JP7304161B2 - Insulating resin composition, insulating resin cured body, laminate and circuit board - Google Patents

Description

TECHNICAL FIELD The present invention relates to an insulating resin composition and a cured product thereof that are suitable for use in the production of metal-based circuit boards. The present invention also relates to a laminate and a circuit board formed using the insulating resin composition.

2. Description of the Related Art Various circuit boards have been put into practical use as circuit boards for forming hybrid integrated circuits by mounting electronic/electrical parts such as semiconductor elements. Circuit boards are classified into resin circuit boards, ceramic circuit boards, metal-based circuit boards, and the like, based on the substrate material.

Although the resin circuit board is inexpensive, its low thermal conductivity limits it to applications requiring relatively low power. A ceramic circuit board is suitable for use with a relatively large amount of electric power because of its high electrical insulation and heat resistance properties, but has the disadvantage of being expensive. On the other hand, metal-based circuit boards have intermediate properties between the two, and are used for general-purpose applications that require relatively large amounts of power, such as power supplies for refrigerators, power supplies for home air conditioners, power supplies for automobiles, and high-speed trains. It is suitable for applications such as power supplies.

For example, in Patent Document 1, a circuit board having excellent stress relaxation properties, heat resistance, moisture resistance, and heat dissipation properties is manufactured using a circuit board composition containing a specific epoxy resin, a curing agent, and an inorganic filler as essential components. A method for obtaining is disclosed.

JP 2008-266535 A

In recent years, with the spread of plug-in hybrid vehicles, electric vehicles, etc., the demand for quick chargers for vehicles is increasing. Circuit boards used for such charger applications are used at higher voltages than conventional automotive circuit boards, so higher moisture-resistant adhesiveness and moisture-resistant insulation are required, and conventional automotive circuit boards Thermal conductivity and heat cycle resistance equal to or higher than

As a method for improving the heat cycle resistance of a circuit board, there is a method of suppressing the progression of solder cracks by reducing the elastic modulus of the insulating layer to relax the thermal stress. However, when the elastic modulus of the insulating layer is reduced, the adhesive strength between the metal foil and the insulating layer tends to decrease under the conditions of high temperature, high humidity and DC voltage application, which may cause swelling of the metal foil.

An object of the present invention is to provide an insulating resin composition capable of forming an insulating layer having both excellent adhesion and insulating properties in a high-temperature and high-humidity environment and a low elastic modulus, and a cured product thereof. Another object of the present invention is to provide a circuit board having an insulating layer made of a cured product of the insulating resin composition and having excellent moisture resistance insulation, thermal conductivity and heat cycle resistance.

The present invention includes aspects shown below.
(1) containing an epoxy resin, an amine-based curing agent, an inorganic filler, and a phosphate ester compound having one or more hydroxyl groups in one molecule;
The amine-based curing agent is
a first amine-based curing agent having an amine equivalent of 300 or less;
a second amine-based curing agent having an amine equivalent of 800 or more;
An insulating resin composition containing
(2) The insulating resin composition according to (1), wherein at least one selected from the group consisting of the first amine-based curing agent and the second amine-based curing agent has a polyether chain.
(3) The content of the phosphate ester compound is 0.05 to 0.4 parts by mass with respect to a total of 100 parts by mass of the epoxy resin, the amine curing agent and the inorganic filler, (1 ) or the insulating resin composition according to (2).
(4) The insulating resin composition according to any one of (1) to (3), wherein the inorganic filler contains at least one selected from the group consisting of aluminum oxide, silica, silicon nitride and boron nitride. .
(5) The maximum particle size of the inorganic filler is 200 µm or less, and the content of the inorganic filler is 45 parts by mass with respect to the total of 100 parts by mass of the epoxy resin, the amine curing agent, and the inorganic filler. The insulating resin composition according to any one of (1) to (4), which is to 95 parts by mass.
(6) The insulating resin composition according to any one of (1) to (5), wherein the phosphate ester compound has a polyether chain.
(7) The insulating resin composition according to any one of (1) to (6), wherein the phosphate ester compound has an oxycarbonyl group.
(8) A cured insulating resin, which is a cured product of the insulating resin composition according to any one of (1) to (7).
(9) The insulating resin cured product according to (8), which has a storage elastic modulus of 500 MPa or less at 85°C.
(10) a metal plate;
The insulating resin cured body according to (8) or (9) arranged on the metal plate;
a metal foil disposed on the insulating resin cured body;
A laminate.
(11) a metal plate;
The insulating resin cured body according to (8) or (9) arranged on the metal plate;
a circuit portion disposed on the insulating resin cured body;
A circuit board.
(12) After applying a voltage of 500 V DC between the circuit part and the metal plate for 1000 hours in an environment of 85 ° C. and 85% RH, the volume resistivity between the circuit part and the metal plate at 85 ° C. and 85% RH is , 1.0×10 ⁹ Ω·cm or more, the circuit board according to (10).

INDUSTRIAL APPLICABILITY According to the present invention, an insulating resin composition capable of forming an insulating layer having both excellent adhesiveness and insulating properties in a high-temperature and high-humidity environment and a low elastic modulus and a cured product thereof are provided. Further, according to the present invention, there is provided a circuit board having an insulating layer made of a cured product of the insulating resin composition and having excellent moisture resistance insulation, thermal conductivity and heat cycle resistance.

It is a sectional view showing one embodiment of a layered product. 1 is a cross-sectional view showing an embodiment of a circuit board; FIG.

Preferred embodiments of the present invention are described in detail below.

(Insulating resin composition)
The insulating resin composition according to this embodiment contains an epoxy resin, an amine curing agent, an inorganic filler, and a phosphate ester compound having one or more hydroxyl groups in one molecule. Further, the insulating resin composition according to the present embodiment includes, as amine curing agents, a first amine curing agent having an amine equivalent of 300 or less, a second amine curing agent having an amine equivalent of 800 or more, contains

In the insulating resin composition, by using two amine-based curing agents having different amine equivalents together, a crosslinked structure of the epoxy resin develops during curing, and by using a phosphate ester compound having a hydroxyl group, Since the dispersibility and adhesion between the resin component and the inorganic filler are improved, it is possible to form a cured product having both excellent adhesion and insulation properties in a high-temperature and high-humidity environment and a low elastic modulus.

Any epoxy resin may be used as long as it is cured with an amine-based curing agent and exhibits an adhesive action. Examples of epoxy resins include bifunctional epoxy resins such as bisphenol A type epoxy resin, bisphenol F type epoxy resin, and bisphenol A/F type epoxy resin; novolac type epoxy resins such as phenol novolak type epoxy resin and cresol novolak type epoxy resin. polyfunctional epoxy resins such as trisphenolmethane-type epoxy resins; glycidylamine-type epoxy resins; heterocyclic-containing epoxy resins such as triglycidyl isocyanurate; A cyclic epoxy resin and the like can be mentioned.

Among the above epoxy resins, bifunctional epoxy resins and alicyclic epoxy resins can be preferably used. The use of these epoxy resins tends to further improve the heat cycle resistance of the circuit board. The insulating resin composition according to the present embodiment may contain at least one of a bifunctional epoxy resin and an alicyclic epoxy resin, and contains both the bifunctional epoxy resin and the alicyclic epoxy resin. good too.

When the insulating resin composition contains a bifunctional epoxy resin and an alicyclic epoxy resin, the ratio of the content _A2 of the alicyclic epoxy resin to the content _A1 of the bifunctional epoxy resin ( _A2 / _A1 , mass ratio) may be, for example, 1.5 or more, preferably 2.0 or more, more preferably 2.5 or more. This tends to further improve the heat cycle resistance of the circuit board. Also, the ratio (A ₂ /A ₁ , mass ratio) may be, for example, 8.0 or less, preferably 6.0 or less, and more preferably 4.0 or less. This tends to further improve the insulation and adhesiveness of the cured product.

The amine-based curing agent may be any curing agent having an amino group and capable of curing an epoxy resin. Examples of amine-based curing agents include aromatic amine-based curing agents, aliphatic amine-based curing agents, and dicyandiamide.

As the amine-based curing agent, an aliphatic amine-based curing agent is preferable from the viewpoint of further improving the heat cycle resistance of the circuit board.

The amine curing agent includes a first amine curing agent having an amine equivalent of 300 or less and a second amine curing agent having an amine equivalent of 800 or more.

The amine-based curing agent preferably contains an amine-based curing agent having a polyether chain, and at least one of the first amine-based curing agent and the second amine-based curing agent has a polyether chain. is more preferred, and it is even more preferred that both the first amine curing agent and the second amine curing agent have polyether chains. Since an amine-based curing agent having a polyether chain has excellent compatibility with an epoxy resin, the use of such an amine-based curing agent makes it easier to obtain a cured product with even better adhesion and heat resistance. The polyether chain is preferably a polyoxyalkylene chain, more preferably a polyoxyalkylene chain having an alkylene group selected from the group consisting of ethylene group and propylene group.

Both the first amine curing agent and the second amine curing agent are preferably aliphatic amine curing agents.

Both the first amine-based curing agent and the second amine-based curing agent are preferably curing agents having two amino groups in one molecule.

The ratio of the content _B2 of the second amine curing agent to the content _B1 of the first amine curing agent in the insulating resin composition ( _B2 / _B1 , mass ratio) is, for example, 0.2 or more. and is preferably 0.25 or more, more preferably 0.3 or more. This tends to further improve the heat cycle resistance of the circuit board. The ratio (B ₂ /B ₁ , mass ratio) may be, for example, 2.0 or less, preferably 1.5 or less, and more preferably 1.0 or less. This tends to further improve the insulation, adhesiveness and heat resistance of the cured product.

In the insulating resin composition, the ratio of the active hydrogen equivalent of the amine curing agent to the epoxy equivalent of the epoxy resin may be, for example, 0.3 to 2.0, and may be 0.5 to 1.25. It is preferably from 0.6 to 1.0.

The inorganic filler is not particularly limited, and known inorganic fillers used for applications requiring insulation and thermal conductivity can be used without particular limitations.

Examples of inorganic fillers include inorganic fillers composed of aluminum oxide, silica, aluminum nitride, silicon nitride, boron nitride, and the like.

The inorganic filler is mainly composed of an inorganic material selected from the group consisting of aluminum oxide, silica, silicon nitride and boron nitride from the viewpoint of suppressing deterioration of moisture resistance insulation due to hydrolysis of the inorganic material. is preferred. The content of the inorganic material in the inorganic filler is preferably 60% by mass or more, more preferably 70% by mass or more, and even more preferably 80% by mass or more, based on the total amount of the inorganic filler.

For example, when the inorganic filler contains a large amount of aluminum nitride, hydrolysis of the aluminum nitride may occur in a high-temperature and high-humidity environment, resulting in a decrease in insulating properties. Therefore, the content of aluminum nitride in the inorganic filler is preferably 40% by mass or less, more preferably 30% by mass or less, and even more preferably 20% by mass or less, based on the total amount of the inorganic filler. As described above, by using an inorganic material selected from the group consisting of aluminum oxide, silica, silicon nitride, and boron nitride as a main component, such deterioration in insulation due to hydrolysis is significantly suppressed. .

The shape of the inorganic filler is not particularly limited, and may be particulate, scale-like, polygonal, etc., and is preferably particulate.

The maximum particle size of the inorganic filler may be, for example, 250 μm or less, preferably 200 μm or less, more preferably 150 μm or less. This tends to further improve the insulating properties of the cured body. Although the minimum particle size of the inorganic filler is not particularly limited, it may be, for example, 0.05 μm or more, preferably 0.1 μm or more, from the viewpoint of further improving thermal conductivity. In this specification, the maximum particle size and minimum particle size of the inorganic filler indicate the d90 size and d10 size in the volume-based particle size distribution, which are measured with a laser diffraction particle size distribution analyzer.

The inorganic filler may contain two or more inorganic fillers having different average particle sizes. For example, the inorganic filler may contain a first inorganic filler with an average particle size of 25 μm or more and a second inorganic filler with an average particle size of 4 μm or less. With such an inorganic filler, filling the gaps between the first inorganic fillers with the second inorganic filler increases the filling density and further improves the thermal conductivity of the cured body. In this specification, the average particle size of the inorganic filler indicates the d50 size in the volume-based particle size distribution. The volume-based particle size distribution is measured with a laser diffraction particle size distribution analyzer.

The average particle size of the first inorganic filler is preferably 30 µm or more, more preferably 40 µm or more. Also, the average particle size of the first inorganic filler may be, for example, 200 μm or less, preferably 150 μm or less. With such an average particle size, the above-mentioned effects are exhibited more remarkably.

The average particle size of the second inorganic filler is preferably 3.5 μm or less, more preferably 3 μm or less. Also, the average particle size of the second inorganic filler may be, for example, 0.05 μm or more, preferably 0.1 μm or more. As a result, the above-described effects are exhibited more remarkably.

The content of the inorganic filler in the insulating resin composition is preferably 45 parts by mass or more, and 55 parts by mass or more, with respect to the total of 100 parts by mass of the epoxy resin, the amine-based curing agent, and the inorganic filler. It is more preferable to have This tends to further improve the moisture-resistant adhesion and thermal conductivity of the cured product. In addition, the content of the inorganic filler in the insulating resin composition is preferably 95% by mass or less with respect to the total 100 parts by mass of the epoxy resin, the amine-based curing agent and the inorganic filler, and 90% by mass. The following are more preferable. As a result, it becomes easier to obtain a cured product with improved adhesiveness and insulation in a high-temperature and high-humidity environment, and the heat cycle resistance of the circuit board tends to be further improved.

A phosphate ester compound has one or more hydroxyl groups in one molecule. In the present embodiment, the phosphate ester compound is considered to have the effect of improving the dispersibility and adhesion between the resin component and the inorganic filler and improving the moisture-resistant adhesion due to the presence of hydroxyl groups in the molecule. be done. In addition, the above phosphate ester compound traps OH radicals generated under conditions of high temperature, high humidity, and application of a direct current voltage, thereby suppressing a decrease in moisture resistance insulation due to oxidative deterioration of the insulating layer. it seems to do.

The number of hydroxyl groups possessed by the phosphate ester compound is more preferably 1 to 2 per molecule, more preferably 2 per molecule.

The phosphate ester compound preferably has a hydroxyl group directly bonded to the phosphorus atom. Moreover, it is more preferable that the phosphate ester compound has two hydroxyl groups directly bonded to the phosphorus atom.

The phosphate ester compound preferably contains a polyether chain from the viewpoint of excellent compatibility with the epoxy resin and the amine-based curing agent, and from the viewpoint of further improving the adhesion between the inorganic filler and the resin component. The polyether chain is preferably a polyoxyalkylene chain, more preferably a polyoxyalkylene chain having an alkylene group selected from the group consisting of ethylene group and propylene group.

The phosphate ester compound preferably contains an oxycarbonyl group from the viewpoint of excellent compatibility with the epoxy resin and the amine-based curing agent, and from the viewpoint of further improving the adhesion between the inorganic filler and the resin component.

The number average molecular weight of the phosphate compound is preferably 200 or more, more preferably 400 or more. Also, the number average molecular weight of the phosphate ester compound is preferably 2000 or less, more preferably 1000 or less. The number average molecular weight of the phosphate ester compound is the value measured by size exclusion chromatography (GPC).

The phosphate ester compound may be, for example, a compound represented by the following formula (1).

In formula (1), R represents a monovalent group having a polyether chain. R may further have a polyester chain.

The content of the phosphate ester compound in the insulating resin composition is preferably 0.05 parts by mass or more with respect to a total of 100 parts by mass of the epoxy resin, the amine curing agent and the inorganic filler. It is more preferably 1 part by mass or more. As a result, the above-described effects of the phosphate ester compound are exhibited more remarkably. Further, the content of the phosphate ester compound in the insulating resin composition is preferably 0.4 parts by mass or less with respect to a total of 100 parts by mass of the epoxy resin, the amine-based curing agent and the inorganic filler. It is more preferably 0.3 parts by mass or less. As a result, deterioration in moisture-resistant insulating properties and moisture-resistant adhesiveness due to moisture absorption and hydrolysis of the phosphate ester compound itself is suppressed, and the heat cycle resistance of the circuit member tends to be further improved.

The insulating resin composition may further contain other components than those mentioned above. The insulating resin composition may further contain, for example, a surface modifier such as a coupling agent, a leveling agent, an antifoaming agent, a wetting agent, a stabilizer, a curing accelerator, and the like, if necessary.

(Insulating resin cured body)
The insulating resin cured product according to this embodiment is a cured product of the insulating resin composition described above. The insulating resin cured product can form an insulating layer having both excellent adhesiveness and insulating properties in a high-temperature and high-humidity environment and a low elastic modulus.

The storage elastic modulus of the cured insulating resin at 85° C. is preferably 500 MPa or less, more preferably 250 MPa or less, and even more preferably 150 MPa or less. According to such an insulating resin cured body, a circuit board having even better heat cycle resistance can be realized.

The method for producing the insulating resin cured product is not particularly limited. For example, the insulating resin cured body can be produced by heat-treating and curing an insulating resin composition. The heat treatment may be performed in one step or in two steps. By performing the heat treatment in two steps, the insulating resin cured product can be formed via the semi-cured product of the insulating resin composition.

When the heat treatment is performed in one step, the heat treatment temperature may be, for example, 150 to 250° C., preferably 160 to 240° C., and the heat treatment time may be, for example, 2 to 15 hours, preferably 2 hours. .5 to 10 hours.

When the heat treatment is performed in two stages, the temperature of the heat treatment in the first stage may be, for example, 60 to 130° C., preferably 65 to 100° C., and the heat treatment time is, for example, 0.3 to 8 hours. , preferably 0.5 to 5 hours. The temperature of the heat treatment in the second stage may be, for example, 150 to 250° C., preferably 160 to 240° C., and the heat treatment time may be, for example, 2 to 15 hours, preferably 2.5. ~10 hours.

By performing heat treatment while maintaining the insulating resin composition or its semi-cured body in a predetermined shape, it is possible to obtain a cured insulating resin body having a predetermined shape. For example, a layered insulating resin cured product can be formed on a metal plate by applying the insulating resin composition onto a metal plate, laminating a metal foil as necessary, and curing the composition.

(Laminate)
A laminate according to the present embodiment includes a metal plate, an insulating resin cured body placed on the metal plate, and a metal foil placed on the insulating resin cured body. In the laminate according to this embodiment, the metal plate and the metal foil may be separated by the insulating resin cured body, and the insulating resin cured body may function as an insulating layer.

Metal materials constituting the metal plate are not particularly limited, and examples thereof include aluminum, aluminum alloys, copper, copper alloys, iron, stainless steel, and the like. The metal plate may be composed of one kind of metal material, or may be composed of two or more kinds of metal materials. Moreover, the metal plate may have a single-layer structure or a multi-layer structure.

The thickness of the metal plate is not particularly limited, and may be, for example, 0.5 to 3.0 mm from the viewpoint of being suitable for manufacturing a circuit board.

Metal materials constituting the gold foil are not particularly limited, and examples thereof include copper, aluminum, and nickel. The metal foil may be composed of one kind of metal material, or may be composed of two or more kinds of metal materials. Moreover, the metal foil may have a single-layer structure or a multi-layer structure.

The thickness of the metal foil is not particularly limited, and may be, for example, 5 μm to 1 mm from the viewpoint of being suitable for making a circuit board.

The thickness of the insulating resin cured body is not particularly limited, and may be, for example, 50 μm to 300 μm from the viewpoint of being suitable for making a circuit board.

The laminate preferably has a 90-degree peel strength of the metal foil at 85° C. of 2 N/cm or more, more preferably 5 N/cm or more. Such a laminate easily maintains sufficient adhesion between the metal foil and the cured insulating resin even under conditions of high temperature, high humidity, and direct current voltage application, so that the laminate has excellent heat cycle resistance. A printed circuit board is obtained. The peel strength is measured by the method described in JIS C2110.

A method for manufacturing the laminate is not particularly limited. For example, the laminate is formed by applying an insulating resin composition on a metal plate and curing or semi-curing it, and then curing or semi-curing the cured or semi-cured insulating resin composition (that is, insulating resin cured or semi-cured body ) bonding a metal foil thereon. The method may further include a step of curing the semi-cured insulating resin composition. The joining of the metal foils may be performed by, for example, a roll lamination method, lamination press method, or the like.

In addition, the laminated body is obtained by applying an insulating resin composition on a metal foil and curing or semi-curing it, and curing or semi-curing the insulating resin composition (that is, insulating resin cured body or semi-cured body ) bonding a metal plate thereon. The method may further include a step of curing the semi-cured insulating resin composition.

FIG. 1 is a cross-sectional view showing a preferred embodiment of the laminate. A laminate 10 shown in FIG. 1 includes a metal plate 1 , a metal foil 3 , and an insulating layer 2 interposed between the metal plate 1 and the metal foil 3 and made of a cured insulating resin. A circuit board can be easily formed by processing the metal foil 3 of the laminate 10 into a predetermined pattern.

(circuit board)
A circuit board according to the present embodiment includes a metal plate, an insulating resin cured body placed on the metal plate, and a circuit portion placed on the insulating resin cured body. In the circuit board according to the present embodiment, the metal plate and the circuit portion may be separated by the insulating resin cured body, and the insulating resin cured body may function as an insulating layer.

The metal plate can be exemplified by the same metal plate as in the laminate described above.

The circuit section may be made of a metal material. As the metal material forming the circuit section, the same metal material as the metal material forming the metal foil described above can be exemplified. The circuit portion may be formed by processing the metal foil described above into a predetermined pattern.

The thickness of the circuit portion is not particularly limited, and may be, for example, 5 μm to 1 mm from the viewpoint of heat resistance and workability.

The thickness of the insulating resin cured body is not particularly limited, and may be, for example, 50 μm to 300 μm from the viewpoint of thermal conductivity and insulation.

After continuously applying a voltage of DC 500 V between the circuit part and the metal plate for 1000 hours in an environment of 85 ° C. and 85% RH, the circuit board measured the volume resistivity between the circuit part and the metal plate at 85 ° C. and 85% RH. is preferably 1.0×10 ⁹ Ω·cm or more, more preferably 5.0×10 ⁹ Ω·cm or more. Such a circuit board can be said to be a circuit board particularly excellent in moisture resistance insulation.

A method for manufacturing the circuit board is not particularly limited. For example, a circuit board can be manufactured by a method including a step of processing the metal foil of the laminate into a predetermined pattern. A method for processing (etching) the metal foil is not particularly limited, and a conventionally known method may be applied.

FIG. 2 is a cross-sectional view of a preferred embodiment of a circuit board. A circuit board 20 shown in FIG. 2 includes a metal plate 1 , a circuit portion 4 , and an insulating layer 2 interposed between the metal plate 1 and the circuit portion 4 and made of a cured insulating resin. The circuit board 20 may be formed by processing the metal foil 3 of the laminate 10 into the circuit portion 4, for example.

Although the preferred embodiments of the present invention have been described above, the present invention is not limited to the above embodiments.

<Example 1>
(Synthesis of phosphate ester compound)
An autoclave was charged with 90 g of methoxypropanol and 0.3 g of potassium hydroxide, and after the autoclave was purged with nitrogen, the temperature was raised to 100° C., and 1914 g of propylene oxide was pressurized over 3 hours while stirring. After that, the mixture was stirred at 90 to 100° C. for 30 minutes, cooled, neutralized with phosphoric acid water, dehydrated and filtered to obtain polypropylene glycol monomethyl ether.

An autoclave was charged with 400 g of polypropylene glycol monomethyl ether, 100 g of succinic anhydride, and 2 g of tetramethylammonium chloride. After stirring at 100° C. for 2 hours, 558 g of oil was obtained.

1.8 g of water was added to 558 g of the above oil, and 14 g of phosphorus pentoxide was added little by little over about 30 minutes while maintaining the temperature at 50°C. Then, the mixture was stirred at the same temperature for about 1 hour to obtain a phosphate ester compound (P-1) having two hydroxyl groups bonded to phosphorus atoms and a polyether chain.
The number average molecular weight of the obtained phosphate ester was determined to be 510 by size exclusion chromatography.

(Preparation of insulating resin composition)
Bisphenol A/F type epoxy resin (manufactured by Mitsubishi Chemical Corporation, "YD-6020") 2.2 parts by mass, bisphenol A type hydrogenated epoxy resin (manufactured by Nippon Steel & Sumikin Chemical Co., Ltd., "YX-8000") 6.7 mass parts, aliphatic amine (manufactured by Huntsman, "D-400", amine equivalent weight 200) 2.4 parts by weight, aliphatic amine (manufactured by Huntsman, "D-2000", amine equivalent weight 1040) 1.6 parts by weight, Alumina (“DAS45” manufactured by Denka Co., Ltd., maximum particle size 70 μm, average particle size 45 μm) 30.5 parts by mass, alumina (“DAS10” manufactured by Denka Co., Ltd., maximum particle size 21 μm, average particle size 10 μm) 30.5 parts by mass, 26.1 parts by mass of alumina (“AA2” manufactured by Sumitomo Chemical Co., Ltd., maximum particle size: 5 μm, average particle size: 2 μm) and 0.2 parts by mass of phosphate compound (P-1) were added. The mixture was kneaded with a planetary stirrer ("Thinky Mixer AR-310", rotation speed 2000 rpm) to prepare an insulating resin composition.

(Manufacture of circuit boards)
An insulating resin composition is applied to an aluminum plate with a thickness of 1.5 mm (manufactured by Amano Aluminum Co., Ltd., "A1050 1.5 mm thickness") and dried at 120 ° C. for 15 minutes to obtain a B stage (semi-cured) state. and The amount of the insulating resin composition applied was adjusted so that the thickness of the insulating layer after curing was 100 μm.

After that, a 70 μm thick copper foil (manufactured by Furukawa Electric Co., Ltd., “Electrolytic copper foil 70 μm thick”) is placed on the semi-cured body of the insulating resin composition, and a heat press method is performed to 180 mm in the laminated state. C. for 6 hours to cure the semi-cured body to obtain a laminate.

Next, after masking a predetermined position with an etching resist, the copper foil was etched using a mixed solution of sulfuric acid and hydrogen peroxide as an etchant. By removing the etching resist, washing and drying, a circuit board having a circuit portion made of copper foil was obtained.

<Example 2>
An insulating resin composition and a circuit board were obtained in the same manner as in Example 1, except that the amount of the phosphate ester compound (P-1) added was changed to 0.06 parts by mass.

<Example 3>
An insulating resin composition and a circuit board were obtained in the same manner as in Example 1, except that the amount of the phosphate ester compound (P-1) added was changed to 0.38 parts by mass.

<Example 4>
As an inorganic filler, aluminum nitride (Denka, maximum particle size 70 μm (Denka, maximum particle size 70 μm, average particle size 45 μm) 39.2 parts by mass, alumina (Denka “DAS10”, maximum particle size 21 μm , average particle diameter 10 μm) 21.8 parts by mass, and alumina (“AA2” manufactured by Sumitomo Chemical Co., Ltd., maximum particle diameter 5 μm, average particle diameter 2 μm) 26.1 parts by weight were added. Similarly, an insulating resin composition and a circuit board were obtained.

<Example 5>
As an inorganic filler, alumina (“DAW20” manufactured by Denka Co., Ltd., maximum particle size 32 μm, average particle size 20 μm) 30.5 parts by mass, alumina (“DAS10” manufactured by Denka Co., Ltd., maximum particle size 21 μm, average particle size 10 μm) 30 .5 parts by mass and 26.1 parts by mass of alumina (“AA2” manufactured by Sumitomo Chemical Co., Ltd., maximum particle size 5 μm, average particle size 2 μm) were added in the same manner as in Example 1, insulating resin A composition and a circuit board were obtained.

<Example 6>
As an inorganic filler, alumina (“DAW70” manufactured by Denka, maximum particle size 113 μm, average particle size 70 μm) 30.5 parts by mass, alumina (“DAS10” manufactured by Denka, maximum particle size 21 μm, average particle size 10 μm) 30 .5 parts by mass and 26.1 parts by mass of alumina (“AA2” manufactured by Sumitomo Chemical Co., Ltd., maximum particle size 5 μm, average particle size 2 μm) were added in the same manner as in Example 1, insulating resin A composition and a circuit board were obtained.

<Example 7>
The amount of bisphenol A/F type epoxy resin ("YD-6020" manufactured by Mitsubishi Chemical Corporation) added is 9.0 parts by mass, and the amount of bisphenol A type hydrogenated epoxy resin ("YX-8000" manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.) is added. Addition amount of 27.0 parts by mass, aliphatic amine (manufactured by Huntsman, "D-400", amine equivalent 200) addition amount of 9.5 parts by mass, aliphatic amine (manufactured by Huntsman, "D-2000" , amine equivalent 1040) was changed to 6.3 parts by mass. Further, 48.2 parts by mass of boron nitride (“XGP” manufactured by Denka Co., Ltd., maximum particle size 90 μm, average particle size 30 μm) was added as an inorganic filler. An insulating resin composition and a circuit board were obtained in the same manner as in Example 1 except for the above.

<Example 8>
The amount of bisphenol A/F type epoxy resin ("YD-6020" manufactured by Mitsubishi Chemical Corporation) added is 1.2 parts by mass, and the amount of bisphenol A type hydrogenated epoxy resin ("YX-8000" manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.) is added. Addition amount of 3.6 parts by mass, aliphatic amine (manufactured by Huntsman, "D-400", amine equivalent 200) addition amount of 1.3 parts by mass, aliphatic amine (manufactured by Huntsman, "D-2000" , amine equivalent 1040) added amount of 0.8 parts by mass, alumina (Denka "DAS45", maximum particle size 70 μm, average particle size 45 μm) added amount of 32.6 parts by mass, alumina (Denka " DAS10”, maximum particle size 21 μm, average particle size 10 μm) added amount to 32.6 parts by mass, alumina (Sumitomo Chemical Co., Ltd. “AA2”, maximum particle size 5 μm, average particle size 2 μm) to 27.9 parts by mass changed. An insulating resin composition and a circuit board were obtained in the same manner as in Example 1 except for the above.

<Example 9>
Addition amount of aliphatic amine (manufactured by Huntsman, "D-400", amine equivalent 200) is 3.2 parts by mass, and addition amount of aliphatic amine (manufactured by Huntsman, "D-2000", amine equivalent 1040) is It was changed to 0.8 parts by mass. An insulating resin composition and a circuit board were obtained in the same manner as in Example 1 except for the above.

<Example 10>
The amount of bisphenol A/F type epoxy resin (manufactured by Mitsubishi Chemical Corporation, "YD-6020") is 1.3 parts by mass, and the amount of bisphenol A type hydrogenated epoxy resin (manufactured by Nippon Steel & Sumikin Chemical Co., Ltd., "YX-8000") is added. Addition amount of 7.6 parts by mass, aliphatic amine (manufactured by Huntsman, "D-400", amine equivalent 200) addition amount of 2.4 parts by mass, aliphatic amine (manufactured by Huntsman, "D-2000" , amine equivalent 1040) was changed to 1.6 parts by mass. An insulating resin composition and a circuit board were obtained in the same manner as in Example 1 except for the above.

<Comparative Example 1>
An insulating resin composition and a circuit board were obtained in the same manner as in Example 1, except that the phosphate ester compound (P-1) was not added.

<Comparative Example 2>
Instead of the phosphate ester compound (P-1), except that 0.2 parts by mass of a phosphate ester compound having no hydroxyl group in the molecule (manufactured by Johoku Chemical Industry Co., Ltd., "JC-224") was added. An insulating resin composition and a circuit board were obtained in the same manner as in Example 1.

<Comparative Example 3>
The addition amount of the aliphatic amine (manufactured by Huntsman, "D-400", amine equivalent weight 200) was changed to 4.0 parts by mass, and the aliphatic amine (manufactured by Huntsman, "D-2000", amine equivalent weight 1040) was added. An insulating resin composition and a circuit board were obtained in the same manner as in Example 1, except that they were not added.

<Comparative Example 4>
Aliphatic amine (manufactured by Huntsman, "D-400", amine equivalent 200) was not added, and the amount of aliphatic amine (manufactured by Huntsman, "D-2000", amine equivalent 1040) was added to 4.0 parts by mass. An insulating resin composition and a circuit board were obtained in the same manner as in Example 1, except for changing to .

<Comparative Example 5>
Instead of the aliphatic amine (manufactured by Huntsman, "D-400", amine equivalent 200), 2.4 parts by mass of an aliphatic amine (manufactured by Huntsman, "ED-900", amine equivalent 450) was added. obtained an insulating resin composition and a circuit board in the same manner as in Example 1.

Table 1 shows the formulations of the insulating resin compositions of Examples and Comparative Examples. The maximum particle size and average particle size of the inorganic fillers used in Examples and Comparative Examples were obtained by the following methods.

[Measurement of inorganic filler]
Measurement was performed using a “laser diffraction particle size distribution analyzer SALD-200” manufactured by Shimadzu Corporation. Specifically, 50 cc of pure water and 5 g of an inorganic filler were added to a glass beaker, stirred with a spatula, and then dispersed with an ultrasonic cleaner for 10 minutes. The inorganic filler dispersion was added drop by drop to the sampler section of the apparatus using a dropper, and the absorbance was allowed to stabilize until it became measurable. Measurement was performed when the absorbance became stable. In the laser diffraction particle size distribution analyzer, the particle size distribution was calculated from the light intensity distribution data of the diffracted/scattered light by the particles detected by the sensor. The maximum particle size was d90, and the average particle size was d50.

[Measurement of Phosphate Ester Compound]
The number average molecular weight of the phosphate ester compound (P-1) was measured using size exclusion chromatography manufactured by Tosoh Corporation. Tetrahydrofuran was used as the mobile phase, and the value converted to polystyrene was used with an RI detector (refractive method) under the conditions of a flow rate of 1.0 ml/min.

The insulating resin compositions obtained in Examples and Comparative Examples and the circuit board obtained in Example 1 were evaluated by the following methods. Table 2 shows the results.

[Measurement of Storage Elastic Modulus of Cured Insulating Resin]
The measurement was performed using TA Instruments'"RSA-III". Specifically, the insulating resin composition was applied onto a PET film so that the thickness after curing was 200 μm, and cured by heating at 180° C. for 6 hours to produce a cured insulating resin. A measurement sample was obtained by processing the prepared insulating resin cured body into a width of 4 mm and a length of 5 cm. Using the obtained sample, the measurement frequency was set to 1 Hz, and the temperature was raised from -50°C to 150°C at a heating rate of 7°C/min to measure the storage modulus. From the measurement results, the storage modulus at 85°C was obtained.

[Measurement of Thermal Conductivity of Cured Insulating Resin]
Thermal conductivity was calculated from thermal diffusivity, specific gravity and specific heat. Specifically, first, the thermal conductivity was obtained by a laser flash method using a measurement sample obtained by processing an insulating resin cured body to have a width of 10 mm, a length of 10 mm, and a thickness of 1 mm. A xenon flash analyzer (LFA447NanoFlash manufactured by NETZSCH) was used as a measuring device. The specific gravity was determined using the Archimedes method. The specific heat was determined by raising the temperature from room temperature to 300°C at a heating rate of 10°C/min in a nitrogen atmosphere using a differential scanning calorimeter ("Q2000" manufactured by TA Instruments).

[Evaluation of moisture resistance insulation]
For the laminates obtained in Examples and Comparative Examples, copper foils were etched to prepare circular electrodes with a diameter of 20 mm, which were used as measurement samples. Then, under the conditions of 85° C. and 85% RH, a DC voltage of 500 V was applied between the circular electrode and the metal plate for 1000 hours. After voltage application, the volume resistivity between the circular electrode and the metal plate was measured at 85° C. and 85% RH. This measurement was performed using an insulation deterioration system (“SIR13” manufactured by Kusumoto Kasei Co., Ltd.).

[Evaluation of moisture resistant adhesion]
For the laminates obtained in Examples and Comparative Examples, copper foils were etched to prepare circular electrodes with a diameter of 20 mm, which were used as measurement samples. Then, under the conditions of 85° C. and 85% RH, a DC voltage of 500 V was applied between the circular electrode and the metal plate for 1000 hours. C is when the electrode part is swollen by 500 hours after the start of voltage application, B is when the electrode part is swollen after 500 to 1000 hours, and the electrode part is not swollen even after 1000 hours. The case was evaluated as A. The presence or absence of swelling was visually confirmed.

[Evaluation of heat cycle resistance]
Electrodes were produced by etching the copper foils of the laminates obtained in Examples and Comparative Examples, and used as measurement samples. A chip resistor with a chip size of 2.0 mm x 1.25 mm is soldered between the electrodes of the circuit board, and a cycle of -40°C for 15 minutes to +150°C for 15 minutes is applied to 2000 heat cycle tests at JIS-C-0025 temperature. It was carried out according to the change test method. The total number of chip resistors was 20 for each example and comparative example. After the test, the presence or absence of cracks in the solder portion was observed under a microscope. C was evaluated when 10% or more of cracks occurred in the solder portion, and A was evaluated when less than 10% of solder cracks occurred.

As shown in Table 2, in Examples, it was confirmed that an insulating layer having both a low elastic modulus and a high thermal conductivity can be formed, and a circuit board having excellent moisture-resistant insulation, moisture-resistant adhesion, and heat cycle resistance can be obtained. was done.

According to the present invention, it is possible to form an insulating layer having both excellent adhesiveness and insulating properties in a high-temperature and high-humidity environment and a low elastic modulus. According to the present invention, a circuit board having the insulating layer and having excellent moisture resistance insulation, thermal conductivity, and heat cycle resistance can be obtained. Therefore, the present invention can be suitably used in fields where heat cycle resistance, moisture resistance insulation, heat dissipation, etc. are required (for example, circuit substrates for vehicle-mounted chargers, etc.).

DESCRIPTION OF SYMBOLS 1... Metal plate, 2... Insulating layer, 3... Metal foil, 4... Circuit part, 10... Laminated body, 20... Circuit board.

Claims (11)

containing an epoxy resin, an amine-based curing agent, an inorganic filler, and a phosphate ester compound having one or more hydroxyl groups in one molecule,
The epoxy resin is
a bifunctional epoxy resin selected from the group consisting of bisphenol A type epoxy resins, bisphenol F type epoxy resins and bisphenol A/F type epoxy resins;
an alicyclic epoxy resin selected from the group consisting of hydrogenated bisphenol A type epoxy resins and hydrogenated bisphenol F type epoxy resins;
contains
The amine-based curing agent is
a first amine-based curing agent having an amine equivalent of 300 or less;
a second amine-based curing agent having an amine equivalent of 800 or more;
contains
the inorganic filler contains an inorganic material selected from the group consisting of aluminum oxide, silica, silicon nitride and boron nitride;
The content of the inorganic material in the inorganic filler is 80% by mass or more based on the total amount of the inorganic filler,
The insulating resin, wherein the ratio of the content A2 of _the alicyclic epoxy resin to the content _A1 of the bifunctional epoxy resin (A2 _/ A1 _, mass ratio) is 1.5 or more and 8.0 or less. Composition. 2. The insulating resin composition according to claim 1, wherein at least one selected from the group consisting of said first amine-based curing agent and said second amine-based curing agent has a polyether chain. Claim 1 or 2, wherein the content of the phosphate ester compound is 0.05 to 0.4 parts by mass with respect to a total of 100 parts by mass of the epoxy resin, the amine curing agent and the inorganic filler. The insulating resin composition according to . The maximum particle size of the inorganic filler is 200 μm or less,
The content of the inorganic filler is 45 to 95 parts by mass with respect to a total of 100 parts by mass of the epoxy resin, the amine curing agent and the inorganic filler, any one of claims 1 to 3 . The insulating resin composition according to . The insulating resin composition according to any one of claims 1 to 4 , wherein the phosphate ester compound has a polyether chain. The insulating resin composition according to any one of claims 1 to 5 , wherein the phosphate ester compound has an oxycarbonyl group. An insulating resin cured product, which is a cured product of the insulating resin composition according to any one of claims 1 to 6 . The insulating resin cured product according to claim 7 , which has a storage elastic modulus at 85°C of 500 MPa or less. a metal plate;
The insulating resin cured body according to claim 7 or 8 arranged on the metal plate;
a metal foil disposed on the insulating resin cured body;
A laminate. a metal plate;
The insulating resin cured body according to claim 7 or 8 arranged on the metal plate;
a circuit portion disposed on the insulating resin cured body;
A circuit board. The volume resistivity between the circuit part and the metal plate at 85°C and 85% RH after continuously applying a DC voltage of 500V between the circuit part and the metal plate for 1000 hours in an environment of 85°C and 85% RH was 1. 11. The circuit board according to claim 10 , which is 0×10 ⁹ Ω·cm or more.

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