WO2019059384A1

WO2019059384A1 - Thick copper circuit with attached protective material

Info

Publication number: WO2019059384A1
Application number: PCT/JP2018/035213
Authority: WO
Inventors: 格山浦; 東哲姜; 片木　秀行; 高橋　裕之; 戸川　光生; 真司天沼
Original assignee: 日立化成株式会社
Priority date: 2017-09-22
Filing date: 2018-09-21
Publication date: 2019-03-28
Also published as: TW201922909A

Abstract

This thick copper circuit with attached protective material comprises: thick copper circuits; and a protective material disposed in spaces between the thick copper circuits and containing 55 vol% to 95 vol% of an inorganic filler.

Description

Thick copper circuit with protective material

The present disclosure relates to thick copper circuits with protective material.

2. Description of the Related Art With the progress of miniaturization and high functionalization of electronic devices, printed circuit boards are widely used as circuit boards capable of mounting electronic components on a substrate at high density.

On the other hand, with the diversification of use environments of electronic devices, an increase (increase in current) of current capacity of a circuit board is required. As a method of increasing the current of the circuit board, a method of producing a circuit for large current (such as a thick copper circuit) using a metal member previously processed into a circuit state has been proposed (see, for example, Patent Document 1) . In Patent Document 1, as a method of producing a circuit for large current, a conductive circuit is inserted into an insulating material made of glass polyimide resin punched into a shape of the conductive circuit, and mounted on a metal substrate through an insulating layer. A method of making a high current circuit board is described.

Japanese Patent Application Laid-Open No. 6-169148

In a large current circuit, soldering (reflow treatment) is performed at a high temperature (for example, about 285 ° C.) in the mounting process. At this time, particularly in a thick copper circuit using copper as a circuit, the circuit may be deformed due to the high coefficient of thermal expansion of copper. Therefore, particularly in thick copper circuits, it is required to suppress circuit deformation in the mounting process. However, for example, in the method of fitting the circuit into the insulating material made of glass polyimide resin as in Patent Document 1, the deformation of the circuit can not be sufficiently suppressed, and peeling of the fitting member may occur.
This indication makes it a subject to provide a thick copper circuit with a protection material in which modification of a circuit was controlled in view of the above-mentioned situation.

The specific means for achieving the said subject are as follows.

<1> A thick copper circuit with a protective material, comprising: a thick copper circuit; and a protective material disposed in a space between the thick copper circuits and containing 55% by volume to 95% by volume of an inorganic filler.
<2> The thick copper circuit with a protective material according to <1>, wherein the protective material is a resin composition or a cured product thereof.
<3> The protective copper circuit with a protective material according to <2>, wherein the resin composition is an epoxy resin composition containing an epoxy resin, a curing agent, and the inorganic filler.
<4> The thick copper circuit with a protective material according to <3>, wherein the epoxy resin includes an epoxy resin having a mesogen skeleton.
The thick copper circuit with a protective material as described in <4> whose phase transition temperature which carries out phase transition to the liquid crystal phase in the epoxy resin which has <5> above-mentioned mesogenic frame structure is 140 degrees C or less.
<6> The thick copper circuit with a protective material according to <4> or <5>, wherein the epoxy resin having a mesogen skeleton includes a reaction product of a phenol compound and an epoxy compound having a mesogen skeleton.
The thick copper circuit with a protective material as described in <6> in which the epoxy compound which has <7> said mesogen frame | skeleton contains the compound represented with the following general formula (I-0).

(In the general formula (I-0), R ¹ to R ⁴ each independently represent a hydrogen atom or an alkyl group having 1 to 3 carbon atoms.)

<8> The protective copper circuit with a protective material according to any one of <3> to <7>, wherein the curing agent contains an amine curing agent.
<9> The thick copper circuit with a protective material according to <8>, wherein the amine curing agent comprises 4,4′-diaminodiphenyl sulfone.
<10> The thick copper circuit with a protective material according to any one of <2> to <9>, wherein the protective material is a transfer molded product of the resin composition.
<11> The thick copper circuit with protective material according to any one of <1> to <10>, wherein the protective material is further disposed around the thick copper circuit.
<12> The protective copper circuit with a protective material according to any one of <1> to <11>, further including an insulating layer in the thickness direction of the thick copper circuit.

According to the present disclosure, a thick copper circuit with a protective material in which deformation of the circuit is suppressed is provided.

It is a schematic sectional drawing of an example of the thick copper circuit with a protective material. It is a schematic sectional drawing of an example of the thick copper circuit with a protective material. It is a schematic sectional drawing of an example of the thick copper circuit with a protective material. It is a schematic sectional drawing of an example of the thick copper circuit with a protective material. It is a figure which shows an example of the graph obtained by the differential scanning calorimetry (DSC) measurement of the epoxy resin which has mesogen frame | skeleton. FIG. 5 is a schematic plan view of an example of a protected thick copper circuit for describing “a volume of an entire space between thick copper circuits”.

Hereinafter, modes for carrying out the present invention will be described in detail. However, the present invention is not limited to the following embodiments. In the following embodiments, the constituent elements (including element steps and the like) are not essential unless otherwise specified. The same applies to numerical values and ranges thereof, and does not limit the present invention.

In the present disclosure, the term “step” includes, in addition to steps independent of other steps, such steps as long as the purpose of the step is achieved even if it can not be clearly distinguished from other steps. .
In the present disclosure, numerical values described before and after “to” are included in the numerical range indicated using “to” as the minimum value and the maximum value, respectively.
The upper limit value or the lower limit value described in one numerical value range may be replaced with the upper limit value or the lower limit value of the other stepwise description numerical value range in the numerical value range described stepwise in the present disclosure. . In addition, in the numerical range described in the present disclosure, the upper limit value or the lower limit value of the numerical range may be replaced with the value shown in the example.
In the present disclosure, each component may contain a plurality of corresponding substances. When a plurality of substances corresponding to each component are present in the composition, the content or content of each component is the total content or content of the plurality of substances present in the composition unless otherwise specified. Means quantity.
In the present disclosure, particles corresponding to each component may contain a plurality of types. When there are a plurality of particles corresponding to each component in the composition, the particle diameter of each component means the value for the mixture of the plurality of particles present in the composition unless otherwise specified.
In the present disclosure, the words “layer” or “film” mean that when the region in which the layer or film is present is observed, in addition to the case where the region is entirely formed, only a part of the region The case where it is formed is also included.
The term "laminate" in the present disclosure refers to stacking layers, two or more layers may be combined, and two or more layers may be removable.
When an embodiment of the present disclosure is described with reference to the drawings, the configuration of the embodiment is not limited to the configuration shown in the drawings. Further, the sizes of the members in the respective drawings are conceptual, and the relative relationship between the sizes of the members is not limited thereto.

<Thick copper circuit with protective material>
The protected thick copper circuit of the present disclosure comprises a thick copper circuit and a protective material disposed in the space between the thick copper circuit and containing 55% by volume to 95% by volume of an inorganic filler. The protected thick copper circuit of the present disclosure may have other configurations as needed.
According to the thick copper circuit with a protective material of the present disclosure, deformation of the circuit in the mounting process can be suppressed. Although the reason for this is not clear, it is considered as follows. In the thick protective copper circuit with a protective material of the present disclosure, the protective material contains 55% by volume to 95% by volume of the inorganic filler, and is excellent in mechanical strength. Further, the thermal expansion coefficient (CTE) of the protective material can be made close to the thermal expansion coefficient of the thick copper circuit. Therefore, even in the case of using a thick copper circuit having a high coefficient of thermal expansion, it is considered that deformation of the circuit in the mounting process can be suppressed.

1 to 4 each show a schematic cross-sectional view of an example of a thick copper circuit with a protective material. The protected thick copper circuit 10 has a thick copper circuit 12 and a protective material 14 disposed in the space between the thick copper circuits. The protective material 14 contains an inorganic filler 16.
In the thick copper circuit 10 with protective material shown in FIGS. 1 and 2, the protective material 14 is disposed inside the thick copper circuit 12. Such a protective material-attached thick copper circuit 10 can be manufactured, for example, by disposing a protective material in the space of the thick copper circuit processed into a shape having an outer frame.
In the thick copper circuit 10 with protective material shown in FIGS. 3 and 4, the protective material is disposed on the inside and the outside of the thick copper circuit 12. Such a thick copper circuit 10 can be produced, for example, by disposing a protective material on the inside and the outside of the thick copper circuit processed into a shape having no outer frame. If the protective material is disposed on the inner side and the outer side of the thick copper circuit, the thick copper circuit is pressed by the protective material, so the adhesion between the protective material and the thick copper circuit is further improved, and the peeling is performed. Tend to be more restrained.

The thermal expansion coefficient is the difference between the amount of thermal expansion of the measurement sample and that of the standard sample when the temperature is raised at a constant rate using a thermomechanical analyzer (for example, TMAQ400 manufactured by TA Instruments Japan Ltd.) Can be obtained by measuring the amount of thermal expansion of the measurement sample. The measurement conditions can be set, for example, as follows.
Load: 20g
Measurement temperature: 30 ° C to 280 ° C
Heating temperature: 5 ° C / min

The thick copper circuit with protective material of the present disclosure is disposed on a metal substrate through an insulating layer separately prepared or obtained or an insulating layer integrally formed with the thick copper circuit with protective material of the present disclosure, and a circuit board It can be done. The use in particular of a circuit board is not restrict | limited, It can use suitably in the field | areas, such as industrial equipment.

Hereinafter, each component of the thick copper circuit with a protective material of this indication is demonstrated.

(Thick copper circuit)
In the present disclosure, a thick copper circuit refers to a copper plate previously processed into a circuit state. The thick copper circuit may be purchased or manufactured. The thickness of the thick copper circuit is not particularly limited, and can be appropriately selected according to the application of the circuit board manufactured using the same. From the viewpoint of increasing the current of the circuit board, the thickness of the thick copper circuit is preferably 350 μm or more, more preferably 500 μm or more, and still more preferably 1000 μm or more. From the viewpoint of volume and weight, the thickness of the thick copper circuit may be, for example, 5000 μm or less.
When the above values differ depending on the location of the thick copper circuit, the arithmetic mean value of the measurement values obtained at five arbitrarily selected locations is taken as the above value.
The thickness of the circuit means the thickness of the circuit itself, and in the case where a part of the circuit is embedded in the adjacent member, the thickness of the embedded part is included in the thickness of the circuit.

The width and length of the circuit in the thick copper circuit are not particularly limited, and can be selected according to the application etc. of the circuit board manufactured using this. For example, it may be selected from the range of 350 μm to 70000 μm.

A thick copper circuit can be obtained, for example, by processing a copper plate into a circuit of a desired shape. The method of processing is not particularly limited, and can be selected from known methods such as punching and cutting. The thick copper circuit may be processed into a shape having an outer frame around the circuit, or may be processed into a shape without an outer frame, depending on the convenience of the processing process.

(Protective layer)
The protective material is disposed in the space between the thick copper circuits described above and contains 55% by volume to 95% by volume of the inorganic filler.
In the present disclosure, the “space between thick copper circuits” refers to an inner space sandwiched by one or more metal members of the thick copper circuit. The protective material may be disposed at the outer edge of the thick copper circuit as required.

In a thick copper circuit, the proportion of the protective material disposed in the space between the circuits varies depending on the shape of the thick copper circuit, the manufacturing conditions of the circuit board, and the like, and is not particularly limited. The protective material may be disposed in all of the space between the thick copper circuits or in part of the space. From the viewpoint of further improving the insulation reliability, the ratio of the protective material to the volume of the entire space between the thick copper circuits is preferably 70% or more, more preferably 80% or more, and 90% or more. It is further preferred that

In the present disclosure, "the volume of the entire space between thick copper circuits" means the volume obtained by multiplying the area of the spaces between thick copper circuits in the plan view of the thick copper circuits by the thickness of thick copper circuits. Do. For example, in the plan view of the thick copper circuit 12 exemplarily shown in FIG. 6, the area of the thick copper circuit obtained by subtracting the area occupied by the thick copper circuit 12 from the area obtained by multiplying the width a and the length b. The value obtained by multiplying the area of the space 18 between the thickness 18 and the thickness of the thick copper circuit 12 is referred to as “the volume of the entire space between the thick copper circuits”. In addition, in FIG. 6, the broken line has shown the extension line of the outermost side of the width direction of a thick copper circuit, and a length direction for convenience.

The thickness of the protective material may be the same as or different from the thickness of the thick copper circuit. The thickness is preferably 80% to 120%, more preferably 90% to 110%, and still more preferably 95% to 105% of the thickness of the thick copper circuit. When the above-mentioned value is different depending on the place of the protective material, the arithmetic mean value of the measurement values obtained at 5 arbitrarily selected places is taken as the above-mentioned value.

The protective material may be further disposed outside the thick copper circuit in addition to the space between the thick copper circuit. In this case, the protective material is preferably arranged around the thick copper circuit in addition to the space between the thick copper circuits. When the protective material is also disposed around the thick copper circuit, the adhesion between the protective material and the thick copper circuit is further improved, and the peeling tends to be further suppressed.

From the viewpoint of the handleability of the thick copper circuit, it is preferable that the protective material is integrated with the thick copper circuit (the thick copper circuit with protective material can be treated as a single sheet). For example, it is preferable that the protective material in the thick copper circuit with protective material be continuously provided from the space between the thick copper circuits to the outer edge. When the thick copper circuit and protective material in the thick copper circuit with protective material are integrated, the insulation reliability and moisture resistance reliability of the thick copper circuit obtained are excellent, and creeping discharge, partial discharge, tracking, migration, etc. occur. Tend to be suppressed.

The protective material contains an inorganic filler. The material of the inorganic filler is not particularly limited, and is preferably insulating. In the present disclosure, the “insulating property” of the inorganic filler refers to the property that the inorganic filler itself does not flow current even when a voltage of about several hundred volts to several thousand volts is applied, and the most energy occupied by electrons. It is a property that the high valence band to the next band (conduction band) above it are separated by a large energy gap.

Specific examples of the material of the inorganic filler include boron nitride, alumina, silica, aluminum nitride, magnesium oxide, silicon oxide, aluminum hydroxide, barium sulfate and the like. Among them, silica is preferable from the viewpoint of more suitably adjusting the thermal expansion coefficient of the protective material. From the viewpoint of fluidity, thermal conductivity and electrical insulation, at least one selected from the group consisting of magnesium oxide and alumina is preferred. Moreover, you may further contain a boron nitride, a silica, aluminum nitride etc. in the range which does not prevent a fluidity.

The total proportion of at least one inorganic filler selected from the group consisting of magnesium oxide and alumina in the inorganic filler is preferably 50% by mass or more, and more preferably 80% by mass or more. It is more preferable that it is 90 mass% or more.

The shape of the inorganic filler is not particularly limited, and examples thereof include powder, sphere, and fiber. A spherical shape is preferable from the viewpoint of flowability at molding and mold abradability.

The inorganic filler may be used alone or in combination of two or more. In addition, “two or more types of inorganic fillers are used in combination” means, for example, when two or more types of inorganic fillers having the same component and different average particle sizes are used, the inorganic particles having the same average particle size but different components are used. The case where it uses more than a kind, and the case where two or more kinds of inorganic fillers from which an average particle diameter and a kind differ are used are mentioned.

The inorganic 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. By using an inorganic filler having a plurality of peaks in the particle size distribution curve, the filling property of the inorganic filler is improved, and the thermal conductivity of the cured product is improved.

When the inorganic filler has a single peak when the particle size distribution curve is drawn, the volume average particle size (D50) corresponding to 50% of the cumulative particle size distribution of the inorganic filler from the small particle size side is From the viewpoint of thermal conductivity, 0.1 μm to 100 μm is preferable, and 0.1 μm to 70 μm is more preferable. The volume average particle size of the inorganic filler can be measured using a laser diffraction method, and can be measured using a laser diffraction scattering particle size distribution measuring apparatus (for example, LS230 manufactured by Beckman Coulter, Inc.).

In addition, the inorganic filler having a plurality of peaks in the particle size distribution curve can be configured, for example, by combining two or more types of inorganic fillers having different volume average particle diameters.

The content of the inorganic filler in the protective material is 55% by volume to 95% by volume based on the total volume of the protective material. From the viewpoint of thermal conductivity, moldability, mechanical strength and the like, the content of the inorganic filler is preferably 60% by volume to 95% by volume, and more preferably 70% by volume to 85% by volume. If the content of the inorganic filler is 55% by volume or more, high thermal conductivity tends to be achieved. On the other hand, when the content of the inorganic filler is 95% by volume or less, the formability tends to be good.

The volume based content of the inorganic filler in the protective material is measured as follows.
The protective material is fired in air at 800 ° C. for 5 hours, and after the resin content is decomposed and burned and removed, the mass (Wf) of the remaining inorganic filler at 25 ° C. is measured. The density (df) of the inorganic filler at 25 ° C. is then determined using an electronic densitometer or a pycnometer. Next, the density (dp) of the protective material at 25 ° C. is measured in the same manner. Next, the volume (Vc) of the protective material and the volume (Vf) of the remaining inorganic filler are determined, and the volume of the remaining inorganic filler is divided by the volume of the protective material as shown in (equation 1) to obtain inorganic It is determined as the volume ratio of filler (Vr).

(Formula 1)
Vp = Wp / dp
Vf = Wf / df
Vr = Vf / Vp

Vp: volume of protective material (cm ³ )
Wp: Weight of protective material (g)
dp: Density of protective material (g / cm ³ )
Vf: Volume of inorganic filler (cm ³ )
Wf: mass of inorganic filler (g)
df: density of inorganic filler (g / cm ³ )
Vr: volume ratio of inorganic filler

The content basis of the inorganic filler in the protective material on a mass basis is not particularly limited, and can be appropriately adjusted according to the type of the inorganic filler and the like. For example, when the inorganic filler is alumina, the content of the inorganic filler in the protective material is preferably 80% by mass to 99% by mass, and more preferably 85% by mass to 98% by mass. More preferably, it is 90% by mass to 95% by mass.

The protective material is preferably a resin composition or a cured product thereof. When the protective material is a resin composition or a cured product thereof, the resin composition is not particularly limited as long as it is a resin composition containing an inorganic filler. In particular, the protective material is preferably a transfer molded product of a resin composition.

When the protective material is a resin composition or a cured product thereof, the resin used for the resin portion is not particularly limited. Examples thereof include thermosetting resins such as epoxy resin, phenol resin, urea resin, melamine resin, urethane resin, silicone resin, unsaturated polyester resin, acrylic resin, imide resin, and amidimide resin. The resin used for the resin part may be one type or two or more types. From the viewpoint of electrical insulation and adhesiveness, the resin used for the resin portion preferably contains at least one selected from the group consisting of an epoxy resin, a silicone resin, an amidimide resin and a urethane resin, and from the viewpoint of moisture resistance It is preferable that at least one selected from the group consisting of an epoxy resin, an acrylic resin and an amidimide resin. The resin used for the resin part may be one kind alone or two or more kinds.

Among them, the resin composition is preferably an epoxy resin composition containing an epoxy resin, a curing agent, and an inorganic filler (hereinafter, also simply referred to as “epoxy resin composition” in the present disclosure). Hereinafter, each component which can be contained in an epoxy resin composition is demonstrated.

-Epoxy resin-
The type of epoxy resin contained in the epoxy resin composition is not particularly limited. For example, bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol AD type epoxy resin, hydrogenated bisphenol A type epoxy resin, hydrogenated bisphenol AD type epoxy resin, naphthalene type epoxy resin, and reactive diluent The epoxy resin which has only one epoxy group to be separated is mentioned. The epoxy resin may be used alone or in combination of two or more.

Among them, from the viewpoint of improving the thermal conductivity, the epoxy resin preferably contains an epoxy resin having a mesogen skeleton. The epoxy resin having a mesogen skeleton may be used alone or in combination of two or more. The epoxy resin may be a combination of an epoxy resin having a mesogen skeleton and an epoxy resin not having a mesogen skeleton, or may be an epoxy resin composed of an epoxy resin having a mesogen skeleton. When the epoxy resin contains an epoxy resin having a mesogen skeleton, the content of the epoxy resin not having a mesogen skeleton may be 10% by mass or less, or 5% by mass or less based on the total amount of the epoxy resin. It may be 2% by mass or 0% by mass.

When the epoxy resin composition contains, as an epoxy resin, an epoxy resin having a mesogen skeleton and an epoxy resin not having a mesogen skeleton, the content of the epoxy resin having a mesogen skeleton relative to the total amount of epoxy resin is a UV spectrum detector And a liquid chromatograph equipped with a mass spectrum detector.

In the present disclosure, “mesogenic skeleton” indicates a molecular structure that may exhibit liquid crystallinity. Specifically, biphenyl skeleton, phenyl benzoate skeleton, cyclohexyl bensoate skeleton, azobenzene skeleton, stilbene skeleton, derivatives thereof and the like can be mentioned. An epoxy resin having a mesogen skeleton tends to form a high-order structure upon curing, and when cured, tends to be able to achieve higher thermal conductivity.

Here, the higher-order structure is a state in which the constituent elements are arranged in a micro, and corresponds to, for example, a crystal phase and a liquid crystal phase. Whether such a higher order structure exists can be easily determined by observation with a polarizing microscope. That is, in the observation in the cross nicol state, when an interference pattern due to depolarization is observed, it can be determined that a higher order structure exists.
The higher order structure is usually present in the form of islands in the resin to form a domain structure. And each of the islands forming the domain structure is called a higher order structure. The structural units constituting the higher order structural body are generally linked by a covalent bond.

The highly ordered higher order structure derived from the mesogen skeleton includes a nematic structure, a smectic structure and the like. The nematic structure is a liquid crystal structure in which the molecular long axis is oriented in a uniform direction and has only an orientational order. On the other hand, the smectic structure is a liquid crystal structure which has a one-dimensional position order in addition to the alignment order and has a layer structure of a constant period. In addition, within the same periodic structure of the smectic structure, the direction of the period of the layer structure is uniform. That is, the molecular order is higher in the smectic structure than in the nematic structure. When a highly ordered higher-order structure is formed in the cured product, scattering of phonon, which is a medium for heat conduction, can be suppressed. For this reason, the thermal conductivity of the smectic structure is higher than that of the nematic structure.
That is, the order of the molecule is higher in the smectic structure than in the nematic structure, and the thermal conductivity of the cured product is also higher in the case of exhibiting the smectic structure. It is considered that an epoxy resin having a mesogen skeleton reacts with a curing agent to form a smectic structure, thereby exhibiting high thermal conductivity when it is a cured product.

It can be judged by the following method whether a smectic structure is formed using an epoxy resin composition.
Using a CuK _α 1 ray, X-ray diffraction measurement is performed using an X-ray analyzer (for example, manufactured by Rigaku Corporation) with a tube voltage of 40 kV, a tube current of 20 mA, and 2θ of 0.5 ° to 30 °. When a diffraction peak exists in the range of 1 ° to 10 ° of 2θ, it is determined that the periodic structure includes a smectic structure. In the case of having a highly ordered high-order structure derived from a mesogen structure, a diffraction peak appears in the range of 1 ° to 30 ° of 2θ.

The epoxy equivalent of the epoxy resin having a mesogen skeleton is preferably 150 g / eq to 500 g / eq, and preferably 150 g / eq to 450 g / eq, from the viewpoint of achieving both handleability and thermal conductivity when cured. Is more preferably 200 g / eq to 450 g / eq, particularly preferably 230 g / eq to 400 g / eq, and most preferably 250 g / eq to 370 g / eq. If the epoxy equivalent is 150 g / eq or more, the crystallinity of the epoxy resin does not become too high, and the handling property tends to be difficult to reduce. On the other hand, if the epoxy equivalent is 500 g / eq or less, the crosslink density of the epoxy resin is unlikely to decrease, and the thermal conductivity of the cured product tends to be high.
The epoxy equivalent is measured by perchloric acid titration method in accordance with JIS K 7236: 2009.

In addition, the number average molecular weight (Mn) in gel permeation chromatography (GPC) measurement of the epoxy resin having a mesogen skeleton is 400 to 2500, from the viewpoint of achieving both the handling property and the thermal conductivity when it is a cured product. It is preferably 450 to 2000, more preferably 500 to 1800. When the Mn of the epoxy resin is 400 or more, the crystallinity of the epoxy resin does not become too high, and the handling property tends to be difficult to reduce. If the Mn of the epoxy resin is 2500 or less, the crosslink density of the epoxy resin is unlikely to be reduced, and the thermal conductivity of the cured product tends to be high.

GPC measurement in the present disclosure uses “G2000HXL” and “3000HXL” manufactured by Tosoh Corp. as GPC columns for analysis, uses tetrahydrofuran as a mobile phase, a sample concentration of 0.2 mass%, and a flow rate of 1.0 ml. Measure as / min. A calibration curve is prepared using polystyrene standard samples, and Mn is calculated by polystyrene conversion value.

The epoxy resin having a mesogen skeleton may contain an epoxy compound having a mesogen skeleton, and may contain a reactant obtained by polymerizing an epoxy compound having a mesogen skeleton. As a reaction product obtained by polymerizing an epoxy compound having a mesogen skeleton, even if it is a reaction product of epoxy compounds having a mesogen skeleton, a part of the epoxy compound having a mesogen skeleton is partially reacted with a curing agent or the like It may be in the form of a prepolymer. The curing agent used for prepolymerization may be the same as or different from the curing agent to be contained in the epoxy resin composition. When the epoxy compound having a mesogenic skeleton is partially polymerized, the formability may be improved.

The epoxy compounds having a mesogen skeleton may be used alone or in combination of two or more. A specific example of the epoxy compound having a mesogen skeleton is described in, for example, Japanese Patent No. 4118691. Although the specific example of the epoxy compound which has a mesogen frame is shown below, the epoxy compound which has a mesogen frame is not limited to these.

Examples of the epoxy compound having a mesogenic skeleton include 1- (3-methyl-4-oxiranylmethoxyphenyl) -4- (4-oxiranylmethoxyphenyl) -1-cyclohexene, 1- (3-methyl-4- 4- Oxiranylmethoxyphenyl) -4- (4-oxiranylmethoxyphenyl) -benzene, 4- {4- (2,3-epoxypropoxy) phenyl} cyclohexyl 4- (2,3-epoxypropoxy) benzoate and the like Can be mentioned. Among these epoxy compounds, 1- (3-methyl-4-oxiranylmethoxyphenyl) -4- (4-oxiranylmethoxyphenyl) -benzene and 4- {4 from the viewpoint of improving the thermal conductivity It is preferable to use at least one selected from the group consisting of-(2,3-epoxypropoxy) phenyl} cyclohexyl = 4- (2,3-epoxypropoxy) benzoate.

Furthermore, from the viewpoint of improving the flowability of the resin composition, the epoxy compound having a mesogen skeleton forms a nematic structure having low order by itself when phase transition from a crystal phase to a liquid crystal phase is carried out, but when it is prepolymerized, It is preferable that it is an epoxy compound which forms a highly ordered smectic structure. As such an epoxy compound, it is preferable that the epoxy compound which has mesogen frame | skeleton contains the compound represented by the following general formula (I-0).

Among the compounds represented by the general formula (I-0), a compound represented by the following general formula (I-1) is preferable.

In formulas (I-0) and (I-1), each of R ¹ to R ⁴ independently represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms.

In formulas (I-0) and (I-1), R ¹ to R ⁴ each independently represent a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and a hydrogen atom or 1 or 2 carbon atoms It is preferably an alkyl group, more preferably a hydrogen atom or a methyl group, and still more preferably a hydrogen atom.
Furthermore, 2 to ⁴ of R ¹ to R ⁴ are preferably hydrogen atoms, more preferably 3 or 4 of them are hydrogen atoms, and all 4 of them are all hydrogen atoms preferable. When ^{one of} R ¹ to R ⁴ is an alkyl group having 1 to 3 carbon atoms, it is preferable that at least one of R ¹ and R ⁴ is an alkyl group having 1 to 3 carbon atoms.

In the epoxy resin having a mesogen skeleton, the phase transition temperature at which a crystalline phase is transformed to a liquid crystal phase is preferably 140 ° C. or less, more preferably 135 ° C. or less. When an epoxy resin having a mesogen skeleton and a phase transition temperature of 140 ° C. or less is used as the epoxy resin, it tends to exhibit higher thermal conductivity when it is cured. Although the reason is not clear, the epoxy resin is easily melted when the epoxy resin composition is prepared, and therefore the epoxy resin composition is easily homogenized by mixing, and as a result, the generation of the liquid crystal phase is suppressed. it is conceivable that.

The phase transition temperature can be measured using a differential scanning calorimetry (DSC) measurement device (for example, Perkin Elmer Pyris 1). Specifically, the differential scanning calorific value of a 3 mg to 5 mg sample sealed in an aluminum pan under conditions of a nitrogen atmosphere with a temperature increase rate of 20 ° C./min, a measurement temperature range of 25 ° C. to 350 ° C. The measurement is performed, and it is measured as a temperature at which an energy change (endothermic reaction) accompanying the phase transition occurs. An example of a graph obtained by this measurement is shown in FIG. The temperature of the endothermic reaction peak appearing in FIG. 5 is taken as a phase transition temperature.

In general, epoxy compounds having a mesogenic skeleton tend to have a high phase transition temperature. In particular, an epoxy compound having a highly ordered smectic structure tends to have a high phase transition temperature. Here, by partially reacting the epoxy compound having a mesogen skeleton with a curing agent or the like to perform prepolymerization, it becomes possible to make the phase transition temperature of the epoxy resin having a mesogen skeleton 140 ° C. or less. The epoxy compound having a mesogenic skeleton may have a phase transition temperature of 140 ° C. or lower, or may exceed 140 ° C.

As a curing agent used for prepolymerization of the epoxy compound which has mesogen frame | skeleton, a phenol compound and an amine compound are mentioned. That is, the epoxy resin having a mesogen skeleton may contain a reaction product of a phenol compound and an epoxy compound having a mesogen skeleton, and may contain a reaction product of an amine compound and an epoxy compound having a mesogen skeleton. As a phenol compound, a dihydric phenol compound having two hydroxyl groups as a substituent on one benzene ring (hereinafter, also simply referred to as a dihydric phenol compound), 3 having three hydroxyl groups on one benzene ring as a substituent 3 Dihydric phenol compounds (hereinafter, also simply referred to as trivalent phenol compounds) and the like.

It is preferable to use a dihydric phenol compound for prepolymerizing an epoxy compound having a mesogen skeleton from the viewpoint of controlling the molecular weight, thermal conductivity and glass transition temperature (Tg) of the epoxy resin.
In addition, when an epoxy compound having a mesogen skeleton and a dihydric phenol compound are partially reacted and prepolymerized, it is possible to lower the phase transition temperature. Therefore, even if the phase transition temperature of the epoxy compound having a mesogen skeleton exceeds 140 ° C., it becomes easy to use. In general, since epoxy resins having a mesogen skeleton have a high phase transition temperature, a method of prepolymerizing with a compound capable of lowering the phase transition temperature is useful.

Examples of dihydric phenol compounds include catechol, resorcinol, hydroquinone, 4,4'-biphenol, 4,3'-biphenol, 2,2'-biphenol and derivatives thereof. The derivatives include compounds in which a benzene ring is substituted with an alkyl group having 1 to 8 carbon atoms and the like. Among these dihydric phenol compounds, hydroquinone or 4,4'-biphenol is preferably used from the viewpoint of improving the thermal conductivity. Since hydroquinone and 4,4'-biphenol have a structure in which two hydroxyl groups are substituted so as to be in the positional relationship of para position, a prepolymerized epoxy resin obtained by reacting with an epoxy compound having a mesogenic skeleton Has a linear structure. For this reason, it is considered that the stacking properties of the molecules are high and it is easy to form a higher order structure. The dihydric phenol compounds may be used alone or in combination of two or more.

Using a trivalent phenol compound for prepolymerizing an epoxy compound having a mesogen skeleton is a cured product while suitably achieving low softening point and retention of the ability to form a high-order structure of the epoxy compound having a mesogen skeleton It is preferable at the point which can raise the glass transition temperature (Tg) at the time.
The trivalent phenol compound is at least one selected from the group consisting of 1,2,3-trihydroxybenzene, 1,2,4-trihydroxybenzene and 1,3,5-trihydroxybenzene Preferably, it is at least one selected from the group consisting of 1,2,4-trihydroxybenzene and 1,3,5-trihydroxybenzene from the viewpoint of improving the thermal conductivity of a cured product using an epoxy polymer Is more preferred.

In the following, a method of synthesizing an epoxy resin having a mesogen skeleton is described, in which the epoxy resin having a mesogen skeleton is a reaction product of an epoxy compound having a mesogen skeleton and a phenol compound.
The epoxy resin having a mesogen skeleton can be synthesized, for example, by dissolving an epoxy compound having a mesogen skeleton, a phenol compound, and a reaction catalyst in a synthesis solvent, and stirring while applying heat. It is also possible to synthesize an epoxy resin having a mesogen skeleton by melting and reacting an epoxy compound having a mesogen skeleton and a phenol compound without using a synthesis solvent. In this case, the reaction is carried out by raising the temperature to a temperature at which the epoxy resin melts. From the viewpoint of safety, a synthesis method using a synthesis solvent is preferred.

For example, when a reaction product of an epoxy compound having a mesogen skeleton and a dihydric phenol compound is synthesized, the equivalent number of the phenolic hydroxyl group of the dihydric phenol compound and the equivalent number of the epoxy group of the epoxy compound having a mesogen skeleton The ratio (equivalent number of epoxy groups / equivalent number of phenolic hydroxyl groups) may be from 100/1 to 100/100, preferably from 100/10 to 100/50, and preferably from 100/10 to 100/40. And more preferably 100/10 to 100/30.

Also, for example, when synthesizing a reaction product of an epoxy compound having a mesogen skeleton and a trivalent phenol compound, the equivalent number of phenolic hydroxyl groups of the trivalent phenol compound, and the equivalent number of epoxy groups of an epoxy compound having a mesogen skeleton (The number of equivalents of epoxy group / the number of equivalents of phenolic hydroxyl group) may be 100/1 to 100/100, and the viewpoint of the fluidity of the epoxy resin composition and the heat resistance and thermal conductivity of the cured product Are preferably 100/10 to 100/50, more preferably 100/10 to 100/40, and still more preferably 100/10 to 100/30. Assuming that the ratio of the number of equivalents of phenolic hydroxyl group of trihydric phenol compound to the number of equivalents of epoxy group of epoxy compound having a mesogen skeleton (number of equivalents of epoxy group / number of equivalents of phenolic hydroxyl group) is 100/10 or less The tendency to be able to suppress the rise of the softening point of the obtained epoxy polymer, and when Ep / Ph is 100/40 or more, suppresses the deterioration of the heat resistance of the cured product due to the decrease of the crosslink point density, and the heat of the cured product. It tends to be able to suppress the decrease in conductivity.

The synthesis solvent is not particularly limited as long as the solvent can be heated to a temperature necessary for the reaction of the epoxy compound having a mesogen skeleton with the phenol compound to proceed. Specific examples thereof include cyclohexanone, cyclopentanone, ethyl lactate, propylene glycol monomethyl ether, N-methyl pyrrolidone and the like.

The amount of the synthesis solvent is preferably such that the epoxy compound having a mesogen skeleton, the phenol compound, and the reaction catalyst can all be dissolved at the reaction temperature. Although the solubility varies depending on the type of raw material before reaction, the type of solvent and the like, it is preferable to set the concentration of the charged solid content to 20 mass% to 60 mass%. When the amount of such synthesis solvent is used, the viscosity of the resin solution after synthesis tends to be in the preferable range.

The type of reaction catalyst is not particularly limited, and an appropriate one can be selected from the viewpoint of reaction rate, reaction temperature, storage stability and the like. Specific examples of the reaction catalyst 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 them, from the viewpoint of heat resistance, organic phosphine compounds; organic phosphine compounds maleic anhydride, quinone compounds (1,4-benzoquinone, 2,5-toluquinone, 1,4-naphthoquinone, 2,3-dimethylbenzoquinone, 2, 6-Dimethylbenzoquinone, 2,3-dimethoxy-5-methyl-1,4-benzoquinone, 2,3-dimethoxy-1,4-benzoquinone, phenyl-1,4-benzoquinone etc.), diazophenylmethane, phenol resin etc. A compound having an intramolecular polarization formed by adding a compound having a π bond; and a complex of an organic phosphine compound and an organic boron compound (tetraphenyl borate, tetra-p-tolyl borate, tetra-n-butyl borate, etc.); It is preferable that it is at least one selected from the group consisting of

Examples of organic phosphine compounds include triphenyl phosphine, diphenyl (p-tolyl) phosphine, tris (alkylphenyl) phosphine, tris (alkoxyphenyl) phosphine, tris (alkylalkoxyphenyl) phosphine, tris (dialkylphenyl) phosphine, and tris (trimethylphenyl) phosphine. Alkylphenyl) phosphine, tris (tetraalkylphenyl) phosphine, tris (dialkoxyphenyl) phosphine, tris (trialkoxyphenyl) phosphine, tris (tetraalkoxyphenyl) phosphine, trialkyl phosphine, dialkyl aryl phosphine, alkyl diaryl phosphine etc It can be mentioned.

The amount of reaction catalyst is not particularly limited. From the viewpoint of reaction rate and storage stability, the content is preferably 0.1% by mass to 3.0% by mass with respect to the total mass of the epoxy compound having a mesogen skeleton and the phenol compound, and is preferably 0.5% by mass to 2.%. More preferably, it is 0% by mass.

The reaction product of an epoxy compound having a mesogen skeleton and a phenol compound can be synthesized using a glass flask for small scale and using a stainless steel synthesis pot for large scale. The specific synthesis method is, for example, as follows. First, an epoxy compound having a mesogen skeleton is charged into a flask or a synthesis pot, a synthetic solvent is charged, and the reaction temperature is raised with an oil bath or a heat medium to dissolve the epoxy compound having a mesogen skeleton. A phenol compound is charged therein, and after confirming that the compound is sufficiently dissolved in the synthesis solvent, the reaction catalyst is charged to start the reaction. When the reaction solution is taken out after the reaction time, a reaction product solution of an epoxy compound having a mesogen skeleton and a phenol compound is obtained. In addition, if the synthesis solvent is distilled off under reduced pressure under heating conditions in a flask or in a synthesis pot, a reaction product of an epoxy compound having a mesogen skeleton and a phenol compound is obtained at room temperature (for example, 25 ° C.) Obtained as a solid.

The reaction temperature is not limited as long as the reaction between the epoxy group and the phenolic hydroxyl group proceeds in the presence of the reaction catalyst. For example, the range of 100 ° C. to 180 ° C. is preferable, and the range of 120 ° C. to 170 ° C. More preferable. By setting the reaction temperature to 100 ° C. or more, it tends to be possible to shorten the time until the reaction is completed. On the other hand, gelation tends to be suppressed by setting the reaction temperature to 180 ° C. or less.

It is preferable that the epoxy resin which has mesogen frame | skeleton contains the dimer of the epoxy compound which has mesogen frame | skeleton as prepolymerized epoxy resin. The epoxy resin having a mesogen skeleton is selected from the group consisting of an epoxy compound (monomer) having a mesogen skeleton, and a multimer of an epoxy compound having a mesogen skeleton, in addition to the dimer of the epoxy compound having a mesogen skeleton At least one may be further included. The dimer and the multimer of the epoxy compound having a mesogen skeleton are a reaction product of epoxy resins having a mesogen skeleton or a reaction product in which an epoxy compound having a mesogen skeleton is reacted with a curing agent or the like. Good. The curing agent used for dimerization and multimerization may be the same as or different from the curing agent to be contained in the epoxy resin composition.

An epoxy compound having a mesogenic skeleton in its molecular structure is generally easy to crystallize and tends to have a high melting temperature as compared with a general purpose epoxy compound. However, crystallization is suppressed by partially polymerizing such an epoxy compound to form a dimer. As a result, the handling property tends to be improved.

As a curing agent used for dimerization or multimerization of an epoxy compound, the phenol compound and amine compound which were mentioned above as a curing agent used for prepolymerization of the epoxy compound which has a mesogen frame | skeleton are mentioned, for example It is similar to that described above.

When the epoxy resin having a mesogen skeleton contains a dimer of an epoxy compound having a mesogen skeleton, the ratio of the dimer of the epoxy compound having a mesogen skeleton is 15% by mass to the total amount of the epoxy resin having a mesogen skeleton. The content is preferably in the range of 20% by mass to 27% by mass, and more preferably in the range of 22% by mass to 25% by mass.

If the proportion of the dimer of the epoxy compound having a mesogen skeleton is 15% by mass or more, the handling property such as flexibility tends to be excellent. Moreover, when it is set as hardened | cured material as the ratio of the dimer of the epoxy compound which has a mesogen frame is 28 mass% or less, the fall of crosslinking density is suppressed and the thermal conductivity and glass transition temperature of the hardened | cured material obtained ( Tg) tends to be maintained high.

The ratio of the dimer of the epoxy compound having a mesogen skeleton to the total amount of the epoxy resin having a mesogen skeleton can be determined by reversed phase chromatography (RPLC) measurement.

RPLC measurement in the present disclosure uses “Mightysil RP-18” manufactured by Kanto Chemical Co., Ltd. as an RPLC column for analysis, and using a gradient method, the mixing ratio (by volume) of the eluent is acetonitrile / tetrahydrofuran / water = 20. It is carried out by continuously changing from 5/75 to acetonitrile / tetrahydrofuran = 80/20 (20 minutes from the start) to acetonitrile / tetrahydrofuran = 50/50 (35 minutes from the start). Also, the flow rate is 1.0 ml / min. In the present disclosure, the absorbance at a wavelength of 280 nm is detected, the total area of all detected peaks is set to 100, the ratio of the area at each corresponding peak is determined, and the value is the content of each compound in the epoxy resin [mass %]

Among them, an epoxy resin having a mesogen skeleton is a dimer of a compound represented by the above general formula (I-0) as a dimer of an epoxy compound having a mesogen skeleton (hereinafter, “specific dimer compound”) (Also referred to as The specific dimer compound is a dimer of the compound represented by the general formula (I-0), and thus has two structural units represented by the following general formula (I) in one molecule.

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.

In 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, preferably a hydrogen atom Or a methyl group is more preferable, and a hydrogen atom is more preferable.
Furthermore, 2 to ⁴ of R ¹ to R ⁴ are preferably hydrogen atoms, more preferably 3 or 4 of them are hydrogen atoms, and all 4 of them are all hydrogen atoms preferable. When ^{one of} R ¹ to R ⁴ is an alkyl group having 1 to 3 carbon atoms, it is preferable that at least one of R ¹ and R ⁴ is an alkyl group having 1 to 3 carbon atoms.

The specific dimer compound preferably has at least one structural unit selected from the group consisting of a structural unit represented by the following general formula (IA) and a structural unit represented by the following general formula (IB).

In formulas (IA) and (IB), R ¹ to R ⁴ each independently represent a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and R ⁵ each independently has 1 to 8 carbon atoms It shows an alkyl group. n is an integer of 0 to 4;

Specific examples of ^R 1 ~ ^{R 4} in the general formula (IA) and Formula (IB) is the same as ^R 1 ~ ^{R 4} in formula (I), is the same preferred ranges thereof.

In the general formula (IA) and the general formula (IB), each R ⁵ independently represents an alkyl group having 1 to 8 carbon atoms, preferably an alkyl group having 1 to 3 carbon atoms, and is preferably a methyl group More preferable.
In general formula (IA) and general formula (IB), n is an integer of 0 to 4, preferably an integer of 0 to 2, more preferably an integer of 0 to 1, and 0 Is more preferred. That is, the benzene ring to which R ⁵ is attached in the general formula (IA) and the general formula (IB) preferably has 2 to 4 hydrogen atoms, and 3 or 4 hydrogen atoms. More preferably, it has four hydrogen atoms.

The structural unit represented by the general formula (IA) is at least selected from the group consisting of a structural unit represented by the following general formula (IA-1) and a structural unit represented by the following general formula (IA-2) It is preferable to contain one structural unit, and it is more preferable to contain a structural unit represented by the following general formula (IA-1).

The structural unit represented by the general formula (IB) is at least selected from the group consisting of a structural unit represented by the following general formula (IB-1) and a structural unit represented by the following general formula (IB-2) It preferably contains one structural unit, and more preferably contains a structural unit represented by the following general formula (IB-1).

Specific examples of R ¹ to R ⁵ and n in the general formula (IA-1), the general formula (IA-2), the general formula (IB-1) and the general formula (IB-2) are the general formula (IA) and The same applies to R ¹ to R ⁵ and n in the general formula (IB), and the preferred range is also the same.

Specific examples of the specific dimer compound include a compound represented by the following general formula (II-A), a compound represented by the following general formula (II-B), and a compound represented by the following general formula (II-C) Compounds and the like. The specific dimer compound comprises a compound represented by the following general formula (II-A), a compound represented by the following general formula (II-B), and a compound represented by the following general formula (II-C) It is preferred to include at least one compound selected from the group.

Specific examples of the general formula (II-A), general formula (II-B) and formula (II-C) in ^R 1 ~ ^{R 5} and n have the general formula (IA) and ^{R 1} in the general formula (IB) The same applies to R ⁵ and n, and the preferred range is also the same.

The compound represented by the general formula (II-A) preferably includes a compound represented by the following general formula (II-A-1) and a compound represented by the following general formula (II-A-2) It is more preferable to include a compound represented by the following general formula (II-A-1).

The compound represented by the general formula (II-B) preferably includes a compound represented by the following general formula (II-B-1) and a compound represented by the following general formula (II-B-2) It is more preferable to include a compound represented by the following general formula (II-B-1).

The compound represented by the general formula (II-C) preferably includes a compound represented by the following general formula (II-C-1) and a compound represented by the following general formula (II-C-2) It is more preferable to include a compound represented by the following general formula (II-C-1).

Formula (II-A-1), Formula (II-A-2), Formula (II-B-1), Formula (II-B-2), Formula (II-C-1) and specific examples of ^R 1 ~ ^{R 5} and n in the general formula (II-C-2) is the same as ^R 1 ~ ^{R 5} and n in the general formula (IA) and formula (IB), also the preferred ranges It is similar.

The specific dimer compound is a compound represented by the general formula (II-A-1), a compound represented by the general formula (II-B-1), and a compound represented by the general formula (II-C-1) It is preferred to include at least one compound selected from the group consisting of compounds.

The structure of the specific dimer compound is presumed to be obtained by the reaction of the compound represented by the above general formula (I-0) used when synthesizing the epoxy resin and a curing agent such as a phenol compound. It can be determined by comparing the molecular weight of the structure with the molecular weight of the target compound determined by liquid chromatography performed using a liquid chromatograph equipped with a UV spectrum detector and a mass spectrum detector.

In liquid chromatography, for example, "LaChrom II C18" manufactured by Hitachi, Ltd. is used as a column for analysis, and tetrahydrofuran is used as an eluent at a flow rate of 1.0 ml / min. The UV spectrum detector detects the absorbance at a wavelength of 280 nm. The mass spectrum detector detects at an ionization voltage of 2700 V.

The epoxy resin having a mesogen skeleton may further include a multimer of an epoxy compound having a mesogen skeleton, in addition to the dimer of the epoxy compound having a mesogen skeleton. The number of structural units of the epoxy compound having a mesogen skeleton in the multimer of the epoxy compound having a mesogen skeleton is 3 or more, preferably 5 or less as an average value, more preferably 4 or less, and 3 It is further preferred that

Examples of the multimer of the epoxy compound having a mesogen skeleton include multimers of the compound represented by General Formula (I-0) (hereinafter, also referred to as “specific multimer compound”). The specific multimer compound is a multimer of the compound represented by the general formula (I-0) and has three or more structural units represented by the general formula (I) in one molecule. The number of structural units represented by General Formula (I) in the specific multimeric compound is preferably 5 or less as an average value, more preferably 4 or less, and still more preferably 3.

The specific multimeric compound is a specific multimeric compound having at least one structural unit selected from the group consisting of the structural unit represented by the above general formula (IA) and the structural unit represented by the general formula (IB) Is preferred.
The structural unit represented by the general formula (IA) in the specific multimeric compound is selected from the group consisting of the structural unit represented by the general formula (IA-1) and the structural unit represented by the general formula (IA-2) It is preferable to include at least one structural unit to be treated, and it is more preferable to include the structural unit represented by general formula (IA-1).
The structural unit represented by the general formula (IB) in the specific multimeric compound is selected from the group consisting of the structural unit represented by the general formula (IB-1) and the structural unit represented by the general formula (IB-2) It is preferable to include at least one structural unit to be treated, and it is more preferable to include a structural unit represented by General Formula (IB-1).

The epoxy resin having a mesogen skeleton may further include an epoxy compound (monomer) having a mesogen skeleton, in addition to the dimer of the epoxy compound having a mesogen skeleton. When the epoxy resin having a mesogen skeleton contains an epoxy compound having a mesogen skeleton in addition to the dimer of the epoxy compound having a mesogen skeleton, the proportion of the epoxy compound having a mesogen skeleton in the total epoxy resin having a mesogen skeleton Is preferably 57% by mass to 80% by mass, more preferably 59% by mass to 74% by mass, and still more preferably 62% by mass to 70% by mass. When the proportion of the epoxy compound having a mesogen skeleton is 57% by mass or more, when the cured product is formed, the crosslink density is unlikely to be reduced, and the heat conductivity and the Tg tend to be excellent. On the other hand, when the proportion of the epoxy compound having a mesogen skeleton is 80% by mass or less, the handling property such as flexibility tends to be excellent.

Examples of the epoxy compound having a mesogen skeleton include the compounds represented by the general formula (I-0) and the compounds described above as the epoxy compound having a mesogen skeleton.

When the epoxy resin having a mesogen skeleton contains a dimer of an epoxy compound having a mesogen skeleton, the epoxy resin having a mesogen skeleton may be, for example, an epoxy compound having a mesogen skeleton, a phenol compound, and a reaction catalyst in a synthesis solvent It can be dissolved and stirred while heating to synthesize. An example of a specific synthesis method is as described above as “a method of synthesizing an epoxy resin having a mesogen skeleton when the epoxy resin having a mesogen skeleton is a reaction product of an epoxy compound having a mesogen skeleton and a phenol compound”. .

-Hardener-
The epoxy resin composition contains a curing agent. As the curing agent, those generally used in the art can be used without particular limitation. The curing agent may, for example, be a polyaddition curing agent such as an acid anhydride curing agent, an amine curing agent, a phenol curing agent or a mercaptan curing agent, or a latent curing agent such as imidazole. From the viewpoint of heat resistance and adhesion, an amine-based curing agent or a phenol-based curing agent is preferred. From the viewpoint of storage stability, phenolic curing agents are preferred. Also, from the viewpoint of obtaining a cured product with high toughness, an amine-based curing agent is preferable. The curing agent may be used alone or in combination of two or more.

As a phenol type hardening agent, what is normally used can be used without a restriction | limiting in particular. For example, a phenolic compound and a phenolic resin having novolakized phenolic compound can be used. The phenol-based curing agent may be used alone or in combination of two or more.

Examples of the phenol compound include monofunctional phenol compounds such as phenol, o-cresol, m-cresol, p-cresol, etc .; difunctional phenol compounds such as catechol, resorcinol, hydroquinone; 1,2,3-trihydroxybenzene, 1 And trifunctional phenol compounds such as 2,4-trihydroxybenzene and 1,3,5-trihydroxybenzene. Moreover, as a phenol resin, the phenol novolak resin which linked these phenol compounds by the methylene chain etc. and was novolak-ized is mentioned.

From the viewpoint of thermal conductivity, the phenol-based curing agent is preferably a phenol novolac resin in which a bifunctional phenol compound such as catechol, resorcinol, or hydroquinone or a bifunctional phenol compound is linked by a methylene chain, and heat resistance It is more preferable that it is a phenol novolak resin which connected the bifunctional phenol compound by the methylene chain from a viewpoint of these.

Resins obtained by novolakizing one kind of phenol compound such as cresol novolac resin, catechol novolac resin, resorcinol novolac resin, hydroquinone novolac resin as phenol novolac resin; two or more kinds of phenol such as catechol resorcinol novolac resin, resorcinol hydroquinone novolac resin The resin which made the compound novolak-ized; etc. can be mentioned.

When a phenol novolac resin is used as a phenol-based curing agent, a compound having a structural unit represented by at least one selected from the group consisting of the following general formula (II-1) and the following general formula (II-2) It is preferable to include.

In formulas (II-1) and (II-2), each R ¹ independently represents an alkyl group, an aryl group or an aralkyl group. The alkyl group, aryl group and aralkyl group represented by R ¹ may further have a substituent. Examples of the substituent include an alkyl group (except when R ¹ is an alkyl group), an aryl group, a halogen atom, a hydroxyl group and the like. Each m independently represents an integer of 0 to 2, and when m is 2, two R ^{1 s} may be the same or different. Each m is preferably independently 0 or 1, and more preferably 0. Further, n each independently represents an integer of 1 to 7.

In formulas (II-1) and (II-2), R ² and R ³ 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 ² and R ³ may further have a substituent. Examples of the substituent include an alkyl group (except when R ² or R ³ is an alkyl group), an aryl group, a halogen atom, a hydroxyl group and the like.

From the viewpoint of storage stability and thermal conductivity, R ² and R ^{3 in} general formulas (II-1) and (II-2) are preferably a hydrogen atom, an alkyl group or an aryl group, and hydrogen An atom, an alkyl group having 1 to 4 carbon atoms or an aryl group having 6 to 12 carbon atoms is more preferable, and a hydrogen atom is more preferable.

When the compound having a structural unit represented by the general formula (II-1) contains a partial structure derived from a phenolic compound other than resorcinol, the partial structure derived from a phenolic compound other than resorcinol includes thermal conductivity and adhesiveness. From the viewpoint of at least one selected from the group consisting of phenol, cresol, catechol, hydroquinone, 1,2,3-trihydroxybenzene, 1,2,4-trihydroxybenzene and 1,3,5-trihydroxybenzene It is preferable that it is a partial structure derived from, and more preferably a partial structure derived from at least one selected from catechol and hydroquinone.

When the compound having a structural unit represented by the general formula (II-2) contains a partial structure derived from a phenol compound other than catechol, the partial structure derived from a phenol compound other than catechol includes thermal conductivity and adhesiveness. From the viewpoint of at least one selected from the group consisting of phenol, cresol, resorcinol, hydroquinone, 1,2,3-trihydroxybenzene, 1,2,4-trihydroxybenzene and 1,3,5-trihydroxybenzene It is preferable that it is a partial structure derived from, and it is more preferable that it is a partial structure derived from at least one selected from resorcinol and hydroquinone.

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

In the compound having a structural unit represented by General Formula (II-1), the content ratio of the partial structure derived from resorcinol is not particularly limited. From the viewpoint of elastic modulus, the content ratio of the partial structure derived from resorcinol to the total mass of the compound having a structural unit represented by General Formula (II-1) is preferably 55% by mass or more, and the glass of the cured product From the viewpoint of transition temperature (Tg) and linear expansion coefficient, the content is more preferably 60% by mass or more, still more preferably 80% by mass or more, and from the viewpoint of thermal conductivity, 90% by mass or more Particularly preferred.

In the compound having a structural unit represented by the general formula (II-2), the content ratio of the partial structure derived from catechol is not particularly limited. From the viewpoint of elastic modulus, the content ratio of the partial structure derived from catechol to the total mass of the compound having a structural unit represented by General Formula (II-2) is preferably 55% by mass or more, and the glass of the cured product From the viewpoint of transition temperature (Tg) and linear expansion coefficient, the content is more preferably 60% by mass or more, still more preferably 80% by mass or more, and from the viewpoint of thermal conductivity, 90% by mass or more Particularly preferred.

The molecular weight of the compound having a structural unit represented by at least one selected from the group consisting of general formula (II-1) and general formula (II-2) 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 still more preferably 350 to 1500. The weight average molecular weight (Mw) is preferably 2000 or less, more preferably 1500 or less, and still more preferably 400 to 1500. These Mn and Mw are measured by the usual method using gel permeation chromatography (GPC).

The hydroxyl equivalent of the compound having a structural unit represented by at least one selected from the group consisting of general formula (II-1) and general formula (II-2) is not particularly limited. From the viewpoint of the crosslink density involved in heat resistance, the hydroxyl group equivalent is preferably 50 g / eq to 150 g / eq on average, more preferably 50 g / eq to 120 g / eq, and more preferably 55 g / eq to 120 g / eq. More preferably, it is eq. In addition, a hydroxyl equivalent means the value measured based on JISK0070: 1992.

When a compound having a structural unit represented by at least one selected from the group consisting of General Formula (II-1) and General Formula (II-2) is used as a phenol-based curing agent, it occupies in the phenol-based curing agent The proportion of the compound having a structural unit represented by at least one selected from the group consisting of general formula (II-1) and general formula (II-2) is preferably 50% by mass or more and 80% by mass or more More preferably, 90 mass% or more is more preferable.

When a phenol novolac resin is used as a phenol-based curing agent, the phenol novolac resin is a structure represented by at least one selected from the group consisting of the following general formula (III-1) to the following general formula (III-4) It is also preferred to include a compound having

In formulas (III-1) to (III-4), m and n each independently represent a positive integer, and represent the number of each structural unit to which m or n is attached. Ar each independently represents a group represented by the following formula (III-a) or the following formula (III-b).

In formulas (III-a) and (III-b), R ¹¹ and R ¹⁴ each independently represent a hydrogen atom or a hydroxyl group. R ¹² and R ¹³ each independently represent a hydrogen atom or an alkyl group having 1 to 8 carbon atoms.

The compound having a structure represented by at least one selected from the group consisting of general formula (III-1) to general formula (III-4) is a by-product produced by a method of novolakizing a divalent phenol compound Can be generated as

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

In each of the general formulas (III-1) to (III-4), a plurality of Ar may be the same atomic group or may contain two or more kinds of atomic groups. Ar each independently represents a group represented by formula (III-a) or (III-b).

R ¹¹ and R ¹⁴ in the general formula (III-a) and the general formula (III-b) each independently represent a hydrogen atom or a hydroxyl group, and are preferably a hydroxyl group from the viewpoint of thermal conductivity. Also, the substitution position of R ¹¹ and R ¹⁴ is not particularly limited.

Further, R ¹² and R ¹³ in the general formula (III-a) 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 for R ¹² and R ¹³ include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, t-butyl, pentyl and hexyl Groups, heptyl groups, and octyl groups. Further, the substitution position of R ¹² and R ¹³ in the general formula (III-a) is not particularly limited.

Ar in the general formula (III-1) ~ formula (III-4), from the viewpoint of achieving a more excellent thermal conductivity, ^{R 11} in group (general formula (III-a) derived from a dihydroxy benzene hydroxyl And at least one selected from the group consisting of groups wherein R ¹² and R ¹³ are hydrogen atoms, and groups derived from dihydroxynaphthalene (groups where R ¹⁴ is a hydroxyl group in general formula (III-b)) Is preferred.

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

Further, from the viewpoint of productivity and fluidity of the epoxy resin composition, Ar is more preferably a group derived from dihydroxybenzene, and a group derived from 1,2-dihydroxybenzene (catechol) and 1,3- More preferably, it is at least one selected from the group consisting of groups derived from dihydroxybenzene (resorcinol). In particular, from the viewpoint of particularly enhancing the thermal conductivity, it is preferable to include a group derived from resorcinol as Ar.

When the compound having a structure represented by at least one selected from the group consisting of general formula (III-1) to general formula (III-4) contains a structural unit derived from resorcinol, a structural unit derived from resorcinol In view of elastic modulus, the content of at least one of the compounds having a structure represented by at least one selected from the group consisting of general formulas (III-1) to (III-4) in the total weight of the compound The content is preferably not less than 60% by mass, more preferably not less than 80% by mass, in view of the Tg and the linear expansion coefficient of the cured product. It is especially preferable that it is 90 mass% or more.

The m and n in the general formulas (III-1) to (III-4) are preferably m / n = 20/1 to 1/5 from the viewpoint of fluidity, and 20/1 to 5 / It is more preferably 1 and still more 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. The lower limit value of (m + n) is not particularly limited.

Compounds having a structure represented by at least one selected from the group consisting of general formula (III-1) to general formula (III-4) are, in particular, groups derived from Ar substituted or unsubstituted dihydroxybenzene and When it is at least one kind of group derived from substituted or unsubstituted dihydroxy naphthalene, its curing is easy as compared with a phenol resin etc. which simply made these novolakized, and a curing agent having a low softening point is It tends to be obtained. Therefore, the inclusion of such a phenol resin as a curing agent has the advantage of facilitating production and handling of the epoxy resin composition.

In addition, whether or not the phenol novolac resin has a partial structure represented by at least one selected from the group consisting of the above general formula (III-1) to the above general formula (III-4) depends on field desorption / ionization. It is judged by mass spectrometry (FD-MS) whether or not the component corresponding to the partial structure represented by any of the above general formula (III-1) to the above general formula (III-4) is contained as a fragment component thereof. can do.

The molecular weight of the compound having a structure represented by at least one selected from the group consisting of general formula (III-1) to general formula (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 still more preferably 350 to 1500. The weight average molecular weight (Mw) is preferably 2000 or less, more preferably 1500 or less, and still more preferably 400 to 1500. These Mn and Mw are measured by the usual method using GPC.

The hydroxyl equivalent of the compound having a structure represented by at least one selected from the group consisting of general formula (III-1) to general formula (III-4) is not particularly limited. From the viewpoint of the crosslink density involved in heat resistance, the hydroxyl group equivalent is preferably 50 g / eq to 150 g / eq on average, more preferably 50 g / eq to 120 g / eq, and more preferably 55 g / eq to 120 g / eq. More preferably, it is eq.

When a compound having a structure represented by at least one selected from the group consisting of General Formula (III-1) to General Formula (III-4) is used as a phenol-based curing agent, a general proportion of the phenol-based curing agent The proportion of the compound having a structure represented by at least one selected from the group consisting of Formula (III-1) to General Formula (III-4) is preferably 50% by mass or more, and 80% by mass or more Is more preferably 90% by mass or more.

Compounds having a structural unit represented by at least one selected from the group consisting of general formula (II-1) and general formula (II-2) as a phenolic curing agent, or general formula (III-1) to general formula When a compound having a structure represented by at least one selected from the group consisting of (III-4) is used, the phenolic curing agent is selected from the group represented by the general formula (II-1) and the general formula (II-2) A compound having a structural unit represented by at least one selected from the group consisting of: or a structure represented by at least one selected from the group consisting of general formula (III-1) to general formula (III-4) You may contain the monomer which is a phenol compound which comprises the compound which it has. The content ratio of the monomer which is a phenol compound (hereinafter, also referred to as “monomer content ratio”) is not particularly limited. From the viewpoint of thermal conductivity and moldability, the content is preferably 5% by mass to 80% by mass, more preferably 15% by mass to 60% by mass, and still more preferably 20% by mass to 50% by mass in the phenolic curing agent. It is further preferred that

When the monomer content ratio is 80% by mass or less, the amount of monomers not contributing to crosslinking decreases in the curing reaction, and the amount of crosslinked high molecular weight increases, so that a denser crosslinked structure is formed, and thermal conductivity Tend to improve. Moreover, since it is easy to flow at the time of shaping | molding by being 5 mass% or more, it exists in the tendency which adhesiveness with an inorganic filler improves more, and more excellent thermal conductivity and heat resistance can be achieved.

As an amine curing agent, those which are usually used can be used without particular limitation, and those which are commercially available may be used. The amine curing agent may be used alone or in combination of two or more. Among them, from the viewpoint of heat resistance, it is preferable to use an amine-based curing agent having a benzene ring or a naphthalene ring, and it is more preferable to use an amine-based curing agent having an amino group on the benzene ring or naphthalene ring. From the viewpoint of curability, it is preferable to use a polyfunctional amine-based curing agent having two or more amino groups.
When an epoxy resin having a mesogen skeleton is cured using an amine curing agent, a cured product having high toughness tends to be obtained.

As an amine curing agent, for example, 3,3'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl sulfone, 4,4'-diaminodiphenylmethane, 3,3'-diethyl-4,4'-diaminodiphenylmethane, 4 4,4'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 2,4,4'-triaminodiphenyl ether, 4,4'-diamino-2,2'-dimethylbiphenyl, 4,4'-diamino-3, 3'-dimethoxybiphenyl, 4,4'-diaminophenylbenzoate, 1,5-diaminonaphthalene, 1,3-diaminonaphthalene, 1,2-phenylenediamine, 1,3-phenylenediamine, 1,4-phenylenediamine, 4,4'-Diaminobenzanilide, 3,3'-diaminobenzanili , Trimethylene - bis-4-aminobenzoate, 1,4-diaminonaphthalene, and 1,8-diaminonaphthalene and the like. From the viewpoint of heat resistance, storage stability and the like, 4,4'-diaminodiphenyl sulfone is preferred.

The content of the curing agent is not particularly limited.
For example, when using a phenol-based curing agent as the curing agent, the equivalent number of active hydrogens of the phenolic hydroxyl group contained in the phenol-based curing agent (the equivalent number of phenolic hydroxyl groups) and the equivalent weight of the epoxy group contained in the epoxy resin The ratio to the number (number of equivalents of phenolic hydroxyl group / number of equivalents of epoxy group) is preferably 0.5 to 2.0, and more preferably 0.8 to 1.2.
Also, for example, when using an amine-based curing agent as the curing agent, the ratio of the number of equivalents of active hydrogen of the amine-based curing agent to the number of equivalents of epoxy groups of the epoxy resin The number of equivalents of active hydrogen / the number of equivalents of epoxy groups is preferably 0.3 to 3.0, and more preferably 0.5 to 2.0.

-Inorganic filler-
The epoxy resin composition contains an inorganic filler. This inorganic filler is the same as that described above as the inorganic filler contained in the protective material.

The content of the inorganic filler in the epoxy resin composition is 55% by volume to 95% by volume with respect to the total volume of the solid content of the epoxy resin composition from the viewpoints of thermal conductivity, moldability, mechanical strength, etc. The content is preferably 60% by volume to 95% by volume, and more preferably 70% by volume to 85% by volume. If the content of the inorganic filler is 55% by volume or more, high thermal conductivity tends to be achieved. On the other hand, when the content of the inorganic filler is 95% by volume or less, an epoxy resin composition having excellent moldability tends to be obtained.

In addition, in this indication, the solid content of an epoxy resin composition means the remaining component except the volatile component from an epoxy resin composition.

The content (volume%) of the inorganic filler in the epoxy resin composition is a value determined by the following equation.
Inorganic filler content (% by volume) = [(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 (mass%)
Bw: mass composition ratio of the curing agent (mass%)
Cw: mass composition ratio of inorganic filler (mass%)
Dw: mass composition ratio (% by mass) of a curing accelerator used as needed
Ew: mass composition ratio (mass%) of silane coupling agent used as needed
Fw: mass composition ratio (mass%) of other components used as needed
Ad: Specific gravity of epoxy resin Bd: Specific gravity of curing agent Cd: Specific gravity of inorganic filler Dd: Specific gravity of curing accelerator used as required Ed: Specific gravity of silane coupling agent used as needed Fd: Necessary Specific gravity of other ingredients used accordingly

The content ratio by weight of the inorganic filler in the epoxy resin composition can be appropriately adjusted depending on the type of the inorganic filler and the like. For example, when the inorganic filler is alumina, the content of the inorganic filler in the epoxy resin composition is preferably 80% by mass to 99% by mass with respect to the solid content of the epoxy resin composition, and 85 The content is more preferably in the range of 90% by mass to 90% by mass, and further preferably in the range of 90% by mass to 95% by mass.

-Hardening accelerator-
The epoxy resin composition may optionally contain a curing accelerator.
By using a curing accelerator together with the curing agent, the epoxy resin composition can be cured more sufficiently. The type and amount of the curing accelerator are not particularly limited, and may be selected appropriately from the viewpoint of reaction rate, reaction temperature, storage stability and the like. The curing accelerator may be used alone or in combination of two or more.

Specific examples of the curing accelerator include imidazole compounds, organic phosphorus compounds, tertiary amines, quaternary ammonium salts and the like. Among them, from the viewpoint of heat resistance, organic phosphine compounds; organic phosphine compounds maleic anhydride, quinone compounds (1,4-benzoquinone, 2,5-toluquinone, 1,4-naphthoquinone, 2,3-dimethylbenzoquinone, 2, 6-Dimethylbenzoquinone, 2,3-dimethoxy-5-methyl-1,4-benzoquinone, 2,3-dimethoxy-1,4-benzoquinone, phenyl-1,4-benzoquinone etc.), diazophenylmethane, phenol resin etc. A compound having an intramolecular polarization formed by adding a compound having a π bond; and a complex of an organic phosphine compound and an organic boron compound (tetraphenyl borate, tetra-p-tolyl borate, tetra-n-butyl borate, etc.); It is preferable that it is at least one selected from the group consisting of

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, dialkyl aryl phosphine Alkyl diaryl phosphine etc. are mentioned.

Specific examples of the imidazole compound include 2-undecylimidazole, 2-heptadecylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 1-benzyl-2 -Methylimidazole, 1-benzyl-2-phenylimidazole, 1- (1-cyanoethyl) -2-undecylimidazole, 1-cyano-2-phenylimidazole, 1-cyanoethyl-2-undecylimidazole trimellitate, 1 -Cyanoethyl-2-phenylimidazolium trimellitate, 2,4-diamino-6- [2'-methylimidazolyl- (1 ')]-ethyl-s-triazine, 2,4-diamino-6- [2' -Ethyl-4'-methylimidazolyl- (1 ')]-ethyl-s-to Azine, 2,4-diamino-6- [2′-methylimidazolyl- (1 ′)]-ethyl-s-triazine isocyanuric acid adduct, 2-phenylimidazole isocyanuric acid adduct, 2-phenyl-4,5- Examples thereof include dihydroxymethylimidazole, 2-phenyl-4-methyl-5-hydroxymethylimidazole, adducts of epoxy resins and imidazoles, and the like. The imidazole compound may be microencapsulated to increase its potential. The imidazole compound exemplified above is solid at normal temperature (25 ° C.) and is excellent in workability.

When the epoxy resin composition contains a curing accelerator, the content of the curing accelerator in the epoxy resin composition is not particularly limited. From the viewpoint of flowability and moldability, the content of the curing accelerator is preferably 0.1 mass% to 5.0 mass% with respect to the total mass of the epoxy resin and the curing agent, 0.5 mass More preferably, it is% to 3% by mass.

-Silane coupling agent-
The epoxy resin composition may optionally contain a silane coupling agent. When the epoxy resin composition contains a silane coupling agent, an interaction is caused between the surface of the inorganic filler and the epoxy resin surrounding the surface, flowability is improved, high thermal conductivity is achieved, and further, The insulation reliability tends to be improved by preventing the entry of moisture.

The type of silane coupling agent is not particularly limited, and one type may be used alone, or two or more types may be used in combination. Among them, silane coupling agents having a phenyl group are preferred. The silane coupling agent containing a phenyl group is likely to interact with the epoxy resin having a mesogen skeleton. For this reason, when an epoxy resin composition contains the silane coupling agent containing a phenyl group, when it is set as hardened | cured material, it exists in the tendency for more superior thermal conductivity to be achieved.

The type of silane coupling agent containing a phenyl group is not particularly limited. Specific examples of the silane coupling agent having a phenyl group include 3-phenylaminopropyltrimethoxysilane, 3-phenylaminopropyltriethoxysilane, N-methylanilinopropyltrimethoxysilane, N-methylanilinopropyltriethoxy Silanes, 3-phenyliminopropyltrimethoxysilane, 3-phenyliminopropyltriethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, diphenyldimethoxysilane, diphenyldiethoxysilane, triphenylmethoxysilane, triphenylethoxysilane, etc. It can be mentioned. The phenyl coupling agents may be used alone or in combination of two or more. A commercially available silane coupling agent containing a phenyl group may be used.

It is preferable that the ratio of the silane coupling agent which has a phenyl group to the whole silane coupling agent is 50 mass% or more, It is more preferable that it is 80 mass% or more, It is more preferable that it is 90 mass% or more .

From the viewpoint of achieving excellent thermal conductivity by bringing the surface of the inorganic filler and the epoxy resin surrounding it close to each other and achieving excellent thermal conductivity, it contains a silane coupling agent in which a phenyl group is directly bonded to a silicon atom (Si) It is also good.

When the silane coupling agent contains a silane coupling agent in which a phenyl group is directly bonded to a silicon atom (Si), the phenyl group is directly bonded to a silicon atom (Si) in the silane coupling agent having a phenyl group The proportion of the silane coupling agent is preferably 30% by mass or more, more preferably 50% by mass or more, and still more preferably 80% by mass or more.

When the epoxy resin composition contains a silane coupling agent, the silane coupling agent may be present in the state of being attached to the surface of the inorganic filler or in the state of not being attached to the surface of the inorganic filler. , And both may be mixed.

When at least a part of the silane coupling agent adheres to the surface of the inorganic filler, the adhesion amount of silicon atoms derived from the silane coupling agent per specific surface area of the inorganic filler is 5.0 × 10 ⁻⁶ mol / M ² to 10.0 × 10 ⁻⁶ mol / m ² is preferable, 5.5 × 10 ⁻⁶ mol / m ² to 9.5 × 10 ⁻⁶ mol / m ² is more preferable, and 6.0 × 10 6 More preferably, it is ⁻⁶ mol / m ² to 9.0 × 10 ⁻⁶ mol / m ² .

The measuring method of the coating amount of the silicon atom derived from the silane coupling agent per specific surface area of an inorganic filler is as follows.
First, the BET method is mainly applied as a method of measuring the specific surface area of the inorganic filler. The BET method is a gas adsorption method in which inert gas molecules such as nitrogen (N ₂ ), argon (Ar), krypton (Kr) and the like are adsorbed on solid particles and the specific surface area of solid particles is measured from the amount of adsorbed gas molecules. It is a law. The measurement of the specific surface area can be performed using a specific surface area pore distribution measuring apparatus (for example, manufactured by Beckman Coulter, SA3100).

Furthermore, silicon atoms derived from the silane coupling agent present on the surface of the inorganic filler are quantified. The quantitative method includes ²⁹ Si CP / MAS (Cross-Polarization / Magic angle spinning) solid-state NMR (nuclear magnetic resonance). A nuclear magnetic resonance apparatus (for example, JNM-ECA700 manufactured by Nippon Denshi Co., Ltd.) has high resolution, and therefore, even when the epoxy resin composition contains silica as an inorganic filler, the silicon atom derived from silica as an inorganic filler It is possible to distinguish it from the silicon atom derived from the silane coupling agent.
When the epoxy resin composition does not contain a silicon atom other than the silicon atom derived from the silane coupling agent, the silicon atom derived from the silane coupling agent is also quantified by a fluorescent X-ray analyzer (for example, Supermini 200 manufactured by Rigaku Corporation) can do.

Silane coupling agent per specific surface area of the inorganic filler, based on the specific surface area of the inorganic filler obtained as described above and the amount of silicon atoms derived from the silane coupling agent present on the surface of the inorganic filler The coating amount of the silicon atom derived from is calculated.

In performing the said measurement, the inorganic filler contained in the epoxy resin composition can be taken out from an epoxy resin composition by the method mentioned below, for example.
(1) The epoxy resin composition is placed in a porcelain crucible and heated (eg, 600 ° C.) in a muffle furnace or the like to burn the resin component.
(2) The resin component of the epoxy resin composition is dissolved in a suitable solvent, and the inorganic filler is recovered by filtration and dried.

When the epoxy resin composition contains a silane coupling agent, the method of adding the silane coupling agent to the epoxy resin composition is not particularly limited. Specifically, an integral method in which a silane coupling agent is also added when mixing other materials such as an epoxy resin and an inorganic filler, a silane coupling agent is mixed with a small amount of resin, and then this is used as an inorganic filler Before mixing with other materials such as masterbatch method and epoxy resin mixed with other materials, etc., the inorganic filler and the silane coupling agent are mixed and the silane coupling agent is previously added to the surface of the inorganic filler. There is a pretreatment method to be processed. As a pretreatment method, a dry method in which a stock solution or a solution of a silane coupling agent is dispersed by high speed stirring with an inorganic filler and treated, a slurry of the inorganic filler with a dilute solution of a silane coupling agent, an inorganic filler The wet method etc. which perform a silane coupling agent process on the inorganic filler surface by immersing a silane coupling agent etc. are mentioned.

-Other ingredients-
The epoxy resin composition may contain other components in addition to the components described above. Other components include release agents such as oxidized and non-oxidized polyolefins, carnauba wax, montanic acid ester, montanic acid, stearic acid and the like; silicone oil, silicone rubber powder, polymer elastomer such as acrylic and imide, etc. Stress relaxation agents; Reinforcing materials such as glass fibers; Coloring materials such as carbon; Phosphorous-based and hydroxide-based flame retardants; Defoaming materials for void suppression and the like. The other components may be used alone or in combination of two or more.

-Method of preparing epoxy resin composition-
The preparation method of the epoxy resin composition is not particularly limited. As a general method, after the components are sufficiently mixed by a mixer or the like, a method of melt-kneading, cooling and pulverizing may be mentioned. Melt-kneading can be carried out with a kneader, roll, extruder or the like which has been heated to 70 ° C. to 140 ° C. The epoxy resin composition is easy to use when it is tableted in such a size and mass as to meet molding conditions.

The thick copper circuit with protective material may further have an insulating layer in the thickness direction of the thick copper circuit. The width and length of the insulating layer may be the same as or different from that of the protected thick copper circuit.
The method for arranging the insulating layer in the thickness direction of the thick copper circuit is not particularly limited. For example, a method of affixing a sheet-like insulating layer in the thickness direction of a thick-layer copper circuit with a protective material and performing curing treatment as needed, and a method of integrally molding a thick copper circuit with a protective material and an insulating layer .

<Method of producing thick copper circuit with protective material>
There is no particular limitation on the method of producing the protective copper circuit. For example, it can be produced as follows.
First, a copper plate is punched and cut by cutting or the like to form a circuit having a desired shape. Next, the prepared circuit is disposed on a temporary base such as an adhesive film. If necessary, burrs, residues and the like generated during circuit formation may be removed. After that, a protective material is formed on the space between the circuits and the outer edge of the circuits as needed, and a curing process is performed as needed. Thereafter, the temporary base material is peeled off from the circuit. Next, removal of burrs generated during formation of the resin portion, post curing treatment of the resin, and the like are performed as necessary to obtain a thick copper circuit.

The method of arranging the protective material in the space between the thick copper circuits is not particularly limited. For example, extrusion molding method, compression molding method, transfer molding method, insert molding method etc. may be mentioned as a method of using solid resin material such as powder, etc. As a method of using liquid resin material, casting method, coating method, printing Law, embedding method, etc. When disposing the protective material in the space between the thick copper circuits, the thick copper circuits may be disposed on a temporary base material such as a resin sheet. In particular, when the protective material is disposed on the thick copper circuit by the transfer molding method, the protective material can be disposed without an air gap between the circuits, so the adhesion with the thick copper circuit is improved, and the thick copper circuit and the protective material are It tends to be able to suppress voids and the like at the interface. Therefore, insulation reliability tends to be improved.

The temperature of the mold at the time of molding is not particularly limited, and may be 150 ° C. to 200 ° C. When using an epoxy resin composition containing an epoxy resin having a mesogen skeleton and having a phase transition temperature of 140 ° C. or less which causes a phase transition from a crystalline phase to a liquid crystal phase as the protective material, the phase transition temperature of the epoxy resin is 150 ° C. or higher It is preferable to set it as the following, and it is more preferable to set it as 140 degrees C or less. When the temperature is above the phase transition temperature of the epoxy resin, the epoxy resin is sufficiently melted and easily molded at the time of molding, and when it is 150 ° C. or less, the thermal conductivity of the molded product tends to be excellent.

The molded product preferably has a diffraction peak in the range of a diffraction angle 2θ of 3.0 ° to 3.5 ° in an X-ray diffraction spectrum obtained by an X-ray diffraction method using a CuKα ray. A molded product having such a diffraction peak has a smectic structure which is particularly high among the higher-order structures, and is excellent in thermal conductivity.

The details of the X-ray diffraction measurement using the CuKα ray in the present disclosure are as follows.
〔Measurement condition〕
Device used: X-ray diffractometer ATX-G (manufactured by Rigaku Corporation) for thin film structure evaluation
X-ray type: CuKα
Scanning mode: 2θ / ω
Output: 50kV, 300mA
S1 slit: Width 0.2 mm, height: 10 mm
S2 slit: Width 0.2 mm, height: 10 mm
RS slit: Width 0.2 mm, height: 10 mm
Measurement range: 2θ = 2.0 ° to 4.5 °
Sampling width: 0.01 °

The protective material may be used as it is after being molded and removed from the mold, or may be used after being post-cured by heating in an oven or the like, if necessary.

When the molded product is post-cured by heating, a molded cured product is obtained. The heating conditions of the molded product can be appropriately selected according to the type and amount of the components contained in the protective material. For example, the heating temperature of the molding is preferably 130 ° C. to 200 ° C., and more preferably 150 ° C. to 180 ° C. The heating time of the molding is preferably 1 hour to 10 hours, more preferably 2 hours to 6 hours.

When using the epoxy resin composition containing the epoxy resin which has a mesogen frame as a protective material, a shaping | molding hardening thing is the X-ray diffraction obtained by the X ray diffraction method using a CuK alpha ray similarly to the molding before post-hardening In the spectrum, it is preferable that the diffraction angle 2θ has a diffraction peak in the range of 3.0 ° to 3.5 °. This indicates that the highly ordered smectic structure formed in the molded product can be maintained even after post curing by heating, and a molded cured product having excellent thermal conductivity can be obtained.

EXAMPLES The present invention will next be described in more detail by way of examples, which should not be construed as limiting the scope of the present invention. In addition, unless there is particular notice, "part" and "%" are mass references.

<Preparation of Epoxy Resin Composition>
Below, the material used for the synthesis | combination of an epoxy resin and its abbreviation are shown.

Epoxy resin monomer 1 (trans-4- {4- (2,3-epoxypropoxy) phenyl} cyclohexyl = 4- (2,3-epoxypropoxy) benzoate, see Japanese Patent No. 5471975, epoxy equivalent: 212 g / Eq)

・ Phenol compound 1
Compound name: hydroquinone (hydroxy group equivalent: 55 g / eq)
・ Synthetic solvent 1
Cyclohexanone (boiling point: 156 ° C)
・ Reaction catalyst 1
Triphenylphosphine (made by Hokuko Chemical Industry Co., Ltd., molecular weight: 262)

[Synthesis of Epoxy Resin 1]
50 g (0.118 mol) of epoxy resin monomer 1 was weighed into a 500 mL three-necked flask, and 80 g of synthesis solvent 1 (cyclohexanone) was added thereto. A cooling pipe and a nitrogen introducing pipe were placed in a three-necked flask, and a stirring blade was attached so as to be immersed in a solvent. The three-necked flask was immersed in an oil bath at 160 ° C. to start stirring. After several minutes, it was confirmed that the epoxy resin monomer 1 was dissolved, and it became a clear solution, and then 1.3 g (0.0118 mol) of the phenol compound 1 (hydroquinone) was added to the flask, and then the reaction catalyst 1 (triphenyl) was added. 0.5 g of phosphine) was added and heating was continued at an oil bath temperature of 160.degree. After continuing heating for 5 hours, the epoxy resin 1 was obtained by cooling the residue which vacuum-distillated cyclohexanone from the reaction solution to room temperature. The epoxy resin 1 also contains a part of the synthesis solvent and an unreacted epoxy resin monomer.

The solid content of the epoxy resin 1 was measured by a heat loss method and found to be 96.3% by mass. In addition, 1.0 g-1.1 g of epoxy resin 1 was weighed in an aluminum cup, and the solid content was measured for 30 minutes in a dryer set at a temperature of 180 ° C., and the measured amount before heating. Based on the following equation.
Solid content (mass%) = (measured after leaving for 30 minutes / measured before heating) × 100

It was 256 g / eq when the epoxy equivalent of the epoxy resin 1 was measured by the perchloric-acid titration method. In addition, the softening point of the epoxy resin 1 was measured by the ring and ball method, and was 75 ° C. to 80 ° C.

[Synthesis of Epoxy Resin 2]
An epoxy resin 2 was obtained in the same manner as in Example 1 except that the amount of the phenolic compound 1 (hydroquinone) added was changed to 2.5 g (0.0227 mol). The epoxy resin 2 also contains a part of the synthesis solvent and an unreacted epoxy resin monomer.
The solid content of the epoxy resin 2 was measured by a heat loss method and found to be 96.1% by mass. Moreover, it was 320 g / eq when the epoxy equivalent of the epoxy resin 2 was measured by a perchloric-acid titration method.
The softening point of the epoxy resin 2 was measured by the ring and ball method and was 70 ° C. to 80 ° C.

[Preparation of Epoxy Resin Composition]
The components shown below are weighed out in proportions (parts by mass) shown in Table 1 and kneaded with a kneader preheated to 70 ° C. to 140 ° C., cooled and pulverized to give epoxy resins of Examples and Comparative Examples. The composition was prepared.

・ Epoxy resin 1
・ Epoxy resin 2
・ Epoxy resin 3: Biphenyl type epoxy resin, Mitsubishi Chemical Corporation, product name "YX-4000")
・ Epoxy resin 4 ... bisphenol F type epoxy resin, Nippon Steel & Sumikin Chemical Co., Ltd., product name "YSLV-70XY")

Curing agent 1: Aromatic diamine, Wakayama Seika Kogyo Co., Ltd. 4,4'-diaminodiphenyl sulfone Curing agent 2. Aromatic diamine, Wakayama Seika Kogyo Co., Ltd. 3,4'-diaminodiphenyl ether · Hardener 3 ... Multifunctional phenolic resin, Air Water Co., Ltd., product name "HE 910"

-Hardening accelerator 1-Phosphorus-based hardening accelerator-Coupling agent-Silane coupling agent, Shin-Etsu Chemical Co., Ltd., product name "KBM-573"

· Inorganic filler 1 · · · D50 volume average particle diameter 29.0μm alumina particles · inorganic filler 2 ... D50 volume average particle diameter 21.0μm alumina particles · inorganic filler 3 · D 50 volume average particle diameter 5.5μm alumina Particles · Inorganic filler 4 ... D50 Alumina particles · Inorganic filler 5 with a volume average particle diameter of 14.9 μm · · · A50 particles with a volume average particle diameter of 2.0 μm · Inorganic fillers 6 ... with a volume average particle diameter of 0.4 μm Alumina particles

Releasing agent: Montanic acid ester (Licowax E, manufactured by Clariant Japan Co., Ltd.)

In Examples 1 to 5, the content of the inorganic filler is 55% by volume to 95% by volume with respect to the total volume of the protective material, and in Comparative Example 1, the content of the inorganic filler is the entire content of the protective material. Less than 55% by volume with respect to the product.

(Evaluation of liquidity)
The evaluation of the flowability of the epoxy resin composition was performed by a spiral flow test.
Specifically, the epoxy resin composition was molded using a spiral flow measurement mold according to EMMI-1-66, and the flow distance (cm) of the molded product of the epoxy resin composition was measured. Molding of the epoxy resin composition was performed using a transfer molding machine under conditions of a mold temperature of 180 ° C., a molding pressure of 6.9 MPa, and a curing time of 120 seconds. Moreover, fluidity | liquidity made A 50 cm or more into B, and set less than 50 cm.

(Evaluation of high temperature adhesion)
The high temperature adhesiveness evaluation of the epoxy resin composition was performed by the following. Transfer molding was performed on a Cu substrate under conditions of a mold temperature of 180 ° C., a molding pressure of 7 MPa, and a curing time of 300 seconds to obtain a cured product having a thickness of 0.4 mm. This was allowed to stand on a hot plate heated to 280 ° for 15 minutes. The appearance after cooling and observation using an ultrasonic imaging apparatus (SAT) and having no peeling was designated as A, and the one where peeling was observed was designated as B.

(Evaluation of thermal conductivity)
The evaluation of the thermal conductivity of the epoxy resin composition was performed as follows. Specifically, transfer molding was performed using the prepared epoxy resin composition under conditions of a mold temperature of 180 ° C., a molding pressure of 7 MPa, and a curing time of 300 seconds, to obtain a cured product of a mold shape. The specific gravity of the obtained cured product measured by the Archimedes method was 3.00. Further, the thermal diffusivity of the cured product was measured by a laser flash method using a thermal diffusivity measuring device (manufactured by NETZSCH, LFA 467). Further, the thermal conductivity is A at 7 W / (m · K) or more, and B at less than 7 W / (m · K).

(Observation of circuit deformation)
The appearance of the circuit was observed by appearance observation and laser displacement meter.

As shown in Table 2, when the protective material contained 55% by volume to 95% by volume of the inorganic filler, deformation of the thick copper circuit was suppressed. Further, in Examples 1 to 3 in which the epoxy resin having a mesogen skeleton and the amine curing agent were used, good evaluations were obtained for all of the fluidity, the high temperature adhesion, and the thermal conductivity.

The disclosure of Japanese Patent Application No. 2017-182264 is incorporated herein by reference in its entirety.
All documents, patent applications, and technical standards described herein are as specific and individually as individual documents, patent applications, and technical standards are incorporated by reference. Hereby incorporated by reference.

10 thick copper circuit with protective material 12 thick copper circuit 14 protective material 16 inorganic filler 18 space between thick copper circuits

Claims

Thick copper circuit,
A protective material disposed in the space between the thick copper circuits and containing 55% by volume to 95% by volume of an inorganic filler;
Thick copper circuit with protective material.
The thick protective copper circuit according to claim 1, wherein the protective material is a resin composition or a cured product thereof.
The thick-copper circuit with a protective material according to claim 2, wherein the resin composition is an epoxy resin composition containing an epoxy resin, a curing agent, and the inorganic filler.
The thick protective copper circuit according to claim 3, wherein the epoxy resin comprises an epoxy resin having a mesogen skeleton.
The thick copper circuit with a protective material according to claim 4, wherein the phase transition temperature at which phase transition from a crystalline phase to a liquid crystal phase in the epoxy resin having a mesogen skeleton is 140 ° C or less.
The protected material-thick copper circuit according to claim 4 or 5, wherein the epoxy resin having a mesogen skeleton contains a reaction product of a phenol compound and an epoxy compound having a mesogen skeleton.
The thick copper circuit with a protective material according to claim 6, wherein the epoxy compound having a mesogen skeleton contains a compound represented by the following general formula (I-0).

(In the general formula (I-0), R 1 to R 4 each independently represent a hydrogen atom or an alkyl group having 1 to 3 carbon atoms.)
The thick protective copper circuit according to any one of claims 3 to 7, wherein the curing agent comprises an amine curing agent.
The protected thick copper circuit of claim 8, wherein the amine based curing agent comprises 4,4'-diaminodiphenyl sulfone.
The thick protective copper circuit according to any one of claims 2 to 9, wherein the protective material is a transfer molded product of the resin composition.
The protective thickened copper circuit according to any one of claims 1 to 10, wherein the protective material is further disposed around the thick copper circuit.
The protective copper circuit according to any one of claims 1 to 11, further comprising an insulating layer in the thickness direction of the thick copper circuit.