Resin film, metal-clad laminate, circuit board, electronic device and electronic apparatus

Abstract

To provide a polyimide-based resin film that has heat resistance, and moisture absorptivity under a use environment and dielectric loss tangent in a high frequency band being sufficiently low.SOLUTION: A resin film contains polyimide having a constitutional unit including an aliphatic chain or an alicyclic skeleton as a resin component, and satisfies: (i) moisture absorptivity is less than 0.4 wt.%; (ii) dielectric constant at 10GHz when measured by a split-post dielectric resonator (SPDR) under the environment of the temperature 24 to 26°C and the humidity 45 to 55% is 3.1 or less and dielectric loss tangent is 0.0024 or less; and (iii) glass-transition temperature is 100°C or more. The film contains the constitutional unit including an aliphatic chain or an alicyclic skeleton within the range of 5 mol% or more 44 mol% or less for the total constitutional unit of polyimide included in the resin film.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a resin film and a metal-clad laminate that are useful as, for example, circuit board materials and have heat resistance, low dielectric properties, and low moisture absorption properties, as well as to a circuit board, an electronic device, and an electronic equipment that utilize them. [Background technology]

[0002] Polyimide is chemically and thermally stable, and has particularly excellent insulating properties, making it widely used as an insulating resin for circuit board materials. In recent years, with the increasing speed and capacity of communication in electronic devices, signals for transmitting and processing information have tended to be higher in frequency, and circuit board materials are also required to be able to accommodate these higher frequencies.

[0003] It is known that signal transmission loss increases as the frequency of signals flowing through circuits increases. Transmission loss is significantly affected by moisture in the insulating material, and the higher the dielectric loss tangent of the insulating material, the worse it becomes. Therefore, insulating materials that have low moisture absorption and a low dielectric loss tangent are required.

[0004] As a prior art technique for low-hygroscopic polyimide, for example, Patent Document 1 describes the use of a specific monomer composition to achieve low hygroscopicity. However, the dielectric loss tangent for high-frequency applications is not considered. Similarly, Patent Document 2 describes the use of a cycloolefin copolymer or a fluororesin mixed with polyimide to achieve low hygroscopicity, but the dielectric loss tangent is unclear. Furthermore, Patent Document 3 proposes a polyimide having high heat resistance, low dielectric loss tangent, and low moisture absorption, which is obtained by block polymerization of a non-thermoplastic block and a thermoplastic block. However, the moisture absorption rate is not sufficiently low, and the dielectric loss tangent is not sufficiently low. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 5374817 [Patent Document 2] Japanese Patent Publication No. 2023-1895 [Patent Document 3] Patent No. 6515180 Summary of the Invention [Problem to be solved by the invention]

[0006] In the prior art, there has been no resin film provided that has sufficient heat resistance, low moisture absorption, and a low dielectric loss tangent. Therefore, an object of the present invention is to provide a polyimide-based resin film that has heat resistance, a moisture absorption rate under the usage environment, and a dielectric loss tangent in the high frequency band that is sufficiently low. [Means for solving the problem]

[0007] The resin film of the present invention contains, as a resin component, a polyimide having a structural unit containing an aliphatic chain or an alicyclic skeleton. The resin film of the present invention satisfies the following conditions (i) to (iii): (i) moisture absorption rate of less than 0.4% by weight; (ii) A dielectric constant of 3.1 or less and a dielectric loss tangent of 0.0024 or less at 10 GHz when measured using a split post dielectric resonator (SPDR) in an environment of 24 to 26°C and 45 to 55% humidity; (iii) a glass transition temperature of 100°C or higher; Meet the following.

[0008] The resin film of the present invention may contain the aliphatic chain or alicyclic skeleton-containing structural unit in an amount of 5 mol % to 44 mol % based on all structural units of the polyimide contained in the resin film.

[0009] In the resin film of the present invention, the structural unit containing the aliphatic chain or alicyclic skeleton may be a structural unit derived from a dimer acid type diamine in which the two terminal carboxylic acid groups of a dimer acid are substituted with primary aminomethyl groups or amino groups.

[0010] The resin film of the present invention may have a value obtained by dividing the storage modulus at 40°C by the storage modulus at 260°C of 30 or less.

[0011] The metal-clad laminate of the present invention comprises an insulating resin layer consisting of a single layer or multiple layers, and a metal layer laminated on one or both sides of the insulating resin layer, and at least one layer of the insulating resin layer is composed of the resin film.

[0012] The circuit board of the present invention comprises an insulating resin layer consisting of a single layer or multiple layers, and a conductor circuit layer laminated on one or both sides of the insulating resin layer, and at least one layer of the insulating resin layer is composed of the resin film.

[0013] The electronic device of the present invention is characterized by comprising the circuit board described above.

[0014] An electronic device according to the present invention includes the circuit board. [Effects of the Invention]

[0015] By satisfying conditions (i) to (iii), the resin film of the present invention achieves both low moisture absorption and low dielectric loss tangent, while also possessing sufficient heat resistance. Furthermore, the present invention allows for a wide range of material selection, allowing for the formation of a form suited to the intended purpose. For example, the resin film can achieve transmission characteristics that allow for applications such as coating materials, in addition to rigid substrates and flexible printed circuit boards (FPCs) for high-frequency applications. It can also withstand heating during the mounting process and use in high-temperature environments. The resin film of the present invention is particularly suitable for use as a circuit board material for FPCs and other electronic devices requiring high-speed signal transmission. DETAILED DESCRIPTION OF THE INVENTION

[0016] Hereinafter, an embodiment of the present invention will be described.

[0017] [Resin film] A resin film according to one embodiment of the present invention contains, as a resin component, a polyimide (hereinafter sometimes referred to as an "aliphatic polyimide") having a structural unit (hereinafter sometimes referred to as "structural unit (I)") containing an aliphatic chain or an alicyclic skeleton. In the present invention, an "aliphatic chain" refers to a skeleton derived from a hydrocarbon such as an alkane, alkene, or alkyne having 10 or more carbon atoms, preferably in the range of 10 to 54 carbon atoms, and may be a straight chain or a branched chain, and may have a substituent. In addition, in the present invention, an "alicyclic skeleton" refers to a skeleton derived from a cyclic hydrocarbon such as a cycloalkane or cycloalkene, and may have a side chain or a substituent.

[0018] The resin film of the present invention may contain polyimides other than aliphatic polyimides or other resin components, but the aliphatic polyimide content is 25% by weight or more, preferably 40% by weight or more, more preferably 50% by weight or more, and most preferably 50 to 100% by weight of the total resin components. If the aliphatic polyimide content is 25% by weight or less of the total resin components, it becomes difficult to achieve low moisture absorption, low dielectric constant, and low dielectric loss tangent in the resin film.

[0019] The resin film of the present invention is a single layer, but may be laminated with any layer. That is, it may be in the form of a film (sheet) consisting of only an insulating resin containing the resin film of the present invention, or may be laminated directly or via any layer on a supporting substrate such as a metal foil such as copper foil, a glass plate, or a resin sheet. Note that by using a metal foil as the supporting substrate, the metal-clad laminate of the present invention described below can be produced.

[0020] The resin film of the present invention satisfies the following conditions (i) to (iii): (i) moisture absorption rate of less than 0.4% by weight; (ii) A dielectric constant of 3.1 or less and a dielectric loss tangent of 0.0024 or less at 10 GHz when measured using a split post dielectric resonator (SPDR) in an environment of 24 to 26°C and 45 to 55% humidity; (iii) a glass transition temperature of 100°C or higher; In other words, the resin film of the present invention has low moisture absorption, a low dielectric constant and a low dielectric loss tangent, yet is excellent in heat resistance.

[0021] Condition (i) means that the material is not easily affected by moisture in the environment. If the moisture absorption rate is 0.4% by weight or more, when the material is used in a circuit board such as an FPC, moisture can cause transmission loss and variations in dielectric properties. In other words, moisture in the environment can deteriorate the dielectric properties, leading to increased transmission loss in high-frequency signal transmission. Therefore, the moisture absorption rate is preferably 0.30% by weight or less, more preferably 0.25% by weight or less, and most preferably 0.20% by weight or less. The moisture absorption rate under condition (i) is the moisture absorption rate from a temperature of 23 to 26°C and humidity of 0% to a temperature of 23 to 26°C and humidity of 45 to 55%, and can be measured by the method described in the Examples below.

[0022] Condition (ii) indicates dielectric properties under a certain environment. By satisfying condition (ii), transmission loss of high-frequency signals in the GHz band can be suppressed in a typical usage environment expected for, for example, a circuit board. If the dielectric constant at 10 GHz exceeds 3.1 or the dielectric dissipation factor exceeds 0.0024, problems such as electrical signal loss are likely to occur in the transmission path of high-frequency signals when used in, for example, a circuit board such as an FPC. From this perspective, the dielectric constant at 10 GHz is preferably 3.0 or less, more preferably 2.9 or less. From the same perspective, the dielectric dissipation factor at 10 GHz is preferably 0.0022 or less, more preferably 0.0020 or less, particularly preferably 0.0018 or less, and most preferably 0.0015 or less. Condition (ii) refers to the dielectric constant and dielectric dissipation factor at 10 GHz measured using a split-post dielectric resonator (SPDR) after conditioning for 24 hours under conditions of temperature: 24 to 26°C and humidity: 45 to 55%, and can be measured by the method described in the Examples below.

[0023] By satisfying condition (i), the material becomes less susceptible to the influence of moisture in the environment, and the relative permittivity and dielectric loss tangent of condition (ii) are more likely to be maintained. However, condition (ii) is not realized by condition (i) alone, and it does not necessarily follow that condition (i) is always satisfied when condition (ii) is satisfied.

[0024] Condition (iii) indicates the heat resistance of the resin film. By satisfying condition (iii), the thermal stability of the resin film can be ensured. If the glass transition temperature is less than 100°C, heating, for example, during the manufacturing process of circuit boards or in the usage environment may increase the fragility and cause deformation, impair dimensional stability, or reduce handleability. From this perspective, the glass transition temperature is preferably 150°C or higher, and more preferably 200°C or higher. A resin film having a glass transition temperature of 100°C or higher facilitates handling, such as temperature control during transportation and storage of the resin film, and is also expected to suppress changes in physical properties and prevent adhesion in the actual usage environment when used in circuit boards, etc. The glass transition temperature can be measured by the method shown in the examples below.

[0025] (storage modulus) When the "storage modulus ratio" of the resin film of the present invention is defined as the value obtained by dividing the storage modulus at 40°C by the storage modulus at 260°C, the storage modulus ratio is preferably 30 or less, more preferably 25 or less, and even more preferably 20 or less. A storage modulus ratio of 30 or less means that a sudden decrease in the elastic modulus does not occur or is unlikely to occur at high temperatures around 260°C. Therefore, by having a storage modulus ratio of 30 or less, misalignment during mounting or resin outflow due to a sudden decrease in the elastic modulus at high temperatures is suppressed, and heat resistance that allows mounting in high-temperature environments can be achieved. Furthermore, the storage modulus of the resin film of the present invention at 40°C is 1.0 to 8.0 × 10 9 The range of 1.5 to 6.0 × 10 Pa is preferable. 9 It is more preferable that the storage modulus at 260°C is in the range of 0.1 to 3.0 × 10 9The range of Pa is preferably 0.2 to 2.0 × 10 9 It is more preferable that the temperature is in the range of Pa. The storage modulus can be measured by the method shown in the Examples below.

[0026] The resin film of the present invention contains the structural unit (I) at least in the aliphatic polyimide. It is effective for the resin film to contain the structural unit (I) in an amount of preferably 5 mol % or more, more preferably 8 mol % or more, and particularly preferably 10 mol % or more, based on the total structural units of the polyimide contained in the resin film (i.e., the total of the acid dianhydride residues and diamine residues of the aliphatic polyimide and other polyimides). Furthermore, the resin film preferably contains the structural unit (I) in an amount of 44 mol % or less, more preferably 40 mol % or less, and particularly preferably 35 mol % or less, based on the total structural units of the polyimide contained in the resin film. By including the structural unit (I) in this range, the resin film can achieve both low moisture absorption and a low dielectric constant and dielectric loss tangent. Furthermore, setting an upper limit on the content allows for the inclusion of other structural units to improve heat resistance. If the content of the structural unit (I) is less than 5 mol %, moisture absorption and dielectric properties may deteriorate, while if it exceeds 44 mol %, it becomes difficult to impart heat resistance.

[0027] The resin film of the present invention is · Selecting synthesis methods using polymer blends; and / or Selecting a specific structural unit (hereinafter sometimes referred to as "structural unit (II)") different from structural unit (I) and copolymerizing it with structural unit (I); This makes it possible to simultaneously satisfy conditions (i) to (iii). That is, in the present invention, the structural unit (I) containing an aliphatic chain or an alicyclic skeleton is primarily responsible for reducing moisture absorption and decreasing the dielectric constant and dielectric loss tangent, while the polymer structure produced by polymer blending and / or the structural unit (II) in the copolymer primarily contributes to the development of a high glass transition temperature.

[0028] Next, the polyimides (aliphatic polyimides and other polyimides) contained in the resin film will be described with reference to the tetracarboxylic acid anhydrides and diamines that are the raw materials.

[0029] Polyimide contains, as structural units, acid dianhydride residues and diamine residues. The acid dianhydride residue refers to a tetravalent group derived from a tetracarboxylic acid anhydride, and the diamine residue refers to a divalent group derived from a diamine.

[0030] [Structural unit (I) containing an aliphatic chain or alicyclic skeleton] In aliphatic polyimides, the aliphatic chain or alicyclic skeleton may be contained in either the acid dianhydride residue or the diamine residue, or may be contained in both. The inclusion of an aliphatic chain or alicyclic skeleton reduces the moisture absorption rate, dielectric constant, and dielectric loss tangent of the resin film, improving its dielectric properties.

[0031] When an aliphatic chain or an alicyclic skeleton is contained in the acid dianhydride residue, examples of tetracarboxylic acid anhydrides that can be used as the starting material include cyclohexane-1,2,4,5-tetracarboxylic acid dianhydride (H-PMDA), 1,2,3,4-cyclobutanetetracarboxylic acid dianhydride (CBDA), dicyclohexyl-3,4,3',4'-tetracarboxylic acid dianhydride (H-BPDA), and norbornane-2-spiro-α-cyclopentanone-α'-spiro-2"-norbornane-5,5",6,6"-tetracarboxylic acid dianhydride (CpODA). Among these, H-PMDA and H-BPDA are particularly preferred.

[0032] Furthermore, when an aliphatic chain or an alicyclic skeleton is contained in the diamine residue, examples of dimer acid type diamines that have the two terminal carboxylic acid groups of a dimer acid substituted with primary aminomethyl groups or amino groups, hexamethylenediamine, dodecanediamine, cyclohexanediamine, polyoxyalkyleneamine, 4,4-diaminodicyclohexylmethane, and the like can be used as the raw material diamine, and among these, dimer acid type diamines are particularly preferred.

[0033] The dimer acid diamine is a mixture containing the following component (a) as a main component and optionally containing components (b) and (c), and it is preferable to use a purified product in which the amounts of components (b) and (c) are controlled. (a) Dimer diamine (b) Monoamine compounds obtained by substituting the terminal carboxylic acid group of a monobasic acid compound having 10 to 40 carbon atoms with a primary aminomethyl group or an amino group. (c) Amine compounds obtained by substituting the terminal carboxylic acid group of a polybasic acid compound having a hydrocarbon group having 41 to 80 carbon atoms with a primary aminomethyl group or an amino group (excluding the dimer diamine).

[0034] The dimer diamine of component (a) refers to a diamine in which the two terminal carboxylic acid groups (—COOH) of a dimer acid are replaced with primary aminomethyl groups (—CH—NH) or amino groups (—NH). Dimer acids are known dibasic acids obtained by the intermolecular polymerization of unsaturated fatty acids. Their industrial production process is largely standardized in the industry, and they are obtained by dimerizing unsaturated fatty acids with 11 to 22 carbon atoms using a clay catalyst or the like. Industrially obtained dimer acids are primarily composed of a 36-carbon dibasic acid obtained by dimerizing 18-carbon unsaturated fatty acids such as oleic acid, linoleic acid, and linolenic acid. However, depending on the degree of purification, they may contain arbitrary amounts of monomer acid (18 carbon atoms), trimer acid (54 carbon atoms), and other polymerized fatty acids with 20 to 54 carbon atoms. Although double bonds remain after the dimerization reaction, in the present invention, dimer acids that have been further hydrogenated to reduce the degree of unsaturation are also included in the definition of dimer acids. The dimer diamine of component (a) can be defined as a diamine obtained by substituting the terminal carboxylic acid group of a dibasic acid compound having 18 to 54 carbon atoms, preferably 22 to 44 carbon atoms, with a primary aminomethyl group or an amino group.

[0035] Commercially available dimer acid diamines are available, such as Diamine H20 (manufactured by Okamura Oil Mills, Ltd.), and PRIAMINE 1073 (trade name), PRIAMINE 1074 (trade name), and PRIAMINE 1075 (trade name) manufactured by Croda Japan.

[0036] The polyimides (aliphatic polyimides and other polyimides) contained in the resin film of the present invention can be made from the tetracarboxylic anhydrides and diamine components exemplified below as raw materials.

[0037] (Tetracarboxylic acid anhydride) The tetracarboxylic anhydride used as a raw material for polyimide can be a tetracarboxylic anhydride commonly used in polyimide synthesis or its equivalent. For example, a tetracarboxylic anhydride represented by O(OC)2-X-(CO)2O is preferred, and examples thereof include those that give the following acid dianhydride residues. Each aromatic ring may have an optional substituent.

[0038] [ka]

[0039] The tetracarboxylic acid anhydrides can be used alone or in combination of two or more. Among these, pyromellitic dianhydride (PMDA), 4,4'-(hexafluoroisopropylidene)diphthalic anhydride (6FDA), 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA), 3,3',4,4'-benzophenonetetracarboxylic dianhydride (BTDA), 4,4'-(4,4'-isopropylidenediphenoxy)diphthalic anhydride (BPADA), naphthalene-2,6-diylbis(1, It is preferable to use one selected from the group consisting of bis(1,3-dioxo-1,3-dihydro-2-benzofuran-5-carboxylate) (DHNTME), bis(1,3-dioxo-1,3-dihydroisobenzofuran-5-carboxylic acid) 1,1'-biphenyl-4,4'-diyl (BP-TME), 3,3',4,4'-diphenylsulfonetetracarboxylic dianhydride (DSDA), 4,4'-oxydiphthalic dianhydride (ODPA), and the like.

[0040] (Diamine component) The diamine raw material can be a diamine commonly used in polyimide synthesis or its equivalent. For example, a diamine represented by H2N-Y-NH2 is preferred, and examples include diamines that give the following diamine residues. Each aromatic ring may have an optional substituent.

[0041] [ka]

[0042] The diamines can be used alone or in combination. Among these diamines, preferred examples include diaminodiphenyl ether (DAPE), 2,2'-dimethyl-4,4'-diaminobiphenyl (mTB), paraphenylenediamine (p-PDA), 1,3-bis(4-aminophenoxy)benzene (TPE-R), 1,3-bis(3-aminophenoxy)benzene (APB), 4,4'-bis(4-aminophenoxy)biphenyl (BAPB), 1,4-bis(4-aminophenoxy)benzene (TPE-Q), 2,2-bis[4-(4-aminophenoxy)phenyl]propane (BAPP), and 2,2-bis(trifluoromethyl)benzidine (TFMB).

[0043] [Polyimide synthesis] The polyimide contained in the resin film of the present invention is preferably produced by any one of the following production methods 1 to 3.

[0044] [Manufacturing method 1] In a first embodiment of polyimide synthesis using a polymer blending technique, a resin composition (V1) is used, which is obtained by mixing, for example, a resin solution containing the following component (A) or a precursor thereof with a resin solution containing the following precursor of component (B). (A) Soluble polyimide having a structural unit containing an aliphatic chain or an alicyclic skeleton (B) Heat-resistant polyimide Here, "heat-resistant polyimide" means a material having a storage modulus of 1.0 × 10 at 100°C. 8 The term "heat-resistant polyimide" refers to a polyimide having a storage modulus of 1.0 x 10 Pa or more. The glass transition temperature (Tg) of the heat-resistant polyimide is preferably 100°C or more. The heat-resistant polyimide is preferably a non-thermoplastic polyimide, but may also be a thermoplastic polyimide. Note that "non-thermoplastic polyimide" generally refers to a polyimide that does not soften or exhibit adhesiveness even when heated. In the present invention, however, a polyimide having a storage modulus of 1.0 x 10 at 30°C measured using a dynamic viscoelasticity measuring device (DMA) is used. 9The storage modulus is 1.0×10 Pa or more in the temperature range within the glass transition temperature + 30°C. 8 The term "thermoplastic polyimide" generally refers to a polyimide that can be softened by heating and solidified by cooling repeatedly, and has a clearly identifiable glass transition temperature (Tg). In the present invention, however, the term "thermoplastic polyimide" refers to a polyimide having a storage modulus of 1.0 × 10 Pa or more at 30°C as measured using a dynamic viscoelasticity measuring apparatus (DMA). 9 The storage modulus is 1.0×10 Pa or more in the temperature range within the glass transition temperature + 30°C. 8 This refers to polyimides that exhibit a modulus of less than Pa.

[0045] The method for preparing the resin composition (V1) includes the following steps 1 to 3a: Step 1: (A) preparing a resin solution of component (A) or a precursor thereof; Step 2: (B) preparing a resin solution of a precursor of component; Step 3a: a step of mixing a resin solution of component (A) or a precursor thereof with a resin solution of a precursor of component (B); may include:

[0046] Steps 1 and 2 can be carried out by reacting a tetracarboxylic anhydride and a diamine, which are raw materials for component (A) or component (B), in a solvent to produce a polyimide precursor (polyamic acid), and then, if necessary, performing ring closure by heating. The precursor of the heat-resistant polyimide of component (B) can be synthesized from a monomer generally used in the synthesis of polyimides, but it is preferable to use a monomer selected from tetracarboxylic anhydrides and diamines that give the residues exemplified in the above chemical formula as the raw material. This may have an aliphatic or alicyclic skeleton, and it is more preferable to use a monomer that is a raw material for the structural unit (II) described below.

[0047] In step 3a, the order of adding the resin solution of component (A) or its precursor and the resin solution of component (B) precursor is not important. That is, when preparing resin composition (V1), the resin solution of component (A) or its precursor may be added to the resin solution (varnish) of component (B) precursor and mixed, or the resin solution of component (B) precursor may be added to the resin solution (varnish) of component (A) or its precursor and mixed. The weight ratio (A / B) of component (A) or its precursor to component (B) precursor mixed in step 3a is preferably within the range of 10 / 90 to 90 / 10, and more preferably within the range of 15 / 85 to 85 / 15 from the viewpoint of reducing the dielectric constant and dielectric loss tangent. If the weight ratio (A / B) is less than 10 / 90, the effect of reducing the dielectric loss tangent of the resin film may not be fully realized. If it exceeds 90 / 10, the effect of imparting heat resistance to the resin film may not be fully realized.

[0048] The resin composition (V1) may contain a solvent such as an organic solvent. Since the component (A) or its precursor, and the precursor of the component (B) are both solvent-soluble and exhibit good solubility, the resin composition (V1) can be prepared as a polyimide solution (varnish) containing a solvent. In the present invention, the term "solvent" includes organic solvents and is used in a broader sense than organic solvents.

[0049] Examples of organic solvents that can be used in steps 1 to 3a include N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAc), N,N-diethylacetamide, N-methyl-2-pyrrolidone (NMP), 2-butanone, dimethyl sulfoxide (DMSO), hexamethylphosphoramide, N-methylcaprolactam, dimethyl sulfate, cyclohexanone, dioxane, tetrahydrofuran, γ-butyrolactone, diglyme, triglyme, cresol, methyl ethyl ketone, hexane, methanol, and ethanol. Mixtures of one or more solvents selected from these groups, and aromatic hydrocarbon solvents such as xylene and toluene, are preferably used in any ratio, and more preferably in a ratio of 50 to 100:0 to 50. The solvent content is not particularly limited, but is preferably adjusted so that the total concentration of the resin components is about 5 to 50 wt.% relative to the entire mixture of resin composition (V1).

[0050] [Manufacturing method 2] In a second embodiment of polyimide synthesis using polymer blending technology, component (A) or a precursor thereof and a precursor of component (B) are used as raw materials, and a resin composition (V2) containing component (C1), which is a reaction product of these, is produced. In this case, the method for preparing resin composition (V2) includes the following steps 1 to 3b: Step 1: (A) preparing a resin solution of component (A) or a precursor thereof; Step 2: (B) preparing a resin solution of a precursor of component; Step 3b: a step of mixing a resin solution of component (A) or a precursor thereof with a resin solution of a precursor of component (B) to synthesize component (C1) as a reaction product; may include:

[0051] Steps 1 and 2 can be carried out in the same manner as in Production Method 1.

[0052] In step 3b, the order of adding the resin solution of component (A) or its precursor and the resin solution of component (B) precursor is not important. The weight ratio (A / B) of component (A) or its precursor to component (B) precursor mixed in step 3b is preferably within the range of 10 / 90 to 90 / 10, and more preferably within the range of 15 / 85 to 85 / 15 from the viewpoint of lowering the dielectric constant and dielectric loss tangent. If the weight ratio (A / B) is less than 10 / 90, the effect of lowering the dielectric loss tangent of the resin film may not be fully realized. If it exceeds 90 / 10, the effect of imparting heat resistance to the resin film may not be fully realized.

[0053] The reaction product, component (C1), is a polymer in which a soluble polyimide or its precursor having a structural unit containing an aliphatic chain or alicyclic skeleton and a precursor of a heat-resistant polyimide are covalently linked. For example, in step 3b, a resin solution of component (A) or its precursor and a resin solution of a precursor of component (B) are mixed, and amide bonds are formed at the polymer chain ends of a portion of component (A) or its precursor and a portion of the precursor of component (B), thereby forming component (C1). The reaction conditions in step 3b are not particularly limited; for example, component (C1) can be synthesized by stirring at room temperature for approximately 10 to 72 hours. In this case, step 3b is preferably performed under an inert gas atmosphere. The formation of a new chemical bond, such as an amide bond, can be confirmed, for example, by nuclear magnetic resonance spectroscopy (NMR).

[0054] In the above steps 1 to 3b, when component (A) or its precursor has an acid terminal, a precursor of component (B) having an amine terminal is used; when component (A) or its precursor has an amine terminal, a precursor of component (B) having an acid terminal is used. In this way, by mixing polymers with different terminal functional groups, the reaction product (C1) can be efficiently synthesized. The term "acid terminal" refers to a state in which an acid anhydride group or a carboxyl group (-COOH) is present at the end of the polymer chain, and the term "amine terminal" refers to a state in which an amino group is present at the end of the polymer chain. The acid or amine terminals of component (A) or its precursor and the precursor of component (B) can be adjusted by the molar ratio of the tetracarboxylic anhydride component and the diamine component used as raw materials. For example, by setting the molar ratio of the tetracarboxylic anhydride component and the diamine component (tetracarboxylic anhydride component / diamine component) to less than 1.0, component (A) or its precursor and the precursor of component (B) can be amine-terminated. On the other hand, by setting the molar ratio of the tetracarboxylic acid anhydride component to the diamine component (tetracarboxylic acid anhydride component / diamine component) to a range of more than 1.0, it is possible to make the component (A) or its precursor and the precursor of the component (B) acid-terminated.

[0055] The resin composition (V2) obtained by steps 1 to 3b may contain, in addition to the reactant component (C1), component (A) or its precursor and / or a precursor of component (B). The resin composition (V2) may also contain a solvent such as an organic solvent. In producing the resin composition (V2), the same solvents as those described for the resin composition (V1) can be used in steps 1 to 3b.

[0056] [Manufacturing method 3] In aliphatic polyimides, the structural unit (II) contained in combination with the structural unit (I) to achieve desired physical properties is a structural unit that does not have an aliphatic chain or an alicyclic skeleton, and may be an acid dianhydride residue, a diamine residue, or both an acid dianhydride residue and a diamine residue. The structural unit (II) is not limited to one type, and it is preferable to combine two or more types.

[0057] Examples of the structural unit (II) include an acid dianhydride residue containing one or more selected from an ester skeleton, an alkyl halide skeleton, a biphenyl skeleton, and a benzophenone skeleton, and a diamine residue containing one or more selected from a biphenyl skeleton, a phenyl ether skeleton, and an ester skeleton. The inclusion of the structural unit (II) increases the rigidity of the aliphatic polyimide, thereby improving the heat resistance of the resin film. It is effective for the aliphatic polyimide to contain the structural unit (II) in an amount of preferably 30 mol% or more, more preferably 40 mol% or more, and most preferably 45 mol% or more, based on the total amount (total) of the acid dianhydride residues and the diamine residues. Furthermore, the aliphatic polyimide preferably contains the structural unit (II) in an amount of 95 mol% or less, more preferably 85 mol% or less, and most preferably 80 mol% or less, based on the total amount (total) of the acid dianhydride residues and the diamine residues. By including the structural unit (II) in such a range, the glass transition temperature of the aliphatic polyimide can be increased, thereby imparting heat resistance to the resin film.

[0058] Examples of acid dianhydride residues having an ester skeleton include naphthalene-2,6-diyl bis(1,3-dioxo-1,3-dihydro-2-benzofuran-5-carboxylate) (DHNTME), p-biphenylene bis(trimellitic acid monoester dihydrate) (BP-TME), 2,2',3,3',5,5'-hexamethyl[1,1'-biphenyl]-4,4'-diyl bis(1,3-dioxo-1,3-dihydro-2-benzofuran-5-carboxylate) (TMPBP-T Preferred are acid dianhydride residues derived from tetracarboxylic acid anhydrides such as 1,3-dihydro-1,3-dioxo-5,5'-(3,3'-dimethyl[1,1'-biphenyl]-4,4'-diyl) ester, 1,3-dihydro-1,3-dioxo-5,5'-(3,3',5,5'-tetramethyl[1,1'-biphenyl]-4,4'-diyl) ester, and 1,4-phenylenebis(trimellitic acid monoester) dianhydride (TAHQ), and among these, DHNTME is particularly preferred.

[0059] Preferred examples of acid dianhydride residues having an alkyl halide skeleton include acid dianhydride residues derived from tetracarboxylic acid anhydrides such as 4,4'-(hexafluoroisopropylidene)diphthalic anhydride (6FDA), 5,5'-(((perfluoropropane-2,2-diyl)bis(4,1-phenylene))bis(oxy))bis(isobenzofuran-1,{{9}}dione) (6F-BPADA), 1,4-bis(trifluoromethyl)-2,3,5,6-benzenetetracarboxylic acid dianhydride (P6FDA), and 1-(trifluoromethyl)-2,3,5,6-benzenetetracarboxylic acid dianhydride (P3FDA), and among these, 6FDA is particularly preferred.

[0060] Preferred examples of diamine residues having a biphenyl skeleton include diamine residues derived from diamines such as 2,2'-dimethyl-4,4'-diaminobiphenyl (mTB), 2,2'-diethyl-4,4'-diaminobiphenyl (m-EB), 2,2'-diethoxy-4,4'-diaminobiphenyl (m-EOB), 2,2'-dipropoxy-4,4'-diaminobiphenyl (m-POB), 2,2'-di-n-propyl-4,4'-diaminobiphenyl (m-NPB), 2,2'-divinyl-4,4'-diaminobiphenyl (VAB), 4,4'-diaminobiphenyl, and 4,4'-diamino-2,2'-bis(trifluoromethyl)biphenyl (TFMB), and among these, mTB is particularly preferred.

[0061] In order to impart desired physical properties to the resin film, the content ratio of each residue in the aliphatic polyimide is preferably such that, when the structural unit (I) is in the range of 5 to 44 mol % relative to 100 mol % of all structural units constituting the aliphatic polyimide, the acid dianhydride residue having an ester skeleton is in the range of 5 to 50 mol %, the acid dianhydride residue having an alkyl halide skeleton is in the range of 5 to 30 mol %, and the diamine residue having a biphenyl skeleton is in the range of 10 to 50 mol %.

[0062] Furthermore, when the structural unit (I) is a diamine residue derived from a dimer acid diamine (hereinafter sometimes referred to as a "DDA residue"), a specific example of the most preferred structural unit (II) is a combination of an acid dianhydride residue derived from DHNTME (hereinafter sometimes referred to as a "DHNTME residue"), an acid dianhydride residue derived from 6FDA (hereinafter sometimes referred to as a "6FDA residue"), and a diamine residue derived from mTB (hereinafter sometimes referred to as an "mTB residue"). In this case, the most preferred content ratios of each residue are, relative to 100 mol% of all structural units constituting the aliphatic polyimide, 25 to 40 mol% for DHNTME residues, 10 to 25 mol% for 6FDA residues, 5 to 44 mol% for DDA residues, and 6 to 45 mol% for mTB residues.

[0063] When copolymerizing the structural unit (I) and the structural unit (II), it is preferable to use a resin composition (V3) containing a polyimide or its precursor. Resin composition (V3) can be produced by reacting the raw materials, tetracarboxylic anhydride and diamine, in a solvent to produce a precursor polyamic acid, followed by heating to ring-close (imidization) as needed. For example, a precursor polyamic acid solution can be obtained by dissolving approximately equimolar amounts of tetracarboxylic anhydride and diamine in an organic solvent and stirring at a temperature within the range of 0 to 100°C for 30 minutes to 1 week to cause a polymerization reaction. Alternatively, a polyimide solution can be obtained by heating and stirring highly solvent-soluble compounds, such as those containing dimer acid-type diamines, to approximately 150 to 240°C for 2 to 10 hours. In either case, the reaction components, tetracarboxylic anhydride and diamine, can be used alone or in combination of two or more. The order and timing of addition to the reaction vessel are not limited, but it is preferable to add and dissolve at least one diamine component in the solvent before the tetracarboxylic anhydride. Alternatively, two or more polyamic acid solutions and / or polyimide solutions may be reacted in separate reaction vessels and then mixed together, or may be reacted in a single reaction vessel. The structural units (I) and (II) may be present as blocks or randomly.

[0064] In the polymerization reaction, the reaction components can be dissolved in an organic solvent to a concentration of 5 to 50% by weight, preferably 10 to 35% by weight. The organic solvent used in the polymerization reaction can be preferably one of the organic solvents described for resin composition (V1). The amount of organic solvent used is not particularly limited, but it is preferable to adjust the amount used so that the concentration of the polyamic acid and / or polyimide obtained by the polymerization reaction is about 5 to 50% by weight. Resin composition (V3) can also contain a solvent such as the organic solvent described for resin composition (V1).

[0065] The resin compositions (V1), (V2), and (V3) obtained by the above-mentioned Production Methods 1 to 3 all contain an aliphatic polyimide or a precursor thereof. The aliphatic polyimide or its precursor or the heat-resistant polyimide precursor in the resin compositions (V1), (V2), and (V3) may have an amide acid structure or may contain an imide structure, but preferably contains at least an imide structure, and may contain both an amide acid structure and an imide structure. Furthermore, the reactant component (C1) may be covalently bonded to a molecule having an amide acid skeleton and a molecule having an imide skeleton.

[0066] [Manufacturing method of resin film] The resin film of the present invention is produced by using resin composition (V1), (V2), or (V3), and optionally imidizing the polyimide precursor in the resin composition and forming it into a film. There are no particular limitations on the method for producing the resin film of the present invention, and known techniques can be used. For example, the resin film is preferably produced by repeatedly applying resin composition (V1), (V2), or (V3) to a supporting substrate and drying the composition once or multiple times. There are no particular limitations on the method for applying the resin composition to the supporting substrate, and it can be applied using, for example, a coater such as a comma coater, a die coater, a knife coater, or a lip coater.

[0067] When the resin film of the present invention is produced using the resin composition (V1), the following components (A) and (B) are used: (A): a soluble polyimide having a structural unit containing an aliphatic chain or an alicyclic skeleton; and, (B): Heat-resistant polyimide, The resin film contains the above as a resin component. Component (A) is an "aliphatic polyimide."

[0068] When the resin film of the present invention is produced using the resin composition (V2), the following components (A), (B) and (C2) are used; (A): a soluble polyimide having a structural unit containing an aliphatic chain or an alicyclic skeleton; (B): Heat-resistant polyimide, and, (C2): a polyimide in which a soluble polyimide having a structural unit containing an aliphatic chain or an alicyclic skeleton and a heat-resistant polyimide are linked by a covalent bond; The resulting resin film contains the above as resin components. Of these, components (A) and (C2) are "aliphatic polyimides." Note that component (C2) is formed by imidizing the amide acid skeleton of component (C1), which is the reaction product of step 3b described above.

[0069] Component (C2) is a reaction product between components (A) and (B) (including products that are imidized after reacting at the precursor stage), and is formed by a covalent bond between a reactive functional group of component (A) and a reactive functional group of component (B). For example, the reactive functional groups of components (A) and (B) may be linked by an amide bond. Specifically, component (C2) may have either a block structure in which the acid end of the soluble polyimide of component (A) is linked to the amine end of the heat-resistant polyimide of component (B), or a block structure in which the amine end of the soluble polyimide of component (A) is linked to the acid end of the heat-resistant polyimide of component (B). This block structure allows component (C2) to have low moisture absorption, low dielectric constant, low dielectric dissipation factor, and a high glass transition temperature when formed into a film. Examples of the covalent bond include a single bond (carbon-carbon), an amide bond, an ester bond, an imino bond, an imide bond, an ether bond, a sulfide bond, etc. In addition to the examples given here, general covalent bonds may also be included.

[0070] When the resin film of the present invention is produced using resin composition (V3), the resulting resin film contains an aliphatic polyimide in which the structural unit (I) and the structural unit (II) are copolymerized in a block or random manner.

[0071] The resin film of the present invention is preferably produced, for example, by coating a support substrate with a resin composition, drying the composition once or multiple times, and then, if necessary, imidizing the polyamic acid contained in the coating film. The imidization method is not particularly limited, and a heat treatment, such as heating at a temperature in the range of 80 to 400°C for 1 to 24 hours, is preferably employed. Heating may be performed at a constant temperature, or the temperature may be changed during the process. In the resin film of the present invention, aliphatic polyimides and heat-resistant polyimides are most preferably fully imidized. However, a portion of the polyimide may be in the form of an amic acid. The imidization rate can be determined by measuring the infrared absorption spectrum of the polyimide thin film using a Fourier transform infrared spectrophotometer (commercially available: JASCO Corporation, trade name: FT / IR620) by the single-reflection ATR method, and determining the imidization rate at 1015 cm. -1 Based on the benzene ring absorber near 1780cm -1 It can be calculated from the absorbance of the C=O stretching derived from the imide group. By using a metal foil as the supporting substrate, the metal-clad laminate of the present invention described below can be produced.

[0072] When the resin film of the present invention contains component (A) and component (B), the weight ratio (A / B) of component (A) to component (B) is preferably within the range of 10 / 90 to 90 / 10, more preferably within the range of 15 / 85 to 85 / 15. If the weight ratio (A / B) is less than 10 / 90, the effect of lowering the dielectric tangent may not be fully exerted, and if the weight ratio (A / B) exceeds 90 / 10, the effect of imparting heat resistance to the resin film may not be fully exerted.

[0073] Furthermore, when the resin film of the present invention contains components (A), (B), and (C2), the weight ratio of component (C2) to the total of components (A), (B), and (C2) [C2 / (A+B+C2)] is preferably 0.2 or more, more preferably 0.4 or more, and most preferably 0.6 or more. If the weight ratio [C2 / (A+B+C2)] is less than 0.2, the presence of unreacted components (A) and (B) increases the terminal groups of each component, resulting in increased polarity and a deterioration in the dielectric loss tangent.

[0074] When the resin film of the present invention contains the structural unit (I) and the structural unit (II), the weight ratio (I / II) of the structural unit (I) to the structural unit (II) is preferably within the range of 5 / 95 to 90 / 10, and more preferably within the range of 10 / 90 to 85 / 15. If the weight ratio (I / II) is less than 5 / 95, the effect of lowering the dielectric tangent may not be fully exerted, and if the weight ratio (I / II) exceeds 90 / 10, the effect of imparting heat resistance to the resin film may not be fully exerted.

[0075] [Optional ingredients] The resin film of the present invention may contain optional components such as inorganic fillers, organic fillers, plasticizers, curing accelerators, coupling agents, pigments, and flame retardants, as long as the components do not impair the effects of the invention. Examples of inorganic fillers include silicon dioxide, aluminum oxide, beryllium oxide, niobium oxide, titanium oxide, magnesium oxide, boron nitride, aluminum nitride, silicon nitride, aluminum fluoride, calcium fluoride, magnesium fluoride, potassium silicofluoride, and metal phosphinates. These may be used alone or in combination. Furthermore, resin components other than the aliphatic polyimide and heat-resistant polyimide may be added as optional components, as long as the components do not impair the effects of the invention.

[0076] The thickness of the resin film of the present invention is not particularly limited and can be appropriately set depending on the intended use, but when used as a circuit board material, it is preferably in the range of 2 to 150 μm, more preferably in the range of 5 to 75 μm, and most preferably in the range of 15 to 55 μm. If the resin film is less than 2 μm thick, problems such as wrinkles may occur during transport during production of the resin film, or sufficient toughness may not be exhibited, making it impossible to obtain a self-supporting film. On the other hand, if the resin film thickness exceeds 150 μm, there is a risk of a decrease in productivity of the resin film.

[0077] The resin film of the present invention is useful as a material for insulating layers in circuit boards and the like, since it has both a low moisture absorption rate and a low dielectric loss tangent and also has heat resistance sufficient for practical use.

[0078] [Metal-clad laminate] A metal-clad laminate according to one embodiment of the present invention comprises an insulating resin layer consisting of a single layer or multiple layers and a metal layer laminated on one or both surfaces of the insulating resin layer, with at least one insulating resin layer being made of the resin film of the present invention. Circuit boards such as FPCs can be manufactured by processing one or more metal layers of the metal-clad laminate into a pattern using a conventional method to form a wiring layer (conductor circuit layer). The metal-clad laminate of the present invention may also include any other layers.

[0079] The material of the metal layer is not particularly limited, but examples thereof include copper, stainless steel, iron, nickel, beryllium, aluminum, zinc, indium, silver, gold, tin, zirconium, tantalum, titanium, lead, magnesium, manganese, and alloys thereof. Among these, copper or copper alloys are particularly preferred. The material of the wiring layer in the circuit board of this embodiment, which will be described later, is the same as that of the metal layer.

[0080] The method for laminating with a metal layer is not particularly limited, and examples thereof include, as described above, a method in which a metal foil is used as a supporting substrate and a polyimide-based resin composition is applied thereto, a method in which the resin film is laminated and pressure-bonded, and a method in which a metal layer is formed on the resin film by vapor deposition.

[0081] The thickness of the metal layer is not particularly limited, but when a metal foil such as copper foil is used, it is preferably 35 μm or less, and more preferably in the range of 5 to 25 μm. From the viewpoint of production stability and handling, the lower limit of the thickness of the metal foil is preferably 5 μm. When copper foil is used, it may be rolled copper foil or electrolytic copper foil. Furthermore, commercially available copper foil may be used as the copper foil.

[0082] The surface roughness of the metal layer is not particularly limited, but from the viewpoint of ensuring adhesion to the adhesive layer while reducing conductor loss, it is preferable that the metal layer has a roughened surface with a maximum height (Rz) in the range of 0.3 to 1.5. Furthermore, the metal foil may be subjected to a surface treatment, for example, with siding, aluminum alcoholate, aluminum chelate, silane coupling agent, etc., for the purpose of, for example, rust prevention treatment or improving adhesive strength.

[0083] [Circuit board] A circuit board according to one embodiment of the present invention is formed by wiring the metal layer of the metal-clad laminate. That is, the circuit board of the present invention comprises an insulating resin layer consisting of a single layer or multiple layers and a conductor circuit layer laminated on one or both surfaces of the insulating resin layer, at least one layer of which is made of the resin film of the present invention. Note that the circuit board of the present invention may include any layer other than those described above, and may also include a coverlay film that covers the wiring layer.

[0084] [Electronic Devices and Electronic Equipment] The electronic devices and electronic equipment according to the embodiments of the present invention include the above-described circuit board. Examples of the electronic devices according to the present embodiments include display devices such as liquid crystal displays, organic EL displays, and electronic paper, as well as organic EL lighting, solar cells, touch panels, camera modules, inverters, converters, and components thereof. Examples of the electronic equipment include hard disk drives, DVDs, mobile phones, smartphones, tablet devices, automotive electronic control units (ECUs), and power control units (PCUs). Circuit boards are preferably used in these electronic devices and electronic equipment as components such as wiring for moving parts, cables, and connectors. [Example]

[0085] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. In the following examples, various measurements and evaluations were carried out according to the following methods unless otherwise specified.

[0086] [Moisture absorption rate measurement] 90 to 110 mg of each resin film from the Examples and Comparative Examples was taken as a sample, and the moisture absorption rate was measured using a high-sensitivity differential thermobalance with a humidity control device (manufactured by Netsch Japan, product name: STA 2500 Regulus, HC9700). The measurement method involved holding the sample in an atmosphere of 23°C temperature and 0% RH humidity until the weight change was sufficiently stabilized, with the sample weight at that time being designated w1, and then holding the sample in an atmosphere of 23°C temperature and 50% RH humidity until the weight change was sufficiently stabilized, with the sample weight at that time being designated w2, and the value calculated using the following formula 1 was defined as the moisture absorption rate. 100×(w2−w1) / w1 (Formula 1) The moisture absorption rate was evaluated as follows: 0.4% by weight or more was marked "x", less than 0.4% by weight was marked "◯", and less than 0.25% by weight was marked "◎".

[0087] [Measurement of dielectric loss tangent] Each film of the Examples and Comparative Examples was left as a sample for 24 hours under conditions of temperature: 24 to 26°C and humidity: 45°C to 55% RH, and then the relative permittivity and dielectric loss tangent at 10 GHz were measured using a vector network analyzer (manufactured by Agilent, product name: E8363C) and an SPDR resonator.

[0088] [Measurement of storage modulus and glass transition temperature (Tg)] The storage modulus was measured by cutting a 5mm x 20mm piece of polyimide film or cured resin sheet and using a dynamic viscoelasticity analyzer (DMA: manufactured by TA Instruments, product name: RSA-G2) to stepwise heat the material from 30°C to 380°C at a heating rate of 4°C / min and a frequency of 1Hz. The peak value of Tan δ at the maximum temperature during the measurement was defined as Tg, and the storage modulus at 40°C divided by the storage modulus at 260°C was defined as the storage modulus ratio.

[0089] [Measurement of copper foil surface roughness (Rz)] The sample was cut into approximately 10 mm square pieces, fixed to a sample stage with double-sided tape, and irradiated with soft X-rays to remove static electricity from the copper foil surface. The surface roughness was then measured. The maximum height (Rz) of the copper foil surface was measured using a scanning probe microscope (AFM, manufactured by Bruker AXS, product name: Dimension Icon SPM) under the following measurement conditions. Measurement mode; Tapping mode Measurement area: 1 μm x 1 μm Scan speed: 1Hz Probe: Olympus AC160 Analysis software: NanoScope Analysis

[0090] The abbreviations used in the examples represent the following compounds. PMDA: Pyromellitic dianhydride 6FDA: 4,4'-(hexafluoroisopropylidene)diphthalic anhydride BPDA: 3,3',4,4'-biphenyltetracarboxylic dianhydride BTDA: 3,3',4,4'-benzophenonetetracarboxylic dianhydride BPADA: 4,4'-(4,4'-isopropylidenediphenoxy)diphthalic anhydride DHNTME: Naphthalene-2,6-diyl bis(1,3-dioxo-1,3-dihydro-2-benzofuran-5-carboxylate), CAS number: 115383-00-1 DDA: a mixture mainly composed of dimer diamine having 36 carbon atoms (manufactured by Croda Japan Co., Ltd., trade name: PRIAMINE 1075, amine value: 209 mg KOH / g) mTB: 2,2'-dimethyl-4,4'-diaminobiphenyl TPE-R: 1,3-bis(4-aminophenoxy)benzene BAPP: 2,2-bis[4-(4-aminophenoxy)phenyl]propane ODPA: 4,4'-oxydiphthalic dianhydride NMP: N-methyl-2-pyrrolidone

[0091] (Synthesis Example 1) In a reaction vessel under a nitrogen stream, 12.5 g of 6FDA (0.028 mol), 13.7 g of DDA (0.026 mol), 36.6 g of NMP, and 24.4 g of xylene were charged and mixed thoroughly at 40 °C for 1 hour. The mixture was then heated to 190 °C and heated and stirred for 5 hours. An amount of xylene was added to obtain a resin solution 1-1 such that the solids concentration after polymerization was 30 wt%. In a separate reaction vessel, 10.5 g of mTB (0.049 mol) and 82.5 g of NMP were charged under a nitrogen stream and dissolved by stirring at room temperature. Next, 13.8 g of BPDA (0.047 mol) and 55.0 g of NMP were added, and the mixture was then polymerized by stirring at room temperature for 2 days to obtain a resin solution 1-2 with a solids concentration of 15 wt%. To the resin solution 1-2, the entire amount of the resin solution 1-1, 25.8 g of NMP, and 61.3 g of xylene were added, and the mixture was stirred at room temperature for 2 days to prepare a resin solution 1-3 having a solid content of 15 wt %.

[0092] (Synthesis Example 2) In a reaction vessel under a nitrogen stream, 13.5 g of BPADA (0.026 mol), 12.7 g of DDA (0.024 mol), 36.7 g of NMP, and 24.5 g of xylene were charged and mixed thoroughly at 40 ° C for 1 hour. The mixture was then heated to 190 ° C, heated and stirred for 5 hours, and an amount of xylene was added to obtain a resin solution 2-1 such that the solids concentration after polymerization was 30 wt%. In a separate reaction vessel, 7.4 g of mTB (0.035 mol) and 81.1 g of NMP were charged under a nitrogen stream and dissolved by stirring at room temperature. Next, 16.5 g of DHNTME (0.032 mol) and 54.1 g of NMP were added, and the mixture was then polymerized by stirring at room temperature for 1 week to obtain a resin solution 2-2 with a solids concentration of 15 wt%. To the resin solution 2-2, the entire amount of the resin solution 2-1, 26.8 g of NMP, and 60.7 g of xylene were added, and the mixture was stirred at room temperature for 2 days to prepare a resin solution 2-3 having a solid content of 15 wt %.

[0093] (Synthesis Example 3) A reaction vessel was charged with 12.5 g of 6FDA (0.028 mol), 13.7 g of DDA (0.026 mol), 36.6 g of NMP, and 24.4 g of xylene under a nitrogen stream. The mixture was thoroughly mixed at 40 °C for 1 hour, then heated to 190 °C and stirred for 5 hours. An amount of xylene was added to obtain a resin solution 3-1 such that the solids concentration after polymerization was 30 wt%. In a separate reaction vessel, 12.5 g of TPE-R (0.043 mol) and 82.2 g of NMP were charged under a nitrogen stream and dissolved by stirring at room temperature. Next, 11.7 g of BPDA (0.040 mol) and 54.8 g of NMP were added, and the mixture was polymerized by stirring at room temperature for 1 week to obtain a resin solution 3-2 with a solids concentration of 15 wt%. To the resin solution 3-2, the entire amount of the resin solution 3-1, 26.0 g of NMP, and 61.1 g of xylene were added, and the mixture was stirred at room temperature for 2 days to prepare a resin solution 3-3 having a solid content of 15 wt %.

[0094] (Synthesis Example 4) In a reaction vessel under a nitrogen stream, 12.5 g of 6FDA (0.028 mol), 13.7 g of DDA (0.026 mol), 36.6 g of NMP, and 24.4 g of xylene were charged and mixed thoroughly at 40 °C for 1 hour. The mixture was then heated to 190 °C and heated and stirred for 5 hours. An amount of xylene was added to obtain a resin solution 4-1 such that the solids concentration after polymerization was 30 wt%. In a separate reaction vessel, 7.4 g of mTB (0.035 mol) and 81.1 g of NMP were charged under a nitrogen stream and dissolved by stirring at room temperature. Next, 17.0 g of DHNTME (0.033 mol) and 54.1 g of NMP were added, and the mixture was then polymerized by stirring at room temperature for 2 days to obtain a resin solution 4-2 with a solids concentration of 15 wt%. To the resin solution 4-2, the entire amount of the resin solution 4-1, 26.5 g of NMP, and 60.6 g of xylene were added, and the mixture was stirred at room temperature for 2 days to prepare a resin solution 4-3 having a solid content of 15 wt %.

[0095] (Synthesis Example 5) In a reaction vessel under a nitrogen stream, 6.2 g of 6FDA (0.014 mol), 6.8 g of DDA (0.013 mol), 18.3 g of NMP, and 12.2 g of xylene were charged and mixed thoroughly at 40 °C for 1 hour. The mixture was then heated to 190 °C and heated and stirred for 5 hours. An amount of xylene was added to obtain a resin solution 5-1 such that the solids concentration after polymerization was 30 wt%. In a separate reaction vessel, 11.0 g of mTB (0.052 mol) and 82.5 g of NMP were charged under a nitrogen stream and dissolved by stirring at room temperature. Next, 24.7 g of DHNTME (0.049 mol) and 55.0 g of NMP were added, and the mixture was then polymerized by stirring at room temperature for 2 days to obtain a resin solution 5-2 with a solids concentration of 20 wt%. To the resin solution 5-2, the entire amount of the resin solution 5-1, 32.3 g of NMP, and 70.8 g of xylene were added, and the mixture was stirred at room temperature for 2 days to prepare a resin solution 5-3 having a solid content of 15 wt %.

[0096] (Synthesis Example 6) A reaction vessel was charged with 18.7 g of 6FDA (0.042 mol), 20.5 g of DDA (0.038 mol), 54.9 g of NMP, and 36.6 g of xylene under a nitrogen stream. The mixture was thoroughly mixed at 40 °C for 1 hour, then heated to 190 °C and stirred for 5 hours. An amount of xylene was added to obtain a resin solution 6-1 such that the solids concentration after polymerization was 30 wt%. In a separate reaction vessel, 3.7 g of mTB (0.017 mol) and 40.6 g of NMP were charged under a nitrogen stream and dissolved by stirring at room temperature. Next, 8.2 g of DHNTME (0.016 mol) and 27.0 g of NMP were added, and the mixture was stirred at room temperature for 2 days to carry out the polymerization reaction. A resin solution 6-2 with a solids concentration of 15 wt% was prepared. To the resin solution 6-2, the entire amount of the resin solution 6-1, 80.3 g of NMP, and 50.3 g of xylene were added, and stirring was continued at room temperature for 2 days to prepare a resin solution 6-3 with a solid concentration of 15 wt %.

[0097] (Synthesis Example 7) A reaction vessel was charged with 11.0 g of 6FDA (0.025 mol), 13.7 g of DDA (0.026 mol), 34.6 g of NMP, and 23.1 g of xylene under a nitrogen stream. The mixture was thoroughly mixed at 40 °C for 1 hour, then heated to 190 °C and stirred for 5 hours. An amount of xylene was added to obtain a resin solution 7-1 such that the solids concentration after polymerization was 30 wt%. In a separate reaction vessel, 7.4 g of mTB (0.035 mol) and 81.1 g of NMP were charged under a nitrogen stream and dissolved by stirring at room temperature. Next, 16.5 g of DHNTME (0.032 mol) and 54.1 g of NMP were added, and the mixture was stirred at room temperature for 2 days to carry out the polymerization reaction, obtaining a resin solution 7-2 with a solids concentration of 15 wt%. The entire amount of the resin solution 7-1, 22.9 g of NMP, and 59.5 g of xylene were added to the resin solution 7-2 and stirred to prepare a resin solution 7-3 having a solid content concentration of 15 wt %.

[0098] (Synthesis Example 8) Into a reaction vessel under a nitrogen stream were charged 4.2 g of DDA (0.008 mol), 2.3 g of mTB (0.011 mol), 3.4 g of 6FDA (0.008 mol), 5.4 g of DHNTME (0.011 mol), 59.4 g of NMP, and 25.5 g of xylene, and the mixture was stirred at room temperature for 2 days to carry out a polymerization reaction, thereby preparing resin solution 8 with a solids concentration of 15 wt%.

[0099] (Synthesis Example 9) In a reaction vessel under a nitrogen stream, 10.6 g of BPDA (0.036 mol), 14.0 g of DDA (0.026 mol), 1.4 g of mTB (0.007 mol), 36.3 g of NMP, and 24.2 g of xylene were charged and mixed thoroughly at 40 °C for 1 hour. The mixture was then heated to 190 °C and heated and stirred for 5 hours. An amount of xylene was added to obtain a resin solution 9-1 such that the solids concentration after polymerization was 30 wt%. In a separate reaction vessel, 12.3 g of mTB (0.058 mol) and 82.2 g of NMP were charged under a nitrogen stream and dissolved by stirring at room temperature. Next, 11.8 g of PMDA (0.054 mol) and 54.8 g of NMP were added, and the mixture was then polymerized by stirring at room temperature for 1 week to obtain a resin solution 9-2 with a solids concentration of 15 wt%. To the resin solution 9-2, the entire amount of the resin solution 9-1, 25.5 g of NMP, and 61.0 g of xylene were added, and the mixture was stirred at room temperature for 2 days to prepare a resin solution 9-3 having a solid content of 15 wt %.

[0100] (Synthesis Example 10) Into a reaction vessel under a nitrogen stream, 13.2 g of DDA (0.025 mol), 11.5 g of 6FDA (0.026 mol), 33.9 g of NMP, and 22.6 g of xylene were charged and mixed well at 40°C for 1 hour. After that, the temperature was raised to 190°C and the mixture was heated and stirred for 5 hours. Xylene was added in an amount such that the solid concentration after polymerization would be 30 wt% to prepare resin solution 10.

[0101] (Synthesis Example 11) A reaction vessel was charged with 68.5 g of DDA (0.128 mol), 5.8 g of BAPP (0.014 mol), 46.1 g of BTDA (0.143 mol), 168.6 g of NMP, and 112.4 g of xylene under a nitrogen stream, and the mixture was thoroughly mixed at 40°C for 1 hour. The temperature was then raised to 190°C, and the mixture was heated and stirred for 5 hours. Xylene was added in an amount such that the solids concentration after polymerization would be 30 wt %, thereby preparing resin solution 11.

[0102] (Synthesis Example 12) 5.2 g of mTB (0.024 mol) and 77.4 g of NMP were placed in a reaction vessel under a nitrogen stream and stirred at room temperature to dissolve. Next, 11.7 g of DHNTME (0.023 mol) and 19.3 g of NMP were added, and the mixture was stirred at room temperature for 2 days to carry out a polymerization reaction, preparing a resin solution 12 with a solids concentration of 15 wt%.

[0103] (Synthesis Example 13) 12.3 g of mTB (0.057 mol) and 129.2 g of NMP were placed in a reaction vessel under a nitrogen stream and dissolved by stirring at room temperature. Next, 16.2 g of BPDA (0.055 mol) and 32.3 g of NMP were added, and the mixture was stirred at room temperature for 1 day to carry out a polymerization reaction, preparing a resin solution 13 with a solids concentration of 15 wt%.

[0104] (Synthesis Example 14) 23.7g of ODPA (0.076mol), 28.5g of BAPP (0.069mol), 73.0g of NMP, and 48.7g of xylene were added to a reaction vessel under a nitrogen stream. After mixing thoroughly at 40°C for 1 hour, the mixture was heated to 190°C and heated and stirred for 5 hours. An amount of xylene was added to obtain a resin solution 14-1 such that the solids concentration after polymerization was 30% by weight. In a separate reaction vessel, 14.7g of mTB (0.069mol) and 162.2g of NMP were added under a nitrogen stream and dissolved by stirring at room temperature. Next, 33.9g of DHNTME (0.067mol) and 108.1g of NMP were added, and the mixture was stirred at room temperature for 1 week to carry out the polymerization reaction. Resin solution 14-2 with a solids concentration of 15% by weight was prepared. To the resin solution 14-2, the entire amount of the resin solution 14-1, 52.8 g of NMP, and 121.1 g of xylene were added, and the mixture was stirred at room temperature for 2 days to prepare a resin solution 14-3 having a solid content of 15 wt %.

[0105] [Example 1] Resin solution 1-3 prepared in Synthesis Example 1 was uniformly applied onto copper foil 1 (electrolytic copper foil, thickness: 12 μm, surface roughness Rz on the resin layer side: 0.6 μm) so that the thickness after heat treatment would be 25 μm, and then the solution was dried by heating at 100 to 120°C for 15 minutes to remove the solvent. Further, heat treatment was carried out in a nitrogen atmosphere from room temperature to 320°C at a temperature increase rate of 5°C / min to prepare a single-sided metal-clad laminate 1 having a resin layer thickness of 25 μm. The copper foil layer of the single-sided metal-clad laminate 1 was etched away using an aqueous solution of ferric chloride to prepare a resin film 1 having a thickness of 25 μm. The resin film 1 was transparent and colored, and had a relative permittivity Dk and a dielectric loss tangent Df of 2.9 and 0.0023, respectively. The Tg was 319°C. The storage moduli at 40°C and 260°C were 3.4 × 10 9 Pa, 0.6 × 10 9 It was Pa.

[0106] [Examples 2 to 9, Comparative Examples 1 to 5] Single-sided metal-clad laminates 2 to 14 and resin films 2 to 14 were obtained in the same manner as in Example 1, except that resin solutions 2-3, 3-3, 4-3, 5-3, 6-3, 7-3, 8, 9-3, 10, 11, 12, 13, and 14-3 obtained in Synthesis Examples 2 to 14 were used instead of resin solution 1-3 in Synthesis Example 1. The results are summarized in Table 1.

[0107] [Table 1]

[0108] Examples 1 to 9 achieved a Dk of 3.1 or less, a Df of 0.0024 or less, and a moisture absorption rate of less than 0.4% by weight, and had a Tg of 100°C or higher. On the other hand, Comparative Examples 1 and 2 had a low Tg and could not withstand use at high temperatures of 100°C or higher. Comparative Examples 3, 4, and 5 were all aromatic polyimides, and therefore had excellent heat resistance, but had high Dk and Df, and Comparative Example 4 had a high moisture absorption rate. Therefore, the resin film of the present invention can realize excellent transmission characteristics, can be applied to heating during the mounting process and in high-temperature environments, and can be developed as a variety of materials for high-frequency applications.

[0109] Although the embodiments of the present invention have been described in detail above for the purpose of illustration, the present invention is not limited to the above-described embodiments and various modifications are possible.

Claims

1. A resin film containing, as a resin component, a polyimide having a structural unit containing an aliphatic chain or an alicyclic skeleton, The following conditions (i) to (iii) are met: (i) moisture absorption rate of less than 0.4% by weight; (ii) A relative dielectric constant of 3.1 or less and a dielectric loss tangent of 0.0024 or less at 10 GHz when measured with a split post dielectric resonator (SPDR) in an environment of a temperature of 24 to 26°C and a humidity of 45 to 55%; (iii) a glass transition temperature of 100°C or higher; A resin film characterized by satisfying the above.

2. 2. The resin film according to claim 1, wherein the resin film contains the structural unit having an aliphatic chain or an alicyclic skeleton in an amount of 5 mol % to 44 mol % based on all structural units of the polyimide contained in the resin film.

3. The resin film according to claim 1, wherein the structural unit containing an aliphatic chain or an alicyclic skeleton is a structural unit derived from a dimer acid type diamine in which two terminal carboxylic acid groups of a dimer acid are substituted with primary aminomethyl groups or amino groups.

4. 2. The resin film according to claim 1, wherein the value obtained by dividing the storage modulus at 40°C by the storage modulus at 260°C is 30 or less.

5. A metal-clad laminate comprising a single or multiple insulating resin layer and a metal layer laminated on one or both sides of the insulating resin layer, A metal-clad laminate, wherein at least one of the insulating resin layers is formed from the resin film according to any one of claims 1 to 4.

6. A circuit board comprising an insulating resin layer consisting of a single layer or multiple layers, and a conductor circuit layer laminated on one side or both sides of the insulating resin layer, A circuit board, wherein at least one of the insulating resin layers is formed from the resin film according to any one of claims 1 to 4.

7. An electronic device comprising the circuit board according to claim 6.

8. An electronic device comprising the circuit board according to claim 6.

Images