Resin sheet for sealing

Abstract

To provide a sealing resin sheet for resin-sealing an electronic component chip mounted on a base material in a state of facing a base material via a gap, which is suitable for suppressing warpage in a resin-sealed body.SOLUTION: A sealing resin sheet X according to the present invention includes a first sealing resin layer 11 and a second sealing resin layer 12 in order in the thickness direction T. The first sealing resin layer 11 includes a first thermosetting resin and a first inorganic filler. The second sealing resin layer 12 includes a second thermosetting resin and a second inorganic filler, is thicker than the first sealing resin layer 11, and has a glass transition temperature of 50°C or higher and 100°C or lower after curing.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a resin sheet for sealing.

Background Art

[0002] Conventionally, an electronic component chip on a mounting substrate may be sealed with a resin sheet for sealing. The resin sheet for sealing is a sheet-like sealing resin material containing a thermosetting resin. The electronic component chip is mounted on the substrate, for example, in a state of facing the substrate with a gap therebetween. In such a process of sealing the electronic component chip, for example, a resin sheet for sealing having a predetermined thickness is pressed by a flat press machine against a plurality of electronic component chips (facing the substrate with a gap therebetween) that are bonded on the same surface of the substrate and are separated from each other. As a result, the resin sheet for sealing is softened by heating, plastically deformed, and covers each electronic component chip (pressing step). Then, the resin sheet for sealing covering the electronic component chip is cured by heating at a high temperature (curing step). Thereafter, for example, by blade dicing, the cured resin sheet for sealing is cut together with the substrate, and individual pieces are formed into each resin-sealed body. Technologies related to such resin sealing of electronic component chips are described, for example, in Patent Document 1 below.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the above-described resin sheet for sealing, in the pressing step, it is required to be fluidized in a heat-softened state and the surface (exposed surface) on the side opposite to the electronic component chip is flattened (requirement for high fluidity). Further, on the side of the resin sheet for sealing facing the electronic component chip, in the curing step, it is required that the sealing resin that is once softened by high-temperature heating does not enter the gap between the mounting substrate and the electronic component chip too much (requirement for low fluidity). Thus, different characteristics regarding fluidity during heat softening are required for the resin sheet for sealing on the side opposite to the electronic component chip (the side opposite to the electronic component chip) and the side of the electronic component chip.

[0005] In addition, internal stress is generated in the resin sheet for sealing (sealing resin material) that has been heat-cured in the curing step. This internal stress may cause warping in the workpiece obtained through the curing step (for example, a plurality of electronic component chips on a substrate are sealed by the resin sheet for sealing). If the warping of the workpiece is too large, the process after the curing step cannot be properly executed. For example, laser marking cannot be properly performed on the surface of the resin-sealed body. For example, the workpiece cannot be diced because it cannot be properly fixed to the adhesive surface of the dicing tape.

[0006] The present invention provides a sheet for resin-sealing an electronic component chip mounted on a base material in a state of facing the base material with a gap therebetween, which is suitable for suppressing warping in the resin-sealed body, the resin sheet for sealing.

Means for Solving the Problems

[0007] The present invention [1] is a resin sheet for sealing including a first sealing resin layer and a second sealing resin layer provided in order in the thickness direction, wherein the first sealing resin layer includes a first thermosetting resin and a first inorganic filler, the second sealing resin layer includes a second thermosetting resin and a second inorganic filler, and is thicker than the first sealing resin layer and has a glass transition temperature of 50°C or higher and 100°C or lower after curing, including the resin sheet for sealing.

[0008] The resin sheet for encapsulation can be used to encapsulate an electronic component chip mounted on a base material in a state of facing the base material with a gap therebetween through the following pressing process and curing process. In the pressing process, with the first encapsulation resin layer side of the resin sheet for encapsulation in contact with the electronic component chip on the base material, the sheet is pressed toward the base material while being heated and softened (the gap is closed along the side surface of the electronic component chip by the first encapsulation resin layer that adheres to the base material around the electronic component chip). In the curing process, the resin sheet for encapsulation covering the electronic component chip is further heated to a higher temperature and cured. The resin sheet for encapsulation is suitable for exhibiting different characteristics by making the compositions of the first encapsulation resin layer disposed on the side of the electronic component chip and the second encapsulation resin layer disposed on the opposite side of the electronic component chip different in such an encapsulation process. Specifically, in the pressing process, while causing the second encapsulation resin layer to exhibit high fluidity so that the flattening of the exposed surface on the opposite side of the electronic component chip progresses, in the curing process, it is suitable for causing the first encapsulation resin layer to exhibit low fluidity so that the encapsulation resin that is once softened by high-temperature heating does not enter the gap between the base material and the electronic component chip too much.

[0009] Also, in the resin sheet for encapsulation as described above, the glass transition temperature after curing of the second encapsulation resin layer, which is thicker than the first encapsulation resin layer, is 50°C or higher and 100°C or lower. A configuration in which the glass transition temperature after curing of the second encapsulation resin layer is this low is suitable for suppressing internal stress in the second encapsulation resin layer after being cured through high-temperature heating and then cooled to, for example, room temperature. Suppression of internal stress in the second encapsulation resin layer, which is thicker than the first encapsulation resin layer, is suitable for suppressing warpage in a resin encapsulation body manufactured using the resin sheet for encapsulation. The resin sheet for encapsulation is suitable for suppressing warpage of the manufactured resin encapsulation body even when it has an asymmetric laminated structure in the thickness direction with the first encapsulation resin layer and the second encapsulation resin layer having different compositions (in contrast, a conventional thermosetting resin sheet having an asymmetric laminated structure is more likely to warp after heat curing than a thermosetting resin sheet having a single-layer structure).

[0010] The present invention [2] includes the sealing resin sheet described in the above [1], wherein the second thermosetting resin contains n types (n is an integer of 1 or more) of epoxy resins ERk (k = 1, 2, 3, ···, n), and the epoxy equivalent AEk (g / eq) and mass ratio Wk of the epoxy resin ERk satisfy the following formula (1).

[0011]

Number

[0012] Such a configuration (a configuration in which the weight-average epoxy equivalent of the epoxy resin in the second sealing resin layer is large enough to satisfy formula (1)) is suitable for lowering the glass transition temperature after curing of the second sealing resin layer. Therefore, the configuration is suitable for suppressing the internal stress of the second sealing resin layer that has been cured through high-temperature heating and then cooled to room temperature, for example. Accordingly, it is suitable for suppressing the warpage of the resin-sealed body manufactured using the present sealing resin sheet.

[0013] The present invention [3] is a sealing resin sheet including 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 and a first inorganic filler, the second sealing resin layer contains a second thermosetting resin and a second inorganic filler, and is thicker than the first sealing resin layer, and the second thermosetting resin contains n types (n is an integer of 1 or more) of epoxy resins ERk (k = 1, 2, 3, ···, n), and the epoxy equivalent AEk (g / eq) and mass ratio Wk of the epoxy resin ERk satisfy the following formula (1).

[0014]

Number

[0015] The resin sheet for sealing of the present invention [3] can be used in the same manner as the resin sheet for sealing of the present invention [1]. It is suitable for exhibiting different characteristics by varying the composition between a first sealing resin layer disposed on the electronic component chip side and a second sealing resin layer disposed on the opposite side of the electronic component chip. Specifically, in the pressing process, high fluidity is exhibited in the second sealing resin layer so that the flattening of the exposed surface on the opposite side of the electronic component chip progresses. On the other hand, in the curing process, it is suitable for exhibiting low fluidity in the first sealing resin layer so that the sealing resin that softens once by high-temperature heating does not enter too much into the gap between the base material and the electronic component chip. Further, as described above, in this resin sheet for sealing, the weight-average epoxy equivalent of the epoxy resin in the second sealing resin layer is 300 g / eq or more. A configuration in which the weight-average epoxy equivalent of the epoxy resin in the second sealing resin layer is as large as this is suitable for lowering the glass transition temperature after curing of the second sealing resin layer. Therefore, this configuration is suitable for suppressing the internal stress of the second sealing resin layer that has been cured through high-temperature heating and then cooled to room temperature, for example. Accordingly, it is suitable for suppressing the warpage of the resin-sealed body manufactured using this resin sheet for sealing. Even when the resin sheet for sealing has a laminated structure that is asymmetric in the thickness direction with a first sealing resin layer and a second sealing resin layer having different compositions, it is suitable for suppressing the warpage of the resin-sealed body to be manufactured.

[0016] The present invention [4] includes the resin sheet for sealing according to any one of [1] to [3] above, wherein the coefficient of linear expansion Z (ppm / °C) after curing and the tensile storage modulus E' (GPa) after curing in the second sealing resin layer satisfy the following formula (2).

[0017]

Equation

[0018] Such a configuration is suitable for suppressing the internal stress of the second sealing resin layer that has been cured through high-temperature heating and then cooled to room temperature, for example. Accordingly, it is suitable for suppressing the warpage of the resin-sealed body manufactured using this resin sheet for sealing.

[0019] The present invention [5] includes the resin sheet for sealing according to any one of [1] to [4] above, wherein the first sealing resin layer has an average linear expansion coefficient of 20 ppm / °C or less in the temperature range from -40°C to the glass transition temperature after curing, and the second sealing resin layer has an average linear expansion coefficient of 20 ppm / °C or less in the temperature range from -40°C to the glass transition temperature after curing.

[0020] Such a configuration is suitable for suppressing the internal stress in the first and second sealing resin layers that have been cured through high-temperature heating and then cooled to room temperature, for example, in the present resin sheet for sealing. Therefore, it is suitable for suppressing warping in the resin-sealed body manufactured using the present resin sheet for sealing.

[0021] The present invention [6] includes the resin sheet for sealing according to any one of [1] to [5] above, wherein the first inorganic filler is a layered silicate compound.

[0022] Such a configuration is suitable for thickening the first sealing resin layer by adding the first inorganic filler and expressing thixotropic properties in the first sealing resin layer, where the viscosity becomes lower when receiving a pressing force than when not receiving it. The expression of thixotropic properties in the first sealing resin layer is suitable for the first sealing resin layer and the second sealing resin layer to soften and flow under a pressing force and deform following the outer shape of the electronic component chip in the above-mentioned pressing process. The thickening of the first sealing resin layer is suitable for suppressing the decrease in the viscosity of the first sealing resin layer due to the increase in temperature in the above-mentioned curing process and suppressing the excessive entry of the sealing resin into the voids.

Brief Description of the Drawings

[0023]

Figure 1

Figure 2

Embodiments for Carrying Out the Invention

[0024] As an embodiment of the resin sheet for encapsulation of the present invention, the resin sheet for encapsulation X is a sheet-like encapsulating resin material for encapsulating an electronic component chip such as a semiconductor chip. As shown in FIG. 1, it includes a first encapsulating resin layer 11 and a second encapsulating resin layer 12 in order in the thickness direction. The resin sheet for encapsulation X preferably consists only of the first encapsulating resin layer 11 and the second encapsulating resin layer 12 disposed on one surface in the thickness direction of the first encapsulating resin layer 11.

[0025] The first encapsulating resin layer 11 is a layer formed from a first thermosetting composition. The first thermosetting composition includes a first thermosetting resin and a first inorganic filler. That is, the first encapsulating resin layer 11 includes a first thermosetting resin and a first inorganic filler. The first encapsulating resin layer 11 is in an uncured state (state of A stage) or a semi-cured state (state of B stage).

[0026] 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.

[0027] 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.

[0028] 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 weighted 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 weighted 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.

[0029] 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 with excellent sealing reliability. As the phenolic resin, a novolac-type phenolic resin is preferably used. Examples of the novolac-type phenolic resin include a phenol novolac resin, a phenol aralkyl resin, a trishydroxyphenylmethane novolac resin, a cresol novolac resin, a tert-butylphenol novolac resin, and a nonylphenol novolac resin. These phenolic resins may be used alone or in combination of two or more.

[0030] In the first thermosetting composition, the amount of hydroxyl groups in the phenolic resin as a curing agent with respect 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 with respect to 1 equivalent of epoxy groups of the epoxy resin is preferably 1.5 equivalents or less, more preferably 1.2 equivalents or less. Further, the blending amount of the phenolic resin as a curing agent with respect 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 with respect 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.

[0031] 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.

[0032] Examples of the first inorganic filler include phyllosilicate compounds and inorganic fillers other than phyllosilicate compounds. The first inorganic filler preferably contains a phyllosilicate compound and an inorganic filler other than the phyllosilicate compound.

[0033] The phyllosilicate 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 phyllosilicate compound include smectite, kaolinite, halloysite, talc, and mica. Examples of smectite include montmorillonite, beidellite, nontronite, saponite, hectorite, sauconite, and stevensite. As the phyllosilicate compound, smectite is preferably used because it is easily mixed with the thermosetting resin, and montmorillonite is more preferably used.

[0034] 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, preferably, a layered silicate compound with a surface modified by an organic component is used, more preferably, an organic modified smectite with a surface modified by an organic component is used, and still more preferably, an organic modified bentonite with a surface modified by an organic component is used.

[0035] 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, preferably ammonium is used, and more preferably dimethyldistearylammonium is used.

[0036] As the organic layered silicate compound, preferably, an organically modified smectite whose surface is modified with ammonium is used, and more preferably, an organically modified bentonite whose surface is modified with dimethyldistearylammonium is used.

[0037] The average particle diameter of the layered silicate compound is preferably 1 nm or more, more preferably 5 nm or more, and still more preferably 10 nm or more. The average particle diameter of the layered silicate compound is preferably 100 μm or less, more preferably 50 μm or less, and still more preferably 10 μm or less. 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, the particle size distribution measurement method in the laser scattering method.

[0038] As the layered silicate compound, commercially available products can be used. Examples of commercially available products of organically modified bentonite include the Esbent series (manufactured by Hoejung Co., Ltd.).

[0039] The content ratio of the layered silicate compound in the first thermosetting composition (that is, the content ratio of the layered silicate compound in the first sealing resin layer 11) is preferably 1% by mass or more, more preferably 1.2% by mass or more, and still more preferably 1.4% by mass or more. Such a configuration is suitable for exhibiting thixotropic properties in which the first 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 of the layered silicate compound in the first thermosetting composition is preferably 6% by mass or less, more preferably 5% by mass or less, and still more preferably 4% by mass or less.

[0040] Examples of inorganic fillers other than the layered silicate compound include silicon compounds such as silica and silicon nitride (silicon compounds other than the layered silicate compound), and silicate compounds other than the layered silicate compound such as orthosilicate, solo silicate, and ino silicate. Examples of inorganic fillers other than the layered silicate compound also include aluminum hydroxide, magnesium hydroxide, calcium carbonate, magnesium carbonate, calcium oxide, magnesium oxide, aluminum oxide, aluminum nitride, aluminum borate whisker, and boron nitride. These inorganic fillers may be used alone or in combination of two or more. As the inorganic filler, a silicon compound other than the layered silicate compound is preferably used, and silica is more preferably used.

[0041] Examples of the shape of the inorganic filler other than the layered silicate compound include a substantially spherical shape, a substantially plate shape, a substantially needle shape, and an irregular shape, and the substantially spherical shape is preferred.

[0042] The average particle diameter of the inorganic filler other than the layered silicate compound (when the inorganic filler has a shape other than the substantially spherical shape, it is 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. The average particle diameter of the inorganic filler is determined as the D50 value (cumulative 50% median diameter) based on the particle size distribution obtained by the particle size distribution measurement method in the laser scattering method, for example.

[0043] The surface of the inorganic filler other than the layered silicate compound may be partially or entirely treated with a surface treatment agent such as a silane coupling agent.

[0044] The content ratio of the inorganic filler other than the layered silicate compound in the first thermosetting composition is preferably 50% by mass or more, more preferably 60% by mass or more, still more preferably 70% by mass or more. Such a configuration is suitable for suppressing expansion and contraction due to temperature changes in the first sealing resin layer 11. The content ratio is preferably 90% by mass or less, more preferably 85% by mass or less, still more preferably 80% by mass or less. Such a configuration is suitable for avoiding excessive thickening of the first thermosetting composition and ensuring the fluidity of the first sealing resin layer 11 in the pressing process described later.

[0045] The content ratio of the first inorganic filler in the first thermosetting composition is preferably 50% by mass or more, more preferably 60% by mass or more, still more preferably 70% by mass or more. Such a configuration is suitable for suppressing expansion and contraction due to temperature changes in the first sealing resin layer 11. The content ratio is preferably 90% by mass or less, more preferably 87% by mass or less, still more preferably 84% by mass or less. Such a configuration is suitable for avoiding excessive thickening of the first thermosetting composition and ensuring the fluidity of the first sealing resin layer 11 in the pressing process described later.

[0046] The ratio of the layered silicate compound in the first inorganic filler is preferably 1% by mass or more, more preferably 1.5% by mass or more, still more preferably 2% by mass or more. The ratio is preferably 8% by mass or less, more preferably 7% by mass or less, still more preferably 6.5% by mass or less. These configurations are suitable for achieving a good balance among suppressing expansion and contraction due to temperature changes in the first sealing resin layer 11, ensuring fluidity in the pressing process described later, and expressing the above-mentioned thixotropic property.

[0047] The first thermosetting composition may contain other components. Examples of the other components include a thermoplastic resin, a pigment, and a silane coupling agent.

[0048] Examples of the thermoplastic resin include acrylic resin, 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, phenoxy resin, saturated polyester resin (such as PET), polyamideimide resin, fluororesin, and styrene-isobutylene-styrene block copolymer. These thermoplastic resins may be used alone or in combination of two or more kinds.

[0049] 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.

[0050] 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).

[0051] 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.

[0052] 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-methylpropanesulfonic acid, (meth)acrylamidepropanesulfonic acid, sulfopropyl (meth)acrylate, and (meth)acryloyloxynaphthalenesulfonic acid. Examples of the phosphoric acid group-containing monomers include 2-hydroxyethylacryloyl phosphate. These copolymerizable monomers may be used alone or in combination of two or more kinds.

[0053] 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.

[0054] 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 can also be determined by the method specifically described in JP-A-2007-51271.

[0055] Fox's equation 1 / (273 + Tg) = Σ[Wi / (273 + Tgi)]

[0056] 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 1,000,000 or less. The weight average molecular weight of the resin is measured by gel permeation chromatography (GPC) based on the standard polystyrene conversion value.

[0057] The content ratio of the thermoplastic resin in the first thermosetting composition is preferably 1% by mass or more, more preferably 2% by mass or more. The content ratio is preferably 80% by mass or less, more preferably 60% by mass or less.

[0058] 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.

[0059] 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-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.

[0060] The second 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 second sealing resin layer 12 includes a second thermosetting resin and a second inorganic filler. The second sealing resin layer 12 is in an uncured state (state of stage A) or a semi-cured state (state of stage B).

[0061] 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 3% by mass or more, more preferably 3.5% by mass or more. The content ratio of the second thermosetting resin in the second thermosetting composition is preferably 30% by mass or less, more preferably 25% by mass or less.

[0062] In this embodiment, the second thermosetting resin contains an epoxy resin. Examples of the epoxy resin include, for example, the epoxy resins described above for 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 are used.

[0063] In this embodiment, the epoxy equivalent of the epoxy resin contained in the second thermosetting resin is 300 g / eq or more. When the second thermosetting composition contains a plurality of epoxy resins, the weight-average epoxy equivalent of the plurality of epoxy resins is 300 g / eq or more in this embodiment. That is, the second thermosetting resin contains n types (n is an integer of 1 or more) of epoxy resins ERk (k = 1, 2, 3, ···, n), and the epoxy equivalent AEk (g / eq) and mass ratio Wk of the epoxy resin ERk satisfy the following formula (1). The unit of the numerical value on the right side in formula (1) is "g / eq".

[0064]

Equation

[0065] The epoxy equivalent of the epoxy resin contained in the second thermosetting resin (when the second thermosetting resin contains a plurality of epoxy resins, the weight-average epoxy equivalent) is preferably 350 g / eq or more, more preferably 400 g / eq or more. The weight-average epoxy equivalent is preferably 650 g / eq or less, more preferably 600 g / eq or less, and even more preferably 550 g / eq or less.

[0066] The second thermosetting resin preferably contains a phenolic resin as a curing agent for an epoxy resin. As the phenolic resin, a novolak-type phenolic resin is preferably used. In the second thermosetting composition, the amount of hydroxyl groups in the phenolic resin as a curing agent per equivalent of epoxy groups in the epoxy resin is preferably 0.1 equivalent or more, more preferably 0.2 equivalent or more. In the second thermosetting composition, the amount of hydroxyl groups in the phenolic resin as a curing agent per equivalent of epoxy groups in 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 with respect 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 with respect 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.

[0067] The second thermosetting composition preferably contains a curing accelerator. Examples of the curing accelerator include the curing accelerators described above for the first thermosetting composition. The blending amount of the curing accelerator with respect to 100 parts by mass of the second thermosetting resin is, for example, 0.05 part by mass or more and, for example, 5 parts by mass or less.

[0068] Examples of the second inorganic filler include the first inorganic filler described above for the first thermosetting composition. As the second inorganic filler, an inorganic filler other than a layered silicate compound is preferably used, more preferably a silicon compound other than a layered silicate compound is used, and even more preferably silica is used.

[0069] 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, with the substantially spherical shape being preferred. 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 lengths 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 average particle diameter of the second inorganic filler is determined as the D50 value (cumulative 50% median diameter) based on the particle size distribution obtained by a particle size distribution measurement method such as the laser scattering method, for example. The surface of the second inorganic filler may be partially or entirely treated with a surface treatment agent such as a silane coupling agent.

[0070] The content ratio of the second inorganic filler in the second thermosetting composition is preferably 50% by mass or more, more preferably 55% by mass or more, and still more preferably 58% by mass or more. Such a configuration is suitable for suppressing expansion and contraction due to temperature changes in the second sealing resin layer 12. The content ratio of the second inorganic filler in the second sealing resin layer 12 is preferably 95% by mass or less, more preferably 90% by mass or less, and still more preferably 88% by mass or less. Such a configuration is suitable for ensuring the fluidity of the second sealing resin layer 12 in the pressing process described later.

[0071] The second thermosetting composition may contain other components. Examples of other components include the same thermoplastic resin, pigment, and silane coupling agent as described above for the first thermosetting composition.

[0072] The resin sheet X for sealing can be produced, for example, by forming a first sealing resin layer 11 and a second sealing resin layer 12 respectively and then laminating the first sealing resin layer 11 and the second sealing resin layer 12. The first sealing resin layer 11 can be formed, for example, as follows. First, each of the above-described components for the first thermosetting composition is blended at a predetermined ratio to prepare the first thermosetting composition. If necessary, a solvent such as methyl ethyl ketone is further blended into the composition. Next, the composition 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, the first sealing resin layer 11 having a sheet shape and being in a semi-cured state can be formed. The second sealing resin layer 12 can be formed, for example, as follows. First, each of the above-described components for the second thermosetting composition is blended at a predetermined ratio to prepare the second thermosetting composition. If necessary, a solvent such as methyl ethyl ketone is further blended into the composition. Next, the composition 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, the second sealing resin layer 12 having a sheet shape and being in a semi-cured state can be formed. The resin sheet X for sealing may be produced by forming the first sealing resin layer 11 on a substrate and then forming the second sealing resin layer 12 on the first sealing resin layer 11. Alternatively, the resin sheet X for sealing may be produced by forming the second sealing resin layer 12 on a substrate and then forming the first sealing resin layer 11 on the second sealing resin layer 12.

[0073] The thickness of the first sealing resin layer 11 is, for example, 10 μm or more, preferably 25 μm or more, more preferably 30 μm or more. The thickness of the first sealing resin layer 11 is, for example, 3000 μm or less, preferably 1000 μm or less, more preferably 500 μm or less, still more preferably 300 μm or less, and particularly preferably 100 μm or less.

[0074] The second encapsulation resin layer 12 is thicker than the first encapsulation resin layer 11. The thickness of the second encapsulation resin layer 12 is, as long as it is greater than the thickness of the first encapsulation resin layer 11, for example, 20 μm or more, preferably 30 μm or more, more preferably 50 μm or more. The thickness of the second encapsulation resin layer 12 is, as long as it is greater than the thickness of the first encapsulation resin layer 11, for example, 3000 μm or less, preferably 1000 μm or less, more preferably 500 μm or less, particularly preferably 300 μm or less.

[0075] The ratio of the thickness of the second encapsulation resin layer 12 to the thickness of the first encapsulation resin layer 11 is preferably 1.1 or more, more preferably 1.2 or more, still more preferably 1.3 or more. The ratio of the thickness of the second encapsulation resin layer 12 to the thickness of the first encapsulation resin layer 11 is preferably 20 or less, more preferably 10 or less, still more preferably 5 or less.

[0076] The thickness of the resin sheet X for encapsulation is, for example, 20 μm or more, preferably 25 μm or more, more preferably 30 μm or more. The thickness of the resin sheet X for encapsulation is, for example, 6000 μm or less, preferably 3000 μm or less, more preferably 1500 μm or less, still more preferably 1000 μm or less, particularly preferably 500 μm or less, and especially preferably 300 μm or less.

[0077] In the resin sheet X for encapsulation, the second encapsulation resin layer 12 has a glass transition temperature of 50°C or more and 100°C or less after curing. "After curing" for the encapsulation resin layer means after the encapsulation resin layer is cured by heating at 150°C for 1 hour (the same applies to "after curing" described later). The glass transition temperature of the second encapsulation resin layer 12 is preferably 55°C or more, more preferably 60°C or more. The glass transition temperature is preferably 95°C or less, more preferably 90°C or less. The glass transition temperature of the second encapsulation resin layer 12 can be determined by the measurement method described later with respect to the examples. Also, the glass transition temperature of the second encapsulation resin layer 12 can be adjusted, for example, by selecting the type and adjusting the blending amount of the second thermosetting resin, and when using an epoxy resin as the second thermosetting resin, by adjusting the epoxy equivalent of the epoxy resin.

[0078] The linear expansion coefficient Z (ppm / °C) and the tensile storage modulus E’ (Pa) after curing in the second sealing resin layer 12 preferably satisfy the following formula (2). In formula (2), Z is the linear expansion coefficient (which is a function of temperature) of the second sealing resin layer 12 after curing in the range of 25°C to 150°C, and E’ is the tensile storage modulus (which is a function of temperature) of the second sealing resin layer 12 after curing in the range of 25°C to 150°C. Also, the unit of the numerical value on the right side in formula (2) is “Pa·°C”. The linear expansion coefficient Z and the tensile storage modulus E’ of the second sealing resin layer 12 can be obtained by the measurement method described later with respect to the examples.

Number

[0079] The integral value on the left side of formula (2) is preferably 0.8×10 13 Hereinafter, more preferably 0.7×10 13 Hereinafter. The integral value on the left side of formula (2) is, for example, 0.1×10 13 Hereinafter.

[0080] In the resin sheet X for sealing, preferably, after the first sealing resin layer 11 is cured by heating at 150°C for 1 hour, it has an average linear expansion coefficient (first average linear expansion coefficient) of 20 ppm / °C or less in the temperature range from -40°C to the glass transition temperature, and the second sealing resin layer 12 preferably has an average linear expansion coefficient (second average linear expansion coefficient) of 20 ppm / °C or less in the temperature range from -40°C to the glass transition temperature after being cured by heating at 150°C for 1 hour. The first average linear expansion coefficient is more preferably 19 ppm / °C or less, and still more preferably 17 ppm / °C or less. The second average linear expansion coefficient is more preferably 19 ppm / °C or less, still more preferably 17 ppm / °C or less, and particularly preferably 15 ppm / °C or less. The value of the average linear expansion coefficient can be obtained by the measurement method described later with respect to the examples.

[0081] The ratio of the second coefficient of linear expansion to the first coefficient of linear expansion is preferably 0.3 or more, more preferably 0.4 or more, and still more preferably 0.5 or more. This ratio is preferably 1.5 or less, more preferably 1.3 or less, and still more preferably 1.2 or less.

[0082] FIG. 2 shows a method of encapsulating an electronic component chip on a substrate using an encapsulating resin sheet X.

[0083] In this method, first, as shown in FIG. 2A, an encapsulating resin sheet X is prepared (preparation step).

[0084] Next, as shown in FIG. 2B, a workpiece W and an encapsulating resin sheet X are arranged between a first press plate P1 and a second press plate P2 provided in a flat press machine (arrangement step).

[0085] The workpiece W includes a substrate S and a plurality of chips 21. The substrate S is a base material that will be later separated into individual mounting substrates 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.

[0086] The separation distance between the substrate S and the chip 21 is, for example, 10 μm or more, preferably 15 μm or more, and more preferably 20 μm or more. This separation distance is, for example, 80 μm or less, preferably 60 mm or less, and more preferably 50 μm or less.

[0087] Further, the plurality of chips 21 are mounted on the mounting surface Sa of the substrate S with a space therebetween in the plane direction. The 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.

[0088] 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 first sealing resin layer 11 contacts the chips 21 of the workpiece W.

[0089] Next, as shown in FIG. 2C, the sealing resin sheet X and the workpiece W are pressed in the thickness direction T by the first pressing plate P1 and the second pressing plate P2 (pressing step). Specifically, with the first sealing resin layer 11 side of the sealing resin sheet X in contact with the chips 21 on the substrate S, the sealing resin sheet X is pressed toward the substrate S while being heated and softened.

[0090] 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.

[0091] In this step, while maintaining the B-stage, the sealing resin sheet X is deformed corresponding to the outer shape of the chips 21, covers the side surfaces 21b of the respective chips 21, and contacts the mounting surface Sa of the substrate S that does not overlap with the chips 21 in plan view. The first sealing resin layer 11 that adheres to the substrate S around the chips 21 closes the gap G along the side surfaces 21b of the chips 21 (the open edge ends of the gap G are closed).

[0092] 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.

[0093] 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 main surface 21a of the chip 21, and is also suitable for securing an area where wiring can be formed on the mounting surface Sa of the substrate S. Therefore, it is useful for enhancing the functionality of the resin seal. 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 to the outside of the resin seal in the resin seal after singulation described later.

[0094] Next, after taking out the workpiece 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).

[0095] 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.

[0096] The entry length L2 in the gap G in the cured resin sheet X for sealing 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 main surface 21a of the chip 21, and is also suitable for securing an area where wiring can be formed on the mounting surface Sa of the substrate S. Therefore, it is useful for enhancing the functionality of the resin seal. The entry length L2 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 to the outside of the resin seal in the resin seal after singulation described later.

[0097] The difference (L2 - L1) between the entry length L2 and the entry length L1 is preferably 10 μm or less, more preferably 7 μm or less, and is, for example, 0 μm or more. The ratio (L2 / L1) of the entry length L2 to the entry length L1 is preferably 2 or less, more preferably 1.5 or less, and is, for example, 1 or more.

[0098] Thereafter, for example, by blade dicing, the cured resin sheet X for sealing and the substrate S are cut along a predetermined cutting line to be separated into individual pieces for the resin-sealed body.

[0099] The resin sheet X for sealing is suitable for exhibiting different characteristics by making the composition different between the first sealing resin layer 11 disposed on the chip 21 side and the second sealing resin layer 12 disposed on the side opposite to the chip 21 in the above process. Specifically, in the pressing process described above with reference to FIG. 2C, while causing the second sealing resin layer 12 to exhibit high fluidity so that the flattening of the exposed surface on the side opposite to the chip 21 progresses, in the curing process described above with reference to FIG. 2D, it is suitable for causing the first sealing resin layer 11 to exhibit low fluidity so that the sealing resin that is once softened by high-temperature heating does not enter the gap G between the substrate S and the chip 21 too much.

[0100] As described above, the resin sheet X for sealing has a glass transition temperature after curing of the second sealing resin layer 12, which is thicker than the first sealing resin layer 11, of 50°C or higher, preferably 55°C or higher, more preferably 60°C or higher, and also 100°C or lower, preferably 95°C or lower, more preferably 90°C or higher. A configuration in which the glass transition temperature after curing of the second sealing resin layer 12 is this low is suitable for suppressing internal stress in the second sealing resin layer 12 that has been cured through high-temperature heating and then cooled to, for example, room temperature. Suppressing internal stress in the second sealing resin layer 12, which is thicker than the first sealing resin layer 11, is suitable for suppressing warping in the resin-sealed body (work) manufactured using the resin sheet X for sealing. Although the resin sheet X for sealing has an asymmetric laminated structure in the thickness direction with the first sealing resin layer 11 and the second sealing resin layer 12 having different compositions, it is suitable for suppressing warping in the manufactured resin-sealed body (in contrast, a conventional thermosetting resin sheet having an asymmetric laminated structure is more prone to warping after heat curing than a thermosetting resin sheet having a single-layer structure). Suppressing warping in the work is preferable for appropriately performing the process after the curing step. For example, it is preferable for appropriately performing laser marking on the surface of the resin-sealed body, and it is preferable for appropriately fixing the work to the adhesive surface of the dicing tape and appropriately dicing the work. Also, suppressing internal stress in the second sealing resin layer 12, which is thicker than the first sealing resin layer 11, is suitable for suppressing peeling of the sealing resin from the surface of the chip 21, and thus is suitable for ensuring high reliability of the resin-sealed body.

[0101] The second thermosetting resin in the second encapsulation resin layer 12 contains, as described above, n types (n is an integer of 1 or more) of epoxy resins ERk (k = 1, 2, 3, ···, n). The epoxy equivalent AEk (g / eq) and mass ratio Wk of the epoxy resin ERk satisfy the above formula (1), and the epoxy equivalent of the epoxy resin represented by the left side of formula (1) is preferably 350 g / eq or more, more preferably 400 g / eq or more. In the second encapsulation resin layer 12 after curing, the higher the epoxy equivalent of the epoxy resin, the lower the crosslinking point density in the polymer network structure (that is, the larger the distance between crosslinking points), and thus the coarser the polymer network structure. The coarser the polymer network structure, the lower the glass transition temperature of the second encapsulation resin layer 12 (after curing). Therefore, a configuration in which the weight-average epoxy equivalent of the epoxy resin in the second encapsulation resin layer 12 is large enough to satisfy formula (1) is suitable for lowering the glass transition temperature of the second encapsulation resin layer 12 after curing. Such a configuration is suitable for suppressing the internal stress of the second encapsulation resin layer 12 that has been cured through high-temperature heating in the curing process (Figure 2D) and then cooled to room temperature, for example. Therefore, it is suitable for suppressing the warping of the resin encapsulant manufactured using the resin encapsulation sheet X. Although the resin encapsulation sheet X includes the first encapsulation resin layer 11 and the second encapsulation resin layer 12 having different compositions and has an asymmetric laminated structure in the thickness direction, it is suitable for suppressing the warping of the resin encapsulant to be manufactured.

[0102] The coefficient of linear expansion Z (ppm / °C) after curing and the tensile storage modulus E' (Pa) after curing in the second encapsulation resin layer 12 preferably satisfy the above formula (2), as described above. The integral value represented by the left side of formula (2) is preferably 0.8×10 13 Hereinafter, more preferably 0.7×10 13 Hereinafter. Such a configuration is suitable for suppressing the internal stress of the second encapsulation resin layer 12 that has been cured through high-temperature heating in the curing process (Figure 2D) and then cooled to room temperature, for example. Therefore, it is suitable for suppressing the warping of the resin encapsulant manufactured using the resin encapsulation sheet X.

[0103] In the resin sheet X for sealing, as described above, the first average coefficient of linear expansion of the first sealing resin layer 11 is preferably 20 ppm / °C or less, more preferably 19 ppm / °C or less, still more preferably 17 ppm / °C or less, and the second average coefficient of linear expansion of the first sealing resin layer 11 is preferably 20 ppm / °C or less, more preferably 19 ppm / °C or less, still more preferably 17 ppm / °C or less, particularly preferably 15 ppm / °C or less. The ratio of the second coefficient of linear expansion to the first coefficient of linear expansion is preferably 0.3 or more, more preferably 0.4 or more, still more preferably 0.5 or more, and is preferably 1.5 or less, more preferably 1.3 or less, still more preferably 1.2 or less, as described above. These configurations are suitable for suppressing the internal stress in the first sealing resin layer 11 and the second sealing resin layer 12 after being cured through high-temperature heating in the curing process (FIG. 2C) and then cooled to room temperature, for example, in the resin sheet X for sealing. Therefore, they are suitable for suppressing warping in the resin-sealed body manufactured using the resin sheet X for sealing.

[0104] As described above, the first sealing resin layer 11 preferably contains a layered silicate compound. Such a configuration is suitable for expressing thixotropic properties in which the first sealing resin layer 11 thickens while having a lower viscosity when receiving a pressing force than when not receiving the pressing force. The expression of thixotropic properties in the first sealing resin layer 11 is suitable for the first sealing resin layer 11 and the second sealing resin layer 12 to soften and flow under a pressing force and deform following the outer shape of the chip 21 in the pressing process (FIG. 2C). The thickening of the first sealing resin layer 11 is suitable for suppressing the decrease in the viscosity of the first sealing resin layer 11 caused by the temperature rise and suppressing the excessive entry of the sealing resin into the void G in the curing process (FIG. 2D).

Examples

[0105] Examples are shown below to explain the present invention more specifically. 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".

[0106] [Production Examples 1 to 3] Each first resin film of Production Examples 1 to 3 for forming the first sealing resin layer was produced as follows. First, each component was mixed according to the compounding formulation shown in Table 1 to prepare a composition (varnish) (in Table 1, the unit of each numerical value representing the composition is a relative "part 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 produce a first resin film with a thickness of 50 μm on the PET film (the formed first resin film was in a B-stage state).

[0107] [Production Examples 4 to 7] Each second resin film of Production Examples 4 to 7 for forming the second sealing resin layer was produced as follows. First, each component was mixed according to the compounding formulation shown in Table 1 to prepare a composition (varnish). Next, the composition was applied onto a 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 form a resin film with a thickness of 50 μm on the PET film (the formed resin film was in a B-stage state). Then, two resin films with a thickness of 50 μm formed as described above from the varnish of the same composition were laminated to produce a second resin film with a thickness of 100 μm.

[0108] [Table 1]

[0109] Each component used in Production Examples 1 to 7 is as follows. Epoxy resin E1: "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) Epoxy resin E2: "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 E3: "EPPN-501HY" manufactured by Nippon Kayaku Co., Ltd. (polyfunctional epoxy resin, epoxy equivalent 169 g / eq, solid at room temperature, softening point 60 °C) Phenolic resin F1: "LVR-8210DL" manufactured by Gunei Chemical Industry Co., Ltd. (novolac type phenolic resin, latent curing agent, hydroxyl equivalent 104 g / eq, solid at room temperature, softening point 60 °C) Phenolic resin F2: "MEHC-7851SS" manufactured by Meiwafosis Co., Ltd. (phenol aralkyl resin, latent curing agent, hydroxyl equivalent 201 - 220 g / eq, solid at room temperature, softening point 64 - 85 °C) Phenolic resin F3: "TPM-100" manufactured by Gunei Chemical Industry Co., Ltd. (triphenylmethane type phenolic resin, latent curing agent, hydroxyl equivalent 98 g / eq, solid at room temperature, softening point 108.2 °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 solid content concentration of 20 mass%) Silane coupling agent: "KBM-403" manufactured by Shin-Etsu Chemical Co., Ltd. (3-glycidoxypropyltrimethoxysilane) Layered silicate compound: "Esven NX" manufactured by Hoejung Co., Ltd. (organophilic bentonite with surface modified by dimethyldistearylammonium) First silica particles: "FB-8SM" manufactured by Denka Co., Ltd. (spherical silica particles, average particle diameter 7.0 μm, without surface treatment) Second silica particles: "SC220G-SMJ" manufactured by Admatechs Co., Ltd. (spherical silica particles, average particle size 0.5 μm), surface-treated with 3-methacryloxypropyltrimethoxysilane ("KBM-503" manufactured by Shin-Etsu Chemical Co., Ltd.) (the silane coupling agent used for surface treatment is 1 part by mass with respect to 100 parts by mass of silica particles) Curing 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 (MEK)

[0110] [Examples 1 to 4, Comparative Examples 1 to 4] Sealing resin sheets of Examples 1 to 4 and Comparative Examples 1 to 4 were produced. Specifically, a sealing resin sheet with a thickness of 150 μm was produced by laminating a first resin film (first sealing resin layer) and a second resin film (second sealing resin layer) in the combinations shown in Table 2. The epoxy equivalent of the epoxy resin in the second sealing resin layer (weighted average epoxy equivalent when a plurality of epoxy resins are included in the second sealing material layer) is shown in Table 2.

[0111] 〈Glass transition temperature and coefficient of linear expansion〉 For the first sealing resin layer and the second sealing resin layer of each of the sealing resin sheets of Examples 1 to 4 and Comparative Examples 1 to 4, the glass transition temperature after curing and the average coefficient of linear expansion after curing were examined.

[0112] First, a sample film for measurement was prepared from the first sealing resin layer (each first resin film of Production Examples 1 to 3) and the second sealing resin layer (each second resin film of Production Examples 4 to 7). Specifically, four resin films (in the case of the resin films of Production Examples 1 to 3) or two resin films (in the case of the resin films of Production Examples 4 to 7) were stacked in the thickness direction to form a laminated film (thickness: 200 μm), and then a sample film (width: 4.5 mm × length: 16 mm × thickness: 200 μm) was cut out from the laminated film. Next, the sample film was cured by heating at 150°C for 1 hour. Next, the linear expansion coefficient and glass transition temperature of the sample film were measured under the following conditions using a thermomechanical analyzer (TMA) (TMA measurement). From the measurement results, for the cured sample film, the glass transition temperature and the average linear expansion coefficient in the temperature range from -40°C to the glass transition temperature were determined. The glass transition temperature Tg (°C) after curing of each second sealing resin layer, the first linear expansion coefficient Z1 (ppm / °C) after curing of each first sealing resin layer, and the second linear expansion coefficient Z2 (ppm / °C) after curing of each second sealing resin layer are shown in Table 2. Table 2 also shows the ratio (Z2 / Z1) of the second linear expansion coefficient Z2 to the first linear expansion coefficient Z1.

[0113] (Measurement conditions) Thermomechanical analyzer (TMA): Q400 TMA (manufactured by TA Instruments Japan) Mode: Tensile mode Heating rate: 1°C / min Modulation: ±5.000°C / 300 s Measurement temperature range: -40°C to 260°C

[0114] 〈Tensile storage modulus〉 The second sealing resin layer after curing of each of the sealing resin sheets of Examples 1 to 4 and Comparative Examples 1 to 4 was subjected to dynamic viscoelasticity measurement. In this measurement, specifically, a tensile storage elastic modulus between 25°C and 150°C was measured using a dynamic viscoelasticity measuring device (trade name "RSAIII", manufactured by TA Instruments). The sample piece for measurement (sample piece of the second sealing resin layer) has a size of 10 mm in width × 40 mm in length and has been heat-treated at a curing temperature of 150°C for 1 hour. Also, in the measurement, the initial chuck distance of the chuck for holding the sample piece was set to 22.5 mm, the measurement mode was set to the tensile mode, the measurement temperature range was set to -10°C to 260°C, the heating rate was set to 10°C / min, the frequency was set to 1 Hz, and the dynamic strain was set to 0.005%. Then, using the value of the tensile storage elastic modulus E' (which is a function of temperature) in the range of 25°C to 150°C obtained by this measurement and the value of the linear expansion coefficient Z (which is a function of temperature) in the range of 25°C to 150°C obtained by the above-described TMA measurement, integration was performed in the range of temperature from 25°C to 150°C in the following formula (3) (the upper limit of the integration range is the above-described curing temperature of the second sealing resin layer). The integrated value is shown in Table 2 as the value of formula (3).

[0115] [Number]

[0116] <Warp evaluation> For each of the sealing resin sheets of Examples 1 to 4 and Comparative Examples 1 to 4, the degree of warp after curing was examined. Specifically, first, a laminate sample including a 42 alloy plate having a size of 90 mm × 90 mm × 150 μm in thickness and a sealing resin sheet bonded to the entire one surface in the thickness direction of the 42 alloy plate was heated at 150°C for 1 hour, and then left standing at 25°C for 1 hour. Then, the maximum value of the distance between the placement surface on which the laminate sample was placed with the 42 alloy plate on the lower side and the edge of the laminate sample was measured as the amount of warp. The results are shown in Table 2.

[0117] <Reliability evaluation> For each of the resin sheets for sealing in Examples 1 to 4 and Comparative Examples 1 to 4, when both the first linear expansion coefficient Z1 of the first sealing resin layer and the second linear expansion coefficient Z2 of the second sealing resin layer are 20 ppm / °C or less, the reliability of the sealing resin material is evaluated as "good" (that is, in the resin-sealed body obtained using the same sheet, it is suitable for sufficiently suppressing peeling of the sealing resin from the surface of the electronic component chip and obtaining high reliability). When at least one of the first linear expansion coefficient Z1 and the second linear expansion coefficient Z2 exceeds 20 ppm / °C, it is evaluated that the reliability of the sealing resin material is "poor". The evaluation results are shown in Table 2.

[0118]

Table 2

Explanation of Symbols

[0119] X Resin sheet for sealing T Thickness direction 11 First sealing resin layer 12 Second sealing resin layer W Workpiece S Substrate Sa Mounting surface 21 Chip 21a Main surface 21b Side surface 22 Bump electrode P1 First press flat plate P2 Second press flat plate

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 and a first inorganic filler, the first inorganic filler contains a layered silicate compound and an inorganic filler other than the layered silicate compound, the second sealing resin layer contains a second thermosetting resin and an inorganic filler other than the layered silicate compound, is thicker than the first sealing resin layer, and has a glass transition temperature of 50°C or higher and 100°C or lower after curing, and a resin sheet for sealing, wherein the linear expansion coefficient Z (ppm / °C) and the tensile storage modulus E' (Pa) after curing in the second sealing resin layer satisfy the following formula (2). [Equation 1]

2. The resin sheet for sealing according to claim 1, wherein the second thermosetting resin contains n types (n is an integer of 1 or more) of epoxy resins ERk (k = 1, 2, 3,..., n), and the epoxy equivalent AEk (g / eq) and the mass ratio Wk of the epoxy resin ERk satisfy the following formula (1). [Equation 2]

3. 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 and a first inorganic filler, the first inorganic filler contains a layered silicate compound and an inorganic filler other than the layered silicate compound, the second sealing resin layer contains a second thermosetting resin and an inorganic filler other than the layered silicate compound, and is thicker than the first sealing resin layer, the second thermosetting resin contains n types (n is an integer of 1 or more) of epoxy resins ERk (k = 1, 2, 3,..., n), and the epoxy equivalent AEk (g / eq) and the mass ratio Wk of the epoxy resin ERk satisfy the following formula (1), A resin sheet for sealing, wherein the linear expansion coefficient Z (ppm / °C) and the tensile storage modulus E' (Pa) after curing in the second sealing resin layer satisfy the following formula (2). 【Equation 3】 【Equation 4】

4. The first sealing resin layer has an average linear expansion coefficient of 20 ppm / °C or less in the temperature range from -40°C to the glass transition temperature after curing, The second sealing resin layer has an average linear expansion coefficient of 20 ppm / °C or less in the temperature range from -40°C to the glass transition temperature after curing. The resin sheet for sealing according to any one of claims 1 to 3.

5. A resin sheet for sealing comprising 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 and a first inorganic filler, The first inorganic filler contains a layered silicate compound and an inorganic filler other than the layered silicate compound, The ratio of the content of the layered silicate compound to the content of the first inorganic filler is 6% or less, The second sealing resin layer contains a second thermosetting resin and an inorganic filler other than the layered silicate compound, is thicker than the first sealing resin layer, and has a glass transition temperature of 50°C or higher and 100°C or lower after curing. A resin sheet for sealing.

6. The resin sheet for sealing according to claim 5, wherein the second thermosetting resin contains n types (n is an integer of 1 or more) of epoxy resins ERk (k = 1, 2, 3,..., n), and the epoxy equivalent AEk (g / eq) and mass ratio Wk of the epoxy resin ERk satisfy the following formula (1). 【Equation 5】

7. A resin sheet for sealing comprising 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 and a first inorganic filler, The first inorganic filler contains a layered silicate compound and an inorganic filler other than the layered silicate compound. The ratio of the content ratio of the layered silicate compound to the content ratio of the first inorganic filler is 6% or less. The second encapsulating resin layer contains a second thermosetting resin and an inorganic filler other than the layered silicate compound, and is thicker than the first encapsulating resin layer. The second thermosetting resin contains n types (n is an integer of 1 or more) of epoxy resins ERk (k = 1, 2, 3,..., n), and the epoxy equivalent AEk (g / eq) and mass ratio Wk of the epoxy resin ERk satisfy the following formula (1). An encapsulating resin sheet. 【Equation 6】

8. The encapsulating resin sheet according to any one of claims 5 to 7, wherein the coefficient of linear thermal expansion Z (ppm / °C) after curing and the tensile storage modulus E' (Pa) after curing in the second encapsulating resin layer satisfy the following formula (2). 【Equation 7】

9. The first encapsulating resin layer has an average coefficient of linear thermal expansion of 20 ppm / °C or less in the temperature range from -40°C to the glass transition temperature after curing. The encapsulating resin sheet according to any one of claims 5 to 8, wherein the second encapsulating resin layer has an average coefficient of linear thermal expansion of 20 ppm / °C or less in the temperature range from -40°C to the glass transition temperature after curing.

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