JP2015059186A - Epoxy composition, and heat-conductive sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat-conductive sheet having an epoxy resin layer having excellent heat conductivity, and an epoxy composition suitable for the formation of such a heat-conductive sheet.SOLUTION: An epoxy composition comprises an epoxy monomer having a specific structure and a phenolic curing agent having a specific structure.

Description

  The present invention relates to an epoxy composition and a heat conductive sheet, and relates to an epoxy composition containing a curing agent together with an epoxy monomer, and a heat conductive sheet having an epoxy resin layer formed by the epoxy composition.

Conventionally, an epoxy composition containing an epoxy monomer and a curing agent has been used for sealing a semiconductor package.
The epoxy composition is widely used as a material for forming a prepreg sheet or the like by using a B-staged semi-cured product.
In recent years, epoxy resin moldings such as semiconductor packages and prepreg sheets have been required to exhibit excellent thermal conductivity. Boron nitride, aluminum oxide, and the like are used as epoxy compositions for forming the epoxy resin moldings. Inorganic fillers having excellent thermal conductivity are blended.

  In particular, a prepreg sheet in which an epoxy resin layer formed of an epoxy composition containing an inorganic filler at a high ratio is supported on a base sheet, or a prepreg sheet consisting only of the epoxy resin layer is a semiconductor module and a radiator. It is widely used as a heat conductive sheet interposed therebetween.

In general, the higher the inorganic filler is filled in this kind of epoxy composition, the more excellent the thermal conductivity of the epoxy resin molded body becomes. However, when the inorganic filler is excessively contained, the mechanical properties of the epoxy resin molded body are increased. There is a risk of damage to properties.
For example, the heat conductive sheet contains a large amount of an inorganic filler in the epoxy resin layer, and a reduction in the thickness of the epoxy resin layer is advantageous in reducing the thermal resistance in the thickness direction. In such a case, the epoxy resin layer may be easily broken.

Against this background, attempts have been made to improve the thermal conductivity of the epoxy resin itself.
For example, in the following Patent Document 1, in order to form an epoxy resin molded body having high thermal conductivity, an epoxy monomer having a mesogen skeleton is used, and a high magnetic field is applied in one direction to form an epoxy resin molded body. Is described.
The epoxy resin having such a mesogenic skeleton easily forms a crystallized portion with a uniform molecular chain in the molded body, and the crystallized portion exhibits higher thermal conductivity than other amorphous portions. It is more advantageous than general epoxy resins in forming an epoxy resin molded article having an excellent rate.

  However, it is not preferable from the viewpoint of productivity or the like to produce a molded body such as a heat conductive sheet by a special manufacturing method described in Patent Document 1.

Japanese Patent No. 4414674

  It is an object of the present invention to provide an epoxy composition suitable for the formation of such a heat conductive sheet in order to provide a heat conductive sheet that can exhibit excellent heat conductivity without significantly limiting the production method. It is said.

  This invention which concerns on the epoxy composition for solving such a subject contains the epoxy monomer represented by following General formula (1), and the phenol type hardening | curing agent represented by following General formula (2). It is characterized by.

(However, “Ph ¹ ” and “Ph ² ” in the formula are represented by the following general formula (x)

(However, “R ¹ ” in the formula represents a hydrocarbon group having 1 to 6 carbon atoms or a methoxy group.)
Or “Ph ¹ ” and “Ph ² ” may be the same as or different from each other. )

(However, “R ² ” is any one of a hydroxyl group, a methyl group, an ethyl group, a propyl group, or a hydrogen atom, and “Ph ³ ”, “Ph ⁴ ”, and “Ph ⁵ ” are common to each other. Or may be different, the following general formula (y)

(However, “R ³ ” to “R ⁷ ” in the formula are any of a hydroxyl group, a methyl group, an ethyl group, a propyl group, or a hydrogen atom.)
And at least two of the “Ph ³ ”, “Ph ⁴ ” and “Ph ⁵ ” are substituted phenyls having a hydroxyl group. )

  Moreover, this invention which concerns on the heat conductive sheet for solving the said subject is a heat conductive sheet which has an epoxy resin layer, Comprising: The epoxy monomer represented by the said General formula (1), and the said General formula (2) The epoxy resin layer is formed of an epoxy composition further including an inorganic filler.

Since the epoxy composition of this invention contains the specific epoxy monomer with the specific hardening | curing agent, the hardened | cured material which has high thermal conductivity can be formed with the said hardening | curing agent and an epoxy monomer.
Therefore, according to this invention, the heat conductive sheet which has an epoxy resin layer excellent in heat conductivity can be provided.

The schematic sectional drawing which showed the cross-section of the heat conductive sheet of one Embodiment. FIG. 2 is a schematic cross-sectional view of a semiconductor module schematically showing a usage state of the heat conductive sheet of FIG. 1. The schematic cross-sectional view of a semiconductor module schematically showing a usage state of a heat conductive sheet of another embodiment.

Below, preferable embodiment of the heat conductive sheet of this invention is described.
The heat conductive sheet of this embodiment has an epoxy resin layer formed of a predetermined epoxy composition.
The epoxy composition of this embodiment contains a specific epoxy monomer and a phenolic curing agent, so that the epoxy resin layer contains only an epoxy resin that does not contain an inorganic filler or the like, and the epoxy resin layer has 0.3 W / (m · K) or more. It can exhibit excellent thermal conductivity.
In addition, the thermal conductive sheet in the present embodiment exhibits the excellent thermal conductivity as described above in the epoxy resin layer without performing a special operation such as applying a high magnetic field when the epoxy resin layer is formed. It can be made.

First, the epoxy composition used for forming the epoxy resin layer will be described.
The epoxy composition in the present embodiment contains an epoxy monomer represented by the following general formula (1) and a phenolic curing agent represented by the following general formula (2).

(However, “Ph ¹ ” and “Ph ² ” in the formula are represented by the following general formula (x)

(However, “R ¹ ” in the formula represents a hydrocarbon group having 1 to 6 carbon atoms or a methoxy group.)
Or “Ph ¹ ” and “Ph ² ” may be the same as or different from each other. )

(However, “R ² ” is any one of a hydroxyl group, a methyl group, an ethyl group, a propyl group, or a hydrogen atom, and “Ph ³ ”, “Ph ⁴ ”, and “Ph ⁵ ” are common to each other. Or may be different, the following general formula (y)

(However, “R ³ ” to “R ⁷ ” in the formula are any of a hydroxyl group, a methyl group, an ethyl group, a propyl group, or a hydrogen atom.)
And at least two of the “Ph ³ ”, “Ph ⁴ ” and “Ph ⁵ ” are substituted phenyls having a hydroxyl group. )

  The epoxy composition in the present embodiment further contains a curing accelerator and an inorganic filler.

In the epoxy monomer, “Ph ¹ ” and “Ph ² ” in the general formula (1) are paraphenylene.
In the present embodiment, the “Ph ¹ ” is preferably unsubstituted phenylene.
In addition, the “Ph ² ” is preferably a substituted phenylene in which one of four hydrogen atoms is substituted with a methoxy group, and a carbon atom adjacent to a carbon atom that is ether-bonded to a glycidyl group. The methoxy group is preferably bonded.

  That is, it is particularly preferable that the epoxy monomer has a structure represented by the following general formula (3).

It is important to employ a phenolic curing agent having a structure represented by the general formula (2).
It is important that the phenolic curing agent has two or more phenyl groups having a hydroxyl group, and all phenyls (“Ph ³ ”, “Ph ⁴ ” and “Ph ⁵ ”) have a hydroxyl group. Is preferred.
Further, examples of the phenolic curing agent, it is preferable that the number of hydroxyl groups of the phenyl ( "Ph ^3" ~ "Ph ^5") is 1 or 2.
Moreover, as said phenol type hardening | curing agent, it is preferable that each phenyl does not have substituents other than a hydroxyl group (it is preferable that other than a hydroxyl group is a hydrogen atom).
That is, it is preferable that the said phenol type hardening | curing agent in this embodiment is 4,4 ', 4 "-methylidyne trisphenol etc. which are shown to following General formula (4), for example.

Depending on the blending ratio with the epoxy monomer and the presence or absence of other blending materials such as a curing accelerator, the epoxy composition of the present embodiment adopts a preferable phenol-based curing agent as described above to achieve a glass transition. A cured product having a temperature of 150 ° C. or higher can be formed.
That is, in order to form an epoxy resin layer having excellent heat resistance, it is preferable to employ a phenolic curing agent such as 4,4 ′, 4 ″ -methylidynetrisphenol in the epoxy composition of this embodiment. .

  The phenolic curing agent is usually contained in the epoxy composition so that the number of hydroxyl groups is substantially the same as the number of glycidyl groups of the epoxy monomer (for example, a ratio between 0.8 times to 1.25 times). Can be made.

  In addition, the epoxy composition of the present embodiment includes other phenolic curing agents, amine curing agents, acid anhydride curing agents, polymercaptan curing agents, polyaminoamide curing agents, and isocyanate curing agents, if necessary. Further, a blocked isocyanate curing agent and the like may be contained within a range in which the effects of the present invention are not significantly impaired.

Moreover, the epoxy composition of the present embodiment contains a curing accelerator together with the phenolic curing agent, and examples of the curing accelerator include onium salts such as a phosphonium salt-based curing accelerator and a sulfonium salt-based curing accelerator. It is preferable to contain a system curing accelerator.
Since many of the phenolic curing agents shown above have a softening temperature exceeding 200 ° C., those that do not exhibit excessive catalytic activity at temperatures of 200 ° C. or less are preferable as curing accelerators to be included in the epoxy composition.
Therefore, the epoxy composition of the present embodiment contains a phosphonium salt-based curing accelerator such as a tetraphenylphosphonium salt-based curing accelerator or a triphenylphosphonium salt-based curing accelerator as the onium salt-based curing accelerator. Is particularly preferable, and it is most preferable to contain tetraphenylphosphonium tetraphenylborate.
The onium salt-based curing accelerator such as tetraphenylphosphonium tetraphenylborate can usually be contained in the epoxy composition so that the ratio with respect to 100 parts by mass of the epoxy monomer is 0.1 parts by mass or more and 5 parts by mass or less. .

The epoxy composition of this embodiment further contains an inorganic filler having excellent thermal conductivity in order to make the epoxy resin layer excellent in thermal conductivity as described above.
Examples of the inorganic filler include particles, plates and fibers made of metal, metal oxide, metal nitride, metal carbide, metal hydroxide, carbon, metal-coated resin, and the like.
Examples of the metal include silver, copper, gold, platinum, and zirconium, examples of the metal oxide include aluminum oxide and magnesium oxide, examples of the metal nitride include boron nitride, aluminum nitride, and silicon nitride. Examples of the metal carbide include silicon carbide and the like. Examples of the metal hydroxide include aluminum hydroxide and magnesium hydroxide, and examples of the carbon include carbon black, graphite, carbon nanotube, and carbon nanohorn.

When the inorganic filler is contained in the epoxy composition of the present embodiment, the inorganic filler is contained so that the volume ratio of the inorganic filler in the cured product of the epoxy composition is usually 30% by volume or more and 90% by volume or less. Can be made.
The epoxy composition of the present embodiment preferably contains either boron nitride particles or aluminum nitride particles as the inorganic filler.

  In addition, the epoxy composition contains pigments, dyes, fluorescent brighteners, dispersants, stabilizers, ultraviolet absorbers, antistatic agents, antioxidants, flame retardants, heat stabilizers, lubricants, plasticizers, as necessary. It is also possible to appropriately contain a solvent or the like.

The thermally conductive sheet in the present embodiment can be formed by forming only the above epoxy composition into a sheet or laminating it on another sheet-like member.
In the case where not only heat conduction but also electrical insulation is required for the heat conductive sheet, the heat conductive sheet is provided with two or more epoxy resin layers laminated, and the It is preferable to separately provide a base material layer for supporting the epoxy resin layer.

  Hereinafter, as an example showing one embodiment of the thermally conductive sheet in the present embodiment, a thermally conductive insulating sheet will be described with reference to the drawings.

The thermally conductive sheet (hereinafter also referred to as “insulating sheet”) of the present embodiment has two epoxy resin layers 11 and 12 (hereinafter also referred to as “insulating layers”), as shown in FIG. And a base material layer 13 for supporting the insulating layers 11 and 12.
That is, the insulating sheet 10 of the present embodiment is a sheet body having a three-layer laminated structure, and the first insulating layer 11 (hereinafter referred to as “first insulating layer 11”) of the two insulating layers 11 and 12. The other side is constituted by the base material layer 13 and the intermediate layer between the base material layer 13 and the first insulating layer 11 is the second insulating layer 12 (hereinafter also referred to as the other side). , Also referred to as “second insulating layer 12”).

The 1st insulating layer 11 and the 2nd insulating layer 12 consist of the epoxy composition of this embodiment, and consist of the said epoxy composition made into B-stage (semi-hardened).
The epoxy composition of this embodiment exhibits excellent thermal conductivity even with an epoxy cured product alone, but these insulating layers 11 and 12 are formed of the epoxy composition containing an inorganic filler. It is formed so as to exhibit even more excellent thermal conductivity.
In addition, when it is going to make high filling with an inorganic filler in order to exhibit the outstanding heat conductivity with respect to the 1st insulating layer 11 and the 2nd insulating layer 12, the said insulating layers 11 and 12 will become weak and will be careful with respect to an insulating sheet. However, the insulating sheet 1 of the present embodiment suppresses cracking and cracking of the insulating layers 11 and 12 by providing the base material layer 13.
In particular, in a semi-cured state containing an unreacted epoxy group called a B stage, unlike the case where the unreacted epoxy group is cured so as to be in a state called a C stage that does not substantially exist in the system. Since the insulating layers 11 and 12 are easily broken even by slight deformation, it can be said that the base material layer 13 plays an important role in the insulating sheet 1 of the present embodiment.

In addition, if an attempt is made to highly fill the inorganic filler, defects such as pinholes and voids are likely to be formed in the insulating layers 11 and 12, but the insulating sheet 10 of the present embodiment is temporarily formed by stacking two insulating layers. Even when a defective portion is formed, the defect is prevented from being continuous in the thickness direction of the insulating sheet.
That is, the electrical reliability of the insulating sheet 10 of this embodiment is ensured by making the insulating layer a laminated structure and by supporting the insulating layer by the base material layer 13.

The first insulating layer 11 and the second insulating layer 12 preferably have a total volume resistivity of 1 × 10 ¹³ Ω · cm or more so that the insulating sheet 10 can exhibit excellent electrical insulation. More preferably, it is 1 × 10 ¹⁴ Ω · cm or more.
The first insulating layer 11 and the second insulating layer 12 also preferably have an individual volume resistivity of 1 × 10 ¹³ Ω · cm or more, and more preferably 1 × 10 ¹⁴ Ω · cm or more.

In addition, the first insulating layer 11 and the second insulating layer 12 have a thermal conductivity when the epoxy composition is sufficiently cured (C-staged) in order to exhibit excellent thermal conductivity in the insulating sheet 10. It is preferable that the kind and blending amount of the inorganic filler is adjusted so that the rate is 5 W / m · K or more, and the inorganic filler is contained in a proportion of 30% by volume to 90% by volume. preferable.
In addition, about the heat conductivity of the molded object formed with the epoxy composition, it can measure with a xenon flash analyzer (For example, the product made from NETZSCH, "LFA-447 type") normally.
This thermal conductivity can be measured by other laser flash methods or TWA methods without using a xenon flash analyzer. For example, the laser flash method is measured using “TC-9000” manufactured by ULVAC-RIKO. can do.
And in TWA method, it can measure using "ai-Phase mobile" by an eye phase company.

In order to make the insulating sheet 10 exhibit excellent thermal conductivity as described above, the inorganic filler contained in the first insulating layer 11 and the second insulating layer 12 may be boron nitride particles or aluminum nitride particles. preferable.
Boron nitride particles have a hexagonal plate-like particle shape as a primary particle in a general production method, but aggregated particles in which a plurality of hexagonal plate-like primary particles form an aggregate are also inorganic. The filler is commercially available, and the aggregated particles are particularly preferable as the inorganic filler contained in the epoxy composition of the present embodiment.

When the epoxy composition for forming the first insulating layer 11 and the second insulating layer 12 contains boron nitride particles as an inorganic filler, the boron nitride particles are more resinous than aluminum oxide particles or silicon oxide particles. Since it is difficult to exert an excellent cohesive force with respect to the first insulating layer 11 and the second insulating layer 12 only with boron nitride particles, the first insulating layer 11 and the second insulating layer 12 are excellent. If adhesiveness is required, it is preferable to contain metal oxide particles such as aluminum oxide particles and silicon oxide particles.
In addition, when making the 1st insulating layer 11 and the 2nd insulating layer 12 exhibit heat conductivity and adhesiveness with sufficient balance, the total amount of the inorganic filler which occupies for the 1st insulating layer 11 and the 2nd insulating layer 12 is 40. It is preferable to set it as volume%-70 volume%.
Moreover, in order to make the 1st insulating layer 11 and the 2nd insulating layer 12 exhibit heat conductivity and adhesiveness with sufficient balance, the said metal oxide particle and the said nitriding in the 1st insulating layer 11 and the 2nd insulating layer 12 are carried out. The volume ratio with the boron particles is preferably 0.5: 99.5 to 50:50.
Further, the metal oxide particles preferably have a median diameter of 0.1 μm to 30 μm determined by measurement with a laser diffraction / scattering particle size distribution meter.

The first insulating layer 11 and the second insulating layer 12 do not need to be formed of the same epoxy composition, and further, the thicknesses of the first insulating layer 11 and the second insulating layer 12 do not need to be made common.
The thicknesses of the first insulating layer 11 and the second insulating layer 12 can usually be about 25 μm to 300 μm.

  In addition, about the said base material layer 13, it can form with the polymer film, metal foil, fiber sheet, etc. which have thickness of 5 micrometers-500 micrometers normally.

  In the case of the polymer film, for example, polyester resins such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polylactic acid, and polyarylate; polyolefin resins such as polyethylene and polypropylene; polyamide 6, polyamide 6, 6 Aliphatic polyamide resins such as polyamide 11, polyamide 12; aromatic polyamide resins such as poly-p-phenylene terephthalamide and poly-m-phenylene isophthalamide; chlorinated resins such as polyvinyl chloride and polyvinylidene chloride; Fluoroethylene, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, tetrafluoroethylene-hexafluoropropylene copolymer, tetrafluoroethylene-ethylene copolymer Polyimide resins; polycarbonate resins, acrylic resins, polyphenylene sulfide resins; polyurethane resins; polymer, fluorine-based resins such as polyvinylidene fluoride resin film made of a polyvinyl alcohol resin can be used in the formation of the base layer 13.

Moreover, if it is the said metal foil, the base material layer 13 can be formed with metal foil which consists of metals, such as copper, aluminum, nickel, iron, and its alloy.
The metal foil may be a clad foil formed by bonding different metals or a plating foil plated with different metals.

  Furthermore, if it is the said fiber sheet, a polyester fiber nonwoven fabric, a pulp sheet, a glass mat, a carbon fiber sheet, etc. are employ | adopted and the said base material layer 13 can be formed.

  In addition, the base material layer can be formed by a sheet in which these are combined, for example, by using a laminated film in which a metal foil such as an aluminum laminated resin film and a polymer film are laminated. it can.

Specific examples of the usage method of the insulating sheet 10 include a usage method as a constituent member of a semiconductor module as shown in FIGS.
First, the usage method of the insulating sheet 10 is demonstrated based on FIG.
FIG. 2 is a schematic view showing a cross section of a semiconductor module. The semiconductor module 100 includes a semiconductor element 30 and a metal plate 40 that functions as a heat sink for the semiconductor element 30 and is disposed in a flat position. The semiconductor element 30 is fixed to the upper surface side of the metal plate 40 by solder 50.
The semiconductor element 30 is smaller than the area of the upper surface of the metal plate 40. In the present embodiment, the semiconductor element 30 is mounted on the metal plate in a bare chip state.

And the said insulating sheet 10 of this embodiment is distribute | arranged to the lower surface of the metal plate 40 used as the opposite side to the side in which this semiconductor element 30 is mounted.
That is, the insulating sheet 10 is used to form the semiconductor module 100 by bonding the first insulating layer 11 to the other surface of the metal plate 40 on which the semiconductor element 30 is mounted on one surface.
The insulating sheet 10 of the present embodiment has a shape corresponding to the lower surface of the metal plate 40 in a plan view, and the lower surface outer edge 40e of the metal plate 40 and the outer edge of the first insulating layer 11 are aligned. It is bonded to the lower surface of the metal plate 40.

The semiconductor module 100 of this embodiment has a rectangular tube-shaped case 60 that forms an outer shell thereof. The shape of the case 60 is slightly larger than that of the metal plate 40 in a plan view, and the shape in a front view. However, the insulating sheet 10, the metal plate 40, and the semiconductor element 30 are formed to be higher than the total height.
That is, the case 60 has a size capable of including all of the insulating sheet 10, the metal plate 40, and the semiconductor element 30.
The semiconductor module 100 has the case 60 disposed so as to surround the metal plate 40, and further includes a lead frame 70 that penetrates the side wall of the case 60 and extends inside and outside the case.

Further, in the semiconductor module 100, an end portion of the lead frame 70 in the case and the semiconductor element 30 are electrically connected by a bonding wire 80, and an empty space in the case is filled with sealing resin. The mold part 90 is formed.
The mold part 90 is formed so that the semiconductor element 30, the metal plate 40, and the insulating sheet 10 are embedded and the lower surface side of the insulating sheet 10 is exposed.
That is, the mold part 90 is formed so that the lower surface is substantially flush with the lower surface of the base material layer 13.

The semiconductor module 100 of the present embodiment is sealed when the mold portion 90 is formed when the upper surface of the first insulating layer 11 that is a B-staged epoxy resin layer is bonded to the lower surface of the metal plate 40. Utilizes the heat and pressure of the resin.
That is, before the formation of the mold part 90, the metal plate 40 and the insulating sheet 10 are not temporarily bonded to each other, or are not bonded at all. In this case, the first insulating layer 11 and the lower surface of the metal plate 40 are brought into pressure contact with each other when the sealing resin heated and melted to form the mold part 90 is pressurized and filled in the case, so that the metal plate is heated. 40 is bonded and fixed.

Further, the insulating sheet 10 is finally made into a C-stage by forming the first insulating layer 11 and the second insulating layer 12 by heat when forming the mold portion 90 and additional heating performed as necessary. The semiconductor module 100 is provided.
In this way, the insulating sheet 10 constituting a part of the semiconductor module 100 exposes only the lower surface side of the base material layer 13 on the lower surface of the semiconductor module 100 here.
The insulating sheet 10 of the present embodiment has the base material layer 13 formed of a metal foil, and the exposed surface of the metal foil is provided in the semiconductor module 100 so as to be used as a main heat dissipation surface of the semiconductor module 100. Yes.

As described above, in the semiconductor module 100, the semiconductor element 30 is directly mounted on the metal plate 40, and the semiconductor element 30 and the metal plate 40 have substantially the same potential.
Therefore, the insulating sheet 10 forms a good heat transfer path between the metal plate 40 and the heat radiating surface, and the metal module 40 is connected to the semiconductor module 100 so as to be disconnected from the outside. Is provided.

  Since the insulating sheet 10 of the present embodiment has excellent electrical insulation and thermal conductivity, it is possible to suppress an excessive increase in the junction temperature of the semiconductor element 30 during the operation of the semiconductor module 100, and the semiconductor module It can prevent 100 failures and prolong the service life.

Such an effect is not limited to the embodiment illustrated in FIG. 2 but also in the semiconductor module illustrated in FIG.
This will be described with reference to FIG.
3 is a schematic diagram showing a cross section of the semiconductor module as in FIG. 2. In FIG. 3, the components denoted by the same reference numerals as those in FIG. 2 are the same as those in FIG. The explanation will not be repeated more than necessary.

  The semiconductor module 100 ′ shown in FIG. 3 is an epoxy resin layer single layer sheet body in which the insulating sheet 10 ′ does not have a laminated structure, and an epoxy composition containing an inorganic filler is B-staged. It differs from the semiconductor module 100 of FIG. 2 in a certain point.

  In addition, the semiconductor module 100 ′ has an insulating sheet 10 ′ formed in the same shape as the planar shape of the case 60 ′, and the mold part 90 ′ is substantially flush with the lower surface of the metal plate 40 ′. It differs from the semiconductor module 100 of FIG. 2 also in the point formed.

  The insulating sheet 10 ′ is used by being adhered to the lower surface of the module main body 100x ′, which is the main part of the semiconductor module 100 ′ excluding the insulating sheet 10 ′, and insulates the metal plate 40 ′ to provide a semiconductor. Used to configure module 100 '.

  Further, as shown in FIG. 3, the insulating sheet 10 ′ is used by being interposed between the module main body 100x ′ and the radiator 20 ′. For example, the upper surface is lower than the lower surface of the metal plate 40 ′. The upper surface of the substrate portion of the radiator 20 ′ and the module body having a plate-like substrate portion 21 ′ having a large flat surface and fin portions 22 ′ in which a plurality of fins are suspended from the lower surface of the substrate portion 21 ′. It is used for bonding to the lower surface of the portion 100x ′.

In addition, when forming a semiconductor module with a radiator as shown in FIG. 3 using the insulating sheet 10 ′, the insulating sheet 10 ′ is first bonded to the module main body side to temporarily form the shape of the semiconductor module 100 ′. The heat sink 20 'may be further bonded using the insulating sheet 10' after completing the process, and conversely, the insulating sheet 10 'is once bonded to the upper surface of the substrate portion of the heat radiator 20' to provide an insulating layer. After the heatsink is manufactured, the heatsink with an insulating layer may be adhered to the module body 100x ′.
Further, the insulating sheet 10 ′ is bonded to the module body 100x ′ and the radiator 20 ′ at the same time by, for example, hot pressing the insulating sheet 10 ′ between the module body 100x ′ and the radiator 20 ′. You may do it.

Even in such a case, since the C-staged insulating sheet 10 ′ exhibits excellent electrical insulation and thermal conductivity, the semiconductor module 100 ′ including the insulating sheet 10 ′ as a constituent member has a useful life. Can be prolonged.
Here, detailed description will not be repeated any more. For example, in the embodiment illustrated in FIG. 3, the insulating sheet 10 ′ has two or more insulating layers as illustrated in FIGS. It is also possible to have a base material layer other than the insulating layer.

The epoxy composition of the present invention is not only used as a material for forming an insulating sheet, but can also be used for forming the mold parts 90, 90 ′, the cases 60, 60 ′, etc. Naturally, the epoxy resin molded body of the invention can have various aspects other than those described above.
The embodiment of the heat conductive sheet of the present invention is not limited to the insulating sheet as described above.
In addition, about the epoxy composition and heat conductive sheet of this invention, it is possible to employ | adopt suitably a conventionally well-known technical matter in the range which the effect of this invention is not impaired remarkably.

  EXAMPLES Next, although an Example is given and this invention is demonstrated in more detail, this invention is not limited to these.

<Preparation of epoxy composition>
The following materials were prepared to adjust the evaluation epoxy composition.

(Epoxy A): Substance represented by the following general formula (3) having an epoxy equivalent of 224 g / eq

(Epoxy B): Substance represented by the following general formula (5) having an epoxy equivalent of 167 g / eq)

（ただし、式中の「ｎ」は、１〜３の正数を表す。）

(However, “n” in the formula represents a positive number of 1 to 3.)

(Phenol C): 4,4 ', 4 "-methylidynetrisphenol represented by the following general formula (4) having a hydroxyl group equivalent of 97 g / eq

(Phenol D): A substance represented by the following general formula (6) having a hydroxyl group equivalent of 105 g / eq

(Curing accelerator E): Tetraphenylphosphonium tetraphenylborate (TPPK)
(Silane coupling agent F): Phenyltrimethoxysilane (inorganic filler G): Boron nitride aggregated particles (manufactured by Mizushima Alloy Iron Company, trade name “HP-40”)
(Inorganic filler H): Aluminum nitride particles (manufactured by Furukawa Denshi, trade name “f-50J”)

<Production of test piece 1>
Example 1
The “epoxy A” and the “phenol P” are obtained by changing the number of epoxy groups (EX) by “epoxy A” and the number of hydroxyl groups (OH) by “phenol C” to 1: 1 (EX: OH). The “curing accelerator E” was blended so that the ratio to 100 parts by mass of “epoxy A” was 1 part by mass.
An epoxy solution was prepared by adding cyclopentanone so that the proportion of the total of the blends (“epoxy A”, “phenol C”, and “curing accelerator E”) was 30% by mass.
This epoxy solution was poured into an aluminum cup and heated to a temperature of about 100 ° C. to remove the solvent (cyclopentanone) to produce a dry solid.
Next, this dried solid was placed on a glass plate and stored in a vacuum chamber at 140 ° C. for 10 minutes to melt and degas.
Place a spacer around this glass plate, and put another glass plate on it, and allow it to fully react with “epoxy A” and “phenol C” while being stored in a dryer at 180 ° C. for 3 hours, A sheet-like cured body having a thickness of 0.45 mm was produced.
It was 0.32 W / m * K as a result of measuring the heat conductivity of this hardening body.

Next, the blending ratio of “epoxy A”, “phenol C” and “curing accelerator E” was the same as described above, and a heat conductive sheet was prepared using an epoxy composition containing an inorganic filler.
In the following, the term “parts by mass” means a mass ratio with respect to a total of 100 parts by mass of “epoxy A” and “phenol C”, unless otherwise specified.
First, the silane coupling treatment of the inorganic filler was performed so that the ratio of the silane coupling agent to 100 parts by mass of the inorganic filler was 1.5 parts by mass.
That is, as shown in Table 1, after weighing 246.02 parts by mass of “inorganic filler G (BN)” and placing it in a bag, 3.69 parts by mass of “silane coupling agent F” was added. Mix and stir in the bag.
Similarly, “inorganic filler H (AlN)” is weighed so that the ratio of “epoxy A” and “phenol C” to 100 parts by mass in total is 88.72 parts by mass, and this is stored in a bag. 1.33 parts by mass of “silane coupling agent F” was added and mixed and stirred in the bag.
And this "inorganic filler G" and "inorganic filler H" were left still for 2 days or more with the state accommodated in the bag, respectively, and the silane coupling process was performed.

Next, 269.74 parts by mass of cyclopentanone was prepared, and 5.24 parts by mass of a silica-based thickener was added thereto. Furthermore, “Epoxy A” 69.7 parts by mass, “Phenol C” 30.3 parts by mass After adding 0.7 part by mass of “curing accelerator E”, this was set in a hot stirrer and mixed and stirred at a temperature of about 70 ° C.
Finally, the filler subjected to the coupling treatment was added to prepare a coating solution.
A surface-roughened polyethylene terephthalate resin (PET) film was set on a table so that the roughened surface was facing upward, and the coating solution was applied thereto using an applicator for a thickness of 200 μm.
A sample sheet in which an epoxy resin layer is formed on a PET film by containing the PET film coated with this coating solution in a dryer at 130 ° C. for 10 minutes to volatilize and remove cyclopentanone from the coating film. Obtained.
Four pieces of approximately square sheet pieces each having a side of 50 mm were cut out from this sample sheet, and two of them were superposed so that the coating film was on the inside, and bonded by hot pressing.
Further, the remaining two sheet pieces were similarly bonded by hot pressing.
In addition, the hot press at this time is such that a pressure of 10 MPa is applied in the thickness direction to the two pieces of the stacked sheets, and the temperature is made constant when the temperature reaches 130 ° C. by heating from room temperature, The cooling was carried out when 20 minutes had passed since the start of heating.
Moreover, in this hot press, pressurization was continued during cooling, and cooling in the pressurized state was performed for 20 minutes or more.

The PET films were removed from one side of each of the two laminated sheets (PET film / epoxy resin layer / epoxy resin layer / PET film four-layer laminate) thus obtained, and the epoxy resin layers exposed on the surface were mutually exposed. The samples were stacked so as to contact each other and heat-pressed again to prepare a sample for thermal conductivity measurement.
The heat press at this time is such that a pressure of 5 MPa is applied to the two laminated sheets in the thickness direction, the temperature is constant when the temperature reaches 180 ° C. when heated from room temperature, and heating is started. Cooling was performed at the time when 60 minutes passed later, and the epoxy composition constituting the epoxy resin layer was cured almost completely.
Moreover, also in this hot press, pressurization was continued during cooling, and cooling in the pressurized state was performed for 20 minutes or more.
Finally, the outer PET film was removed from the hot-pressed sheet to obtain a thermally conductive sheet in which four epoxy resin layers were laminated, and this thermally conductive sheet was used as a sample for measuring thermal conductivity.

About the heat conductivity of this heat conductive sheet (4 layer lamination | stacking sample), it shows in Table 1 with the measurement result about the sheet | seat which does not contain the said inorganic filler.
The thermal conductivity is measured by a xenon flash analyzer “LFA-447 type” (manufactured by NETZSCH).

(Example 2, Comparative Examples 1-4)
A sample was prepared in the same manner as in Example 1 except that the composition of the epoxy composition was changed as shown in Table 1, and the thermal conductivity was measured.
The results are also shown in Table 1.

  From the above, it can be seen that the present invention can provide a thermally conductive sheet excellent in thermal conductivity and an epoxy composition suitable for forming such a thermally conductive sheet.

  10: Thermally conductive sheet (insulating sheet), 11: Epoxy resin layer (first insulating layer), 12: Epoxy resin layer (second insulating layer), 30: Semiconductor element, 40: Metal plate, 100: Semiconductor module

Claims (8)

An epoxy composition comprising an epoxy monomer represented by the following general formula (1) and a phenolic curing agent represented by the following general formula (2).

(However, “Ph ¹ ” and “Ph ² ” in the formula are represented by the following general formula (x)

(However, “R ¹ ” in the formula represents a hydrocarbon group having 1 to 6 carbon atoms or a methoxy group.)
Or “Ph ¹ ” and “Ph ² ” may be the same as or different from each other. )

(However, “R ² ” is any one of a hydroxyl group, a methyl group, an ethyl group, a propyl group, or a hydrogen atom, and “Ph ³ ”, “Ph ⁴ ”, and “Ph ⁵ ” are common to each other. Or may be different, the following general formula (y)

(However, “R ³ ” to “R ⁷ ” in the formula are any of a hydroxyl group, a methyl group, an ethyl group, a propyl group, or a hydrogen atom.)
And at least two of the “Ph ³ ”, “Ph ⁴ ” and “Ph ⁵ ” are substituted phenyls having a hydroxyl group. )   The epoxy composition according to claim 1, further comprising an onium salt-based curing accelerator.   The epoxy composition according to claim 2, wherein the onium salt-based curing accelerator is a phosphonium salt-based curing accelerator. A thermally conductive sheet having an epoxy resin layer,
The epoxy resin layer is formed of an epoxy composition containing an epoxy monomer represented by the following general formula (1) and a phenolic curing agent represented by the following general formula (2), and further containing an inorganic filler. The heat conductive sheet characterized by the above-mentioned.

(However, “Ph ¹ ” and “Ph ² ” in the formula are represented by the following general formula (x)

(However, “R ¹ ” in the formula represents a hydrocarbon group having 1 to 6 carbon atoms or a methoxy group.)
Or “Ph ¹ ” and “Ph ² ” may be the same as or different from each other. )

(However, “R ² ” is any one of a hydroxyl group, a methyl group, an ethyl group, a propyl group, or a hydrogen atom, and “Ph ³ ”, “Ph ⁴ ”, and “Ph ⁵ ” are common to each other. Or may be different, the following general formula (y)

(However, “R ³ ” to “R ⁷ ” in the formula are any of a hydroxyl group, a methyl group, an ethyl group, a propyl group, or a hydrogen atom.)
And at least two of the “Ph ³ ”, “Ph ⁴ ” and “Ph ⁵ ” are substituted phenyls having a hydroxyl group. )   The heat conduction according to claim 4, wherein the epoxy resin layer contains boron nitride particles or aluminum nitride particles as the inorganic filler, and the inorganic filler is contained in a proportion of 30% by volume to 90% by volume. Sex sheet.   The thermally conductive sheet according to claim 4 or 5, wherein the epoxy composition forming the epoxy resin layer further contains an onium salt curing accelerator.   The thermally conductive sheet according to claim 6, wherein the onium salt-based curing accelerator is a phosphonium salt-based curing accelerator.   Used as a component of a semiconductor module including a semiconductor element and further including a metal plate as a heat sink for the semiconductor element, and bonding the epoxy resin layer to the other surface side of the metal plate on which the semiconductor element is mounted The heat conductive sheet according to any one of claims 4 to 7, wherein the heat conductive sheet is used.

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