JP2016138194A - Resin composition, resin sheet, and resin sheet cured product - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resin composition excellent in thermal conductivity and adhesive strength (shear strength), a resin sheet, and a resin sheet cured product.SOLUTION: The resin composition contains a resin, a curing agent for the resin, a dispersant having a weight average molecular weight of 100,000 or less, and boron nitride having a specific surface area of 3 m/g or less. The resin is one of an epoxy resin, a phenoxy resin, an acrylic resin, a polyamide resin, a polycarbonate resin, a bismaleimide resin, and a polyimide resin. The content of the dispersant is 1-70 pts.mass based on 100 pts.mass of the resin.SELECTED DRAWING: None

Description

  The present invention relates to a resin composition, a resin sheet, and a cured resin sheet.

  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, and is 3.8 W / m · K in the xenon flash method and 4.5 W / m in the temperature wave thermal analysis method. -It is supposed that the thermal conductivity of K can be achieved (for example, refer to 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 / m · K 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.

  Patent Document 1 has a configuration including alumina, boron nitride, and a thermosetting resin, and an elastomer is mixed with the resin to soften the resin before and after curing. Further, the thermal conductivity is 10 W / m · K or more, and the shear strength between copper is 5 MPa. Patent Document 2 is a resin sheet having an increased thermal conductivity in the in-plane direction. It is important to orient the particles of flakes in the plane, and particles having a large aspect ratio are used. Further, since adhesion is important, a matrix resin mainly composed of rubber is used.

International Publication No. 2013/035354 International Publication No. 2013/118849 JP 2011-37919 A JP 2013-39834 A

  However, the problem of Patent Document 1 is that the shear strength is not as high as 5 MPa and the insulation is not as high as 4 kV / 100 μm, and the problem of Patent Document 2 is that the in-plane thermal conductivity is at least 18 W / m · K or more. Although it is high, the thermal conductivity in the surface thickness direction is about 2 W / m · K, and is low as a problem.

  As described above, in the cured resin described in Patent Documents 1 to 4, it is difficult to achieve both high levels of thermal conductivity, insulation, and adhesive strength. In particular, when boron nitride having a large particle diameter is used in order to increase the thermal conductivity, the thermal conductivity is improved, but the dielectric breakdown strength and the adhesive strength (shear strength) may be lowered.

  An object of the present invention is to provide a resin composition, a resin sheet, and a cured resin sheet that are excellent in thermal conductivity and adhesive strength (shear strength).

The present invention is a resin composition comprising a resin, a curing agent for the resin, a dispersant having a weight average molecular weight of 100,000 or less, and a boron nitride having a specific surface area of 3 m ² / g or less. Is any one of an epoxy resin, a phenoxy resin, an acrylic resin, a polyamide resin, a polycarbonate resin, a bismaleimide resin, and a polyimide resin, and the content of the dispersant is 1 to 70 parts by mass with respect to 100 parts by mass of the resin. It is related with the resin composition which is. The resin composition of the present invention is excellent in thermal conductivity and adhesive strength (shear strength).
Moreover, this invention relates to the resin composition whose boron nitride has a hydroxyl group on the surface in the above.
Moreover, this invention relates to the resin composition whose particle diameter of a boron nitride is 5-100 micrometers in the above.
Moreover, the present invention is a resin sheet having the first resin layer and the second resin layer laminated on the first resin layer in the above, wherein the first resin layer and the first resin layer The second resin layer relates to a resin sheet made of a resin composition.
Moreover, this invention relates to the resin sheet hardened | cured material formed by heat-processing a resin sheet in the above.
Moreover, this invention relates to the resin sheet hardened | cured material whose thermal conductivity is 2-20 W / m * K and whose shear strength is 6 Mpa or more in the above.

  According to the present invention, a resin composition, a resin sheet, and a cured resin sheet that are excellent in thermal conductivity and adhesive strength (shear strength) are provided.

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.
Hereinafter, embodiments of the present invention will be described in detail.

<Resin composition>
The resin composition of this embodiment is a resin composition containing a resin, a curing agent for the resin, a dispersant having a weight average molecular weight of 100,000 or less, and boron nitride having a specific surface area of 3 m ² / g or less. The resin is one of an epoxy resin, a phenoxy resin, an acrylic resin, a polyamide resin, a polycarbonate resin, a bismaleimide resin and a polyimide resin, and the content of the dispersant is 100 parts by mass of the resin, 1 to 70 parts by mass. In particular, from the viewpoint of adhesiveness, an epoxy resin is preferable as the resin.

(Resin: Monomer)
The resin composition of this embodiment contains at least 1 type 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 embodiment include an epoxy resin, a phenoxy resin, an acrylic resin, a polyimide resin, a polyamide resin, a polycarbonate resin, and a bismaleimide resin. The phenoxy resin and epoxy resin used in the present embodiment may be a high molecular weight resin having a weight average molecular weight of 10,000 or more and 100,000 or less.

  In the resin composition of this embodiment, an epoxy resin that can suppress phonon scattering, which is a heat conductive medium, can form a higher order structure, and can achieve high heat conductivity may be used. . Forming a highly ordered high order structure derived from covalent bonds or intermolecular forces in the cured resin by forming a cured resin with a novolak resin having a specific structural unit by using an epoxy resin Can do.

  The resin composition which is the first aspect of the present embodiment contains an epoxy resin, its curing agent, and boron nitride and a dispersant as a filler. In addition, it is preferable that the said dispersing agent contains an amino group. Further, the dispersant may be mainly composed of an acrylic resin and phase-separated from the epoxy resin. The resin composition having such a configuration is excellent in adhesion to the metal plate and the heat radiating plate before curing. Moreover, the resin composition which is excellent in thermal conductivity, adhesiveness, and insulation can be comprised by thermosetting.

  The epoxy resin used in this embodiment is not particularly limited as long as it cures and exhibits an adhesive action, but it is preferably bifunctional or higher and an epoxy equivalent of 400 g / eq or lower. In particular, it may be a crystalline form in which the viscosity at the time of melting tends to be low, or a polyfunctional one that can increase the Tg.

  When the resin composition of this embodiment contains an epoxy resin, the epoxy resin has a trifunctional or higher functional first structure having a structure in which two naphthalene rings are included in the molecule and the two naphthalene rings are connected by an alkylene chain. The epoxy resin may be contained. Moreover, when the resin composition of this embodiment 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 composition of this embodiment 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 this embodiment 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).

If the 2nd epoxy resin which concerns on this embodiment is a bifunctional thing which has a mesogen structure in a molecule | numerator, there will be no limitation in particular.
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 embodiment, 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. A higher order structure can be formed. The higher order structure means a state in which molecules are arranged by a mesogenic structure after the resin composition is cured.

  The second epoxy resin according to this embodiment 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 embodiment can form a higher order structure in the cured resin when the epoxy resin reacts with the curing agent to form a cured resin. In addition, the higher order structure as used in this embodiment means the state in which the molecule | numerator is orientated after hardening of a resin composition, 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) esters 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 which consists of a resin composition of this embodiment, 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 made of the resin composition. Specifically, the use of a liquid epoxy resin may improve the flexibility of the resin sheet made of the resin composition 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.

  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 or lamination of the resin sheet made of the resin composition of the present embodiment The fluidity of time can be further improved.

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

  In the resin composition of the present embodiment, when the first epoxy resin and the second epoxy resin are used in combination as the resin, the content ratio (mass basis) of the first epoxy resin and the second epoxy resin is: It is preferably 25:75 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 first 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 (mass basis) of 2 with the epoxy resin is preferably 25:75 to 85:15, more preferably 30:70 to 80:20, and 35:65 to 75:25. More preferably.
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 composition of this embodiment contains an epoxy resin, the resin composition of this embodiment contains a curing agent.
The curing agent that can be used in the present embodiment is not particularly limited as long as it is a compound that can cure with an epoxy resin. Specific examples of the curing agent in the present embodiment 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.
Moreover, it is preferable to use a phenol novolac-based curing agent. It is preferable because the molecular weight between cross-linking points is small, the glass transition temperature can be increased, the weight loss at high temperatures is small, and the pot life can be increased.

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. 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 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 to 20% by mass. And j is preferably 80 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 to 10% by mass. , J is more preferably 90 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 novolak resin can be obtained by conversion from a calibration curve using standard polystyrene by gel permeation chromatography (GPC).

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, 5-60 mass% is preferable, 10-55 mass% is more preferable, 15-50 mass% is 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 composition of this embodiment contains a hardening | curing agent, it does not restrict | limit especially as a total content rate of the hardening | curing agent in a resin composition. From the viewpoint of thermal conductivity and adhesiveness, the total content of the curing agent is preferably 1 to 10% by mass, and 1.2 to 8% by mass in the total solid content of the resin composition. Is more preferable, and it is still more preferable that it is 1.4-7 mass%.

  When the resin composition of this embodiment contains a specific novolak resin as a curing agent, the content of the specific novolak resin in the resin composition is not particularly limited. The content of the specific novolak resin is preferably 0.3 to 10% by mass in the total solid content mass of the resin composition from the viewpoints of thermal conductivity and adhesiveness, and from the viewpoint of thermal conductivity, it is preferably set to 0.001%. More preferably, it is 5-8 mass%, and it is still more preferable that it is 0.7-7 mass%.

  The resin composition of the present embodiment may contain at least one other novolac resin not containing the structural unit represented by the general formula (IV), in addition to the specific novolac resin, from the viewpoints of insulation and heat resistance. preferable. 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 composition of this embodiment further contains other curing agents other than the specific novolak resin, the content of other curing agents 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 composition of this embodiment contains a hardening | curing agent and contains an epoxy resin as resin, content of the hardening | curing agent in a resin composition is 0.8-1.2 on an equivalent basis with respect to an epoxy resin. Is preferable, and 0.9 to 1.1 is more preferable. 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.

(Dispersant)
As a dispersing agent used for the resin composition of this embodiment, a weight average molecular weight is 100,000 or less from a viewpoint of adhesiveness or thermal conductivity, and it is more preferable that it is 20,000-90,000. The weight average molecular weight can be obtained by, for example, converting from a calibration curve using standard polystyrene by gel permeation chromatography (GPC).
Content of the dispersing agent used with the resin composition of this embodiment is 1-20 mass parts with respect to 100 mass parts of said resin from an adhesiveness or a heat conductive viewpoint, and is 2-20 mass parts. More preferably.
Examples of the dispersant include, but are not limited to, polymers, silicon, and those obtained by chemically modifying these compounds. The filler dispersant used in the present embodiment is preferably a thermoplastic resin such as acrylic rubber or silicon rubber. Moreover, it is preferable that a dispersing agent contains an amino group. In particular, the dispersant preferably contains a carboxyl group in the side chain and has an amino group with a structural unit of 20% or less from the viewpoint of improving thermal conductivity and adhesiveness.
Further, the dispersant may be mainly composed of an acrylic resin and phase-separated from an epoxy resin or the like. In addition, as content of the acrylic resin in a dispersing agent, 20-100 mass% is preferable.

In the present embodiment, boron nitride and a filler other than boron nitride may be used in combination, and the filler dispersant used is preferably a thermoplastic resin such as acrylic rubber or silicon rubber. In particular, a dispersant containing an acrylic resin as a main component and phase-separating from the resin is preferable.
As a filler dispersant, in the state of a varnish containing a solvent, it is possible to prevent problems such as precipitation and aggregation of boron nitride, and to reduce macro unevenness and variation in characteristics of the resin composition when B-staged. . When the C stage is used, it is possible to increase the breaking strain of the resin due to the plasticizing effect on the epoxy resin. On the other hand, a phenoxy resin or a high molecular weight epoxy resin can reduce the elastic modulus and increase the strain. However, if the dispersant becomes compatible with the epoxy resin, the thermal conductivity may be impaired, and the moldability may be affected due to the high viscosity. Therefore, the dispersant is preferably phase-separated from phenoxy resin, epoxy resin, or the like.

(Filler: Boron nitride)
In the resin composition of this embodiment, boron nitride is contained as a filler, but fillers other than boron nitride may be contained. In addition, in this embodiment, a filler represents an inorganic filler.
The material of the inorganic filler is not particularly limited as long as it is an inorganic compound particle having insulating properties. The material of the inorganic filler is preferably one having high thermal conductivity and volume resistivity.
Inorganic fillers include aluminum hydroxide, magnesium hydroxide, calcium silicate, magnesium oxide, aluminum nitride, silicon nitride, crystalline silica, amorphous silica, aluminum oxide (alumina), aluminum oxide hydrate, talc, Examples thereof include inorganic compound particles such as mica and barium sulfate. An inorganic filler may be used individually by 1 type, or may be used in combination of 2 or more type. From the viewpoints of thermal conductivity and insulation, aluminum oxide, aluminum nitride, and aluminum hydroxide are preferable.
The boron nitride used in the present embodiment has a specific surface area of 3 m ² / g or less. Furthermore, the specific surface area of the boron nitride is preferably 0.1~2.8m ² / g, more preferably 1~2.5m ² / g. When the specific surface area is 3 m ² / g or less, there are effects such as improvement in adhesive strength (shear strength). In the present embodiment, the specific surface area of an inorganic filler such as boron nitride can be measured from the nitrogen adsorption capacity in accordance with JIS Z8830-2013, and generally refers to the BET specific surface area.

The boron nitride used in the present embodiment preferably has a hydroxyl group on the surface. By having a hydroxyl group on the surface, a cured resin product is preferable because effects such as improved fluidity of the resin and improved adhesive strength can be obtained. Moreover, it is possible to quantify the amount of hydroxyl groups on the surface of boron nitride using infrared spectroscopy. The apparatus used was a FT-IR FTS6000 model manufactured by Bio-Rad Laboratories, and the number of integrations was 256 using the diffuse reflection method. The amount of the hydroxyl group was normalized by the peak intensity of BN bending vibration near 820 cm ⁻¹ as measured by infrared spectroscopy, and 0.01 or more was regarded as having a hydroxyl group and less than 0.01.

The content of boron nitride is preferably 20 to 400 parts by volume with respect to 100 parts by volume of the resin solid content from the viewpoint of thermal conductivity and adhesiveness, and more preferably 40 to 300 parts by volume. preferable.
In the present embodiment, the blending of the inorganic filler such as boron nitride has one purpose to impart thermal conductivity and insulating properties. If it is less than 20 parts by volume, the thermal conductivity and insulation properties are insufficient, and if it exceeds 400 parts by volume, the molding becomes difficult and voids are likely to enter, so that the insulation properties may be insufficient. From such a background, the inorganic filler is required to be added in such an amount that does not impair the moldability while ensuring the thermal conductivity.
Further, the particle diameter of boron nitride used in the present embodiment is preferably 5 to 100 μm from the viewpoint of thermal conductivity and adhesiveness, more preferably 5 to 80 μm, and 10 to 80 μm. More preferably. Moreover, when it exceeds 100 micrometers, there exists a possibility of impairing insulation, and there exists a possibility that thermal conductivity may become inadequate when it is less than 5 micrometers. In addition, the said particle diameter is a primary particle diameter (average particle diameter), for example, can be calculated | required from the peak which exists in the particle size distribution measurement measured using a laser diffraction method.
Moreover, in this embodiment, it exists in the tendency for heat conductivity to become it low that the ratio of the particle | grains which have a particle diameter of 20-100 micrometers occupied in an inorganic filler is less than 30 volume% in the resin composition except a solvent. On the other hand, when the proportion of particles having a particle diameter of 20 to 100 μm in the inorganic filler exceeds 80% by volume, the adhesiveness tends to decrease. Therefore, the inorganic filler used in the present embodiment has a ratio of particles having a particle diameter of 20 to 100 μm in the inorganic filler in the resin composition excluding the solvent when measured by a laser diffraction method. %, More preferably 36 to 80% by volume, and still more preferably 39 to 75% by volume.

(Other ingredients)
The resin composition of the present embodiment can contain other components as needed in addition to the above components. Examples of other components include a curing accelerator and a silane coupling agent.

(Curing accelerator)
Examples of the curing accelerator include imidazole, triphenylphosphine, derivatives obtained by introducing side chains into these compounds, and the like. If necessary when curing the thermosetting resin, a curing accelerating component can be included without any particular limitation.

(Silane coupling agent)
The resin composition may further contain at least one silane coupling agent. By including the silane coupling agent, the bondability between the resin component including the epoxy resin monomer and the novolac resin and the filler can be further improved, and higher thermal conductivity and stronger adhesiveness can be achieved.

  The silane coupling agent is not particularly limited as long as it is a compound having a functional group that binds to a resin component and a functional group that binds to a filler, and can be appropriately selected from commonly used silane coupling agents. . Examples of the functional group bonded to the filler include trialkoxysilyl groups such as a trimethoxysilyl group and a triethoxysilyl group. 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 aminophenyl group.

  Specific examples of silane coupling agents include 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, and 2- (3,4-epoxycyclohexyl). Ethyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3- (2-aminoethyl) aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3- (2-aminoethyl) aminopropyltrimethoxysilane, 3 -Phenylaminopropyltrimethoxysilane, 3-mercaptotriethoxysilane, 3-ureidopropyltriethoxysilane and the like can be mentioned. Moreover, the silane coupling agent oligomer (made by Hitachi Chemical Techno Service Co., Ltd.) represented by SC-6000KS2 can also be used. These silane coupling agents can be used alone or in combination of two or more.

  When the resin composition contains a silane coupling agent, the content of the silane coupling agent in the resin composition is not particularly limited. The content of the silane coupling agent is preferably 0.02% by mass or more and 0.83% by mass or less in the total solid content mass of the resin composition from the viewpoint of thermal conductivity, and is 0.04% by mass. More preferably, it is 0.42 mass% or less.

  Moreover, when a resin composition contains a silane coupling agent, the content rate of the silane coupling agent with respect to content of a filler is 0.02 mass% or more and 1 mass% from a viewpoint of thermal conductivity, insulation, and moldability. From the viewpoint of higher thermal conductivity, it is more preferably 0.05% by mass or more and 0.8% by mass or less.

(Production method of resin composition)
As a method for producing a resin composition, a commonly used method for producing a resin composition can be used without particular limitation. As a method for mixing a resin (monomer), a curing agent, a dispersant, a filler such as boron nitride, etc., a normal agitator, a raking machine, a three-roller, a ball mill or the like can be appropriately combined. . Further, dispersion or dissolution can be performed by adding an appropriate organic solvent.

  Specifically, for example, an epoxy resin, a novolak resin, a filler (boron nitride, alumina), a dispersant containing an acrylic resin, and a silane coupling agent added as necessary are dissolved or dispersed in an appropriate organic solvent. Moreover, a resin composition can be obtained by mixing other components, such as a hardening accelerator, as needed.

  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 resin sheet manufacturing method described later. 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, when the organic solvent is completely 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 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-propanol, and cyclohexanol, ketone solvents such as methyl ethyl ketone, cyclohexanone, and cyclopentanone, dimethylformamide, dimethylacetamide, and the like. And nitrogen-containing solvents. The organic solvents can be used alone or in combination of two or more.

<Resin sheet>
The resin sheet preferably further has a support on at least one surface, and more preferably has a support on both surfaces. Thereby, the resin sheet can be protected from adhesion and impact of foreign matter on the adhesive surface of the resin sheet from the external environment. That is, the support functions as a protective film. The support is preferably peeled off when used.

  Examples of the support include plastic films such as a polytetrafluoroethylene film, a polyethylene terephthalate 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. Moreover, metal foils, such as copper foil and aluminum foil; Metal plates, such as an aluminum plate, etc. can also be used as said support body.

  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 or more and 150 μm or less, and more preferably 25 μm or more and 110 μm or less from the viewpoint 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 or more and 400 μm or less, and is preferably 18 μm or more and 300 μm or less from the viewpoint of handleability as a roll foil.

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 this embodiment is interposed between members such as a metal plate, a heat radiating plate, and an adherend, these members are highly likely to be bonded without causing voids at the bonding interface. Become. If the thermal conductivity is high, there is no need to fill the inorganic filler with a high amount in the resin sheet. Therefore, the increase in the elastic modulus of the resin sheet and the improvement in the elongation can be achieved. Can 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.

The resin sheet of the present embodiment 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. And a second resin layer containing other components such as a curing agent used as necessary.
For example, the resin sheet of the present embodiment 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 this embodiment may have a configuration in which a metal foil is provided on one surface and a plastic film is provided on a surface opposite to the surface having the metal foil.
Further, the resin sheet of the present embodiment 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 laminated on the first resin layer. It is a laminate having an inorganic 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, It is preferable to further have a protective film such as a plastic film on the surface. 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 to 250 μm using the resin composition containing the components constituting the resin sheet of the present embodiment. The sheet can be appropriately selected from commonly used sheet manufacturing methods. Specifically, as a method for producing a resin sheet, a resin composition containing an organic solvent together with components constituting the resin sheet of the present embodiment is applied on a support so as to have a desired average thickness. Examples thereof include a method of forming a resin layer by forming a layer and drying the formed resin composition layer to remove at least a part of the organic solvent.

  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.

  Furthermore, the method of heat-pressing the resin layer of the resin sheet 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 thickness of the resin composition layer of the resin sheet 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 embodiment is a laminated body, it is preferable that the first resin layer and the second resin layer are manufactured to overlap each other. 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 embodiment 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 components constituting the resin sheet of the present embodiment. It can be formed by drying the layer to remove at least a portion of the organic solvent. The second resin layer is formed by, for example, 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 embodiment. It can be formed by drying the composition 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 with the resin composition containing the components constituting the resin sheet of the present embodiment, the surface of the laminate before the heat and pressure treatment is uneven due to the inorganic filler and may not be smooth. . The thickness of the resin sheet of the present embodiment obtained by subjecting such a laminate to heat and pressure treatment may not be consistent with the sum of the thicknesses of the resin layers, and may be reduced. 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.

<Hardened resin sheet>
The cured resin sheet of the present embodiment is a heat-treated product of the resin sheet of the present embodiment. That is, the cured resin sheet of the present embodiment is formed by curing the resin composition constituting the resin sheet by heat-treating the resin sheet of the present embodiment. 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 embodiment preferably has a thermal conductivity of 2 to 20 W / m · K, more preferably 5 to 20 W / m · K, and 9 to 15 W / m · K. More preferably. Further, the shear strength is preferably 6 MPa or more, and more preferably 9 MPa or more. When the shear strength is 6 MPa or more, there is an advantage that the adhesive strength can be improved when adherends having different linear expansion coefficients are attached.
The thermal conductivity is measured by, for example, measuring the thermal diffusivity using a NETZSCH Nanoflash LFA447 model, the measured thermal diffusivity, the density measured by the Archimedes method, and the specific heat measured by DSC (differential calorimetry). Calculated from product.
Moreover, shear strength can be calculated | required, for example using Shimadzu Corporation AGC-100 type | mold.

Further, the cured resin sheet of this embodiment preferably further has a storage elastic modulus of 30 GPa or less, and preferably has a linear expansion coefficient of 8 to 25 ppm / ° C. There exists an advantage which can improve the adhesive strength when adhere | attaching the adherend from which a linear expansion coefficient differs by making the storage elastic modulus and linear expansion coefficient of the resin sheet hardened | cured material of this embodiment into a predetermined range.
The storage elastic modulus can be measured using a dynamic viscoelasticity measuring device (DMA) or the like. The linear expansion coefficient can be measured using a linear expansion coefficient measuring device (TMA) or the like.

The cured resin sheet of this embodiment has a tensile modulus of 0.1 GPa to 30 GPa, preferably 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 more preferably 0.18% to 0.60%. .
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 cured resin sheet of this embodiment into a predetermined range.
In addition, in order to make the tensile elastic modulus and tensile fracture strain of the cured resin sheet (resin sheet in the C stage state) of the present embodiment within a predetermined range, a resin, an inorganic filler, and a curing agent used as necessary This is achieved by appropriately selecting the type and content of other components. In this embodiment, 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 is reduced, but the breaking strength is increased. 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.

  In the cured resin sheet of the present embodiment, 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 embodiment. For example, the resin sheet of this embodiment 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 steps of heating at 100 ° C. to 160 ° C. and 160 ° C. to 250 ° C. with respect to the resin sheet of the present embodiment. More preferably, heat 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.

(Resin sheet laminate)
The resin sheet laminated body of this embodiment has the resin sheet of this embodiment, and the metal plate or heat sink arrange | positioned on the at least one surface of the said resin sheet. The details of the resin sheet of this embodiment constituting the resin sheet laminate of this embodiment 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 embodiment, a metal plate or a heat sink is arrange | positioned on the at least one surface of the resin sheet of this embodiment, Preferably it arrange | positions on both surfaces.

  The resin sheet laminated body of this embodiment 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 embodiment, 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 embodiment has a metal plate or a heat radiating plate on one surface of the resin sheet, and an adherend on a surface opposite to the surface on which the metal plate or the heat radiating plate is arranged. You may have. 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 embodiment 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. It may be.

(Production method of cured resin sheet laminate)
The cured resin sheet laminate of the present embodiment is a heat-treated product of the resin sheet laminate. The method for producing a cured resin sheet laminate according to the present embodiment 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 method for producing the cured resin sheet laminate of the present embodiment, the resin sheet of the present embodiment 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.

  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.
(Filler)
Table 1 summarizes the specific surface area and primary particle diameter of the boron nitride filler.
HP: Mizushima Alloy Iron Co., Ltd., product name HP40
MP: Product name Agglomerates, manufactured by 3M Japan
RP: manufactured by Denki Kagaku Kogyo Co., Ltd., product name SGPS
The specific surface area (BET specific surface area) of the boron nitride filler is measured from the nitrogen adsorption capacity according to JIS Z8830-2013, and the primary particle diameter is a laser diffraction particle size distribution meter Master Sizer Microplus (trade name, manufactured by Malvern). Then, the particle size distribution was measured and obtained as a refractive index of 2.2.

(Hydroxyl content of boron nitride)
Infrared spectroscopy was used to quantify the hydroxyl groups on the surface of boron nitride. The apparatus used was a FT-IR FTS6000 model manufactured by Bio-Rad Laboratories, and the number of integrations was 256 using the diffuse reflection method. The amount of the hydroxyl group is normalized by the peak intensity (hydroxyl group peak height) of the BN bending vibration at 820 cm ⁻¹ as measured by infrared spectroscopy, and is expressed by the specific surface area as shown in the formula (1). The amount of hydroxyl group was determined by dividing. The results are shown in Table 1.
Hydroxyl amount = (Hydroxyl peak height) / ((BN bending height) × (specific surface area)) (1)

(Alumina filler)
AA-18: Aluminum oxide particles, product name: AA-18, manufactured by Sumitomo Chemical Co., Ltd., volume average particle diameter 18 μm
AA-3: aluminum oxide particles, product name: AA-3, manufactured by Sumitomo Chemical Co., Ltd., volume average particle diameter: 3 μm
AA-04: aluminum oxide particles, product name: AA-04, manufactured by 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)
-PNAP: Triphenylmethane type epoxy resin, model number EPPN-502H, manufactured by Nippon Kayaku Co., Ltd.-BIS-A / F: Bisphenol A / F mixed type epoxy resin, model number ZX-1059, manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.

(Additive)
TPP: Triphenylphosphine (curing accelerator, manufactured by Wako Pure Chemical Industries, Ltd.)
Coupling agent: KBM-573 (N-phenyl-3-aminopropyltrimethoxysilane, manufactured by Shin-Etsu Chemical Co., Ltd.)

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

(Dispersant)
R1: Weight average molecular weight 25000, manufactured by Hitachi Chemical Co., Ltd., acrylic resin content 43% by mass
R2: weight average molecular weight 81000, manufactured by Hitachi Chemical Co., Ltd., acrylic resin content 36% by mass
R3: weight average molecular weight 130,000, manufactured by Hitachi Chemical Co., Ltd., acrylic resin content 25% by mass
The weight average molecular weight of the dispersant was converted from a calibration curve using standard polystyrene by gel permeation chromatography (GPC). The calibration curve was approximated by a cubic equation using a standard polystyrene 5 sample set (PStQuick MP-H, PStQuick B [trade name, manufactured by Tosoh Corporation]). The GPC conditions are shown below.
Apparatus: (Pump: L-2130 type [manufactured by Hitachi High-Technologies Corporation]),
(Detector: L-2490 type RI [manufactured by Hitachi High-Technologies Corporation]),
(Column oven: L-2350 [manufactured by Hitachi High-Technologies Corporation])
Column: Gelpack GL-R440 + Gelpack GL-R450 + Gelpack GL-R400M (three in total) (trade name, manufactured by Hitachi Chemical Co., Ltd.)
Column size: 10.7 mmI. D x 300mm
Eluent: Tetrahydrofuran Sample concentration: 10 mg / 2 mL
Injection volume: 200 μL
Flow rate: 2.05 mL / min Measurement temperature: 25 ° C

<Synthesis example>
(Curing agent; 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 by GPC of the obtained catechol resorcinol novolak resin (CRN). Moreover, the NMR spectrum of the obtained product (CRN) was measured, and it was confirmed that the structural unit represented by the general formula (IV) was included. The conditions for GPC measurement and NMR measurement are as follows.

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

<Example 1>
(AA-04, AA-3, AA-18) is 9.55 parts, (HP) 37.0 parts, (R1) is 2.26 parts, and (CRN) is 9 as an epoxy resin curing agent. .85 parts, 0.066 part of the coupling agent, and 38 parts of (CHN) were mixed. After confirming that it was uniform, (PNAP) 6.62 parts and (BIS-A / F) 6.70 parts and (TPP) 0.15 parts were further added and mixed as an epoxy resin, Ball milling was performed for 3 to 40 hours to obtain a resin layer forming coating solution 1 (also referred to as varnish) as a resin composition.

  Using a PET film (thickness 50 μm, Teijin DuPont Film Co., Ltd. A31) on which one side is release-treated as a support, a resin layer forming coating solution is formed so that the thickness is about 100 μm on the release-treated surface. The coating layer was formed by coating using a table coater (manufactured by Tester Sangyo Co., Ltd.). Drying was performed in a box oven at 100 ° C. for 5 minutes to form a resin sheet 1 (also referred to as an “A stage sheet”) having an A stage resin layer formed on a PET film.

  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 were performed to obtain a B-stage resin sheet 1 (also referred to as a B-stage sheet).

[Preparation of cured resin sheet laminate]
After peeling the PET film from both sides of the B-stage sheet obtained above, and stacking 35 μm thick copper foil (product name: CF-T9D-SV) on each side, Press processing was performed. 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. Furthermore, the cured resin sheet laminate 1 in a C-stage state in which copper foil was provided on both sides was obtained by sequentially heat-treating at 160 ° C. for 0.5 hours and 190 ° C. for 2 hours in a box-type oven.

<Example 2>
(AA-18, AA-3, AA-04) is 9.55 parts, (HP) 37.0 parts, (R1) is 4.52 parts, and (CRN) is 9 as an epoxy resin curing agent. .33 parts, 0.066 part of the coupling agent, and 38 parts of (CHN) were mixed. After confirming that it became uniform, (PNAP) 6.27 parts and (BIS-A / F) 6.35 parts and (TPP) 0.15 parts were further added and mixed as an epoxy resin. Is the same as in Example 1, the resin layer-forming coating solution 2, the A-stage resin sheet 2, the B-stage resin sheet 2, and the C-stage resin sheet laminate provided with copper foil on both sides. Each cured product 2 was obtained.

<Example 3>
Resin layer-forming coating solution 3, A-stage resin sheet 3, B-stage resin sheet, except that 37.0 parts of (MP) were used instead of (HP) 3. Each cured resin sheet laminate 3 in a C-stage state in which copper foil was provided on both sides was obtained.

<Example 4>
Resin layer-forming coating solution 4, A-stage resin sheet 3, B-stage resin sheet, except that 5.33 parts of (R2) were used instead of (R1) 3. Each cured resin sheet laminate 3 in a C-stage state in which copper foil was provided on both sides was obtained.

<Comparative Example 1>
(AA-04, AA-3, AA-18) are each 9.55 parts, (HP) 37.0 parts, (CRN) is 10.37 parts as a curing agent for epoxy resin, and a coupling agent is used. 0.066 parts and 38 parts of (CHN) were mixed. After confirming that it was uniform, (PNAP) 6.97 parts and (BIS-A / F) 7.05 parts and (TPP) 0.15 parts were further added and mixed as an epoxy resin, Ball milling was performed for 3 hours to 40 hours to obtain a resin layer forming coating solution C1 as a resin composition.

  For forming a resin layer such that a PET film (thickness 50 μm, manufactured by Teijin DuPont Films, product name: A31) on one side is used as a support, and the thickness is about 100 μm on the release side. The coating liquid was applied using a table coater (manufactured by Tester Sangyo Co., Ltd.) to form a coating layer. It was dried in a box oven at 100 ° C. for 5 minutes to form a resin sheet C1 (also referred to as an A stage sheet) on which a resin layer in an A stage state was formed on a PET film.

  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 treatment and bonding were performed to obtain a B-stage resin sheet C1 (also referred to as a B-stage sheet).

[Preparation of cured resin sheet laminate]
After peeling the PET film from both sides of the B-stage sheet obtained above, and stacking 35 μm thick copper foil (product name: CF-T9D-SV) on each side, Press processing was performed. 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. Furthermore, the resin sheet laminated body cured | curing material C1 of the C stage state by which copper foil was provided in both surfaces was obtained by heat-processing in a box-type oven for 0.5 hour at 160 degreeC, and 2 hours at 190 degreeC.

<Comparative example 2>
(AA-04, AA-3, AA-18) is 9.55 parts, (HP) 37.0 parts, (R1) is 9.03 parts, and (CRN) is used as an epoxy resin curing agent. 8.29 parts, 0.066 part of the coupling agent, and 38 parts of (CHN) were mixed. After confirming that it became uniform, (PNAP) 5.57 parts and (BIS-A / F) 5.64 parts and (TPP) 0.15 parts were further added and mixed as an epoxy resin. As in Comparative Example 1, the resin layer forming coating liquid C2, the A stage resin sheet C2, the B stage resin sheet C2, and the C stage resin sheet laminate provided with copper foil on both sides Cured products C2 were obtained.

<Comparative Example 3>
(AA-04, AA-3, AA-18) is 9.55 parts, (RP) is 37.0 parts, (R1) is 4.52 parts, and (CRN) is used as a curing agent for epoxy resin. 9.33 parts, 0.066 part of the coupling agent, and 38 parts of (CHN) were mixed. After confirming that it became uniform, (PNAP) 6.27 parts and (BIS-A / F) 6.35 parts and (TPP) 0.15 parts were further added and mixed as an epoxy resin. As in Comparative Example 1, the resin layer forming coating liquid C3, the A stage resin sheet C3, the B stage resin sheet C3, and the C stage resin sheet laminate provided with copper foil on both sides Each cured product C3 was obtained.

<Comparative example 4>
(AA-04, AA-3, AA-18) is 9.55 parts, (HP) 37.0 parts, (R3) is 7.88 parts, and (CRN) is used as a curing agent for epoxy resin. 9.33 parts, 0.066 part of the coupling agent, and 38 parts of (CHN) were mixed. After confirming that it became uniform, (PNAP) 6.27 parts and (BIS-A / F) 6.35 parts and (TPP) 0.15 parts were further added and mixed as an epoxy resin. As in Comparative Example 1, the resin layer forming coating solution C4, the A-stage resin sheet C4, the B-stage resin sheet C4, and the C-stage resin sheet laminate provided with copper foil on both sides Cured products C4 were 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 Table 2. In addition, the unit of the numerical value in the resin composition of Table 2 is a mass part.

(Thixotropy of resin layer forming coating solution)
The viscosity behavior of the resin composition raw material obtained in the above experiment was measured using MCR-301 (viscoelasticity measuring device) manufactured by Anton Paar. The measurement conditions were a temperature of 25 ° C., and a cone plate having a flat plate shape was used. The thixotropy is a natural logarithm obtained by dividing a viscosity difference at a shear rate of 100 (S ⁻¹ ) and 0.03 (S ⁻¹ ) by a shear rate, and a value obtained with the resin composition of Example 1 is 1. As calculated. As a measurement procedure, 1 ml of the resin composition is dropped on a metal plate in which circulating water at 25 ° C. has flowed, and the cone plate is lowered. After accelerating the shear rate of the cone plate from 0.03 (S ^-1 ) to 100 (S ^-1 ), the speed was reduced again to 0.03 (S ^-1 ), and the viscosity after 20 seconds when the speed was changed was It was measured.

(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 calorimeter).

(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 this with an AGC-100 type manufactured by 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).

As shown in Table 2, it can be seen that Examples 1 to 4 are excellent in both thermal conductivity and shear strength. On the other hand, compared with Examples 1-4, the comparative example 1 which does not contain a dispersing agent has low shear strength, and the comparative example 2 in which content of a dispersing agent exceeds 70 mass parts with respect to 100 mass parts of epoxy resins. (80 parts by mass), the thermal conductivity and shear strength both to low, and Comparative example specific surface area was used boron nitride of more than ^{3m 2 / g 3 (3.1m 2} / g) , the shear strength is low, Moreover, it turns out that the comparative example 4 (130,000) using the dispersing agent with a weight average molecular weight exceeding 100,000 is low in both thermal conductivity and shear strength.

Claims (6)

A resin composition comprising a resin, a curing agent for the resin, a dispersant having a weight average molecular weight of 100,000 or less, and a boron nitride having a specific surface area of 3 m ² / g or less, wherein the resin is an epoxy resin , A phenoxy resin, an acrylic resin, a polyamide resin, a polycarbonate resin, a bismaleimide resin, and a polyimide resin, and the content of the dispersant is 1 to 70 parts by mass with respect to 100 parts by mass of the resin object.   The resin composition according to claim 1, wherein the boron nitride has a hydroxyl group.   The resin composition according to claim 1 or 2, wherein the boron nitride has a particle size of 5 to 100 µm.   A resin sheet having a first resin layer and a second resin layer laminated on the first resin layer, wherein the first resin layer and the second resin layer are claims. The resin sheet which consists of a resin composition as described in any one of 1-3.   A cured resin sheet obtained by heat-treating the resin sheet according to claim 4.   The cured resin sheet according to claim 5, wherein the thermal conductivity is 2 to 20 W / m · K, and the shear strength is 6 MPa or more.