JP2016155985A - Epoxy resin composition, semi-cured epoxy resin composition and cured epoxy resin composition, and resin sheet, prepreg, laminate sheet, metal substrate, wiring board and power semiconductor device, using these - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an epoxy resin composition capable of forming a cured body having high thermal conductance, high insulation and high peeling strength with a metal foil, and also to provide a resin sheet, a prepreg, a laminate sheet, a metal substrate, a wiring board, a power semiconductor device, using the same.SOLUTION: An epoxy resin composition includes: a curative including a novolak resin prepared by reacting a divalent phenolic compound and an epoxy resin monomer expressed by formula (I) into a novolak resin; and a mixed filler of α-alumina and boron nitride. With regard to 100 vol.% of the volume of the entire filler, the volume ratio of the α-alumina is 50-90 vol.%. [In the general formula (I), Rto Rindependently represent a hydrogen atom or a 1-3C alkyl group.]SELECTED DRAWING: None

Description

  The present invention relates to an epoxy resin composition, a semi-cured epoxy resin composition, a cured epoxy resin composition, and a resin sheet, prepreg, laminate, metal substrate, wiring board, and power semiconductor device using the same.

  Many electronic devices and electrical devices ranging from generators, motors to printed wiring boards and IC chips are configured to include a conductor for conducting electricity and an insulating material. In recent years, since the amount of heat generation has increased with the miniaturization of these devices, how to dissipate heat in insulating materials has become an important issue.

  As an insulating material used in these devices, a cured resin product made of a thermosetting resin composition is widely used from the viewpoints of insulation and heat resistance. However, since the thermal conductivity of the cured resin is generally low and is a major factor hindering heat dissipation, development of a cured resin having high thermal conductivity is desired.

  As a resin cured product having high thermal conductivity, a cured product of an epoxy resin composition having a mesogen skeleton in the molecular structure has been proposed (for example, see Patent Document 1). Examples of the epoxy resin having a mesogen skeleton in the molecular structure include compounds shown in Patent Documents 2 to 4 and the like.

  Further, as a technique for achieving high thermal conductivity of a cured resin product, there is a method of filling a resin composition with a thermal conductive filler made of high thermal conductive ceramic to form a composite material. As high thermal conductive ceramics, alumina, boron nitride, aluminum nitride, silica, silicon nitride, magnesium oxide, silicon carbide and the like are known. By filling the resin composition with a thermally conductive filler that achieves both high thermal conductivity and insulating properties, the composite material can achieve both high thermal conductivity and insulating properties.

  In relation to the above, a resin composition containing a so-called mesogen skeleton-containing epoxy resin having a biphenyl skeleton, a phenol resin, and spherical alumina as essential components is disclosed (see, for example, Patent Document 5), and a semiconductor encapsulation excellent in high thermal conductivity is disclosed. It is said that it is a resin composition. Moreover, a resin composition containing an epoxy resin having a biphenyl skeleton, a curing agent having a xanthene skeleton, and an inorganic filler is disclosed (for example, see Patent Document 6), and is said to be a resin composition having excellent heat dissipation. Yes. Furthermore, a resin composition containing a tricyclic mesogen skeleton-containing epoxy resin, a curing agent, and alumina powder is disclosed (see, for example, Patent Document 7), and is said to have high thermal conductivity and excellent workability.

Japanese Patent No. 4118691 Japanese Patent No. 4619770 Japanese Patent No. 5471975 JP 2011-84557 A Japanese Patent No. 2874089 JP 2007-262398 A JP 2008-13759 A Japanese Patent No. 5348332 Japanese Patent No. 5652307

  Many resin compositions using alumina as a filler have been proposed as resin compositions having high thermal conductivity, including the resin compositions disclosed in the above-mentioned known documents. In recent years, many resin compositions using boron nitride as a filler have been proposed as resin compositions having higher thermal conductivity (see, for example, Patent Document 8). Boron nitride is also excellent in insulation. However, when boron nitride is used as the filler, the fluidity of the resin decreases, and the moldability of the resin composition tends to deteriorate.

  Under such circumstances, it has been proposed to ensure fluidity of the resin by mixing particulate fillers such as alumina and silica with boron nitride as shown in Patent Document 9 and the like. Since it becomes easy to shape | mold by ensuring the fluidity | liquidity of resin, it becomes a resin composition which has higher thermal conductivity and insulation. At this time, the volume fraction of the particulate filler is equal to or higher than the volume fraction of boron nitride in all fillers.

Furthermore, the resin composition using boron nitride as a filler generally has a reduced peel strength from the metal foil. When the adhesive strength with the metal foil is weak, when it is necessary to adhere the metal foil as described later, a micro or macro gap is formed at the interface with the metal foil, and the insulation as the metal substrate is It will fall greatly. Therefore, the adhesive strength with the metal foil is required to be a high value in order to ensure insulation when applied to a module such as the metal substrate. However, no resin composition has been reported so far that sufficiently satisfies the peel strength from the metal foil in addition to thermal conductivity and insulation.
Note that Patent Document 9 also does not describe the adhesive strength with the metal foil.

  In view of the above problems, the present invention provides an epoxy resin composition, a semi-cured epoxy resin composition, and the epoxy resin composition capable of forming a cured product having high thermal conductivity, high insulation, and high peel strength with a metal foil. It is another object of the present invention to provide a resin sheet, a prepreg, and a laminate that are configured using a semi-cured epoxy resin composition. Further, a cured epoxy resin composition having a high thermal conductivity, a high peel strength and a high insulating property, a resin sheet, a prepreg, a laminate, a metal substrate, obtained by curing the epoxy resin composition and the semi-cured epoxy resin composition, It is an object to provide a wiring board and a power semiconductor device.

As a result of intensive studies to solve the above problems, the present inventors have reached the present invention. That is, the present invention includes the following aspects.
<1> An epoxy resin monomer represented by the following general formula (I), a curing agent containing a novolac resin obtained by novolacizing a divalent phenol compound, and a mixed filler of α-alumina and boron nitride are contained. An epoxy resin composition,
The epoxy resin composition whose ratio which the volume of (alpha) -alumina occupies is 50-90 volume% when the volume of all the fillers contained in the said epoxy resin composition is 100 volume%.

In general formula (I), R < ¹ > -R < ⁴ > shows a hydrogen atom or a C1-C3 alkyl group each independently.

<2> The epoxy resin composition according to <1>, wherein the boron nitride is an aggregate of primary particles, and the average particle diameter (D50) of the aggregate is 1 to 100 μm.

<3> The epoxy resin composition according to <1> or <2>, wherein the α-alumina has a particle shape and an average particle diameter (D50) of 0.1 to 50 μm.

<4> Any one of <1> to <3>, wherein the curing agent is a novolak resin including a compound having a structural unit represented by the following general formula (II-1) or (II-2). The epoxy resin composition described in 1.

In general formulas (II-1) and (II-2), R ²¹ and R ²⁴ each independently represents an alkyl group, an aryl group, or an aralkyl group. R ²² , R ²³ , R ²⁵ , and R ²⁶ each independently represent a hydrogen atom, an alkyl group, an aryl group, or an aralkyl group. m21 and m22 each independently represent an integer of 0-2. n21 and n22 each independently represent an integer of 1 to 7.

<5> The curing agent is a novolak resin including a compound having a structure represented by at least one selected from the group consisting of the following general formulas (III-1) to (III-4): <1> The epoxy resin composition according to any one of to <3>.

In general formulas (III-1) to (III-4), m31 to m34 and n31 to n34 each independently represent a positive integer. Ar ^{31 to} Ar ³⁴ each independently represent either a group represented by the following general formula (III-a) or a group represented by the following general formula (III-b).

In the general formulas (III-a) and (III-b), R ³¹ and R ³⁴ each independently represent a hydrogen atom or a hydroxyl group. R ³² and R ³³ each independently represent a hydrogen atom or an alkyl group having 1 to 8 carbon atoms.

<6> The epoxy resin composition according to any one of <1> to <5>, wherein the curing agent has a content ratio of a monomer that is a phenol compound constituting the novolak resin of 5 to 80% by mass. .

<7> The epoxy resin composition according to any one of <1> to <6>, wherein the content of the mixed filler is 50 to 80% by volume in the entire volume.

<8> The epoxy resin composition according to any one of <1> to <7>, further comprising an elastomer having a structural unit represented by the following general formula (IV).

In the general formula (IV), R ⁴¹ , R ⁴² , and R ⁴³ each independently represent a linear or branched alkyl group or a hydrogen atom. R ⁴⁴ represents a linear or branched alkyl group. n4 represents an arbitrary positive integer.

<9> The epoxy resin composition according to <8>, wherein the elastomer contains an acrylic elastomer containing a structural unit represented by the following general formula (V).

In general formula (V), a, b, c, and d show the mol% of each structural unit in all the structural units, and are a + b + c + d = 90 mol% or more. R ⁵¹ and R ⁵² each independently represent a linear or branched alkyl group having a different carbon number. R ^{53 to} R ⁵⁶ each independently represent a hydrogen atom or a methyl group.

<10> A semi-cured epoxy resin composition which is a semi-cured product of the epoxy resin composition according to any one of <1> to <9>.

<11> A cured epoxy resin composition that is a cured product of the epoxy resin composition according to any one of <1> to <9>.

<12> The resin sheet which is a sheet-like molded object of the epoxy resin composition of any one of <1>-<9>.

<13> A prepreg having a fiber base material and the epoxy resin composition according to any one of <1> to <9> impregnated in the fiber base material.

<14> Adhering material, the epoxy resin composition according to any one of <1> to <9>, the resin sheet according to <12>, and <13> disposed on the adhering material. A laminate having a semi-cured epoxy resin composition layer that is at least one semi-cured material selected from the group consisting of the prepregs described in 1. or a cured epoxy resin composition layer that is a cured material.

It is selected from the group consisting of <15> metal foil, the epoxy resin composition according to any one of <1> to <9>, the resin sheet according to <12>, and the prepreg according to <13>. A metal substrate in which a cured epoxy resin composition layer, which is at least one cured body, and a metal plate are laminated in this order.

It is selected from the group consisting of <16> a metal plate, the epoxy resin composition according to any one of <1> to <9>, the resin sheet according to <12>, and the prepreg according to <13>. A wiring board in which a cured epoxy resin composition layer, which is at least one cured body, and a wiring layer are laminated in this order.

<17> A semiconductor module in which a metal plate, a solder layer, and a semiconductor chip are stacked in this order, a heat dissipation member, and <1> to <9 disposed between the metal plate and the heat dissipation member in the semiconductor module. > The hardened | cured material of the epoxy resin composition of any one of>.

  According to the present invention, an epoxy resin composition, a semi-cured epoxy resin composition, and an epoxy resin composition capable of forming a cured product having high thermal conductivity, high insulation, and high peel strength with a metal foil and a metal plate It is possible to provide a resin sheet, a prepreg, and a laminate that are formed using the product and a semi-cured epoxy resin composition. Further, a cured epoxy resin composition having a high thermal conductivity, a high peel strength and a high insulating property, a resin sheet, a prepreg, a laminate, a metal substrate, obtained by curing the epoxy resin composition and the semi-cured epoxy resin composition, A wiring board and a power semiconductor device can be provided.

It is a schematic sectional drawing which shows an example of a structure of the power semiconductor device comprised using the resin sheet concerning this invention. It is a schematic sectional drawing which shows another example of a structure of the power semiconductor device comprised using the resin sheet concerning this invention.

  In this specification, the term “process” is not limited to an independent process, and is included in the term if the intended purpose of the process is achieved even when it cannot be clearly distinguished from other processes. . Moreover, the numerical range shown using "to" shows the range which includes the numerical value described before and behind "to" as a minimum value and a maximum value, respectively. Furthermore, the amount of each component in the composition means the total amount of the plurality of substances present in the composition unless there is a specific notice when there are a plurality of substances corresponding to each component in the composition.

<Epoxy resin composition>
The epoxy resin composition of the present invention is a mixed filler of an epoxy resin monomer represented by the following general formula (I), a curing agent containing a novolak resin of a divalent phenol compound, and α-alumina and boron nitride When the volume of the mixed filler is 100% by volume, the proportion of the α-alumina volume is 50 to 90% by volume. In addition, the epoxy resin composition may further contain other components as necessary.
With such a configuration, the epoxy resin composition of the present invention can exhibit excellent high thermal conductivity after curing, high insulation, and high peel strength with a metal foil.

In general formula (I), R < ¹ > -R < ⁴ > represents a hydrogen atom or a C1-C3 alkyl group each independently.

  The epoxy resin monomer represented by the general formula (I) is an epoxy resin monomer having a mesogenic group in the molecular structure. It is described in the specification of patent document 1 that the cured body of such an epoxy resin monomer is excellent in thermal conductivity. In addition, by combining a novolak resin obtained by novolacizing a divalent phenol compound with the epoxy resin monomer represented by the general formula (I), the thermal conductivity of the cured epoxy resin composition is further improved and the heat resistance is also improved. Then, it is described in International Publication No. 2013/0665759. This is considered to be because, for example, a very high-density crosslink is formed in the cured product composed of the epoxy resin monomer and the novolak resin. Generally, when the crosslink density is high, the glass transition temperature (Tg) of the cured body is increased, and when the Tg of the cured body is increased, the thermal conductivity and heat resistance tend to be improved.

  Here, the mesogenic group refers to a functional group that facilitates the expression of crystallinity or liquid crystallinity by the action of intermolecular interaction. Specific examples include a biphenyl group, a phenylbenzoate group, an azobenzene group, a stilbene group, and derivatives thereof. The epoxy resin monomer represented by the general formula (I) is also a kind of epoxy resin monomer having a mesogenic group in the molecular structure.

  In addition, the present inventors have formed a higher order structure having higher ordering around the α-alumina filler, the epoxy resin monomer represented by the general formula (I) having a mesogenic group in the molecular structure, It has been found that the thermal conductivity of the cured product is dramatically improved. That is, since the cured product of the epoxy resin monomer serves as a heat conduction path between the α-alumina fillers, higher heat conductivity can be achieved.

Here, the higher order structure means a structure including a higher order structure in which the constituent elements are arranged to form a micro ordered structure, and corresponds to, for example, a crystal phase or a liquid crystal phase. The presence confirmation of such a higher-order structure can be easily determined by observation with a polarizing microscope. In other words, in the observation in the crossed Nicols state, it can be determined by seeing interference fringes due to depolarization.
This higher-order structure usually exists in an island shape in the cured epoxy resin composition to form a domain structure, and one of the islands corresponds to one higher-order structure. The constituent elements of this higher order structure are generally formed by covalent bonds.

In addition, presence of the higher order structure in the cured epoxy resin composition containing an α-alumina filler can be confirmed as follows.
A cured product of a composition obtained by adding 5 to 10% by volume of α-alumina filler to the epoxy resin monomer represented by formula (I) having a mesogenic group in the molecular structure and a curing agent (thickness: 0. 1-20 μm) is prepared. Observation is performed using a polarizing microscope (for example, Olympus BX51) in a state where the obtained cured body is sandwiched between slide glasses (thickness: about 1 mm). An interference pattern is observed around the α-alumina filler in the region where the α-alumina filler is present, but no interference pattern is observed in the region where the α-alumina filler is not present. From this, it can be seen that the cured product of the epoxy resin monomer represented by the general formula (I) centering on the α-alumina filler forms a higher order structure.

  Note that the observation needs to be performed not in the crossed Nicols state but in a state where the analyzer is rotated by 60 ° with respect to the polarizer. When observed in a crossed Nicol state, a region where no interference pattern is observed (that is, a region where the cured resin body does not form a higher order structure) becomes a dark field, and cannot be distinguished from the α-alumina filler portion. However, by rotating the analyzer by 60 ° with respect to the polarizer, the region where no interference pattern is observed is not a dark field, and can be distinguished from the α-alumina filler portion.

In a cured product that does not contain a filler and is composed only of a resin and a curing agent, whether the resin forms a higher-order structure depending on whether an interference pattern is observed or a dark field is observed in observation in a crossed Nicol state. You can determine whether or not.
On the other hand, in a cured product containing a filler, when observed in a crossed Nicol state, the dark field region where no interference pattern is observed is because the resin does not form a higher order structure, or is derived from the filler. It is impossible to determine if it exists. Therefore, it is necessary to observe the analyzer with the analyzer rotated by 60 ° with respect to the polarizer. The filler becomes a dark field regardless of the angle between the polarizer and the analyzer, but the portion where the resin does not form a higher order structure is observed when the analyzer is rotated by 60 ° with respect to the polarizer. It is not a dark field, but light is transmitted through a little, but it looks bright. That is, it is possible to distinguish between a portion where the resin does not form a higher order structure and a portion derived from the filler.

  Moreover, the peeling strength with metal foil becomes high by using a particulate thing like an alumina for a filler. When the peel strength from the metal foil is weak, when it is necessary to bond the metal foil as described later, a micro or macro gap is formed at the interface with the metal foil, and the insulation as the metal substrate is It will fall greatly. Therefore, when applied to a module such as the metal substrate, the peel strength from the metal foil is required to be a high value in order to ensure insulation.

  On the other hand, the electrical insulation of the epoxy resin composition itself is higher when a scaly material such as boron nitride is used as a filler than a particulate material such as alumina.

Therefore, the epoxy resin composition of the present invention raises the electrical insulation of the epoxy resin composition itself by using a mixed filler of α-alumina and boron nitride as a filler, and further, the proportion of the volume of α-alumina Is limited to 50 to 90% by volume when the volume of all fillers is 100% by volume, it is possible not to lower the peel strength to the metal foil. Therefore, it is possible to achieve both thermal conductivity and electrical insulation of the entire module such as a laminated plate, a metal substrate, a wiring board, and a power semiconductor device.
In addition, it is more preferable that the ratio which the volume of (alpha) -alumina occupies is 60-90 volume% when the volume of all the fillers is 100 volume%, and it is still more preferable that it is 70-85 volume%.

  In addition, in order not to reduce the peel strength with the metal foil, α-alumina is contained more as a volume fraction than boron nitride, so compared with the epoxy resin composition using boron nitride as the main filler. There is concern about a decrease in thermal conductivity. However, the epoxy resin composition of the present invention uses the general formula (I) having a mesogenic group in the molecular structure as an epoxy resin monomer, and as described above, has higher ordering centering on an α-alumina filler. Since the higher order structure is formed, the thermal conductivity of the cured body is not lowered.

That is, the mixed filler contains an epoxy resin monomer represented by the general formula (I), a curing agent containing a resin obtained by novolacizing a divalent phenol compound, and a mixed filler of α-alumina and boron nitride. When the volume of α is 100% by volume, the proportion of the volume of α-alumina is in the range of 50 to 90% by volume, thereby having high thermal conductivity, high insulation, and high peel strength with the metal foil. An epoxy resin composition capable of forming a cured body is obtained.
In addition, a resin sheet, a prepreg, and a laminate formed using the epoxy resin composition and the semi-cured epoxy resin composition also have high thermal conductivity, high insulating properties, and high peel strength from the metal foil. Further, a cured epoxy resin composition obtained by curing the epoxy resin composition and the semi-cured epoxy resin composition, a resin sheet, a prepreg, a laminate, a metal substrate, a wiring board, and a power semiconductor device have high thermal conductivity and high resistance. Insulation can be exhibited.
Hereinafter, the material used for the epoxy resin composition and the physical properties of the epoxy resin composition will be described.

(Epoxy resin monomer)
The said epoxy resin composition contains at least 1 sort (s) of the epoxy resin monomer represented by the following general formula (I).

  The epoxy resin monomer represented by the general formula (I) tends to form a higher order structure having higher ordering with α-alumina as the center. As a result, the thermal conductivity after curing tends to improve dramatically. It is considered that this is because the cured product of the epoxy resin in which higher-order structure is formed by the presence of α-alumina becomes an efficient heat conduction path, and high heat conductivity is obtained.

  The epoxy resin monomer represented by the general formula (I) has a high transition temperature to the liquid crystal phase, that is, a melting temperature of about 150 ° C. Therefore, when the epoxy resin monomer is to be melted, although depending on the curing agent and curing accelerator used, the curing reaction usually proceeds simultaneously with melting. As a result, the epoxy resin monomer becomes a cured body before forming a higher order structure. However, in a system containing α-alumina, a cured product in which the epoxy resin monomer forms a higher order structure tends to be obtained even when heated at a high temperature.

  This is considered because the higher-order structure formation effect of the said epoxy resin monomer by using (alpha) -alumina is remarkable. That is, it is considered that a higher-order structure is quickly formed around the α-alumina before the curing reaction of the epoxy resin monomer proceeds.

  Furthermore, the epoxy resin monomer represented by the general formula (I) can exhibit only a nematic structure with the epoxy resin monomer alone. For this reason, it is relatively difficult to form a higher order structure in an epoxy resin monomer having a mesogenic group in the molecular structure. However, by using a composite material combined with an α-alumina filler, the epoxy resin monomer represented by the general formula (I) exhibits a smectic structure having a higher order than a nematic structure. As a result, the thermal conductivity is unpredictably high from a cured product composed of a single epoxy resin monomer.

  Note that each of the nematic structure and the smectic structure is a kind of liquid crystal structure. The nematic structure is a liquid crystal structure in which the molecular long axis is oriented in a uniform direction and has only alignment order. On the other hand, the smectic structure is a liquid crystal structure having a one-dimensional positional order in addition to the orientation order and having a layer structure. The order is higher in the smectic structure than in the nematic structure. For this reason, the thermal conductivity of the cured resin is also higher when it exhibits a smectic structure.

In the general formula (I), R ^{1 to} R ⁴ each independently represent a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, preferably a hydrogen atom or an alkyl group having 1 to 2 carbon atoms, It is more preferably an atom or a methyl group, and further preferably a hydrogen atom.
Further, 2 to ⁴ of R ^{1 to} R ⁴ are preferably hydrogen atoms, 3 or 4 are preferably hydrogen atoms, and all 4 are preferably hydrogen atoms. When any of R ^{1 to} R ⁴ is an alkyl group having 1 to 3 carbon atoms, at least one of R ¹ and R ⁴ is preferably an alkyl group having 1 to 3 carbon atoms.

  The preferred form of the epoxy resin monomer is as described in Patent Document 3. Specifically, the epoxy resin monomer includes 4- {4- (2,3-epoxypropoxy) phenyl} cyclohexyl-4- (2,3-epoxypropoxy) benzoate and 4- {4- (2,3- Epoxypropoxy) phenyl} cyclohexyl-4- (2,3-epoxypropoxy) -3-methylbenzoate is preferred.

  The epoxy resin monomer may be used as a prepolymer obtained by partially reacting the epoxy resin monomer with a curing agent described later. Epoxy resin monomers having a mesogenic group in the molecular structure are generally easily crystallized, and the solubility in solvents is often lower than that of general epoxy resin monomers. The epoxy resin monomer represented by the general formula (I) also corresponds to this. However, since the crystallization can be suppressed by partially polymerizing the epoxy resin monomer represented by the general formula (I), the solubility in a solvent is improved, and the moldability may be further improved.

The resin component of the epoxy resin composition is preferably contained in an amount of 20 to 50% by volume in the total volume of the total solid content of the epoxy resin composition from the viewpoints of moldability, adhesiveness, and thermal conductivity. More preferably, it is contained at 20 to 40% by volume, and more preferably 25 to 35% by volume.
In addition, when the said epoxy resin composition contains the below-mentioned hardening | curing agent or hardening accelerator, unless otherwise indicated, the content rate of a resin component here includes the content rate of these hardening | curing agents and hardening accelerators. To do.

  In addition, let the content rate (volume%) of the resin component containing the hardening | curing agent and hardening accelerator in this specification be the value calculated | required by following Formula. Hereinafter, the content rate (volume%) of the material used for the epoxy resin composition is a value obtained based on this method.

  Resin component content (volume%) = {((Aw / Ad) + (Bw / Bd) + (Cw / Cd)) / ((Aw / Ad) + (Bw / Bd) + (Cw / Cd) + (Dw / Dd) + (Ew / Ed) + (Fw / Fd))} × 100

Here, each variable is as follows.
Aw: mass composition ratio of epoxy resin monomer (mass%)
Bw: mass composition ratio (% by mass) of curing agent
Cw: mass composition ratio (mass%) of curing accelerator (optional component)
Dw: mass composition ratio of alumina filler (mass%)
Ew: Mass composition ratio (mass%) of boron nitride filler
Fw: Mass composition ratio (% by mass) of other optional components (excluding organic solvents)
Ad: Specific gravity of epoxy resin monomer Bd: Specific gravity of curing agent Cd: Specific gravity of curing accelerator (optional component) Dd: Specific gravity of alumina filler Ed: Specific gravity of boron nitride filler Fd: Other optional components (excluding organic solvents) specific gravity

(Curing agent)
The epoxy resin composition includes a curing agent including a novolak resin obtained by novolacizing a divalent phenol compound (hereinafter sometimes referred to as “specific novolak resin”).

  Examples of the divalent phenol compound include catechol, resorcinol, hydroquinone, 1,2-naphthalenediol, 1,3-naphthalenediol, and the like. A novolak resin obtained by novolacizing a divalent phenol compound refers to a novolak resin in which these compounds are connected by a methylene chain. The thermal conductivity of the epoxy resin composition is improved by using a divalent phenol compound, and the heat resistance is further improved by making these compounds novolak.

  It is preferable that specific novolak resin contains the compound which has a structural unit represented by the following general formula (II-1) or (II-2).

In the general formulas (II-1) and (II-2), R ²¹ and R ²⁴ each independently represents an alkyl group, an aryl group, or an aralkyl group. The alkyl group, aryl group, and aralkyl group represented by R ²¹ or R ²⁴ may further have a substituent, if possible. Examples of the substituent include an alkyl group, an aryl group, a halogen atom, and a hydroxyl group.

R ²¹ and R ²⁴ each independently represents an alkyl group, an aryl group, or an aralkyl group, but an alkyl group having 1 to 6 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an aralkyl group having 7 to 13 carbon atoms. It is preferable that it is a C1-C6 alkyl group.

m21 and m22 each independently represents an integer of 0 to 2. If m21 is 2, two R ²¹ may be the same or different and when m22 is 2, two R ²⁴ may be different even in the same. In the present invention, m21 and m22 are each independently preferably 0 or 1, and more preferably 0.
N21 and n22 each independently represents an integer of 1 to 7, and represents the number of structural units represented by the general formula (II-1) or the structural unit represented by the general formula (II-2). Show.

In the general formulas (II-1) and (II-2), R ²² , R ²³ , R ²⁵ , and R ²⁶ each independently represent a hydrogen atom, an alkyl group, an aryl group, or an aralkyl group. The alkyl group, aryl group, and aralkyl group represented by R ²² , R ²³ , R ²⁵ , or R ²⁶ may further have a substituent if possible. Examples of the substituent include an alkyl group, an aryl group, a halogen atom, and a hydroxyl group.

R ²² , R ²³ , R ²⁵ , and R ²⁶ in the present invention are preferably a hydrogen atom, an alkyl group, or an aryl group from the viewpoint of storage stability and thermal conductivity. It is more preferable that it is -4 alkyl group or a C6-C12 aryl group, and it is still more preferable that it is a hydrogen atom.
Furthermore, from the viewpoint of heat resistance, at least one of R ²² and R ²³ or at least one of R ²⁵ and R ²⁶ is also preferably an aryl group, and more preferably an aryl group having 6 to 12 carbon atoms. .
In addition, the said aryl group may contain the hetero atom in the aromatic group, and it is preferable that it is a heteroaryl group from which the total number of a hetero atom and carbon becomes 6-12.

  The curing agent may contain one type of compound having the structural unit represented by the general formula (II-1) or the structural unit represented by the general formula (II-2). It may contain more than species. From the viewpoint of thermal conductivity, the curing agent preferably includes at least a compound having a structural unit represented by General Formula (II-1), and is represented by General Formula (II-1) and is a structure derived from resorcinol. More preferably, it contains at least a compound having a unit.

When the compound having the structural unit represented by the general formula (II-1) has a structural unit derived from resorcinol, it may further include at least one partial structure derived from a phenol compound other than resorcinol. . Examples of phenol compounds other than resorcinol in the general formula (II-1) include phenol, cresol, catechol, hydroquinone, 1,2,3-trihydroxybenzene, 1,2,4-trihydroxybenzene, 1,3,5- A trihydroxybenzene etc. can be mentioned. The compound having the structural unit represented by the general formula (II-1) may contain a partial structure derived from these phenol compounds alone or in combination of two or more.
In addition, the compound represented by the general formula (II-2) and having a structural unit derived from catechol may include at least one partial structure derived from a phenol compound other than catechol.

  Here, the partial structure derived from a phenol compound means a monovalent or divalent group constituted by removing one or two hydrogen atoms from the aromatic ring portion of the phenol compound. The position where the hydrogen atom is removed is not particularly limited.

  In the compound having the structural unit represented by the general formula (II-1), as a partial structure derived from a phenol compound other than resorcinol, from the viewpoint of thermal conductivity, adhesiveness, and storage stability, phenol, cresol, It is preferably a partial structure derived from at least one selected from catechol, hydroquinone, 1,2,3-trihydroxybenzene, 1,2,4-trihydroxybenzene, and 1,3,5-trihydroxybenzene. More preferably, it is a partial structure derived from at least one selected from catechol and hydroquinone.

  Moreover, when the compound which has a structural unit represented by general formula (II-1) contains the structural unit derived from resorcinol, there is no restriction | limiting in particular about the content rate of the partial structure derived from resorcinol. From the viewpoint of the elastic modulus, the content ratio of the partial structure derived from resorcinol to the total mass of the compound having the structural unit represented by the general formula (II-1) is preferably 55% by mass or more. From the viewpoint of the expansion coefficient, it is more preferably 60% by mass or more, further preferably 80% by mass or more, and particularly preferably 90% by mass or more from the viewpoint of thermal conductivity.

  Furthermore, the specific novolak resin is more preferably a novolak resin containing a compound having a structure represented by at least one selected from the group consisting of the following general formulas (III-1) to (III-4).

In general formulas (III-1) to (III-4), m31 to m34 and n31 to n34 each independently represent a positive integer. Ar ^{31 to} Ar ³⁴ each independently represent either a group represented by the following general formula (III-a) or a group represented by the following general formula (III-b).

In the general formulas (III-a) and (III-b), R ³¹ and R ³⁴ each independently represent a hydrogen atom or a hydroxyl group. R ³² and R ³³ each independently represent a hydrogen atom or an alkyl group having 1 to 8 carbon atoms.

  A curing agent having a structure represented by at least one selected from the group consisting of the general formulas (III-1) to (III-4) is obtained by a production method described below in which a divalent phenol compound is converted into a novolak form. It can be generated generatively.

The structure represented by at least one selected from the group consisting of general formulas (III-1) to (III-4) may be included as the main chain skeleton of the curing agent, It may be included as a part. Furthermore, each repeating unit constituting the structure represented by any one of the general formulas (III-1) to (III-4) may be included randomly or regularly. It may be included in a block shape.
In the general formulas (III-1) to (III-4), the hydroxyl substitution position is not particularly limited as long as it is on the aromatic ring.

For each of the general formulas (III-1) to (III-4), a plurality of Ar ³¹ to Ar ³⁴ may all be the same atomic group or may contain two or more kinds of atomic groups. . Ar ^{31 to} Ar ³⁴ each independently represent either a group represented by the general formula (III-a) or a group represented by the general formula (III-b).

R ³¹ and R ³⁴ in formulas (III-a) and (III-b) are each independently a hydrogen atom or a hydroxyl group, and are preferably a hydroxyl group from the viewpoint of thermal conductivity. Further, the substitution positions of R ³¹ and R ³⁴ are not particularly limited.

In the general formulas (III-a) and (III-b), R ³² and R ³³ each independently represent a hydrogen atom or an alkyl group having 1 to 8 carbon atoms. Examples of the alkyl group having 1 to 8 carbon atoms in R ³² and R ³³ include methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, t-butyl group, pentyl group, hexyl group, heptyl group, An octyl group etc. are mentioned. Further, the substitution positions of R ³² and R ^{33 in} the general formulas (III-a) and (III-b) are not particularly limited.

Ar ^{31 to} Ar ³⁴ in the general formulas (III-1) to (III-4) are each independently a group derived from dihydroxybenzene (ie, from the viewpoint of achieving the effect of the present invention, particularly excellent thermal conductivity) In the above general formula (III-a), R ³¹ is a hydroxyl group and R ³² and R ³³ are hydrogen atoms), and a group derived from dihydroxynaphthalene (that is, R in the above general formula (III-b)) It is preferably at least one selected from the group wherein ³⁴ is a hydroxyl group.

  Here, the “group derived from dihydroxybenzene” means a divalent group formed by removing two hydrogen atoms from the aromatic ring portion of dihydroxybenzene, and the position at which the hydrogen atom is removed is not particularly limited. In addition, “group derived from dihydroxynaphthalene” has the same meaning.

In addition, from the viewpoint of productivity and fluidity of the epoxy resin composition, Ar ^{31 to} Ar ³⁴ are preferably each independently a group derived from dihydroxybenzene, such as 1,2-dihydroxybenzene (catechol). More preferably, it is at least one selected from the group consisting of a group derived from and a group derived from 1,3-dihydroxybenzene (resorcinol). Furthermore, Ar ^{31 to} Ar ³⁴ preferably include at least a group derived from resorcinol from the viewpoint of particularly enhancing thermal conductivity.
Moreover, it is preferable that the structural unit represented by n31-n34 contains at least the partial structure derived from a resorcinol from a viewpoint which raises heat conductivity especially.

  When the specific novolac resin includes a partial structure derived from resorcinol, the content of the partial structure derived from resorcinol is a structure represented by at least one of general formulas (III-1) to (III-4) It is preferably 55% by mass or more, preferably 60% by mass or more, more preferably 80% by mass or more, and still more preferably 90% by mass or more, based on the total mass of the compound having the above.

  From the viewpoint of fluidity, m31 to m34 and n31 to n34 in the general formulas (III-1) to (III-4) are preferably m / n = 20/1 to 1/5. It is more preferably 1 to 5/1, and further preferably 20/1 to 10/1. Further, (m + n) is preferably 20 or less, more preferably 15 or less, and still more preferably 10 or less, from the viewpoint of fluidity. In addition, the lower limit of (m + n) is not particularly limited. Here, when n is n31, m is m31, when n is n32, m is m32, when n is n33, m is m33, and when n is n34, m is m34.

The novolak resin having a structure represented by at least one selected from the group consisting of the general formulas (III-1) to (III-4), particularly Ar ^{31 to} Ar ³⁴ is substituted or unsubstituted dihydroxybenzene and substituted or unsubstituted When at least one kind of unsubstituted dihydroxynaphthalene is used, compared to a novolak resin or the like obtained by simply novolacizing these, the synthesis thereof is easy, and a novolak resin having a low softening point tends to be obtained. Therefore, there exists an advantage that manufacture and handling of such a novolak resin as a hardening | curing agent also become easy.
In addition, the novolak resin having the structure represented by any one of the above general formulas (III-1) to (III-4) has the structure as a fragment component by field desorption ionization mass spectrometry (FD-MS). Can be specified.

The molecular weight of the novolak resin having a structure represented by any one of the general formulas (III-1) to (III-4) is not particularly limited. From the viewpoint of fluidity, the number average molecular weight (Mn) is preferably 2000 or less, more preferably 1500 or less, and further preferably 350 or more and 1500 or less. Further, the weight average molecular weight (Mw) is preferably 2000 or less, more preferably 1500 or less, and further preferably 400 or more and 1500 or less.
These Mn and Mw are measured by a normal method using GPC.

  The hydroxyl equivalent of the novolak resin having a structure represented by any one of the general formulas (III-1) to (III-4) is not particularly limited. From the viewpoint of the crosslinking density involved in heat resistance, the hydroxyl group equivalent is preferably 50 or more and 150 or less on average, more preferably 50 or more and 120 or less, and further preferably 55 or more and 120 or less. preferable.

  The specific novolac resin may contain a monomer that is a phenol compound constituting the novolac resin. There is no restriction | limiting in particular as a content ratio (henceforth "monomer content ratio") of the monomer which is a phenol compound which comprises specific novolak resin. From the viewpoint of thermal conductivity, heat resistance, and moldability, the monomer content ratio is preferably 5 to 80% by mass, more preferably 15 to 60% by mass, and 20 to 50% by mass. Further preferred.

  When the monomer content is 80% by mass or less, the amount of monomers that do not contribute to crosslinking during the curing reaction is reduced and the number of crosslinked high molecular weight substances is increased, so that a higher-order higher-order structure is formed and heat conduction is increased. Improves. Moreover, since it is easy to flow at the time of shaping | molding because it is 5 mass% or more, adhesiveness with a filler improves more and more excellent thermal conductivity and heat resistance can be achieved.

  The content of the curing agent in the epoxy resin composition is not particularly limited. The ratio (phenolic hydroxyl group equivalent / epoxy equivalent) of the active hydrogen equivalent of the phenolic hydroxyl group in the curing agent (phenolic hydroxyl group equivalent) to the epoxy equivalent of the epoxy resin monomer represented by formula (I) is 0.5 to 0.5. 2 is preferable, and 0.8 to 1.2 is more preferable.

Moreover, the epoxy resin composition may further contain a curing accelerator as necessary. By further including a curing accelerator, it can be further sufficiently cured. The type and content of the curing accelerator are not particularly limited, and an appropriate type and content can be selected from the viewpoint of reaction rate, reaction temperature, storage property, and the like. Specific examples of the curing accelerator include imidazole compounds, organic phosphorus compounds, tertiary amines, quaternary ammonium salts, and the like. These may be used alone or in combination of two or more.
Among these, from the viewpoint of heat resistance, it is preferably at least one selected from the group consisting of an organic phosphine compound and a complex of an organic phosphine compound and an organic boron compound.

  Specific examples of the organic phosphine compound include triphenylphosphine, diphenyl (p-tolyl) phosphine, tris (alkylphenyl) phosphine, tris (alkoxyphenyl) phosphine, tris (alkylalkoxyphenyl) phosphine, and tris (dialkylphenyl). Phosphine, tris (trialkylphenyl) phosphine, tris (tetraalkylphenyl) phosphine, tris (dialkoxyphenyl) phosphine, tris (trialkoxyphenyl) phosphine, tris (tetraalkoxyphenyl) phosphine, trialkylphosphine, dialkylarylphosphine, Examples thereof include alkyl diaryl phosphine.

  Specific examples of the complex of an organic phosphine compound and an organic boron compound include tetraphenylphosphonium tetraphenylborate, tetraphenylphosphonium tetra-p-tolylborate, tetrabutylphosphonium tetraphenylborate, and tetraphenylphosphonium n-butyl. Examples thereof include triphenyl borate, butyl triphenyl phosphonium tetraphenyl borate, and methyl tributyl phosphonium tetraphenyl borate.

  One type of curing accelerator may be used alone, or two or more types may be used in combination. As a method for efficiently producing a semi-cured epoxy resin composition and a cured epoxy resin composition, which will be described later, a method of mixing and using two kinds of curing accelerators having different reaction start temperatures and reaction rates between an epoxy resin monomer and a novolac resin Is mentioned.

  When using two or more types of curing accelerators in combination, the mixing ratio should be determined without any particular restrictions depending on the properties required for the semi-cured epoxy resin composition (for example, how much flexibility is required). Can do.

  When the epoxy resin composition includes a curing accelerator, the content of the curing accelerator in the epoxy resin composition is not particularly limited. From the viewpoint of moldability, the content of the curing accelerator is preferably 0.5 to 1.5% by mass of the total mass of the epoxy resin monomer having a mesogenic group in the molecule and the curing agent, and 0.5 to 1 It is more preferable that it is mass%, and it is still more preferable that it is 0.75-1 mass%.

(Filler)
The epoxy resin composition of the present invention contains a mixed filler of α-alumina and boron nitride described later.
The mixed filler content in the epoxy resin composition is not particularly limited. The mixed filler content is preferably 50 to 80% by volume in the total volume of the total solid content of the epoxy resin composition. When the content of the mixed filler in the epoxy resin composition is 50% by volume or more, the thermal conductivity is excellent, and when the content of the mixed filler is 80% by volume or less, moldability and adhesiveness are further improved. The content of the mixed filler is more preferably 55 to 75% by volume and more preferably 60 to 75% by volume in the total volume of the total solid content of the epoxy resin composition from the viewpoint of increasing the thermal conductivity. .

  In addition, let the content rate (volume%) of the filler in this specification be the value calculated | required by following Formula.

  Filler content (volume%) = {((Dw / Dd) + (Ew / Ed)) / ((Aw / Ad) + (Bw / Bd) + (Cw / Cd) + (Dw / Dd) + ( Ew / Ed) + (Fw / Fd))} × 100

Here, each variable is as follows.
Aw: mass composition ratio of epoxy resin monomer (mass%)
Bw: mass composition ratio (% by mass) of curing agent
Cw: mass composition ratio (mass%) of curing accelerator (optional component)
Dw: mass composition ratio of alumina filler (mass%)
Ew: Mass composition ratio (mass%) of boron nitride filler
Fw: Mass composition ratio (% by mass) of other optional components (excluding organic solvents)
Ad: Specific gravity of epoxy resin monomer Bd: Specific gravity of curing agent Cd: Specific gravity of curing accelerator (optional component) Dd: Specific gravity of alumina filler Ed: Specific gravity of boron nitride filler Fd: Other optional components (excluding organic solvents) specific gravity

(Α-alumina filler)
The epoxy resin composition contains α-alumina. By using α-alumina as a filler, it is excellent in thermal conductivity, moldability, adhesiveness, and mechanical strength.

  The α-alumina filler may further contain alumina other than α-alumina as necessary. Examples of alumina other than α-alumina include γ-alumina, θ-alumina, δ-alumina, and the like, but from the viewpoint of thermal conductivity, it is preferably composed of only α-alumina. The shape of the alumina filler is preferably particulate. The shape of the alumina filler can be confirmed by a scanning electron microscope (SEM).

  The presence of α-alumina in the alumina filler can be confirmed by an X-ray diffraction spectrum. Specifically, according to the description in Japanese Patent No. 3759208, the presence of α-alumina can be confirmed using a peak peculiar to α-alumina as an index.

  The content of α-alumina in the alumina filler is preferably 80% by volume or more, more preferably 90% by volume or more, and 100% by volume from the viewpoint of thermal conductivity and fluidity. More preferably. When an alumina filler having a high α-alumina content is used, the higher-order structure forming force due to the epoxy resin monomer represented by the general formula (I) is large, and a better thermal conductivity tends to be obtained. is there. The content of α-alumina in the alumina filler can be confirmed by an X-ray diffraction spectrum.

  The α-alumina filler content in the epoxy resin composition occupies 50 to 90% by volume when the volume of all fillers is 100% by volume. If the α-alumina filler is 50% by volume or more in the total filler volume, the peel strength from the metal foil does not decrease, and if it is 90% by volume or less, the insulation is excellent. The α-alumina filler is more preferably 60 to 90% by volume, and further preferably 70 to 90% by volume in the total filler volume.

  The α-alumina filler may have a single peak or a plurality of peaks when a particle size distribution curve is drawn with the particle diameter on the horizontal axis and the frequency on the vertical axis. Good. By using the α-alumina filler having a plurality of peaks in the particle size distribution curve, the filling property of the α-alumina filler is further improved, and the thermal conductivity as the cured epoxy resin composition is further improved.

  When the α-alumina filler has a single peak when a particle size distribution curve is drawn, an average particle size corresponding to 50% volume cumulative from the small particle size side of the volume cumulative particle size distribution of the α-alumina filler The particle diameter (D50) is preferably from 0.1 to 50 μm, more preferably from 0.1 to 30 μm, from the viewpoint of thermal conductivity. Moreover, the α-alumina filler having a plurality of peaks in the particle size distribution curve can be constituted by combining two or more fillers having different average particle diameters (D50), for example.

  The average particle diameter (D50) of the α-alumina filler is measured using a laser diffraction method, and corresponds to the particle diameter at which the volume accumulation is 50% when the volume accumulation particle size distribution curve is drawn from the small particle diameter side. . The particle size distribution measurement using the laser diffraction method can be performed using a laser diffraction scattering particle size distribution measuring device (for example, LS230 manufactured by Beckman Coulter, Inc.).

  As an example of combining the two types of filler groups having different average particle sizes with respect to the combination of the α-alumina filler, the α-alumina filler (A) having an average particle size (D50) of 10 μm or more and 50 μm or less, And a mixed filler with an α-alumina filler (B) having an average particle diameter (D50) of ½ or less of the filler (A) and not less than 0.1 μm and less than 10 μm. The mixed filler is based on the total volume of α-alumina filler (100% by volume), α-alumina filler (A) is 60 to 90% by volume, and α-alumina filler (B) is 10 to 40% by volume (however, , Α-alumina fillers (A) and (B) are preferably 100% by volume.

  Moreover, when the case where three types of filler groups having different average particle sizes are combined is exemplified, an α-alumina filler (A ′) having an average particle size (D50) of 10 μm or more and 50 μm or less, and an average particle size (D50). α-alumina filler (B ′) which is ½ or less of α-alumina filler (A ′) and is 1 μm or more and less than 10 μm, and average particle diameter (D50) is ½ of α-alumina filler (B ′). Examples thereof include a mixed filler with an α-alumina filler (C ′) that is 0.1 μm or more and less than 1 μm. The mixed filler is based on the total volume of the α-alumina filler (100% by volume), the α-alumina filler (A ′) is 30 to 89% by volume, the α-alumina filler (B ′) is 10 to 40% by volume, And α-alumina filler (C ′) is 1 to 30% by volume (provided that the total volume% of fillers (A ′), (B ′), and (C ′) is 100% by volume). Is preferred.

  The average particle diameter (D50) of the α-alumina fillers (A) and (A ′) is the target resin sheet or laminate when the epoxy resin composition is applied to a resin sheet or laminate described later. The thickness of the cured epoxy resin composition layer, and when the epoxy resin composition is applied to a prepreg described later, the thickness of the target prepreg and the fineness of the fiber base material are appropriately selected according to each. It is preferred that

  When there is no other limitation, the average particle diameter of the fillers (A) and (A ′) is preferably as large as possible from the viewpoint of thermal conductivity. On the other hand, it is preferable to make the film thickness as thin as possible within a range in which necessary insulation is ensured from the viewpoint of thermal resistance. Therefore, the average particle diameter of the fillers (A) and (A ′) is preferably 10 to 50 μm, and more preferably 10 to 30 μm from the viewpoint of filler filling property, thermal resistance, and thermal conductivity.

(Boron nitride filler)
The epoxy resin composition includes boron nitride. By using boron nitride as a filler, it is excellent in thermal conductivity and electrical insulation.

The boron nitride is an aggregate of primary particles, and the average particle diameter (D50) of the aggregate is preferably 1 to 100 μm.
From the viewpoint of thermal conductivity, the boron nitride used is preferably an aggregate in which primary particles are aggregated in a round shape rather than a scaly or plate-like one. The shape of boron nitride can be confirmed by SEM.

  The content of the boron nitride filler in the epoxy resin composition occupies 10 to 50% by volume when the volume of all fillers is 100% by volume. If the boron nitride filler is 10% by volume or more of the total filler volume, the insulation is excellent, and if it is 50% by volume or less, the peel strength from the metal foil does not decrease. In addition, it is more preferable that the said boron nitride filler is 10-40 volume% in the whole filler volume, and it is still more preferable that it is 10-30 volume%.

  The boron nitride filler may have a single peak or a plurality of peaks when a particle size distribution curve having a particle diameter on the horizontal axis and a frequency on the vertical axis is drawn. . By using a boron nitride filler having a plurality of peaks in the particle size distribution curve, the filling property of the boron nitride filler is further improved, and the thermal conductivity and insulation as the cured epoxy resin composition are further improved.

  When the boron nitride filler has a single peak when drawing a particle size distribution curve, the average particle size is a particle size corresponding to 50% volume cumulative from the small particle size side of the volume cumulative particle size distribution of the boron nitride filler. (D50) is preferably 1 to 100 μm and more preferably 1 to 70 μm from the viewpoint of thermal conductivity. In addition, the boron nitride filler having a plurality of peaks in the particle size distribution curve can be constituted by combining two or more fillers having different average particle diameters (D50), for example.

  The average particle diameter (D50) of the boron nitride filler is measured using a laser diffraction method, as in the case of the α-alumina filler, and the volume cumulative particle size distribution curve is drawn when the volume cumulative particle size distribution curve is drawn from the small particle diameter side. Corresponds to a particle size of 50%.

  As an example of combining the two types of filler groups having different average particle sizes with respect to the combination of the boron nitride fillers, the boron nitride filler (D) having an average particle size (D50) of 10 μm or more and 100 μm or less, and the average A mixed filler with a boron nitride filler (E) having a particle size (D50) of ½ or less of the filler (D) and not less than 1 μm and less than 10 μm can be mentioned. The mixed filler is based on the total volume of the boron nitride filler (100% by volume), the boron nitride filler (D) is 60 to 90% by volume, and the boron nitride filler (E) is 10 to 40% by volume (however, boron nitride) The total volume% of the fillers (D) and (E) is preferably 100% by volume).

  Further, when combining three types of filler groups having different average particle diameters, boron nitride filler (D ′) having an average particle diameter (D50) of 10 μm or more and 100 μm or less, and an average particle diameter (D50) of nitriding are exemplified. Boron nitride filler (E ′) which is 1/2 or less of boron filler (D ′) and 5 μm or more and less than 10 μm, and average particle diameter (D50) is 1/2 or less of boron nitride filler (E ′) and 1 μm or more A mixed filler with a boron nitride filler (F ′) that is less than 5 μm can be mentioned. The mixed filler is based on the total volume of the boron nitride filler (100% by volume), the boron nitride filler (D ′) is 30 to 89% by volume, the boron nitride filler (E ′) is 10 to 40% by volume, and boron nitride. The filler (F ′) is preferably 1 to 30% by volume (provided that the total volume% of the fillers (D ′), (E ′), and (F ′) is 100% by volume).

  The average particle diameter (D50) of the boron nitride fillers (D) and (D ′) is a target curing in the resin sheet or laminate when the epoxy resin composition is applied to a resin sheet or laminate described below. When applying the epoxy resin composition to the film thickness of the epoxy resin composition layer and the prepreg described later, the film thickness of the target prepreg and the fineness of the fiber substrate are appropriately selected according to each. It is preferable.

  When there is no other limitation, the average particle diameter of the fillers (D) and (D ′) is preferably as large as possible from the viewpoint of thermal conductivity. On the other hand, it is preferable to make the film thickness as thin as possible within a range in which necessary insulation is ensured from the viewpoint of thermal resistance. Therefore, the average particle diameter of the fillers (D) and (D ′) is preferably 10 to 70 μm, and more preferably 10 to 60 μm from the viewpoint of filler filling property, thermal resistance, and thermal conductivity.

(Elastomer)
The epoxy resin composition preferably further contains an elastomer having at least a structural unit represented by the following general formula (IV) in the molecule. By including the elastomer having the structural unit represented by the general formula (IV), the dispersibility of the filler is further improved, and the flexibility is further improved in the B stage sheet described later. Moreover, in the resin sheet and prepreg described later, effects such as improvement in density and reduction in insulation due to reduction of internal voids can be obtained.

In the general formula (IV), R ⁴¹ , R ⁴² and R ⁴³ each independently represent a linear or branched alkyl group or a hydrogen atom. R ⁴⁴ represents a linear or branched alkyl group. n4 is an arbitrary positive integer indicating the number of structural units.

  The elastomer is preferably a homopolymer or copolymer derived from at least one monomer selected from the group consisting of (meth) acrylic acid and (meth) acrylic acid ester. In one embodiment of the present invention, it is preferable to use an acrylic resin copolymer mainly containing a structural unit represented by the general formula (IV) as the elastomer.

In general formula (IV), when any of R ⁴¹ , R ⁴² , or R ⁴³ is an alkyl group, from the viewpoint of imparting flexibility, the number of carbon atoms is preferably 1 to 12, and a low glass transition temperature ( From the viewpoint of Tg), the number of carbon atoms is more preferably 1-8. In a preferred embodiment of the present invention, R ⁴¹ and R ⁴² are each a hydrogen atom, R ⁴³ is a hydrogen atom or a methyl group, and more preferably R ⁴¹ , R ⁴² , and R ⁴³ are hydrogen atoms. is there.

In the general formula (IV), R ⁴⁴ is a linear or branched alkyl group. The alkyl group in R ⁴⁴ preferably has 2 to 16 carbon atoms from the viewpoint of imparting flexibility, and has 3 to 14 carbon atoms from the viewpoint of small inhibition of higher-order structure formation in the epoxy resin monomer. It is more preferable, and it is still more preferable that it is 4-12 from a viewpoint of acquisition and the ease of synthesis.

In addition, the elastomer preferably has a structural unit number of carbon atoms of the alkyl group represented by R ⁴⁴ is represented by two or more different formula (IV). For example, when the elastomer has two structural units represented by the general formula (IV), the carbon number of the alkyl group in one structural unit is 2 to 7 carbon atoms from the viewpoint of low Tg. Preferably, it is 3-6. Moreover, as for carbon number of the alkyl group in the other structural unit, it is preferable that carbon number is 8-16 from a viewpoint of softness | flexibility provision, and it is more preferable that it is 10-14.

  In general formula (IV), n4 is an arbitrary positive integer indicating the number of structural units. The number of structural units represented by n4 means the average value of the total number of structural units represented by the general formula (IV) contained in the elastomer molecule. n4 = 100 to 1000 is preferable, n4 = 100 to 500 is more preferable from the viewpoint of imparting flexibility, and n4 = 100 to 300 is still more preferable from the viewpoint of low Tg.

  By using an elastomer having a structural unit represented mainly by the general formula (IV), a soft structure (flexibility) can be imparted to the epoxy resin composition. Therefore, it is possible to improve the problems such as a decrease in flexibility of the sheet due to the high filling of the inorganic filler as seen in the conventional heat conductive sheet.

  The elastomer having at least a structural unit represented by the general formula (IV) in the molecule preferably further has at least one of a carboxy group and a hydroxy group in the molecule, and has a structural unit having at least one of a carboxy group and a hydroxy group. More preferably, it contains at least a structural unit having a carboxy group.

Examples of the monomer that can form a structural unit having a carboxy group include acrylic acid, methacrylic acid, maleic acid, itaconic acid, and the like. Among these, acrylic acid and methacrylic acid are preferable.
Moreover, as a monomer which can form the structural unit which has a hydroxyl group, the (meth) acrylic acid ester containing a C2-C20 hydroxyalkyl group can be mentioned, A C2-C6 hydroxyalkyl group is mentioned. It is preferable that it is a (meth) acrylic ester containing. Specific examples include hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, hydroxybutyl (meth) acrylate, and the like.

When a carboxy group or a hydroxyl group is present in the elastomer, they can undergo a crosslinking reaction with the epoxy resin monomer during the curing reaction, so that the crosslinking density is further improved, and as a result, the thermal conductivity can be further improved.
In addition, since the carboxy group releases hydrogen ions, it is easy to open the epoxy group during the curing reaction, thereby providing an effect of acting as a catalyst. Furthermore, since the carboxy group acts with the hydroxyl group on the filler surface, it brings about the effect of surface treatment on the filler. The effect of such surface treatment is that the wettability between the filler and the elastomer is improved, so that the viscosity of the epoxy resin composition (varnish) further containing a solvent tends to be lowered and the coating tends to be easy. Furthermore, the filler is more highly dispersed by the improvement of wettability, which contributes to the improvement of thermal conductivity.

  When the elastomer has at least one of a carboxy group and a hydroxy group, the content of the structural unit having at least one of a carboxy group and a hydroxy group contained in the elastomer is not particularly limited. From the viewpoint of filler dispersibility, the content of the structural unit having at least one of a carboxy group and a hydroxy group in the elastomer is preferably 10 to 30 mol% based on the entire elastomer molecule (100 mol%). More preferably, it is -28 mol%.

  The elastomer having at least a structural unit represented by the general formula (IV) in the molecule preferably further contains at least one amino group in the molecule, and more preferably contains at least one structural unit having an amino group. preferable. The amino group is preferably a secondary amino group or a tertiary amino group from the viewpoint of preventing moisture absorption. Further, from the viewpoint of improving thermal conductivity, an N-methylpiperidino group is particularly preferable. When an N-methylpiperidino group is present in the elastomer, the compatibility is remarkably improved by the interaction with a curing agent containing a novolac resin obtained by novolacizing a divalent phenol compound. Thus, when the acrylic monomer excellent in compatibility is added to an epoxy resin composition, the loss of heat conductivity becomes smaller. Further, the interaction between the N-methylpiperidino group and a curing agent containing a novolac resin obtained by novolacizing a divalent phenol compound exhibits a stress relaxation effect due to slippage between different molecules, and contributes to further improvement of the adhesive force. It will be.

  When the elastomer has an amino group, the content of the amino group contained in the elastomer is not particularly limited. From the viewpoint of compatibility, the content of the structural unit having an amino group in the elastomer is preferably 0.5 to 5 mol%, and more preferably 0.7 to 3.5 mol%.

  In one embodiment of the present invention, it is more preferable to use an acrylic elastomer containing a structural unit represented by the following general formula (V). By containing the acrylic elastomer containing the structural unit represented by the general formula (V), the flexibility of the B stage sheet, which is a semi-cured epoxy resin composition described later, is improved, and the internal voids in the resin sheet and prepreg described later are included. Effects such as density improvement and electrical insulation improvement due to the reduction can be obtained more remarkably.

In general formula (V), a, b, c, and d show the mol% of each structural unit in all the structural units, and are a + b + c + d = 90 mol% or more. R ⁵¹ and R ⁵² each independently represent a linear or branched alkyl group having a different carbon number. R ^{53 to} R ⁵⁶ each independently represent a hydrogen atom or a methyl group.

  In the general formula (V), a + b + c + d = 90 mol% or more, preferably 95 mol% or more, and more preferably 99 mol% or more.

In the acrylic elastomer represented by the general formula (V), the structural unit (hereinafter also referred to as “structural unit a”) present in the proportion of a can impart flexibility to the resin sheet, and has thermal conductivity. And compatibility with flexibility. Further, the structural unit present in the ratio of b (hereinafter also referred to as “structural unit b”) makes the flexibility of the resin sheet more preferable in the combination with the structural unit a shown above. Thus, the carbon number of the alkyl group represented by R ⁵¹ and R ⁵² in the structural units a and b that imparts a soft structure (flexibility) is not particularly limited. When the carbon number of the alkyl group is 16 or less, the glass transition temperature (Tg) of the acrylic elastomer does not become too high, and the flexibility improvement effect obtained by adding the acrylic elastomer to the epoxy resin composition is sufficiently obtained. Tend. On the other hand, when the carbon number of the alkyl group of R ⁵¹ and R ⁵² is 2 or more, the flexibility of the acrylic elastomer itself is further improved, and the flexibility effect obtained by adding the acrylic elastomer tends to be sufficiently obtained. In such a viewpoint, the carbon number of the alkyl group of R ⁵¹ and R ⁵² is preferably in the range of 2 to 16, more preferably in the range of 3 to 14, and still more preferably in the range of 4 to 12.

The alkyl groups represented by R ⁵¹ and R ⁵² have different carbon numbers. Although the difference in carbon number in R ⁵¹ and R ⁵² is not particularly limited, the difference in carbon number is preferably 4 to 10 and more preferably 6 to 8 from the viewpoint of the balance between flexibility and flexibility. .
Furthermore, from the viewpoint of the balance between flexibility and flexibility, R ⁵¹ has preferably 2 to 6 carbon atoms, R ⁵² preferably has 8 to 16 carbon atoms, and R ⁵¹ has 3 to 5 carbon atoms. More preferably, R ⁵² has 10 to 14 carbon atoms.

  In the general formula (V), the range of mol% of the structural units a and b is not particularly limited. Further, the ratio between the structural units a and b may be arbitrary. It is preferable to use an acrylic elastomer that includes a combination of structural units a and b, rather than any of structural units a and b. The combination of structural units a and b may increase the number of side chains and increase the flexibility of the acrylic elastomer, and may increase Tg. However, Tg can be controlled within a suitable range by appropriately adjusting the proportion of mol% of the structural units a and b in the acrylic elastomer.

  Specifically, for example, from the viewpoint of the flexibility and filler dispersibility of the resin sheet, the content of the structural unit a is preferably 50 to 85 mol%, and more preferably 60 to 80 mol%. Moreover, 2-20 mol% is preferable and, as for the content rate of the structural unit b, 5-15 mol% is more preferable. Furthermore, 4-10 are preferable and, as for the content ratio (a / b) of the structural unit a with respect to the structural unit b, 6-8 are more preferable.

In general formula (V), the presence of a carboxy group in the acrylic elastomer derived from a structural unit present in the proportion of c (hereinafter also referred to as “structural unit c”) improves thermal conductivity and filler. The effect of improving the wettability between the resin and the resin is obtained. Further, the presence of N-methylpiperidino group in the acrylic elastomer derived from the structural unit present in the proportion of d (hereinafter also referred to as “structural unit d”) improves compatibility and adhesion. An effect is obtained. These effects become more prominent when carboxy groups and N-methylpiperidino groups coexist in the acrylic elastomer. More specifically, the N-methylpiperidino group can accept hydrogen ions from a carboxy group and then allows interaction with a novolak resin, for example, included as a curing agent. Thus, the compatibility with the acrylic elastomer in the epoxy resin composition is improved by the interaction with the novolac resin. Further, the intramolecular interaction between the carboxy group and the N-methylpiperidino group contributes to the stress relaxation due to the low elasticity. This can be considered, for example, because the entire molecule of the acrylic elastomer has a curved structure instead of a linear structure. From such a viewpoint, in an embodiment of the acrylic elastomer represented by the general formula (V), the proportion of the structural units c and d is preferably in the range of 10 to 28 mol%, more preferably 14 to 28, respectively. In the range of mol%, more preferably in the range of 20 to 28 mol%, d is preferably in the range of 0.5 to 5 mol%, more preferably in the range of 0.7 to 3.5 mol%, still more preferably. It is in the range of 0.7 to 1.4 mol%.
Moreover, 0.01-0.5 are preferable, as for the content ratio (d / c) of the structural unit c with respect to the structural unit d, 0.03-0.3 are more preferable, and 0.035-0.25 are still more preferable.

R ^{53 to} R ⁵⁶ are each independently a hydrogen atom or a methyl group, but preferably at least one of R ⁵³ and R ⁵⁴ is a hydrogen atom and the other is a methyl group, R ⁵³ is a hydrogen atom and R ⁵⁴ is More preferred is a methyl group. Also preferably the other is a methyl group at least one hydrogen atom of the pair of R ⁵⁵ and R ^56, and more preferably R ⁵⁶ R ⁵⁵ is a hydrogen atom is a methyl group.

The acrylic elastomer having the structure represented by the general formula (V) may further include structural units other than the structural units a to d. There is no restriction | limiting in particular as structural units other than structural unit ad. Examples of the structural unit other than the structural units a to d include a structural unit derived from a (meth) acrylic acid ester containing a hydroxyalkyl group and a structural unit derived from a (meth) acrylic acid ester containing a tertiary amino group. Can do.
The content of structural units other than the structural units a to d in the acrylic elastomer is 10 mol% or less, preferably 5 mol% or less, and more preferably 1 mol% or less.

The weight average molecular weight of the acrylic elastomer is not particularly limited. Among these, from the viewpoint of thermal conductivity and flexibility, it is preferably 10,000 to 100,000, more preferably 10,000 to 50,000, and 10,000 to 30,000. Is more preferable. Furthermore, when the weight average molecular weight of the acrylic elastomer is within the above range, the dispersibility of the inorganic filler is further improved, and the viscosity of the epoxy resin composition tends to be further decreased.
The weight average molecular weight of the acrylic elastomer is measured by a normal method using GPC.

In the epoxy resin composition according to the present invention, the content of the acrylic elastomer is in the range of 0.1 to 50 parts by mass when the total mass of the epoxy resin components (epoxy resin monomer and curing agent) is 100 parts by mass. Preferably, it is the range of 1-20 mass parts, More preferably, it is the range of 1-10 mass parts.
When the content of the acrylic elastomer is 0.1 parts by mass or more, a decrease in thermal conductivity is further suppressed, and the adhesive force with the adherend tends to be further improved. On the other hand, when the amount is 50 parts by mass or less of the acrylic elastomer, a decrease in adhesive strength with the adherend is further suppressed, and the thermal conductivity tends to be further improved. Therefore, it becomes easy to express various characteristics in a well-balanced manner by adjusting the content of the acrylic elastomer within the above range.

(Silane coupling agent)
The epoxy resin composition preferably further includes at least one silane coupling agent. As an effect of adding a silane coupling agent, it plays the role of forming a covalent bond between the surface of the filler and the thermosetting resin surrounding it (equivalent to a binder agent), and the effect of transferring heat more efficiently, In addition, an effect of improving the insulation reliability can be obtained by preventing moisture from entering.

  It does not specifically limit as a kind of said silane coupling agent, It can select from a commercially available thing suitably. To reduce the compatibility between the epoxy resin monomer represented by the general formula (I) having a mesogenic group in the molecular structure and the curing agent, and the heat conduction deficiency at the interface between the cured product of the epoxy resin monomer and the filler. Considering this, in the present invention, it is preferable to use a silane coupling agent having at least one functional group selected from the group consisting of an epoxy group, an amino group, a mercapto group, a ureido group, and a hydroxyl group at the terminal.

  Specific examples of the silane coupling agent include 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, and 3-glycidoxypropylmethyldimethoxysilane. Silane coupling agents having an epoxy group such as 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane; 3-aminopropyltriethoxysilane, 3- (2-aminoethyl) aminopropyltrimethoxysilane, 3- Silane coupling agents having an amino group such as (2-aminoethyl) aminopropyltrimethoxysilane, 3-aminopropyltrimethoxysilane, 3-phenylaminopropyltrimethoxysilane; 3-mercaptopropyltrimethoxysilane, 3-mercapto bird Silane coupling agent having a ureido group such as 3-ureidopropyltriethoxysilane; silane coupling agent having a mercapto group such Tokishishiran the like. Moreover, the silane coupling agent oligomer (made by Hitachi Chemical Techno Service Co., Ltd.) represented by SC-6000KS2 can further be mentioned. These silane coupling agents may be used alone or in combination of two or more.

(Other ingredients)
The epoxy resin composition may further contain at least one organic solvent. By including an organic solvent, it can be easily adapted to various molding processes. The organic solvent can be appropriately selected from commonly used organic solvents. Specific examples include alcohol solvents, ether solvents, ketone solvents, amide solvents, aromatic hydrocarbon solvents, ester solvents, nitrile solvents, sulfoxide solvents, and the like. Specific examples of the organic solvent include alcohol solvents such as methanol, ethanol and isopropanol; ether solvents such as ethyl ether, iso-propyl ether, n-butyl ether, n-hexyl ether, 2-ethylhexyl ether, ethylene oxide and ethylene glycol monomethyl ether. Ketone solvents such as methyl isobutyl ketone, cyclohexanone and methyl ethyl ketone; amide solvents such as dimethylacetamide, dimethylformamide and N-methyl-2-pyrrolidone; aromatic hydrocarbon solvents such as benzene, toluene and xylene; γ-butyrolactone, etc. Nitrile solvents such as acetonitrile; sulfoxide solvents such as dimethyl sulfoxide and sulfolane; and the like. These may be used alone or as a mixed solvent using two or more kinds in combination.

  The epoxy resin composition can contain other components as needed in addition to the above components. Examples of other components include a dispersant. Examples of the dispersant include Ajinomoto Finetech Co., Ltd. Ajisper series, Enomoto Kasei Co., Ltd. HIPLAAD series, Kao Corporation homogenol series, and the like. These may be used alone or in combination of two or more.

<Semi-cured epoxy resin composition>
The semi-cured epoxy resin composition of the present invention is derived from the epoxy resin composition, and is obtained by semi-curing the epoxy resin composition. For example, when the semi-cured epoxy resin composition is molded into a sheet shape, the handleability is improved as compared with a resin sheet made of an epoxy resin composition that is not semi-cured.

Here, the semi-cured epoxy resin composition means that the viscosity of the semi-cured epoxy resin composition is 10 ⁴ to 10 ⁵ Pa · s at 25 to 30 ° C., and 10 ² to 10 at 100 ° C. ^It has a feature of lowering to ³ Pa · s. Moreover, the cured epoxy resin composition after curing described later does not melt by heating. The viscosity is measured by dynamic viscoelasticity measurement (DMA) (for example, ARES-2KSTD manufactured by T.A. Instruments). The measurement conditions are a frequency of 1 Hz, a load of 40 g, a temperature increase rate of 3 ° C./min, and a shear test.

  Examples of the semi-curing treatment include a method of heating the epoxy resin composition at a temperature of 100 to 200 ° C. for 1 to 30 minutes.

<Curing epoxy resin composition>
The cured epoxy resin composition of the present invention is derived from the epoxy resin composition, and is obtained by curing the epoxy resin composition.

The cured epoxy resin composition can be produced by curing the uncured epoxy resin composition or the semi-cured epoxy resin composition. Although the method of the said hardening process can be suitably selected according to the structure of an epoxy resin composition, the objective of a cured epoxy resin composition, etc., it is preferable that they are a heating and a pressurization process.
For example, a cured epoxy resin composition can be obtained by heating an uncured epoxy resin composition or the semi-cured epoxy resin composition at 100 to 250 ° C. for 1 to 10 hours, preferably 130 to 230 ° C. for 1 to 8 hours. can get.

<Resin sheet>
The resin sheet of the present invention is formed by molding the epoxy resin composition into a sheet shape. The said resin sheet can be manufactured by providing the said epoxy resin composition on a release film, for example, and removing the solvent contained as needed.

  The thickness of the resin sheet is not particularly limited and can be appropriately selected according to the purpose. For example, the thickness of the resin sheet can be 50 to 500 μm, and is preferably 100 to 300 μm from the viewpoints of thermal conductivity, insulation, and flexibility.

  The resin sheet is a varnish-like epoxy resin composition (hereinafter referred to as “resin varnish”) prepared by adding an organic solvent such as methyl ethyl ketone or cyclohexanone to the epoxy resin composition on a release film such as a PET film. Can be produced by removing at least a part of the organic solvent from the coating layer and drying.

  The application of the resin varnish can be performed by a known method. Specific examples include methods such as comma coating, die coating, lip coating, and gravure coating. Examples of the coating method for forming the epoxy resin composition layer to a predetermined thickness include a comma coating method in which an object to be coated is passed between gaps, and a die coating method in which a resin varnish with a flow rate adjusted from a nozzle is applied. . For example, when the thickness of the coating layer (resin composition layer) before drying is 50 to 500 μm, it is preferable to use a comma coating method.

  The drying method is not particularly limited as long as at least a part of the organic solvent contained in the resin varnish can be removed, and can be appropriately selected from commonly used drying methods according to the organic solvent contained in the resin varnish. In general, a heat treatment method at about 80 to 180 ° C. can be mentioned.

  Since the epoxy resin composition layer of the resin sheet hardly undergoes a curing reaction, it has flexibility, but the sheet has poor flexibility, and in the state where the PET film as a support is removed, the sheet is self-supporting. It may be difficult to handle.

  The resin sheet is preferably a semi-cured epoxy resin composition obtained by semi-curing an epoxy resin composition constituting the resin sheet. That is, the resin sheet is preferably a B stage sheet that is further heat-treated until it is in a semi-cured state (B stage state). Since the resin sheet is composed of a semi-cured epoxy resin composition obtained by semi-curing the epoxy resin composition, the resin sheet is excellent in thermal conductivity, electrical insulation, and peel strength from the metal foil, and is a B stage sheet. Excellent flexibility and pot life.

Here, the B-stage sheet has a viscosity of 10 ⁴ Pa · s to 10 ⁵ Pa · s at room temperature (25 to 30 ° C.), whereas 10 ² Pa · s to 10 ³ Pa at 100 ° C. -It has the characteristic which falls to s. Moreover, the cured epoxy resin composition after curing described later is not melted by heating. The viscosity is measured by DMA (frequency 1 Hz, load 40 g: temperature rising rate 3 ° C./min).

  The conditions for heat-treating the resin sheet are not particularly limited as long as the epoxy resin composition layer can be brought into a B-stage state, and can be appropriately selected according to the configuration of the epoxy resin composition. For the heat treatment, a heat treatment method selected from hot vacuum press, hot roll laminating and the like is preferred for the purpose of eliminating voids in the resin layer generated during coating. Thereby, a flat B stage sheet | seat can be manufactured efficiently.

  Specifically, for example, the epoxy resin composition is subjected to B stage by heating and pressurizing under a reduced pressure (for example, 1 kPa) at a temperature of 100 to 200 ° C. for 1 to 5 minutes at a press pressure of 1 to 10 MPa. It can be semi-cured to the state.

  It is preferable that after the two resin sheets obtained by applying the epoxy resin composition on the release film and drying are pasted together, the above heating and pressurizing processes are performed to semi-cure to the B stage state. At this time, it is desirable to bond the application surfaces (the surfaces opposite to the surfaces in contact with the release film in the epoxy resin composition layer formed by applying the epoxy resin composition to the release film). When the two sheets are bonded together in this way, both surfaces of the resulting B-stage resin sheet become flatter and the adhesion to the adherend becomes better, so that a laminate, metal board, wiring board, and Higher thermal conductivity when applied to power semiconductor devices.

  The thickness of the B-stage sheet can be appropriately selected according to the purpose, and can be, for example, 50 to 500 μm, and is 100 to 300 μm from the viewpoints of thermal conductivity, electrical insulation, and flexibility. Preferably there is.

  The solvent remaining rate in the B-stage sheet is preferably 2.0% by mass or less, more preferably 1.0% by mass or less, from the viewpoint of suppressing bubble formation due to outgas generation during curing. More preferably, it is 5 mass% or less.

  The solvent residual ratio is determined from the change in mass before and after drying when a B-stage sheet is cut into a 40 mm square and dried in a thermostat preheated to 190 ° C. for 2 hours.

  The B-stage sheet is excellent in fluidity. Specifically, the flow amount in the B stage sheet is preferably 110 to 150%, and more preferably 110 to 130%. This flow amount is an indicator of melt fluidity during thermocompression bonding. When the flow amount is 110% or more, sufficient embeddability can be obtained, and when it is 150% or less, generation of burrs due to excessive flow can be suppressed.

  The flow amount is as follows. When a sample obtained by punching a 200 mm thick B stage sheet into a 10 mm square was pressed for 1 minute under atmospheric pressure, at a temperature of 160 ° C., and at a press pressure of 1.6 MPa, Calculated as the area change rate. The area change rate is obtained from the change rate of the area (number of pixels) after taking an external projection image of the sample with a scanner of 300 DPI or more, binarizing with image analysis software (Adobe Photoshop).

  Flow amount (%) = (Area of B stage sheet after pressing) / (Area of B stage sheet before pressing)

The resin sheet may be a cured epoxy resin composition obtained by curing the epoxy resin composition. A resin sheet made of a cured epoxy resin composition can be produced by curing an uncured resin sheet or B-stage sheet. Although the method of the said hardening process can be suitably selected according to the structure of an epoxy resin composition, the objective of a cured epoxy resin composition, etc., it is preferable that they are a heating and a pressurization process.
For example, a resin sheet made of a cured epoxy resin composition can be obtained by heating an uncured resin sheet or B-stage sheet at 100 to 250 ° C. for 1 to 10 hours, preferably 130 to 230 ° C. for 1 to 8 hours. . Moreover, it is preferable to perform the said heating, applying a pressure of 1-10 Mpa.

  In addition, the following method is mentioned as an example of the method of manufacturing the resin sheet which consists of a cured epoxy resin composition which has high heat conductivity and high heat resistance. First, the B stage sheet is sandwiched so as to be in contact with the roughened surface of two copper foils (thickness 30 to 120 μm) each having a roughened surface, at a temperature of 130 to 230 ° C. for 3 to 10 minutes, a pressure of 1 Heating and pressurizing are performed at a press pressure of 10 MPa to bond the B stage sheet and the copper foil. Subsequently, the epoxy resin composition is cured by heating at 130 to 230 ° C. for 1 to 8 hours to obtain a resin sheet with copper foil. There is a method of removing a copper foil portion of the obtained resin sheet with copper foil by etching treatment to obtain a resin sheet made of a cured epoxy resin composition.

<Prepreg>
The prepreg of the present invention includes a fiber base material and the epoxy resin composition impregnated in the fiber base material.

  The fiber base material constituting the prepreg is not particularly limited as long as it is usually used when producing a metal foil-clad laminate or a multilayer wiring board, and is appropriately selected from fiber base materials such as woven fabrics and nonwoven fabrics that are usually used. Selected.

  The opening of the fiber base material is not particularly limited. From the viewpoint of thermal conductivity and electrical insulation, it is more preferable that the opening be an opening that is 5 times or more the particle diameter of the filler having the largest average particle diameter (D50) among the fillers.

  The material of the fiber base material is not particularly limited. Specifically, inorganic fibers such as glass, alumina, boron, silica alumina glass, silica glass, tyranno, silicon carbide, silicon nitride, zirconia, carbon, aramid, polyetheretherketone, polyetherimide, polyether Examples thereof include organic fibers such as sulfone and cellulose, and mixed papers thereof.

  Among these, a glass fiber woven fabric is preferably used as the fiber base material. Thereby, for example, when a wiring board is configured using prepreg, a wiring board that is flexible and can be arbitrarily bent can be obtained. Furthermore, it becomes possible to reduce the dimensional change of the wiring board accompanying the temperature change, moisture absorption, etc. in the manufacturing process.

  The thickness of the fiber base material is not particularly limited. From the viewpoint of imparting better flexibility, the thickness is more preferably 30 μm or less, and from the viewpoint of impregnation, it is preferably 15 μm or less. Although the minimum of the thickness of a fiber base material is not restrict | limited in particular, Usually, it is about 5 micrometers.

  The impregnation amount (content ratio) of the epoxy resin composition in the prepreg is preferably 50 to 99.9% by mass in the total mass of the fiber base material and the epoxy resin composition.

  The prepreg may be produced by impregnating a fiber base material with the epoxy resin composition prepared in a varnish form in the same manner as described above, and removing at least a part of the organic solvent by heat treatment at 80 to 180 ° C. it can.

  Moreover, there is no restriction | limiting in particular in the method of impregnating a fiber base material with an epoxy resin composition. For example, the method of apply | coating with a coating machine can be mentioned. Specifically, a vertical coating method in which a fiber base material is pulled through an epoxy resin composition, a horizontal coating method in which an epoxy resin composition is coated on a support film and then impregnated by pressing the fiber base material, etc. be able to. From the viewpoint of suppressing the uneven distribution of the filler in the fiber base material, the horizontal coating method is preferable.

  The prepreg in the present invention may be used after the surface is smoothed in advance by hot press treatment with a press, a roll laminator or the like before lamination or sticking. The method of the hot press treatment is the same as the method mentioned in the method for producing the B stage sheet. Further, the processing conditions such as the heating temperature, the degree of pressure reduction, and the pressing pressure in the hot pressurizing process of the prepreg are the same as the conditions mentioned in the heating and pressurizing process of the B stage sheet.

  The residual solvent ratio in the prepreg is preferably 2.0% by mass or less, more preferably 1.0% by mass or less, and further preferably 0.5% by mass or less.

  The solvent residual rate is obtained from the mass change before and after drying when the prepreg is cut into 40 mm square and dried in a thermostat preheated to 190 ° C. for 2 hours.

<Laminated plate>
The laminate in the present invention has an adherend and a semi-cured epoxy resin composition layer or a cured epoxy resin composition layer disposed on the adherend. The semi-cured epoxy resin composition layer and the cured epoxy resin composition layer are derived from at least one selected from the group consisting of an epoxy resin composition layer composed of the epoxy resin composition, the resin sheet, and the prepreg. It is at least one selected from the group consisting of a semi-cured epoxy resin composition layer and a cured epoxy resin composition layer.

  Examples of the adherend include a metal foil and a metal plate. The adherend may be attached to only one side of the semi-cured epoxy resin composition layer or the cured epoxy resin composition layer, or may be attached to both sides.

  The metal foil is not particularly limited, and can be appropriately selected from commonly used metal foils. Specifically, gold foil, copper foil, aluminum foil, etc. can be mentioned, and copper foil is generally used. The thickness of the metal foil is not particularly limited as long as it is 1 to 200 μm, and a suitable thickness can be selected according to the power to be used.

  Further, as the metal foil, nickel, nickel-phosphorus, nickel-tin alloy, nickel-iron alloy, lead, lead-tin alloy or the like is used as an intermediate layer, and a 0.5-15 μm copper layer and 10-10 A three-layer composite foil provided with a 150 μm copper layer, or a two-layer composite foil in which aluminum and copper foil are combined can also be used.

  The metal plate is preferably made of a metal material having high thermal conductivity and a large heat capacity. Specific examples include copper, aluminum, iron, alloys used for lead frames, and the like.

  The plate | board thickness of the said metal plate can be suitably selected according to a use. For example, the material of the metal plate can be selected according to the purpose, such as selecting aluminum when priority is given to weight reduction or workability, and selecting copper when priority is given to heat dissipation.

  In the laminated board, as a semi-cured epoxy resin composition layer or a cured epoxy resin composition layer, in a form having one layer derived from any one of the epoxy resin composition layer, the resin sheet, or the prepreg. There may be a form in which two or more layers are laminated. In the case of having two or more semi-cured epoxy resin composition layers or cured epoxy resin composition layers, two or more epoxy resin composition layers, two or more resin sheets, and two prepregs are used. Any form having at least one sheet may be used. Furthermore, you may have combining any 2 or more of the said epoxy resin composition layer, the said resin sheet, and the said prepreg.

  The laminated board in the present invention, for example, forms the epoxy resin composition layer by applying the epoxy resin composition on an adherend, and heats and pressurizes it to semi-cur the epoxy resin composition layer. Or it is obtained by making it harden | cure and sticking to a to-be-adhered material. Alternatively, it is obtained by preparing a laminate of the resin sheet or the prepreg on the adherend and heating and pressurizing it to make the resin sheet or the prepreg semi-cured or cured and to adhere to the adherend. It is done.

  The curing method for semi-curing or curing the epoxy resin composition layer, the resin sheet, and the prepreg is not particularly limited. For example, heat treatment and pressure treatment are preferable. The heating temperature in the heating and pressure treatment is not particularly limited. Usually, it is the range of 100-250 degreeC, Preferably it is the range of 130-230 degreeC. Moreover, the pressurization conditions in a heating and pressurizing process are not specifically limited. Usually, it is the range of 1-15 MPa, Preferably it is the range of 1-10 MPa. Moreover, a vacuum press is used suitably for a heating and pressurizing process.

  The thickness of the laminate is preferably 500 μm or less, and more preferably 100 to 300 μm. When the thickness is 500 μm or less, the flexibility is excellent and the occurrence of cracks during bending is suppressed, and when the thickness is 300 μm or less, this tendency is more apparent. Further, when the thickness is 100 μm or more, the workability is excellent.

<Metal substrate>
As an example of the laminated board, a metal substrate that can be used to produce a wiring board described later can be given.

The metal substrate is configured using a metal foil and a metal plate as an adherend in the laminated plate. Specifically, the metal substrate is configured by laminating the metal foil, the cured epoxy resin composition layer, and the metal plate in this order.
The details of the metal foil and the cured epoxy resin composition layer constituting the metal substrate are as described above.

  The metal plate is not particularly limited and can be appropriately selected from commonly used metal plates. Specifically, an aluminum plate, an iron plate, etc. can be mentioned. The thickness of the metal plate is not particularly limited. From the viewpoint of workability, the thickness is preferably 0.5 to 5 mm.

  Moreover, it is preferable that the said metal plate is cut | disconnected to the size to be used, after producing a larger size than necessary and mounting an electronic component from a viewpoint of improving productivity. Therefore, it is desirable that the metal plate used for the metal substrate is excellent in cutting workability.

  When aluminum is used as the metal plate, aluminum or an alloy mainly composed of aluminum can be selected as the material. Many types of aluminum or alloys containing aluminum as a main component are available depending on the chemical composition and heat treatment conditions. Among them, it is preferable to select a type having high workability such as easy cutting and excellent strength.

<Wiring board>
The wiring board of the present invention is formed by laminating a metal plate, a cured epoxy resin composition layer, and a wiring layer in this order. The cured epoxy resin composition layer is a cured epoxy resin composition layer derived from at least one selected from an epoxy resin composition layer composed of the epoxy resin composition, the resin sheet, and the prepreg.

  The said wiring board can be manufactured by carrying out circuit processing of the metal foil in the at least one metal foil in the resin cured body with metal foil as stated above, or a metal substrate. An ordinary photolithography method can be applied to the circuit processing of the metal foil.

  Preferred embodiments of the wiring board are, for example, the same as the wiring board described in paragraph No. 0064 of JP2009-214525A and the wiring boards described in paragraph Nos. 0056 to 0059 of JP2009-275086A. Can be mentioned.

<Power semiconductor device>
The resin sheet which is a sheet-like molded body of the epoxy resin composition of the present invention can be applied to, for example, a power semiconductor device. An example of a power semiconductor device configured using the resin sheet will be described with reference to the drawings. FIG. 1 is a schematic cross-sectional view showing an example of the configuration of a power semiconductor device. In FIG. 1, the resin sheet cured body 2 is disposed between the metal plate 6, the metal plate 6 in the semiconductor module in which the solder layer 10 and the semiconductor chip 8 are laminated in this order, and the heat dissipation base substrate 4. It is sealed with a sealing material 14. FIG. 2 is a schematic cross-sectional view showing another example of the configuration of the power semiconductor device. In FIG. 2, the resin sheet cured body 2 is disposed between the metal plate 6 and the heat dissipation base substrate 4 in the semiconductor module in which the metal plate 6, the solder layer 10, and the semiconductor chip 8 are laminated in this order. The base substrate 4 is molded with a mold resin 12.
Thus, the cured body of the resin sheet, which is a sheet-like molded body of the epoxy resin composition of the present invention, can be used as a heat radiation adhesive layer between the semiconductor module and the heat radiation base substrate as shown in FIG. It is. In addition, when the whole is molded as shown in FIG. 2, it can be used as a heat dissipation material between the heat dissipation base substrate and the metal plate.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. Unless otherwise specified, “part” and “%” are based on mass.

The material used for preparation of an epoxy resin composition and its abbreviation are shown below.
(Epoxy resin monomer)
Resin monomer A:

4- {4- (2,3-epoxypropoxy) phenyl} cyclohexyl 4- (2,3-epoxypropoxy) benzoate, epoxy equivalent: 212, production method: described in Patent Document 3.
・ YL6121H (Mitsubishi Chemical Corporation), epoxy equivalent 175, epoxy resin having biphenyl skeleton as liquid crystal epoxy resin

(Curing agent)
Curing agent 1 [catechol resorcinol novolak (preparation ratio: catechol / resorcinol = 5/95) resin, manufactured by Hitachi Chemical Co., Ltd.]

<Method for synthesizing curing agent 1>
A 3 L separable flask equipped with a stirrer, a cooler, and a thermometer was charged with 627 g of resorcinol, 33 g of catechol, 316.2 g of 37% by mass formaldehyde, 15 g of oxalic acid, and 300 g of water, and 100 ° C. while heating in an oil bath The temperature was raised to. The mixture was refluxed at around 104 ° C., and the reaction was continued at the reflux temperature for 4 hours. Thereafter, the temperature in the flask was raised to 170 ° C. while distilling off water. The reaction was continued for 8 hours while maintaining 170 ° C. After the reaction, concentration was performed under reduced pressure for 20 minutes, water in the system was removed, and a novolak resin as the target curing agent 1 was obtained.
When the structure of the obtained curing agent 1 was confirmed by FD-MS (Field Desorption Mass Spectrometry), it was represented by any one of the general formulas (III-1) to (III-4). All the structures were confirmed.

In addition, about the said hardening | curing agent 1, the measurement of the physical-property value was performed as follows.
The number average molecular weight (Mn) and the weight average molecular weight (Mw) were measured using a high performance liquid chromatography L6000 manufactured by Hitachi, Ltd. and a data analyzer C-R4A manufactured by Shimadzu Corporation. G2000HXL and G3000HXL manufactured by Tosoh Corporation were used as analytical GPC columns, the sample concentration was 0.2% by mass, tetrahydrofuran was used as the mobile phase, and measurement was performed 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 (Mn) and the weight average molecular weight (Mw) were measured in terms of polystyrene using the standard curve.

The hydroxyl equivalent was measured by acetyl chloride-potassium hydroxide titration method. The determination of the titration end point was performed by potentiometric titration rather than coloration with an indicator because the solution color was dark. Specifically, the hydroxyl group of the phenol resin to be measured is acetylated with acetyl chloride in a pyridine solution, the excess reagent is decomposed with water, and the acetic acid produced is titrated with a potassium hydroxide / methanol solution to measure the hydroxyl group equivalent. did.
The physical properties of the curing agent 1 are shown below.

A mixture containing a compound having a structure represented by at least one of the general formulas (III-1) to (III-4), wherein Ar ^{31 to} Ar ³⁴ are represented by the general formula (III-a) R ³¹ = OH, R ³² = R ³³ = H, a group derived from 1,2-dihydroxybenzene (catechol) or a group derived from 1,3-dihydroxybenzene (resorcinol), a low molecular diluent As a novolak resin composition containing a novolak resin (hydroxyl equivalent: 65, Mn: 422, Mw: 564) containing 35% by mass of a monomer component (resorcinol).

(Alumina filler)
AA-18 [α-alumina, manufactured by Sumitomo Chemical Co., Ltd., average particle diameter (D50): 18 μm]
AA-3 [α-alumina, manufactured by Sumitomo Chemical Co., Ltd., average particle size (D50): 3 μm]
AA-04 [α-alumina, manufactured by Sumitomo Chemical Co., Ltd., average particle diameter (D50): 0.4 μm]

(Boron nitride filler)
HP-40 [Aggregated boron nitride, manufactured by Mizushima Alloy Iron Co., Ltd., average particle size (D50): 20 to 50 μm]
PTX60 [Aggregated boron nitride, manufactured by Momentive, average particle diameter (D50): 55-60 μm]
Agglomerates 50 [Aggregated boron nitride, manufactured by 3M, average particle size (D50): 10 to 20 μm]

(Elastomer)
・ REB122-4:

  Made by Hitachi Chemical Co., Ltd., containing 50% by mass of ethyl lactate, production method: see JP-A-2010-106220.

(Additive)
[Curing accelerator]
・ TPP: Triphenylphosphine [silane coupling agent]
KBM-573: 3-phenylaminopropyltrimethoxysilane [manufactured by Shin-Etsu Chemical Co., Ltd.]

(Organic solvent)
・ MEK: Methyl ethyl ketone ・ CHN: Cyclohexanone

(Support)
・ PET film [Purex A53, manufactured by Teijin DuPont Films Ltd.]
Copper foil [Furukawa Electric Co., Ltd., thickness: 105 μm or 35 μm, GTS grade]

Example 1
<Preparation of epoxy resin composition>
7.52 parts by mass of resin monomer A, 2.31 parts by mass of curing agent 1, and 60.89 parts by mass of α-alumina filler (AA-18: 52.98 parts by mass, AA-04: 7.91 parts by mass) Part), 4.59 parts by mass of boron nitride filler HP-40, 0.08 parts by mass of TPP, 0.07 parts by mass of KBM-573, and 24.54 parts by mass of organic solvent (MEK: 18.41). (Mass part, CHN: 6.13 parts by mass) were mixed to obtain an epoxy resin varnish as an epoxy resin composition containing an organic solvent.

Density 1.20 g / cm ³ of a mixture of resin monomer A and the curing agent 1, the density of α- alumina filler as 3.97 g / cm ^3, and 2.20 g / cm ³ density of boron nitride filler, epoxy It was 68 volume% when the ratio of the mixed filler of (alpha)-alumina and boron nitride with respect to the total volume of a resin monomer, a hardening | curing agent, and a filler was computed.
Moreover, when the volume of all the fillers was 100 volume%, the ratio for which an alpha alumina filler occupied was 88 volume%.

<Preparation of semi-cured epoxy resin composition>
The epoxy resin varnish was coated on a PET film using an applicator so that the thickness after drying was about 250 μm, and then dried at room temperature (20 ° C. to 30 ° C.) for 5 minutes and further at 120 ° C. for 10 minutes. . Thereafter, hot pressing (pressing temperature: 150 ° C., vacuum degree: 1 kPa, pressing pressure: 5 MPa, pressing time: 1 minute) by a vacuum press, and a sheet-like semi-cured epoxy resin composition having a thickness of 200 μm I got a thing.

<Preparation of cured epoxy resin composition with copper foil>
After peeling off the PET film from the sheet-like semi-cured epoxy resin composition obtained above, two sheets of 105 μm thickness were used so that the mat surfaces of the two copper foils faced the semi-cured epoxy resin composition, respectively. The semi-cured epoxy resin composition was sandwiched between copper foils and vacuum thermocompression bonded (temperature: 180 ° C., degree of vacuum: 1 kPa, press pressure: 5 MPa, pressurization time: 5 minutes) with a vacuum press. Then, it heated at 180 degreeC on atmospheric pressure conditions for 4 hours, and obtained the cured epoxy resin composition with copper foil.

<Measurement of thermal conductivity>
The copper foil of the cured epoxy resin composition with copper foil obtained above was removed by etching to obtain a sheet-shaped cured epoxy resin composition. The obtained cured epoxy resin composition was cut into a 10 mm square and blackened with a graphite spray, and then the thermal diffusivity was evaluated by a xenon flash method (LFA447 nanoflash manufactured by NETZSCH). The thermal conductivity of the cured epoxy resin composition was determined from the product of this value, the density measured by the Archimedes method, and the specific heat measured by DSC (DSC Pyris 1 manufactured by Perkin Elmer). The obtained thermal conductivity results are shown in Table 1.
Thermal conductivity λ (W / (m · K)) = α × ρ × Cp
α: Thermal diffusivity (m ² / s)
ρ: Density (kg / cm ³ )
Cp: Specific heat (capacity) (kJ / (kg · K))

<Measurement of breakdown voltage>
The copper foil of the cured epoxy resin composition with copper foil obtained above was removed by etching to obtain a sheet-like cured epoxy resin composition, which was cut out with a size of 100 mm square or more to obtain a sample. Using a YST-243-100RHO manufactured by Yamayo Tester Co., Ltd., the sample was sandwiched between cylindrical electrodes with a diameter of 25 mm, and the dielectric breakdown voltage was measured in the air at a pressure increase rate of 500 V / s, room temperature (25 ° C.). Five or more points were measured, and the average value and the minimum value were obtained. The results obtained are shown in Table 1.

<Measurement of peel strength with metal foil>
When producing the cured epoxy resin composition with copper foil, the copper foil to be used was changed to one having a thickness of 35 μm on one side, and a cured epoxy resin composition with copper foil was produced.
The cured epoxy resin composition with copper foil obtained above was cut out in dimensions of 5 cm in length and 10 cm in width, and a copper foil having dimensions of 1 cm in width and 10 cm in length was left in the central portion on the surface to which a 35 μm copper foil was crimped. The copper foil etching was performed only on the surface to which the 35 μm copper foil was pressure-bonded so as to be in a state to obtain a sample. Using an autograph AG-X manufactured by Shimadzu Corporation, a 100N load cell was installed, and a 2 cm portion of a 10 cm long copper foil was picked with a dedicated jig and pulled at a pulling speed of 50 mm / s at room temperature. The peel strength was measured. From the obtained test force (N) -stroke (mm) graph, the average value and the minimum value were obtained. The results obtained are shown in Table 1.

(Example 2)
Resin monomer A is 7.83 parts by mass, curing agent 1 is 2.40 parts by mass, and α-alumina filler is 54.07 parts by mass (AA-18: 47.04 parts by mass, AA-04: 7.03 parts by mass). Part), 9.96 parts by mass of boron nitride filler HP-40, 0.08 parts by mass of TPP, 0.08 parts by mass of KBM-573, and 25.57 parts by mass of organic solvent (MEK: 19.18) (Mass part, CHN: 6.39 parts by mass) was mixed to obtain an epoxy resin varnish as an epoxy resin composition containing an organic solvent.

Density 1.20 g / cm ³ of a mixture of resin monomer A and the curing agent 1, the density of α- alumina filler as 3.97 g / cm ^3, and 2.20 g / cm ³ density of boron nitride filler, epoxy It was 68 volume% when the ratio of the mixed filler of (alpha)-alumina and boron nitride with respect to the total volume of a resin monomer, a hardening | curing agent, and a filler was computed.
Moreover, when the volume of all the fillers was 100 volume%, the ratio for which an alpha alumina filler occupied was 75 volume%.

Using the epoxy resin varnish obtained above, a semi-cured epoxy resin composition and a cured epoxy resin composition were prepared in the same manner as in Example 1 except that the press pressure was changed to 10 MPa, and evaluated in the same manner as described above. did.
The results are shown in Table 1.

(Example 3)
7.13 parts by mass of resin monomer A, 2.64 parts by mass of curing agent 1, and 60.62 parts by mass of α-alumina filler (AA-18: 52.74 parts by mass, AA-04: 7.88 parts by mass) Part), boron nitride filler in total 4.57 parts by mass (PTX60: 3.43 parts by mass, Agglomerates 50: 1.14 parts by mass), TPP 0.08 parts by mass, KBM-573 0.07 parts by mass, REB122 -4 is mixed with 0.45 parts by mass, and an organic solvent is mixed in a total of 24.44 parts by mass (MEK: 18.33 parts by mass, CHN: 6.11 parts by mass), and an epoxy resin is prepared as an epoxy resin composition containing an organic solvent. A varnish was obtained.

Density 1.20 g / cm ³ of a mixture of resin monomer A and the curing agent 1, the density of α- alumina filler as 3.97 g / cm ^3, and 2.20 g / cm ³ density of boron nitride filler, epoxy The ratio of the mixed filler of α-alumina and boron nitride with respect to the total volume of the resin monomer, the curing agent, and the filler was calculated to be 67% by volume.
Moreover, when the volume of all the fillers was 100 volume%, the ratio for which an alpha alumina filler occupied was 88 volume.

A semi-cured epoxy resin composition and a cured epoxy resin composition were prepared in the same manner as in Example 1 except that the epoxy resin varnish obtained above was used, and evaluated in the same manner as described above.
The results are shown in Table 1.

(Comparative Example 1)
7.16 parts by mass of YL6121H, 2.66 parts by mass of curing agent 1, and 60.89 parts by mass of α-alumina filler (AA-18: 52.98 parts by mass, AA-04: 7.91 parts by mass) , 4.59 parts by mass of boron nitride filler HP-40, 0.08 parts by mass of TPP, 0.07 parts by mass of KBM-573, and 24.55 parts by mass of organic solvent (MEK: 18.41 parts by mass) , CHN: 6.14 parts by mass) to obtain an epoxy resin varnish as an epoxy resin composition containing an organic solvent.

Density 1.20 g / cm ³ of a mixture of YL6121H the curing agent 1, alpha-alumina filler density 3.97 g / cm ^3, and the density of the boron nitride filler as 2.20 g / cm ^3, an epoxy resin monomer The ratio of the mixed filler of α-alumina and boron nitride relative to the total volume of the curing agent and filler was calculated to be 68% by volume.
Moreover, when the volume of all the fillers was 100 volume%, the ratio for which an alpha alumina filler occupied was 88 volume%.

A semi-cured epoxy resin composition and a cured epoxy resin composition were prepared in the same manner as in Example 1 except that the epoxy resin varnish obtained above was used, and evaluated in the same manner as described above.
The results are shown in Table 1.

(Comparative Example 2)
Resin monomer A is 7.34 parts by mass, curing agent 1 is 2.13 parts by mass, and α-alumina filler is a total of 66.72 parts by mass (AA-18: 44.04 parts by mass, AA-3: 16.01 parts by mass). Parts, AA-04: 6.67 parts by mass), 0.07 parts by mass of TPP, 0.07 parts by mass of KBM-573, and 23.67 parts by mass of organic solvent (MEK: 17.75 parts by mass, (CHN: 5.92 parts by mass) was mixed to obtain an epoxy resin varnish as an epoxy resin composition containing an organic solvent.

Density 1.20 g / cm ³ of a mixture of resin monomer A and the curing agent 1, the density of α- alumina filler as 3.97 g / cm ^3, relative to the total volume of the curing agent and α- alumina filler with epoxy resin monomer The proportion of α-alumina filler was calculated and found to be 68% by volume.

A semi-cured epoxy resin composition and a cured epoxy resin composition were prepared in the same manner as in Example 1 except that the epoxy resin varnish obtained above was used, and evaluated in the same manner as described above.
The results are shown in Table 1.

(Comparative Example 3)
8.17 parts by mass of resin monomer A, 2.37 parts by mass of curing agent 1, and 16.52 parts by mass of α-alumina filler (AA-3: 8.26 parts by mass, AA-04: 8.26 parts by mass) Part), boron nitride filler HP-40 36.50 parts by mass, TPP 0.09 parts by mass, KBM-573 0.05 parts by mass, REB122-4 1.17 parts by mass, and organic solvent CHN 35 .13 parts by mass was mixed to obtain an epoxy resin varnish as an epoxy resin composition containing an organic solvent.

Density 1.20 g / cm ³ of a mixture of resin monomer A and the curing agent 1, the density of α- alumina filler as 3.97 g / cm ^3, and 2.20 g / cm ³ density of boron nitride filler, epoxy It was 68 volume% when the ratio of the mixed filler of (alpha)-alumina and boron nitride with respect to the total volume of a resin monomer, a hardening | curing agent, and a filler was computed.
Moreover, when the volume of all the fillers was 100 volume%, the ratio for which an alpha alumina filler occupied was 20 volume%.

A semi-cured epoxy resin composition and a cured epoxy resin composition were prepared in the same manner as in Example 1 except that the press pressure was changed to 15 MPa using the epoxy resin varnish obtained above, and evaluated in the same manner as described above. did.
The results are shown in Table 1.

From Table 1, Comparative Example 1 is an example in which an epoxy resin having a biphenyl skeleton as a liquid crystal epoxy resin is used as an epoxy resin monomer, and has lower thermal conductivity than the epoxy resin monomer of the general formula (I) used in the present invention, The dielectric breakdown voltage is also slightly reduced. In Comparative Examples 2 and 3, 100% by volume of α-alumina (comparative example 2), and 20% by volume of α-alumina in which the proportion of the volume of α-alumina in the volume of all fillers is outside the range of 50 to 90% by volume ( In the case of Comparative Example 3), when α-alumina is 100% by volume, the peel strength is high, but the thermal conductivity and the dielectric breakdown voltage are low. When α-alumina is 20% by volume, the thermal conductivity and the dielectric breakdown voltage are increased, but the peel strength is remarkably lowered.
When the epoxy resin monomer represented by the general formula (I) of the present invention and a specific curing agent are used and the volume of all fillers contained in the epoxy resin composition is 100% by volume, the volume of α-alumina occupies. The cured epoxy resin compositions of Examples 1 to 3 obtained by curing an epoxy resin composition having a ratio of 50 to 90% by volume are more thermally conductive, insulating, and metal than Comparative Examples 1 to 3. It can be seen that the peel strength is at a high level with a good balance.

2 Resin sheet cured body 4 Heat radiation base substrate 6 Metal plate 8 Semiconductor chip 10 Solder layer 12 Mold resin 14 Sealing material

Claims (17)

An epoxy resin composition comprising an epoxy resin monomer represented by the following general formula (I), a curing agent containing a novolak resin obtained by novolacizing a divalent phenol compound, and a mixed filler of α-alumina and boron nitride. Is a thing,
The epoxy resin composition whose ratio which the volume of (alpha) -alumina occupies is 50-90 volume% when the volume of all the fillers contained in the said epoxy resin composition is 100 volume%.

[In General Formula (I), R ^{1 to} R ⁴ each independently represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms]   The epoxy resin composition according to claim 1, wherein the boron nitride is an aggregate of primary particles, and an average particle diameter (D50) of the aggregate is 1 to 100 μm.   The epoxy resin composition according to claim 1, wherein the α-alumina has a particle shape and an average particle diameter (D50) of 0.1 to 50 μm. The epoxy resin according to any one of claims 1 to 3, wherein the curing agent is a novolak resin containing a compound having a structural unit represented by the following general formula (II-1) or (II-2). Composition.

[In General Formulas (II-1) and (II-2), R ²¹ and R ²⁴ each independently represents an alkyl group, an aryl group, or an aralkyl group. R ²² , R ²³ , R ²⁵ , and R ²⁶ each independently represent a hydrogen atom, an alkyl group, an aryl group, or an aralkyl group. m21 and m22 each independently represent an integer of 0-2. n21 and n22 each independently represent an integer of 1 to 7] The said hardening | curing agent is a novolak resin containing the compound which has a structure represented by at least 1 selected from the group which consists of the following general formula (III-1)-(III-4). The epoxy resin composition according to any one of the above.

[In General Formulas (III-1) to (III-4), m31 to m34 and n31 to n34 each independently represent a positive integer. Ar ^{31 to} Ar ³⁴ each independently represent a group represented by the following general formula (III-a) or a group represented by the following general formula (III-b)]

[In the general formulas (III-a) and (III-b), R ³¹ and R ³⁴ each independently represent a hydrogen atom or a hydroxyl group. R ³² and R ³³ each independently represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms]   The epoxy resin composition according to any one of claims 1 to 5, wherein the curing agent has a content ratio of a monomer that is a phenol compound constituting the novolak resin of 5 to 80% by mass.   The epoxy resin composition according to any one of claims 1 to 6, wherein a content of the mixed filler is 50 to 80% by volume in the entire volume. Furthermore, the epoxy resin composition of any one of Claims 1-7 containing the elastomer which has a structural unit represented by the following general formula (IV).

[In General Formula (IV), R ⁴¹ , R ⁴² , and R ⁴³ each independently represent a linear or branched alkyl group or a hydrogen atom. R ⁴⁴ represents a linear or branched alkyl group. n4 represents an arbitrary positive integer] The epoxy resin composition according to claim 8, wherein the elastomer contains an acrylic elastomer containing a structural unit represented by the following general formula (V).

[In General Formula (V), a, b, c, and d represent the mol% of each structural unit in all structural units, and a + b + c + d = 90 mol% or more. R ⁵¹ and R ⁵² each independently represent a linear or branched alkyl group having a different carbon number. R ^{53 to} R ⁵⁶ each independently represent a hydrogen atom or a methyl group]   The semi-hardened epoxy resin composition which is a semi-hardened body of the epoxy resin composition of any one of Claims 1-9.   A cured epoxy resin composition, which is a cured product of the epoxy resin composition according to any one of claims 1 to 9.   The resin sheet which is a sheet-like molded object of the epoxy resin composition of any one of Claims 1-9.   The prepreg which has a fiber base material and the epoxy resin composition of any one of Claims 1-9 impregnated in the said fiber base material.   From the adherend and the epoxy resin composition according to any one of claims 1 to 9, the resin sheet according to claim 12, and the prepreg according to claim 13 disposed on the adherend. A laminate having a semi-cured epoxy resin composition layer that is at least one semi-cured material selected from the group consisting of, or a cured epoxy resin composition layer that is a cured product.   At least 1 hardening selected from the group which consists of metal foil, the epoxy resin composition of any one of Claims 1-9, the resin sheet of Claim 12, and the prepreg of Claim 13. A metal substrate in which a cured epoxy resin composition layer as a body and a metal plate are laminated in this order.   At least 1 hardening selected from the group which consists of a metal plate, the epoxy resin composition of any one of Claims 1-9, the resin sheet of Claim 12, and the prepreg of Claim 13. A wiring board in which a cured epoxy resin composition layer, which is a body, and a wiring layer are laminated in this order.   The semiconductor module in which the metal plate, the solder layer, and the semiconductor chip are laminated in this order, the heat radiating member, and the metal plate and the heat radiating member in the semiconductor module are disposed between the metal plate and the heat radiating member. A power semiconductor device comprising a cured product of the epoxy resin composition according to the item.

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