Polyimide precursor composition for flexible wiring board, polyimide film, and polyimide metal laminate

Abstract

The present invention provides a polyimide precursor composition for a flexible wiring board, which contains a polyimide precursor having a repeating unit represented by general formula (I). By using the polyimide precursor composition, it is possible to produce a polyimide film having a low dielectric loss tangent in a high frequency band and at the same time having excellent heat resistance. In the # imgabs0 # formula, more than 0 mol% and less than 30 mol% of Y1 is a group represented by formula (1): # imgabs1 # formula (1), A is a structure represented by formula (A): # imgabs2 # wherein n is 1 to 4, m is 0 to 4, B is an alkyl group having 1 to 6 carbon atoms, or the like, and U is-CO-O-or-O-CO-.

Description

Technical Field

[0001] The present invention relates to a polyimide film for a flexible wiring board, more particularly, to a polyimide film suitable for a circuit board in a high frequency band, and also to a polyimide precursor composition for producing the polyimide film. Background Art

[0002] Polyimide films have excellent thermal and electrical properties and are therefore widely used in electronic devices such as flexible wiring boards, tapes for TAB (Tape Automated Bonding), etc. In particular, it is known that polyimide having a low linear expansion coefficient and a high elastic modulus can be obtained by using 3,3',4,4'-biphenyltetracarboxylic dianhydride and p-phenylenediamine as the tetracarboxylic acid component and the diamine component, respectively.

[0003] Meanwhile, in recent years, communication devices such as smartphones have begun to use high frequency bands close to 5 GHz or even above 10 GHz. For polyimide, which is a material for flexible circuit boards that transmit high-frequency signals, a material with a small dielectric loss tangent, that is, a material with a small transmission loss when used as a flexible wiring board, is required.

[0004] Patent document 1 (JP 2019-210342 A) proposes a polyimide film with a small dielectric loss tangent, which "contains at least one of p-phenylene bis(trimellitic anhydride monoester) and 3,3',4,4'-biphenyltetracarboxylic dianhydride as an aromatic acid dianhydride component, and contains one of 4,4'-diaminodiphenyl ether, 1,3-bis(4-aminophenyl)benzene, bis(4-aminophenyl) terephthalate and 2,2'-bis(trifluoromethyl)benzidine as an aromatic diamine component" (see claim 4).

[0005] Patent document 2 (JP 2021-74894A) describes a multilayer polyimide film having a thermoplastic polyimide resin layer on at least one side of a non-thermoplastic polyimide resin layer, wherein the non-thermoplastic polyimide resin layer is a reaction product of an acid dianhydride and a diamine, and the tetracarboxylic dianhydride contains more than 30 mol % of a specific ester tetracarboxylic dianhydride, and / or the diamine contains more than 30 mol % of a specific ester diamine (see claim 1).

[0006] Polyimide films using ester diamine compounds (such as the diamine compounds disclosed in the above-mentioned Documents 1 and 2) are also disclosed in Patent Documents 3 to 5.

[0007] [Prior art literature]

[0008] [Patent Document]

[0009] Patent Document 1: Japanese Patent Publication No. 2019-210342

[0010] Patent Document 2: Japanese Patent Publication No. 2021-74894

[0011] Patent Document 3: Japanese Patent Publication No. 11-199668

[0012] Patent Document 4: WO 2008 / 056808

[0013] Patent Document 5: Japanese Patent Publication No. 2007-246709 Summary of the invention

[0014] [Technical issues]

[0015] However, the polyimide film for flexible wiring board needs not only to have a small dielectric loss tangent, but also to have various other properties. For example, the polyimide film used as the polyimide core layer (heat-resistant layer) of the flexible copper-clad laminate needs to have high heat resistance. The polyimide film disclosed in patent document 1 is a thermoplastic polyimide film and cannot be used as a heat-resistant film for the polyimide core layer. Patent document 2 aims to provide a non-thermoplastic polyimide resin layer in a multilayer polyimide film, but the heat resistance is insufficient. The polyimide films disclosed in patent documents 3 to 5 also lack heat resistance.

[0016] An object of the present invention is to provide a polyimide precursor composition for a flexible wiring board, which can be used to produce a polyimide film having a small dielectric loss tangent in a high frequency band and excellent heat resistance and suitable for producing a flexible wiring board, and a polyimide film.

[0017] Another object of the present invention is to provide a polyimide-metal laminate, such as a copper-clad laminate, using a polyimide film obtained from the polyimide precursor composition as a substrate, and a flexible printed wiring board obtained by processing the polyimide metal laminate.

[0018] [Technical solution]

[0019] The main disclosures of this application are summarized as follows:

[0020] 1. A polyimide precursor composition for a flexible wiring board, comprising a polyimide precursor having a repeating unit represented by the following general formula (I).

[0021]

[0022] {Wherein, in the general formula I, X1 is a tetravalent aliphatic group or an aromatic group, Y1 is a divalent aliphatic group or an aromatic group, R1 and R2 are each independently a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an alkylsilyl group having 3 to 9 carbon atoms, and wherein more than 0 mol% and less than 30 mol% of Y1 is a group represented by formula (1):

[0023]

[0024] Wherein, in formula (1), A is a structure represented by formula (A):

[0025]

[0026] wherein n is an integer of 1 to 4, m is an integer of 0 to 4, B is one selected from the group consisting of an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, a halogen group, and a fluoroalkyl group having 1 to 6 carbon atoms, and U independently represents -CO-O- or -O-CO-.}

[0027] 2. The polyimide precursor composition according to item 1 above, wherein A is a structure selected from the group consisting of 1,4-phenylene and 4,4′-biphenylene.

[0028] 3. The polyimide precursor composition according to item 1 or 2 above, wherein 50 mol % or more of X1 is a group represented by the following formula (21):

[0029]

[0030] 4. A polyimide film for a flexible wiring board, obtained from the polyimide precursor composition according to any one of items 1 to 3 above.

[0031] 5. A polyimide metal laminate comprising the polyimide film according to item 4 above, and a metal foil or a metal layer laminated with the polyimide film.

[0032] 6. A flexible wiring board having wiring formed by patterning the metal foil or metal layer of the polyimide metal laminate according to the above item 5.

[0033] [Beneficial Effects of the Invention]

[0034] According to the present invention, a polyimide precursor composition for a flexible wiring board and a polyimide film obtained from the precursor composition are provided, wherein the polyimide precursor composition can be used to produce a polyimide film having a small dielectric loss tangent in a high frequency band and excellent heat resistance and suitable for producing a flexible wiring board.

[0035] Furthermore, according to another aspect of the present invention, there are provided a polyimide-metal laminate, such as a copper-clad laminate, using a polyimide film obtained from the polyimide precursor composition as a substrate, and a flexible printed wiring board obtained by processing the polyimide metal laminate. DETAILED DESCRIPTION

[0036] <Polyimide Precursor Composition>

[0037] The polyimide precursor composition for a flexible wiring board contains a polyimide precursor having a repeating unit represented by the general formula (I), and contains a solvent in its form during circulation, and the polyimide precursor is dissolved in the solvent.

[0038] The polyimide precursor contains a repeating unit represented by the following general formula (I):

[0039]

[0040] (In the general formula I, X1 is a tetravalent aliphatic group or aromatic group, Y1 is a divalent aliphatic group or aromatic group, and R1 and R2 are each independently a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an alkylsilyl group having 3 to 9 carbon atoms).

[0041] The polyamic acid in which R1 and R2 are hydrogen atoms is particularly preferred.

[0042] The polyimide precursor will be described in terms of the monomers (tetracarboxylic acid component, diamine component, and other components) providing X1 and Y1 in the general formula (I), and then the production method will be described.

[0043] In this specification, the tetracarboxylic acid component includes tetracarboxylic acids, tetracarboxylic dianhydrides, and other tetracarboxylic acid derivatives (such as tetracarboxylic acid silyl esters, tetracarboxylic acid esters, and tetracarbonyl chlorides), each of which is used as a starting material for producing polyimide. Although not particularly limited, it is convenient to use tetracarboxylic dianhydrides for production, and examples of using tetracarboxylic dianhydrides as the tetracarboxylic acid component will be described below. In addition, the diamine component is a diamine compound having two amino groups (-NH2), which is used as a starting material for producing polyimide.

[0044] <X1 and the tetracarboxylic acid component>

[0045] X1 may be an aliphatic group or an aromatic group, but an aromatic group is preferred. Preferably 50 mol% or more, more preferably 70 mol% or more, even more preferably 90 mol% or more (100 mol% or more is also highly preferred) of X1 is an aromatic group.

[0046] Examples of the aromatic group X1 include the following structures.

[0047]

[0048] (In which, Z1 is a direct bond or any one of the following divalent groups:

[0049]

[0050] Wherein, Z2 in the formula is a divalent organic group, Z3 and Z4 are each independently an amide bond, an ester bond or a carbonyl bond, and Z5 is an organic group containing an aromatic ring.

[0051] Specific examples of Z2 include aliphatic hydrocarbon groups having 2 to 24 carbon atoms and aromatic hydrocarbon groups having 6 to 24 carbon atoms.

[0052] Specific examples of Z5 include aromatic hydrocarbon groups having 6 to 24 carbon atoms.

[0053] The tetracarboxylic acid component providing the repeating unit of the general formula (I) in which X1 is a tetravalent group having an aromatic ring includes, but is not limited to: halogen-substituted aromatic tetracarboxylic dianhydrides, such as 3,3',4,4'-biphenyltetracarboxylic dianhydride, 2,3,3',4'-biphenyltetracarboxylic dianhydride, 2,2',3,3'-biphenyltetracarboxylic dianhydride, pyromellitic dianhydride, benzophenonetetracarboxylic dianhydride, 4,4'-oxydiphthalic dianhydride, diphenylsulfonetetracarboxylic dianhydride, p-terphenyltetracarboxylic dianhydride, m-terphenyltetracarboxylic dianhydride and 1,4-phenylenebis(1,3-dioxy-1,3-dihydroisobenzofuran-5-carboxylate); and halogen-substituted tetracarboxylic dianhydrides, such as 4,4'-(hexafluoroisopropylidene)diphthalic anhydride , 3,3'-(hexafluoroisopropylidene)diphthalic anhydride, 5,5'-[2,2,2-trifluoro-1-[3-(trifluoromethyl)phenyl]ethylidene]diphthalic anhydride, 5,5'-[2,2,3,3,3-pentafluoro-1-(trifluoromethyl)propylene]diphthalic anhydride, 1H-difluoro[3,4-b:3',4'-i]xanthene-1,3,7,9(11H)-tetraone, 5,5'-oxybis[4,6,7-trifluoropyromellitic anhydride], 3,6-bis(trifluoromethyl)pyromellitic dianhydride, 4-(trifluoromethyl)pyromellitic dianhydride, 1,4-difluoropyromellitic dianhydride, 1,4-bis(3,4-dicarboxytrifluorophenoxy)tetrafluorophthalic anhydride, etc. These may be used alone or in combination of a plurality of them.

[0054] Among them, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 2,3,3',4'-biphenyltetracarboxylic dianhydride, 2,2',3,3'-biphenyltetracarboxylic dianhydride, pyromellitic dianhydride, 4,4'-oxydiphthalic dianhydride, 1,4-phenylenebis(1,3-dioxy-1,3-dihydroisobenzofuran-5-carboxylate), benzophenonetetracarboxylic dianhydride and p-terphenyltetracarboxylic dianhydride are particularly preferred.

[0055] In a preferred embodiment of the present invention, the content of the structure derived from s-BPDA in X1 is at least 50 mol% or more, more preferably 60 mol% or more, even more preferably 70 mol% or more, and most preferably 80 mol% or more (including 100 mol%). The remaining X1 is preferably an aromatic group, and is preferably selected from, for example, a group derived from 2,3,3',4'-biphenyltetracarboxylic dianhydride, 2,2',3,3'-biphenyltetracarboxylic dianhydride, pyromellitic dianhydride, 4,4'-oxydiphthalic dianhydride and 1,4-phenylenebis(1,3-dioxy-1,3-dihydroisobenzofuran-5-carboxylate).

[0056] The aliphatic group X1 may be an open-chain aliphatic group or an alicyclic group, but is preferably an alicyclic group. As the alicyclic group X1, a tetravalent group having an alicyclic structure of 4 to 40 carbon atoms is preferred, more preferably a tetravalent group having at least one aliphatic 4-12-membered ring, more preferably a tetravalent group having an aliphatic 4-membered ring or an aliphatic 6-membered ring. Preferred examples of the tetravalent group having an aliphatic 4-membered ring or an aliphatic 6-membered ring include the following groups.

[0057]

[0058] (Among them, R 31 To R 38 are each independently a direct bond or a divalent organic group; and R 41 To R 47 and R 71 To R 73 Each independently represents one selected from the group consisting of -CH2-, -CH=CH-, -CH2CH2-, -O- and -S-. 48 It is an organic group with an aromatic ring or an alicyclic structure.

[0059] R 31 , R 32 , R 33 , R 34 , R 35 , R 36 , R 37 Specific examples of R3 include a direct bond or an aliphatic hydrocarbon group having 1 to 6 carbon atoms, or an oxygen atom (—O—), a sulfur atom (—S—), a carbonyl bond, an ester bond, and an amide bond.

[0060] With aromatic ring as R 48 Examples of the organic group include the following groups.

[0061]

[0062] (Wherein, W1 is a direct bond or a divalent organic group; n 11 to n13 Each independently represents an integer from 0 to 4; and R 51 , R 52 and R 53 Each is independently an alkyl group having 1 to 6 carbon atoms, a halogen group, a hydroxyl group, a carboxyl group or a trifluoromethyl group.

[0063] Specific examples of W1 include a divalent group represented by formula (5) described below, and a divalent group represented by formula (6) described below.

[0064]

[0065] (Wherein, in formula (6), R 61 To R 68 Each independently represents any one of the divalent groups represented by formula (5).

[0066] Among them, the following groups are particularly preferred as the tetravalent group having an alicyclic structure.

[0067]

[0068] The tetracarboxylic acid component providing the alicyclic group X1 includes, for example, 1,2,3,4-cyclobutanetetracarboxylic dianhydride, cyclohexane-1,2,4,5-tetracarboxylic dianhydride, [1,1'-di(cyclohexane)]-3,3',4,4'-tetracarboxylic dianhydride, [1,1'-di(cyclohexane)]-2,3,3',4'-tetracarboxylic dianhydride, [1,1'-di(cyclohexane)]-2,2',3,3'-tetracarboxylic dianhydride, 4,4'-methylenebis(cyclohexane-1,2-dicarboxylic anhydride), 4,4'-(propane-2,2-diyl)bis(cyclohexane-1,2-dicarboxylic anhydride), 4,4'-oxybis(cyclohexane-1,2-dicarboxylic anhydride), 4,4'-thiobis(cyclohexane-1,2-dicarboxylic anhydride), 4,4'-sulfonebis(cyclohexane-1,2-dicarboxylic anhydride), 4,4'-(dimethylsilanediyl)bis(cyclohexane-1,2-dicarboxylic anhydride), 4,4'-(tetrafluoropropane-2,2-diyl)bis(cyclohexane-1,2-dicarboxylic anhydride), octahydropentalene-1,3,4,6-tetracarboxylic dianhydride, bicyclo[2.2.1]heptane-2,3,5,6-tetracarboxylic dianhydride, 6-(carboxymethyl)bicyclo[2.2.1]heptane- 2,3,5-tricarboxylic dianhydride, bicyclo[2.2.2]octane-2,3,5,6-tetracarboxylic dianhydride, bicyclo[2.2.2]oct-5-ene-2,3,7,8-tetracarboxylic dianhydride, tricyclo[4.2.2.02,5]decane-3,4,7,8-tetracarboxylic dianhydride, tricyclo[4.2.2.02,5]decane-7-ene-3,4,9,10-tetracarboxylic dianhydride, 9-oxotricyclo[4.2.1.02,5]nonane-3,4,7,8-tetracarboxylic dianhydride, norbornane-2-spiro-α-cyclopentanone-α'-spiro-2"-norbornane-5,5 ",6,6"-tetracarboxylic dianhydride, (4arH,8acH)-decahydro-1t,4t:5c,8c-dimethylnaphthalene-2c,3c,6c,7c-tetracarboxylic dianhydride, (4arH,8acH)-decahydro-1t,4t:5c,8c-dimethylnaphthalene-2t,3t,6c,7c-tetracarboxylic dianhydride, decahydro-1,4-ethoxy-5,8-methylnaphthalene-2,3,6,7-tetracarboxylic dianhydride, tetradecahydro-1,4:5,8:9,10-trimethylanthracene-2,3,6,7-tetracarboxylic dianhydride, etc. These can be used alone or in combination of two or more.

[0069] The tetracarboxylic acid component providing the open-chain aliphatic group X1 includes linear or branched tetracarboxylic dianhydrides having about 4 to 10 carbon atoms, such as 1,2,3,4-butanetetracarboxylic dianhydride and 1,2,3,4-pentanetetracarboxylic dianhydride.

[0070] Y1 contains at least a group represented by formula (1):

[0071]

[0072] A includes a group represented by formula (A):

[0073]

[0074] (wherein, n is an integer of 1 to 4, m is an integer of 0 to 4, and B is one selected from the group consisting of an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, a halogen group, and a fluoroalkyl group having 1 to 6 carbon atoms).

[0075] n is preferably 1 to 3, more preferably 1 or 2. m is preferably 0 or 1. Examples of A include 1,4-phenylene, 1,3-phenylene, 4,4'-biphenylene, 3,4'-biphenylene, 3,3'-biphenylene and 4,4"-p-terphenylene. In particular, 1,4-phenylene, 4,4'-biphenylene and 4,4"-p-terphenylene bonded at the para position are preferred.

[0076] Preferably, one of U represents -CO-O-, and the other represents -O-CO-. That is, a preferred structure of formula (1) is represented by formula (1-1) or formula (1-2).

[0077]

[0078]

[0079] The positional relationship between U and the bond in formula (1) (the positional relationship between U and N in formula (I)) may be any of the ortho position, meta position or para position, but is preferably the para position.

[0080] Examples of the diamine compound providing the group of formula (1) include bis(4-aminophenyl)terephthalate (abbreviated as BPTP), bis(4-aminophenyl)biphenyl-4,4′-dicarboxylate (abbreviated as APBP), and [4-(4-aminobenzoyl)oxyphenyl]4-aminobenzoate (abbreviated as ABHQ).

[0081] The ratio of the group of formula (1) in Y1 is greater than 0 mol% and less than 30 mol%, more preferably 10 mol% or more, even more preferably 15 mol% or more, and preferably less than 25 mol%. Within this range, a polyimide film having a good balance between low dielectric loss tangent and heat resistance can be obtained.

[0082] Y1 other than the formula (1) may be an aliphatic group or an aromatic group, but is preferably an aromatic group.

[0083] Examples of the aromatic group Y1 include the following structures.

[0084]

[0085] (Wherein, W1 is a direct bond or a divalent organic group; n 11 to n 13 Each independently represents an integer from 0 to 4; and R 51 , R 52 and R 53 Each is independently an alkyl group having 1 to 6 carbon atoms, a halogen group, a hydroxyl group, a carboxyl group or a trifluoromethyl group.

[0086] Specific examples of W1 include a divalent group represented by formula (5) described below, and a divalent group represented by formula (6) described below.

[0087]

[0088] (Wherein, in formula (6), R 61 To R 68 Each independently represents any one of the divalent groups represented by formula (5).

[0089] The diamine component providing the divalent group Y1 having an aromatic ring includes, for example, p-phenylenediamine, m-phenylenediamine, 2,4-toluenediamine, 3,3′-dihydroxy-4,4′-diaminobiphenyl, bis(4-amino-3-carboxyphenyl)methane, benzidine, 3,3′-diaminobiphenyl, 2,2′-bis(trifluoromethyl)benzidine, 3,3′-bis(trifluoromethyl)benzidine, m-tolidine, 4,4′-diaminobenzanilide, 3,4′-diaminobenzanilide, N,N′-bis(4-aminophenyl)terephthalamide, N,N′-p-phenylenebis(p-aminobenzamide), 4-aminophenoxy-4-nitrophenylenebis(p-aminobenzamide), and the like. diaminobenzoate, bis(4-aminophenyl)terephthalate, bis(4-aminophenyl)biphenyl-4,4'-dicarboxylate, p-phenylenebis(p-aminobenzoate), bis(4-aminophenyl)-[1,1'-biphenyl]-4,4'-dicarboxylate, [1,1'-biphenyl]-4,4'-diylbis(4-aminobenzoate), 4,4'-oxydiphenylamine (also known as 4,4'-diaminodiphenyl ether), 3,4'-oxydiphenylamine, 3,3'-oxydiphenylamine, p-methylenebis(phenylenediamine), 1,3-bis(4-aminophenoxy)benzene, 1,3-bis(3-aminophenoxy)benzene )benzene, 1,4-bis(4-aminophenoxy)benzene, 4,4'-bis(4-aminophenoxy)biphenyl, 4,4'-bis(3-aminophenoxy)biphenyl, 2,2-bis(4-(4-aminophenoxy)phenyl)hexafluoropropane, 2,2-bis(4-aminophenyl)propane, bis(4-aminophenyl)sulfone, 2,2-bis(4-aminophenyl)hexafluoropropane, bis(4-aminophenyl)sulfone, 3,3'-bis(trifluoromethyl)benzidine, 3,3'-bis((aminophenoxy)phenyl)propane, 2,2'-bis(3-amino-4-hydroxyphenyl)hexafluoropropane, bis(4-(4-aminophenoxy)difluoropropane bis(4-(3-aminophenoxy)diphenyl)sulfone, bis(4-(3-aminophenoxy)diphenyl)sulfone, octafluorobenzidine, 3,3'-dimethoxy-4,4'-diaminobiphenyl, 3,3'-dichloro-4,4'-diaminobiphenyl, 3,3'-difluoro-4,4'-diaminobiphenyl, 2,4-bis(4-aminoanilino)-6-amino-1,3,5-triazine, 2,4-bis(4-aminoanilino)-6-methylamino-1,3,5-triazine, 2,4-bis(4-aminoanilino)-6-ethylamino-1,3,5-triazine and 2,4-bis(4-aminoanilino)-6-anilino-1,3,5-triazine. Examples of diamine components providing repeating units of the general formula (I) (wherein Y1 is a divalent group having an aromatic ring containing a fluorine atom) include 2,2'-bis(trifluoromethyl)benzidine, 3,3'-bis(trifluoromethyl)benzidine, 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane, 2,2-bis(4-aminophenyl)hexafluoropropane and 2,2'-bis(3-amino-4-hydroxyphenyl)hexafluoropropane.In addition, preferred diamine compounds include 9,9-bis(4-aminophenyl)fluorene, 4,4'-(((9H-fluorene-9,9-diyl)bis([1,1'-biphenyl]-5,2-diyl))bis(oxy))diamine, [1,1':4',1"-terphenyl]-4,4"-diamine, 4,4'-([1,1'-binaphthyl]-2,2'-diylbis(oxy))diamine. The diamine components may be used alone or in combination of a plurality thereof.

[0090] The group Y1 having an alicyclic structure includes the following structures.

[0091]

[0092] (Wherein, V1 and V2 are each independently a direct bond or a divalent organic group; n 21 to n 26 Each independently represents an integer from 0 to 4; and R 81 To R 86 are each independently an alkyl group having 1 to 6 carbon atoms, a halogen group, a hydroxyl group, a carboxyl group or a trifluoromethyl group; and R 91 , R 92 and R 93 Each is independently one selected from the group consisting of -CH2-, -CH=CH-, -CH2CH2-, -O- and -S-.)

[0093] Specific examples of V1 and V2 include a direct bond and a divalent group represented by the formula (5) as described above.

[0094] The diamine component providing the group Y1 having an alicyclic structure includes, for example, 1,4-diaminocyclohexane, 1,4-diamino-2-methylcyclohexane, 1,4-diamino-2-ethylcyclohexane, 1,4-diamino-2-n-propylcyclohexane, 1,4-diamino-2-isopropylcyclohexane, 1,4-diamino-2-n-butylcyclohexane, 1,4-diamino-2-isobutylcyclohexane, 1,4-diamino-2-sec-butylcyclohexane, 1,4-diamino-2-tert-butylcyclohexane, 1,2-diaminocyclohexane, 1,3-diaminocyclobutane, 1,4-diaminocyclohex ... (aminomethyl) cyclohexane, 1,3-bis(aminomethyl) cyclohexane, diaminodicycloheptane, diaminomethyldicycloheptane, diaminooxydicycloheptane, diaminomethyloxydicycloheptane, isophoronediamine, diaminotricyclodecane, diaminomethyltricyclodecane, bis(aminocyclohexyl)methane, bis(aminocyclohexyl)isopropylidene, 6,6'-bis(3-aminophenoxy)-3,3,3',3'-tetramethyl-1,1'-spirobiindane and 6,6'-bis(4-aminophenoxy)-3,3,3',3'-tetramethyl-1,1'-spirobiindane. The diamine components may be used alone or in combination of a plurality thereof.

[0095] Y1 other than formula (1) is preferably selected from those that provide high heat resistance to the polyimide, and is preferably an aromatic group. When described as a diamine compound, examples thereof include p-phenylenediamine, 4,4″-diamino-p-terphenyl, 2,2′-dimethyl-4,4′-diaminobiphenyl, 4,4′-bis(4-aminophenoxy)biphenyl, and 1,3-bis(4-aminophenoxy)benzene.

[0096] In particular, the amount of p-phenylenediamine and / or 4,4″-diamino-p-terphenyl present is 40 mol% or more and less than 100 mol%, preferably 50 mol% or more and less than 100 mol%, based on the total amount of the diamine component.

[0097] As described above, the proportion of the diamine compound providing the group of formula (1) is greater than 0 mol% and less than 30 mol%, more preferably 10 mol% or more, even more preferably 15 mol% or more, and preferably 25 mol% or less, more preferably less than 25 mol%. Therefore, p-phenylenediamine and / or 4,4″-diamino-p-terphenyl and other diamine compounds such as 2,2′-dimethyl-4,4′-diaminobiphenyl, 4,4′-bis(4-aminophenoxy)biphenyl, 1,3-bis(4-aminophenoxy)benzene, etc. are used so that the total amount becomes 100 mol%.

[0098] The polyimide precursor composition for flexible wiring board is obtained by reacting a tetracarboxylic acid component with a diamine component in a solvent. By using an approximately equimolar amount of a tetracarboxylic acid component (tetracarboxylic dianhydride) and a diamine component, the reaction is carried out at a relatively low temperature (e.g., below 100°C, preferably below 80°C). Although not limited thereto, the reaction temperature is generally 25°C to 100°C, preferably 25°C to 80°C, more preferably 30°C to 80°C, and the reaction time is, for example, about 0.1 to 72 hours, preferably about 2 to 60 hours. The reaction can be carried out in an air atmosphere, but is usually suitably carried out in an inert atmosphere, preferably in a nitrogen atmosphere.

[0099] Here, approximately equimolar amounts of the tetracarboxylic acid component (tetracarboxylic dianhydride) and the diamine component specifically means that the molar ratio [tetracarboxylic acid component / diamine component] is 0.90 to 1.10, preferably about 0.95 to 1.05.

[0100] The solvent used to prepare the polyimide precursor composition preferably includes water or an aprotic solvent such as N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone or dimethyl sulfoxide, and its structure is not particularly limited, as any kind of solvent can be used without problem as long as it dissolves the starting material monomer components and the resulting polyimide precursor. As the solvent, water is preferably used; amide solvents such as N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone and N-ethyl-2-pyrrolidone; cyclic ester solvents such as γ-butyrolactone, γ-valerolactone, δ-valerolactone, γ-caprolactone, ε-caprolactone and α-methyl-γ-butyrolactone; carbonate solvents such as ethylene carbonate and propylene carbonate; glycol solvents such as triethylene glycol; phenolic solvents such as m-cresol, p-cresol, 3-chlorophenol and 4-chlorophenol; acetophenone, 1,3-dimethyl-2-imidazolidinone, cyclopentane sulfoxide, dimethyl sulfoxide, etc. In addition, other commonly used organic solvents may be used, such as phenol, o-cresol, butyl acetate, ethyl acetate, isobutyl acetate, propylene glycol methyl acetate, ethyl cellosol, butyl cellosol, 2-methyl cellosol acetate, ethyl cellosol acetate, butyl cellosol acetate, tetrahydrofuran, dimethoxyethane, diethoxyethane, dibutyl ether, diethylene glycol dimethyl ether, methyl isobutyl ketone, diisobutyl ketone, cyclopentanone, cyclohexanone, methyl ethyl ketone, acetone, butanol, ethanol, xylene, toluene, chlorobenzene, turpentine, mineral spirits, naphtha solvent, etc. The solvent may be used in combination of two or more.

[0101] When the polyimide precursor composition is produced, although not particularly limited, a monomer and a solvent are charged so that the solid concentration of the polyimide precursor (polyimide equivalent mass concentration) is, for example, 5 to 45% by mass and reacted.

[0102] The solution viscosity of the polyimide precursor composition can be appropriately selected according to the purpose of use (coating, casting, etc.) and the purpose of production. For example, preferably, in terms of processability when handling the polyamic acid solution, the rotational viscosity of the polyamic acid (polyimide precursor) solution measured at 30° C. is about 0.1 to 5000 poise, particularly 0.5 to 2000 poise, and more preferably about 1 to 2000 poise.

[0103] As the polyimide precursor composition, the reaction solution of the tetracarboxylic acid component and the diamine component can be used as it is, or can be concentrated or diluted by adding a solvent if necessary. Therefore, the solvent included in the polyimide precursor composition can be the solvent used in the reaction of the tetracarboxylic acid component and the diamine component. The solvent added if necessary can be the same as or different from the reaction solvent.

[0104] In the case of thermal imidization, the polyimide precursor composition may contain an imidization catalyst, an organic phosphorus-containing compound, inorganic fine particles, etc., if necessary. In the case of chemical imidization, the polyamic acid solution may contain a cyclization catalyst, a dehydrating agent, inorganic fine particles, etc., if necessary.

[0105] The imidization catalyst may be a substituted or unsubstituted nitrogen-containing heterocyclic compound, an N-oxide of a nitrogen-containing heterocyclic compound, a substituted or unsubstituted amino acid compound, an aromatic hydrocarbon compound or an aromatic heterocyclic compound having a hydroxyl group. Examples include, in particular, lower alkyl-substituted or aryl-substituted imidazoles, such as 1,2-dimethylimidazole, N-methylimidazole, N-benzyl-2-methylimidazole, 2-methylimidazole, 2-ethyl-4-methylimidazole and 2-phenylimidazole; benzimidazoles, such as 5-methylbenzimidazole; substituted pyridines, such as isoquinoline, 3,5-lutidine, 3,4-lutidine, 2,5-lutidine, 2,4-lutidine, 4-n-propylpyridine, etc. The amount of the imidization catalyst used is preferably about 0.01 to 2 equivalents, in particular 0.02 to 1 equivalents, based on the amic acid unit of the polyamic acid. The imidization catalyst can improve the physical properties of the resulting polyimide film, particularly the elongation and edge tear resistance.

[0106] Examples of the compound containing organophosphorus include phosphoric acid esters such as monocaproyl phosphate, monooctyl phosphate, monolauryl phosphate, monomyristyl phosphate, monocetyl phosphate, monostearyl phosphate, phosphoric acid monoester of triethylene glycol monotridecanether, phosphoric acid monoester of tetraethylene glycol monolauryl ether, phosphoric acid monoester of diethylene glycol monostearyl ether, dicaproyl phosphate, dioctyl phosphate, didecyl phosphate, dilauryl phosphate, dimyristyl phosphate, dicetyl phosphate, distearyl phosphate, phosphoric acid diester of tetraethylene glycol mononeopentyl ether, phosphoric acid diester of triethylene glycol monotridecanether, phosphoric acid diester of tetraethylene glycol monolauryl ether and phosphoric acid diester of diethylene glycol monostearyl ether, and triesters of phosphoric acid such as trimethyl phosphate and triphenyl phosphate, and amine salts of these phosphoric acid esters. Amines include ammonia, monomethylamine, monoethylamine, monopropylamine, monobutylamine, dimethylamine, diethylamine, dipropylamine, dibutylamine, trimethylamine, triethylamine, tripropylamine, tributylamine, monoethanolamine, diethanolamine, triethanolamine and the like.

[0107] Examples of the cyclization catalyst include aliphatic tertiary amines such as trimethylamine and triethylenediamine; aromatic tertiary amines such as dimethylaniline; and heterocyclic tertiary amines such as isoquinoline, pyridine, α-picoline, and β-picoline.

[0108] Examples of the dehydrating agent include aliphatic carboxylic acid anhydrides such as acetic anhydride, propionic anhydride and butyric anhydride; and aromatic carboxylic acid anhydrides such as benzoic anhydride.

[0109] Examples of inorganic fine particles include inorganic oxide powders in particle form, such as titanium dioxide powder, silicon dioxide (silica) powder, magnesium oxide powder, aluminum oxide (alumina) powder, and zinc oxide powder; inorganic nitride powders in particle form, such as silicon nitride powder and titanium nitride powder; inorganic carbide powders, such as silicon carbide powder; and inorganic salt powders in particle form, such as calcium carbonate powder, calcium sulfate powder, and barium sulfate powder. Two or more of these inorganic fine particles may be used in combination. In order to uniformly disperse these inorganic fine particles, any method known to the public may be used.

[0110] <Method for producing polyimide film>

[0111] The polyimide precursor composition of the present invention can be used to prepare a single-layer or multi-layer polyimide film.

[0112] The polyimide film can be produced by a known method. For example, the following methods (1) and (2) can be used to produce a single-layer polyimide film.

[0113] (1) The method comprises casting or coating a polyimide precursor composition on a support, and then heating it in this state on the support to complete imidization, thereby obtaining a polyimide film.

[0114] (2) The method comprises casting or coating a polyimide precursor composition on a support, heating to produce a self-supporting film (gel film) in a semi-cured state or an early dried state, peeling the self-supporting film from the support, heating the self-supporting film while fixing the edges with a tensioning device or the like to remove the solvent, and performing imidization to obtain a polyimide film.

[0115] The above method (2) is suitable for the continuous production of longer polyimide films.

[0116] The single-layer polyimide film produced using the polyimide precursor composition of the present invention has excellent heat resistance, and the glass transition temperature (Tg) is preferably 260° C. or higher, more preferably 270° C. or higher, even more preferably 280° C. or higher, and even more preferably 290° C. or higher. The 5% weight reduction temperature (Td5) is preferably 550° C. or higher, more preferably 555° C. or higher, and even more preferably 560° C. or higher. At a frequency of 10 GHz and a humidity of 60% RH, the dielectric loss tangent is preferably less than 0.0055, more preferably 0.0053 or lower, even more preferably 0.0051 or lower, even more preferably 0.0045 or lower, even more preferably 0.0040 or lower, and even more preferably 0.0036 or lower.

[0117] The linear thermal expansion coefficient (CTE) of the single-layer polyimide film of the present invention is preferably 20 ppm / K or less, more preferably 16 ppm / K or less, and even more preferably 13 ppm / K or less.

[0118] The following methods (3) and (4) can be used to produce a multilayer polyimide film.

[0119] (3) The method comprises casting or coating a polyimide precursor composition on a support to produce a self-supporting film, casting or coating two or more layers of the polyimide precursor composition on one side or both sides of the self-supporting film, and then heating (if necessary, fixing the self-supporting film with a tensioning device immediately after the self-supporting film is manufactured) to complete imidization, thereby obtaining a polyimide film.

[0120] (4) The method comprises, for example, simultaneously casting or coating two or more layers of a polyimide precursor composition on a support by a coextrusion method, and then heating (if necessary, fixing the self-supporting film with a tensioning device immediately after the self-supporting film is manufactured) to complete imidization, thereby obtaining a polyimide film.

[0121] The multilayer polyimide film (or polyimide layer) of the present invention has excellent heat resistance, and the solder heat resistance temperature is preferably 280° C. or higher, more preferably 290° C. or higher. At a frequency of 10 GHz and a humidity of 60% RH, the dielectric loss tangent is preferably less than 0.0055, more preferably 0.0053 or lower, even more preferably 0.0051 or lower, even more preferably 0.0048 or lower, and even more preferably 0.0045 or lower.

[0122] The linear thermal expansion coefficient (CTE) of the multilayer polyimide film of the present invention is preferably 25 ppm / K or less, more preferably 23 ppm / K or less, and even more preferably 20 ppm / K or less.

[0123] Examples of the form of the multilayer polyimide film include a two-layer structure of melt-adhesive PI layer / heat-resistant PI layer, and a three-layer structure of melt-adhesive PI layer / heat-resistant PI layer / melt-adhesive PI layer (PI is the abbreviation of polyimide). The polyimide precursor composition of the present invention is suitably used as a heat-resistant polyimide layer of a multilayer polyimide film.

[0124] <Melt-bonding polyimide layer (melt-bonding PI layer)>

[0125] In the multilayer polyimide film, the melt-adhesive polyimide layer is formed of a melt-adhesive polyimide obtained from a tetracarboxylic acid component and a diamine component.

[0126] The melt-adhesive polyimide is preferably prepared using at least one tetracarboxylic dianhydride selected from 3,3',4,4'-biphenyltetracarboxylic dianhydride, 2,3,3',4'-biphenyltetracarboxylic dianhydride (these two components are also collectively referred to as "biphenyltetracarboxylic dianhydride") and pyromellitic dianhydride as a tetracarboxylic acid component in an amount of 50 to 100 mol % based on the total amount of the tetracarboxylic acid component. The total amount of these tetracarboxylic acid components is preferably 70 mol % or more, more preferably 80 mol % or more, and even more preferably 90 mol % or more based on the total amount of the tetracarboxylic acid component.

[0127] When pyromellitic dianhydride is the main component of the tetracarboxylic acid component, the amount of pyromellitic dianhydride is preferably 50 mol% or more and 90 mol% or less, more preferably 65 mol% or more, even more preferably 70 mol% or more, and more preferably 85 mol% or less, and even more preferably 80 mol% or less. The amount of biphenyltetracarboxylic dianhydride is preferably 10 mol% or more and 50 mol% or less, more preferably 15 mol% or more, even more preferably 20 mol% or more, and more preferably 35 mol% or less, and even more preferably 30 mol% or less.

[0128] When biphenyltetracarboxylic dianhydride is the main component of the tetracarboxylic acid component, the amount of biphenyltetracarboxylic dianhydride is preferably 50 mol % or more and 100 mol % or less, more preferably 70 mol % or more, and even more preferably 90 mol % or more. The amount of pyromellitic dianhydride is preferably 0 mol % or more and 50 mol % or less, more preferably 30 mol % or less, and even more preferably 10 mol % or less.

[0129] When biphenyltetracarboxylic dianhydride is taken as 100 mol %, the proportion of 3,3',4,4'-biphenyltetracarboxylic dianhydride is preferably 50 mol % or more and 100 mol % or less, more preferably 70 mol % or more and more preferably 90 mol % or less, and the proportion of 2,3,3',4'-biphenyltetracarboxylic dianhydride is preferably 0 mol % or more and 50 mol % or less, more preferably 10 mol % or more and more preferably 30 mol % or less.

[0130] As tetracarboxylic acid components, the above three tetracarboxylic acid components can be used in combination with other tetracarboxylic acid components. Examples of other tetracarboxylic acid components used in combination include 3,3',4,4'-benzophenone tetracarboxylic acid dianhydride, bis(3,4-dicarboxyphenyl)ether dianhydride, bis(3,4-dicarboxyphenyl)sulfide dianhydride, bis(3,4-dicarboxyphenyl)sulfone dianhydride; bis(3,4-dicarboxyphenyl)methane dianhydride, 2,2-bis(3,4-dicarboxyphenyl)propane dianhydride and 1,4-hydroquinone dibenzoate-3,3',4,4'-tetracarboxylic acid dianhydride. The tetracarboxylic acid components used in combination can be used alone or in combination of two or more.

[0131] The melt-adhesive polyimide is preferably prepared using a diamine represented by the following chemical formula (13) as a diamine component in an amount of 50 to 100 mol % of the total diamine component. The total amount of these diamine components accounts for preferably 70 mol % or more of the total diamine components, more preferably 80 mol % or more, and even more preferably 90 mol % or more.

[0132]

[0133] [In formula (13), X represents O, CO, COO, OCO, C(CH3)2, CH2, SO2, S or a direct bond, and may have two or more types of bonds, and m represents an integer of 0 to 4.]

[0134] Examples of the diamine represented by formula (13) include 1,3-bis(4-aminophenoxy)benzene, 1,4-bis(4-aminophenoxy)benzene, 1,3-bis(3-aminophenoxy)benzene, 4,4'-bis(3-aminophenoxy)biphenyl, 4,4'-bis(4-aminophenoxy)biphenyl, 3,3'-diaminobenzophenone, bis[4-(3-aminophenoxy)phenyl]ketone, bis[4-(4-aminophenoxy)phenyl]ketone, bis[4-(3-aminophenoxy)phenyl]sulfide, bis[4-(4-aminophenoxy)phenyl]sulfide, bis[4-(3-aminophenoxy)phenyl]sulfone, bis[4-(4-aminophenoxy)phenyl]sulfone, bis[4-(3-aminophenoxy)phenyl]ether, bis[4-(4-aminophenoxy)phenyl]ether, 2,2-bis[4-(4-aminophenoxy)phenyl]propane, 2,2-bis[4-(3-aminophenoxy)phenyl]propane, bis(4-aminophenyl)terephthalate, bis(4-aminophenyl)biphenyl-4,4'-dicarboxylate, [4-(4-aminobenzoyl)oxyphenyl]4-aminobenzoate, etc. The diamine components may be used alone or in combination of two or more.

[0135] The melt-adhesive polyimide constituting the melt-adhesive polyimide layer is preferably amorphous in terms of improving the peel strength between the melt-adhesive polyimide layer and the heat-resistant polyimide layer and between the melt-adhesive polyimide layer and the copper foil. The melt-adhesive polyimide being amorphous means that it has a glass transition temperature and a melting point is not observed. In order to produce a melt-adhesive polyimide layer composed of amorphous melt-adhesive polyimide, for example, the following method can be adopted: a compound having an ether bond is used as a tetracarboxylic acid component or a diamine component.

[0136] The glass transition temperature of the melt-adhesive polyimide constituting the melt-adhesive polyimide layer is preferably 250 to 320° C., more preferably 270 to 300° C., in terms of improving the heat resistance of the resulting melt-adhesive polyimide film. The method of measuring the glass transition temperature will be described in detail in Examples described later.

[0137] <Polyimide Metal Laminate>

[0138] The polyimide precursor composition or polyimide film of the present invention can be used to produce a polyimide metal laminate in which a polyimide film (or layer) and a metal foil (or layer) are laminated together. Examples of the production method of the polyimide metal laminate include the following method.

[0139] (i) A method of laminating a polyimide film with a substrate (e.g., metal foil) directly or via an adhesive by applying pressure or applying heat and pressure;

[0140] (ii) a method of directly forming a metal layer on a polyimide film by a dry method (metallization, such as vacuum deposition and sputtering) and / or a wet method (plating);

[0141] (iii) A method in which a polyimide precursor is applied to a substrate such as a metal foil and dried and imidized.

[0142] In the above (i), when the polyimide film is directly laminated on a substrate (such as a metal foil), it is preferred to use a multilayer polyimide film having a melt-bonded polyimide layer on the surface, such as a two-layer structure of a melt-bonded PI layer / heat-resistant PI layer, or a three-layer structure of a melt-bonded PI layer / heat-resistant PI layer / melt-bonded PI layer.

[0143] In the above (i), when the polyimide film and the substrate (such as metal foil) are laminated via an adhesive, the adhesive is not particularly limited as long as it is a heat-resistant adhesive used in the electronic field, and examples thereof include polyimide-based adhesives, epoxy-modified polyimide-based adhesives, phenol resin-modified epoxy resin adhesives, epoxy-modified acrylic resin adhesives, epoxy-modified polyamide-based adhesives, etc. The heat-resistant adhesive layer may be provided by any method itself used in the electronic field, for example, the above-mentioned polyimide film or the formed product may be coated with an adhesive solution and dried, or a film-like adhesive formed separately may be laminated.

[0144] In the above (i) and (iii), examples of the substrate include metal foils of elemental metals or alloys such as copper, aluminum, gold, silver, nickel or stainless steel, and metal plating (vapor-deposited metal base-metal plating or chemical metal plating, or other known techniques may be preferably applied), and preferred examples include wound copper foil, electrolytic copper foil, copper plating, etc. The thickness of the metal foil is not particularly limited, but is preferably 0.1 μm to 10 mm, more preferably 1 μm to 50 μm and particularly preferably 5 μm to 18 μm.

[0145] As the dry method (metallization method) used in (ii) above, known methods such as vacuum deposition, sputtering, ion plating and electron beam can be used. As the metal used for the metallization method, metals such as copper, nickel, chromium, manganese, aluminum, iron, molybdenum, cobalt, tungsten, vanadium, titanium, tantalum or their alloys, or oxides of these metals, carbides of these metals, etc. can be used, but are not particularly limited to these materials. The thickness of the formed metal layer is, for example, 1nm to 500nm, and the metal plating of copper, tin, etc. can be provided on the surface with a thickness of, for example, 1μm to 40μm by known wet plating methods such as electrolytic plating or electroless plating.

[0146] As the wet method (plating method) used in (ii) above, a known plating method can be used, and examples of the plating method include electrolytic plating and electroless plating, and a combination of these methods can be adopted. The metal used for wet plating is not limited as long as it can be wet plated.

[0147] The thickness of the metal layer formed by the wet plating method can be appropriately selected according to the purpose of use, and is preferably 0.1 μm to 50 μm, more preferably 1 μm to 30 μm, for practical use. The number of layers of the metal layer formed by the wet plating method can be appropriately selected according to the purpose of use, and can be one layer, two layers, or three layers or more.

[0148] Wet plating methods include the conventionally known Elfseed process available from Ebara-Udylite Co., Ltd., and the catalyst bonding process available from JX Nippon Mining & Metals Co., Ltd., which is a surface treatment process, followed by electroless copper plating.

[0149] Since the polyimide film of the present invention has a small dielectric loss tangent in the high frequency band and has excellent heat resistance, the polyimide metal laminate of the present invention (including a laminate obtained by laminating a film and a metal layer via an adhesive layer, and a laminate obtained by directly forming a metal layer on a film) can be suitably used for flexible wiring board applications. That is, the flexible wiring board can be produced by patterning the metal foil (or metal layer) of the polyimide metal laminate by a known method for forming wiring.

[0150] The polyimide precursor composition, polyimide film or polyimide metal laminate of the present invention can be used not only for flexible wiring boards but also for TAB tapes, COF tapes, flexible heaters, resistor substrates, insulating films, protective films and the like.

[0151] Example

[0152] The present invention will be described in more detail with reference to Examples and Comparative Examples.

[0153] The following abbreviations are used below:

[0154] <Tetracarboxylic acid>

[0155] s-BPDA: 3,3',4,4'-biphenyltetracarboxylic dianhydride

[0156] PMDA: trimellitic dianhydride

[0157] ODPA: Oxydiphthalic dianhydride (also known as bis(3,4-dicarboxyphenyl) ether dianhydride)

[0158] TAHQ: 1,4-phenylenebis(1,3-dioxo-1,3-dihydroisobenzofuran-5-carboxylate) (also known as p-phenylenebis(trimellitic anhydride))

[0159] <Diamine>

[0160] PPD: p-phenylenediamine

[0161] DATP: 4,4"-diaminoterphenyl

[0162] m-TB: 2,2'-dimethyl-4,4'-diaminobiphenyl (also known as m-tolidine)

[0163] BPTP: Bis(4-aminophenyl)terephthalate

[0164] APBP: Bis(4-aminophenyl)biphenyl-4,4'-dicarboxylate

[0165] BAPB: 4,4'-bis(4-aminophenoxy)biphenyl

[0166] TPE-R: 1,3-bis(4-aminophenoxy)benzene

[0167] BAPP: 2,2-bis[4-(4-aminophenoxy)phenyl]propane

[0168] <Others>

[0169] DMAc: N,N-dimethylacetamide

[0170] Table 1 shows the structural formulas of the tetracarboxylic acid component and the diamine component.

[0171] Table 1

[0172]

[0173] <Evaluation of polyimide film>

[0174] [Glass transition temperature (Tg)]

[0175] The dynamic viscoelasticity of the polyimide film was measured using a TA Instruments RSA G2 dynamic viscoelasticity measuring apparatus at a temperature increase rate of 10° C. / min and a frequency of 1 Hz, and the tan δ peak temperature was taken as the glass transition temperature.

[0176] [Dielectric loss tangent]

[0177] A split cylindrical resonator 10 GHz CR-710 (manufactured by EM Lab) was used as a measuring device, and the dielectric loss tangent of the polyimide film was measured under the following conditions:

[0178] Measurement frequency: 10GHz

[0179] Measurement conditions: temperature 25±2℃, humidity 60±2% RH

[0180] Measurement sample: Use a sample that has been left to stand for 48 hours under the above measurement conditions.

[0181] [5% weight loss temperature (Td5)]

[0182] A polyimide film having a thickness of about 25 μm was used as a test piece, and the test piece was heated from 30° C. to 700° C. at a heating rate of 10° C. / min in a nitrogen gas stream using a thermogravimetric measuring apparatus (Q5000IR) manufactured by TA Instruments Inc. The 5% weight reduction temperature was determined from a weight curve obtained by taking the weight at 150° C. as 100%.

[0183] [Solder heat resistance test]

[0184] Copper foil (manufactured by Fukuda Metal Foil and Powder Co., Ltd., CF-T49A-DS-HD2, thickness 12 μm) was placed on both sides of the multilayer polyimide film, and the resulting laminate was hot pressed at a temperature of 360°C, preheated for 2 minutes, a hot press pressure of 3 MPa, and a pressing time of 2 minutes to obtain a copper-clad laminate with copper foil laminated on both sides of the multilayer polyimide film. A resist was printed on a portion of one side of the copper-clad laminate and the entire surface of the other side, and the laminate was immersed in an etching solution at 30°C for 20 to 30 minutes to obtain a laminate in which the metal layer on one side was partially etched and the copper foil on the entire surface of the other side was maintained. The resulting laminate was dried at 80°C for 30 minutes and humidified in an environment of 85°C-85% RH for more than 24 hours. The sample was floated in a solder bath of various temperatures for 60 seconds to check whether the sample had foaming. The highest temperature at which foaming was not confirmed was taken as the solder heat resistance temperature.

[0185] <Example 5>

[0186] [Preparation of polyimide precursor composition]

[0187] DMAc was added to a reaction vessel equipped with a stirrer and a nitrogen inlet tube, and then PPD and BDTP as diamine components were added. Next, s-BPDA as a tetracarboxylic dianhydride component was added in an equimolar amount to the diamine component and reacted to obtain a polyimide precursor composition having a monomer concentration of 18% by mass and a solution viscosity of 1800 poise at 30° C. The molar ratio of PPD to BPTP was 80:20.

[0188] [Method for producing polyimide film]

[0189] The polyimide precursor composition was cast on a glass plate in the form of a film, heated in an oven at 120° C. for 12 minutes, and then peeled off from the glass plate to obtain a self-supporting film. The four sides of the self-supporting film were fixed with a pin tenter, and then gradually heated from 150° C. to 450° C. (maximum heating temperature: 450° C.) in a heating furnace to remove the solvent and imidize the film, thereby obtaining a polyimide film.

[0190] The thickness of the polyimide film was about 25 μm.

[0191] <Examples 1 to 4 and 6 to 19, Comparative Examples 1 to 6>

[0192] The polyimide precursor composition was prepared in the same manner as in Example 5, except that the tetracarboxylic acid component and the diamine component were changed to the compounds and amounts (molar ratios) shown in Table 2. Thereafter, a polyimide film was produced in the same manner as in Example 5, and the physical properties of the film were evaluated. The evaluation results are shown in Table 2.

[0193] Table 2

[0194]

[0195] Table 2 shows that the addition of BPTP has the effect of reducing the dielectric loss tangent. When the addition amount of BPTP accounts for more than 30 mol% of the diamine component, the glass transition temperature (Tg) decreases more than the comparative example without adding BPTP. The addition of APBP also has the effect of reducing the dielectric loss tangent.

[0196] As described above, according to the present invention, it has been shown that the dielectric loss tangent and the glass transition temperature (Tg), which are properties required for a flexible copper-clad laminate and production thereof, are achieved in a well-balanced manner.

[0197] <Multilayer polyimide film>

[0198] A multilayer polyimide film having a three-layer structure of melt-adhesive PI layer / heat-resistant PI layer / melt-adhesive PI layer was produced, wherein the polyimide film of the present invention was used as a heat-resistant PI layer (core layer). The polyimide precursor composition for producing the core layer was prepared in the same manner as in Example 5, except that the tetracarboxylic acid component and the diamine component in Example 5 were changed to the compounds and amounts (molar ratios) shown in Table 3.

[0199] [Preparation of polyimide precursor composition providing melt-adhesive polyimide]

[0200] DMAc was added to a reaction vessel equipped with a stirrer and a nitrogen inlet tube, and then BAPP as a diamine component was added. Next, s-BPDA and PMDA as tetracarboxylic dianhydride components were added in an equimolar amount to the diamine component and reacted to obtain a polyimide precursor composition having a monomer concentration of 18% by mass and a solution viscosity of 800 poise at 30° C. The molar ratio of s-BPDA to PMDA was 30:70.

[0201] [Method for producing polyimide film]

[0202] The polyimide precursor composition for producing the core layer and the polyimide precursor composition for forming the melt-bonding layer are extruded and cast into a film on the upper surface of a smooth metal carrier from a three-layer extrusion die, thereby having a structure of melt-bonding PI layer / heat-resistant PI layer / melt-bonding PI layer. The film casting product is continuously dried with hot air at 140°C to form a self-supporting film. The self-supporting film is peeled off from the carrier, and then the self-supporting film is gradually heated from 200°C to 390°C (the maximum heating temperature is 390°C) in a heating furnace to remove the solvent and imidize the film, thereby producing a multilayer polyimide film with a three-layer structure of 50μm (5.7μm / 38.6μm / 5.7μm) in thickness.

[0203] The measurement results of the dielectric loss tangent and the results of the solder heat resistance test of the produced multilayer polyimide films are shown in Table 3.

[0204] Table 3

[0205]

[0206] In addition, when a polyimide film having the composition of the present invention is used as a heat-resistant PI layer (core layer), these results show that the multilayer polyimide film has a small dielectric loss tangent and excellent solder heat resistance, and is therefore ideal for producing flexible copper-clad laminates.

[0207] Industrial Applicability

[0208] The polyimide film produced from the polyimide precursor composition of the present invention can be suitably used for flexible wiring board applications.

Claims

1. A polyimide precursor composition for a flexible wiring board, comprising a polyimide precursor having a repeating unit represented by the following general formula (I): in, In the general formula I, X1 is a tetravalent aliphatic group or an aromatic group, Y1 is a divalent aliphatic group or an aromatic group, R1 and R2 are each independently a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an alkylsilyl group having 3 to 9 carbon atoms, Among them, more than 0 mol% and less than 30 mol% of Y1 is a group represented by formula (1): Wherein, in formula (1), A is a structure represented by formula (A): wherein n is an integer of 1 to 4, m is an integer of 0 to 4, B is one selected from the group consisting of an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, a halogen group and a fluoroalkyl group having 1 to 6 carbon atoms, and U independently represents -CO-O- or -O-CO-.

2. The polyimide precursor composition according to claim 1, wherein A is a structure selected from the group consisting of 1,4-phenylene and 4,4′-biphenylene.

3. The polyimide precursor composition according to any one of claims 1 to 3, wherein 50 mol % or more of X1 is a group represented by the following formula (21): 。 4 . A polyimide film for a flexible wiring board, obtained from the polyimide precursor composition according to claim 1 . 5 . A polyimide metal laminate comprising the polyimide film according to claim 4 , and a metal foil or a metal layer laminated with the polyimide film. 6 . A flexible wiring board having wiring formed by patterning the metal foil or the metal layer of the polyimide metal laminate according to claim 5 .

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