JP6222209B2 - Resin composition, resin sheet, resin sheet with metal foil, cured resin sheet, structure, and semiconductor device for power or light source - Google Patents

Description

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

  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, heat sinks and heat dissipation fins are indispensable for heat dissipation for stable operation of semiconductor devices used for central processing units of personal computers and motors of electric vehicles. There is a demand for a material that can achieve both insulation and thermal conductivity.

  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 insulating properties, their thermal conductivity is low and their contribution to heat dissipation from semiconductor devices and the like has not been significant. 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, their insulating properties are not sufficient compared to organic materials, and materials that can achieve both high insulating properties and thermal conductivity are required.

  In relation to the above, Patent Document 1 discloses a technique for providing a thermosetting resin cured product having excellent thermal conductivity as a material capable of achieving both insulation and thermal conductivity. High thermal conductivity is achieved by forming an anisotropic structure in the resin, and the thermal conductivity of the cured epoxy resin with the anisotropic structure formed by the mesogen skeleton is obtained by the plate comparison method (steady method). 0.68 to 1.05 W / m · K.

  In Patent Document 2, a composite material in which an epoxy resin containing a mesogenic skeleton and alumina as an inorganic filler having high thermal conductivity are mixed is studied. For example, a cured product composed of a composite system of a general bisphenol A type epoxy resin and an alumina filler is known, and the obtained thermal conductivity is 3.8 W / m · K, temperature wave thermal analysis in the xenon flash method. According to the law, 4.5 W / m · K can be achieved (see, for example, Patent Document 2). Similarly, a cured product composed of a composite system of an epoxy resin containing mesogen, an amine curing agent, and alumina is known, and the thermal conductivity is 9.4 W / m · K, temperature wave heat in the xenon flash method. According to the analysis method, 10.4 W / m · K can be achieved.

International Publication 02/094905 Pamphlet JP 2008-13759 A

However, in the cured product described in Patent Document 1, sufficient thermal conductivity has not been obtained in practical use. Moreover, since the hardened | cured material of patent document 2 was using the amine hardening | curing agent, it was inferior to a softness | flexibility and had the subject that a semi-hardened sheet | seat was easy to break.
The present invention relates to a resin composition having flexibility before curing and capable of achieving high thermal conductivity after curing, a resin sheet formed using the resin composition, a resin sheet with a metal foil, and a resin cured product It is an object to provide a sheet, a structure, and a semiconductor device for power or light source.

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

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

The resin composition preferably contains 50% to 85% by volume of the inorganic filler.
And it is preferable that the said resin composition contains the said polyfunctional epoxy resin 20 mass% or more in all the epoxy resins. The polyfunctional epoxy resin preferably contains a branched structure from the viewpoint of the crosslinking density and glass transition temperature of the cured resin, and specifically, a triphenylmethane type epoxy resin, a tetraphenylethane type epoxy resin, and dihydroxybenzene. It is preferably at least one selected from a novolac type epoxy resin and a glycidylamine type epoxy resin. In particular, at least one selected from a triphenylmethane type epoxy resin and a dihydroxybenzene novolak type epoxy resin containing a branched structure in the repeating unit is more preferable.

  From the viewpoint of lowering the softening point of the resin composition, the polyfunctional epoxy resin preferably further contains a liquid or semisolid epoxy resin, and the liquid or semisolid epoxy resin is a bisphenol A type epoxy resin or a bisphenol F type epoxy. It is preferably at least one selected from resins, bisphenol A-type and F-type mixed epoxy resins, bisphenol F-type novolac epoxy resins, naphthalene diol-type epoxy resins, and glycidylamine-type epoxy resins. In the present invention, “liquid” means that the melting point or softening point is less than room temperature, and “semi-solid” means that the melting point or softening point is 40 ° C. or less.

  The curing agent preferably contains 20 mass% to 70 mass% of at least one selected from mononuclear dihydroxybenzene.

  More preferably, the inorganic filler contains 50% to 95% by volume of the nitride particles. The nitride particles are preferably aggregates or pulverized products of hexagonal boron nitride, and the ratio of the major axis to the minor axis is preferably 2 or less.

  The resin composition preferably further contains a coupling agent. Furthermore, it is also preferable to contain a dispersing agent.

The second aspect of the present invention is a resin sheet that is an uncured body or a semi-cured body of the resin composition.
The 3rd aspect of this invention is a resin sheet with a metal foil which has the said resin sheet and metal foil.
A fourth aspect of the present invention is a cured resin sheet that is a cured product of the resin composition. The cured resin sheet preferably has a thermal conductivity of 10 W / m · K or more.

A fifth aspect of the present invention is a structure having the resin sheet or the cured resin sheet and a metal plate provided in contact with one or both surfaces of the resin sheet or the cured resin sheet.
A sixth aspect of the present invention is a power or light source semiconductor device having the resin sheet, the resin sheet with metal foil, the cured resin sheet, or the structure.

  ADVANTAGE OF THE INVENTION According to this invention, it has a softness | flexibility before hardening and the resin composition which can achieve high thermal conductivity after hardening, the resin sheet comprised using this resin composition, the resin sheet with metal foil, resin Hardened material sheets, structures and semiconductor devices for power or light sources can be provided.

It is a schematic sectional drawing which shows the structural example of the power semiconductor device comprised using the resin sheet with metal foil of this invention. It is a schematic sectional drawing which shows the other structural example of the power semiconductor device comprised using the resin sheet of this invention. It is a schematic sectional drawing which shows the other structural example of the power semiconductor device comprised using the resin sheet of this invention. It is a schematic sectional drawing which shows the other structural example of the power semiconductor device comprised using the resin sheet with metal foil of this invention. It is a schematic sectional drawing which shows the other structural example of the power semiconductor device comprised using the resin sheet of this invention. It is a schematic sectional drawing which shows the structural example of the LED light bar comprised using the structure of this invention. It is a schematic sectional drawing which shows the structural example of the LED bulb | ball comprised using the structure of this invention.

In this specification, “to” indicates a range including the numerical values described before and after the values as a minimum value and a maximum value, respectively.
In addition, in this specification, the term “process” is not limited to an independent process, and even if it cannot be clearly distinguished from other processes, the term “process” is used as long as the intended action of the process is achieved. included.
Further, when referring to the amount of each component in the composition in the present specification, when there are a plurality of substances corresponding to each component in the composition, the plurality of the components present in the composition unless otherwise specified. It means the total amount of substance.

<Resin composition>
The resin composition of the present invention includes an epoxy resin containing a polyfunctional epoxy resin, a curing agent containing a novolak resin having a structural unit represented by the following general formula (I), an inorganic filler containing nitride particles, Containing. With such a configuration, it is possible to form an insulating resin cured product having flexibility before curing and having excellent thermal conductivity after curing.

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

  In general, phonons are dominant in heat conduction in a cured epoxy resin obtained from an epoxy resin and a curing agent, and the heat conductivity is about 0.15 W / m · K to 0.22 W / m · K. This is due to the fact that the cured epoxy resin is amorphous and does not have a structure that can be called an ordered structure, and that there are fewer covalent bonds that bring about the harmony of lattice vibration than metals and ceramics. Therefore, phonon scattering is large in the cured epoxy resin, and the mean free path of phonons is as short as about 0.1 nm for the cured epoxy resin, for example, compared to 100 nm for crystalline silica, which causes low thermal conductivity. ing.

  The formation of the anisotropic structure by mesogen as shown in the above-mentioned International Publication 02/094905 pamphlet is considered that the crystalline arrangement of the epoxy resin molecule suppresses the static scattering of phonons and the thermal conductivity is improved. . However, many epoxy resin monomers containing mesogens have high crystallinity and low solubility in solvents, and special conditions may be required to handle them as resin compositions. Therefore, there is a demand for an epoxy resin monomer that does not contain a mesogen and is easily dissolved in a solvent.

  The present inventors have found that in order to increase the thermal conductivity, increasing the number of covalent bonds that bring about the harmonicity of lattice vibration and reducing dynamic phonon scattering are effective in improving the thermal conductivity. The present invention has been reached. A structure having a large number of covalent bonds that bring about harmonicity of lattice vibration can be obtained by shortening the distance between the branch points of the resin skeleton and forming a fine mesh. That is, in the thermosetting resin, a structure having a small molecular weight between crosslinking points is preferable. With such a configuration, the crosslink density is increased, and even when the anisotropic structure is not formed in the cured epoxy resin containing no mesogen, it is effective in improving the thermal conductivity.

  In the resin composition after curing, in order to shorten the distance between the branch points of the resin skeleton and to form a fine network, in the present invention, specifically, a polyfunctional epoxy resin is used as the epoxy resin, and the above-mentioned as a curing agent. A novolak resin having a structural unit represented by the general formula (I) is used, and nitride particles are used as an inorganic filler.

(Epoxy resin)
The resin composition of the present invention contains a polyfunctional epoxy resin as an epoxy resin. By including a polyfunctional epoxy resin, the crosslinking density can be increased. The polyfunctional epoxy resin can be prepared from a polyfunctional epoxy resin monomer.

The polyfunctional epoxy resin may have a linear structure or a branched structure. However, the polyfunctional epoxy resin having a branched structure and a skeleton having a reactive epoxy group at a side chain or a terminal has a branched structure. Since the molecular weight between the crosslinking points decreases and the crosslinking density increases because the part becomes a crosslinking point, it is particularly preferable that the repeating unit of the multimer contains a branched structure.
This will be described by comparing an epoxy resin having a repeating unit represented by the following formula (II) with an epoxy resin having a repeating unit represented by the following formula (III).

  An epoxy resin (epoxy equivalent 165 g / eq) having a repeating unit represented by the following formula (II) has a linear structure. On the other hand, the repeating structure (2) and a repeating epoxy chain end group (1) containing a reactive epoxy terminal group (1) in the branched side chain moiety and having substantially the same epoxy equivalent as the formula (II) are shown below. In the case of an epoxy resin having a unit (epoxy equivalent: 168 g / eq), it is estimated that the cross-linking network is finer, and it is expected that the cross-linking density is further increased.

An epoxy resin having a repeating unit represented by the above formula (II) or (III) (reactive epoxy terminal group (1): p-position), and a structural unit represented by the general formula (I) according to the present invention as a curing agent The structural formulas of the reactants when ideally reacted with a novolak resin (m = 2.0, n = 2, bonding position of OH group: m-position, R ¹ and R ² = hydrogen atom), respectively, It is shown in formulas (IV) and (V). Rather than the size of the network of the following formula (IV) which is a reaction product of the general formula (I) and the formula (II), the following formula is a reaction product of the general formula (I) and the formula (III) having a branched structure. It is clear that the mesh of (V) is smaller. Therefore, the polyfunctional epoxy resin is preferably an epoxy resin having a repeating unit represented by the formula (III).

  In addition, the epoxy resin skeleton including the repeating unit includes, for example, a skeleton of the following formula (VI) represented by n = 1 assuming that a hydrogen atom and an epoxidized phenol are bonded to both ends in the formula (III). be able to.

  The polyfunctional epoxy resin preferably has a small epoxy equivalent. A small epoxy equivalent indicates a high crosslink density. Specifically, the epoxy equivalent is preferably 200 g / eq or less, and more preferably 170 g / eq or less.

  Moreover, it is preferable that the said polyfunctional epoxy resin does not have residues, such as an alkyl group and a phenyl group which do not participate in bridge | crosslinking. Residues not involved in the reaction are considered to cause phonon scattering by being converted into phonon reflection and thermal motion of the residues in phonon conduction.

  Examples of the polyfunctional epoxy resin include phenol novolac epoxy resin, triphenylmethane type epoxy resin, tetraphenylethane type epoxy resin, dihydroxybenzene novolac epoxy resin, and glycidylamine type epoxy resin. From the viewpoint of the branched structure, it is more preferable that it is at least one selected from triphenylmethane type epoxy resin, tetraphenylethane type epoxy resin and glycidylamine type epoxy resin, and from the viewpoint of crosslinking density, a reactive terminal is added to the repeating unit. A triphenylmethane type epoxy resin having a branched structure is more preferable. Further, even with a linear type curing agent, a dihydroxybenzene novolac type epoxy resin having a reactive end larger than 1 in the repeating unit is preferable from the viewpoint of the crosslinking density.

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

  The epoxy resin in the present invention preferably further contains a liquid or semi-solid epoxy resin. Liquid and semi-solid epoxy resins may give the effect of lowering the softening point of the resin composition. Among liquid and semi-solid epoxy resins, liquid epoxy resins are preferred from the viewpoint of the effect of lowering the softening point.

  Examples of such liquid or semi-solid epoxy resins include bisphenol A type epoxy resins, bisphenol F type epoxy resins, bisphenol A type and F type mixed epoxy resins, bisphenol F novolak type epoxy resins, naphthalenediol type epoxy resins, and glycidylamine. It is preferable to use at least one selected from type epoxy resins.

  From the viewpoint of the softening point lowering effect, the liquid or semi-solid epoxy resin is selected from bisphenol F type epoxy resin, bisphenol A type and F type mixed epoxy resin, bisphenol F type novolac epoxy resin, and glycidylamine type epoxy resin. It is preferable to use at least one of the above.

  The liquid or semi-solid epoxy resin is often a bifunctional epoxy resin, and in the case of a bifunctional epoxy resin monomer, it does not have a branched structure and extends between the cross-linking points, thereby reducing the cross-linking density. Should not be much. Therefore, the bifunctional liquid or semi-solid epoxy resin is preferably contained at 50% by mass or less of the total epoxy resin, more preferably at 30% by mass or less, and further at 20% by mass or less. preferable.

From the above viewpoint, in order to suppress a decrease in the crosslinking density, it is preferable to use a bisphenol F type novolac epoxy resin or a glycidylamine type epoxy resin which is a polyfunctional liquid or semi-solid epoxy resin. The polyfunctional liquid or semi-solid epoxy resin is preferably contained at 50% by mass or less of the total epoxy resin, more preferably at 30% by mass or less, and further preferably at 20% by mass or less.
However, the modification functions and skeletons listed here are only examples and are not limited.

(Curing agent)
The resin composition of this invention contains the novolak resin which has a structural unit represented by the following general formula (I) as a hardening | curing agent.
From the viewpoint of the molecular design described above, it is preferable to select a novolak resin used as the curing agent in the present invention having a smaller hydroxyl equivalent as in the case of the epoxy resin. Thereby, the density | concentration of the hydroxyl group which is a reactive group becomes high. Further, like an epoxy resin, it is preferable that a novolak resin contains as little residue as possible not involved in crosslinking.
From the above viewpoint, the novolak resin used as the curing agent has a structural unit represented by the following general formula (I).

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

  The novolak resin preferably has a small hydroxyl equivalent, and in the novolak resin having the structural unit represented by the general formula (I), m is 1.5 or more on average, so that the hydroxyl equivalent is appropriately reduced. ing. On the other hand, if the hydroxyl equivalent is too small, the resulting cured product tends to be brittle, so m is an average value of 2.5 or less. Therefore, m in the general formula (I) is an average value of 1.5 to 2.5, and more preferably 1.7 to 2.2.

  Moreover, m which is the valence of a hydroxyl group should just be an average value, for example, the monovalent phenol and divalent resorcinol are used together as an equimolar ratio, and an average valence is adjusted to 1.5-2.5. May be.

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

Furthermore, from the viewpoint of the softening point of the novolak resin, n in the general formula (I) is an average value of 1 to 15, and from the viewpoint of fluid viscosity at the time of heating such as pressure bonding of the resin composition processed into a sheet shape, n is preferably an average value of 1 to 10.
In addition, n should just be an average value, ie, as a hardening | curing agent frame | skeleton containing a repeating unit, for example, in general formula (I), a hydrogen atom and m valent phenol (-Ph- (OH) m) are used for both ends. Including a compound of the following formula (VII) represented by n = 1 obtained when n is bonded or a compound in which n is greater than 15, n may be 1 to 15 as an average value.

  Moreover, it may be a case where the novolak resin is a mixture having different molecular weights by synthesis and n is obtained as an average value of 1 to 15, or a novolak resin having a different molecular weight is mixed and n is 1 to 15 as an average value. It may be a case where it is adjusted to.

  The aldehyde and ketone used for synthesizing the novolak resin are preferably formaldehyde from the viewpoint of hydroxyl equivalent, but acetaldehyde may be selected from the viewpoint of heat resistance, or acetone may be selected for ease of synthesis. Furthermore, in order to achieve both hydroxyl equivalent and heat resistance, at least two of formaldehyde, acetaldehyde, and acetone may be used in combination.

  From the above, the novolak resin is preferably a novolak resin obtained by condensing a mononuclear phenol compound having a divalent phenolic hydroxyl group as a monomer and formaldehyde, acetaldehyde or acetone as an aldehyde.

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

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

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

  The curing agent may further contain other novolak resin, a phenol compound (monomer) having a mononuclear or higher divalent hydroxyl group, an aralkyl resin, and the like for modification. The higher the valence of the phenolic hydroxyl group, the smaller the hydroxyl equivalent, but the crosslinking density becomes too high and the cured resin tends to be brittle. On the other hand, when the said hardening | curing agent contains the said monomer, it becomes suppressed that a resin hardened | cured material becomes weak. The curing agent containing the monomer can be obtained by adding a monomer to the curing agent or leaving unreacted monomer at the time of synthesis.

  The monomer is preferably a raw material phenol compound used to synthesize the novolak resin having the structural unit represented by the general formula (I), but may further include another mononuclear phenol compound. . Among such mononuclear phenol compounds, mononuclear dihydric phenol compounds (mononuclear dihydroxybenzene) are preferable. Mononuclear dihydroxybenzene may be used individually by 1 type, or may use 2 or more types together. It is preferable to add mononuclear dihydroxybenzene because the effect of suppressing the decrease in the crosslinking density can be obtained while lowering the softening point of the resin composition.

  Examples of the mononuclear dihydroxybenzene include catechol, resorcinol, and hydroquinone, and among these three types, resorcinol that is not easily oxidized is preferable. The skeletons listed here are examples and are not limited.

  The total content of at least one selected from the mononuclear dihydroxybenzene compound is preferably 20% by mass to 70% by mass in the total curing agent from the viewpoints of thermal conductivity and softening point, and particularly the semi-cured sheet. From a viewpoint of a softness | flexibility and the crosslinking density of hardened | cured material, 30 mass%-50 mass% are preferable. Within the above range, the number of functional groups not involved in crosslinking is suppressed, so that dynamic scattering of phonons is suppressed, and a decrease in the thermal conductivity of the cured resin is suppressed.

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

The content of the curing agent in the resin composition of the present invention is preferably adjusted so that the ratio of the hydroxyl group equivalent in the curing agent to the epoxy equivalent of the poxy resin is close to 1. The closer the equivalent ratio is to 1, the higher the crosslink density, and the expected effect of reducing phonon dynamic scattering can be expected. Specifically, the equivalent ratio (hydroxyl group equivalent / epoxy equivalent) is preferably 0.8 to 1.2, more preferably 0.9 to 1.1, and 0.95 to 1. More preferably, it is 05.
However, when using an imidazole curing accelerator or an amine curing accelerator in which chain polymerization of epoxy groups occurs as a curing accelerator, unreacted epoxy groups are unlikely to remain. May be added in excess.

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

  In general, aluminum oxide, aluminum hydroxide, silicon oxide, and the like used as inorganic fillers have a hydroxyl group on the surface of the particles and adsorb water, although a very small amount, adsorbed water inhibits the curing reaction and has a crosslinking density. It is known to go down. Therefore, the cured epoxy resin containing an inorganic filler mainly composed of aluminum oxide, aluminum hydroxide, silicon oxide or the like has a lower glass transition temperature than the cured epoxy resin containing no inorganic filler. In particular, in the epoxy resin system having a high crosslinking density according to the present invention, it is considered that the influence appears remarkably.

  In contrast, boron nitride has low polarity and does not have a hydroxyl group on the surface, so it is difficult to adsorb water, and does not cause curing inhibition to the epoxy resin caused by these hydroxyl groups or adsorbed water. And the curing reaction of the curing agent proceeds to give a high crosslinking density. Thereby, it is considered that the glass transition temperature of the cured epoxy resin containing the inorganic filler mainly composed of boron nitride is equivalent to the cured epoxy resin not containing the inorganic filler.

  Whether or not boron nitride is contained in the resin composition can be confirmed by, for example, energy dispersive X-ray analysis (EDX), and particularly in combination with a scanning electron microscope (SEM). It is also possible to confirm the distribution state of boron nitride in the cross section.

  The crystal form of the boron nitride may be any of hexagonal, cubic, and rhombohedral, but hexagonal is preferable because the particle diameter can be easily controlled. Two or more types of boron nitride having different crystal forms may be used in combination.

  From the viewpoint of thermal conductivity and varnish viscosity, the hexagonal boron nitride particles are preferably pulverized or agglomerated. Examples of the particle shape of the hexagonal boron nitride include a round shape, a spherical shape, a flake shape, and an agglomerated particle. As the shape of the particle having a high filling property, the ratio of the major axis to the minor axis is preferably 3 or less. Is preferably 2 or less round or spherical, more preferably spherical. In particular, the agglomerated boron hexagonal boron nitride has many gaps and is easily crushed and deformed by applying pressure. Therefore, the filling rate of the inorganic filler is lowered in consideration of the coating properties of the varnish of the resin composition. However, it is possible to increase the substantial filling rate by compressing with a press after application. From the viewpoint of the ease of forming a heat conduction path by contact between inorganic fillers with high thermal conductivity, the particle shape is considered to have more contact points in the round shape or scale shape than the spherical shape, Spherical particles are preferable in view of the balance between the above-described filling properties and the thixotropic viscosity of the resin composition. In addition, the said boron nitride particle from which particle shape differs may be used individually by 1 type, or may use 2 or more types together.

  Moreover, in view of the filling property of the inorganic filler, an inorganic filler other than boron nitride may be used in combination in order to fill the gap. Although it will not have a restriction | limiting in particular if it is an inorganic compound which has insulation, It is preferable that it is what has high heat conductivity. Specific examples of inorganic fillers other than boron nitride include beryllium oxide, aluminum oxide, magnesium oxide, silicon oxide, aluminum nitride, silicon nitride, talc, mica, aluminum hydroxide, barium sulfate and the like. Among these, aluminum oxide, aluminum nitride, and silicon nitride are preferable from the viewpoint of thermal conductivity.

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

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

  As the particle size distribution of the inorganic filler exhibiting the particle size distribution having two or more peaks, for example, when showing the particle size distribution having three peaks, the average of 0.1 μm to 0.8 μm as the small particle size particles It is preferable to have a particle diameter, an average particle diameter of 1 μm to 8 μm as a medium particle diameter particle, and an average particle diameter of 20 μm to 60 μm as a large particle diameter particle. By being such an inorganic filler, the filling rate of the inorganic filler is further improved, and the thermal conductivity is further improved. From the viewpoint of filling properties, the large particle diameter particles preferably have an average particle diameter of 30 μm to 50 μm, and the medium particle diameter particles are preferably 1/4 to 1/10 of the average particle diameter of the large particle diameter particles. The particles are preferably ¼ to 1/10 of the average particle size of the medium-sized particles.

  The nitride particles are preferably used as the large particle size particles. The medium-sized particles and the small-sized particles may be nitride particles or other particles, and are preferably aluminum oxide particles from the viewpoint of thermal conductivity and thixotropic properties of the varnish. .

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

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

  The volume-based content of the inorganic filler in the resin composition is measured as follows. First, the mass (Wc) of the resin composition at 25 ° C. was measured, and the resin composition was baked in the air at 400 ° C. for 2 hours, then at 700 ° C. for 3 hours, and the resin content was decomposed and burned off. Thereafter, the mass (Wf) of the remaining inorganic filler at 25 ° C. is measured. Next, the density (df) of the inorganic filler at 25 ° C. is obtained using an electronic hydrometer or a specific gravity bottle. Next, the density (dc) of the resin composition at 25 ° C. is measured by the same method. Next, the volume (Vc) of the resin composition and the volume (Vf) of the remaining inorganic filler are obtained, and the volume of the remaining inorganic filler is divided by the resin composition volume as shown in (Equation 1). Obtained as the volume ratio (Vr) of the inorganic filler.

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

Vc: volume of the resin composition (cm ³ ), Wc: mass of the resin composition (g)
dc: Density of resin composition (g / cm ³ )
Vf: Volume of inorganic filler (cm ³ ), Wf: Mass of inorganic filler (g)
df: density of the inorganic filler (g / cm ³ )
Vr: Volume ratio of inorganic filler

  Moreover, if the said inorganic filler is contained within the range of the said volume ratio, it will not specifically limit as a mass ratio. Specifically, when the resin composition is 100 parts by mass, the inorganic filler can be contained in a range of 1 part by mass to 99 parts by mass, and in a range of 50 parts by mass to 97 parts by mass. It is preferable to contain, More preferably, it is 80 mass parts-95 mass parts. When the content of the inorganic filler is within the above range, higher thermal conductivity can be achieved.

(Other ingredients)
The resin composition of the present invention can contain other components as needed in addition to the above components. Examples of other components include a curing accelerator, a coupling agent, a dispersant, an organic solvent, and a curing accelerator.

  In particular, when the epoxy resin or the curing agent has a nitrogen atom and is not basic, it is preferable to add the curing accelerator from the viewpoint of sufficiently proceeding the curing reaction of the resin composition. In addition, since the effect similar to an amine hardening accelerator can be anticipated when the nitrogen atom is contained in the molecule | numerator or resin composition of the said epoxy resin, it is not necessary to add a hardening accelerator.

  Examples of the curing accelerator include phosphorus-based curing accelerators such as triphenylphosphine (manufactured by Hokuko Chemical) and PPQ (manufactured by Hokuko Chemical); phosphonium salt-based curing accelerators such as TPP-MK (manufactured by Hokuko Chemical); EMZ- Organoboron curing accelerators such as K (made by Hokuko Chemical); 2E4MZ (made by Shikoku Chemicals), 2E4MZ-CN (made by Shikoku Chemicals), 2PZ-CN (made by Shikoku Chemicals), 2PHZ (made by Shikoku Chemicals) It is possible to use an imidazole curing accelerator such as triethylamine, N, N-dimethylaniline, an amine curing accelerator such as 4- (N, N-dimethylamino) pyridine, hexamethylenetetramine, and the like. In particular, phosphorus-based curing accelerators and phosphonium salt-based curing accelerators are suitable because they can suppress homopolymerization of the epoxy resin monomer, and thus facilitate the reaction between the curing agent and the epoxy resin. In this case, if the epoxy equivalent / hydroxyl equivalent is greater than 1, especially 1.2 or more, an unreacted epoxy group is generated, which may cause phonon scattering that lowers the thermal conductivity as described above. It is preferable to add an imidazole curing accelerator or an amine curing accelerator capable of homopolymerizing an epoxy group.

  Moreover, the resin composition contains a coupling agent, so that the bondability between the resin component containing the epoxy resin and the novolak resin and the inorganic filler is further improved, and higher thermal conductivity and stronger adhesion can be achieved. it can.

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

Examples of the functional group bonded to the resin component include an epoxy group, an amino group, a mercapto group, a ureido group, and an N-phenylamino group. From the viewpoint of storage stability, the coupling agent preferably has an epoxy group or N-phenylamino group functional group having a slow reaction rate.
Examples of the functional group bonded to the inorganic filler include an alkoxy group and a hydroxyl group. Examples of the coupling agent having such a functional group include a silane coupling having a dialkoxysilane or a trialkoxysilane. And titanate coupling agents having an alkoxy titanate.

  Specific examples of the silane coupling agent include 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 2- (3,4-epoxycyclohexyl). ) Ethyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3- (2-aminoethyl) aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3- (2-aminoethyl) aminopropyltrimethoxysilane, Examples thereof include N-phenyl-3-aminopropyltrimethoxysilane, 3-mercaptotriethoxysilane, and 3-ureidopropyltriethoxysilane.

Silane coupling agent oligomers (manufactured by Hitachi Chemical Coated Sand Co., Ltd.) represented by SC-6000KS2 can also be used.
As the titanate coupling agent, a titanate coupling agent having a terminal amino group (Ajinomoto Fine Techno Preact KR44) can be used.
These coupling agents can be used alone or in combination of two or more.

Although there is no restriction | limiting in particular as content of the coupling agent in the said resin composition, From a heat conductive viewpoint, it is 0.02 mass%-0.83 mass% with respect to the total mass of a resin composition. Is preferable, and it is more preferable that it is 0.04 mass%-0.42 mass%.
Moreover, it is preferable that content of a coupling agent is 0.02 mass%-1 mass% with respect to an inorganic filler from a heat conductive and insulating viewpoint, and 0.05 mass%-0.5 mass%. % Is more preferable.

  Further, since the resin composition contains a dispersant, the dispersibility of the inorganic filler in the resin component including the epoxy resin and the novolac resin is further improved, and the inorganic filler is uniformly dispersed, so that it is higher. Thermal conductivity and stronger adhesion can be achieved.

  The dispersant can be appropriately selected from those commonly used. For example, ED-113 (manufactured by Enomoto Kasei Co., Ltd.), DISPERBYK-106 (manufactured by BYK-Chemie GmbH), DISPERBYK-111 (manufactured by BYK-Chemie GmbH), Azisper PN-411 (manufactured by Ajinomoto Fine Techno), REB122-4 (manufactured by Hitachi) (Made by Kasei Kogyo) and the like. These dispersants may be used alone or in combination of two or more.

  The content of the dispersant in the resin composition is not particularly limited, but is preferably 0.01% by mass to 2% by mass with respect to the inorganic filler from the viewpoint of thermal conductivity. More preferably, the content is 1% by mass to 1% by mass.

(Production method of resin composition)
As a method for producing the resin composition of the present invention, a usual method for producing a resin composition can be used without particular limitation. For example, an inorganic filler and a coupling agent as necessary are mixed, and in addition to the epoxy resin and curing agent dissolved or dispersed in a suitable organic solvent, other curing accelerators or the like added as necessary It can be obtained by mixing the components.

The organic solvent for dissolving or dispersing the curing agent can be appropriately selected according to the novolak resin used. For example, alcohols such as methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-propanol, cellosolve, methyl cellosolve, ketone solvents such as methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, cyclopentanone, and butyl acetate An ester solvent such as ethyl lactate, an ether solvent such as dibutyl ether, tetrahydrofuran or methyltetrahydrofuran, or a nitrogen solvent such as dimethylformamide or dimethylacetamide can be preferably used.
In addition, as a method of mixing the epoxy resin, the curing agent, the inorganic filler, and the like, a normal stirrer, a raking machine, a three-roller, a ball mill, and the like can be appropriately combined.

<Resin sheet>
The resin sheet of this invention can be obtained by shape | molding the said resin composition in a sheet form. By the said resin sheet being comprised including the said resin composition, it is excellent in the storage stability before hardening, and the heat conductivity after hardening. The resin sheet of the present invention may be an uncured body or a semi-cured body. Here, semi-curing refers to a state generally referred to as a B-stage state, where the viscosity at room temperature (25 ° C.) is 10 ⁴ to 10 ⁵ Pa · s, whereas the viscosity at 100 ° C. is 10 ² to 10 ² . It means a state where the viscosity decreases to 10 ³ Pa · s. The viscosity can be measured by a torsional dynamic viscoelasticity measuring device or the like.

  Further, the resin sheet of the present invention may be one in which a resin layer made of the resin composition is provided on a support. The film thickness of the resin layer can be appropriately selected according to the purpose. For example, it is 50 μm to 500 μm, and is preferably thinner from the viewpoint of thermal resistance, and thicker from the viewpoint of insulation. The thickness is preferably 70 μm to 300 μm, more preferably 100 μm to 250 μm.

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

If necessary, the insulating support may be subjected to surface treatment such as primer coating, UV treatment, corona discharge treatment, polishing treatment, etching treatment, mold release treatment. The conductive support may also be subjected to surface treatment such as primer coating, coupling treatment, UV treatment, etching treatment, mold release treatment and the like. In particular, when the adhesion between the metal foil and the resin layer made of the resin composition is required, a resin layer may be provided on the roughened surface by polishing treatment or electrolytic foil.
Moreover, the said support body may be arrange | positioned only at the one surface of the resin sheet, and may be arrange | positioned at both surfaces.

  The film thickness of the support is not particularly limited, and is determined based on the knowledge of those skilled in the art as appropriate depending on the film thickness of the resin composition layer, the use of the resin sheet, and the production equipment. In terms of excellent handling properties, the thickness is preferably 10 μm to 150 μm, more preferably 40 μm to 110 μm.

  The resin sheet of this invention can be manufactured by apply | coating and drying the said resin composition on the said support body, for example. With respect to the application method and the drying method of the resin composition, a method that is usually used can be appropriately selected without particular limitation. For example, examples of the coating method include a comma coater, a die coater, and dip coating.

  As the drying method, a box-type hot air dryer can be used for batch processing, and a multistage hot air dryer can be used for continuous processing with a coating machine. There is no particular limitation on the heating conditions for drying, but when using a hot air dryer, the hot air of the dryer is lower than the boiling point of the solvent from the viewpoint of preventing the resin composition coating from swelling. It is preferable to include the process of heat-processing in the range.

When the resin sheet is a semi-cured material, the method for semi-curing is not particularly limited and a commonly used method can be appropriately selected. For example, the resin composition is semi-cured by heat treatment. There is no particular limitation on the heat treatment method for semi-curing.
The temperature range for the semi-curing can be appropriately selected according to the epoxy resin constituting the resin composition. From the viewpoint of the strength of the B-stage sheet, it is preferable to advance the curing reaction slightly by heat treatment, and the temperature range of the heat treatment is preferably 80 ° C to 150 ° C, more preferably 100 ° C to 120 ° C. . The time for the heat treatment for semi-curing is not particularly limited, but can be appropriately selected from the viewpoints of the curing speed of the resin of the B-stage sheet and the fluidity and adhesiveness of the resin. Heating is preferably performed within 30 minutes, more preferably 3 to 10 minutes.

  After semi-curing the resin sheet, two or more resin sheets may be superposed and pressed while being heated, and the resin sheet may be thermocompression bonded. Although the heating temperature at the time of thermocompression bonding can be selected according to the softening point and melting point of the resin, it is preferably 80 ° C to 180 ° C, more preferably 100 ° C to 150 ° C. Moreover, it is preferable to perform the pressurization at the time of thermocompression bonding under a vacuum, it is more preferable to pressurize by 4 MPa-20 MPa under a vacuum, and it is still more preferable to pressurize by 5 MPa-15 MPa.

<Resin cured product sheet and production method thereof>
The cured resin sheet of the present invention can be obtained by curing the resin composition. Thereby, the resin cured material excellent in heat conductivity can be comprised. There is no restriction | limiting in particular as a method of hardening | curing a resin composition, The method used normally can be selected suitably, For example, the said resin composition is hardened | cured by heat-processing.

There is no restriction | limiting in particular as a method of heat-processing the said resin composition, and there is no restriction | limiting in particular also about heating conditions.
However, since polyfunctional epoxy resins generally have a high curing rate, functional groups such as unreacted epoxy groups and hydroxyl groups are likely to remain when cured at high temperatures, and the effect of improving thermal conductivity tends to be difficult to obtain. Therefore, from the viewpoint of achieving higher thermal conductivity, it is preferable to include a step of performing a heat treatment in a temperature range near the activation temperature of the curing reaction (hereinafter sometimes referred to as “specific temperature range”). Here, the vicinity of the activation temperature of the curing reaction refers to the temperature from the temperature at which the curing heat generation of the epoxy resin occurs to the peak temperature of the reaction heat in the differential thermal analysis.

  Although the said specific temperature range can be suitably selected according to the epoxy resin which comprises a resin composition, it is preferable that it is 80 to 180 degreeC, and it is more preferable that it is 100 to 150 degreeC. By performing the heat treatment in such a temperature range, higher thermal conductivity can be achieved. When the temperature is 150 ° C. or lower, curing is prevented from proceeding too quickly, and when the temperature is 80 ° C. or higher, the resin is melted and curing proceeds.

  In addition, the time for the heat treatment in the specific temperature range is not particularly limited, but it is preferable to heat within 30 seconds to 15 minutes.

  In the present invention, it is preferable to provide at least one step of heat treatment at a higher temperature in addition to the heat treatment in a specific temperature range. Thereby, the elastic modulus, thermal conductivity, and adhesive force of the cured product can be further improved. The heat treatment at a higher temperature is preferably performed at 120 ° C. to 250 ° C., more preferably 120 ° C. to 200 ° C. If the temperature is too high, the resin is likely to oxidize and cause coloring. In addition, the heat treatment time is preferably 30 minutes to 8 hours, and more preferably 1 hour to 5 hours. Furthermore, this heat treatment is preferably carried out in multiple stages from a low temperature to a high temperature within the above temperature range.

  Examples of the method for forming a cured product of the resin composition into a sheet include a method in which the resin sheet is molded and then cured, and a method in which the resin composition is cured and then sliced into a sheet.

<Structure, resin sheet with metal foil>
The structure of the present invention includes the resin sheet or the cured resin sheet (hereinafter sometimes collectively referred to as “the sheet of the present invention”) and a metal provided in contact with one or both sides of the sheet of the present invention. And a board.

  Examples of the metal plate include a copper plate, an aluminum plate, and an iron plate. In addition, the thickness of a metal plate or a heat sink is not specifically limited. Moreover, you may use metal foil, such as copper foil, aluminum foil, and tin foil, as a metal plate. In addition, in this invention, what has the said metal foil on the single side | surface or both surfaces of the said resin sheet is called a resin sheet with metal foil.

  The thickness of the metal plate is preferably set as appropriate depending on the usage pattern, the thermal conductivity of the metal plate, and the like. Specifically, the average thickness is preferably 5 μm to 300 μm, and preferably 15 μm to 200 μm. Is more preferable, and it is preferable that it is 30 micrometers-150 micrometers.

  The said structure can be manufactured with the manufacturing method including the process of arrange | positioning a metal plate and obtaining a laminated body on the at least one surface of the sheet | seat of this invention. As a method for arranging the metal plate on the sheet of the present invention, a commonly used method can be used without any particular limitation. For example, a method of bonding a metal plate on at least one surface of the sheet of the present invention can be exemplified. Examples of the bonding method 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.

  Moreover, the said structure may have a metal plate on one surface of the sheet | seat of this invention, and may have a to-be-adhered body on the other surface. In this form, since the resin sheet or the cured resin sheet is sandwiched between the adherend and the metal plate, the thermal conductivity between the adherend and the metal plate is excellent after curing. The adherend is not particularly limited, and examples of the material of the adherend include a composite material that is a metal, a resin, a ceramic, and a mixture thereof.

  The said structure can be used for the semiconductor device for motive power or a light source. FIGS. 1-7 shows the structural example of the power semiconductor device comprised using the sheet | seat of this invention, an LED light bar, and an LED bulb as an example of the said structure.

  In FIG. 1, a resin sheet 110 with a metal foil in which a semi-cured resin sheet 112 and a metal support 114 are laminated as a protective layer of the semi-cured resin sheet 112 is used. Specifically, FIG. 1 shows that the power semiconductor chip 102 is disposed on a copper or copper alloy lead frame 106 through a solder layer 104, and is sealed and fixed with a sealing resin 108, whereby the resin with metal foil of the present invention is used. The semi-cured resin sheet 112 in the sheet 110 is pressure-bonded and cured with the lead frame 106, the metal support 114 is configured as a protective layer for the semi-cured resin sheet 112, and the heat sink 120 is interposed via a heat conductive material 122 such as heat radiation grease. It is a schematic sectional drawing which shows the structural example of the power semiconductor device 100 arrange | positioned in.

Through the resin sheet 110 with metal foil of the present invention, it is possible to electrically insulate between the lead frame 106 and the heat sink 120 and to efficiently dissipate heat generated in the power semiconductor chip 102 to the heat sink 120. . Note that a thick metal plate can be used for the lead frame 106 in order to improve heat dissipation. The heat sink 120 can be configured by using copper or aluminum having thermal conductivity, and can further efficiently transfer heat to a fluid such as air or water by forming cooling fins and water channels. . Examples of power semiconductor chips include IGBTs, MOS-FETs, diodes, and integrated circuits.
In addition, in subsequent FIGS. 2-7, about the member demonstrated in FIG. 1, the same code | symbol is provided and the description is abbreviate | omitted.

  In FIG. 2, a semi-cured resin sheet 112 is used. In detail, FIG. 2 shows the present invention in a so-called individual semiconductor component in which a power semiconductor chip 102 is disposed on a copper lead frame 106 via a solder layer 104 and sealed and fixed with a sealing resin 108 and a heat sink 120. 2 is a schematic cross-sectional view showing a configuration example of a power semiconductor device 150 in which a semi-cured resin sheet 112 is pressure-bonded and heat-cured and disposed via a heat conductive material 122. FIG. By using the resin sheet 112 of the present invention, it is possible to achieve both insulation and heat dissipation as in FIG.

  In FIG. 3, the power semiconductor chip 102 is disposed on a lead frame 106 made of copper or copper alloy via a solder layer 104, and the lead frame 106 made of copper or copper alloy is crimped to the heat sink 120 via the resin sheet 112 of the present invention. FIG. 6 is a schematic cross-sectional view showing a configuration example of a power semiconductor device 160 that is sealed with a sealing resin 108. As in FIG. 1, it is possible to achieve both insulation and heat dissipation.

  FIG. 4 is a schematic cross-sectional view showing a configuration example of a power semiconductor device 200 configured by disposing heat sinks 120 on both surfaces of the power semiconductor chip 102. Between each heat sink 120 and the lead frame 106, the resin sheet 110 with a metal foil of the present invention is disposed. The spacer 107 is disposed between the power semiconductor chip 102 and the lead frame 106 via the solder layer 104. With this configuration, it is possible to obtain a high cooling effect as compared with the single-sided cooling structure of FIGS.

  FIG. 5 is a schematic cross-sectional view showing a configuration example of a power semiconductor device 210 configured by arranging cooling members on both surfaces of the power semiconductor chip 102. Since the resin sheet 112 of the present invention bonds the lead frame 106 and the heat sink 120, the spacer 107 is not necessary, and a higher cooling effect than the configuration of FIG. 4 can be obtained.

FIG. 6 is a schematic cross-sectional view showing an example of the configuration of an LED light bar 300 configured using a structure 115 in which a cured resin sheet 112 of the present invention is sandwiched between a circuit-formed copper foil 116 and an aluminum plate 118. .
The LED light bar 300 includes a housing 132, a heat conductive material 122, a structure 115 of the present invention, and an LED individual component 130 arranged in this order. The LED individual component 130 that is a heating element can efficiently dissipate heat while having aluminum electrical insulation properties through the circuit-formed copper foil 116 and the cured resin sheet 112 of the present invention. The housing 132 can be made of metal to function as a heat sink.

  FIG. 7 is a schematic cross-sectional view illustrating an example of the configuration of an LED bulb 400 configured using a structure 115 in which a cured resin sheet 112 of the present invention is sandwiched between a circuit-formed copper foil 116 and an aluminum plate 118. The LED bulb 400 has an LED drive circuit 142, and the cap 146 on one side, the heat conductive material 122 on the other side, the structure 115 of the present invention, and the individual LED component 130 are arranged in this order via the bulb casing 140. The LED individual component 130 is covered with a lens 146. The LED individual component 130 that is a heating element is disposed on the light bulb housing 140 via the structure 115 of the present invention, so that 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 types and abbreviations or model numbers of the epoxy resins, novolak resins, inorganic fillers, additives, and solvents described in the examples are shown below.

(Epoxy resin monomer)
TPM-Ep: Triphenylmethane type epoxy resin (Nippon Kayaku EPPN-502H, multifunctional / branched solid epoxy resin, epoxy equivalent 168 g / eq)
PhN-Ep: Bisphenol F novolac epoxy resin (Mitsubishi Chemical Corporation jER 152, multifunctional / linear liquid epoxy resin, epoxy equivalent 165 g / eq)
BisAF-Ep: Liquid bisphenol A type epoxy resin and bisphenol F type epoxy resin mixture (manufactured by Nippon Steel Chemical Co., Ltd. ZX-1059, bifunctional liquid epoxy resin, epoxy equivalent 165 g / eq)

(Curing agent)
ReN: Resorcinol novolak resin (synthetic product, dihydric phenol type novolak resin (m = 2), hydroxyl equivalent: 62 g / eq, R ^{1 in} formula (I): H, R ² : H)
RCN: resorcinol catechol novolak resin (synthetic product, dihydric phenol type novolak resin (m = 2), hydroxyl equivalent: 62 g / eq, R ^{1 in} formula (I): H, R ² : H)
XLC: Phenol / phenylene aralkyl resin (Mitsui Chemicals XLC-LL, polyfunctional solid aralkyl resin, hydroxyl equivalent: 175 g / eq)
Res: Resorcinol (Reagent manufactured by Wako Pure Chemical Industries, divalent mononuclear phenol compound, hydroxyl group equivalent 55 g / eq)

(Inorganic filler)
HP-40 (Boron nitride, made of Mizushima alloy iron; volume average particle size 40 μm, hexagonal crystal, aggregation, aspect ratio 1.5)
PT-110 (boron nitride, manufactured by Momentive Japan; volume average particle size 43 μm, hexagonal, scaly, aspect ratio 10)
AA-18 (aluminum oxide, manufactured by Sumitomo Chemical; volume average particle size 18 μm)
AA-3 (aluminum oxide, manufactured by Sumitomo Chemical; volume average particle size 3 μm)
AA-04 (aluminum oxide, manufactured by Sumitomo Chemical; volume average particle size 0.4 μm)
Shapal H (aluminum nitride Tokuyama; volume average particle diameter 0.5 μm)

(Curing accelerator)
TPP: Triphenylphosphine (Wako Pure Chemical Industries, Ltd.)

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

(Dispersant)
BYK-106 (Made by Big Chemie Japan)
REB122-4 (Hitachi Chemical Industries, 45% ethyl lactate solution)

(solvent)
CHN: cyclohexanone

(Support)
PET: single-sided release-treated polyethylene terephthalate film (Fujimori Kogyo Co., Ltd., film binder 75E-0010CTR-4)
GTS: Electrolytic copper foil (Furukawa Electric Co., Ltd., thickness 80 μm, GTS grade)

[Synthesis of novolac resin]
(ReN synthesis)
In a 1 L separable flask equipped with a stirrer, a condenser and a thermometer, resorcinol 110 g (1 mol), 37% formalin 45 g (about 0.5 mol, F / P = 0.5), oxalic acid 1.1 g as a catalyst, solvent After weighing 50 g of water, the oil bath was brought to 120 ° C. while stirring the contents, and the reaction was carried out for 3 hours while refluxing. Thereafter, the cooler was removed, a distiller was attached, and the temperature was raised to 150 ° C. while distilling off water. The reaction was further continued with stirring at 150 ° C. for 12 hours. After completion of the reaction, the mixture was heated to 170 ° C., and unreacted resorcinol was sublimated under reduced pressure and removed over 8 hours. After removing the monomer, it was transferred to a stainless steel bat and cooled to obtain a resorcinol novolak resin (ReN).

Resorcinol novolak resin (ReN) was measured for molecular weight by GPC, the monomer content was 8% by mass, and the number average molecular weight of the reaction product excluding the monomer was 900. ¹ H NMR measurement showed that the repeating unit contained 2.0 hydroxyl groups on average. By dividing the number average molecular weight by the molecular weight 122 of the structural unit of the formula (I), the average number of repeating units n was calculated as 7.4. The hydroxyl equivalent was 62 g / eq.

(Synthesis of RCN)
Into a 3 L separable flask equipped with a stirrer, a condenser and a thermometer, 627 g of resorcinol, 33 g of catechol, 316.2 g of 37% formalin, 15 g of oxalic acid, and 300 g of water were heated to 100 ° C. while heating in an oil bath. did. The mixture was refluxed at around 104 ° C. and reacted at the reflux temperature for 4 hours. Thereafter, the temperature in the flask was raised to 170 ° C. while distilling off water. The reaction was continued for 8 hours while maintaining 170 ° C. After the reaction, concentration was performed under reduced pressure for 20 minutes to remove water in the system and obtain resorcinol novolak resin (RCN).

Resorcinol / catechol novolak resin (RCN) was measured for molecular weight by GPC, the monomer content was 8% by mass, and the number average molecular weight of the reaction product excluding the monomer was 600. ¹ H NMR measurement revealed that the repeating unit contained 1.8 hydroxyl groups on average. The hydroxyl equivalent was 62 g / eq. Moreover, when the structure was confirmed by FD-MS, at least one xanthene skeleton derivative represented by any of the following formulas (VIIIa) to (VIIId) was contained. By ignoring the xanthene skeleton derivative and dividing the number average molecular weight by the molecular weight 119 of the structural unit of formula (I), the average number of repeating units n was calculated to be 5.0.

[Evaluation method of curing agent]
About the hardening | curing agent obtained above, the measurement of the physical-property value was performed as follows.
(Molecular weight measurement)
The number average molecular weight (Mn) was measured using a high performance liquid chromatography L6000 manufactured by Hitachi, Ltd. and a data analyzer C-R4A manufactured by Shimadzu Corporation. G2000HXL and G3000HXL manufactured by Tosoh Corporation were used as analytical GPC columns. The sample concentration was 0.2% by mass, tetrahydrofuran was used as the mobile phase, and the measurement was performed at a flow rate of 1.0 ml / min. A calibration curve was prepared using a polystyrene standard sample, and the number average molecular weight was calculated using the polystyrene conversion value.

(Hydroxyl equivalent)
The hydroxyl equivalent was measured by acetyl chloride-potassium hydroxide titration method. The determination of the titration end point was performed by potentiometric titration rather than coloration with an indicator because the solution color was dark. Specifically, the hydroxyl group of the measurement resin was acetylated in a pyridine solution, the excess reagent was decomposed with water, and the resulting acetic acid was titrated with a potassium hydroxide / methanol solution.

[Manufacture of cured epoxy resin without inorganic filler]
<Reference Example 1>
100 parts of TPM-Ep as a polyfunctional epoxy resin, 37 parts of ReN as a curing agent, and 0.3 part of TPP as a curing accelerator are weighed into a 5 cm diameter stainless steel petri dish, and 150 parts on a hot plate. After mixing while heating and melting at 0 ° C., the mixture was allowed to stand at 150 ° C. for 1 hour to be cured. Furthermore, after performing secondary curing at 160 ° C. for 2 hours and 190 ° C. for 2 hours, the cured resin was removed from the stainless steel dish to obtain a cured epoxy resin. As a result of the dynamic viscoelasticity measurement, a rubber-like flat region was present at 300 ° C. or higher, and the minimum value of the storage elastic modulus was 230 MPa at 340 ° C.

<Reference Example 2>
A cured resin was obtained in the same manner except that 66 parts of BisAF-Ep was used instead of TPM-Ep as the epoxy resin of Example 1, and 71 parts of XLC was used instead of ReN as the curing agent.

[Calculation of Crosslink Density of Reference Examples 1 and 2]
The crosslinking density was calculated for the cured products of the resin compositions of Reference Examples 1 and 2 by the following method. When Reference Example 1 and Reference Example 2 were compared, it was found that the cured product having the resin composition of Reference Example 1 had a crosslinking density that was about 12 times higher.

  The crosslinking density of the cured resin can be obtained from (Equation 2) from the storage elastic modulus minimum value (E′min) of the rubber-like flat region of the cured resin according to the classical rubber elasticity theory.

(Formula 2)

n: Crosslink density (mol / cm ³ ), Mc: Average molecular weight between crosslink points (g / mol)
E′min: minimum value of tensile storage modulus (Pa), ρ: density (g / cm ³ )
φ: front coefficient (φ≈1), R: gas constant (J / K · mol)
T: Absolute temperature of E'min (K)

[Manufacture of structure]
<Example 1>
In a 250 mL plastic bottle, 10.0 g (100 parts) of TPM-Ep as a polyfunctional epoxy resin main agent, 3.7 g (37 parts) of ReN as a curing agent, and 0.11 g (1.1 parts of TPP as a curing accelerator) ), 56 g (560 parts) of HP-40 as inorganic filler, 11.3 g (113 parts) of AA-04, 0.07 g (0.7 parts) of PAM as a coupling agent, and BYK-106 as a dispersant. 0.1 g (1 part) and 1.6 g (16 parts) of REB122-4, 50 g (500 parts) of CHN as a solvent, and 100 g (1000 parts) of 5 mm diameter alumina balls, Was closed for 30 minutes with a ball mill at a rotational speed of 100 revolutions / minute to obtain a resin composition varnish.

  After applying the obtained resin composition varnish on the release surface of a PET film (75E-0010CTR-4, manufactured by Fujimori Kogyo Co., Ltd.) using an applicator with a gap of 400 μm, a box oven at 100 ° C. is immediately applied. For 10 minutes.

  Next, two dry sheets were cut into 10 cm square, and two sheets were laminated with the resin surface facing inward, and thermocompression bonded by vacuum hot pressing (hot plate 150 ° C., pressure 10 MPa, vacuum degree ≦ 1 kPa, treatment time 1 minute), A B-stage sheet was obtained as a resin sheet having a resin composition layer thickness of 200 μm.

  The PET film is peeled off from both sides of the obtained B stage sheet, and both sides are sandwiched between the roughened surfaces of the GTS copper foil having a thickness of 80 μm, and vacuum hot press (hot plate temperature 150 ° C., vacuum degree ≦ 1 kPa, pressure 10 MPa, processing time) 10 minutes), followed by secondary curing in a box-type oven at 160 ° C. for 2 hours and 190 ° C. for 2 hours to obtain a structure having copper foil on both sides.

<Comparative Example 1>
Resin in the same manner as in Example 1 except that 6.6 g (66 parts) of BisAF-Ep was used instead of TPM-Ep, and 7.1 g (71 parts) of XLC was used instead of ReN as a curing agent. A cured product was obtained.

<Comparative example 2>
Instead of HP-40 and AA-04, the inorganic filler of Example 1 was 84.9 g (849 parts) of AA-18, 30.9 g (309 parts) of AA-3, and 12.9 g of AA-04. A cured resin was obtained in the same manner as in Example 1 except that (129 parts) was used.

<Comparative Example 3>
In place of HP-40 and AA-04, the inorganic filler of Comparative Example 1 was 84.9 g (849 parts) of AA-18, 30.9 g (309 parts) of AA-3, and 12.9 g of AA-04. A cured resin was obtained in the same manner as in Comparative Example 1 except that (129 parts) was used.

[Preparation of cured copper foil resin sheet sample]
The obtained resin sheet cured product with double-sided copper foil was immersed in an etching solution of a 20% aqueous solution of sodium persulfate and treated until the copper foil was completely dissolved. After the copper foil removal was completed, the sheet-like cured product was sufficiently washed with water, and a sample dried at 120 ° C. for 4 hours was used as a copper foil-removed resin sheet cured product sample.

(Evaluation of thermal diffusivity)
A 10 mm square sample was cut out from the cured copper foil resin sheet sample, and the thermal diffusivity in the thickness direction of the cured resin sheet at 25 ° C. was removed by flash method using Nanoflash LFA447 manufactured by NETZSCH. It was measured.

(Evaluation of specific heat)
Several pieces of about 3 mm square samples were cut out from the copper foil-removed resin sheet cured sample so that the weight was 20 to 40 mg. Using a differential scanning calorimeter (Pyris-1 manufactured by PERKINELMER), the specific heat of the cured resin sheet after removing the copper foil at 25 ° C. was measured using sapphire as a reference sample.

(Evaluation of density)
The density of the cured resin sheet after removing the copper foil at 25 ° C. was measured using an Archimedes method density measuring device (SD-200L manufactured by Alpha Mirage).

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

λ = α · Cp · ρ (Formula 3)

λ: thermal conductivity (W / m · K), α: thermal diffusivity (mm ² / s)
Cp: specific heat (J / kg · K), ρ: density (g / cm ³ )

[Measurement of storage modulus and glass transition temperature]
A sample having a length of 33 mm and a width of 5 mm was cut out from the cured product of the copper foil-removed resin sheet, and the temperature dependence of the storage elastic modulus at 30 to 350 ° C. was measured in a tensile mode using SOLIDS ANALYZER II manufactured by Rheometric Scientific.
The peak temperature of tan δ was read as the glass transition temperature (Tg) in the dynamic viscoelasticity measurement. The test conditions were a heating rate of 5 ° C./min, a frequency of 10 Hz, a span distance of 21 mm, a tensile strain of 0.1%, and an air atmosphere.

(result)
From the results of Example 1 and Comparative Example 1, it has been clarified that when boron nitride is the main component of the inorganic filler, the thermal conductivity increases by 30% when the crosslink density of the matrix resin is about 13 times.
On the other hand, from the results of Comparative Example 2 and Comparative Example 3, when aluminum oxide was the main component of the inorganic filler, the improvement was only 10% even when the cross-linking density of the matrix resin was about 12 times. Since the glass transition temperature of Comparative Example 2 is lower by 45 ° C. than that of Example 1, it is considered that the adsorbed water of aluminum oxide inhibited the curing reaction and the crosslinking density was lowered.

[Manufacture of structure]
<Examples 2 to 12, Comparative Examples 4 to 5>
According to the procedure of Example 1, the materials shown in Table 2 were blended to obtain a cured resin. In addition, the hardening accelerator, the coupling agent, and the dispersing agent which are materials not described in Table 2 were blended in the same amounts as in Example 1.

〔Evaluation method〕
About the resin composition obtained above, it carried out similarly to the above, and measured the heat conductivity and glass transition temperature of the resin cured material. Further, the flexibility of the resin composition and the dielectric breakdown voltage of the cured resin formed by the resin composition were evaluated as follows. The results are shown in Table 2.

(Flexibility evaluation)
The produced B-stage sheet was cut into a length of 100 mm and a width of 10 mm, and the PET film on the surface was removed. The sample is applied to a jig made of aluminum and having a diameter of 20 to 140 mm and 20 mm increments stacked in multiple stages, and the minimum diameter that can be bent without breaking at 25 ° C. is 20 mm. In the case of 60 mm, it was evaluated as ◯, in the case of 80 mm or 100 mm, Δ in the practical limit, and in the case of 120 mm or more, x was evaluated as inappropriate.

(Dielectric breakdown voltage measurement)
A copper foil-removed resin sheet cured product sample was placed in a metal container, and an electrode (aluminum flat round electrode, diameter 25 mm, contact surface 20 mm) was placed in a sheet shape. Subsequently, Fluorinert insulating oil (FC-40 manufactured by 3M) was poured, and the dielectric breakdown voltage at 25 ° C. was measured using DAC-6032C manufactured by Sokenden Co., Ltd. while immersed in Fluorinert. The measurement conditions were a constant speed boost with a frequency of 50 Hz and a boost speed of 500 V / sec.

Examples 1-12 have the softness | flexibility excellent before hardening compared with Comparative Examples 1-5, and have shown high heat conductivity after hardening.
When confirmed in more detail, in the comparison of Example 1, Example 12 and Comparative Example 4, TPM-Ep, PhN-Ep, and BisAF-Ep have substantially the same hydroxyl group equivalent and the same amount. Thermal conductivity is greatly different. TPM-Ep is a resin skeleton that has a branched structure at the reactive end in the repeating unit and has a high crosslink density. Therefore, compared with PhN-Ep and bifunctional Bis-AF having a polyfunctional and linear structure, It can be said that the effect of improving the conductivity has appeared.
The results of Comparative Examples 1, 4, and 5 are considered to be due to the lower thermal conductivity compared to Example 1 and the low crosslink density of the epoxy resin composition.

  Furthermore, from the comparison of the results of Examples 1 to 5, the flexibility is improved by adding the bifunctional epoxy resin or the mononuclear dihydric phenol compound, and both the bifunctional epoxy resin and the mononuclear dihydric phenol compound are combined. And sufficient flexibility. On the other hand, it was considered that the addition of the bifunctional epoxy resin or the mononuclear dihydric phenol compound lowered the crosslinking density, and the thermal conductivity was lower than that in Example 1. In addition, since RCN used in Examples 6 and 7 contains a monomer, it is considered that the same softening effect as in Examples 4 and 5 was obtained.

From the results of Examples 8 to 10, it can be said that boron nitride can be reduced and the proportion of aluminum oxide can be increased to 34% by volume of the inorganic filler as compared with Examples 1, 6, and 7.
From the results of Example 11, it can be said that the heat conductivity of the cured resin can be improved when aluminum nitride having a higher thermal conductivity than aluminum oxide is used as the small particle size filler as compared with Example 1.

102: Power semiconductor chip, 104: Solder layer, 106: Metal plate for wiring (lead frame, bus bar), 107: Spacer, 108: Sealing resin, 110: Resin sheet with metal foil, 112: Resin sheet or cured resin Sheet: 114: Metal foil support, 115: Structure, 116: Circuit processed metal foil, 118: Metal plate, 120: Heat sink, 122: Thermal conductive material (heat radiation grease, heat radiation sheet, phase change sheet), 130: LED individual parts, 132: housing, 140: LED bulb housing, 142: LED drive circuit, 144: lens, 146: base

Claims (15)

Containing an epoxy resin containing a polyfunctional epoxy resin, a curing agent containing a novolac resin having a structural unit represented by the following general formula (I), and an inorganic filler containing nitride particles,
In the inorganic filler, containing 50% by volume to 95% by volume of the nitride particles,
A resin composition in which the nitride particles are boron nitride.

In general formula (I), R ¹ and R ² each independently represent a hydrogen atom or a methyl group, m represents an average value of 1.5 to 2.5, and n represents an average value of 1 to 15.   The resin composition according to claim 1, wherein the boron nitride has an average particle size of 20 μm to 60 μm.   The resin composition of Claim 1 or Claim 2 which contains the said inorganic filler 50 volume%-85 volume%.   The resin composition according to any one of claims 1 to 3, wherein the polyfunctional epoxy resin is contained in an amount of 20% by mass or more in all epoxy resins.   The said polyfunctional epoxy resin is at least 1 type selected from a triphenylmethane type epoxy resin, a tetraphenylethane type epoxy resin, a dihydroxybenzene novolak type epoxy resin, and a glycidylamine type epoxy resin. The resin composition according to claim 1.   The epoxy resin further contains a liquid or semi-solid epoxy resin, and the liquid or semi-solid epoxy resin is bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol A type and F type epoxy resin, bisphenol F novolac type epoxy resin. The resin composition according to any one of claims 1 to 5, which is at least one selected from naphthalenediol type epoxy resins and glycidylamine type epoxy resins.   The resin composition as described in any one of Claims 1-6 in which the said hardening | curing agent contains 20 mass%-70 mass% of at least 1 type selected from mononuclear dihydroxybenzene. Further, the resin composition according to any one of claims 1 to 7 containing a coupling agent. Furthermore, the resin composition as described in any one of Claims 1-8 containing a dispersing agent. A resin sheet which is an uncured body or a semi-cured body of the resin composition according to any one of claims 1 to 9 . The resin sheet with metal foil which has the resin sheet of Claim 10 , and metal foil. A cured resin sheet, which is a cured product of the resin composition according to any one of claims 1 to 9 . The cured resin sheet according to claim 12 , wherein the thermal conductivity in the thickness direction is 10 W / m · K or more. The resin sheet according to claim 10 or the cured resin sheet according to claim 12 or 13 , and a metal plate provided in contact with one side or both sides of the resin sheet or the cured resin sheet. Structure. The resin sheet according to claim 10 , the resin sheet with metal foil according to claim 11 , the cured resin sheet according to claim 12 or claim 13 , or a power source having the structure according to claim 14 or Semiconductor device for light source.