Method for manufacturing an electrode-equipped curable resin sheet, electrode-equipped curable resin sheet, and thermosetting resin sheet

Abstract

This method for manufacturing a cured resin sheet with electrode includes a step for arranging a plurality of electronic component electrodes (20) on a temporary fixed surface (11) of a temporary fixed base material (10), a step for bonding a first surface (31) of a thermosetting resin sheet (30) to a first surface (11) of the temporary fixed base material (10) while embedding a plurality of electrodes (20) using the sheet, a step for thermally curing the resin sheet (30) to form a cured resin sheet (30A), a step for separating the temporary fixed base material (10) from the cured resin sheet (30A), and a step for grinding a second surface (32) side of the cured resin sheet (30A) and exposing the electrodes (20) on the second surface (32) side. A resin sheet (X) of the present invention is a thermosetting resin sheet for manufacturing the cured resin sheet with electrode, and has a tensile storage modulus of 2-18 GPa, inclusive, at 25°C after curing.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a cured resin sheet with electrodes, a cured resin sheet with electrodes, and a thermosetting resin sheet.

Background Art

[0002] In the manufacturing process of electronic component packages such as semiconductor packages, after an electronic component is mounted on a base material such as a mounting substrate, a cured resin portion that covers the electronic component is formed to seal the electronic component. When the electronic component is face-up mounted with respect to the base material, the terminals on the side of the electronic component opposite to the base material (the upper surface side of the electronic component) and the terminals of the base material are electrically connected via bonding wires. When the electronic component is face-down mounted with respect to the base material, conventionally, the terminals on the base material side of the electronic component and the terminals of the base material are electrically connected via electrodes such as bumps. Techniques related to the manufacture of electronic component packages are described in, for example, 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 case of the above-described face-up mounting, the cured resin portion that seals the electronic component is formed to a thickness such that the bonding wires extending from the upper surface side of the electronic component are embedded in the cured resin portion together with the electronic component. In the case of the above-described face-down mounting, the cured resin portion is formed to a thickness such that the electronic component at the height mounted via the electrode with respect to the base material is embedded in the cured resin portion. Therefore, conventionally, it may not be possible to manufacture an electronic component package with a sufficient thinness suitable for the application.

[0005] The present invention provides a method for manufacturing an electrode-equipped cured resin sheet suitable for manufacturing thin electronic component packages, an electrode-equipped cured resin sheet, and a thermosetting resin sheet used in the manufacture of said sheet. [Means for solving the problem]

[0006] The present invention [1] includes a method for manufacturing an electrode-equipped mounting substrate, comprising: a first step of arranging a plurality of electrodes for electronic components on the temporary fixing surface of a temporary fixing substrate having a temporary fixing surface; a second step of bonding the first surface of a thermosetting resin sheet having a first surface and a second surface opposite to the first surface to the temporary fixing surface of the temporary fixing substrate while embedding the plurality of electrodes for electronic components with the thermosetting resin sheet; a third step of thermosetting the thermosetting resin sheet to form a cured resin sheet; a fourth step of separating the temporary fixing substrate from the cured resin sheet; and a fifth step of grinding the second surface side of the cured resin sheet to expose the electrodes for electronic components on the second surface side.

[0007] According to this method, a cured resin sheet with electrodes is manufactured. This sheet comprises a sheet-like cured resin portion and a plurality of electrodes for electronic components held in the cured resin portion. Each of the plurality of electrodes has a first electrode surface exposed on one side in the thickness direction of the sheet and a second electrode surface exposed on the other side. The plurality of electrodes are positioned according to the type and number of electronic components to be mounted. Such a cured resin sheet with electrodes is suitable for manufacturing thin electronic component packages as follows.

[0008] First, an electronic component is mounted face-down on one side of an electrode-equipped cured resin sheet. In this face-down mounting, the electrode on the electrode-equipped cured resin sheet and the surface of the electronic component are in contact, and the electrodes on the sheet and the terminals on the surface of the electronic component are joined one-to-one. Next, a semi-cured sealing resin composition is supplied onto the electrode-equipped cured resin sheet so as to cover the electronic component. Then, the sealing resin composition covering the electronic component is cured by heating. This forms a cured resin portion around the electronic component on the electrode-equipped cured resin sheet. After that, the electronic component is separated into individual electronic component packages as needed. In the electronic component package thus obtained, the electronic component is sealed by the cured resin portion of the electrode-equipped cured resin sheet and the cured resin portion formed from the sealing resin composition, in a state where it can be externally connected via the electrodes of the electrode-equipped cured resin sheet. Since such an electronic component package is face-down mounted on the substrate with the electronic component in contact with the substrate, it is more suitable for thinning than conventional face-up type and face-down type electronic component packages. In other words, the electrode-equipped cured resin sheet obtained by the manufacturing method of the present invention is suitable for manufacturing thin electronic component packages.

[0009] The present invention [2] includes a method for producing the electrode-equipped cured resin sheet described in [1] above, wherein the thermosetting resin sheet has a tensile storage modulus of 2 GPa or more and 18 GPa or less at 25°C after curing.

[0010] This configuration is suitable for separating the temporary fixing substrate from the cured resin sheet while suppressing plastic deformation and cracking of the cured resin sheet in the fourth step described above.

[0011] The present invention [3] includes a curable resin sheet having a first surface and a second surface opposite to the first surface, and a plurality of electrodes for electronic components disposed within the curable resin sheet, each electrode having a first electrode surface exposed to the first surface and a second electrode surface exposed to the second surface.

[0012] A cured resin sheet with electrodes of this configuration can be manufactured by the manufacturing method described above and is suitable for manufacturing thin electronic component packages.

[0013] The present invention [4] includes a thermosetting resin sheet for manufacturing an electrode-equipped curing resin sheet, wherein, after curing, the thermosetting resin sheet has a tensile storage modulus of 2 GPa or more and 18 GPa or less at 25°C.

[0014] Such thermosetting resin sheets are suitable for separating the temporary fixing substrate from the cured resin sheet while suppressing plastic deformation and cracking in the cured resin sheet during the fourth step of the electrode-equipped cured resin sheet manufacturing method described above. Therefore, this thermosetting resin sheet is suitable for use in the manufacture of electrode-equipped cured resin sheets suitable for manufacturing thin electronic component packages.

[0015] The present invention [5] includes the thermosetting resin sheet described in [4] above, having a viscosity of 3 kPa·s or more and 100 kPa·s or less at 90°C.

[0016] This configuration is suitable for embedding electrodes with a thermosetting resin sheet while suppressing the formation of voids between the sheet and the electrodes in the second step of the electrode-attached curing resin sheet manufacturing method described above, at a temperature of 90°C or near that temperature.

[0017] The present invention [6] includes a thermosetting resin sheet as described in [4] or [5] above, having a mass W1 after a heat treatment at 150°C for 1 hour and a first standing period of 1 hour at 25°C and 40% relative humidity, and having a mass W2 after a second standing period of 168 hours at 85°C and 85% relative humidity, with a moisture absorption rate expressed as [(W2-W1) / W1] × 100 of 0.3% by mass or less.

[0018] Such a configuration is preferable for ensuring the sealing reliability of the cured resin portion formed from the thermosetting resin sheet.

[0019] The present invention [7] includes the thermosetting resin sheet according to any one of [4] to [6] having a relative permittivity of 4.2 or less at 10 GHz.

[0020] Such a configuration is preferable for reducing the transmission loss of a high-frequency signal passing through the cured resin portion formed from the thermosetting resin sheet.

Brief Description of Drawings

[0021] [Figure 1] It is a process diagram of one embodiment of a method for manufacturing a cured resin sheet with electrodes of the present invention. FIG. 1A shows an electrode arrangement process, FIG. 1B shows a bonding process, FIG. 1C shows a curing process, FIG. 1D shows a peeling process, and FIG. 1E shows a grinding process. [Figure 2] It is a schematic cross-sectional view of one embodiment of the thermosetting resin sheet of the present invention. [Figure 3] An example of a method of using a cured resin sheet with electrodes is shown. FIG. 3A shows a process of mounting an electronic component on a cured resin sheet with electrodes, FIG. 3B shows a process of supplying a thermosetting composition for sealing the electronic component, and FIG. 3C shows a process of curing the thermosetting composition.

Modes for Carrying Out the Invention

[0022] FIGS. 1A to 1E are process diagrams of one embodiment of a method for manufacturing a cured resin sheet with electrodes of the present invention. This manufacturing method includes an electrode arrangement process (FIG. 1A) as the first step, a bonding process (FIG. 1B) as the second step, a curing process (FIG. 1C) as the third step, a peeling process (FIG. 1D) as the fourth step, and a grinding process (FIG. 1E) as the fifth step. Specifically, it is as follows.

[0023] First, in the electrode arrangement process, as shown in FIG. 1A, electrodes 20 are arranged on a temporarily fixed base material 10. The temporarily fixed base material 10 has a temporarily fixed surface 11 having an adhesive force on one side in the thickness direction T. In this step, specifically, a plurality of electrodes 20 (electrodes for electronic components) for electronic components are arranged on the temporarily fixed surface 11 of the temporarily fixed base material 10.

[0024] The temporary fixing substrate 10 comprises, for example, a support substrate and an adhesive layer disposed on the support substrate to form a temporary fixing surface 11. Examples of the support substrate include a resin substrate and a metal substrate. Examples of the resin substrate include a flexible plastic film. Examples of the plastic film include polyethylene terephthalate film, polyethylene film, polypropylene film, and polyester film. Examples of the metal substrate material include stainless steel, aluminum, and nickel. The adhesive layer is formed from a pressure-sensitive adhesive. The adhesive layer may be an adhesive layer whose adhesive strength can be reduced afterward. Examples of such an adhesive layer include an adhesive layer whose adhesive strength can be reduced by curing with ultraviolet irradiation.

[0025] The electrode 20 is an electrode for an electronic component such as a semiconductor chip. In this embodiment, the electrode 20 has a first portion 21 and a second portion 22. In the planar direction perpendicular to the thickness direction T, the first portion 21 is relatively thin and the second portion 22 is relatively thick. The planar shapes of the first portion 21 and the second portion 22 may be circular or rectangular, such as a square. The width (maximum length in the planar direction) of the first portion 21 is, for example, 20 to 100 μm. The width (maximum length in the planar direction) of the second portion 22 is, for example, 40 to 300 μm, as long as it is greater than the width of the first portion 21. In this embodiment, the first portion 21 side of the electrode 20 is temporarily fixed to the temporary fixing surface 11. The height (length in the thickness direction T) of the electrode 20 placed on the temporary fixing surface 11 is, for example, 20 to 100 μm. In addition, multiple electrodes 20 are arranged on the temporary fixing surface 11 with spacing between them in the planar direction. The spacing between adjacent electrodes 20 is, for example, 100 to 500 μm. Multiple electrodes 20 are provided at positions corresponding to the type and number of electronic components to be mounted on the electrode-equipped cured resin sheet X (shown in Figure 1E) manufactured by this manufacturing method. Examples of materials for the electrodes 20 include copper, silver, nickel, and gold.

[0026] Next, in the bonding process, as shown in Figure 1B, the thermosetting resin sheet 30 is bonded to the temporary fixing substrate 10. The thermosetting resin sheet 30 used in this process has a first surface 31 and a second surface 32 opposite to the first surface 31, as shown in Figure 2, and extends in a direction perpendicular to the thickness direction T. The thermosetting resin sheet 30 contains a thermosetting resin and an inorganic filler, as will be described later. The thermosetting resin sheet 30 is in a semi-cured state (stage B).

[0027] In this process, specifically, a plurality of electrodes 20 on the temporary fixing surface 11 of the temporary fixing substrate 10 are embedded with the thermosetting resin sheet 30, and the first surface 31 of the thermosetting resin sheet 30 is bonded to the temporary fixing surface 11. A vacuum press can be used for bonding. Preferably, the thermosetting resin sheet 30 is softened by heating before bonding. The heating temperature (softening temperature) in this process is, for example, 40°C or higher, preferably 60°C or higher. This heating temperature is below the curing temperature of the thermosetting resin sheet 30, for example, less than 100°C, preferably 90°C or lower.

[0028] Next, in the curing process, as shown in Figure 1C, the thermosetting resin sheet 30 is heat-cured to form a cured resin sheet 30A. The heating temperature (curing temperature) is higher than the softening temperature described above, for example, 100°C or higher, preferably 120°C or higher. The heating temperature (curing temperature) is for example 200°C or lower, preferably 180°C or lower. The heating time is for example 10 minutes or more, preferably 30 minutes or more. The heating time is for example 180 minutes or less, preferably 120 minutes or less.

[0029] Next, in the peeling process, the temporary fixing substrate 10 is separated from the cured resin sheet 30A, as shown in Figure 1D. If the temporary fixing surface 11 of the temporary fixing substrate 10 is formed from an adhesive layer whose adhesive strength can be reduced by ultraviolet irradiation, the adhesive strength of the adhesive layer is reduced by ultraviolet irradiation before separating the temporary fixing substrate 10 from the cured resin sheet 30A. As a result, the first surface 31 of the cured resin sheet 30A and the end surface of the first portion 21 of the electrode 20 (the first electrode surface 20a, described later), which were in contact with the temporary fixing surface 11, are exposed.

[0030] Next, in the grinding process, as shown in Figure 1E, the second surface 32 of the cured resin sheet 30A (cured thermosetting resin sheet 30) is ground to expose the end face of the second portion 22 of the electrode 20 (the second electrode surface 20b described later) on the second surface 32 side. In this process, the electrode 20 may be ground together with the cured resin sheet 30A. For the grinding process, for example, a back grinding device equipped with a grinding wheel is used. The thickness of the cured resin sheet 30A after grinding is, for example, 80 μm or more, and for example, 500 μm or less. The ratio of the height of the electrode 20 after grinding to the height of the electrode 20 before grinding (length T in the thickness direction) is, for example, 0.8 to 1.

[0031] As described above, an electrode-equipped curable resin sheet X is manufactured. The electrode-equipped curable resin sheet X comprises a curable resin sheet 30A as a sheet-shaped curable resin portion and a plurality of electrodes 20 arranged within the curable resin sheet 30A. The curable resin sheet 30A has a first surface 31 and a second surface 32 opposite to the first surface 31. Each electrode 20 arranged and held within the curable resin sheet 30A has a first electrode surface 20a exposed to the first surface 31 side and a second electrode surface 20b exposed to the second surface 32 side. The plurality of electrodes 20 are provided at positions corresponding to the type and number of electronic components to be mounted on the electrode-equipped curable resin sheet X.

[0032] Figure 3 illustrates a method for manufacturing a semiconductor package, as an example of how to use the electrode-equipped curing resin sheet X.

[0033] First, as shown in Figure 3A, a semiconductor chip 50 is face-down mounted onto the second surface Xb of the electrode-equipped cured resin sheet X. In this embodiment, the semiconductor chip 50 is a semiconductor chip for wireless communication. The operating frequency of the semiconductor chip 50 is, for example, 0.01 to 100 GHz. The semiconductor chip 50 also has a main surface 51 and a side surface 52. The main surface 51 is provided with terminals (not shown) for external connection. In the face-down mounting process of this step, with the second surface Xb of the electrode-equipped cured resin sheet X and the main surface 51 of the semiconductor chip 50 in contact, the second electrode surface 20b of the electrode 20 and the terminals on the main surface 51 are joined one-to-one. Examples of joining methods include ultrasonic bonding and soldering.

[0034] Next, as shown in Figure 3B, a semi-cured encapsulating resin composition 60 is supplied onto the electrode-equipped curing resin sheet X so as to cover the semiconductor chip 50. The encapsulating resin composition 60 is, for example, a thermosetting resin composition containing a thermosetting resin.

[0035] Next, as shown in Figure 3C, the encapsulating resin composition 60 covering the semiconductor chip 50 is cured by heating to form a cured resin portion 60A around the semiconductor chip 50 on the electrode-equipped cured resin sheet X. The heating temperature is, for example, 100°C to 200°C.

[0036] Subsequently, for example, by blade dicing, the electrode-equipped cured resin sheet X and the cured resin portion 60A are cut along predetermined cutting lines to form individual semiconductor packages. In the semiconductor package thus obtained, the semiconductor chip 50 is sealed by the cured resin sheet 30A, which is the cured resin portion of the electrode-equipped cured resin sheet X, and the cured resin portion 60A formed from the sealing resin composition 60, in a state where it can be externally connected via the electrodes 20 of the electrode-equipped cured resin sheet X. Since such a semiconductor package is face-down mounted on the electrode-equipped cured resin sheet X with the semiconductor chip 50 in contact with the electrode-equipped cured resin sheet X, it is more suitable for thinning than conventional face-up type semiconductor packages and face-down type semiconductor packages. That is, the electrode-equipped cured resin sheet X obtained by the manufacturing method of the present invention described above with reference to Figure 1 is suitable for manufacturing thin semiconductor packages.

[0037] The thermosetting resin sheet 30 shown in Figure 2 is one embodiment of the thermosetting resin sheet of the present invention and is formed from a thermosetting composition. In this embodiment, the thermosetting composition includes a thermosetting resin and an inorganic filler. The thermosetting resin sheet 30 is in a semi-cured state (stage B).

[0038] Examples of thermosetting resins include epoxy resins, silicone resins, urethane resins, polyimide resins, urea resins, melamine resins, and unsaturated polyester resins. These thermosetting resins may be used individually or in combination of two or more types. The content of thermosetting resin in the thermosetting composition is preferably 3% by mass or more, more preferably 3.5% by mass or more. The content of thermosetting resin in the thermosetting composition is preferably 35% by mass or less, more preferably 30% by mass or less.

[0039] The thermosetting resin preferably includes an epoxy resin. Examples of epoxy resins include difunctional epoxy resins and polyfunctional epoxy resins with three or more functions. Examples of difunctional epoxy resins 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 polyfunctional epoxy resins with three or more functions include phenol novolac type epoxy resin, cresol novolac type epoxy resin, trishydroxyphenylmethane type epoxy resin, tetraphenyloleethane type epoxy resin, and dicyclopentadiene type epoxy resin. These epoxy resins may be used individually or in combination of two or more types. Preferably, a difunctional epoxy resin and / or the above-mentioned polyfunctional epoxy resin is used as the epoxy resin, and more preferably, bisphenol F type epoxy is used.

[0040] The epoxy equivalent of the epoxy resin is preferably 10 g / eq or more, more preferably 50 g / eq or more, and even more preferably 100 g / eq or more. The epoxy equivalent of the epoxy resin is preferably 500 g / eq or less, more preferably 450 g / eq or less, and even more preferably 400 g / eq or less. When the thermosetting resin contains multiple epoxy resins, the epoxy equivalent is the weighted average epoxy equivalent of the multiple epoxy resins.

[0041] When epoxy resin is used, the thermosetting resin preferably includes a phenolic resin as a curing agent for the epoxy resin. Such a configuration is suitable for the thermosetting resin sheet 30 to exhibit high heat resistance and high chemical resistance after curing, and is therefore suitable for forming a cured resin portion with excellent sealing reliability from the thermosetting resin sheet 30. Preferably, a novolac-type phenolic resin and / or a triphenylmethane-type epoxy resin are used as the phenolic resin. Examples of novolac-type phenolic resins include phenol novolac resin, phenol aralkyl resin, trishydroxyphenylmethane novolac resin, cresol novolac resin, tert-butylphenol novolac resin, and nonylphenol novolac resin. An example of a triphenylmethane-type epoxy resin is trishydroxyphenylmethane-type epoxy resin. These phenolic resins may be used alone or in combination of two or more types.

[0042] In the thermosetting composition, the amount of hydroxyl groups in the phenol resin per equivalent of epoxy groups in the epoxy resin is preferably 0.7 equivalents or more, more preferably 0.9 equivalents or more. In the thermosetting composition, the amount of hydroxyl groups in the phenol resin per equivalent of epoxy groups in the epoxy resin is preferably 1.5 equivalents or less, more preferably 1.2 equivalents or less. Furthermore, the amount of phenol resin blended per 100 parts by mass of epoxy resin is preferably 20 parts by mass or more, more preferably 30 parts by mass or more. The amount of phenol resin blended as a curing agent per 100 parts by mass of epoxy resin is preferably 80 parts by mass or less, more preferably 70 parts by mass or less.

[0043] Examples of inorganic fillers include inorganic particles having a solid structure (solid inorganic particles) and inorganic particles having a hollow structure (hollow inorganic particles).

[0044] Examples of materials for solid inorganic particles include silica, calcium oxide, magnesium oxide, titanium oxide, aluminum oxide, zirconium oxide, cesium oxide, aluminum hydroxide, magnesium hydroxide, calcium carbonate, magnesium carbonate, aluminum nitride, boron nitride, silicon nitride, and silicon carbide. Solid inorganic particles may be used alone or in combination of two or more types. As the solid inorganic particles, solid silica filler is preferably used.

[0045] The average particle size of the solid inorganic particles is preferably 0.1 μm or more, more preferably 0.5 μm or more. The average particle size is preferably 20 μm or less, more preferably 10 μm or less. These configurations are preferable in the thermosetting resin sheet 30 of the bonding process described above (Figure 1B) to ensure good viscosity and electrode shape conformability. The average particle size of the solid inorganic particles is the median diameter in the volume-based particle size distribution (the particle size at which the volume cumulative frequency reaches 50% from the smallest diameter side), and can be 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).

[0046] The content of solid inorganic particles in the thermosetting composition is preferably 60% by mass or more, more preferably 70% by mass or more, and even more preferably 80% by mass or more. Such a configuration is suitable for suppressing expansion and contraction due to temperature changes in the thermosetting resin sheet 30. The content of solid inorganic particles is preferably 90% by mass or less, more preferably 85% by mass or less. Such a configuration is suitable for ensuring fluidity in the above-described bonding process (Figure 1B) in the thermosetting resin sheet 30.

[0047] Layered silicate compounds can also be used as materials for solid inorganic particles. Layered silicate compound particles in a thermosetting composition are components that thicken the thermosetting composition while exhibiting thixotropic properties. Examples of layered silicate compounds include smectite, kaolinite, halloysite, talc, and mica. Examples of smectite include montmorillonite, bydelite, nontronite, saponite, hectorite, soaconite, and stevensite. As for layered silicate compounds, smectite is preferably used, and montmorillonite is more preferably used, because it is easily mixed with thermosetting resins.

[0048] The layered silicate compound may be an unmodified compound with an unmodified surface, or a modified compound 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 organically modified smectite with a surface modified by an organic component is used, and even more preferably, an organically modified bentonite with a surface modified by an organic component is used.

[0049] Examples of organic components 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 phosphoniums 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 types. Ammonium is preferably used as the organic cation, and dimethyldistearylammonium is more preferably used.

[0050] Preferably, an organically modified smectite with an ammonium-modified surface is used as the organically modified layered silicate compound, and more preferably, an organically modified bentonite with a dimethyldistearylammonium-modified surface is used.

[0051] The average particle size of the layered silicate compound is preferably 1 nm or more, more preferably 5 nm or more, and even 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, and even more preferably 10 μm or less.

[0052] The content of the layered silicate compound in the thermosetting composition is preferably 1% by mass or more, more preferably 1.2% by mass or more, and even more preferably 1.4% by mass or more. Such a configuration is suitable for increasing the viscosity of the thermosetting composition while exhibiting thixotropic properties in the thermosetting composition, where the viscosity becomes lower when pressure is applied compared to when no pressure is applied. Such thixotropic properties are preferable for ensuring good electrode shape conformability in the thermosetting resin sheet 30 of the bonding process described above (Figure 1B). From the viewpoint of avoiding excessive viscosity increase of the thermosetting composition, the content of the layered silicate compound in the thermosetting composition is preferably 6% by mass or less, more preferably 5% by mass or less, and even more preferably 4% by mass or less.

[0053] Preferably, hollow ceramic fillers are used as hollow inorganic particles. Hollow ceramic fillers are hollow fillers made of fired inorganic material. Examples of materials for hollow ceramic fillers include oxide ceramics, nitride ceramics, carbide ceramics, and glass ceramics. Examples of oxide ceramics include titanium oxide, aluminum oxide, zirconium oxide, and cesium oxide. Examples of nitride ceramics include silicon nitride, titanium nitride, and aluminum nitride. Examples of carbide ceramics include silicon carbide, titanium carbide, and tungsten carbide. Examples of glass ceramics include aluminoborosilicate glass, lead borosilicate glass, and zinc borosilicate glass. Preferably, glass ceramics are used as hollow ceramic fillers, and more preferably, aluminoborosilicate glass is used.

[0054] The average particle size of the hollow ceramic filler is preferably 0.1 μm or more, more preferably 0.5 μm or more. The average particle size is preferably 30 μm or less, more preferably 20 μm or less, and even more preferably 10 μm or less.

[0055] The particle density of the hollow ceramic filler is preferably 0.3 g / cm³.3 More preferably 0.5 g / cm³ 3 The above applies, and preferably 0.9 g / cm³. 3 More preferably, 0.8 g / cm³ 3 The following configuration is preferable for reducing the dielectric constant of the cured resin sheet 30A (cured resin portion) formed from the thermosetting resin sheet 30, and therefore is preferable for reducing the transmission loss of high-frequency signals passing through the cured resin portion in the semiconductor package described above.

[0056] From the viewpoint of reducing transmission loss as described above, the content of hollow ceramic fillers in the thermosetting composition is preferably 15% by volume or more, more preferably 50% by volume or more, even more preferably 60% by volume or more, still more preferably 65% ​​by volume or more, especially preferably 70% by volume or more, and particularly preferably 75% by volume or more. From the viewpoint of reducing transmission loss as described above, the content of hollow ceramic fillers in the inorganic filler is preferably 20% by volume or more, more preferably 50% by volume or more, still more preferably 80% by volume or more, and particularly preferably 100% by volume. Furthermore, the content of hollow ceramic fillers in the thermosetting composition is preferably 85% by volume or less, more preferably 82% by volume or less, and still more preferably 80% by volume or less. The content of hollow ceramic fillers in the thermosetting composition is preferably 90% by mass or less, more preferably 85% by mass or less. Such a configuration is suitable for ensuring fluidity in the thermosetting resin sheet 30 during the bonding process (Figure 1B) described above.

[0057] The inorganic filler content in the thermosetting composition is preferably 60% by mass or more, more preferably 70% by mass or more, and even more preferably 80% by mass or more. Such a configuration is suitable for suppressing expansion and contraction due to temperature changes in the thermosetting resin sheet 30. The inorganic filler content is preferably 90% by mass or less, more preferably 85% by mass or less. Such a configuration is suitable for ensuring fluidity in the above-described bonding process (Figure 1B) in the thermosetting resin sheet 30.

[0058] The thermosetting composition may contain other components. Examples of other components include curing accelerators, thermoplastic resins, pigments, and silane coupling agents.

[0059] A curing accelerator is a catalyst (thermosetting catalyst) that accelerates the curing of a thermosetting resin by heating. Examples of curing accelerators include imidazole compounds and organophosphorus compounds. Examples of imidazole compounds include 2-phenyl-4,5-dihydroxymethylimidazole and 2-phenyl-4-methyl-5-hydroxymethylimidazole. Examples of organophosphorus compounds include triphenylphosphine, tricyclohexylphosphine, tributylphosphine, and methyldiphenylphosphine. Preferably, an imidazole compound is used as the curing accelerator, and more preferably, 2-phenyl-4,5-dihydroxymethylimidazole is used. The amount of curing accelerator blended per 100 parts by mass of thermosetting resin is, for example, 0.05 parts by mass or more, and also, for example, 5 parts by mass or less.

[0060] Examples of thermoplastic resins include acrylic resins, 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), polyamide-imide resin, fluororesin, and styrene-isobutylene-styrene block copolymer. These thermoplastic resins may be used individually or in combination of two or more types.

[0061] As the thermoplastic resin, acrylic resin is preferably used from the viewpoint of ensuring compatibility between the thermosetting resin and the thermoplastic resin. Examples of acrylic resins include (meth)acrylic polymers as polymers of monomer components containing an alkyl (meth)acrylate ester having a linear or branched alkyl group and other monomers (copolymerizable monomers).

[0062] The glass transition temperature (Tg) of thermoplastic resins is preferably -70°C or higher. The glass transition temperature is preferably 0°C or lower, more preferably -5°C or lower. For the glass transition temperature (Tg) of polymers, the theoretical glass transition temperature (Tg) can be obtained based on Fox's equation below. Fox's equation is a relationship between the glass transition temperature Tg of a polymer and the glass transition temperature Tgi of the homopolymer of the monomers constituting the polymer. In Fox's equation below, 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 homopolymers, 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 Coatings" (by Kyozo Kitaoka, Polymer Publishing Association, 1995) list the glass transition temperatures of various homopolymers. On the other hand, the glass transition temperature of the monomer homopolymer can also be determined by the method specifically described in Japanese Patent Publication No. 2007-51271.

[0063] Fox's formula 1 / (273+Tg)=Σ[Wi / (273+Tgi)]

[0064] The weight-average molecular weight of the thermoplastic resin is preferably 100,000 or more, and more preferably 300,000 or more. The weight-average molecular weight of the thermoplastic resin is preferably 2,000,000 or less, and 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 value equivalent to standard polystyrene.

[0065] The content of thermoplastic resin in the thermosetting composition is preferably 1% by mass or more, more preferably 2% by mass or more. The content is preferably 80% by mass or less, more preferably 60% by mass or less.

[0066] Examples of pigments include black pigments such as carbon black. The particle size of the pigment is, for example, 0.001 μm or larger, and for example, 1 μm or smaller. The particle size of the pigment is the arithmetic mean diameter obtained by observing the pigment with an electron microscope. The pigment content in the thermosetting composition is, for example, 0.1% by mass or larger, and for example, 2% by mass or smaller.

[0067] Examples of silane coupling agents include silane coupling agents containing epoxy groups. Examples of epoxy group-containing silane coupling agents include 3-glycidoxydialkyldialkoxysilane and 3-glycidoxyalkyltrialkoxysilane. Examples of 3-glycidoxydialkyldialkoxysilane include 3-glycidoxypropylmethyldimethoxysilane and 3-glycidoxypropylmethyldiethoxysilane. Examples of 3-glycidoxyalkyltrialkoxysilane include 3-glycidoxypropyltrimethoxysilane and 3-glycidoxypropyltriethoxysilane. Preferably, 3-glycidoxyalkyltrialkoxysilane is used as the silane coupling agent, and more preferably 3-glycidoxypropyltrimethoxysilane is used. The content of the silane coupling agent in the thermosetting composition is preferably 0.1% by mass or more, more preferably 1% by mass or more. The content is preferably 10% by mass or less, and more preferably 5% by mass or less.

[0068] The thermosetting resin sheet 30 can be manufactured, for example, as follows.

[0069] First, a thermosetting composition varnish is prepared by kneading the above-mentioned components with a solvent. Examples of solvents include methyl ethyl ketone, ethyl acetate, and toluene. Next, the varnish is applied to a substrate such as a release film to form a coating, and then the coating is dried by heating. This allows a composition film of a predetermined thickness in a semi-cured state to be formed as a thermosetting resin sheet 30 (in Figure 2, the thermosetting resin sheet 30 is placed on the release film L shown by the dashed line). Examples of release films include flexible plastic films. Examples of such plastic films include polyethylene terephthalate film, polyethylene film, polypropylene film, and polyester film. The thickness of the release film is, for example, 3 μm or more, and for example, 200 μm or less. The surface of the release film is preferably treated for mold release.

[0070] When manufacturing a thick thermosetting resin sheet 30, multiple composition films may be bonded together under heating conditions to form a single unit. The heating temperature is, for example, 70°C to 90°C.

[0071] As described above, a thermosetting resin sheet 30 of a predetermined thickness can be produced. The thickness of the thermosetting resin sheet 30 is, for example, 10 μm or more, preferably 25 μm or more, and more preferably 30 μm or more. The thickness of the thermosetting resin sheet 30 is, for example, 3000 μm or less, preferably 1000 μm or less, more preferably 500 μm or less, even more preferably 300 μm or less, and particularly preferably 100 μm or less.

[0072] The thermosetting resin sheet 30, after being cured by heating at 150°C for 1 hour, has a tensile storage modulus of 2 GPa to 18 GPa at 25°C. This configuration is suitable for separating the temporary fixing substrate 10 from the cured resin sheet 30A while suppressing plastic deformation and cracking in the cured resin sheet 30A during the peeling process described above (Figure 1D). Such a thermosetting resin sheet 30 is suitable for use in the manufacture of the electrode-equipped cured resin sheet X described above. From the viewpoint of suppressing plastic deformation and cracking, the storage modulus of the thermosetting resin sheet 30 is preferably 5 GPa or more, more preferably 7 GPa or more, and also preferably 16 GPa or less, more preferably 12 GPa or less. The tensile storage modulus can be measured by the method described later with respect to the examples.

[0073] The thermosetting resin sheet 30 has a viscosity of 3 kPa·s to 100 kPa·s at 90°C. This configuration is suitable for embedding the electrode 20 with the thermosetting resin sheet 30 while suppressing the formation of a gap between the thermosetting resin sheet 30 and the electrode 20 at a temperature of 90°C or near 90°C during the peeling process described above (Figure 1B). From the viewpoint of such embedding properties, the viscosity of the thermosetting resin sheet 30 at 90°C is preferably 5 kPa·s or more, more preferably 6 kPa·s or more, and also 90 kPa·s or less, and 80 kPa·s or less. The viscosity at 90°C can be determined by the measurement method described later with respect to the examples.

[0074] The thermosetting resin sheet 30 has a mass W1 after a heat treatment at 150°C for 1 hour, followed by a first standing period of 1 hour at 25°C and 40% relative humidity. The thermosetting resin sheet 30 has a mass W2 after a second standing period of 168 hours at 85°C and 85% relative humidity following the first standing period. The thermosetting resin sheet 30 has a moisture absorption rate expressed as [(W2-W1) / W1]×100, preferably 0.3% by mass or less, more preferably 0.2% by mass or less. Such a configuration is preferable for ensuring the sealing reliability of the cured resin portion formed from the thermosetting resin sheet 30.

[0075] The thermosetting resin sheet 30 is cured by heating at 150°C for 1 hour, and then the relative permittivity at 10 GHz is preferably 4.2 or less, more preferably 4.0 or less, and even more preferably 3.0 or less. Such a configuration is preferable for reducing the transmission loss of high-frequency signals passing through the cured resin portion formed from the thermosetting resin sheet 30. The relative permittivity is, for example, 1 or more. The relative permittivity can be measured by the method described later with respect to the examples. [Examples]

[0076] The present invention will be described in more detail below with reference to examples. The present invention is not limited to these examples. Furthermore, specific numerical values ​​such as formulation amounts (content), physical properties, and parameters used in the following description can be replaced with the corresponding formulation amounts (content), physical properties, and parameters described in the "Modes for Carrying Out the Invention" above, which are defined as upper limits (numbers defined as "less than or equal to" or "less than") or lower limits (numbers defined as "greater than or equal to" or "greater than").

[0077] [Examples 1-4 and Comparative Examples 1,2] The components were mixed according to the formulation shown in Table 1 to prepare the composition varnish (in Table 1, the units of each numerical value representing the composition are relative "parts by mass"). Next, the varnish was applied to a polyethylene terephthalate film (PET film) whose surface had been treated with a silicone release agent to form a coating film. Next, this coating film was heated and dried at 120°C for 2 minutes to create a composition film with a thickness of 65 μm on the PET film (the formed composition film is in the B stage). Next, four composition films were bonded together at 80°C to create a thermosetting resin sheet with a thickness of 260 μm (the formed thermosetting resin sheet is in the B stage).

[0078] <Viscosity of thermosetting resin sheets> The viscosity of each thermosetting resin sheet from Examples 1-4 and Comparative Examples 1 and 2 was measured at 90°C. For this measurement, a rheometer (product name "HAAKE MARS III," manufactured by Thermo Fisher Scientific) was used. A sample taken from the thermosetting resin sheet was placed between a heating plate and a parallel plate (8 mm in diameter) positioned parallel to the heating plate, with a gap of 1 mm between the plates. The viscosity was then measured under the following conditions: frequency 1 Hz, strain value 0.005%, measurement temperature range 50°C to 90°C, and heating rate 30°C / min. Table 1 shows the viscosity (kPa·s) at 90°C.

[0079] <Tensile storage modulus> The tensile storage modulus after curing was measured for each thermosetting resin sheet in Examples 1-4 and Comparative Examples 1 and 2 as follows. First, the thermosetting resin sheet was cured by heating at 150°C for 1 hour. Next, a sample piece (3 mm wide × 40 mm long × 260 μm thick) for measurement was cut from the cured thermosetting resin sheet. Then, the tensile storage modulus was measured in the temperature range of -10°C to 260°C using a dynamic viscoelasticity analyzer (product name "RSA-G2", manufactured by TA Instruments). In this measurement, the initial chuck distance of the sample piece holding chuck was set to 22.5 mm, the measurement mode was set to tensile mode, the heating rate was set to 10°C / min, the frequency was set to 1 Hz, and the dynamic strain was set to 0.05%. The tensile storage modulus (GPa) at 25°C is shown in Table 1.

[0080] <Moisture absorption rate> The moisture absorption rate of each thermosetting resin sheet in Examples 1-4 and Comparative Examples 1 and 2 was investigated as follows. First, the thermosetting resin sheet was cured by heating at 150°C for 1 hour. Next, a sample piece (50 mm wide × 50 mm long × 260 μm thick) for measurement was cut from the cured thermosetting resin sheet. Next, the sample piece was left to stand for 1 hour at 25°C and 40% relative humidity. Next, the mass of the sample piece (mass W1) was measured. Next, the sample piece was left to stand for 168 hours at 85°C and 85% relative humidity. Next, the mass of the sample piece (mass W2) was measured. Then, the moisture absorption rate expressed by the following formula was calculated. The values ​​(%) are shown in Table 1.

[0081] Moisture absorption rate (%)=[(W2-W1) / W1]×100

[0082] <Relative permittivity> The dielectric constant at 10 GHz after curing was measured for each thermosetting resin sheet in Examples 1-4 and Comparative Examples 1 and 2 as follows. First, the thermosetting resin sheet was cured by heating at 150°C for 1 hour. Next, a sample piece (30 mm wide × 30 mm long × 260 μm thick) was cut from the cured thermosetting resin sheet for measurement. Then, the dielectric constant at 10 GHz of the sample piece was measured using a PNA network analyzer (manufactured by Agilent Technologies) and an SPDR (Split post dielectric resonator) resonator. The measurement results are shown in Table 1.

[0083] <Evaluation of curvature> The degree of warping after curing was investigated for each thermosetting resin sheet in Examples 1-4 and Comparative Examples 1 and 2. Specifically, a laminated sample comprising a 90mm x 90mm x 150μm thick 42 alloy plate and a thermosetting resin sheet bonded to the entire thickness of one side of the 42 alloy plate was heated at 150°C for 1 hour, and then left to stand at 25°C for 1 hour. The maximum distance between the mounting surface on which the laminated sample was placed with the 42 alloy plate facing downwards, and the edge of the laminated sample was measured as the amount of warping (mm). The results are shown in Table 1.

[0084] <Deformation resistance and crack resistance> For each thermosetting resin sheet in Examples 1-4 and Comparative Examples 1 and 2, the presence or absence of deformation and cracking during the process of manufacturing the electrode-attached curing resin sheet was investigated. Specifically, first, a thermosetting resin sheet was bonded to the temporary fixing surface of a temporary fixing substrate on which multiple electrodes were arranged, while embedding the multiple electrodes with the thermosetting resin sheet (Figure 1B). The temporary fixing substrate was a SUS substrate with a thickness of 100 μm. The electrodes were made of copper and had a cylindrical first part (height 30 μm) and a larger diameter cylindrical second part (height 20 μm). The distance between adjacent electrodes was set to approximately 100-150 μm. A vacuum press (product name "Vacuum Pressurizing Device VS008-1515", manufactured by Mikado Technos Co., Ltd.) was used for bonding. For bonding, a bonded body was obtained by sealing under conditions of a temperature of 90°C, a press pressure of 0.1 MPa, and a press time of 40 seconds, with a vacuum of 2000 Pa or less. Next, the bonded body (temporary fixing substrate, electrode, thermosetting resin sheet) was heated at 150°C for 1 hour (Figure 1C). This cured the thermosetting resin sheet, forming a cured resin sheet that would hold the electrode. Next, the bonded body was left to stand at 25°C for 1 hour. Then, the temporary fixing substrate was peeled from the electrode-attached cured resin sheet of the bonded body (Figure 1D). For peeling, the peeling angle was set to 90° to 145°, and the peeling speed was set to approximately 300 mm / second. After that, the presence or absence of deformation and cracks was checked by visual inspection of the electrode-attached cured resin sheet. The deformation and crack resistance of the cured thermosetting resin sheet was evaluated as "good" if neither deformation nor cracking occurred, and as "poor" if deformation and / or cracking occurred. The results are shown in Table 1.

[0085] <Implantability of electrodes> For each thermosetting resin sheet in Examples 1-4 and Comparative Examples 1 and 2, the electrode embedding properties during the process of manufacturing the electrode-attached cured resin sheet were investigated. Specifically, first, the electrode-attached cured resin sheets used for the deformation resistance and cracking resistance evaluation described above were cut in the thickness direction, and the cross-section of the predetermined electrode and the cured resin portion around the electrode was cut out. Next, the cross-section was observed using an optical microscope. The electrode embedding properties in the cured thermosetting resin sheet were evaluated as "good" if no void was formed between the electrode and the cured resin portion, and as "poor" if a void was formed. The results are shown in Table 1.

[0086] [Table 1]

[0087] The components used in the examples and comparative examples are as follows: Epoxy resin 1: "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) Second epoxy resin: "EPPN-501HY" manufactured by Nippon Kayaku Co., Ltd. (polyfunctional epoxy resin, epoxy equivalent 169 g / eq, solid at room temperature, softening point 60°C) First phenolic resin: "LVR-8210DL" manufactured by Gun-ei Chemical Co., Ltd. (novolac-type phenolic resin, latent curing agent, hydroxyl group equivalent 104 g / eq, solid at room temperature, softening point 60°C) Second phenolic resin: "TPM-100" manufactured by Gun-ei Chemical Co., Ltd. (triphenylmethane type phenolic resin, latent curing agent, hydroxyl group equivalent 98 g / eq, solid at room temperature, softening point 108.2°C) Acrylic resin (acrylic polymer): "HME-2006M" manufactured by Negami Kogyo Co., Ltd. (carboxyl group-containing acrylic resin, acid value 32 mg KOH / g, weight-average molecular weight 1.29 million, glass transition temperature (Tg) -13.9℃, methyl ethyl ketone solution with solid content concentration of 20% by mass) Silica filler #1: "FB-8SM" manufactured by Denka Co., Ltd. (spherical silica particles, average particle size 7.0 μm, no surface treatment) Second silica filler: Admatex's "SC220G-SMJ" (spherical silica particles, average particle size 0.5 μm) surface-treated with 3-methacryloxypropyltrimethoxysilane (Shin-Etsu Chemical's "KBM-503") (the silane coupling agent used for surface treatment was 1 part by mass per 100 parts by mass of silica particles). Hollow ceramic filler: "Cellspheres" manufactured by Taiheiyo Cement Corporation (aluminoborosilicate glass, hollow spherical particles, average particle diameter 4.0 μm, particle density 0.6 g / cm³) 3 ) Layered silicate compound: Esben NX from Hojun (organic bentonite with a surface modified with dimethyldistearylammonium) Curing accelerator: "2PHZ-PW" (2-phenyl-4,5-dihydroxymethylimidazole) manufactured by Shikoku Chemicals Co., Ltd. Silane coupling agent: "KBM-403" (3-glycidoxypropyltrimethoxysilane) manufactured by Shin-Etsu Chemical Co., Ltd. Pigment: Mitsubishi Chemical's "Carbon Black #20" (average particle size 50nm) Solvent: Methyl ethyl ketone (MEK) The present invention relates to a method for manufacturing a curable resin sheet with electrodes, a curable resin sheet with electrodes, and a thermosetting resin sheet.

[0088] The embodiments described above are illustrative of the present invention and should not be interpreted as limiting the invention. Modifications of the present invention that are obvious to those skilled in the art are included in the claims below. [Industrial applicability]

[0089] The present invention provides a method for manufacturing an electrode-equipped curable resin sheet, and the electrode-equipped curable resin sheet and thermosetting resin sheet can be used in the manufacture of electronic component packages such as semiconductor packages. [Explanation of Symbols]

[0090] X electrode-equipped curing resin sheet T (thickness direction) 10 Temporary fixing base material 11 Temporary fixing surface 20 electrodes (electrodes for electronic components) 20a 1st electrode surface 20b 2nd electrode surface 21 Part 1 22 Part 2 30 Thermosetting resin sheets 31 Page 1 32 Side 2 30A Cured Resin Sheet

Claims

1. A first step involves arranging a plurality of electrodes for electronic components on the temporary fixing surface of a temporary fixing substrate having a temporary fixing surface, A second step involves bonding the first surface of a thermosetting resin sheet, which has a first surface and a second surface opposite to the first surface, to the temporary fixing surface of the temporary fixing substrate while embedding the plurality of electrodes for electronic components with the thermosetting resin sheet. A third step involves heat-curing the aforementioned thermosetting resin sheet to form a cured resin sheet, A fourth step involves separating the temporary fixing substrate from the cured resin sheet, A method for manufacturing an electrode-equipped cured resin sheet, comprising a fifth step of grinding the second surface of the cured resin sheet to expose the electrode for the electronic component on the second surface.

2. The method for manufacturing an electrode-equipped cured resin sheet according to claim 1, wherein the thermosetting resin sheet has a tensile storage modulus of 2 GPa or more and 18 GPa or less at 25°C after curing.

3. A cured resin sheet having a first surface and a second surface opposite to the first surface, The set comprises a plurality of electrodes for electronic components arranged within the cured resin sheet, each having a first electrode surface exposed to the first surface and a second electrode surface exposed to the second surface, The aforementioned cured resin sheet is formed from a thermosetting resin sheet. The thermosetting resin sheet is a curing resin sheet with electrodes having a relative permittivity of 4.2 or less at 10 GHz.

4. A thermosetting resin sheet for manufacturing electrode-equipped curing resin sheets, After curing, it has a tensile storage modulus of 2 GPa or more and 18 GPa or less at 25°C. A thermosetting resin sheet having a dielectric constant of 4.2 or less at 10 GHz.

5. A thermosetting resin sheet for manufacturing electrode-equipped curing resin sheets, After curing, it has a tensile storage modulus of 2 GPa or more and 18 GPa or less at 25°C. A thermosetting resin sheet having a viscosity of 3 kPa·s to 100 kPa·s at 90°C.

6. A thermosetting resin sheet for manufacturing electrode-equipped curing resin sheets, After curing, it has a tensile storage modulus of 2 GPa or more and 18 GPa or less at 25°C. After a heat treatment at 150°C for 1 hour, and a subsequent first standing period of 1 hour at 25°C and 40% relative humidity, the material having mass W1 is obtained. After the first settling, a second settling for 168 hours under conditions of 85°C and 85% relative humidity, having a mass W2, A thermosetting resin sheet having a moisture absorption rate of 0.3% by mass or less, expressed as [(W2 - W1) / W1] × 100.

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