TW201319158A - Resin composition, resin sheet, resin sheet with metal foil, cured resin sheet, structure, and semiconductor device for power or luminous source - Google Patents

Abstract

A resin composition according to the invention contains: an epoxy resin including a multifunctional epoxy resin; a curing agent including a novolac resin having a structural unit represented by the following general formula (I); and an inorganic filler including a nitride particle. In the general formula (I), R1 and R2 respectively and independently represents a hydrogen atom or a methyl group, m represents from 1.5 to 2.5 at the average, and n represents from 1 to 15 at the average.

Description

Resin composition, resin sheet, resin sheet with metal foil, resin cured sheet, structure, and semiconductor element for power or light source

The present invention relates to a resin composition, a resin sheet, a resin sheet with a metal foil, a cured resin sheet, a structure, and a semiconductor element for power or light source.

With the progress of miniaturization, large capacity, high performance, and the like of electronic devices using semiconductors, the amount of heat generated from semiconductors that have been subjected to high-density packaging is increasing. For example, in the stable operation of the semiconductor device used for the control of the central processing unit of the computer or the motor of the electric vehicle, the heat sink or the heat dissipating fin is indispensable for heat dissipation, and a material capable of having both insulation and thermal conductivity is required. As a member that bonds a semiconductor device to a heat sink or the like.

Further, an organic material is generally widely used for an insulating material such as a printed circuit board for packaging a semiconductor device or the like. Although these organic materials have high insulating properties, they have low thermal conductivity and contribute little to heat dissipation of semiconductor devices and the like. On the other hand, an inorganic material such as an inorganic ceramic may be used for heat dissipation of a semiconductor device or the like. Although these inorganic materials have high thermal conductivity, insulating properties are difficult to say as compared with organic materials, and materials requiring high insulating properties and thermal conductivity are required.

In the above description, the method of providing a thermosetting resin cured product having excellent thermal conductivity as a material capable of simultaneously providing insulation and thermal conductivity is described in the specification of the International Publication No. 02/094905. High thermal conductivity is achieved by forming an anisotropic structure in the resin. The thermal conductivity of the cured epoxy resin forming the anisotropic structure by the mesogen skeleton It was determined by the plate comparison method (fixed method) and was 0.68 W/m. K~1.05 W/m. K.

Further, JP-A-2008-13759 discloses a composite material obtained by mixing an epoxy resin containing a liquid crystal skeleton and an alumina having an inorganic conductivity as a high inorganic filler. For example, it is known that a cured product comprising a combination of a usual bisphenol A type epoxy resin and an alumina filler has a thermal conductivity of 3.8 W/m in a xenon flash method. K, 4.5 W/m can be achieved in the temperature wave thermal analysis method. K (refer to Japanese Patent Laid-Open Publication No. 2008-13759). It is also known that a cured product comprising a combination of an epoxy resin containing a liquid crystal cell and an amine hardener or alumina has a thermal conductivity of 9.4 W/m in a xenon flash lamp method. K, in the temperature wave thermal analysis method can reach 10.4 W / m. K.

However, the cured product described in the specification of International Publication No. 02/094905 cannot obtain sufficient thermal conductivity in practical use. In the cured product described in Japanese Laid-Open Patent Publication No. 2008-13759, since an amine-based curing agent is used, the cured product is inferior in flexibility and the semi-cured sheet is easily broken.

An object of the present invention is to provide a resin composition which is flexible before curing and which can achieve high thermal conductivity after curing, a resin sheet comprising the resin composition, a resin sheet with a metal foil, a cured resin sheet, and a structure. A semiconductor component for power or light source.

The first aspect of the present invention includes an epoxy resin containing a polyfunctional epoxy resin, a curing agent containing a novolac resin having a structural unit represented by the following general formula (I), and an inorganic filler containing nitride particles. . In addition, The polyfunctionality in the present invention means that the number of functional groups in one molecule is 3 or more.

In the formula (I), R ¹ and R ² each independently represent a hydrogen atom or a methyl group, m represents an average value of 1.5 to 2.5, and n represents an average value of 1 to 15.

It is preferred that the above polyfunctional epoxy resin does not substantially have a liquid crystal skeleton. Further, it is preferred that the polyfunctional epoxy resin has a branched structure and a reactive epoxy group in a side chain.

The resin cured product obtained by curing the resin composition from which the above-mentioned inorganic filler is removed is preferably a crosslinking density of 5 mmol/cm ³ or more.

It is preferable that the resin composition contains 50% by volume to 85% by volume of the above inorganic filler.

Further, the resin composition preferably contains 20% by mass or more of the above polyfunctional epoxy resin in all the epoxy resins. Further, the polyfunctional epoxy resin preferably has a branched structure from the viewpoint of the crosslinking density of the cured resin and the glass transition temperature, and specifically, is preferably selected from a triphenylmethane type epoxy resin. At least one of a tetraphenylethane type epoxy resin, a dihydroxy novolac type epoxy resin, and a glycidylamine type epoxy resin. In particular, it is more preferably a triphenyl group selected from a repeating unit containing a branched structure. At least one of a methane type epoxy resin and a dihydroxy novolac type epoxy resin.

The polyfunctional epoxy resin preferably further contains a liquid or semi-solid epoxy resin from the viewpoint of lowering the softening point of the resin composition, and the liquid or semi-solid epoxy resin is preferably selected from the group consisting of Phenolic A type epoxy resin, bisphenol F type epoxy resin, bisphenol A type and F type mixed epoxy resin, bisphenol F type novolak epoxy resin, naphthalene glycol type epoxy resin and glycidylamine type ring At least one of oxygen resins. Further, in the present invention, the liquid state means that the melting point or the softening point is less than room temperature (25 ° C), and the semi-solid shape means that the melting point or the softening point is 40 ° C or less.

It is preferable that the hardener contains at least one selected from the group consisting of mononuclear dihydroxybenzenes in an amount of 20% by mass to 70% by mass.

More preferably, the inorganic filler contains 50% by volume to 95% by volume of the above nitride particles. Further, it is preferable that the nitride particles are aggregates or pulverized materials of hexagonal boron nitride, and the ratio of the major axis to the minor axis is 2 or less.

It is preferred that the above resin composition further contains a coupling agent. It is also preferred to further contain a dispersing agent.

A second aspect of the present invention is a resin sheet which is an uncured or semi-cured material of the resin composition.

According to a third aspect of the invention, there is provided a metal foil-attached resin sheet comprising the resin sheet and a metal foil.

According to a fourth aspect of the invention, there is provided a cured resin sheet which is a cured product of the resin composition. Preferably, the cured resin sheet has a thermal conductivity of 10 W/m in the thickness direction. K or more.

According to a fifth aspect of the invention, there is provided a structure comprising: the resin sheet or the cured resin sheet; and a metal plate provided in contact with one surface or both surfaces of the resin sheet or the resin cured sheet.

According to a sixth aspect of the invention, there is provided a semiconductor element for power or light source, comprising: the resin sheet, the metal foil-attached resin sheet, the resin cured sheet, or the structure.

According to the present invention, it is possible to provide a resin composition which is flexible before curing and which can achieve high thermal conductivity after curing, a resin sheet which is formed using the resin composition, a resin sheet with a metal foil, a cured resin sheet, and a structure. Semiconductor components for body and power or light source.

In the present specification, "~" indicates a range including the numerical values described before and after the minimum value and the maximum value.

In addition, the term "step" in this specification is not only an independent step, but also can be included in the present term if the desired effect of the step can be achieved when it is not clearly distinguishable from other steps.

Further, the amount of each component in the composition in the present specification is a plurality of substances suitable for each component in the composition, and unless otherwise specified, means the total amount of the plurality of substances present in the composition.

<Resin composition>

The resin composition of the present invention contains an epoxy resin containing a polyfunctional epoxy resin, a hardener containing a novolak resin having a structural unit represented by the following general formula (I), and an inorganic filler containing nitride particles. . borrow According to this configuration, it is possible to form an insulating resin cured product which is soft before curing and excellent in thermal conductivity after curing.

In the formula (I), R ¹ and R ² each independently represent a hydrogen atom or a methyl group, m represents an average value of 1.5 to 2.5, and n represents an average value of 1 to 15.

Generally, the thermal conductivity in the cured epoxy resin obtained from epoxy resin and hardener is dominated by phonons with a thermal conductivity of 0.15 W/m. K~0.22 W/m. K or so. The reason for this is that the cured epoxy resin is amorphous and does not have a structure called an ordered structure; and the covalent bond which makes the lattice vibration have coordination is less than that of metal or ceramic. Therefore, the scattering of phonons in the hardened epoxy resin is large, and the average free path of the phonons is, for example, shorter than 0.1 nm of the crystalline erbium oxide, and the cured epoxy resin is about 0.1 nm and short, resulting in low thermal conductivity. .

It is considered that the formation of an anisotropic structure by a liquid crystal cell as shown in the above-mentioned International Publication No. 02/094905 causes the crystal alignment of epoxy resin molecules to suppress static scattering of phonons. And improve the thermal conductivity. However, the epoxy resin monomer containing a liquid crystal cell is often highly crystalline and has low solubility in a solvent, and special conditions are sometimes required when operating in the form of a resin composition. Therefore, there is a need for an epoxy resin monomer which does not contain a liquid crystal cell and is easily dissolved in a solvent.

The present inventors have found that in order to increase the thermal conductivity, the number of covalent bonds which coordinate the lattice vibration is increased and the dynamic phonon scattering is reduced, which is effective for improving the thermal conductivity, and completed the present invention. A structure having a large number of covalent bonds that makes the lattice vibration coordinated can be obtained by shortening the distance between the branch points of the resin skeleton to form a fine mesh. That is, in the thermosetting resin, a structure having a small molecular weight between crosslinking points is preferred. According to this configuration, the crosslinking density is increased, and even when the anisotropic structure is not formed in the cured epoxy resin substantially containing no liquid crystal skeleton, the thermal conductivity is improved.

In the resin composition after hardening, in order to shorten the distance between the branching points of the resin skeleton, a fine mesh is formed. In the present invention, specifically, a polyfunctional epoxy resin is used as the epoxy resin, and the above formula ( The novolak resin of the structural unit shown in I) is used as a hardener, and nitride particles are used as an inorganic filler.

The crosslinking density of the cured resin obtained by curing the resin composition containing no inorganic filler is preferably 5 mmol/cm ³ or more, more preferably 7 mmol/cm ³ or more, and particularly preferably 10 mmol/cm ^{3 .} the above.

The upper limit of the crosslinking density is not particularly limited, and is preferably 100 mmol/cm ³ or less, more preferably 70 mmol/cm ³ or less, and particularly preferably 50 mmol/% from the viewpoint of brittleness of the cured resin. Below cm ³ .

(epoxy resin)

The resin composition of the present invention contains a polyfunctional epoxy resin as an epoxy resin. The crosslinking density can be increased by including a polyfunctional epoxy resin. The multifunctional epoxy resin can be prepared from a polyfunctional epoxy resin monomer.

The polyfunctional epoxy resin may be a linear structure or a branched structure, and a polyfunctional epoxy resin having a branched structure and a side chain or a terminal having a reactive epoxy group may be crosslinked by the branch portion. Since the molecular weight between the joints is lowered and the crosslinking density is increased, it is preferred that the repeating unit particularly preferably a polymer contains a branched structure.

The epoxy resin having a repeating unit represented by the following formula (II) is compared with an epoxy resin having a repeating unit represented by the following formula (III), and the above-described form will be described.

The epoxy resin (epoxy equivalent 165 g/eq) having a repeating unit represented by the following formula (II) has a linear structure. In contrast, it is presumed that the branched structure (2) and the side chain portion derived from the branch include the reactive epoxy terminal group (1), and have the following formula equivalent to the epoxy equivalent of the above formula (II). In the epoxy resin (epoxy equivalent: 168 g/eq) of the repeating unit shown in (III), the crosslinked network becomes finer, and the crosslinking density can be expected to further increase.

[Chemical 4]

An epoxy resin having a repeating unit represented by the above formula (II) or (III) (reactive epoxy terminal group (1): para), and a general formula (I) having the present invention as a curing agent The structural formula of the reactants in the case where the novolak resin (m=2.0, n=2, bonding position of OH group: meta position, R ¹ and R ² = hydrogen atom) of the structural unit shown is ideally reacted, respectively Shown in formula (IV) and formula (V). It is also understood that the reactant of the formula (I) and the formula (III) having a branched structure are compared with the size of the mesh of the formula (I) and the formula (II), that is, the mesh of the following formula (IV). That is, the mesh of the following formula (V) becomes smaller. Therefore, the above polyfunctional epoxy resin is preferably an epoxy resin having a repeating unit represented by the above formula (III).

Further, in the epoxy resin skeleton containing a repeating unit, for example, in the above formula (III), assuming that a hydrogen atom and an epoxidized phenol are bonded to both ends, a skeleton of the following formula (VI) represented by n=1 may be contained.

Further, the above polyfunctional epoxy resin preferably has a small epoxy equivalent. A small epoxy equivalent means that the crosslinking density becomes high. Specifically, the epoxy equivalent is preferably 200 g/eq or less, more preferably 190 g/eq or less, and still more preferably 170 g/eq or less.

Further, the above polyfunctional epoxy resin preferably does not have a residue such as an alkyl group or a phenyl group which does not participate in crosslinking. It is generally believed that residues that do not participate in the reaction cause phonon reflection or conversion into thermal motion of the residue in phonon conduction resulting in phonon scattering.

Examples of the polyfunctional epoxy resin include a phenol novolak epoxy resin, a triphenylmethane epoxy resin, a tetraphenylethane epoxy resin, a dihydroxy novolac epoxy resin, and a glycidylamine type. The epoxy resin is preferably at least one selected from the group consisting of a triphenylmethane type epoxy resin, a tetraphenylethane type epoxy resin, a dihydroxy novolac type epoxy resin, and a glycidylamine type epoxy resin. From the viewpoint of the branched structure, it is more preferably at least one selected from the group consisting of a triphenylmethane type epoxy resin, a tetraphenylethane type epoxy resin, and a glycidylamine type epoxy resin, from the viewpoint of crosslinking density. In particular, a triphenylmethane type epoxy resin having a branched structure having a reactive terminal in a repeating unit is preferred. Further, in the hardener having a linear structure, from the viewpoint of crosslinking density, a dihydroxy novolac type epoxy resin having a reactive terminal of more than 1 in the repeating unit is preferred.

The polyfunctional epoxy resin is preferably contained in an amount of 20% by mass or more, more preferably 30% by mass or more, and particularly preferably 50% by mass or more based on the total epoxy resin.

The epoxy resin in the present invention preferably further comprises a liquid or semi-solid epoxy resin. The liquid and semi-solid epoxy resins have the effect of lowering the softening point of the resin composition. Among the liquid and semi-solid epoxy resins, a liquid epoxy resin is preferred from the viewpoint of lowering the effect of softening point.

Such a liquid or semi-solid epoxy resin is preferably, for example, selected from the group consisting of bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol A type and F type mixed epoxy resin, and bisphenol F phenol aldehyde. At least one of a varnish type epoxy resin, a naphthalene glycol type epoxy resin, and a glycidylamine type epoxy resin.

From the viewpoint of the effect of lowering the softening point, the liquid or semi-solid epoxy resin is preferably selected from the group consisting of bisphenol F type epoxy resins, bisphenol A type and F type mixed epoxy resins, and bisphenol F type. At least one of a novolak epoxy resin and a glycidylamine type epoxy resin.

The liquid or semi-solid shape epoxy resin is mostly a difunctional epoxy resin. When it is a difunctional epoxy resin monomer, since it does not have a branched structure, the crosslinking point is prolonged, so the crosslinking density is lowered, so that it should not be large. Add to. Therefore, the difunctional liquid or semi-solid epoxy resin preferably contains 50% by mass or less, more preferably 30% by mass or less, and particularly preferably 20% by mass or less.

From the above viewpoints, in order to suppress the decrease in the crosslinking density, it is preferred to use a bisphenol F type novolak epoxy resin or a glycidylamine type epoxy resin as a polyfunctional liquid or semi-solid epoxy resin. The polyfunctional liquid or semi-solid epoxy resin preferably contains 50% by mass or less, more preferably 30% by mass or less, and particularly preferably 20% by mass or less based on the total epoxy resin.

However, the mechanism or skeleton of the modification listed here is an example and is not intended to be limiting.

(hardener)

The resin composition of the present invention contains a novolac resin having a structural unit represented by the following formula (I) as a curing agent.

In the method for thinking about the molecular design, the novolac resin used as the curing agent of the present invention preferably has a structure in which the hydroxyl group equivalent is small as in the case of the epoxy resin. Thereby, the concentration of the hydroxyl group as a reaction group becomes high. another Further, it is preferable that the novolak resin is as receptive as possible to the residue which does not participate in crosslinking as much as the epoxy resin.

From the above viewpoints, the novolak resin used as the curing agent has a structural unit represented by the following formula (I).

In the formula (I), R ¹ and R ² each independently represent a hydrogen atom or a methyl group, m represents an average value of 1.5 to 2.5, and n represents an average value of 1 to 15.

In the novolak resin having a small hydroxyl group equivalent of the above-mentioned novolac resin and having a structural unit represented by the formula (I), since m has an average value of 1.5 or more, the hydroxyl group equivalent is appropriately small. On the other hand, when the hydroxyl equivalent is excessively small, the obtained cured product is liable to become brittle, so m is set to have an average value of 2.5 or less. Therefore, m in the above formula (I) has an average value of 1.5 to 2.5, more preferably 1.7 to 2.2.

Further, m which is a valence of a hydroxyl group may be an average value. For example, a monovalent phenol of a molar amount and a binary resorcinol may be used together as a raw material, and the average valence may be adjusted to 1.5 to 2.5.

In the novolak resin having the structural unit represented by the general formula (I), since R ¹ and R ² each independently represent a hydrogen atom or a methyl group, they have a structure which does not contain a residue which does not participate in crosslinking as much as possible.

In the viewpoint of the softening point of the novolak resin, the flow viscosity at the time of heating such as pressure bonding of the resin composition processed into a sheet form by the average value of n in the above formula (I) is from 1 to 15. From the viewpoint of viewpoint, it is preferable that n has an average value of 1 to 10.

Further, n is an average value, that is, a hardener skeleton containing a repeating unit includes, for example, a compound obtained by combining a hydrogen atom and a m-phenol (-Ph-(OH)m) at both ends in the formula (I). The compound of the following formula (VII) represented by n=1 or the compound of n exceeding 15 and n may have an average value of 1 to 15.

Further, it may be a case where the novolac resin is a mixture having a different molecular weight by synthesis, and n is obtained by an average value of 1 to 15, or a novolak resin having a different molecular weight may be mixed to adjust n to an average value of 1 ~15 situation.

The aldehyde and the ketone used for the synthesis of the novolak resin are preferably formaldehyde in view of the hydroxyl group equivalent, but acetaldehyde may be selected in consideration of heat resistance, or acetone may be selected in terms of easiness of synthesis. . Further, in order to have both a hydroxyl group equivalent and heat resistance, at least two or more of formaldehyde, acetaldehyde, and acetone may be used in combination.

According to the above, the above novolak resin is preferably used as A phenolic resin having a phenolic hydroxyl group having a binary phenolic hydroxyl group and a phenol varnish resin obtained by condensing formaldehyde, acetaldehyde or acetone as an aldehyde.

In addition, the novolak resin having the structural unit represented by the above formula (I) may further have another structure if it has a structural unit represented by the formula (I) in the molecule. For the purpose of the modification, for example, a condensed ring structure of a phenol compound such as an alkylphenol or an aralkyl skeleton or a xanthene skeleton may be present in the molecule as a skeleton derived from a phenol compound. Further, the novolak resin having the structural unit represented by the above formula (I) may be a random polymer or a block copolymer.

The content of the structural unit represented by the formula (I) in the molecular group of the novolak resin having the structural unit represented by the above formula (I) is preferably 50% by mass or more, and more preferably 70% by mass or more. More preferably, it is 80% by mass or more.

The hydroxyl equivalent of the novolak resin having the structural unit represented by the above formula (I) is preferably 100 g/eq or less, more preferably 80 g/eq or less, and more preferably from the viewpoint of crosslinking density. Below 70 g/eq.

The curing agent may further contain another novolak resin or a phenol compound (monomer) having a divalent or higher hydroxyl group on a mononuclear or an aralkyl resin. The higher the valence of the phenolic hydroxyl group, the smaller the hydroxyl group equivalent, but the crosslinking density tends to be too high, and the cured resin tends to become brittle. On the other hand, when the said hardening agent contains the said monomer, it can suppress that a cured resin is becoming brittle. The hardener containing the above monomer can be obtained by adding a monomer to the above-mentioned hardener or by leaving an unreacted monomer at the time of synthesis.

The monomer is preferably a phenol compound of a raw material used for synthesizing a novolak resin having a structural unit represented by the above formula (I), which may further comprise Contains other mononuclear phenolic compounds. Among such mononuclear phenol compounds, a mononuclear dihydric phenol compound (mononuclear dihydroxybenzene) is preferred. The mononuclear dihydroxybenzene may be used alone or in combination of two or more. When mononuclear dihydroxybenzene is added, it is preferable to reduce the softening point of the resin composition and to suppress the decrease in the crosslinking density to a low level.

The mononuclear dihydroxybenzene may, for example, be catechol, resorcin or hydroquinone, and among these three, resorcin which is difficult to oxidize is preferred. The skeletons listed here are examples and are not intended to be limiting.

The total content of at least one selected from the above-mentioned mononuclear dihydroxybenzene compounds is preferably from 20% by mass to 70% by mass, particularly in terms of thermal conductivity and softening point, in all the hardeners. The softness of the cured sheet and the crosslink density of the cured product are preferably from 30% by mass to 50% by mass. When the total content is within the above range, the number of functional groups that do not participate in crosslinking is suppressed, and dynamic scattering of phonons is suppressed, thereby suppressing a decrease in thermal conductivity of the cured resin.

The hydroxyl group equivalent of the entire curing agent is preferably 80 g/eq or less, more preferably 70 g/eq or less.

The content of the curing agent in the resin composition of the present invention is preferably adjusted such that the ratio of the hydroxyl group equivalent of the curing agent to the epoxy equivalent of the epoxy resin is close to 1. The closer the ratio of the above equivalents is to 1, the higher the crosslinking density is, and the more the effect of reducing the dynamic scattering of phonons is expected. Specifically, the above equivalent ratio (hydroxyl equivalent/epoxy equivalent) is preferably from 0.8 to 1.2, more preferably from 0.9 to 1.1, still more preferably from 0.95 to 1.05.

However, the imidazole hardening promotes the use of a chain polymerization which causes an epoxy group. When the agent or the amine-based hardening accelerator is used as the curing accelerator, since the unreacted epoxy group is hard to remain, the epoxy resin may be added in excess to the above-mentioned curing agent.

(inorganic filler)

The resin composition of the present invention contains nitride particles as an inorganic filler from the viewpoint of thermal conductivity. Examples of the nitride particles include particles of boron nitride, tantalum nitride, and aluminum nitride, and boron nitride is preferable. When the above-described boron nitride is used as the inorganic filler in the resin composition, the decrease in the glass transition temperature can be suppressed. The reason is considered as follows.

It is generally known that alumina, aluminum hydroxide or cerium oxide used as an inorganic filler has a hydroxyl group on the surface of the particles, and adsorbs a very small amount of water, and the adsorbed water hinders the hardening reaction to lower the crosslinking density. Therefore, an epoxy resin cured product containing an inorganic filler mainly composed of such alumina, aluminum hydroxide or cerium oxide has a glass transition temperature lower than that of an epoxy resin cured product containing no inorganic filler. In particular, in the epoxy resin system of the present invention which has a high crosslinking density, the influence is considered to be apparent.

On the other hand, boron nitride has a small polarity and does not have a hydroxyl group on the surface, so that it is difficult to adsorb water, and it does not cause hardening inhibition of the epoxy resin due to these hydroxyl groups or adsorbed water, so that an epoxy resin can be obtained. The body reacts with the hardening agent to impart a high crosslinking density. From this, it is considered that the glass transition temperature of the cured epoxy resin containing the inorganic filler containing boron nitride as the main component is equivalent to the cured epoxy resin containing no inorganic filler.

Further, whether or not the resin composition contains boron nitride can be, for example, energy dispersive X-ray analysis (energy dispersive X-ray analysis). It was confirmed by EDX) that, in particular, by combining with a scanning electron microscope (SEM), the distribution state of boron nitride in the cross section of the resin composition can be confirmed.

The crystal form of the boron nitride may be any of a hexagonal crystal, a cubic crystal, and a rhombohedral, and is preferably hexagonal in terms of easy control of the particle diameter. Further, two or more kinds of boron nitrides having different crystal forms may be used in combination.

The hexagonal boron nitride particles are preferably pulverized or agglomerated hexagonal boron nitride particles from the viewpoint of thermal conductivity and varnish viscosity. The particle shape of the hexagonal boron nitride may be a circular shape, a spherical shape, a scaly shape, or agglomerated particles. The shape of the high-filling particles is preferably a ratio of a long diameter to a short diameter of 3 or less, more preferably 2 or less. The shape of the circle or the sphere is more preferably spherical. In particular, the above-described hexagonal boron nitride which has been subjected to agglomeration processing has a large amount of gap and is easily deformed by the application of pressure, so that the filling rate of the inorganic filler is lowered even in consideration of the coating property of the varnish of the resin composition. It is also possible to increase the substantial filling ratio by compression after pressing or the like after coating. From the viewpoint of the ease of forming a heat-conducting passage by the contact of the inorganic filler having a high thermal conductivity, the shape of the particles is considered to be more round or scaly than the spherical contact point, but the above-mentioned filling property is taken into consideration. From the viewpoint of the thixotropic viscosity of the resin composition, spherical particles are preferred. In addition, the boron nitride particles having different particle shapes may be used alone or in combination of two or more.

Further, in view of the filling property of the inorganic filler, an inorganic filler other than boron nitride may be used in combination in order to fill the gap. If the inorganic filler is absolutely The inorganic compound of the rim is not particularly limited, and is preferably an inorganic filler having a high thermal conductivity. Specific examples of the inorganic filler other than boron nitride include cerium oxide, aluminum oxide, magnesium oxide, cerium oxide, aluminum nitride, cerium nitride, talc, mica, aluminum hydroxide, barium sulfate, and the like. Among them, from the viewpoint of thermal conductivity, alumina, aluminum nitride, and tantalum nitride are preferable.

The volume average particle diameter of the inorganic filler is not particularly limited, and is preferably 100 μm or less from the viewpoint of moldability, and more preferably 20 μm to 100 from the viewpoint of thermal conductivity and thixotropy of varnish. Μm, and in terms of insulation, it is preferably from 20 μm to 60 μm.

The inorganic filler may be an inorganic filler exhibiting a particle size distribution having a single peak, or an inorganic filler exhibiting a particle size distribution having two or more peaks. In the present invention, from the viewpoint of the filling ratio, an inorganic filler having a particle size distribution of two or more peaks is preferable.

In the above-described particle size distribution of the inorganic filler having a particle size distribution of two or more peaks, for example, when a particle size distribution having three peaks is exhibited, the small particle diameter preferably has an average particle diameter of 0.1 μm to 0.8 μm. The medium particle size particles preferably have an average particle diameter of from 1 μm to 8 μm, and the large particle size particles preferably have an average particle diameter of from 20 μm to 60 μm. By using this inorganic filler, the filling rate of the inorganic filler is further improved, and the thermal conductivity is further improved. From the viewpoint of the filling property, the large particle diameter is preferably an average particle diameter of 30 μm to 50 μm, and the medium particle diameter is preferably 1/4 to 1/10 of the average particle diameter of the large particle diameter, which is small. The particle diameter particles are preferably 1/4 to 1/10 of the average particle diameter of the medium particle diameter particles.

The above nitride particles are preferably used as the above-mentioned large-sized particles. Above The particle diameter particles or the small particle diameter particles may be nitride particles or other particles, and from the viewpoint of thermal conductivity and thixotropy of the varnish, alumina particles are preferred.

The content of the nitride particles in the total amount of the inorganic filler is preferably 50% by volume to 95% by volume from the viewpoint of moldability, and more preferably 60% by volume from the viewpoint of filling property. From the viewpoint of thermal conductivity, it is preferably from 65% by volume to 92% by volume.

In addition, the content of the inorganic filler in the resin composition of the present invention is preferably 50% by volume to 85% by volume from the viewpoint of moldability, and more preferably 60% by volume from the viewpoint of thermal conductivity. From 8% by volume, it is particularly preferably from 65% by volume to 75% by volume from the viewpoint of thixotropy of the varnish. When the content of the volume-based inorganic filler is within the above range, an insulating resin cured product having flexibility before curing and excellent thermal conductivity after curing can be formed.

Further, the volume-based content of the inorganic filler in the resin composition was measured in the following manner. First, the mass (Wc) of the resin composition at 25 ° C was measured, and the resin composition was calcined in air at 400 ° C for 2 hours, then calcined at 700 ° C for 3 hours, and the resin component was decomposed, burned, and removed. The mass (Wf) of the inorganic filler remaining at 25 °C. Next, the density (df) of the inorganic filler at 25 ° C was determined using an electronic hydrometer or a pycnometer. Next, the density (dc) of the resin composition at 25 ° C was measured in the same manner. Next, the volume (Vc) of the resin composition and the volume (Vf) of the remaining inorganic filler are determined, and the volume of the remaining inorganic filler is divided by the volume of the resin composition as shown in (Formula 1). The volume ratio (Vr) of the inorganic filler is taken out.

(Formula 1) Vc=Wc/dc Vf=Wf/df Vr=Vf/Vc

Vc: volume of resin composition (cm ³ ), Wc: mass of resin composition (g)

Dc: density of resin composition (g/cm ³ )

Vf: volume of inorganic filler (cm ³ ), Wf: mass of inorganic filler (g)

Df: density of inorganic filler (g/cm ³ )

Vr: volume ratio of inorganic filler

Further, when the inorganic filler is contained in the range of the volume ratio, the mass ratio is not particularly limited. Specifically, when the resin composition is 100 parts by mass, the inorganic filler may be contained in an amount of from 1 part by mass to 99 parts by mass, preferably from 50 parts by mass to 97 parts by mass, More preferably, it is 80 mass parts - 95 mass parts. When the content of the inorganic filler is within the above range, a higher thermal conductivity can be achieved.

(other ingredients)

The resin composition of the present invention may contain other components as needed in addition to the above components. Examples of other components include a curing accelerator, a coupling agent, a dispersing agent, an organic solvent, and a curing accelerator.

Especially in the above epoxy resin or the above hardener does not have a nitrogen atom In the case of having a basic component, it is preferred to add the above-mentioned curing accelerator from the viewpoint of sufficiently proceeding the curing reaction of the resin composition. In addition, when a nitrogen atom is contained in the molecule of the epoxy resin or the resin composition, the same effect as the amine-based curing accelerator can be expected. Therefore, the curing accelerator may not be added.

As the hardening accelerator, a phosphorus-based hardening accelerator such as triphenylphosphine (TPP manufactured by Behind Chemical Co., Ltd.) or PPQ (manufactured by Kitajhin Chemical Co., Ltd.) or a barium salt-based hardening accelerator such as TPP-MK (manufactured by Kitagawa Chemical Co., Ltd.); EMZ- can be used. Organic boron-based hardening accelerators such as K (Beixing Chemical Manufacturing Co., Ltd.); 2E4MZ (manufactured by Shikoku Chemical Industries, Ltd.), 2E4MZ-CN (manufactured by Shikoku Chemical Industries, Ltd.), 2PZ-CN (manufactured by Shikoku Chemical Industries, Ltd.), 2PHZ (Four Nations) Industrial manufacturing), such as imidazole-based hardening accelerator; amine-based hardening promotion such as triethylamine, N,N-dimethylaniline, 4-(N,N-dimethylamino)pyridine, and hexamethylenetetramine Agents, etc. In particular, since the phosphorus-based hardening accelerator or the onium-based hardening accelerator suppresses the homopolymerization of the epoxy resin monomer, it is preferred to carry out the reaction between the curing agent and the epoxy resin. In terms of blending design, when the epoxy equivalent/hydroxyl equivalent is more than 1, particularly 1.2 or more, an unreacted epoxy group is generated, which causes scattering of phonons which lowers the thermal conductivity as described above, and therefore, In this case, it is preferred to add an imidazole-based hardening accelerator or an amine-based hardening accelerator which can perform homopolymerization of an epoxy group.

Further, since the resin composition contains a coupling agent, the resin component containing the epoxy resin and the novolak resin is further improved in the bonding property with the inorganic filler, and a higher thermal conductivity and stronger adhesion can be achieved. .

The coupling agent is a functional group having a bond with a resin component, and The compound of the functional group bonded to the inorganic filler is not particularly limited, and a commonly used coupling agent can be used.

The functional group bonded to the above resin component may, for example, be an epoxy group, an amine group, a thiol group, a ureido group or an N-phenylamino group. From the viewpoint of storage stability, the above coupling agent is preferably a functional group having an epoxy group having a slow reaction rate or an N-phenylamino group.

Further, examples of the functional group to be bonded to the inorganic filler include an alkoxy group and a hydroxyl group. Examples of the coupling agent having such a functional group include a decane coupling agent having a dialkoxy decane or a trialkoxy decane. A titanate coupling agent having an alkoxy titanate.

Specific examples of the decane coupling agent include 3-glycidoxypropyltrimethoxydecane, 3-glycidoxypropyltriethoxydecane, and 3-glycidoxypropylmethyldimethacrylate. Oxydecane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxydecane, 3-aminopropyltriethoxydecane, 3-(2-aminoethyl)aminopropyltri Ethoxy decane, 3-aminopropyltrimethoxydecane, 3-(2-aminoethyl)aminopropyltrimethoxydecane, N-phenyl-3-aminopropyltrimethoxydecane , 3-mercaptotriethoxydecane, 3-ureidopropyltriethoxydecane, and the like.

Further, a decane coupling agent oligomer represented by SC-6000KS2 (manufactured by Hitachi Chemical Coated Sand Co., Ltd.) can also be used.

As the titanate coupling agent, a titanate coupling agent having an amine group at the end (PLENACT KR44 manufactured by Ajinomoto Fine-Techno) can be used.

These coupling agents may be used alone or in combination of two or more.

The content of the coupling agent in the resin composition is not particularly limited, and from the viewpoint of thermal conductivity, it is preferably 0.02% by mass to 0.83% by mass, and more preferably 0.04% by mass based on the total mass of the resin composition. ~0.42% by mass.

In addition, the content of the coupling agent is preferably 0.02% by mass to 1% by mass, and more preferably 0.05% by mass to 0.5% by mass, from the viewpoint of thermal conductivity and insulating properties with respect to the inorganic filler.

Further, when the resin composition contains a dispersant, the dispersibility of the inorganic filler in the resin component containing the epoxy resin and the novolak resin is further improved, and higher heat can be achieved by uniformly dispersing the inorganic filler. Conductivity and stronger adhesion.

The above dispersant can be appropriately selected from the dispersants which are usually used. For example, ED-113 (manufactured by Nanben Chemical Co., Ltd.), DISPERBYK-106 (manufactured by BYK-Chemie GmbH), and DISPERBYK-111 (BYK-Chemical Co., Ltd. (BYK-) Manufactured by Chemie GmbH), Ajisper PN-411 (manufactured by Ajinomoto Fine Chemicals), REB122-4 (manufactured by Hitachi Chemical Co., Ltd.), etc. Further, these dispersants may be used singly or in combination of two or more.

The content of the dispersant in the resin composition is not particularly limited, and is preferably from 0.01% by mass to 2% by mass, more preferably from 0.1% by mass to 1% by mass, based on the inorganic filler from the viewpoint of thermal conductivity. .

(Method for Producing Resin Composition)

The method for producing the resin composition of the present invention can be carried out by a usual method for producing a resin composition without any particular limitation. For example, it can be obtained by mixing an inorganic filler with a coupling agent as needed, dissolving or dispersing the epoxy resin and the curing agent in a suitable organic solvent, and further mixing other components such as a hardening accelerator added as needed. .

The organic solvent in which the hardener is dissolved or dispersed can be appropriately selected depending on the novolak resin or the like to be used. For example, an alcohol such as methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-propanol, cellosolve or methyl cellosolve may be preferably used; or methyl ethyl ketone a ketone solvent such as methyl isobutyl ketone, cyclohexanone or cyclopentanone; or an ester solvent such as butyl acetate or ethyl lactate; or an ether such as dibutyl ether, tetrahydrofuran or methyltetrahydrofuran; A nitrogen-based solvent such as carbamide or dimethylacetamide.

Further, a method of mixing an epoxy resin, a curing agent, an inorganic filler, or the like can be carried out by appropriately combining a disperser such as a usual agitator, a kneader, a three-roller, or a ball mill.

<Resin sheet>

The resin sheet of the present invention can be obtained by forming the above resin composition into a sheet shape. The resin sheet is composed of the resin composition described above, and is excellent in flexibility before curing and thermal conductivity after curing. Further, the resin sheet of the present invention may be an uncured material or a semi-cured material. Here, semi-hardening refers to a state generally referred to as a B-stage state, and means a viscosity of 10 ⁴ Pa with respect to a normal temperature (25 ° C.). s~10 ⁵ Pa. s, and the viscosity at 100 ° C is reduced to 10 ² Pa. s~10 ³ Pa. The state of s. Further, the viscosity can be measured by a torsional dynamic viscoelasticity measuring device or the like.

Further, the resin sheet of the present invention may be a resin sheet in which a resin layer containing the above resin composition is provided on a support. The film thickness of the above-mentioned resin layer can be appropriately selected depending on the purpose, for example, 50 μm to 500 μm, and is preferably thinner from the viewpoint of thermal resistance, and thicker is preferable from the viewpoint of insulation. The thickness can be both thermally and insulative, preferably from 70 μm to 300 μm, more preferably from 100 μm to 250 μm.

Examples of the support include an insulating support and a conductive support. Examples of the insulating support include a polytetrafluoroethylene film, a polyethylene terephthalate film, polybutylene terephthalate, polyethylene naphthalate, polyethylene film, polypropylene film, and polymethylation. A plastic film such as a pentene film, a polyamide film, or a polyimide film. As the conductive support, a metal or metal vapor-deposited plastic film such as copper foil or aluminum foil can also be used.

The insulating support may be subjected to surface treatment such as primer coating, ultraviolet (UV) treatment, corona discharge treatment, polishing treatment, etching treatment, and release treatment as needed. The conductive support may be subjected to a surface treatment such as primer coating, coupling treatment, UV treatment, etching treatment, or mold release treatment. In particular, when the adhesion between the metal foil and the resin layer containing the resin composition is required, it is preferred to provide a resin layer on the roughened surface of the polishing treatment or the electrolytic foil.

Further, the support may be disposed only on one surface of the resin sheet or on both surfaces.

The film thickness of the above-mentioned support is not particularly limited, and it is appropriately determined according to the knowledge of the manufacturer, based on the thickness of the resin composition layer, the use of the resin sheet, and the production equipment, and is excellent in economical efficiency and handleability of the resin sheet. Compared Preferably, it is from 10 μm to 150 μm, more preferably from 40 μm to 110 μm.

The resin sheet of the present invention can be produced, for example, by applying the above resin composition to the support and drying it. The coating method and drying method of the resin composition are not particularly limited, and a method generally used can be appropriately selected. For example, coating methods include blade coating, die coating, dip coating, and the like.

In the above drying method, a box-type warm air dryer can be used for batch processing, and a multi-stage warm air dryer or the like can be used for continuous treatment with the coating machine. Further, the heating conditions for drying are not particularly limited, and in the case of using a warm air dryer, from the viewpoint of preventing swelling of the coating of the resin composition, it is preferred that the warm air included in the dryer is lower than the solvent. The step of heat treatment in the temperature range of the boiling point.

When the resin sheet is a semi-cured material, the method of semi-curing is not particularly limited, and a method generally used can be appropriately selected, for example, the resin composition is semi-cured by heat treatment. The heat treatment method for semi-hardening is not particularly limited.

The above temperature range for semi-hardening can be appropriately selected depending on the epoxy resin constituting the resin composition. From the viewpoint of the strength of the B-stage sheet, it is preferred to carry out a hardening reaction by heat treatment, and the temperature range of the heat treatment is preferably from 80 ° C to 150 ° C, more preferably from 100 ° C to 120 ° C. Further, the time for the heat treatment for the semi-hardening is not particularly limited, and may be appropriately selected from the viewpoints of the curing speed of the resin of the B-stage sheet and the fluidity or adhesiveness of the resin, and it is preferred to heat for 1 minute. Within 30 minutes, more preferably 3 minutes to 10 minutes.

After the resin sheet is semi-hardened, two or more resin sheets are superposed, one The resin sheet is thermocompression bonded while being heated while being heated. The heating temperature at the time of thermocompression bonding can be selected according to the softening point or melting point of the resin, preferably 80 ° C to 180 ° C, more preferably 100 ° C to 150 ° C. Further, the pressurization at the time of thermocompression bonding is preferably carried out under vacuum, more preferably at 4 MPa to 20 MPa under vacuum, and particularly preferably at 5 MPa to 15 MPa.

<Resin cured sheet and method for producing the same>

The cured resin sheet of the present invention can be obtained by curing the above resin composition. Thereby, a cured resin having excellent thermal conductivity can be formed. The method of curing the resin composition is not particularly limited, and a method generally used can be appropriately selected, for example, the resin composition is cured by heat treatment.

The method of heat-treating the resin composition described above is not particularly limited, and the heating conditions are not particularly limited.

However, since the polyfunctional epoxy resin generally has a high curing rate, the curing at a high temperature tends to leave a functional group such as an unreacted epoxy group or a hydroxyl group, and it is difficult to obtain an effect of improving the thermal conductivity. Therefore, from the viewpoint of achieving a higher thermal conductivity, it is preferred to include a step of performing heat treatment in a temperature range (hereinafter sometimes referred to as "specific temperature range") in the vicinity of the activation temperature of the curing reaction. Here, the vicinity of the activation temperature of the hardening reaction indicates the temperature from the temperature at which the epoxy resin hardens and heats up to the peak temperature of the reaction heat in the differential thermal analysis.

The specific temperature range described above can be appropriately selected depending on the epoxy resin constituting the resin composition, and is preferably from 80 ° C to 180 ° C, more preferably from 100 ° C to 150 ° C. Higher heat conductivity can be achieved by heat treatment in this temperature range. When the above specific temperature range is below 150 ° C, it will inhibit hardening quickly. When the ground is excessively carried out, when it is 80 ° C or more, the resin is melted and hardened.

Further, the time of the heat treatment in a specific temperature range is not particularly limited, and it is preferably heated for 30 seconds or more and 15 minutes or less.

In the present invention, in addition to the heat treatment in a specific temperature range, at least one step of the step of performing heat treatment at a further high temperature is preferred. Thereby, the elastic modulus, thermal conductivity, and adhesion of the cured product can be further improved. The heat treatment at a further high temperature is preferably carried out at 120 ° C to 250 ° C, more preferably at 120 ° C to 200 ° C. If the temperature is too high, the resin is oxidized and easily causes coloration. Further, the heat treatment time is preferably from 30 minutes to 8 hours, more preferably from 1 hour to 5 hours. Further, the heat treatment is preferably carried out in a plurality of stages from a low temperature to a high temperature in the above temperature range.

In addition, a method of forming the cured product of the resin composition may be a method of curing the resin sheet after molding, or a method of curing the resin composition, and then slicing and slicing.

The thermal conductivity of the cured resin sheet of the present invention in the thickness direction is preferably 10 W/m. K or more, more preferably 12 W/m. K or more. Such thermal conductivity can be achieved by using the resin composition of the present invention.

<Structure, resin sheet with metal foil attached>

The structure of the present invention includes the resin sheet or the resin cured sheet (hereinafter collectively referred to as "the sheet of the present invention"), and a metal sheet provided in contact with one or both sides of the sheet of the present invention.

Examples of the metal plate include a copper plate, an aluminum plate, and an iron plate. Further, the thickness of the metal plate or the heat dissipation plate is not particularly limited. And, the metal plate can use copper. Metal foil such as foil or aluminum foil or tin foil. Further, in the present invention, the sheet having the metal foil on one side or both sides of the resin sheet is referred to as a metal foil-attached resin sheet.

The thickness of the metal plate is preferably set according to the use form or the thermal conductivity of the metal plate. Specifically, the average thickness is preferably 5 μm to 300 μm, more preferably 15 μm to 200 μm, and particularly preferably 30 μm to 150 μm.

The above structure can be produced by a production method including a step of disposing a metal plate on at least one surface of the sheet of the present invention to obtain a laminate. The method of arranging the metal plate on the sheet of the present invention can be carried out without any particular limitation. For example, a method of bonding a metal plate to at least one surface of the sheet of the present invention may be mentioned. Examples of the bonding method include a pressing method, a lamination method, and the like. The conditions of the pressing method and the lamination method can be appropriately selected depending on the constitution of the resin sheet.

Further, the above structure may have a metal plate on one surface of the sheet of the present invention and a bonded body on the other surface. In this aspect, since the resin sheet or the resin cured sheet is sandwiched between the adherend and the metal plate, the bonded body and the metal plate are excellent in thermal conductivity after curing. The material to be bonded is not particularly limited, and examples of the material of the adherend include a metal, a resin, a ceramic, and a composite material of a mixture thereof.

The above structure can be used for a semiconductor element for power or light source. 1 to 7 show examples of the configuration of the power semiconductor device, the light emitting diode (LED) light bar, and the LED light bulb which are formed using the sheet of the present invention.

In Fig. 1, a semi-hardened resin sheet 112 is used as a semi-hardened resin. A metal foil-attached resin sheet 110 is laminated with a metal support 114 of a protective layer of the sheet 112. More specifically, FIG. 1 is a schematic cross-sectional view showing a configuration example of a power semiconductor device 100 in which a power semiconductor wafer 102 is placed on a lead frame 106 of copper or a copper alloy via a solder layer 104. The sealing resin 108 is sealed and fixed, and the semi-hardened resin sheet 112 in the metal foil-attached resin sheet 110 of the present invention is pressed and hardened with the lead frame 106, and the metal support 114 is protected as the semi-hardened resin sheet 112. The layer is configured to be disposed on the heat sink 120 via the heat conductive material 122 such as a heat-dissipating grease.

The electrical insulation between the lead frame 106 and the heat sink 120 is electrically insulated by the metal foil-attached resin sheet 110 of the present invention, and heat generated in the power semiconductor wafer 102 can be efficiently dissipated to the heat sink 120. Further, the lead frame 106 may be a thick metal plate in order to improve heat dissipation. The heat sink 120 can be formed using copper or aluminum having thermal conductivity, and can be efficiently transferred to air or a fluid such as water by further forming a cooling wing or a water path. In addition, examples of the power semiconductor wafer include an insulated gate bipolar transistor (IGBT), a metal-oxide-semiconductor field-effect transistor (MOS-FET), and a diode. , integrated circuits, etc.

In the following FIGS. 2 to 7 , members denoted by FIG. 1 are denoted by the same reference numerals, and their description will be omitted.

In Fig. 2, a semi-hardened resin sheet 112 is used. More specifically, FIG. 2 is a schematic cross-sectional view showing a configuration example of the power semiconductor device 150 in which the power semiconductor wafer 102 passes through the solder layer 104. The copper lead frame 106 is placed on the copper lead frame 106, sealed and fixed by the sealing resin 108, and the obtained so-called split semiconductor component and the semi-hardened resin sheet 112 of the present invention are pressure-bonded to the heat sink 120 and thermally cured. The heat shield member 122 is disposed. By the resin sheet 112 of the present invention, it is possible to have both insulation and heat dissipation properties as in the case of FIG.

3 is a schematic cross-sectional view showing a configuration example of the power semiconductor device 160. In the power semiconductor device 160, the power semiconductor wafer 102 is placed on a copper or copper alloy lead frame 106 via a solder layer 104, and a copper or copper alloy wire is used. The holder 106 is crimped to the heat sink 120 via the resin sheet 112 of the present invention, and is sealed by a sealing resin 108. As in Fig. 1, it can have both insulation and heat dissipation.

FIG. 4 is a schematic cross-sectional view showing a configuration example of the power semiconductor device 200 in which the heat sink 120 is disposed on both surfaces of the power semiconductor wafer 102. The metal foil-attached resin sheet 110 of the present invention is disposed between each of the fins 120 and the lead frame 106. Further, the spacer 107 is disposed between the power semiconductor wafer 102 and the lead frame 106 via the solder layer 104. With this configuration, a higher cooling effect can be obtained than the one-side cooling structure of FIGS. 1 to 3.

FIG. 5 is a schematic cross-sectional view showing a configuration example of the power semiconductor device 210 in which cooling members are disposed on both surfaces of the power semiconductor wafer 102. The resin sheet 112 of the present invention bonds the lead frame 106 to the heat sink 120, so that the spacer 107 is not required, and a cooling effect higher than that of the configuration of Fig. 4 can be obtained.

Figure 6 is a view showing the use of a copper foil 116 and an aluminum plate which have been formed by a circuit A schematic cross-sectional view showing an example of the configuration of the LED light bar 300 formed by sandwiching the structure 115 of the resin cured product sheet 112 of the present invention.

The LED light bar 300 is configured by sequentially arranging the outer cover 132, the heat conductive member 122, the structural body 115 of the present invention, and the individual LED components 130. The LED individual component 130 as a heating element is electrically insulated from the metal plate (aluminum plate) 118 by interposing the copper foil 116 having the circuit and the resin cured material sheet 112 of the present invention, but can efficiently dissipate heat. The cover 132 can function as a heat sink by using a metal.

FIG. 7 is a schematic cross-sectional view showing an example of a configuration of an LED bulb 400 configured by sandwiching a structure 115 of the resin cured product sheet 112 of the present invention with a copper foil 116 having a circuit formed thereon and an aluminum plate 118. The LED bulb 400 has an LED driving circuit 142, and the lamp holder 146 is disposed on one side of the bulb housing 140, and the thermal conductor 122, the structural body 115 of the present invention, and the LED individual component 130 are sequentially disposed on the other side. Lens 144 covers LED individual parts 130. The LED individual component 130 as a heating element is disposed on the bulb housing 140 via the structural body 115 of the present invention, whereby heat can be efficiently dissipated.

[Example]

Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited to these examples. In addition, “parts” and “%” are quality standards unless otherwise stated.

The types and abbreviations or types of the epoxy resin, the novolak resin, the inorganic filler, the additive, and the solvent described in the examples are shown below.

(epoxy resin monomer)

TPM-Ep: Triphenylmethane type epoxy resin (EPPN-502H manufactured by Nippon Kayaku Co., Ltd., multi-functional, branched solid epoxy resin, epoxy equivalent 168 g/eq)

PhN-Ep: bisphenol F novolac type epoxy resin (jER 152 manufactured by Mitsubishi Chemical Corporation, polyfunctional, linear liquid epoxy resin, epoxy equivalent 165 g/eq)

BisAF-Ep: liquid bisphenol A epoxy resin and bisphenol F epoxy resin mixture (ZX-1059, difunctional liquid epoxy resin, epoxy equivalent 165 g/eq) manufactured by Nippon Steel Chemical Co., Ltd.

(hardener)

ReN: resorcinol novolac resin (synthetic product, diphenol novolak resin (m=2), hydroxyl equivalent: 62 g/eq, R ¹ :H, R ² :H of the general formula (I)

RCN: resorcinol catechol novolac resin (synthesis product, diphenol novolak resin (m=2), hydroxyl equivalent: 62 g/eq, R ¹ :H, R of the general formula (I) ² :H)

XLC: phenol-phenylphenyl aralkyl resin (XLC-LL, polyfunctional solid aralkyl resin manufactured by Mitsui Chemicals, hydroxyl equivalent: 175 g/eq)

Res: resorcinol (a reagent made from Wako Pure Chemical Industries, a binary mononuclear phenol compound, a hydroxyl equivalent of 55 g/eq)

(inorganic filler)

HP-40 (boron nitride, water island alloy iron; volume average particle size 40 μm, hexagonal crystal, agglomeration, aspect ratio 1.5)

PT-110 (boron nitride, manufactured by Momentive Japan; volume average particle size 43 μm, hexagonal crystal, scale, aspect ratio 10)

AA-18 (alumina, manufactured by Sumitomo Chemical; volume average particle size 18 μm)

AA-3 (alumina, manufactured by Sumitomo Chemical; volume average particle size 3 μm)

AA-04 (manufactured by Alumina and Sumitomo Chemical; volume average particle size 0.4 μm)

Shapal H (aluminum nitride, manufactured by Tokuyama; volume average particle size 0.5 μm)

(hardening accelerator)

TPP: Triphenylphosphine (manufactured by Wako Pure Chemical Industries, Ltd.)

(coupling agent)

PAM: N-phenyl-3-aminopropyltrimethoxydecane (manufactured by Shin-Etsu Chemical Co., Ltd., KBM-573)

(Dispersant)

BYK-106 (made by BYK-Chemie Japan)

REB122-4 (manufactured by Hitachi Chemical Co., Ltd., ethyl lactate 45% solution)

(solvent)

CHN: cyclohexanone

(support)

PET: Polyethylene terephthalate film which has been subjected to single-sided release treatment (manufactured by Fujimori Industrial Co., Ltd., Filmbyna 75E-0010CTR-4)

GTS: Electrolytic copper foil (manufactured by Furukawa Electric Co., Ltd., thickness 80 μm, GTS grade)

[Synthesis of Novolak Resin] (Synthesis of ReN)

In a 1 L separable flask equipped with a stirrer, a cooler and a thermometer, 110 g (1 mol) of resorcinol and 45 g of fumarin (about 0.5 mol, F/P = 0.5) were taken as a touch. After 1.1 g of oxalic acid and 50 g of water as a solvent, the oil bath was set to 120 ° C while stirring the contents, and the reaction was carried out for 3 hours while refluxing. Then, the cooler was taken out, and the distiller was attached, and the temperature was raised to 150 ° C while distilling off the water. Further, the mixture was stirred at 150 ° C for 12 hours and the reaction was continued. After completion of the reaction, the mixture was heated to 170 ° C, and unreacted resorcinol was sublimed under reduced pressure and removed over 8 hours. After removing the monomer, it was transferred to a stainless vat and cooled to obtain a resorcinol novolak resin (ReN).

The resorcinol novolak resin (ReN) has a monomer content of 8 mass%, and the number average molecular weight of the reaction product other than the monomer is determined by molecular weight of gel permeation chromatography (GPC). 900. It was found by ¹ H NMR (nuclear magnetic resonance) that the repeating unit contained an average of 2.0 hydroxyl groups. The average number of repeating units n was calculated to be 7.4 by dividing the number average molecular weight by the molecular weight 122 of the structural unit of the formula (I). Further, the hydroxyl equivalent was 62 g/eq.

(synthesis of RCN)

In a 3 L separable flask equipped with a stirrer, a cooler and a thermometer, 627 g of resorcinol, 33 g of catechol, 316.2 g of 37% humamine, 15 g of oxalic acid, and 300 g of water were charged. The oil bath was heated to 100 ° C while heating. Reflow at about 104 ° C, 4 hours at reflux temperature reaction. Then, the temperature in the flask was raised to 170 ° C while distilling off the water. The reaction was continued for 8 hours while maintaining 170 °C. After the reaction, the mixture was concentrated under reduced pressure for 20 minutes to remove water or the like in the system to obtain resorcinol catechol novolak resin (RCN).

The resorcinol catechol novolak resin (RCN) has a monomer content of 8% by mass as determined by molecular weight of GPC, and the number average molecular weight of the reaction product other than the monomer is 600. It was found by ¹ H NMR that the repeating unit contained an average of 1.8 hydroxyl groups. The hydroxyl equivalent weight was 62 g/eq. In addition, the structure was confirmed by field desorption mass spectrometry (FD-MS), and as a result, at least one of the dibenzopyrans represented by any one of the following formulas (VIIIa) to (VIIId) was contained. Skeleton derivatives. The dibenzopyran skeleton derivative was neglected, and the number average molecular weight was divided by the molecular weight 119 of the structural unit of the formula (I), whereby the average number of repeating units n was calculated to be 5.0.

[11]

[Evaluation method of hardener]

The physical properties of the hardener obtained above were measured in the following manner.

(molecular weight determination)

The number average molecular weight (Mn) was measured using a high performance liquid chromatography instrument L6000 manufactured by Hitachi, Ltd. and Shimadzu Corporation. The data analysis device C-R4A is used. The GPC column for analysis was G2000HXL and G3000HXL manufactured by Tosoh Corporation. The sample concentration was 0.2% by mass, and the mobile phase was measured using tetrahydrofuran at a flow rate of 1.0 ml/min. A calibration curve was prepared using a polystyrene standard sample, and the number average molecular weight was calculated using the calibration curve in terms of polystyrene.

(hydroxy equivalent)

The hydroxyl equivalent is determined by the ethyl chlorohydroxide-potassium hydroxide titration method. Further, since the color of the solution is dark, the determination of the end point of the titration is not performed by potentiometric titration by the coloring method using the indicator. Specifically, after the hydroxyl group of the measurement resin is subjected to acetonitrile chlorination in a pyridine solution, the excess reagent is decomposed with water, and the produced acetic acid is titrated by a potassium hydroxide/methanol solution.

[Manufacture of hardened epoxy resin without inorganic filler] <Reference Example 1>

100 parts of TPM-Ep as a multifunctional epoxy resin, 37 parts of ReN as a hardener, 0.3 parts of TPP as a hardening accelerator, on a hot plate in a 5 cm diameter stainless steel petri dish which was subjected to release treatment The mixture was mixed while heating and melting at 150 ° C, and then allowed to stand at 150 ° C for 1 hour to be hardened. Next, after secondary hardening at 160 ° C for 2 hours and 190 ° C for 2 hours, the cured resin was taken out from the stainless steel petri dish to obtain an epoxy resin cured product. As a result of the dynamic viscoelasticity measurement, a rubbery flat region was present at 300 ° C or higher, and the minimum value of the storage elastic modulus was 230 MPa at 340 ° C.

<Reference Example 2>

A resin cured product was obtained in the same manner except that 66 parts of BisAF-Ep was used instead of TPM-Ep as an epoxy resin of Example 1, and 71 parts of XLC was used instead of ReN as a hardener.

[Calculation of Crosslink Density of Reference Example 1 and Reference Example 2]

The crosslink density was calculated for the cured product of the resin compositions of Reference Example 1 and Reference Example 2 according to the following method. Comparing Reference Example 1 with Reference Example 2, it was found that the cured product of the resin composition of Reference Example 1 had a crosslinking density of about 12 times higher.

The crosslink density of the cured resin can be determined by (Expression 2) from the minimum value (E'min) of the storage elastic modulus of the rubber-like flat region of the cured resin according to the classical rubber elastic theory.

n: crosslink density (mol/cm ³ ), Mc: average molecular weight between cross-linking points (g/mol)

E'min: tensile storage elastic modulus minimum (Pa), ρ: density (g/cm ³ )

Φ: front coefficient (Φ) 1), R: gas constant (J/K.mol)

T: E'min absolute temperature (K)

[Manufacture of structure] <Example 1>

Metered as a multifunctional epoxy resin in a 250 mL polyethylene bottle The main agent has TPM-Ep 10.0 g (100 parts), ReN 3.7 g (37 parts) as a hardener, TPP 0.11 g (1.1 parts) as a hardening accelerator, and HP-40 56 g (560) as an inorganic filler. A), AA-04 11.3 g (113 parts), PAM 0.07 g (0.7 parts) as a coupling agent, BYK-106 0.1 g (1 part) as a dispersing agent, and REB122-4 1.6 g (16 parts) as After the solvent had a CHN of 50 g (500 parts) and a diameter of 5 mm of alumina beads of 100 g (1000 parts), the lid of the polyethylene bottle was sealed, and the resin composition was obtained by mixing at a rotation speed of 100 rpm for 30 minutes by a ball mill. Varnish.

The resulting resin composition varnish was applied to a polyethylene terephthalate (PET) film (manufactured by Fujimori Industrial Co., Ltd., 75E-0010 CTR-4) using an applicator having a gap of 400 μm. After the die surface, it was quickly dried in a box oven at 100 ° C for 10 minutes.

Next, the dried sheet was cut out into two pieces of 10 cm square, and the resin surface was superposed on the inner side by two pieces, and the vacuum heat pressing machine (hot plate 150 ° C, pressure 10 MPa, vacuum degree ≦ 1 kPa, treatment time 1 minute) was carried out. The resin sheet having a thickness of 200 μm in the resin composition layer was formed by thermocompression bonding, and a B-stage sheet was obtained.

The PET film was peeled off from both sides of the obtained B-stage sheet, and both sides were sandwiched by the roughened side of the 80 μm thick GTS copper foil by a vacuum hot press (hot plate temperature 150 ° C, vacuum degree 1 kPa, pressure 10) MPa and a treatment time of 10 minutes were subjected to pressure bonding and hardening, and then secondary hardening was performed at 160 ° C for 2 hours and at 190 ° C for 2 hours in a box type oven to obtain a structure in which copper foil was provided on both sides.

<Comparative Example 1>

A resin cured product was obtained in the same manner except that BisAF-Ep 6.6 g (66 parts) was used instead of TPM-Ep as an epoxy resin of Example 1, and XLC 7.1 g (71 parts) was used instead of ReN as a hardener. .

<Comparative Example 2>

84.9 g (849 parts) of AA-18, 30.9 g (309 parts) of AA-3, and 12.9 g (129 parts) of AA-04 were used instead of HP-40 and AA-04 as inorganic fillers of Example 1. Except for this, a cured resin was obtained in the same manner as in Example 1.

<Comparative Example 3>

84.9 g (849 parts) of AA-18, 0.9 g (309 parts) of AA-3 3 and 12.9 g (129 parts) of AA-04 were used instead of HP-40 and AA as inorganic fillers of Comparative Example 1. -04, except that the resin cured product was obtained in the same manner as in Comparative Example 1.

[Preparation of a resin sheet cured sample from which copper foil is removed]

The obtained cured resin sheet having copper foil on both sides thereof was immersed in an etching solution of a 20% aqueous solution of sodium persulfate, and the mixture was treated until the copper foil was completely dissolved. After the copper foil removal was completed, the sheet-like cured product was sufficiently washed with water, and dried at 120 ° C for 4 hours, and the obtained sample was used as a resin sheet cured product sample from which copper foil was removed.

(Evaluation of thermal diffusivity)

A sample of a cured sheet of a copper foil was removed, and a 10 mm square sample was cut out, and the heat of the thickness direction of the cured copper sheet-removed resin sheet at 25 ° C was measured by a flash method using a Nanoflash LFA447 model manufactured by NETZSCH Co., Ltd. Diffusion rate.

(Evaluation of specific heat)

A sample of about 3 mm square was cut out from the cured sheet of the resin sheet of the copper foil in a weight of 20 mg to 40 mg. The specific heat of the cured copper sheet-removed resin sheet at 25 ° C was measured using a differential scanning calorimeter (Pyris-1 manufactured by PERKINELMER Co., Ltd.) as a reference sample.

(Evaluation of density)

The density of the cured copper sheet-removed resin sheet at 25 ° C was measured using an Archimedes-based density measuring apparatus (SD-200L manufactured by Alfa Mirage Co., Ltd.).

(Evaluation of thermal conductivity)

The thermal diffusivity, the specific heat, and the density obtained above were substituted into (Formula 3), and the thermal conductivity in the thickness direction of the cured resin sheet was determined.

λ=α. Cp. ρ (Formula 3)

λ: thermal conductivity (W/m.K), α: thermal diffusivity (mm ² /s)

Cp: specific heat (J/kg.K), ρ: density (g/cm ³ )

[Measurement of storage elastic modulus and glass transition temperature]

A sample having a length of 33 mm × a width of 5 mm was cut out from the cured sheet of the resin sheet from which the copper foil was removed, and stored at 30 ° C to 350 ° C by a tensile mode using a SOLIDS ANALYZER II manufactured by Rheometric Scientific Co., Ltd. The temperature dependence of the elastic modulus.

Read the peak temperature of tan δ as the glass transition in dynamic viscoelasticity measurement Shift temperature (Tg). The test conditions were as follows: a heating rate of 5 ° C / min, a frequency of 10 Hz, a span of 21 mm, a tensile strain of 0.1%, and an air atmosphere.

(result)

According to the results of Example 1 and Comparative Example 1, it is understood that when boron nitride is used as a main component of the inorganic filler, if the crosslinking density of the matrix resin is about 13 times, the thermal conductivity is improved by 30%.

On the other hand, according to the results of Comparative Example 2 and Comparative Example 3, when alumina is used as the main component of the inorganic filler, even if the crosslinking density of the matrix resin is about 12 times, it is limited to 10%. The glass transition temperature according to Comparative Example 2 was lowered by 45 ° C compared to Example 1, and the reason was that the adsorption of alumina was Water is attached to hinder the hardening reaction and reduce the crosslinking density.

[Manufacture of structure] <Example 2 to Example 12, Comparative Example 4 to Comparative Example 5>

According to the procedure of Example 1, the materials shown in Table 2 were blended to obtain a cured resin. Further, materials not described in Table 2, that is, a curing accelerator, a coupling agent, and a dispersing agent were blended in the same amounts as in Example 1.

[Evaluation method]

The thermal conductivity and the glass transition temperature of the cured resin were measured in the same manner as described above for the resin composition obtained above. Further, the flexibility of the resin composition and the dielectric breakdown voltage of the cured resin formed of the resin composition were evaluated in the following manner. The results are shown in Table 2.

(softness evaluation)

The produced B-stage sheet was cut into a length of 100 mm and a width of 10 mm, and the PET film on the surface was removed. A sample was provided in a fixture made of aluminum and having a plurality of discs having a diameter of 20 mm to 140 mm and a score of 20 mm, and the minimum diameter of 20 mm which was bent without damage at 25 ° C was evaluated as good. The case where the minimum diameter of bending is 40 mm or 60 mm without damage is evaluated by ○; the case where the minimum diameter of bending is 80 m or 100 m without damage is evaluated as a practical limit; The case where the minimum diameter of the curve is 120 mm or more is evaluated as not suitable.

(Measurement of dielectric breakdown voltage)

A resin sheet cured sample from which copper foil was removed was placed in a metal container, and an electrode (a flat electrode made of aluminum, a diameter of 25 mm, and a contact surface of 20 mm) was placed in a sheet shape. Next, inject Fluorinert insulating oil (manufactured by 3M Company) FC-40), the dielectric breakdown voltage at 25 ° C was measured using a DAC-6032C manufactured by Total Electric Co., Ltd. in a state of being immersed in Fluorinert. The measurement conditions were set to a fixed speed boost of a frequency of 50 Hz and a boosting speed of 500 V/sec.

In Examples 1 to 12, compared with Comparative Example 1 to Comparative Example 5, it had excellent flexibility before curing, and exhibited high thermal conductivity after curing.

In more detail, in the comparison of Example 1, Example 12, and Comparative Example 4, the hydroxyl equivalents of TPM-Ep, PhN-Ep, and BisAF-Ep were approximately the same, and the blending amounts were approximately the same, but the thermal conductivity was greatly different. . TPM-Ep is a branched structure having a reactive end in a repeating unit and has a high crosslinking density Since the resin skeleton is compared with the polyfunctional or linear-structured PhN-Ep and the difunctional Bis-AF, it can be said that the effect of improving the thermal conductivity is exhibited.

The results of Comparative Example 1, Comparative Example 4, and Comparative Example 5 were lower than those of Example 1, and the reason was that the crosslinking density of the epoxy resin composition was low.

Further, according to the comparison of the results of Examples 1 to 5, the flexibility is improved by adding a difunctional epoxy resin or a mononuclear dihydric phenol compound, and if a difunctional epoxy resin and a mononuclear dihydric phenol compound are used, When combined, sufficient flexibility can be obtained. On the other hand, it is considered that by adding a difunctional epoxy resin or a mononuclear dihydric phenol compound, the crosslinking density is lowered, and the thermal conductivity is lowered as compared with Example 1. Further, since the RCN used in Examples 6 and 7 contained monomers, it was considered that the same softening effects as those of Examples 4 and 5 were obtained.

The results of Examples 8 to 10 are comparable to those of Example 1, Example 6, and Example 7, and it can be said that boron nitride can be reduced to increase the proportion of alumina up to 34% by volume of the inorganic filler.

As a result of Example 11, as compared with Example 1, it can be said that if aluminum nitride having a higher thermal conductivity than alumina is used as the small-particle diameter filler, the thermal conductivity of the cured resin can be improved.

100, 150, 160, 200, 210‧‧‧ power semiconductor devices

102‧‧‧Power semiconductor wafer

104‧‧‧ solder layer

106‧‧‧Metal plates for wiring (conductor, busbar)

107‧‧‧ spacers

108‧‧‧ Sealing resin

110‧‧‧Resin sheet with metal foil

112‧‧‧Resin sheet or resin cured sheet

114‧‧‧metal foil support

115‧‧‧ structure

116‧‧‧Circuit processed metal foil

118‧‧‧Metal plate

120‧‧‧ Heat sink

122‧‧‧Hot conductive materials (heat-dissipating grease, heat sink, phase change film)

130‧‧‧LED individual parts

132‧‧‧ Cover

140‧‧‧LED bulb housing

142‧‧‧LED drive circuit

144‧‧‧ lens

146‧‧‧ lamp holder

300‧‧‧LED strips

400‧‧‧LED bulb

1 is a schematic cross-sectional view showing a configuration example of a power semiconductor device configured by using a metal foil-attached resin sheet of the present invention.

2 is a schematic cross-sectional view showing another configuration example of a power semiconductor device configured by using the resin sheet of the present invention.

Figure 3 is a diagram showing a power semiconductor constructed using the resin sheet of the present invention. A schematic cross-sectional view of another configuration example of the device.

4 is a schematic cross-sectional view showing another configuration example of a power semiconductor device configured by using a metal foil-attached resin sheet of the present invention.

FIG. 5 is a schematic cross-sectional view showing another configuration example of a power semiconductor device configured by using the resin sheet of the present invention.

Fig. 6 is a schematic cross-sectional view showing a configuration example of an LED light bar constructed by using the structure of the present invention.

FIG. 7 is a schematic cross-sectional view showing a configuration example of an LED light bulb configured by using the structure of the present invention.

100‧‧‧Power semiconductor devices

102‧‧‧Power semiconductor wafer

104‧‧‧ solder layer

106‧‧‧Metal plates for wiring (conductor, busbar)

108‧‧‧ Sealing resin

110‧‧‧Resin sheet with metal foil

112‧‧‧Resin sheet or resin cured sheet

114‧‧‧metal foil support

120‧‧‧ Heat sink

122‧‧‧Hot conductive materials (heat-dissipating grease, heat sink, phase change film)

Claims (19)

A resin composition comprising: an epoxy resin containing a polyfunctional epoxy resin; a hardener comprising a novolac resin having a structural unit represented by the following formula (I); and an inorganic filler comprising nitride particles: In the formula (I), R ¹ and R ² each independently represent a hydrogen atom or a methyl group, m represents an average value of 1.5 to 2.5, and n represents an average value of 1 to 15. The resin composition according to claim 1, wherein the polyfunctional epoxy resin does not substantially have a liquid crystal skeleton. The resin composition according to claim 1 or 2, wherein the polyfunctional epoxy resin has a branched structure and has a reactive epoxy group in a side chain caused by the branched structure. The resin composition according to any one of claims 1 to 3, wherein the resin cured product when the resin composition containing the inorganic filler is not cured has a crosslinking density of 5 mmol/cm ³ the above. The resin composition according to any one of claims 1 to 4, which contains 50% by volume to 85% by volume of the above inorganic filler. The resin composition according to any one of the items 1 to 5, wherein the epoxy resin contains 20% by mass or more of the above polyfunctional epoxy resin. The resin composition according to any one of claims 1 to 6, wherein the polyfunctional epoxy resin is selected from the group consisting of a triphenylmethane type epoxy resin and a tetraphenylethane type epoxy resin. At least one of a dihydroxy novolac type epoxy resin and a glycidylamine type epoxy resin. The resin composition according to any one of claims 1 to 7, wherein the epoxy resin further comprises a liquid or semi-solid epoxy resin, and the liquid or semi-solid epoxy resin is Selected from bisphenol A epoxy resin, bisphenol F epoxy resin, bisphenol A and F epoxy resin, bisphenol F novolak epoxy resin, naphthalene glycol epoxy resin and glycidol At least one of the amine type epoxy resins. The resin composition according to any one of claims 1 to 8, wherein the curing agent contains 20% by mass to 70% by mass of at least one selected from the group consisting of mononuclear dihydroxybenzenes. The resin composition according to any one of claims 1 to 9, wherein the inorganic filler contains 50% by volume to 95% by volume of the nitride particles. The resin composition according to any one of the preceding claims, wherein the nitride particles are agglomerates or pulverized materials of hexagonal boron nitride, and a ratio of a major axis to a minor axis is 2 or less. . The resin composition according to any one of claims 1 to 11, further comprising a coupling agent. The resin composition according to any one of claims 1 to 12, further comprising a dispersing agent. A resin sheet which is an uncured or semi-cured product of the resin composition according to any one of claims 1 to 13. A resin sheet with a metal foil, comprising: a resin sheet as described in claim 14 of the patent application, and a metal foil. A cured resin sheet which is a cured product of the resin composition according to any one of claims 1 to 13. The resin cured sheet according to claim 16, wherein the thermal conductivity in the thickness direction is 10 W/m. K or more. A structure comprising the resin sheet according to claim 14 or the resin cured sheet according to claim 16 or 17, and the resin sheet or the cured resin sheet. A metal plate that is placed on one or both sides. A semiconductor element for a power source or a light source, comprising: a resin sheet according to claim 14 of the patent application, a metal foil-attached resin sheet according to claim 15 of the patent application, as claimed in claim 16 or The cured resin sheet according to item 17, or the structure according to item 18 of the patent application.