JP7501801B2 - Molding resin composition, method for producing sealed structure, and sealed structure - Google Patents

Description

The present invention relates to a molding resin composition, a method for producing a sealing structure, and a sealing structure.

To protect electronic components such as semiconductor elements or structures such as stators from the external environment, a method of encapsulating them using thermosetting resins is widely used. In particular, the transfer molding method using epoxy resin as the encapsulating resin is economical and productive, and is suitable for mass production, making it the mainstream method of resin encapsulation.

Patent Document 1 (JP Patent Publication 2003-284277A) describes a technology for using a resin material in a stator core. The document describes a rotating electric machine having a stator in which multiple coils are wound at regular intervals around a stator core made of multiple laminated electromagnetic steel sheets, a rotor that is rotatably held relative to the stator, and a cooling frame to which the stator is fixed, in which a highly heat-conductive composite material made of a thermosetting resin with an anisotropic structure in the resin component is arranged in the slots that form the winding portion of the stator. It is said that this configuration provides a rotating electric machine with good heat dissipation properties, where heat generated in the coils is easily transferred.

JP 2003-284277 A

However, resin compositions of the prior art require high-temperature processing for curing, leaving room for improvement in terms of workability. Also, sealing structures using resin compositions of the prior art leave room for improvement in terms of adhesion to structures such as electronic components and stators, and waterproofing, which can cause problems with the sealing structures.

The present invention has been made in consideration of these circumstances, and aims to provide a molding resin composition that can be cured at low temperatures and can improve adhesion and waterproofing when used to seal structures such as electronic components or stators.

As a result of their investigations, the inventors have completed the invention provided below and solved the above-mentioned problems.

According to the present invention,
The following molding resin composition, method for producing a sealed structure, and sealed structure are provided.

[1]
A molding resin composition used to collectively seal a substrate on which electronic components are mounted, a stator core fixed on the substrate and having a plurality of slots formed in the circumferential direction, and a plurality of coils housed in the slots,
Epoxy resin,
a curing agent and/or a curing catalyst;
an inorganic filler;
The molding resin composition is cured at 140° C. for 2 minutes, and the cured product has a flexural modulus at 25° C. (in accordance with JIS K6911:2006) of 0.1 GPa or more and 30 GPa or less.
[2]
In the molding resin composition according to the above [1],
A molding resin composition having a glass transition temperature (Tg) of 140° C. or higher and 300° C. or lower, as measured by the following (Method 1).
(Method 1)
The molding resin composition is molded into a test piece of 80 mm x 10 mm x 4 mm using a transfer molding machine at a mold temperature of 175 ° C, injection pressure of 6.9 MPa, and curing time of 90 seconds, and then post-cured at 175 ° C for 2 hours. Furthermore, the thermal expansion coefficient of the test piece obtained is measured at a heating rate of 5 ° C / min using a thermomechanical analyzer. Next, based on the obtained measurement results, the glass transition temperature (Tg) ( ° C) of the cured product is calculated from the inflection point of the thermal expansion coefficient.
[3]
In the molding resin composition according to the above [1] or [2],
The molding resin composition, wherein the epoxy resin comprises one or more selected from the group consisting of phenol novolac type epoxy resins, cresol novolac type epoxy resins, and trisphenolmethane type epoxy resins.
[4]
In the molding resin composition according to any one of the above [1] to [3],
A molding resin composition, wherein the content of the epoxy resin is 3% by mass or more and 40% by mass or less, when the total solid content of the molding resin composition is 100% by mass.
[5]
In the molding resin composition according to any one of the above [1] to [4],
A molding resin composition comprising the above curing agent, wherein the curing agent comprises a phenolic resin-based curing agent.
[6]
In the molding resin composition according to the above [5],
The molding resin composition, wherein the phenolic resin-based curing agent comprises one or more selected from the group consisting of phenol novolac resins, cresol novolac resins, naphthol novolac resins and trisphenolmethane type phenolic resins.
[7]
In the molding resin composition according to the above [5] or [6],
The molding resin composition, wherein the content of the curing agent is 0.8% by mass or more and 12% by mass or less, when the total solid content of the molding resin composition is 100% by mass. [8]
In the molding resin composition according to any one of the above [1] to [7],
A molding resin composition comprising the above curing catalyst, the curing catalyst comprising an imidazole-based compound.
[9]
In the molding resin composition according to the above [8],
The molding resin composition has a content of the curing catalyst of 0.01% by mass or more and 2.0% by mass or less, when the total solid content of the molding resin composition is taken as 100% by mass.
[10]
In the molding resin composition according to any one of the above [1] to [9],
The molding resin composition satisfies S2 ≧ 0.8 × S1, where _S1 is a spiral flow measured for the molding resin composition at a mold temperature of 175°C, an injection pressure of 9.8 MPa, and a curing time of 3 minutes, and _S2 is a spiral flow measured for the molding resin composition after leaving the composition at 25°C for 48 hours, at a mold temperature of 175°C, an injection _pressure of 9.8 _MPa , and a curing time of 3 minutes.
[11]
In the molding resin composition according to any one of the above [1] to [10],
A molding resin composition, in which the time required for a torque value to reach 2 N·m, as measured by the following (Method 2), is less than 100 seconds.
(Method 2)
Using a Curastometer (registered trademark), the torque value of the molding resin composition is measured over time at a mold temperature of 140° C. and an amplitude angle of ±0.25°. Based on the measurement results, the time (seconds) from the start of measurement until the torque value reaches 2 N·m is calculated.
[12]
In the molding resin composition according to any one of the above [1] to [11],
A molding resin composition having a spiral flow of 70 cm or more, as measured by the following (Method 3).
(Method 3)
The above molding resin composition is injected into a spiral flow measurement mold in accordance with ANSI/ASTM D 3123-72 using a low-pressure transfer molding machine under conditions of 175°C, injection pressure of 6.9 MPa, and pressure retention time of 3 minutes, and the flow length is measured, which is defined as the spiral flow (cm).
[13]
In the molding resin composition according to any one of the above [1] to [12],
A molding resin composition having a gel time of 30 seconds or more, as measured by the following (Method 4).
(Method 4)
The molding resin composition is injected into a spiral flow measurement mold conforming to ANSI/ASTM D 3123-72 using a low-pressure transfer molding machine under conditions of 175° C., injection pressure of 6.9 MPa, and pressure retention time of 3 minutes. The time from the start of injection until the molding resin composition hardens and no longer flows is measured and taken as the gel time (seconds).
[14]
In the molding resin composition according to any one of the above [1] to [13],
A molding resin composition having a linear expansion coefficient α1 of 10.0 ppm/° C. or less, as measured by the following (Method 5).
(Method 5)
The molding resin composition is injected and molded using a low-pressure transfer molding machine under conditions of a mold temperature of 175°C, an injection pressure of 9.8 MPa, and a curing time of 3 minutes to obtain a molded product of 15 mm x 4 mm x 4 mm. The molded product obtained is then post-cured at 175°C for 4 hours to prepare a test piece. The average linear expansion coefficient α1 (ppm/°C) of the obtained test piece at 25-70°C is measured using a thermomechanical analyzer under conditions of a measurement temperature range of 0°C to 400°C and a heating rate of 5°C/min.
[15]
In the molding resin composition according to any one of the above [1] to [14],
A molding resin composition having a thermal conductivity of 0.5 W/m·K or more, as measured by the following (Method 6).
(Method 6)
The molding resin composition is injected and molded using a transfer molding machine under the conditions of a mold temperature of 175°C, an injection pressure of 6.9 MPa, and a curing time of 90 seconds to obtain a molded body of 80 mm x 10 mm x 4 mm. The molded body obtained is then post-cured at 175°C for 2 hours to obtain a test piece. The thermal diffusivity of the obtained test piece is measured using a laser flash method. In addition, the specific gravity of the test piece used for the thermal conductivity measurement is measured using an electronic specific gravity meter. Furthermore, the specific heat of the test piece used for the thermal conductivity and specific gravity measurement is measured using a differential scanning calorimeter. The thermal conductivity (W/m·K) in the thickness direction of the test piece is calculated from the measured values of the thermal diffusivity, specific gravity, and specific heat.
[16]
A step of arranging, in a mold in a transfer molding machine, a substrate on which electronic components are mounted, a stator core having a plurality of slots formed in a circumferential direction and fixed on the substrate, and a plurality of coils housed in the slots;
A step of obtaining a sealed structure by encapsulating the substrate, the stator core, and the coil in the mold with the molding resin composition according to any one of [1] to [15] above by a transfer molding method using the transfer molding machine;
A method for manufacturing a sealing structure comprising the steps of:
[17]
In the method for producing a sealing structure according to the above [16],
A method for producing a sealed structure, wherein in the step of obtaining the sealed structure, sealing molding is performed at a temperature equal to or lower than the Tg of a cured product of the molding resin composition.
[18]
In the method for producing a sealing structure according to the above [16] or [17],
A method for producing a sealing structure, in which a post-curing step is not performed as the step of obtaining the sealing structure.
[19]
A substrate on which electronic components are mounted;
a stator core fixed on one surface of the substrate and having a plurality of slots formed in a circumferential direction;
A plurality of coils housed in the slot;
A sealed body including the above-mentioned
a sealing member provided to cover a part or the whole of the sealed object,
A sealed structure, wherein the sealing member is constituted by a cured product of the molding resin composition according to any one of [1] to [15] above.

According to the present invention, a molding resin composition is provided that can be cured at low temperatures and can improve adhesion and waterproofing when sealing structures such as electronic components or stators.

3A to 3C are top views of the sealed body and the sealing structure before and after molding in one example of this embodiment. 3A to 3C are side views of a sealed body and a sealing structure before and after molding in one example of this embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In all the drawings, the same components are given the same reference numerals and the description will be omitted as appropriate.
In this specification, the expression "X to Y" regarding a numerical range means from X to Y, unless otherwise specified. In this specification, the upper and lower limit values regarding a numerical range can be arbitrarily combined, unless otherwise specified.

<Molding resin composition>
The molding resin composition of the present embodiment is a molding resin composition used to collectively seal a substrate on which electronic components are mounted, a stator core fixed on the substrate having a plurality of slots formed in the circumferential direction, and a plurality of coils housed in the slots, the molding resin composition comprising an epoxy resin, a curing catalyst, and an inorganic filler, and a cured product obtained by curing the molding resin composition at 140°C for 2 minutes has a flexural modulus at 25°C (in accordance with JIS K6911:2006) of 0.1 GPa or more and 30 GPa or less.

The molding resin composition of this embodiment is used to collectively seal a substrate on which electronic components are mounted, a stator core having multiple slots formed in the circumferential direction and fixed onto the substrate, and multiple coils housed in the slots. The method of using the moldable resin composition of this embodiment as a sealant is described in detail below.

The molding resin composition of this embodiment has a flexural modulus at 25°C (based on JIS K6911:2006) of 0.1 GPa to 30 GPa in the cured product obtained by curing the molding resin composition at 140°C for 2 minutes. By having a flexural modulus within the above numerical range, the molding resin composition of this embodiment can be cured at a low temperature, and can improve adhesion and waterproofing when sealing structures such as electronic components or stators.

Although the mechanism by which this effect is achieved is unclear, it is believed that by having a flexural modulus within the above numerical range, when a load is applied to the cured product of the molding resin composition of this embodiment, the occurrence of fine cracks in the cured product can be suppressed, resulting in improved adhesion and waterproofing when sealing structures such as electronic components or stators.

The molding resin composition of this embodiment has a flexural modulus (based on JIS K6911: 2006) at 25° C. in a cured product obtained by curing the molding resin composition at 140° C. for 2 minutes, with a lower limit of 0.1 GPa or more, preferably 1.0 GPa or more, more preferably 3.0 GPa or more, even more preferably 5.0 GPa or more, even more preferably 8.0 GPa or more, even more preferably 10.0 GPa or more, even more preferably 12.0 GPa or more, and even more preferably 13.0 GPa or more. By making the flexural modulus equal to or more than the lower limit, a structure having excellent mechanical strength can be obtained even when cured at a low temperature.
The upper limit of the flexural modulus is 30 GPa or less, preferably 27.0 GPa or less, more preferably 24.0 GPa or less, and even more preferably 21.0 GPa or less. By making the flexural modulus equal to or less than the upper limit, the stress accumulated in the cured product is sufficiently small, and warping is reduced. This can improve the adhesion and waterproofing when sealing a structure such as an electronic component or a stator, and the structure is less likely to have defects.

The flexural modulus at 25° C. of the molding resin composition of this embodiment can be measured, for example, by the following method.
Using a low pressure transfer molding machine, the resin composition was injected and molded under the conditions of a mold temperature of 140°C, an injection pressure of 9.8 MPa, and a curing time of 2 minutes to obtain a molded product having 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-cure to obtain a test piece, and the flexural modulus can be measured at an ambient temperature of 25°C in accordance with JIS K 6911:2006. As the low pressure transfer molding machine, for example, KTS-15 or KTS-30 (manufactured by Kotaki Seiki Co., Ltd.) can be used.

Below, we will explain each component used in the molding resin composition of this embodiment.

[Epoxy resin]
Examples of epoxy resins used in the molding resin composition of this embodiment include novolac type epoxy resins such as phenol novolac type epoxy resins and cresol novolac type epoxy resins, bisphenol type epoxy resins such as bisphenol A type epoxy resins and bisphenol F type epoxy resins, aromatic glycidylamine type epoxy resins such as N,N-diglycidylaniline, N,N-diglycidyltoluidine, diaminodiphenylmethane type glycidylamine, and aminophenol type glycidylamine, hydroquinone type epoxy resins, biphenyl type epoxy resins, stilbene type epoxy resins, trisphenolmethane type epoxy resins, trisphenol methane type epoxy resins, and the like. Examples of such epoxy resins include aromatic epoxy resins such as aralkyl type epoxy resins, such as phenol propane type epoxy resins, alkyl modified trisphenol methane type epoxy resins, triazine nucleus-containing epoxy resins, dicyclopentadiene modified phenol type epoxy resins, naphthol type epoxy resins, naphthalene type epoxy resins, phenol aralkyl type epoxy resins having a phenylene and/or biphenylene skeleton, and naphthol aralkyl type epoxy resins having a phenylene and/or biphenylene skeleton, and aliphatic epoxy resins such as alicyclic epoxy resins, such as vinylcyclohexene dioxide, dicyclopentadiene oxide, and alicyclic diepoxy adipide. These may be used alone or in combination of two or more.
Among these, the epoxy resin used in the molding resin composition of this embodiment preferably contains one or more types selected from the group consisting of phenol novolac type epoxy resins, cresol novolac type epoxy resins, and trisphenolmethane type epoxy resins.

The lower limit of the epoxy resin content in the molding resin composition of this embodiment is, from the viewpoint of further improving adhesion and waterproofing when sealing structures such as electronic components or stators, preferably 3 mass % or more, more preferably 4 mass % or more, even more preferably 5 mass % or more, even more preferably 6 mass % or more, and even more preferably 7 mass % or more, when the total solid content of the molding resin composition is taken as 100 mass %.
Furthermore, from the viewpoint of obtaining a structure having excellent mechanical strength even when cured at low temperature, the upper limit of the epoxy resin content is preferably 40% by mass or less, more preferably 30% by mass or less, even more preferably 20% by mass or less, and still more preferably 15% by mass or less, when the total solid content of the molding resin composition is taken as 100% by mass.
The content of the epoxy resin in the molding resin composition of this embodiment, from the viewpoint of further improving adhesion and waterproofing when sealing structures such as electronic components or stators, and from the viewpoint of obtaining structures having excellent mechanical strength even when cured at low temperatures, is preferably 3% by mass or more and 40% by mass or less, more preferably 4% by mass or more and 30% by mass or less, even more preferably 5% by mass or more and 20% by mass or less, even more preferably 6% by mass or more and 20% by mass or less, and even more preferably 7% by mass or more and 15% by mass or less, when the total solid content of the molding resin composition is taken as 100% by mass.

(Hardening agent)
The molding resin composition of this embodiment includes one or both of a curing agent and a curing catalyst. The molding resin composition of this embodiment preferably includes a curing agent in order to three-dimensionally crosslink the epoxy resin, and when the curing agent is included as an essential component, more preferably includes a phenolic resin-based curing agent. Examples of the phenolic resin-based curing agent include novolac-type phenolic resins such as phenol novolac resins, cresol novolac resins, and naphthol novolac resins; multifunctional phenolic resins such as trisphenolmethane-type phenolic resins; modified phenolic resins such as terpene-modified phenolic resins and dicyclopentadiene-modified phenolic resins; aralkyl-type phenolic resins such as phenol aralkyl resins having a phenylene skeleton and/or biphenylene skeleton, and naphthol aralkyl resins having a phenylene and/or biphenylene skeleton; and bisphenol compounds such as bisphenol A and bisphenol F. These may be used alone or in combination of two or more types.

In the molding resin composition of this embodiment, the phenolic resin-based curing agent preferably contains one or more selected from the group consisting of phenol novolac resin, cresol novolac resin, naphthol novolac resin, and trisphenolmethane type phenolic resin. Such a phenolic resin-based curing agent provides a good balance of flame resistance, moisture resistance, electrical properties, curability, storage stability, etc. In particular, from the viewpoint of curability, for example, the hydroxyl group equivalent of the phenolic resin-based curing agent can be 90 g/eq or more and 250 g/eq or less.

In addition, examples of curing agents that can be used in combination include polyaddition type curing agents, catalyst type curing agents, condensation type curing agents, etc.

Examples of polyaddition type curing agents include aliphatic polyamines such as diethylenetriamine (DETA), triethylenetetramine (TETA), and metaxylenediamine (MXDA), aromatic polyamines such as diaminodiphenylmethane (DDM), m-phenylenediamine (MPDA), and diaminodiphenylsulfone (DDS), as well as polyamine compounds including dicyandiamide (DICY) and organic acid dihydrazides; alicyclic acid anhydrides such as hexahydrophthalic anhydride (HHPA), methyltetrahydrophthalic anhydride (MTHPA), and aromatic acid anhydrides such as trimellitic anhydride (TMA), pyromellitic anhydride (PMDA), and benzophenonetetracarboxylic acid (BTDA); polyphenol compounds such as novolac-type phenolic resins and phenol polymers; polymercaptan compounds such as polysulfides, thioesters, and thioethers; isocyanate compounds such as isocyanate prepolymers and blocked isocyanates; and organic acids such as carboxylic acid-containing polyester resins.

Examples of catalyst-type curing agents include tertiary amine compounds such as benzyldimethylamine (BDMA) and 2,4,6-trisdimethylaminomethylphenol (DMP-30); imidazole compounds such as 2-methylimidazole and 2-ethyl-4-methylimidazole (EMI24); and Lewis acids such as _BF3 complex.

Examples of condensation type curing agents include resole resins, urea resins such as methylol group-containing urea resins, and melamine resins such as methylol group-containing melamine resins.

When such other curing agents are used in combination, the lower limit of the content of the phenolic resin-based curing agent is preferably 20% by mass or more, more preferably 30% by mass or more, even more preferably 50% by mass or more, even more preferably 70% by mass or more, and even more preferably 90% by mass or more, based on the total curing agent. When the content of the phenolic resin-based curing agent is equal to or more than the above lower limit, it is possible to exhibit good fluidity while maintaining curability at low temperatures. In addition, the upper limit of the content of the phenolic resin-based curing agent is not particularly limited, but it is preferable that it is 100% by mass or less based on the total curing agent.

The lower limit of the total content of the curing agent in the molding resin composition of this embodiment is not particularly limited, but is preferably 0.8% by mass or more, more preferably 1% by mass or more, even more preferably 1.5% by mass or more, even more preferably 2% by mass or more, even more preferably 3% by mass or more, and even more preferably 4% by mass or more, when the total solid content of the molding resin composition is 100% by mass. When the total content of the curing agent is equal to or more than the above lower limit, good curing properties can be obtained. In addition, the upper limit of the total content of the curing agent in the molding resin composition is not particularly limited, but is preferably 12% by mass or less, more preferably 10% by mass or less, and even more preferably 8% by mass or less, relative to the entire molding resin composition.

It is preferable to mix the phenolic resin as a curing agent and the epoxy resin so that the equivalent ratio (EP)/(OH) between the number of epoxy groups (EP) in the molding resin composition and the number of phenolic hydroxyl groups (OH) in the total phenolic resin is 0.8 or more and 1.6 or less. If the equivalent ratio is within the above range, sufficient curing characteristics can be obtained when molding the resulting molding resin composition. However, when using a resin other than the phenolic resin that can react with the epoxy resin, the equivalent ratio can be adjusted appropriately.

[Curing catalyst]
When the molding resin composition of the present embodiment contains a curing catalyst as an essential component, it is preferable to use an imidazole-based compound as the curing catalyst used in the molding resin composition of the present embodiment. The imidazole-based compound is, for example, an imidazoline compound such as imidazole, 2-methylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 1,2-dimethylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 1-benzyl-2-phenylimidazole, 1-benzyl-2-methylimidazole, 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, 1-cyanoethyl-2-undecylimidazole, 1-cyanoethyl-2-phenylimidazole, 2-phenyl-4,5-dihydroxymethylimidazole, and 2-phenyl-4-methyl-5-hydroxymethylimidazole. The compound may include one or more selected from the group consisting of an isocyanuric acid adduct of 2,4-diamino-6-[2'-methylimidazolyl(1')]-ethyl-s-triazine, an isocyanuric acid adduct of 2,4-diamino-6-[2'-ethyl-4-methylimidazolyl(1')]-ethyl-s-triazine, an isocyanuric acid adduct of 2-phenylimidazole, and an isocyanuric acid adduct of 2-methylimidazole.

When an imidazole-based compound is used as a curing catalyst, the content of the imidazole-based compound is preferably 0.01% by mass or more, more preferably 0.03% by mass or more, even more preferably 0.05% by mass or more, even more preferably 0.1% by mass or more, even more preferably 0.3% by mass or more, even more preferably 0.5% by mass or more, and even more preferably 1.0% by mass or more, when the entire solid content of the molding resin composition is taken as 100% by mass. By making the content of the imidazole-based compound equal to or more than the above lower limit, it is possible to improve the adhesion and waterproofing when sealing a structure such as an electronic component or a stator. It is also possible to improve the curing property at low temperatures during sealing molding. On the other hand, the content of the imidazole-based compound is preferably 2.0% by mass or less, more preferably 1.5% by mass or less, when the entire solid content of the molding resin composition is taken as 100% by mass. By making the content of the imidazole-based compound equal to or less than the above upper limit, it is possible to improve the fluidity during transfer molding and contribute to improving the filling property.

In addition to the imidazole-based compounds, the curing catalyst may further include one or more selected from phosphorus atom-containing compounds such as organic phosphines, tetra-substituted phosphonium compounds, phosphobetaine compounds, adducts of phosphine compounds and quinone compounds, and adducts of phosphonium compounds and silane compounds; and amine-based curing catalysts other than imidazole-based compounds, such as 1,8-diazabicyclo(5,4,0)undecene.

Examples of organic phosphines include primary phosphines such as ethylphosphine and phenylphosphine; secondary phosphines such as dimethylphosphine and diphenylphosphine; and tertiary phosphines such as trimethylphosphine, triethylphosphine, tributylphosphine, and triphenylphosphine.

Examples of tetra-substituted phosphonium compounds include compounds represented by the following general formula (4):

In the above general formula (4), P represents a phosphorus atom. R ⁴ , R ⁵ , R ⁶ and R ⁷ represent an aromatic group or an alkyl group. A represents an anion of an aromatic organic acid having at least one functional group selected from a hydroxyl group, a carboxyl group and a thiol group on an aromatic ring. AH represents an aromatic organic acid having at least one functional group selected from a hydroxyl group, a carboxyl group and a thiol group on an aromatic ring. x and y are numbers from 1 to 3, z is a number from 0 to 3, and x=y.

The compound represented by the general formula (4) can be obtained, for example, as follows, but is not limited thereto. First, a tetra-substituted phosphonium halide, an aromatic organic acid, and a base are mixed uniformly in an organic solvent, and an aromatic organic acid anion is generated in the solution system. Then, water is added to precipitate the compound represented by the general formula (4). In the compound represented by the general formula (4), R ⁴ , R ⁵ , R ⁶ and R ⁷ bonded to the phosphorus atom are phenyl groups, and AH is a compound having a hydroxyl group on the aromatic ring, i.e., a phenol, and A is preferably an anion of the phenol. Examples of the phenol include monocyclic phenols such as phenol, cresol, resorcin, and catechol, condensed polycyclic phenols such as naphthol, dihydroxynaphthalene, and anthraquinol, bisphenols such as bisphenol A, bisphenol F, and bisphenol S, and polycyclic phenols such as phenylphenol and biphenol.

Examples of phosphobetaine compounds used as curing catalysts include compounds represented by the following general formula (5):

In the above general formula (5), P represents a phosphorus atom. ^R8 represents an alkyl group having 1 to 3 carbon atoms, ^R9 represents a hydroxyl group, f is a number from 0 to 5, and g is a number from 0 to 3.

The compound represented by the general formula (5) can be obtained, for example, as follows. First, a triaromatic substituted phosphine, which is a tertiary phosphine, is contacted with a diazonium salt, and the triaromatic substituted phosphine is substituted for the diazonium group of the diazonium salt. However, the method is not limited to this.

Examples of adducts of phosphine compounds and quinone compounds used as curing catalysts include compounds represented by the following general formula (6):

In the above general formula (6), P represents a phosphorus atom. R ¹⁰ , R ¹¹ and R ¹² represent an alkyl group having 1 to 12 carbon atoms or an aryl group having 6 to 12 carbon atoms and may be the same or different. R ¹³ , R ¹⁴ and R ¹⁵ represent a hydrogen atom or a hydrocarbon group having 1 to 12 carbon atoms and may be the same or different, and R ¹⁴ and R ¹⁵ may be bonded to form a cyclic structure.

Phosphine compounds used in the adduct of a phosphine compound and a quinone compound are preferably those which are unsubstituted or have a substituent such as an alkyl group or an alkoxy group on the aromatic ring, such as triphenylphosphine, tris(alkylphenyl)phosphine, tris(alkoxyphenyl)phosphine, trinaphthylphosphine, or tris(benzyl)phosphine, and examples of the substituent such as an alkyl group or an alkoxy group include those having 1 to 6 carbon atoms. Triphenylphosphine is preferred from the viewpoint of ease of availability.

In addition, examples of quinone compounds used in the adduct of a phosphine compound and a quinone compound include benzoquinone and anthraquinones, of which p-benzoquinone is preferred from the standpoint of storage stability.

The adduct of a phosphine compound and a quinone compound can be produced by contacting and mixing the organic tertiary phosphine and the benzoquinone in a solvent in which both can dissolve. The solvent should preferably be a ketone such as acetone or methyl ethyl ketone, which has low solubility in the adduct. However, the solvent is not limited to this.

In the compound represented by general formula (6), a compound in which R ¹⁰ , R ¹¹ and R ¹² bonded to the phosphorus atom are phenyl groups, and R ¹³ , R ¹⁴ and R ¹⁵ are hydrogen atoms, i.e., an addition compound of 1,4-benzoquinone and triphenylphosphine, is preferred in terms of reducing the hot elastic modulus of the cured product of the molding resin composition.

Examples of adducts of phosphonium compounds and silane compounds used as curing catalysts include compounds represented by the following general formula (7):

In the above general formula (7), P represents a phosphorus atom, and Si represents a silicon atom. R ¹⁶ , R ¹⁷ , R ¹⁸ and R ¹⁹ each represent an organic group having an aromatic ring or a heterocyclic ring, or an aliphatic group, and may be the same or different from each other. In the formula, R ²⁰ is an organic group bonded to groups Y ² and Y ^3. In the formula, R ²¹ is an organic group bonded to groups Y ⁴ and Y ^5. Y ² and Y ³ represent groups formed by releasing a proton from a proton-donating group, and groups Y ² and Y ³ in the same molecule are bonded to a silicon atom to form a chelate structure. Y ⁴ and Y ⁵ represent groups formed by releasing a proton from a proton-donating group, and groups Y ⁴ and Y ⁵ in the same molecule are bonded to a silicon atom to form a chelate structure. R ²⁰ and R ²¹ may be the same or different, and Y ² , Y ³ , Y ⁴ and Y ⁵ may be the same or different. Z ¹ is an organic group having an aromatic ring or a heterocyclic ring, or an aliphatic group.

In general formula (7), examples of R ¹⁶ , R ¹⁷ , R ¹⁸ and R ¹⁹ include a phenyl group, a methylphenyl group, a methoxyphenyl group, a hydroxyphenyl group, a naphthyl group, a hydroxynaphthyl group, a benzyl group, a methyl group, an ethyl group, an n-butyl group, an n-octyl group and a cyclohexyl group. Among these, an aromatic group having a substituent such as an alkyl group, an alkoxy group or a hydroxyl group, such as a phenyl group, a methylphenyl group, a methoxyphenyl group, a hydroxyphenyl group or a hydroxynaphthyl group, or an unsubstituted aromatic group is more preferable.

In addition, in the general formula (7), R ²⁰ is an organic group bonded to Y ² and Y ^3. Similarly, R ²¹ is an organic group bonded to groups Y ⁴ and Y ^5. Y ² and Y ³ are groups formed by a proton-donating group releasing a proton, and groups Y ² and Y ³ in the same molecule are bonded to a silicon atom to form a chelate structure. Similarly, Y ⁴ and Y ⁵ are groups formed by a proton-donating group releasing a proton, and groups Y ⁴ and Y ⁵ in the same molecule are bonded to a silicon atom to form a chelate structure. Groups R ²⁰ and R ²¹ may be the same or different from each other, and groups Y ² , Y ³ , Y ⁴ , and Y ⁵ may be the same or different from each other. In such general formula (7), -Y ² -R ²⁰ -Y ³ - and -Y ⁴ -R ²¹ -Y ⁵ The group represented by - is constituted by a group formed by releasing two protons from a proton donor, and as the proton donor, an organic acid having at least two carboxyl groups or hydroxyl groups in the molecule is preferable, an aromatic compound having at least two carboxyl groups or hydroxyl groups on adjacent carbons constituting an aromatic ring is more preferable, and an aromatic compound having at least two hydroxyl groups on adjacent carbons constituting an aromatic ring is more preferable. Examples of the proton donor include catechol, pyrogallol, 1,2-dihydroxynaphthalene, 2,3-dihydroxynaphthalene, 2,2'-biphenol, 1,1'-bi-2-naphthol, salicylic acid, 1-hydroxy-2-naphthoic acid, 3-hydroxy-2-naphthoic acid, chloranilic acid, tannic acid, 2-hydroxybenzyl alcohol, 1,2-cyclohexanediol, 1,2-propanediol, and glycerin, and among these, catechol, 1,2-dihydroxynaphthalene, and 2,3-dihydroxynaphthalene are more preferable.

^Z1 in the general formula (7) represents an organic group or an aliphatic group having an aromatic ring or a heterocyclic ring. Specific examples of such groups include aliphatic hydrocarbon groups such as methyl, ethyl, propyl, butyl, hexyl, and octyl groups; aromatic hydrocarbon groups such as phenyl, benzyl, naphthyl, and biphenyl groups; glycidyloxy groups such as glycidyloxypropyl, mercaptopropyl, and aminopropyl groups; mercapto groups; and reactive substituents such as alkyl groups and vinyl groups having amino groups. Among these, the methyl, ethyl, phenyl, naphthyl, and biphenyl groups are more preferable in terms of thermal stability.

In a method for producing an adduct of a phosphonium compound and a silane compound, a silane compound such as phenyltrimethoxysilane and a proton donor such as 2,3-dihydroxynaphthalene are added and dissolved in a flask containing methanol, and then a sodium methoxide-methanol solution is added dropwise at room temperature with stirring. A previously prepared solution of a tetra-substituted phosphonium halide such as tetraphenylphosphonium bromide dissolved in methanol is then added dropwise at room temperature with stirring, causing crystals to precipitate. The precipitated crystals are filtered, washed with water, and vacuum dried to obtain an adduct of a phosphonium compound and a silane compound. However, the method is not limited to this.

The content of the curing catalyst in the molding resin composition of this embodiment is preferably 0.1% by mass or more, more preferably 0.3% by mass or more, even more preferably 0.5% by mass or more, and even more preferably 1.0% by mass or more, when the entire solid content of the molding resin composition is 100% by mass. By making the content of the curing catalyst equal to or more than the above lower limit, the curing property of the molding resin composition during transfer molding can be effectively improved and the curing property at low temperatures can be improved. On the other hand, the content of the curing catalyst is preferably 2.0% by mass or less, more preferably 1.7% by mass or less, and even more preferably 1.5% by mass or less, when the entire solid content of the molding resin composition is 100% by mass. By making the content of the curing catalyst equal to or less than the above upper limit, the fluidity during sealing can be improved and the filling property can be improved.

[Inorganic filler]
Examples of inorganic fillers used in the molding resin composition of this embodiment include fused silica such as fused crushed silica and fused spherical silica, crystalline 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, wood, and pulverized powder obtained by pulverizing a cured product of a phenolic resin molding material or an epoxy resin molding material. Among these, silica such as fused crushed silica, fused spherical silica, and crystalline silica is preferred, and fused spherical silica is more preferred. Among these, calcium carbonate and wollastonite are preferred in terms of cost. The inorganic fillers may be used alone or in combination of two or more.

The average particle diameter _D50 of the inorganic filler is preferably 0.01 μm or more and 75 μm or less, more preferably 0.05 μm or more and 50 μm or less. By setting the average particle diameter _D50 of the inorganic filler within the above range, the filling property in the mold during molding is improved. Furthermore, by setting the upper limit of the average particle diameter _D50 of the inorganic filler to 75 μm or less, the filling property is further improved. The average particle diameter _D50 was determined as the volume-converted average particle diameter measured by a laser diffraction type measuring device RODOS SR type (SYMPATEC HEROS & RODOS).

The molding resin composition of the present embodiment may contain, as an inorganic filler, two or more kinds of spherical silica having different average particle sizes D _50. This can improve the flowability and filling property during transfer molding.

The content of the inorganic filler in the molding resin composition of this embodiment is preferably 50% by mass or more, more preferably 60% by mass or more, even more preferably 65% by mass or more, even more preferably 70% by mass or more, and even more preferably 75% by mass or more, when the entire solid content of the molding resin composition is 100% by mass. When the content of the inorganic filler is equal to or more than the above lower limit, the increase in moisture absorption amount and the decrease in strength due to the hardening of the obtained molding resin composition can be reduced. In addition, the content of the inorganic filler is preferably 93% by mass or less, more preferably 91% by mass or less, and even more preferably 90% by mass or less, when the entire solid content of the molding resin composition is 100% by mass. When the content of the inorganic filler is equal to or less than the above upper limit, the obtained molding resin composition has good fluidity and good moldability. Therefore, the manufacturing stability of the sealing structure is improved, and a structure with an excellent balance between yield and durability is obtained.

When silica such as fused crushed silica, fused spherical silica, or crystalline silica is used as the inorganic filler, the content of silica is preferably 40% by mass or more, more preferably 60% by mass or more, and even more preferably 75% by mass or more, based on 100% by mass of the entire inorganic filler in the molding resin composition. When the content of silica is equal to or more than the lower limit, the balance between the curability and fluidity of the molding resin composition during transfer molding is good.
The upper limit of the silica content is not particularly limited, but is, for example, 100% by mass or less when the total amount of the inorganic filler in the molding resin composition is taken as 100% by mass.

In addition, when inorganic fillers are used in combination with metal hydroxides such as aluminum hydroxide and magnesium hydroxide, as described below, or inorganic flame retardants such as zinc borate, zinc molybdate, and antimony trioxide, it is desirable that the total amount of these inorganic flame retardants and the above-mentioned inorganic fillers be within the range of the content of the above-mentioned inorganic fillers.

[Other ingredients]
In addition to the above components, the molding resin composition of the present embodiment may further contain other components, such as an adhesion aid, wax, coupling agent, colorant, flame retardant, mold release agent, and stress reducing agent, as necessary.

(Adhesion aid)
The molding resin composition of the present embodiment preferably contains an adhesion aid in order to improve curability at low temperatures. The adhesion aid used in the molding resin composition of the present embodiment is not particularly limited, and examples thereof include triazole compounds, and examples of the triazole compounds include compounds having a 1,2,4-triazole ring and compounds having a 1,2,3-triazole ring. Specific examples of the compound 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, and one or more of these compounds may be used in combination. Of these compounds, compounds having at least one mercapto group are preferred.

The lower limit of the content of the adhesion assistant in the molding resin composition of the present embodiment is, for example, preferably 0.01% by mass or more, more preferably 0.05% by mass or more, and even more preferably 0.07% by mass or more, when the total solid content of the molding resin composition is taken as 100% by mass. This can further improve the curability at low temperatures.
The upper limit of the content of the adhesion assistant is, for example, preferably 10% by mass or less, more preferably 5% by mass or less, even more preferably 1% by mass or less, even more preferably 0.5% by mass or less, and even more preferably 0.3% by mass or less, when the total solid content of the molding resin composition is taken as 100% by mass. This makes it possible to improve adhesion and waterproofing when a structure such as an electronic component or a stator is sealed with the molding resin composition of this embodiment.

(wax)
The molding resin composition of the present embodiment preferably contains a wax having a melting point of 30° C. to 90° C. By containing such a wax, the molding resin composition has good melting properties at the temperature applied in transfer molding, and therefore the fluidity during sealing and the filling property can be improved. Examples of such wax include natural waxes such as carnauba wax, synthetic waxes such as montan acid ester wax and oxidized polyethylene wax, and higher fatty acids and metal salts thereof such as zinc stearate.

The amount of wax blended is, for example, 0.05% by mass or more and 2.0% by mass or less, when the total solid content of the molding resin composition is 100% by mass. The lower limit of the amount of wax blended is preferably 0.1% by mass or more, more preferably 0.2% by mass or more, when the total solid content of the molding resin composition is 100% by mass. The upper limit of the amount of wax blended is preferably 1.5% by mass or less, more preferably 1.0% by mass or less, when the total solid content of the molding resin composition is 100% by mass. By blending the wax in the above range, the obtained molding resin composition has excellent fluidity and filling properties during transfer molding.

(Coupling Agent)
The molding resin composition of the present embodiment may contain a coupling agent such as a silane coupling agent in order to improve adhesion between the epoxy resin and the inorganic filler. Examples of the coupling agent include epoxysilane, aminosilane, ureidosilane, and mercaptosilane.

Examples of epoxy silanes include γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldimethoxysilane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, etc. Examples of aminosilanes 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, and N-(3-(trimethoxysilylpropyl)-1,3-benzenedimethanane. Examples of ureidosilanes include γ-ureidopropyltriethoxysilane and hexamethyldisilazane. Primary aminosilanes include A latent aminosilane coupling agent in which an amino site is protected by reacting with a ketone or aldehyde may be used. The aminosilane may have a secondary amino group. Examples of mercaptosilane include γ-mercaptopropyltrimethoxysilane, 3-mercaptopropylmethyldimethoxysilane, and silane coupling agents that exhibit the same function as a mercaptosilane coupling agent by thermal decomposition, such as bis(3-triethoxysilylpropyl)tetrasulfide and bis(3-triethoxysilylpropyl)disulfide. These silane coupling agents may be blended after being hydrolyzed in advance. These silane coupling agents may be used alone or in combination of two or more.

From the viewpoint of continuous moldability, mercaptosilane is preferred, from the viewpoint of fluidity, aminosilane is preferred, and from the viewpoint of adhesion, epoxysilane is preferred.

The lower limit of the content of the coupling agent such as the silane coupling agent in the molding resin composition of this embodiment is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, even more preferably 0.1% by mass or more, and even more preferably 0.2% by mass or more, when the entire solid content of the molding resin composition is taken as 100% by mass. If the content of the coupling agent such as the silane coupling agent is equal to or more than the above lower limit, the interfacial strength between the epoxy resin and the inorganic filler is not reduced, and the adhesion and waterproofing when sealing a structure such as an electronic component or a stator can be improved. In addition, the upper limit of the content of the coupling agent such as the silane coupling agent is preferably 1% by mass or less, more preferably 0.8% by mass or less, even more preferably 0.6% by mass or less, and even more preferably 0.4% by mass or less, when the entire solid content of the molding resin composition is taken as 100% by mass. If the content of the coupling agent such as the silane coupling agent is equal to or less than the above upper limit, the interfacial strength between the epoxy resin and the inorganic filler is not reduced, and the adhesion and waterproofing when sealing a structure such as an electronic component or a stator can be improved. In addition, when the content of the coupling agent such as the silane coupling agent is equal to or less than the above upper limit, the water absorption of the cured product of the molding resin composition is prevented from increasing.

[Characteristic]
The molding resin composition of this embodiment has a glass transition temperature (Tg) of preferably at least 140° C., more preferably at least 150° C., even more preferably at least 155° C., even more preferably at least 160° C., and even more preferably at least 165° C., as measured by the following (Method 1). By having a glass transition temperature (Tg) of at least the above-mentioned lower limit, the molding resin composition of this embodiment can be cured even at low temperatures, and the heat resistance of the cured product of the molding resin composition of this embodiment is improved.
The upper limit of the glass transition temperature (Tg) is not particularly limited, but is, for example, 300° C. or less, 250° C. or less, or 220° C. or less.

(Method 1)
The molding resin composition is molded into a test piece of 80 mm x 10 mm x 4 mm using a transfer molding machine at a mold temperature of 175 ° C, injection pressure of 6.9 MPa, and curing time of 90 seconds, and then post-cured at 175 ° C for 2 hours. Furthermore, the thermal expansion coefficient of the obtained test piece is measured at a heating rate of 5 ° C / min using a thermomechanical analyzer. Next, based on the obtained measurement results, the glass transition temperature (Tg) ( ° C) of the cured product is calculated from the inflection point of the thermal expansion coefficient.

The cured product for measuring the glass transition temperature can be obtained, for example, by curing the resin composition at 175° C. for two hours.
Specifically, the glass transition temperature Tg can be calculated from the measurement results obtained by, for example, using a low-pressure transfer molding machine to inject and mold a resin composition at a mold temperature of 175 ° C., an injection pressure of 6.9 MPa, and a curing time of 90 seconds, post-curing the resulting test piece at 175 ° C. for 2 hours, and then measuring the test piece using a thermomechanical analyzer under conditions of a measurement temperature range of 0 ° C. to 320 ° C. and a temperature rise rate of 5 ° C./min. Examples of low-pressure transfer molding machines that can be used include KTS-15 and KTS-30 (manufactured by Kotaki Seiki Co., Ltd.). Examples of thermomechanical analyzers that can be used include TMA/SS6000 (manufactured by Seiko Instruments Inc.) and TMA7100 (manufactured by Hitachi High-Tech Science Corporation).

The molding resin composition of this embodiment preferably satisfies S2 ≧ 0.8 × S1, where _S1 is a spiral flow measured at a mold temperature of 175°C, an injection pressure of 9.8 MPa, and a curing time of 3 minutes, and S2 is a spiral flow measured at a mold temperature of 175°C, an injection pressure of 9.8 _MPa , and a curing time of 3 minutes after leaving the molding resin composition at 25° _C for ₄₈ hours. In this way, the composition can be cured at a low temperature, and the adhesion and waterproofing when sealing a structure such as an electronic component or a stator can be improved, as well as long-term storage stability can be improved.

The molding resin composition of this embodiment has an upper limit of the time for the torque value to reach 2 N m, as measured by the following (Method 2), which is preferably less than 100 seconds, more preferably less than 70 seconds, even more preferably less than 50 seconds, and even more preferably less than 30 seconds. When the time for the torque value to reach 2 N m is less than the upper limit, the molding resin composition of this embodiment can be molded even at low temperatures.
Furthermore, the lower limit of the time required for the torque value to reach 2 N·m is not particularly limited, but may be, for example, 0.1 seconds or more and 1 second or more.

(Method 2)
Using a Curastometer (registered trademark), the torque value of the molding resin composition is measured over time at a mold temperature of 140° C. and an amplitude angle of ±0.25°. Based on the measurement results, the time (seconds) from the start of measurement until the torque value reaches 2 N·m is calculated.

As a Curastometer (registered trademark), for example, Curastometer (registered trademark) MODEL 7 (manufactured by A&D Co., Ltd.) can be used.

The molding resin composition of the present embodiment has a spiral flow of preferably 70 cm or more, more preferably 80 cm or more, and even more preferably 90 cm or more, as measured by the following (Method 3). By having a spiral flow of at least the above lower limit, it is possible to further improve the adhesion and waterproofing when sealing a structure such as an electronic component or a stator.
The spiral flow is preferably 180 cm or less, more preferably 160 cm or less, and even more preferably 140 cm or less. By having the spiral flow be equal to or less than the upper limit, the long-term storage stability of the molding resin composition of the present embodiment can be improved.

(Method 3)
The molding resin composition is injected into a spiral flow measurement mold in accordance with ANSI/ASTM D 3123-72 using a low-pressure transfer molding machine under conditions of 175°C, injection pressure of 6.9 MPa, and pressure retention time of 3 minutes, and the flow length is measured, which is defined as the spiral flow (cm).

Examples of low-pressure transfer molding machines that can be used include the above-mentioned KTS-15 and KTS-30 (manufactured by Kotaki Seiki Co., Ltd.).

The molding resin composition of this embodiment has a gel time, measured by the following (Method 4), of preferably 30 seconds or more, more preferably 40 seconds or more, and even more preferably 50 seconds or more. By having a gel time of at least the above lower limit, the long-term storage stability of the molding resin composition of this embodiment can be improved.
The gel time is preferably 80 seconds or less, more preferably 70 seconds or less, and even more preferably 60 seconds or less. By making the gel time equal to or less than the upper limit, the adhesion and waterproofing when sealing a structure such as an electronic component or a stator can be further improved.

(Method 4)
The molding resin composition is injected into a spiral flow measurement mold conforming to ANSI/ASTM D 3123-72 using a low-pressure transfer molding machine under conditions of 175° C., injection pressure of 6.9 MPa, and pressure retention time of 3 minutes. The time from the start of injection until the molding resin composition hardens and no longer flows is measured and taken as the gel time (seconds).

Examples of low-pressure transfer molding machines that can be used include the above-mentioned KTS-15 and KTS-30 (manufactured by Kotaki Seiki Co., Ltd.).

The molding resin composition of this embodiment has a linear expansion coefficient α1, as measured by the following (Method 5), whose lower limit is not particularly limited, and is, for example, 0.8 ppm/°C or more, 1.0 ppm/°C or more, or 1.2 ppm/°C or more.
Moreover, the linear expansion coefficient α1 is preferably 10.0 ppm/° C. or less, more preferably 5.0 ppm/° C. or less, even more preferably 3.0 ppm/° C. or less, and even more preferably 2.0 ppm/° C. or less. By having the linear expansion coefficient α1 be equal to or less than the above upper limit, it is possible to further improve the adhesion and waterproofing when sealing a structure such as an electronic component or a stator.

(Method 5)
The molding resin composition is injected and molded using a low-pressure transfer molding machine under conditions of a mold temperature of 175°C, an injection pressure of 9.8 MPa, and a curing time of 3 minutes to obtain a molded product of 15 mm x 4 mm x 4 mm. The molded product obtained is then post-cured at 175°C for 4 hours to prepare a test piece. The average linear expansion coefficient α1 (ppm/°C) of the obtained test piece at 25-70°C is measured using a thermomechanical analyzer under conditions of a measurement temperature range of 0°C to 400°C and a heating rate of 5°C/min.

As a low-pressure transfer molding machine, for example, the above-mentioned KTS-15 and KTS-30 (manufactured by Kotaki Seiki Co., Ltd.) can be used. Furthermore, as a thermomechanical analyzer, for example, the above-mentioned TMA/SS6000 (manufactured by Seiko Instruments Inc.) or TMA7100 (manufactured by Hitachi High-Tech Science Corporation) can be used.

The molding resin composition of this embodiment has a thermal conductivity, measured by the following (Method 6), of preferably 0.5 W/m K or more, more preferably 0.6 W/m K or more, even more preferably 0.7 W/m K or more, and still more preferably 0.8 W/m K or more. When the thermal conductivity is equal to or more than the above lower limit, heat associated with electronic components inside an article molded using the molding resin composition of this embodiment can be efficiently released.
The thermal conductivity is preferably 3.5 W/m K or less, more preferably 3.3 W/m K or less, even more preferably 3.1 W/m K or less, even more preferably 2.9 W/m K or less, and even more preferably 2.8 W/m K or less. When the thermal conductivity is equal to or less than the upper limit, the influence of external heat on electronic components inside a molded article using the molding resin composition of this embodiment can be suppressed.

(Method 6)
The molding resin composition is injected and molded using a transfer molding machine under the conditions of a mold temperature of 175°C, an injection pressure of 6.9 MPa, and a curing time of 90 seconds to obtain a molded body of 80 mm x 10 mm x 4 mm. The molded body obtained is then post-cured at 175°C for 2 hours to obtain a test piece. The thermal diffusivity of the obtained test piece is measured using a laser flash method. In addition, the specific gravity of the test piece used for the thermal conductivity measurement is measured using an electronic specific gravity meter. Furthermore, the specific heat of the test piece used for the thermal conductivity and specific gravity measurement is measured using a differential scanning calorimeter. The thermal conductivity (W/m·K) in the thickness direction of the test piece is calculated from the measured values of the thermal diffusivity, specific gravity, and specific heat.

As a transfer molding machine, for example, the above-mentioned KTS-15 and KTS-30 (manufactured by Kotaki Seiki Co., Ltd.) can be used. Furthermore, for measuring thermal diffusivity by the laser flash method, for example, a xenon flash analyzer LFA447 (manufactured by NETZSCH) can be used. Furthermore, as an electronic specific gravity meter, for example, an SD-200L (manufactured by Alpha Mirage Co., Ltd.) can be used. Furthermore, as a differential scanning calorimeter, for example, a DSC8230 (manufactured by Rigaku Corporation) can be used.

[Application]
The molding resin composition of the present embodiment is used to collectively seal a substrate on which electronic components are mounted, a stator core having a plurality of slots formed in the circumferential direction and fixed on the substrate, and a plurality of coils housed in the slots. A stator including the molding resin composition of the present embodiment as a sealant is applied to, for example, an electric motor (motor) as a rotating electric machine (electric motor, generator, or dual-purpose motor/generator).

<Sealing structure>
Hereinafter, a sealing structure 200 using the molding resin composition of this embodiment will be described with reference to the drawings.
Fig. 1 shows a top view of the sealed body 100 and the sealing structure 200 before and after molding. Similarly, Fig. 2 shows a side view of the sealed body 100 and the sealing structure 200 before and after molding. Here, (a) and (c) show the sealed body 100 before molding, and (b) and (d) show the sealing structure 200 after molding.

The sealing structure 200 in this embodiment comprises a substrate 10 on which an electronic component 11 is mounted, a stator core 20 fixed to one surface of the substrate 10 and having a plurality of slots 21 formed in the circumferential direction, a sealed object 100 including a plurality of coils 30 housed in the slots 21, and a sealing member 50 provided to cover a part or all of the sealed object 100, the sealing member 50 being composed of a cured product of the molding resin composition of this embodiment.

In the sealing structure 200 of this embodiment, the sealed object 100 to be sealed with the molding resin composition of this embodiment includes a substrate 10 on which an electronic component 11 is mounted, a stator core 20 fixed to one surface of the substrate 10 and having a plurality of slots 21 formed in the circumferential direction, and a plurality of coils 30 housed in the slots 21.

As shown in Fig. 1, the substrate 10 is a substrate on which electronic components 11 are mounted on one or both of one surface and the other surface opposite to the one surface. As shown in Fig. 1, the substrate 10 has, for example, a flat plate shape.

The substrate 10 may have a solder resist layer on one surface on which the electronic component 11 is mounted. The solder resist layer can be formed using a resin composition for forming a solder resist that is commonly used in the field of semiconductor devices. In this embodiment, for example, the solder resist layer can be provided on one surface and the other surface of the substrate 10.
The solder resist layer provided on one surface or on both surfaces of the substrate 10 is formed from a resin composition containing a silicone compound, for example, which makes it possible to realize a solder resist layer with excellent surface smoothness.

1A, the electronic components 11 are mounted on, for example, one surface and the other surface of the substrate 10. On the other hand, the electronic components 11 may be provided only on one surface of the substrate 10 and may not be provided on the other surface of the substrate 10.
Examples of electronic components 11 include light-emitting elements such as LED chips, biometers that detect bioelectric potentials such as electroencephalograms and myoelectric potentials, and biological activities such as blood pressure and pulse rate, general measuring instruments that detect environmental information such as pressure, temperature, position, humidity, light, sound, and acceleration, portable power sources such as capacitors, acoustic modules, communication modules, and other elements, as well as wiring that connects the above elements.

Here, it is preferable that a lead wire 40 is connected to the substrate 10 and the electronic component 11. By connecting the lead wire 40 to the substrate 10 and the electronic component 11 before sealing with the molding resin composition of this embodiment, the connection parts between the lead wire 40 and the substrate 10 and the electronic component 11 can be sealed together with the sealing member 50 described later, and as a result, the waterproofness of the sealing structure 200 of this embodiment can be improved.

The stator core 20 has a plurality of slots 21 formed in the circumferential direction when viewed from the axial end as shown in Fig. 1(a). Here, as shown in Fig. 1(a), four slots 21 are provided. The stator core 20 is fixed onto one surface of the substrate 10 on which the electronic components 11 are mounted as shown in Fig. 2(c).
Stator core 20 may be provided by stacking a plurality of electromagnetic steel plates in the axial direction and closely fixing them together, or may be provided by molding a resin composition.

The coil 30 is, for example, a rectangular wire U-shaped and is wound so as to be accommodated in two spaced apart slots 21. The coil 30 has a first coil end and a second coil end. The first coil end protrudes to one axial side of the stator core 20. The second coil end protrudes to the other axial side of the stator core 20. In other words, the coil 30 has a pair of coil ends that protrude to both axial sides of the stator core 20.

1(b) and 2(d), the sealing member 50 collectively seals the substrate 10 on which the above-mentioned electronic components 11 are mounted, the stator core 20 fixed to one surface of the substrate 10 and having a plurality of slots 21 formed in the circumferential direction, and the plurality of coils 30 housed in the slots 21. In other words, the sealing member 50 is provided to cover a part or the whole of the sealed body 100 including the substrate 10 on which the electronic components 11 are mounted, the stator core 20 fixed to one surface of the substrate 10 and having a plurality of slots 21 formed in the circumferential direction, and the plurality of coils 30 housed in the slots 21.
As the material for the sealing member 50, the above-mentioned molding resin composition is used.

At this time, as shown in Figures 1(b) and 2(d), it is preferable that the connection portions between the lead wires 40 and the substrate 10 and the electronic components 11 are collectively sealed with the sealing member 50. In this way, the waterproofness of the sealing structure 200 of this embodiment can be improved.

<Method of manufacturing sealing structure>
Hereinafter, a method for producing a sealing structure using the molding resin composition of this embodiment will be described.
The method for manufacturing the sealing structure of the present embodiment includes the steps of arranging, in a molding die in a transfer molding machine, a substrate on which electronic components are mounted, a stator core having a plurality of slots formed in the circumferential direction and fixed onto the substrate, and a plurality of coils housed in the slots, and obtaining a sealing structure by encapsulating the substrate, the stator core, and the coils in the molding die with the molding resin composition of the present embodiment by a transfer molding method using the transfer molding machine.

The step of obtaining the sealed structure is carried out, for example, at a temperature of 80° C. or more and less than 180° C. and a pressure of 1 MPa or more and 15 MPa or less. Preferably, the step is carried out at a temperature of 120° C. or more and 170° C. or less and a pressure of 3 MPa or more and 12 MPa or less. This makes it possible to obtain a sealed structure having excellent adhesion and waterproof properties.
In this case, the step of obtaining the sealed structure is preferably performed by sealing and molding at a temperature equal to or lower than the Tg of the cured product of the molding resin composition.

The step of obtaining the sealing structure includes:
(A) a molding process by a technique such as transfer molding or compression molding;
(B) After the molding step, a post-curing step of heating the molded body may be included.

In a typical sealing process, after the above step (A), the above step (B) is carried out in order to promote curing of the epoxy resin and obtain a good crosslinked structure.
In contrast, a preferred aspect of this embodiment is to perform only the molding step (A) without performing the post-curing step (B), which not only improves productivity but also suppresses thermal damage caused by the post-curing, i.e., thermal damage to the stator core, coil, and substrate, which are the objects to be sealed, and a good sealing structure can be obtained.
In this embodiment, the molding resin composition is configured so that the cured product cured at 140°C for 2 minutes has a flexural modulus at 25°C (in accordance with JIS K6911:2006) of 0.1 GPa or more and 30 GPa or less, so that a good crosslinked structure can be obtained even if (B) is omitted.

In this embodiment, the molding temperature in (A) is preferably a temperature not higher than the Tg (° C.) of the cured product obtained from the molding resin composition, more preferably not higher than (Tg-10° C.), and most preferably not higher than (Tg-30° C.). The molding temperature is preferably not higher than 160° C., more preferably not higher than 140° C., and most preferably not higher than 130° C.
By molding at such a low temperature, thermal damage to the objects to be sealed, that is, the stator core, the coils and the substrate, can be suppressed, and a good sealing structure can be obtained.
The lower limit of the molding temperature is not particularly limited as long as the molding resin composition can be sufficiently cured. For example, it can be (Tg-80°C) or higher, and can be 90°C or higher.

When performing the post-curing of (B) above, the post-curing temperature is preferably in the same range as the molding temperature. That is, it is preferable to set the temperature at or below the Tg (°C) of the cured product obtained from the molding resin composition, more preferably at or below (Tg-10°C), and most preferably at or below (Tg-30°C). The molding temperature is preferably 160°C or lower, more preferably at or below 140°C, and most preferably at or below 130°C. By performing post-curing at such a low temperature, thermal damage to the object to be sealed can be suppressed, and a good sealing structure can be obtained. There is no particular limit to the lower limit of the molding temperature, but it can be, for example, at or above (Tg-80°C), and can be at or above 90°C.

In a typical sealing process, the temperatures of (A) and (B) are usually set to temperatures exceeding the Tg (°C) of the cured product obtained from the molding resin composition. In contrast, in this embodiment, the above-mentioned low temperature range is preferred. In this embodiment, the molding resin composition is configured so that the cured product cured at 140°C for 2 minutes has a flexural modulus at 25°C (in accordance with JIS K6911:2006) of 0.1 GPa or more and 30 GPa or less, so that a good crosslinked structure can be obtained even if the temperatures of (A) and (B) are low.

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 also be adopted.

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

(Examples 1 to 4, Comparative Examples 1 and 2)
<Preparation of molding resin composition>
For each of the Examples and Comparative Examples, a molding resin composition was prepared as follows.
First, the components shown in Table 1 were mixed in a mixer. The resulting mixture was then roll-kneaded, cooled, and pulverized to obtain a molding resin composition in the form of powder.

The details of each component in Table 1 are as follows. The formulation shown in Table 1 indicates the content (mass%) of each component relative to the entire resin composition.

(Inorganic filler)
Inorganic filler 1: Fused spherical silica (manufactured by Denka Co., Ltd., product name "FB-950")
Inorganic filler 2: Fused spherical silica (manufactured by Denka Co., Ltd., product name "FB-105")
Inorganic filler 3: Alumina (manufactured by Denka Co., Ltd., product name "DAW-02")

(Coupling Agent)
Coupling agent 1: N-phenyl-3-aminopropyltrimethoxysilane (manufactured by Dow Corning Toray Co., Ltd., product name "CF-4083")

(Epoxy resin)
Epoxy resin 1: Orthocresol novolac type epoxy resin (manufactured by DIC Corporation, product name "EPICRON N-670")

(Hardening agent)
Hardener 1: Biphenylene skeleton-containing phenol aralkyl resin (manufactured by Meiwa Kasei Co., Ltd., product name "MEH-7851SS")
Hardener 2: Trisphenylmethane type phenol novolac resin (manufactured by Meiwa Kasei Co., Ltd., product name "MEH-7500")

(Adhesion aid)
Adhesion aid 1: 3-amino-1,2,4-triazole

(Curing catalyst)
Curing catalyst 1: 2-phenylimidazole Curing catalyst 2: 2-phenyl-4,5-dihydroxymethylimidazole

(Coloring material)
Coloring material 1: Carbon black (manufactured by Mitsubishi Chemical Corporation, product name "Carbon #5")

<Performance evaluation of molding resin composition>
The obtained molding resin composition was evaluated for the following items. The evaluation results are shown in Table 1 below.

(Flexural modulus)
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 140°C, an injection pressure of 9.8 MPa, and a curing time of 2 minutes to obtain a molded product having a length of 80 mm, a width of 10 mm, and a thickness of 4 mm. The obtained molded product was post-cured by heat treatment at 200°C for 4 hours to obtain a test piece, and the flexural modulus (GPa) was measured at an ambient temperature of 25°C in accordance with JIS K 6911:2006.

(Low temperature formability)
Using a Curastometer (registered trademark) (Curastometer (registered trademark) MODEL 7, manufactured by A&D Co., Ltd.), the torque value of the obtained molding resin composition was measured over time at a mold temperature of 140°C and an amplitude angle of ±0.25 degrees. Based on the measurement results, the time (seconds) from the start of measurement until the torque value reached 2 N·m was calculated. From the time (seconds) until the torque value reached 2 N·m, the low-temperature moldability was evaluated according to the following criteria.
A: The time it takes for the torque value to reach 2 Nm is less than 30 seconds (see example here)
B: Time required for torque value to reach 2 N.m is 30 seconds or more and less than 100 seconds. C: Time required for torque value to reach 2 N.m is 100 seconds or more.

(Adhesion and waterproofing)
A resin composition was injected into a 23 mmφ×0.9 mm glass epoxy substrate (a substrate mounted with an IC package and an aluminum electrolytic capacitor) using a low-pressure transfer molding machine (KTS-30, manufactured by Kotaki Seiki Co., Ltd.) under conditions of a mold temperature of 140° C., an injection pressure of 3 to 5 MPa, and a curing time of 2 minutes to a thickness of 2 cm on the substrate, and a substrate sealing body was obtained without post-curing.
Thereafter, the substrate sealing body was immersed in a pure water pool 15 to 100 cm deep for 1000 hours, and then air-dried, after which the continuity of the circuit wiring on the substrate was checked using a tester.
A: No continuity failure B: Continuity failure (short circuit, increased resistance, etc.)

(Spiral Flow Gel Time)
Using a low pressure transfer molding machine (manufactured by Kotaki Seiki Co., Ltd., "KTS-15"), the molding resin compositions of each Example and Comparative Example were injected into a spiral flow measurement mold conforming to ANSI/ASTM D 3123-72 under conditions of 175°C, injection pressure of 6.9 MPa, and pressure retention time of 3 minutes, and the flow length was measured and defined as the spiral flow (cm). In addition, the time from the start of injection until the molding resin composition hardened and no longer flowed was measured and defined as the gel time (seconds).
The spiral flow is a parameter of fluidity, and the larger the value, the better the fluidity.

(Linear expansion coefficient α1)
The linear expansion coefficient of the molding resin composition obtained for each Example and Comparative Example was measured. Using a low pressure transfer molding machine ("KTS-30" manufactured by Kotaki Seiki Co., Ltd.), injection molding was performed under conditions of a mold temperature of 175°C, an injection pressure of 9.8 MPa, and a curing time of 3 minutes, to obtain a molded product of 15 mm x 4 mm x 4 mm. The molded product obtained was then post-cured at 175°C for 4 hours to prepare a test piece. Then, the average linear expansion coefficient α1 (ppm/°C) of the obtained test piece was measured at 25-70°C using a thermomechanical analyzer (TMA100 manufactured by Seiko Instruments Inc.) under conditions of a measurement temperature range of 0°C to 400°C and a heating rate of 5°C/min.

(Glass Transition Temperature (Tg))
The glass transition temperature of the molding resin composition of each Example and Comparative Example was measured in accordance with JIS K 6911:2006. That is, for the molding resin composition of each Example and Comparative Example, a transfer molding machine (manufactured by Kotaki Seiki Co., Ltd., "KTS-15") was used to mold a test piece of 80 mm x 10 mm x 4 mm at a mold temperature of 175 ° C, an injection pressure of 6.9 MPa, and a curing time of 90 seconds. Then, the test piece was post-cured at 175 ° C for 2 hours. Furthermore, the thermal expansion coefficient of the test piece obtained at a heating rate of 5 ° C / min was measured using a thermomechanical analyzer (manufactured by Seiko Instruments Inc., TMA / SS6000). Next, based on the obtained measurement results, the glass transition temperature (Tg) (° C.) of the cured product was calculated from the inflection point of the thermal expansion coefficient.

(Thermal conductivity)
The molding resin compositions of each Example and Comparative Example were injected and molded using a transfer molding machine (KOTAKISEIKI Co., Ltd., "KTS-15") at a mold temperature of 175°C, injection pressure of 6.9 MPa, and curing time of 90 seconds to obtain molded bodies of 80 mm x 10 mm x 4 mm. The molded bodies obtained were then post-cured at 175°C for 2 hours to obtain test pieces. The thermal diffusivity of the obtained test pieces was measured using a laser flash method (Xenon Flash Analyzer LFA447 manufactured by NETZSCH). In addition, the specific gravity of the test pieces used for the thermal conductivity measurement was measured using an electronic specific gravity meter SD-200L manufactured by Alpha Mirage Co., Ltd. Furthermore, the specific heat of the test pieces used for the thermal conductivity and specific gravity measurement was measured using a differential scanning calorimeter DSC8230 manufactured by Rigaku Corporation. The thermal conductivity (W/m·K) in the thickness direction of the test pieces was calculated from the measured values of thermal diffusivity, specific gravity, and specific heat.

(Storage at room temperature)
The molding resin compositions of each Example and Comparative Example were measured for room temperature storage stability. Using a low pressure transfer molding machine (KOTAKISEIKI Co., Ltd.'s "KTS-30"), the molding resin compositions of each Example and Comparative Example were injected under conditions of a mold temperature of 175°C, an injection pressure of 9.8 MPa, and a curing time of 3 minutes, and the flow length was measured. The spiral flow at this time was designated as _S1 .
In addition, after the molding resin composition of each Example and Comparative Example was allowed to stand at 25° C. for 48 hours, the flow length was measured under the same conditions as above, and the spiral flow at this time was designated as _S2 .
The above _S1 and _S2 were evaluated according to the following criteria.
A: _S2 ≧0.8× _S1 is satisfied.
B: _S2 < 0.8 x _S1 is satisfied.

All of the molding resin compositions in the examples could be cured at low temperatures and had excellent adhesion and waterproofing when used to seal structures such as electronic components or stators.

This application claims priority based on Japanese Patent Application No. 2022-058500, filed on March 31, 2022, the disclosure of which is incorporated herein in its entirety.

REFERENCE SIGNS LIST 10: Substrate 11: Electronic component 20: Stator core 21: Slot 30: Coil 40: Lead wire 50: Sealing member 100: Sealed object 200: Sealing structure

Claims (19)

A molding resin composition used to collectively seal a substrate on which electronic components are mounted, a stator core fixed on the substrate and having a plurality of slots formed in a circumferential direction, and a plurality of coils housed in the slots, the composition comprising:
Epoxy resin,
a curing agent and/or a curing catalyst;
an inorganic filler;
The molding resin composition is cured at 140° C. for 2 minutes, and the cured product has a flexural modulus at 25° C. (in accordance with JIS K6911:2006) of 0.1 GPa or more and 30 GPa or less. The molding resin composition according to claim 1,
A molding resin composition having a glass transition temperature (Tg) of 140° C. or higher and 300° C. or lower, as measured by the following (Method 1).
(Method 1)
The molding resin composition is molded into a test piece of 80 mm x 10 mm x 4 mm using a transfer molding machine at a mold temperature of 175 ° C, injection pressure of 6.9 MPa, and curing time of 90 seconds, and then post-cured at 175 ° C for 2 hours. Furthermore, the thermal expansion coefficient of the obtained test piece is measured at a heating rate of 5 ° C / min using a thermomechanical analyzer. Next, based on the obtained measurement results, the glass transition temperature (Tg) ( ° C) of the cured product is calculated from the inflection point of the thermal expansion coefficient. The molding resin composition according to claim 1 or 2,
The molding resin composition, wherein the epoxy resin comprises one or more selected from the group consisting of phenol novolac type epoxy resins, cresol novolac type epoxy resins, and trisphenolmethane type epoxy resins. The molding resin composition according to claim 1 or 2 ,
The molding resin composition has a content of the epoxy resin of 3% by mass or more and 40% by mass or less, when the total solid content of the molding resin composition is taken as 100% by mass. The molding resin composition according to claim 1 or 2 ,
A molding resin composition comprising the curing agent, wherein the curing agent comprises a phenolic resin-based curing agent. The molding resin composition according to claim 5,
The molding resin composition, wherein the phenolic resin-based curing agent comprises one or more selected from the group consisting of phenol novolac resins, cresol novolac resins, naphthol novolac resins, and trisphenolmethane type phenolic resins. The molding resin composition according to claim 5 ,
The molding resin composition has a curing agent content of 0.8% by mass or more and 12% by mass or less, when the total solid content of the molding resin composition is taken as 100% by mass. The molding resin composition according to claim 1 or 2 ,
A molding resin composition comprising the curing catalyst, the curing catalyst comprising an imidazole-based compound. The molding resin composition according to claim 8,
The molding resin composition has a content of the curing catalyst of 0.01% by mass or more and 2.0% by mass or less, when the total solid content of the molding resin composition is taken as 100% by mass. The molding resin composition according to claim 1 or 2 ,
The molding resin composition satisfies S2 ≧ 0.8 × S1, where _S1 is a spiral flow measured for the molding resin composition at a mold temperature of 175°C, an injection pressure of 9.8 MPa, and a curing time of 3 minutes, and _S2 is a spiral flow measured for the molding resin composition after leaving the composition at 25°C for 48 hours, at a mold temperature of 175°C, an injection _pressure of 9.8 _MPa , and a curing time of 3 minutes. The molding resin composition according to claim 1 or 2 ,
A molding resin composition, in which the time required for a torque value to reach 2 N·m, as measured by the following (Method 2), is less than 100 seconds.
(Method 2)
Using a Curastometer (registered trademark), the torque value of the molding resin composition is measured over time at a mold temperature of 140° C. and an amplitude angle of ±0.25°. Based on the measurement results, the time (seconds) from the start of measurement until the torque value reaches 2 N·m is calculated. The molding resin composition according to claim 1 or 2 ,
A molding resin composition having a spiral flow of 70 cm or more, as measured by the following (Method 3).
(Method 3)
The molding resin composition is injected into a spiral flow measurement mold in accordance with ANSI/ASTM D 3123-72 using a low-pressure transfer molding machine under conditions of 175° C., injection pressure of 6.9 MPa, and pressure retention time of 3 minutes, and the flow length is measured, which is defined as the spiral flow (cm). The molding resin composition according to claim 1 or 2 ,
A molding resin composition having a gel time of 30 seconds or more, as measured by the following (Method 4).
(Method 4)
The molding resin composition is injected into a spiral flow measurement mold conforming to ANSI/ASTM D 3123-72 using a low-pressure transfer molding machine under conditions of 175° C., injection pressure of 6.9 MPa, and pressure retention time of 3 minutes. The time from the start of injection until the molding resin composition hardens and no longer flows is measured and taken as the gel time (seconds). The molding resin composition according to claim 1 or 2 ,
A molding resin composition having a linear expansion coefficient α1 of 10.0 ppm/° C. or less, as measured by the following (Method 5).
(Method 5)
The molding resin composition is injected and molded using a low-pressure transfer molding machine under conditions of a mold temperature of 175°C, an injection pressure of 9.8 MPa, and a curing time of 3 minutes to obtain a molded product of 15 mm x 4 mm x 4 mm. The molded product obtained is then post-cured at 175°C for 4 hours to prepare a test piece. The average linear expansion coefficient α1 (ppm/°C) of the obtained test piece at 25-70°C is measured using a thermomechanical analyzer under conditions of a measurement temperature range of 0°C to 400°C and a heating rate of 5°C/min. The molding resin composition according to claim 1 or 2 ,
A molding resin composition having a thermal conductivity of 0.5 W/m·K or more, as measured by the following (Method 6).
(Method 6)
The molding resin composition is injected and molded using a transfer molding machine under the conditions of a mold temperature of 175°C, an injection pressure of 6.9 MPa, and a curing time of 90 seconds to obtain a molded body of 80 mm x 10 mm x 4 mm. The molded body obtained is then post-cured at 175°C for 2 hours to obtain a test piece. The thermal diffusivity of the obtained test piece is measured using a laser flash method. In addition, the specific gravity of the test piece used for the thermal conductivity measurement is measured using an electronic specific gravity meter. Furthermore, the specific heat of the test piece used for the thermal conductivity and specific gravity measurement is measured using a differential scanning calorimeter. The thermal conductivity (W/m·K) in the thickness direction of the test piece is calculated from the measured values of the thermal diffusivity, specific gravity, and specific heat. A step of arranging, in a mold in a transfer molding machine, a substrate on which electronic components are mounted, a stator core having a plurality of slots formed in a circumferential direction and fixed on the substrate, and a plurality of coils housed in the slots;
a step of encapsulating the substrate, the stator core, and the coil in the mold with the molding resin composition according to claim 1 or 2 by a transfer molding method using the transfer molding machine to obtain an encapsulated structure;
A method for manufacturing a sealing structure comprising the steps of: The method for producing a sealing structure according to claim 16,
The method for producing a sealed structure, wherein in the step of obtaining the sealed structure, sealing molding is performed at a temperature equal to or lower than the Tg of a cured product of the molding resin composition. The method for producing a sealing structure according to claim 16,
A method for producing a sealing structure, the method not including a post-curing step as the step of obtaining the sealing structure. A substrate on which electronic components are mounted;
a stator core fixed on one surface of the substrate and having a plurality of slots formed in a circumferential direction;
A plurality of coils housed in the slots;
A sealed body including the above-mentioned
a sealing member provided to cover a part or the whole of the sealed object,
3. A sealing structure, wherein the sealing member is constituted by a cured product of the molding resin composition according to claim 1 .

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