JP2016079304A - Resin sheet, resin sheet cured product, resin sheet laminate, resin sheet laminate cured product and method for producing the same, semiconductor device, and led device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resin sheet excellent in shear adhesion, insulation properties and thermal conductivity after curing.SOLUTION: A resin sheet contains a resin and an inorganic filler, and has a melt viscosity at 100°C of 1×10Pa s to 1×10Pa s. A specific area of the inorganic filler is 1.0 m/g to 6.5 m/g. A ratio of particles having a particle size of 25 μm to 100 μm with respect to the inorganic filler when measured by a laser diffraction method is 30 vol.% to 80 vol.%, and a reactivity ratio is 20% or less.SELECTED DRAWING: None

Description

  The present invention relates to a resin sheet, a resin sheet cured product, a resin sheet laminate, a resin sheet laminate cured product, a manufacturing method thereof, a semiconductor device, and an LED device.

  With the progress of miniaturization, large capacity, high performance, etc. of electronic devices using semiconductors, the amount of heat generated from semiconductors mounted at high density is increasing. For example, for stable operation of a semiconductor device used to control a central processing unit of a personal computer and a motor of an electric vehicle, a heat sink, a heat radiating fin, etc. are indispensable for heat dissipation, and a member that couples the semiconductor device and the heat sink, etc. Therefore, there is a demand for a material that achieves both insulation and thermal conductivity and has high reliability even in a high-temperature operating environment.

  In general, an organic material is widely used as an insulating material for a printed circuit board or the like on which a semiconductor device or the like is mounted. Although these organic materials have high insulation properties, they have low thermal conductivity and do not contribute significantly to heat dissipation of semiconductor devices and the like. On the other hand, inorganic materials such as inorganic ceramics are sometimes used for heat dissipation of semiconductor devices and the like. Although these inorganic materials have high thermal conductivity, since semiconductor devices and the like are bonded to inorganic materials such as inorganic ceramics via grease, it is difficult to say that connection reliability is sufficient compared to organic materials.

  In relation to the above, various materials in which a resin is combined with an inorganic filler with high thermal conductivity called a filler have been studied. For example, an epoxy resin composition having a low melt viscosity and capable of being filled with a high filler is known (see, for example, Patent Document 1). Further, a cured product composed of a composite system of a general bisphenol A type epoxy resin and an alumina filler is known. The heat of 3.8 W / mK in the xenon flash method and 4.5 W / mK in the temperature wave thermal analysis method. The conductivity can be achieved (for example, see Patent Document 2). Similarly, a cured product composed of a composite system of a special epoxy resin, an amine curing agent and an alumina filler is known, and a thermal conductivity of up to 9.8 W / mK can be achieved (for example, (See Patent Document 3). Moreover, in patent document 4, it is supposed that the resin sheet hardened | cured material excellent in all of heat conductivity, adhesive strength, and insulation, and the resin sheet and resin composition which can form this resin sheet hardened | cured material can be obtained. . In particular, it is said that a resin sheet excellent in insulation under high temperature and high humidity can be provided.

JP 2001-055425 A JP 2008-013759 A International Publication No. 2011/040416 International Publication No. 2012/133587

  The cured resin described in Patent Document 1 is characterized by having a high glass transition temperature using a highly cross-linked epoxy resin with a dense reaction point and a phenolic resin derived from dihydroxybenzene. However, there are many reactive sites, and the hydroxyl group derived from the epoxy group as a by-product increases the water absorption rate in the cured product, which may adversely affect the insulating properties (especially the insulating properties when absorbing moisture). it is conceivable that.

  In the cured resin described in Patent Document 2, it is considered that it may be difficult to achieve both high thermal conductivity and adhesive strength with an adherend at a high level. When a phenol compound is used as the curing agent, the viscosity of the resin composition tends to increase, and it is necessary to increase the press pressure and temperature during curing when obtaining adhesive strength with the adherend. In particular, since aluminum oxide is used for the filler, it is considered that sufficient strength cannot be obtained.

  In Patent Document 3, a special epoxy resin monomer having a mesogenic structure is used. Patent Document 3 is characterized by increasing the thermal conductivity of the resin itself by melting the resin and self-aligning the mesogenic structure during flow and curing. Such a resin needs to increase the proportion of the mesogen site in the resin skeleton, and accordingly, the monomer before curing has a high melting point, and the cured product of the monomer has a high elastic modulus. Adhesion is considered disadvantageous.

  Further, the cured resin described in Patent Document 4 is said to be excellent in thermal conductivity and shear bond strength near room temperature. However, since it contains a lot of low-strength boron nitride in the resin composition, it is necessary to add a liquid epoxy resin for B-stage, there is no description about the glass transition temperature, etc. There is concern about a decrease in adhesive strength at a temperature of 100 ° C. or higher.

  As a technical problem shown in Patent Documents 1 to 4, when a mesogenic structure-containing epoxy resin, novolac resin, or the like is used, since the melting point is high before curing, it is difficult to handle and it is difficult to obtain sufficient adhesive strength. It is considered that it may be difficult to wet the adherend. Since it has a high elastic modulus after curing, thermal stress may be a problem during bonding with dissimilar metals.

  The present invention relates to a resin sheet excellent in shearing adhesiveness, insulation and thermal conductivity after curing, a cured resin sheet using the same, a resin sheet laminate, a resin sheet laminate cured product, a method for producing the same, and a semiconductor device In addition, an LED (Light Emitting Diode) device is provided.

Specific means for achieving the above object are as follows.
<1> Contains a resin and an inorganic filler,
The melt viscosity at 100 ° C. is 1.0 × 10 ⁵ Pa · s to 1.0 × 10 ⁸ Pa · s,
The specific surface area of the inorganic filler is 1.0m ² /g~6.5m ² / g,
When measured by a laser diffraction method, the proportion of particles having a particle diameter of 25 μm to 100 μm in the inorganic filler is 30% by volume to 80% by volume,
A resin sheet having a reaction rate of 20% or less.

<2> The resin sheet according to <1>, wherein an average particle diameter determined from a specific surface area of the inorganic filler is 0.4 μm to 2.7 μm.

<3> The resin sheet according to <1> or <2>, wherein the resin contains an epoxy resin and further contains a curing agent.

<4> The above epoxy resin contains a trifunctional or higher functional first epoxy resin having a structure in which two naphthalene rings are included in a molecule and the two naphthalene rings are connected by an alkylene chain. Resin sheet.

<5> The resin sheet according to <4>, wherein the first epoxy resin contains a compound represented by the following general formula (I).

(In General Formula (I), R ¹ represents an alkylene group having 1 to 7 carbon atoms.)

<6> The resin sheet according to any one of <1> to <5>, wherein the inorganic filler includes at least one selected from the group consisting of boron nitride, aluminum oxide, and aluminum hydroxide.

<7> Any one of <1> to <6>, wherein the tensile elastic modulus in the C stage state is 0.1 GPa to 30 GPa, and the tensile fracture strain in the C stage state is 0.10% to 0.70%. The resin sheet as described in 2.

<8> A first resin layer containing the resin and the inorganic filler, and a second resin layer containing the resin and the inorganic filler laminated on the first resin layer. The resin sheet according to any one of <1> to <7>.

<9> A cured resin sheet, which is a heat-treated product of the resin sheet according to any one of <1> to <8>.

<10> A resin sheet laminate comprising the resin sheet according to any one of <1> to <8> and a metal plate or a heat radiating plate disposed on at least one surface of the resin sheet.

<11> The resin sheet laminate according to <10>, further including an adherend on a surface opposite to a surface on which the metal plate or the heat radiating plate of the resin sheet is disposed.

<12> A cured resin sheet laminate, which is a heat-treated product of the resin sheet laminate according to <10> or <11>.

<13> A step of arranging a metal plate or a heat radiating plate on at least one surface of the resin sheet according to any one of <1> to <8>,
Curing the resin sheet by applying heat to the resin sheet;
The manufacturing method of the resin sheet laminated body hardened | cured material which has this.

<14> a semiconductor element;
The resin sheet cured product according to <9>, which is disposed on the semiconductor element,
A semiconductor device comprising:

The LED device by which a <15> LED element, the resin sheet hardened | cured material as described in <9>, and a board | substrate are laminated | stacked in this order.

  According to the present invention, a cured resin sheet having excellent shear adhesion, insulation and thermal conductivity, and a cured resin sheet using the resin sheet, a resin sheet laminate, a resin sheet laminate cured product, and a method for producing the same, Semiconductor devices and LED devices are provided.

It is a schematic cross section which shows an example of a structure of the power semiconductor device comprised using the resin sheet hardened | cured material of this invention. It is a schematic cross section which shows an example of a structure of the power semiconductor device comprised using the resin sheet hardened | cured material of this invention. It is a schematic cross section which shows an example of a structure of the power semiconductor device comprised using the resin sheet hardened | cured material of this invention. It is a schematic cross section which shows an example of a structure of the power semiconductor device comprised using the resin sheet hardened | cured material of this invention. It is a schematic cross section which shows an example of a structure of the power semiconductor device comprised using the resin sheet hardened | cured material of this invention. It is a schematic cross section which shows an example of a structure of the power semiconductor device comprised using the resin sheet hardened | cured material of this invention. It is a schematic cross section which shows an example of a structure of the LED light bar comprised using the resin sheet hardened | cured material of this invention. It is a schematic cross section which shows an example of a structure of the LED light bulb comprised using the resin sheet hardened | cured material of this invention. It is a schematic cross section which shows an example of a structure of the LED light bulb comprised using the resin sheet hardened | cured material of this invention. It is a schematic cross section which shows an example of a structure of the LED board comprised using the resin sheet hardened | cured material of this invention.

In this specification, the term “process” is not limited to an independent process, and is included in the term if the intended purpose of the process is achieved even when it cannot be clearly distinguished from other processes. . Moreover, the numerical range shown using "to" shows the range which includes the numerical value described before and behind "to" as a minimum value and a maximum value, respectively. Furthermore, the content of each component in the composition means the total amount of the plurality of substances present in the composition unless there is a specific notice when there are a plurality of substances corresponding to each component in the composition.
In this specification, the term “layer” includes a configuration formed in a part in addition to a configuration formed in the entire surface when observed as a plan view.
In this specification, the term “lamination” indicates that layers are stacked, and two or more layers may be combined, or two or more layers may be detachable.

The resin sheet of the present invention contains a resin and an inorganic filler, has a melt viscosity at 100 ° C. of 1.0 × 10 ⁵ Pa · s to 1.0 × 10 ⁸ Pa · s, and has a specific surface area of the inorganic filler. There is 1.0m ² /g~6.5m ² / g, when measured by a laser diffraction method, the ratio of particles having a particle size of 25μm~100μm occupied in the inorganic filler is 30 vol% to 80 vol% It is a resin sheet having a reaction rate of 20% or less.
The resin sheet of the present invention may further contain other components as necessary.

When the resin sheet having such a configuration is cured, a cured resin sheet having excellent shear adhesion, insulation, and thermal conductivity can be obtained. This can be thought of as follows.
When the resin sheet of the present invention is interposed between members such as a metal plate, a heat radiating plate, and an adherend, these members are more likely to be bonded without causing voids at the bonding interface. Further, the resin sheet of the present invention contains an inorganic filler having a large specific surface area such as a specific surface area of 1.0 m ² / g or more, so that thixotropic property is imparted to the resin and the resin outflow at the time of adhesion is prevented. On the other hand, the fluidity of the resin sheet can be ensured by containing an inorganic filler having a specific surface area of not more than 6.5 m ² / g. As a result, insulation is ensured.
Moreover, thermal conductivity can also be improved by making the ratio of the particle | grains which have a particle diameter of 25 micrometers-100 micrometers in an inorganic filler into 30 volume%-80 volume%. Furthermore, if the thermal conductivity is high, there is no need to make the inorganic filler highly filled in the resin sheet, so that the increase in the elastic modulus of the resin sheet and the improvement in the elongation rate can be achieved. Can also be improved.
For this reason, the hardened | cured material which is excellent in the shear adhesiveness after hardening, insulation, and heat conductivity can be obtained.
Moreover, the reaction rate of the resin sheet of this invention shall be 20% or less. When the reaction rate of the resin sheet exceeds 20%, adhesion failure and insulation failure may occur. The reaction rate of the resin sheet of the present invention is preferably 18% or less, and more preferably 15% or less.
In the present invention, the reaction rate of the resin sheet refers to a value measured by the following method.
The amount of heat of the curing reaction for the resin sheet before the heat treatment at 30 ° C. for 48 hours is measured by a differential scanning calorimeter, and this is defined as (the amount of heat for the curing reaction of the resin sheet before the heat treatment at 30 ° C. for 48 hours). On the other hand, the amount of heat of the curing reaction for the resin sheet after heat treatment at 30 ° C. for 48 hours was measured with a differential scanning calorimeter, and this was calculated as (the amount of heat for the curing reaction of the resin sheet after heat treatment at 30 ° C. for 48 hours). To do. Based on the value of (the amount of heat of the curing reaction of the resin sheet before heat treatment at 30 ° C. for 48 hours) and the value of (the amount of heat of the curing reaction of the resin sheet after heat treatment at 30 ° C. for 48 hours), The reaction rate is calculated.

(Reaction rate of resin sheet (%)) = {1- (heat amount of resin sheet curing reaction after heat treatment at 30 ° C. for 48 hours) / (heat amount of resin sheet curing reaction before heat treatment at 30 ° C. for 48 hours)} × 100

  Hereinafter, each component which comprises the resin sheet of this invention is demonstrated in detail.

(Inorganic filler)
The resin sheet of the present invention contains an inorganic filler. The material of the inorganic filler is not particularly limited as long as it is an inorganic compound having insulating properties. The material of the inorganic filler is preferably one having high thermal conductivity and volume resistivity. Specific examples include aluminum oxide (alumina), aluminum oxide hydrate, magnesium oxide, boron nitride, aluminum nitride, silicon nitride, talc, mica, aluminum hydroxide, barium sulfate, and the like. Among these, from the viewpoint of thermal conductivity and insulation, it is preferably at least one selected from the group consisting of aluminum oxide, boron nitride, aluminum nitride and aluminum hydroxide, and a group consisting of boron nitride, aluminum oxide and aluminum hydroxide At least one selected from the above is more preferable, and boron nitride is more preferable. An inorganic filler may be used individually by 1 type, or may be used in combination of 2 or more type.

Inorganic filler contained in the resin sheet of the present invention is a specific surface area of 1.0m ² /g~6.5m ² / g, when measured by a laser diffraction method, of 25μm~100μm occupying the inorganic filler particles The ratio of the diameter particles is in the range of 30% to 80% by volume. By containing an inorganic filler in this range, there is a tendency to obtain a cured product having excellent shear adhesion, insulation and thermal conductivity.
If the specific surface area of the inorganic filler is less than 1.0 m ² / g, the resin may flow out during bonding. On the other hand, if the specific surface area of the inorganic filler exceeds 6.5 m ² / g, the fluidity of the resin sheet may not be ensured.
The specific surface area of the inorganic filler used in the present invention is ^preferably 1.1m ² /g~6.0m 2 / ^g, more preferably ^{1.2m 2 /g~5.5m 2 / g, 1.3m} 2 / More preferably, it is g-5.0m < ² > / g.

When the proportion of particles having a particle diameter of 25 μm to 100 μm in the inorganic filler is less than 30% by volume, the thermal conductivity tends to be low. On the other hand, when the ratio of particles having a particle diameter of 25 μm to 100 μm in the inorganic filler exceeds 80% by volume, the adhesiveness tends to decrease.
In the inorganic filler used in the present invention, the proportion of particles having a particle diameter of 25 μm to 100 μm in the inorganic filler when measured by a laser diffraction method is preferably 33% by volume to 80% by volume, and 36% by volume. % To 80% by volume is more preferable, and 39% to 75% by volume is still more preferable.

  In the present invention, the specific surface area of the inorganic filler refers to the BET specific surface area measured from the nitrogen adsorption capacity according to JIS Z8830-2013.

In the present invention, the method for measuring the ratio (volume%) of particles having a particle diameter in a specific range in the inorganic filler is as follows.
The particle size distribution of the inorganic filler can be measured by a laser diffraction method. When using the laser diffraction method, first, an inorganic filler is extracted from a resin sheet, a cured resin sheet, or the like, and a particle size distribution of the inorganic filler can be measured by using a laser diffraction scattering particle size distribution measuring device.

  The inorganic filler contained in the resin sheet, cured resin sheet, etc. is extracted using an organic solvent, nitric acid, aqua regia, etc., and sufficiently dispersed with an ultrasonic disperser to prepare a dispersion. The particle size distribution can be measured using the liquid. And the volume content rate of the particle group which belongs to each peak in the total volume of an inorganic filler is computable by calculating the volume of the particle group which belongs to each peak in the particle diameter distribution of an inorganic filler.

  Moreover, the particle diameter distribution of an inorganic filler can be measured by observing the cross section of a resin sheet or its hardened | cured material with a scanning electron microscope. Specifically, these resin sheets or their cured products are embedded in a transparent epoxy resin and polished with a polisher and slurry, ion milling, FIB (focused ion beam), etc., and the cross section of the resin sheet or its cured product is exposed. Let By observing this cross section with a scanning electron microscope, the particle size distribution of the inorganic filler can be actually measured. Further, using a FIB apparatus (focused ion beam SEM) or the like, polishing and two-dimensional cross-sectional observation can be repeated, and a three-dimensional structural analysis can be performed to measure the particle size distribution of the inorganic filler. Furthermore, by calculating the volume of the particle group belonging to each peak in the particle size distribution of the inorganic filler, the volume content of the particle group belonging to each peak in the total volume of the inorganic filler can be calculated.

  In the present invention, the ratio of the particles having a particle diameter of 25 μm to 100 μm in the inorganic filler is specified for the purpose of improving the thermal conductivity, suppressing the increase in the elastic modulus, and improving the elongation of the resin. This is because the proportion of particles having a particle diameter of 25 μm to 100 μm in the filler has a great influence. By setting the ratio of particles having a particle diameter of 25 μm to 100 μm in the inorganic filler within a specific range, both excellent thermal conductivity and shear strength can be achieved.

In the present invention, the specific surface area of the inorganic filler when two or more inorganic fillers are used in combination refers to the specific surface area of a mixture of two or more inorganic fillers.
In the present invention, when two or more inorganic fillers are used in combination, the proportion of particles having a particle diameter of 25 to 100 μm in the inorganic filler is 25 μm to the total volume of the mixture of two or more inorganic fillers. This refers to the volume ratio of particles having a particle diameter of 100 μm.

  In the resin sheet of the present invention, the average particle diameter obtained from the specific surface area of the inorganic filler is preferably 0.4 μm to 2.7 μm, more preferably 0.6 μm to 2.5 μm, and 0.8 μm. More preferably, it is -2.3 micrometers.

As a method for calculating the particle diameter R from the specific surface area S _m, there is a method using the density ρ of the inorganic filler assuming that the inorganic filler is spherical. V is the volume of the inorganic filler, S is the surface area of the inorganic filler, S _m is the specific surface area of the inorganic filler, and the particle diameter R is calculated from the specific surface area S _m using the following equation.

  Actually, since the surface of the inorganic filler has irregularities, R deviated from the spherical shape becomes slightly smaller than the value obtained by the laser diffraction method or actual measurement. By using this evaluation method, the primary particle diameter constituting the inorganic filler can be evaluated. When the primary particle size is small, the fluidity is deteriorated. On the other hand, if the primary particle size is large, even if the amount of inorganic filler added is increased, the moldability does not deteriorate, but anisotropy of the entire inorganic filler may occur. However, since the average particle diameter calculated | required from the specific surface area of the inorganic filler used in the resin sheet of this invention shall be 0.4 micrometer-2.7 micrometers, the problem by the above primary particle diameters does not arise easily.

  In addition, the inorganic filler contained in the resin sheet, cured resin sheet, etc. is extracted using an organic solvent, nitric acid, aqua regia, etc., and sufficiently dispersed with an ultrasonic disperser to prepare a dispersion. The average particle size can be measured by measuring the particle size distribution of the liquid using a laser diffraction method. Alternatively, the resin may be removed by heating, a dispersion may be prepared from the extracted inorganic filler by the above method, and the average particle size may be measured. The volume average particle diameter of the inorganic filler measured using a laser diffraction method is preferably 10 μm to 100 μm, more preferably 15 μm to 80 μm, and still more preferably 20 μm to 80 μm.

  As described above, boron nitride is more preferable as the inorganic filler used in the present invention. Boron nitride has a Mohs hardness of 2, which is lower and softer than other insulating ceramics such as aluminum oxide (alumina) and aluminum nitride (for example, Mohs hardness 8). Further, the boron nitride having a particle shape such as a spherical shape or a round shape has a shape in which the primary particles are aggregated, and there are cavities inside the aggregated particles, which are harder than the molten resin, but the aggregated particles themselves are easily deformed. It has become.

  For this reason, the boron nitride particles in the resin sheet can be deformed during the heating and pressurizing step, laminating step, or pressing step using the resin sheet of the present invention, and exist between the inorganic fillers during the deformation. By removing the resin to be removed, the inorganic fillers can easily approach each other. For example, when an inorganic filler containing boron nitride particles having a particle size of 25 μm to 100 μm and an inorganic filler other than boron nitride coexist, boron nitride particles can be filled while deforming between other hard inorganic filler particles. . Thereby, it becomes easy to form a structure (also referred to as “thermal conduction path”) in which the inorganic filler is continuously in contact with the thickness direction of the resin sheet and the cured resin sheet, and it can be considered that the thermal conductivity is improved. .

  Aluminum nitride particles are known as inorganic fillers having higher thermal conductivity than boron nitride particles. However, since the particles are hard and difficult to deform, a heat conduction path hardly occurs. Therefore, it is considered that the aluminum nitride particles are less effective in improving the thermal conductivity than the boron nitride particles.

  The resin sheet of the present invention may further contain inorganic particles having a volume average particle diameter of 1 μm or less as an inorganic filler. By doing so, the fluidity | liquidity of a resin sheet is suppressed, and when using the resin sheet of this invention as an adhesive agent, it exists in the tendency which can suppress the seepage of resin. As the inorganic particles having a volume average particle diameter of 1 μm or less, alumina, aluminum hydroxide, boron nitride, silicon oxide and the like are preferable, and alumina or aluminum hydroxide is more preferable.

  In the present invention, the inorganic filler may have a single peak or a plurality of peaks in the particle size distribution.

  The particle shape of the inorganic filler is not particularly limited, and examples thereof include a spherical shape, a round shape, a crushed shape, a flake shape, and an aggregated particle shape. The particle shape of the inorganic filler is preferably rounded, spherical, or agglomerated from the viewpoints of fillability and thermal conductivity.

When boron nitride is contained as the inorganic filler, the content of boron nitride contained in the inorganic filler is 10% by volume to 100% by volume when the total volume of the inorganic filler is 100% by volume from the viewpoint of thermal conductivity. It is preferable that it is 15 volume%-97 volume%, and it is still more preferable that it is 20 volume%-95 volume% from an adhesive viewpoint.
Further, the content of the inorganic compound particles contained in the inorganic filler is preferably 90% by volume to 100% by volume when the total volume of the inorganic filler is 100% by volume from the viewpoint of thermal conductivity. In view of the above, it is more preferably 95% by volume to 100% by volume.
The content of the inorganic filler contained in the resin sheet of the present invention is preferably 40% by volume to 85% by volume, more preferably 42% by volume to 82% by volume, and 44% by volume with respect to the total solid content volume of the resin sheet. -79 volume% is still more preferable.
When the content of the inorganic filler is 40% by volume to 80% by volume, viscosity is imparted to the resin and the resin tends to be prevented from flowing out during bonding. Moreover, if the content rate of an inorganic filler is 80 volume% or less, the deterioration of the fluidity | liquidity of resin will be suppressed and it exists in the tendency for fixability to improve. If the content rate of an inorganic filler is 40 volume% or more, it will suppress that the fluidity | liquidity of resin becomes high too much, and there exists a tendency for generation | occurrence | production of a void to be suppressed.
In addition, the total solid content volume of a resin sheet means the total volume of a non-volatile component among the components which comprise a resin sheet.

(resin)
The resin sheet of the present invention contains at least one kind of resin. As the resin, a general resin usually used for an adhesive can be used without particular limitation. In particular, it is preferable that it has a low viscosity before curing, is excellent in filler filling property and moldability, and has high heat conductivity in addition to high heat resistance and adhesiveness after thermosetting.
Specific examples of the resin used in the present invention include, for example, epoxy resins, phenoxy resins, acrylic resins, polyimide resins, polyamide resins, polycarbonate resins, bismaleimide resins, and polyimide resins.

  In the resin sheet of this invention, you may use the epoxy resin which can suppress the phonon scattering which is a heat conductive medium, can form a higher order structure, and can achieve high thermal conductivity. This is because an epoxy resin forms a cured resin together with a novolak resin having a specific structural unit, thereby forming a highly ordered higher order structure derived from a covalent bond or intermolecular force in the cured resin. This is because it can.

  When the resin sheet of the present invention contains an epoxy resin, as the epoxy resin, a trifunctional or higher functional first epoxy having a structure in which two naphthalene rings are included in the molecule and the two naphthalene rings are connected by an alkylene chain A resin may be contained. Moreover, when the resin sheet of this invention contains the said 1st epoxy resin, you may use together the bifunctional 2nd epoxy resin which has a mesogen structure in a molecule | numerator as an epoxy resin. When the resin sheet of this invention contains an epoxy resin, you may contain other epoxy resins other than a 1st epoxy resin and a 2nd epoxy resin as an epoxy resin as needed.

  The first epoxy resin according to the present invention is preferably a compound represented by the following general formula (I).

In the general formula (I), R ¹ represents an alkylene group having 1 to 7 carbon atoms. R ¹ is preferably an alkylene group having 1 to 5 carbon atoms, more preferably an alkylene group having 1 to 3 carbon atoms, and still more preferably a methylene group. The alkylene group represented by R ¹ may further have a substituent, if necessary. Examples of the substituent include an alkyl group, an aryl group, a halogen atom, and a hydroxyl group.
The position to which R ¹ is bonded in the naphthalene ring is not particularly limited, and may be the 1-position or the 2-position, and the 1-position is preferred. The position to which R ¹ is bonded may be the same position or a different position in each naphthalene ring.

  The compound represented by the general formula (I) is more preferably a compound represented by the following general formula (IA).

The second epoxy resin according to the present invention is not particularly limited as long as it is a bifunctional one having a mesogenic structure in the molecule.
It is known that good thermal conductivity can be obtained after an epoxy resin having a mesogenic structure is cured at a specific temperature. In the present invention, by using an epoxy resin having a mesogenic structure, when the epoxy resin reacts with a curing agent at a specific temperature to form a cured resin, regularity derived from the mesogenic structure in the cured resin is obtained. A higher order structure can be formed. The higher order structure means a state in which molecules are arranged in a mesogenic structure after the resin sheet is cured.

  The second epoxy resin according to the present invention is preferably at least one selected from the group consisting of a compound represented by the following general formula (II) and a compound represented by the following general formula (III).

In the general formula (III), each R ² independently represents an alkyl group, an alkoxy group, an aryl group, or an aralkyl group. Each m independently represents an integer of 0 to 2. R ² is preferably an alkyl group or an alkoxy group, and more preferably an alkyl group.
Examples of the alkyl group represented by R ² include a methyl group, an ethyl group, and a butyl group.
Examples of the alkoxy group represented by R ² include a methoxy group, an ethoxy group, and a butoxy group.
Examples of the aryl group represented by R ² include a phenyl group.
The aralkyl group represented by R ^2, include a benzyl group.
The alkyl group, alkoxy group, aryl group and aralkyl group represented by R ² may further have a substituent as necessary. Examples of the substituent include an alkyl group, an aryl group, a halogen atom, and a hydroxyl group.
R ² is preferably a methyl group or an ethyl group.

The mesogenic group referred to in the present invention refers to a group that can form a higher order structure in a cured resin when the epoxy resin reacts with a curing agent to form a cured resin.
In addition, the higher order structure as used in the field of this invention means the state by which the molecule | numerator is orientated after hardening of a resin sheet, for example, means that a crystal structure exists in cured resin. The presence of such a crystal structure can be directly confirmed by, for example, observation with a polarizing microscope under crossed Nicols or an X-ray scattering spectrum. The presence of the crystal structure can also be indirectly confirmed by a small change in the storage elastic modulus with respect to the temperature change.

  Specific examples of the epoxy resin monomer having a mesogenic group include 4,4′-biphenol glycidyl ether, 3,3 ′, 5,5′-tetramethyl-4,4′-biphenol glycidyl ether, 1- {(3-Methyl-4-oxiranylmethoxy) phenyl} -4- (4-oxiranylmethoxyphenyl) -1-cyclohexene, 4- (oxiranylmethoxy) benzoic acid-1,8-octanediylbis Mention may be made of (oxy-1,4-phenylene) ester and 2,6-bis [4- [4- [2- (oxiranylmethoxy) ethoxy] phenyl] phenoxy] pyridine. Among these, 4,4′-biphenol glycidyl ether or 3,3 ′, 5,5′-tetramethyl-4,4′-biphenol glycidyl ether is preferable from the viewpoint of improving thermal conductivity.

  The other epoxy resin preferably has a low viscosity before curing, is excellent in filler filling property and moldability, and has high heat conductivity in addition to high heat resistance and adhesiveness after thermosetting. For example, the other epoxy resin is preferably liquid at 25 ° C. (hereinafter sometimes referred to as “liquid epoxy resin”). Thereby, the softness | flexibility of the resin sheet of this invention or the fluidity | liquidity at the time of lamination | stacking becomes easy to express. Moreover, it becomes possible by using a liquid epoxy resin to reduce the resin softening point in the A-stage state and B-stage state of the resin sheet. Specifically, the use of a liquid epoxy resin may improve the flexibility of the resin sheet and excel in handleability, and may lower the melt viscosity during bonding. Since the liquid epoxy resin may have a low glass transition temperature and thermal conductivity after curing, the content of the liquid epoxy resin can be appropriately selected in view of the physical properties of the cured resin.

  Examples of such epoxy resins that are liquid at 25 ° C. include bisphenol A type epoxy resins, bisphenol F type epoxy resins, bisphenol AD type epoxy resins, hydrogenated bisphenol A type epoxy resins, and hydrogenated bisphenol AD type epoxy resins. And an epoxy resin having only one epoxy group called a naphthalene type epoxy resin and a reactive diluent. The epoxy resin that is liquid at 25 ° C. is from the group consisting of bisphenol A-type epoxy resin, bisphenol F-type epoxy resin, bisphenol AD-type epoxy resin, and naphthalene-type epoxy resin, from the viewpoint of the change in elastic modulus with respect to the temperature after curing and the thermal properties. It is preferable that it is at least one selected.

  The number average molecular weight of the epoxy resin that is liquid at 25 ° C. is not particularly limited. For example, from the viewpoint of fluidity during lamination, the number average molecular weight is preferably 100 or more and 100,000 or less, and 200 or more and 50,000 or less. More preferably, it is 300 or more and 10,000 or less. The number average molecular weight is a value measured by gel permeation chromatography (GPC). The conditions for GPC measurement will be described later in Examples.

  In particular, when at least one liquid epoxy resin selected from the group consisting of a bisphenol A type epoxy resin and a bisphenol F type epoxy resin having a molecular weight of 500 or less is included, the flexibility of the resin sheet of the present invention or the fluidity at the time of lamination is further improved. Can be improved.

There is no restriction | limiting in particular in the content rate of resin contained in the resin sheet of this invention. From the viewpoints of thermal conductivity and adhesiveness, the resin content is preferably 3% by mass to 30% by mass in the total solid mass constituting the resin sheet, and from the viewpoint of thermal conductivity, 5% by mass to It is more preferably 25% by mass, and further preferably 5% by mass to 20% by mass.
There is no restriction | limiting in particular in the content rate of the epoxy resin contained in the resin sheet in case the resin sheet of this invention contains an epoxy resin especially as resin. From the viewpoint of thermal conductivity and adhesiveness, the content of the epoxy resin is preferably 3% by mass to 30% by mass in the total solid mass constituting the resin sheet, and 5% by mass from the viewpoint of thermal conductivity. % To 25% by mass is more preferable, and 5% to 20% by mass is even more preferable.

  In the resin sheet of the present invention, when the first epoxy resin and the second epoxy resin are used together as the resin, the content ratio (mass basis) of the first epoxy resin and the second epoxy resin is 25: It is preferably 75 to 85:15, more preferably 30:70 to 80:20, and still more preferably 35:65 to 75:25.

The first epoxy resin and the second epoxy resin when the compound represented by the general formula (I) is used as the first epoxy resin and the compound represented by the general formula (II) is used as the second epoxy resin. The content ratio (by mass) of the epoxy resin is preferably 25:75 to 85:15, more preferably 30:70 to 80:20, and 35:65 to 75:25. Is more preferable.
In addition, when the compound represented by the general formula (I) is used as the first epoxy resin and the compound represented by the general formula (III) is used as the second epoxy resin, the second epoxy resin and the second epoxy resin are used. The content ratio of the epoxy resin to the epoxy resin (mass basis) is preferably 25:75 to 85:15, more preferably 35:65 to 75:25, and 40:60 to 65:35. Is more preferable.

.
(Curing agent)
When the resin contained in the resin sheet of the present invention contains an epoxy resin, the resin sheet of the present invention may contain a curing agent.
The curing agent that can be used in the present invention is not particularly limited as long as it is a compound capable of curing reaction with an epoxy resin. Specific examples of the curing agent in the present invention include novolak resins, aromatic amine curing agents, aliphatic amine curing agents, mercaptan curing agents, polyaddition curing agents such as acid anhydride curing agents, and the like.
Among these, novolak resins are preferable, and novolak resins containing a structural unit represented by the following general formula (IV) (hereinafter sometimes referred to as specific novolak resins) are more preferable.
The specific novolac resin acts as a curing agent, reacts with the above-described epoxy resin to form a cured resin, and exhibits insulation, adhesiveness, and thermal conductivity. By including the above-mentioned specific epoxy resin and specific novolak resin, it is possible to exhibit more excellent flexibility before curing, and to exhibit better thermal conductivity and high-temperature adhesiveness after curing.

In general formula (IV), R < ³ > represents an alkyl group, an aryl group, or an aralkyl group each independently. R ⁴ and R ⁵ each independently represents a hydrogen atom, an alkyl group, an aryl group or an aralkyl group. m represents an integer of 0-2.

m represents an integer of 0 to 2, and when m is 2, two R ³ may be the same or different. m is preferably 0 or 1 and more preferably 0 from the viewpoints of adhesiveness and thermal conductivity.

  The specific novolak resin only needs to include at least one compound having the structural unit represented by the general formula (IV), and two or more compounds having the structural unit represented by the general formula (IV). May be included.

  Since the specific novolac resin includes a compound having a structural unit represented by the general formula (IV), it includes at least a partial structure derived from resorcinol as a phenol compound. The specific novolac resin may further include at least one partial structure derived from a phenol compound other than resorcinol. Examples of phenol compounds other than resorcinol include phenol, cresol, catechol, hydroquinone, 1,2,3-trihydroxybenzene, 1,2,4-trihydroxybenzene, 1,3,5-trihydroxybenzene, and the like. it can. The specific novolak resin may contain a partial structure derived from these alone or in combination of two or more. Here, the partial structure derived from a phenol compound means a monovalent or divalent group constituted by removing one or two hydrogen atoms from the benzene ring portion of the phenol compound. The position where the hydrogen atom is removed is not particularly limited.

  As a partial structure derived from a phenol compound other than resorcinol in the specific novolak resin, from the viewpoint of thermal conductivity, adhesiveness and storage stability, phenol, cresol, catechol, hydroquinone, 1,2,3-trihydroxybenzene, 1 , 2,4-trihydroxybenzene, and a partial structure derived from at least one selected from the group consisting of 1,3,5-trihydroxybenzene, hydroquinone, 1,2,4-trihydroxybenzene, And a partial structure derived from at least one selected from the group consisting of 1,3,5-trihydroxybenzene.

  There is no restriction | limiting in particular about the content rate of the partial structure derived from resorcinol in specific novolak resin. From the viewpoint of thermal conductivity, the content of the partial structure derived from resorcinol is preferably 20% by mass or more in the total mass of the specific novolak resin, and from the viewpoint of further high thermal conductivity, 50% by mass or more. It is more preferable that The upper limit of the content of the partial structure derived from resorcinol in the total mass of the specific novolak resin is not particularly limited, and is preferably 95% by mass or less, for example.

In general formula (IV), R ⁴ and R ⁵ 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 ⁴ and R ⁵ may further have a substituent, if necessary. Examples of the substituent include an alkyl group, an aryl group, a halogen atom, and a hydroxyl group.

R ⁴ and R ⁵ are preferably a hydrogen atom, an alkyl group, or an aryl group from the viewpoint of storage stability and thermal conductivity, and are preferably a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or a carbon number 6 Is more preferably a hydrogen atom or a phenyl group, and particularly preferably a hydrogen atom. Furthermore, from the viewpoint of heat resistance, it is also preferable that at least one of R ⁴ and R ⁵ is an aryl group having 6 to 10 carbon atoms (more preferably, a phenyl group).

  Specifically, the specific novolac resin is preferably a novolac resin containing a compound having a structural unit represented by any one of the following general formulas (IVa) to (IVf).

  In general formula (IVa)-general formula (IVf), i and j represent the content rate (mass%) of the structural unit derived from each phenol compound. i is 2 mass% or more and 30 mass% or less, j is 70 mass% or more and 98 mass% or less, and the sum total of i and j is 100 mass%.

  The specific novolac resin includes a structural unit represented by at least one selected from the group consisting of general formula (IVa) and general formula (IVf) from the viewpoint of thermal conductivity, and i is 2% by mass to 20% by mass. It is preferable that j is 80% by mass to 98% by mass, and includes a structural unit represented by the general formula (IVa) from the viewpoint of elastic modulus and linear expansion coefficient, and i is 5% by mass to More preferably, it is 10% by mass and j is 90% by mass to 95% by mass.

  The specific novolac resin includes a compound having a structural unit represented by the general formula (IV), and preferably includes at least one compound represented by the following general formula (V).

In general formula (V), R ⁶ represents a hydrogen atom or a monovalent group derived from a phenol compound represented by the following general formula (Vp), and R ⁷ represents a monovalent group derived from a phenol compound. . ^Also, R ^3, R 4, ^{R 5} and m are respectively the same as ^{R 3,} R 4, ^{R 5} and m in the general formula (IV). The monovalent group derived from the phenol compound represented by R ⁷ is a monovalent group formed by removing one hydrogen atom from the benzene ring portion of the phenol compound, and the position at which the hydrogen atom is removed is particularly limited. Not.
n is a number of 1 to 7, and is the number of repeating structural units represented by the general formula (IV). When the specific novolac resin is a single compound, n is an integer. When the specific novolac resin is composed of a plurality of molecular species, n is an average value of the number of structural units represented by the general formula (IV) and is a rational number. When the specific novolac resin includes a plurality of types of compounds having the structural unit represented by the general formula (IV), n has an average value of 1.7 to 6.5 from the viewpoints of adhesiveness and thermal conductivity. It is preferable that it is 2.4 to 6.1.

In general formula (Vp), p represents the number of 1-3. ^Also, R ^3, R 4, ^{R 5} and m are respectively the same as ^{R 3,} R 4, ^{R 5} and m in the general formula (IV).

The phenol compound in R ⁶ and R ⁷ is not particularly limited as long as it is a compound having a phenolic hydroxyl group. Specific examples of the phenol compound include phenol, cresol, catechol, resorcinol, and hydroquinone. Among these, from the viewpoint of thermal conductivity and storage stability, at least one selected from the group consisting of cresol, catechol, and resorcinol is preferable.

The number average molecular weight of the specific novolak resin is preferably 800 or less from the viewpoint of thermal conductivity and moldability, more preferably from 300 to 750 from the viewpoint of elastic modulus and linear expansion coefficient, and further From the viewpoint of moldability and adhesive strength, it is more preferably 350 or more and 550 or less.
The number average molecular weight of the specific novolac resin is a value measured by gel permeation chromatography (GPC). The conditions for GPC measurement will be described later in Examples.

Moreover, it is preferable that specific novolak resin further contains the monomer which is a phenol compound which comprises a novolak resin from a softness | flexibility viewpoint. In general, a novolac resin is synthesized by condensation polymerization of a phenol compound and an aldehyde compound. Therefore, the phenol compound constituting the novolak resin means a phenol compound used for the synthesis of the novolak resin. The phenolic compound contained in the specific novolak resin may be a phenolic compound remaining during the synthesis of the novolac resin or a phenolic compound added after the synthesis of the novolac resin.
As a content rate of the phenol compound contained in specific novolak resin, 5 mass%-60 mass% are preferable, 10 mass%-55 mass% are more preferable, 15 mass%-50 mass% are still more preferable.

  The phenol compound contained as a monomer in the specific novolak resin is selected according to the structure of the specific novolak resin. Among them, the phenol compound is at least one selected from the group consisting of resorcinol, catechol, 1,2,4-trihydroxybenzene, 1,3,5-trihydroxybenzene and 1,2,3-trihydroxybenzene. And at least one selected from the group consisting of resorcinol and catechol is more preferable.

  When the resin sheet of the present invention contains a curing agent, the total content of the curing agent in the resin sheet is not particularly limited. From the viewpoint of thermal conductivity and adhesiveness, the total content of the curing agent is preferably 1% by mass to 10% by mass, and 1.2% by mass to 8% by mass in the total solid content of the resin sheet. It is more preferable that it is 1.4 mass%-7 mass%.

  When the resin sheet of the present invention contains a specific novolak resin as a curing agent, the content of the specific novolak resin in the resin sheet is not particularly limited. The content of the specific novolac resin is preferably 0.3% by mass to 10% by mass in the total solid content mass of the resin composition from the viewpoint of thermal conductivity and adhesiveness, and from the viewpoint of thermal conductivity, More preferably, it is 0.5 mass%-8 mass%, and it is still more preferable that it is 0.7 mass%-7 mass%.

  From the viewpoint of insulation and heat resistance, the resin sheet of the present invention preferably contains at least one kind of other novolac resin not containing the structural unit represented by the general formula (IV) in addition to the specific novolac resin. The other novolak resin is not particularly limited as long as it is a novolak resin that does not contain the structural unit represented by the general formula (IV), and can be appropriately selected from novolak resins that are usually used as curing agents for epoxy resins. .

  When the resin sheet of the present invention further contains other curing agent other than the specific novolak resin, the content of the other curing agent is not particularly limited. From the viewpoint of thermal conductivity, it is preferably 30% by mass or less, more preferably 20% by mass or less, and still more preferably 10% by mass or less with respect to the specific novolac resin.

  Moreover, when the resin sheet of this invention contains a hardening | curing agent and contains an epoxy resin as resin, content of the hardening | curing agent in a resin sheet is 0.8-1.2 on an equivalent basis with respect to an epoxy resin. Is preferable, and it is more preferable that it is 0.9-1.1. Here, the equivalent is the reaction equivalent. For example, the equivalent of novolak resin is calculated as one phenolic hydroxyl group reacts with one epoxy group, and the equivalent of amine is amino with respect to one epoxy group. One active hydrogen of the group is calculated to react, and the acid anhydride equivalent of the acid anhydride is calculated as one acid anhydride group reacts to one epoxy group.

(Other ingredients)
The resin sheet of the present invention can contain other components as needed in addition to the above components. Examples of other components include a curing accelerator and a dispersant.
Examples of the curing accelerator include imidazole, triphenylphosphine, derivatives obtained by introducing side chains into these compounds, and the like.
Examples of the dispersant include, but are not limited to, polymers, silicon, and those obtained by chemically modifying these compounds.

  The average thickness of the resin sheet of the present invention is preferably 40 μm to 250 μm, more preferably 50 μm to 240 μm, and still more preferably 60 μm to 230 μm, from the viewpoint of achieving both thermal conductivity and insulation. 70 μm to 220 μm is particularly preferable. The average thickness of the resin sheet can be selected as appropriate in consideration of the electrical characteristics such as the voltage value to be insulated and the current value, and the thermal resistance value between the heating element and the resin sheet. If the required thermal resistance value can be satisfied, the average thickness of the resin sheet is preferably thick from the viewpoint of insulation. The average thickness of the resin sheet is given as an arithmetic average value obtained by measuring the thickness of nine points using a micrometer (for example, Mitutoyo Corporation, Micrometer IP65).

  The resin sheet of the present invention preferably has a support on at least one surface, and more preferably has a support on both surfaces. As a result, it is possible to prevent foreign matter from adhering to the adhesive surface of the resin sheet from the external environment and to protect the resin sheet from impact. That is, the support functions as a protective film. The support is preferably peeled off when used.

  Examples of the support include a plastic film such as a polytetrafluoroethylene film, a polyethylene terephthalate (PET) film, a polyethylene film, a polypropylene film, a polymethylpentene film, and a polyimide film. These plastic films may be subjected to surface treatment such as primer coating, UV treatment, corona discharge treatment, polishing treatment, etching treatment, mold release treatment and the like as necessary. Further, as the support, a metal foil such as a copper foil or an aluminum foil, a metal plate such as an aluminum plate, or the like can be used.

  When the support is a plastic film, the average thickness is not particularly limited. The average thickness is appropriately determined based on the knowledge of those skilled in the art depending on the average thickness of the resin sheet to be formed and the application of the resin sheet. The average thickness of the plastic film is preferably 10 μm to 150 μm, and more preferably 25 μm to 110 μm, in terms of good economic efficiency and good handleability.

  Moreover, when the said support body is metal foil, the average thickness in particular is not restrict | limited, According to the use etc. of a resin sheet, it can select suitably. For example, the average thickness of the metal foil can be 10 μm to 400 μm, and preferably 18 μm to 300 μm from the viewpoint of handleability as a roll foil.

  The resin sheet of the present invention includes a first resin layer containing a resin, an inorganic filler, and other components such as a curing agent used as necessary, and a resin and an inorganic filler laminated on the first resin layer. It is preferable to include a second resin layer containing other components such as a curing agent used as necessary. For example, the resin sheet of the present invention is preferably a laminate of a first resin layer and a second resin layer. Thereby, the withstand voltage can be further improved. The component constituting the first resin layer and the component constituting the second resin layer may have the same composition or different compositions. It is preferable that the component which comprises a 1st resin layer and the component which comprises a 2nd resin layer are the same compositions from a heat conductive viewpoint.

The resin sheet of the present invention may have a metal foil on one surface and a plastic film on a surface opposite to the surface having the metal foil.
The resin sheet of the present invention includes a first resin layer containing a resin, an inorganic filler, and other components such as a curing agent used as necessary, and a resin and an inorganic layer laminated on the first resin layer. It is a laminate having a filler and a second resin layer containing other components such as a curing agent used as necessary, further having a metal foil on one surface of the laminate, and the other surface It is preferable to further have a protective film such as a plastic film on the top. That is, the resin sheet may further have a protective film such as a metal foil and a plastic film, and is provided in the order of a protective film such as a metal foil, a first resin layer, a second resin layer, and a plastic film. Is preferred. As a result, a void filling effect is obtained, and the withstand voltage tends to be further improved.

(Production method of resin sheet)
The method for producing the resin sheet is not particularly limited as long as it is a method capable of forming a sheet-like resin layer having an average thickness of 40 μm to 250 μm, using the resin composition containing the components constituting the resin sheet of the present invention. It can select suitably from the manufacturing method of the sheet | seat normally used. Specifically, as a method for producing a resin sheet, a resin composition containing an organic solvent together with the components constituting the resin sheet of the present invention is applied on a support so as to have a desired average thickness. And forming the resin layer by removing at least a part of the organic solvent by drying the formed resin composition layer.

  There is no restriction | limiting in particular about the provision method of a resin composition, and the drying method, It can select suitably from the method used normally. Examples of the application method include a comma coater method, a die coater method, and a dip coating method. Examples of the drying method include heat drying under normal pressure or reduced pressure, natural drying, freeze drying, and the like.

  The thickness of the resin composition layer can be appropriately selected so that the resin layer after the drying treatment has a desired average thickness. The average thickness of the resin layer after drying is preferably 40 μm to 250 μm, and the thickness of the resin composition layer is preferably adjusted to be 50 μm to 250 μm. When the average thickness of the resin layer after drying is 40 μm or more, cavities are hardly formed in the resin layer, and the production likelihood tends to increase. Moreover, even when forming the resin roll as the average thickness of the resin layer after drying is 250 micrometers or less, it exists in the tendency which can suppress scattering of the resin powder.

  When the resin sheet of this invention is a laminated body, it is preferable to manufacture by superimposing the 1st resin layer and the 2nd resin layer. With such a configuration, the withstand voltage is further improved.

  This can be considered as follows, for example. That is, by overlapping two resin layers, a thinned portion (pinhole or void) that may exist in one resin layer is compensated by the other resin layer. Thereby, it can be considered that the minimum insulation thickness can be increased and the withstand voltage is further improved. The probability of occurrence of pinholes or voids in the resin sheet manufacturing method is not high, but by overlapping two resin layers, the probability of overlap of thin parts becomes the square, and the number of pinholes or voids approaches zero. become. Since dielectric breakdown occurs at a place where the insulation is weakest, it can be considered that the effect of further improving the withstand voltage can be obtained by overlapping two resin layers. Furthermore, it can be considered that by overlapping the two resin layers, the contact probability between the inorganic fillers is improved, and the effect of improving the thermal conductivity is also produced.

  The resin sheet manufacturing method includes a resin, an inorganic filler, and a curing agent used as necessary on the first resin layer containing other components such as a curing agent used as needed. It is preferable to include a step of obtaining a laminate by superimposing the second resin layer containing the other components, and a step of subjecting the obtained laminate to a heat and pressure treatment. With such a manufacturing method, the withstand voltage is further improved.

  Moreover, it is preferable that the resin sheet of this invention further has metal foil on one surface of the said laminated body, and further has protective films, such as a plastic film, on the other surface. A method for producing a resin sheet having such a structure includes a first resin layer provided on a metal foil, containing a resin, an inorganic filler, and other components such as a curing agent used as necessary, a plastic film, and the like. It is preferable to have a step of stacking the resin, the inorganic filler, and the second resin layer containing other components such as a curing agent used as necessary so as to contact each other. Thereby, the hole filling effect can be obtained more effectively.

  The first resin layer is formed, for example, by forming a resin composition layer on a metal foil by applying a resin composition containing an organic solvent together with the components constituting the resin sheet of the present invention. Can be formed by drying to remove at least a portion of the organic solvent. The second resin layer is formed, for example, by forming a resin composition layer on a plastic film by applying a resin composition containing an organic solvent together with components constituting the resin sheet of the present invention. It can be formed by drying the material layer to remove at least part of the organic solvent.

  It is preferable that the average thicknesses of the first resin layer and the second resin layer are appropriately selected so that the average thickness of the laminate is 40 μm to 250 μm when the laminate is configured. The average thicknesses of the first resin layer and the second resin layer can be, for example, 10 μm to 240 μm, respectively, and preferably 20 μm to 230 μm. When the average thickness is 10 μm or more, voids are hardly formed in the resin layer, and the production likelihood tends to increase. When the average thickness is 240 μm or less, there is a tendency that cracks are not easily formed in the sheet. The average thicknesses of the first resin layer and the second resin layer may be the same or different from each other.

  Furthermore, it is preferable that the laminate in which the first resin layer and the second resin layer are stacked is subjected to a heat and pressure treatment. Thereby, a resin sheet with improved thermal conductivity can be produced. The method for heat and pressure treatment is not particularly limited as long as it can apply a predetermined pressure and heat, and can be appropriately selected from commonly used heat and pressure treatment methods. Specific examples include laminating, pressing, and metal roll processing. In addition, the heat and pressure treatment includes a method of performing treatment at normal pressure and a vacuum treatment of performing treatment under reduced pressure. Vacuum treatment is preferred, but not limited.

  When the resin layer is formed from the resin composition containing the component constituting the resin sheet of the present invention, the surface of the laminate before the heat and pressure treatment is uneven due to an inorganic filler or the like, and may not be smooth. The thickness of the resin sheet of the present invention obtained by subjecting such a laminate to heat and pressure treatment may be small without matching the sum of the thicknesses of the resin layers. This is considered to be because, for example, the filler filling property changes before and after the heat and pressure treatment, the convexity and the concaveness of the surface are superimposed, the uniformity of the sheet is improved, and the void is filled. be able to.

(Production method of resin composition)
As a method for producing a resin composition containing the components constituting the resin sheet of the present invention, a usual method for producing a resin composition can be used without particular limitation. As a method of mixing the resin, the inorganic filler, and other components such as a curing agent used as necessary, an ordinary agitator, a raking machine, a three-roller, a ball mill or the like is appropriately combined. Can do. Further, dispersion or dissolution can be performed by adding an appropriate organic solvent.

  Specifically, for example, a resin, an inorganic filler, and other components such as a curing agent used as necessary are dissolved or dispersed in an appropriate organic solvent, and other components such as a curing accelerator are added as necessary. By mixing, a resin composition can be obtained.

  The organic solvent is preferably a solvent having a low boiling point or a high vapor pressure because at least a part of the organic solvent is removed by a drying process in the drying step in the method for producing a resin sheet. If a large amount of the organic solvent remains in the resin sheet, it may affect the thermal conductivity or the insulation performance. On the other hand, if the organic solvent is removed, the sheet may become too hard and the adhesion performance may be lost. Therefore, the selection of the organic solvent needs to be compatible with the drying method and drying conditions. The organic solvent can be appropriately selected depending on the type of resin to be used, the type of inorganic filler, the ease of drying during sheet preparation, and the like. Examples of organic solvents include alcohol solvents such as methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, and cyclohexanol, ketone solvents such as methyl ethyl ketone, cyclohexanone, and cyclopentanone, dimethylformamide, dimethylacetamide, and the like. And nitrogen-containing solvents. Further, the organic solvents can be used alone or in combination of two or more.

The resin sheet of the present invention has a melt viscosity at 100 ° C. of 1.0 × 10 ⁵ Pa · s to 1.0 × 10 ⁸ Pa · s. The melt viscosity is a value measured by dynamic viscoelasticity measurement (frequency 1 Hz, load 40 g, temperature increase rate 3 ° C./min). Melt viscosity at 100 ° C. is preferably ^{1.5 × 10 5 Pa · s~8.0 ×} 10 7 Pa · s, 3.0 × 10 5 Pa · s~6.0 × 10 7 Pa · s Gayori preferable.
In this specification, a resin sheet obtained by drying a resin composition layer formed from a resin composition is an A stage sheet, and a resin sheet obtained by further heating and pressing the A stage sheet is a B stage. Sometimes referred to as a sheet. For the A stage, the B stage, and the C stage, which will be described later, the specifications are referred to JIS K6900-1994.
The resin sheet of the present invention having a melt viscosity at 100 ° C. of 1.0 × 10 ⁵ Pa · s to 1.0 × 10 ⁸ Pa · s belongs to a so-called B stage sheet.

When the melt viscosity at 100 ° C. of the resin sheet of the present invention is 1.0 × 10 ⁵ Pa · s to 1.0 × 10 ⁸ Pa · s, the handleability of the resin sheet is improved. This is because the elastic modulus is increased and the strength is improved by the progress of curing as compared with the A stage sheet. On the other hand, the degree of cure of the resin sheet of the present invention is preferably suppressed to such an extent that the resin sheet can be handled flexibly. Moreover, as a method of making the resin layer semi-cured and setting the melt viscosity at 100 ° C. of the resin sheet to a range of 1.0 × 10 ⁵ Pa · s to 1.0 × 10 ⁸ Pa · s, for example, resin The method of heat-pressing a layer can be mentioned.

  The method for heat-pressing the resin layer is not particularly limited as long as the resin layer can be in a semi-cured state. For example, the resin layer can be heated and pressurized using a hot press and a laminator. Moreover, the heating and pressurizing conditions for setting the resin layer in a semi-cured state can be appropriately selected according to the structure of the resin composition. The minute conditions can be mentioned.

The resin sheet in the C stage state of the present invention preferably has a tensile modulus of 0.1 GPa to 30 GPa, a tensile fracture strain of 0.10% to 0.70%, and a tensile modulus of 1 GPa to 28 GPa. More preferably, the tensile fracture strain is 0.14% to 0.65%, the tensile modulus is 2 GPa to 26 GPa, and the tensile fracture strain is further 0.18% to 0.60%. preferable.
There exists an advantage which can improve the adhesive strength when adhere | attaching the to-be-adhered body from which a linear expansion coefficient differs by making the tensile elasticity modulus and tensile fracture strain of the resin sheet of the C-stage state of this invention into a predetermined range.
In addition, in order to make the tensile elastic modulus and tensile fracture strain of the resin sheet in the C-stage state of the present invention within a predetermined range, the types and contents of other components such as a resin, an inorganic filler, and a curing agent used as necessary This is achieved by appropriately selecting the rate. In the present invention, the composition of the inorganic filler often affects these physical property parameters. For example, when the content of the inorganic filler is increased, the tensile fracture strain decreases, but the fracture strength increases. On the other hand, when the content of the inorganic filler is lowered, the tensile fracture strain increases and the breaking strength decreases. Further, it can be adjusted by changing the kind of the inorganic filler, for example, it can be adjusted by changing the ratio of alumina and boron nitride. When alumina is increased, the tensile fracture strain decreases, but the fracture strength increases. On the other hand, when boron nitride is increased, the reverse occurs. These techniques may be used alone or in combination.

  In addition, a tensile elasticity modulus and a tensile fracture strain say the value measured according to JISK7161-1994.

<Hardened resin sheet>
The cured resin sheet of the present invention is a heat-treated product of the resin sheet of the present invention. That is, the cured resin sheet of the present invention is formed by curing the resin composition constituting the resin sheet by heat-treating the resin sheet of the present invention. Therefore, the cured resin sheet contains a cured product of a resin composition including a resin, an inorganic filler, and other components such as a curing agent used as necessary.

  The cured resin sheet of the present invention is at least selected from the group consisting of a compound represented by general formula (I), a compound represented by general formula (II), and a compound represented by general formula (III). It is preferable to contain a cured resin derived from one kind and a curing agent.

  In the cured resin sheet of the present invention, high thermal conductivity is exhibited when the inorganic fillers come into contact with each other. Since the thermal conductivity differs greatly between the resin and the inorganic filler, it is preferable that in the mixture of the resin and the inorganic filler, the inorganic fillers having high thermal conductivity are brought as close as possible to reduce the distance between the inorganic fillers. For example, when an inorganic filler having a higher thermal conductivity than a resin contacts without interposing the resin, a heat conduction path is formed, and a path that easily conducts heat can be formed.

  The heat treatment conditions for producing the cured resin sheet can be appropriately selected according to the configuration of the resin sheet of the present invention. For example, the resin sheet of the present invention can be heat-treated under conditions of 120 ° C. to 250 ° C. and 1 minute to 300 minutes. In addition, when the resin contains an epoxy resin, from the viewpoint of glass transition temperature, thermal conductivity, and adhesiveness of the epoxy resin, the heat treatment conditions gradually increase the temperature in order to facilitate the formation of a three-dimensional crosslinked structure. It is preferable to include the process to make. For example, it is more preferable to perform at least two stages of heating at 100 ° C. to 160 ° C. and 160 ° C. to 250 ° C. with respect to the resin sheet of the present invention. More preferably, the treatment is performed. By reducing the number of unreacted parts between the epoxy resin and the curing agent, the effect of preventing the thermal decomposition of the unreacted parts and the overheating of the resin center due to the reaction heat, in addition to improving the characteristics due to the increase in the crosslink density. There is also.

It is known that high thermal conductivity can be achieved by using an epoxy resin having a mesogenic structure as an epoxy resin and reacting with a curing agent at a specific temperature to form a cured resin. For example, this can be considered as follows.
That is, by forming a cured resin using an epoxy resin having a mesogenic structure in the molecule and a specific novolac resin, a highly ordered higher order structure can be formed in the cured resin. However, if the temperature is not within a specific temperature range, a highly ordered structure may not be obtained, and thus a desired thermal conductivity may not be obtained. According to the heat treatment conditions for producing the cured resin sheet described above, when a cured resin is formed using an epoxy resin having a mesogenic structure in the molecule and a specific novolac resin, a highly regular structure is cured. It is easy to obtain a product and tends to improve the thermal conductivity.

<Resin sheet laminate>
The resin sheet laminated body of this invention has the resin sheet of this invention, and the metal plate or heat sink which are arrange | positioned on the at least one surface of the said resin sheet. The details of the resin sheet of the present invention constituting the resin sheet laminate of the present invention are as described above. Moreover, as a metal plate or a heat sink, a copper plate, an aluminum plate, a ceramic plate, etc. are mentioned. In addition, the thickness of a metal plate or a heat sink is not specifically limited, According to the objective etc., it can select suitably. Moreover, you may use metal foil, such as copper foil and aluminum foil, as a metal plate or a heat sink.

  In the resin sheet laminated body of this invention, a metal plate or a heat sink is arrange | positioned on the at least one surface of the resin sheet of this invention, Preferably it arrange | positions on both surfaces.

  The resin sheet laminated body of this invention can be manufactured with the manufacturing method including the process of arrange | positioning a metal plate or a heat sink on at least one surface of the resin sheet of this invention, and obtaining a laminated body.

  As a method of disposing a metal plate or a heat radiating plate on the resin sheet, a commonly used method can be used without particular limitation. For example, the method of bonding a metal plate or a heat sink on at least one surface of a resin sheet can be mentioned. The bonding method may be a method by adhesion with a resin component contained in the resin sheet or a method by adhesion of grease applied to the surface of the resin sheet. These methods can be appropriately used depending on the required physical properties, the form of the semiconductor device formed using the resin sheet laminate, and the like. Specific bonding methods include a pressing method and a laminating method. The conditions for the pressing method and the laminating method can be appropriately selected according to the configuration of the resin sheet. The heating and pressing method in the pressing step is not particularly limited. For example, the method of heat-pressing using a press apparatus, a lamination apparatus, a metal roll press apparatus, and a vacuum press apparatus can be mentioned.

  Conditions for heating and pressurizing can be, for example, a temperature of 60 ° C. to 250 ° C., a pressure of 0.5 MPa to 100 MPa, a time of 0.1 minutes to 360 minutes, a temperature of 70 ° C. to 240 ° C., The pressure is preferably 1 to 80 MPa, and the time is preferably 0.5 to 300 minutes. The heat and pressure treatment can be performed at atmospheric pressure (under normal pressure), but is preferably performed under reduced pressure. The decompression condition is preferably 30000 Pa or less, more preferably 10,000 Pa or less.

  Further, the resin sheet laminate of the present invention has a metal plate or a heat radiating plate on one surface of the resin sheet, and has an adherend on the surface opposite to the surface on which the metal plate or the heat radiating plate is arranged. You may do it. Heat-treating the resin sheet laminate to cure the resin sheet contained in the resin sheet laminate, thereby forming a cured resin sheet laminate that has excellent thermal conductivity between the adherend and the metal plate or heat sink can do.

The adherend is not particularly limited. Examples of the material of the adherend include metals, resins, ceramics, composite materials such as resins / ceramics and resins / metals that are mixtures thereof. Examples of the shape of the adherend include various forms such as a thin film, a plate, and a box.
The resin sheet laminate of the present invention has a metal plate or a heat radiating plate on one surface of the resin sheet, and has a metal foil on the surface opposite to the surface on which the metal plate or the heat radiating plate is arranged. May be.

<Resin sheet laminate cured product and production method thereof>
The cured resin sheet laminate of the present invention is a heat-treated product of the resin sheet laminate. The method for producing a cured resin sheet laminate of the present invention includes a step of placing a metal plate or a heat sink on at least one surface of the resin sheet, and curing the resin sheet by applying heat to the resin sheet. And may include other steps as necessary.

  As a method of disposing a metal plate or a heat sink on the resin sheet, the method and conditions disclosed in the section of the resin sheet laminate can be applied.

  In the manufacturing method of the resin sheet laminated body cured product of the present invention, the resin sheet of the present invention is cured by heat treatment after the step of arranging the metal plate or the heat sink. Thermal conductivity improves more by performing the heat processing of the resin sheet laminated body. The heat treatment of the resin sheet laminate can be performed, for example, at 120 ° C. to 250 ° C. for 10 minutes to 300 minutes. Moreover, it is preferable that the heat processing conditions of a resin sheet laminated body include the temperature which a hardened | cured material tends to form a higher order structure from a heat conductive viewpoint. For example, in the heat treatment of the resin sheet laminate, it is more preferable to perform at least two steps of heating at 100 ° C. to 160 ° C. and 160 ° C. to 250 ° C. Furthermore, in the above temperature range, there are three or more steps. It is more preferable to perform the heating.

<Semiconductor device>
The semiconductor device of this invention is equipped with a semiconductor element and the resin sheet hardened | cured material of this invention arrange | positioned on the said semiconductor element. The semiconductor device may further include other members as necessary. As the semiconductor element, a commonly used semiconductor element can be used without particular limitation. Specific examples of the semiconductor element include an IGBT (Insulated Gate Bipolar Transistor), a power semiconductor element such as a thyristor, and an LED element. Hereinafter, a configuration example of a semiconductor device will be described with reference to the drawings.

1 to 6 show configuration examples of a power semiconductor device configured using the cured resin sheet of the present invention. In each figure, description of the same reference numerals may be omitted.
FIG. 1 shows heat dissipation in which a power semiconductor element 110 is disposed in a housing 103 on a water cooling jacket 120 via a copper plate 104 disposed via a solder layer 112, a cured resin sheet 102, and a grease layer 108. 3 is a schematic cross-sectional view showing a configuration example of a power semiconductor device 100 configured with a base 106. FIG. The periphery of the power semiconductor element 110 is sealed with a sealing resin 146. Since the heating element including the power semiconductor element 110 is in contact with the heat radiating member via the cured resin sheet 102, heat is efficiently radiated. The heat dissipation base 106 can be configured using copper, aluminum, or the like having thermal conductivity. Examples of the power semiconductor element 110 include an IGBT and a thyristor.

  FIG. 2 is a schematic cross-sectional view showing a configuration example of a power semiconductor device 150 configured by arranging cooling members on both surfaces of the power semiconductor element 110. In the power semiconductor device 150, the cooling member disposed on the upper surface of the power semiconductor element 110 includes a two-layer copper plate 104 provided via a solder layer 112. With such a configuration, generation of chip cracks and solder cracks can be more effectively suppressed. In FIG. 2, the copper plate 104 disposed on the side far from the semiconductor element 110 is connected to the water cooling jacket 120 via the resin sheet cured product 102 and the grease layer 108. On the other hand, in the cooling member disposed on the lower surface of the semiconductor element 110, one layer of the copper plate 104 is connected to the water cooling jacket 120 via the resin sheet cured product 102 and the grease layer 108. Further, a copper foil, an aluminum foil, or the like may be bonded to the surface of the cured resin sheet 102 on the grease layer 108 side. In FIG. 2, the cured resin sheet 102 and the water cooling jacket 120 are arranged via the grease layer 108, but the cured resin sheet 102 and the water cooling jacket 120 may be arranged so as to be in direct contact with each other.

  FIG. 3 is a schematic cross-sectional view illustrating a configuration example of a power semiconductor device 200 configured by disposing cooling members on both surfaces of the power semiconductor element 110. In the power semiconductor device 200, the cooling members disposed on both surfaces of the power semiconductor element 110 are each configured to include one layer of copper plate 104. Further, a copper foil, an aluminum foil, or the like may be bonded to the surface of the cured resin sheet 102 on the grease layer 108 side. In FIG. 3, the cured resin sheet 102 and the water cooling jacket 120 are disposed via the grease layer 108, but the cured resin sheet 102 and the water cooling jacket 120 may be disposed so as to be in direct contact with each other.

  FIG. 4 is a schematic cross-sectional view showing a configuration example of a power semiconductor device 250 configured by disposing cooling members on both surfaces of the power semiconductor element 110. In the power semiconductor device 250, the cooling member disposed on the upper surface of the power semiconductor element 110 includes the copper plate 104 provided via the solder layer 112. With such a configuration, generation of chip cracks and solder cracks can be more effectively suppressed. Further, by including the cured resin sheet 102 in the module, it is possible to prevent the influence of sheet cracking, external vibration, and the like, and the reliability is improved. In FIG. 4, the copper plates 104 disposed on the upper surface and the lower surface are connected to the water cooling jacket 120 via the resin sheet cured product 102, the heat dissipation base 106, and the grease layer 108, respectively. Examples of the heat dissipation base 106 include copper foil and aluminum foil. The power semiconductor element 110 is connected to the external terminal 116 through the wiring member 114. In FIG. 4, the cured resin sheet 102 and the water cooling jacket 120 are disposed via the heat radiation base 106 and the grease layer 108 disposed on the cured resin sheet 102. You may arrange | position so that the jacket 120 may contact directly.

  FIG. 5 is a schematic cross-sectional view showing a configuration example of a power semiconductor device 300 configured by disposing cooling members on both surfaces of the power semiconductor element 110. In the power semiconductor device 300, the cooling members disposed on both surfaces of the power semiconductor element 110 are each configured to include one layer of the copper plate 104. A copper plate 104 is disposed on one surface of the power semiconductor element 110 with a spacer 101 interposed therebetween. Further, by including the cured resin sheet 102 in the module, it is possible to prevent the influence of sheet cracking, external vibration, and the like, and the reliability is improved. In FIG. 5, the copper plate 104 is connected to the water cooling jacket 120 through the cured resin sheet 102, the heat dissipation base 106 and the grease layer 108. The power semiconductor element 110 is connected to an external terminal 116 through a wiring member 114. In FIG. 5, the cured resin sheet 102 and the water cooling jacket 120 are disposed via the heat dissipation base 106 and the grease layer 108 disposed on the cured resin sheet 102. You may arrange | position so that 120 may contact directly.

  In FIG. 6, the power semiconductor element 110 includes a copper plate 104 disposed via a solder layer 112, a cured resin sheet 102, and a heat radiation base 106 disposed on a water cooling jacket 120 via a grease layer 108. 2 is a schematic cross-sectional view showing a configuration example of a power semiconductor device 350. Since the heating element including the power semiconductor element 110 is in contact with the heat radiating member via the cured resin sheet 102, heat is efficiently radiated. The heat dissipation base 106 can be configured using copper, aluminum, or the like having thermal conductivity.

<LED device>
The LED device of the present invention is configured by laminating an LED element, a cured resin sheet of the present invention, and a substrate in this order. The LED device of the present invention may further include other members as necessary. An example of the substrate is an aluminum substrate.

In FIGS. 7-10, the structural example of the LED apparatus comprised using the resin sheet hardened | cured material of this invention is shown.
FIG. 7 is a schematic cross-sectional view showing an example of the configuration of the LED light bar 400 configured using the cured resin sheet of the present invention. The LED light bar 400 includes a housing 138, a grease layer 136, an aluminum substrate 134, a cured resin sheet 132, and an LED chip 130 arranged in this order and fixed with screws 140. By disposing the LED chip 130 as a heating element on the aluminum substrate 134 through the cured resin sheet 132, it is possible to efficiently dissipate heat.

  FIG. 8 is a schematic cross-sectional view showing a configuration example of the light emitting unit 450 of the LED bulb. The light emitting unit 450 of the LED bulb includes a housing 138, a grease layer 136, an aluminum substrate 134, a resin sheet cured product 132, a circuit layer 142, and an LED chip 130 arranged in this order and fixed with screws 140. Composed. FIG. 9 is a schematic cross-sectional view showing an example of the overall configuration of the LED bulb 500. A housing 138 that constitutes a light emitting portion of the LED bulb is disposed on a sealing resin 146 that encloses a power supply member 148.

  FIG. 10 is a schematic cross-sectional view showing an example of the configuration of the LED substrate 550. The LED substrate 550 includes an aluminum substrate 134, a cured resin sheet 132, a circuit layer 142, and an LED chip 130 arranged in this order. By disposing the LED chip 130 as a heating element on the aluminum substrate 134 via the circuit layer 142 and the cured resin sheet 132, heat can be efficiently radiated.

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

  The materials used for the production of the resin sheet and their abbreviations are shown below.

(Boron nitride filler)
Table 1 summarizes the specific surface area, primary particle size, and secondary particle size of the boron nitride filler.
HP: Mizushima Alloy Iron Co., Ltd., product name HP40
RP: Electrochemical Industry Co., Ltd., product name FP40
MP: Sumitomo 3M Co., Ltd., product name Agglomerates
GP: Electrochemical Industry Co., Ltd., product name GP
SGP: Electrochemical Industry Co., Ltd., product name SGP
HGP: Electrochemical Industry Co., Ltd., product name HGP
SP-2: Electrochemical Industry Co., Ltd., product name SP-2

(Alumina filler)
AA-18: aluminum oxide particles, product name: AA-18, Sumitomo Chemical Co., Ltd., volume average particle diameter 18 μm
AA-3: aluminum oxide particles, product name: AA-3, Sumitomo Chemical Co., Ltd., volume average particle diameter 3 μm
AA-04: aluminum oxide particles, product name: AA-04, Sumitomo Chemical Co., Ltd., volume average particle size 0.4 μm

(Curing agent (including novolak resin))
CRN: catechol resorcinol novolak resin, number average molecular weight 425, phenol compound content 35%

(Epoxy resin)
TN: 2,2 ′, 7,7′-tetra (2,3-epoxypropoxy) -1,1′-methylenebisnaphthalene type epoxy resin, product name: HP4710, DIC Corporation
-BP: biphenyl type epoxy resin, model number YL6121H, Mitsubishi Chemical Corporation
・ BIS-A / F: Bisphenol A / F mixed epoxy resin, model number ZX-1059, Nippon Steel & Sumikin Chemical Co., Ltd.

(Additive)
・ TPP: Triphenylphosphine (curing accelerator, Wako Pure Chemical Industries, Ltd.)

(Organic solvent)
CHN: cyclohexanone (Wako Pure Chemical Industries, Ltd., 1st grade)

(Support)
・ PET film: Product name A31, Teijin DuPont Films Ltd.
Copper foil: product name CF-T9D-SV, Fukuda Metal Foil Powder Co., Ltd., thickness 35 μm

<Synthesis example>
(Synthesis of novolac resin)
In a separable flask under a nitrogen atmosphere, 105 g of resorcinol and 5 g of catechol as monomers of a phenol compound, 0.11 g of oxalic acid as a catalyst (0.1% monomer ratio), and 15 g of methanol as a solvent were measured, respectively. The product was stirred and 30 g of formalin was added while cooling in an oil bath to 40 ° C. or lower. After stirring for 2 hours, the temperature of the oil bath was set to 100 ° C., and water and methanol were distilled off under reduced pressure while heating. After confirming that water and methanol were no longer distilled, CHN was added so that the content of novolak resin was 50% to obtain a catechol resorcinol novolak resin (CRN) solution.

  The number average molecular weight and monomer content ratio were quantified by molecular weight measurement of the obtained product by GPC. Moreover, the NMR spectrum of the obtained product was measured and it confirmed that the structural unit represented by general formula (IV) was contained. The conditions for GPC measurement and NMR measurement will be described later.

<Example 1>
3.13 parts of alumina (AA-04), 58.6 parts of HP, 19.6 parts of CRN as a solid content of an epoxy resin curing agent, and 52.5 parts of CHN were mixed. After confirming that it became uniform, 15.2 parts of TN, 2.75 parts of BP, 8.89 parts of BIS-A / F and 0.11 part of TPP were added and mixed as an epoxy resin, and then 3 Ball milling was performed for 40 hours to obtain a resin layer forming coating solution as a resin composition.

  A PET film (thickness 50 μm, Teijin DuPont Films Co., Ltd.) A31 is used as a support, and a resin layer-forming coating solution is placed on a table so that the thickness is approximately 100 μm on the release-treated surface. A coating layer was formed by coating using a coater (Tester Sangyo Co., Ltd.) Resin sheet 1 (A stage resin layer formed on a PET film after drying for 5 minutes in a box oven at 100 ° C. ( A stage sheet) was also formed.

  Two A-stage sheets obtained as described above were used and overlapped so that the resin layers face each other. Using a hot press apparatus (hot plate 100 ° C., pressure 10 MPa, treatment time 1 minute), heat-pressing and bonding, the B-stage resin sheet 1 having an average thickness of 188 μm (also called a B-stage sheet) )

[Preparation of cured resin sheet laminate]
The PET film was peeled off from both sides of the B stage sheet obtained above, and a 35 μm thick copper foil (Fukuda Metal Foil Powder Co., Ltd., CF-T9D-SV) was stacked on each side, followed by press treatment. went. The press treatment conditions were a hot plate temperature of 150 ° C., a vacuum degree of 10 kPa or less, a pressure of 10 MPa, and a treatment time of 3 minutes. Further, the cured resin sheet laminate 1 in a C-stage state in which copper foil is provided on both sides by sequentially heat-treating in a box-type oven at 140 ° C. for 2 hours, 165 ° C. for 2 hours, and 190 ° C. for 2 hours. Got.

<Example 2>
Alumina (AA-18, AA-3, AA-04) 7.67 parts, 5.56 parts, 9.16 parts, HP 48.2 parts, respectively, CRN as a solid content of epoxy resin curing agent 15.3 parts and 43.8 parts of CHN were mixed. After confirming that it became uniform, except that TN 11.8 parts, BP 2.14 parts and BIS-A / F 6.93 parts, and TPP 0.09 parts were further added and mixed as an epoxy resin. In the same manner as in Example 1, a resin sheet 2 in an A stage state, a resin sheet 2 in a B stage state, and a cured resin sheet laminate 2 in a C stage state in which copper foils were provided on both surfaces were obtained.

<Example 3>
In Example 1, alumina (AA-18, AA-3, AA-04) was 7.84 parts, 5.68 parts, 9.37 parts, HP 49.3 parts, and a curing agent for epoxy resin, respectively. 14.4 parts of CRN as a solid content and 41.3 parts of CHN were mixed. After confirming that it became uniform, except that 11.2 parts of TN, 2.02 parts of BP, 6.53 parts of BIS-A / F, and 0.08 parts of TPP were further added and mixed as an epoxy resin. In the same manner as in Example 1, a resin sheet 3 in an A stage state, a resin sheet 3 in a B stage state, and a cured resin sheet laminate 3 in a C stage state in which copper foils were provided on both surfaces were obtained.

<Example 4>
In Example 2, except that HP was replaced with 48.2 parts of RP and 65.7 parts of CHN were used, the same as in Example 2, the resin sheet 4 in the A stage state, the resin sheet 4 in the B stage state, C-stage resin sheet cured products 4 each having a copper foil provided on both surfaces were obtained.

<Example 5>
In Example 2, except that HP was replaced with 48.2 parts of MP and 65.7 parts of CHN were used, the same as in Example 2, the resin sheet 5 in the A stage state, the resin sheet 5 in the B stage state, C-stage resin sheet cured products 5 each having a copper foil provided on both surfaces were obtained.

<Example 6>
Alumina (AA-18, AA-3, AA-04) 17.4 parts, 5.97 parts, 9.81 parts, RP 47.6 parts, respectively, CRP as a solid content of epoxy resin curing agent 10.3 parts and 74.3 parts of CHN were mixed. After confirming that it became uniform, except that TN 8.06 parts, BP 1.46 parts and BIS-A / F 4.71 parts and TPP 0.16 parts were further added and mixed as an epoxy resin. In the same manner as in Example 1, a resin sheet 6 in the A stage state, a resin sheet 6 in the B stage state, and a cured resin sheet laminate 6 in the C stage state in which copper foil was provided on both surfaces were obtained.

<Example 7>
Alumina (AA-18, AA-3, AA-04) 24.73 parts, 5.54 parts, 9.11 parts, RP 44.2 parts, respectively, CRN as a solid content of epoxy resin curing agent 8.21 parts and 59.1 parts of CHN were mixed. After confirming that it became uniform, TN 6.41 parts, BP 1.16 parts and BIS-A / F 3.75 parts, and TPP 0.13 parts were further added and mixed as an epoxy resin. In the same manner as in Example 1, a resin sheet 7 in the A stage state, a resin sheet 7 in the B stage state, and a cured resin sheet laminate 7 in the C stage state in which copper foil was provided on both surfaces were obtained.

<Example 8>
Alumina (AA-18, AA-3, AA-04) 31.67 parts, 5.27 parts, 8.67 parts, RP 42.1 parts, respectively, CRP as a solid content as a curing agent for epoxy resin 6.51 parts and 46.9 parts of CHN were mixed. After confirming that it became uniform, TN 5.09 parts, BP 0.92 parts and BIS-A / F 2.98 parts, and TPP 0.10 parts were further added and mixed as an epoxy resin. In the same manner as in Example 1, a resin sheet 8 in an A stage state, a resin sheet 8 in a B stage state, and a cured resin sheet laminate 8 in a C stage state in which copper foils were provided on both surfaces were obtained.

<Comparative Example 1>
Alumina (AA-18, AA-3, AA-04) 7.67 parts, 5.56 parts, 9.16 parts, GP 48.2 parts respectively, CRN as a solid content of epoxy resin curing agent 15.3 parts and 43.8 parts of CHN were mixed. After confirming that it became uniform, except that TN 11.8 parts, BP 2.14 parts and BIS-A / F 6.93 parts, and TPP 0.09 parts were further added and mixed as an epoxy resin. In the same manner as in Example 1, a resin sheet C1 in the A stage state, a resin sheet C1 in the B stage state, and a cured resin sheet laminate C1 in the C stage state in which copper foil was provided on both surfaces were obtained.

<Comparative Example 2>
In Comparative Example 1, except that GP was replaced with 48.2 parts of SGP, a resin sheet C2 in the A stage state, a resin sheet C2 in the B stage state, and copper foils were provided on both sides in the same manner as in Comparative Example 1. C-stage resin sheet laminates C2 were obtained.

<Comparative Example 3>
In Comparative Example 1, except that GP was replaced with 48.2 parts of HGP, a resin sheet C3 in the A stage state, a resin sheet C3 in the B stage state, and copper foils were provided on both sides in the same manner as in Comparative Example 1. C-stage resin sheet laminates C3 were obtained.

<Comparative example 4>
In Comparative Example 1, except that GP was replaced with 48.2 parts of SP-2, in the same manner as Comparative Example 1, a resin sheet C4 in the A stage state, a resin sheet C4 in the B stage state, and copper foil provided on both surfaces The obtained C-stage resin sheet laminate cured product C4 was obtained.

<Evaluation>
The following evaluation was performed about the resin sheet laminated body of the B-stage state resin sheet obtained above and the C-stage state. The evaluation results are shown in Tables 2 to 3. In addition, the unit of the numerical value in the resin composition of Table 2-Table 3 is a mass part.

(Melt viscosity of resin sheet)
The melt viscosity at 100 ° C. of the resin sheet in the B-stage state is set at a measuring temperature of 25 ° C. to 180 ° C., a temperature increase rate of 5 ° C./min, Anton Paar Co., Ltd., a viscoelastic device MCR, The sheet thickness was measured at 0.6 mm or more.

(Specific surface area of inorganic filler)
The specific surface area of the inorganic filler refers to the BET specific surface area measured from the nitrogen adsorption capacity according to JIS Z8830-2001. As the evaluation device, QUANTACHROME: AUTOSORB-1 (trade name) or the like can be used. When measuring the BET specific surface area, it is considered that the moisture adsorbed on the sample surface and the structure affects the gas adsorption capacity. Therefore, pretreatment for removing moisture by heating is first performed.
In the pretreatment, the measurement cell charged with 0.05 g of the measurement sample is depressurized to 10 Pa or less with a vacuum pump, heated at 110 ° C., held for 3 hours or more, and kept at a normal temperature while maintaining the depressurized state. Cool naturally to (25 ° C). After performing this pretreatment, the evaluation temperature is 77K, and the evaluation pressure range is measured as a relative pressure (equilibrium pressure with respect to saturated vapor pressure) of less than 1. Moreover, each sample is measured 3 times and let the average value be a specific surface area.

(Calculation of average particle size determined from specific surface area of inorganic filler)
As a method for calculating the particle diameter R from the specific surface area S _m, a method using the inorganic filler density ρ, assuming that the inorganic filler is spherical, was used. V is the volume of the inorganic filler, S is the surface area of the inorganic filler, S _m is the specific surface area of the inorganic filler, and the particle diameter R is calculated from the specific surface area S _m using the following equation.

(Ratio of particles having a particle diameter of 25 μm to 100 μm in the inorganic filler)
The proportion of particles having a particle size of 25 μm to 100 μm in the inorganic filler contained in the resin sheet according to each of Examples and Comparative Examples is a resin in an organic solvent using a particle size distribution measuring device, Nikkiso Co., Ltd., MT3300EX. It was measured by dissolving the sheet. Specifically, the resin sheet is dissolved in an organic solvent, the resin is removed, and a liquid in which the inorganic filler is dispersed is produced. This inorganic filler dispersion is measured by repeating the measurement three times using the above apparatus.
Specifically, first, an inorganic filler is added to the solvent (water) within a range of 1% by mass to 5% by mass with 0.01% by mass to 0.1% by mass of a dispersant (sodium hexametaphosphate). Prepare sample solution. This sample solution is vibrated and dispersed with an ultrasonic vibrator (Sharp Manufacturing System Co., Ltd., model number UT-106, output 100 W) at a temperature of 23 ° C. for 3 to 5 minutes. About 2 mL of the dispersed sample solution is poured into the cell, and the particle size distribution is measured at 25 ° C., for example, with the refractive index of alumina being 1.77 and the refractive index of boron nitride being 2.17.

(Thermal conductivity of cured resin sheet laminate)
The copper foil was removed by etching using a sodium persulfate solution from the cured C-stage resin sheet laminate obtained in the above experiment. This was cut into 10 mm squares, blackened with graphite spray, and the thermal diffusivity was measured using a Nanoflash LFA447 model from NETZSCH.
The measurement conditions were a measurement temperature of 25 ± 1 ° C., a measurement voltage of 270 V, Amplitude 5000, and a pulse width of 0.06 ms.
The thermal conductivity was calculated from the product of the thermal diffusivity measured above, the density measured by the Archimedes method, and the specific heat measured by DSC (differential scanning calorimeter).

(Dielectric breakdown voltage of cured resin sheet laminate)
From the cured resin sheet laminate in the C-stage state obtained above, one side of the copper foil is left as it is, and five circular patterns with a diameter of 20 mm are formed on the opposite side copper foil by 20 mm each for evaluation. A substrate was produced. The dielectric breakdown voltage was measured by applying a voltage between the electrodes produced on the laminate cured product using a Yamayo Tester (with) YST-243-100RHO. As measurement conditions, the voltage was boosted by 1 kV to 0.2 kV at a time, and each voltage was held for 5 seconds. Measurement was performed at a measurement temperature of 23 ° C. ± 2 ° C. in Fluorinert.

(Evaluation of moisture resistance insulation)
From the cured C-stage resin sheet laminate obtained above, the copper foil on one side is left as it is, and four circular patterns with a diameter of 20 mm are formed on the opposite side copper foil by 20 mm each for evaluation. A substrate was produced. With respect to one example or comparative example, moisture resistance was evaluated as follows for a total of eight circular patterns using two evaluation substrates.
A DC voltage of 750 V was applied to each of the circular patterns in an environment of 85 ° C. and 85% RH for 1000 hours to determine the presence or absence of dielectric breakdown. The evaluation results are shown in Tables 2 to 3 as the form of the ratio of the number of circular patterns in which dielectric breakdown did not occur with respect to the total number (8) of circular patterns subjected to the test.

(Evaluation of tensile modulus, tensile fracture strain and tensile stress)
A dumbbell-shaped test piece having a distance between gripping jigs of 50 mm, a width of 5 mm, and a thickness of 0.2 mm is cut out from the B-stage sheet and heated at 100 ° C., 120 ° C., 140 ° C., and 180 ° C. for 1 hour. It hardened | cured and produced the test piece. The test conditions were a tensile speed of 1 mm / min, a test temperature of 23 ° C., and the elongation and load when it was pulled were measured. Tensile fracture strain was calculated as a percentage of the ratio of specimen length to elongation before testing. The tensile stress was calculated by calculating the ratio of the maximum load during the test and the area of the fractured part. The tensile modulus was a value obtained by dividing the tensile stress by the strain at that time.

(Evaluation of shear strength)
The PET film was peeled off from both sides of the B stage sheet, a metal plate was bonded to both sides, and the tensile shear bond strength (shear strength) was measured. Specifically, a 100 mm × 25 mm × 3 mm copper plate and an aluminum plate were alternately stacked and bonded to a 12.5 mm × 25 mm × 0.2 mm B stage sheet and cured. This was measured by pulling it with an AGC-100 type Shimadzu Corporation at a test speed of 2 mm / min and a measurement temperature of 23 ° C. In addition, adhesion | attachment and a hardening process were performed as follows. Bonding was performed by vacuum hot pressing (hot plate temperature 180 ° C., degree of vacuum 1 kPa or less, pressure 1 MPa, treatment time 30 minutes).

(Measurement of reaction rate)
The amount of heat of the B stage sheet (resin sheet) curing reaction was measured with a differential scanning calorimeter. The amount of heat obtained at this time was defined as 100%, and the reaction rate was calculated by calculating the ratio with the amount of heat of the curing reaction of the sheet after storage or after compression bonding by the following formula.

(Reaction rate of resin sheet (%)) = {1- (heat amount of resin sheet curing reaction after heat treatment at 30 ° C. for 48 hours) / (heat amount of resin sheet curing reaction before heat treatment at 30 ° C. for 48 hours)} × 100

Details of the measurement conditions and measurement method of the calorific value of the curing reaction with a differential scanning calorimeter are as follows.
A test piece was prepared by using Pyris 1 manufactured by Perkin Elmer as a differential scanning calorimeter, and slicing the resin sheet into a sample pan so that the resin weight contained in the sheet was 1 mg or more. The measurement atmosphere is nitrogen, the temperature rise rate is 10 ° C./min, the temperature is stabilized at 30 ° C. for 5 minutes, then the temperature rise is started and the calorific value up to 250 ° C. is measured. Calorific value.

(GPC measurement)
CRN obtained in the above synthesis example was dissolved in tetrahydrofuran (for liquid chromatograph), and PTFE (polytetrafluoroethylene) filter (Kurabo Co., Ltd., for HPLC pretreatment, chromatodisc, model number: 13N, pore size: 0 .45 μm) to remove insoluble matter. GPC [Pump: L6200 Pump (Hitachi, Ltd.), Detector: Differential refractive index detector L3300 RI Monitor (Hitachi, Ltd.), Column: TSKgel-G5000HXL and TSKgel-G2000HXL (both in total) (both Tosoh) The number average molecular weight was measured using a column temperature: 30 ° C., eluent: tetrahydrofuran, flow rate: 1.0 ml / min, standard material: polystyrene, detector: RI].

(NMR measurement)
The CRN obtained in the above example was dissolved in deuterated dimethyl sulfoxide _{(DMSO-d 6),} proton nuclear magnetic resonance method ⁽¹ H-NMR) ^(BRUKER Co., with AV-300 a (300 ^MHz), 1 H -NMR spectrum was measured, and the standard of chemical shift was set to 0 ppm for tetramethylsilane as an internal reference material.

  In Tables 2 and 3, “particle ratio” represents the ratio of particles having a particle diameter of 25 μm to 100 μm in the inorganic filler.

Table 2 and Table 3, the specific surface area of the inorganic filler according to the resin sheets of Examples are 1.0m ² /g~6.5m ² / g, 25μm~ occupying the inorganic filler when measured by a laser diffraction method It can be seen that when the proportion of the particles having a particle diameter of 100 μm is 30% by volume to 80% by volume, the cured adhesiveness (shear strength), insulation and thermal conductivity are excellent.

  100: power semiconductor device, 102: cured resin sheet, 103: housing, 104: copper plate, 106: heat dissipation base, 108: grease layer, 110: power semiconductor element, 120: water cooling jacket, 150: power semiconductor device, 200: Power semiconductor device, 250: Power semiconductor device, 300: Power semiconductor device, 350: Power semiconductor device, 130: LED chip, 132: Hardened resin sheet, 134: Aluminum substrate, 136: Grease layer, 138: Housing, 140: Screws 142: circuit layer, 146: sealing resin, 148: power supply member.

Claims (15)

Containing a resin and an inorganic filler,
The melt viscosity at 100 ° C. is 1.0 × 10 ⁵ Pa · s to 1.0 × 10 ⁸ Pa · s,
The specific surface area of the inorganic filler is 1.0m ² /g~6.5m ² / g,
When measured by a laser diffraction method, the proportion of particles having a particle diameter of 25 μm to 100 μm in the inorganic filler is 30% by volume to 80% by volume,
A resin sheet having a reaction rate of 20% or less.   2. The resin sheet according to claim 1, wherein an average particle diameter determined from a specific surface area of the inorganic filler is 0.4 μm to 2.7 μm.   The resin sheet according to claim 1, wherein the resin contains an epoxy resin and further contains a curing agent.   4. The resin sheet according to claim 3, wherein the epoxy resin contains a first or more trifunctional epoxy resin having a structure in which two naphthalene rings are included in a molecule and the two naphthalene rings are connected by an alkylene chain. . The resin sheet according to claim 4, wherein the first epoxy resin contains a compound represented by the following general formula (I).

(In General Formula (I), R ¹ represents an alkylene group having 1 to 7 carbon atoms.)   The resin sheet according to any one of claims 1 to 5, wherein the inorganic filler includes at least one selected from the group consisting of boron nitride, aluminum oxide, and aluminum hydroxide.   The tensile elastic modulus in the C stage state is 0.1 GPa to 30 GPa, and the tensile fracture strain in the C stage state is 0.10% to 0.70%. 7. Resin sheet.   2. A first resin layer containing the resin and the inorganic filler, and a second resin layer containing the resin and the inorganic filler laminated on the first resin layer. The resin sheet according to claim 7.   A cured resin sheet, which is a heat-treated product of the resin sheet according to any one of claims 1 to 8.   The resin sheet laminated body which has a resin sheet of any one of Claims 1-8, and the metal plate or heat sink arrange | positioned on the at least one surface of the said resin sheet.   The resin sheet laminated body of Claim 10 which further has a to-be-adhered body in the surface opposite to the surface where the said metal plate or heat sink of the said resin sheet is arrange | positioned.   A cured resin sheet laminate, which is a heat-treated product of the resin sheet laminate according to claim 10 or 11. A step of disposing a metal plate or a heat radiating plate on at least one surface of the resin sheet according to any one of claims 1 to 8,
Curing the resin sheet by applying heat to the resin sheet;
The manufacturing method of the resin sheet laminated body hardened | cured material which has this. A semiconductor element;
The resin sheet cured product according to claim 9, which is disposed on the semiconductor element,
A semiconductor device comprising:   The LED device by which an LED element, the resin sheet hardened | cured material of Claim 9, and a board | substrate are laminated | stacked in this order.