolymers, ethylene-acrylic ester copolymers, polybutadiene resins, polycarbonate resins, thermoplastic polyimide resins, polyamide resins, phenoxy resins, saturated polyester resins (such as PET), polyamideimide resins, fluororesins, and styrene-isobutylene-styrene block copolymers. These thermoplastic resins may be used alone or in combination of two or more kinds.

[0056] From the viewpoint of ensuring the compatibility between the thermosetting resin and the thermoplastic resin, an acrylic resin is preferably used as the thermoplastic resin.

[0057] Examples of the acrylic resin include (meth)acrylic polymers which are polymers of a monomer component containing an alkyl (meth)acrylate having a linear or branched alkyl group and other monomers (copolymerizable monomers).

[0058] Examples of the alkyl group of the alkyl (meth)acrylate include alkyl groups having 1 to 6 carbon atoms. Examples of the alkyl group include methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, t-butyl group, isobutyl group, pentyl group, and hexyl group.

[0059] Examples of the copolymerizable monomers include carboxyl group-containing monomers, acid anhydride monomers, glycidyl group-containing monomers, hydroxyl group-containing monomers, sulfonic acid group-containing monomers, phosphoric acid group-containing monomers, and acrylonitrile. Examples of the carboxyl group-containing monomers include acrylic acid, methacrylic acid, carboxyethyl acrylate, carboxypentyl acrylate, itaconic acid, maleic acid, fumaric acid, and crotonic acid. Examples of the acid anhydride monomers include maleic anhydride and itaconic anhydride. Examples of the glycidyl group-containing monomers include glycidyl acrylate and glycidyl methacrylate. Examples of the hydroxyl group-containing monomers include 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-hydroxylauryl (meth)acrylate. Examples of the sulfonic acid group-containing monomers include styrene sulfonic acid, allyl sulfonic acid, 2-(meth)acrylamide-2-methylpropane sulfonic acid, (meth)acrylamide propane sulfonic acid, sulfopropyl (meth)acrylate, and (meth)acryloyloxy naphthalene sulfonic acid. Examples of the phosphoric acid group-containing monomers include 2-hydroxyethyl acryloyl phosphate. These copolymerizable monomers may be used alone or in combination of two or more kinds.

[0060] The glass transition temperature (Tg) of the thermoplastic resin is preferably -70°C or higher. The glass transition temperature is preferably 0°C or lower, more preferably -5°C or lower.

[0061] Regarding the glass transition temperature (Tg) of the polymer, the glass transition temperature (theoretical value) obtained based on the following Fox's equation can be used. Fox's equation is a relational expression between the glass transition temperature Tg of the polymer and the glass transition temperature Tgi of the homopolymer of the monomer constituting the polymer. In the following Fox's equation, Tg represents the glass transition temperature (°C) of the polymer, Wi represents the weight fraction of monomer i constituting the polymer, and Tgi represents the glass transition temperature (°C) of the homopolymer formed from monomer i. For the glass transition temperature of the homopolymer, literature values can be used. For example, "Polymer Handbook" (4th Edition, John Wiley & Sons, Inc., 1999) and "New Polymer Library 7 Introduction to Synthetic Resins for Paints" (written by Kyozo Kitaoka, Polymer Publishing Society, 1995) list the glass transition temperatures of various homopolymers. On the other hand, for the glass transition temperature of the homopolymer of the monomer, it is also possible to obtain it by the method specifically described in Japanese Patent Application Laid-Open No. 2007-51271.

[0062] Fox's equation 1 / (273 + Tg) = Σ[Wi / (273 + Tgi)]

[0063] The weight average molecular weight of the thermoplastic resin is preferably 100,000 or more, preferably 300,000 or more. The weight average molecular weight of the thermoplastic resin is preferably 2,000,000 or less, more preferably 1,500,000 or less. The weight average molecular weight of the resin is measured by gel permeation chromatography (GPC) based on the standard polystyrene conversion value.

[0064] The content ratio of the thermoplastic resin in the first thermosetting composition is preferably 0.5% by mass or more, more preferably 1% by mass or more, more preferably 1.3% by mass or more, and still more preferably 1.5% by mass or more. The content ratio is preferably 30% by mass or less, more preferably 20% by mass or less.

[0065] Examples of the pigment include black pigments such as carbon black. The particle diameter of the pigment is, for example, 0.001 μm or more and, for example, 1 μm or less. The particle diameter of the pigment is the arithmetic mean diameter obtained by observing the pigment with an electron microscope. The content ratio of the pigment in the first thermosetting composition is, for example, 0.1% by mass or more and, for example, 2% by mass or less.

[0066] Examples of the silane coupling agent include silane coupling agents containing an epoxy group. Examples of the epoxy group-containing silane coupling agent include 3-glycidoxy dialkyldialkoxysilane and 3-glycidoxyalkyltrialkoxysilane. Examples of 3-glycidoxy dialkyldialkoxysilane include 3-glycidoxypropylmethyldimethoxysilane and 3-glycidoxypropylmethyldiethoxysilane. Examples of 3-glycidoxyalkyltrialkoxysilane include 3-glycidoxypropyltrimethoxysilane and 3-glycidoxypropyltriethoxysilane. As the silane coupling agent, preferably 3-glycidoxyalkyltrialkoxysilane is used, and more preferably 3-glycidoxypropyltrimethoxysilane is used. The content ratio of the silane coupling agent in the first thermosetting composition is preferably 0.1% by mass or more, more preferably 1% by mass or more. The content ratio is preferably 10% by mass or less, more preferably 5% by mass or less.

[0067] The sealing resin layer 12 is a layer formed from the second thermosetting composition. The second thermosetting composition includes a second thermosetting resin and a second inorganic filler. That is, the sealing resin layer 12 includes a second thermosetting resin and a second inorganic filler. The sealing resin layer 12 is in a semi-cured state (B-stage state).

[0068] Examples of the second thermosetting resin include, for example, the above-described first thermosetting resin. The content ratio of the second thermosetting resin in the second thermosetting composition is preferably 2% by mass or more, more preferably 3% by mass or more. The content ratio of the second thermosetting resin in the second thermosetting composition is preferably 20% by mass or less, more preferably 15% by mass or less.

[0069] The second thermosetting resin preferably contains an epoxy resin. Examples of the epoxy resin include, for example, the epoxy resins described above with respect to the first thermosetting composition. Preferably, a bifunctional epoxy resin is used, and more preferably a bisphenol A type epoxy resin and / or a bisphenol F type epoxy resin is used. The preferable range of the epoxy equivalent of the epoxy resin in the second thermosetting composition is the same as that described above for the preferable range of the epoxy equivalent of the epoxy resin in the first thermosetting composition.

[0070] When an epoxy resin is used as the second thermosetting resin, the second thermosetting resin preferably contains a phenol resin as a curing agent for the epoxy resin. Examples of the phenol resin preferably include a novolak type phenol resin and a triphenylmethane type phenol resin. The amount of hydroxyl groups in the phenol resin as a curing agent per equivalent of epoxy groups in the epoxy resin in the second thermosetting composition is the same as that of the amount of hydroxyl groups in the phenol resin as a curing agent per equivalent of epoxy groups in the epoxy resin described above with respect to the first thermosetting composition. Also, the compounding amount of the phenol resin as a curing agent per 100 parts by mass of the epoxy resin in the second thermosetting composition is the same as that of the compounding amount of the phenol resin as a curing agent per 100 parts by mass of the epoxy resin described above with respect to the first thermosetting composition.

[0071] The second thermosetting composition preferably contains a curing accelerator. Examples of the curing accelerator include, for example, the curing accelerators described above with respect to the first thermosetting composition. The compounding amount of the curing accelerator per 100 parts by mass of the second thermosetting resin is, for example, 0.05 parts by mass or more, and is, for example, 5 parts by mass or less.

[0072] Examples of the second inorganic filler include the first inorganic filler described above with respect to the first thermosetting composition. From the viewpoint of ensuring the content of the inorganic filler other than the layered silicate compound in the second thermosetting composition, the second inorganic filler preferably does not contain a layered silicate compound. That is, as the second inorganic filler, an inorganic filler other than the layered silicate compound is preferable. Further, from the viewpoint of ensuring the thermal conductivity of the sealing resin layer 12, the second inorganic filler is preferably at least one selected from the group consisting of aluminum oxide, aluminum nitride, boron nitride, silicon nitride, and silicon carbide.

[0073] Examples of the shape of the second inorganic filler include a substantially spherical shape, a substantially plate shape, a substantially needle shape, and an irregular shape, and a substantially spherical shape is preferable. The average particle diameter of the second inorganic filler (when the second inorganic filler has a shape other than a substantially spherical shape, it is the average value of the maximum length of the second inorganic filler) is preferably 0.1 μm or more, more preferably 0.5 μm or more. The average particle diameter is preferably 50 μm or less, more preferably 20 μm or less, and still more preferably 10 μm or less. The surface of the second inorganic filler may be partially or entirely treated with a surface treatment agent such as a silane coupling agent.

[0074] The content ratio R3 of the second inorganic filler in the second thermosetting composition (sealing resin layer 12) is preferably 75% by mass or more, more preferably 78% by mass or more, and still more preferably 80% by mass or more. Such a configuration is preferable for ensuring the thermal conductivity of the sealing resin layer 12. Further, such a configuration is preferable for suppressing the expansion and contraction due to temperature change in the sealing resin layer 12. The content ratio R3 is preferably 95% by mass or less, more preferably 93% by mass or less, and still more preferably 91% by mass or less. Such a configuration is suitable for ensuring the fluidity of the sealing resin layer 12 in the pressing step described later. Further, from the viewpoint of ensuring the thermal conductivity of the sealing resin layer 12 and ensuring the thermal conductivity of the resin sheet X for sealing, preferably, the content ratio R3 of the second inorganic filler is larger than the content ratio R2 of the first inorganic filler.

[0075] The second thermosetting composition may contain other components. Examples of the other components include the same thermoplastic resins, pigments, and silane coupling agents as described above for the first thermosetting composition. The blending amounts of the other components are the same as those described above for the other components in the first thermosetting composition, for example.

[0076] The resin sheet X for sealing can be produced, for example, by forming a sealing resin layer 11 (first sealing resin layer) and a sealing resin layer 12 (second sealing resin layer) respectively, and then laminating the sealing resin layer 11 and the sealing resin layer 12.

[0077] The sealing resin layer 11 can be formed, for example, as follows. First, each component and a solvent described above for the first thermosetting composition are mixed at a predetermined ratio to prepare a varnish of the first thermosetting composition. Examples of the solvent include methyl ethyl ketone, ethyl acetate, and toluene. Next, the varnish is applied onto a substrate such as a release sheet to form a coating film, and then the coating film is dried by heating. Thereby, a resin film (first resin film) having a sheet shape and being in a semi-cured state is obtained as the sealing resin layer 11. A plurality of first resin films may be laminated to form the sealing resin layer 11.

[0078] The sealing resin layer 12 can be formed, for example, as follows. First, each component and a solvent described above for the second thermosetting composition are mixed at a predetermined ratio to prepare a varnish of the second thermosetting composition. Next, the varnish is applied onto a substrate such as a release sheet to form a coating film, and then the coating film is dried by heating. Thereby, a resin film (second resin film) having a sheet shape and being in a semi-cured state is obtained as the sealing resin layer 12. A plurality of second resin films may be laminated to form the sealing resin layer 12.

[0079] The resin sheet X for sealing may be produced by forming a sealing resin layer 11 on a base material and forming a sealing resin layer 12 on the sealing resin layer 11. Alternatively, the resin sheet X for sealing may be produced by forming a sealing resin layer 12 on a base material and forming a sealing resin layer 11 on the sealing resin layer 12.

[0080] The thickness of the sealing resin layer 11 is preferably 30 μm or more, more preferably 50 μm or more, still more preferably 60 μm or more. Such a configuration is preferable from the viewpoint of suppressing breakage of the sealing resin layer 11 in the pressing process described later. The thickness of the sealing resin layer 11 is, for example, 300 μm or less, more preferably 250 μm or less, still more preferably 200 μm or less, and particularly preferably 180 μm or less. Such a configuration is preferable for ensuring the fluidity of the resin sheet X for sealing and filling the gaps between adjacent chips with the sealing resin in the pressing process described later.

[0081] The thickness H2 of the sealing resin layer 12 is preferably 40 μm or more, more preferably 60 μm or more, still more preferably 80 μm or more, and particularly preferably 100 μm or more. Such a configuration is preferable from the viewpoint of suppressing breakage of the sealing resin layer 12 in the pressing process described later. The thickness H2 of the sealing resin layer 12 is, for example, 300 μm or less, preferably 250 μm or less, more preferably 200 μm or less, and particularly preferably 180 μm or less. Such a configuration is preferable for ensuring the fluidity of the resin sheet X for sealing and filling the gaps between adjacent chips with the sealing resin in the pressing process described later.

[0082] The ratio of the thickness H2 to the thickness H1 is preferably 1 or more, more preferably 2 or more, still more preferably 3 or more, and is also preferably 6 or less, more preferably 5 or less, still more preferably 4.5 or less. Such a configuration is preferable for balancing the fluidity of the entire resin sheet X for sealing while suppressing breakage of the sealing resin layer 11 in the pressing process described later.

[0083] The melt viscosity Z1 of the encapsulating resin layer 11 at 90°C is preferably 110 kPa·s or more, more preferably 120 kPa·s or more, still more preferably 150 kPa·s or more, and particularly preferably 180 kPa·s or more. Such a configuration is preferable for suppressing the over-entry of the encapsulating resin layer 11, which is softened once by high-temperature heating in the curing process described later, into the gap between the base material and the electronic component chip. The melt viscosity of the encapsulating resin layer can be determined by measuring the viscoelasticity of the encapsulating resin layer. The viscoelasticity measurement can be carried out using a rheometer. As the rheometer, for example, "HAAKE MARS III" manufactured by Thermo Fisher Scientific can be used. In the measurement, the frequency is set to 1 Hz, the strain value is set to 0.005%, the temperature range is set to 50°C to 90°C, and the heating rate is set to 30°C / min. Specifically, the melt viscosity can be determined by the measurement method described later for the examples.

[0084] The melt viscosity Z1 of the encapsulating resin layer 11 at 90°C is preferably 500 kPa·s or less, more preferably 400 kPa·s or less, and still more preferably 380 kPa·s or less. Such a configuration is preferable for ensuring the fluidity of the encapsulating resin layer 11 in the pressing process described later.

[0085] The melt viscosity Z2 of the encapsulating resin layer 12 at 90°C is preferably 1 kPa·s or more, more preferably 3 kPa·s or more, and is preferably 100 kPa·s or less, more preferably 80 kPa·s or less. Such a configuration is preferable for ensuring the fluidity of the encapsulating resin layer 12 in the pressing process described later.

[0086] The ratio of the melt viscosity Z1 to the melt viscosity Z2 is preferably 4 or more, more preferably 10 or more, still more preferably 20 or more, and particularly preferably 30 or more. Such a configuration is preferable for achieving both the low fluidity of the encapsulating resin layer 11 and the high fluidity of the encapsulating resin layer 12 in the encapsulating resin sheet X, which is softened once by high-temperature heating in the curing process described later. In the curing process, the high fluidity of the encapsulating resin layer 12 is useful for flattening the exposed surface on the side of the encapsulating resin layer 12 of the encapsulating resin sheet X.

[0087] The resin sheet X for sealing (sealing resin layers 11 and 12) has a thermal conductivity of 2 W / m·K or more after being cured by heating at 150°C for 1 hour. This thermal conductivity is preferably 2.2 W / m·K or more, more preferably 2.5 W / m·K or more, still more preferably 2.8 W / m·K or more, and particularly preferably 3 W / m·K or more. Such a configuration is suitable for ensuring good heat dissipation as a sealing resin material in the resin sheet X for sealing. The thermal conductivity of the resin sheet for sealing can be determined, for example, by the method described later with respect to the examples.

[0088] In the resin sheet X for sealing, the following entry length L shown in the entry length evaluation test in which the following first step to fourth step are carried out is preferably 50 μm or less, more preferably 30 μm or less, still more preferably 20 μm or less. Also, the entry length L is preferably 0 μm or more. Such a configuration is preferable for suppressing the over-entry of the sealing resin into the gap between the substrate and the electronic component chip in the electronic component chip sealing process including the pressing process and the curing process as described later in which the resin sheet X for sealing is used.

[0089] Entry length evaluation test First step: Prepare a dummy chip mounting substrate including a glass substrate and a dummy chip having a size of 1 mm × 1 mm × 200 μm in thickness, wherein the dummy chip is joined to the glass substrate via bumps in a state of facing the glass substrate with a gap therebetween, and the length from the glass substrate to the dummy chip in the gap is 50 μm. Second step: With the sealing resin layer 11 side of the resin sheet X for sealing in contact with the dummy chip on the glass substrate, press the resin sheet X for sealing toward the glass substrate under the conditions of a temperature of 70°C, a degree of vacuum of 1.6 kPa or less, a pressing force of 0.1 MPa, and a pressing time of 40 seconds by a vacuum flat press, and close the open edge of the gap with the sealing resin layer 11 that adheres to the glass substrate around the dummy chip. Third step: After the second step, cure the resin sheet X for sealing by heating at 150°C for 1 hour under atmospheric pressure. Step 4: After the third step, measure the penetration length L into the voids in the encapsulating resin sheet X.

[0090] Figures 2A to 2D illustrate a method of encapsulating an electronic component chip on a substrate using an encapsulating resin sheet X.

[0091] In this method, first, as shown in Figure 2A, prepare an encapsulating resin sheet X (preparation step).

[0092] Next, as shown in Figure 2B, place a workpiece W and the encapsulating resin sheet X between a first press plate P1 and a second press plate P2 provided in a flat press machine (placement step).

[0093] The workpiece W includes a substrate S and a plurality of chips 21. The substrate S is a base material that will be singulated into individual mounting substrates later and has a mounting surface Sa. Mounting terminals (not shown) are provided on the mounting surface Sa. The chip 21 is an electronic component chip such as a semiconductor chip and has a main surface 21a and a side surface 21b. External connection terminals (not shown) are provided on the main surface 21a. The chip 21 is mounted on the substrate S via bump electrodes 22 in a state of facing the substrate S with a gap G therebetween. Each bump electrode 22 is interposed between a terminal provided on the mounting surface Sa of the substrate S and a terminal provided on the main surface 21a of the chip 21, and electrically connects the substrate S and the chip 21.

[0094] The mounting height of the chip 21 on the substrate S (the height from the surface of the substrate S on the side opposite to the substrate S in the chip 21) is, for example, 200 μm or more, preferably 220 μm or more, more preferably 250 μm or more. The same mounting height is, for example, 400 μm or less, preferably 350 μm or less, more preferably 300 μm or less.

[0095] The separation distance between the substrate S and the chip 21 is, for example, 10 μm or more, preferably 15 μm or more, more preferably 20 μm or more. The same separation distance is, for example, 80 μm or less, preferably 60 μm or less, more preferably 50 μm or less.

[0096] The plurality of chips 21 are mounted on the mounting surface Sa of the substrate S with spaces therebetween in the plane direction. The space (mounting space) between adjacent chips 21 is, for example, 50 μm or more, preferably 100 μm or more, and more preferably 200 μm or more. The space between adjacent chips 21 is, for example, 10 mm or less, preferably 5 mm or less, and more preferably 1 mm or less.

[0097] In this step, the workpiece W is placed on the first pressing plate P1 such that the substrate S thereof contacts the first pressing plate P1. The sealing resin sheet X is laminated on the workpiece W such that the sealing resin layer 11 contacts the chip 21 of the workpiece W.

[0098] Next, as shown in FIG. 2C, the sealing resin sheet X and the workpiece W are pressed in the thickness direction D by the first pressing plate P1 and the second pressing plate P2 (pressing step). Specifically, with the sealing resin layer 11 side of the sealing resin sheet X in contact with the chip 21 on the substrate S, the sealing resin sheet X is pressed toward the substrate S while being heated and softened.

[0099] The pressing pressure is, for example, 0.01 MPa or more, preferably 0.05 MPa or more. The pressing pressure is, for example, 10 MPa or less, preferably 5 MPa or less. The pressing time is, for example, 0.3 minutes or more, preferably 0.5 minutes or less. The pressing time is, for example, 10 minutes or more, preferably 5 minutes or less. Further, the heating temperature during pressing is, for example, 40° C. or more, preferably 60° C. or more. The heating temperature is, for example, 100° C. or less, preferably 95° C. or less.

[0100] In this step, while maintaining the B-stage, the sealing resin sheet X deforms following the outer shape of the chip 21, covers the side surface 21b of each chip 21, and contacts the mounting surface Sa of the substrate S that does not overlap the chip 21 in plan view. The sealing resin layer 11 that adheres to the substrate S around the chip 21 closes the gap G along the side surface 21b of the chip 21 (the open edge of the gap G is closed).

[0101] The deformed resin sheet X for sealing is allowed to slightly enter the gap G between the substrate S and the chip 21. Specifically, the resin sheet X for sealing is allowed to have an entry length L1 that enters the gap G with reference to the side surface 21b of the chip 21.

[0102] The entry length L1 is preferably 50 μm or less, more preferably 30 μm or less. Such a configuration is suitable for securing an area where wiring can be formed on the mounting surface Sa of the substrate S and the main surface 21a of the chip 21. Therefore, it is useful for enhancing the functionality of the electronic component device as an electronic component package after singulation, which will be described later. Also, the entry length L1 is preferably 0 μm or more. Such a configuration is suitable for appropriately sealing the chip 21 and the gap G so that the gap G does not open outside the resin seal in the electronic component device after singulation.

[0103] Next, after taking out the work W sealed with the resin sheet X for sealing from the flat press machine, as shown in FIG. 2D, the resin sheet X for sealing is heated and cured (curing step). Thereby, a cured resin portion 10 is formed around each chip 21 on the substrate S, and each chip 21 is resin-sealed.

[0104] The heating temperature (cure temperature) is, for example, 100° C. or higher, preferably 120° C. or higher. The heating temperature (cure temperature) is, for example, 200° C. or lower, preferably 180° C. or lower. The heating time is, for example, 10 minutes or longer, preferably 30 minutes or longer. The heating time is, for example, 180 minutes or shorter, preferably 120 minutes or shorter.

[0105] In the cured resin sealing sheet X, the penetration length L2 in the void G is preferably 50 μm or less, more preferably 30 μm or less. Such a configuration is suitable for securing an area where wiring can be formed on the mounting surface Sa of the substrate S and the main surface 21a of the chip 21. Therefore, it is useful for enhancing the functionality of the electronic component device as an electronic component package after dicing, which will be described later. The penetration length L2 is preferably 0 μm or more. Such a configuration is suitable for appropriately sealing the chip 21 and the void G so that the void G does not open to the outside of the resin seal in the electronic component device after dicing.

[0106] Thereafter, for example, by blade dicing, the cured resin portion 10 (cured resin sealing sheet X) and the substrate S are cut along a predetermined line to obtain an electronic component device Y as an individualized electronic component package (dicing step). The thus obtained electronic component device Y includes a substrate S as a base material, a chip 21 mounted on the substrate S in a state of facing the substrate S with a void G therebetween, and a cured resin portion 10 formed from the resin sealing sheet X and sealing the chip 21 and the void G.

[0107] In the resin sealing sheet X, as described above, the sealing resin layer 11 on the side in contact with the chip 21 (the first side) contains a layered silicate compound. In the sealing resin layer 11, the layered silicate compound exhibits thixotropic properties such that its viscosity decreases when the sealing resin layer 11 is subjected to a pressing force compared to when it is not. Therefore, the configuration in which the sealing resin layer 11 contains a layered silicate compound is suitable for highly fluidizing the same layer in the pressing step (FIG. 2C) where the sealing resin layer 11 is subjected to a pressing force, while suppressing the viscosity decrease of the sealing resin layer 11 due to high-temperature heating in the curing step (FIG. 2D) to make the same layer less fluid. The high fluidization of the sealing resin layer 11 in the pressing step helps to form the cured resin portion 10 that appropriately covers the chip 21 from the resin sealing sheet X. The low fluidization of the sealing resin layer 11 in the curing step helps to prevent the sealing resin from excessively entering the void G between the substrate S and the chip 21 (over-penetration). The coexistence of such high fluidization and low fluidization in the sealing resin layer 11 is suitable for hermetically sealing the chip 21 on the substrate S.

[0108] Also, as described above, the thermal conductivity of the resin sheet X for sealing is 2 not less than W / m·K, preferably not less than 2.2 W / m·K, more preferably not less than 2.5 W / m·K, still more preferably not less than 2.8 W / m·K, and particularly preferably not less than 3 W / m·K. Such a configuration is suitable for ensuring good heat dissipation as the sealing resin material in the resin sheet X for sealing.

[0109] In addition, in the resin sheet X for sealing, as described above, the sealing resin layer 11 contains the first inorganic filler in addition to the layered silicate compound, and the sealing resin layer 12 contains the second inorganic filler. Such a configuration is suitable for ensuring the thermal conductivity of the resin sheet X for sealing, and thus helps to achieve a thermal conductivity of not less than 2 W / m·K after the sheet is cured.

[0110] As described above, the resin sheet X for sealing is suitable for achieving both heat dissipation and hollow sealing properties.

Examples

[0111] Examples are shown below to more specifically explain the present invention. The present invention is not limited to the examples. Also, specific numerical values such as compounding amounts (contents), physical property values, parameters, etc. used in the following description can be replaced with the upper limits (numerical values defined as "below" or "less than") or lower limits (numerical values defined as "above" or "exceeding") of the corresponding compounding amounts (contents), physical property values, parameters, etc. described in the above "Mode for Carrying Out the Invention".

[0112] 〔Production Examples 1 to 8〕 Each of the resin films of Preparation Examples 1 to 8 for forming a sealing resin layer was prepared as follows. First, with the formulation shown in Table 1, each component and methyl ethyl ketone as a solvent were mixed to prepare a composition (varnish) (in Table 1, the unit of each numerical value representing the composition is relative "parts by mass"). Next, the composition was applied onto a polyethylene terephthalate film (PET film) whose surface had been subjected to a silicone release treatment to form a coating film. Next, this coating film was heated and dried at 120°C for 2 minutes to prepare a resin film on the PET film (the resin film was in a B-stage state). The resin films of Preparation Examples 1 to 7 were prepared to have a thickness of 35 μm. The resin film of Preparation Example 8 was prepared to have a thickness of 50 μm.

[0113]

Table 1

[0114] Each component used in Preparation Examples 1 to 8 is as follows. Epoxy resin E1: "YSLV-80XY" manufactured by Nippon Steel Chemical Co., Ltd., bisphenol F type epoxy resin, high molecular weight epoxy resin, epoxy equivalent 191 g / eq, solid at room temperature, softening point 80°C Epoxy resin E2: "EPICLON EXA-4850-150" manufactured by DIC Corporation, bisphenol A type epoxy resin, molecular weight 900, epoxy equivalent 450 g / eq, liquid at room temperature Phenol resin: "LVR-8210DL" manufactured by Gunei Chemical Industry Co., Ltd., novolac type phenol resin, latent curing agent, hydroxyl equivalent 104 g / eq, solid at room temperature, softening point 60°C Acrylic resin: "HME-2006M" manufactured by Negami Kogyo Co., Ltd., carboxyl group-containing acrylic resin, acid value 32 mgKOH / g, weight average molecular weight 1.29 million, glass transition temperature (Tg) -13.9°C, methyl ethyl ketone solution with a solid content concentration of 20% by mass Silane coupling agent: "KBM-403" manufactured by Shin-Etsu Chemical Co., Ltd., 3-glycidoxypropyltrimethoxysilane Layered silicate compound: "Esven NX" manufactured by Hoojun Co., Ltd., organically modified bentonite whose surface is modified with dimethyldistearylammonium Alumina particles: "AC-9150SME" manufactured by Admatechs Co., Ltd., average particle size 3 μm) Boron nitride particles: "SGP" manufactured by Denka Co., Ltd., plate-shaped particles, average particle size 18 μm) Hardening accelerator: "2PHZ-PW" manufactured by Shikoku Kasei Kogyo Co., Ltd., 2-phenyl-4,5-dihydroxymethylimidazole Pigment: Carbon black: #20 manufactured by Mitsubishi Chemical Corporation, average particle size 50 nm Solvent: Methyl ethyl ketone

[0115] [Examples 1 to 6 and Comparative Example 1] Sealing resin sheets for Examples 1 to 6 and Comparative Example 1 were produced. Specifically, it is as follows.

[0116] In the production of the sealing resin sheet of Example 1, two resin films (thickness 35 μm) of Production Example 1 were laminated to form a first sealing resin layer (thickness 65 μm), and four resin films (thickness 50 μm) of Production Example 8 were laminated to form a second sealing resin layer (thickness 195 μm), and these first and second sealing resin layers were laminated. The lamination temperature was 90°C.

[0117] The sealing resin sheet of Example 2 was produced in the same manner as the sealing resin sheet of Example 1, except that the resin film of Production Example 2 was used instead of the resin film of Production Example 1. The sealing resin sheet of Example 3 was produced in the same manner as the sealing resin sheet of Example 1, except that the resin film of Production Example 3 was used instead of the resin film of Production Example 1. The sealing resin sheet of Example 4 was produced in the same manner as the sealing resin sheet of Example 1, except that the resin film of Production Example 4 was used instead of the resin film of Production Example 1. The sealing resin sheet of Example 5 was produced in the same manner as the sealing resin sheet of Example 1, except that the resin film of Production Example 5 was used instead of the resin film of Production Example 1. The sealing resin sheet of Example 6 was produced in the same manner as the sealing resin sheet of Example 1, except that the resin film of Production Example 6 was used instead of the resin film of Production Example 1. The sealing resin sheet of Comparative Example 12 was produced in the same manner as the sealing resin sheet of Example 1, except that the resin film of Production Example 7 was used instead of the resin film of Production Example 1.

[0118] <Melt viscosity> For the first sealing resin layer and the second sealing resin layer of each of the sealing resin sheets of Examples 1 to 6 and Comparative Example 1, the melt viscosity at 90 °C was measured as follows.

[0119] First, for each of the sealing resin sheets of Examples 1 to 6 and Comparative Example 1, 30 sheets of the above-mentioned resin films (thickness 35 μm) for forming the first sealing resin layer were laminated to prepare a first sample film (thickness 1 mm) for measurement. Next, viscoelasticity measurement of the first sample film was carried out. In this measurement, a rheometer (trade name "HAAKE MARS III", manufactured by Thermo Fisher Scientific) was used, and the first sample film was sandwiched between a heating hot plate in the apparatus and a parallel plate (diameter 8 mm) arranged in parallel to the hot plate, and the plate gap was set to 0.8 mm. Then, the viscosity of the first sample film was measured under the conditions of a frequency of 1 Hz, a strain value of 0.005%, a temperature range of 50 °C to 90 °C, and a heating rate of 30 °C / min. On the other hand, 20 sheets of the above-mentioned resin films (thickness 50 μm) for forming the second sealing resin layer of the sealing resin sheets of Examples 1 to 6 and Comparative Example 1 were laminated to prepare a second sample film (thickness 1 mm) for measurement. Viscoelasticity measurement similar to the above-mentioned viscoelasticity measurement was carried out except that the second sample film was used instead of the first sample film. The melt viscosity Z1 (kPa·S) at 90 °C of the first sealing resin layer and the melt viscosity Z2 (kPa·S) at 90 °C of the second sealing resin layer are shown in Table 2. Table 2 also shows the ratio of the melt viscosity Z1 to the melt viscosity Z2.

[0120] <Thermal conductivity> For each of the sealing resin sheets of Examples 1 to 6 and Comparative Example 1, the thermal conductivity after curing was examined. Specifically, it is as follows.

[0121] First, the resin sheet for sealing was heated at 150°C for 30 minutes under normal pressure to cure it. Then, for the cured resin sheet for sealing, the thermal diffusivity, specific heat, and specific gravity were each measured. The thermal diffusivity was measured using a xenon flash method thermal measurement device (product name "LFA447 nanoflash", manufactured by Netzsch Japan). The specific heat was measured using a differential scanning calorimeter (product name "DSC Q-2000", manufactured by TA instrument) in accordance with the JIS-7123 standard. The specific gravity was measured by the Archimedes method using an electronic balance (product name "AEL-200", manufactured by Shimadzu Corporation). And the thermal conductivity of the cured resin sheet for sealing was determined from the following formula. The thermal conductivity after curing (W / mk) is shown in Table 2.

[0122] Thermal conductivity = Thermal diffusivity × Specific heat × Specific gravity

[0123] 〈Evaluation of Penetration Length〉 The hollow sealing properties of the resin sheets for sealing in Examples 1 to 6 and Comparative Example 1 were examined. Specifically, it was as follows.

[0124] First, as shown in FIG. 3A, a sample sheet X' (10 mm in length × 10 mm in width) was prepared from the resin sheet for sealing. The sample sheet X' includes a first sealing resin layer 11 and a second sealing resin layer 12 in order in the thickness direction.

[0125] On the other hand, as a work W, a dummy chip mounting substrate was prepared. The dummy chip mounting substrate includes a glass substrate S and a plurality of dummy chips 21' (1 mm × 1 mm × 200 μm in thickness). The dummy chips 21' are bonded to the substrate S via bumps electrode 22 in a state of facing the substrate S with a gap G therebetween. The dummy chips 21' have a main surface 21a facing the substrate S and a side surface 21b. The mounting height of the dummy chips 21' is 300 μm. The mounting interval of the dummy chips 21' is 300 μm. The length from the substrate S to the dummy chips 21' in the gap G (the separation distance between the substrate S and the dummy chips 21') is 50 μm.

[0126] Next, as shown in FIG. 3B, the above-described workpiece W and sample sheet X' were placed between the first press plate P1 and the second press plate P2 provided in the flat press machine.

[0127] Next, as shown in FIG. 3C, the dummy chip 21' on the substrate S was sealed by the sample sheet X' under vacuum flat pressing under the sealing conditions of a temperature of 70°C, a degree of vacuum of 1.6 kPa or less, a pressing force of 0.1 MPa, and a pressing time of 40 seconds (pressing step).

[0128] Next, as shown in FIG. 3D, the sample sheet X' was cured by heating at 150°C for 1 hour under atmospheric pressure. Thereby, the cured resin portion 10 was formed.

[0129] Then, as shown in the enlarged view of FIG. 3D, with reference to the side surface 21b of the dummy chip 21', the length by which the sealing resin (a part of the first sealing resin layer 11) derived from the sample sheet X' entered the gap G between the dummy chip 21' and the substrate S from the side surface 21b was measured as the penetration length L (μm). The results are shown in Table 2.

[0130] According to each of the sealing resin sheets of Examples 1 to 6, the penetration length L was 0 μm or more and 50 μm or less, and the dummy chip 21' could be appropriately sealed in a hollow manner. On the other hand, in the sealing resin sheet of Comparative Example 1, in the pressing step, the first sealing resin layer 11 over-penetrated into the gap G between the substrate S and the dummy chip 21', and in the curing step, the cured resin portion 10 that over-penetrated into the gap G was formed.

[0131]

Table 2

Description of Reference Numerals

[0132] X Sealing resin sheet H Thickness direction 11 Sealing resin layer (first sealing resin layer) 12 Sealing resin layer (second sealing resin layer) W Workpiece S substrate Mounting surface of Sa 21 Electronic component chip Main surface of 21a Side surface of 21b 22 Bump electrode P1 First press flat plate P2 Second press flat plate Y Electronic component device 10 Cured resin part

Claims

1. A resin sheet for sealing, comprising a first sealing resin layer and a second sealing resin layer in order in the thickness direction, wherein the first sealing resin layer contains a first thermosetting resin, a layered silicate compound, and a first inorganic filler other than the layered silicate compound, the second sealing resin layer contains a second thermosetting resin and a second inorganic filler, the first inorganic filler is at least one selected from the group consisting of aluminum oxide, aluminum nitride, boron nitride, silicon nitride, and silicon carbide, the mass ratio of the amount of the layered silicate compound to the total amount of the layered silicate compound and the first inorganic filler in the first sealing resin layer is 0.01 or more and 0.059 or less, A resin sheet for sealing having a thermal conductivity of 2 W / m·K or more after curing.

2. The resin sheet for sealing according to claim 1, wherein the ratio of the melt viscosity of the first sealing resin layer at 90°C to the melt viscosity of the second sealing resin layer at 90°C is 4 or more.

3. The resin sheet for sealing according to claim 1 or 2, wherein the melt viscosity of the first sealing resin layer at 90°C is 110 kPa·s or more and 500 kPa·s or less.

4. The resin sheet for sealing according to any one of claims 1 to 3, wherein the second inorganic filler is at least one selected from the group consisting of aluminum oxide, aluminum nitride, boron nitride, silicon nitride, and silicon carbide.

5. The resin sheet for sealing according to any one of claims 1 to 4, wherein the content ratio of the inorganic filler in the first sealing resin layer is 83% by mass or more.

6. The resin sheet for sealing according to any one of claims 1 to 5, wherein the content ratio of the inorganic filler in the first sealing resin layer is 90% by mass or less.

7. In the entry length evaluation test in which the following first step to fourth step are carried out, the following entry length L shown is 0 μm or more and 50 μm or less. The resin sheet for sealing according to any one of claims 1 to 6. Entry length evaluation test First step: Prepare a dummy chip mounting substrate including a glass substrate and a dummy chip having a size of 1 mm × 1 mm × 200 μm in thickness, wherein the dummy chip is joined to the glass substrate via bumps in a state of facing the glass substrate with a gap therebetween, and the length from the glass substrate to the dummy chip in the gap is 50 μm. Second step: With the first sealing resin layer side of the resin sheet for sealing in contact with the dummy chip on the glass substrate, press the resin sheet for sealing toward the glass substrate by a vacuum flat press under the conditions of a temperature of 70°C, a degree of vacuum of 1.6 kPa or less, a pressing force of 0.1 MPa, and a pressing time of 40 seconds, and close the open edge of the gap with the first sealing resin layer that adheres to the glass substrate around the dummy chip. Third step: After the second step, cure the resin sheet for sealing by heating at 150°C for 1 hour under atmospheric pressure. Fourth step: After the third step, measure the entry length L into the gap in the resin sheet for sealing.

8. A base material, An electronic component chip mounted on the base material in a state of facing the base material with a gap therebetween, An electronic component device comprising a cured resin part formed from the resin sheet for sealing according to any one of claims 1 to 7 and sealing the electronic component chip and the gap.

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