JP7844933B2 - curable composition - Google Patents

Description

This invention relates to a curable composition. Furthermore, it relates to a sheet containing the curable composition, a circuit board, a semiconductor chip package, and an electronic component using the curable composition.

In recent years, as electronic devices have become smaller and more sophisticated, the mounting density of semiconductor elements on printed circuit boards has tended to increase. Coupled with the increasing sophistication of the semiconductor elements being mounted, there is a growing demand for technologies that efficiently dissipate the heat generated by these semiconductor elements.

For example, Patent Document 1 discloses a method of dissipating heat by using an insulating layer, formed by curing a resin composition containing a resin and alumina satisfying predetermined requirements, on a circuit board.

Japanese Patent Publication No. 2012-77123

Insulating layers require not only high thermal conductivity but also low elastic modulus for impact resistance. However, conventional technologies have not always been able to fully achieve insulating layers with both high thermal conductivity and low elastic modulus.

The present invention has been made in view of the above, and aims to provide a curable composition that can produce a cured product with high thermal conductivity and low elastic modulus; and a sheet containing the curable composition, a circuit board, a semiconductor chip package, and an electronic component using the curable composition.

To achieve the objectives of this invention, the inventors conducted diligent research and, as a result, discovered that by incorporating (A) a thermally conductive filler, (B) a silsesquioxane compound, and (C) a liquid polythiol, a cured product with high thermal conductivity and low elastic modulus can be obtained, thus completing the present invention.

In other words, the present invention includes the following:
[1] (A) Thermally conductive filler,
A curable composition containing (B) a silsesquioxane compound and (C) a liquid polythiol compound,
If component (B) does not contain an epoxy group-containing silsesquioxane compound having an epoxy group, the curable composition further contains (D) an epoxy resin.
(B) If component contains an epoxy group-containing silsesquioxane compound, the curable composition is a curable composition that contains (D) an epoxy resin or does not contain it.
[2] The curable composition according to [1], wherein the content of component (A) is 20% by mass or more and 80% by mass or less, when the nonvolatile components in the curable composition are taken as 100% by mass.
[3] The curable composition according to [1] or [2], wherein the curable composition contains an epoxy group-containing silsesquioxane compound as component (B) and further contains an epoxy resin (D), and the content of component (B) is 5% by mass or more and 65% by mass or less, when the nonvolatile components in the curable composition are taken as 100% by mass.
[4] The curable composition according to [1] or [2], wherein the curable composition contains an epoxy group-containing silsesquioxane compound as component (B) and does not contain an epoxy resin (D), and the content of component (B) is 10% by mass or more and 65% by mass or less, when the nonvolatile components in the curable composition are taken as 100% by mass.
[5] The curable composition according to any one of [1] to [4], wherein the content of component (C) is 5% by mass or more and 30% by mass or less, when the nonvolatile components in the curable composition are taken as 100% by mass.
[6] The curable composition according to any one of [1] to [5], wherein component (C) contains two or more thiol groups in one molecule.
[7] A sheet containing a curable composition, comprising a support and a curable composition layer provided on the support containing the curable composition described in any of [1] to [6].
[8] A circuit board comprising an insulating layer formed of a cured product of any of the curable compositions described in [1] to [6].
[9] A semiconductor chip package comprising a cured product of any of the curable compositions described in [1] to [6].
[10] An electronic component having an electronic component, a cured product of any of the curable compositions described in [1] to [6] provided on the electronic component, and a heat dissipation member mounted on the cured product.

According to the present invention, a curable composition can be obtained that yields a cured product with high thermal conductivity and low elastic modulus; and a sheet containing the curable composition, a circuit board, a semiconductor chip package, and an electronic component using the curable composition can be provided.

The present invention will be described in detail below with reference to its preferred embodiments. However, the present invention is not limited to the embodiments and examples described below, and can be modified and implemented as appropriate without departing from the scope of the claims and equivalents of the present invention. In the present invention, unless otherwise specified, the content of each component in the curable composition is the value when the non-volatile component in the curable composition is taken as 100% by mass.

[Curable composition]
The curable composition contains (A) a thermally conductive filler, (B) a silsesquioxane compound, and (C) a liquid polythiol compound, wherein component (B) does not contain an epoxy group-containing silsesquioxane compound having an epoxy group, and further contains (D) an epoxy resin, and if component (B) contains an epoxy group-containing silsesquioxane compound, it may or may not contain (D) an epoxy resin. By containing these components, the curable composition can increase the thermal conductivity of its cured product and decrease its elastic modulus.

The curable composition may, in addition to components (A) to (D), optionally further contain (E) a curing accelerator and (F) any optional additives. The components included in the curable composition are described in detail below.

<(A) Thermally conductive filler>
The curable composition contains (A) a thermally conductive filler as component (A). By including component (A) in the curable composition, a cured product (insulating layer) with high thermal conductivity can be obtained.

(A) The thermal conductivity of the thermally conductive filler is preferably 20 W/m·K or higher, more preferably 30 W/m·K or higher, even more preferably 50 W/m·K or higher, and 100 W/m·K or higher, from the viewpoint of obtaining a cured product with high thermal conductivity. The upper limit is not particularly limited, but it can be 1000 W/m·K or lower, etc.

The material of component (A) is not particularly limited as long as its thermal conductivity is within the above range. Examples of materials for component (A) include silicon carbide, boron nitride, aluminum nitride, and aluminum oxide (alumina). Component (A) may be used alone or in combination of two or more. Furthermore, two or more identical materials may be used in combination. In particular, from the viewpoint of obtaining a cured product with high thermal conductivity, component (A) preferably contains one or more selected from silicon carbide, boron nitride, aluminum nitride, and aluminum oxide, and more preferably contains silicon carbide.

The average particle size of component (A) is preferably 50 μm or less, more preferably 45 μm or less, even more preferably 40 μm or less, preferably 1 μm or more, more preferably 5 μm or more, even more preferably 10 μm or more, 20 μm or more, or 30 μm or more, from the viewpoint of obtaining an insulating layer with excellent thermal conductivity and improving filling properties.

The average particle size of component (A) can be measured by a laser diffraction/scattering method based on Mie scattering theory. Specifically, a volume-based particle size distribution of the thermal conductive filler is created using a laser diffraction/scattering particle size distribution analyzer, and the median diameter is used as the average particle size for measurement. A sample of component (A) dispersed in water using ultrasound is preferably used. Suitable laser diffraction/scattering particle size distribution analyzers include the LA-500 from Horiba, Ltd. and the SALD2200 from Shimadzu Corporation.

(A) The specific surface area of component (A) is preferably 0.01 ^m² /g or more, more preferably 0.025 ^m² /g or more, and even more preferably 0.05 ^m² /g or more, from the viewpoint of obtaining a cured product with excellent thermal conductivity. The upper limit is preferably 30 ^m² /g or less, more preferably 25 ^m² /g or less, and even more preferably 20 ^m² /g or less. The specific surface area of component (A) can be measured by the nitrogen BET method. Specifically, it can be measured using an automatic specific surface area measuring device, and as an automatic specific surface area measuring device, the "Macsorb HM-1210" manufactured by Mountec Co., Ltd. can be used.

(A) Component may be a commercially available product. Examples of commercially available products include MOMENTIVE's "PT-110A," "PT-120," "PT-350," "PTX-25," and "PTX-60," MARUWA's "ANF-S-30," "ANF-S-50," "ANF-A-01-F," and "ANF-A-05-F," and Denka's "DAW-05" and "DAW-20."

(A) Component may be treated with one or more surface treatment agents, such as aminosilane coupling agents, epoxysilane coupling agents, mercaptosilane coupling agents, silane coupling agents, alkoxysilane compounds, organosilazane compounds, or titanate coupling agents, from the viewpoint of improving moisture resistance and dispersibility. Examples of commercially available surface treatment agents include Shin-Etsu Chemical Co., Ltd.'s "KBM403" (3-glycidoxypropyltrimethoxysilane), Shin-Etsu Chemical Co., Ltd.'s "KBM803" (3-mercaptopropyltrimethoxysilane), Shin-Etsu Chemical Co., Ltd.'s "KBE903" (3-aminopropyltriethoxysilane), Shin-Etsu Chemical Co., Ltd.'s "KBM573" (N-phenyl-3-aminopropyltrimethoxysilane), Shin-Etsu Chemical Co., Ltd.'s "KBM5783" (N-phenyl-3-aminooctyltrimethoxysilane), Shin-Etsu Chemical Co., Ltd.'s "SZ-31" (hexamethyldisilazane), Shin-Etsu Chemical Co., Ltd.'s "KBM103" (phenyltrimethoxysilane), and Shin-Etsu Chemical Co., Ltd.'s "KBM-4803" (long-chain epoxy type silane coupling agent).

From the viewpoint of improving the dispersibility of component (A), the degree of surface treatment with the surface treatment agent is preferably 0.2 to 5 parts by mass of the surface treatment agent per 100 parts by mass of component (A), preferably 0.2 to 3 parts by mass, and preferably 0.3 to 2 parts by mass.

The degree of surface treatment by the surface treatment agent can be evaluated by the amount of carbon per unit surface area of component (A). From the viewpoint of improving the dispersibility of component (A), the amount of carbon per unit surface area of component (A) is preferably 0.02 mg/ ^m² or more, more preferably 0.1 mg/ ^m² or more, and even more preferably 0.2 mg/ ^m² or more. On the other hand, from the viewpoint of suppressing the increase in melt viscosity, it is preferably 1 mg/ ^m² or less, more preferably 0.8 mg/ ^m² or less, and even more preferably 0.5 mg/ ^m² or less.

The amount of carbon per unit surface area of component (A) can be measured after cleaning component (A) with a solvent (e.g., methyl ethyl ketone (MEK)) following surface treatment. Specifically, a sufficient amount of MEK is added to component (A) that has been surface-treated with a surface treatment agent, and ultrasonic cleaning is performed at 25°C for 5 minutes. After removing the supernatant and drying the solids, the amount of carbon per unit surface area of component (A) can be measured using a carbon analyzer. A carbon analyzer such as the EMIA-320V manufactured by Horiba, Ltd. can be used.

From the viewpoint of obtaining a cured product with excellent thermal conductivity, the content of component (A) is preferably 20% by mass or more, more preferably 30% by mass or more, and even more preferably 40% by mass or more, when the non-volatile components in the curable composition are considered to be 100% by mass. The upper limit is preferably 80% by mass or less, more preferably 65% by mass or less, and even more preferably 50% by mass or less. When the content of component (A) is within the above range, the thermal conductivity and elastic modulus can be effectively improved. Also, when the content of component (A) is usually below the upper limit, the viscosity of the curable composition can be lowered, thus improving workability and adhesiveness.

<(B) Silsesquioxane compounds>
The curable composition contains a silsesquioxane compound (B) as component (B). By combining component (B) with component (C), described later, in the curable composition, it is possible to obtain a cured product with excellent thermal conductivity and low elastic modulus. Generally, suppressing phonon scattering tends to increase the thermal conductivity of the cured product. The reason why the thermal conductivity of the cured product of the curable composition improves when component (B) is included is not clear, but it is presumed that the framework of component (B) suppresses phonon scattering. Component (B) may be used alone or in combination of two or more types.

Component (B) can be a compound having a silsesquioxane structure. A silsesquioxane structure is a structure in which one silicon atom is bonded to three oxygen atoms, and each oxygen atom is bonded to two silicon atoms, and is represented by the following structural formula (B-1).
In the formula, R independently represents an alkyl group, a hydroxyl group, a glycidyl group, an epoxy group, a thiol group, an alkoxy group, or a (meth)acryloyl group, and n represents an integer from 4 to 20.

If, among the silsesquioxane structures contained in component (B), at least one R represents a glycidyl group or an epoxy group, then component (B) is an epoxy-containing silsesquioxane compound having an epoxy group.

If, in the silsesquioxane structure contained in component (B), all R groups independently represent a hydrocarbon group, a hydroxyl group, a thiol group, an alkoxy group, or a (meth)acryloyl group, then component (B) is a silsesquioxane compound without epoxy groups. The (meth)acryloyl group includes methacryloyl groups, acryloyl groups, and combinations thereof.

The curable composition of the present invention, when containing an epoxy group-containing silsesquioxane compound as component (B), also contains the epoxy resin (D) described later.

The curable composition of the present invention, when not containing an epoxy group-containing silsesquioxane compound as component (B), may or may not contain the epoxy resin (D) described later. However, from the viewpoint of significantly obtaining the effects of the present invention, it is preferable to include the epoxy resin (D).

The alkyl group represented by R may be linear, branched, or cyclic. Preferably, the alkyl group has 1 to 6 carbon atoms, more preferably 1 to 3 carbon atoms, and even more preferably a methyl or ethyl group.

The alkoxy group represented by R is preferably an alkoxy group having 1 to 6 carbon atoms, more preferably an alkoxy group having 1 to 3 carbon atoms, and even more preferably a methoxy group or an ethoxy group.

In particular, R is preferably a functional group that can react with component (C), more preferably selected from a hydroxyl group, a glycidyl group, an epoxy group, and a thiol group, even more preferably selected from a glycidyl group, an epoxy group, and a thiol group, and particularly preferably either an epoxy group or a thiol group.

n represents an integer between 4 and 20, preferably between 6 and 12.

Component (B) may include a structure represented by the following formula (B-2) in addition to the silsesquioxane structure. If component (B) includes a structure represented by formula (B-2), it is preferable that the structure represented by formula (B-2) is located at a part of the terminal of component (B).
In the formula, ^R1 is the same as R in formula (B-1). * represents a bond with the silsesquioxane structure.

Examples of silsesquioxane structures include random structures, ladder structures with a ladder skeleton, and cage structures. Component (B) preferably contains one or more selected from random structures, ladder structures, and cage structures; more preferably contains either a random structure or a cage structure; and even more preferably contains a random structure.

A random structure is a structure in which the arrangement of silsesquioxane structures lacks regularity and is incomplete. A typical random structure is the structure represented by formula (B-3) below. A typical ladder structure is the structure represented by formula (B-4) below. There are two types of cage structures: fully condensed cage structures and incompletely condensed cage structures. A fully condensed cage structure is a structure that contains multiple cyclic structures composed of silsesquioxane structures, and these multiple cyclic structures form a closed space or can form a closed space after the reaction. An incompletely condensed cage structure is a structure in which at least one part of the fully condensed cage structure is not closed. Typical fully condensed cage structures include the T8 structure with eight silicon atoms represented by formula (B-5) below, the T10 structure with ten silicon atoms represented by formula (B-6) below, and the T12 structure with twelve silicon atoms represented by formula (B-7) below. A typical example of an incomplete condensation cage structure is the structure represented by the following formula (B-8). In the formula, ^R² is the same as R in formula (B-1), and * represents a bond with the silsesquioxane structure.

The identification of whether component (B) has a random structure, ladder structure, or cage structure can be measured according to known methods. For example, a specific identification method can be measured according to the method described in Japanese Patent Application Publication No. 2022-3126.

Component (B) can be synthesized by known methods. Alternatively, commercially available components (B) may be used. Examples of commercially available components (B) include "SQ-502-8" and "SQ-107" from Arakawa Chemical Industries, Ltd., and "AC-SQ-TA-100" and "AC-SQ-SI20" from Toagosei Co., Ltd.

The functional group equivalent of component (B) is preferably 170 g/eq. or more, more preferably 180 g/eq. or more, even more preferably 190 g/eq. or more, preferably 300 g/eq. or less, more preferably 290 g/eq. or less, and even more preferably 280 g/eq. or less. Unless otherwise specified, the functional group equivalent represents the mass of the resin containing one equivalent of a functional group.

In the case of a silsesquioxane compound that does not contain epoxy groups and has thiol groups, the thiol group equivalent of component (B) is preferably 170 g/eq. or more, more preferably 180 g/eq. or more, even more preferably 190 g/eq. or more, preferably 220 g/eq. or less, more preferably 210 g/eq. or less, and even more preferably 200 g/eq. or less. "Thiol group equivalent" refers to the mass of resin containing one equivalent of thiol groups, and can be measured by known methods, such as iodine solution titration using starch as an indicator.

The epoxy equivalent of the epoxy group-containing silsesquioxane compound is preferably 250 g/eq. or higher, more preferably 260 g/eq. or higher, even more preferably 270 g/eq. or higher, preferably 300 g/eq. or lower, more preferably 290 g/eq. or lower, and even more preferably 280 g/eq. or lower. The epoxy equivalent can be measured according to JIS K7236 and is the mass of the resin containing one equivalent of epoxy groups.

The weight-average molecular weight of component (B) is preferably 100 to 50,000, more preferably 500 to 10,000, and even more preferably 1,000 to 10,000. Here, the weight-average molecular weight of component (B) is the weight-average molecular weight in polystyrene terms, measured by gel permeation chromatography (GPC).

Regarding the content of component (B), from the viewpoint of significantly obtaining the effects of the present invention, when the nonvolatile component in the curable composition is considered to be 100% by mass, it is preferably 5% by mass or more, more preferably 15% by mass or more, even more preferably 25% by mass or more, preferably 65% by mass or less, more preferably 55% by mass or less, and even more preferably 45% by mass or less.

If component (B) does not contain an epoxy group-containing silsesquioxane compound, the content of component (B) is preferably 5% by mass or more, more preferably 15% by mass or more, even more preferably 25% by mass or more, preferably 65% by mass or less, more preferably 55% by mass or less, and even more preferably 45% by mass or less, when the nonvolatile components in the curable composition are considered to be 100% by mass.

When component (B) contains an epoxy group-containing silsesquioxane compound and the curable composition contains component (D) described later, the content of the epoxy group-containing silsesquioxane compound is preferably 5% by mass or more, more preferably 15% by mass or more, even more preferably 25% by mass or more, preferably 65% by mass or less, more preferably 55% by mass or less, and even more preferably 45% by mass or less, when the nonvolatile components in the curable composition are considered to be 100% by mass.

When component (B) contains an epoxy group-containing silsesquioxane compound and the curable composition does not contain component (D) described later, the content of the epoxy group-containing silsesquioxane compound is preferably 10% by mass or more, more preferably 20% by mass or more, even more preferably 30% by mass or more, preferably 65% by mass or less, more preferably 55% by mass or less, and even more preferably 45% by mass or less, when the nonvolatile components in the curable composition are considered to be 100% by mass.

<(C) Liquid polythiol compound>
The curable composition contains a liquid polythiol compound as component (C). This liquid polythiol compound (C) does not include any of the components described above as component (B). By combining component (C) and component (B) and including them in the curable composition, it is possible to improve the thermal conductivity and lower the elastic modulus of the cured product of the curable composition. Component (C) may be used alone or in combination of two or more types. In this invention, "liquid" means having fluidity at room temperature (20°C) and atmospheric pressure (0.1 MPa). Preferably, the viscosity measured using an E-type viscometer at atmospheric pressure, 25°C, and a cone rotation speed of 2.0 rpm is 200,000 mPa·s or less. An example of an E-type viscometer is the E-type viscometer: RE-85U (cone rotor: 3° × R14) (manufactured by Toki Sangyo Co., Ltd.).

As component (C), a polythiol compound that has the function of curing the curable composition by reacting with the functional group of component (B) or the epoxy group of component (D), and that is liquid at a temperature of 20°C, can be used. From the viewpoint of obtaining the effects of the present invention in particular, the number of thiol groups in one molecule of component (C) is preferably 2 or more (2 or more functional groups), more preferably 3 or more (3 or more functional groups), preferably 6 or less (6 or fewer functional groups), and more preferably 5 or less (5 or fewer functional groups).

Examples of such liquid polythiol compounds include trimethylolpropane tris(3-mercaptopropionate) (abbreviation: TMTP), pentaerythritol tetrakis(3-mercaptopropionate) (abbreviation: PEMP), dipentaerythritol hexakis(3-mercaptopropionate) (abbreviation: DPMP), tris-[(3-mercaptopropionyloxy)-ethyl]-isocyanurate (abbreviation: TEMPIC), tris(3-mercaptopropyl)isocyanurate (abbreviation: TMPIC), octyl thioglycolate (abbreviation: OTG), ethylene glycol bisthioglycolate (abbreviation: EGTG), trimethylolpropane tristhioglycolate (abbreviation: TMTG), and pentaerythritol Examples include lithol tetrakisthioglycolate (abbreviated as PETG), 3-mercaptopropionic acid (abbreviated as 3-MPA), pentaerythritol tetrakis(3-mercaptobutyrate), 1,4-bis(3-mercaptobutyryloxy)butane, 1,3,5-tris(3-mercaptobutyryloxyethyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, trimethylolpropanetris(3-mercaptobutyrate) (abbreviated as TPMB), trimethylolethanetris(3-mercaptobutyrate) (abbreviated as TEMB), 1,3,4,6-tetrakis(2-mercaptoethyl)glycoluryl, and 4,4'-isopropylidenebis[(3-mercaptopropoxy)benzene].

These compounds can be synthesized by known methods. For example, tris(3-mercaptopropyl)isocyanurate (abbreviated as TMPIC) and 4,4'-isopropylidenebis[(3-mercaptopropoxy)benzene] can be synthesized, for example, by the methods described in Japanese Patent Application Publication No. 2012-153794 and International Publication No. 2001/00698.

(C) Component may be a commercially available product. Examples of commercially available products include "PEMP" (manufactured by SC Organic Chemicals Co., Ltd.), "OTG", "EGTG", "TMTG", "PETG", "3-MPA", "TMTP", "PETP" (manufactured by Yodo Chemical Co., Ltd.), "TEMP", "PEMP", "TEMPIC", "DPMP" (manufactured by Sakai Chemical Industry Co., Ltd.), "PE-1" (pentaerythritol tetrakis(3-mercaptobutyrate)), "BD-1" (1,4-bis(3-mercaptobutyryloxy)butane), "NR-1" (1,3,5-tris(3-mercaptobutyryloxyethyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione), "TPMB", "TEMB" (manufactured by Showa Denko Corporation), and "TS-G" (mercaptoethyl glycol) (manufactured by Shikoku Chemicals Co., Ltd.).

The thiol group equivalent of the polythiol compound is preferably 50 to 500 g/eq, more preferably 75 to 300 g/eq, and even more preferably 100 to 200 g/eq. "Thiol group equivalent" refers to the number of grams (g/eq) of resin containing 1 gram equivalent of thiol groups, and can be measured by known methods, such as iodine solution titration using starch as an indicator.

The ratio of component (B) to component (C) is preferably in the range of 1:0.1 to 1:5, more preferably 1:0.5 to 1:2, and even more preferably 1:0.5 to 1:1, as expressed in the ratio of [total number of functional groups in component (B)] : [total number of thiol groups in component (C)]. Here, the functional group of (B) is one of the hydroxyl group, glycidyl group, epoxy group, and thiol group represented by R in the above formula (B-1), and varies depending on the type of component (B). Furthermore, the total number of functional groups of component (B) is the sum of the values obtained by dividing the solid content mass of each component (B) by the functional group equivalent for all components (B), and the total number of thiol groups of component (C) is the sum of the values obtained by dividing the solid content mass of each component (C) by the thiol group equivalent for all components (C). By setting the ratio of component (B) to component (C) within this range, it becomes possible to more significantly improve the effects of the present invention.

When the curable composition contains the epoxy resin (D) described later, the ratio of the epoxy resin (D) to component (C) is preferably in the range of 1:0.1 to 1:3, more preferably 1:0.5 to 1:2, and even more preferably 1:0.5 to 1:1, as expressed in the ratio of [total number of epoxy groups in the epoxy resin] : [total number of thiol groups in component (C)]. The total number of epoxy groups in the epoxy resin is the sum of the values obtained by dividing the solid content mass of each (D) epoxy resin by the epoxy equivalent for all epoxy resins, and the total number of thiol groups in component (C) is the sum of the values obtained by dividing the solid content mass of each (C) component by the thiol group equivalent for all (C) components. By setting the ratio of the epoxy resin (D) to component (C) within this range, the heat resistance of the cured product of the curable composition is further improved.

The content of component (C) is preferably 5% by mass or more, more preferably 10% by mass or more, even more preferably 15% by mass or more, preferably 30% by mass or less, more preferably 28% by mass or less, and even more preferably 25% by mass or less, when the nonvolatile components in the curable composition are considered to be 100% by mass.

When the non-volatile components in the curable composition are considered to be 100% by mass, and the content of component (B) is denoted as B1 (by mass%), and the content of component (C) is denoted as C1 (by mass%), then from the viewpoint of significantly obtaining the effects of the present invention, the ratio of B1/C1 is preferably 0.1 or more, more preferably 0.8 or more, even more preferably 1 or more, preferably 5 or less, more preferably 3 or less, and even more preferably 2 or less.

<(D) Epoxy resin>
If the curable composition does not contain an epoxy group-containing silsesquioxane compound as component (B), the curable composition contains epoxy resin (D) as component (D). If the curable composition contains an epoxy group-containing silsesquioxane compound as component (B), it may or may not contain epoxy resin (D) as an optional component in combination with components (A) to (C) described above. This epoxy resin (D) does not include those corresponding to components (A) to (C) described above. By including component (D) in the curable composition, the insulation reliability can be improved. If component (B) contains an epoxy group-containing silsesquioxane compound, epoxy resin (D) may not be included, but from the viewpoint of significantly obtaining the effects of the present invention, it is preferable to include epoxy resin (D).

Examples of component (D) include bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, bisphenol AF type epoxy resin, dicyclopentadiene type epoxy resin, trisphenol type epoxy resin, naphthol novolac type epoxy resin, phenol novolac type epoxy resin, tert-butyl-catechol type epoxy resin, naphthalene type epoxy resin, naphthol type epoxy resin, anthracene type epoxy resin, glycidylamine type epoxy resin, glycidyl ester type epoxy resin, cresol novolac type epoxy resin, biphenyl type epoxy resin, linear aliphatic epoxy resin, epoxy resin having a butadiene structure, alicyclic epoxy resin, heterocyclic epoxy resin, spiroring-containing epoxy resin, cyclohexanedimethanol type epoxy resin, naphthylene ether type epoxy resin, and trimethylol type epoxy resin. Component (D) epoxy resin may be used alone or in combination of two or more types.

Component (D) preferably contains an epoxy resin having two or more epoxy groups per molecule. From the viewpoint of significantly obtaining the desired effects of the present invention, the ratio of epoxy resin having two or more epoxy groups per molecule to 100% by mass of the non-volatile component of the epoxy resin is preferably 50% by mass or more, more preferably 60% by mass or more, and particularly preferably 70% by mass or more.

Component (D) is classified into a liquid epoxy resin at 20°C (hereinafter referred to as "liquid epoxy resin") and a solid epoxy resin at 20°C (hereinafter referred to as "solid epoxy resin"). The curable composition may contain only liquid epoxy resin, only solid epoxy resin, or a combination of both. However, from the viewpoint of significantly achieving the effects of the present invention, it is preferable to contain only liquid epoxy resin.

As the liquid epoxy resin, a liquid epoxy resin having two or more epoxy groups per molecule is preferred.

Preferred liquid epoxy resins include bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol AF type epoxy resin, naphthalene type epoxy resin, glycidyl ester type epoxy resin, glycidylamine type epoxy resin, phenol novolac type epoxy resin, alicyclic epoxy resin having an ester skeleton, cyclohexane type epoxy resin, cyclohexanedimethanol type epoxy resin, glycidylamine type epoxy resin, and epoxy resin having a butadiene structure. Bisphenol A type epoxy resin and bisphenol F type epoxy resin are more preferred.

Specific examples of liquid epoxy resins include DIC Corporation's "HP4032," "HP4032D," and "HP4032SS" (naphthalene-type epoxy resins); Mitsubishi Chemical Corporation's "828US," "jER828EL," "825," and "Epicote 828EL" (bisphenol A-type epoxy resins); Mitsubishi Chemical Corporation's "jER807" and "1750" (bisphenol F-type epoxy resins); Mitsubishi Chemical Corporation's "jER152" (phenol novolac-type epoxy resin); and Mitsubishi Chemical Corporation's "630" and "630LSD" (glycidylamine-type epoxy resins). Examples include: "ZX1059" (a mixture of bisphenol A type epoxy resin and bisphenol F type epoxy resin) manufactured by Nippon Steel Chemical & Material Co., Ltd.; "EX-721" (glycidyl ester type epoxy resin) manufactured by Nagase ChemteX Corporation; "Celoxide 2021P" (alicyclic epoxy resin with an ester skeleton) manufactured by Daicel Corporation; "PB-3600" (epoxy resin with a butadiene structure) manufactured by Daicel Corporation; and "ZX1658" and "ZX1658GS" (liquid 1,4-glycidylcyclohexane type epoxy resin) manufactured by Nippon Steel Chemical & Material Co., Ltd. These may be used individually or in combination of two or more types.

As the solid epoxy resin, a solid epoxy resin having three or more epoxy groups per molecule is preferred, and an aromatic solid epoxy resin having three or more epoxy groups per molecule is more preferred.

Preferred solid epoxy resins include bixylenol-type epoxy resin, naphthalene-type epoxy resin, naphthalene-type tetrafunctional epoxy resin, novolac-type epoxy resin, cresol-novolac-type epoxy resin, dicyclopentadiene-type epoxy resin, trisphenol-type epoxy resin, naphthol-type epoxy resin, biphenyl-type epoxy resin, naphthylene ether-type epoxy resin, anthracene-type epoxy resin, bisphenol A-type epoxy resin, bisphenol AF-type epoxy resin, and tetraphenylethane-type epoxy resin.

Specific examples of solid epoxy resins include DIC's "HP4032H" (naphthalene-type epoxy resin), "HP-4700", "HP-4710" (naphthalene-type tetrafunctional epoxy resin), "N-690" (cresol novolac-type epoxy resin), "N-695" (cresol novolac-type epoxy resin), "HP-7200", "HP-7200HH", and "HP-7200H" (dicyclopentadiene-type epoxy resin). (Epoxy resin), "EXA-7311", "EXA-7311-G3", "EXA-7311-G4", "EXA-7311-G4S", "HP6000", "HP6000L" (naphthylene ether type epoxy resin); Nippon Kayaku Co., Ltd.'s "EPPN-502H" (trisphenol type epoxy resin), "NC7000L" (naphthol novolac type epoxy resin), "NC3000H", "NC3000", "N Examples include C3000L and NC3100 (biphenyl-type epoxy resin); ESN475V (naphthalene-type epoxy resin) and ESN485 (naphthol novolac-type epoxy resin) from Nippon Steel Chemical &Material; YX4000H and YL6121 (biphenyl-type epoxy resin), YX4000HK (bixylenol-type epoxy resin), YX8800 (anthracene-type epoxy resin), and 157S70 (novolac-type epoxy resin) from Mitsubishi Chemical Corporation; PG-100 and CG-500 from Osaka Gas Chemical Co., Ltd.; and YX7760 (bisphenol AF-type epoxy resin), YL7800 (fluorene-type epoxy resin), jER1010 (solid bisphenol A-type epoxy resin), and jER1031S (tetraphenylethane-type epoxy resin) from Mitsubishi Chemical Corporation. These may be used individually or in combination of two or more types.

When using a combination of solid epoxy resin and liquid epoxy resin as the epoxy resin, the mass ratio of the solid epoxy resin to the liquid epoxy resin is preferably 1:0.01 to 1:50, more preferably 1:0.05 to 1:20, and particularly preferably 1:0.1 to 1:10. By setting the ratio of liquid epoxy resin to solid epoxy resin within this range, the following effects can be obtained: 1) appropriate tackiness is achieved when used in the form of a resin sheet; 2) sufficient flexibility is obtained when used in the form of a resin sheet, improving handling; and 3) a cured product with sufficient breaking strength can be obtained.

The epoxy equivalent of the epoxy resin is preferably 50 g/eq. to 5000 g/eq., more preferably 50 g/eq. to 3000 g/eq., even more preferably 80 g/eq. to 2000 g/eq., and even more preferably 110 g/eq. to 1000 g/eq. This range allows for the production of a curable composition with sufficient crosslinking density. The epoxy equivalent is the mass of the epoxy resin containing one equivalent of epoxy groups. This epoxy equivalent can be measured according to JIS K7236.

The weight-average molecular weight (Mw) of the epoxy resin is preferably 100 to 5000, more preferably 250 to 3000, and even more preferably 400 to 1500, from the viewpoint of significantly obtaining the desired effects of the present invention. The weight-average molecular weight of the epoxy resin is the weight-average molecular weight in terms of polystyrene, measured by gel permeation chromatography (GPC).

(D) The epoxy resin content is preferably 1% by mass or more, more preferably 3% by mass or more, and even more preferably 5% by mass or more, when the non-volatile components in the curable composition are considered to be 100% by mass, from the viewpoint of obtaining a cured product exhibiting good mechanical strength and insulation reliability. The upper limit of the epoxy resin content is preferably 25% by mass or less, more preferably 20% by mass or less, and even more preferably 15% by mass or less, from the viewpoint of significantly obtaining the desired effects of the present invention.

If component (B) does not contain an epoxy group-containing silsesquioxane compound, the content of (D) epoxy resin is preferably 1% by mass or more, more preferably 3% by mass or more, even more preferably 5% by mass or more, preferably 25% by mass or less, more preferably 20% by mass or less, and even more preferably 15% by mass or less, when the nonvolatile components in the curable composition are considered to be 100% by mass.

When component (B) contains an epoxy group-containing silsesquioxane compound and the curable composition contains epoxy resin (D), the content of epoxy resin (D) is preferably 1% by mass or more, more preferably 3% by mass or more, even more preferably 5% by mass or more, preferably 25% by mass or less, more preferably 20% by mass or less, and even more preferably 15% by mass or less, when the nonvolatile components in the curable composition are considered to be 100% by mass.

When component (B) contains an epoxy group-containing silsesquioxane compound and component (D) is also present, if the content of component (B) in the curable composition is taken as 100% by mass, then B2 is the content of component (B) and D1 is the content of component (D). From the viewpoint of significantly obtaining the effects of the present invention, B2/D1 is preferably 1 or more, more preferably 1.5 or more, even more preferably 2 or more, preferably 5 or less, more preferably 4 or less, and even more preferably 3 or less.

When component (B) does not contain an epoxy group-containing silsesquioxane compound and component (D) is present, if the content of component (B) in the curable composition is taken as 100% by mass, then B3 is the content of component (B) and D1 is the content of component (D). From the viewpoint of significantly obtaining the effects of the present invention, B3/D1 is preferably 1 or more, more preferably 1.5 or more, even more preferably 2 or more, preferably 5 or less, more preferably 4 or less, and even more preferably 3 or less.

<(E) Hardening accelerator>
The curable composition may further contain, as an optional component, (E) a curing accelerator in combination with the components (A) to (D) described above. This curing accelerator (E) does not include any of the components (A) to (D) described above. The curing accelerator (E) functions as a curing catalyst that accelerates the curing of the (B) silsesquioxane compound and the (D) epoxy resin.

Examples of such (E) curing accelerators include phosphorus-based curing accelerators, urea-based curing accelerators, guanidine-based curing accelerators, imidazole-based curing accelerators, metal-based curing accelerators, and amine-based curing accelerators. (E) curing accelerators may be used individually or in combination of two or more types.

Examples of phosphorus-based curing accelerators include aliphatic phosphonium salts such as tetrabutylphosphonium bromide, tetrabutylphosphonium chloride, tetrabutylphosphonium acetate, tetrabutylphosphonium decanoate, tetrabutylphosphonium laurate, bis(tetrabutylphosphonium) pyromelitate, tetrabutylphosphonium hydrogen hexahydrophthalate, tetrabutylphosphonium 2,6-bis[(2-hydroxy-5-methylphenyl)methyl]-4-methylphenolate, di-tert-butyldimethylphosphonium tetraphenylborate; methyltriphenylphosphonium bromide, ethyltriphenylphosphonium bromide, propyltriphenylphosphonium bromide, butyltriphenylphosphonium bromide, benzyltriphenylphosphonium chloride, and tetraphenyl Aromatic phosphonium salts such as phosphonium bromide, p-tolyltriphenylphosphonium tetra-p-tolylborate, tetraphenylphosphonium tetraphenylborate, tetraphenylphosphonium tetra-p-tolylborate, triphenylethylphosphonium tetraphenylborate, tris(3-methylphenyl)ethylphosphonium tetraphenylborate, tris(2-methoxyphenyl)ethylphosphonium tetraphenylborate, (4-methylphenyl)triphenylphosphonium thiocyanate, tetraphenylphosphonium thiocyanate, and butyltriphenylphosphonium thiocyanate; aromatic phosphine-borane complexes such as triphenylphosphine and triphenylborane; aromatic phosphine-quinone addition products such as triphenylphosphine-p-benzoquinone addition products; tributylphosphine, tri- Aliphatic phosphines such as tert-butylphosphine, trioctylphosphine, di-tert-butyl(2-butenyl)phosphine, di-tert-butyl(3-methyl-2-butenyl)phosphine, tricyclohexylphosphine; dibutylphenylphosphine, di-tert-butylphenylphosphine, methyldiphenylphosphine, ethyldiphenylphosphine, butyldiphenylphosphine, diphenylcyclohexylphosphine, triphenylphosphine, tri-o-tolylphosphine, tri-m-tolylphosphine, tri-p-tolylphosphine, tris(4-ethylphenyl)phosphine, tris(4-propylphenyl)phosphine, tris(4-isopropylphenyl)phosphine, tris(4-butylphenyl)phosphine, tris(4-tert-butylphenyl)phosphine, tris(2,4-dimethylphenyl) Examples of aromatic phosphines include tris(2,5-dimethylphenyl)phosphine, tris(2,6-dimethylphenyl)phosphine, tris(3,5-dimethylphenyl)phosphine, tris(2,4,6-trimethylphenyl)phosphine, tris(2,6-dimethyl-4-ethoxyphenyl)phosphine, tris(2-methoxyphenyl)phosphine, tris(4-methoxyphenyl)phosphine, tris(4-ethoxyphenyl)phosphine, tris(4-tert-butoxyphenyl)phosphine, diphenyl-2-pyridylphosphine, 1,2-bis(diphenylphosphino)ethane, 1,3-bis(diphenylphosphino)propane, 1,4-bis(diphenylphosphino)butane, 1,2-bis(diphenylphosphino)acetylene, and 2,2'-bis(diphenylphosphino)diphenyl ether.

Examples of urea-based curing accelerators include aliphatic dimethylureas such as 1,1-dimethylurea, 1,1,3-trimethylurea, 3-ethyl-1,1-dimethylurea, 3-cyclohexyl-1,1-dimethylurea, and 3-cyclooctyl-1,1-dimethylurea; 3-phenyl-1,1-dimethylurea, 3-(4-chlorophenyl)-1,1-dimethylurea, 3-(3,4-dichlorophenyl)-1,1-dimethylurea, 3-(3-chloro-4-methylphenyl)-1,1-dimethylurea, 3-(2-methylphenyl)-1,1-dimethylurea, 3-(4-methylphenyl)-1,1-dimethylurea, and 3-(3,4-dimethylphenyl)-1,1-dimethylurea. Examples include aromatic dimethylureas such as tolueneurea, 3-(4-isopropylphenyl)-1,1-dimethylurea, 3-(4-methoxyphenyl)-1,1-dimethylurea, 3-(4-nitrophenyl)-1,1-dimethylurea, 3-[4-(4-methoxyphenoxy)phenyl]-1,1-dimethylurea, 3-[4-(4-chlorophenoxy)phenyl]-1,1-dimethylurea, 3-[3-(trifluoromethyl)phenyl]-1,1-dimethylurea, N,N-(1,4-phenylene)bis(N',N'-dimethylurea), and N,N-(4-methyl-1,3-phenylene)bis(N',N'-dimethylurea) [toluenebisdimethylurea].

Examples of guanidine-based curing accelerators include dicyandiamide, 1-methylguanidine, 1-ethylguanidine, 1-cyclohexylguanidine, 1-phenylguanidine, 1-(o-tolyl)guanidine, dimethylguanidine, diphenylguanidine, trimethylguanidine, tetramethylguanidine, pentamethylguanidine, 1,5,7-triazabicyclo[4.4.0]deca-5-ene, 7-methyl-1,5,7-triazabicyclo[4.4.0]deca-5-ene, 1-methylbiguanide, 1-ethylbiguanide, 1-n-butylbiguanide, 1-n-octadecylbiguanide, 1,1-dimethylbiguanide, 1,1-diethylbiguanide, 1-cyclohexylbiguanide, 1-allylbiguanide, 1-phenylbiguanide, and 1-(o-tolyl)biguanide.

Examples of imidazole-based curing accelerators include 2-methylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 1,2-dimethylimidazole, 2-ethyl-4-methylimidazole, 1,2-dimethylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 1-benzyl-2-methylimidazole, 1-benzyl-2- Phenylimidazole, 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-undecylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, 1-cyanoethyl-2-phenylimidazole, 1-cyanoethyl-2-undecylimidazolium trimellitate, 1-cyanoethyl-2-phenylimidazolium trimellitate, 2,4-diamino-6-[2'-methylimidazolyl] -(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-undecylimidazolyl-(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-ethyl-4'-methylimidazolyl-(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine isocyanurate adduct, 2-phenylimidazole isocyanurate adduct Examples include imidazole compounds such as 2-phenyl-4,5-dihydroxymethylimidazole, 2-phenyl-4-methyl-5-hydroxymethylimidazole, 2,3-dihydro-1H-pyrrolo[1,2-a]benzimidazole, 1-dodecyl-2-methyl-3-benzylimidazolium chloride, 2-methylimidazoline, and 2-phenylimidazoline, as well as adducts of imidazole compounds with epoxy resins. Examples of commercially available imidazole-based curing accelerators include "1B2PZ," "2E4MZ," "2MZA-PW," "2MZ-OK," "2MA-OK," "2MA-OK-PW," "2PHZ," "2PHZ-PW," "Cl1Z," "Cl1Z-CN," "Cl1Z-CNS," and "C11Z-A" from Shikoku Chemicals Corporation; and "P200-H50" from Mitsubishi Chemical Corporation.

Examples of metal-based hardening accelerators include organometallic complexes or organometallic salts of metals such as cobalt, copper, zinc, iron, nickel, manganese, and tin. Specific examples of organometallic complexes include organocobalto complexes such as cobalt(II) acetylacetonate and cobalt(III) acetylacetonate, organocouprogentocompound complexes such as copper(II) acetylacetonate, organozinc complexes such as zinc(II) acetylacetonate, organoiron complexes such as iron(III) acetylacetonate, organoniceric complexes such as nickel(II) acetylacetonate, and organomanganese complexes such as manganese(II) acetylacetonate. Examples of organometallic salts include zinc octoate, tin octoate, zinc naphthenate, cobalt naphthenate, tin stearate, and zinc stearate.

Examples of amine-based curing accelerators include trialkylamines such as triethylamine and tributylamine, 4-dimethylaminopyridine, benzyldimethylamine, 2,4,6-tris(dimethylaminomethyl)phenol, and 1,8-diazabicyclo(5,4,0)-undecene. Commercially available amine-based curing accelerators may also be used; for example, "MY-25" manufactured by Ajinomoto Fine Techno Co., Ltd. is one such example.

(E) The content of the curing accelerator is preferably 0.1% by mass or more, more preferably 0.3% by mass or more, even more preferably 0.5% by mass or more, preferably 5% by mass or less, more preferably 3% by mass or less, and even more preferably 1% by mass or less, when the nonvolatile components in the curable composition are considered to be 100% by mass.

<(F) Any additives>
The curable composition may further contain (F) any additive as an optional nonvolatile component, in combination with the components (A) to (D) described above. (F) Optional additives include, for example, preservatives and stabilizers; curing agents; thermoplastic resins; polymerization initiators; organometallic compounds such as organocopper compounds, organozinc compounds, and organocobalt compounds; colorants such as phthalocyanine blue, phthalocyanine green, iodine green, diazo yellow, crystal violet, titanium dioxide, and carbon black; polymerization inhibitors such as hydroquinone, catechol, pyrogallol, and phenothiazine; leveling agents such as silicone-based leveling agents and acrylic polymer-based leveling agents; thickeners such as bentonite and montmorillonite; defoamers such as silicone-based defoamers, acrylic-based defoamers, fluorine-based defoamers, and vinyl resin-based defoamers; ultraviolet absorbers such as benzotriazole-based ultraviolet absorbers; adhesion improvers such as urea silane; adhesion ferrites such as triazole-based adhesion ferrites, tetrazole-based adhesion ferrites, and triazine-based adhesion ferrites; hindered ferrites Examples include antioxidants such as ol-based antioxidants; fluorescent whitening agents such as stilbene derivatives; surfactants such as fluorine-based surfactants and silicone-based surfactants; flame retardants such as phosphorus-based flame retardants (e.g., phosphate ester compounds, phosphazene compounds, phosphinic acid compounds, red phosphorus), nitrogen-based flame retardants (e.g., melamine sulfate), halogen-based flame retardants, and inorganic flame retardants (e.g., antimony trioxide); dispersants such as phosphate ester-based dispersants, polyoxyalkylene-based dispersants, acetylene-based dispersants, silicone-based dispersants, anionic dispersants, and cationic dispersants; stabilizers such as borate-based stabilizers, titanate-based stabilizers, aluminate-based stabilizers, zirconate-based stabilizers, isocyanate-based stabilizers, carboxylic acid-based stabilizers, and carboxylic acid anhydride-based stabilizers; photopolymerization initiators such as tertiary amines; and photosensitizers such as pyrarizones, anthracenes, coumarins, xanthones, and thioxanthones. (F) Any additive may be used individually or in combination of two or more types.

The curable composition may further contain any solvent as a volatile component. Examples of solvents include organic solvents. Furthermore, the solvent may be used alone, or two or more solvents may be used in any ratio.

Examples of solvents include ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; ester solvents such as methyl acetate, ethyl acetate, butyl acetate, isobutyl acetate, isoamyl acetate, methyl propionate, ethyl propionate, and γ-butyrolactone; ether solvents such as tetrahydropyran, tetrahydrofuran, 1,4-dioxane, diethyl ether, diisopropyl ether, dibutyl ether, and diphenyl ether; alcohol solvents such as methanol, ethanol, propanol, butanol, and ethylene glycol; and 2-ethoxyethyl acetate, propylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, ethyl diglycol acetate, γ-butyrolactone, and methyl methoxypropionate. Examples of solvents include ether ester solvents; ester alcohol solvents such as methyl lactate, ethyl lactate, and methyl 2-hydroxyisobutyrate; ether alcohol solvents such as 2-methoxypropanol, 2-methoxyethanol, 2-ethoxyethanol, propylene glycol monomethyl ether, and diethylene glycol monobutyl ether (butyl carbitol); amide solvents such as N,N-dimethylformamide, N,N-dimethylacetamide, and N-methyl-2-pyrrolidone; sulfoxide solvents such as dimethyl sulfoxide; nitrile solvents such as acetonitrile and propionitrile; aliphatic hydrocarbon solvents such as hexane, cyclopentane, cyclohexane, and methylcyclohexane; and aromatic hydrocarbon solvents such as benzene, toluene, xylene, ethylbenzene, and trimethylbenzene.

The amount of solvent is preferably 3% by mass or less, more preferably 1% by mass or less, even more preferably 0.5% by mass or less, even more preferably 0.1% by mass or less, and even more preferably 0.01% by mass or less, relative to 100% by mass of the non-volatile components in the curable composition. It is particularly preferable that there is no solvent (0% by mass). Furthermore, when the amount of solvent is so low, the curable composition may be in paste form. The viscosity of the paste-like curable composition at 25°C is preferably in the range of 20 Pa·s to 1000 Pa·s.

The method for preparing the curable composition is not particularly limited. For example, it can be manufactured by adding the components in any order and/or some or all of them simultaneously to any preparation container and mixing them. The temperature can be appropriately set during the process of adding and mixing each component, and heating and/or cooling may be performed temporarily or continuously. Stirring or shaking may also be performed during the process of adding and mixing each component. Furthermore, the curable composition may be stirred or shaken using a stirring or shaking device, such as a mixer, during or after mixing to ensure uniform dispersion. Degassing may also be performed simultaneously with stirring or shaking under low-pressure conditions, such as under vacuum. The mixing temperature may be, for example, 10 to 40°C. The stirring speed during mixing may be, for example, 100 to 10,000 rpm. The mixing time may be, for example, 10 seconds to 10 minutes.

<Physical properties and applications of curable compositions>
The cured product obtained by thermal curing the curable composition at 120°C for 90 minutes exhibits excellent thermal conductivity. That is, it provides an insulating layer with high thermal conductivity. The thermal conductivity is preferably 1.4 W/m·K or higher, more preferably 1.41 W/m·K or higher, and even more preferably 1.42 W/m·K or higher. There is no particular upper limit to the thermal conductivity, but it can be 10 W/m·K or lower. The thermal conductivity can be evaluated by measuring it according to the method described in the examples below.

The cured product obtained by thermal curing the curable composition at 120°C for 90 minutes exhibits a low elastic modulus. That is, it yields an insulating layer with a low elastic modulus. The elastic modulus of the cured product is preferably less than 4000 MPa, more preferably 3500 MPa or less, and even more preferably 1000 MPa or less, 600 MPa or less, 500 MPa or less, or 150 MPa or less. The lower limit is not particularly limited, but can be 0.1 MPa or higher, for example. The elastic modulus can be evaluated according to the method described in the examples below. Because the cured product exhibits a low elastic modulus, a cured product with excellent impact resistance can be obtained.

The curable composition of the present invention can provide an insulating layer with high thermal conductivity and low elastic modulus. Therefore, the curable composition of the present invention can be suitably used as a curable composition for bonding heat sinks to electronic components (curable composition for heat sink bonding), a curable composition for forming an insulating layer of a semiconductor chip package (curable composition for insulating layer of semiconductor chip package), and a curable composition for forming an insulating layer of a circuit board (including printed wiring boards) (curable composition for insulating layer of circuit board). It can be even more suitably used as a curable composition for forming an interlayer insulating layer on which a conductive layer is formed by plating (curable composition for interlayer insulating layer of circuit board where a conductive layer is formed by plating). Furthermore, it can be suitably used as a curable composition for encapsulating semiconductor chips (curable composition for semiconductor chip encapsulation) and a curable composition for forming wiring on semiconductor chips (curable composition for semiconductor chip wiring formation).

[Curable composition-containing sheet]
The sheet containing the curable composition of the present invention comprises a support and a curable composition layer formed of the curable composition of the present invention, provided on the support.

From the viewpoint of miniaturization, the thickness of the curable composition layer is preferably 200 μm or less, more preferably 150 μm or less, and even more preferably 100 μm or less. The lower limit of the thickness of the curable composition layer is not particularly limited, but it can usually be 1 μm or more, 5 μm or more, 10 μm or more, etc.

Examples of support materials include films made of plastic materials, metal foils, and release paper, with films made of plastic materials and metal foils being preferred.

When using a film made of plastic material as a support, examples of plastic materials include polyesters such as polyethylene terephthalate (hereinafter sometimes abbreviated as "PET") and polyethylene naphthalate (hereinafter sometimes abbreviated as "PEN"), polycarbonate (hereinafter sometimes abbreviated as "PC"), acrylics such as polymethyl methacrylate (PMMA), cyclic polyolefins, triacetylcellulose (TAC), polyether sulfide (PES), polyether ketones, and polyimides. Among these, polyethylene terephthalate and polyethylene naphthalate are preferred, and inexpensive polyethylene terephthalate is particularly preferred.

When using metal foil as a support, examples of metal foil include copper foil and aluminum foil, with copper foil being preferred. As for copper foil, foil made of pure copper may be used, or foil made of an alloy of copper with another metal (e.g., tin, chromium, silver, magnesium, nickel, zirconium, silicon, titanium, etc.) may be used.

The support may have a matte finish, corona treatment, or antistatic treatment applied to the surface that bonds with the curable composition layer.

Furthermore, as the support, a support with a release layer may be used, which has a release layer on the surface that bonds with the curable composition layer. Examples of release agents used in the release layer of the support with a release layer include one or more release agents selected from the group consisting of alkyd resins, polyolefin resins, urethane resins, and silicone resins. Commercially available support products may be used for the support with a release layer. Examples include PET films having a release layer mainly composed of an alkyd resin-based release agent, such as "SK-1," "AL-5," and "AL-7" from Lintec Corporation, "Lumirror T60" from Toray Industries, Inc., "Purex" from Teijin Corporation, and "Unipeel" from Unitika Corporation.

The thickness of the support is not particularly limited, but is preferably in the range of 5 μm to 75 μm, and more preferably in the range of 10 μm to 60 μm. When using a support with a release layer, it is preferable that the overall thickness of the support with the release layer be within the above range.

In one embodiment, the sheet containing the curable composition may further include other layers as needed. Such other layers include, for example, a protective film similar to the support, provided on the side of the curable composition layer that is not bonded to the support (i.e., the side opposite the support). The thickness of the protective film is not particularly limited, but is, for example, 1 μm to 40 μm. By laminating the protective film, the adhesion of dust and other debris to the surface of the curable composition layer and scratches can be suppressed.

A sheet containing a curable composition can be manufactured, for example, by preparing a varnish containing the curable composition by dissolving the curable composition in an organic solvent, applying this varnish to a support using a die coater or the like, and then drying it to form a layer of the curable composition.

The organic solvent is the same as the solvent that may be included in the curable composition, as described above.

Drying may be carried out by known methods such as heating or hot air blowing. While the drying conditions are not particularly limited, the drying should be performed so that the content of the organic solvent in the curable composition layer is 10% by mass or less, preferably 5% by mass or less. Although this varies depending on the boiling point of the organic solvent in the curable composition-containing varnish, for example, when using a curable composition-containing varnish containing 30% to 60% by mass of organic solvent, the curable composition layer can be formed by drying at 50°C to 150°C for 3 to 10 minutes.

Sheets containing the curable composition can be stored by being rolled up. If the sheet has a protective film, it can be used after removing the protective film.

[Circuit board]
The circuit board of the present invention includes an insulating layer formed from a cured product of the curable composition of the present invention.
The method for manufacturing a circuit board of the present invention is:
(1) A step of preparing a substrate with a wiring layer, which has a substrate and a wiring layer provided on at least one surface of the substrate.
(2) A step of forming a curable composition layer on a substrate with a wiring layer so that the wiring layer is embedded, and then heat-curing it to form an insulating layer.
(3) Includes the step of inter-layer connection of wiring layers.
Furthermore, the method for manufacturing the circuit board may include (4) the step of removing the substrate.

Step (3) is not particularly limited as long as the wiring layers can be interlayer-connected, but it is preferably at least one of the following steps: forming via holes in the insulating layer and forming the wiring layer, and polishing or grinding the insulating layer to expose the wiring layer.

<Step (1)>
Step (1) is a step of preparing a substrate with a wiring layer, which has a substrate and a wiring layer provided on at least one side of the substrate. Typically, a substrate with a wiring layer has a first metal layer and a second metal layer, which are part of the substrate, on both sides of the substrate, and the wiring layer is on the side of the second metal layer opposite to the substrate side. Specifically, a dry film (photosensitive resist film) is laminated onto the substrate, and a pattern dry film is formed by exposure and development under predetermined conditions using a photomask. After forming a wiring layer by electroplating using the developed pattern dry film as a plating mask, the pattern dry film is peeled off.

Examples of substrates include glass epoxy substrates, metal substrates (such as stainless steel or cold-rolled steel sheets (SPCC)), polyester substrates, polyimide substrates, BT resin substrates, and thermosetting polyphenylene ether substrates. A metal layer, such as copper foil, may be formed on the substrate surface. Furthermore, peelable metal layers, such as a first metal layer and a second metal layer (for example, ultra-thin copper foil with carrier copper foil, product name "Micro Thin," manufactured by Mitsui Mining & Smelting Co., Ltd.), may be formed on the surface.

The dry film is not particularly limited as long as it is a photosensitive dry film made from a photoresist composition; for example, dry films made from novolac resin, acrylic resin, etc., can be used. Commercially available dry films may also be used.

Lamination of the substrate and dry film may be carried out by vacuum lamination. In vacuum lamination, the heat-pressing temperature is preferably in the range of 60°C to 160°C, more preferably 80°C to 140°C; the heat-pressing pressure is preferably in the range of 0.098 MPa to 1.77 MPa, more preferably 0.29 MPa to 1.47 MPa; and the heat-pressing time is preferably in the range of 20 seconds to 400 seconds, more preferably 30 seconds to 300 seconds. Lamination is preferably carried out under reduced pressure conditions of 13 hPa or less.

After laminating the dry film onto the substrate, the dry film is exposed and developed under predetermined conditions using a photomask to form the desired pattern.

The line (circuit width) / space (width between circuits) ratio of the wiring layer is not particularly limited, but is preferably 20/20 μm or less (i.e., pitch of 40 μm or less), more preferably 10/10 μm or less, even more preferably 5/5 μm or less, even more preferably 1/1 μm or less, and particularly preferably 0.5/0.5 μm or more. The pitch does not need to be the same throughout the entire wiring layer. The minimum pitch of the wiring layer may be 40 μm or less, 36 μm or less, or 30 μm or less.

After forming the pattern on the dry film, a wiring layer is formed, and the dry film is peeled off. Here, the wiring layer can be formed by using the dry film with the desired pattern as a plating mask and performing a plating method.

The conductive material used for the wiring layer is not particularly limited. In a preferred embodiment, the wiring layer contains one or more metals selected from the group consisting of gold, platinum, palladium, silver, copper, aluminum, cobalt, chromium, zinc, nickel, titanium, tungsten, iron, tin, and indium. The wiring layer may be a single-metal layer or an alloy layer. Examples of alloy layers include those formed from an alloy of two or more metals selected from the above group (e.g., nickel-chromium alloy, copper-nickel alloy, and copper-titanium alloy). Among these, from the viewpoint of versatility in wiring layer formation, cost, and ease of patterning, single-metal layers of chromium, nickel, titanium, aluminum, zinc, gold, palladium, silver, or copper, or alloy layers of nickel-chromium alloy, copper-nickel alloy, or copper-titanium alloy are preferred. Single-metal layers of chromium, nickel, titanium, aluminum, zinc, gold, palladium, silver, or copper, or alloy layers of nickel-chromium alloy are more preferred, and single-metal layers of copper are even more preferred.

The thickness of the wiring layer depends on the desired design of the wiring board, but is preferably 3 μm to 35 μm, more preferably 5 μm to 30 μm, and even more preferably 10 to 20 μm, or 15 to 20 μm. If step (3) involves polishing or grinding the insulating layer to expose the wiring layer and then inter-layer connecting the wiring layers, it is preferable that the thickness of the inter-layer connecting wiring differs from that of the unconnected wiring. The thickness of the wiring layer can be adjusted by repeating the pattern formation process described above. The thickness of the thickest wiring layer (conductive pillar) depends on the desired design of the wiring board, but is preferably 2 μm to 100 μm. The inter-layer connecting wiring may also be convex.

After forming the wiring layer, the dry film is peeled off. The dry film can be peeled off using an alkaline stripping solution, such as a sodium hydroxide solution. If necessary, unwanted wiring patterns can be removed by etching or other methods to form the desired wiring pattern. The pitch of the wiring layer to be formed is as described above.

<Step (2)>
Step (2) is a step in which a curable composition layer is formed on a substrate with a wiring layer so that the wiring layer is embedded, and then heat-cured to form an insulating layer. Specifically, the curable composition layer of the curable composition-containing sheet is bonded to the wiring layer of the substrate with a wiring layer obtained in step (1) above, and the curable composition layer is heat-cured to form an insulating layer. Alternatively, in step (2), the curable composition may be applied to the substrate with a wiring layer, and the curable composition may be heat-cured to form an insulating layer.

One embodiment of the method for forming a curable composition layer involves laminating a sheet containing a curable composition onto a substrate with a wiring layer so that the curable composition layer is bonded to the substrate with the wiring layer. In one embodiment, the lamination of the substrate with the wiring layer and the sheet containing the curable composition can be performed, for example, by heat-pressing the sheet containing the curable composition onto the substrate with the wiring layer from the support side. Examples of the heat-pressing member used to heat-press the sheet containing the curable composition onto the substrate with the wiring layer (hereinafter also referred to as the "heat-pressing member") include a heated metal plate (such as a SUS end plate) or a metal roll (such as a SUS roll). It is preferable to press the sheet containing the curable composition via an elastic material such as heat-resistant rubber, rather than directly pressing the sheet containing the curable composition onto it, so that the sheet conforms sufficiently to the surface irregularities of the substrate with the wiring layer.

Lamination of the substrate with the wiring layer and the sheet containing the curable composition may be carried out by a vacuum lamination method. In the vacuum lamination method, the heat-pressing temperature is preferably in the range of 60°C to 160°C, more preferably in the range of 80°C to 140°C; the heat-pressing pressure is preferably in the range of 0.098 MPa to 1.77 MPa, more preferably in the range of 0.29 MPa to 1.47 MPa; and the heat-pressing time is preferably in the range of 10 seconds to 400 seconds, more preferably in the range of 20 seconds to 300 seconds. Furthermore, lamination is preferably carried out under reduced pressure conditions of 26.7 hPa or less.

Lamination can be performed using a commercially available vacuum laminator. Examples of commercially available vacuum laminators include vacuum pressure laminators manufactured by Meiki Seisakusho Co., Ltd., vacuum applicators and batch-type vacuum pressure laminators manufactured by Nikko Materials Co., Ltd.

After lamination, the laminated sheets containing the curable composition may be smoothed by pressing a heat-pressure bonding member from the support side under normal pressure (atmospheric pressure). The pressing conditions for the smoothing process can be the same as those for the heat-pressure bonding process described above. The smoothing process can be performed using a commercially available laminator. Furthermore, lamination and the smoothing process may be performed continuously using a commercially available vacuum laminator.

Another embodiment of the method for forming a curable composition layer involves applying the curable composition onto a substrate with a wiring layer. For example, this can be done by injecting the curable composition with a syringe and then pressing the composition to form a curable composition layer of uniform thickness.

After forming a curable composition layer on a substrate with a wiring layer so that the wiring layer is embedded, the curable composition layer is heat-cured to form an insulating layer. The heat-curing conditions for the curable composition layer vary depending on the type of curable composition, but for example, the curing temperature can be in the range of 120°C to 240°C, and the curing time can be in the range of 5 minutes to 120 minutes. Before heat-curing the curable composition layer, it may be preheated at a temperature lower than the curing temperature.

After thermally curing the curable composition layer to form an insulating layer, the surface of the insulating layer may be polished. The polishing method is not particularly limited; any known method may be used. For example, the surface of the insulating layer can be polished using a surface grinding machine.

<Step (3)>
Step (3) is the step of inter-layer connection of the wiring layers. Specifically, it is the step of forming via holes in the insulating layer, forming a conductor layer, and inter-layer connection of the wiring layers. Alternatively, it is the step of polishing or grinding the insulating layer to expose the wiring layer and inter-layer connection of the wiring layers.

When employing a process of forming via holes in the insulating layer, forming a conductor layer, and then interlayer-connecting the wiring layer, the via hole formation method is not particularly limited, but examples include laser irradiation, etching, and mechanical drilling. However, laser irradiation is preferred. This laser irradiation can be performed using any suitable laser processing machine that employs a carbon dioxide laser, YAG laser, excimer laser, etc., as the light source.

The conditions for laser irradiation are not particularly limited, and laser irradiation can be carried out by any suitable process in accordance with conventional methods depending on the selected means.

The shape of the beer hole, that is, the shape of the opening's contour when viewed in the direction of extension, is not particularly limited, but it is generally considered to be circular (or nearly circular).

After via hole formation, a desmearing process, also known as a desmearing process, may be performed to remove smear from within the via holes. If the conductive layer is formed by a plating process (described later), a wet desmearing treatment may be performed on the via holes. If the conductive layer is formed by a sputtering process, a dry desmearing process, such as a plasma treatment, may be performed. Furthermore, the desmearing process may also serve as a roughening treatment.

Before forming the conductive layer, roughening treatment may be performed on the via holes and insulating layer. Commonly known procedures and conditions can be used for the roughening treatment. Examples of dry roughening treatments include plasma treatment, while examples of wet roughening treatments include swelling with a swelling solution, roughening with an oxidizing agent, and neutralization with a neutralizing solution, performed in that order.

The surface roughness (Ra) of the insulating layer surface after roughening treatment is preferably 350 nm or more, more preferably 400 nm or more, and even more preferably 450 nm or more. The upper limit is preferably 700 nm or less, more preferably 650 nm or less, and even more preferably 600 nm or less. The surface roughness (Ra) can be measured, for example, using a non-contact surface roughness meter.

After forming via holes, a conductor layer is formed. The conductor material constituting the conductor layer is not particularly limited, and the conductor layer can be formed by any suitable conventionally known method such as plating, sputtering, or vapor deposition; formation by plating is preferred. A preferred embodiment involves plating the surface of the insulating layer using conventionally known techniques such as semi-additive or fully additive methods to form a conductor layer having a desired wiring pattern. The conductor layer may be a single-layer structure or a multi-layer structure consisting of two or more single-metal or alloy layers made of different types of metals or alloys.

In detail, a plating seed layer is formed on the surface of the insulating layer by electroless plating. Next, a mask pattern is formed on the formed plating seed layer, exposing a portion of the plating seed layer corresponding to the desired wiring pattern. An electroplated layer is then formed on the exposed plating seed layer by electroplating. At this time, via holes may be filled by electroplating to form filled vias along with the formation of the electroplated layer. After forming the electroplated layer, the mask pattern is removed. Then, the unnecessary plating seed layer can be removed by etching or other means to form a conductor layer with the desired wiring pattern. The dry film used to form the mask pattern when forming the conductor layer is the same as the dry film described above.

The conductor layer may include not only linear wiring but also electrode pads (lands) on which external terminals may be mounted. Alternatively, the conductor layer may consist solely of electrode pads.

Furthermore, the conductive layer may be formed by forming an electroplating layer and filled vias without using a mask pattern after the plating seed layer has been formed, and then performing patterning by etching.

When employing a process of polishing or grinding the insulating layer to expose the wiring layer and connect the wiring layers, the method of polishing or grinding the insulating layer is not particularly limited as long as it can expose the wiring layer and the polished or ground surface is horizontal. Conventional known polishing or grinding methods can be applied, such as chemical mechanical polishing using a chemical mechanical polishing apparatus, mechanical polishing using a buff, or surface grinding using a rotating grinding wheel. Similar to the process of forming via holes in the insulating layer and forming a conductor layer to connect the wiring layers, a smear removal process and a roughening process may be performed, or a conductor layer may be formed. Furthermore, it is not necessary to expose all wiring layers; only a portion of the wiring layers may be exposed.

<Step (4)>
Step (4) is a step of removing the substrate and forming the circuit board of the present invention. The method of removing the substrate is not particularly limited. In one preferred embodiment, the substrate is peeled off from the circuit board at the interface between the first and second metal layers, and the second metal layer is etched off with, for example, an aqueous copper chloride solution. If necessary, the substrate may be peeled off while the conductive layer is protected with a protective film.

[Semiconductor Chip Packages]
The semiconductor chip package of the present invention includes a cured product of the curable composition of the present invention.

In one embodiment, the semiconductor chip package of the present invention is a semiconductor chip package in which a semiconductor chip is mounted on the circuit board. The semiconductor chip package can be manufactured by bonding the semiconductor chip to the circuit board.

As long as the terminal electrodes of the semiconductor chip are conductively connected to the circuit wiring of the circuit board, the bonding conditions are not particularly limited, and known conditions used in flip-chip mounting of semiconductor chips may be used. Alternatively, the semiconductor chip and the circuit board may be bonded via an insulating adhesive.

A preferred embodiment involves crimping a semiconductor chip onto a circuit board. For example, the crimping conditions can be set as follows: a crimping temperature in the range of 120°C to 240°C (preferably 130°C to 200°C, more preferably 140°C to 180°C), and a crimping time in the range of 1 second to 60 seconds (preferably 5 seconds to 30 seconds).

Another preferred embodiment involves reflow bonding the semiconductor chip to the circuit board. The reflow temperature can be, for example, in the range of 120°C to 300°C.

After bonding the semiconductor chip to the circuit board, it is also possible to obtain a semiconductor chip package by, for example, filling the semiconductor chip with a mold underfill material. The method of filling with mold underfill material can be carried out by known methods. A curable composition may be used as the mold underfill material.

In another embodiment (hereinafter also referred to as the "second embodiment"), the semiconductor chip package of the present invention can be manufactured, for example, by a method including the following steps (A) to (F) using the curable composition of the present invention. The curable composition of the present invention may be used to form the sealing layer in step (C) or the redistribution layer in step (E). An example of forming a sealing layer or a redistribution layer using the curable composition is shown below, but the techniques for forming sealing layers and redistribution layers of semiconductor chip packages are well known, and those skilled in the art can manufacture semiconductor chip packages using the curable composition of the present invention in accordance with known techniques.
(A) A step of laminating a temporary fixing film onto the substrate,
(B) A step of temporarily fixing the semiconductor chip onto a temporary fixing film,
(C) A process of forming a sealing layer on a semiconductor chip.
(D) Steps to peel off the substrate and temporary fixing film from the semiconductor chip.
(E) A step of forming a redistribution layer as an insulating layer on the surface from which the substrate and temporary fixing film of the semiconductor chip have been peeled off, and (F) A step of forming a redistribution layer as a conductive layer on the redistribution layer.

<Process (A)>
The material used for the substrate is not particularly limited. Examples of substrates include silicon wafers, glass wafers, glass substrates, metal substrates such as copper, titanium, stainless steel, and cold-rolled steel sheets (SPCC), substrates made by impregnating glass fibers with epoxy resin and heat-curing treatment (e.g., FR-4 substrates), and substrates made of bismaleimidotriazine resin (BT resin).

The temporary fixing film can be peeled off from the semiconductor chip in process (D) and can temporarily fix the semiconductor chip; however, the material is not particularly limited. Commercially available temporary fixing films can be used. Examples of commercially available products include Riva Alpha manufactured by Nitto Denko Corporation.

<Process (B)>
The semiconductor chip is temporarily fixed onto a temporary fixing film such that its electrode pad surface is in contact with the temporary fixing film. Temporary fixing of the semiconductor chip can be performed using known equipment such as a flip-chip bonder or die bonder. The layout and number of semiconductor chips can be appropriately set according to the shape and size of the temporary fixing film, the target production quantity of the semiconductor package, etc. For example, they can be temporarily fixed in a matrix arrangement of multiple rows and multiple columns.

<Step (C)>
The curable composition of the present invention is applied to a semiconductor chip and cured (e.g., by thermal curing) to form a sealing layer. Alternatively, the curable composition of the present invention may be laminated on a semiconductor chip in the form of a sheet containing the curable composition described above and cured (e.g., by thermal curing) to form a sealing layer.

Furthermore, when used in the form of a sheet containing the curable composition, the lamination of the semiconductor chip and the sheet containing the curable composition can be performed by removing the protective film from the sheet containing the curable composition as needed, and then heat-pressing the sheet containing the curable composition onto the semiconductor chip from the support side. The lamination of the semiconductor chip and the sheet containing the curable composition may also be carried out by a vacuum lamination method, and the lamination conditions are the same as those in step (2) of the circuit board manufacturing method.

After lamination, the curable composition is heat-cured to form a sealing layer. The heat-curing conditions are the same as those in step (2) of the circuit board manufacturing method.

The support for the sheet containing the curable composition may be peeled off after the sheet has been laminated onto the semiconductor chip and heat-cured, or the support may be peeled off before the sheet containing the curable composition has been laminated onto the semiconductor chip.

When applying the curable composition of the present invention to form a sealing layer, the application conditions are the same as those used to form the curable composition layer in the sheet containing the curable composition of the present invention.

<Step (D)>
The method for peeling off the substrate and the temporary fixing film can be appropriately changed depending on the material of the temporary fixing film, etc. Examples include a method of peeling off the temporary fixing film by heating and foaming (or expanding) it, and a method of peeling off the temporary fixing film by irradiating it with ultraviolet light from the substrate side to reduce its adhesive strength.

In the method of peeling off a temporary fixing film by heating and foaming (or expanding) it, the heating conditions are usually 100 to 250°C for 1 to 90 seconds or 5 to 15 minutes. In the method of peeling off a temporary fixing film by irradiating it with ultraviolet light from the substrate side to reduce its adhesive strength, the amount of ultraviolet light irradiated is usually 10 mJ/ ^cm² to 1000 mJ/ ^cm² .

<Step (E)>
The material used to form the redistribution layer (insulating layer) is not particularly limited as long as it has insulating properties when the redistribution layer (insulating layer) is formed. From the viewpoint of ease of manufacturing semiconductor chip packages, photosensitive resins and thermosetting resins are preferred. The redistribution layer may also be formed using the curable composition of the present invention.

After forming the redistribution layer, via holes may be formed in the redistribution layer to connect the semiconductor chip to the conductor layer described later. The via holes may be formed by known methods depending on the material of the redistribution layer.

<Process (F)>
The material of the conductor layer formed on the rewiring layer is not particularly limited. In a preferred embodiment, the conductor layer is the same as the conductor material used for the wiring layer in the circuit board. The conductor material is as described above.

The conductive layer may be a single-layer structure, or it may be a multi-layer structure consisting of two or more single-metal or alloy layers made of different types of metals or alloys. When the conductive layer is a multi-layer structure, the layer in contact with the insulating layer is preferably a single-metal layer of chromium, zinc, or titanium, or an alloy layer of nickel-chromium alloy.

The thickness of the conductor layer depends on the desired semiconductor chip package design, but is generally 1 μm to 35 μm, preferably 1 μm to 20 μm.

In one embodiment, the conductor layer may be formed by plating. For example, a conductor layer having a desired wiring pattern can be formed by plating the surface of the rewiring layer using conventionally known techniques such as the semi-additive method or the fully additive method. From the viewpoint of ease of manufacturing, it is preferable to form it by the semi-additive method. An example of forming the conductor layer by the semi-additive method is shown below.

First, a plating seed layer is formed on the surface of the rewiring layer by electroless plating. Next, a mask pattern is formed on the formed plating seed layer, exposing a portion of the plating seed layer corresponding to the desired wiring pattern. After forming a metal layer on the exposed plating seed layer by electroplating, the mask pattern is removed. Then, the unnecessary plating seed layer is removed by etching or other means to form a conductor layer (rewiring layer) with the desired wiring pattern.

Furthermore, steps (E) and (F) may be repeated to alternately stack the conductor layer (rewiring layer) and the rewiring formation layer (insulating layer) (build-up).

In manufacturing semiconductor chip packages, the following steps may be further performed: (G) forming a solder resist layer on a conductor layer (redistribution layer), (H) forming bumps, and (I) dicing multiple semiconductor chip packages into individual semiconductor chip packages. These steps may be carried out according to various methods known to those skilled in the art for the manufacture of semiconductor chip packages.

The second embodiment described above is an example of a manufacturing method in which a semiconductor chip is first provided and a redistribution layer is formed on its electrode pad surface, i.e., the Chip- ^1st method. In addition to the Chip-1st method described above, the semiconductor chip package of the present invention may also be manufactured by a method in which a redistribution layer is first provided, and a semiconductor chip is provided on the redistribution layer in a state in which its electrode pad surface can be electrically connected to the redistribution layer, and then sealed, i.e., the Redistribution Layer 1st (RDL- ^1st ) method.

By forming a sealing layer, a redistribution layer, etc., using the curable composition of the present invention, the semiconductor chip package of the present invention can be either a fan-in type package or a fan-out type package. The curable composition of the present invention can be applied to both fan-out type panel-level packages (FOLP) and fan-out type wafer-level packages (FOWLP).

[Semiconductor equipment]
Semiconductor devices on which the semiconductor chip package of the present invention will be mounted include various semiconductor devices used in electrical products (e.g., computers, mobile phones, smartphones, tablet devices, wearable devices, digital cameras, camera modules, medical equipment, and televisions, etc.) and vehicles (e.g., motorcycles, automobiles, trains, ships, and aircraft, etc.).

[Electronic components]
The electronic component of the present invention comprises an electronic component, a cured product of the curable composition of the present invention provided on the electronic component, and a heat dissipation member mounted on the cured product. Since the cured product of the curable composition has high thermal conductivity and low elastic modulus, for example, by providing the cured product of the curable composition on the electronic component so as to adhere to the electronic component, and mounting the heat dissipation member on the cured product, the heat dissipation efficiency of the electronic component to the heat dissipation member is increased. The method for forming the cured product can be carried out by the same method as in step (2) described above. The electronic component of the present invention may have a plurality of heat dissipation members. In this case, it is preferable that the electronic component comprises an electronic component, a first cured product of the curable composition of the present invention provided on the electronic component, a first heat dissipation member mounted on the first cured product, a second cured product of the curable composition of the present invention provided on the heat dissipation member, and a second heat dissipation member mounted on the second cured product. The first cured product and the second cured product may have the same components or different components. Furthermore, the first heat dissipation member and the second heat dissipation member may be the same heat dissipation member or they may be different heat dissipation members.

Examples of heat dissipation components include heat spreaders and heat sinks. Examples of electronic components include semiconductor chip packages, power semiconductors, and LED packages. Examples of electronic materials include circuit boards, semiconductor chip packages, and semiconductor devices.

The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples. In the following description, "parts" and "%" refer to "parts by mass" and "mass%", respectively, unless otherwise specified.

[Preparation of curable compositions]
The curable compositions for Examples 1-7 and Comparative Examples 1-3 were prepared by mixing each component according to the formulation shown in the table below. Specifically, the amounts (parts by mass) shown in the table below were weighed into a dedicated plastic container. Then, using a rotating/revolving vacuum mixer, Awatori Rentaro (manufactured by Shinky Co., Ltd.; ARE-310), the mixture was thoroughly mixed at 2000 rpm at room temperature, and degassed for a further minute to obtain the curable composition. In the table, the amount of each component represents parts by mass.

The abbreviations used in the table are as follows:
(A) Component PT-110A: Boron nitride filler (average particle size 33 μm), manufactured by MOMENTIVE Inc.
(B) Component SQ-502-8: Manufactured by Arakawa Chemical Industries, Ltd., epoxy group-containing silsesquioxane compound (containing 16.5% isopropyl alcohol and 3.5% toluene), epoxy equivalent approximately 276 g/eq.
SQ-107: Manufactured by Arakawa Chemical Industries, Ltd., a thiol group-containing silsesquioxane compound (containing 24.4% ethylene glycol dimethyl ether and 4% toluene), with a thiol group equivalent of approximately 206 g/eq.
(C) Ingredients/TMTP: Manufactured by Yodo Chemical Co., Ltd., trimethylolpropane tristhiopropionate, thiol group equivalent 140 g/eq.
PEMP: Manufactured by SC Organic Chemicals, pentaerythritol tetrakis(3-mercaptopropionate), thiol group equivalent 122 g/eq.
PE-1: Manufactured by Showa Denko Corporation, pentaerythritol tetrakis(3-mercaptobutyrate), thiol group equivalent 135 g/eq.
(D) Component ZX1059: Manufactured by Nippon Steel Corporation, bisphenol-type epoxy resin (a 1:1 mixture of bisphenol A and bisphenol F), epoxy equivalent approximately 165 g/eq.
(E) Component 1B2PZ: Manufactured by Shikoku Chemicals, Inc., 1-benzyl-2-phenylimidazole (F) Component HN-2200 (acid anhydride-based curing agent): Manufactured by Showa Denko Materials, Inc., 3 or 4-methyl-1,2,3,6-tetrahydrophthalic anhydride, molecular weight 166, acid anhydride group equivalent 179 g/eq.

[Measurement and evaluation of thermal conductivity]
Each curable composition was placed in a designated container and heat-cured in a heat-circulating oven at 120°C for 90 minutes to produce cylindrical cured objects with a thickness of 10 mm and a diameter of φ36 mm. The thermal conductivity of the obtained cylindrical cured objects was measured using the hot-disk method with a Kyoto Electronics Manufacturing Co., Ltd. "TPS-2500" under constant temperature conditions of 25°C and 40% RH. The measured thermal conductivity was also evaluated according to the following criteria.
○: Thermal conductivity of 1.40 W/mK or higher ×: Thermal conductivity of less than 1.40 W/mK

[Measurement and evaluation of elastic modulus]
Each curable composition was applied to a release PET film (NS-80A: manufactured by Toray Industries, Inc.) using a bar coat, and heated and cured at 120°C for 90 minutes to obtain a cured product. The resulting cured product, with a thickness of 100 μm, was punched out using a dumbbell (product name "Super Dumbbell Cutter (model: SDMK-5889-01)," manufactured by Dumbbell Co., Ltd.) to prepare test specimens for tensile strength measurement. The PET film was peeled off the test specimens. Tensile tests were performed using a Tensilon universal tester (manufactured by Orientec, Inc., RTM-500) under the conditions of a temperature of 25°C, humidity of 60%, and a tensile speed of 50 mm/min. The measured modulus of elasticity was also evaluated according to the following criteria.
○: Elastic modulus less than 4000 MPa ×: Elastic modulus 4000 MPa or more

Claims (10)

(A) Thermally conductive filler,
A curable composition containing (B) a silsesquioxane compound and (C) a liquid polythiol compound,
(C) The components are trimethylolpropane tris(3-mercaptopropionate), pentaerythritol tetrakis(3-mercaptopropionate), dipentaerythritol hexakis(3-mercaptopropionate), tris-[(3-mercaptopropionyloxy)-ethyl]-isocyanurate, tris(3-mercaptopropyl)isocyanurate, octyl thioglycolate, ethylene glycol bisthioglycolate, trimethylolpropane tristhioglycolate, pentaerythritol tetrakisthioglycolate, 3-mercaptoprop Selected from pionic acid, pentaerythritol tetrakis(3-mercaptobutyrate), 1,4-bis(3-mercaptobutyryloxy)butane, 1,3,5-tris(3-mercaptobutyryloxyethyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, trimethylolpropane tris(3-mercaptobutyrate), trimethylolethane tris(3-mercaptobutyrate), 1,3,4,6-tetrakis(2-mercaptoethyl)glycoluryl, and 4,4'-isopropylidene bis[(3-mercaptopropoxy)benzene],
If component (B) does not contain an epoxy group-containing silsesquioxane compound having an epoxy group, then component (B) contains a thiol group-containing silsesquioxane compound having a thiol group, and further contains (D) epoxy resin.
If component (B) contains an epoxy group-containing silsesquioxane compound, the curable composition may or may not contain (D) epoxy resin.
A curable composition in which component (D) is selected from bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, bisphenol AF type epoxy resin, dicyclopentadiene type epoxy resin, trisphenol type epoxy resin, naphthol novolac type epoxy resin, phenol novolac type epoxy resin, tert-butyl-catechol type epoxy resin, naphthalene type epoxy resin, naphthol type epoxy resin, anthracene type epoxy resin, glycidylamine type epoxy resin, glycidyl ester type epoxy resin, cresol novolac type epoxy resin, biphenyl type epoxy resin, linear aliphatic epoxy resin, epoxy resin having a butadiene structure, alicyclic epoxy resin, heterocyclic epoxy resin, spiro ring-containing epoxy resin, cyclohexanedimethanol type epoxy resin, naphthylene ether type epoxy resin, and trimethylol type epoxy resin . The curable composition according to claim 1, wherein the content of component (A) is 20% by mass or more and 80% by mass or less, when the nonvolatile components in the curable composition are considered to be 100% by mass. The curable composition according to claim 1 or 2, wherein the curable composition contains an epoxy group-containing silsesquioxane compound as component (B) and further contains an epoxy resin (D), and the content of component (B) is 5% by mass or more and 65% by mass or less, when the non-volatile components in the curable composition are considered to be 100% by mass. The curable composition according to claim 1 or 2, wherein the curable composition contains an epoxy group-containing silsesquioxane compound as component (B) and does not contain epoxy resin (D), and the content of component (B) is 10% by mass or more and 65% by mass or less, when the non-volatile components in the curable composition are considered to be 100% by mass. The curable composition according to any one of claims 1 to 4, wherein the content of component (C) is 5% by mass or more and 30% by mass or less, when the non-volatile components in the curable composition are considered to be 100% by mass. (C) The curable composition according to any one of claims 1 to 5, wherein component C contains two or more thiol groups in one molecule. A sheet containing a curable composition, comprising a support and a curable composition layer provided on the support, the layer containing the curable composition described in any one of claims 1 to 6. A circuit board comprising an insulating layer formed from a cured product of a curable composition according to any one of claims 1 to 6. A semiconductor chip package comprising a cured product of a curable composition according to any one of claims 1 to 6. An electronic component comprising: an electronic component; a cured product of a curable composition according to any one of claims 1 to 6 provided on the electronic component; and a heat dissipation member mounted on the cured product.