Thermosetting resin composition and power module

Abstract

The thermosetting resin composition contains an epoxy resin containing an epoxy compound represented by formula (1), a curing agent, and an inorganic filler. The glass transition temperature of a thermosetting resin composition in which m is 2 and n is 2 in formula (1), measured at a heating rate of 5°C / min using thermomechanical analysis (TMA), is 190°C or more, and the die shear strength of the thermosetting resin composition to copper at 230°C, measured by the following <Procedure>, is 3.0 MPa or more. <Procedure> The thermosetting resin composition is molded using a low-pressure transfer molding machine at a mold temperature of 175° C, an injection pressure of 10 MPa, and a curing time of 120 seconds, and four 10 mm2 test pieces per level are molded on a copper lead frame. Subsequently, the die shear strength between the test piece and the copper lead frame is measured at 230°C using an automatic die shear measuring device. The die shear strength of the four test pieces is adopted.

Description

Thermosetting resin composition and power module

[0001] The present invention relates to a thermosetting resin composition and a power module. More specifically, to a thermosetting resin composition used as a encapsulant for encapsulating power semiconductors, and to a power module obtained by encapsulating power semiconductors with the thermosetting resin composition.

[0002] In recent years, SiC / GaN power semiconductor devices incorporating elements made of SiC (silicon carbide) or GaN (gallium nitride) have attracted attention from the perspective of efficient use of electrical energy (see, for example, Patent Document 1). Compared to conventional Si-based elements, such elements not only significantly reduce power loss but can also operate at higher voltages, high currents, and high temperatures of over 200°C, thus opening up possibilities for applications that were difficult to achieve with conventional Si power semiconductor devices.

[0003] Devices capable of operating under harsh conditions, such as those using SiC / GaN (semiconductor devices), require semiconductor encapsulants that offer greater heat resistance than conventional devices to protect these devices. In conventional Si power semiconductor devices, encapsulants containing cured epoxy resin compositions as the main material are used, from the viewpoint of adhesion and electrical stability.

[0004] Generally, the glass transition temperature (Tg) is used as an indicator to represent the heat resistance of cured products of such resin compositions. This is because, in the temperature range above Tg, the thermosetting resin composition (cured product) becomes rubbery, which causes a decrease in its strength and adhesive strength. Therefore, methods to raise Tg include increasing the crosslinking density by lowering the epoxy group equivalent of the epoxy resin contained in the resin composition, or the hydroxyl group equivalent of the curing agent (phenol resin curing agent), or making the structure connecting these functional groups (epoxy groups and hydroxyl groups) more rigid.

[0005] Therefore, in order to improve the heat resistance of resin compositions, it is desirable to realize a resin composition that has a high Tg, as well as excellent adhesion and high-temperature reliability, by designing the resin skeleton formed by the epoxy resin and curing agent and the functional group density under optimal conditions.

[0006] Japanese Patent Publication No. 2005-167035

[0007] The present invention has been made in view of the above problems, and aims to provide a thermosetting resin composition for sealing materials that has a high Tg and can therefore ensure high reliability even in high-temperature ranges.

[0008] The present invention provides the following thermosetting resin composition and power module: [1] A thermosetting resin composition comprising an epoxy resin (A), a phenolic resin curing agent (B), and an inorganic filler (C), wherein the epoxy resin (A) comprises a naphthalene-type epoxy resin (a1) represented by formula (1), In formula (1), m is 2 and n is 2, the thermosetting resin composition has a glass transition temperature of 190°C or higher, measured by thermomechanical analysis (TMA) at a heating rate of 5°C / min, and a die shear strength against copper at 230°C of the thermosetting resin composition is 3.0 MPa or higher, measured by the following procedure: <Procedure> The thermosetting resin composition is molded using a low-pressure transfer molding machine under the conditions of a mold temperature of 175°C, an injection pressure of 10 MPa, and a curing time of 120 seconds, and then molded onto a copper lead frame by 10 mm ２Four test pieces are molded per level. Subsequently, the die shear strength between the test piece and the copper lead frame is measured at 230°C using an automatic die shear measuring device. The die shear strengths of the four test pieces are adopted. [2] A thermosetting resin composition according to [1], wherein the epoxy resin (A) further comprises a triphenylmethane type epoxy resin (a2). [3] A thermosetting resin composition according to [1] or [2], wherein the phenol resin curing agent (B) comprises a polyfunctional phenol resin or a phenol aralkyl type phenol resin, or a combination thereof. [4] A thermosetting resin composition according to any one of [1] to [3], wherein the phenol resin curing agent (B) comprises a trisphenylmethane type phenol resin or a biphenyl skeleton-containing polyfunctional phenol resin, or a combination thereof. [5] A thermosetting resin composition according to any one of [1] to [3], further comprising a low-stress agent. [6] A thermosetting resin composition according to [5], wherein the low-stress agent comprises at least one selected from butadiene rubber, nitrile rubber, silicone rubber, core-shell type rubber particles, and silicone oil. [7] A thermosetting resin composition according to [6], wherein the low-stress agent comprises core-shell type rubber particles. [8] A thermosetting resin composition according to any one of [1] to [7], further comprising an adhesion aid. [9] A thermosetting resin composition according to any one of [1] to [8], wherein the inorganic filler (C) comprises silica powder.

[10] A power module comprising: a metal circuit board; a power semiconductor element provided on one side of the metal circuit board; a bonding layer made of sintering paste that bonds the power semiconductor element and the metal circuit board; a heat dissipation sheet laminated on the side of the metal circuit board opposite to the side on which the power semiconductor element is provided; and a sealing material that covers the power semiconductor element, the bonding layer, the circuit board and the heat dissipation sheet, wherein the sealing material is made of a cured product of a thermosetting resin composition according to any one of [1] to [9].

[11] A power module comprising: a circuit board; a power semiconductor element mounted on one surface of the circuit board, the power semiconductor element having an electrical connection from the power semiconductor element to the circuit board; a sealing material provided on the one surface of the circuit board for sealing the power semiconductor element, the circuit board and the electrical connection; and a heat sink connected to the other surface of the circuit board via a thermally conductive bonding material, wherein the sealing material is made of a cured product of a thermosetting resin composition according to any one of [1] to [9].

[0009] According to the present invention, a thermosetting resin composition for sealing having a high Tg and excellent high-temperature reliability is provided, as well as a power module equipped with such a thermosetting resin composition as a sealing material.

[0010] This is a schematic cross-sectional view showing an example of a power module according to this embodiment.

[0011] Embodiments of the present invention will be described below with reference to the drawings. In all drawings, similar components are denoted by the same reference numerals, and their descriptions are omitted as appropriate. Furthermore, all drawings are for illustrative purposes only. The shapes and dimensional ratios of each component in the drawings do not necessarily correspond to actual articles. In this specification, the notation "a to b" in the description of numerical ranges means "a or more and b or less" unless otherwise specified.

[0012] [Thermosetting Resin Composition] The thermosetting resin composition of this embodiment will now be described. The thermosetting resin composition of this embodiment (which may be simply referred to as "resin composition" in this specification) comprises an epoxy resin (A), a phenolic resin curing agent (B), and an inorganic filler (C). In the resin composition of this embodiment, the epoxy resin (A) comprises a naphthalene-type epoxy resin (a1) represented by formula (a).

[0013]

[0014] In equation (1), m is 2 and n is 2. The glass transition temperature of the thermosetting resin composition of this embodiment, measured by thermomechanical analysis (TMA) under the condition of a heating rate of 5°C / min, is 190°C or higher, and the die shear strength of the thermosetting resin composition against copper at 230°C, measured by the following procedure, is 3.0 MPa or higher: Procedure Using a low-pressure transfer molding machine, the thermosetting resin composition is molded under the conditions of a mold temperature of 175°C, an injection pressure of 10 MPa, and a curing time of 120 seconds, and a 10 mm layer is formed on a copper lead frame. ２ Four test specimens are formed for each level. Subsequently, the die shear strength between the test specimen and the copper lead frame is measured at 230°C using an automated die shear measuring device. The die shear strengths of the four test specimens are adopted.

[0015] The thermosetting resin composition of this embodiment, by incorporating the above components, has a high glass transition temperature (Tg), and therefore exhibits excellent heat resistance and excellent adhesion to metals such as lead frames and substrates.

[0016] The following describes each component included in the resin composition of this embodiment.

[0017] (Epoxy resin (A)) The resin composition of this embodiment includes a naphthalene-type epoxy resin (a1) represented by the following formula (1) as epoxy resin (A).

[0018]

[0019] In formula (1), m is 2 and n is 2. The resin composition of this embodiment contains the epoxy compound represented by formula (1) above, and its cured product has a high glass transition temperature of 190°C or higher, and therefore exhibits excellent heat resistance.

[0020] In one embodiment, the epoxy resin (A) preferably includes a triphenylmethane-type epoxy resin (a2). Examples of the triphenylmethane-type epoxy resin (a2) include epoxy resins having a structure represented by the following formula (2).

[0021]

[0022] In formula (2), R １ Each of the following independently represents a hydrocarbon group with 1 to 4 carbon atoms, each of the following independently represents an integer from 0 to 4: n １ This represents the average value, showing a number between 0 and 10. １ The hydrocarbon group having 1 to 4 carbon atoms represented is preferably an alkyl group, and the alkyl group may be linear, branched, or cyclic. Each i independently represents an integer from 0 to 4, and is preferably 0. Each k independently represents an integer from 0 to 4, and is preferably 0. n １ is a number between 0 and 10, preferably a number between 1 and 10, and more preferably 2 to 8.

[0023] In one embodiment, epoxy resin (A) may include other epoxy resins (a3) ​​in addition to the epoxy resins (a1) and (a2) described above. Examples of usable epoxy resins (a3) ​​include phenol novolac type epoxy resins, orthocresol novolac type epoxy resins, and other phenols such as cresol, xylenol, resorcinol, catechol, bisphenol A, bisphenol F, and / or naphthols such as α-naphthol, β-naphthol, dihydroxynaphthalene, and compounds having aldehyde groups such as formaldehyde, acetaldehyde, propionaldehyde, benzaldehyde, salicylaldehyde, etc., epoxidized from novolac resins obtained by condensation or co-condensation under an acidic catalyst; for example, diglycidyl ethers such as bisphenol A, bisphenol F, bisphenol S, bisphenol A / D; biphenyl type epoxy resins which are diglycidyl ethers of alkyl-substituted or unsubstituted biphenols; and epoxidized novolac resins synthesized from phenols and dimethoxyp-xylene or bis(methoxymethyl)biphenyl. Examples include epoxides of aralkyl resins such as phenol aralkyl resins, biphenylene-backbone phenol aralkyl resins, and naphthol aralkyl resins; stilbene-type epoxy resins; hydroquinone-type epoxy resins; glycidyl ester-type epoxy resins obtained by the reaction of polybasic acids such as phthalic acid and dimer acid with epichlorohydrin; glycidylamine-type epoxy resins obtained by the reaction of polyamines such as diaminodiphenylmethane and isocyanuric acid with epichlorohydrin; dicyclopentadiene-type epoxy resins, which are epoxides of co-condensation resins of dicyclopentadiene and phenols; trimethylolpropane-type epoxy resins; terpene-modified epoxy resins; linear aliphatic epoxy resins obtained by oxidizing olefin bonds with peracids such as peracetic acid; alicyclic epoxy resins; and epoxy resins obtained by modifying these epoxy resins with silicone, acrylonitrile, butadiene, isoprene, polyamide, etc.

[0024] In one embodiment of the present invention, the epoxy resin (A) may consist only of the naphthalene-type epoxy resin (a1) represented by formula (1), or it may consist of the naphthalene-type epoxy resin (a1) represented by formula (1) and the triphenylmethane-type epoxy resin (a2), or it may consist of the naphthalene-type epoxy resin (a1) represented by formula (1) and the triphenylmethane-type epoxy resin (a2) plus the epoxy resin (a3).

[0025] When epoxy resin (A) contains naphthalene-type epoxy resin (a1) and the above-mentioned triphenylmethane-type epoxy resin (a2), these are used in a blending amount such that the molar ratio (EP(a1) / EP(a2)) of the total amount of epoxy groups of the naphthalene-type epoxy resin (a1) (EP(a1)) to the total amount of epoxy groups of the triphenylmethane-type epoxy resin (a2) (EP(a2)) is 0.1 or more and 5 or less.

[0026] The epoxy equivalent of epoxy resin (A) in the resin composition is preferably 100 g / eq or more, more preferably 120 g / eq or more, and even more preferably 150 g / eq or more, from the viewpoint of achieving excellent fluidity during molding and improving filling and adhesion. Furthermore, from the viewpoint of improving the high-temperature reliability of the cured product of the resin composition, the epoxy equivalent of epoxy resin (A) in the resin composition is preferably 500 g / eq or less, more preferably 480 g / eq or less, and even more preferably 450 g / eq or less.

[0027] Here, the epoxy equivalent of component (A) can be specifically measured according to JIS K7236 and is the mass of resin containing one equivalent of epoxy groups. In this embodiment, the epoxy equivalent of epoxy resin (A) is the total equivalent amount of the epoxy resin (a1) and epoxy resins (a2) and (a3) ​​used as needed.

[0028] The content of epoxy resin (A) in the resin composition is preferably 5% by mass or more, more preferably 7% by mass or more, and even more preferably 8% by mass or more, relative to the total resin composition, from the viewpoint of achieving excellent fluidity during molding and improving filling and adhesion. Furthermore, from the viewpoint of improving the high-temperature reliability and reflow resistance of the cured resin composition, the content of epoxy resin (A) in the resin composition is preferably 15% by mass or less, more preferably 14% by mass or less, and even more preferably 13% by mass or less, relative to the total resin composition.

[0029] In this embodiment, the epoxy equivalent of the total epoxy resin in the resin composition is preferably 100 g / eq or more, more preferably 120 g / eq or more, and even more preferably 150 g / eq or more, from the viewpoint of achieving excellent fluidity during molding and improving filling and adhesion. Furthermore, for power modules obtained using the resin composition as a encapsulant, the epoxy equivalent of the total epoxy resin in the resin composition is preferably 500 g / eq or less, more preferably 480 g / eq or less, and even more preferably 450 g / eq or less, from the viewpoint of improving high-temperature reliability and reflow resistance.

[0030] (Phenolic resin curing agent (B)) The resin composition of this embodiment contains a phenolic resin curing agent (B). Examples of the phenolic resin curing agent (B) include phenols such as phenol, cresol, resorcinol, catechol, bisphenol A, bisphenol F, phenylphenol, aminophenol, and / or naphthols such as α-naphthol, β-naphthol, dihydroxynaphthalene, and compounds having an aldehyde group such as formaldehyde, benzaldehyde, salicylaldehyde. Novolak-type phenolic resins obtained by condensation or co-condensation under an acidic catalyst, polyfunctional phenolic resins such as triphenylmethane-type phenolic resins and polyphenolic resins containing a biphenylene skeleton, phenolic aralkyl-type phenolic resins such as polyphenolic resins containing a biphenylene skeleton synthesized from phenols and / or naphthols and dimethoxyparaxylene or bis(methoxymethyl)biphenyl, dicyclopentadiene-type phenolic resins, and terpene-modified phenolic resins.

[0031] Among them, the phenolic resin curing agent (B) preferably contains a polyaromatic ring type (Multi Aromatic Resin: MAR) phenolic resin (b1) from the viewpoint of improving the reliability and heat resistance of the cured product of the obtained resin composition. Also, the phenolic resin curing agent (B) is preferably a polyhydric phenolic resin having two or more functional groups, more preferably a phenolic resin having three or more functional groups, and also preferably a phenolic resin having four or less functional groups, from the viewpoint of improving the reliability and heat resistance of the cured product of the resin composition.

[0032] Specific examples of the polyhydric MAR-type phenolic resin include polyhydric MAR containing a biphenyl skeleton, polyhydric MAR containing a trisphenylmethane skeleton, polyhydric MAR containing a naphthalene skeleton, and the like. Examples of the polyhydric MAR containing a biphenyl skeleton include those represented by formula (3).

[0033]

[0034] In formula (3), n2 is a number from 1 to 10.

[0035] In the resin composition, the molar ratio (EP(A) / OH(B)) of the total amount of epoxy groups (EP(A)) of the epoxy resin (A) to the total amount of phenolic hydroxyl groups (OH(B)) of the phenolic resin curing agent (B) is preferably 1.0 or more and 1.5 or less, more preferably 1.0 or more and 1.4 or less, from the viewpoint of maximizing the crosslink density and improving the glass transition temperature, which is an important factor for heat resistance.

[0036] Here, the phenolic hydroxyl group equivalent of the phenolic resin curing agent (B) can be determined, for example, by measurement. Specifically, the phenolic hydroxyl group equivalent of the curing agent used can be determined by reacting a monoepoxy resin with a known epoxy equivalent such as phenyl glycidyl ether and a curing agent with an unknown phenolic hydroxyl group equivalent, and measuring the amount of the consumed monoepoxy resin.

[0037] The content of the phenolic resin curing agent (B) in the resin composition is preferably 0.5% by mass or more, more preferably 1.0% by mass or more, and still more preferably 1.5% by mass or more, based on the entire resin composition, from the viewpoint of achieving excellent fluidity during molding and improving filling properties and adhesion. Also, from the viewpoint of improving high-temperature reliability and reflow resistance of the semiconductor device obtained using the resin composition, the content of the phenolic resin curing agent (B) in the resin composition is preferably 10% by mass or less, more preferably 7% by mass or less, and still more preferably 5% by mass or less, based on the entire resin composition.

[0038] (Inorganic filler (C)) The resin composition of the present embodiment contains an inorganic filler (C). Examples of the inorganic filler (C) used in the resin composition of the present embodiment include silica, alumina, kaolin, talc, clay, mica, rock wool, wollastonite, glass powder, glass flakes, glass beads, glass fiber, silicon carbide, silicon nitride, aluminum nitride, carbon black, graphite, titanium dioxide, calcium carbonate, calcium sulfate, barium carbonate, magnesium carbonate, magnesium sulfate, barium sulfate, cellulose, aramid, or wood. These may be used alone or in combination of two or more.

[0039] The average particle size of the inorganic filler is not particularly limited, but is typically 1 to 100 μm, preferably 1 to 50 μm, and more preferably 1 to 20 μm. A suitable average particle size ensures adequate fluidity during curing. The average particle size of the inorganic filler can be determined by acquiring volume-based particle size distribution data using a laser diffraction / scattering particle size distribution analyzer and processing that data.

[0040] The inorganic filler (C) may be surface-modified in advance (before mixing with other components to prepare the resin composition) with a coupling agent such as a silane coupling agent. This suppresses aggregation of the inorganic filler and allows for better fluidity. It also increases the affinity between the inorganic filler and other components, improving the dispersibility of the inorganic filler. This leads to improved mechanical strength of the cured product and suppression of microcrack formation.

[0041] For surface treatment of inorganic fillers, the coupling agents listed as coupling agent (E) below can be used. Among these, aminosilanes such as γ-aminopropyltriethoxysilane and γ-aminopropyltrimethoxysilane are preferably used. By modifying the surface of the inorganic filler with groups (such as amino groups) that can react with epoxy resin (A), the dispersibility of the inorganic filler (C) in the resin composition can be improved. Furthermore, by appropriately selecting the type of coupling agent used for surface treatment of the inorganic filler and appropriately adjusting the amount of coupling agent, the fluidity of the resin composition and the strength after curing can be adjusted.

[0042] From the viewpoint of obtaining a desired coefficient of linear expansion, the inorganic filler content in the resin composition of this embodiment is preferably 75% by mass or more, more preferably 78% by mass or more, and even more preferably 80% by mass or more, relative to the entire resin composition. Furthermore, from the viewpoint of more effectively improving the fluidity and filling properties of the resin composition during molding, the inorganic filler content is preferably 90% by mass or less, more preferably 88% by mass or less, and even more preferably 86% by mass or less, relative to the entire resin composition.

[0043] In a preferred embodiment, the inorganic filler includes silica powder. Examples of silica powder include crystalline silica (crushed crystalline silica), fused silica (crushed amorphous silica, spherical amorphous silica), and liquid sealing silica (spherical amorphous sealing silica for liquid sealing materials). Among these, fused spherical silica is preferred from the viewpoint of facilitating low-temperature, low-pressure sealing.

[0044] (Other components) In addition to the curing agent, epoxy resin, and inorganic filler, the resin composition of the present invention may contain the following components.

[0045] (Stress-reducing agent) In one embodiment, the resin composition of the present invention includes a stress-reducing agent. Here, the stress-reducing agent refers to a substance that acts to alleviate internal stress caused by volume changes in the cured resin composition due to thermal changes during the operation of the power module or during the sealing material formation process. By using a stress-reducing agent, the adhesion between the metal, such as the substrate or lead frame, and the cured resin can be improved.

[0046] Examples of low-stress agents include silicone microparticles, rubber particles having a core-shell structure, and pulverized elastomer resins. More specifically, examples include butadiene rubber, nitrile rubber, silicone rubber, core-shell type rubber particles, and silicone oil. Among these, core-shell type rubber particles are preferred because they have high strength and low modulus of elasticity, and therefore provide an excellent toughening effect.

[0047] Core-shell type rubber particles refer to rubber particles in which a particulate core component, mainly composed of a cross-linked rubber-like polymer, is graft-polymerized with a polymer different from the core component, thereby coating part or all of the surface of the particulate core component with a shell component.

[0048] Examples of the core component include crosslinked rubber particles. Examples of crosslinked rubber particles include diene rubber, acrylic rubber, and polysiloxane rubber. More specifically, examples include butadiene rubber, acrylic rubber, silicone rubber, butyl rubber, nitrile rubber, styrene rubber, synthetic natural rubber, ethylene propylene rubber, and the like.

[0049] Examples of shell components include diene rubber, acrylic rubber, and polysiloxane rubber. Preferably, polymers polymerized from one or more monomers selected from the group consisting of acrylic acid esters, methacrylic acid esters, and aromatic vinyl compounds are used. The shell component is preferably graft polymerized onto the core component and chemically bonded to the polymer constituting the core component. When a crosslinked rubber-like polymer composed of a polymer of styrene and butadiene is used as the core component, it is preferable to use a polymer of methyl methacrylate (a methacrylic acid ester) and styrene (an aromatic vinyl compound) as the shell component.

[0050] Furthermore, the average particle size of the primary particles of the core-shell type rubber particles is preferably in the range of 50 to 500 nm, and more preferably in the range of 50 to 300 nm, in order to obtain a resin composition that can form a cured product having high strength and low elastic modulus.

[0051] Examples of commercially available core-shell type rubber particles include "Paraloid® EXL-2655" (manufactured by Dow Chemical), which consists of a butadiene alkyl methacrylate styrene copolymer; "Stafiloid® AC-3355, TR-2122" (manufactured by Takeda Pharmaceutical Company Limited), which consists of an acrylic acid ester / methacrylate ester copolymer; "PARALOID® EXL-2611, EXL-3387" (manufactured by Dow Chemical), which consists of a butyl acrylate / methyl methacrylate copolymer; and "KaneAce® MX series" (manufactured by Kaneka Corporation).

[0052] When a low-stress agent is used, the content of the low-stress agent in the resin composition is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, and even more preferably 0.1% by mass or more, relative to the total resin composition, in order to obtain a resin composition capable of forming a cured product with high strength and low modulus of elasticity. The upper limit of the low-stress agent content is preferably 5% by mass or less, more preferably 3% by mass or less, and even more preferably 2% by mass or less.

[0053] (Adhesion Enhancer) In one embodiment, the resin composition of the present invention includes an adhesion enhancer. The adhesion enhancer works to improve the adhesive strength between the sealing portion, which is made of the cured resin composition, and the metal constituting the substrate or lead frame. Examples of usable adhesion enhancers include triazine compounds and triazole compounds. One type of adhesion enhancer may be used alone, or two or more types may be used in combination. Examples of triazine compounds include compounds having a triazine ring, and examples of triazole compounds include compounds having a 1,2,4-triazole ring and compounds having a 1,2,3-triazole ring.

[0054] Examples of triazine compounds include 2,4-diamino-s-triazine, 2,4,6-triamino-s-triazine, 2,4-dimercapto-s-triazine, 2,4,6-trimercapto-s-triazine, 2-amino-4,6-dimercapto-s-triazine, 2,4,6-trimethylhexahydro-1,3,5-triazine, 6-amino-1,3,5-triazine-2,4-diol, 2,4-diamino-6-hydroxy-1,3,5-triazine, 6-anilino-1,3,5-triazine-2,4-dithiol, 4-amino-1,3,5-triazine-2(1H)-one, 2,4-diamino-6-phenyl-1,3,5-triazine, and 2-chloro-4,6-dia Examples include mino-1,3,5-triazine, 2,4-diamino-6-butylamino-1,3,5-triazine, 2,4-diamino-6-diallylamino-1,3,5-triazine, 2,4-diamino-6-diethylamino-1,3,5-triazine, 2,4-diamino-6-dimethylamino-1,3,5-triazine, 2,4-diamino-6-[2-(2-methyl-1-imidazolyl)ethyl]-1,3,5-triazine, 2,4-diamino-6-methyl-1,3,5-triazine, 2,4-diamino-6-[2-(2-undecyl-1-imidazolyl)ethyl]-1,3,5-triazine, and 6-(dibutylamino)-1,3,5-triazine-2,4-dithiol.

[0055] Examples of triazole compounds include 3-amino-1,2,4-triazole, 4-amino-1,2,3-triazole, 3-amino-1,2,4-triazole-5-carboxylic acid, 3-mercapto-1,2,4-triazole, 4-mercapto-1,2,3-triazole, 3,5-diamino-1,2,4-triazole, 3,5-dimercapto-1,2,4-triazole, 4,5-dimercapto-1,2,3-triazole, 3-amino-5-mercapto-1,2,4-triazole, 4-amino-5-mercapto-1,2,3-triazole, 3-hydrazino-4-amino-5-mercapto-1,2,4-triazole, and 5-mercapto-1,2,4-triazole-3-methanol. Among these, compounds having at least one mercapto group are preferably used.

[0056] The content of the adhesion aid in the resin composition is preferably 0.01 to 2% by mass, and more preferably 0.03 to 1% by mass, relative to the total resin composition. By setting the content of the adhesion aid within this range, it is possible to improve the adhesive strength to metals constituting lead frames, substrates, etc., while maintaining the curing speed and mechanical strength of the resin composition within a usable range.

[0057] (Curing accelerator) In one embodiment, the resin composition of the present invention includes a curing accelerator. The curing accelerator has the function of promoting the reaction between the epoxy groups of the epoxy resin and the reactive groups of the curing agent, and a curing accelerator commonly used in the field is used.

[0058] Specific examples of curing accelerators include phosphorus-containing compounds such as organic phosphines, tetrasubstituted phosphonium compounds, phosphobetaine compounds, adducts of phosphine compounds and quinone compounds, and adducts of phosphonium compounds and silane compounds; nitrogen-containing compounds such as amidines and tertiary amines, exemplified by 1,8-diazabicyclo(5,4,0)undecene-7, benzyldimethylamine, and 2-methylimidazole, as well as quaternary salts of the aforementioned amidines and amines. One or more of these can be used in combination. Of these, phosphorus-containing compounds are preferred from the viewpoint of curability, phosphobetaine compounds and adducts of phosphine compounds and quinone compounds are particularly preferred from the viewpoint of solder resistance and fluidity, and phosphorus-containing compounds such as tetrasubstituted phosphonium compounds and adducts of phosphonium compounds and silane compounds are particularly preferred in that they cause minimal mold contamination during continuous molding.

[0059] Examples of organic phosphines that can be used in resin compositions include primary phosphines such as ethylphosphine and phenylphosphine; secondary phosphines such as dimethylphosphine and diphenylphosphine; tertiary phosphines such as trimethylphosphine, triethylphosphine, tributylphosphine, and triphenylphosphine; and derivatives thereof.

[0060] The content of the curing accelerator in the resin composition is, for example, 0.1 to 5% by mass, preferably 0.2 to 4% by mass, relative to the total resin composition. By setting the content of the curing accelerator to above the lower limit, the resin composition becomes easier to cure properly. On the other hand, by setting the content of the curing accelerator to below the upper limit, the molten state is prolonged, and the low viscosity state can be maintained for a longer period, making it easier to achieve low-temperature sealing.

[0061] (Coupling agent) A coupling agent is used when an inorganic filler is included in the resin composition to improve the adhesion between the epoxy resin and the inorganic filler. For example, a silane coupling agent is used.

[0062] Various silane coupling agents can be used, but aminosilane is preferred. This improves the fluidity and solder resistance of the resin composition.

[0063] The aminosilane is not particularly limited, but examples include γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, N-β(aminoethyl)γ-aminopropyltrimethoxysilane, N-β(aminoethyl)γ-aminopropylmethyldimethoxysilane, N-phenylγ-aminopropyltriethoxysilane, N-phenylγ-aminopropyltrimethoxysilane, N-β(aminoethyl)γ-aminopropyltriethoxysilane, N-6-(aminohexyl)3-aminopropyltrimethoxysilane, N-(3-(trimethoxysilylpropyl)-1,3-benzenedimethanamine, etc.

[0064] The content of the coupling agent in the resin composition is preferably 0.05 to 3% by mass, and more preferably 0.1 to 2% by mass, relative to the total resin composition. By setting the content of the coupling agent above the lower limit, the dispersibility of the inorganic filler in the resin composition can be improved. Furthermore, by setting the content of the coupling agent below the upper limit, the fluidity of the resin composition can be improved, thereby enhancing moldability.

[0065] Furthermore, the resin composition of this embodiment may also contain various additives in addition to the above-mentioned components, such as colorants like carbon black; release agents like natural waxes, synthetic waxes, higher fatty acids or their metal salts, paraffin, and polyethylene oxide; ion scavenging agents like hydrotalcite; stress-reducing agents like silicone oil and silicone rubber; flame retardants like aluminum hydroxide; and antioxidants.

[0066] (Method for producing thermosetting resin composition) The thermosetting resin composition of this embodiment can be produced, for example, by mixing the above-mentioned components by known means, further melt-kneading them in a kneader such as a roll, kneader, or extruder, cooling, and then pulverizing. Alternatively, after pulverization, the mixture may be molded to obtain a thermosetting resin composition in the form of particles or sheets. For example, a particle-like resin composition may be obtained by tablet molding. Alternatively, a sheet-like resin composition may be obtained, for example, by a vacuum extruder. The degree of dispersion and fluidity of the obtained resin composition may also be adjusted as appropriate. The resin composition of this embodiment can be provided in various forms depending on the application, such as a molding method for sealing materials. For example, the resin composition of this embodiment can be provided in the form of particles such as bullets, powders, granules, or sheets.

[0067] (Physical Properties of the Resin Composition) The thermosetting resin composition of this embodiment, by containing the above components, has a glass transition temperature of 190°C or higher, preferably 200°C or higher, and more preferably 210°C or higher. Furthermore, the average linear expansion coefficient α1 of the cured product of the thermosetting resin composition of this embodiment in the temperature range of 20°C or higher and below the glass transition temperature is preferably 5 to 15 ppm / K, and the average linear expansion coefficient α2 in the temperature range of glass transition temperature or higher and below 300°C is 25 ppm / K or higher and 65 ppm / K or lower. As a result, the thermal expansion coefficient of the encapsulating material 6 and the thermal expansion coefficient of the metal constituting the substrate and lead frame are approximately the same, and even when the power module is used in a high-temperature environment, warping is reduced and a high level of adhesion to the metal members is achieved. As a result, the reliability of the power module obtained can be improved. Here, the linear expansion coefficient α of the Cu substrate is approximately 15 to 20 ppm / K.

[0068] The thermosetting resin composition of this embodiment, by containing the above components, has a die shear strength against copper at 230°C of 3.0 MPa or more, as measured by the following procedure: <Procedure> Using a low-pressure transfer molding machine, the thermosetting resin composition is molded under the conditions of a mold temperature of 175°C, an injection pressure of 10 MPa, and a curing time of 120 seconds, and then applied to a copper lead frame by 10 mm ２Four test pieces are molded per level. Subsequently, the die shear strength between the test piece and the copper lead frame is measured at 230°C using an automatic die shear measuring device. The die shear strengths of the four test pieces are adopted. In another embodiment, the die shear strength of the thermosetting resin composition measured by the above procedure against copper at 230°C is preferably 3.0 to 10 MPa, preferably 3.5 to 10 MPa, and more preferably 3.8 to 10 MPa. Furthermore, the die shear strength of the thermosetting resin composition in this embodiment against copper at room temperature (25°C) is, for example, 5 to 20 MPa, preferably 8 to 15 MPa.

[0069] The thermosetting resin composition of this embodiment, by containing the above components, has a die shear strength against silver at 230°C of 3.0 MPa or more, as measured by the following procedure: <Procedure> Using a low-pressure transfer molding machine, the thermosetting resin composition is molded under the conditions of a mold temperature of 175°C, an injection pressure of 10 MPa, and a curing time of 120 seconds, and then applied to a silver lead frame by 10 mm ２ Four test pieces are molded for each level. Subsequently, the die shear strength between the test piece and the silver lead frame is measured at 230°C using an automatic die shear measuring device. The die shear strengths of the four test pieces are adopted. In another embodiment, the die shear strength of the thermosetting resin composition measured by the above procedure against silver at 230°C is preferably 3.0 to 10 MPa, preferably 3.5 to 10 MPa, and more preferably 3.8 to 10 MPa. Furthermore, the die shear strength of the thermosetting resin composition in this embodiment against silver at room temperature (25°C) is, for example, 5 to 20 MPa, preferably 8 to 15 MPa.

[0070] The thermosetting resin composition of this embodiment, by containing the above components, has a die shear strength against gold at 230°C of 2.0 MPa or more, as measured by the following procedure: <Procedure> Using a low-pressure transfer molding machine, the thermosetting resin composition is molded under the conditions of a mold temperature of 175°C, an injection pressure of 10 MPa, and a curing time of 120 seconds, and then applied to a gold lead frame by 10 mm２ Four test pieces are molded per level. Subsequently, using an automatic die shear measurement device, the die shear strength between the test piece and the gold lead frame is measured at 230°C. The die shear strength of the four test pieces is adopted. In another embodiment, the die shear strength of the thermosetting resin composition measured according to the above <Procedure> against gold at 230°C is preferably 2.0 to 10 MPa, preferably 2.5 to 10 MPa, and more preferably 2.8 to 10 MPa. Also, the thermosetting resin composition of this embodiment has a die shear strength against gold at room temperature (25°C) of, for example, 5 to 20 MPa, preferably 8 to 15 MPa.

[0071] By including the above components, the thermosetting resin composition of this embodiment has a high adhesion strength to metals that are generally used for members that are the encapsulated objects. Therefore, the power module obtained by using the thermosetting resin composition of this embodiment as a sealing material has no or reduced crack generation between the metal member and the sealing material and is excellent in reliability.

[0072] [Power Module] The power module according to this embodiment will be described.

[0073] <Power Module 10> FIG. 1 is a cross-sectional view schematically showing the power module 10 according to the embodiment of the present invention. Hereinafter, for simplicity of explanation, there may be cases where the positional relationship (vertical relationship, etc.) of each component of the power module 10 is described as the relationship shown in each figure. However, the positional relationship in this explanation is independent of the positional relationship during the use or manufacture of the power module 10.

[0074] The power module of this embodiment comprises a metal circuit board, a power semiconductor element provided on one side of the metal circuit board, a bonding layer made of sintering paste that bonds the power semiconductor element and the metal circuit board, a heat dissipation sheet laminated on the side of the metal circuit board opposite to the side on which the power semiconductor element is provided, and a sealing material that covers the power semiconductor element, the bonding layer, the circuit board, and the heat dissipation sheet, wherein the sealing material is made from a cured product of the thermosetting resin composition of this embodiment described above. The power module 10 of this embodiment will be described in detail below.

[0075] As shown in Figure 1, the power module 10 of this embodiment has a laminated structure consisting of a Cu circuit 3 as a metal circuit board and a power semiconductor element 1 provided on one side of the Cu circuit 3 via a sintering layer 2 made of sintering paste, which is bonded to a Cu base plate (heat dissipation member) 5 via a heat dissipation sheet 4. In the power module 10, the power semiconductor element 1 is electrically connected by a lead frame 7. In the power module 10, the Cu base plate 5, heat dissipation sheet 4, Cu circuit 3, sintering layer 2, power semiconductor element 1 and lead frame 7 are sealed with a sealing material 6. The individual components of the power module 10 will be described below.

[0076] (Power semiconductor element 1) The power semiconductor element 1 is, for example, an insulated gate bipolar transistor (IGBT) and a diode. An electrode pattern (not shown) is formed on the upper surface of the power semiconductor element 1, and a conductive pattern (not shown) is formed on the lower surface of the power semiconductor element 1. The lower surface of the power semiconductor element 1 is bonded to one side of the Cu circuit 3 via a sintering layer 2, which is a junction layer. The electrode pattern on the upper surface of the power semiconductor element 1 is electrically connected to the lead frame 7.

[0077] Power semiconductor device 1 is, for example, SiC, GaN, Ga ２ O ３Alternatively, it is a semiconductor made of diamond. The power consumption of the power semiconductor element 1 is, for example, 2.0 W or more, preferably 3.0 W or more, and may also be, for example, 4.0 W or less. The voltage of the power semiconductor element 1 is, for example, 1.0 V or more, preferably 3.0 V or more, and may also be, for example, 5.0 V or more. The voltage of the power semiconductor element 1 may also be, for example, 100 V or less. The power density of the power semiconductor element 1 is, for example, 10 W / cm². ３ The above is preferable, with a load of 20 W / cm². ３ That's all, and also, for example, 30 W / cm² ３ The above values ​​may also be used. Furthermore, the power density of the power semiconductor element 1 may be, for example, 200 W / cm². ３ The following is also possible. Furthermore, the power semiconductor element 1 can operate at higher temperatures than conventional semiconductors made of Si, for example, in high-temperature environments of 200°C or higher.

[0078] (Sintering layer 2) Sintering layer 2 is a bonding layer formed by sintering a sintering paste containing metal particles. As the sintering paste, any of the following can be used: Ag sintering paste containing silver particles, Al sintering paste containing aluminum particles, or Cu sintering paste containing copper particles.

[0079] A sintering paste as described above is placed between the power semiconductor element 1 and the Cu circuit 3 and stacked, and the power semiconductor element 1 and the Cu circuit 3 are joined by the sintering layer 2 through a sintering process. The Cu circuit 3 and the lead frame 7 are joined by the sintering layer 2. In the sintering layer 2, a sintering network (metal bonding bus) made of metal particles is formed, achieving high thermal conductivity and low electrical resistance. From the viewpoint of improving the bonding performance by the sintering layer 2, the Cu circuit 3 and the lead frame 7 may be subjected to a surface treatment of plating with the metal contained in the sintering paste. Specifically, in this embodiment, Ag plating may be applied to the surface of the Cu circuit 3 and the lead frame 7.

[0080] (Cu Circuit 3) Cu Circuit 3 is a metal circuit board made of a conductive metallic material. A power semiconductor element 1 is provided on a circuit pattern formed on one side of Cu Circuit 3 (the upper side in the figure) via a sintering layer 2, which is a bonding layer.

[0081] The Cu circuit 3 is a circuit board patterned with thick copper (rolled copper), for example, having a thickness of 0.3 mm or more and 5 mm or less. For example, thick copper (rolled copper) can be suitably used as the metal material constituting the Cu circuit 3. This results in a relatively low resistance value for the Cu circuit 3. At least a portion of the Cu circuit 3 may be covered with a solder resist layer.

[0082] The Cu circuit 3 is formed, for example, by cutting and etching a metal layer (such as thick copper) laminated on the upper surface of the base 5A of the Cu base plate 5 via a heat dissipation sheet 4 into a predetermined pattern, or by attaching the Cu circuit 3 to the heat dissipation sheet 4 in a state where it has been pre-processed into a predetermined pattern.

[0083] The lower limit of the thickness of the Cu circuit 3 is, for example, 0.3 mm or more. A thickness of this value or higher can suppress heat generation in the circuit pattern, even in applications requiring high current. The upper limit of the thickness of the circuit pattern 20 is, for example, 5.0 mm or less, preferably 4.0 mm or less, and even more preferably 3.0 mm or less. A thickness of this value or lower can improve circuit processability and allow for a thinner overall substrate.

[0084] (Heat dissipation sheet 4) The heat dissipation sheet 4 is placed between the Cu circuit 3 and the Cu base plate 5. The heat from the power semiconductor element 1 is received by the Cu circuit 3 and then transferred to the Cu base plate 5, which is a heat dissipation means, via the heat dissipation sheet 4. This allows the heat generated from the heat-generating power semiconductor element 1 to be effectively dissipated to the outside of the power module 10 while maintaining the insulation of the power module 10. As a result, the insulation reliability of the power module 10 can be improved.

[0085] The planar shape of the heat dissipation sheet 4 is not particularly limited and can be appropriately selected to match the shape of the Cu circuit 3 and Cu base plate 5, but it can be rectangular, for example. The film thickness of the heat dissipation sheet 4 is, for example, 50 μm or more and 250 μm or less. This improves mechanical strength and heat resistance while more effectively transferring heat from the Cu circuit 3 to the Cu base plate 5. Furthermore, the heat dissipation sheet 4 has an excellent balance of heat dissipation and insulation properties. The thermal conductivity of the heat dissipation sheet 4 is not particularly limited, but preferably it is 10 W / mK (175°C) or more, more preferably 15 W / mK (175°C) or more.

[0086] (Cu base plate 5) The Cu base plate 5 is a type of heat dissipation member and has a copper plate-shaped base portion 5A and a plurality of fin portions 5B that extend integrally from the lower surface of the base portion 5A. In addition to the Cu base plate 5, an aluminum base plate may also be used as a heat dissipation member. Furthermore, as long as it has the function of acquiring the heat generated by the power semiconductor chip 1 via the Cu circuit 3 and dissipating it elsewhere, it is not limited to a general heat dissipation member, but may also be part of another component (for example, the housing).

[0087] (Lead frame 7) The lead frame 7 supports and fixes the power semiconductor chip 1 and also makes electrical connections with external wiring. It is a component made from a thin sheet of metal material such as copper or iron by pressing or etching.

[0088] (Sealing material 6) The sealing material 6 is made from a cured product of the thermosetting resin composition of this embodiment. The sealing material 6 integrally seals the power semiconductor chip 1, the sintering layer 2, the Cu circuit 3, the heat dissipation sheet 4, the Cu base plate 5, and the lead frame 7 inside.

[0089] In this sealing process, a portion of the lead frame 7 is sealed, while the remaining unsealed portion is connected to external equipment. Furthermore, the upper and side surfaces of the base portion 5A of the Cu base plate 5 are covered and sealed by the sealing material 6. The lower surface and fin portion 5B of the Cu base plate 5 are not covered by the sealing material 6. In other words, the sealing material 6 covers and seals the power semiconductor chip 1 by covering part or all of the side surfaces in the thickness direction of the base portion 5A of the Cu base plate 5. Here, a configuration in which all of the side surfaces of the base portion 5A of the Cu base plate 5 are covered by the sealing material 6 is illustrated.

[0090] The cured product of the thermosetting resin composition of this embodiment, which constitutes the encapsulant 6, has a glass transition temperature of 190°C or higher, preferably 200°C or higher, more preferably 210°C or higher, and 300°C or lower. The average linear expansion coefficient α1 of the cured product of the thermosetting resin composition of this embodiment in the temperature range of 20°C or higher and below the glass transition temperature is preferably 5 to 15 ppm / K, and the average linear expansion coefficient α2 in the temperature range of glass transition temperature or higher and below 300°C is 25 ppm / K or higher and 65 ppm / K or lower. As a result, the thermal expansion coefficient of the encapsulant 6 is approximately the same as that of the Cu substrate 3, heat dissipation sheet 4, and sintering layer 2, and even when the power module is used in a high-temperature environment, warping is reduced and a high level of adhesion between the Cu substrate 3, heat dissipation sheet 4, and sintering layer 2 is achieved. As a result, the reliability of the resulting power module can be improved. Here, the average linear expansion coefficient α1 of the heat dissipation sheet 4 below the glass transition temperature is about 10 to 15 ppm / K, and the average linear expansion coefficient α2 of the heat dissipation sheet 4 in the range from above the glass transition temperature to 300°C is about 20 to 25 ppm / K. The linear expansion coefficient α of the sintering layer 2 is about 20 to 25 ppm / K. The linear expansion coefficient α of the Cu substrate is about 15 to 20 ppm / K. The cured product of the thermosetting resin composition of this embodiment has high adhesion to all of the heat dissipation sheet 4, the sintering layer 2, and the Cu substrate because their linear expansion coefficients are all close to those of the heat dissipation sheet 4 and the Cu substrate. The linear expansion coefficient of the thermosetting resin composition of this embodiment can be achieved by adopting the above formulation.

[0091] <Power Module 100> A power module according to a further embodiment of the present invention will now be described. Figure 2 is a schematic cross-sectional view of the power module 100 according to this embodiment. The power module 100 comprises a substrate 10, a power semiconductor element 20 mounted on one surface of the substrate 10 via an adhesive layer 40, wires 60 that electrically connect the power semiconductor element 20 and the substrate 10, a lead frame 70 electrically connected to the substrate 10, and a sealing material 50 that seals a part of the power semiconductor element 20, the substrate 10, the wires 60 and the lead frame 70. Furthermore, a heat sink 80 is connected to the other surface of the substrate 10 (the side on which the power semiconductor element 20 is not mounted) via an adhesive layer 90. The sealing material 50 is made of a cured product of the thermosetting resin composition described above. Here, the substrate 10 is a circuit board having a ceramic substrate (or resin sheet) 12 which is an insulating substrate, a copper circuit layer 11 formed on one surface of the ceramic substrate 12 and a copper layer 13 formed on the other surface of the ceramic substrate 12. The power semiconductor element 20 is mounted on the copper circuit layer 11. The lead frame 70 is a terminal for electrical connection with external equipment and is made of a conductive material such as copper or a copper alloy. One end of the lead frame 70 is joined to the circuit pattern 11 of the substrate 10 using a thermally conductive bonding material such as silver paste or solder, and the other end extends outward from the side of the sealing material 50.

[0092] The power semiconductor element 20 is, for example, an insulated gate bipolar transistor (IGBT) and a diode. The power semiconductor element 20 is, for example, SiC, GaN, Ga ２ O ３ Alternatively, it may be a semiconductor made of diamond. Such a power semiconductor element 20 can operate at higher temperatures than conventional silicon semiconductors, for example, in high-temperature environments of 200°C or higher. Furthermore, the power consumption of the power semiconductor element 20 is, for example, 2.0W or more, and the power density is, for example, 10W / cm². ３ That's all.

[0093] The encapsulant 50 is provided to protect the power semiconductor element 20 and wire 60 from the external environment and to ensure insulation. In this embodiment, the encapsulant 50 is formed by transfer molding, compression molding, or the like, and is formed on the substrate 10, covering the power semiconductor element 20.

[0094] As shown in Figure 2, the power module 100 is equipped with a heat sink 80 on the back side of the substrate 10. The heat sink 80 is bonded to the substrate 10 via an adhesive layer 90 and efficiently dissipates heat transferred from the power semiconductor element 20 through the substrate 10. In this embodiment, it is preferable that the adhesive layer 90 be a sintered body of a sinterable metal paste (sintering paste or semi-sintering paste) containing silver particles or the like, or a thermally conductive bonding material such as solder. In particular, using a sinterable metal paste as the thermally conductive bonding material provides extremely high thermal conductivity and heat resistance. The heat sink 80 may have multiple fins to improve heat dissipation efficiency.

[0095] In this embodiment, the thermosetting resin composition described above is used as the encapsulant 50. The bonding process of the heat sink 80 using the sintering material requires high-temperature heating of 200°C or higher (for example, 200°C to 250°C). In this case, in a structure where the encapsulant 50 is present only on one side of the substrate 10, thermal expansion due to high-temperature heating and subsequent cooling contraction occur, causing significant warping and stress throughout the package due to the difference in the coefficients of linear expansion of the substrate 10, the encapsulant 50, and the heat sink 80. This may cause cracks in the encapsulant 50 or delamination at the interface with the substrate 10. The encapsulant 50 (resin composition) in this embodiment achieves a high Tg by employing a specific naphthalene-type epoxy resin (a1), suppressing softening deformation even in sintering processes above 200°C and maintaining heat resistance. Furthermore, by incorporating core-shell type rubber particles, the modulus of elasticity is reduced, effectively mitigating thermal stress generated during high-temperature processes and cooling. This allows for improved heat dissipation through sintering bonding while ensuring high reliability without cracks or delamination.

[0096] (Manufacturing Method for Power Modules) Next, an example of a manufacturing method for the power module 100 according to this embodiment will be described. The manufacturing method of this embodiment has the following steps: (Step 1) A step of mounting semiconductor elements onto a substrate. (Step 2) A step of sealing the semiconductor elements. (Step 3) A step of joining the heat sink. Each step will be described below.

[0097] (Step 1) First, a substrate 10 is prepared, and a semiconductor element 20 is bonded to one side of the substrate via an adhesive layer 40. Solder, conductive adhesive, or sintering paste can be used as the adhesive layer 40. Next, an electrical connection (wire 60) is formed between the semiconductor element 20 and the substrate 10 by wire bonding or the like.

[0098] (Step 2) Next, the power semiconductor element 20 and wire 60 on the substrate 10 are encapsulated using the thermosetting resin composition of this embodiment. Transfer molding or compression molding is used as the molding method. This results in a structure in which the power semiconductor element 20 and the like are covered with the encapsulating material 50.

[0099] (Step 3) Next, the heat sink 80 is joined to the other side (back side) of the substrate 10. In this embodiment, a sintering paste, such as a silver paste containing silver particles, is used for this joining. Specifically, the sintering material is applied to the back side of the substrate 10 or to the heat sink 80, and after the two are bonded together, a heat treatment is performed using a sintering furnace or the like. In this sintering process, high-temperature heating is performed, for example, at 200°C or higher, preferably 200°C to 250°C, in order to sinter (sinter) the metal particles and form strong heat conduction paths. Pressurization may also be performed as needed.

[0100] The encapsulant 50, composed of the cured resin composition of this embodiment, maintains a high glass transition temperature (Tg) even at sintering temperatures of 200°C or higher, due to the inclusion of the specific naphthalene-type epoxy resin (a1) described above. Therefore, it exhibits minimal changes in physical properties at high temperatures, maintaining the shape stability of the package. Furthermore, the encapsulant 50 has a low modulus of elasticity due to the inclusion of core-shell type rubber particles. As a result, it can effectively mitigate and absorb the large thermal stress generated between the substrate 10 and the heat sink 80 during the sintering process and the subsequent cooling process. Consequently, a highly reliable power module is provided.

[0101] The embodiments of the present invention have been described above, but these are merely examples, and various other configurations can also be adopted.

[0102] The present invention will be described below with reference to examples and comparative examples, but the present invention is not limited thereto.

[0103] <Examples 1-12, Comparative Examples 1-2> (Preparation of Resin Compositions) For each example and comparative example, the resin composition was prepared as follows. First, the components shown in Table 1 were mixed using a mixer. Next, the resulting mixture was roll-kneaded, cooled, and pulverized to obtain a resin composition in powder form. Details of each component in Table 1 are as follows.

[0104] (Inorganic fillers) ・Inorganic filler 1: Molten spherical silica (Denka Co., Ltd., "FB-560", average particle size 29.5 μm) ・Inorganic filler 2: Molten spherical silica (Denka Co., Ltd., "FB-105", average particle size 10.5 μm) ・Inorganic filler 3: Molten spherical silica (Admatex Co., Ltd., "SC-2500-SQ", average particle size 0.6 μm)

[0105] (Coupling agents) ・Coupling agent 1: N-phenylaminopropyltrimethoxysilane (Toray Dow Co., Ltd., "CF-4083") ・Coupling agent 2: 3-mercaptopropyltrimethoxysilane (JNC Co., Ltd., "S810") ・Coupling agent 3: 3-glycidoxypropyltrimethyldimethoxysilane (JNC Co., Ltd., "S510")

[0106] (Epoxy resins) ・Epoxy resin 1: Polyfunctional epoxy resin (DIC Corporation, "HP-4700-RC", epoxy equivalent: 156 g / eq, epoxy compound represented by the above formula (1) (m=n=2)) ・Epoxy resin 2: Tris(hydroxyphenyl)methane type epoxy resin (Mitsubishi Chemical Corporation, "E-1032H60")

[0107] (Hardening agent) ・Hardening agent 1: Biphenylene skeleton-containing polyfunctional phenolic resin represented by the following formula (12A) (UBE Corporation, phenolic hydroxyl group equivalent 135 g / e)

[0108]

[0109] In formula (12A), the two Ys each independently represent a hydroxyphenyl group represented by formula (12B) or formula (12C) below, and X represents a hydroxyphenylene group represented by formula (12D) or formula (12E) below. n represents an integer between 0 and 10.

[0110]

[0111] • Hardener 2: Trisphenylmethane-type phenol novolac resin (UBE Corporation, "MEH-7500")

[0112] (Curing accelerators) • Curing accelerator 1: 4-hydroxy-2-(triphenylphosphonium)phenolate • Curing accelerator 2: 2,3-dihydroxynaphthalene • Curing accelerator 3: Tetraphenylphosphonium 4,4'-sulfonyldiphenolate

[0113] (Release agent) • Release agent 1: Carnauba wax (Toagosei Co., Ltd., "TOWAX-132")

[0114] (Ion scavengers) • Ion scavenger 1: Magnesium aluminum hydroxide carbonate hydrate (Kyowa Chemical Co., Ltd., "DHT-4H")

[0115] (Adhesion enhancers) ・Adhesion enhancer 1: 3-amino-5-mercapto-1,2,4-triazole (Nippon Carbide Co., Ltd.) ・Adhesion enhancer 2: 4,6-diamino-1,3,5-triazine-2-ethanol ・Adhesion enhancer 3: 2-hydroxy-N-1H-1,2,4-triazole-3-ylbenzamide (ADEKA Corporation, "CDA-1M")

[0116] (Low-stress agents) ・Low-stress agent 1: Silicone resin (Shin-Etsu Chemical Co., Ltd., "KR-480") ・Low-stress agent 2: Silicone oil (Toray Dow Corning, "FZ-3730") ・Low-stress agent 3: Polybutadiene (Nippon Soda Co., Ltd., "JP200") ・Low-stress agent 4: Silicone elastomer (Toray Dow Corning, "CF-2152") ・Low-stress agent 5: Core-shell type rubber particles (Core: Butadiene-based rubber, Shell: Acrylic-based rubber) (Dow Chemical, "EXL-2655") ・Low-stress agent 6: Core-shell type rubber particles (Acrylic-based rubber) (Aica Kogyo Co., Ltd., "AC-3832SD")

[0117] (Coloring agent) ・Coloring agent 1: Carbon black

[0118] (Physical Property Evaluation) The physical properties of the resin compositions obtained in each example were evaluated using the following method. In Table 1, "-" indicates that the measurement was not performed.

[0119] (Spiral Flow (SF) and Gel Time) The spiral flow was measured for the resin compositions of Examples 1-4 and Comparative Examples 1-2. The gel time was also measured for the resin compositions of Examples 1-12 and Comparative Examples 1-3. Using a low-pressure transfer molding machine (KTS-15, manufactured by Kotaki Seiki Co., Ltd.), the resin compositions of each example and comparative example were injected into a spiral flow measurement mold conforming to ANSI / ASTM D 3123-72 at 175°C, an injection pressure of 6.9 MPa, and a holding pressure time of 120 seconds. The flow length was measured and defined as the spiral flow. The time from the start of injection until the resin composition hardened and ceased to flow was measured and defined as the gel time. Note that spiral flow is a parameter of fluidity, and a larger value indicates better fluidity.

[0120] (TMA Measurement) The resin compositions obtained in each example were transfer-molded under the conditions of a molding temperature of 175°C for 3 minutes and a post-mode cure of 200°C for 4 hours to obtain cured products. A thermomechanical analyzer (Seiko Instruments, DMS6100) was used to measure the TMA under the conditions of a nitrogen flow rate of 150 mL / min, a heating rate of 10°C / min, a frequency of 10 Hz, a measurement temperature range of 30 to 350°C, and two-handed mode. The obtained TMA measurement data was analyzed, and the average linear expansion coefficient in the temperature range from 20°C to below the glass transition temperature was defined as α1. The unit of α1 is [ppm / K]. The average linear expansion coefficient in the temperature range from above the glass transition temperature to below 300°C was defined as α2. The unit of α2 is [ppm / K].

[0121] (Glass transition temperature (Tg), DMA) Using a transfer molding machine (KTS-15, manufactured by Kotaki Seiki Co., Ltd.), the resin compositions for each example were injected and molded at a mold temperature of 175°C, an injection pressure of 6.9 MPa, and a curing time of 120 seconds to obtain cured products of 10 mm × 4 mm × 4 mm. After curing at 200°C for 4 hours, these were used as test specimens. In accordance with JIS K 6911, DMA was measured using a DMA measuring device (manufactured by Seiko Instruments Inc.) under the conditions of a measurement temperature range of 0°C to 400°C, a heating rate of 5°C / min, and 10 Hz, and a tanδ chart of the test specimens was obtained. The glass transition temperature Tg (°C) was calculated from the peak values ​​of the tanδ charts obtained for each example.

[0122] (Flexural modulus, flexural strength) Using a low-pressure transfer molding machine (KTS-30, manufactured by Kotaki Seiki Co., Ltd.), the resin composition was injected and molded under the conditions of a mold temperature of 175°C, injection pressure of 9.8 MPa, and curing time of 120 seconds to obtain a molded product with a length of 80 mm, a width of 10 mm, and a thickness of 4 mm. The obtained molded product was heat-treated at 200°C for 4 hours as a post-curing test piece, and the flexural modulus and flexural strength were measured in accordance with JIS K 6911 at ambient temperatures of 25°C and 260°C.

[0123] (Specific Gravity) The specific gravity of the resin compositions obtained in each example was measured using the water displacement method (Archimedes method).

[0124] (Water Absorption Rate) Using a low-pressure transfer molding machine (KTS-30, manufactured by Kotaki Seiki Co., Ltd.), a resin composition was injected and molded under the conditions of a mold temperature of 175°C, an injection pressure of 7.4 MPa, and a curing time of 120 seconds to produce test specimens with a diameter of 50 mm and a thickness of 3 mm. These specimens were cured at 200°C for 4 hours. Subsequently, the obtained test specimens were subjected to humidification treatment in a boiling environment for 24 hours, and the water absorption rate was determined by measuring the weight change before and after the humidification treatment.

[0125] (Reliability 1: Presence or absence of delamination at the interface between the copper lead frame and the sealing resin) For each resin composition obtained in the example, the sealing resin was molded onto a PKG containing an AMB substrate (24 mm x 28 mm, 1 mm thick) using a low-pressure transfer molding machine (Apic Yamada "MSL-06M") at a mold temperature of 175°C, injection pressure of 10 MPa, and curing time of 180 seconds. A test semiconductor device was then fabricated by post-mold curing (PMC) at 200°C for 4 hours. After pressing the sealed test semiconductor device at 230°C and 15 MPa for 3 minutes, the presence or absence of delamination at the interface between the lead frame and the sealing resin was observed using an ultrasonic testing (SAT) device. The results are shown in Table 1 according to the following evaluation criteria. <Evaluation Criteria> A: No delamination is observed at the interface between the lead frame and the sealing resin. B: Delamination is observed at the interface between the lead frame and the sealing resin.

[0126] (Reliability 2: Presence or absence of cracks at the interface between the sintering layer and the sealing resin) For each resin composition obtained in the example, a PKG (lead frame made of Cu, sintering layer made of silver paste) containing an AMB substrate (24 mm x 28 mm, thickness 1 mm) was molded using a low-pressure transfer molding machine (Apic Yamada "MSL-06M") at a mold temperature of 175°C, injection pressure of 10 MPa, and curing time of 180 seconds. A test semiconductor device was then fabricated by performing post-mold curing (PMC) at 200°C for 4 hours. After pressing the sealed test semiconductor device at 230°C and 15 MPa for 3 minutes, the presence or absence of cracks at the interface between the sintering layer and the sealing resin was observed using an ultrasonic testing (SAT) device. The results are shown in Table 1 according to the following evaluation criteria. <Evaluation Criteria> A: No cracks are observed at all at the interface between the sintering layer and the sealing resin. B: Delamination is observed at the interface between the sintering layer and the sealing resin.

[0127] (Reliability 3: Tracking Resistance (CTI) Test) For each example and comparative example, the obtained resin composition was cured and molded under the conditions of a molding temperature of 175°C, a molding pressure of 6.9 MPa, and a molding time of 120 seconds to form a cured product with a thickness of 3 mm and a diameter of 50 mm. The cured product was post-cured at 200°C for 4 hours. A tracking resistance test was performed using the cured product according to the method of JIS C 2134 (IEC 60112). As the tracking resistance voltage, in an evaluation with n=5 measurements, the maximum voltage at which all cured products did not break was measured using 50 or more drops of a 0.1% aqueous solution of ammonium chloride.

[0128] (Reliability 4: HAST Test) A TEG (Test Element Group) chip (3.5 mm x 3.5 mm) equipped with aluminum electrode pads was mounted on the die pad portion of a lead frame whose surface was plated with Ag. Next, the electrode pads of the TEG chip, the outer lead portion of the lead frame, and a bonding wire made of a copper alloy containing 99.9 mass% Cu were wire-bonded at a wire pitch of 120 μm. The resulting structure was then encapsulated and molded using the resin composition of each example under the conditions of a mold temperature of 175°C, injection pressure of 10.0 MPa, and curing time of 2 minutes using a low-pressure transfer molding machine to produce a semiconductor package. Subsequently, the obtained semiconductor package was post-cured at 200°C for 4 hours to obtain a test semiconductor device. The obtained test semiconductor device was left to stand in an environment with a temperature of 130°C, humidity of 85% RH, and voltage of 20 V, and the resistance value was measured every 40 hours up to 240 hours. Tests whose resistance value exceeded 1.2 times the initial value before 200 hours were deemed unsuccessful, while those whose resistance value did not exceed 1.2 times the initial value after 200 hours were deemed successful. The number of unsuccessful tests in the evaluation with n=5 measurements is shown in Table 1.

[0129] (Reliability 5: Cooler Bonding Test) A bonding material (semi-sintering paste) was dispensed onto 28 mm x 39 mm modules sealed using the resin compositions of each example and comparative example. A Cu metal plate simulating a cooler was placed on top, and the modules were bonded under a nitrogen atmosphere at 175°C for 120 minutes (150 minutes of heating). After bonding, cracks and internal delamination of the modules were observed using a scanning electron microscope. A: No delamination or cracks were observed. B: Either delamination or cracks, or both, were observed.

[0130]

[0131] This application claims priority based on Japanese Patent Application No. 2025-006105 filed on 16 January 2025, Japanese Patent Application No. 2025-144645 filed on 1 September 2025, and Japanese Patent Application No. 2026-001049 filed on 6 January 2026, and incorporates all disclosures thereof herein.

[0132] 1 Power semiconductor element 2 Sintering layer 3 Cu circuit (metal circuit board) 4 Heat dissipation sheet 5 Cu base plate (heat dissipation material) 6 Encapsulation material 7 Lead frame 10 Power module 100 Power module 10 Substrate 11 Copper circuit layer 12 Ceramic substrate (resin sheet) 13 Copper layer 20 Power semiconductor element 40 Adhesive layer (die attach material) 50 Encapsulation material 60 Electrical connection (wire) 70 Lead frame 80 Heat sink 90 Adhesive layer (sintering paste)

Claims

A thermosetting resin composition comprising an epoxy resin (A), a phenolic resin curing agent (B), and an inorganic filler (C), The epoxy resin (A) is It contains a naphthalene-type epoxy resin (a1) represented by formula (1), In equation (1), m is 2 and n is 2, The glass transition temperature of the thermosetting resin composition, measured by thermomechanical analysis (TMA) under a heating rate of 5°C / min, is 190°C or higher. A thermosetting resin composition having a die shear strength against copper at 230°C of 3.0 MPa or higher, as measured by the following procedure; <Instructions> Using a low-pressure transfer molding machine, the thermosetting resin composition was molded under the conditions of a mold temperature of 175°C, an injection pressure of 10 MPa, and a curing time of 120 seconds, and then applied to a copper lead frame by 10 mm. ２ Four test specimens are molded for each level. Next, using an automated die-shear measuring device, the die-shear strength between the test specimen and the copper lead frame is measured at 230°C. The die-shear strengths of four test specimens are adopted. 　 A thermosetting resin composition according to claim 1, The epoxy resin (A) is a thermosetting resin composition further comprising a triphenylmethane-type epoxy resin (a2). 　 A thermosetting resin composition according to claim 1 or 2, The phenol resin curing agent (B) is a thermosetting resin composition comprising a polyfunctional phenol resin, a phenol aralkyl type phenol resin, or a combination thereof. 　 A thermosetting resin composition according to any one of claims 1 to 3, The phenolic resin curing agent (B) is a thermosetting resin composition comprising a trisphenylmethane-type phenolic resin, a biphenyl skeleton-containing polyfunctional phenolic resin, or a combination thereof. 　 A thermosetting resin composition according to any one of claims 1 to 4, A thermosetting resin composition further containing a stress-reducing agent. 　 A thermosetting resin composition according to claim 5, The low-stress agent is a thermosetting resin composition comprising at least one selected from butadiene rubber, nitrile rubber, silicone rubber, core-shell type rubber particles, and silicone oil. 　 The thermosetting resin composition according to claim 6, The low-stress agent is a thermosetting resin composition containing core-shell type rubber particles. 　 A thermosetting resin composition according to any one of claims 1 to 7, A thermosetting resin composition further comprising an adhesion promoter. 　 A thermosetting resin composition according to any one of claims 1 to 8, The inorganic filler (C) is a thermosetting resin composition containing silica powder. 　 Metal circuit board and A power semiconductor element provided on one side of the aforementioned metal circuit board, A bonding layer consisting of sintering paste that bonds the power semiconductor element and the metal circuit substrate, A heat dissipation sheet laminated on the metal circuit board opposite to the side on which the power semiconductor element is provided, A power module comprising the power semiconductor element, the junction layer, the circuit board, and a sealing material covering the heat dissipation sheet, The sealing material consists of a cured product of the thermosetting resin composition described in any one of claims 1 to 9. Power module. 　 Circuit board and A power semiconductor element mounted on one surface of the circuit board, the power semiconductor element having an electrical connection from the power semiconductor element to the circuit board, A sealing material provided on one surface of the circuit board, which seals the power semiconductor element, the circuit board, and the electrical connections, A power module comprising a heat sink connected to the other side of the circuit board via a thermally conductive bonding material, The sealing material is made of a cured product of the thermosetting resin composition described in any one of claims 1 to 9, in a power module.

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