JP2022083294A - Polymer film and laminate - Google Patents

Abstract

A polymer film having excellent adhesion to other polymer films and metal foils, and a laminate using the polymer film are provided. A layer A and a layer B on at least one surface of the layer A, wherein at least one of the layer A and the layer B is a layer capable of being volume-expanded by an external stimulus, and the dielectric loss tangent is A polymer film of 0.005 or less, and a laminate using the polymer film. [Selection figure] None

Description

The present disclosure relates to polymer films and laminates.

In recent years, the frequencies used in communication equipment have tended to be very high. In order to suppress transmission loss in the high frequency band, it is required to reduce the relative permittivity and the dielectric loss tangent of the insulating material used for the circuit board.
Conventionally, polyimide has been widely used as an insulating material used for a circuit board, but a liquid crystal polymer having high heat resistance and low water absorption and having a small loss in a high frequency band has been attracting attention.

As a conventional polymer film, for example, in Patent Document 1, a liquid crystal polyester film containing at least liquid crystal polyester is oriented with a first degree of orientation in a first direction parallel to the main surface of the liquid crystal polyester film. When the degree is defined as the degree of orientation with respect to the second direction parallel to the main surface and orthogonal to the first direction, the first degree of orientation and the second orientation are defined as the degree. The liquid polyester having a first degree of orientation / second degree of orientation, which is a ratio to the degree, is 0.95 or more and 1.04 or less, and is measured by a wide-angle X-ray scattering method in a direction parallel to the main surface. A liquid crystal polyester film having a third degree of orientation of 60.0% or more is described.

Further, as a conventional releaseable laminated film, the one described in Patent Document 2 is known.
Patent Document 2 has a laminate containing an A layer containing a cellulose ester and a B layer containing a resin capable of forming a solution different from the above cellulose ester, and the adhesion between the A layer and the B layer is 5 N / cm or less. A peelable laminated film characterized by the above is described.

Japanese Unexamined Patent Publication No. 2020-264474 Japanese Unexamined Patent Publication No. 2013-46992

An object to be solved by one embodiment of the present invention is to provide a polymer film having excellent adhesion to other polymer films and metal foils.
Further, an object to be solved by another embodiment of the present invention is to provide a laminate having excellent interlayer adhesion using the polymer film.

The means for solving the above problems include the following aspects.
<1> A layer A and a layer B on at least one surface of the layer A, and at least one of the layer A and the layer B is a layer capable of volume expansion by an external stimulus and has a dielectric loss tangent of 0. Polymer film of .005 or less.
<2> The polymer film according to <1>, wherein the layer B is a layer that can expand in volume by the external stimulus.
<3> The polymer film according to <2>, wherein the expansion rate of the layer B at 160 ° C. is 0.1% or more.
<4> The polymer film according to <2> or <3>, wherein the expansion coefficient of the layer B at 300 ° C. is 0.1% or more.
<5> The polymer film according to any one of <2> to <4>, wherein the expansion coefficient of the layer B at 300 ° C. is larger than the expansion coefficient of the layer A at 300 ° C.
<6> The polymer film according to any one of <1> to <5>, wherein the coefficient of thermal expansion αs of the layer B is larger than the coefficient of thermal expansion αc of the layer A.
<7> The polymer film according to any one of <1> to <6>, wherein the layer B contains a foaming agent.
<8> The polymer film according to any one of <1> to <7>, wherein the polymer film contains a filler in any of the layers.
<9> The polymer film according to <8>, wherein the number density of the filler is larger inside than on the surface of the polymer film.
<10> The polymer film according to <8> or <9>, wherein the layer B contains a filler.
<11> The polymer film according to <10>, wherein the layer B contains a needle-shaped filler or a filler having protrusions.
<12> The polymer film according to any one of <1> to <11>, wherein the coefficient of linear expansion of the polymer film is −20 ppm / K to 50 ppm / K.
<13> The polymer film according to any one of <1> to <12>, wherein the polymer film has a dielectric loss tangent of 0.004 or less.
<14> The polymer film according to any one of <1> to <13>, wherein the polymer film contains a liquid crystal polymer in any of the layers.
<15> The polymer film according to <14>, wherein the liquid crystal polymer is a liquid crystal polymer having a structural repeating unit represented by any of the formulas (1) to (3).
Equation (1) -O-Ar ¹ -CO-
Equation (2) -CO-Ar ² -CO-
Equation (3) -X-Ar ³ -Y-
In the formulas (1) to (3), Ar ¹ represents a phenylene group, a naphthylene group or a biphenylylene group, and Ar ² and Ar ³ independently represent a phenylene group, a naphthylene group, a biphenylylene group or the following formula (4). X and Y each independently represent an oxygen atom or an imino group, and the hydrogen atoms in the above groups represented by Ar ¹ to Ar ³ independently represent a halogen atom and an alkyl group, respectively. Alternatively, it may be substituted with an aryl group.
Equation (4) -Ar ⁴ -Z-Ar ^5-
In formula (4), Ar ⁴ and Ar ⁵ independently represent a phenylene group or a naphthylene group, and Z represents an oxygen atom, a sulfur atom, a carbonyl group, a sulfonyl group or an alkylene group.
<16> The polymer film according to any one of <1> to <15>, which further has a layer C, and has the layer B, the layer A, and the layer C in this order.
<17> A laminate having the polymer film according to any one of <1> to <16> and a copper layer arranged on the surface of the polymer film on the layer B side.
<18> The laminate according to <17>, wherein the average thickness of the layer B is larger than the average thickness of the copper layer.
<19> The laminate according to <17> or <18>, wherein the peel strength between the layer B and the copper layer is 0.5 kN / m or more.
<20> The polymer film according to <16>, a copper layer arranged on the surface of the polymer film on the layer B side, and a copper layer arranged on the surface of the polymer film on the layer C side. Laminated body.
<21> The laminate according to <20>, wherein the peel strength between the layer C and the copper layer arranged on the surface on the layer C side is 0.5 kN / m or more.

According to one embodiment of the present invention, it is possible to provide a polymer film having excellent adhesion to other polymer films and metal foils.
Further, according to another embodiment of the present invention, it is possible to provide a laminate having excellent interlayer adhesion using the above polymer film.

The contents of the present disclosure will be described in detail below. The description of the constituents described below may be based on the representative embodiments of the present disclosure, but the present disclosure is not limited to such embodiments.
In addition, in this specification, "-" indicating a numerical range is used in the sense that the numerical values described before and after the numerical range are included as the lower limit value and the upper limit value.
In the numerical range described stepwise in the present disclosure, the upper limit value or the lower limit value described in one numerical range may be replaced with the upper limit value or the lower limit value of the numerical range described in another stepwise description. .. Further, in the numerical range described in the present disclosure, the upper limit value or the lower limit value of the numerical range may be replaced with the value shown in the examples.
Further, in the notation of a group (atomic group) in the present specification, the notation that does not describe substitution or non-substitution includes those having no substituent as well as those having a substituent. For example, the "alkyl group" includes not only an alkyl group having no substituent (unsubstituted alkyl group) but also an alkyl group having a substituent (substituted alkyl group).
As used herein, "(meth) acrylic" is a term used in a concept that includes both acrylic and methacrylic, and "(meth) acryloyl" is a term that is used as a concept that includes both acryloyl and methacrylic. Is.
In addition, the term "process" in the present specification is not limited to an independent process, and even if it cannot be clearly distinguished from other processes, the term "process" will be used as long as the intended purpose of the process is achieved. included. Further, in the present disclosure, "% by mass" and "% by weight" are synonymous, and "parts by mass" and "parts by weight" are synonymous.
Further, in the present disclosure, a combination of two or more preferred embodiments is a more preferred embodiment.
Further, unless otherwise specified, the weight average molecular weight (Mw) and the number average molecular weight (Mn) in the present disclosure are gel permeation chromatography using a column of TSKgel SuperHM-H (trade name manufactured by Toso Co., Ltd.). The molecular weight is detected by a solvent PFP (pentafluorophenol) / chloroform = 1/2 (mass ratio) by a GPC) analyzer and converted using polystyrene as a standard substance.

(Polymer film)
The polymer film according to the present disclosure has a layer A and a layer B on at least one surface of the layer A, and at least one of the layer A and the layer B is a layer capable of volume expansion by an external stimulus. , The dielectric loss tangent is 0.005 or less.

Since the conventional polymer film has a low content of polar groups, the adhesion to other polymer films and metal foils is not sufficient, and flexible wiring produced by laminating and patterning the polymer film and the metal foil and further laminating them. The present inventor has found that a portion of the substrate having poor interlayer adhesion is generated.
As a result of diligent studies by the present inventor, it has been found that a polymer film having excellent adhesion to a metal foil can be provided by adopting the above configuration.
The detailed mechanism by which the above effect is obtained is unknown, but it is presumed as follows.
A patterned metal leaf having a layer A and a layer B on at least one surface of the layer A, and at least one of the layer A and the layer B is a layer that can be expanded by volume by an external stimulus. In the local pressure drop (poor adhesion) portion that occurs when the laminated plate (a metal foil portion and another polymer film portion are present on the surface) is bonded, the volume-expandable layer is volume-expanded by the above-mentioned external stimulus. It is presumed that the pressure for adhesion can be further increased by volume expansion, and the adhesion to other polymer films and metal foils is excellent.

<< Dissipation factor >>
The polymer film according to the present disclosure has a dielectric loss tangent of 0.005 or less, preferably 0.004 or less, and more preferably 0.0035 or less, from the viewpoint of reducing transmission loss of the produced substrate. , 0 and 0.003 or less are particularly preferable.

The dielectric loss tangent of layer A in the polymer film according to the present disclosure is preferably 0.005 or less, more preferably 0.004 or less, and more preferably 0.0035, from the viewpoint of reducing the transmission loss of the produced substrate. It is more preferably less than or equal to, and particularly preferably more than 0 and 0.003 or less.

The dielectric positive contact of layer B in the polymer film according to the present disclosure is preferably 0.01 or less from the viewpoint of reducing transmission loss of the produced substrate and adhesion to other polymer films and metal foils. It is more preferably 0.005 or less, further preferably 0.004 or less, and particularly preferably more than 0 and 0.003 or less.

The dielectric loss tangent in the present disclosure shall be measured by the following method.
The permittivity measurement is carried out by the resonance perturbation method at a frequency of 10 GHz. A 10 GHz hollow resonator (CP531 manufactured by Kanto Denshi Applied Development Co., Ltd.) is connected to a network analyzer (“E8633B” manufactured by Agent Technology), and a polymer film or a sample of each layer (width: 2.0 mm × length) is connected to the cavity resonator. (S: 80 mm) is inserted, and the dielectric constant and dielectric adjacency of the polymer film or each layer are measured from the change in the resonance frequency before and after the insertion for 96 hours under a temperature of 25 ° C. and a humidity of 60% RH.

<< Expansion rate >>
The polymer film according to the present disclosure may be a layer in which at least one of the layer A and the layer B can be expanded in volume by an external stimulus, but from the viewpoint of adhesion to other polymer films and metal foils, the above-mentioned It is preferable that the layer B is a layer that can be expanded in volume by an external stimulus.

The expansion coefficient of the layer B at 160 ° C. is preferably 0.1% or more, preferably 1% or more, from the viewpoint of adhesion to other polymer films and metal foils and low-temperature adhesiveness. Is more preferable, 3% or more and 100% or less is more preferable, and 5% or more and 70% or less is particularly preferable.
The expansion coefficient of the layer B at 300 ° C. is preferably 0.1% or more, more preferably 3% or more, and 5% or more, from the viewpoint of adhesion to other polymer films and metal foils. It is more preferably 100% or less, and particularly preferably 10% or more and 70% or less.
Further, the expansion coefficient of the layer B at 160 ° C. is preferably larger than the expansion coefficient of the layer A at 160 ° C. from the viewpoint of adhesion to other polymer films and metal foils, and the expansion rate of the layer A and the layer B is preferably larger. The difference in expansion coefficient is preferably 0.1% or more, more preferably 1% or more, further preferably 3% or more and 100% or less, and particularly preferably 5% or more and 70% or less. preferable.
Further, the expansion coefficient of the layer B at 300 ° C. is preferably larger than the expansion coefficient of the layer A at 300 ° C. from the viewpoint of adhesion to other polymer films and metal foils, and the expansion rate of the layer A and the layer B is preferably larger. The difference in expansion coefficient is preferably 0.1% or more, more preferably 3% or more, further preferably 5% or more and 100% or less, and particularly preferably 10% or more and 70% or less. preferable.

The coefficient of expansion in the present disclosure shall be measured by the following method.
A section sample is prepared by cutting a polymer film with a microtome, and the thickness changes of layers A and B are determined using an optical microscope equipped with a heating stage system (HS82, manufactured by METTLER TOLEDO). The initial thickness (t25) at 25 ° C. and the thickness (t160) when the temperature was raised to 160 ° C. at a rate of 10 ° C./min were evaluated, and the value divided by the initial thickness (t160 / t25) was calculated. The coefficient of expansion at 160 ° C. (unit:%). The same applies to the case of 300 ° C.

<< Thermal expansion coefficient >>
In the polymer film according to the present disclosure, it is preferable that the coefficient of thermal expansion of the layer that can be volume-expanded by an external stimulus is larger than the coefficient of thermal expansion of a layer that is not a layer that can be volume-expanded by an external stimulus.
When the layer B is a layer that can be expanded by volume due to an external stimulus, the coefficient of thermal expansion αs of the layer B is larger than the coefficient of thermal expansion αc of the layer A from the viewpoint of adhesion to other polymer films and metal foils. Is preferable.

The coefficient of thermal expansion of the layer that can be expanded by volume by an external stimulus is preferably 50 ppm / K or more, and preferably 60 ppm / K to 300 ppm / K, from the viewpoint of adhesion to other polymer films and metal foils. More preferably, it is particularly preferably 70 ppm / K to 250 ppm / K.
When the layer B is a layer that can be expanded by volume due to an external stimulus, the coefficient of thermal expansion αs of the layer B is preferably 50 ppm / K or more from the viewpoint of adhesion to other polymer films and metal foils. , 60 ppm / K to 300 ppm / K, more preferably 70 ppm / K to 250 ppm / K.
When the layer A is not a layer that can be expanded by volume due to an external stimulus, the coefficient of thermal expansion αc of the layer A is not particularly limited, but is -20 ppm / K or more from the viewpoint of adhesion to other polymer films and metal foils. It is preferably 0 ppm / K or more, more preferably 30 ppm / K or more, and particularly preferably 50 ppm / K to 100 ppm / K.

The coefficient of thermal expansion of each layer in the present disclosure shall be measured by the following method.
A section sample is prepared by cutting a polymer film with a microtome and set in an optical microscope equipped with a heating stage system (HS82, manufactured by METTLER TOLEDO). Subsequently, the temperature was raised from 25 ° C. to 200 ° C. at a rate of 5 ° C./min, cooled to 30 ° C. at a rate of 20 ° C./min, and then heated again at a rate of 5 ° C./min to 30 ° C. The thickness of the layer B (ts30) and the thickness of the layer B at 150 ° C. (ts150) were evaluated, and the value obtained by dividing the dimensional change by the temperature change ((ts150-ts30) / (150-30)) was obtained. Calculated and used as the coefficient of thermal expansion (αs) of layer B. The coefficient of thermal expansion (αc) of the layer A is also obtained in the same manner.

<< Layer that can expand in volume by external stimulus >>
In the polymer film according to the present disclosure, at least one of layer A and layer B is a layer capable of volume expansion by an external stimulus.
The external stimulus is not particularly limited, and an external stimulus can be appropriately selected according to a known volume expansion method.
Specific examples of the external stimulus include heat, pressure, electric field, sound wave, electromagnetic wave (including light), and magnetic field.
Among them, at least one external stimulus selected from the group consisting of heat, pressure and electromagnetic waves is more suitable from the viewpoints of ease of laminating the fabrication, low dielectric loss tangent, and adhesion to other polymer films and metal foils. Preferably, at least one external stimulus selected from the group consisting of heat and pressure is more preferred, and heat is particularly preferred.

The layer that can be expanded by volume due to the external stimulus preferably contains a foaming agent from the viewpoint of handleability and storage stability of the polymer film.
For example, when the layer B is a layer that can be expanded by volume due to an external stimulus, it is preferable that the layer B contains a foaming agent.
The foaming agent is not particularly limited, and a known foaming agent can be used. It may be a physical foaming agent or a chemical foaming agent, but from the viewpoint of handleability and storage stability of the polymer film, it may be used. It is preferably a chemical foaming agent.
Further, the foaming agent is preferably a foaming agent that decomposes by heat from the viewpoint of low dielectric loss tangent and adhesion to the metal foil, and the decomposition temperature is appropriately selected according to the laminating temperature at the time of pasting and the like. However, the temperature is preferably 100 ° C to 300 ° C, more preferably 100 ° C to 160 ° C. Further, from the viewpoint of storage stability, the decomposition temperature is preferably 200 ° C to 300 ° C.
The chemical foaming agent may be an inorganic compound or an organic compound, and two or more kinds thereof may be used in combination.
Examples of the organic chemical foaming agent include nitrosamine compounds such as dinitrosopentamethylenetetramine (DPT), azo compounds such as azodicarbonamide (ADCA), 4,4'-oxybisbenzenesulfonyl hydrazide (OBSH) and hydrazodicarbonates. Examples thereof include hydrazine compounds such as amide (HDCA).
Examples of the inorganic chemical foaming agent include hydrogen carbonates such as sodium hydrogen carbonate, carbonates, and combinations of hydrogen carbonates and organic acid salts such as sodium citrate.
Among them, an inorganic chemical foaming agent is preferable, a combination of a hydrogen carbonate and an organic acid salt is more preferable, and hydrogen carbonate is preferable from the viewpoints of low dielectric adaptivity, adhesion to a metal foil, and handleability and storage stability of a polymer film. A combination of sodium and sodium citrate is particularly preferred.

The foaming agent may be used alone or in combination of two or more.
The content of the foaming agent in the layer that can be expanded by volume due to the external stimulus can be expanded by the external stimulus from the viewpoints of low dielectric normal contact, adhesion to the metal foil, and handleability and storage stability of the polymer film. It is preferably 0.01% by mass to 30% by mass, more preferably 0.05% by mass to 20% by mass, and 0.5% by mass to 15% by mass with respect to the total mass of the layer. Is particularly preferable.

The layer that can be expanded by volume due to the external stimulus preferably contains a liquid crystal polymer.
Further, the layer that can be expanded in volume by the above-mentioned external stimulus may contain other components.
As the liquid crystal polymer and other components in the layer that can expand in volume by the external stimulus, the liquid crystal polymers and other components described in layers A and B described later can be preferably used.
The preferred embodiment of the average thickness of the layer that can be expanded by volume by the external stimulus is the same as that of the layer A or the layer B described later.

Further, the layer that can be expanded by volume due to the external stimulus preferably contains a polymer having a coefficient of linear expansion larger than that of the liquid crystal polymer contained in the layer A, from the viewpoint of handleability and storage stability of the polymer film. By containing the polymer having a large coefficient of linear expansion, it is possible to form a layer that can be expanded by volume due to heat.
Preferred examples of the polymer having a large linear expansion coefficient include silicone rubber, silicone resin, polyethylene, cycloolefin-based polymers, and amorphous polyesters.

The polymer having a large coefficient of linear expansion may be used alone or in combination of two or more.
The content of the polymer having a large linear expansion coefficient in the layer that can be expanded by the external stimulus is the external stimulus from the viewpoints of low dielectric adjunct, adhesion to the metal foil, and handleability and storage stability of the polymer film. It is preferably 1% by mass to 90% by mass, more preferably 5% by mass to 80% by mass, and 10% by mass to 70% by mass with respect to the total mass of the layer that can be expanded by volume. It is more preferably 20% by mass to 60% by mass, and particularly preferably 20% by mass.

<Layer A>
The polymer film according to the present disclosure has a layer A and a layer B on at least one surface of the layer A, and from the viewpoint of low dielectric loss tangent, it is preferable that one of the layers contains a liquid crystal polymer, and the layer A is preferable. However, it is more preferable to contain a liquid crystal polymer, it is particularly preferable that the layer A and the layer B each contain a liquid crystal polymer, and it is most preferable that the layer A and the layer B contain the same type of liquid crystal polymer.
The layer A may be a layer that can be expanded in volume by an external stimulus, but is preferably not a layer that can be expanded in volume by an external stimulus from the viewpoint of the coefficient of thermal expansion and low dielectric loss tangent.

-Liquid crystal polymer-
In the present disclosure, the type of liquid crystal polymer is not particularly limited, and known liquid crystal polymers can be used.
Further, the liquid crystal polymer may be a thermotropic liquid crystal polymer that exhibits liquid crystal properties in a molten state, or may be a riotropic liquid crystal polymer that exhibits liquid crystal properties in a solution state. Further, in the case of a thermotropic liquid crystal, it is preferable that the liquid crystal is melted at a temperature of 450 ° C. or lower.
Examples of the liquid crystal polymer include liquid crystal polyester, liquid crystal polyester amide having an amide bond introduced into the liquid crystal polyester, liquid crystal polyester ether having an ether bond introduced into the liquid crystal polyester, and liquid crystal polyester carbonate having a carbonate bond introduced into the liquid crystal polyester. Can be mentioned.
Further, the liquid crystal polymer is preferably a polymer having an aromatic ring, and more preferably an aromatic polyester or an aromatic polyester amide, from the viewpoint of liquid crystal property and coefficient of thermal expansion.
Further, the liquid crystal polymer may be a polymer in which an imide bond, a carbodiimide bond, an isocyanate-derived bond such as an isocyanurate bond, or the like is further introduced into an aromatic polyester or an aromatic polyester amide.
Further, the liquid crystal polymer is preferably a total aromatic liquid crystal polymer using only an aromatic compound as a raw material monomer.

Examples of liquid crystal polymers include, for example:
1) (i) Aromatic hydroxycarboxylic acid, (ii) Aromatic dicarboxylic acid, and (iii) At least one compound selected from the group consisting of aromatic diols, aromatic hydroxyamines and aromatic diamines. It is made by polycondensing.
2) Polycondensation of multiple types of aromatic hydroxycarboxylic acids.
3) A compound obtained by polycondensing (i) an aromatic dicarboxylic acid and (ii) at least one compound selected from the group consisting of aromatic diols, aromatic hydroxyamines and aromatic diamines.
4) (i) Polyester such as polyethylene terephthalate and (ii) aromatic hydroxycarboxylic acid are polycondensed.
Here, the aromatic hydroxycarboxylic acid, the aromatic dicarboxylic acid, the aromatic diol, the aromatic hydroxyamine and the aromatic diamine are independently used in place of a part or all of them, and a polycondensable derivative thereof is used. May be good.

Examples of polymerizable derivatives of compounds having a carboxy group, such as aromatic hydroxycarboxylic acid and aromatic dicarboxylic acid, are those obtained by converting a carboxy group into an alkoxycarbonyl group or an aryloxycarbonyl group (ester), carboxy. Examples thereof include those obtained by converting a group into a haloformyl group (acid halide) and those obtained by converting a carboxy group into an acyloxycarbonyl group (acid anhydride).
Examples of polymerizable derivatives of compounds having a hydroxy group, such as aromatic hydroxycarboxylic acids, aromatic diols and aromatic hydroxyamines, are those obtained by acylating a hydroxy group and converting it into an acyloxy group (acylated product). Can be mentioned.
Examples of polymerizable derivatives of compounds having an amino group, such as aromatic hydroxyamines and aromatic diamines, include those obtained by acylating an amino group and converting it into an acylamino group (acylated product).

The liquid crystal polymer is a structural repeating unit represented by any of the following formulas (1) to (3) from the viewpoint of liquid crystal property, coefficient of thermal expansion, and adhesion to metal foil (hereinafter, formula (1)). It is preferable to have a repeating unit (1) or the like, and it is more preferable to have a structural repeating unit represented by the following formula (1). It is particularly preferable to have a structural repeating unit represented by 1), a structural repeating unit represented by the following formula (2), and a structural repeating unit represented by the following formula (2).
Equation (1) -O-Ar ¹ -CO-
Equation (2) -CO-Ar ² -CO-
Equation (3) -X-Ar ³ -Y-
In the formulas (1) to (3), Ar ¹ represents a phenylene group, a naphthylene group or a biphenylylene group, and Ar ² and Ar ³ independently represent a phenylene group, a naphthylene group, a biphenylylene group or the following formula (4). X and Y each independently represent an oxygen atom or an imino group, and the hydrogen atoms in the above groups represented by Ar ¹ to Ar ³ independently represent a halogen atom and an alkyl group, respectively. Alternatively, it may be substituted with an aryl group.
Equation (4) -Ar ⁴ -Z-Ar ^5-
In formula (4), Ar ⁴ and Ar ⁵ independently represent a phenylene group or a naphthylene group, and Z represents an oxygen atom, a sulfur atom, a carbonyl group, a sulfonyl group or an alkylene group.

Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom and an iodine atom.
Examples of the above alkyl groups include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, s-butyl group, t-butyl group, n-hexyl group and 2-ethylhexyl group. Examples thereof include an n-octyl group and an n-decyl group, the number of carbon atoms thereof is preferably 1 to 10.
Examples of the aryl group include a phenyl group, an o-tolyl group, an m-tolyl group, a p-tolyl group, a 1-naphthyl group and a 2-naphthyl group, and the number of carbon atoms thereof is preferably 6 to 20. be.
When the hydrogen atom is substituted with these groups, the number thereof is independently for each of the groups represented by Ar ¹ , Ar ² or Ar ³ , preferably 2 or less, and more preferably 1. It is an individual.

Examples of the alkylene group include a methylene group, a 1,1-ethanediyl group, a 1-methyl-1,1-ethanediyl group, a 1,1-butandyl group and a 2-ethyl-1,1-hexanediyl group. , The number of carbon atoms is preferably 1 to 10.

The repeating unit (1) is a constituent repeating unit derived from a predetermined aromatic hydroxycarboxylic acid.
As the repeating unit (1), Ar ¹ is a p-phenylene group (constituent repeating unit derived from p-hydroxyacousic acid) and Ar ¹ is a 2,6-naphthylene group (6-hydroxy). A structural repeating unit derived from -2-naphthoic acid) or a 4,4'-biphenylylene group (constituent repeating unit derived from 4'-hydroxy-4-biphenylcarboxylic acid) is preferable.

The repeating unit (2) is a constituent repeating unit derived from a predetermined aromatic dicarboxylic acid.
As the repeating unit (2), Ar ² is a p-phenylene group (a constituent repeating unit derived from terephthalic acid), Ar ² is an m-phenylene group (a constituent repeating unit derived from isophthalic acid), and the like. Ar ² is a 2,6-naphthylene group (a structural repeating unit derived from 2,6-naphthalenedicarboxylic acid), or Ar ² is a diphenyl ether-4,4'-diyl group (diphenyl ether-4, A structural repeating unit derived from 4'-dicarboxylic acid) is preferred.

The repeating unit (3) is a constituent repeating unit derived from a predetermined aromatic diol, aromatic hydroxylamine or aromatic diamine.
As the repeating unit (3), Ar ³ is a p-phenylene group (a constituent repeating unit derived from hydroquinone, p-aminophenol or p-phenylenediamine), and Ar ³ is an m-phenylene group (isophthale). Acid-derived structural repeating unit) or Ar ³ having a 4,4'-biphenylylene group (4,4'-dihydroxybiphenyl, 4-amino-4'-hydroxybiphenyl or 4,4'-diaminobiphenyl (Constituent repeating unit derived from) is preferable.

The content of the repeating unit (1) is the total amount of all the constituent repeating units (the amount equivalent to the amount of substance of each repeating unit by dividing the mass of each constituent repeating unit constituting the liquid crystal polymer by the formula amount of each repeating unit. (Mole) was determined, and the total value thereof) was preferably 30 mol% or more, more preferably 30 mol% to 80 mol%, further preferably 30 mol% to 60 mol%, and particularly preferably 30 mol. % -40 mol%.
The content of the repeating unit (2) is preferably 35 mol% or less, more preferably 10 mol% to 35 mol%, still more preferably 20 mol% to 35 mol%, based on the total amount of all the constituent repeating units. Particularly preferably, it is 30 mol% to 35 mol%.
The content of the repeating unit (3) is preferably 35 mol% or less, more preferably 10 mol% to 35 mol%, still more preferably 20 mol% to 35 mol%, based on the total amount of all the constituent repeating units. Particularly preferably, it is 30 mol% to 35 mol%.
The larger the content of the repeating unit (1), the easier it is to improve the heat resistance, strength and rigidity, but if it is too large, the solubility in the solvent tends to be low.

The ratio between the content of the repeating unit (2) and the content of the repeating unit (3) is expressed as [content of repeating unit (2)] / [content of repeating unit (3)] (mol / mol). It is preferably 0.9 / 1 to 1 / 0.9, more preferably 0.95 / 1 to 1 / 0.95, and further preferably 0.98 / 1 to 1 / 0.98.

The liquid crystal polymer may have two or more types of repeating units (1) to (3) independently. Further, the liquid crystal polymer may have a constituent repeating unit other than the repeating units (1) to (3), but the content thereof is preferably 10 mol% or less with respect to the total amount of all the repeating units. More preferably, it is 5 mol% or less.

The liquid crystal polymer has a repeating unit (3) in which at least one of X and Y is an imino group, that is, a structural repeating unit derived from a predetermined aromatic hydroxylamine and a structural repeating unit derived from an aromatic diamine. Having at least one of the units is preferable because the solubility in a solvent is excellent, and it is more preferable to have only one having at least one of X and Y as an imino group as the repeating unit (3).

The liquid crystal polymer is preferably produced by melt-polymerizing the raw material monomer corresponding to the constituent repeating unit constituting the liquid crystal polymer. The melt polymerization may be carried out in the presence of a catalyst, and examples of this catalyst include metal compounds such as magnesium acetate, stannous acetate, tetrabutyl titanate, lead acetate, sodium acetate, potassium acetate and antimony trioxide. Examples thereof include nitrogen-containing heterocyclic compounds such as 4- (dimethylamino) pyridine and 1-methylimidazole, and nitrogen-containing heterocyclic compounds are preferably used. The melt polymerization may be further solid-phase polymerized, if necessary.

The flow start temperature of the liquid crystal polymer is preferably 250 ° C. or higher, more preferably 250 ° C. or higher and 350 ° C. or lower, and further preferably 260 ° C. or higher and 330 ° C. or lower. When the flow start temperature of the liquid crystal polymer is within the above range, the solubility, heat resistance, strength and rigidity are excellent, and the viscosity of the solution is appropriate.

The flow start temperature, also called the flow temperature or the flow temperature, melts the liquid crystal polymer using a capillary leometer while raising the temperature at a rate of 4 ° C./min under a load of 9.8 MPa (100 kg / cm ² ). It is a temperature that shows a viscosity of 4,800 Pa · s (48,000 poise) when extruded from a nozzle with an inner diameter of 1 mm and a length of 10 mm, and is a guideline for the molecular weight of the liquid crystal polymer (edited by Naoyuki Koide). , "Liquid Liquid Polymer-Synthesis / Molding / Application-", CMC Co., Ltd., June 5, 1987, p.95).

The weight average molecular weight of the liquid crystal polymer is preferably 1,000,000 or less, more preferably 3,000 to 300,000, still more preferably 5,000 to 100,000. , 5,000 to 30,000 are particularly preferable. When the weight average molecular weight of this liquid crystal polymer is in the above range, the film after heat treatment is excellent in thermal conductivity, heat resistance, strength and rigidity in the thickness direction.

The liquid crystal polymer is preferably a liquid crystal polymer that is soluble in a specific organic solvent (hereinafter, also referred to as "soluble liquid crystal polymer").
Specifically, the soluble liquid crystal polymer in the present disclosure is N-methylpyrrolidone, N-ethylpyrrolidone, dichloromethane, dichloroethane, chloroform, N, N-dimethylacetamide, γ-butyrolactone, dimethylformamide, ethylene glycol mono at 25 ° C. It is a liquid crystal polymer that dissolves 0.1 g or more in 100 g of at least one solvent selected from the group consisting of butyl ether and ethylene glycol monoethyl ether.

The layer A may contain only one type of liquid crystal polymer, or may contain two or more types of liquid crystal polymer.
The content of the liquid crystal polymer in the layer A is preferably 20% by volume to 100% by volume, preferably 20% by volume, based on the total volume of the layer A from the viewpoint of the coefficient of thermal expansion and the adhesion to the metal foil. It is more preferably ~ 100% by volume, further preferably 30% by volume to 100% by volume, and particularly preferably 40% by volume to 100% by volume.

-Filler-
From the viewpoint of the coefficient of thermal expansion and the adhesion to other polymer films and metal foils, the polymer film preferably contains a filler in at least one of the layers, and more preferably the layer A contains the filler.
The filler may be in the form of particles or fibers, and may be an inorganic filler or an organic filler.
In the polymer film according to the present disclosure, it is preferable that the number density of the filler is larger inside than on the surface from the viewpoint of suppressing distortion of the metal wiring when it is adhered to the metal wiring.

As the inorganic filler, a known inorganic filler can be used.
Examples of the material of the inorganic filler include BN, Al ₂ O ₃ , Al N, TiO ₂ , SiO ₂ , barium titanate, strontium titanate, aluminum hydroxide, calcium carbonate, and a material containing two or more of these. Be done.
Among them, as the inorganic filler, metal oxide particles or fibers are preferable, silica particles, titania particles, or glass fibers are more preferable, and silica particles are preferable from the viewpoint of thermal expansion coefficient and adhesion to a metal foil. , Or glass fiber is particularly preferred.
The average particle size of the inorganic filler is preferably 5 nm to 20 μm, more preferably 10 nm to 10 μm, and more preferably 20 nm to 1 μm from the viewpoint of the coefficient of thermal expansion and the adhesion to the metal foil. It is more preferably 25 nm to 500 nm, and particularly preferably 25 nm to 500 nm. When the particle or fiber is flat, it indicates the length in the short side direction.

As the organic filler, a known organic filler can be used.
Examples of the material of the organic filler include polyethylene, polystyrene, urea-formalin filler, polyester, cellulose, acrylic resin, fluororesin, cured epoxy resin, crosslinked benzoguanamine resin, crosslinked acrylic resin, and a material containing two or more of these. Can be mentioned.
Further, the organic filler may be in the form of fibers such as nanofibers, or may be hollow resin particles.
Among them, the organic filler is preferably fluororesin particles, polyester-based resin particles, or cellulose-based resin nanofibers from the viewpoint of thermal expansion coefficient and adhesion to the metal foil, and is preferably polytetrafluoro. More preferably, it is an ethylene particle.
The average particle size of the organic filler is preferably 5 nm to 20 μm, more preferably 10 nm to 1 μm, and more preferably 20 nm to 500 nm from the viewpoint of the coefficient of thermal expansion and the adhesion to the metal foil. It is more preferably 25 nm to 90 nm, and particularly preferably 25 nm to 90 nm.

The layer A may contain only one type of filler or may contain two or more types of filler.
The content of the filler in the layer A is preferably 5% by volume to 80% by volume, preferably 10% by volume or more, based on the total volume of the layer A, from the viewpoint of the coefficient of thermal expansion and the adhesion to the metal foil. It is more preferably 70% by volume, further preferably 20% by volume to 70% by volume, and particularly preferably 30% by volume to 60% by volume.

-Other additives-
Layer A may contain other additives other than the liquid crystal polymer and the filler.
As other additives, known additives can be used. Specific examples thereof include leveling agents, antifoaming agents, antioxidants, ultraviolet absorbers, flame retardants, colorants and the like.

Further, the layer A may contain a resin other than the above-mentioned components as another additive.
Examples of resins other than liquid crystal polymers include polyolefins, cycloolefin polymers, polyamides, polyesters, polyphenylene sulfides, polyether ketones, polycarbonates, polyether sulfones, polyphenylene ethers and their modifications, polyetherimides, silicone resins, and fluororesins. Thermoplastic resins such as; elastomers such as copolymers of glycidyl methacrylate and polyethylene; thermosetting resins such as phenolic resins, epoxy resins, polyimide resins, cyanate resins and the like.

The total content of the other additives in the layer A is preferably 25 parts by mass or less, more preferably 10 parts by mass or less, still more preferably 5 parts by mass, based on 100 parts by mass of the liquid crystal polymer. It is as follows.

The average thickness of the layer A is not particularly limited, but is preferably 5 μm to 90 μm, more preferably 10 μm to 70 μm, and more preferably 15 μm to 15 μm from the viewpoint of the coefficient of thermal expansion and the adhesion to the metal foil. It is particularly preferably 50 μm.

The method for measuring the average thickness of each layer in the polymer film according to the present disclosure is as follows.
The polymer film is cut with a microtome and the cross section is observed with an optical microscope to evaluate the thickness of each layer. The cross-section sample is cut out at three or more places, the thickness is measured at three or more points in each cross-section, and the average value thereof is taken as the average thickness.
The polymer film is cut at a plane perpendicular to the plane direction of the polymer film, and the thickness is measured at 5 points or more in the cross section, and the average value thereof is taken as the average thickness.

<Layer B>
The polymer film according to the present disclosure has a layer A and a layer B on at least one surface of the layer A.
Further, the layer B is preferably a surface layer (outermost layer).
Further, the layer B is preferably a layer that can be expanded in volume by an external stimulus from the viewpoint of adhesion to the metal foil.

The layer B preferably contains a liquid crystal polymer from the viewpoint of the coefficient of thermal expansion and the adhesion to the metal foil.
The preferred embodiment of the liquid crystal polymer used for the layer B is the same as the preferred embodiment of the liquid crystal polymer used for the layer A, except as described later.
The liquid crystal polymer contained in the layer B may be the same as or different from the liquid crystal polymer contained in the layer A, but is preferably the same as the liquid crystal polymer contained in the layer A.

The content of the liquid crystal polymer in the layer B is preferably smaller than the content of the liquid crystal polymer in the layer A from the viewpoint of the coefficient of thermal expansion and the adhesion to the metal foil.
Further, the content of the liquid crystal polymer in the layer B is preferably 10% by mass to 99.99% by mass with respect to the total mass of the layer B from the viewpoint of the thermal expansion coefficient and the adhesion to the metal foil. , 20% by mass to 99.9% by mass, more preferably 30% by mass to 95% by mass, and particularly preferably 30% by mass to 90% by mass.

The layer B preferably contains a filler, and more preferably contains a needle-shaped filler or a filler having protrusions, from the viewpoint of adhesion to the metal foil.
The preferred embodiment of the filler used for the layer B is the same as the preferred embodiment of the filler used for the layer A, except as described later.
As the needle-shaped filler, an inorganic needle-shaped filler is preferable, and an inorganic oxide needle-shaped filler is more preferable.
The aspect ratio of the needle-shaped filler is preferably 3 or more, more preferably 5 or more, and particularly preferably 5 or more and 100 or less.
As the filler having protrusions, an inorganic filler having protrusions is preferable, and an inorganic oxide filler having protrusions is more preferable.
Further, as the filler having protrusions, a star-shaped rock candy (Japanese confection having horned protrusions on the surface of a spherical shape) -like filler is more preferable. As the konpeito-like filler, for example, the konpeito-like silica sol described in Japanese Patent Application Laid-Open No. 2008-169102 is preferably used.
The average particle size of the needle-shaped filler and the filler having protrusions is preferably 5 nm to 20 μm, more preferably 10 nm to 1 μm, and more preferably 20 nm to 500 nm from the viewpoint of adhesion to the metal foil. It is more preferably 25 nm to 90 nm, and particularly preferably 25 nm to 90 nm.

When the layer A contains a filler, the content of the filler in the layer B is preferably smaller than the content of the filler in the layer A from the viewpoint of the coefficient of thermal expansion and the adhesion to the metal foil.
When the layer B contains a filler, the content of the filler in the layer B is 1% by mass to 70% by mass with respect to the total mass of the layer B from the viewpoint of the thermal expansion coefficient and the adhesion to the metal foil. It is preferably 5% by mass to 60% by mass, more preferably 10% by mass to 55% by mass, and particularly preferably 10% by mass to 55% by mass.

Layer B may contain other additives other than liquid crystal polymers, foaming agents and fillers.
Preferred embodiments of the other additives used in the layer B are the same as in the preferred embodiments of the other additives used in the layer A, except as described later.

The average thickness of the layer B is preferably thinner than the average thickness of the layer A from the viewpoint of the coefficient of thermal expansion and the adhesion to the metal foil.
The value of ^TA / ^TB , which is the ratio of the average thickness TA of the layer ^A to the average thickness TB of the layer ^B , may be larger than 1 from the viewpoint of the coefficient of thermal expansion and the adhesion to the metal foil. It is preferably 1.5 to 100, more preferably 2 to 10, and particularly preferably 2 to 5.
The average thickness of the layer B is preferably 3 μm to 40 μm, more preferably 5 μm to 30 μm, and 8 μm to 20 μm from the viewpoint of the coefficient of thermal expansion and the adhesion to the metal foil. Is more preferable, and 10 μm to 15 μm is particularly preferable.
When the layer B is a layer that can be expanded in volume by an external stimulus, the average thickness of the layer B is preferably thicker than the average thickness of the copper layer (copper wiring) in the laminate described later.

<Layer C>
The polymer film according to the present disclosure preferably further has a layer C, and more preferably has the layer B, the layer A, and the layer C in this order.
Further, the layer C is preferably a surface layer (outermost layer).
Further, the layer C may be a layer that can be expanded in volume by an external stimulus.
The layer C preferably contains a liquid crystal polymer from the viewpoint of the coefficient of thermal expansion and the adhesion to the metal foil.
The preferred embodiment of the liquid crystal polymer used for the layer C is the same as the preferred embodiment of the liquid crystal polymer used for the layer A, except as described later.
The liquid crystal polymer contained in the layer C may be the same as or different from the liquid crystal polymer contained in the layer A or the layer B, but may be the same as the liquid crystal polymer contained in the layer A and the layer B. It is preferable to have.

The content of the liquid crystal polymer in the layer C is preferably smaller than the content of the liquid crystal polymer in the layer A from the viewpoint of the coefficient of thermal expansion and the adhesion to the metal foil.
Further, the content of the liquid crystal polymer in the layer C is preferably 10% by mass to 99.99% by mass with respect to the total mass of the layer C from the viewpoint of the thermal expansion coefficient and the adhesion to the metal foil. , 20% by mass to 99.9% by mass, more preferably 30% by mass to 95% by mass, and particularly preferably 30% by mass to 90% by mass.

The layer C may contain a filler.
The preferred embodiment of the filler used for the layer C is the same as the preferred embodiment of the filler used for the layer B, except as described later.

Layer C may contain other additives other than the liquid crystal polymer and the filler.
Preferred embodiments of the other additives used in layer C are similar to preferred embodiments of the other additives used in layer A.

The average thickness of the layer C is preferably thinner than the average thickness of the layer A from the viewpoint of the coefficient of thermal expansion and the adhesion to the metal foil.
The value of ^TA / ^TC , which is the ratio of the average thickness TA of the layer ^A to the average thickness TC of the layer ^C , may be larger than 1 from the viewpoint of the coefficient of thermal expansion and the adhesion to the metal foil. It is preferably 1.5 to 100, more preferably 2 to 10, and particularly preferably 2 to 5.
The value of ^TC / ^TB , which is the ratio of the average thickness TC of the layer ^C to the average thickness TB of the layer ^B , is 0.2 from the viewpoint of the coefficient of thermal expansion and the adhesion to the metal foil. It is preferably from 5 to 5, more preferably 0.5 to 2, and particularly preferably 0.8 to 1.2.
Further, the average thickness of the layer C is preferably 3 μm to 40 μm, more preferably 5 μm to 30 μm, and 8 μm to 20 μm from the viewpoint of the coefficient of thermal expansion and the adhesion to the metal foil. Is more preferable, and 10 μm to 15 μm is particularly preferable.
Further, when the layer C is a layer that can be expanded in volume by an external stimulus, the average thickness of the layer C may be thicker than the average thickness of the copper layer (copper wiring) arranged on the C layer side in the laminate described later. preferable.

The average thickness of the polymer film according to the present disclosure is preferably 6 μm to 200 μm, more preferably 12 μm to 100 μm, and more preferably 20 μm to 20 μm from the viewpoint of strength, coefficient of thermal expansion, and adhesion to the metal foil. It is particularly preferably 60 μm.

The average thickness of the polymer film is measured at any five points using an adhesive film thickness meter, for example, an electronic micrometer (product name "KG3001A", manufactured by Anritsu Co., Ltd.), and is used as the average value thereof.

The coefficient of linear expansion of the polymer film according to the present disclosure is preferably -20 ppm / K to 50 ppm / K, more preferably -10 ppm / K to 40 ppm / K, and 0 ppm / K from the viewpoint of the coefficient of thermal expansion. It is more preferably K to 35 ppm / K, and particularly preferably 10 ppm / K to 30 ppm / K.

The method for measuring the coefficient of linear expansion in the present disclosure shall be as follows.
Using a thermomechanical analyzer (TMA), a polymer film with a width of 5 mm and a length of 20 mm or a tensile load of 1 g is applied to both ends of each layer, and the temperature is raised to 25 ° C to 200 ° C at a rate of 5 ° C / min. The linear expansion coefficient is calculated from the slope of the TMA curve between 30 ° C. and 150 ° C. when the temperature is cooled to 30 ° C. at a rate of 20 ° C./min and then raised again at a rate of 5 ° C./min.

<Manufacturing method of polymer film>
[Film formation]
The method for producing the polymer film according to the present disclosure is not particularly limited, and known methods can be referred to.
As a method for producing a polymer film according to the present disclosure, for example, a co-flow spreading method, a multi-layer coating method, a co-extrusion method and the like are preferably mentioned. Of these, the coextrusion method is particularly preferable for relatively thin film formation, and the coextrusion method is particularly preferable for thick film formation.
When manufactured by the co-flow spreading method and the multi-layer coating method, as a layer A forming composition, a layer B forming composition, a layer C forming composition, etc. in which the components of each layer such as a liquid crystal polymer are dissolved or dispersed in a solvent, respectively. , It is preferable to carry out a co-flow spreading method or a multi-layer coating method.

Examples of the solvent include halogenated hydrocarbons such as dichloromethane, chloroform, 1,1-dichloroethane, 1,2-dichloroethane, 1,1,2,2-tetrachloroethane, 1-chlorobutane, chlorobenzene and o-dichlorobenzene; Halogenized phenols such as p-chlorophenol, pentachlorophenol and pentafluorophenol; ethers such as diethyl ether, tetrahydrofuran and 1,4-dioxane; ketones such as acetone and cyclohexanone; esters such as ethyl acetate and γ-butyrolactone; ethylene Phenols such as carbonates and propylene carbonates; amines such as triethylamine; nitrogen-containing heterocyclic aromatic compounds such as pyridine; nitriles such as acetonitrile and succinonitrile; N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl Examples include amides such as pyrrolidone, urea compounds such as tetramethylurea; nitro compounds such as nitromethane and nitrobenzene; sulfur compounds such as dimethylsulfoxide and sulfolane; and phosphorus compounds such as hexamethylphosphate amide and tri-n-butylphosphate. Two or more of them may be used.

As the solvent, an aprotonic compound, particularly a solvent containing an aprotonic compound having no halogen atom as a main component is preferable because it is low in corrosiveness and easy to handle, and the ratio of the aprotonic compound to the whole solvent is It is preferably 50% by mass to 100% by mass, more preferably 70% by mass to 100% by mass, and particularly preferably 90% by mass to 100% by mass. Further, as the aprotonic compound, since it is easy to dissolve a liquid crystal polymer, an amide such as N, N-dimethylformamide, N, N-dimethylacetamide, tetramethylurea, N-methylpyrrolidone or γ-butyrolactone may be used. Esters are preferred, with N, N-dimethylformamide, N, N-dimethylacetamide, and N-methylpyrrolidone being more preferred.

Further, as the solvent, a solvent containing a compound having a dipole moment of 3 to 5 as a main component is preferable because the liquid crystal polymer is easily dissolved, and the ratio of the compound having a dipole moment of 3 to 5 in the whole solvent is preferable. Is preferably 50% by mass to 100% by mass, more preferably 70% by mass to 100% by mass, and particularly preferably 90% by mass to 100% by mass.
As the aprotic compound, it is preferable to use a compound having a dipole moment of 3 to 5.

Further, as the solvent, since it is easy to remove, a solvent containing a compound having a boiling point of 220 ° C. or lower at 1 atm as a main component is preferable, and the ratio of the compound having a boiling point of 220 ° C. or less at 1 atm to the whole solvent is preferable. Is preferably 50% by mass to 100% by mass, more preferably 70% by mass to 100% by mass, and particularly preferably 90% by mass to 100% by mass.
As the aprotic compound, it is preferable to use a compound having a boiling point of 220 ° C. or lower at 1 atm.

Further, as the method for producing a polymer film according to the present disclosure, a support may be used when the polymer film is produced by the above-mentioned co-flow spreading method, multi-layer coating method, co-extrusion method or the like. Further, when the metal layer (metal foil) or the like used for the laminate described later is used as a support, it may be used as it is without peeling.
Examples of the support include a metal drum, a metal band, a glass plate, a resin film or a metal foil. Of these, metal drums, metal bands, and resin films are preferable.
Examples of the resin film include a polyimide (PI) film, and examples of commercially available products include U-Pylex S and U-Pylex R manufactured by Ube Kosan Co., Ltd., Kapton manufactured by Toray DuPont Co., Ltd., and Examples thereof include IF30, IF70 and LV300 manufactured by SKC Koron PI.
Further, the support may have a surface treatment layer formed on the surface thereof so that the support can be easily peeled off. For the surface treatment layer, hard chrome plating, fluororesin or the like can be used.
The average thickness of the resin film support is not particularly limited, but is preferably 25 μm or more and 75 μm or less, and more preferably 50 μm or more and 75 μm or less.

Further, the method for removing at least a part of the solvent from the cast or coated film-like composition (cast film or coating film) is not particularly limited, and a known drying method can be used. ..

[Stretching]
The liquid crystal polymer film according to the present disclosure can be appropriately combined with stretching from the viewpoint of controlling the molecular orientation and adjusting the coefficient of linear expansion and the mechanical characteristics. The stretching method is not particularly limited, and a known method can be referred to, and the stretching method may be carried out in a solvent-containing state or in a dry film state. Stretching in a solvent-containing state may be carried out by gripping the film and stretching it, or by utilizing the self-shrinking force of the web due to drying without stretching, or a combination thereof. Stretching is particularly effective for the purpose of improving the elongation at break and the strength at break when the brittleness of the film is reduced by the addition of an inorganic filler or the like.

<Use>
The polymer film according to the present disclosure can be used for various purposes, and above all, it can be suitably used for a film for electronic parts such as a printed wiring board, and can be preferably used for a flexible printed circuit board.
Further, the polymer film according to the present disclosure can be suitably used as a polymer film for metal adhesion.

(Laminated body)
The laminate according to the present disclosure may be a laminate of the polymer films according to the present disclosure, but the polymer film according to the present disclosure and the metal layer arranged on the surface on the layer B side of the polymer film are used. It is preferable to have the metal layer, and it is more preferable that the metal layer is a copper layer.
Further, the laminate according to the present disclosure includes a polymer film according to the present disclosure having a layer B, a layer A, and a layer C in this order, and a metal layer arranged on the surface of the polymer film on the layer B side. It is preferable to have a metal layer arranged on the surface of the polymer film on the layer C side, and it is more preferable that all of the metal layers are copper layers.
Further, the average thickness of the layer B is preferably larger than the average thickness of the metal layer (preferably a copper layer) from the viewpoint of adhesion to the metal foil.
Further, the average thickness of the layer C is preferably larger than the average thickness of the metal layer (preferably a copper layer) arranged on the surface on the layer C side from the viewpoint of adhesion to the metal foil.
Further, the metal layer arranged on the surface on the layer B side and the metal layer arranged on the surface on the layer C side are different materials and thicknesses even if they are metal layers having the same material, thickness and shape. And may be a metal layer of shape. From the viewpoint of adjusting the characteristic impedance, the metal layer arranged on the surface on the layer B side and the metal layer arranged on the surface on the layer C side may be metal layers having different materials and thicknesses. A metal layer may be laminated on only one side of the layer B or the layer C.
Further, from the viewpoint of adjusting the characteristic impedance, there is also an embodiment in which a metal layer is laminated on one side of the layer B or C, and another polymer film (preferably another liquid crystal polymer film) is laminated on the other side. Preferred.

The peel strength between the layer B and the copper layer is preferably 0.5 kN / m or more, more preferably 0.7 kN / m or more, and 0.7 kN / m to 2.0 kN / m. It is more preferably 0.9 kN / m to 1.5 kN / m, and particularly preferably 0.9 kN / m to 1.5 kN / m.
The peel strength between the layer C and the copper layer is preferably 0.5 kN / m or more, more preferably 0.7 kN / m or more, and 0.7 kN / m to 2.0 kN /. It is more preferably m, and particularly preferably 0.9 kN / m to 1.5 kN / m.

In the present disclosure, the peel strength between the layer B or C of the polymer film and the metal layer (for example, the copper layer) shall be measured by the following method.
A 1.0 cm wide peeling test piece was prepared from the laminate of the polymer film and the metal layer, the polymer film was fixed to a flat plate with double-sided adhesive tape, and 50 mm by the 180 ° method according to JIS C 5016 (1994). The strength (kN / m) when the metal layer is peeled from the polymer film at a rate of / minute is measured.

The metal layer is preferably a copper layer. As the copper layer, a rolled copper foil formed by a rolling method or an electrolytic copper foil formed by an electrolytic method is preferable, and a rolled copper foil is more preferable from the viewpoint of bending resistance.

The average thickness of the metal layer, preferably the copper layer, is not particularly limited, but is preferably 2 μm to 20 μm, more preferably 3 μm to 18 μm, and even more preferably 5 μm to 12 μm. The copper foil may be a copper foil with a carrier formed on a support (carrier) so as to be peelable. As the carrier, a known carrier can be used. The average thickness of the carrier is not particularly limited, but is preferably 10 μm to 100 μm, and more preferably 18 μm to 50 μm.

The metal layer in the laminate according to the present disclosure may be a metal layer having a circuit pattern.
Further, it is also preferable that the metal layer in the laminate according to the present disclosure is processed into a desired circuit pattern by etching, for example, to obtain a flexible printed circuit board. The etching method is not particularly limited, and a known etching method can be used.

The present disclosure will be described in more detail with reference to examples below. The materials, amounts used, ratios, treatment contents, treatment procedures, etc. shown in the following examples may be appropriately changed as long as they do not deviate from the gist of the present disclosure. Therefore, the scope of the present disclosure is not limited to the specific examples shown below.

<< Measurement method >>
[Expansion rate]
A section sample was prepared by cutting a polymer film with a microtome, and the thickness changes of layers A and B were determined using an optical microscope equipped with a heating stage system (HS82, manufactured by METTLER TOLEDO). The initial thickness (t25) at 25 ° C. and the thickness (t160) when the temperature was raised to 160 ° C. at a rate of 10 ° C./min were evaluated, and the value divided by the initial thickness (t160 / t25) was calculated. The expansion rate at 160 ° C. (unit:%) was used. It was obtained in the same manner in the case of 300 ° C.

[Coefficient of thermal expansion]
The film was cut with a microtome to prepare a section sample and set in an optical microscope equipped with a heating stage system (HS82, METTLER TOLEDO). Subsequently, the temperature was raised from 25 ° C. to 200 ° C. at a rate of 5 ° C./min, cooled to 30 ° C. at a rate of 20 ° C./min, and then heated again at a rate of 5 ° C./min to 30 ° C. The thickness of the layer B (ts30) and the thickness of the layer B at 150 ° C. (ts150) were evaluated, and the value obtained by dividing the dimensional change by the temperature change ((ts150-ts30) / (150-30)) was obtained. It was calculated and used as the coefficient of thermal expansion (αs) of layer B. The same applies to layer A.

[Dissipation factor]
The measurement of the dielectric constant was carried out by the resonance perturbation method at a frequency of 10 GHz. A 10 GHz hollow resonator (CP531 manufactured by Kanto Denshi Applied Development Co., Ltd.) is connected to a network analyzer (“E8363B” manufactured by Agent Technology), and a polymer film sample (width: 2.0 mm × length:: 80 mm) was inserted, and the dielectric constant and the dielectric tangent of the polymer film sample were measured from the change in the resonance frequency before and after the insertion for 96 hours under the environment of temperature 25 ° C. and humidity 60% RH.

[Peeling strength]
A 1.0 cm wide peeling test piece was prepared from the flexible wiring board described later, the double-sided copper-clad laminate side was fixed to a flat plate with double-sided adhesive tape, and one side was measured by the 180 ° method according to JIS C 5016 (1994). The strength (kN / m) when the copper-clad laminate side was peeled off at a rate of 50 mm / min was measured.

<< Manufacturing example >>
<Liquid crystal polymer>
LC-A: A liquid crystal polymer having a melting point of 315 ° C. obtained by adjusting heat treatment conditions with reference to the production example of the liquid crystal polyester (B) of International Publication No. 2020/166644.

<Additives>
A-1: A foaming agent consisting of the following mixture. A-1 was added so as to have the mass ratio shown in Table 1.
-Sodium hydrogen carbonate: 5 parts by mass-Sodium citrate: 5 parts by mass-Tark: 1 part by mass

A-2: A foaming agent consisting of the following mixture. A-2 was added so as to have the mass ratio shown in Table 1.
-Sodium hydrogen carbonate: 5 parts by mass-Sodium citrate: 5 parts by mass-Tark: 1 part by mass-Kinpira sugar-like silica sol prepared according to the following production method (average particle size 35.8 nm): 989 parts by mass

B-1: Commercially available silicone rubber powder with an average particle size of 5 μm (KMP-597, manufactured by Shin-Etsu Chemical Co., Ltd.)

B-2: Additive consisting of the following mixture. B-2 was added so as to have the mass ratio shown in Table 1.
-Commercially available silicone rubber powder with an average particle size of 5 μm (KMP-597, manufactured by Shin-Etsu Chemical Co., Ltd.): 40 parts by mass.

-How to make konpeito-like silica sol-
Silica sol (manufactured by Catalyst Kasei Kogyo Co., Ltd .: Cataloid SI-40, average particle diameter 21.2 nm, SiO ₂ concentration 40.7% by mass) Add water to 102.4 g, and add 4,170 g (SiO ₂ concentration 1% by mass). ), Further, a sodium hydroxide aqueous solution having a concentration of 5% by mass was added so that the pH of the silica sol became 11. Next, the temperature of the silica sol was raised to 80 ° C. and maintained at 80 ° C. for 30 minutes to prepare a nuclear particle dispersion liquid (solution A).

575 g of water glass (manufactured by AGC SI Tech Co., Ltd .: JIS No. 3 water glass, SiO ₂ concentration 24% by mass) was diluted with 2,185 g of water to prepare 2,760 g of an alkaline silicate aqueous solution (solution B). Further, 2352 g of water was added to 98.0 g of ammonium sulfate (manufactured by Mitsubishi Chemical Corporation) as an electrolyte to prepare 2,450 g of an aqueous electrolyte solution. Then, the alkaline aqueous solution of silicate (solution B) and the aqueous electrolyte solution are added to the total amount of the nuclear particle dispersion liquid (solution A) at 80 ° C. over 1 hour at 80 ° C., respectively. Particle growth was carried out by.
Then, after aging at 80 ° C. for 1 hour, the particles were washed with an ultrafiltration membrane until the pH of the grown nuclear particle dispersion became 10.8. Then, it was concentrated to obtain a konpeito-like silica sol having a SiO ₂ concentration of 20% by mass.

<Film formation>
Film formation was performed according to the following co-flow spread.

[Hypersalivation (solution film formation)]
-Preparation of polymer solution-
The liquid crystal polymers shown in Table 1 are added to N-methylpyrrolidone, stirred at 140 ° C. for 4 hours to form a solution, and then first passed through a sintered fiber metal filter having a nominal pore size of 10 μm, and then also nominally. It was passed through a sintered fiber filter having a pore size of 10 μm. Subsequently, the additives shown in Table 1 were added, and the mixture was stirred at 25 ° C. for 30 minutes to obtain a polymer solution. The solid content concentration was 23% by mass for the solution for layer A and 20% by mass for the solution for layer B.

-Manufacturing of polymer film and single-sided copper-clad laminate-
The obtained polymer solution for layer A and the polymer solution for layer B were sent to a casting die equipped with a feed block adjusted for co-casting of a two-layer structure (layer A / layer B), and the roughness was low. The layer A was cast so as to be in contact with the treated surface of the copper foil (CF-T4X-SV-12, thickness 12 μm, manufactured by Fukuda Metal Leaf Powder Industry Co., Ltd.). The solvent was removed from the cast film by drying at 40 ° C. for 4 hours to obtain a single-sided copper-clad laminate with a polymer film.

<Manufacturing of double-sided copper-clad laminate>
-Copper-clad laminate precursor process-
Place the low-roughness copper foil (CF-T4X-SV-12, thickness 12 μm, manufactured by Fukuda Metal Leaf Powder Industry Co., Ltd.) on the single-sided copper-clad laminate of Comparative Example 1 so that the treated surface side is in contact with the polymer film. , Laminated for 1 minute at 140 ° C. and a laminating pressure of 0.4 MPa using a laminator (“Vacuum Laminator V-130” manufactured by Nikko Materials Co., Ltd.) to obtain a precursor of a double-sided copper foil laminated plate. Obtained.

-This thermocompression bonding process-
Using a thermocompression bonding machine (“MP-SNL” manufactured by Toyo Seiki Seisakusho Co., Ltd.), the obtained copper-clad laminate precursor was thermocompression-bonded at 300 ° C. and 4.5 MPa for 10 minutes, thereby copper-clad on both sides. A laminated board was produced.

<Manufacturing of flexible wiring board>
Using the obtained single-sided copper-clad laminate and double-sided copper-clad laminate, a flexible wiring board having a four-layer stripline structure of an outer layer plane (ground layer) was produced.

-Process of forming wiring base material-
A wiring group including a signal line in which a metal foil is patterned on one side of the double-sided copper-clad laminate by a known photofabrication method and the line and space (L / S) is a striped pattern of 300 μm / 300 μm. A material (having a metal foil portion and a polymer film portion on the surface) was prepared.

-Laminating process-
Using the wiring substrate and the single-sided copper-clad laminate, the layer configuration of the single-sided copper-clad laminate / wiring substrate is such that the polymer film side of the single-sided copper-clad laminate is in contact with the signal line side of the wiring substrate. It was placed and laminated at 300 ° C. using a vacuum press device to prepare a flexible wiring board.

<< Evaluation >>
The produced polymer film was evaluated by the above-mentioned method, and the results are shown in Table 1. The dielectric loss tangent and the coefficient of thermal expansion were measured using the single-sided copper-clad laminate as it was.
Further, the peel strength of the produced flexible wiring board was evaluated by cutting out a sample having a width of 1.0 cm in the direction orthogonal to the striped pattern from the wiring substrate. It is estimated that the lower limit of the peel strength is due to the polymer film portion of the wiring substrate.

From the results shown in Table 1, the polymer films of Examples 1 to 4, which are the polymer films according to the present disclosure, have better adhesion to other polymer films and metal foils than the polymer films of Comparative Example 1. In the polymer film of Comparative Example 1, the peel strength was distributed, and the peel strength of the portion where the films were in contact with each other was low.
Further, from the results shown in Table 1, the polymer films of Examples 1 to 4, which are the polymer films according to the present disclosure, have a low dielectric loss tangent.

Claims (21)

It has a layer A and a layer B on at least one surface of the layer A.
At least one of the layer A and the layer B is a layer that can be expanded in volume by an external stimulus.
A polymer film having a dielectric loss tangent of 0.005 or less. The polymer film according to claim 1, wherein the layer B is a layer that can be expanded in volume by the external stimulus. The polymer film according to claim 2, wherein the difference in expansion coefficient between the layer A and the layer B due to the external stimulus is 0.1% or more. The polymer film according to claim 2 or 3, wherein the expansion rate of the layer B at 300 ° C. is 0.1% or more. The polymer film according to any one of claims 2 to 4, wherein the expansion rate of the layer B at 300 ° C. is larger than the expansion rate of the layer A at 300 ° C. The polymer film according to any one of claims 1 to 5, wherein the coefficient of thermal expansion αs of the layer B is larger than the coefficient of thermal expansion αc of the layer A. The polymer film according to any one of claims 1 to 6, wherein the layer B contains a foaming agent. The polymer film according to any one of claims 1 to 7, wherein the polymer film contains a filler in any of the layers. The polymer film according to claim 8, wherein the number density of the filler is larger inside than on the surface of the polymer film. The polymer film according to claim 8 or 9, wherein the layer B contains a filler. The polymer film according to claim 10, wherein the layer B contains a needle-like filler or a filler having protrusions. The polymer film according to any one of claims 1 to 11, wherein the polymer film has a coefficient of linear expansion of −20 ppm / K to 50 ppm / K. The polymer film according to any one of claims 1 to 12, wherein the polymer film has a dielectric loss tangent of 0.004 or less. The polymer film according to any one of claims 1 to 13, wherein the polymer film contains a liquid crystal polymer in any layer. The polymer film according to claim 14, wherein the liquid crystal polymer is a liquid crystal polymer having a structural repeating unit represented by any of the formulas (1) to (3).
Equation (1) -O-Ar ¹ -CO-
Equation (2) -CO-Ar ² -CO-
Equation (3) -X-Ar ³ -Y-
In the formulas (1) to (3), Ar ¹ represents a phenylene group, a naphthylene group or a biphenylylene group, and Ar ² and Ar ³ independently represent a phenylene group, a naphthylene group, a biphenylylene group or the following formula (4). Represents a group represented by, X and Y each independently represent an oxygen atom or an imino group, and the hydrogen atom in the group represented by Ar ¹ to Ar ³ independently represents a halogen atom and an alkyl group, respectively. Alternatively, it may be substituted with an aryl group.
Equation (4) -Ar ⁴ -Z-Ar ^5-
In formula (4), Ar ⁴ and Ar ⁵ independently represent a phenylene group or a naphthylene group, and Z represents an oxygen atom, a sulfur atom, a carbonyl group, a sulfonyl group or an alkylene group. Further having layer C
The polymer film according to any one of claims 1 to 15, which has the layer B, the layer A, and the layer C in this order. A laminate having the polymer film according to any one of claims 1 to 16 and a copper layer arranged on the surface of the polymer film on the layer B side. The laminate according to claim 17, wherein the average thickness of the layer B is larger than the average thickness of the copper layer. The laminate according to claim 17 or 18, wherein the peel strength between the layer B and the copper layer is 0.5 kN / m or more. A laminate having the polymer film according to claim 16, a copper layer arranged on the surface of the polymer film on the layer B side, and a copper layer arranged on the surface of the polymer film on the layer C side. The laminate according to claim 20, wherein the peel strength between the layer C and the copper layer arranged on the surface on the layer C side is 0.5 kN / m or more.