WO2012039324A1 - Heat-conductive resin composition, resin sheet, resin-clad metal foil, cured resin sheet, and heat-dissipating member - Google Patents

Abstract

A heat-conductive resin composition comprises an epoxy resin, an inorganic filler, and an elastomer having at least a structural unit represented by general formula (I) in the molecule. In formula (I), R¹, R² and R³ independently represent a linear or branched alkyl group or a hydrogen atom; R⁴ represents a linear or branched alkyl group; and n represents an arbitrary integer.

Description

Thermally conductive resin composition, resin sheet, metal foil with resin, cured resin sheet, and heat dissipation member

The present invention relates to a thermally conductive resin composition, a resin sheet, a metal foil with resin, a cured resin sheet, and a heat dissipation member.

In the field of semiconductors such as power transistors, thermistors, printed wiring boards and IC chips, and other fields of electrical and electronic components, epoxy resins and inorganic fillers are included as thermally conductive insulating materials constituting the heat dissipation member. Thermally conductive resin compositions are widely used. The thermal conductive resin composition is required to have excellent thermal conductivity. Therefore, in many cases, a method of adding an inorganic filler having a high thermal conductivity with a filling rate as high as possible is used for the preparation of the thermal conductive resin composition. For example, in Japanese Patent Application Laid-Open No. 2001-348488, a molded product having a thermal conductivity of 3 W / mK to 10 W / mK is obtained by setting the inorganic filler in the epoxy resin to a high filling rate of 80% by mass to 95% by mass. It is described that it can be obtained.

However, when filler is added at a high filling rate, the resulting heat conductive resin composition is often hard and brittle, and therefore, it tends to break easily. Moreover, when a filler is added with a high filling rate, the ratio of the epoxy resin component which has the adhesive performance contained in a heat conductive resin composition decreases. Therefore, in general, when filler is added at a high filling rate, the adhesiveness of the resin to a metal surface such as aluminum or copper, that is, the adhesive strength at the resin-metal interface tends to be greatly reduced.

As described above, it is possible to achieve a high thermal conductivity of the resin composition by adding an inorganic filler at a high filling rate, but on the other hand, the resin composition tends to lack flexibility and has an adhesive strength. It is a problem that the decline of

In view of the above situation, an object of the present invention is to provide a thermal conductive resin composition having excellent thermal conductivity and excellent flexibility and adhesiveness, and a molded product using the resin composition. It is to provide.

The present invention includes the following aspects.
The first aspect of the present invention is a thermally conductive resin composition containing an epoxy resin, an inorganic filler, and an elastomer having at least a structural unit represented by the following general formula (I) in the molecule.

In general formula (I), R ¹ , R ² and R ³ are each independently a linear or branched alkyl group or a hydrogen atom, R ⁴ is a linear or branched alkyl group, and n Represents an arbitrary integer.

The elastomer is preferably an acrylic resin. The acrylic resin preferably further has at least one of a carboxy group and a hydroxy group in the molecule. The acrylic resin preferably further has an amino group in the molecule.

The acrylic resin is preferably a compound having a structure represented by the following general formula (II).

In the formula (II), symbols a, b, c and d described in each structural unit are the mol% of each structural unit in all the structural units, and a + b + c + d = 90 mol% or more. R ²¹ and R ²² are each independently a linear or branched alkyl group having a different carbon number, and R ²³ to R ²⁶ are each independently a hydrogen atom or a methyl group.
R ²¹ and R ²² are preferably each independently a linear or branched alkyl group having 4 to 12 carbon atoms, each having a different carbon number.
The heat conductive resin composition preferably further contains a phenolic curing agent.

The second aspect of the present invention is a resin sheet formed by molding the thermal conductive resin composition into a sheet shape.

A third aspect of the present invention is a metal foil with a resin having a metal foil and a semi-cured resin layer that is a semi-cured product of the thermally conductive resin composition disposed on the metal foil.

A fourth aspect of the present invention is a cured resin sheet that is a heat-treated product of the thermally conductive resin composition.

A fifth aspect of the present invention is a heat dissipating member having a metal work and the resin sheet or the cured resin sheet disposed on the metal work.

ADVANTAGE OF THE INVENTION According to this invention, while having the outstanding heat conductivity, the heat conductive resin composition which was excellent also in the flexibility and the adhesiveness, and the molded article using this resin composition can be provided. .

It is typical sectional drawing which shows an example of the member for thermal radiation concerning this embodiment. (A) And (b) is typical sectional drawing explaining the state of the resin sheet in the flexibility judgment concerning a present Example.

In this specification, the term “process” is not limited to an independent process, and is included in the term if the intended action of the process is achieved even when it cannot be clearly distinguished from other processes. .
In the present specification, a numerical range indicated using “to” indicates a range including the numerical values described before and after “to” as the minimum value and the maximum value, respectively.
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.

<Thermal conductive resin composition>
The thermally conductive resin composition of the present invention (hereinafter also simply referred to as “resin composition”) comprises an epoxy resin, an inorganic filler, and an elastomer having at least a structural unit represented by the following general formula (I) in the molecule. Containing. By adding an elastomer having a specific chemical structure, the flexibility of the thermally conductive resin composition is greatly improved. In addition, the addition of the elastomer provides a stress relaxation function by lowering the elastic modulus, and greatly improves the adhesion of the heat conductive resin composition to, for example, a metal.

In general formula (I), R ¹ , R ² and R ³ are each independently a linear or branched alkyl group or a hydrogen atom, R ⁴ is a linear or branched alkyl group, and n Represents an arbitrary integer.

(Epoxy resin)
The epoxy resin used in the present invention is not particularly limited. For example, bisphenol F type epoxy resin, bisphenol S type epoxy resin, phenol novolac type epoxy resin, cresol novolac type epoxy resin, naphthalene type epoxy resin, cycloaliphatic epoxy resin and the like can be mentioned. Among these, from the viewpoint of increasing the thermal conductivity, it is preferable to use an epoxy resin having a mesogenic skeleton in the molecule, which is a structure that is easily self-aligned, such as a biphenyl group. An epoxy resin having such a mesogenic skeleton in the molecule is disclosed, for example, in JP-A-2005-206814. Examples of the epoxy resin include 1-{(3-methyl-4-oxiranylmethoxy) phenyl} -4- (4-oxiranylmethoxyphenyl) -1-cyclohexene, 1-{(2-methyl-4 -Oxiranylmethoxy) phenyl} -4- (4-oxiranylmethoxyphenyl) -1-cyclohexene, 1-{(3-ethyl-4-oxiranylmethoxy) phenyl} -4- (4-oxira Nylmethoxyphenyl) -1-cyclohexene.

Among these, 1-{(3-methyl-4-oxiranylmethoxy) phenyl} -4- (4-oxiranylmethoxyphenyl) -1-cyclohexene is preferable from the viewpoint of a low melting temperature. By using such a specific epoxy resin, it becomes possible to melt and mix with a curing agent described later at a curing temperature (preferably 120 ° C.) or lower, and it can be applied to a process requirement for low temperature curing.

The content of the epoxy resin in the resin composition is not particularly limited. For example, the solid content of the resin composition can be 1% by mass to 50% by mass, and preferably 1% by mass to 10% by mass. Adhesiveness and heat conductivity can be improved more because the content rate of an epoxy resin is the said range. The solid content of the resin composition means a residue obtained by removing volatile components from the resin composition.

(Inorganic filler)
The inorganic filler used in the present invention is not particularly limited, and compounds well known in the art can be used. They may be non-conductive or conductive. Examples of the non-conductive inorganic filler include aluminum oxide (alumina), magnesium oxide, aluminum nitride, boron nitride, silicon nitride, silicon oxide, aluminum hydroxide, and barium sulfate. When a non-conductive inorganic filler is used, it is preferable because there is little risk of a decrease in insulation. Examples of the conductive inorganic filler include gold, silver, nickel, and copper. When a conductive inorganic filler is used, the thermal conductivity can be improved, but the insulation tends to be lowered.

The inorganic filler may be used alone or in a mixed system of two or more. In addition, inorganic fillers having different particle sizes may be used in combination. In the embodiment in which fillers having different particle diameters are used in combination, an inorganic filler having a small particle diameter enters a gap between inorganic fillers having a large particle diameter, facilitating high filling of the inorganic filler, and high thermal conductivity efficiently. This is preferable because it can be realized.
In one embodiment of the present invention, it is preferable to use alumina as the inorganic filler, and it is more preferable to use a combination of alumina having different particle sizes.

As an example of an embodiment in which alumina having different particle diameters is used in combination as the inorganic filler, when the 50% cumulative particle size from the small particle side of the weight cumulative particle size distribution is D50, the alumina has a D50 of 2 μm or more. 100 μm or less of alumina (A), D50 is alumina powder (B) of 1 μm or more and 10 μm or less, and D50 is alumina powder (C) of 0.01 μm or more and 5 μm or less of alumina powder (A) with respect to the total volume of alumina powder The ratio of (B) and (C) is (A) 50% by volume to 90% by volume, (B) 5% by volume to 40% by volume, and (C) 1% by volume to 30% by volume, respectively. Some embodiments may be mentioned (wherein the total volume% of alumina (A), (B) and (C) is 100 volume%).

Furthermore, in the said embodiment, alumina (A) is 60 volume% or more and 90 volume% or less, alumina (B) is 10 volume% or more and 40 volume% or less, and alumina (C) is 5 volume% with respect to the total volume of alumina powder. Alumina powder having a volume% of 30% or less is preferable (however, the total volume% of alumina (A), (B) and (C) is 100% by volume). As an example of a more preferable alumina powder, alumina (A) is 70 volume% or more and 90 volume% or less, alumina (B) is 10 volume% or more and 30 volume% or less, and alumina (C) is 5 volume% or more and 20 volume% or less. A certain alumina powder is mentioned (however, the total volume% of alumina (A), (B) and (C) is 100 volume%).

More preferably, as an example of an embodiment in which aluminas having different particle sizes are used in combination as inorganic fillers, when the 50% cumulative particle size from the small particle side of the weight cumulative particle size distribution is D50, the alumina is D50 Is an alumina powder composed of alumina (A) having a diameter of 10 μm to 100 μm, alumina (B) having a D50 of 1 μm to less than 10 μm, and alumina (C) having a D50 of 0.01 μm to less than 1 μm, The ratio of (A), (B) and (C) is (A) 55 volume% or more and 85 volume% or less, (B) 10 volume% or more and 30 volume% or less, and (C) 5 volume% or more and 15 volume%, respectively. %, Wherein the total volume% of alumina (A), (B) and (C) is 100% by volume.

Furthermore, in the said embodiment, alumina (A) is 55 volume% or more and 85 volume% or less, alumina (B) is 10 volume% or more and 40 volume% or less, and alumina (C) is 5 volume% with respect to the total volume of alumina powder. Alumina powder having a volume% of 30% or less is preferable (however, the total volume% of alumina (A), (B) and (C) is 100% by volume). As an example of a more preferable alumina powder, alumina (A) is 65 volume% or more and 80 volume% or less, alumina (B) is 10 volume% or more and 20 volume% or less, and alumina (C) is 10 volume% or more and 15 volume% or less. A certain alumina powder is mentioned (however, the total volume% of alumina (A), (B) and (C) is 100 volume%).

The above alumina (A), (B) and (C) can be obtained as commercial products. Further, it is also possible to produce transition alumina or alumina powder that becomes transition alumina by heat treatment in an atmosphere gas containing hydrogen chloride (for example, Japanese Patent Laid-Open Nos. 6-191833 and 6-6-1). No. 191836). The alumina powder can be prepared by appropriately mixing alumina (A), (B) and (C) having a predetermined particle size distribution. The alumina powder is preferably α-alumina powder. As the alumina (A) and (B), alumina made of α-alumina particles is preferable, and alumina made of α-alumina single crystal particles is more preferable. The alumina (C) may be alumina made of α-alumina particles, or alumina made of transition alumina particles such as γ-alumina, θ-alumina, and δ-alumina. Alumina made of α-alumina particles is preferred, and alumina made of α-alumina single crystal particles is more preferred.

The particle diameter D50 of the alumina particles is measured as a weight average particle diameter by a wet method using a laser diffraction / scattering particle size distribution analyzer.

In the present invention, the content of the entire filler in the resin composition is not particularly limited. In particular, the total solid volume of the resin composition is preferably 30% by volume to 95% by volume, more preferably 45% by volume to 90% by volume from the viewpoint of improving thermal conductivity, and further heat conduction. From the viewpoint of improving the rate, it is more preferably 80 to 90% by volume. When it is 30% by volume or more, the thermal conductivity of the resin composition tends to be higher. Moreover, it exists in the tendency which the moldability of a resin composition improves more that it is 95 volume% or less.
In addition, the total solid content volume of a resin composition means the total volume of a non-volatile component among the components which comprise a resin composition.

(Elastomer)
The elastomer is a compound having at least a structural unit represented by the following general formula (I) in the molecule, and an acrylic resin is particularly preferable. The acrylic resin is preferably a homopolymer or a copolymer derived from (meth) acrylic acid or (meth) acrylic acid ester. In one embodiment of the present invention, it is preferable to use an acrylic resin copolymer mainly containing a structural unit represented by the following general formula (I) as an elastomer.

In the general formula (I), R ¹ , R ² and R ³ each independently represent a linear or branched alkyl group or a hydrogen atom. When any of R ¹ , R ² or R ³ is an alkyl group, the number of carbons is preferably 1 to 12 from the viewpoint of imparting flexibility, and the number of carbons from the viewpoint of low Tg (glass transition temperature). Is more preferably 1-8. In a preferred embodiment of the present invention, R ¹ and R ² are each a hydrogen atom, and R ³ is a hydrogen atom or a methyl group. More preferably, R ¹ , R ² and R ³ are hydrogen atoms.

In the above general formula (I), R ⁴ is a linear or branched alkyl group. The alkyl group in R ⁴ preferably has 2 to 16 carbon atoms from the viewpoint of imparting flexibility, and more preferably 3 to 14 carbon atoms from the viewpoint of small inhibition of the formation of the resin higher-order structure. Preferably, the number of carbon atoms is 4 to 12 from the viewpoints of availability and ease of synthesis.
Also, the elastomer preferably has a structural unit number of carbon atoms in the alkyl group represented by R ⁴ is represented by two or more of the general formulas differ (I). For example, when the elastomer has two types of structural units represented by the general formula (I), the carbon number of the alkyl group in one structural unit may be 2 to 8 from the viewpoint of low Tg. Preferably, the number of carbon atoms is 3-6. The number of carbon atoms of the alkyl group in the other structural unit is preferably 8 to 16 carbon atoms, and more preferably 10 to 14 carbon atoms from the viewpoint of imparting flexibility.

In the above general formula (I), n is an arbitrary integer indicating the number of repeating units. The number of repeating units represented by n means the total number of structural units represented by the general formula (I) contained in the elastomer molecule. n = 100 to 1000 is preferable, n = 100 to 500 is more preferable from the viewpoint of imparting flexibility, and n = 100 to 300 is particularly preferable from the viewpoint of low Tg.

By using an acrylic resin mainly having a structural unit represented by the above general formula (I), it is possible to impart a soft structure (flexibility) to a thermally conductive resin composition containing an epoxy resin and an inorganic filler. Become. Therefore, it is possible to improve the problems such as a decrease in the flexibility of the sheet due to the high filling of the inorganic filler as seen in the conventional heat conductive sheet.

In one embodiment of the present invention, the acrylic resin having at least the structural unit represented by the general formula (I) in the molecule preferably further has at least one of a carboxy group and a hydroxy group in the molecule. It is more preferable to include a structural unit having at least one of hydroxy groups, and it is more preferable to include a structural unit having at least a carboxy group.

Examples of monomers that can form a structural unit having a carboxy group include acrylic acid, methacrylic acid, maleic acid, and itaconic acid. Among these, acrylic acid and methacrylic acid are preferable.
Examples of the monomer capable of forming a structural unit having a hydroxy group include (meth) acrylic acid esters containing a hydroxyalkyl group having 2 to 20 carbon atoms, including a hydroxyalkyl group having 2 to 6 carbon atoms. A (meth) acrylic acid ester is preferred. Specific examples include hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, hydroxybutyl (meth) acrylate, and the like.

When a carboxy group or a hydroxy group is present in the acrylic resin, these undergo a crosslinking reaction with the epoxy resin during the curing reaction, so that the crosslinking density is improved, and as a result, the thermal conductivity can be improved.
In addition, since the carboxy group releases hydrogen ions, the epoxy group is easily opened during the curing reaction, and has an effect of acting as a catalyst. Furthermore, since the carboxy group acts with a hydroxyl group on the surface of the inorganic filler, it brings about a surface treatment effect on the inorganic filler. The effect of such surface treatment is that the wettability between the inorganic filler and the acrylic resin is improved, so that the viscosity of the varnish is lowered when the varnish is blended, and the coating tends to be easy. Furthermore, the improvement of wettability causes the inorganic filler to be more highly dispersed and contributes to the improvement of thermal conductivity.

When the acrylic resin has at least one of carboxy group and hydroxy group, the content of the structural unit having at least one of carboxy group and hydroxy group contained in the acrylic resin is not particularly limited. From the viewpoint of filler dispersibility, the content of the structural unit having at least one of a carboxy group and a hydroxy group in the acrylic resin is preferably 10 mol% or more and 30 mol% or less, and 14 mol% or more and 28 mol% or less. More preferably.

In one embodiment of the present invention, the acrylic resin having at least the structural unit represented by the general formula (I) in the molecule preferably further includes at least one amino group in the molecule. It is preferable to include at least one kind of structural unit. Among these, from the viewpoint of preventing moisture absorption, a secondary amino group or a tertiary amino group is preferable. From the viewpoint of improving thermal conductivity, an N-methylpiperidino group is particularly preferable. When an N-methylpiperidino group is present in the acrylic resin, the compatibility is remarkably improved by the interaction with the phenol curing agent, which is preferable. Thus, when the acrylic resin excellent in compatibility is added to the system of a composition, the loss of heat conductivity becomes small. In addition, the interaction between the N-methylpiperidino group and the phenol-based curing agent exhibits a stress relaxation effect due to slippage between different types of molecules, and contributes to an improvement in adhesion.

When the acrylic elastomer has an amino group, the content of the amino group contained in the acrylic elastomer is not particularly limited. From the viewpoint of compatibility, the content of the structural unit having an amino group in the resin constituting the acrylic elastomer is preferably 0.5 mol% or more and 5 mol% or less, and 0.7 mol% or more and 3.5 mol% or less. More preferably, it is at most mol%.

In one embodiment of the present invention, it is preferable to use a compound having a structure represented by the following general formula (II) as the acrylic resin.

In the formula (II), the symbols a, b, c and d described in each structural unit are mol% of each structural unit with respect to all structural units constituting the compound, and a + b + c + d = 90 mol% or more. It is preferably at least mol%, more preferably at least 99 mol%.
R ²¹ and R ²² are each independently a linear or branched alkyl group having a different carbon number. R ²³ to R ²⁶ each independently represents a hydrogen atom or a methyl group.

In the acrylic resin represented by the general formula (II), the structural unit present in the proportion of a (hereinafter also referred to as “structural unit a”) can impart flexibility to the sheet, and also has thermal conductivity. And compatibility with flexibility. Further, the structural unit present in the proportion of b (hereinafter also referred to as “structural unit b”) makes the sheet more flexible in combination with the structural unit a shown above. Thus, the chain length of the alkyl group represented by R ²¹ and R ²² in the structural units a and b that imparts a flexible structure (flexibility) is not particularly limited. However, if the chain length is 16 or less, the Tg of the acrylic resin does not become too high, and the flexibility improving effect obtained by adding the acrylic resin to the resin composition tends to be sufficiently obtained. On the other hand, when the chain length of R ²¹ and R ²² is 2 or more, the flexibility of the acrylic resin itself is further improved, and the effect obtained by adding the acrylic resin tends to be sufficiently obtained. From such a viewpoint, the chain lengths of R ²¹ and R ²² are preferably in the range of 2 to 16 carbon atoms, more preferably in the range of 3 to 14 carbon atoms, and still more preferably in the range of 4 to 12 carbon atoms.

The alkyl groups represented by R ²¹ and R ²² have different carbon numbers. The difference in carbon number between R ²¹ and R ²² is not particularly limited, but the difference in carbon number is preferably 4 to 10 and more preferably 6 to 8 from the viewpoint of the balance between flexibility and flexibility. .
Further, from the viewpoint of the balance between flexibility and flexibility, R ²¹ preferably has 2 to 6 carbon atoms, R ²² preferably has 8 to 16 carbon atoms, and R ²¹ has 3 to 5 carbon atoms. More preferably, R ²² has 10 to 14 carbon atoms.

In the general formula (II), the range of mol% of the structural unit a and the structural unit b is not particularly limited. Further, the ratio between the structural unit a and the structural unit b may be arbitrary. It is preferable to use an acrylic resin including a combination of the structural unit a and the structural unit b, rather than any one of the structural unit a and the structural unit b being included alone. The combination of the structural unit a and the structural unit b may increase the number of side chains and increase the flexibility of the acrylic resin, and may increase the Tg. However, Tg can be controlled within a suitable range by appropriately adjusting the molar ratios a and b of the structural unit a and the structural unit b in the acrylic resin.

Specifically, for example, from the viewpoint of the flexibility and filler dispersibility of the resin sheet, the content of the structural unit a is preferably 50 mol% to 85 mol%, more preferably 60 mol% to 80 mol%. The content of the structural unit b is preferably 2 mol% to 20 mol%, more preferably 5 mol% to 15 mol%. Further, the content ratio of the structural unit a to the structural unit b is preferably 4 to 10, and more preferably 6 to 8.

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

R ²³ to R ²⁶ are each independently a hydrogen atom or a methyl group, but it is preferable that at least one of R ²³ and R ²⁴ is a hydrogen atom and the other is a methyl group, and R ²³ is a hydrogen atom and R ²⁴ is More preferred is a methyl group. Moreover, it is preferable that at least one of R ²⁵ and R ²⁶ is a hydrogen atom and the other is a methyl group, and it is more preferable that R ²⁵ is a hydrogen atom and R ²⁶ is a methyl group.

The acrylic resin having the structure represented by the general formula (II) may further contain structural units other than the structural units a to d. The structural unit other than the structural units a to d is not particularly limited. For example, the structural unit derived from the (meth) acrylic acid ester containing a hydroxyalkyl group and the structural unit derived from the (meth) acrylic acid ester containing a tertiary amino group can be mentioned.
The content of structural units other than the structural units a to d in the acrylic resin is 10 mol% or less, preferably 5 mol% or less, and more preferably 1 mol% or less.

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

In the thermally conductive resin composition according to the present invention, the content of the elastomer is 0. 0 when the total mass of the epoxy resin-containing components (epoxy resin and a curing agent included as necessary) is 100 parts by mass. It can be in the range of 1 to 99 parts by mass, preferably in the range of 1 to 20 parts by mass, and more preferably in the range of 1 to 10 parts by mass.
When the added amount of the acrylic resin is 0.1 parts by mass or more, a decrease in thermal conductivity tends to be suppressed and the adhesive force with the adherend tends to be improved. On the other hand, when the amount is 99 parts by mass or less of the acrylic resin, a decrease in adhesive strength with the adherend is suppressed, and the thermal conductivity tends to be improved. Therefore, it becomes easy to express various characteristics in a well-balanced manner by adjusting the amount of the acrylic resin added to the above range.

(Curing agent)
The resin composition preferably contains at least one curing agent. There is no restriction | limiting in particular as a hardening | curing agent, According to curable resin, it can select suitably. In particular, when the curable resin is an epoxy resin, the curing agent can be appropriately selected from curing agents usually used as a curing agent for epoxy resins. Specific examples include amine curing agents such as dicyandiamide and aromatic diamine, and phenolic curing agents such as phenol novolac resin, cresol novolac resin, and catechol resorcinol novolak resin. Among these, from the viewpoint of improving thermal conductivity, a phenolic curing agent is preferable, and a phenolic curing agent containing a bifunctional phenol such as catechol, resorcinol and p-hydroquinone is preferable.

The content of the curing agent in the resin composition is not particularly limited. For example, with respect to the epoxy resin, it can be 0.1 to 2.0 on an equivalent basis, preferably 0.5 to 1.5 from the viewpoint of improving flexibility, and 0.8 from the viewpoint of high thermal conductivity. It is preferable that it is -1.1.
Adhesiveness and heat conductivity can be improved more because the content rate of a hardening | curing agent is the said range.

(Curing catalyst)
The resin composition preferably contains at least one curing catalyst. There is no restriction | limiting in particular as a curing catalyst, According to the kind of curable resin, it can select from the curing catalyst used normally, and can use it. When the curable resin is an epoxy resin, specific examples of the curing catalyst include triphenylphosphine, 2-ethyl-4-methylimidazole, boron trifluoride amine complex, 1-benzyl-2-methylimidazole, and the like. Can be mentioned. Among them, it is preferable to use triphenylphosphine from the viewpoint of achieving high thermal conductivity.

The content rate of the curing catalyst in the resin composition is not particularly limited. For example, it can be 0.1% by mass to 2.0% by mass and preferably 0.5% by mass to 1.5% by mass with respect to the epoxy resin.
Adhesiveness and heat conductivity can be improved more because the content rate of a curing catalyst is the said range.

(Coupling agent)
The resin composition preferably contains at least one coupling agent in addition to the essential components, epoxy resin, elastomer and inorganic filler. The coupling agent can be contained for the purpose of, for example, surface treatment of inorganic filler.
The coupling agent is not particularly limited, and can be appropriately selected from commonly used coupling agents. Specifically, for example, methyltrimethoxysilane (available from Shin-Etsu Chemical Co., Ltd., available as trade name “KBM-13”), 3-mercaptopropyltrimethoxysilane (available from Shin-Etsu Chemical Co., Ltd., trade name “KBM-”). 803 "), 3-triethoxysilyl-N- (1,3-dimethyl-butylidene) propylamine (available from Shin-Etsu Chemical Co., Ltd., trade name" KBE-9103 "), N-phenyl- 3-aminopropyltrimethoxysilane (available from Shin-Etsu Chemical Co., Ltd., trade name “KBM-573”), 3-aminopropyltrimethoxysilane (made by Shin-Etsu Chemical Co., Ltd., trade name “KBM-903”) 3-glycidyloxypropyltrimethoxysilane (available from Shin-Etsu Chemical Co., Ltd., trade name “KB”) -403 "available) include silane coupling agents such as. Among these, N-phenyl-3-aminopropyltrimethoxysilane is preferable from the viewpoint of achieving high thermal conductivity.

The content of the coupling agent in the resin composition is not particularly limited. For example, with respect to the inorganic filler, it can be 0.05% by mass to 1.0% by mass, and preferably 0.1% by mass to 0.5% by mass.
Thermal conductivity can be improved more because the content rate of a coupling agent is the said range.

(solvent)
The thermally conductive resin composition may contain at least one solvent. The solvent is not particularly limited as long as it does not inhibit the curing reaction of the resin composition, and can be appropriately selected from commonly used organic solvents. Specific examples include ketone solvents such as methyl ethyl ketone and cyclohexanone, and alcohol solvents such as cyclohexanol.
The content of the solvent in the heat conductive resin composition is not particularly limited, and can be appropriately selected according to the applicability of the heat conductive resin composition.

<Resin sheet>
The resin sheet of the present invention is formed by molding the resin composition into a sheet shape. The said resin sheet can be manufactured by apply | coating the said resin composition on a release film, for example, and removing the solvent contained as needed.
The said resin sheet is excellent in thermal conductivity, flexibility, and adhesiveness by being comprised from the said resin composition.

The resin sheet is formed from the resin composition into a sheet shape, and is preferably a B stage sheet that is further heat-treated until it is in a semi-cured state (B stage state).
The B-stage sheet is a resin sheet having a viscosity of 10 ⁴ Pa · s to 10 ⁵ Pa · s at room temperature (25 degrees), whereas it is 10 ² Pa · s to 10 ³ Pa · s at 100 ° C. The viscosity is reduced to s. Moreover, the cured resin sheet to be described later is not melted by heating. The viscosity is measured by dynamic viscoelasticity measurement (frequency 1 Hz, load 40 g, temperature increase rate 3 ° C./min).

For example, the resin sheet can be manufactured as follows.
A resin layer can be obtained by applying and drying a varnish-like resin composition to which a solvent such as methyl ethyl ketone or cyclohexanenon is added on a release film such as a PET film.
Application | coating can be implemented by a well-known method. Specific examples of the coating method include comma coating, die coating, lip coating, and gravure coating. As a coating method for forming a resin layer with a predetermined thickness, a comma coating method in which an object to be coated is passed between gaps, a die coating method in which a resin varnish whose flow rate is adjusted from a nozzle, or the like can be applied. . For example, when the thickness of the resin layer before drying is 50 μm to 500 μm, it is preferable to use a comma coating method.

Since the resin layer after coating has hardly progressed the curing reaction, it has flexibility, but it has poor flexibility as a sheet, and in the state where the PET film as a support is removed, the sheet is not self-supporting, It is difficult to handle. Therefore, it is preferable to B-stage the resin composition by heat treatment described below.
The conditions for heat-treating the obtained resin layer are not particularly limited as long as the resin composition can be semi-cured to the B stage state, and can be appropriately selected according to the configuration of the resin composition. The heat treatment is preferably a heat treatment method selected from a hot vacuum press and a hot roll laminate. Thereby, the void | void (void) in the resin layer produced in the case of coating can be reduced, and a flat B stage sheet | seat can be manufactured efficiently.
Specifically, for example, the resin composition can be semi-cured in a B-stage state by heat-pressing at a heating temperature of 80 ° C. to 130 ° C. for 1 to 30 seconds under reduced pressure (for example, 1 MPa).

The thickness of the resin sheet can be appropriately selected according to the purpose. For example, it can be 50 μm or more and 200 μm or less, and from the viewpoint of thermal conductivity and sheet flexibility, it is 60 μm or more and 150 μm or less. preferable. The resin sheet can also be produced by hot pressing while laminating two or more resin layers.

<Metal foil with resin>
The metal foil with resin of this invention has metal foil and the semi-hardened resin layer which is a semi-hardened material of the said heat conductive resin composition arrange | positioned on the said metal foil. By having a semi-cured resin layer derived from the thermal conductive resin composition, the thermal conductivity, electrical insulation, and flexibility are excellent.
The semi-cured resin layer is obtained by heat-treating the resin composition so as to be in a B-stage state.

The metal foil is not particularly limited, such as a gold foil, a copper foil, and an aluminum foil, but generally a copper foil is used.
The thickness of the metal foil is not particularly limited as long as it is 1 μm to 35 μm, but flexibility is further improved by using a metal foil of 20 μm or less.
In addition, nickel, nickel-phosphorus, nickel-tin alloy, nickel-iron alloy, lead, lead-tin alloy, etc. are used as the intermediate layers for the metal foil, and 0.5 μm to 15 μm copper layer and 10 μm to 300 μm on both sides. A composite foil having a three-layer structure provided with a copper layer or a two-layer structure composite foil in which aluminum and copper foil are combined can also be used.

The metal foil with resin can be produced by forming a resin layer by applying and drying the thermally conductive resin composition on the metal foil, and the method for forming the resin layer is as described above.

The production conditions of the resin-coated metal foil are not particularly limited, but it is preferable that 80% by mass or more of the organic solvent used for the resin varnish is volatilized in the resin layer after drying. The drying temperature is about 80 ° C. to 180 ° C., and the drying time can be determined in consideration of the gelling time of the varnish, and is not particularly limited. The coating amount of the resin varnish is preferably applied so that the thickness of the resin layer after drying is 50 μm to 200 μm, and more preferably 60 μm to 150 μm.
The resin layer after drying becomes a B stage state by heat treatment. The conditions for heat treatment of the thermally conductive resin composition are the same as the heat treatment conditions for the B-stage sheet.

<Hardened resin sheet>
The cured resin sheet of the present invention is obtained by heat-treating the thermally conductive resin composition. The curing method for curing the thermally conductive resin composition can be appropriately selected according to the configuration of the thermally conductive resin composition, the purpose of the cured resin sheet, and the like, but is preferably a heat and pressure treatment. The conditions for the heat and pressure treatment are, for example, that the heating temperature is 80 ° C. to 250 ° C., the pressure is preferably 0.5 MPa to 8.0 MPa, the heating temperature is 130 ° C. to 230 ° C., and the pressure is 1.5 MPa to More preferably, it is 5.0 MPa.
The treatment time for the heat and pressure treatment can be appropriately selected according to the heating temperature and the like. For example, it can be 2 to 8 hours, and preferably 4 to 6 hours.
Further, the heat and pressure treatment may be performed once, or may be performed twice or more by changing the heating temperature or the like.

<Heat dissipation member>
The heat radiating member of the present invention includes at least a metal workpiece and the B stage sheet or the cured resin sheet disposed on the metal workpiece so as to be in contact with the metal workpiece.
Here, the “metal workpiece” means a molded product made of a metal material that can function as a heat dissipation member, including a substrate, fins, and the like. In one embodiment of the present invention, the metal workpiece is preferably a substrate composed of various metals such as Al and Cu.

As an embodiment of the heat radiating member of the present invention, a heat radiating member using a resin sheet obtained by molding the heat conductive resin composition into a sheet is illustrated in FIG. The resin sheet may be a B stage sheet or a cured resin sheet.
In FIG. 1, the resin sheet 10 is located between a first metal workpiece 20 made of, for example, Al and a second metal workpiece 30 made of, for example, Cu, and one surface thereof is on the surface of the metal workpiece 20. The other surface is bonded to the surface of the metal work 30. The resin sheet 10 is excellent in flexibility and can realize excellent adhesiveness with the contact surfaces of the first and second metal workpieces 20 and 30.
In general, the resin sheet applied to the adhesion of the metal workpiece desirably has a shear strength of 5 MPa or more from the viewpoint of adhesion. As will be apparent from Examples described later, according to the present invention, a resin sheet satisfying the above-described shear strength can be provided. In addition, since the resin sheet 10 has excellent thermal conductivity, for example, the heat generated from the second metal work 30 made of Cu is used as the first metal work made of Al through the resin sheet 10. It becomes possible to conduct efficiently to the 20 side and to dissipate heat to the outside.

Hereinafter, the present invention will be specifically described by way of examples. However, the present invention is not limited to these examples. Unless otherwise specified, “part” and “%” are based on mass.

(Synthesis of catechol resorcinol novolak (CRN))
Into a 3 L separable flask equipped with a stirrer, a cooler and a thermometer, 594 g of resorcinol, 66 g of catechol, 316.2 g of 37% formalin, 15 g of oxalic acid and 100 g of water were added, and the temperature was raised to 100 ° C. while heating in an oil bath. The reaction was continued for 4 hours at this reflux temperature. Thereafter, the temperature in the flask was raised to 170 ° C. while distilling off water, and the reaction was continued for 8 hours while maintaining 170 ° C.

Thereafter, concentration was performed under reduced pressure for 20 minutes to remove water and the like in the system, and catechol resorcinol novolak was taken out. The obtained catechol resorcinol novolak (CRN) resin had a number average molecular weight of 530 and a weight average molecular weight of 930. The hydroxyl equivalent of the CRN resin was 65. The catechol resorcinol novolak (CRN) resin obtained above was used in the following examples.

(Elastomer synthesis)
The elastomer used in the following examples was synthesized with reference to Japanese Patent Application Laid-Open No. 2010-106220. According to the structure of the elastomer, an appropriate solvent was used, and the monomer components were mixed with a polymerization initiator and the like so as to have a desired ratio, stirred, heated and copolymerized.
Example 1
1. Production of Elastomer-Containing Resin Sheet In a 100 cm ³ plastic bottle, 0.0960 parts by mass of 3-glycidyloxypropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., trade name “KBM403”) as a coupling agent and the following structure as an elastomer 0.5027 parts by mass of an acrylic resin REB122-4 having a formula, weight average molecular weight 24000) and a catechol resorcinol novolak (CRN) resin synthesized above as a curing agent (weight average molecular weight 930, catechol: resorcinol = 5: 95) ) 4.7758 parts by mass of a cyclohexanone-dissolved product (solid content 50% by mass) was added in this order.

Next, after putting 120.00 parts by mass of alumina balls (particle diameter 3 mm) into the plastic bottle, 66.72 parts by mass of aluminum oxide (AA-18) having a weight average particle diameter (D50) of 18 μm as an inorganic filler (Sumitomo) Chemical Co., Ltd., 74.0% by volume in inorganic filler), weight average particle size (D50) 3 μm of aluminum oxide (AA-3) 12.62 parts by mass (manufactured by Sumitomo Chemical Co., Ltd., inorganic filler) 10.2 parts by volume of aluminum oxide (AA-04) having a content rate of 14.0% by volume and a weight average particle size (D50) of 0.4 μm (Sumitomo Chemical Co., Ltd., content rate of 12.0% by volume in inorganic filler) ) Was added.
Further, 15.84 parts by mass of methyl ethyl ketone and 2.89 parts by mass of cyclohexanone were added and mixed. After confirmation of homogeneity by stirring, 1-{(3 synthesized from 1- (3-methyl-4-hydroxyphenyl) -4- (4-hydroxyphenyl) -1-cyclohexene and epichlorohydrin was obtained. -Methyl-4-oxiranylmethoxy) phenyl} -4- (4-oxiranylmethoxyphenyl) -1-cyclohexene 7.1638 parts by mass (epoxy resin) and 0.053 parts by mass triphenylphosphine (Wako Pure) Further, the mixture was further mixed and ball milled for 40 to 60 hours to obtain a resin sheet coating solution as a heat conductive resin composition.

Using the applicator, the obtained resin sheet coating solution is applied to a release surface of a polyethylene terephthalate film (Fujimori Kogyo Co., Ltd., 75E-0010CTR-4, hereinafter abbreviated as PET film) to a thickness of about 300 μm. It was coated and allowed to stand for 15 minutes in a normal state, and then dried in a box oven at 100 ° C. for 30 minutes to form a resin composition layer on the PET film. Next, the upper surface of the resin composition layer that has been in contact with air is covered with a PET film, and flattened by hot pressing (upper hot plate 150 ° C., lower hot plate 80 ° C., pressure 1.5 MPa, treatment time 3 minutes). A B-stage sheet was obtained as an elastomer-containing resin sheet having a thickness of 200 μm.
When the flexibility of the obtained B-stage sheet was evaluated as follows, it was good and was A.

(Evaluation of flexibility)
The flexibility was determined mainly by touching the B stage sheet before curing. The judgment criteria are as follows.
-Criteria-
A: The handling is good and it is considered that no trouble occurs during molding.
B: Hard and brittle and considered to require careful handling during molding.
FIG. 2 is a schematic cross-sectional view for explaining the state of the sheet in determining the flexibility of the sheet. In the figure, reference numeral 10 denotes a resin sheet, and 40 denotes a support. FIG. 2 (a) shows a state in which the elastomer is not added and the flexibility of the sheet is poor, and FIG. 2 (b) shows a state in which the flexibility of the sheet is improved by adding an elastomer having a specific structure. .

2. Preparation of cured product of resin sheet The PET film is peeled off from both sides of the elastomer-containing resin sheet (B stage sheet) obtained by the method described above, and both sides are sandwiched between 105 μm-thick copper foils (Furukawa Electric Co., Ltd., GTS foil), Vacuum heat press (upper hot plate 150 ° C, lower hot plate 80 ° C, degree of vacuum ≤ 1 kPa, pressure 4 MPa, treatment time 7 minutes), then put in a box-type oven at 140 ° C for 2 hours, 165 ° C for 2 hours Curing was performed by step curing at 190 ° C. for 2 hours. From the obtained cured copper foil, only copper was removed by etching using a sodium persulfate solution to obtain a cured product of a heat conductive resin sheet containing an acrylic resin (REB122-4).
As a result of measuring the thermal conductivity of the obtained cured product by the xenon flash method as follows, the thermal conductivity was 8.0 W / mK.

(Measurement method of thermal conductivity)
The thermal diffusivity of the sheet was measured using a Nanoflash LFA447 Xe flash method thermal diffusivity measuring apparatus manufactured by NETZSCH. The thermal conductivity (W / mK) was calculated by multiplying the numerical value of the obtained thermal diffusivity by the specific heat Cp (J / g · K) and the density d (g / cm ³ ). All measurements were performed at 25 ± 1 ° C.

3. Adhesion of the elastomer-containing resin sheet to the metal workpiece The PET film is peeled off from both sides of the elastomer-containing resin sheet (B stage sheet) obtained by the above method, and both sides are sandwiched between a copper plate and an aluminum plate, and vacuum hot press (hot plate temperature) 140 ° C, degree of vacuum ≤ 1 kPa, pressure 0.2 MPa, treatment time 10 minutes), then put in a box-type oven for 2 hours at 140 ° C, 2 hours at 165 ° C and 2 hours at 190 ° C to cure Went. The shear bond strength of the metal workpiece on which the B stage sheet containing REB122-4 thus obtained was affixed was 7.5 [MPa].

(Measurement method of adhesive strength)
Using a Tensilon universal testing machine “RTC-1350A” manufactured by Orientec Co., Ltd., the copper plate and the aluminum plate were peeled off at a test speed of 1 mm / min to measure the shear adhesive strength of the sheet work.

(Example 2)
An acrylic resin (REB124-6) was used in the same manner as in Example 1 except that “REB124-6” (weight average molecular weight 44000) having the following structural formula was used instead of “REB122-4” as the acrylic resin. A) B-stage sheet was prepared. When the flexibility of the obtained B-stage sheet was evaluated in the same manner as in Example 1, it was good and the evaluation was A.

Next, a cured B-stage sheet containing REB124-6 was produced in the same manner as in Example 1. As a result of measuring the thermal conductivity of the obtained cured product by the xenon flash method in the same manner as in Example 1, the thermal conductivity was 7.0 W / mK.
Further, in the same manner as in Example 1, a metal workpiece on which a B stage sheet containing REB124-6 was attached was produced. When the shear adhesive strength of the obtained metal workpiece was measured in the same manner as in Example 1, it was 7.4 [MPa].

(Example 3)
An acrylic resin (REB58-5) was used in the same manner as in Example 1 except that “REB58-5” (weight average molecular weight 34000) having the following structural formula was used instead of “REB122-4” as the acrylic resin. A) B-stage sheet was prepared. The flexibility of the obtained B stage sheet was good.

Next, a cured B-stage sheet containing REB58-5 was produced in the same manner as in Example 1. As a result of measuring the thermal conductivity of the obtained cured product by the xenon flash method in the same manner as in Example 1, the thermal conductivity was 6.8 W / mK.
Further, in the same manner as in Example 1, a metal workpiece on which a B stage sheet containing REB58-5 was attached was produced. When the shear adhesive strength of the obtained metal workpiece was measured in the same manner as in Example 1, it was 7.6 [MPa].

Example 4
An acrylic resin (REB124-2) was used in the same manner as in Example 1 except that “REB124-2” (weight average molecular weight 39000) having the following structural formula was used instead of “REB122-4”. A) B-stage sheet was prepared. When the flexibility of the obtained B-stage sheet was evaluated in the same manner as in Example 1, it was good and the evaluation was A.

Next, a cured B-stage sheet containing REB 124-2 was produced in the same manner as in Example 1. As a result of measuring the thermal conductivity of the obtained cured product by the xenon flash method in the same manner as in Example 1, the thermal conductivity was 5.5 W / mK.
Further, in the same manner as in Example 1, a metal workpiece on which a B stage sheet containing REB 124-2 was attached was produced. When the shear adhesive strength of the obtained metal workpiece was measured in the same manner as in Example 1, it was 5.0 [MPa].

(Example 5)
An acrylic resin (REB 146-2) was used in the same manner as in Example 1 except that “REB 146-2” (weight average molecular weight 43081) having the following structural formula was used instead of “REB 122-4” as the acrylic resin. A) B-stage sheet was prepared. When the flexibility of the obtained B-stage sheet was evaluated in the same manner as in Example 1, it was good and the evaluation was A.

Next, a cured product of a B stage sheet containing REB 146-2 was produced in the same manner as in Example 1. As a result of measuring the thermal conductivity of the obtained cured product by the xenon flash method in the same manner as in Example 1, the thermal conductivity was 6.0 W / mK.
Further, in the same manner as in Example 1, a metal workpiece on which a B stage sheet containing REB 146-2 was attached was produced. When the shear adhesive strength of the obtained metal workpiece was measured in the same manner as in Example 1, it was 5.1 [MPa].

(Example 6)
An acrylic resin (REB100-5) was used in the same manner as in Example 1 except that “REB100-5” (weight average molecular weight 25000) having the following structural formula was used instead of “REB122-4” as the acrylic resin. A) B-stage sheet was prepared. When the flexibility of the obtained B-stage sheet was evaluated in the same manner as in Example 1, it was good and the evaluation was A.

Next, in the same manner as in Example 1, a cured B stage sheet containing REB 100-5 was produced. As a result of measuring the thermal conductivity of the obtained cured product by the xenon flash method in the same manner as in Example 1, the thermal conductivity was 7.0 W / mK.
Further, in the same manner as in Example 1, a metal workpiece on which a B stage sheet containing REB 100-5 was attached was produced. When the shear adhesive strength of the obtained metal workpiece was measured in the same manner as in Example 1, it was 5.0 [MPa].

(Comparative Example 1)
1. Preparation of Elastomer-Free Resin Sheet In a 100 cm ³ plastic bottle, 0.0960 parts by mass of 3-glycidyloxypropyltrimethoxysilane (trade name “KBM403” manufactured by Shin-Etsu Chemical Co., Ltd.) was used in the same manner as in Example 1. A pre-prepared catechol resorcinol novolak (CRN) resin cyclohexanone-dissolved product 5.0272 parts by mass (solid content 50% by mass) was added in this order.
Next, 120.00 parts by mass of alumina balls (particle size 3 mm) were charged into the plastic bottle, followed by 66.72 parts by mass of aluminum oxide (AA-18) having a weight average particle size of 18 μm (manufactured by Sumitomo Chemical Co., Ltd., inorganic Content in the filler 74.0% by volume), 12.62 parts by mass of aluminum oxide (AA-3) having a weight average particle diameter of 3 μm (manufactured by Sumitomo Chemical Co., Ltd., content 14.0% by volume in the inorganic filler), 10.82 parts by mass of aluminum oxide (AA-04) having a weight average particle size of 0.4 μm (Sumitomo Chemical Co., Ltd., content: 12.0% by volume in inorganic filler) was added. Further, 15.84 parts by mass of methyl ethyl ketone and 2.77 parts by mass of cyclohexanone were added and mixed. After confirmation of homogeneity by stirring, the 1-{(3-methyl-4-hydroxyphenyl) -4- (4-hydroxyphenyl) -1-cyclohexene synthesized from epichlorohydrin and 1-{(3- Methyl-4-oxiranylmethoxy) phenyl} -4- (4-oxiranylmethoxyphenyl) -1-cyclohexene 7.5407 parts by mass (epoxy resin) and 0.053 parts by mass of triphenylphosphine (manufactured by Wako Pure Chemical Industries, Ltd.) The mixture was further mixed and ball milled for 40 to 60 hours to obtain a resin sheet coating solution.

Using the applicator, the coating solution obtained above is adjusted to a thickness of about 300 μm on the release surface of a polyethylene terephthalate film (Fujimori Kogyo Co., Ltd., 75E-0010CTR-4, hereinafter abbreviated as PET film). After coating and leaving in a normal state for 15 minutes, drying was performed in a box oven at 100 ° C. for 30 minutes, and then the upper surface that had been in contact with air was covered with a PET film and hot pressing (upper hot plate 150 ° C., lower hot plate 80 ° C. , Pressure 1.5 MPa, treatment time 3 minutes), and a B stage sheet was obtained as an elastomer-free resin sheet having a thickness of 200 μm. When the flexibility of the obtained B-stage sheet was evaluated in the same manner as in Example 1, the sheet was fragile and judged as B.

2. Preparation of cured product of non-elastomer-containing resin sheet The PET film was peeled off from both sides of the non-elastomer-containing resin sheet (B stage sheet) obtained by the above-mentioned method, and both sides were 105 μm thick copper foil (Furukawa Electric Co., Ltd., GTS foil) ) And vacuum hot press (upper hot plate 150 ° C., lower hot plate 80 ° C., degree of vacuum ≦ 1 kPa, pressure 4 MPa, treatment time 7 minutes), then placed in a box-type oven at 140 ° C. for 2 hours, 165 Curing was performed by step curing at 2 ° C. for 2 hours and at 190 ° C. for 2 hours. From the obtained cured copper foil, only copper was removed by etching using a sodium persulfate solution to obtain a cured product of an elastomer-free B stage sheet. As a result of measuring the thermal conductivity of the obtained cured product by the xenon flash method in the same manner as in Example 1, the thermal conductivity was 8.8 W / mK.

3. Adhesion of non-elastomer-containing resin sheet to heat radiating member The PET film is peeled off from both sides of the non-elastomer-containing resin sheet (B stage sheet) obtained by the above-described method, and both sides are sandwiched between a copper plate and an aluminum plate, and vacuum hot press (heat Plate temperature 140 ° C, degree of vacuum ≤ 1 kPa, pressure 0.2 MPa, treatment time 10 minutes), then put into a box-type oven at 140 ° C for 2 hours, 165 ° C for 2 hours, 190 ° C for 2 hours Was cured. The shear bond strength of the metal workpiece on which the elastomer-free resin sheet thus obtained was affixed was measured in the same manner as in Example 1 and found to be 3.5 [MPa].

(Comparative Example 2)
Except that a silicone resin (trade name “X-22-162C” manufactured by Shin-Etsu Chemical Co., Ltd.) was used in place of “REB122-4” (acrylic resin), X- A B-stage sheet containing 22-162C was produced. When the flexibility of the obtained B-stage sheet was evaluated in the same manner as in Example 1, the sheet was fragile and judged as B.

For the obtained B stage sheet, a cured product was produced in the same manner as in Example 1. However, because of the brittleness, the thermal conductivity could not be measured.

Next, in the same manner as in Example 1, a metal workpiece on which a B-stage sheet containing X-22-162C was attached was produced. However, since the cured product was brittle, it could not be bonded to the metal, and the shear strength could not be measured. It was.

(Comparative Example 3)
Except that a nitrile resin (manufactured by ZEON Corporation, trade name “Nipol DN601”) was used instead of “REB122-4” (acrylic resin), B containing Nipol DN601 was the same as in Example 1. A stage sheet was prepared. When the flexibility of the obtained B-stage sheet was evaluated in the same manner as in Example 1, the sheet was fragile and judged as B.

For the obtained B stage sheet, a cured product was produced in the same manner as in Example 1. However, because of the brittleness, the thermal conductivity could not be measured.

Next, in the same manner as in Example 1, a metal workpiece on which a B stage sheet containing Nipol DN601 was affixed was produced. However, since the sheet was brittle, it could not be bonded to the metal, and the shear strength could not be measured.

Table 1 summarizes the examination results of the thermal conductivity and flexibility of the heat conductive sheets prepared in Examples 1 to 5 and Comparative Examples 1 to 3, and the shear bond strength of the metal workpiece using the sheets.

As can be seen from Table 1, it can be seen that the resin sheet composed of the heat conductive resin composition of the present invention is excellent in flexibility and adhesiveness. Moreover, it turns out that the resin sheet hardened | cured material is excellent in heat conductivity and adhesiveness.

The entire disclosure of Japanese Patent Application No. 2010-212022 is incorporated herein by reference.
All documents, patent applications, and technical standards mentioned in this specification are to the same extent as if each individual document, patent application, and technical standard were specifically and individually stated to be incorporated by reference, Incorporated herein by reference.

DESCRIPTION OF SYMBOLS 10 Resin sheet 20 1st metal workpiece 30 2nd metal workpiece 40 Support

Claims (11)

1. A thermally conductive resin composition comprising an epoxy resin, an inorganic filler, and an elastomer having at least a structural unit represented by the following general formula (I) in the molecule.
   

   

   
   (In the general formula (I), R ¹ , R ² and R ³ are each independently a linear or branched alkyl group or a hydrogen atom, and R ⁴ is a linear or branched alkyl group. , N represents an arbitrary integer)
2. The thermally conductive resin composition according to claim 1, wherein the elastomer is an acrylic resin.
3. The heat conductive resin composition according to claim 2, wherein the acrylic resin further has at least one of a carboxy group and a hydroxy group in the molecule.
4. The heat conductive resin composition according to claim 2 or 3, wherein the acrylic resin further has an amino group in the molecule.
5. The thermally conductive resin composition according to any one of claims 2 to 4, wherein the acrylic resin has a structure represented by the following general formula (II).
   

   

   
   (In the formula (II), symbols a, b, c and d described in each structural unit are the mol% of each structural unit in all structural units, and a + b + c + d = 90 mol% or more.
   R ²¹ and R ²² are each independently a linear or branched alkyl group having a different carbon number, and R ²³ to R ²⁶ are each independently a hydrogen atom or a methyl group. )
6. 6. The thermally conductive resin composition according to claim 5, wherein R ²¹ and R ²² in formula (II) are each independently a linear or branched alkyl group having 4 to 12 carbon atoms having different carbon numbers.
7. The heat conductive resin composition according to any one of claims 1 to 6, further comprising a phenolic curing agent.
8. A resin sheet obtained by molding the thermally conductive resin composition according to any one of claims 1 to 7 into a sheet shape.
9. A resin-coated metal foil comprising: a metal foil; and a semi-cured resin layer that is a semi-cured product of the thermally conductive resin composition according to any one of claims 1 to 7 disposed on the metal foil. .
10. A cured resin sheet, which is a heat-treated product of the thermally conductive resin composition according to any one of claims 1 to 7.
11. A heat dissipating member having a metal workpiece and the resin sheet according to claim 8 or the cured resin sheet according to claim 10 disposed on the metal workpiece.

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