JP7679677B2 - Phenoxy resin, thermosetting resin composition, thermally conductive sheet, resin substrate, laminate, and electronic device - Google Patents

Description

The present invention relates to a phenoxy resin, a thermosetting resin composition containing the same, and a resin sheet, a resin substrate, and a circuit board produced from the thermosetting resin composition. More specifically, the present invention relates to a phenoxy resin that can be used as a highly thermally conductive material and its uses.

As semiconductors become more highly integrated and the processing power of electronic devices rapidly improves, electronic components with high processing power generate a lot of heat. For this reason, heat countermeasures that effectively dissipate heat from electronic components to the outside have become a very important issue. As a countermeasure for such heat dissipation, thermally conductive members made of heat dissipating materials such as metals, ceramics, and polymer compositions are used for heat dissipation components such as printed wiring boards, semiconductor packages, housings, heat pipes, heat sinks, and heat diffusion plates.

Among these heat dissipation components, thermally conductive epoxy resin molded products made from epoxy resin compositions have excellent electrical insulation, mechanical properties, heat resistance, chemical resistance, adhesive properties, etc., and are therefore widely used primarily in the electrical and electronics fields as castings, laminates, sealing materials, thermally conductive sheets, adhesives, etc.

The epoxy resin composition that constitutes the thermally conductive epoxy resin molding is known to be a mixture of a polymer matrix material such as resin or rubber with a thermally conductive filler having high thermal conductivity. Thermally conductive fillers that can be used include metal oxides such as aluminum oxide, magnesium oxide, zinc oxide, and quartz, metal nitrides such as boron nitride and aluminum nitride, metal carbides such as silicon carbide, metal hydroxides such as aluminum hydroxide, metals such as gold, silver, and copper, carbon fiber, and graphite.

When even higher thermal conductivity is required, thermally conductive epoxy resin compositions and thermally conductive epoxy resin molded bodies in which special thermally conductive fillers are blended with epoxy resin have been proposed (for example, Patent Document 1). It has also been proposed to improve the thermal conductivity and heat resistance of the epoxy resin itself (for example, Patent Document 2). In Patent Document 2, an insulating composition with improved thermal conductivity is obtained by polymerizing a liquid crystal epoxy resin having a mesogenic group.

JP 2015-193504 A Patent Application No. 2004-331811

However, as a result of the inventor's investigations, it was found that the resin composition described in Patent Document 2 has room for further improvement in terms of thermal conductivity.

The present invention was made in consideration of the above problems, and the inventors discovered that a new phenoxy resin with a specific structure has high thermal conductivity, leading to the completion of the present invention.

According to the present invention,
A bifunctional epoxy compound (A) having two epoxy groups;
A phenoxy resin obtained by reacting a polyfunctional phenol compound (B) having at least two phenolic hydroxyl groups with
The bifunctional epoxy compound (A) includes a compound represented by the formula (d-EP),

In the formula (d-EP), X represents a divalent group having a mesogenic skeleton,
The polyfunctional phenol compound (B) is at least one selected from the compounds represented by formulas (p1) to (p8),

In the formulas (p1) to (p8), R ¹¹ and R ¹² independently represent a hydrogen atom, an alkoxy group having 1 to 4 carbon atoms, or a linear or branched alkyl group having 1 to 4 carbon atoms.

The present invention also provides a thermosetting resin composition containing the above-mentioned phenoxy resin.

Further, according to the present invention,
A bifunctional epoxy compound (A) having two epoxy groups, represented by the formula (d-EP),
and (B) a polyfunctional phenol compound having at least two phenolic hydroxyl groups,
The polyfunctional phenol compound (B) is at least one selected from the compounds represented by formulas (p1) to (p8):

In the formula (d-EP), X represents a divalent group having a mesogenic skeleton,
The polyfunctional phenol compound (B) is at least one selected from the compounds represented by formulas (p1) to (p8),

In the formulas (p1) to (p8), R ¹¹ and R ¹² independently represent a hydrogen atom, an alkoxy group having 1 to 4 carbon atoms, or a linear or branched alkyl group having 1 to 4 carbon atoms.

Further, according to the present invention,
A substrate;
An electronic component provided on the substrate;
and a sealant for sealing the electronic component.
The electronic device is provided, wherein the sealing material is made of a cured product of the above thermosetting resin composition.

The present invention also provides a thermally conductive sheet formed from the above-mentioned thermosetting resin composition.

The present invention also provides a resin substrate made of the cured product of the above-mentioned thermally conductive sheet.

The present invention also provides an electronic device that includes the above-mentioned resin substrate.

Furthermore, according to the present invention,
A metal layer;
A resin layer laminated on at least one surface of the metal layer,
There is provided a laminate, wherein the resin layer is made of a cured product of the thermally conductive sheet.

The present invention provides a phenoxy resin with high thermal conductivity and a resin composition using the same.

1 is a schematic cross-sectional view showing a structure of a metal base substrate according to an embodiment of the present invention.

The following describes an embodiment of the present invention with reference to the drawings. In all drawings, similar components are given similar reference numerals and descriptions are omitted where appropriate. In this specification, the notation "~" means "above and below" unless otherwise specified.

[Phenoxy resin]
The phenoxy resin of this embodiment is
Formula (d-EP)(A) having two epoxy groups;
and a polyfunctional phenol compound (B) having at least two phenolic hydroxyl groups.
More specifically, the phenoxy resin of the present embodiment is a polymer obtained by reacting an epoxy group of a bifunctional epoxy compound (A) with a phenolic hydroxyl group of a polyfunctional phenol compound (B) to generate a crosslinked structure. That is, the phenoxy resin of the present embodiment is a phenoxy resin containing a structural unit derived from the bifunctional epoxy compound (A) and a structural unit derived from the polyfunctional phenol compound (B).

The bifunctional epoxy compound (A) that constitutes the crosslinked structure of the phenoxy resin of this embodiment contains a compound represented by the formula (d-EP),

In the formula (d-EP), X is a divalent group having a mesogenic skeleton.
The phenoxy resin of the present embodiment contains a structural unit derived from the epoxy compound (A) having a mesogenic skeleton, and thus the cured product thereof has high thermal conductivity and high heat resistance.

The mesogenic skeleton of the X group in formula (d-EP) includes a biphenyl skeleton, a naphthalene skeleton, a phenylbenzoate skeleton, an azobenzene skeleton, a stilbene skeleton, a cyclohexylbenzene skeleton, and derivatives thereof. Since the X group has the above-mentioned mesogenic skeleton, the phenoxy resin of this embodiment can have high thermal conductivity.

In one embodiment, at least one of the X groups in formula (d-EP) is a group represented by formula (2). By including a structure having a mesogenic skeleton represented by formula (2), the phenoxy resin of this embodiment has high thermal conductivity and excellent heat resistance.

In one embodiment, the group represented by formula (2) is preferably a group in which R ₁ , R ₄ , R ₅ , and R ₈ are alkyl groups having 1 to 4 carbon atoms, and R ₂ , R ₃ , R ₆ , and R ₇ are hydrogen atoms. Among these, a group in which R ₁ , R ₄ , R ₅ , and R ₈ are alkyl groups having 1 carbon atom, and R ₂ , R ₃ , R ₆ , and R ₇ are hydrogen atoms in formula (2) (referred to as a "tetramethylbiphenyl group") is preferred in that the thermal conductivity and heat resistance of the resulting phenoxy resin can be well balanced.

In one embodiment, the group represented by formula (2) may be a group in which R ₁ , R ₄ , R ₅ , and R ₈ are alkyl groups having one carbon atom, and R ₂ , R ₃ , R ₆ , and R ₇ are hydrogen atoms (referred to as a "biphenyl group"). By having such a group, the phenoxy resin has excellent thermal conductivity and heat resistance.

In one embodiment, the formula (d-EP) preferably contains a tetramethylbiphenyl group and a biphenyl group as the X group. A phenoxy resin containing a combination of these groups can have an excellent balance of thermal conductivity and heat resistance.

The polyfunctional phenol compound (B) constituting the crosslinked structure of the phenoxy resin of this embodiment is a phenol compound having at least two phenolic hydroxyl groups, preferably a bifunctional phenol compound having two phenolic hydroxyl groups, or a trifunctional phenol compound having three phenolic hydroxyl groups, and specifically, at least one selected from the compounds represented by formulas (p1) to (p8).

In the formulas (p1) to (p8), R ¹¹ and R ¹² independently represent a hydrogen atom, an alkoxy group having 1 to 4 carbon atoms, or a linear or branched alkyl group having 1 to 4 carbon atoms.
The phenoxy resin of the present embodiment contains structural units derived from the compounds represented by formulas (p1) to (p8), and thus the cured product thereof has high thermal conductivity.
In this embodiment, the polyfunctional phenol compounds having a flavanone skeleton represented by formulae (P3), (p4), (p7) and (p8) include stereoisomers. Specifically, the isoflavanone compounds of formulae (p3) and (p7) include stereoisomers in which the C2 carbon is an asymmetric carbon atom, and the isoflavanone compounds of formulae (p4) and (p8) include stereoisomers in which the C3 atom is an asymmetric carbon atom.

In one embodiment, all of R ¹¹ and R ¹² in the compounds represented by formulae (p1) to (p8) are hydrogen atoms. A phenoxy resin having a structural unit derived from a polyfunctional phenol compound having such a structure can have high thermal conductivity and heat resistance.

The phenoxy resin of this embodiment may contain structural units derived from other component (C) in addition to the bifunctional epoxy compound (A) and polyfunctional phenol compound (B) as long as the properties of the phenoxy resin are not affected. Examples of component (C) include, but are not limited to, glycidyl ester type epoxy compounds, glycidyl amine type epoxy compounds, alicyclic epoxy compounds, Bis-A type epoxy compounds, Bis-E type epoxy compounds, Bis-F type epoxy compounds, Bis-S type epoxy compounds, and bisphenol compounds that are precursors of these. When the phenoxy resin of this embodiment contains structural units derived from component (C), the content of the structural units is, for example, 10 mol% or less, and preferably 5 mol% or less, based on the total structural units constituting the phenoxy resin.

In one embodiment, the phenoxy resin of the present invention is a resin having a structure represented by the following (1), which is obtained by reacting a bifunctional epoxy compound represented by the above formula (d-EP) with at least one selected from the bifunctional phenol compounds represented by the above formulas (p1) to (p4).

In formula (1),
n is a number representing a repeating unit, and represents an integer of 2 to 50, preferably an integer of 5 to 40, more preferably an integer of 6 to 30, and even more preferably an integer of 8 to 20;
X has the same meaning as X in formula (d-EP).
Y is independently at least one divalent group selected from the following formulas (y1) to (y4):

In formulae (y1) to (y4), R ¹¹ and R ¹² each independently represent a hydrogen atom, an alkoxy group having 1 to 4 carbon atoms, or a linear or branched alkyl group having 1 to 4 carbon atoms, and * represents a linking position. The groups of formulae (y1) to (y4) are groups derived from polyfunctional phenol compounds of formulae (p1) to (p4), respectively.

The phenoxy resin having a structure represented by formula (1) of this embodiment has in its structure a divalent organic group having a mesogen skeleton represented by "X" in formula (1) and at least one divalent group selected from formula (y1) having an isoflavonoid skeleton, formula (y2) having a flavonoid skeleton, formula (y3) having a flavanone skeleton, and formula (y4) represented by "Y" in formula (1). By having such a structure, the cured product of the phenoxy resin has high thermal conductivity.

The phenoxy resin represented by formula (1) may contain, in addition to the above-mentioned X and Y groups, other groups as long as they do not affect the properties of the phenoxy resin.

The weight average molecular weight (Mw) of the phenoxy resin of this embodiment is, for example, 1,000 to 10,000, preferably 2,000 to 8,000, more preferably 3,000 to 7,000, and even more preferably 3,500 to 6,500. Mw is a value measured by gel permeation chromatography and converted using a standard polystyrene calibration curve. By setting Mw in the above range, the thermal conductivity of the phenoxy resin can be further improved.

In this embodiment, the weight average molecular weight (Mw) of the phenoxy resin can be measured by obtaining a molecular weight distribution curve using GPC (Gel Permeation Chromatography). The weight average molecular weight (Mw), number average molecular weight (Mn), and polydispersity (PDI: Mw/Mn) of the phenoxy resin are calculated using polystyrene equivalent values obtained from the calibration curve of standard polystyrene (PS) obtained by GPC measurement.

The measurement conditions for GPC are, for example, as follows.
Gel permeation chromatography device HLC-8320GPC manufactured by Tosoh Corporation
Column: TSK-GEL GMH, G2000H, Super HM-M manufactured by Tosoh Corporation
Detector: RI detector for liquid chromatography Measurement temperature: 40°C
Solvent: THF
Sample concentration: 2.0 mg/ml

The dispersity (Mw/Mn) of the phenoxy resin is, for example, 1.00 to 5.00, preferably 1.20 to 4.00, and more preferably 1.30 to 3.50. By setting the dispersity within the above range, the thermal conductivity and fluidity of the phenoxy resin can be further improved.

The phenoxy resin may contain a low molecular weight phenoxy resin having a weight average molecular weight (Mw) of 1000 or less. When the phenoxy resin contains a low molecular weight phenoxy resin, the low molecular weight phenoxy resin is, for example, 5% to 60% and preferably 5% to 50% in terms of the total area of components corresponding to a weight average molecular weight Mw of 1,000 or less, relative to the total area of 100% of the entire molecular weight distribution obtained by GPC measurement. Phenoxy resins containing low molecular weight phenoxy resins in the above range have improved fluidity and excellent handleability. Therefore, for example, the processing stability is improved when the phenoxy resin is processed into the form of a sheet or film.

From the viewpoint of the effects of the present invention, the epoxy equivalent of the phenoxy resin is, for example, 300 to 6,000 g/eq, preferably 350 to 5,000 g/eq, and more preferably 400 to 4,500 g/eq.

The phenoxy resin of this embodiment has the specific configuration described above, which allows the thermal conductivity of the cured product to be improved. The thermal conductivity of the cured product of the phenoxy resin of this embodiment is, for example, 0.3 W/(m·K) or more, preferably 0.35 W/(m·K) or more, and more preferably 0.4 W/(m·K) or more.

The phenoxy resin of this embodiment has the specific structure described above, and thus the cured product has a high 1% weight loss temperature. The 1% weight loss temperature of the cured product of the phenoxy resin of this embodiment is 300°C or higher, preferably 310°C or higher, more preferably 320°C or higher, and even more preferably 330°C or higher. The upper limit of the 1% weight loss temperature of the cured product of the phenoxy resin of this embodiment is, for example, 400°C or lower.

[Production of phenoxy resin]
The phenoxy resin of this embodiment can be synthesized by reacting the bifunctional epoxy compound (A) represented by the above formula (d-EP) with at least one of the polyfunctional phenol compounds (B) represented by the above formulas (p1) to (p8). The phenoxy resin of this embodiment may be synthesized using the above-mentioned component (C) in addition to the bifunctional epoxy compound (A) and the polyfunctional phenol compound (B) within a range that does not impair the effects of the present invention.

The above reaction can be carried out without a solvent or in the presence of a reaction solvent using a reaction catalyst.

Suitable reaction solvents include aprotic organic solvents such as methyl ethyl ketone, dioxane, tetrahydrofuran, acetophenone, N-methylpyrrolidone, dimethyl sulfoxide, N,N-dimethylacetamide, sulfolane, propylene glycol monomethyl ether, and cyclohexanone. The use of a reaction solvent can reduce the initial viscosity and improve the reactivity of the monomer.

As the reaction catalyst, a conventionally known polymerization catalyst can be used, and alkali metal hydroxides, tertiary amine compounds, quaternary ammonium compounds, tertiary phosphine compounds, quaternary phosphonium compounds, and imidazole compounds are preferably used.

Specifically, a bifunctional epoxy compound (A), a polyfunctional phenol compound (B), a reaction catalyst, and, if necessary, a reaction solvent are added and melt-mixed under stirring. The heating temperature during melt-mixing is about 90-120°C, the mixing time is about 30 minutes to 2 hours, and the reaction pressure is normal pressure. After melt-mixing, the mixed solution is heated and a polymerization reaction is carried out at a predetermined reaction temperature under reduced pressure or normal pressure. The reaction temperature is about 140-180°C, the reaction time is about 2 hours to 10 hours, and the reaction pressure is about 1-760 Torr.

After the reaction is complete, it is possible to obtain the resin dissolved in a suitable solvent by performing solvent replacement or the like. In addition, the phenoxy resin obtained in the solvent reaction can be obtained as a solid resin that does not contain the solvent by performing a solvent removal process using an evaporator or the like.

In the above synthesis method, a phenoxy resin having the desired weight average molecular weight can be obtained by appropriately selecting reaction conditions such as the amount of starting material used, reaction temperature, and reaction time to adjust the degree of polymerization.

The bifunctional epoxy compound (A) used in the synthesis of the phenoxy resin of this embodiment includes 4,4'-diglycidylbiphenyl, 4,4'-diglycidyl-3,3',5,5'-tetramethylbiphenyl, and the like.

The polyfunctional phenol compound (B) used in the synthesis of the phenoxy resin of this embodiment includes flavones such as luteolin, apigenin, baicalein, scutellarein, tricetin, diosmetin, and nobiletin; isoflavonoids such as daidzein and genistein; and flavanones such as naringenin, butin, eriodictyol, hesperetin, homoeriodictyol, isosakuranetin, pinocembrin, sakuranetin, and sterubin. Among these, it is preferable to use daidzein, genistein, and naringenin because they are easy to handle and the resulting phenoxy resin has high thermal conductivity.

[Thermosetting resin composition]
First Embodiment
In the first embodiment, the thermosetting resin composition contains the above-mentioned phenoxy resin and other components depending on the application. Hereinafter, components that can constitute the thermosetting resin composition of this embodiment will be described.

(Phenoxy resin)
The thermosetting resin composition of the present embodiment contains the above-mentioned phenoxy resin. When the thermosetting resin composition of the present embodiment is used, for example, in a heat dissipation insulating material, the content of the phenoxy resin is, for example, 1 mass % to 70 mass %, preferably 2 mass % to 50 mass %, and more preferably 3 mass % to 45 mass %, based on the total solid content (non-volatile content) of the thermosetting resin composition not including the inorganic filler described below.

(Thermal conductive filler)
The thermosetting resin composition of the present embodiment may contain a thermally conductive filler. By blending the thermally conductive filler, the thermosetting resin composition of the present embodiment can be used as a material for producing a heat dissipation member. The thermally conductive filler may contain, for example, highly thermally conductive inorganic particles having a thermal conductivity of 20 W/m·K or more. Examples of highly thermally conductive inorganic particles include alumina, aluminum nitride, boron nitride, silicon nitride, silicon carbide, and magnesium oxide. These may be used alone or in combination of two or more.

When boron nitride is used as the thermally conductive filler, the boron nitride may contain monodisperse particles, agglomerated particles, or a mixture thereof, of scaly boron nitride. The scaly boron nitride may be granulated. By using agglomerated particles of scaly boron nitride, the thermal conductivity of the resulting thermosetting resin composition can be further increased. The agglomerated particles may be sintered or non-sintered particles.

(thermosetting resin)
The thermosetting resin composition of the present embodiment may contain other thermosetting resins other than the above-mentioned phenoxy resin, as long as the effect of the present invention is not impaired. Examples of the other thermosetting resins include epoxy resins other than the phenoxy resin having the structure of formula (1) of the present embodiment, polyimide resins, benzoxazine resins, unsaturated polyester resins, phenolic resins, melamine resins, silicone resins, cyanate resins, bismaleimide resins, acrylic resins, phenol derivatives, and derivatives thereof. As these thermosetting resins, monomers, oligomers, and polymers having two or more reactive functional groups in one molecule can be used in general, and the molecular weight and molecular structure are not particularly limited. These may be used alone or in combination of two or more.

(Hardening agent)
The thermosetting resin composition of the present embodiment may contain a curing agent as necessary. The curing agent is selected according to the type of thermosetting resin, and is not particularly limited as long as it reacts with the thermosetting resin. Examples of the curing agent include phenol resin curing agents, amine curing agents, acid anhydride curing agents, and mercaptan curing agents. These may be used alone or in combination of two or more.

(Cure Accelerator)
The thermosetting resin composition may contain a curing accelerator as necessary.
The type and amount of the curing accelerator are not particularly limited, but an appropriate one can be selected from the viewpoints of reaction rate, reaction temperature, storage property, and the like.

Examples of the curing accelerator include imidazoles, organic phosphorus compounds, tertiary amines, phenolic compounds, organic acids, and the like. These may be used alone or in combination of two or more. Among these, from the viewpoint of improving heat resistance, it is preferable to use nitrogen atom-containing compounds such as imidazoles.

(Silane coupling agent)
The thermosetting resin composition may contain a silane coupling agent. This can improve the compatibility of the thermally conductive filler in the thermosetting resin composition. The coupling agent may be added to the thermosetting resin composition, or may be used by treating the surface of the thermally conductive filler.

The thermosetting resin composition of this embodiment may contain other components in addition to the components described above. Examples of such other components include an antioxidant and a leveling agent.

Second Embodiment
The thermosetting resin composition in the second embodiment contains a difunctional epoxy compound (A) represented by the above formula (d-EP) and at least one of the polyfunctional phenol compounds (B) represented by the above formulas (p1) to (p8).

The thermosetting resin composition in the second embodiment, like the thermosetting resin composition in the first embodiment, may contain other components depending on the application. The other components include thermally conductive fillers, thermosetting resins, curing agents, curing accelerators, and silane coupling agents, which are the same as those that may be blended into the thermosetting resin composition in the first embodiment.

[Method for producing thermosetting resin composition]
The thermosetting resin composition in the first and second embodiments can be prepared by dissolving, mixing, and stirring the above-mentioned components in a solvent to prepare a resin varnish (a varnish-like thermosetting resin composition). This mixing can be performed using various mixers such as an ultrasonic dispersion method, a high-pressure collision dispersion method, a high-speed rotation dispersion method, a bead mill method, a high-speed shear dispersion method, and a rotation-revolution dispersion method. Alternatively, the thermosetting resin composition in the first and second embodiments can be produced by uniformly mixing the above-mentioned components with a mixer or blender such as a tumbler mixer or a Henschel mixer, and then kneading them while heating with a kneader, roll, disperser, azihomobister, planetary mixer, or the like. The temperature during kneading must be within a temperature range in which a curing reaction does not occur, and it is preferable to melt-knead the mixture at about 70 to 150 ° C. after kneading. The mixture may be cooled and solidified after kneading, and the kneaded product may be processed into a powder, granule, tablet, or sheet shape.

The above solvents are not particularly limited, but include acetone, methyl isobutyl ketone, toluene, ethyl acetate, cyclohexane, heptane, cyclohexanone, tetrahydrofuran, dimethylformamide, dimethylacetamide, dimethylsulfoxide, ethylene glycol, cellosolve-based solvents, carbitol-based solvents, anisole, and N-methylpyrrolidone.

[Uses of thermosetting resin composition]
(Resin sheet)
The resin sheet of this embodiment includes a carrier substrate and a resin layer made of the thermosetting resin composition of this embodiment provided on the carrier substrate. The resin sheet of this embodiment can be used as a thermally conductive resin sheet for producing a heat dissipation member. The thermally conductive sheet of this embodiment is provided, for example, between a heat generating body such as a semiconductor chip and a substrate such as a lead frame or wiring substrate (interposer) on which the heat generating body is mounted, or between the substrate and a heat dissipation member such as a heat sink.

The resin sheet can be obtained, for example, by applying a varnish-like thermosetting resin composition onto a carrier substrate to obtain a coating film (resin layer) and then carrying out a solvent removal process. The solvent content in the resin sheet can be 10% by weight or less based on the entire thermosetting resin composition. For example, the solvent removal process can be carried out under conditions of 80°C to 200°C and 1 minute to 30 minutes.

In this embodiment, the carrier substrate may be, for example, a polymer film or a metal foil. Examples of the polymer film include, but are not limited to, polyolefins such as polyethylene and polypropylene, polyesters such as polyethylene terephthalate and polybutylene terephthalate, polycarbonates, release papers such as silicone sheets, and heat-resistant thermoplastic resin sheets such as fluorine-based resins and polyimide resins. Examples of the metal foil include, but are not limited to, copper and/or copper-based alloys, aluminum and/or aluminum-based alloys, iron and/or iron-based alloys, silver and/or silver-based alloys, gold and gold-based alloys, zinc and zinc-based alloys, nickel and nickel-based alloys, and tin and tin-based alloys.

(Resin substrate)
The resin substrate of the present embodiment includes an insulating layer made of the cured product of the thermosetting resin composition. The resin substrate can be used as a material for a printed circuit board on which electronic components such as LEDs and power modules are mounted.

(Laminated plate)
As an example of the use of the resin substrate of this embodiment, a laminate will be described with reference to FIG.
FIG. 1 is a cross-sectional view showing an example of the configuration of a metal base substrate 100 including a cured resin sheet.

As shown in FIG. 1, the metal base substrate 100 can include a metal substrate 101, an insulating layer 102 provided on the metal substrate 101, and a metal layer 103 provided on the insulating layer 102. The insulating layer 102 can be made of one selected from the group consisting of a resin layer made of the above-mentioned thermosetting resin composition, a cured product of the thermosetting resin composition, and a laminate. Each of these resin layers and laminates may be made of a thermosetting resin composition in a B-stage state before the circuit processing of the metal layer 103, and may be a cured product obtained by curing the resin composition after the circuit processing.

The metal layer 103 is provided on the insulating layer 102 and is processed into a circuit. Examples of metals constituting the metal layer 103 include one or more selected from copper, copper alloys, aluminum, aluminum alloys, nickel, iron, tin, and the like. Among these, the metal layer 103 is preferably a copper layer or an aluminum layer, and is particularly preferably a copper layer. By using copper or aluminum, the circuit processability of the metal layer 103 can be improved. The metal layer 103 may be a metal foil available in a plate form, or a metal foil available in a roll form.

The lower limit of the thickness of the metal layer 103 is, for example, 0.01 mm or more, and preferably 0.035 mm or more, so that the metal layer 103 can be applied to applications requiring a high current.
The upper limit of the thickness of the metal layer 103 is, for example, 10.0 mm or less, and preferably 5 mm or less. If the thickness is less than this value, the circuit processability can be improved, and the substrate as a whole can be made thinner.

The metal substrate 101 has the role of dissipating heat accumulated in the metal base substrate 100. The metal substrate 101 is not particularly limited as long as it is a heat-dissipating metal substrate, but may be, for example, a copper substrate, a copper alloy substrate, an aluminum substrate, or an aluminum alloy substrate, with a copper substrate or an aluminum substrate being preferred, and a copper substrate being more preferred. By using a copper substrate or an aluminum substrate, the heat dissipation properties of the metal substrate 101 can be improved.

The thickness of the metal substrate 101 can be appropriately set as long as the object of the present invention is not impaired.
The upper limit of the thickness of the metal substrate 101 is, for example, 20.0 mm or less, and preferably 5.0 mm or less. By using a metal substrate 101 having a thickness of this value or less, the workability of the metal base substrate 100 in the outer shaping, cutting, and the like can be improved.

The lower limit of the thickness of the metal substrate 101 is, for example, 0.01 mm or more, and preferably 0.6 mm or more. By using a metal substrate 101 with a thickness of this value or more, the heat dissipation properties of the metal base substrate 100 as a whole can be improved.

In this embodiment, the metal base substrate 100 can be used for various substrate applications, but because it has excellent thermal conductivity and heat resistance, it can be used as a printed circuit board that uses LEDs and power modules.

The metal base substrate 100 can have a metal layer 103 that has been circuitized by etching or the like into a pattern. In this metal base substrate 100, a solder resist (not shown) may be formed on the outermost layer, and connection electrodes may be exposed so that electronic components can be mounted by exposure and development.

(Electronic equipment)
The resin sheet, resin substrate, and laminate of the present embodiment described above can be used as a substrate for mounting electronic components thereon to manufacture an electronic device. Alternatively, the thermosetting resin composition of the present embodiment can be used as an encapsulant for encapsulating electronic components.

The above describes embodiments of the present invention, but these are merely examples of the present invention, and various configurations other than those described above can be adopted as long as they do not impair the effects of the present invention.

The present invention will be described below with reference to examples and comparative examples, but the present invention is not limited to these.

Epoxy compound 1: a tetramethylbiphenyl type epoxy resin represented by the following formula (3) ("YX4000" manufactured by Mitsubishi Chemical Corporation)

Epoxy compound 2: a 1:1 mixture of a tetramethylbiphenyl type epoxy resin represented by the following formula (3) and a biphenyl type epoxy resin represented by the following formula (4) ("YL-6121" manufactured by Mitsubishi Chemical Corporation)

(Polyfunctional phenol compounds)
Phenolic compound 1: daidzein (a bifunctional phenolic compound represented by the following formula (5))

Phenolic compound 2: Naringenin (a trifunctional phenolic compound represented by the following formula (6))

Example 1
62 parts by weight of epoxy compound 1, 31 parts by weight of phenol compound 1, 0.05 parts by weight of triphenylphosphine (TPP), and 7 parts by weight of a solvent (cyclohexanone) were added to a reactor and melt-mixed at 100°C to 110°C for 1 hour. The mixture was then heated to 180°C, and reacted while removing the solvent under reduced pressure at that temperature. It was confirmed by GPC that the desired molecular weight was reached, and the reaction was stopped to obtain a phenoxy resin represented by the following formula (1-1). The reaction was carried out for 6 hours. After the reaction, 100 parts by weight of dimethylformamide was added to the resin to dissolve the resin, and the resin was cooled to room temperature. After cooling, the resin was purified by a reprecipitation method using methanol to obtain 100 parts by weight of a phenoxy resin represented by the following formula (1-1) (the average value of the number of repeating units n in formula (1-1) is 11, X is a structural unit derived from epoxy compound 1 in formula (3), and Y is a structural unit derived from daidzein, which is phenol compound 1).

Example 2
62 parts by weight of epoxy compound 2, 31 parts by weight of phenol compound 1, 0.05 parts by weight of triphenylphosphine (TPP), and 7 parts by weight of a solvent (cyclohexanone) were added to a reactor and melt-mixed at 100°C to 110°C for 1 hour. The mixture was then heated to 180°C and reacted at that temperature while removing the solvent under reduced pressure. It was confirmed by GPC that the desired molecular weight was reached, and the reaction was stopped to obtain a phenoxy resin represented by the following formula (1-2). The reaction was carried out for 6 hours. After the reaction, 100 parts by weight of dimethylformamide was added to the resin to dissolve the resin, and the resin was cooled to room temperature. After cooling, the mixture was purified by a reprecipitation method using methanol to obtain 100 parts by weight of a phenoxy resin represented by the following formula (1-2) (the average value of the number of repeating units n in formula (1-2) is 11, X is a structural unit derived from an epoxy compound of formula (3) and a structural unit derived from an epoxy compound of formula (4), and Y is a structural unit derived from daidzein, which is a phenol compound 1).

(Comparative Example 1)
As the phenoxy resin, linear phenoxy resin 1: bisphenol A type phenoxy resin represented by the following formula (7) (no mesogen structure, manufactured by Mitsubishi Chemical Corporation, YP-55) was used.

Example 3
50 parts by weight of epoxy compound 1 and 50 parts by weight of phenol compound 1 were weighed into an aluminum cup and melted on a hot plate at 150° C., and 2 parts by weight of catalyst (2-methylimidazole) was added and mixed for 1 minute to obtain a resin composition.

Example 4
50 parts by weight of epoxy compound 1 and 50 parts by weight of phenol compound 2 were weighed into an aluminum cup and melted on a hot plate at 150° C., and 2 parts by weight of catalyst (2-methylimidazole) was added and mixed for 1 minute to obtain a resin composition.

(Comparative Example 2)
50 parts by weight of epoxy compound 1 and 50 parts by weight of phenol novolak resin (PR-55617, manufactured by Sumitomo Bakelite Co., Ltd.) were weighed into an aluminum cup, melted on a hot plate at 150° C., and 2 parts by weight of a catalyst (2-methylimidazole) was added and mixed for 1 minute to obtain a resin composition.

The physical properties of the phenoxy resins of Examples 1 and 2 and Comparative Example 1 were measured by the following methods.
(Molecular weight, dispersity, and peak area)
The measurement conditions for GPC are as follows.
- Gel permeation chromatography device HLC-8320GPC manufactured by Tosoh Corporation
Column: TSK-GEL GMH, G2000H, Super HM-M manufactured by Tosoh Corporation
Detector: RI detector for liquid chromatography Measurement temperature: 40°C
Solvent: THF
Sample concentration: 2.0 mg/mL Weight average molecular weight (Mw), number average molecular weight (Mn), and polydispersity index (PDI: Mw/Mn) were calculated using polystyrene-equivalent values obtained from a calibration curve of standard polystyrene (PS) obtained by GPC measurement.
Based on the data on molecular weight obtained by the above GPC measurement, the area ratio (%) of the peak area corresponding to the low molecular weight phenoxy resin having Mw of 1k or less contained in the entire phenoxy resin to be measured was calculated when the total area of the molecular weight distribution obtained by the GPC measurement was taken as 100%. The results are shown in Table 1.

(Thermal Conductivity)
- Preparation of phenoxy resin molded body 100 parts by weight of each phenoxy resin of Examples 1, 2, or Comparative Example 1 was mixed with 2 parts by weight of a catalyst (2-methylimidazole), and the mixture was set in a mold coated with a release agent, and compression molding was performed at 180°C for 30 minutes to obtain a resin molded body with a diameter of 10 mm and a thickness of 1 mm. Then, curing was performed in an oven at 180°C for 180 minutes to obtain a resin molded body (a sample for measuring thermal conductivity).
Preparation of resin composition molded body The resin composition of Examples 3 and 4 or Comparative Example 2 was set in a mold coated with a release agent, and compression molded at 180° C. for 30 minutes to obtain a resin molded body having a diameter of 10 mm and a thickness of 1 mm. Then, the resin composition was cured in an oven at 180° C. for 180 minutes to obtain a resin composition molded body (a sample for measuring thermal conductivity).

Measurement of thermal conductivity of molded product From the obtained resin molded product, a test piece was prepared by processing it into a diameter of 10 mm and a thickness of 1 mm for thickness direction measurement. Next, the thermal diffusion coefficient (α) of the plate-shaped test piece in the thickness direction was measured by the laser flash method using a Xe flash analyzer TD-1RTV manufactured by ULVAC. The measurement was performed under the condition of air atmosphere and 25°C.
The thermal conductivity of the resin molded body was calculated from the measured values of the thermal diffusion coefficient (α), specific heat (Cp), and density (ρ) according to the following formula. The results are shown in Table 1.
Thermal conductivity [W/m・K] = α [m ² /s] × Cp [J/kg・K] × ρ [g/cm ³ ]

The cured products of the resin compositions in the Examples all had higher thermal conductivity than those in Comparative Example 1.

100 Metal base substrate 101 Metal substrate 102 Insulating layer 103 Metal layer

Claims (29)

A bifunctional epoxy compound (A) having two epoxy groups;
A phenoxy resin obtained by reacting a polyfunctional phenol compound (B) having at least two phenolic hydroxyl groups with
The bifunctional epoxy compound (A) includes a compound represented by the formula (d-EP),

In the formula (d-EP), X represents a divalent group having a mesogenic skeleton,
The polyfunctional phenol compound (B) is at least one selected from the compounds represented by formulas (p1) to (p8),

In the formulas (p1) to (p8), R ¹¹ and R ¹² each independently represent a hydrogen atom, an alkoxy group having 1 to 4 carbon atoms, or a linear or branched alkyl group having 1 to 4 carbon atoms.
Phenoxy resin. The phenoxy resin according to claim 1, wherein in the polyfunctional phenol compound (B) represented by the formulas (p1) to (p8), all of R ¹¹ and R ¹² are hydrogen atoms. The phenoxy resin according to claim 1 or 2, wherein X in the formula (d-EP) contains a divalent group represented by formula (2):

In formula (2), R ¹ to R ⁸ independently represent a hydrogen atom or a linear or branched alkyl group having 1 to 4 carbon atoms, and * represents a linking position. The phenoxy resin according to claim 3, wherein in the group represented by formula (2), R ¹ , R ⁴ , R ⁵ , and R ⁸ are alkyl groups having 1 to 4 carbon atoms, and R ² , R ³ , R ⁶ , and R ⁷ are hydrogen atoms. The phenoxy resin according to claim 3, wherein in the group represented by formula (2), R ¹ , R ⁴ , R ⁵ and R ⁸ are methyl groups, and R ² , R ³ , R ⁶ and R ⁷ are hydrogen atoms. The phenoxy resin according to claim 3, wherein in the group represented by formula (2), all of R ¹ to R ⁸ are hydrogen atoms. The phenoxy resin according to claim 3, wherein at least one of X in the formula (d-EP) is a divalent group represented by the formula (2) in which R ¹ , R ⁴ , R ⁵ , and R ⁸ are methyl groups, and R ² , R ³ , R ⁶ , and R ⁷ are hydrogen atoms, and at least one of X in the formula (d-EP ) is a divalent group represented by the formula (2) in which R ¹ to R ⁸ are all hydrogen atoms. the polyfunctional phenol compound (B) is at least one selected from the compounds represented by formulas (p1) to (p4),
The phenoxy resin according to any one of claims 1 to 7, wherein the phenoxy resin has a structure represented by formula (1):

In formula (1),
n is a number representing a repeating unit and is an integer of 2 to 50;
X has the same meaning as X in formula (d-EP).
Y is independently at least one divalent group selected from the following formulas (y1) to (y4):

In formulae (y1) to (y4), R ¹¹ and R ¹² independently represent a hydrogen atom, an alkoxy group having 1 to 4 carbon atoms, or a linear or branched alkyl group having 1 to 4 carbon atoms, and * represents a linking position. The phenoxy resin according to any one of claims 1 to 8, having a weight average molecular weight of 1,000 or more and 10,000 or less. The phenoxy resin according to any one of claims 1 to 9, wherein the thermal conductivity of the cured product of the phenoxy resin is 0.3 W/(m·K) or more. A thermosetting resin composition comprising the phenoxy resin according to any one of claims 1 to 10 . The thermosetting resin composition of claim 11 , further comprising a thermally conductive filler. The thermosetting resin composition according to claim 11 or 12 , further comprising a solvent. A bifunctional epoxy compound (A) having two epoxy groups, represented by the formula (d-EP),
and (B) a polyfunctional phenol compound having at least two phenolic hydroxyl groups,
The polyfunctional phenol compound (B) is at least one selected from the compounds represented by formulas (p1) to (p8):

In the formula (d-EP), X represents a divalent group having a mesogenic skeleton,
The polyfunctional phenol compound (B) is at least one selected from the compounds represented by formulas (p1) to (p8),

In the formulas (p1) to (p8), R ¹¹ and R ¹² independently represent a hydrogen atom, an alkoxy group having 1 to 4 carbon atoms, or a linear or branched alkyl group having 1 to 4 carbon atoms. The thermosetting resin composition according to claim 14 , wherein in the polyfunctional phenol compound (B) represented by the formulas (p1) to (p8), all of R ¹¹ and R ¹² are hydrogen atoms. The thermosetting resin composition according to claim 14 or 15 , wherein X in the formula (d-EP) contains a divalent group represented by formula (2):

In formula (2), R ¹ to R ⁸ independently represent a hydrogen atom or a linear or branched alkyl group having 1 to 4 carbon atoms, and * represents a linking position. The thermosetting resin composition according to claim 16, wherein in the group represented by formula (2), R ¹ , R ⁴ , R ⁵ , and R ⁸ are alkyl groups having 1 to 4 carbon atoms, and R ² , R ³ , R ⁶ , and R ⁷ are hydrogen atoms. The thermosetting resin composition according to claim 16 , wherein in the group represented by formula (2), R ¹ , R ⁴ , R ⁵ , and R ⁸ are methyl groups, and R ² , R ³ , R ⁶ , and R ⁷ are hydrogen atoms. The thermosetting resin composition according to claim 16 , wherein in the group represented by formula (2), all of R ¹ to R ⁸ are hydrogen atoms. The bifunctional epoxy compound represented by the formula (d-EP) is
a bifunctional epoxy compound represented by formula (2) in which R ¹ , R ⁴ , R ⁵ , and R ⁸ are methyl groups, and R ² , R ³ , R ⁶ , and R ⁷ are hydrogen atoms;
and a difunctional epoxy compound represented by formula ( 2 ) in which all of R ¹ to R ⁸ are hydrogen atoms. The thermosetting resin composition according to claim 14 , further comprising a thermally conductive filler. 22. The thermosetting resin composition according to any one of claims 14 to 21 , which is in the form of granules or tablets. The thermosetting resin composition according to claim 14 , which is used to form an encapsulant for encapsulating electronic components. A substrate;
An electronic component provided on the substrate;
and a sealant for sealing the electronic component.
The sealing material is made of a cured product of the thermosetting resin composition according to any one of claims 14 to 23 .
electronic equipment. A thermally conductive sheet formed from the thermosetting resin composition according to any one of claims 11 to 21 . A resin substrate comprising a cured product of the thermally conductive sheet according to claim 25 . An electronic device comprising the resin substrate according to claim 26 . A metal layer;
A resin layer laminated on at least one surface of the metal layer,
A laminate comprising the resin layer formed from a cured product of the thermally conductive sheet according to claim 25 . 29. An electronic device comprising the laminate of claim 28 .

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