KR20230117670A - Metal clad laminate and circuit board - Google Patents

Abstract

[Problem] To provide a polyimide film that achieves both low dielectric loss tangent and excellent long-term heat-resistant adhesiveness, and whose adhesiveness to a metal layer is less likely to decrease even when repeatedly exposed to a high-temperature environment.
[Solution] A polyimide film having a non-thermoplastic polyimide layer and a thermoplastic polyimide layer, (i) having a thermal expansion coefficient in the range of 10 to 30 ppm/K, (ii) having an oxygen permeability of 5.5×10 ^-14 mol/ (m 2 · s · Pa) or less, (iii) the ratio of monomer residues having a biphenyl skeleton to all monomer residues derived from the non-thermoplastic polyimide and all monomer components constituting the thermoplastic polyimide is 50 mol% or more polyimide film that meets the requirements.

Description

Metal clad laminate and circuit board {METAL CLAD LAMINATE AND CIRCUIT BOARD}

The present invention relates to a polyimide film, a metal-clad laminate, and a circuit board.

BACKGROUND OF THE INVENTION Polyimide resins have characteristics such as high insulation, dimensional stability, ease of molding, and light weight, and therefore are widely used as materials for circuit boards and the like in electronic and electrical equipment and electronic parts. Particularly in recent years, along with high performance and high functionality of electrical and electronic equipment, high-speed transmission of information is required, and parts and members used therein are also required to respond to high-speed transmission. For polyimide materials used for such applications, attempts have been made to achieve low permittivity and low dielectric dissipation so as to have electrical properties corresponding to high-speed transmission.

Most of the conventional technologies related to low dielectric constant and low dielectric loss tangent of polyimide materials include multilayering with low dielectric constant and low dielectric loss tangent resins (fluorine-based resins, liquid crystal polymers, etc.) and blending of fillers with low dielectric constant and low dielectric loss tangent. Composite with the same heterogeneous material, porous formation, introduction of ester structure, etc. were the main ones. However, there is a problem that processability is lowered for compounding or porous formation, and the film strength of the ester structure is lowered, so there is a problem that it cannot be used in large amounts.

Further, Patent Literatures 1 and 2 propose polyimide films capable of being applied to circuit boards for high frequencies by devising a structure of a raw material monomer of polyimide to improve dielectric properties.

On the other hand, in recent years, it has also come to be assumed that circuit boards are used in an environment exceeding 150°C. For example, flexible printed circuits (FPCs) used in vehicle-mounted electronic devices may be repeatedly exposed to a high-temperature environment of about 150°C.

In addition, flexible printed circuit boards are also used in devices other than vehicle-mounted electronic devices, such as notebook computers and supercomputers having a CPU (Central Processing Unit) capable of high-speed processing, in order to achieve further miniaturization and weight reduction. happening is increasing. Also in such a device, the flexible printed circuit board is repeatedly exposed to a high-temperature environment by the heat generated by the CPU. A typical cause of deterioration of a flexible printed circuit board resulting from use in a high-temperature environment is lifting or peeling of the wiring layer due to a decrease in adhesiveness between the wiring layer and the insulating resin layer.

From this background, in the future, it is expected that flexible printed circuit boards will require both low dielectric dissipation and heat resistance adhesiveness (maintenance of peel strength retention) in a high-temperature environment. It is thought that maintenance of heat-resistant adhesiveness over a long period of time will be required.

WO2017/159274 WO2018/061727

Accordingly, an object of the present invention is to provide a polyimide film that achieves both low dielectric loss tangent and excellent long-term heat-resistant adhesiveness, and whose adhesiveness to a metal layer is less likely to decrease even when repeatedly exposed to a high-temperature environment.

As a result of intensive research, the inventors of the present invention have found that, in the polyimide constituting the polyimide layer, the dielectric loss tangent of a polyimide film in which a plurality of polyimide layers are laminated is reduced by increasing the content ratio of monomer residues having a biphenyl backbone. and suppression of oxygen permeability to find that coexistence of excellent long-term heat-resistant adhesiveness is possible, and completed the present invention.

That is, the polyimide film of the present invention comprises a non-thermoplastic polyimide layer containing non-thermoplastic polyimide and a thermoplastic polyimide layer containing thermoplastic polyimide laminated on at least one surface of the non-thermoplastic polyimide layer. is to have

The polyimide film of the present invention is characterized by satisfying the following conditions (i) to (iii).

(i) The thermal expansion coefficient is in the range of 10 to 30 ppm/K.

(ii) Those with an oxygen permeability of 5.5 × 10 ^-14 mol/(m 2 ·s ·Pa) or less.

(iii) The proportion of monomer residues having a biphenyl skeleton calculated by the following formula (1) relative to all monomer residues derived from the non-thermoplastic polyimide and all monomer components constituting the thermoplastic polyimide is 50 mol% more than

In Formula (1), M _i is the ratio (unit; unit; mol%), L _i is the thickness (unit: μm) of the polyimide layer of the i-th layer, L is the thickness (unit: μm) of the polyimide film, and n is an integer greater than or equal to 2.

In addition to the conditions (i) to (iii), the polyimide film of the present invention may further satisfy the following condition (iv).

(iv) Of all the monomer residues derived from all the monomer components in the thermoplastic polyimide, the proportion of the monomer residue having a biphenyl skeleton is 30 mol% or more.

The polyimide film of the present invention may have a total thickness in the range of 30 to 60 μm. In this case, the ratio T2/T1 of the total thickness T2 of the thermoplastic polyimide layer to the total thickness T1 of the polyimide film may be 0.17 or less.

The metal-clad laminate of the present invention is a metal-clad laminate comprising an insulating resin layer and a metal layer provided on at least one surface of the insulating resin layer. And in the metal-clad laminate of the present invention, the insulating resin layer has a thermoplastic polyimide layer in contact with the surface of the metal layer and a non-thermoplastic polyimide layer laminated indirectly, and contains any of the above polyimide films characterized by

The circuit board of the present invention is a circuit board provided with an insulating resin layer and a wiring layer provided on at least one surface of the insulating resin layer. And the circuit board of the present invention is characterized in that the insulating resin layer has a thermoplastic polyimide layer in contact with the wiring layer and a non-thermoplastic polyimide layer laminated indirectly, and includes any of the above polyimide films. do.

In the polyimide film of the present invention, by setting the content of the monomer residue having a biphenyl skeleton to 50 mol% or more, the oxygen permeability is suppressed, and both the low dielectric constant and the improvement of the long-term heat resistance adhesiveness are achieved. Therefore, by using the polyimide film of the present invention as a circuit board material, a circuit board capable of handling high-speed transmission and maintaining adhesion to the metal layer for a long period of time even in a use environment repeatedly exposed to a high temperature environment can be obtained. can provide

1 is a schematic cross-sectional view showing the configuration of a polyimide film according to an embodiment of the present invention.
2 is a schematic cross-sectional view showing another structural example of a polyimide film according to an embodiment of the present invention.

Next, embodiments of the present invention will be described.

[Polyimide film]

A polyimide film according to an embodiment of the present invention is a non-thermoplastic polyimide layer containing non-thermoplastic polyimide, and a thermoplastic poly containing thermoplastic polyimide laminated on at least one side of the non-thermoplastic polyimide layer. It is a polyimide film having a mid layer. Here, "non-thermoplastic polyimide" has a storage modulus of 1.0 × 10 ⁹ Pa or more at 30 ° C. measured using a dynamic viscoelasticity measuring device (DMA), and is stored in a temperature range within the glass transition temperature + 30 ° C. It means that the elastic modulus shows 1.0×10 ⁸ Pa or more. "Thermoplastic polyimide" has a storage modulus of 1.0 × 10 ⁹ Pa or more at 30°C measured using a dynamic viscoelasticity measuring device (DMA), and a storage modulus of 1.0 in a temperature range within the glass transition temperature + 30°C. It means showing less than ×10 ⁸ Pa.

1 and 2 show a structural example of the polyimide film according to the present embodiment. The polyimide film 100 shown in FIG. 1 is an aspect of a two-layer structure in which a thermoplastic polyimide layer 120A is laminated on one side of a non-thermoplastic polyimide layer 110 . The polyimide film 101 shown in FIG. 2 has a three-layer structure in which a thermoplastic polyimide layer 120A is laminated on one surface of a non-thermoplastic polyimide layer 110 and a thermoplastic polyimide layer 120B is laminated on the other surface. is the aspect of In addition, the polyimide film of this embodiment is not limited to the laminated structure illustrated in FIG. 1 and FIG. 2, For example, you may be provided with 4 or more layers of polyimide layers.

The resin component of the non-thermoplastic polyimide layer 110 preferably contains non-thermoplastic polyimide, and the resin component of the thermoplastic polyimide layers 120A and 120B preferably contains thermoplastic polyimide. When the polyimide films 100 and 101 and the metal foil are laminated to form a metal clad laminate, the metal foil can be laminated on one side or both sides of the thermoplastic polyimide layers 120A and 120B.

In addition, both a non-thermoplastic polyimide and a thermoplastic polyimide contain an acid dianhydride residue and a diamine residue as a "monomer residue." "Acid dianhydride residue" means a tetravalent group derived from tetracarboxylic acid dianhydride, and "diamine residue" means a divalent group derived from a diamine compound.

In the polyimide films 100 and 101 of the present embodiment, the non-thermoplastic polyimide layer 110 constitutes a low thermal expansion polyimide layer, and the thermoplastic polyimide layers 120A and 120B constitute a high thermal expansion polyimide layer. make up The low thermal expansion polyimide layer refers to a polyimide layer having a coefficient of thermal expansion (CTE) preferably within the range of 1 ppm/K or more and 25 ppm/K or less, more preferably within the range of 3 ppm/K or more and 25 ppm/K or less. Further, the high thermal expansible polyimide layer has a CTE of preferably 35 ppm/K or more, more preferably within the range of 35 ppm/K or more and 80 ppm/K or less, and still more preferably in the range of 35 ppm/K or more and 70 ppm/K or less. refers to the inner polyimide layer. A polyimide layer having a desired CTE can be obtained by appropriately changing the combination of raw materials, thickness, and drying/curing conditions.

The polyimide films 100 and 101 of the present embodiment satisfy the following conditions (i) to (iii).

(i) The thermal expansion coefficient is in the range of 10 to 30 ppm/K.

When the polyimide films 100 and 101 of the present embodiment are applied, for example, as an insulating resin layer of a circuit board, in order to prevent occurrence of warpage and a decrease in dimensional stability, the coefficient of thermal expansion (CTE) of the entire film It is important that ) is within the range of 10 ppm/K or more and 30 ppm/K or less, preferably within the range of 10 ppm/K or more and 25 ppm/K or less, and more preferably within the range of 15 to 25 ppm/K. When the CTE is less than 10 ppm/K or exceeds 30 ppm/K, warpage occurs or dimensional stability deteriorates.

(ii) Those with an oxygen permeability of 5.5 × 10 ^-14 mol/(m 2 ·s ·Pa) or less.

By controlling the oxygen permeability of the polyimide films 100 and 101 to 5.5 × 10 ^-14 mol/(m 2 ·s ·Pa) or less, for example, in the case of application as an insulating resin layer of a circuit board, repeated high temperature Even in an environment where it is exposed to, the adhesiveness with the wiring layer is maintained over a long period of time, and excellent long-term heat-resistant adhesiveness is obtained. When the oxygen permeability of the polyimide films 100 and 101 exceeds 5.5 × 10 ^-14 mol/(m 2 ·s ·Pa), for example, it is applied as an insulating resin layer of a circuit board and repeatedly exposed to high temperatures. In this case, oxidation of the wiring layer proceeds due to oxygen that has passed through the insulating resin layer, and the adhesion between the wiring layer and the insulating resin layer is lowered.

(iii) Monomer residues having a biphenyl skeleton calculated by the following formula (1) with respect to all monomer residues derived from the non-thermoplastic polyimide and all monomer components constituting the thermoplastic polyimide (hereinafter referred to as "biphenyl skeleton-containing (sometimes described as "residue") is 50 mol% or more.

In formula (1), M _i is the ratio (unit: mol%) of biphenyl backbone-containing residues among all monomer residues derived from all monomer components in the polyimide constituting the polyimide layer of the i-th layer. ), L _i is the thickness (unit; μm) of the polyimide layer of the i-th layer, L is the thickness (unit: μm) of the polyimide film, and n is an integer greater than or equal to 2.

When the ratio of biphenyl skeleton-containing residues calculated by formula (1) to all monomer residues derived from all monomer components of the polyimide constituting the polyimide films 100 and 101 is 50 mol% or more, the monomer origin The rigid structure of makes it easy to form an ordered structure throughout the polymer, reducing the oxygen permeability, and reducing the dielectric loss tangent by suppressing molecular motion. If the proportion of biphenyl skeleton-containing residues is less than 50 mol%, the dielectric loss tangent does not sufficiently decrease. In addition, when the thickness of the polyimide film is thin, the oxygen permeability does not sufficiently decrease. For this reason, when used for a circuit board, for example, long-term heat-resistant adhesion becomes insufficient, and adaptation to high-speed transmission becomes difficult. From such a viewpoint, it is preferable that it is 60 mol% or more, and, as for the ratio of the biphenyl skeleton containing residue computed by Formula (1), it is more preferable that it is 65 mol% or more. On the other hand, in order to maintain physical properties required for a polyimide film usable as a circuit board material, the proportion of biphenyl skeleton-containing residues calculated by Formula (1) is preferably 80 mol% or less.

Here, the biphenyl skeleton is a skeleton in which two phenyl groups are single-bonded, as shown in formula (a) below. Therefore, the biphenyl skeleton-containing residue includes, for example, a biphenyldiyl group and a biphenyltetrayl group. The aromatic ring contained in these residues may have arbitrary substituents.

Representative examples of the biphenyldiyl group include those represented by the following formula (b). Representative examples of the biphenyl tetrayl group include those represented by the following formula (c). In addition, in the biphenyldiyl group and the biphenyltetrayl group, the bond in the aromatic ring is not limited to the positions shown in the formulas (b) and (c), and as described above, these residues The aromatic ring contained may have arbitrary substituents.

The biphenyl skeleton-containing residue has a structure derived from a raw material monomer, and may be derived from an acid dianhydride or derived from a diamine compound.

Representative examples of acid dianhydride residues having a biphenyl skeleton include 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA) and 2,3',3,4'-biphenyltetracarboxylic acid dianhydride (BPDA). and residues derived from acid dianhydrides such as acid dianhydride and 4,4'-biphenol-bis(trimellitate anhydride). Among these, acid dianhydride residues derived from BPDA (hereinafter also referred to as “BPDA residues”) are preferred because they easily form an ordered structure in a polymer and can reduce the dielectric loss tangent and hygroscopicity by suppressing molecular motion. . In addition, the BPDA residue can impart self-supporting properties to the gel film as the polyamic acid of the polyimide precursor.

Representative examples of diamine compounds having a biphenyl backbone include diamine compounds having only two aromatic rings, 2,2'-dimethyl-4,4'-diaminobiphenyl (m-TB), 2,2' -Diethyl-4,4'-diaminobiphenyl (m-EB), 2,2'-diethoxy-4,4'-diaminobiphenyl (m-EOB), 2,2'-dipropoxy -4,4'-diaminobiphenyl (m-POB), 2,2'-di-n-propyl-4,4'-diaminobiphenyl (m-NPB), 2,2'-divinyl- 4,4'-diaminobiphenyl (VAB), 4,4'-diaminobiphenyl, 4,4'-diamino-2,2'-bis (trifluoromethyl) biphenyl (TFMB), etc. can be heard Since the residue derived from these diamine compounds has a rigid structure, it has an action of imparting an ordered structure to the entire polymer. By containing residues derived from these diamine compounds, a polyimide having low oxygen permeability and low hygroscopicity can be obtained, and since the moisture inside the molecular chain can be reduced, the dielectric loss tangent can be lowered.

The polyimide films 100 and 101 of the present embodiment preferably satisfy the following condition (iv) in addition to the conditions (i) to (iii) above.

(iv) Of all the monomer residues derived from all the monomer components in the thermoplastic polyimide, the ratio occupied by the biphenyl skeleton-containing residue is 30 mol% or more.

When the proportion of the biphenyl skeleton-containing residues among all the monomer residues constituting the thermoplastic polyimide is 30 mol% or more, an ordered structure is formed throughout the polymer due to the monomer-derived rigid structure, so that the oxygen permeability and hygroscopicity are improved while being thermoplastic. A polyimide with a low dielectric loss tangent, excellent long-term heat resistance and a low dielectric loss tangent is obtained. In the case where the thermoplastic polyimide layers 120A and 120B are provided on both sides of the non-thermoplastic polyimide layer 110, either one of the thermoplastic polyimide layers 120A or 120B may satisfy the above condition (iv), It is preferable that both thermoplastic polyimide layers 120A and 120B satisfy the above condition (iv).

<thickness>

The overall thickness T1 of the polyimide films 100 and 101 of the present embodiment can be set within a predetermined range depending on the purpose of use, and is preferably within the range of 30 to 60 μm, for example, It is more preferably within the range of 35 to 50 μm. If the thickness T1 is less than the lower limit, it becomes difficult to sufficiently lower the oxygen permeability, and there is a risk that the adhesiveness between the wiring layer and the insulating resin layer may deteriorate when repeatedly exposed to high temperatures. On the other hand, if the thickness T1 exceeds the above upper limit, problems such as cracks and rupture occur when the polyimide film is bent.

In addition, the total thickness T2 of the thermoplastic polyimide layers 120A and 120B relative to the total thickness T1 of the polyimide films 100 and 101 (here, T2 means T2A in FIG. 1 and T2A+T2B in FIG. 2) ) is preferably 0.17 or less, and more preferably in the range of 0.10 to 0.15. When the value of this ratio is larger than 0.17, the oxygen permeability increases and it becomes difficult to lower the dielectric loss tangent. Therefore, when used for, for example, a circuit board, long-term heat-resistant adhesion becomes insufficient, and adaptation to high-speed transmission becomes difficult.

The lower limit of the ratio T2/T1 is not particularly limited. This is because the smaller the ratio T2/T1, the easier it is to reduce the oxygen permeability and the dielectric loss tangent. However, since the thickness ratio occupied by the thermoplastic polyimide layers 120A and 120B relatively decreases as the ratio T2/T1 decreases, the lower limit of the ratio T2/T1 is the polyimide film 100 and 101 As a value capable of securing the adhesion reliability of the wiring layer, for example, about 0.02 is preferable.

In addition, the thickness T3 of the non-thermoplastic polyimide layer 110 can be set within a predetermined range depending on the purpose of use, and is preferably in the range of 25 to 49 μm, for example, 30 to 49 μm. It is more preferable to be within the range of When the thickness T3 is less than the lower limit, the effect of improving the dielectric properties of the polyimide films 100 and 101 is reduced, the oxygen permeability is increased, and the adhesion between the wiring layer and the insulating resin layer when repeatedly exposed to high temperatures is reduced. There is a risk of deterioration.

In general, polyimide can be produced by reacting an acid dianhydride and a diamine compound in a solvent to produce a polyamic acid, followed by heat cyclization (imidization). For example, polyamic acid as a precursor of polyimide is obtained by dissolving an acid dianhydride and a diamine compound in substantially equimolar amounts in an organic solvent, stirring them at a temperature in the range of 0 to 100°C for 30 minutes to 24 hours, and causing a polymerization reaction. During the reaction, the reaction components are dissolved so that the precursor to be produced is within the range of 5 to 30% by weight, preferably within the range of 10 to 20% by weight, in the organic solvent. As an organic solvent used for a polymerization reaction, for example, N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAc), N,N-diethylacetamide, N-methyl-2-p Rolidone (NMP), 2-butanone, dimethylsulfoxide (DMSO), hexamethylphosphoramide, N-methylcaprolactam, dimethyl sulfate, cyclohexanone, dioxane, tetrahydrofuran, diglyme, triglyme , Cresol, etc. are mentioned. Two or more of these solvents may be used in combination, and also aromatic hydrocarbons such as xylene and toluene may be used in combination. The amount of the organic solvent used is not particularly limited, but it is preferable to adjust the amount used such that the concentration of the polyamic acid solution obtained by the polymerization reaction is about 5 to 30% by weight.

The synthesized polyamic acid is usually advantageously used as a reaction solvent solution, but can be concentrated, diluted, or substituted with another organic solvent if necessary. In addition, polyamic acids are advantageously used because they generally have good solvent solubility. The viscosity of the polyamic acid solution is preferably in the range of 500 cps to 100,000 cps. Outside of this range, defects such as uneven thickness and streaks tend to occur in the film during coating work by a coater or the like. The method of imidizing the polyamic acid is not particularly limited, and, for example, a heat treatment of heating in the above solvent at a temperature within a range of 80 to 400°C for 1 to 24 hours is suitably employed.

Next, non-thermoplastic polyimide and thermoplastic polyimide will be described more specifically.

<Non-thermoplastic polyimide>

In the polyimide films 100 and 101, the non-thermoplastic polyimide constituting the non-thermoplastic polyimide layer 110 contains an acid dianhydride residue and a diamine residue. The non-thermoplastic polyimide preferably contains 60 mol% or more of biphenyl skeleton-containing residues, more preferably 70 mol% or more, among all monomer residues derived from all monomer components. By setting the biphenyl skeleton-containing residue in the non-thermoplastic polyimide to 60 mol% or more, the content ratio of the biphenyl skeleton-containing residue in the entire polyimide constituting the polyimide films 100 and 101 is increased and the oxygen permeability is lowered. , a low dielectric loss tangent can be achieved.

(acid dianhydride residue)

The non-thermoplastic polyimide preferably contains 35 mol% or more of acid dianhydride residues having a biphenyl skeleton, and more preferably contains 50 mol% or more of all acid dianhydride residues. More preferably, it is good to contain the biphenyl tetrayl group represented by formula (c) in the said amount.

The non-thermoplastic polyimide may contain, in addition to the above acid dianhydride residues having a biphenyl backbone, acid dianhydride residues generally used as raw materials for polyimide within a range not impairing the effect of the invention. As such acid dianhydride residues, for example, pyromellitic dianhydride (PMDA), 1,4-phenylenebis(trimellitic acid monoester) dianhydride (TAHQ), 2,3,6,7-naphthalenetetracar Boxylic acid dianhydride (NTCDA), 3,3',4,4'-diphenylsulfotetracarboxylic acid dianhydride, 4,4'-oxydiphthalic anhydride, 2,2',3,3'-, 2 ,3,3',4'- or 3,3',4,4'-benzophenonetetracarboxylic dianhydride, 2,3',3,4'-diphenylethertetracarboxylic dianhydride, bis (2,3-dicarboxyphenyl)ether dianhydride, 3,3",4,4"-, 2,3,3",4"- or 2,2",3,3"-p-terphenyltetra carboxylic acid dianhydride, 2,2-bis(2,3- or 3,4-dicarboxyphenyl)-propane dianhydride, bis(2,3- or 3,4-dicarboxyphenyl)methane dianhydride, bis (2,3- or 3,4-dicarboxyphenyl) sulfone dianhydride, 1,1-bis (2,3- or 3,4-dicarboxyphenyl) ethane dianhydride, 1,2,7,8-, 1,2,6,7- or 1,2,9,10-phenanthrene-tetracarboxylic dianhydride, 2,3,6,7-anthracentetracarboxylic dianhydride, 2,2-bis(3 ,4-dicarboxyphenyl) tetrafluoropropane dianhydride, 2,3,5,6-cyclohexane dianhydride, 1,2,5,6-naphthalenetetracarboxylic dianhydride, 1,4,5,8 -Naphthalenetetracarboxylic dianhydride, 4,8-dimethyl-1,2,3,5,6,7-hexahydronaphthalene-1,2,5,6-tetracarboxylic dianhydride, 2,6- or 2,7-dichloronaphthalene-1,4,5,8-tetracarboxylic dianhydride, 2,3,6,7-(or 1,4,5,8-)tetrachloronaphthalene-1,4; 5,8-(or 2,3,6,7-)tetracarboxylic dianhydride, 2,3,8,9-, 3,4,9,10-, 4,5,10,11- or 5 ,6,11,12-perylene-tetracarboxylic dianhydride, cyclopentane-1,2,3,4-tetracarboxylic dianhydride, pyrazine-2,3,5,6-tetracarboxylic dianhydride Water, pyrrolidine-2,3,4,5-tetracarboxylic dianhydride, thiophene-2,3,4,5-tetracarboxylic dianhydride, 4,4'-bis(2,3- and acid dianhydride residues derived from aromatic tetracarboxylic acid dianhydrides such as dicarboxyphenoxy)diphenylmethane dianhydride and ethylene glycol bisanhydrotrimellitate.

(diamine residue)

The non-thermoplastic polyimide preferably contains 70 mol% or more of diamine residues having a biphenyl skeleton, and more preferably contains 85 mol% or more of all diamine residues. More preferably, it is good to contain the biphenyldiyl group represented by formula (b) in the said amount. Since the biphenyldiyl group represented by formula (b) has a rigid structure and has an action of imparting an ordered structure to the entire polymer, it can lower the oxygen permeability and reduce the dielectric loss tangent by suppressing molecular motion. there is.

The non-thermoplastic polyimide may contain, in addition to the diamine residue having a biphenyl skeleton described above, a residue of a diamine compound that can be generally used as a raw material for polyimide within a range not impairing the effect of the invention. As such diamine residues, for example, 1,4-diaminobenzene (p-PDA; paraphenylenediamine), 4-aminophenyl-4'-aminobenzoate (APAB), 3,3'-diaminodiphenyl Methane, 3,3'-diaminodiphenylpropane, 3,3'-diaminodiphenyl sulfide, 3,3'-diaminodiphenylsulfone, 3,3'-diaminodiphenyl ether, 3,4 '-diaminodiphenyl ether, 3,4'-diaminodiphenylmethane, 3,4'-diaminodiphenylpropane, 3,4'-diaminodiphenyl sulfide, 3,3'-diaminobenzo Phenone, (3,3'-bisamino)diphenylamine, 1,4-bis(3-aminophenoxy)benzene, 3-[4-(4-aminophenoxy)phenoxy]benzenamine, 3-[ 3-(4-aminophenoxy)phenoxy]benzenamine, 1,3-bis(4-aminophenoxy)benzene (TPE-R), 1,3-bis(3-aminophenoxy)benzene (APB) , 4,4'-[2-methyl-(1,3-phenylene)bisoxy]bisaniline, 4,4'-[4-methyl-(1,3-phenylene)bisoxy]bisaniline, 4 ,4'-[5-methyl-(1,3-phenylene)bisoxy]bisaniline, bis[4,4'-(3-aminophenoxy)]benzanilide, 4-[3-[4-( 4-aminophenoxy)phenoxy]phenoxy]aniline, 4,4'-[oxybis(3,1-phenyleneoxy)]bisaniline, bis[4-(4-aminophenoxy)phenyl]ether ( BAPE), bis[4-(4-aminophenoxy)phenyl]sulfone (BAPS), bis[4-(4-aminophenoxy)phenyl]ketone (BAPK), 2,2-bis-[4-(3 -aminophenoxy)phenyl]propane, 2,2-bis[4-(4-aminophenoxy)phenyl]propane (BAPP), bis[4-(3-aminophenoxy)phenyl]sulfone, bis[4- (3-aminophenoxy)phenyl]methane, bis[4-(3-aminophenoxy)phenyl]ether, bis[4-(3-aminophenoxy)]benzophenone, 9,9-bis[4-( 3-aminophenoxy)phenyl]fluorene, 2,2-bis-[4-(4-aminophenoxy)phenyl]hexafluoropropane, 2,2-bis-[4-(3-aminophenoxy) Phenyl] hexafluoropropane, 3,3'-dimethyl-4,4'-diaminobiphenyl, 4,4'-methylenedi-o-toluidine, 4,4'-methylenedi-2,6-xyly Dean, 4,4'-methylene-2,6-diethylaniline, 3,3'-diaminodiphenylethane, 3,3'-diaminobiphenyl, 3,3'-dimethoxybenzidine, 3,3 "-diamino-p-terphenyl, 4,4'-[1,4-phenylenebis(1-methylethylidene)]bisaniline, 4,4'-[1,3-phenylenebis(1 -methylethylidene)]bisaniline, bis(p-aminocyclohexyl)methane, bis(p-β-amino-t-butylphenyl)ether, bis(p-β-methyl-δ-aminopentyl)benzene, p-bis(2-methyl-4-aminopentyl)benzene, p-bis(1,1-dimethyl-5-aminopentyl)benzene, 1,5-diaminonaphthalene, 2,6-diaminonaphthalene, 2, 4-bis(β-amino-t-butyl)toluene, 2,4-diaminotoluene, m-xylene-2,5-diamine, p-xylene-2,5-diamine, m-xylylenediamine, p -xylylenediamine, 2,6-diaminopyridine, 2,5-diaminopyridine, 2,5-diamino-1,3,4-oxadiazole, piperazine, 2'-methoxy-4, 4'-diaminobenzanilide, 4,4'-diaminobenzanilide, 1,3-bis[2-(4-aminophenyl)-2-propyl]benzene, 1,4-bis[2-(4-) Aminophenyl)-2-propyl]benzene, 1,4-bis(4-aminophenoxy)-2,5-di-tert-butylbenzene, 6-amino-2-(4-aminophenoxy)benzoxazole , 2,6-diamino-3,5-diethyltoluene, 2,4-diamino-3,5-diethyltoluene, 2,4-diamino-3,3'-diethyl-5,5' Diamine residues derived from aromatic diamine compounds such as dimethyldiphenylmethane and bis(4-amino-3-ethyl-5-methylphenyl)methane, and the two terminal carboxylic acid groups of dimer acid are converted to primary aminomethyl groups or amino groups. and diamine residues derived from aliphatic diamine compounds such as substituted dimer acid type diamines.

In the non-thermoplastic polyimide, oxygen permeability, dielectric properties, thermal expansion coefficient, Storage modulus, tensile modulus and the like can be controlled. In addition, in non-thermoplastic polyimide, when it has a plurality of polyimide structural units, it may exist as a block or may exist randomly, but it is preferable to exist randomly.

The non-thermoplastic polyimide preferably contains an aromatic tetracarboxylic acid residue derived from an aromatic tetracarboxylic dianhydride and an aromatic diamine residue derived from an aromatic diamine. By making both the acid dianhydride residue and the diamine residue contained in the non-thermoplastic polyimide an aromatic group, the dimensional accuracy of the polyimide films 100 and 101 in a high-temperature environment can be improved.

It is preferable that the imide group concentration of the non-thermoplastic polyimide is 33% by weight or less. Here, "imide group concentration" means the value obtained by dividing the molecular weight of the imide group (-(CO) ₂ -N-) in the polyimide by the molecular weight of the entire structure of the polyimide. When the imide group concentration exceeds 33% by weight, hygroscopicity increases due to an increase in polar groups. By selecting the combination of the acid dianhydride and the diamine compound, the orientation of the molecules in the non-thermoplastic polyimide can be controlled, thereby suppressing the increase in CTE associated with a decrease in the imide group concentration and ensuring low hygroscopicity.

The weight average molecular weight of the non-thermoplastic polyimide is, for example, preferably within a range of 10,000 to 400,000, and more preferably within a range of 50,000 to 350,000. If the weight average molecular weight is less than 10,000, the strength of the film decreases and it tends to become brittle. On the other hand, when the weight average molecular weight exceeds 400,000, the viscosity increases excessively, and defects such as uneven film thickness and streaks tend to occur easily during the coating operation.

<Thermoplastic polyimide>

In the polyimide films 100 and 101, the thermoplastic polyimide constituting the thermoplastic polyimide layers 120A and 120B contains an acid dianhydride residue and a diamine residue. The thermoplastic polyimide preferably contains 30 mol% or more of biphenyl skeleton-containing residues, more preferably 40 mol% or more, among all monomer residues derived from all monomer components, as in condition (iv) above. do. By setting the biphenyl skeleton-containing residue in the thermoplastic polyimide to 30 mol% or more, the content ratio of the biphenyl skeleton-containing residue in the entire polyimide constituting the polyimide films 100 and 101 is increased, and the oxygen permeability is reduced. In addition, a low dielectric loss tangent can be achieved. On the other hand, in thermoplastic polyimide, since it is necessary to improve the flexibility of the polyimide molecular chain to impart thermoplasticity in order to secure adhesion to the metal layer, the upper limit of the content of the biphenyl skeleton-containing residue is set to 65 mol% or less. It is desirable to do

(acid dianhydride residue)

It is preferable that the thermoplastic polyimide contains 60 mol% or more of acid dianhydride residues having a biphenyl skeleton among all acid dianhydride residues. More preferably, it is good to contain the biphenyl tetrayl group represented by formula (c) in the said amount.

The thermoplastic polyimide may contain, in addition to the acid dianhydride residues having a biphenyl skeleton described above, acid dianhydride residues that can be generally used as raw materials for polyimide within a range not impairing the effects of the invention. As such acid dianhydride residues, acid dianhydride residues exemplified for non-thermoplastic polyimide can be mentioned.

(diamine residue)

The thermoplastic polyimide preferably contains 1 mol% or more of diamine residues having a biphenyl skeleton, and more preferably contains 5 mol% or more of all diamine residues. More preferably, it is good to contain the biphenyldiyl group represented by formula (b) in the said amount. Since the biphenyldiyl group represented by formula (b) has a rigid structure and has an action of imparting an ordered structure to the entire polymer, the dielectric loss tangent and hygroscopicity can be reduced by suppressing molecular motion. In addition, by using it as a raw material for thermoplastic polyimide, a polyimide having low oxygen permeability and excellent long-term heat-resistant adhesiveness can be obtained.

The thermoplastic polyimide may contain, in addition to the diamine residue having a biphenyl skeleton described above, a residue of a diamine compound that can be generally used as a raw material for polyimide within a range not impairing the effects of the invention. As such a diamine residue, the residue of the diamine compound exemplified for non-thermoplastic polyimide can be mentioned.

In the thermoplastic polyimide, by selecting the types of acid dianhydride residues and diamine residues or the molar ratio of each when two or more types of acid dianhydride residues or diamine residues are applied, the thermal expansion coefficient, tensile modulus, glass transition temperature, etc. can control. In addition, in thermoplastic polyimide, when it has a plurality of structural units of polyimide, it may exist as a block or may exist randomly, but it is preferable to exist randomly.

The thermoplastic polyimide preferably contains an aromatic tetracarboxylic acid residue derived from an aromatic tetracarboxylic dianhydride and an aromatic diamine residue derived from an aromatic diamine. Deterioration of the polyimide in the high-temperature environment of the polyimide films 100 and 101 can be suppressed by making both the acid dianhydride residue and the diamine residue contained in the thermoplastic polyimide an aromatic group.

The imide group concentration of the thermoplastic polyimide is preferably 30% by weight or less. Here, "imide group concentration" means the value obtained by dividing the molecular weight of the imide group (-(CO) ₂ -N-) in the polyimide by the molecular weight of the entire structure of the polyimide. When the imide group concentration exceeds 30% by weight, the elastic modulus at a temperature equal to or higher than the glass transition temperature becomes less likely to decrease, and the low hygroscopicity deteriorates due to an increase in polar groups.

The weight average molecular weight of the thermoplastic polyimide is, for example, preferably within a range of 10,000 to 400,000, and more preferably within a range of 50,000 to 350,000. If the weight average molecular weight is less than 10,000, the strength of the film decreases and it tends to become brittle. On the other hand, when the weight average molecular weight exceeds 400,000, the viscosity increases excessively, and defects such as uneven film thickness and streaks tend to occur easily during the coating operation.

In the polyimide films 100 and 101, the thermoplastic polyimide layers 120A and 120B function as adhesive layers and can improve adhesion to metal layers such as copper foil. Therefore, the glass transition temperature of the thermoplastic polyimide is preferably within the range of 200°C or more and 350°C or less, and more preferably within the range of 200°C or more and 320°C or less.

Since thermoplastic polyimide becomes, for example, an adhesive layer in contact with a wiring layer of a circuit board, a completely imidized structure is most preferable in order to suppress diffusion of copper. However, a part of polyimide may be amide acid. The imidation rate was determined by measuring the infrared absorption spectrum of the polyimide thin film by the one- ^time reflection ATR method using a Fourier transform infrared spectrophotometer (commercial product: FT/IR620 manufactured by Nippon Bunko). Based on the absorber, it is calculated from the absorbance of the C=O stretch derived from the imide group of 1780 cm ^-1 .

<Form of polyimide film>

The polyimide films 100 and 101 of the present embodiment are not particularly limited as long as they satisfy the above conditions, and may be films (sheets) made of insulating resin, for example, metal foil such as copper foil, glass plate, polyimide It may be a film of an insulating resin laminated on a substrate such as a resin sheet such as a mid-based film, a polyamide-based film, or a polyester-based film.

<Dielectric loss tangent>

When the polyimide films 100 and 101 are applied, for example, as an insulating resin layer of a circuit board, in order to reduce dielectric loss during transmission of a high-frequency signal, the entire film is used as a split post dielectric resonator (SPDR). It is preferable that the dielectric loss tangent (Tan δ) at 10 GHz when measured by ) is 0.004 or less. In order to improve the transmission loss of the circuit board, it is particularly important to control the dielectric loss tangent of the insulating resin layer, and by setting the dielectric loss tangent within the above range, the effect of lowering the transmission loss is increased. Therefore, when the polyimide films 100 and 101 are applied as, for example, an insulating resin layer of a high-frequency circuit board, transmission loss can be reduced efficiently. When the dielectric loss tangent at 10 GHz exceeds 0.004, when the polyimide films 100 and 101 are applied as an insulating resin layer of a circuit board, problems such as increased loss of electric signals on the transmission path of high-frequency signals occur. it becomes easier to do Although the lower limit of the dielectric loss tangent at 10 GHz is not particularly limited, it is necessary to consider the control of physical properties when the polyimide films 100 and 101 are applied as insulating resin layers of circuit boards.

<Permittivity>

When the polyimide films 100 and 101 are applied, for example, as an insulating resin layer of a circuit board, in order to ensure impedance matching, the film as a whole preferably has a dielectric constant of 4.0 or less at 10 GHz. When the dielectric constant at 10 GHz exceeds 4.0, when the polyimide films 100 and 101 are applied as an insulating resin layer of a circuit board, it leads to deterioration of dielectric loss, resulting in loss of electric signals on the transmission path of high-frequency signals. Problems such as enlargement are likely to occur.

<filler>

The polyimide films 100 and 101 of this embodiment may contain an inorganic filler or an organic filler in the non-thermoplastic polyimide layer 110 or the thermoplastic polyimide layer 120A, 120B as needed. Specifically, inorganic fillers such as silicon dioxide, aluminum oxide, magnesium oxide, beryllium oxide, boron nitride, aluminum nitride, silicon nitride, aluminum fluoride, and calcium fluoride; organic fillers such as fluorine-based polymer particles and liquid crystal polymer particles; can These can be used 1 type or in mixture of 2 or more types. In the case of containing an organic filler, the organic filler shall not correspond to all monomer components constituting the non-thermoplastic polyimide layer 110 or the thermoplastic polyimide layers 120A and 120B.

[Method for producing polyimide film]

As a preferable aspect of the manufacturing method of the polyimide films 100 and 101 of this embodiment, the following [1] - [3] can be illustrated, for example.

[1] A method of producing polyimide films (100, 101) by repeating applying and drying a polyamic acid solution to a supporting base material a plurality of times, followed by imidization.

[2] After repeating the application and drying of the polyamic acid solution to the supporting substrate a plurality of times, the polyamic acid gel film is peeled off from the supporting substrate and imidized to produce the polyimide films 100 and 101. method.

[3] A method for producing the polyimide films 100 and 101 by applying and drying the polyamic acid solution in a multi-layered state at the same time by multi-layer extrusion, followed by imidation (hereinafter referred to as multi-layer extrusion method).

The method of the above [1], for example, the following steps 1a to 1c;

(1a) a step of applying a polyamic acid solution to a supporting substrate and drying it;

(1b) a step of forming a polyimide layer by heat-treating and imidating polyamic acid on a support substrate;

(1c) Process of obtaining polyimide films 100 and 101 by separating the supporting substrate and the polyimide layer

can include

The method of [2] above, for example, the following steps 2a to 2c;

(2a) a step of applying a polyamic acid solution to a supporting substrate and drying it;

(2b) a step of separating the support substrate and the gel film of polyamic acid;

(2c) Process of obtaining polyimide films (100, 101) by heat-treating and imidizing the gel film of polyamic acid

can include

In the method [1] or the method [2], the multilayer structure of polyamic acid can be formed on the supporting substrate by repeating step 1a or step 2a a plurality of times. In addition, the method of applying the polyamic acid solution on the supporting substrate is not particularly limited, and for example, it is possible to apply with a coater such as a comma, die, knife, or lip.

In the method of [3] above, in step 1a of the method of [1] or step 2a of the method of [2], the multi-layer extrusion is used to simultaneously coat the laminated structure of polyamic acid and dry it. , It can be carried out in the same way as the method of [1] or the method of [2].

In the polyimide films 100 and 101 manufactured in this embodiment, it is preferable to complete imidation of polyamic acid on the supporting substrate. Since the resin layer of polyamic acid is imidized while being fixed to the support substrate, the change in expansion and contraction of the polyimide layer in the imidization process can be suppressed, and the thickness and dimensional accuracy of the polyimide films 100 and 101 can be maintained. there is.

[Metal clad laminate]

The metal-clad laminate of the present embodiment includes an insulating resin layer and a metal layer provided on at least one surface of the insulating resin layer, and a part or all of the insulating resin layer is the polyimide film (100, 101) may be used. In order to improve the adhesion between the insulating resin layer and the metal layer, it is preferable that the layer in contact with the metal layer in the insulating resin layer is a thermoplastic polyimide layer 120A, 120B.

The material of the metal layer is not particularly limited, and examples thereof include copper, stainless steel, iron, nickel, beryllium, aluminum, zinc, indium, silver, gold, tin, zirconium, tantalum, titanium, lead, magnesium, manganese, and alloys thereof. etc. can be mentioned. Among these, copper or copper alloy is particularly preferable. In addition, the material of the wiring layer in the circuit board described later is also the same as that of the metal layer.

The thickness of the metal layer is not particularly limited, but when a metal foil typified by copper foil is used, for example, it is preferably 35 μm or less, and more preferably within the range of 5 to 25 μm. From the standpoint of production stability and handling, the lower limit of the thickness of the metal foil is preferably 5 μm. Moreover, when using copper foil, a rolled copper foil or an electrolytic copper foil may be sufficient. Moreover, as copper foil, the copper foil marketed can be used.

In addition, the metal foil may be surface treated with, for example, siding, aluminum alcoholate, aluminum chelate, or a silane coupling agent for the purpose of, for example, anti-rust treatment or improvement of adhesive strength.

Next, the metal-clad laminate will be described in more detail by taking as an example a copper-clad laminate in which a metal layer is formed of copper foil. In the copper-clad laminate, copper foil is provided on one side or both sides of the insulating resin layer. That is, the copper-clad laminate may be a single-sided copper-clad laminate (single-sided CCL) or a double-sided copper-clad laminate (double-sided CCL).

The copper-clad laminate is, for example, prepared by preparing a resin film composed of the polyimide films 100 and 101 of the above embodiment, sputtering metal to this to form a seed layer, and then, for example, by copper plating. You may prepare by forming a copper foil layer.

Moreover, you may prepare a copper clad laminated board by preparing the resin film comprised including the polyimide films 100 and 101 of the said embodiment, and laminating copper foil to this by methods, such as thermal compression bonding.

In addition, the copper clad laminate may be prepared by casting a coating liquid containing polyamic acid, which is a precursor of polyimide, onto a copper foil, drying it to form a coating film, heat-treating to imidize, and forming a polyimide layer. .

[circuit board]

The metal-clad laminate of the above embodiment is mainly useful as a circuit board material such as FPC. A circuit board according to an embodiment of the present invention can be manufactured by processing the metal layer of the metal-clad laminate into a pattern shape by a conventional method to form a wiring layer.

That is, the circuit board of the present embodiment includes an insulating resin layer and a wiring layer provided on at least one side of the insulating resin layer, and a part or all of the insulating resin layer is formed of the polyimide film (100) of the above embodiment. , 101). In addition, in order to improve the adhesiveness between the insulating resin layer and the wiring layer, it is preferable that the layer in contact with the wiring layer in the insulating resin layer is a thermoplastic polyimide layer 120A, 120B.

Example

An Example is shown below, and the characteristic of this invention is demonstrated more concretely. However, the scope of the present invention is not limited to the examples. In addition, in the following examples, unless otherwise specified, various measurements and evaluations are based on the following.

[Measurement of viscosity]

The viscosity at 25°C was measured using an E-type viscometer (manufactured by Brookfield, trade name: DV-II+Pro). The number of rotations was set so that the torque was 10% to 90%, and the value when the viscosity was stable was read 2 minutes after the start of the measurement.

[Measurement of Glass Transition Temperature (Tg)]

The glass transition temperature was measured by using a dynamic viscoelasticity measuring device (DMA: manufactured by UBM Co., Ltd., trade name: E4000F) for a polyimide film having a size of 5 mm × 20 mm, at a heating rate of 4 ° C./min from 30 ° C. to 400 ° C., The measurement was performed at a frequency of 11 Hz, and the temperature at which the change in elastic modulus (tan δ) becomes the largest was made the glass transition temperature. In addition, the storage modulus at 30 ° C. measured using DMA is 1.0 × 10 ⁹ Pa or more, and the storage modulus in the temperature range within the glass transition temperature + 30 ° C. is less than 1.0 × 10 ⁸ Pa. “Thermoplastic”. And, the storage modulus at 30 ° C. is 1.0 × 10 ⁹ Pa or more, and the storage modulus in the temperature range within the glass transition temperature + 30 ° C. is 1.0 × 10 ⁸ Pa or more.

[Measurement of Coefficient of Thermal Expansion (CTE)]

A polyimide film having a size of 3 mm × 20 mm was heated from 30 ° C. to 265 ° C. at a constant heating rate while applying a load of 5.0 g using a thermomechanical analyzer (manufactured by Bruker, trade name: 4000SA), After holding at the temperature for another 10 minutes, it was cooled at a rate of 5°C/min, and the average coefficient of thermal expansion (coefficient of thermal expansion) from 250°C to 100°C was determined.

[Measurement of moisture absorptivity]

Two test pieces (width: 4 cm x length: 25 cm) of the polyimide film were prepared and dried at 80°C for 1 hour. Immediately after drying, it was placed in a constant temperature and constant humidity room at 23°C/50% RH, left still for 24 hours or more, and obtained from the weight change before and after that by the following formula.

Moisture absorptivity (% by weight) = [(weight after moisture absorption - weight after drying) / weight after drying] x 100

[Measurement of permittivity and dielectric loss tangent]

The permittivity and dielectric loss tangent of the polyimide film at a frequency of 10 GHz were measured using a vector network analyzer (manufactured by Agilent, trade name; E8363C) and a split post dielectric resonator (SPDR resonator). In addition, the material used for the measurement is temperature; 24-26°C, humidity; It is left to stand on 45 to 55% of conditions for 24 hours.

[Calculation of imide group concentration]

The value obtained by dividing the molecular weight of the imide group (-(CO) ₂ -N-) by the molecular weight of the entire polyimide structure was used as the imide group concentration.

[Measurement of Surface Roughness of Copper Foil]

The surface roughness of the copper foil was AFM (manufactured by Bruker AXS, trade name; Dimension Icon type SPM), probe (manufactured by Bruker AXS, trade name; TESPA (NCHV), tip curvature radius 10 nm, spring constant 42 N/ m) was used, in the tapping mode, the measurement was performed in the range of 80 μm × 80 μm on the surface of the copper foil, and the 10-point average roughness (Rzjis) was obtained.

[Measurement of Oxygen Permeability]

Oxygen gas permeability was measured under conditions of a temperature of 23°C±2°C and a humidity of 65% RH±5% RH in accordance with the differential pressure method of JIS K7126-1. In addition, as a vapor permeability measuring device, GTR-30XAD2 by GTR Tech and G2700T F by Yanako Technical Sciences were used.

[Measurement of Initial Peel Strength]

After the copper foil of the copper-clad laminate (copper foil/multilayer polyimide layer) is subjected to circuit processing to a width of 1 mm in the coating direction of the resin at intervals of 10 mm, width; 8 cm x length; Cut into 4 cm. The peel strength was measured using a Tensilon tester (manufactured by Toyo Seki Seisakusho, trade name: Strograph VE-1D), fixing the polyimide layer surface of the cut measurement sample to an aluminum plate with double-sided tape, and processing a circuit of copper The foil was peeled in the 180° direction at a rate of 50 mm/min, and the median strength when peeling 10 mm from the polyimide layer was obtained, and it was set as the initial peel strength.

[Measurement of peel strength after heating]

After the copper foil of the copper-clad laminate (copper foil/multilayer polyimide layer) is subjected to circuit processing to a width of 1 mm in the coating direction of the resin at intervals of 10 mm, width; 8 cm x length; Cut into 4 cm. The cut samples were stored in a hot air oven (under an atmospheric atmosphere) set at 150°C, and taken out after 1000 hours. The peel strength was measured using a Tensilon tester (manufactured by Toyo Seiki Seisakusho, trade name: Strograph VE-1D), fixing the polyimide layer surface of the taken measurement sample to an aluminum plate with double-sided tape, and circuit-processed copper The foil was peeled at a speed of 50 mm/min in the 180° direction, and the median strength when 10 mm was peeled from the polyimide layer was determined.

[Measurement of thickness of polyimide layer]

About the copper clad laminated board, the copper foil was etched away using the ferric chloride aqueous solution, and the polyimide film was obtained. The obtained polyimide film was cut into a rectangle, embedded in resin, and then cut in the thickness direction of the film with a microtome to prepare an ultrathin slice of about 100 nm. The produced ultra-thin slices were observed using the STEM function of an SEM (SU9000) manufactured by Hitachi High-Technology Co., Ltd. at an accelerating voltage of 30 kV, and the thickness of each polyimide layer was measured at 5 points, and the average value was calculated as It was set as the thickness of the mid layer.

The abbreviations used in Examples and Reference Examples represent the following compounds.

PMDA: pyromellitic dianhydride

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

m-TB: 2,2'-dimethyl-4,4'-diaminobiphenyl

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

TPE-Q: 1,4-bis(4-aminophenoxy)benzene

DAPE: 4,4'-diamino-diphenyl ether

PDA: paraphenylenediamine

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

Bisaniline-P: 1,4-bis[2-(4-aminophenyl)-2-propyl]benzene (manufactured by Mitsui Chemicals Fine Co., Ltd., trade name: Bisaniline-P)

DDA: Aliphatic diamine having 36 carbon atoms (manufactured by Croda Japan, trade name; PRIAMINE1074, amine value; 210 mgKOH/g, mixture of cyclic and chain structure dimer diamines, content of dimer components; 95% by weight or more)

DMAc: N,N-dimethylacetamide

(Synthesis Example 1)

Under a nitrogen stream, in a 300 ml separable flask, 12.061 g of m-TB (0.0568 mol), 0.923 g of TPE-Q (0.0032 mol) and 1.0874 g of bisaniline-P (0.0032 mol) and the solid concentration after polymerization were DMAc in an amount of 15% by weight was added, and dissolved by stirring at room temperature. Next, after adding 6.781 g of PMDA (0.0311 mol) and 9.147 g of BPDA (0.0311 mol), stirring was continued at room temperature for 3 hours to carry out a polymerization reaction, and polyamic acid solution a was obtained. The solution viscosity of the polyamic acid solution a was 29,800cps.

Next, on copper foil 1 (electrolytic copper foil, thickness; 12 μm, surface roughness Rzjis on the resin side; 2.1 μm), polyamic acid solution a was uniformly applied so that the thickness after curing was about 25 μm, The solvent was removed by heating and drying at 120°C. Further, stepwise heat treatment from 120°C to 360°C was performed within 30 minutes to complete imidization. About the obtained copper-clad laminated board, the copper foil was etched away using the ferric chloride aqueous solution, and the polyimide film a (non-thermoplastic, Tg; 316 degreeC, moisture absorption; 0.61 weight%) was prepared. In addition, the imide group concentration of the polyimide constituting the polyimide film a was 31.6% by weight.

(Synthesis Example 2)

Under a nitrogen stream, in a 300 ml separable flask, 11.825 g of m-TB (0.0557 mol), 0.905 g of TPE-Q (0.0031 mol), and 1.653 g of DDA (0.0031 mol), and the solid content concentration after polymerization was 15% by weight. An amount of DMAc was added and dissolved by stirring at room temperature. Next, after adding 6.649 g of PMDA (0.0305 mol) and 8.968 g of BPDA (0.0305 mol), a polymerization reaction was performed by continuing stirring at room temperature for 3 hours to obtain a polyamic acid solution b. The solution viscosity of the polyamic acid solution b was 27,800cps.

Next, on the copper foil 1, the polyamic acid solution b was uniformly applied so that the thickness after curing was about 25 µm, and then the solvent was removed by heating and drying at 120°C. Further, stepwise heat treatment from 120°C to 360°C was performed within 30 minutes to complete imidization. About the obtained copper-clad laminated board, the copper foil was etched away using the ferric chloride aqueous solution, and the polyimide film b (non-thermoplastic, Tg; 258 degreeC, moisture absorption; 0.54 weight%) was prepared. In addition, the imide group concentration of the polyimide constituting the polyimide film b was 30.9% by weight.

(Synthesis Example 3)

In a 300 ml separable flask under a nitrogen stream, 11.920 g of m-TB (0.0562 mol) and 2.897 g of TPE-Q (0.0099 mol) and DMAc in an amount such that the solid content concentration after polymerization is 15% by weight were charged, Stir at room temperature to dissolve. Next, after adding 11.354 g of PMDA (0.0521 mol) and 3.829 g of BPDA (0.0130 mol), stirring was continued at room temperature for 3 hours to carry out a polymerization reaction to obtain a polyamic acid solution c. The solution viscosity of the polyamic acid solution c was 31,200cps.

Next, the polyamic acid solution c was uniformly applied on the copper foil 1 so that the thickness after curing was about 25 µm, and then the solvent was removed by heating and drying at 120°C. Further, stepwise heat treatment from 120°C to 360°C was performed within 30 minutes to complete imidation. About the obtained copper clad laminated board, the copper foil was etched away using the ferric chloride aqueous solution, and the polyimide film c (non-thermoplastic, Tg; 375 degreeC, moisture absorption; 0.81 weight%) was prepared. In addition, the imide group concentration of the polyimide constituting the polyimide film c was 33.2% by weight.

(Synthesis Example 4)

In a 300 ml separable flask under a nitrogen stream, 1.548 g of PDA (0.0143 mol) and 11.465 g of DAPE (0.0573 mol) and DMAc in an amount such that the solid concentration after polymerization is 15% by weight were added, and stirred at room temperature. dissolved Next, after adding 10.764 g of PMDA (0.0494 mol) and 6.223 g of BPDA (0.0212 mol), stirring was continued at room temperature for 3 hours to carry out a polymerization reaction, and polyamic acid solution d was obtained. The solution viscosity of the polyamic acid solution d was 23,500cps.

Next, the polyamic acid solution d was cast from the slit of the T-die mold to a thickness of 25 μm after curing, and extruded onto a smooth belt-shaped metal support in a drying furnace to form a thin film, followed by drying at 130° C. for a predetermined time After heating, it was peeled off from the support to obtain a self-supporting film. Further, both ends of this self-supporting film in the width direction are gripped and inserted into a continuous heating furnace, and the film is heated and imidized under the condition that the maximum heating temperature is 380 ° C. from 100 ° C. Thermoplastic, Tg; >400°C, moisture absorption; 1.14% by weight) was prepared. In addition, the imide group concentration of the polyimide constituting the polyimide film d was 36.2% by weight.

(Synthesis Example 5)

Into a 300 ml separable flask under a nitrogen stream, 15.591 g of BAPP (0.0380 mol) and DMAc in an amount such that the solid content concentration after polymerization is 12% by weight were charged, and stirred at room temperature to dissolve. Next, after adding 8.409 g of PMDA (0.0386 mol), stirring was continued at room temperature for 3 hours to carry out a polymerization reaction, thereby obtaining a polyamic acid solution e. The solution viscosity of the polyamic acid solution e was 2,350cps.

Next, the polyamic acid solution e was uniformly applied on the copper foil 1 so that the thickness after curing was about 10 µm, and then the solvent was removed by heating and drying at 120°C. Further, stepwise heat treatment from 120°C to 360°C was performed within 30 minutes to complete imidization. About the obtained copper clad laminated board, the copper foil was etched away using the ferric chloride aqueous solution, and the polyimide film e (thermoplasticity, Tg; 320 degreeC, moisture absorption rate; 0.55 weight%) was prepared. In addition, the imide group concentration of the polyimide constituting the polyimide film e was 23.6% by weight.

(Synthesis Example 6)

In a 300 ml separable flask under a nitrogen stream, 1.847 g of m-TB (0.0087 mol) and 10.172 g of TPE-R (0.0348 mol) and DMAc in an amount such that the solid content concentration after polymerization is 12% by weight were charged, Stir at room temperature to dissolve. Next, after adding 2.889 g of PMDA (0.0132 mol) and 9.092 g of BPDA (0.0309 mol), stirring was continued at room temperature for 3 hours to carry out a polymerization reaction, thereby obtaining a polyamic acid solution f. The solution viscosity of the polyamic acid solution f was 2,210cps.

Next, the polyamic acid solution f was uniformly applied on the copper foil 1 so that the thickness after curing was about 10 µm, and then the solvent was removed by heating and drying at 120°C. Further, stepwise heat treatment from 120°C to 360°C was performed within 30 minutes to complete imidation. About the obtained copper clad laminated board, the copper foil was etched away using the ferric chloride aqueous solution, and the polyimide film f (thermoplasticity, Tg; 226 degreeC, moisture absorption rate; 0.41 weight%) was prepared. In addition, the imide group concentration of the polyimide constituting the polyimide film f was 27.4% by weight.

[Example 1]

On copper foil 2 (electrolytic copper foil, thickness: 12 μm, surface roughness Rzjis on the resin side; 0.6 μm), the polyamic acid solution f was uniformly applied so that the thickness after curing was 2.5 μm, and then held at 120° C. for 1 minute. The solvent was removed by heating and drying. The polyamic acid solution a was uniformly applied thereon so that the thickness after curing was 25 μm, and then heated and dried at 120° C. for 3 minutes to remove the solvent. Further, polyamic acid f was uniformly applied thereon so that the thickness after curing was 2.5 μm, and then heated and dried at 120° C. for 1 minute to remove the solvent. Thereafter, stepwise heat treatment was performed from 140°C to 360°C, imidization was completed, and copper clad laminate 1 was prepared.

It was 1.06 kN/m and 0.69 kN/m, respectively, as a result of measuring the initial peeling strength and the peeling strength after heating using obtained copper clad laminated board 1. Each measurement result is shown in Table 1.

With respect to the copper clad laminated board 1, the copper foil was etched away using the ferric chloride aqueous solution, and the polyimide film 1a was obtained. About the obtained polyimide film 1a, as a result of evaluating CTE, dielectric characteristics, and oxygen permeability, CTE; 22 ppm/K, permittivity; 3.56, dielectric loss tangent; 0.0032, oxygen permeability; It was 4.59×10 ^-14 mol/(m 2·s·Pa). Each measurement result is shown in Table 2.

[Examples 2 to 4, Comparative Example 1 and Reference Examples 1 to 2]

Copper-clad laminates 2 to 4 of Examples 2 to 4, Comparative Examples 1 and Reference Examples 1 to 2 in the same manner as in Example 1, except that the polyamic acid solution described in Table 1 was used and the thickness configuration was changed. , Copper-clad laminates 5 and copper-clad laminates 6 to 7, polyimide films 2a to 4a, polyimide films 5a, and polyimide films 6a to 7a were obtained. Each measurement result is shown in Table 1 and Table 2.

Comparative Example 2

The polyamic acid solution d was cast from the slit of the T-die mold to a thickness of 30 μm after curing, and extruded onto a smooth belt-shaped metal support in a drying furnace to form a thin film, heated at 130 ° C. for a predetermined time, It was peeled off from the support to obtain a self-supporting film. Further, while continuously transporting the self-supporting film, the polyamic acid solution e was applied to the atmospheric surface of the self-supporting film using a die coater to a thickness of 2.5 μm after curing, and dried in a drying oven at 120° C. for a predetermined time. . Subsequently, the polyamic acid solution e was applied to the surface opposite to the coated surface in the same manner as above to a thickness of 2.5 μm after curing, and dried in a drying oven at 120° C. for a predetermined time.

Both ends of this self-supporting film in the width direction were held and inserted into a continuous heating furnace, and the film was imidized by heating under the condition that the highest heating temperature was 380°C from 100°C, thereby obtaining a polyimide film 8b. A copper foil was superimposed on one side of the polyimide film 8b and a Teflon (registered trademark) film was superimposed on the other side, and the polyimide film 8b was thermally compressed for 15 minutes under conditions of a temperature of 320°C and a pressure of 340 MPa. After compression, the Teflon (registered trademark) film was formed. The copper clad laminated board 8 was prepared by peeling.

It was 1.15 kN/m and 1.01 kN/m, respectively, when the initial peel strength and the peel strength after heating were measured using the obtained copper clad laminated board 8.

About the copper clad laminated board 8, it carried out similarly to Example 1, and the copper foil was removed by etching, and the polyimide film 8a was obtained. About the obtained polyimide film 8a, the CTE, the dielectric property, and the oxygen permeability were evaluated, and as a result, CTE; 22 ppm/K, permittivity; 3.65, dielectric loss tangent; 0.0073, oxygen permeability; It was 1.17×10 ^-14 mol/(m 2·s·Pa).

As mentioned above, although the embodiment of the present invention has been described in detail for the purpose of illustration, the present invention is not limited to the above embodiment, and various modifications are possible.

100, 101: polyimide film
110: non-thermoplastic polyimide layer
120A, 120B: thermoplastic polyimide layer

Claims (4)

A polyimide film having a non-thermoplastic polyimide layer containing non-thermoplastic polyimide and a thermoplastic polyimide layer containing thermoplastic polyimide laminated on at least one surface of the non-thermoplastic polyimide layer,
the following conditions (i) to (vi);
(i) having a coefficient of thermal expansion in the range of 10 to 30 ppm/K;
(ii) those with an oxygen permeability of 4.39×10 ^-14 mol/(m 2·s·Pa) or less;
(iii) The proportion of monomer residues having a biphenyl skeleton calculated by the following formula (1) relative to all monomer residues derived from the non-thermoplastic polyimide and all monomer components constituting the thermoplastic polyimide is 50 mol% more than;
(iv) Of all the monomer residues derived from all the monomer components in the thermoplastic polyimide, the proportion of the monomer residue having a biphenyl skeleton is 30 mol% or more;
(v) that the total thickness of the polyimide film is in the range of 35 to 50 μm;
(vi) the thermoplastic polyimide has an imide group concentration of 30% by weight or less and a glass transition temperature within the range of 200°C or more and 350°C or less;
A polyimide film characterized in that it meets.

[In formula (1), M _i is the ratio (unit _; The polyimide film according to claim 1, wherein the ratio T2/T1 of the total thickness T2 of the thermoplastic polyimide layer to the total thickness T1 of the polyimide film is 0.17 or less. A metal clad laminate comprising an insulating resin layer and a metal layer provided on at least one surface of the insulating resin layer,
The insulating resin layer has a thermoplastic polyimide layer in contact with the surface of the metal layer and a non-thermoplastic polyimide layer laminated indirectly, and includes the polyimide film according to claim 1. A metal-clad laminate characterized in that . A circuit board provided with an insulating resin layer and a wiring layer provided on at least one surface of the insulating resin layer,
A circuit board characterized in that the insulating resin layer includes the polyimide film according to claim 1 while having a thermoplastic polyimide layer in contact with the wiring layer and an indirectly laminated non-thermoplastic polyimide layer.