JP7265474B2 - Curable resin composition, adhesive, adhesive film, coverlay film, and flexible copper-clad laminate - Google Patents

Description

TECHNICAL FIELD The present invention relates to a curable resin composition capable of obtaining a cured product excellent in high-temperature long-term heat resistance, moisture absorption reflow resistance, and plating resistance. The present invention also provides an adhesive containing the curable resin composition, an adhesive film using the curable resin composition, and a coverlay film and flexible copper clad film having a cured product of the curable resin composition. Regarding laminates.

Curable resins such as epoxy resins, which have low shrinkage and excellent adhesiveness, insulation, and chemical resistance, are used in many industrial products. Particularly in applications for electronic devices, curable resin compositions that give good results in solder reflow tests for short-term heat resistance and thermal cycle tests for repeated heat resistance are often used.

In recent years, automotive electric control units (ECUs) and power devices using SiC and GaN have attracted attention. However, heat resistance when continuously exposed to high temperatures for a long period of time (high-temperature long-term heat resistance) is required.

As a curing agent used in a curable resin composition, for example, Patent Document 1 discloses a curing agent obtained by reacting an acid anhydride component composed of an aromatic tetracarboxylic dianhydride and a diamine component composed of an aromatic diamine. A polyimide is disclosed. In Patent Document 1, by using the polyimide, it is possible to form an adhesive layer that does not reduce the adhesive strength between the wiring layer and the coverlay film even in a usage environment in which it is repeatedly exposed to high temperatures. However, it is difficult for conventional curable resin compositions using such polyimides to maintain adhesive strength under severer temperature environments. In addition, there has been a demand for a curable resin composition that exhibits excellent moisture absorption reflow resistance.

JP 2017-145344 A

An object of the present invention is to provide a curable resin composition capable of obtaining a cured product excellent in high-temperature long-term heat resistance, moisture absorption reflow resistance, and plating resistance. The present invention also provides an adhesive containing the curable resin composition, an adhesive film using the curable resin composition, and a coverlay film and flexible copper clad film having a cured product of the curable resin composition. An object of the present invention is to provide a laminate.

The present invention is a curable resin composition containing a curable resin, an imide oligomer having an imide skeleton in the main chain and a crosslinkable functional group at the terminal, and an ion scavenger.
The present invention will be described in detail below.

The present inventors have found that the reasons why conventional curable resin compositions are inferior in high-temperature long-term heat resistance and moisture absorption reflow resistance in severe temperature environments are the raw materials of the curable resin composition, printed wiring boards, etc. It was thought to be in specific ions such as chloride ions derived from the copper foil cleaning solution used.
Therefore, the present inventors have found that by adding an ion scavenger to a curable resin composition containing a curable resin and an imide oligomer having a specific structure, curing that is excellent in high-temperature long-term heat resistance and moisture absorption reflow resistance The inventors have found that the object can be obtained, and have completed the present invention.
In addition, the curable resin composition of the present invention is also excellent in initial adhesiveness and plating resistance.

The curable resin composition of the present invention contains an ion scavenger.
By containing the ion scavenger, the curable resin composition of the present invention provides a cured product with excellent high-temperature long-term heat resistance and moisture absorption reflow resistance.
In this specification, the above-mentioned "ion scavenger" means an organic compound or an inorganic compound having a function of adsorbing, capturing, or exchanging ions.

The ion trapping agent is preferably an ion exchanger.
Examples of the ion exchanger include zirconium-based compounds, antimony-based compounds, magnesium-aluminum-based compounds, antimony-bismuth-based compounds, and zirconium-bismuth-based compounds. Among them, an anion exchanger or amphoteric ion exchanger is preferable, an anion exchanger is more preferable, and a magnesium aluminum-based compound which is an anion exchanger is even more preferable.
The above ion trapping agents may be used alone, or two or more of them may be used in combination.

From the viewpoint of ion trapping ability, the ion trapping agent is preferably particles having an average particle diameter of 10 μm or less. When the ion scavenger is particles having an average particle size of 10 μm or less, the obtained cured product of the curable resin composition is excellent in high-temperature long-term heat resistance and moisture absorption reflow resistance. The ion scavenger is more preferably particles with an average particle size of 6 μm or less, and more preferably particles with an average particle size of 2 μm or less.
Although there is no particular lower limit for the average particle size of the ion scavenger, the ion scavenger is preferably particles having an average particle size of 0.01 μm or more from the viewpoint of thickening or the like, and is preferably 0.1 μm or more. are more preferred.
The average particle size of the ion scavenger and the inorganic filler and flow control agent described later is obtained by dispersing particles in a solvent (water, organic solvent, etc.) using NICOMP 380ZLS (manufactured by PARTICLE SIZING SYSTEMS). can be measured by

The content of the ion trapping agent has a preferable lower limit of 0.1 parts by weight and a preferable upper limit of 200 parts by weight with respect to a total of 100 parts by weight of the curable resin and the imide oligomer. When the content of the ion scavenger is within this range, the resulting cured product of the curable resin composition is excellent in high temperature long-term heat resistance and moisture absorption reflow resistance. A more preferable lower limit of the content of the ion scavenger is 1 part by weight, a more preferable upper limit is 50 parts by weight, and a further preferable upper limit is 20 parts by weight.

The curable resin composition of the present invention contains an imide oligomer having an imide skeleton in the main chain and a crosslinkable functional group at the terminal (hereinafter also referred to as "the imide oligomer according to the present invention"). The imide oligomer according to the present invention is excellent in reactivity and compatibility with curable resins such as epoxy resins. By containing the imide oligomer according to the present invention, the curable resin composition of the present invention provides a cured product that is excellent in mechanical strength at high temperatures and long-term heat resistance at high temperatures.

The crosslinkable functional group is preferably a functional group capable of reacting with an epoxy group.
Specific examples of the crosslinkable functional groups include amino groups, carboxyl groups, acid anhydride groups, phenolic hydroxyl groups, unsaturated groups, active ester groups, and maleimide groups. Among them, at least one of an acid anhydride group and a phenolic hydroxyl group is more preferable. The imide oligomer according to the present invention may have the crosslinkable functional group at one end or at both ends. When the above-described crosslinkable functional groups are present at both ends, the resulting curable resin composition has a higher glass transition temperature after curing due to increased crosslink density. On the other hand, when having the crosslinkable functional group at one end, the functional group equivalent increases, and the content of the imide oligomer according to the present invention in the curable resin composition can be increased. The cured product has excellent long-term heat resistance at high temperatures.

The imide oligomer according to the present invention preferably has a structure represented by the following formula (1-1) or the following formula (1-2) as the structure containing the crosslinkable functional group. By having a structure represented by the following formula (1-1) or the following formula (1-2), the imide oligomer according to the present invention is excellent in reactivity and compatibility with curable resins such as epoxy resins. becomes.

In the formulas (1-1) and (1-2), A is a tetravalent group represented by the following formula (2-1) or the following formula (2-2), and the formula (1-1) Among them, B is a divalent group represented by the following formula (3-1) or the following formula (3-2), and in formula (1-2), Ar is an optionally substituted divalent is an aromatic group of

In formulas (2-1) and (2-2), * is a bonding position, and in formula (2-1), Z is a bond, an oxygen atom, or optionally substituted, a bond It is a divalent hydrocarbon group optionally having an oxygen atom at its position. The hydrogen atoms of the aromatic rings in formulas (2-1) and (2-2) may be substituted.

In formulas (3-1) and (3-2), * is a bonding position, and in formula (3-1), Y is a bond, an oxygen atom, or an optionally substituted divalent is a hydrocarbon group of The hydrogen atoms of the aromatic rings in formulas (3-1) and (3-2) may be substituted.

In addition, the imide oligomer according to the present invention lowers the glass transition temperature after curing and may contaminate the adherend and cause adhesion failure. is preferred.

A preferable upper limit of the number average molecular weight of the imide oligomer according to the present invention is 4,000. When the number average molecular weight is 4000 or less, the cured product of the curable resin composition to be obtained is excellent in high-temperature long-term heat resistance. A more preferable upper limit of the number average molecular weight of the imide oligomer according to the present invention is 3,400, and a more preferable upper limit is 2,800.
In particular, the number average molecular weight of the imide oligomer according to the present invention is preferably 900 or more and 4000 or less when it has a structure represented by the above formula (1-1), and is represented by the above formula (1-2). In the case of having a structure with a A more preferable lower limit of the number average molecular weight in the case of having the structure represented by the above formula (1-1) is 950, and a more preferable lower limit is 1,000. A more preferable lower limit of the number average molecular weight in the case of having the structure represented by the above formula (1-2) is 580, and a more preferable lower limit is 600.
In addition, the above-mentioned "number average molecular weight" in this specification is a value measured by gel permeation chromatography (GPC) using tetrahydrofuran as a solvent and calculated by polystyrene conversion. Examples of the column used for measuring the polystyrene-equivalent number-average molecular weight by GPC include JAIGEL-2H-A (manufactured by Japan Analytical Industry Co., Ltd.).

Specifically, the imide oligomer according to the present invention is represented by the following formula (4-1), the following formula (4-2), the following formula (4-3), or the following formula (4-4). An imide oligomer or an imide oligomer represented by the following formula (5-1), (5-2), (5-3) or (5-4) below is preferable.

In formulas (4-1) to (4-4), A is a tetravalent group represented by formula (6-1) or formula (6-2) below, and formula (4-1), In formulas (4-3) and (4-4), A may be the same or different. In formulas (4-1) to (4-4), B is a divalent group represented by formula (7-1) or formula (7-2) below, and formula (4-3) and In formula (4-4), B may be the same or different. In formula (4-2), X is a hydrogen atom, a halogen atom, or an optionally substituted monovalent hydrocarbon group, and in formula (4-4), W is a hydrogen atom, a halogen atom , or an optionally substituted monovalent hydrocarbon group.

In the formulas (5-1) to (5-4), A is a tetravalent group represented by the following formula (6-1) or the following formula (6-2), the formula (5-3) and In formula (5-4), A may be the same or different. In formulas (5-1) to (5-4), R is a hydrogen atom, a halogen atom, or an optionally substituted monovalent hydrocarbon group, formula (5-1) and formula (5 -3), each R may be the same or different. In formula (5-2) and formula (5-4), W is a hydrogen atom, a halogen atom, or an optionally substituted monovalent hydrocarbon group, and formula (5-3) and formula ( In 5-4), B is a divalent group represented by the following formula (7-1) or the following formula (7-2).

In formulas (6-1) and (6-2), * is a bonding position, and in formula (6-1), Z is a bond, an oxygen atom, or optionally substituted, a bond It is a divalent hydrocarbon group optionally having an oxygen atom at its position. The hydrogen atoms of the aromatic rings in formulas (6-1) and (6-2) may be substituted.

In formulas (7-1) and (7-2), * is a bonding position, and in formula (7-1), Y is a bond, an oxygen atom, or an optionally substituted divalent is a hydrocarbon group of The hydrogen atoms of the aromatic rings in formulas (7-1) and (7-2) may be substituted.

Among the imide oligomers according to the present invention, as a method for producing an imide oligomer having a structure represented by the above formula (1-1), for example, an acid dianhydride represented by the following formula (8) and the following formula and a method of reacting with a diamine represented by (9).

In formula (8), A is the same tetravalent group as A in formula (1-1) above.

In formula (9), B is the same divalent group as B in formula (1-1) above, and R ¹ to R ⁴ are each independently a hydrogen atom or a monovalent hydrocarbon group. .

A specific example of the method for reacting the acid dianhydride represented by the above formula (8) with the diamine represented by the above formula (9) is shown below.
First, the diamine represented by the above formula (9) is dissolved in advance in a solvent (for example, N-methylpyrrolidone) in which the amic acid oligomer obtained by the reaction is soluble, and the resulting solution is added with the above formula (8). An acid dianhydride represented by is added and reacted to obtain an amic acid oligomer solution. Next, the solvent is removed by heating, pressure reduction, or the like, and the mixture is heated at about 200° C. or higher for 1 hour or longer to react the amic acid oligomer. By adjusting the molar ratio of the acid dianhydride represented by the above formula (8) and the diamine represented by the above formula (9), and the imidization conditions, it has a desired number average molecular weight, and both An imide oligomer having a structure represented by the above formula (1-1) at the end can be obtained.
Further, by replacing a part of the acid dianhydride represented by the above formula (8) with the acid anhydride represented by the following formula (10), it has a desired number average molecular weight and one end has the above An imide oligomer having a structure represented by the formula (1-1) and having a structure derived from an acid anhydride represented by the following formula (10) at the other end can be obtained. In this case, the acid dianhydride represented by the above formula (8) and the acid anhydride represented by the following formula (10) may be added simultaneously or separately.
Furthermore, by replacing a part of the diamine represented by the above formula (9) with a monoamine represented by the following formula (11), it has a desired number average molecular weight, and one end has the above formula (1-1) ) and having at the other end a structure derived from a monoamine represented by the following formula (11). In this case, the diamine represented by the above formula (9) and the monoamine represented by the following formula (11) may be added simultaneously or separately.

In formula (10), Ar is an optionally substituted divalent aromatic group.

式（１１）中、Ａｒは、置換されていてもよい１価の芳香族基であり、Ｒ^５及びＲ^６は、それぞれ独立に、水素原子又は１価の炭化水素基である。

In formula (11), Ar is an optionally substituted monovalent aromatic group, and R ⁵ and R ⁶ are each independently a hydrogen atom or a monovalent hydrocarbon group.

Among the imide oligomers according to the present invention, as a method for producing an imide oligomer having a structure represented by the above formula (1-2), for example, an acid dianhydride represented by the above formula (8) and the following formula Examples thereof include a method of reacting with a phenolic hydroxyl group-containing monoamine represented by (12).

In formula (12), Ar is an optionally substituted divalent aromatic group, and R ⁷ and R ⁸ are each independently a hydrogen atom or a monovalent hydrocarbon group.

A specific example of the method for reacting the acid dianhydride represented by the above formula (8) with the phenolic hydroxyl group-containing monoamine represented by the above formula (12) is shown below.
First, a phenolic hydroxyl group-containing monoamine represented by formula (12) is dissolved in advance in a solvent in which the amic acid oligomer obtained by the reaction is soluble (for example, N-methylpyrrolidone, etc.), and the resulting solution is added with the above formula An acid dianhydride represented by (8) is added and reacted to obtain an amic acid oligomer solution. Next, the solvent is removed by heating, pressure reduction, or the like, and the mixture is heated at about 200° C. or higher for 1 hour or longer to react the amic acid oligomer. By adjusting the molar ratio of the acid dianhydride represented by the above formula (8) and the phenolic hydroxyl group-containing monoamine represented by the above formula (12), and the imidization conditions, a desired number average molecular weight can be obtained. An imide oligomer having a structure represented by the above formula (1-2) at both ends can be obtained.
Further, by replacing part of the phenolic hydroxyl group-containing monoamine represented by the above formula (12) with the monoamine represented by the above formula (11), it has a desired number average molecular weight, and one end has the above formula An imide oligomer having a structure represented by (1-2) and having a structure derived from a monoamine represented by the above formula (11) at the other end can be obtained. In this case, the phenolic hydroxyl group-containing monoamine represented by the above formula (12) and the monoamine represented by the above formula (11) may be added simultaneously or separately.

Examples of the acid dianhydride represented by the above formula (8) include pyromellitic dianhydride, 3,3′-oxydiphthalic dianhydride, 3,4′-oxydiphthalic dianhydride, 4,4 '-oxydiphthalic dianhydride, 4,4'-(4,4'-isopropylidenediphenoxy)diphthalic anhydride, 4,4'-bis(2,3-dicarboxylphenoxy)diphenyl ether dianhydride, p -phenylene bis(trimellitate anhydride), 2,3,3',4'-biphenyltetracarboxylic dianhydride and the like.
Among them, aromatic acid dianhydrides having a melting point of 240° C. or less are preferable as the acid dianhydrides used as raw materials for the imide oligomer according to the present invention, since they are excellent in solubility and heat resistance. is more preferably 220° C. or less, more preferably 200° C. or less, 3,4′-oxydiphthalic dianhydride (melting point 180° C.), 4 ,4′-(4,4′-isopropylidenediphenoxy)diphthalic anhydride (melting point 190° C.) is particularly preferred.
In this specification, the "melting point" means a value measured as an endothermic peak temperature when the temperature is raised at 10°C/min using a differential scanning calorimeter. Examples of the differential scanning calorimeter include EXTEAR DSC6100 (manufactured by SII Nano Technology Co., Ltd.).

Examples of diamines represented by the above formula (9) include 3,3′-diaminodiphenylmethane, 3,4′-diaminodiphenylmethane, 4,4′-diaminodiphenylmethane, 3,3′-diaminodiphenyl ether, 3,4 '-diaminodiphenyl ether, 4,4'-diaminodiphenyl ether, o-phenylenediamine, m-phenylenediamine, p-phenylenediamine, 3,3'-diaminodiphenylsulfone, 4,4'-diaminodiphenylsulfone, 1,3- bis(3-aminophenoxy)benzene, 1,3-bis(4-aminophenoxy)benzene, 1,4-bis(4-aminophenoxy)benzene, bis(4-(4-aminophenoxy)phenyl)methane, 2 , 2-bis(4-(4-aminophenoxy)phenyl)propane, 1,3-bis(2-(4-aminophenyl)-2-propyl)benzene, 1,4-bis(2-(4-amino phenyl)-2-propyl)benzene, 3,3′-diamino-4,4′-dihydroxyphenylmethane, 4,4′-diamino-3,3′-dihydroxyphenylmethane, 3,3′-diamino-4, 4'-dihydroxyphenyl ether, bisaminophenylfluorene, bistoluidinefluorene, 4,4'-bis(4-aminophenoxy)biphenyl, 4,4'-diamino-3,3'-dihydroxyphenyl ether, 3,3' -diamino-4,4'-dihydroxybiphenyl, 4,4'-diamino-2,2'-dihydroxybiphenyl and the like. Among them, 4,4′-diaminodiphenylmethane, 4,4′-diaminodiphenyl ether, 1,3-bis(2-(4-aminophenyl)-2-propyl)benzene, 1,4 -bis(2-(4-aminophenyl)-2-propyl)benzene, 1,3-bis(3-aminophenoxy)benzene, 1,3-bis(4-aminophenoxy)benzene, 1,4-bis( 4-Aminophenoxy)benzene is preferred, and 1,3-bis(2-(4-aminophenyl)-2-propyl)benzene, 1,4-bis(2-(2-( 4-aminophenyl)-2-propyl)benzene, 1,3-bis(3-aminophenoxy)benzene, 1,3-bis(4-aminophenoxy)benzene, 1,4-bis(4-aminophenoxy)benzene is more preferred.

Examples of acid anhydrides represented by the above formula (10) include phthalic anhydride, 3-methylphthalic anhydride, 4-methylphthalic anhydride, 1,2-naphthalic anhydride, and 2,3-naphthalic anhydride. acid anhydride, 1,8-naphthalic anhydride, 2,3-anthracenedicarboxylic anhydride, 4-tert-butyl phthalic anhydride, 4-ethynyl phthalic anhydride, 4-phenylethynyl phthalic anhydride, 4-fluorophthalic anhydride, 4-chlorophthalic anhydride, 4-bromophthalic anhydride, 3,4-dichlorophthalic anhydride and the like.

Monoamines represented by the above formula (11) include, for example, aniline, o-toluidine, m-toluidine, p-toluidine, 2,4-dimethylaniline, 3,4-dimethylaniline, 3,5-dimethylaniline, 2-tert-butylaniline, 3-tert-butylaniline, 4-tert-butylaniline, 1-naphthylamine, 2-naphthylamine, 1-aminoanthracene, 2-aminoanthracene, 9-aminoanthracene, 1-aminopyrene, 3- Chloroaniline, o-anisidine, m-anisidine, p-anisidine, 1-amino-2-methylnaphthalene, 2,3-dimethylaniline, 2,4-dimethylaniline, 2,5-dimethylaniline, 3,4-dimethyl aniline, 4-ethylaniline, 4-ethynylaniline, 4-isopropylaniline, 4-(methylthio)aniline, N,N-dimethyl-1,4-phenylenediamine and the like.

Examples of the phenolic hydroxyl group-containing monoamine represented by the above formula (12) include 3-aminophenol, 4-aminophenol, 4-amino-o-cresol, 5-amino-o-cresol, 4-amino-2 ,3-xylenol, 4-amino-2,5-xylenol, 4-amino-2,6-xylenol, 4-amino-1-naphthol, 5-amino-2-naphthol, 6-amino-1-naphthol, 4 -amino-2,6-diphenylphenol and the like. Among them, 4-amino-o-cresol, 5-amino-o-cresol, and 3-aminophenol are preferable because they are excellent in availability and storage stability and can provide a high glass transition temperature after curing.

When the imide oligomer according to the present invention is produced by the production method described above, the imide oligomer according to the present invention is a plurality of types of imide oligomers having a structure represented by the above formula (1-1) or the above formula (1-2) ) and a mixture of each starting material (imide oligomer composition). Since the imide oligomer composition has an imidization ratio of 70% or more, it is possible to obtain a cured product having excellent mechanical strength at high temperatures and long-term heat resistance at high temperatures when used as a curing agent.
A preferred lower limit for the imidization rate of the imide oligomer composition is 75%, and a more preferred lower limit is 80%. Although there is no particular upper limit for the imidization rate of the imide oligomer composition, the practical upper limit is 98%.
The above-mentioned "imidation rate" is measured by a total reflection measurement method (ATR method) using a Fourier transform infrared spectrophotometer (FT-IR), and is derived from the carbonyl group of amic acid at 1660 cm ^-1 It can be derived from the peak absorbance area in the vicinity by the following formula. Examples of the Fourier transform infrared spectrophotometer include UMA600 (manufactured by Agilent Technologies). The "peak absorbance area of the amic acid oligomer" in the following formula is obtained by removing the solvent by evaporation or the like without performing the imidization step after reacting the acid dianhydride with a diamine or a phenolic hydroxyl group-containing monoamine. is the absorbance area of the amic acid oligomer obtained by
Imidation rate (%) = 100 × (1-(peak absorbance area after imidization)/(peak absorbance area of amic acid oligomer))

From the viewpoint of solubility when used as a curing agent in a curable resin composition, the imide oligomer composition preferably dissolves in an amount of 3 g or more per 10 g of tetrahydrofuran at 25°C.

The imide oligomer composition preferably has a melting point of 200° C. or lower from the viewpoint of handleability when used as a curing agent in a curable resin composition. The melting point of the imide oligomer composition is more preferably 190° C. or lower, even more preferably 180° C. or lower.
Although the lower limit of the melting point of the imide oligomer composition is not particularly limited, it is preferably 60°C or higher.

A preferable lower limit of the content of the imide oligomer according to the present invention is 20 parts by weight, and a preferable upper limit thereof is 80 parts by weight, based on a total of 100 parts by weight of the curable resin and the imide oligomer. When the content of the imide oligomer according to the present invention is within this range, the resulting cured product of the curable resin composition is superior in mechanical strength at high temperatures and long-term heat resistance at high temperatures. A more preferable lower limit of the content of the imide oligomer according to the present invention is 25 parts by weight, and a more preferable upper limit thereof is 75 parts by weight.

The curable resin composition of the present invention contains other curing agents in addition to the imide oligomer according to the present invention, within a range that does not hinder the object of the present invention, in order to improve workability in an uncured state. You may
Examples of other curing agents include phenol-based curing agents, thiol-based curing agents, amine-based curing agents, acid anhydride-based curing agents, cyanate-based curing agents, active ester-based curing agents, and the like. Among them, a phenol-based curing agent, an acid anhydride-based curing agent, a cyanate-based curing agent, and an active ester-based curing agent are preferable.

When the curable resin composition of the present invention contains the other curing agent, the upper limit of the content of the other curing agent in the total curing agent is preferably 70% by weight, more preferably 50% by weight, and still more preferably. The upper limit is 30% by weight.

The curable resin composition of the present invention contains a curable resin.
Examples of the curable resins include epoxy resins, acrylic resins, phenol resins, cyanate resins, isocyanate resins, maleimide resins, benzoxazine resins, silicone resins, fluorine resins, polyimide resins, and phenoxy resins. Among them, epoxy resin is preferable. Moreover, these curable resins may be used alone, or two or more of them may be mixed and used.
In the case of film processing, the curable resin is preferably in a liquid or semi-solid form at 25° C., more preferably in a liquid form, in order to improve handling properties.

Examples of the epoxy resin include bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol E type epoxy resin, bisphenol S type epoxy resin, 2,2'-diallylbisphenol A type epoxy resin, and hydrogenated bisphenol type epoxy resin. , propylene oxide-added bisphenol A type epoxy resin, resorcinol type epoxy resin, biphenyl type epoxy resin, sulfide type epoxy resin, diphenyl ether type epoxy resin, dicyclopentadiene type epoxy resin, naphthalene type epoxy resin, fluorene type epoxy resin, naphthylene ether type epoxy resin, phenol novolak type epoxy resin, ortho-cresol novolak type epoxy resin, dicyclopentadiene novolak type epoxy resin, biphenyl novolak type epoxy resin, naphthalenephenol novolak type epoxy resin, glycidylamine type epoxy resin, alkylpolyol type epoxy resin, Examples include rubber-modified epoxy resins and glycidyl ester compounds. Among them, bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol E type epoxy resin, and resorcinol type epoxy resin are preferable because they have low viscosity and can easily adjust the processability at room temperature of the resulting curable resin composition. .

The curable resin composition of the present invention preferably contains a curing accelerator. By containing the curing accelerator, the curing time can be shortened and the productivity can be improved.

Examples of the curing accelerator include imidazole-based curing accelerators, tertiary amine-based curing accelerators, phosphine-based curing accelerators, photobase generators, and sulfonium salt-based curing accelerators. Among these, imidazole-based curing accelerators and phosphine-based curing accelerators are preferable from the viewpoint of storage stability and curability.
The curing accelerators may be used alone, or two or more of them may be used in combination.

The preferable lower limit of the content of the curing accelerator is 0.8% by weight with respect to the total weight of the curable resin, the imide oligomer and the curing accelerator. When the content of the curing accelerator is 0.8% by weight or more, the effect of shortening the curing time is more excellent. A more preferable lower limit for the content of the curing accelerator is 1% by weight.
From the viewpoint of adhesiveness and the like, the preferred upper limit of the content of the curing accelerator is 10% by weight, and the more preferred upper limit is 5% by weight.

The curable resin composition of the present invention preferably contains an inorganic filler.
By containing the inorganic filler, the curable resin composition of the present invention is excellent in moisture absorption reflow resistance, plating resistance, and workability while maintaining excellent adhesiveness and high-temperature long-term heat resistance. .

The inorganic filler is preferably at least one of silica and barium sulfate. By containing at least one of silica and barium sulfate as the inorganic filler, the curable resin composition of the present invention becomes excellent in moisture absorption reflow resistance, plating resistance, and workability.

Examples of inorganic fillers other than silica and barium sulfate include alumina, aluminum nitride, boron nitride, silicon nitride, glass powder, glass frit, glass fiber, carbon fiber, and inorganic ion exchangers.

The above inorganic fillers may be used alone, or two or more of them may be used in combination.

A preferable lower limit of the average particle size of the inorganic filler is 50 nm, and a preferable upper limit thereof is 4 μm. When the average particle size of the inorganic filler is within this range, the resulting curable resin composition is superior in coatability and workability. A more preferable lower limit of the average particle size of the inorganic filler is 100 nm, and a more preferable upper limit thereof is 3 μm.

The content of the inorganic filler has a preferable lower limit of 10 parts by weight and a preferable upper limit of 150 parts by weight with respect to a total of 100 parts by weight of the curable resin and the imide oligomer. When the content of the inorganic filler is within this range, the obtained curable resin composition is more excellent in moisture absorption reflow resistance, plating resistance, and workability. A more preferable lower limit for the content of the inorganic filler is 20 parts by weight.

The curable resin composition of the present invention may contain a fluidity modifier for the purpose of improving wettability to an adherend in a short time and shape retention.
Examples of the flow control agent include fumed silica such as Aerosil and layered silicate.
The flow modifiers may be used alone, or two or more of them may be used in combination.
Moreover, as the fluidity control agent, one having an average particle size of less than 100 nm is preferably used.

The content of the flow control agent has a preferable lower limit of 0.1 parts by weight and a preferable upper limit of 50 parts by weight with respect to a total of 100 parts by weight of the curable resin and the imide oligomer. When the content of the flow control agent is within this range, the effect of improving the wettability to the adherend in a short time and the shape retention property, etc., is excellent. A more preferable lower limit of the content of the flow control agent is 0.5 parts by weight, and a more preferable upper limit thereof is 30 parts by weight.

The curable resin composition of the present invention may contain an organic filler for the purpose of relaxing stress, imparting toughness, and the like.
Examples of the organic filler include silicone rubber particles, acrylic rubber particles, urethane rubber particles, polyamide particles, polyamideimide particles, polyimide particles, benzoguanamine particles, and core-shell particles thereof. Among them, polyamide particles, polyamideimide particles, and polyimide particles are preferred.
The above organic fillers may be used alone, or two or more of them may be used in combination.

A preferable upper limit of the content of the organic filler is 300 parts by weight with respect to a total of 100 parts by weight of the curable resin and the imide oligomer. When the content of the organic filler is within this range, the resulting cured product of the curable resin composition is superior in toughness and the like while maintaining excellent adhesiveness and the like. A more preferable upper limit of the content of the organic filler is 200 parts by weight.

The curable resin composition of the present invention may contain a flame retardant.
Examples of the flame retardant include boehmite-type aluminum hydroxide, aluminum hydroxide, metal hydrates such as magnesium hydroxide, halogen-based compounds, phosphorus-based compounds, and nitrogen compounds. Among them, boehmite-type aluminum hydroxide is preferable.
The flame retardants may be used alone, or two or more of them may be used in combination.

The preferable lower limit of the content of the flame retardant is 5 parts by weight, and the preferable upper limit thereof is 200 parts by weight with respect to 100 parts by weight in total of the curable resin and the imide oligomer. When the content of the flame retardant is within this range, the resulting curable resin composition has excellent flame retardancy while maintaining excellent adhesion and the like. A more preferable lower limit to the content of the flame retardant is 10 parts by weight, and a more preferable upper limit is 150 parts by weight.

The curable resin composition of the present invention may contain a polymer compound as long as the object of the present invention is not impaired. The polymer compound serves as a film-forming component.

The polymer compound may have a reactive functional group.
Examples of the reactive functional groups include amino groups, urethane groups, imide groups, hydroxyl groups, carboxyl groups, and epoxy groups.

Moreover, the polymer compound may form a phase-separated structure in the cured product, or may not form a phase-separated structure. When the polymer compound does not form a phase separation structure in the cured product, the polymer compound is excellent in mechanical strength at high temperatures, long-term heat resistance at high temperatures, and moisture resistance, so the reactive functional group A polymer compound having an epoxy group as is preferred.

The curable resin composition of the present invention may contain a solvent from the viewpoint of coatability and the like.
As the solvent, a non-polar solvent having a boiling point of 120° C. or lower or an aprotic polar solvent having a boiling point of 120° C. or lower is preferable from the viewpoint of coatability, storage stability, and the like.
Examples of the nonpolar solvent having a boiling point of 120° C. or lower or the aprotic polar solvent having a boiling point of 120° C. or lower include ketone solvents, ester solvents, hydrocarbon solvents, halogen solvents, ether solvents, and nitrogen-containing solvents. system solvents and the like.
Examples of the ketone solvent include acetone, methyl ethyl ketone, and methyl isobutyl ketone.
Examples of the ester solvent include methyl acetate, ethyl acetate, and isobutyl acetate.
Examples of the hydrocarbon solvent include benzene, toluene, normal hexane, isohexane, cyclohexane, methylcyclohexane, normal heptane and the like.
Examples of the halogen-based solvent include dichloromethane, chloroform, and trichlorethylene.
Examples of the ether solvent include diethyl ether, tetrahydrofuran, 1,4-dioxane, 1,3-dioxolane and the like.
Examples of the nitrogen-containing solvent include acetonitrile.
Among them, a group consisting of ketone-based solvents with a boiling point of 60°C or higher, ester-based solvents with a boiling point of 60°C or higher, and ether-based solvents with a boiling point of 60°C or higher, from the viewpoint of handleability, solubility of imide oligomers, etc. At least one more selected is preferable. Examples of such solvents include methyl ethyl ketone, methyl isobutyl ketone, ethyl acetate, isobutyl acetate, 1,4-dioxane, 1,3-dioxolane, tetrahydrofuran and the like.
The "boiling point" means a value measured under conditions of 101 kPa, or a value converted to 101 kPa using a boiling point conversion chart or the like.

A preferable lower limit of the content of the solvent in the curable resin composition of the present invention is 20% by weight, and a preferable upper limit thereof is 90% by weight. When the content of the solvent is within this range, the curable resin composition of the present invention is superior in coatability and the like. A more preferable lower limit of the solvent content is 30% by weight, and a more preferable upper limit is 80% by weight.

The curable resin composition of the present invention may contain a reactive diluent as long as the object of the present invention is not impaired.
From the viewpoint of adhesion reliability, the reactive diluent is preferably a reactive diluent having two or more reactive functional groups in one molecule.

The curable resin composition of the present invention may further contain additives such as coupling agents, dispersants, storage stabilizers, bleed inhibitors, fluxing agents, leveling agents, rust inhibitors, and adhesion promoters. good.

As a method for producing the curable resin composition of the present invention, for example, a mixer such as a homodisper, a universal mixer, a Banbury mixer, or a kneader is used to mix the curable resin, the imide oligomer according to the present invention, and the ion trapping agent. and a method of mixing the agent with a solvent or the like added as necessary.

A curable resin composition film comprising the curable resin composition of the present invention can be obtained by applying the curable resin composition of the present invention onto a substrate film and drying the curable resin composition. A cured product can be obtained by curing the product film.

The curable resin composition of the present invention preferably has an initial adhesive strength of 3 N/cm or more to a copper foil when cured. Since the cured product has an initial adhesive strength of 3 N/cm or more to a copper foil, the curable resin composition of the present invention can be suitably used as a coverlay adhesive for flexible printed circuit boards. The initial adhesive strength of the cured product to copper foil is more preferably 5 N/cm or more, and still more preferably 6 N/cm or more.
The initial adhesive strength to the copper foil is the peel strength when a test piece cut into a width of 1 cm is subjected to a 90 ° peel test at 25 ° C. and a peel speed of 50 mm / min using a tensile tester. can be measured. As the test piece, a polyimide base material (“Kapton 100H”, 25 μmt, manufactured by Toray DuPont Co., Ltd.) is laminated on one side of a curable resin composition film having a thickness of 20 μm, and a copper foil having a thickness of 35 μm is laminated on the other side. Those obtained by heating at 190° C. for 1 hour are used. The initial adhesive strength means a value measured within 24 hours after the preparation of the test piece. The curable resin composition film can be obtained by applying the curable resin composition onto a base film and drying the coating. As the copper foil, an electrolytic copper foil ("UN series" manufactured by Fukuda Metal Foil & Powder Co., Ltd., glossy surface roughness (Ra): 0.25 μm) can be used. Examples of the tensile tester include UCT-500 (manufactured by ORIENTEC).

The curable resin composition of the present invention preferably has an adhesive strength of 3 N/cm or more to a copper foil after storage at 200° C. for 100 hours. The curable resin composition of the present invention is suitable for use as a heat-resistant adhesive for vehicles, etc., because the cured product after storage at 200 ° C. for 100 hours has an adhesive strength of 3 N / cm or more to copper foil. can be done. The adhesion of the cured product to the copper foil after being stored at 200° C. for 100 hours is more preferably 5 N/cm or more, still more preferably 6 N/cm or more.
In particular, the curable resin composition of the present invention preferably has an adhesive strength of 3 N/cm or more to a copper foil after being stored at 200° C. for 200 hours. As a result, even after long-term storage under high-temperature conditions such as 175° C. for 1,000 hours, the decrease in adhesive strength can be further suppressed.
The adhesive strength to the copper foil of the cured product after storage at 200 ° C. for 100 hours was measured by storing a test piece prepared in the same manner as the initial adhesive strength measurement method described above at 200 ° C. for 100 hours. It means a value measured in the same manner as the above initial adhesive strength within 24 hours after standing to cool to 100°C.

The curable resin composition of the present invention preferably has a water absorption of 1.5% or less after being exposed to a high-temperature, high-humidity environment of 85° C. and 85% RH for 24 hours. When the water absorption of the cured product is 1.5% or less, the curable resin composition of the present invention is superior in initial adhesiveness, high-temperature long-term heat resistance, and reliability during moisture absorption. The water absorption of the cured product is more preferably 1.2% or less, even more preferably 1.0% or less.
The water absorption of the cured product after exposure to the high temperature and high humidity environment of 85° C. and 85% RH for 24 hours can be determined from the change in weight of the cured product before and after the exposure. Specifically, after measuring the weight of the cured product before exposure, it is exposed to a high temperature and high humidity environment of 85 ° C. and 85% RH for 24 hours, and the weight of the cured product after exposure is measured. The water absorption rate of the cured product can be derived from.
Water absorption (%) = 100 × (((weight after exposure) - (weight before exposure)) ÷ (weight before exposure))
As the cured product for measuring the water absorption rate, one obtained by heating a curable resin composition film having a size of 50 mm×50 mm and a thickness of 400 μm at 190° C. for 1 hour is used.

The curable resin composition of the present invention can be used in a wide range of applications, and is particularly suitable for electronic material applications that require high heat resistance. For example, aviation and automotive electric control unit (ECU) applications, die attach agents for power device applications using SiC and GaN, adhesives for power overlay packages, curable resin compositions for printed wiring boards, flexible printed circuit boards coverlay adhesives, copper clad laminates, semiconductor bonding adhesives, interlayer insulating films, prepregs, LED sealants, curable resin compositions for structural materials, and the like. Among others, it is preferably used for adhesives. An adhesive containing the curable resin composition of the present invention is also one aspect of the present invention.

The curable resin composition film can be suitably used as an adhesive film. An adhesive film using the curable resin composition of the present invention is also one aspect of the present invention.
A coverlay film having a substrate film and a layer formed of a cured product of the curable resin composition of the present invention provided on the substrate film is also one aspect of the present invention.
Furthermore, a flexible copper-clad laminate having a substrate film, a layer formed of a cured product of the curable resin composition of the present invention provided on the substrate film, and a copper foil is also one of the present invention. be.

ADVANTAGE OF THE INVENTION According to this invention, the curable resin composition which can obtain the hardened|cured material which is excellent in high temperature long-term heat resistance, moisture absorption reflow resistance, and plating resistance can be provided. Further, according to the present invention, an adhesive containing the curable resin composition, an adhesive film formed using the curable resin composition, and a coverlay film and flexible film having a cured product of the curable resin composition A copper clad laminate can be provided.

EXAMPLES The present invention will be described in more detail with reference to Examples below, but the present invention is not limited to these Examples.

(Synthesis Example 1 (preparation of imide oligomer composition A))
17.2 parts by weight of 1,4-bis(2-(4-aminophenyl)-2-propyl)benzene (manufactured by Mitsui Chemicals Fine Co., Ltd., “Bisaniline P”) and N-methylpyrrolidone (manufactured by Wako Pure Chemical Industries, Ltd., "NMP") was dissolved in 400 parts by weight. 52.0 parts by weight of 4,4′-(4,4′-isopropylidenediphenoxy)diphthalic anhydride (manufactured by Tokyo Kasei Kogyo Co., Ltd.) was added to the resulting solution, and the reaction was stirred at 25° C. for 2 hours. to obtain an amic acid oligomer solution. After removing N-methylpyrrolidone from the obtained amic acid oligomer solution under reduced pressure, the solution was heated at 300° C. for 2 hours to obtain an imide oligomer composition A (imidization rate: 97%).
By ¹ H-NMR, GPC, and FT-IR analysis, the imide oligomer composition A is an imide oligomer having a structure represented by the above formula (1-1) (A is represented by the following formula (13). It was confirmed that B contains a group represented by the following formula (14). Also, the number average molecular weight of the imide oligomer having the structure represented by the formula (1-1) was 1,390. Furthermore, the imide oligomer composition A includes an imide oligomer represented by the above formula (4-1) as an imide oligomer having a structure represented by the above formula (1-1) and an imide oligomer represented by the above formula (4-3). (A is a group represented by the following formula (13), and B is a group represented by the following formula (14)).

In formula (13), * is a binding position.

In formula (14), * is a binding position.

(Synthesis Example 2 (preparation of imide oligomer composition B))
21.8 parts by weight of 3-aminophenol was dissolved in 400 parts by weight of N-methylpyrrolidone (manufactured by Wako Pure Chemical Industries, Ltd., "NMP"). 17.2 parts by weight of 4,4'-(4,4'-isopropylidenediphenoxy)diphthalic anhydride was added to the resulting solution and stirred at 25°C for 2 hours to react to form an amic acid oligomer solution. Obtained. After removing N-methylpyrrolidone from the obtained amic acid oligomer solution under reduced pressure, the solution was heated at 300° C. for 2 hours to obtain an imide oligomer composition B (imidation rate 96%).
By ¹ H-NMR, GPC, and FT-IR analysis, the imide oligomer composition B is an imide oligomer having a structure represented by the above formula (1-2) (A is represented by the above formula (13). It was confirmed that Ar contains a group represented by the following formula (15). Also, the number average molecular weight of the imide oligomer having the structure represented by the formula (1-2) was 630. Further, the imide oligomer composition B is an imide oligomer represented by the above formula (5-1) as an imide oligomer having a structure represented by the above formula (1-2) (A is represented by the above formula (13) group, R is a hydrogen atom).

In formula (15), * is a binding position.

(Examples 1 to 10, Comparative Examples 1 and 2)
According to the compounding ratio shown in Tables 1 and 2, each material was stirred and mixed to prepare curable resin compositions of Examples 1 to 10 and Comparative Examples 1 and 2.
A curable resin composition film was obtained by applying each of the obtained curable resin compositions onto a substrate PET film so as to have a thickness of about 20 μm, followed by drying.

<Evaluation>
Each curable resin composition and each curable resin composition film obtained in Examples and Comparative Examples were evaluated as follows. The results are shown in Tables 1 and 2.

(initial adhesiveness)
Each curable resin composition obtained in Examples and Comparative Examples is coated on a polyimide substrate ("Kapton 100H" manufactured by Toray DuPont Co., Ltd., 25 μmt) so as to have a thickness of about 20 μm, and dried. Thus, an adhesive film was obtained. The resulting adhesive film was cut into 1 cm width, and a 35 μm thick copper foil (manufactured by Fukuda Metal Foil & Powder Co., Ltd., electrolytic copper foil glossy side, “CF-T8G-UN-35”) was applied to the adhesive side. They were laminated and hot-pressed under the conditions of 190° C., 3 MPa, and 1 hour to cure the adhesive layer and obtain a test piece. A test piece within 24 hours after preparation was subjected to a 90° peel test at a peel speed of 50 mm/min at 25°C using a tensile tester ("UCT-500" manufactured by ORIENTEC) to measure the peel strength. The peel strength obtained was taken as the initial adhesive strength.
When the initial adhesive strength was 6 N / cm or more, "◎", "○" when it was 3 N / cm or more and less than 6 N / cm, and "×" when it was less than 3 N / cm Initial adhesiveness evaluated.

(High temperature long-term heat resistance)
The test piece obtained in the same manner as in the above "(Initial adhesion)" was stored at 175 ° C. for 1000 hours, then allowed to cool to 25 ° C. For the test piece within 24 hours after cooling, the above "(Initial adhesion The peel strength was measured in the same manner as described in "Force)", and the obtained peel strength was defined as the adhesive strength after 1000 hours at 175°C.
If the adhesive strength after 1000 hours at 175 ° C. was 6 N / cm or more, "◎", if it was 3 N / cm or more and less than 6 N / cm, "○", If it was less than 3 N / cm, " The high-temperature long-term heat resistance (175°C, 1000 hours) was evaluated as x.
Also, the test piece obtained in the same manner as in the above "(initial adhesion)" was stored at 200 ° C. for 100 hours or 200 hours, then allowed to cool to 25 ° C., and the test piece within 24 hours after cooling. The peel strength was measured in the same manner as in "(initial adhesive strength)" above, and the obtained peel strength was defined as the adhesive strength after 100 hours at 200°C or the adhesive strength after 200 hours at 200°C.
200 ° C., when the adhesive strength after 100 hours was 6 N / cm or more, "◎", when it was 3 N / cm or more and less than 6 N / cm, "○", when it was less than 3 N / cm, " The high-temperature long-term heat resistance (200° C., 100 hours) was evaluated as ×.
If the adhesive strength after 200 hours at 200 ° C. was 6 N / cm or more, "◎", if it was 3 N / cm or more and less than 6 N / cm, "○", If it was less than 3 N / cm, " The high-temperature long-term heat resistance (200° C., 200 hours) was evaluated as “x”.

(Moisture absorption reflow resistance)
A test piece obtained in the same manner as in the above "(Initial Adhesion)" was subjected to a moisture absorption reflow test in which it was left to stand in an environment of 40°C and 90% RH for 72 hours and then heated at 260°C for 20 seconds. After the moisture absorption reflow test, the test piece was visually checked for air bubbles.
Moisture absorption reflow resistance was evaluated as "○" when no bubbles were confirmed, "Δ" when one or two bubbles were confirmed, and "×" when three or more bubbles were confirmed.

(plating resistance)
Each curable resin composition obtained in Examples and Comparative Examples was coated on a polyimide substrate (manufactured by Toray DuPont, "Kapton 100H", thickness 25 μm) so as to have a thickness of about 20 μm, An adhesive film was obtained by drying. An opening of 10 mm × 10 mm was provided in the obtained adhesive film, and a copper wiring pattern with L/S = 100 µm/100 µm and a thickness of 18 µm and a copper clad laminate made of a polyimide film with a thickness of 50 µm were laminated and evaluated for FPC. A sample for The bonding was performed by hot pressing under the conditions of 190° C., 3 MPa, and 1 hour.
The obtained FPC evaluation sample was plated at 80° C. to 90° C. using commercially available electroless nickel plating bath and electroless gold plating bath under conditions of 5 μm nickel and 0.05 μm gold. Observation of the edge of the adhesive film in the opening with an optical microscope indicates that no oozing of the plating solution was observed, and "○" indicates that the oozing of the plating solution was observed within a range of less than 200 μm from the edge of the adhesive film. Plating resistance was evaluated as "Δ" and "x" when the oozing of the plating solution was confirmed in a range of 200 μm or more from the edge of the adhesive film.

(water absorption rate)
After peeling off the base PET film from each curable resin composition film obtained in Examples and Comparative Examples, the films were laminated and cut to obtain laminated films of 50 mm×50 mm and 400 μm in thickness. A cured product was obtained by heating the obtained laminated film at 190° C. for 1 hour. After measuring the weight of the obtained cured product (weight before exposure), it was exposed to a high temperature and high humidity environment of 85° C. and 85% RH for 24 hours. The weight of the cured product after exposure to the high-temperature and high-humidity environment (weight after exposure) was measured, and the water absorption rate of the cured product was derived from the above formula.

ADVANTAGE OF THE INVENTION According to this invention, the curable resin composition which can obtain the hardened|cured material which is excellent in high temperature long-term heat resistance, moisture absorption reflow resistance, and plating resistance can be provided. Further, according to the present invention, an adhesive containing the curable resin composition, an adhesive film formed using the curable resin composition, and a coverlay film and flexible film having a cured product of the curable resin composition A copper clad laminate can be provided.

Claims (10)

Containing a curable resin, an imide compound having an imide skeleton in the main chain and at least one of an acid anhydride group and a phenolic hydroxyl group at the end, and an ion scavenger ,
The curable resin includes an epoxy resin,
The imide compound has a number average molecular weight of 4000 or less
A curable resin composition characterized by: 2. The curable resin composition according to claim 1, wherein said ion scavenger is an anion exchanger or an amphoteric ion exchanger. 3. The curable resin composition according to claim 1, wherein the ion scavenger is particles having an average particle size of 10 [mu]m or less. 4. The curable resin composition according to claim 1, 2 or 3, wherein the content of said ion scavenger is 0.1 parts by weight or more and 200 parts by weight or less with respect to a total of 100 parts by weight of said curable resin and said imide compound. thing. The cured product has an initial adhesive strength to copper foil of 3 N/cm or more, and the cured product has adhesive strength to copper foil of 3 N/cm or more after being stored at 200° C. for 100 hours. 5. The curable resin composition according to 4. 6. The curable resin composition according to claim 1, 2, 3, 4, or 5, wherein the cured product has a water absorption of 1.5% or less after being exposed to a high-temperature, high-humidity environment of 85° C. and 85% RH for 24 hours. . An adhesive comprising the curable resin composition according to claim 1, 2, 3, 4, 5 or 6 . An adhesive film using the curable resin composition according to claim 1, 2, 3, 4, 5 or 6 . A coverlay film comprising a base film and a layer comprising a cured product of the curable resin composition according to claim 1, 2, 3, 4, 5 or 6 provided on the base film. A flexible copper clad laminate comprising a substrate film, a layer comprising a cured product of the curable resin composition according to claim 1, 2, 3, 4, 5 or 6 provided on the substrate film, and a copper foil. board.