JP7211715B2 - Curable resin composition, cured product, adhesive, adhesive film, coverlay film, and printed wiring board - Google Patents

Description

TECHNICAL FIELD The present invention relates to a curable resin composition having excellent fluidity before curing and excellent adhesiveness, heat resistance and bending resistance after curing. The present invention also relates to a cured product of the curable resin composition, and an adhesive, an adhesive film, a coverlay film and a printed wiring board using the curable resin composition.

A flexible printed wiring board (FPC) usually has a structure in which a copper foil or the like is attached to one side or both sides of an insulating film such as a polyimide film via an adhesive layer. Adhesives used in adhesive layers of flexible printed wiring boards are required to have excellent fluidity characteristics that can achieve both sufficient filling properties (unevenness embedding properties) and ooze-preventing properties during thermocompression bonding. As such adhesives, for example, Patent Documents 1 to 3 disclose thermosetting components such as epoxy resins, thermoplastic resins such as acrylic resins, polyamides, and polyesters, and flexible components such as acrylonitrile-butadiene rubbers. A curable resin composition containing the above is disclosed.

On the other hand, with the recent expansion of applications such as in-vehicle use, adhesives are required to have long-term heat resistance. However, the adhesives using the curable resin compositions disclosed in Patent Documents 1 to 3 have insufficient heat resistance.
As an adhesive with excellent heat resistance, Patent Document 4 discloses an adhesive containing a soluble polyester, a phenoxy resin, and an imidosiloxane oligomer. However, the adhesive disclosed in Patent Document 4 is inferior in fluidity, and it is difficult to achieve both filling properties and leaching prevention properties.

JP 2006-232984 A JP 2009-167396 A Japanese Patent Application Laid-Open No. 2008-308686 JP-A-5-306386

An object of the present invention is to provide a curable resin composition that has excellent fluidity before curing and excellent adhesion, heat resistance, and bending resistance after curing. Another object of the present invention is to provide a cured product of the curable resin composition, and an adhesive, an adhesive film, a coverlay film, and a printed wiring board using the curable resin composition. do.

The present invention contains a thermosetting resin, a thermoplastic resin and an imide oligomer, the imide oligomer has a reactive functional group capable of reacting with the thermosetting resin, and the reactive functional group is an acid It is an anhydride group and/or a phenolic hydroxyl group, and the thermoplastic resin is a curable resin composition containing a phenoxy resin.
The present invention will be described in detail below.

The present inventors use an imide oligomer having a reactive functional group capable of reacting with the thermosetting resin as the imide oligomer in a curable resin composition containing a thermosetting resin, a thermoplastic resin, and an imide oligomer. I considered. As a result, the inventors have found that it is possible to obtain a curable resin composition having excellent fluidity before curing and excellent adhesiveness, heat resistance, and bending resistance after curing, and completed the present invention.

The curable resin composition of the present invention contains a thermosetting resin.
An epoxy resin is preferably used as the thermosetting resin.
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, alkyl polyol type epoxy resin, Examples include rubber-modified epoxy resins, fluorene-type epoxy resins, glycidyl ester compounds, and the like. Among them, bisphenol A-type epoxy resin, bisphenol F-type epoxy resin, bisphenol E-type epoxy resin, resorcinol-type epoxy resin, etc. Epoxy resins that are liquid at room temperature are preferred. The above epoxy resins may be used alone, or two or more of them may be used in combination.

The preferable lower limit of the number average molecular weight of the thermosetting resin is 90, and the preferable upper limit thereof is 3,000. When the number average molecular weight of the thermosetting resin is within this range, the resulting curable resin composition will be more excellent in adhesiveness and heat resistance. A more preferable lower limit of the number average molecular weight of the thermosetting resin is 100, and a more preferable upper limit thereof is 2,500.
In addition, in this specification, the above-mentioned "number average molecular weight" is a value measured by gel permeation chromatography (GPC) 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.).

A preferable lower limit of the content of the thermosetting resin in the total 100 parts by weight of the thermosetting resin, the thermoplastic resin and the imide oligomer is 10 parts by weight, and a preferable upper limit is 90 parts by weight. When the content of the thermosetting resin is 10 parts by weight or more, the resulting curable resin composition is superior in adhesiveness and heat resistance. When the content of the thermosetting resin is 90 parts by weight or less, the resulting curable resin composition has excellent flow properties. A more preferable lower limit for the content of the thermosetting resin is 20 parts by weight, and a more preferable upper limit is 80 parts by weight.

The curable resin composition of the present invention contains a thermoplastic resin.
By using the above-mentioned thermoplastic resin, the curable resin composition of the present invention has excellent fluidity, can easily achieve both filling properties and leaching prevention properties during thermocompression bonding, and has bending resistance after curing. It will be excellent in quality.

Examples of the thermoplastic resin include phenoxy resin, polyamide, acrylic resin, polyester and the like. Among them, phenoxy resins and polyamides are preferable from the viewpoint of heat resistance, and phenoxy resins are more preferable from the viewpoints of leaching resistance and handleability during thermocompression bonding.

Examples of the phenoxy resin include bisphenol A type phenoxy resin, bisphenol F type phenoxy resin, bisphenol E type phenoxy resin, bisphenol A-bisphenol F type phenoxy resin, acetophenone-biphenyl type phenoxy resin, bisphenol S type phenoxy resin, phosphorus-containing Phenoxy resins, trimethylcyclohexane skeleton phenoxy resins, bisphenol fluorene skeleton phenoxy resins and the like can be mentioned. Among them, bisphenol A type phenoxy resin, bisphenol F type phenoxy resin and bisphenol A-bisphenol F type phenoxy resin are preferable.

The preferable lower limit of the weight average molecular weight of the thermoplastic resin is 3,000, and the preferable upper limit thereof is 200,000. When the weight-average molecular weight of the thermoplastic resin is within this range, the obtained curable resin composition is excellent in fluidity and bending resistance after curing. A more preferable lower limit of the weight average molecular weight of the thermoplastic resin is 5,000, a more preferable upper limit is 150,000, and a further preferable upper limit is 100,000.
When the thermoplastic resin is used in applications requiring a higher level of bending resistance, the preferred lower limit of the weight-average molecular weight of the thermoplastic resin is 10,000.
In addition, the above-mentioned "weight 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 weight average molecular weight by GPC in terms of polystyrene include JAIGEL-2H-A (manufactured by Japan Analytical Industry Co., Ltd.).

A preferable lower limit of the content of the thermoplastic resin is 1 part by weight, and a preferable upper limit thereof is 60 parts by weight based on a total of 100 parts by weight of the thermosetting resin, the thermoplastic resin and the imide oligomer. When the content of the thermoplastic resin is 1 part by weight or more, the resulting curable resin composition is excellent in fluidity and bending resistance after curing. When the content of the thermoplastic resin is 60 parts by weight or less, the resulting curable resin composition is superior in adhesiveness and heat resistance. A more preferable lower limit to the content of the thermosetting resin is 3 parts by weight, and a more preferable upper limit is 50 parts by weight.

The curable resin composition of the present invention contains an imide oligomer.
The imide oligomer has a reactive functional group capable of reacting with the thermosetting resin. By using an imide oligomer having a reactive functional group that can react with the thermosetting resin, the curable resin composition of the present invention has the effect of achieving both filling properties and leaching prevention properties during thermocompression bonding, and curing The adhesiveness and heat resistance after curing are excellent while maintaining the bending resistance after curing.

The reactive functional group of the imide oligomer is preferably an acid anhydride group and/or a phenolic hydroxyl group when an epoxy resin is used as the thermosetting resin, although it depends on the type of thermosetting resin used.
The imide oligomer preferably has the reactive functional groups at the ends of the main chain, more preferably at both ends.

As a method for producing an imide oligomer having an acid anhydride group as the reactive functional group, for example, an acid dianhydride represented by the following formula (1) and a diamine represented by the following formula (2) are reacted. and the like.
Further, as a method for producing an imide oligomer having a phenolic hydroxyl group as the reactive functional group, for example, an acid dianhydride represented by the following formula (1) and a phenolic hydroxyl group represented by the following formula (3) A method of reacting with a contained monoamine is also included. Furthermore, after reacting an acid dianhydride represented by the following formula (1) with a diamine represented by the following formula (2), a phenolic hydroxyl group-containing monoamine represented by the following formula (3) is further reacted. and the like.

In formula (1), A is a tetravalent group represented by formula (4-1) or formula (4-2) below.

In formula (2), B is a divalent group represented by the following formula (5-1) or the following formula (5-2), and R ¹ to R ⁴ are each independently a hydrogen atom or 1 is a valent hydrocarbon group.

In formula (3), Ar is an optionally substituted divalent aromatic group, and R ⁵ and R ⁶ are each independently a hydrogen atom or a monovalent hydrocarbon group.

In formula (4-1) and formula (4-2), * is a bonding position, and in formula (4-1), Z is a bond, an oxygen atom, a carbonyl group, a sulfur atom, a sulfonyl group, a bond It is a linear or branched divalent hydrocarbon group which may have an oxygen atom at the position, or a divalent group having an aromatic ring which may have an oxygen atom at the bonding position. The hydrogen atoms of the aromatic rings in formulas (4-1) and (4-2) may be substituted.

In formula (5-1) and formula (5-2), * is a bonding position, and in formula (5-1), Y is a bond, an oxygen atom, a carbonyl group, a sulfur atom, a sulfonyl group, a bond It is a linear or branched divalent hydrocarbon group which may have an oxygen atom at the position, or a divalent group having an aromatic ring which may have an oxygen atom at the bonding position. Some or all of the hydrogen atoms in the phenylene groups in formulas (5-1) and (5-2) may be substituted with hydroxyl groups or monovalent hydrocarbon groups.

A specific example of the method for reacting the acid dianhydride represented by the above formula (1) with the diamine represented by the above formula (2) is shown below.
First, the diamine represented by the above formula (2) is dissolved in advance in a solvent (eg, N-methylpyrrolidone, dimethylformamide, dimethylacetamide, etc.) in which the amic acid oligomer obtained by the reaction is soluble, and the resulting solution is The acid dianhydride represented by the above formula (1) is added to and reacted to obtain an amic acid oligomer solution. Next, the solvent is removed from the resulting amic acid oligomer solution by heating, pressure reduction, or the like, or the amic acid oligomer is recovered by reprecipitating by putting it in a poor solvent such as water, methanol, or hexane, and further, about The imidization reaction proceeds by heating at 200° C. or higher for 1 hour or longer. By adjusting the molar ratio of the acid dianhydride represented by the above formula (1) and the diamine represented by the above formula (2), and the imidization conditions, it has a desired number average molecular weight, and both An imide oligomer having an acid anhydride group as a reactive functional group at the terminal can be obtained.

A specific example of the method of reacting the acid dianhydride represented by the above formula (1) with the phenolic hydroxyl group-containing monoamine represented by the above formula (3) is shown below.
First, a phenolic hydroxyl group-containing monoamine represented by formula (3) is dissolved in advance in a solvent (for example, N-methylpyrrolidone, etc.) in which the amic acid oligomer obtained by the reaction is soluble, and the resulting solution is added with the above formula An acid dianhydride represented by (1) is added and reacted to obtain an amic acid oligomer solution. Next, the solvent is removed from the resulting amic acid oligomer solution by heating, pressure reduction, or the like, or the amic acid oligomer is recovered by reprecipitating by putting it in a poor solvent such as water, methanol, or hexane, and further, about The imidization reaction proceeds by heating at 200° C. or higher for 1 hour or longer. By adjusting the molar ratio of the acid dianhydride represented by the above formula (1) and the phenolic hydroxyl group-containing monoamine represented by the above formula (3), and the imidization conditions, a desired number average molecular weight can be obtained. and having phenolic hydroxyl groups as reactive functional groups at both ends can be obtained.

A method of reacting an acid dianhydride represented by the above formula (1) with a diamine represented by the above formula (2), and then further reacting a phenolic hydroxyl group-containing monoamine represented by the above formula (3). Specific examples of are shown below.
First, the diamine represented by the above formula (2) is dissolved in advance in a solvent (eg, N-methylpyrrolidone, dimethylformamide, dimethylacetamide, etc.) in which the amic acid oligomer obtained by the reaction is soluble, and the resulting solution is The acid dianhydride represented by the above formula (1) is added to and reacted to obtain a solution of an amic acid oligomer (A) having acid anhydride groups at both ends. Next, the solvent is removed from the obtained solution of the amic acid oligomer (A) by heating, pressure reduction, or the like, or the amic acid oligomer (A) is reprecipitated by adding it to a poor solvent such as water, methanol, or hexane to reprecipitate the amic acid oligomer (A). is collected and further heated at about 200° C. or higher for 1 hour or longer to advance the imidization reaction.
The thus-obtained imide oligomer having acid anhydride groups as reactive functional groups at both ends is dissolved again in a soluble solvent (e.g., N-methylpyrrolidone, dimethylformamide, dimethylacetamide, etc.), A phenolic hydroxyl group-containing monoamine represented by the above formula (3) is added and reacted to obtain a solution of an amic acid oligomer (B). The amic acid oligomer (B) is recovered by removing the solvent from the resulting solution of the amic acid oligomer (B) by heating, reducing pressure, or the like, or by reprecipitating it by adding it to a poor solvent such as water, methanol, or hexane. Then, the mixture is heated at about 200° C. or higher for 1 hour or longer to advance the imidization reaction. The molar ratio of the acid dianhydride represented by the above formula (1), the diamine represented by the above formula (2), and the phenolic hydroxyl group-containing monoamine represented by the above formula (3), and imidization conditions By adjusting, it is possible to obtain an imide oligomer having a desired number average molecular weight and phenolic hydroxyl groups as reactive functional groups at both ends.

Examples of the acid dianhydride represented by the above formula (1) 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(3,4-dicarboxylphenoxy)diphenyl ether, p-phenylenebis (trimellitate anhydride), 2,3,3′,4′-biphenyltetracarboxylic dianhydride, 3,3′,4,4′-biphenyltetracarboxylic dianhydride, 4,4′-carbonyldiphthal An acid dianhydride etc. are mentioned. Among them, 4,4′-(4,4′-isopropylidenediphenoxy)diphthalic anhydride, 3,4′-oxydiphthalic dianhydride, 4,4'-oxydiphthalic dianhydride and 4,4'-carbonyldiphthalic dianhydride are preferred.

Examples of diamines represented by the above formula (2) include 3,3′-diaminodiphenylmethane, 3,4′-diaminodiphenylmethane, 4,4′-diaminodiphenylmethane, 3,3′-diaminodiphenyl ether, 3,4 '-diaminodiphenyl ether, 4,4'-diaminodiphenyl ether, 1,2-phenylenediamine, 1,3-phenylenediamine, 1,4-phenylenediamine, 3,3'-diaminodiphenylsulfone, 4,4'-diaminodiphenyl Sulfone, bis(4-(3-aminophenoxy)phenyl)sulfone, bis(4-(4-aminophenoxy)phenyl)sulfone, 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-aminophenyl)-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, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl ether, 1,2-phenylenediamine, and 1,3-phenylene are excellent in terms of solubility, heat resistance, and availability. Diamine, 1,4-phenylenediamine, bis(4-(3-aminophenoxy)phenyl)sulfone, bis(4-(4-aminophenoxy)phenyl)sulfone, 1,3-bis(2-(4-aminophenyl) )-2-propyl)benzene, 1,3-bis(3-aminophenoxy)benzene, 1,4-bis(2-(4-aminophenyl)-2-propyl)benzene, 3,3′-dihydroxybenzidine preferable.

Examples of the phenolic hydroxyl group-containing monoamine represented by the above formula (3) 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, 3-aminophenol, 4-aminophenol, 4-amino-o-cresol, 5-amino-o- Cresol is preferred.

A preferable lower limit of the imidization rate of the imide oligomer is 70%. When the imidization rate is 70% or more, it is possible to obtain a cured product having excellent mechanical strength at high temperatures and long-term heat resistance. A more preferable lower limit of the imidization rate is 75%, and a further preferable lower limit is 80%. Although there is no particular upper limit for the imidization rate of the imide oligomer, the practical upper limit is 98%.
The above-mentioned "imidization rate" can be determined by Fourier transform infrared spectroscopy (FT-IR). Specifically, a Fourier transform infrared spectrophotometer (e.g., Agilent Technologies, "UMA600", etc.) is used to measure total reflection measurement (ATR method), and the carbonyl group of amic acid is used for measurement. It can be derived from the peak absorbance area near 1660 cm ⁻¹ by the following formula. The "peak absorbance area of the amic acid oligomer" in the following formula is the absorbance area of the amic acid oligomer obtained by removing the solvent by evaporation without performing the imidization step in the production method described above.
Imidation rate (%) = 100 × (1-(peak absorbance area after imidization)/(peak absorbance area of amic acid oligomer))

The imide oligomers may be used alone, or two or more of them may be used in combination.

The preferred lower limit of the number average molecular weight of the imide oligomer is 400, and the preferred upper limit is 5,000. When the number average molecular weight is within this range, the resulting cured product is more excellent in long-term heat resistance. A more preferable lower limit of the number average molecular weight of the imide oligomer is 500, and a more preferable upper limit thereof is 4,000.

A preferable upper limit of the softening point of the imide oligomer is 250°C. When the softening point of the imide oligomer is 250° C. or lower, the resulting cured product is excellent in adhesiveness and long-term heat resistance. A more preferable upper limit of the softening point of the imide oligomer is 200°C.
Although there is no preferred lower limit for the softening point of the imide oligomer, the practical lower limit is 60°C.
The softening point of the imide oligomer can be determined by the ring and ball method according to JIS K 2207.

A preferable lower limit of the content of the imide oligomer is 10 parts by weight, and a preferable upper limit thereof is 90 parts by weight based on the total 100 parts by weight of the thermosetting resin, the thermoplastic resin and the imide oligomer. When the content of the imide oligomer is within this range, the resulting cured product of the curable resin composition is excellent in mechanical strength at high temperatures, adhesiveness, and long-term heat resistance. A more preferable lower limit to the content of the imide oligomer is 20 parts by weight, and a more preferable upper limit is 80 parts by weight.

The curable resin composition of the present invention may contain other curing agents in addition to the imide oligomer as long as the object of the present invention is not impaired.
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 preferred upper limit of the content of the other curing agent in the total 100 parts by weight of the imide oligomer and the other curing agent is 70 parts by weight. parts, a more preferred upper limit is 50 parts by weight, and a still more preferred upper limit is 30 parts by weight.

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, phosphorus-based curing accelerators, photobase generators, sulfonium salt-based curing accelerators, and the like. . Of these, imidazole-based curing accelerators are preferred because of their excellent storage stability.

The content of the curing accelerator has a preferable lower limit of 0.01 parts by weight and a preferable upper limit of 10 parts by weight with respect to 100 parts by weight of the thermosetting resin. When the content of the curing accelerator is within this range, the effect of shortening the curing time while maintaining excellent adhesiveness and the like is enhanced. A more preferred lower limit to the content of the curing accelerator is 0.05 parts by weight, and a more preferred upper limit is 5 parts by weight.

The curable resin composition of the present invention may contain an inorganic filler for the purpose of lowering the coefficient of linear expansion after curing to reduce warpage or improving adhesion reliability. In addition, the above inorganic filler can also be suitably used as a flow control agent.

Examples of the inorganic filler include silica such as fumed silica and colloidal silica, alumina, aluminum nitride, boron nitride, silicon nitride, glass powder, glass frit, glass fiber, carbon fiber, inorganic ion exchangers, and the like. .

A preferable upper limit of the content of the inorganic filler is 500 parts by weight with respect to 100 parts by weight of the thermosetting resin. When the content of the inorganic filler is 500 parts by weight or less, excellent effects such as improvement of adhesion reliability and flow adjustment can be obtained while maintaining excellent workability and the like. A more preferable upper limit of the content of the inorganic filler is 400 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.

A preferable upper limit of the content of the organic filler is 500 parts by weight with respect to 100 parts by weight of the thermosetting resin. When the content of the organic filler is 500 parts by weight or less, the obtained cured product 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 400 parts 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.
Examples of the reactive functional group possessed by the reactive diluent include those similar to the reactive functional group possessed by the polymer compound described above.

The curable resin composition of the present invention may further contain additives such as solvents, coupling agents, dispersants, storage stabilizers, anti-bleeding agents and fluxing agents.

As a method for producing the curable resin composition of the present invention, for example, using a mixer such as a homodisper, a universal mixer, a Banbury mixer, a kneader, a thermosetting resin, a thermoplastic resin, a curing agent, A method of mixing other curing agents, curing accelerators, inorganic fillers (fluidity modifiers), etc., which are added as necessary, may be mentioned.

The preferred lower limit of the lowest melt viscosity of the curable resin composition of the present invention is 5 kPa·s, and the preferred upper limit is 300 kPa·s. When the minimum melt viscosity is within this range, the curable resin composition of the present invention has more excellent fluidity. A more preferable lower limit of the minimum melt viscosity is 10 kPa·s, a more preferable upper limit is 200 kPa·s, and a further preferable upper limit is 150 kPa·s.
The above minimum melt viscosity is measured using a rotary rheometer (for example, "VAR-100" manufactured by Rheologicala Co., Ltd.) under the conditions of a temperature increase rate of 10 ° C./min, a frequency of 1 Hz, and a strain of 1%. It can be obtained from the minimum value of the complex viscosity when measured over a temperature range of 60°C to 300°C.

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, it can be used as a die attach agent for aviation and automotive electric control unit (ECU) applications, and for power device applications using SiC and GaN. Also, for example, adhesives for power overlay packages, adhesives for printed wiring boards, adhesives for coverlay films of flexible printed wiring boards, copper-clad laminates, adhesives for semiconductor bonding, interlayer insulating films, prepregs, and LED sealing It can also be used as a blocking agent, an adhesive for structural materials, and the like. Among others, it is preferably used for adhesives, and is particularly preferably used for adhesives for cover lay films of flexible printed wiring boards.
An adhesive comprising the curable resin composition of the present invention is also one aspect of the present invention. The adhesive of the present invention can form an adhesive film (curable resin composition film) by a method such as drying after coating on a release film, and by curing the adhesive film, A cured product can be obtained. A cured product of the curable resin composition of the present invention is also one aspect of the present invention.
An adhesive film using the adhesive of the present invention is also one aspect of the present invention.
A coverlay film having an adhesive layer made of a cured product of the curable resin composition of the present invention and an insulating film is also one aspect of the present invention. Furthermore, a flexible printed wiring board having the coverlay film of the present invention is also one aspect of the present invention.

According to the present invention, it is possible to provide a curable resin composition which has excellent fluidity before curing and excellent adhesion, heat resistance, and bending resistance after curing. Further, according to the present invention, it is possible to provide a cured product of the curable resin composition, and an adhesive, an adhesive film, a coverlay film, and a printed wiring board using the curable resin composition. can.

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 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 Fujifilm Wako Pure Chemical Industries, Ltd.) ) was dissolved in 200 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 A (imidation rate 97%).
It was confirmed by ¹ H-NMR, GPC, and FT-IR analysis that the imide oligomer A was mainly composed of the imide oligomer represented by formula (6). Moreover, the softening point of the imide oligomer A was 155°C.

(Synthesis Example 2 (Preparation of imide oligomer B))
1,4-Bis (2-(4-aminophenyl)-2-propyl) benzene 17.2 parts by weight Synthesis example except that 3-aminophenol (manufactured by Tokyo Chemical Industry Co., Ltd.) was changed to 21.8 parts by weight An imide oligomer B (imidation rate 96%) was obtained in the same manner as in 1.
It was confirmed by ¹ H-NMR, GPC, and FT-IR analysis that the imide oligomer B contained the imide oligomer represented by formula (7) as a main component. In addition, the softening point of the imide oligomer B was 134°C.

(Examples 1 to 8, Reference Example 9, Comparative Examples 1 and 2)
Each material was stirred and mixed so that the compounding ratios shown in Tables 1 and 2 were obtained, and curable resin compositions of Examples 1 to 8, Reference Example 9, and Comparative Examples 1 and 2 were prepared.
Each obtained curable resin composition was coated on a release PET film so as to have a thickness of 20 μm, and dried to obtain an adhesive film.
Further, each of the obtained curable resin compositions was coated on a polyimide film having a thickness of 25 μm (“Kapton 100H” manufactured by Toray DuPont Co., Ltd.) so that the thickness was 20 μm, and a polyimide film having an adhesive layer (cover ray film) was produced. The release PET film was peeled off from the obtained adhesive film, laminated with a laminator so as to have a thickness of 500 μm, and a rotary rheometer (manufactured by Rheologicala, "VAR-100") was used to heat at a rate of 10° C./ Tables 1 and 2 show the minimum melt viscosities measured under the conditions of min, frequency of 1 Hz, strain of 1%, and measurement temperature range of 60°C to 300°C.

<Evaluation>
The curable resin compositions, adhesive films, and coverlay films obtained in Examples , Reference Examples, and Comparative Examples were evaluated as follows. The results are shown in Tables 1 and 2.

(Prevention of leaching)
After opening a hole of 5 mmφ in the coverlay films obtained in Examples , Reference Examples, and Comparative Examples, a flexible copper-clad laminate having a copper wiring pattern of L/S = 100 µm/100 µm was subjected to 190 ° C. and 3 MPa. , under the conditions of 1 hour, and the length of the resin exuded inside the hole was measured as the exudation amount. "○" when there was no leaching (the amount of leaching was less than 0.2 mm), "△" when the amount of leaching was 0.2 mm or more and 0.5 mm or less, and the amount of leaching exceeded 0.5 mm. The leaching preventive property was evaluated as "x" when the case was unfavorable.

(Fillability)
The coverlay films obtained in Examples , Reference Examples, and Comparative Examples were thermocompression bonded to a flexible copper-clad laminate having a copper wiring pattern of L/S = 100 µm/100 µm under conditions of 190°C, 3 MPa, and 1 hour. Then, the presence or absence of voids between the copper wiring patterns was observed with an optical microscope.
"○" indicates that there were no voids between the wires and the filling was good. was observed, and the filling property was evaluated as "×" when the filling property was insufficient.

(Adhesiveness)
The PET film was peeled off from the adhesive films obtained in Examples , Reference Examples, and Comparative Examples, and a polyimide base material (manufactured by Toray DuPont Co., Ltd., manufactured by DuPont Toray Co., Ltd., "Kapton 200H", 50 μmt) was laminated. After hot pressing was performed under the conditions of 190° C., 3 MPa, and 1 hour to cure the adhesive layer, a test piece was obtained by cutting into a width of 1 cm.
Using a tensile tester ("UCT-500" manufactured by ORIENTEC), T-shaped peeling was performed at a peeling speed of 20 mm/min to measure the adhesive force.
"○" when the adhesive strength was 3.4 N / cm or more, "Δ" when it was 2.0 N / cm or more and less than 3.4 N / cm, and when it was less than 2.0 N / cm Adhesiveness was evaluated as "x".

(Heat resistance (glass transition temperature))
The PET film was peeled off from the adhesive films obtained in Examples , Reference Examples, and Comparative Examples, and laminated to a thickness of 500 μm using a laminator. The obtained laminate film was cured by heating at 190° C. for 30 minutes to prepare a cured product. Using a thermomechanical analyzer ("TMA/SS-6000" manufactured by Hitachi High-Tech Science Co., Ltd.), a load of 5 g, a heating rate of 10° C./min, and a sample length of 1 cm were measured from 0° C. to 300° C. for the resulting cured product. The inflection point of the SS curve obtained when the temperature was raised was determined as the glass transition temperature.

(Heat resistance (5% weight loss temperature))
The PET film was peeled off from the adhesive films obtained in Examples , Reference Examples, and Comparative Examples, and laminated to a thickness of 500 μm using a laminator. The obtained laminate film was cured by heating at 190° C. for 30 minutes to prepare a cured product.
The resulting cured product was measured using a thermogravimetry device ("TG/DTA6200" manufactured by Hitachi High-Tech Science), and the temperature range was from 30°C to 500°C, and the temperature was increased at a rate of 10°C/min to reduce the weight by 5%. Temperature was measured.

(Heat resistance (long-term heat resistance))
A test piece obtained in the same manner as in "(Adhesion)" above was subjected to heat treatment at 175°C for 1000 hours. The adhesive strength of the heat-treated test piece was measured by the same method as described in "(Adhesiveness)" above.
"○" when the adhesive strength was 3.4 N / cm or more, "Δ" when it was 2.0 N / cm or more and less than 3.4 N / cm, and when it was less than 2.0 N / cm The heat resistance (long-term heat resistance) was evaluated as "x".

(Flexibility)
A pattern of a bending resistance test sample disclosed in JIS C 6471 was prepared on a polyimide flexible copper-clad substrate, and the coverlay films obtained in Examples , Reference Examples, and Comparative Examples were applied thereto at 190 ° C., 3 MPa, 1 A test piece was obtained by thermocompression bonding under the condition of time. Using an FPC high-speed bending tester (manufactured by Shin-Etsu Engineering Co., Ltd.), the change in resistance value was measured under the conditions of a frequency of 1500 cpm, a stroke of 20 mm, a curvature of 2.5 mmR, and the outside of the coverlay. The bending characteristics were evaluated by utilizing the fact that when a crack such as a crack occurs in the copper foil due to bending, the volume decreases and the resistance increases. The number of times required for the resistance value to rise by 20% or more was measured, and if it was 300,000 times or more, "○", if it was 50,000 times or more and less than 300,000 times, "△", 50,000 times. The flex resistance was evaluated as “x” when the value was less than.

According to the present invention, it is possible to provide a curable resin composition which has excellent fluidity before curing and excellent adhesion, heat resistance, and bending resistance after curing. Further, according to the present invention, it is possible to provide a cured product of the curable resin composition, and an adhesive, an adhesive film, a coverlay film, and a printed wiring board using the curable resin composition. can.

Claims (10)

containing a thermosetting resin, a thermoplastic resin and an imide oligomer,
The imide oligomer has a reactive functional group capable of reacting with the thermosetting resin,
The reactive functional group is an acid anhydride group and/or a phenolic hydroxyl group,
The curable resin composition, wherein the thermoplastic resin contains a phenoxy resin. The curable resin composition according to claim 1, wherein the thermosetting resin contains an epoxy resin. 3. The curable resin according to claim 1, wherein the content of said thermoplastic resin in a total of 100 parts by weight of said thermosetting resin, said thermoplastic resin and said imide oligomer is 1 part by weight or more and 60 parts by weight or less. Composition. 4. The curable resin composition according to claim 1, 2 or 3 , wherein the imidization rate of said imide oligomer is 70% or more. 5. The curable resin composition according to claim 1, 2, 3 or 4 , which has a minimum melt viscosity of 5 kPa·s or more and 300 kPa·s or less. An adhesive comprising the curable resin composition according to claim 1, 2, 3, 4 or 5 . A cured product of the curable resin composition according to claim 1, 2, 3, 4 or 5 . An adhesive film using the adhesive according to claim 6 . A coverlay film comprising an adhesive layer made of the cured product according to claim 7 and an insulating film. A flexible printed wiring board comprising the coverlay film according to claim 9 .