JP2015515402A - Flexible metal-clad laminate - Google Patents

Abstract

The present invention is a flexible metal-clad laminate in which a metal layer is formed on one or both sides of an insulating layer composed of a plurality of polyimide resin layers, and the polyimide resin layer in contact with the metal layer is at 300 ° C. It relates to a flexible metal-clad laminate having a storage elastic modulus of 1-10 8 Pa or higher and a storage elastic modulus at 350 ° C. of 1-10 8 Pa or lower, and does not cause curling and adheres to the metal tension. It has good strength, a small dimensional change rate after heat treatment, and particularly excellent solder resistance after moisture absorption (Soder-Resistance). [Selection figure] None

Description

  The present invention relates to a flexible metal clad laminate used in the manufacture of a flexible printed circuit board, and does not cause curling in the product, has good adhesion to the metal tension, and after heat treatment In addition to having a small dimensional change rate, the soldering resistance (Soder-Resistance) after moisture absorption is particularly excellent.

  Flexible Metal Clad Laminate, which is used to manufacture Flexible Printed Circuit Boards, is a laminate of conductive metal foil and insulating resin, and is used for fine circuit processing. Since it is possible to bend in a narrow space, its use is increasing with the trend toward smaller and lighter electronic devices. Flexible metal-clad laminates can be divided into two-layer and three-layer methods, but the three-layer method using an adhesive is inferior in heat resistance and flame resistance to the two-layer method, and changes in dimensions occur during the heat treatment process. There is a big problem of doing. Accordingly, the recent trend in the production of flexible printed circuit boards is generally to use a two-layer flexible metal-clad laminate rather than a three-layer method.

  In recent years, the use of double-sided metal-clad laminates has been increasing due to the trend of making the circuit lighter and thinner. Double-sided metal-clad laminates are usually manufactured by laminating a thermoplastic polyimide formed on the outermost layer of an insulating layer with a metal foil, but due to the presence of the thermoplastic polyimide resin, the solder resistance after moisture absorption of the insulating layer There is a problem that (Solder-Resistance) becomes poor. In particular, while the normal soldering temperature is about 200 ° C., the temperature in the recent lead-free soldering process is as high as 250 ° C. or higher, so that the solder resistance after moisture absorption is more important.

  As a conventional technique, Patent Document 1 exemplifies using a polyimide resin having a special structure as a thermoplastic polyimide resin layer. In this case, the moisture absorption heat resistance temperature is only 260 ° C., and under severe conditions of 300 ° C. or more. There is a problem in solder resistance.

JP 2002-363284 A

  The present invention relates to a flexible metal-clad laminate used for the production of a printed circuit board and a method for producing the same, and has excellent solder-resistance after moisture absorption even at 300 ° C. or higher, and curling of the product (Curling The purpose of the present invention is to solve the problems of the prior art by providing a flexible metal-clad laminate that has a high bonding strength with copper foil and that has a small rate of dimensional change after heat treatment. To do.

In order to achieve the above object, the present invention provides a flexible metal-clad laminate in which a metal layer is formed on one side or both sides of an insulating layer composed of a plurality of polyimide resin layers, the polyimide being in contact with the metal layer The system resin layer provides a flexible metal-clad laminate having a storage elastic modulus at 300 ° C. of 1 × 10 ⁸ Pa or more and a storage elastic modulus at 350 ° C. of 1 × 10 ⁸ Pa or less.

  The present invention is a flexible metal-clad laminate that has excellent solder resistance after moisture absorption, does not cause curling of the product, has high bonding strength with copper foil, and has a small dimensional change rate after heat treatment Provide the body.

The present invention is a flexible metal-clad laminate in which a metal layer is formed on one or both sides of an insulating layer composed of a plurality of polyimide resin layers, and the polyimide resin layer in contact with the metal layer is at 300 ° C. Provided is a flexible metal-clad laminate having a storage elastic modulus of 1 × 10 ⁸ Pa or more and a storage elastic modulus at 350 ° C. of 1 × 10 ⁸ Pa or less.

  The present invention provides a flexible metal-clad laminate in which the plurality of polyimide resin layers are laminated in the order of thermoplastic polyimide resin layer / thermosetting polyimide resin layer / thermoplastic polyimide resin layer. provide.

  The polyimide resin layer in contact with the metal layer is a thermoplastic polyimide resin layer having a glass transition temperature of 300 ° C. or lower.

  The polyimide resin layer in contact with the metal layer has a linear thermal expansion coefficient measured between 100 ° C. and 200 ° C. of 50 ppm / K or less.

  Moreover, the flexible metal-clad laminate manufactured with the polyimide resin layer according to the present invention has a moisture absorption and soldering resistance temperature of 300 ° C. or higher after being treated for 72 hours at 40 ° C. and a relative humidity of 90%. The adhesive strength is 1.0 kgf / cm or more.

  The present invention also provides a flexible metal-clad laminate, wherein the polyimide resin layer in contact with the metal layer contains 50 to 100 mol% of a structural unit represented by the following chemical formula 1.

[Chemical Formula 1]

  -X- contained in the chemical formula 1 is an aromatic diamino compound containing one or more selected from the following structures, and these can be used alone or in a copolymerized form.

-X ₁ -represents -O-, -CO-, -S-, -SO _2- , -C (CH ₃ ) _2- , -CONH-, -C (CF ₃ ) ₂ -,-(CH ₂ ) -Or a combination thereof.

は、下記の構造から選択される１つまたは２つ以上を含む二無水物であって、これらを単独でまたは共重合して使用することができる。 Included in Chemical Formula 1

Is a dianhydride containing one or two or more selected from the following structures, and these can be used alone or copolymerized.

  Hereinafter, it demonstrates in detail centering on the structure of invention.

  The present invention provides a flexible metal-clad laminate in which a metal tension is formed on one side or both sides of an insulating layer, and the multilayered structure is composed of a plurality of polyimide resins.

  The plurality of polyimide resin layers have a form in which thermoplastic polyimide resin layer / thermosetting polyimide resin layer / thermoplastic polyimide resin layer are laminated in this order.

  A flexible metal-clad laminate can be produced by forming a single polyimide-based resin layer on the metal-clad layer, but in this case, there are the following problems. First, when using a single thermosetting polyimide resin layer, the adhesive process with the metal foil is low, and there is no thermoplastic polyimide resin layer. The body cannot be manufactured. In addition, there is a problem that the product curls before and after etching. On the other hand, when a single thermoplastic polyimide resin is used, the coefficient of dimensional change after heat treatment is high due to the high coefficient of linear thermal expansion of the insulating layer, and the product curls before and after etching. is there. Accordingly, the insulating layer constituting the flexible metal-clad laminate of the present invention has a multilayer structure composed of a plurality of polyimide resin layers, and is a thermoplastic polyimide resin layer / thermosetting polyimide resin layer / thermoplastic. It is composed of a polyimide resin layer.

The thermoplastic polyimide resin layer according to the present invention means a polyimide resin layer in contact with the metal layer, and has a storage elastic modulus at 300 ° C. of 1 × 10 ⁸ Pa or more and a storage elastic modulus at 350 ° C. of 1 × 10. ⁸ Pa or less.

More specifically, the storage elastic modulus at 300 ° C. is 1 × 10 ⁸ Pa or more and 1 × 10 ¹⁰ Pa or less, and the storage elastic modulus at 350 ° C. is 1 × 10 ⁸ Pa or less, 1 × 10 ⁵ Pa or more. It is preferable that

When the storage elastic modulus at 300 ° C. is less than 1 × 10 ⁸ Pa, there is a problem in the solder resistance after moisture absorption, and when it exceeds 1 × 10 ¹⁰ Pa, the brittleness of the material increases, and bending There is a problem that the characteristics deteriorate. Further, when the storage elastic modulus at 350 ° C. exceeds 1 × 10 ⁸ Pa, the thermoplasticity is insufficient, and when it is less than 1 × 10 ⁵ Pa, the resin flows in a molten state. There is a problem that the laminating process becomes difficult.

  Further, the thermoplastic polyimide resin layer according to the present invention has a glass transition temperature of 300 ° C. or lower, more preferably 200 to 300 ° C.

When the thermoplastic polyimide resin layer does not satisfy the above-mentioned conditions, for example, when the glass transition temperature exceeds 300 ° C. and the storage elastic modulus measured at 350 ° C. exceeds 1 × 10 ⁸ Pa, the moisture resistance after moisture absorption is increased. Although solderability is good, there is a problem that the laminating process is impossible due to insufficient flowability of resin at high temperature, and the bonding strength with other base materials such as coverlay and prepreg is low. . Considering the above problems, the thermoplastic polyimide resin layer constituting the present invention has a glass transition temperature of 300 ° C. or lower and a storage elastic modulus at 350 ° C. of 1 × 10 ⁸ Pa or lower. And

When the polyimide resin after moisture absorption is immersed in a high-temperature solder bath, the moisture that has been absorbed rapidly volatilizes and the layers are separated between the polyimide resin layers or at the interface between the polyimide resin layer and the metal-clad layer. In addition, defects such as foaming and expansion inside the resin layer occur. When the polyimide resin is immersed in a high-temperature solder bath, the moisture absorbed inside the resin layer is rapidly vaporized. At this time, the storage elastic modulus is such that the polyimide resin can withstand the water vapor pressure of moisture. If it has, it is thought that the appearance defect by immersion in a solder tank does not occur. As a result of continuing research from this point of view, in order to have moisture absorption solder resistance of 300 ° C. or higher even after absorbing moisture for 72 hours or more at 40 ° C. and 90% relative humidity, the storage elastic modulus measured at 300 ° C. is 1 ×. The conclusion was reached that it must be 10 ⁸ Pa or higher. As a result, it was possible to produce a flexible metal-clad laminate particularly excellent in solder resistance after moisture absorption (Solder-Resistance).

  Further, the thermoplastic polyimide resin layer in contact with the metal layer has a linear thermal expansion coefficient measured between 100 ° C. and 200 ° C. of 50 ppm / K or less.

  More specifically, the linear thermal expansion coefficient is preferably 17 to 50 ppm / K.

In order to prevent curling of the flexible metal-clad laminate and increase the dimensional stability after heat treatment, the linear thermal expansion coefficient of the entire insulating layer must be low. Since the linear thermal expansion coefficient of the thermoplastic polyimide resin layer is higher than that of the thermosetting polyimide resin layer, the linear thermal expansion coefficient of the thermoplastic polyimide resin layer is used to control the linear thermal expansion coefficient of the entire insulating layer. It is essential to control. In order to control the linear thermal expansion coefficient of the thermoplastic polyimide resin layer, a thermoplastic polyimide resin having a high high temperature elastic modulus that is not easily deformed even in a high temperature region is required. The thermoplastic polyimide resin layer of the present invention has a storage elastic modulus measured at 300 ° C. of 1 × 10 ⁸ Pa or higher, and has a high storage elastic modulus at high temperature, and thus was measured in the range of 100 ° C. to 200 ° C. The linear thermal expansion coefficient is 50 ppm / K or less.

  Next, the polyimide resin according to the present invention will be described.

  The precursor of the polyimide resin used in the present invention is obtained by reacting diamine and acid dianhydride in an organic solvent. Under an inert atmosphere such as argon or nitrogen, diamine is dissolved or diffused in a slurry state in an organic solvent, and acid dianhydride is dissolved in an organic solvent and added in a slurry state or in a solid state.

  The solvent used in the synthesis of the polyimide precursor solution is not particularly limited as long as the polyimide precursor is dissolved. For example, sulfoxide solvents such as dimethyl sulfoxide and diethyl sulfoxide, formamide solvents such as N, N-dimethylformamide and N, N-diethylformamide, and acetamide solvents such as N, N-dimethylacetamide and N, N-diethylacetamide Pyrrolidone solvents such as N-methyl-2-pyrrolidone and N-vinyl-2-pyrrolidone, phenol solvents such as phenol, o-, m-, or p-cresol, xylenol, halogenated phenol, catechol, diglyme, Examples include ether solvents such as triglyme, tetraglyme, tetrahydrofuran, and dioxy acid, alcohol solvents such as methanol, ethanol, and butanol, cellosolves such as butyl cellosolve, hexamethylphosphoramide, and γ-butyrolactone. Is, it is preferable to use them alone or as a mixture, further, xylene, aromatic hydrocarbons such as toluene can be used.

  The dianhydride contained in the plurality of polyimide resin layers according to the present invention is not particularly limited as long as it is an acid dianhydride. For example, 2,2 ′ hexafluoropropylidenedibutanoic acid dianhydride, 2, 2-bis (4-hydroxyphenyl) propanedibenzoate-3,3'4,4'tetracarboxylic dianhydride, butanetetracarboxylic dianhydride, 1,2,3,4-cyclobutanetetracarboxylic dianhydride 1,3-dimethyl-1,2,3,4-cyclobutanetetracarboxylic acid, 1,2,3,4-cyclopentanetetracarboxylic dianhydride, 2,3,5-tricarboxycyclopentylacetic acid dianhydride 3,5,6-tricarboxynorponane-2-acetic dianhydride, 2,3,4,5-tetrahydrofurantetracarboxylic dianhydride, 5- (2,5-dioxytetra (Drofural) -3-methyl-3-cyclohexene-1,2-dicarboxylic dianhydride, bicyclo [2,2,2] -oct-7-one-2,3,5,6-tetracarboxylic dianhydride Aliphatic or alicyclic tetracarboxylic dianhydrides such as pyromellitic dianhydride, 3,3′4,4′benzophenone tetracarboxylic dianhydride, 3,3′4,4′biphenylsulfone tetracarboxylic dianhydride Anhydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 3,3'4,4'biphenyl ether tetracarboxylic dianhydride 3,3'4,4 'dimethyldiphenylsilane tetracarboxylic dianhydride, 3,3'4,4' tetraphenylsilane tetracarboxylic dianhydride, 1,2,3,4-furantetracarbo Acid dianhydride, 4,4′bis (3,4-dicarboxyphenoxy) diphenyl sulfide dianhydride, 4,4′bis (3,4-dicarboxyphenoxy) diphenylsulfone dianhydride, 4,4 ′ -Bisphenol A dianhydride, 3,3'4,4'perfluoroisopropylidenediphthalic dianhydride, 3,3'4,4'-biphenyltetracarboxylic dianhydride, bis (phthalic acid) phenylphosphine Oxide dianhydride, p-phenylene-bis (triphenylphthalic acid) dianhydride, m-phenylene-bis (triphenylphthalic acid) dianhydride, bis (triphenylphthalic acid) -4,4 'diphenyl ether dianhydride Products, 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride, and bis (triphenylphthalic acid) -4,4′diphenylmethane dianhydride Aromatic tetracarboxylic dianhydrides are mentioned.

  The diamine contained in the plurality of polyimide resin layers according to the present invention is not particularly limited. For example, p (para) -phenylenediamine, m-phenylenediamine, 4,4′diaminodiphenylmethane, 4,4′diaminodiphenylethane. 4,4′diaminodiphenyl ether, 4,4′diaminophenyl sulfide, 4,4′diaminophenylsulfone, 1,5-diaminonaphthalene, 3,3-dimethyl-4,4′diaminobiphenyl, 3,5-diamino- Benzoic acid, 5-amino-1- (4′aminophenyl) -1,3,3-trimethylindane, 6-amino-1- (4′aminophenyl) -1,3,3-trimethylindane, 4,4 'Diaminobenzanilide, 3,5-diamino-3'trifluoromethylbenzanilide, 3,5-diamino-4' Trifluoromethylbenzanilide, 3,4'diaminodiphenyl ether, 2,7-diaminofluorene, 2,2-bis (4-aminophenyl) hexafluoropropane, 4,4'methylene-bis (2-chloroaniline), 2 , 2′5,5′tetrachloro-4,4′-diaminobiphenyl, 2,2′dichloro-4,4′diamino-5,5′dimethoxybiphenyl, 3,3′dimethoxy-4,4′diaminophenyl, 4,4'diamino-2,2'bis (trifluoromethyl) biphenyl, 2,2-bis [4- (4-aminophenoxy) phenyl] propane, 2,2-bis [4- (4-aminophenoxy) Phenyl] hexafluoropropane, 1,4-bis (4-aminophenoxy) benzene, 4,4-bis (4-aminophenoxy) -biphenyl, 3-bis (4-aminophenoxy) benzene, 9,9-bis (4-aminophenyl) fluorene, 4,4 ′ (p-phenyleneisopropylidene) bisaniline, 4,4 ′ (m-phenyleneisopropylidene) bisaniline, 4,4′-oxydianiline, 2,2′bis [4- (4-amino-2-trifluoromethylphenoxy) phenyl] hexafluoropropane, 4,4′bis [4- (4-amino-2- Aromatic diamines such as (trifluoromethyl) phenoxy] -octafluorophenyl; aromatic diamines having two amino groups bonded to the aromatic ring and hetero atoms other than nitrogen atoms of the amino group, such as diaminotetraphenylthiophene ; 1,1-metaxylenediamine, 1,3-propanediamine, tetramethylenediamine, pentamethyle Diamine, Octamethylenediamine, Nonamethylenediamine, 4,4-Diaminoheptanemethylenediamine, 1,4-Diaminocyclohexane, Isophoronediamine, Tetrahydrodicyclopentadienylenediamine, Hexahydro-4,7-methanoindanylenediethylenediamine And aliphatic diamines such as 4,4′methylenebis (cyclohexylamine) and alicyclic diamines.

  Specifically, in consideration of the above-described physical properties, the thermoplastic polyimide resin layer constituting the present invention preferably contains 50 to 100 mol% of a structural unit represented by the following chemical formula 1.

[Chemical Formula 1]

  -X- included in Chemical Formula 1 is an aromatic diamino compound containing one or more selected from the following structures, and these may be used alone or in a copolymerized form.

-X ₁ -represents -O-, -CO-, -S-, -SO _2- , -C (CH ₃ ) _2- , -CONH-, -C (CF ₃ ) ₂ -,-(CH ₂ ) -Or a combination thereof.

は、下記の構造から選択される１つまたは２つ以上を含む二無水物であって、これらを単独でまたは共重合して使用することができる。 Included in Chemical Formula 1

Is a dianhydride containing one or two or more selected from the following structures, and these can be used alone or copolymerized.

は、下記構造から選択される１つまたは２つ以上を含む二無水物であることを特徴とするフレキシブル金属張積層体を提供する。 More specifically, —X ₁ — is an aromatic diamino compound containing —O—,

Provides a flexible metal-clad laminate characterized by being a dianhydride containing one or more selected from the following structures.

The thermoplastic polyimide resin layer according to the present invention preferably contains 50 to 100 mol% of a structural unit represented by the following chemical formula 1. When it is less than 50 mol%, the storage elastic modulus at 350 ° C. exceeds 1 × 10 ⁸ Pa, and the thermoplastic polyimide resin layer has insufficient fluidity at a high temperature, making the lamination process impossible. There's a problem.

  The polyimide resin in the present invention includes all resins having an imide ring represented by the following chemical formula 2, and examples thereof include polyimide, polyamideimide, polyesterimide, and siloxane-modified polyimide. Moreover, what consists of a mixture which mixed not only the polyimide resin single body but the above-mentioned polyimide resin and other polymer resin is included. In addition, curing additives such as pyridine and quinoline, coupling agents such as silane, adhesion imparting agents such as epoxy, and other additives such as antifoaming agents and leveling agents for facilitating the coating process were mixed. Including things.

[Chemical formula 2]

  The method for producing the flexible metal-clad laminate of the present invention includes a casting method and a laminating method. In the casting method, a polyamic acid resin, which is a precursor of a polyimide resin, is applied on a metal layer, and then a polyimide resin layer is formed through a thermal / chemical conversion process. In addition, the casting method is a casting method in which a double-sided flexible metal-clad laminate is manufactured by laminating a new metal layer on one side of a cast-type single-sided flexible metal-clad laminate formed by the above method. A double-sided flexible metal-clad laminate. Laminating method is to manufacture in advance a polyimide film having a multilayer structure of thermoplastic polyimide resin layer / thermosetting polyimide resin layer / thermoplastic polyimide resin layer, and laminate a metal layer on one or both sides thereof. To manufacture.

  Here, the thermoplastic polyimide resin layer is characterized by containing 50 to 100 mol% of a structural unit represented by the following chemical formula 1, for example, pyromellitic dianhydride as acid dianhydride and diamine 1,3-bis (4-aminophenoxy) benzene (1,3-bis (4-aminophenoxy) benzene) is reacted so as to be 50 to 100 mol% of the whole polyimide to produce amic acid, After applying this, it can manufacture by heating and imidizing.

  Although the thermosetting polyimide resin layer is not particularly limited, according to an embodiment of the present invention, p-phenylenediamine and 4,4′-oxydianiline (4,4′-oxydianiline) are used as diamines. ) And 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride as an acid dianhydride, It can be manufactured by reacting to 100 mol% to produce amic acid, coating this, and imidizing by heating.

  At this time, imidation is performed by a dehydration condensation reaction, the reaction temperature is preferably 100 to 400 ° C., and the reaction time is 10 minutes to 24 hours, but is not particularly limited thereto.

  The solvent used in the synthesis is not particularly limited as long as the polyamic acid, which is a polyimide precursor, can be dissolved, and sulfoxide solvents such as dimethyl sulfoxide and diethyl sulfoxide, N, N-dimethylformamide, N, N- Formamide solvents such as diethylformamide, N, N-dimethylacetamide, acetamide solvents such as N, N-diethylacetamide, pyrrolidone solvents such as N-methyl-2-pyrrolidone and N-vinyl-2-pyrrolidone, phenol, Phenolic solvents such as o-, m-, or p-cresol, xylenol, halogenated phenol, catechol, ether solvents such as diglyme, triglyme, tetraglyme, tetrahydrofuran, dioxyacid, alcohols such as methanol, ethanol, butanol Melting , Cellosolve such as butyl cellosolve or hexamethylphosphoramide and γ-butyrolactone can be used, and these are preferably used alone or as a mixture, and moreover, aromatic hydrocarbons such as xylene and toluene Can also be used.

  The metal layer constituting the flexible metal-clad laminate means a conductive metal such as copper, aluminum, silver, palladium, nickel, chromium, molybdenum, and tungsten, and includes an alloy or a mixture thereof. Usually, copper is widely used, but is not necessarily limited thereto. Further, the metal layer of the present invention includes those obtained by subjecting the surface of the metal layer to physical or chemical surface treatment in order to increase the bond strength between the metal tension and the resin layer.

  Examples of the coating method applicable to the present invention include knife coating, roll coating, die coating, curtain coating and the like, and the method is not limited as long as the object required by the present invention is satisfied. As the coating solution, not only a polyimide precursor solution but also a precured polyimide solution in a radiused or fully-cured state may be used.

  The process of drying and curing the insulating layer after coating can be applied selectively and known methods such as hot air curing, IR curing, batch curing, continuous curing, and chemical curing. Various methods can be applied.

  Hereinafter, the present invention will be described in detail by experimental examples. However, the present invention is not necessarily limited to these examples.

  Abbreviations used in the examples are as follows.

  DMAc: N, N-dimethylacetamide

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

  p-PDA: para-phenylenediamine

  ODA: 4,4'-oxydianiline

  BAPP: 2,2-bis (4-aminophenoxy) phenylpropane

  DABA: 3,5-diamino-benzoic acid

  BPDA: 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride

  PMDA: pyromellitic dianhydride

  BPADA: 4,4'-bisphenol A dianhydride

  BTDA: 3,3 ′, 4,4′-benzophenone tetracarboxylic dianhydride

  TMEG: Ethylene glycol bis (trimellitic dianhydride)

  The physical properties mentioned in the present invention were measured by the following methods.

● Linear thermal expansion coefficient The linear thermal expansion coefficient was measured using a TMA / SDTA861e from Mettler-Toledo with a tension of 0.03N and a temperature of 30 ° C to 400 ° C at a rate of 5 ° C / min in a nitrogen atmosphere. It was measured. Among the measured values, an average value of linear thermal expansion coefficients measured in units of 25 ° C. in a section between 100 ° C. and 200 ° C. was defined as a linear thermal expansion coefficient from 100 ° C. to 200 ° C.

● Storage modulus
Measurement was performed using Mettler-Toledo DMA / SDTA861e under conditions of a tension of 0.1 N, a frequency of 10 Hz, and a displacement of 30 μm while raising the temperature from 30 ° C. to 400 ° C. at a rate of 5 ° C./min.

-Glass transition temperature DMA was used on the same conditions as the storage elastic modulus measurement, and the maximum value of Tan δ obtained at this time was defined as the glass transition temperature.

● Evaluation of thermoplastic polyimide In the thermoplastic polyimide resin of the present invention, a polyimide resin having a storage elastic modulus at 350 ° C. of 1 × 10 ⁸ Pa or less is regarded as a thermoplastic polyimide resin, and storage elasticity at 350 ° C. The case where the rate was 1 × 10 ⁸ Pa or more was regarded as a thermosetting polyimide resin. The storage modulus measurement was based on the method described above.

● Moisture absorption and solder resistance After a test piece of size 5cm x 5cm is treated for 72 hours or more in a constant temperature and humidity chamber at 40 ° C / 90% relative humidity, it expands when immersed in a 300 ° C solder bath. When no defect in appearance such as layer separation occurred, Pass was designated, and when an appearance defect occurred, Fail was designated. In the case of a single-sided copper-clad laminate, the evaluation was made of a specimen having a copper foil and an insulating layer without removing the copper foil. In the case of a double-sided copper-clad laminate, the evaluation was performed after the copper foil was detached on one side, and each side was evaluated.

● Adhesive strength with copper foil Measured according to JIS-C6471.

[Synthesis Example 1]
After p-PDA and ODA were completely dissolved in DMAc at a 90:10 mol% ratio at room temperature, 100.9 mol% of BPDA was gradually added to the solution. The mixture was reacted at room temperature for 24 hours. At this time, the solid content in the whole solution was set to 13% by weight.

[Synthesis Example 2 to Synthesis Example 5]
It manufactured according to the component and content of Table 1 on the manufacturing conditions similar to the synthesis example 1.

＊Ｅ´＠３００℃：３００℃での貯蔵弾性率
＊Ｅ´＠３５０℃：３５０℃での貯蔵弾性率
＊ＣＴＥ：１００〜２００℃範囲で測定した線熱膨張係数
＊Ｔｇ：ガラス転移温度

* E '@ 300 ° C: storage elastic modulus at 300 ° C * E' @ 350 ° C: storage elastic modulus at 350 ° C * CTE: linear thermal expansion coefficient measured in the range of 100 to 200 ° C * Tg: glass transition temperature

[Example 1]
The thickness after final curing of the polyamic acid solution produced in Synthesis Example 2 on an electrolytic copper foil of 12 μm thickness (Furukawa Circuit Foil, F2WS copper foil, illuminance Rz = 2.0 μm) is 2.5 μm. After apply | coating in this way, the 1st polyimide precursor layer was formed by drying at 140 degreeC. After applying the polyamic acid solution manufactured in Synthesis Example 1 on one surface of the first polyimide precursor layer so that the thickness after final curing is 14 μm, it is dried at 140 ° C. A body layer was formed. Thereafter, the polyamic acid solution produced in Synthesis Example 2 was applied to one surface of the second polyimide precursor layer so that the thickness after final curing was 3 μm, and then dried at 140 ° C. A polyamic acid precursor film laminated on was prepared. The laminate thus produced was completely cured by heat treatment for 9 minutes while raising the temperature from 150 ° C. to 385 ° C. in a nitrogen atmosphere. The physical properties of the laminate were evaluated and the results are shown in Table 2.

[Example 2]
In the same manner as in Example 1, a flexible metal-clad laminate was manufactured according to the layer structure shown in Table 2.

[Comparative Examples 1-3]
In the same manner as in Example 1, a flexible metal-clad laminate was manufactured according to the layer structure shown in Table 2.

Claims (8)

A flexible metal-clad laminate in which a metal layer is formed on one or both sides of an insulating layer composed of a plurality of polyimide resin layers, and the polyimide resin layer in contact with the metal layer has a storage elastic modulus at 300 ° C. 1 × 10 ⁸ Pa or more, and wherein the storage modulus at 350 ° C. or less 1 × 10 ⁸ Pa, flexible metal-clad laminate. The polyimide resin layer in contact with the metal layer has a storage elastic modulus at 300 ° C. of 1 × 10 ⁸ Pa to 1 × 10 ¹⁰ Pa and a storage elastic modulus at 350 ° C. of 1 × 10 ⁵ Pa to 1 × 10 10. The flexible metal-clad laminate according to claim 1, wherein the flexible metal-clad laminate is ⁸ Pa.   The plurality of polyimide resin layers are stacked in the order of thermoplastic polyimide resin layer / thermosetting polyimide resin layer / thermoplastic polyimide resin layer according to claim 1. Flexible metal-clad laminate.   The flexible metal-clad laminate according to claim 1, wherein the polyimide resin layer in contact with the metal layer is a thermoplastic polyimide resin layer having a glass transition temperature of 300 ° C or lower.   2. The flexible metal-clad laminate according to claim 1, wherein the polyimide resin layer in contact with the metal layer has a linear thermal expansion coefficient measured between 100 ° C. and 200 ° C. of 50 ppm / K or less.   The moisture absorption soldering resistance temperature after processing for 72 hours under the conditions of 40 ° C and 90% relative humidity is 300 ° C or higher, and the adhesive strength with the metal layer is 1.0 kgf / cm or higher. The flexible metal-clad laminate according to any one of 1 to 5. The flexible metal-clad laminate according to any one of claims 1 to 5, wherein the polyimide resin layer in contact with the metal layer includes 50 to 100 mol% of a structural unit represented by the following chemical formula 1. body.
[Chemical Formula 1]

-X- in Chemical Formula 1 is an aromatic diamino compound containing one or more selected from the following structures, which can be used alone or in a copolymerized form:

-X ₁ -represents -O-, -CO-, -S-, -SO _2- , -C (CH ₃ ) _2- , -CONH-, -C (CF ₃ ) ₂ -,-(CH ₂ ) -Or a combination of these,
Included in Chemical Formula 1

Is a dianhydride containing one or two or more selected from the following structures, and these can be used alone or copolymerized.

-X ₁ -is an aromatic diamino compound containing -O-,

Is a dianhydride containing one or more selected from the following structures, The flexible metal-clad laminate according to claim 7.