CN114364738A

CN114364738A - Insulating resin composition, insulating resin cured product, laminate, and circuit board

Info

Publication number: CN114364738A
Application number: CN202080063653.8A
Authority: CN
Inventors: 木元裕纪; 熊谷良太; 八岛克宪
Original assignee: Denka Co Ltd
Current assignee: Denka Co Ltd
Priority date: 2019-11-08
Filing date: 2020-10-07
Publication date: 2022-04-15
Also published as: WO2021090629A1; TW202124575A; JPWO2021090629A1

Abstract

The insulating resin composition comprises an organic material and an inorganic filler, wherein the organic material contains an epoxy resin, an amine-based curing agent, a phosphate ester compound having 1 or more hydroxyl groups in 1 molecule, and a heavy metal deactivator, and the content of the inorganic filler is 50 to 95 mass%.

Description

Insulating resin composition, insulating resin cured product, laminate, and circuit board

Technical Field

The present invention relates to an insulating resin composition suitable for use in the production of a metal-base circuit board, and a cured product thereof. The present invention also relates to a laminate and a circuit board formed using the insulating resin composition.

Background

Various circuit boards have been put into practical use as circuit boards for mounting electronic and electric components such as semiconductor elements to form hybrid integrated circuits. The circuit board is classified into a resin circuit board, a ceramic circuit board, a metal-base circuit board, and the like based on the material of the board.

Although the resin circuit board is inexpensive, the use of the board is limited to use with a small amount of electric power because of its low thermal conductivity. Ceramic circuit boards are suitable for applications using large electric power because of their high electrical insulation properties and heat resistance, but they have the disadvantage of being expensive. On the other hand, the metal base circuit board has properties between those described above, and is suitable for general-purpose applications in which large electric power is used, for example, applications such as a power supply for a refrigerator, a power supply for an air conditioner for home use, a power supply for an automobile, and a power supply for a high-speed railway.

For example, patent document 1 discloses: a method for obtaining a circuit board excellent in stress relaxation property, heat resistance, moisture resistance and heat dissipation property by using a composition for a circuit board containing a specific epoxy resin, a curing agent and an inorganic filler as essential components.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open No. 2008-266535

Disclosure of Invention

Problems to be solved by the invention

In recent years, with the spread of plug-in hybrid vehicles, electric vehicles, and the like, there has been an increasing demand for rapid chargers for automobiles. Since the circuit board used in such a charger is used at a higher voltage than a conventional circuit board for an automobile, the circuit board is required to have higher moisture-resistant adhesion and moisture-resistant insulation properties, and also required to have heat conductivity and heat cycle resistance equal to or higher than those of the conventional circuit board for an automobile.

As a method for improving the heat cycle resistance of the circuit board, there is a method of suppressing the progress of solder cracking by relaxing the thermal stress by lowering the elastic modulus of the insulating layer. However, when the insulating layer has a low elastic modulus, the bonding strength between the metal foil and the insulating layer tends to be reduced under the conditions of high-temperature and high-humidity environment and application of a dc voltage, which may cause expansion of the metal foil.

An object of the present invention is to provide an insulating resin composition capable of providing an insulating layer having both excellent adhesion and insulation properties under 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 which has an insulating layer formed of a cured product of the insulating resin composition and is excellent in moisture-resistant insulating properties, thermal conductivity, and heat cycle resistance.

Means for solving the problems

One aspect of the present invention relates to an insulating resin composition comprising an organic material and an inorganic filler. In the insulating resin composition, the organic material contains an epoxy resin, an amine-based curing agent, a phosphate ester compound having 1 or more hydroxyl groups in 1 molecule, and a heavy metal deactivator, and the content of the inorganic filler is 50 to 95 mass%.

In one embodiment, the amine-based curing agent may contain a first amine-based curing agent having an amine equivalent of 300 or less and a second amine-based curing agent having an amine equivalent of 800 or more.

In one embodiment, the content of the phosphate ester compound may be 0.05 to 0.4% by mass based on the total amount of the organic material and the inorganic filler.

In one embodiment, the content of the heavy metal deactivator may be 0.01 to 0.5% by mass based on the total amount of the organic material and the inorganic filler.

In one embodiment, the melting point of the heavy metal deactivator may be 250 ℃ or lower.

Another aspect of the present invention relates to an insulating resin cured product, which is a cured product of the insulating resin composition.

The cured product of an insulating resin according to one embodiment may have a storage modulus at 85 ℃ of 500MPa or less.

Another aspect of the present invention relates to a laminate including: a metal plate; the insulating resin cured product disposed on the metal plate; and a metal foil disposed on the cured insulating resin.

Another aspect of the present invention relates to a circuit board including: a metal plate; the insulating resin cured product disposed on the metal plate; a circuit portion disposed on the cured insulating resin.

Effects of the invention

According to the present invention, an insulating resin composition capable of forming an insulating layer having both excellent adhesion and insulation properties under a high-temperature and high-humidity environment and a low elastic modulus, and a cured product thereof can be provided. Further, according to the present invention, there can be provided a circuit board which is provided with an insulating layer comprising a cured product of the insulating resin composition and which is excellent in moisture-resistant insulating properties, thermal conductivity and heat cycle resistance.

Drawings

Fig. 1 is a sectional view showing an embodiment of a laminate.

Fig. 2 is a cross-sectional view showing one embodiment of a circuit board.

Detailed Description

Hereinafter, preferred embodiments of the present invention will be described in detail.

(insulating resin composition)

The insulating resin composition of the present embodiment contains an organic material and an inorganic filler, and the content of the inorganic filler is 50 mass% or more and 95 mass% or less. The insulating resin composition of the present embodiment includes an epoxy resin as an organic material, an amine-based curing agent, a phosphate ester compound having 1 or more hydroxyl groups in 1 molecule, and a heavy metal deactivator.

According to the insulating resin composition, a cured product (insulating layer) having both excellent adhesion and insulation properties under a high-temperature and high-humidity environment and a low elastic modulus can be formed. Therefore, the insulating resin composition can be suitably used for forming an insulating layer for a circuit board (particularly, a metal base circuit board). The reason why the above-described effects can be obtained in the present embodiment is not necessarily clear, but the following can be considered.

In the present embodiment, it is considered that the presence of hydroxyl groups in the molecule of the phosphate ester compound improves the dispersibility and adhesion between the resin component and the inorganic filler, and improves the wet-bond resistance. Further, it is considered that the phosphate ester compound also suppresses a decrease in moisture resistance insulation due to oxidation deterioration of the insulating layer by trapping OH radicals generated under the conditions of high-temperature and high-humidity environment and application of a dc voltage.

Further, although it is considered that ionic impurities migrate into the insulating layer as a cause of the deterioration of the adhesion and the insulation properties, in the present embodiment, the metal ions are captured by the heavy metal deactivator, and the adverse effect due to the migration is suppressed. In particular, in the case where a metal plate such as a metal base circuit board is adjacent to an insulating layer, elution of metal ions (for example, copper ions) from the metal plate into the insulating layer occurs, but according to the insulating resin composition of the present embodiment, an insulating layer maintaining excellent moisture-resistant bonding properties and moisture-resistant insulating properties can be formed even in the case where the metal plate is adjacent to the insulating layer.

In the present embodiment, it is considered that the effect of the phosphate ester compound and the heavy metal deactivator can be remarkably obtained and the elastic modulus of the cured product can be reduced by forming a crosslinked structure of the epoxy resin and the amine-based curing agent in the cured product.

The epoxy resin may be any epoxy resin that is cured by an amine-based curing agent and exhibits a bonding effect. Examples of the epoxy resin 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 Novolac type epoxy resins and cresol Novolac type epoxy resins; polyfunctional epoxy resins such as trisphenol methane type epoxy resins; glycidyl amine type epoxy resins; and alicyclic epoxy resins such as a heterocycle-containing epoxy resin such as triglycidyl isocyanurate, a hydrogenated bisphenol a epoxy resin, and a hydrogenated bisphenol F epoxy resin.

Among the above, a bifunctional epoxy resin (bifunctional aromatic epoxy resin) and an alicyclic epoxy resin can be preferably used as the epoxy resin. By using these epoxy resins, the heat cycle resistance of the circuit board tends to be further increased. The insulating resin composition according to the present embodiment may contain at least one of a bifunctional epoxy resin and an alicyclic epoxy resin, or may contain both of a bifunctional epoxy resin and an alicyclic epoxy resin.

When the insulating resin composition contains a bifunctional epoxy resin and an alicyclic epoxy resin, the content A of the bifunctional epoxy resin is₁The content A of the alicyclic epoxy resin₂Ratio of (A)₂/A₁Mass ratio) may be, for example, 1.5 or more, preferably 2.0 or more, and more preferably 2.5 or more. This tends to further improve the heat cycle resistance of the circuit board. In addition, the above ratio (A)₂/A₁Mass ratio) may be, for example, 8.0 or less, preferably 6.0 or less, and more preferably 4.0 or less. Thereby having the insulating property of the cured product andthe bondability tends to be further improved. And, the above ratio (A)₂/A₁Mass ratio) may be, for example, 1.5 to 8.0, 1.5 to 6.0, 1.5 to 4.0, 2.0 to 8.0, 2.0 to 6.0, 2.0 to 4.0, 2.5 to 8.0, 2.5 to 6.0, or 2.5 to 4.0.

The content of the epoxy resin in the insulating resin composition is, for example, 50 mass% or more, preferably 55 mass% or more, more preferably 60 mass% or more, and further preferably 65 mass% or more, based on the total amount of the organic material. The content of the epoxy resin is, for example, 90 mass% or less, preferably 85 mass% or less, more preferably 80 mass% or less, and still more preferably 75 mass% or less based on the total amount of the organic material. Specifically, the content of the epoxy resin in the insulating resin composition is, for example, 50 to 90 mass%, 50 to 85 mass%, 50 to 80 mass%, 50 to 75 mass%, 55 to 90 mass%, 55 to 85 mass%, 55 to 80 mass%, 55 to 75 mass%, 60 to 90 mass%, 60 to 85 mass%, 60 to 80 mass%, 60 to 75 mass%, 65 to 90 mass%, 65 to 85 mass%, 65 to 80 mass%, or 65 to 75 mass%, based on the total amount of the organic material.

The amine-based curing agent may be a curing agent having an amino group and capable of curing an epoxy resin. Examples of the amine-based curing agent include an aromatic amine-based curing agent, an aliphatic amine-based curing agent, 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-based curing agent preferably contains a first amine-based curing agent having an amine equivalent of 300 or less and a second amine-based curing agent having an amine equivalent of 800 or more. By using 2 kinds of amine-based curing agents having different amine equivalent weights in combination, the density of the crosslinked structure of the epoxy resin tends to be increased during curing, and the elastic modulus of the cured product tends to be further decreased.

The amine-based curing agent preferably contains an amine-based curing agent having a polyether chain, more preferably at least one of the first amine-based curing agent and the second amine-based curing agent has a polyether chain, and even more preferably both the first amine-based curing agent and the second amine-based curing agent have polyether chains. Since the amine-based curing agent having a polyether chain has excellent compatibility with an epoxy resin, a cured product having more excellent adhesion and heat resistance can be easily obtained by using such an amine-based curing agent. The polyether chain is preferably a polyoxyalkylene chain, and more preferably a polyoxyalkylene chain having an alkylene group selected from the group consisting of an ethylene group and a propylene group.

Preferably, the first amine-based curing agent and the second amine-based curing agent are both aliphatic amine-based curing agents.

The first amine-based curing agent and the second amine-based curing agent are each preferably a curing agent having at least 2 amino groups in 1 molecule.

Content B of the first amine-based curing agent in the insulating resin composition₁In terms of the content B of the second amine-based curing agent₂Ratio of (B)₂/B₁Mass ratio) is, for example, 0.2 or more, preferably 0.25 or more, and more preferably 0.3 or more. This tends to further improve the heat cycle resistance of the circuit board. In addition, the above ratio (B)₂/B₁Mass ratio) is, 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 properties, adhesiveness, and heat resistance of the cured product. I.e. the above ratio (B)₂/B₁Mass ratio) of 0.2 to 2.0, 0.2 to 1.5, 0.2 to 1.0, 0.25 to 2.0, 0.25 to 1.5, 0.25 to 1.0, 0.3 to 2.0, 0.3 to 1.5, or 0.3 to 1.0.

The amount of the curing agent added is based on the epoxy equivalent (C) to the epoxy resin₁) Active hydrogen equivalent of amine-based curing agent (C)₂) Ratio of (C)₂/C₁) To be determined. The ratio (C)₂/C₁) Preferably 0.1 or more, more preferably 0.2 or more, and further preferably 0.3 or more. In addition, ratio (C)₂/C₁) Preferably 2.5 or less, more preferably 2.0 or less, and further preferably 1.5 or less. I.e. ratio (C)₂/C₁) For example, 0.1 to 2.5, 0.1 to 2.0, 0.1 to 1.5, 0.2 to 2.5, 0.2 to 2.0, 0.2 to 1.5, 0.3 to 2.5, 0.3 to 2.0, or 0.3 to 1.5.

The phosphate compound has 1 or more hydroxyl groups in 1 molecule. In the present embodiment, it is considered that the phosphate ester compound has an effect of improving the dispersibility and adhesion between the resin component and the inorganic filler and improving the wet-resistant adhesion by the presence of the hydroxyl group in the molecule. The phosphate ester compound is considered to have an effect of suppressing a decrease in moisture-proof insulation properties due to oxidation deterioration of the insulating layer by trapping OH radicals generated under conditions of high-temperature and high-humidity environments and application of a dc voltage.

The number of hydroxyl groups in the phosphate ester compound is more preferably 1 to 2 per molecule, and still more preferably 2 per molecule.

The phosphate compound preferably has a hydroxyl group directly bonded to a phosphorus atom. Further, the phosphate ester compound more preferably has 2 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 further improvement in adhesion between the inorganic filler and the resin component. The polyether chain is preferably a polyoxyalkylene chain, and more preferably a polyoxyalkylene chain having an alkylene group selected from the group consisting of an ethylene group and a propylene group.

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

The number average molecular weight of the phosphate ester compound is preferably 200 or more, more preferably 400 or more. 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 represents a value determined by volume exclusion chromatography (GPC). That is, the number average molecular weight of the phosphate ester compound is, for example, 200 to 2000, 200 to 1000, 400 to 2000 or 400 to 1000.

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

[ chemical formula 1 ]

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

The content of the phosphate ester compound in the insulating resin composition is, for example, 0.05 mass% or more, preferably 0.1 mass% or more, based on the total amount of the organic material and the inorganic filler. This can more significantly achieve the above-described effects of the phosphate ester compound. The content of the phosphate ester compound in the insulating resin composition is, for example, 0.4% by mass or less, preferably 0.3% by mass or less, based on the total amount of the organic material and the inorganic filler. Thus, the following tendency is exhibited: the deterioration of the moisture-resistant insulating property and the moisture-resistant bonding property due to the moisture absorption and hydrolysis of the phosphate compound itself is suppressed, and the heat cycle resistance of the circuit member is further improved. That is, the content of the phosphate ester compound in the insulating resin composition is, for example, 0.05 to 0.4 mass%, 0.05 to 0.3 mass%, 0.1 to 0.4 mass%, or 0.1 to 0.3 mass% based on the total amount of the organic material and the inorganic filler.

The heavy metal deactivator may be, for example, a substance capable of chelating and trapping metal ions (for example, copper ions) in the insulating resin composition or a cured product thereof.

As the heavy metal deactivator, for example, nitrogen-containing deactivators such as hydrazine-based heavy metal deactivators and triazole-based heavy metal deactivators can be preferably used.

Examples of the heavy metal deactivator include: dodecanedioic acid bis [ N2- (2-hydroxybenzoyl) hydrazide ] (product name "CDA-6" manufactured by ADEKA), N- (2H-1, 2, 4-triazol-5-yl) salicylamide (product name "CDA-1" manufactured by ADEKA), N' -bis { 3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionyl } hydrazine (product name "CDA-10" manufactured by ADEKA), 3-amino-1, 2, 4-triazole and the like.

The heavy metal deactivator is preferably a substance having a low melting point from the viewpoint of improving dispersibility in the insulating resin composition. The melting point of the heavy metal deactivator may be, for example, 250 ℃ or lower, preferably 240 ℃ or lower, more preferably 230 ℃ or lower, and still more preferably 220 ℃ or lower.

The content of the heavy metal deactivator in the insulating resin composition is, for example, 0.01 mass% or more, preferably 0.03 mass% or more, and more preferably 0.05 mass% or more, based on the total amount of the organic material and the inorganic filler. This makes it possible to more significantly obtain the above-described effects of the heavy metal deactivator and to further improve the wet adhesion resistance. The content of the heavy metal deactivator in the insulating resin composition is, for example, 0.5% by mass or less, preferably 0.3% by mass or less, and more preferably 0.2% by mass or less, based on the total amount of the organic material and the inorganic filler. This tends to further improve the coatability of the insulating resin composition, and further improve the moisture-resistant insulating property and reliability of the circuit board. That is, the content of the heavy metal deactivator in the insulating resin composition is, for example, 0.01 to 0.5 mass%, 0.01 to 0.3 mass%, 0.01 to 0.2 mass%, 0.03 to 0.5 mass%, 0.03 to 0.3 mass%, 0.03 to 0.2 mass%, 0.05 to 0.5 mass%, 0.05 to 0.3 mass%, or 0.05 to 0.2 mass% based on the total amount of the organic material and the inorganic filler.

The insulating resin composition may further contain other components than the above as an organic material.

Examples of the other components include a leveling agent, an antifoaming agent, a wetting agent, a stabilizer, and a curing accelerator, which are surface modifications of a coupling agent and the like.

The inorganic filler is not particularly limited, and a known inorganic filler used in applications requiring insulation properties and thermal conductivity can be used without particular limitation.

Examples of the inorganic filler include: and an inorganic filler composed of alumina, silica, aluminum nitride, silicon nitride, boron nitride, or the like.

The inorganic filler is preferably an inorganic material selected from the group consisting of alumina, silica, silicon nitride, and boron nitride as a main component, from the viewpoint of suppressing a decrease in moisture-resistant insulation properties due to hydrolysis of the inorganic material. 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 further 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, the aluminum nitride may be hydrolyzed under a high-temperature and high-humidity environment, and the insulation properties may be lowered. 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 still 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 alumina, silica, silicon nitride, and boron nitride as a main component, the reduction in insulation properties due to the hydrolysis can be significantly suppressed.

The shape of the inorganic filler is not particularly limited, and may be in the form of particles, scales, polygonal shapes, or the like, and is preferably in the form of particles.

The maximum particle diameter of the inorganic filler is, for example, 250 μm or less, preferably 200 μm or less, and more preferably 150 μm or less. This tends to further improve the insulation properties of the cured product. The minimum particle size of the inorganic filler is not particularly limited, and is, for example, 0.05 μm or more, preferably 0.1 μm or more, from the viewpoint of further improving the thermal conductivity. In the present specification, the maximum particle diameter and the minimum particle diameter of the inorganic filler represent the d90 diameter and the d10 diameter in the volume-based particle size distribution, and they can be measured by a laser diffraction particle size distribution measuring apparatus.

The inorganic filler may contain 2 or more inorganic fillers having different average particle diameters. For example, the inorganic filler may contain a first inorganic filler having an average particle diameter of 25 μm or more and a second inorganic filler having an average particle diameter of 4 μm or less. With such an inorganic filler, the second inorganic filler is filled in the gap of the first inorganic filler, whereby the filling density is increased and the thermal conductivity of the cured product is further improved. In the present specification, the average particle diameter of the inorganic filler represents the d50 diameter in the volume-based particle size distribution. The volume-based particle size distribution was measured by a laser diffraction particle size distribution measuring apparatus.

The average particle diameter of the first inorganic filler is preferably 30 μm or more, more preferably 40 μm or more. The average particle diameter of the first inorganic filler is, for example, 200 μm or less, preferably 150 μm or less. When the average particle diameter is such, the above-described effect can be more remarkably obtained. That is, the average particle size of the first inorganic filler is, for example, 30 to 200. mu.m, 30 to 150. mu.m, 40 to 200. mu.m, or 40 to 150. mu.m.

The average particle diameter of the second inorganic filler is preferably 3.5 μm or less, and more preferably 3 μm or less. The average particle diameter of the second inorganic filler is, for example, 0.05 μm or more, preferably 0.1 μm or more. Thereby, the above-described effects can be more remarkably obtained. That is, the average particle size of the second inorganic filler is, for example, 0.05 to 3.5. mu.m, 0.05 to 3 μm, 0.1 to 3.5. mu.m, or 0.1 to 3 μm.

In addition, the inorganic filler may further contain a third inorganic filler having an average particle diameter of more than 4 μm and less than 25 μm. By such a third inorganic filler, the above-described effects can be more remarkably obtained.

The content of the inorganic filler in the insulating resin composition is 50 mass% or more, preferably 55 mass% or more, and more preferably 60 mass% or more based on the total amount of the insulating resin composition. This tends to significantly improve the wet adhesion resistance and thermal conductivity of the cured product. The content of the inorganic filler in the insulating resin composition is 95% by mass or less, preferably 90% by mass or less, and more preferably 85% by mass or less, based on the total amount of the insulating resin composition. This makes it easier to obtain a cured product having improved adhesiveness and insulation properties under high-temperature and high-humidity environments, and tends to improve the heat cycle resistance of the circuit board. That is, the content of the inorganic filler in the insulating resin composition is, for example, 50 to 95 mass%, 50 to 90 mass%, 50 to 85 mass%, 55 to 95 mass%, 55 to 90 mass%, 55 to 85 mass%, 60 to 95 mass%, 60 to 90 mass%, or 60 to 85 mass% based on the total amount of the insulating resin composition.

(cured insulating resin)

The insulating resin cured product according to the present embodiment is a cured product of the insulating resin composition. The insulating resin cured product can form an insulating layer having both excellent adhesion and insulation properties under a high-temperature and high-humidity environment and a low elastic modulus.

The storage modulus at 85 ℃ of the cured product of the insulating resin is preferably 500MPa or less, more preferably 400MPa or less, still more preferably 300MPa or less, and still more preferably 200MPa or less. By using the insulating resin cured product, a circuit board having more excellent heat cycle resistance can be realized.

The method for producing the cured insulating resin is not particularly limited. For example, the insulating resin cured product can be produced by heat-treating and curing an insulating resin composition. The heat treatment may be performed in 1 stage or 2 stages. By performing the heat treatment in 2 stages, an insulating resin cured product can be formed via the prepreg of the insulating resin composition.

In the case of the heat treatment in 1 stage, the heat treatment temperature is, for example, 150 to 250 ℃, preferably 160 to 240 ℃, and the heat treatment time is, for example, 2 to 15 hours, preferably 2.5 to 10 hours.

In the case of performing the heat treatment in 2 stages, the temperature of the heat treatment in the 1 st stage is, for example, 60 to 130 ℃, preferably 65 to 100 ℃, and the time of the heat treatment is, for example, 0.3 to 8 hours, preferably 0.5 to 5 hours. The temperature of the heat treatment in the 2 nd stage is, for example, 150 to 250 ℃ and preferably 160 to 240 ℃, and the time of the heat treatment is, for example, 2 to 15 hours and preferably 2.5 to 10 hours.

By performing heat treatment while maintaining the insulating resin composition or the semi-cured product thereof in a predetermined shape, an insulating resin cured product having a predetermined shape can be obtained. For example, a layered cured insulating resin can be formed on a metal plate by coating an insulating resin composition on the metal plate, and laminating and curing a metal foil as necessary.

(laminate)

The laminate according to the present embodiment includes: a metal plate; an insulating resin cured product disposed on the metal plate; and a metal foil disposed on the cured insulating resin. In the laminate according to the present embodiment, the metal plate and the metal foil can be isolated from each other by the cured insulating resin, and the cured insulating resin can function as an insulating layer.

The metal material constituting the metal plate is not particularly limited, and examples thereof include: aluminum, aluminum alloys, copper alloys, iron, stainless steel, and the like. The metal plate may be made of one metal material, or may be made of two or more metal materials. The metal plate may have a single-layer structure or a multilayer structure.

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

The metal material constituting the metal foil is not particularly limited, and examples thereof include copper, aluminum, and nickel. The metal foil may be made of one metal material, or may be made of two or more metal materials. 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 1mm from the viewpoint of suitability for the production of a circuit board.

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

The method for producing the laminate is not particularly limited. For example, the laminate can be produced by a method including the steps of: a step of coating an insulating resin composition on a metal plate and curing or semi-curing the resin composition; and a step of bonding a metal foil to the cured or semi-cured insulating resin composition (i.e., the insulating resin cured product or semi-cured product). The method may further include a step of curing the semi-cured product of the insulating resin composition. The metal foil can be joined by a method such as a roll lamination method or a lamination pressing method.

The laminate can be produced by a method including the steps of: a step of coating an insulating resin composition on a metal foil and curing or semi-curing the resin composition; and a step of bonding a metal plate to the cured or semi-cured insulating resin composition (i.e., the insulating resin cured product or semi-cured product). The method may further include a step of curing the semi-cured product of the insulating resin composition.

Fig. 1 is a sectional view showing a preferred embodiment of the laminate. The laminate 10 shown in fig. 1 includes: a metal plate 1; a metal foil 3; and an insulating layer 2 made of an insulating resin cured product and present between the metal plate 1 and the metal foil 3. The circuit board can be easily formed by processing the metal foil 3 of the laminate 10 into a predetermined pattern.

(Circuit Board)

The circuit board according to the present embodiment includes: a metal plate; an insulating resin cured product disposed on the metal plate; and a circuit portion disposed on the cured insulating resin. In the circuit board according to the present embodiment, the metal plate and the circuit portion can be isolated by the cured insulating resin, and the cured insulating resin can function as an insulating layer.

The metal plate may be the same as the metal plate in the laminate.

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

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

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

In the circuit board, the volume resistivity between the circuit part and the metal plate at 85 ℃ 85% RH after a voltage of 500V DC is continuously applied between the circuit part and the metal plate for 1000 hours in an environment of 85 ℃ 85% RH is preferably 1.0X 10⁹Omega cm or more, more preferably 5.0X 10⁹Omega cm or more. This circuit board can be a circuit board having particularly excellent moisture-proof insulating properties.

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

Fig. 2 is a cross-sectional view showing a preferred embodiment of the circuit board. The circuit board 20 shown in fig. 2 includes: a metal plate 1; a circuit section 4; and an insulating layer 2 made of an insulating cured resin material and present between the metal plate 1 and the circuit portion 4. The circuit board 20 may be obtained by processing the metal foil 3 of the laminate 10 into the circuit portion 4, for example.

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

Examples

< example 1 >

(Synthesis of phosphate ester Compound)

90g of methoxypropanol and 0.3g of potassium hydroxide were charged into an autoclave, the autoclave was purged with nitrogen, heated to 100 ℃ and then charged with 1914g of propylene oxide over 3 hours while stirring. And then stirring at 90-100 ℃ for 30 min, cooling, neutralizing with a phosphoric acid aqueous solution, dehydrating, and filtering to obtain the polypropylene glycol monomethyl ether.

400g of polypropylene glycol monomethyl ether, 100g of succinic anhydride and 2g of tetramethylammonium chloride were charged into an autoclave, and after replacement with nitrogen, the temperature was raised to 100 ℃ and 58g of propylene oxide was introduced thereinto with stirring. Stirring was carried out at 100 ℃ for 2 hours to give 558g of an oil.

1.8g of water was added to 558g of the above oily substance, and 14g of phosphorus pentoxide was added in small amounts over about 30 minutes while keeping the temperature at 50 ℃. Then, the mixture was stirred at the same temperature for about 1 hour to obtain a phosphate ester compound (P-1) having a polyether chain and a hydroxyl group bonded to a phosphorus atom.

The number average molecular weight of the obtained phosphate was measured by volume exclusion chromatography and found to be 510. Tetrahydrofuran was used for the mobile phase, and the flow rate was measured by an RI detector (refractive index) at 1.0ml/min, and the value was obtained in terms of polystyrene. Results of volume exclusion chromatography for hydroxyl groups bound to phosphorus atoms, combined with the resulting sample, and based onResults of LC/MS mass analysis based on¹H-NMR and¹³the structural analysis result by C-NMR was confirmed.

(preparation of insulating resin composition)

To 2.2 parts by mass of bisphenol A/F type epoxy resin ("YD-6020" manufactured by Mitsubishi chemical corporation), 6.7 parts by mass of bisphenol A type water-added epoxy resin ("YX-8000") 2.4 parts by mass of aliphatic amine ("D-400" manufactured by Huntsman corporation), 1.6 parts by mass of aliphatic amine ("D-2000" manufactured by Huntsman corporation, amine equivalent 1040), and 30.5 parts by mass of alumina ("DAS 45" manufactured by Denka corporation, maximum particle diameter of 70 μm, average particle diameter of 45 μm were added, 30.5 parts by mass of alumina (DAS 10, manufactured by Denka, 21 μm in maximum particle size, 10 μm in average particle size), 26.1 parts by mass of alumina (AA 2, manufactured by Sumitomo chemical Co., Ltd., 5 μm in maximum particle size, 2 μm in average particle size), 0.1 part by mass of a heavy metal deactivator (CDA-6, manufactured by ADEKA, melting point 212 ℃ C.), and 0.2 part by mass of a phosphate ester compound (P-1). The resulting mixture was kneaded by a planetary Mixer (Mixer, "あわとり Tailang AR-310", rotation speed 2000rpm) to prepare an insulating resin composition.

(production of Circuit Board)

An aluminum plate having a thickness of 1.5mm (manufactured by Tianye aluminum Co., Ltd. "A10501.5mm thick") was coated with the insulating resin composition, and dried at 120 ℃ for 15 minutes to be in a B-stage (semi-cured) state. The coating amount of the insulating resin composition was adjusted so that the thickness of the insulating layer after curing became 100 μm.

Then, a copper foil having a thickness of 70 μm (manufactured by kohe electric company, "electrolytic copper foil having a thickness of 70 μm") was placed on the prepreg of the insulating resin composition, and the prepreg was cured by heat treatment at 180 ℃ for 6 hours in a laminated state by a hot press method to obtain a laminate.

Next, after masking the predetermined position with a resist, the copper foil is etched using a sulfuric acid-hydrogen peroxide mixed solution as an etching solution. The resist was removed, and the substrate was washed and dried to obtain a circuit board having a circuit portion formed of a copper foil.

< example 2 >

The amount of addition of "YD-6020" was changed to 6.9 parts by mass, the amount of addition of "YX 8000" was changed to 20.7 parts by mass, the amount of addition of "D400" was changed to 7.2 parts by mass, and the amount of addition of "D2000" was changed to 4.8 parts by mass. In addition, 60.4 parts by mass of boron nitride ("XGP" manufactured by Denka corporation, maximum particle diameter of 90 μm and average particle diameter of 30 μm) was used in place of alumina ("DAS 45", "DAS 10" and "AA 2"). In the same manner as in example 1 except for the above, an insulating resin composition and a circuit board were obtained.

< example 3 >

The amount of addition of "YD-6020" was changed to 1.2 parts by mass, the amount of addition of "YX 8000" was changed to 3.6 parts by mass, the amount of addition of "D400" was changed to 1.2 parts by mass, the amount of addition of "D2000" was changed to 0.8 parts by mass, the amount of addition of "DAS 45" was changed to 32.6 parts by mass, the amount of addition of "DAS 10" was changed to 32.6 parts by mass, and the amount of addition of "AA 2" was changed to 28 parts by mass. In the same manner as in example 1 except for the above, an insulating resin composition and a circuit board were obtained.

< example 4 >

An insulating resin composition and a circuit board were obtained in the same manner as in example 1, except that the amount of the heavy metal deactivator added was changed to 0.4 parts by mass.

< example 5 >

An insulating resin composition and a circuit board were obtained in the same manner as in example 1, except that the amount of the heavy metal deactivator added was changed to 0.02 parts by mass.

< example 6 >

An insulating resin composition and a circuit board were obtained in the same manner as in example 1, except that the amount of addition of "D400" was changed to 3.2 parts by mass and the amount of addition of "D2000" was changed to 0.8 part by mass.

< example 7 >

As the heavy metal deactivator, 0.1 part by mass of 3-amino-1, 2, 4-triazole (melting point: 159 ℃ C.) was used in place of "CDA-6". In the same manner as in example 1 except for the above, an insulating resin composition and a circuit board were obtained.

< example 8 >

As the heavy metal deactivator, 0.1 part by mass of "CDA-10" (manufactured by ADEKA, melting point 227 ℃ C.) was used in place of "CDA-6". In the same manner as in example 1 except for the above, an insulating resin composition and a circuit board were obtained.

< example 9 >

As the heavy metal deactivator, 0.1 part by mass of "CDA-1" (manufactured by ADEKA, melting point 320 ℃ C.) was used in place of "CDA-6". In the same manner as in example 1 except for the above, an insulating resin composition and a circuit board were obtained.

< comparative example 1 >

An insulating resin composition and a circuit board were obtained in the same manner as in example 1, except that the heavy metal deactivator was not added.

< comparative example 2 >

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

< comparative example 3 >

The amount of addition of "YD-6020" was changed to 8.9 parts by mass, the amount of addition of "YX 8000" was changed to 27 parts by mass, the amount of addition of "D400" was changed to 9.7 parts by mass, and the amount of addition of "D2000" was changed to 6.4 parts by mass. In addition, 48.0 parts by mass of boron nitride ("XGP" manufactured by Denka corporation, maximum particle diameter of 90 μm and average particle diameter of 30 μm) was used in place of alumina ("DAS 45", "DAS 10" and "AA 2"). In the same manner as in example 1 except for the above, an insulating resin composition and a circuit board were obtained.

< comparative example 4 >

The amount of addition of "YD-6020" was changed to 0.8 parts by mass, the amount of addition of "YX 8000" was changed to 2.3 parts by mass, the amount of addition of "D400" was changed to 0.8 parts by mass, the amount of addition of "D2000" was changed to 0.6 parts by mass, the amount of addition of "DAS 45" was changed to 33.4 parts by mass, the amount of addition of "DAS 10" was changed to 33.4 parts by mass, and the amount of addition of "AA 2" was changed to 28.6 parts by mass. In the same manner as in example 1 except for the above, an insulating resin composition and a circuit board were obtained.

< comparative example 5 >

An insulating resin composition and a circuit board were obtained in the same manner as in example 1, except that 0.2 parts by mass of a phosphate compound having no hydroxyl group in the molecule ("JC-224" manufactured by North City chemical industries, Ltd.) was used in place of the phosphate compound (P-1).

The compounding ratios of the insulating resin compositions of examples and comparative examples are shown in tables 1 and 2. The maximum particle size and the average particle size of the inorganic filler used in examples and comparative examples were determined by the following methods.

[ measurement of inorganic Filler ]

The measurement was carried out by using a "laser diffraction particle size distribution measuring apparatus SALD-200" manufactured by Shimadzu corporation. Specifically, 50cc of pure water and 5g of an inorganic filler were added to a glass beaker, stirred with a spatula, and then subjected to a dispersion treatment for 10 minutes with an ultrasonic cleaner. The dispersion of the inorganic filler was added drop by drop to the sampling portion of the apparatus with a dropper, and was waited until it became stable enough to measure the absorbance. The measurement was performed at the time point when the absorbance became stable. In the laser diffraction particle size distribution measuring apparatus, the particle size distribution is calculated from data of the light intensity distribution of diffracted/scattered light by particles detected by a sensor. The maximum particle diameter was d90, and the average particle diameter was d 50.

The insulating resin compositions obtained in examples and comparative examples and the circuit boards obtained in example 1 were evaluated by the following methods. The results are shown in tables 1 and 2.

[ measurement of storage modulus of cured insulating resin ]

The measurement was carried out using "RSA-III" manufactured by TA Instrument Co. Specifically, the insulating resin composition was coated on a PET film so that the thickness after curing became 200 μm, and cured by heating at 180 ℃ for 6 hours to prepare an insulating resin cured product. The insulating resin cured product was processed to a width of 4mm and a length of 5cm, thereby obtaining a measurement sample. The obtained sample was used, and the storage modulus was measured by raising the temperature from-50 ℃ to 150 ℃ at a rate of 7 ℃/min, with the measurement frequency being 1 Hz. From the measurement results, the storage modulus at 85 ℃ was determined.

[ measurement of thermal conductivity of cured insulating resin ]

The thermal conductivity is calculated from the thermal diffusivity, specific gravity and specific heat. Specifically, the thermal conductivity was first determined by a laser scintillation method using a measurement sample obtained by processing an insulating resin cured product to a width of 10mm × a length of 10mm × a thickness of 1 mm. A xenon flash analyzer (LFA 447 NanoFlash, product of NETZSCH) was used as a measuring device. Specific gravity was measured by the archimedes method. The specific heat was measured by using a differential scanning calorimeter ("Q2000" manufactured by TA Instruments) and raising the temperature from room temperature to 300 ℃ at a temperature raising rate of 10 ℃ per minute under a nitrogen atmosphere.

[ evaluation of moisture resistance insulation ]

For the laminates obtained in examples and comparative examples, a circular electrode having a diameter of 20mm was produced by etching a copper foil, and this was used as a measurement sample. Then, a voltage of 500V DC was applied between the circular electrode and the metal plate at 85 ℃ and 85% RH for 1000 hours. The volume resistivity between the circular electrode and the metal plate at 85 ℃ and 85% RH was measured for the measurement sample after voltage application. The measurement was performed using an insulation deterioration system ("SIR 13" manufactured by nan guo chemical company).

[ evaluation of Wet-resistant joining Properties ]

For the laminates obtained in examples and comparative examples, a circular electrode having a diameter of 20mm was produced by etching a copper foil, and this was used as a measurement sample. Subsequently, a DC voltage of 500V was applied between the circular electrode and the metal plate at 85 ℃ and 85% RH for 1500 hours. The case where swelling occurred in the electrode portion after 1000 hours from the start of voltage application was evaluated as C, the case where swelling occurred in the electrode portion after 1000 to 1250 hours was evaluated as a, and the case where swelling did not occur in the electrode portion even after 1250 hours was evaluated as AA. The presence or absence of swelling was visually confirmed.

[ evaluation of Heat cycle resistance ]

For the laminates obtained in examples and comparative examples, electrodes were produced by etching copper foil, and the electrodes were used as measurement samples. A chip resistor having a chip size of 2.0mm X1.25 mm was soldered between electrodes of a circuit board, and a heat cycle test was carried out 2000 times in accordance with JIS-C-0025 temperature variation test method with-40 ℃ for 15 minutes to +150 ℃ for 15 minutes as1 cycle. The total number of chip resistors was 20 in each of the examples and comparative examples. After the test, the presence or absence of cracking in the solder portion was observed with a microscope. The cracking of the solder portion was evaluated as C when 30% or more, as a when 10% or more and less than 30% and as AA when less than 10% occurred.

[ TABLE 1 ]

[ TABLE 2 ]

As shown in tables 1 and 2, it was confirmed that in the examples, an insulating layer having both a low elastic modulus and a high thermal conductivity could be formed, and a circuit board having excellent moisture-resistant insulating properties, moisture-resistant bonding properties, and heat cycle resistance was obtained.

Industrial applicability

According to the present invention, an insulating layer having both excellent adhesion and insulation properties under a high-temperature and high-humidity environment and a low elastic modulus can be formed. Further, according to the present invention, a circuit board which includes the insulating layer and is excellent in moisture-resistant insulating properties, thermal conductivity, and heat cycle resistance can be obtained. Therefore, the present invention can be suitably used in fields requiring heat cycle resistance, moisture resistance insulation, heat dissipation, and the like (for example, a circuit board for an in-vehicle charger).

Description of the reference numerals

1 … metal plate, 2 … insulating layer, 3 … metal foil, 4 … circuit part, 10 … laminated body, 20 … circuit board.

Claims

1. An insulating resin composition comprising an organic material and an inorganic filler,

the organic material contains an epoxy resin, an amine-based curing agent, a phosphate ester compound having 1 or more hydroxyl groups in 1 molecule, and a heavy metal deactivator,

the content of the inorganic filler is 50 to 95 mass%.

2. The insulating resin composition according to claim 1, wherein the amine-based curing agent comprises:

a first amine-based curing agent having an amine equivalent of 300 or less; and

a second amine curing agent having an amine equivalent of 800 or more.

3. The insulating resin composition according to claim 1 or 2, wherein the content of the phosphate ester compound is 0.05 to 0.4% by mass based on the total amount of the organic material and the inorganic filler.

4. The insulating resin composition according to any one of claims 1 to 3, wherein the content of the heavy metal deactivator is 0.01 to 0.5% by mass based on the total amount of the organic material and the inorganic filler.

5. The insulating resin composition according to any one of claims 1 to 4, wherein the melting point of the heavy metal deactivator is 250 ℃ or lower.

6. An insulating resin cured product which is a cured product of the insulating resin composition according to any one of claims 1 to 5.

7. The cured insulating resin according to claim 6, which has a storage modulus at 85 ℃ of 500MPa or less.

8. A laminate comprising:

a metal plate;

the cured insulating resin according to claim 6 or 7 disposed on the metal plate; and

a metal foil disposed on the cured insulating resin.

9. A circuit board, comprising:

a metal plate;

a circuit portion disposed on the cured insulating resin.