JP2023149765A - Polyamide acid, polyimide, metal-clad laminate board, and circuit board - Google Patents

Abstract

To provide a polyimide excellent in heat dissipation property (thermal conductivity), resilience and toughness, and heat resistance.SOLUTION: A polyamide acid and a polyimide include: an acid anhydride residue derived from an acid anhydride constituent of formula (1); and a diamine residue derived from a diamine constituent, where there are included 50 mol% or more of an acid anhydride residue derived from formula (1) to total acid anhydride residues, and 50 mol% or more of a diamine residue derived from a benzanilide derivative to total diamine residues.SELECTED DRAWING: None

Description

The present invention relates to a polyamic acid, a polyimide obtained by imidizing the polyamic acid, and a metal-clad laminate and a circuit board using a layer of the polyimide.

In recent years, as electronic devices have become smaller, lighter, and space-saving, flexible printed circuit boards (FPCs) have become thinner, lighter, more flexible, and have excellent durability even after repeated bending. Demand for circuits is increasing. FPC can be mounted three-dimensionally and with high density even in a limited space, so its use is expanding, for example, for wiring of movable parts of electronic devices such as HDDs, DVDs, and smartphones, and parts such as cables and connectors. It is being done. Most FPCs are manufactured by forming a circuit on the metal layer of a metal-clad laminate, which is made by laminating a metal layer using metal foil or the like and an insulating resin base material (insulating resin layer).

Furthermore, in recent years, with the miniaturization of electronic devices and the increase in the amount of information processing, the degree of integration of circuits has increased, and the heat generated from the mounted components is expected to increase. In order to improve efficiency and reliability, it is required to improve the heat dissipation characteristics of the heat generated within the equipment. In order to improve heat dissipation inside equipment, conventional methods have been used to install thick aluminum plates with high thermal conductivity, cooling fans, etc., but due to the demand for smaller equipment, such equipment may not be possible.

Furthermore, in order to improve heat dissipation, it is considered effective to increase the thermal conductivity of the electronic device itself. For example, a technique is being considered in which a thermally conductive filler is contained in an insulating resin layer that constitutes a wiring board. More specifically, it is being considered to disperse and blend fillers with high thermal conductivity such as aluminum oxide, boron nitride, aluminum nitride, and silicon nitride into the resin that forms the insulating resin layer. Techniques have been reported in which a thermally conductive filler is blended into polyimide having high properties (for example, Patent Documents 1 to 7). Furthermore, it is also being considered to improve heat dissipation in the thickness direction by making the electronic device (insulating resin layer) itself thinner.

Patent No. 5235211 Patent No. 5442491 Patent No. 5297740 Patent No. 5665449 Patent No. 5330396 Patent No. 5665846 Patent No. 5650084

However, when the filling rate of thermally conductive filler in the resin is increased, the content of the resin component is relatively reduced, which tends to reduce the flexibility and toughness of the cured resin, and the circuit during FPC processing tends to decrease. There is a risk that the single film portion after pattern formation may be torn. Moreover, it is assumed that this will become more noticeable when the insulating resin layer is made thinner.

On the other hand, when a resin component having a functional group with relatively good flexibility and toughness is used as the resin component in the insulating resin layer, there is a tendency for the heat resistance to decrease.

As described above, although there is a demand for improved heat dissipation within electronic devices, conventional technology has not been able to satisfy all of the heat dissipation properties (thermal conductivity), flexibility/toughness, and heat resistance of the insulating resin layer that constitutes the wiring board. There was room for improvement.

Therefore, as a result of intensive study by the inventors of the present application, in using a polyimide layer as an insulating resin layer constituting a wiring board, in addition to using specific compounds as the acid anhydride component and diamine component that constitute the polyimide, The present invention was completed based on the finding that it is effective to adjust their content within a predetermined range.

Therefore, an object of the present invention is to provide a polyamic acid that provides a polyimide layer with excellent heat dissipation (thermal conductivity), flexibility, toughness, and heat resistance.
Another object of the present invention is to provide a metal-clad laminate and a circuit board in which insulating resin layers having the polyimide layer are laminated.

［式（２）中、Ｒは独立に、ハロゲン原子であるか、ハロゲン原子で置換されてもよい炭素数１～６のアルキル基若しくはアルコキシ基であるか、又は炭素数１～６の１価の炭化水素基若しくはアルコキシ基で置換されてもよいフェニル基若しくはフェノキシ基を示す。ｍ、ｎはそれぞれ独立して置換数を示し、ｍは０～４の整数、ｎは０～４の整数を示す。］
［２］下記一般式（３）で表されるジアミン成分から誘導されるジアミン残基を１０モル％～５０モル％を含有することを特徴とする［１］に記載のポリアミド酸。

［式（３）中、Ｚは－Ｏ－を示す。Ｒは独立に、ハロゲン原子であるか、ハロゲン原子で置換されてもよい炭素数１～６のアルキル基若しくはアルコキシ基であるか、又は炭素数１～６の１価の炭化水素基若しくはアルコキシ基で置換されてもよいフェニル基若しくはフェノキシ基を示す。ｎ_１は置換数を示し、０～４の整数である。ｎ_２は０～３の整数を示す。］
［３］［１］又は［２］に記載のポリアミド酸がイミド化されてなる、ポリイミド。
［４］下記ａ）及びｂ）；
ａ）２０ｍｍ幅で測定した端裂抵抗が３０Ｎ以上５００Ｎ以下の範囲内であること、
ｂ）厚み方向における熱伝導率（λｚ）が、０．２０Ｗ／ｍ・Ｋ以上の範囲内であること、
を満たす［３］に記載のポリイミド。
［５］更に、下記の条件ｃ）；
ｃ)厚み方向における熱拡散率（α）が、０．１００m²/s以上の範囲内であること、
を満たす［４］に記載のポリイミド。
［６］更に、下記の条件ｄ）；
ｄ）ガラス転移温度が２５０℃以上であること、
を満たすことを特徴とする［４］又は［５］に記載のポリイミド。
［７］更に、下記の条件ｅ）；
ｅ）引き裂き伝播抵抗が１．５ｋＮ／ｍであること、
を満たすことを特徴とする［４］～［６］のいずれかに記載のポリイミド。
［８］更に、下記の条件ｆ）；
ｆ）熱膨張係数が５０ｐｐｍ／Ｋ以下であること、
を満たすことを特徴とする［４］～［７］のいずれかに記載のポリイミド。
［９］単層又は複数層からなる絶縁樹脂層と、前記絶縁樹脂層の片側又は両側に積層されている金属層と、を備えた金属張積層板であって、
前記絶縁樹脂層の少なくとも１層が、［３］～［８］のいずれか１項に記載のポリイミドの層によって構成されていることを特徴とする金属張積層板。
［１０］単層又は複数層からなる絶縁樹脂層と、前記絶縁樹脂層の片側又は両側に積層されている導体回路層と、を備えた回路基板であって、
前記絶縁樹脂層の少なくとも１層が、［３］～［８］のいずれか１項に記載のポリイミドの層によって構成されている回路基板。 That is, the present invention is as follows.
[1] An acid anhydride residue derived from an acid anhydride component represented by the following general formula (1),
Contains a diamine residue derived from a diamine component represented by general formula (2),
Contains 50 mol% or more of acid anhydride residues derived from the acid anhydride component represented by the following general formula (1) based on the total acid anhydride residues,
A polyamic acid characterized by containing 50 mol% or more of diamine residues derived from a diamine component represented by the following general formula (2) based on all diamine residues.

[In formula (2), R is independently a halogen atom, an alkyl group or alkoxy group having 1 to 6 carbon atoms which may be substituted with a halogen atom, or a monovalent group having 1 to 6 carbon atoms] represents a phenyl group or phenoxy group which may be substituted with a hydrocarbon group or an alkoxy group. m and n each independently represent the number of substitutions, m represents an integer of 0 to 4, and n represents an integer of 0 to 4. ]
[2] The polyamic acid according to [1], which contains 10 mol% to 50 mol% of a diamine residue derived from a diamine component represented by the following general formula (3).

[In formula (3), Z represents -O-. R is independently a halogen atom, an alkyl group or alkoxy group having 1 to 6 carbon atoms which may be substituted with a halogen atom, or a monovalent hydrocarbon group having 1 to 6 carbon atoms or an alkoxy group represents a phenyl group or phenoxy group which may be substituted with n ₁ indicates the number of substitutions and is an integer from 0 to 4. n ₂ represents an integer from 0 to 3. ]
[3] A polyimide obtained by imidizing the polyamic acid according to [1] or [2].
[4] Below a) and b);
a) The end tear resistance measured at a width of 20 mm is within the range of 30 N or more and 500 N or less,
b) The thermal conductivity (λz) in the thickness direction is within the range of 0.20 W/m K or more,
The polyimide according to [3], which satisfies the following.
[5] Furthermore, the following condition c);
c) The thermal diffusivity (α) in the thickness direction is within the range of 0.100 m ² /s or more,
The polyimide according to [4], which satisfies the following.
[6] Furthermore, the following condition d);
d) The glass transition temperature is 250°C or higher,
The polyimide according to [4] or [5], which satisfies the following.
[7] Furthermore, the following condition e);
e) tear propagation resistance is 1.5 kN/m;
The polyimide according to any one of [4] to [6], which satisfies the following.
[8] Furthermore, the following condition f);
f) The coefficient of thermal expansion is 50 ppm/K or less;
The polyimide according to any one of [4] to [7], which satisfies the following.
[9] A metal-clad laminate comprising an insulating resin layer consisting of a single layer or multiple layers, and a metal layer laminated on one or both sides of the insulating resin layer,
A metal-clad laminate, wherein at least one of the insulating resin layers is composed of a polyimide layer according to any one of [3] to [8].
[10] A circuit board comprising an insulating resin layer consisting of a single layer or multiple layers, and a conductor circuit layer laminated on one side or both sides of the insulating resin layer,
A circuit board in which at least one layer of the insulating resin layer is constituted by a polyimide layer according to any one of [3] to [8].

According to the present invention, a polyimide having excellent heat dissipation properties (thermal conductivity), flexibility/toughness, and heat resistance can be obtained.

Embodiments of the present invention will be described below.

<Polyamic acid, polyimide>
The polyamic acid of the present invention is a precursor of polyimide, and has an acid anhydride residue which is a tetravalent group derived from a tetracarboxylic dianhydride (hereinafter sometimes simply referred to as "acid anhydride") component. and a diamine residue, which is a divalent group derived from a diamine compound (hereinafter sometimes simply referred to as "diamine") component, and these components are linked together to form one repeat. When viewed as a unit, it is composed of a polymer of repeating units. The composition can be controlled by adjusting the amount (molar ratio) of the acid anhydride component and the diamine component.

For example, polyamic acid is usually produced by dissolving a predetermined acid anhydride component and a diamine component in approximately equal moles in an organic solvent, and stirring the mixture at a temperature usually in the range of 0 to 100°C for 30 minutes to 24 hours to cause a polymerization reaction. It can be obtained with In the reaction, the reaction components are dissolved in the organic solvent so that the amount of 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. Examples of organic solvents used in the polymerization reaction include N,N-dimethylformamide, N,N-dimethylacetamide (DMAC), N-methyl-2-pyrrolidone, 2-butanone, dimethylsulfoxide, dimethyl sulfate, cyclohexanone, dioxane, Examples include tetrahydrofuran, diglyme, triglyme, and γ-butyrolactone. Two or more of these solvents can be used in combination, and aromatic hydrocarbons such as xylene and toluene can also be used in combination.

In the synthesis of polyamic acid and polyimide, each of the acid anhydride component and the diamine component may be used alone or in combination of two or more thereof. By selecting the type of acid anhydride component and diamine component and the molar ratio of each when using two or more types of acid anhydride or diamine, for example, thermal conductivity, thermal expansion property, adhesiveness, glass transition, etc. Physical properties such as temperature, tear propagation resistance, end tear resistance, and tensile elongation can be controlled.

Furthermore, a terminal capping agent may be used for the polyamic acid and polyimide of the present invention. As the terminal capping agent, monoamines or dicarboxylic acids are preferable. The amount of the terminal capping agent to be introduced is preferably in the range of 0.0001 mol or more and 0.1 mol or less, particularly 0.001 mol or more and 0.05 mol or less, per 1 mol of the acid anhydride component. Preferably within this range. Examples of monoamine terminal capping agents include methylamine, ethylamine, propylamine, butylamine, benzylamine, 4-methylbenzylamine, 4-ethylbenzylamine, 4-dodecylbenzylamine, 3-methylbenzylamine, aniline, 4-Methylaniline etc. are recommended. Among these, benzylamine and aniline can be preferably used. As the dicarboxylic acid terminal capping agent, dicarboxylic acids are preferred, and a portion thereof may be ring-closed. For example, phthalic acid, phthalic anhydride, 4-chlorophthalic acid, tetrafluorophthalic acid, cyclopentane-1,2-dicarboxylic acid, 4-cyclohexene-1,2-dicarboxylic acid, etc. are recommended. Among these, phthalic acid and phthalic anhydride can be preferably used.

It is usually advantageous to use the synthesized polyamic acid as a reaction solvent solution, but it can be concentrated, diluted, or replaced with another organic solvent if necessary. In addition, polyamic acids generally have excellent solvent solubility, so they are advantageously used. The method of imidizing the polyamic acid is not particularly limited, and for example, heat treatment such as heating in the above solvent at a temperature in the range of 80° C. or higher and 400° C. or lower for 1 hour to 24 hours is preferably employed. .

Furthermore, although the polyamic acid is not limited, it is preferable that the viscosity is in the range of 1,000 to 200,000 cP by adjusting the concentration and weight average molecular weight Mw. If the viscosity is high, it may be diluted by adding a solvent. The weight average molecular weight Mw of the polyamic acid is preferably in the range of 10,000 or more and 500,000 or less, and more preferably in the range of 50,000 or more and 500,000 or less. When the weight average molecular weight is less than 10,000, the strength of the film decreases and tends to become brittle. On the other hand, if the weight average molecular weight exceeds 500,000, the viscosity increases excessively and defects such as uneven film thickness and streaks tend to occur during coating operations.

(Acid anhydride component)
Here, as the acid anhydride component used in the polyamic acid and polyimide of the present invention, an acid anhydride represented by the following general formula (1) is essential.

The acid anhydride represented by formula (1) has a rigid structure in which aromatic rings are connected by direct bonds (single bonds), and has a biphenyl structure, giving it high heat resistance and high thermal conductivity. It becomes possible to do so. Examples of the acid anhydride component include 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA), 2,2',3,3'-biphenyltetracarboxylic dianhydride, 2 , 3,3',4'-biphenyltetracarboxylic dianhydride, but are not limited thereto. Preferably it is BPDA.

In the polyamic acid and polyimide of the present invention, the acid anhydride represented by the formula (1) is contained in an amount of 50 mol% or more based on a total of 100 mol% of all acid anhydride components. That is, the acid anhydride residue derived from this acid anhydride is set to be 50 mol % or more with respect to 100 mol % of the total acid anhydride residue of the polyamic acid and polyimide to be synthesized. If the acid anhydride component (acid anhydride residue) of formula (1) is less than 50 mol%, there is a risk that sufficient heat resistance and thermal conductivity may not be obtained in the polyimide synthesized using the acid anhydride component (acid anhydride residue). . Preferably it is 75 mol% or more, more preferably 90 mol% or more, and still more preferably 100 mol%.

Further, as acid anhydride components other than those mentioned above, known ones used in the production of polyamic acid and polyimide can be used without limitation, but aromatic tetracarboxylic dianhydride is preferable. Furthermore, anhydrides of tetracarboxylic acids having an aliphatic skeleton may be used, for example, aliphatic chain anhydrides such as ethylenetetracarboxylic dianhydride and 1,2,3,4-butanetetracarboxylic dianhydride. Tetracarboxylic dianhydride or anhydride of alicyclic tetracarboxylic acid may be used, for example, 1,2,3,4-cyclobutanetetracarboxylic dianhydride, fluorenylidene bisphthalic anhydride, 1 , 2,4,5-cyclohexanetetracarboxylic dianhydride, alicyclic tetracarboxylic dianhydride such as cyclopentanone bisspironorbornane tetracarboxylic dianhydride, and the like. Examples of the aromatic tetracarboxylic dianhydride include 3,3',4,4'-benzophenonetetracarboxylic dianhydride, 2,3',3,4'-benzophenonetetracarboxylic dianhydride, 2 , 2',3,3'-benzophenonetetracarboxylic dianhydride, 4,4'-(paraphenylene dicarbonyl) diphthalic anhydride, 4,4'-(metaphenylene dicarbonyl) diphthalic anhydride, pyro Mellitic dianhydride (PMDA), p-phenylene bis(trimellitate anhydride), 4,4'-oxydiphthalic dianhydride (ODPA), bis(2,3-dicarboxyphenyl)ether dianhydride, 5, 5'-bis(trifluoromethyl)-3,3',4,4'-tetracarboxydiphenyl ether dianhydride, bis{(trifluoromethyl)dicarboxyphenoxy}diphenyl ether dianhydride, bis{3,5-dianhydride (trifluoromethyl)phenoxy}pyromellitic dianhydride, bis{(trifluoromethyl)dicarboxyphenoxy}benzene dianhydride, bis{(trifluoromethyl)dicarboxyphenoxy}, bis(dicarboxyphenoxy)trifluoro Methylbenzene dianhydride, bis(dicarboxyphenoxy)bis(trifluoromethyl)benzene dianhydride, bis(dicarboxyphenoxy)tetrakis(trifluoromethyl)benzene dianhydride, 2,2-bis{(4-( 3,4-dicarboxyphenoxy)phenyl}hexafluoropropane dianhydride, bis{(trifluoromethyl)dicarboxyphenoxy}biphenyl dianhydride, bis{(trifluoromethyl)dicarboxyphenoxy}bis(trifluoromethyl) biphenyl dianhydride, bis(dicarboxyphenoxy)bis(trifluoromethyl)biphenyl dianhydride, 2,2'-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride, naphthalene-2,3, 6,7-tetracarboxylic dianhydride, naphthalene-1,2,5,6-tetracarboxylic dianhydride, naphthalene-1,2,6,7-tetracarboxylic dianhydride, naphthalene-1,2 , 4,5-tetracarboxylic dianhydride, naphthalene-1,4,5,8-tetracarboxylic dianhydride, 2,6-dichloronaphthalene-1,4,5,8-tetracarboxylic dianhydride , 2,7-dichloronaphthalene-1,4,5,8-tetracarboxylic dianhydride, 2,3,6,7-tetrachloronaphthalene-1,4,5,8-tetracarboxylic dianhydride, 1,4,5,8-tetrachloronaphthalene-2,3,6,7-tetracarboxylic dianhydride, 3,3'',4,4''-p-terphenyltetracarboxylic dianhydride, 2,2'',3,3''-p-terphenyltetracarboxylic dianhydride, 2,3,3'',4''-p-terphenyltetracarboxylic dianhydride, 2,2- Bis(2,3-dicarboxyphenyl)-propane dianhydride, 2,2-bis(3,4-dicarboxyphenyl)-propane dianhydride, bis(2,3-dicarboxyphenyl)methane dianhydride , bis(3,4-dicarboxyphenyl)methane dianhydride, 1,1-bis(2,3-dicarboxyphenyl)ethane dianhydride, 1,1-bis(3,4-dicarboxyphenyl)ethane Dianhydride, 3,3',4,4'-diphenylsulfonetetracarboxylic dianhydride, 2,2',3,3'-diphenylsulfonetetracarboxylic dianhydride, 2,3,3',4 '-Diphenylsulfonetetracarboxylic dianhydride, thiophene-2,3,4,5-tetracarboxylic dianhydride, perylene-2,3,8,9-tetracarboxylic dianhydride, perylene-3,4 , 9,10-tetracarboxylic dianhydride, perylene-4,5,10,11-tetracarboxylic dianhydride, perylene-5,6,11,12-tetracarboxylic dianhydride, phenanthrene-1, 2,7,8-tetracarboxylic dianhydride, phenanthrene-1,2,6,7-tetracarboxylic dianhydride, phenanthrene-1,2,9,10-tetracarboxylic dianhydride, pyrazine-2 , 3,5,6-tetracarboxylic dianhydride, pyrrolidine-2,3,4,5-tetracarboxylic dianhydride, (trifluoromethyl)pyromellitic dianhydride, di(trifluoromethyl)pyro Mellitic dianhydride, di(heptafluoropropyl)pyromellitic dianhydride, pentafluoroethylpyromellitic dianhydride, 2,2-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride, 5,5'-bis(trifluoromethyl)-3,3',4,4'-tetracarboxybiphenyl dianhydride, 2,2',5,5'-tetrakis(trifluoromethyl)-3,3' , 4,4'-tetracarboxybiphenyl dianhydride, 5,5'-bis(trifluoromethyl)-3,3',4,4'-tetracarboxybenzophenone dianhydride, trifluoromethylbenzene dianhydride, etc. can be mentioned.

［式（２）中、Ｒは独立に、ハロゲン原子であるか、ハロゲン原子で置換されてもよい炭素数１～６のアルキル基若しくはアルコキシ基であるか、又は炭素数１～６の１価の炭化水素基若しくはアルコキシ基で置換されてもよいフェニル基若しくはフェノキシ基を示す。ｍ、ｎはそれぞれ独立して置換数を示し、ｍは０～４の整数、ｎは０～４の整数を示す。なお、ｍ＝０又はｎ＝０は、それぞれＲを有さない（無置換、側鎖を有さない）ことを意味する。］ (Diamine component)
As the diamine component used in the polyamic acid and polyimide of the present invention, a diamine represented by the following general formula (2) is essential.

[In formula (2), R is independently a halogen atom, an alkyl group or alkoxy group having 1 to 6 carbon atoms which may be substituted with a halogen atom, or a monovalent group having 1 to 6 carbon atoms] represents a phenyl group or phenoxy group which may be substituted with a hydrocarbon group or an alkoxy group. m and n each independently represent the number of substitutions, m represents an integer of 0 to 4, and n represents an integer of 0 to 4. In addition, m=0 or n=0 means that each does not have R (no substitution, no side chain). ]

The diamine represented by formula (2) has a rigid structure in which aromatic rings are connected by amide bonds, and intermolecular interactions (such as hydrogen bonds) between oxygen atoms (O) and hydrogen atoms (H). ), it is possible to impart high heat resistance and high thermal conductivity. Examples of the diamine component include 4,4'-diaminobenzanilide (DABA), 4,4'-diamino-2'-methoxybenzanilide (MABA), and 3,5-diamino-3'-trifluoromethylbenzanilide. Examples include anilide, 3,5-diamino-4'-trifluoromethylbenzanilide, and the like. DABA is preferred because of its high heat resistance and high thermal conductivity.

In the polyamic acid and polyimide of the present invention, the diamine represented by the formula (2) is contained in an amount of 50 mol% or more based on a total of 100 mol% of all diamine components. That is, the amount of diamine residues derived from this diamine is set to be 50 mol % or more based on 100 mol % of all diamine residues in the polyamic acid and polyimide to be synthesized. If the diamine component (diamine residue) of formula (2) is less than 50 mol%, there is a possibility that sufficient heat resistance and thermal conductivity may not be obtained in the polyimide synthesized using the diamine component (diamine residue). For heat resistance and thermal conductivity, the content is preferably 75 mol% or more, more preferably 90 mol% or more, and even more preferably 100 mol%.

［式（３）中、Ｚは－Ｏ－を示す。Ｒは独立に、ハロゲン原子であるか、ハロゲン原子で置換されてもよい炭素数１～６のアルキル基若しくはアルコキシ基であるか、又は炭素数１～６の１価の炭化水素基若しくはアルコキシ基で置換されてもよいフェニル基若しくはフェノキシ基を示す。ｎ_１は置換数を示し、０～４の整数である。ｎ_２は０～３の整数を示す。なお、ｎ_１＝０又はｎ_２＝０は、それぞれＲを有さない（無置換、側鎖を有さない）ことを意味する。］ Moreover, in the polyamic acid and polyimide of the present invention, in addition to the diamine component (diamine residue) of the above formula (2), it is preferable to use a diamine component represented by the following general formula (3).

[In formula (3), Z represents -O-. R is independently a halogen atom, an alkyl group or alkoxy group having 1 to 6 carbon atoms which may be substituted with a halogen atom, or a monovalent hydrocarbon group having 1 to 6 carbon atoms or an alkoxy group represents a phenyl group or phenoxy group which may be substituted with n ₁ indicates the number of substitutions and is an integer from 0 to 4. n ₂ represents an integer from 0 to 3. Note that n ₁ =0 or n ₂ =0 means that each does not have R (no substitution, no side chain). ]

The aromatic diamine compound represented by the above formula (3) has two or more aromatic rings, and has an ether bond, which is a divalent linking group Z, so that the polyimide molecular chain synthesized using this It is thought that this increases the degree of freedom and imparts flexibility, which contributes to improving the flexibility of polyimide molecular chains and promotes higher toughness. By using the diamine component (diamine residue) of formula (3) together with the diamine component (diamine residue) of formula (2) above, a rigid molecular chain according to formula (2) and a rigid molecular chain according to formula (3) can be formed. It is assumed that the effect of structural entanglement with flexible molecular chains is created, and that the occurrence of intermolecular interactions (hydrogen bonds, etc.) between oxygen atoms (O) and hydrogen atoms (H) becomes stronger, resulting in improved heat resistance. - While maintaining relatively high thermal conductivity, toughness (tear propagation resistance, end tear resistance) can also be improved, which is preferable because these properties can be achieved at the same time.

From the viewpoint of achieving both the above-mentioned properties, the diamine component (diamine residue) represented by formula (3) is contained in an amount of 10 to 50 mol % with respect to the total 100 mol % of all diamine components (diamine residue). In order to impart high toughness, the content is preferably 30 to 50 mol%, and even more preferably 40 to 50 mol%. Considering the balance of properties such as heat resistance, thermal conductivity, and toughness, the contents of the diamine component (diamine residue) of the above formula (2) and the diamine component (diamine residue) of this formula (3) are adjusted as appropriate. Can be changed.

Examples of the diamine represented by formula (3) include 4,4'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, bis(p-β-amino-t-butylphenyl) ether, 1,3- Bis(3-aminophenoxy)benzene (APB), 1,3-bis(4-aminophenoxy)benzene (TPE-R), 1,4-bis(3-aminophenoxy)benzene or 1,4-bis(4-aminophenoxy)benzene Examples include, but are not limited to, -aminophenoxy)benzene, bis[4-(4-aminophenoxy)phenyl]ether, and the like.

As the diamine component other than the above, any known diamine component used in the production of polyamic acid and polyimide can be used without restriction, but any known diamine component used in the production of polyamic acid and polyimide can be used without restriction. However, aromatic diamine compounds are preferred. Further, a diamine compound having an aliphatic skeleton may also be used. For example, 3,4'-diaminodiphenylmethane, 3,4'-diaminodiphenylpropane, 3,4'-diaminodiphenyl sulfide, 3,4'-diaminobenzophenone, (3,3'-bisamino)diphenylamine, 3-[4 -(4-aminophenoxy)phenoxy]benzenamine, 3-[3-(4-aminophenoxy)phenoxy]benzenamine, 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-(3-aminophenoxy) ) phenyl]methane, bis[4-(3-aminophenoxy)phenyl]propane, bis[4-(3-aminophenoxy)phenyl]ether, bis[4-(3-aminophenoxy)phenyl]sulfone, bis[4 -(3-aminophenoxy)]benzophenone, 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]ketone (BAPK), bis[4-(3-aminophenoxy)]biphenyl, bis[4-(4-aminophenoxy)phenyl]ketone (BAPK) -aminophenoxy)]biphenyl, 2,2-bis(4-aminophenoxyphenyl)propane (BAPP), 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl (TFMB), bis[4 -(aminophenoxy)phenyl]sulfone (BAPS), 4,6-dimethyl-m-phenylenediamine, 2,5-dimethyl-p-phenylenediamine, 2,4-diaminomesitylene, 3,3'-dimethyl-4, 4'-Diaminodiphenylmethane, 3,5,3',5'-tetramethyl-4,4'-diaminodiphenylmethane, 2,4-toluenediamine, m-phenylenediamine, p-phenylenediamine, 4,4'-diamino Diphenylpropane, 3,3'-diaminodiphenylpropane, 4,4'-diaminodiphenylethane, 3,3'-diaminodiphenylethane, 4,4'-diaminodiphenylmethane, 3,3'-diaminodiphenylmethane, 2,2- Bis(4-aminophenoxyphenyl)propane, 2,2-bis[4-(4-aminophenoxy)phenyl]propane, 4,4'-diaminodiphenyl sulfide, 3,3'-diaminodiphenyl sulfide, 4,4' -diaminodiphenylsulfone, 3,3'-diaminodiphenylsulfone, 1,3-bis(3-aminophenoxy)benzene, 1,3-bis(4-aminophenoxy)benzene, 1,4-bis(4-aminophenoxy) ) Benzene, benzidine, 3,3'-diaminobiphenyl, 3,3'-dimethyl-4,4'-diaminobiphenyl, 3,3'-dimethoxybenzidine, 4,4"-diamino-p-terphenyl, 3, 3"-diamino-p-terphenyl, bis(p-aminocyclohexyl)methane, 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-xylylene diamine, p-xylylene diamine, 2,6-diaminopyridine, 2,5-diaminopyridine, 2 ,5-diamino-1,3,4-oxadiazole, piperazine, 4-(1H,1H,11H-eicosafluoroundecanoxy)-1,3-diaminobenzene, 4-(1H,1H-perfluoro -1-butanoxy)-1,3-diaminobenzene, 4-(1H,1H-perfluoro-1-heptanoxy)-1,3-diaminobenzene, 4-(1H,1H-perfluoro-1-octanoxy)- 1,3-Diaminobenzene, 4-pentafluorophenoxy-1,3-diaminobenzene, 4-(2,3,5,6-tetrafluorophenoxy)-1,3-diaminobenzene, 4-(4-fluorophenoxy )-1,3-diaminobenzene, 4-(1H,1H,2H,2H-perfluoro-1-hexanoxy)-1,3-diaminobenzene, 4-(1H,1H,2H,2H-perfluoro-1 -dodecanoxy)-1,3-diaminobenzene, (2,5)-diaminobenzotrifluoride, diaminotetra(trifluoromethyl)benzene, diamino(pentafluoroethyl)benzene, 2,5-diamino(perfluorohexyl)benzene , 2,5-diamino(perfluorobutyl)benzene, 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl, 3,3'-bis(trifluoromethyl)-4,4'- Diaminobiphenyl, octafluorobenzidine, 4,4'-diaminodiphenyl ether, 2,2-bis(4-aminophenyl)hexafluoropropane, 1,3-bis(anilino)hexafluoropropane, 1,4-bis(anilino) Octafluorobutane, 1,5-bis(anilino)decafluoropentane, 1,7-bis(anilino)tetradecafluoroheptane, 2,2'-bis(trifluoromethyl)-4,4'-diaminodiphenyl ether, 3 ,3'-bis(trifluoromethyl)-4,4'-diaminodiphenyl ether, 3,3',5,5'-tetrakis(trifluoromethyl)-4,4'-diaminodiphenyl ether, 3,3'-bis (trifluoromethyl)-4,4'-diaminobenzophenone, 4,4'-diamino-p-terphenyl, 1,4-bis(p-aminophenyl)benzene, p-(4-amino-2-trifluoro Methylphenoxy)benzene, bis(aminophenoxy)bis(trifluoromethyl)benzene, bis(aminophenoxy)tetrakis(trifluoromethyl)benzene, 2,2-bis{4-(4-aminophenoxy)phenyl}hexafluoropropane , 2,2-bis{4-(3-aminophenoxy)phenyl}hexafluoropropane, 2,2-bis{4-(2-aminophenoxy)phenyl}hexafluoropropane, 2,2-bis{4-( 4-aminophenoxy)-3,5-dimethylphenyl}hexafluoropropane, 2,2-bis{4-(4-aminophenoxy)-3,5-ditrifluoromethylphenyl}hexafluoropropane, 4,4'-bis( 4-Amino-2-trifluoromethylphenoxy)biphenyl, 4,4'-bis(4-amino-3-trifluoromethylphenoxy)biphenyl, 4,4'-bis(4-amino-2-trifluoromethylphenoxy) ) diphenylsulfone, 4,4'-bis(3-amino-5-trifluoromethylphenoxy)diphenylsulfone, 2,2-bis{4-(4-amino-3-trifluoromethylphenoxy)phenyl}hexafluoropropane , bis{(trifluoromethyl)aminophenoxy}biphenyl, bis[{(trifluoromethyl)aminophenoxy}phenyl]hexafluoropropane, bis{2-[(aminophenoxy)phenyl]hexafluoroisopropyl}benzene, 4,4 Examples include aromatic diamines derived from '-bis(4-aminophenoxy)octafluorobiphenyl. Other examples include aliphatic diamines such as dimer diamine, hexamethylene diamine, and pentamethylene diamine.

(Other ingredients)
The polyamic acid and polyimide of the present invention may include silicon dioxide, aluminum oxide, boron nitride, magnesium oxide, beryllium oxide, aluminum nitride, silicon nitride, aluminum fluoride, fluoride, etc. It may also contain fillers such as calcium chloride, metal salts of organic phosphinic acids, and other components. These components can be used alone or in a mixture of two or more.

(Method for forming polyimide layer)
As a method for forming a polyimide layer, for example, [1] a method in which a solution of polyamic acid is applied to a supporting base material (for example, a metal layer), dried, and then imidized to produce a resin film (hereinafter referred to as a casting method) ), [2] Those formed by applying a polyamic acid solution to a supporting base material and drying it, then peeling off the polyamic acid gel film from the supporting base material and imidizing it to produce a resin film. It will be done. In addition, in the case of a plurality of polyimide layers, the manufacturing method may include, for example, [3] Applying and drying a solution of polyamic acid to the supporting base material is repeated multiple times, and then imidization is performed. method (hereinafter referred to as sequential coating method), [4] A method in which a layered structure of polyamic acid is simultaneously coated and dried on a supporting base material by multilayer extrusion, and then imidized (hereinafter referred to as multilayer extrusion method). The following are examples of what has been done.
From the viewpoint of controlling dimensional stability and adhesion with the metal layer, we form a polyimide layer (polyimide film, insulating resin layer and metal-clad laminate described below) using the casting method and sequential coating method. It is preferable to do so.

The method for applying the polyamic acid solution (or polyimide solution) onto the substrate is not particularly limited, and can be applied using, for example, a comma, die, knife, lip, or other coater. When forming a multilayer polyimide layer, a method of repeatedly applying a polyamic acid solution (or polyimide solution) to a base material and drying it is preferred. The insulating resin layer (described later) in the present invention may be formed from only a single layer of the above-mentioned polyimide, or may be formed from a plurality of polyimide layers.

As described above, the polyimide (layer) of the present invention has excellent heat dissipation (thermal conductivity), flexibility/toughness, and heat resistance. In particular, it is preferable to simultaneously satisfy a) end tear resistance and b) thermal conductivity in the thickness direction (λz). Furthermore, one or more of c) thermal diffusivity in the thickness direction (α), d) glass transition temperature (Tg), e) tear propagation resistance, and f) coefficient of thermal expansion is also within a predetermined range. It is preferable.

The polyimide (layer) of the present invention has a) end tear resistance measured at a width of 20 mm (according to JIS standards). It is preferable that it is in the range of 30N or more and 500N or less. A more preferable lower limit is 60N or more, an even more preferable lower limit is 75N or more, and an even more preferable lower limit is 100N or more. On the other hand, there is no particular restriction on the preferable upper limit. Within this range, defects such as tearing during processing and use can be prevented.

The polyimide (layer) of the present invention preferably has b) a thermal conductivity (λz) in the thickness direction of 0.20 W/m·K or more. More preferably, it is 0.22 W/m·K or more. If the thermal conductivity λz is less than 0.20 W/m·K, when the resin alone is used for heat dissipation purposes, the purpose may not be achieved because heat cannot be sufficiently dissipated and the heat dissipation effect is weak.

Furthermore, it is preferable that the (layer of) polyimide of the present invention has c) a thermal diffusivity (α) in the thickness direction of 0.100 m ² /s or more. More preferably, it is 0.120 or more. If the thermal diffusivity (α) is less than 0.100 m ² /s, when the resin alone is used for heat dissipation purposes, heat cannot be sufficiently released and the heat dissipation effect is weak, so the purpose may not be achieved.
Note that the thermal conductivity (λ _z ) and thermal diffusivity (α) are characteristics that do not depend on the thickness of the polyimide layer, so the thickness conditions for measurement may be adjusted as appropriate depending on constraints and convenience of the measuring device. Can be changed/set.

Further, the polyimide (layer thereof) of the present invention preferably has d) a glass transition temperature (Tg) of 250° C. or higher and heat resistance. The temperature is more preferably 270°C or higher, and even more preferably 3000°C or higher.

Moreover, it is preferable that the (layer of) polyimide of the present invention has e) tear propagation resistance of 1.5 kN/m or more. More preferably 3.0 kN/m or more, more preferably 4.0 kN/m or more. The upper limit value is not particularly limited. Within this range, defects such as tearing during processing and use can be prevented.

Further, the polyimide (layer) of the present invention preferably has f) a coefficient of thermal expansion (CTE) of preferably 50 ppm/K or less, more preferably 1 ppm/K or more and 45 ppm/K or less.

In addition, the polyimide (layer) of the present invention preferably has a 1% weight loss temperature (Td1) of 450°C or higher in a thermal decomposition test, more preferably 470°C or higher, and still more preferably 490°C or higher. preferable. By controlling it within such a range, it has sufficient heat resistance even when applied to the main constituent components of FPC.

The thickness of the polyimide (layer) of the present invention as a whole of the insulating resin layer/resin film is preferably within the range of 2 to 100 μm, and more preferably within the range of 4 to 50 μm. If the thickness is less than 2 μm, problems such as wrinkles in the metal foil are likely to occur during the transportation process during the production of the metal-clad laminate. On the other hand, if the thickness exceeds 100 μm, it tends to be disadvantageous in terms of high thermal conductivity, toughness, flexibility, etc.

<Metal-clad laminate>
(metal layer)
The material of the metal layer is not particularly limited, but examples include copper, stainless steel, iron, nickel, beryllium, aluminum, zinc, indium, silver, gold, tin, zirconium, tantalum, titanium, lead, magnesium, and manganese. and alloys thereof. Among these, metal elements such as copper, iron, or nickel, or indium tin oxide (ITO) are preferable, and copper (copper foil) is more preferable. As the copper foil, both electrolytic copper foil and rolled copper foil can be used. In addition, when selecting these metal layers, they should be selected so as to exhibit the characteristics required for the purpose of use, such as the conductivity of the metal layer, the optical transparency of the polyimide layer, and the adhesion with the polyimide layer. . Although there is no particular restriction on the shape of the metal layer, it may be processed as appropriate depending on the application. A roll-shaped material formed in an elongated shape is preferably used.

The thickness of the metal layer is not particularly limited, but is preferably 100 μm or less, more preferably within the range of 0.1 to 70 μm, and even more preferably within the range of 1 to 50 μm. In heat dissipation applications, such as in automotive applications, large currents are often passed through, so a thick metal layer (for example, copper foil) is preferable in order to withstand large currents. On the other hand, if the metal layer is too thick, the flexibility and processability of the laminated substrate will tend to decrease, and on the other hand, the weight will tend to increase.

(insulating resin layer)
The metal-clad laminate of the present invention includes an insulating resin layer consisting of a single layer or multiple layers, and a metal layer laminated on one side (single side) or both sides (both sides) of this insulating resin layer, and the insulating resin layer At least one layer of the polyimide layer is comprised of the above-mentioned polyimide layer.

When the insulating resin layer is composed of a plurality of polyimide layers, it may have a two-layer structure of a polyimide layer (P1) that is directly laminated on a metal layer (described later) and a polyimide layer (P2) that is not directly laminated on the metal layer. Although not particularly limited, it is preferable that the third polyimide layer (P3) is formed in the order of (P1)/(P2)/(P3) as in Structures 1 to 4 illustrated below. It is preferable that they are laminated. M1 and M2 represent metal layers, and M1 and M2 may be the same or different. The polyimide layer (P1) and the third polyimide layer (P3) directly laminated on the metal layer may have the same composition. For example, when forming multiple polyimide layers by a casting method, a polyimide layer (P1) that is laminated directly on the metal layer from the cast surface side and a polyimide layer (P2) that is not laminated directly on the conductor layer are laminated in this order. It may be a layered structure, or a polyimide layer (P1) that is laminated directly on the conductor layer from the cast surface side, a polyimide layer (P2) that is not laminated directly with the conductor layer, and a third polyimide layer (P3) are laminated in this order. It is also possible to have a three-layer structure. The "cast surface" here refers to the surface on the support side when forming the polyimide layer. The support may be a metal layer (described later) of the metal-clad laminate of the present invention, glass, or the like, or a support used when forming a gel film or the like. Note that the surface of the plurality of polyimide layers opposite to the cast surface is described as a "laminate surface," but unless otherwise specified, a metal layer may or may not be laminated on the laminate surface.

Configuration 1; M1/P1/P2
Configuration 2; M1/P1/P2/P1 (or P3)
Configuration 3; M1/P1/P2/P1 (or P3)/M2 (or M1)
Configuration 4; M1/P1/P2/P1 (or P3)/P2/P1 (or P3)/M2 (or M1)

The polyimide constituting the polyimide layer (P1) and the polyimide layer (P3) is preferably thermoplastic polyimide, which improves adhesiveness as an insulating resin layer and is suitable for application as an adhesive layer with a metal layer.

A preferred embodiment of the insulating resin layer has a thermoplastic polyimide layer (P1) and a non-thermoplastic polyimide layer (P2) composed of non-thermoplastic polyimide, and the non-thermoplastic polyimide layer (P2) has a It is preferable to have a polyimide layer (P1) serving as a thermoplastic polyimide layer on at least one side. That is, the polyimide layer (P1) may be provided on one or both sides of the non-thermoplastic polyimide layer.

Further, the non-thermoplastic polyimide layer constitutes a low thermal expansion polyimide layer, and the thermoplastic polyimide layer constitutes a high thermal expansion polyimide layer. Here, the low thermal expansion polyimide layer is a polyimide layer having a coefficient of thermal expansion (CTE) preferably in the range of 1 ppm/K or more and 25 ppm/K or less, more preferably in the range of 3 ppm/K or more and 25 ppm/K or less. say. The high thermal expansion polyimide layer is made of polyimide having a CTE of preferably 35 ppm/K or more, more preferably 35 ppm/K or more and 80 ppm/K or less, and even more preferably 35 ppm/K or more and 70 ppm/K or less. It refers to a layer. The polyimide layer can be made into a polyimide layer having a desired CTE by appropriately changing the combination of raw materials used, the thickness, and drying/curing conditions.

The coefficient of thermal expansion (CTE) of the entire insulating resin layer is preferably within the range of 10 to 30 ppm/K. By controlling it within such a range, deformation such as curling can be suppressed and high dimensional stability can be ensured. Here, CTE is the average value of the coefficient of thermal expansion of the insulating resin layer in the MD direction and the TD direction.

Here, non-thermoplastic polyimide generally refers to polyimide that does not soften or exhibit adhesive properties even when heated; A polyimide having a storage modulus of 1.0×10 ⁹ Pa or more at 350° C. and a storage modulus of 1.0×10 ⁹ Pa or more at 350° C. In addition, thermoplastic polyimide (also referred to as "TPI") generally refers to polyimide whose glass transition temperature (Tg) can be clearly confirmed. A polyimide having a storage modulus of 1.0×10 ⁹ Pa or more at 300° C. and less than 1.0×10 ⁸ Pa at 300° C.

Among the insulating resin layers, when the thickness of the polyimide layer (P1) in contact with the metal layer is T1 and the thickness of the main polyimide layer is T2, the thickness of T1 is preferably within the range of 1 μm or more and 4 μm or less, and the thickness of T2 is It is preferably within the range of 4 μm or more and 30 μm or less. From another viewpoint, the thickness of T1 is preferably 20% or less of the thickness of the insulating resin layer. Here, "main" means having the largest thickness among the plurality of polyimide layers constituting the insulating resin layer, preferably 60% or more, more preferably 70% of the thickness of the insulating resin layer. The thickness is more preferably 80% or more. The main polyimide layer is preferably composed of a non-thermoplastic polyimide.

The insulating resin layer as a whole preferably satisfies all the characteristic values of the polyimide layer described above.

<Method for manufacturing metal-clad laminates>
As mentioned above, in the metal-clad laminate of the present invention, an insulating resin layer consisting of a single layer or multiple layers of polyimide is formed on a metal layer as a supporting base material by a casting method or a sequential coating method. is preferable from the viewpoint of dimensional stability, but is not particularly limited. For example, an insulating resin layer (resin film) comprising a layer of the polyimide of the present invention is prepared, a seed layer is formed by sputtering metal onto this, and then a metal layer is formed by, for example, plating. You may.

Alternatively, the insulating resin layer (resin film) containing the polyimide of the present invention may be prepared, and a metal foil may be laminated thereon by a method such as thermocompression bonding.

In those cases, the surface of the resin film may be subjected to a modification treatment such as plasma treatment in order to improve the adhesion between the resin film and the metal layer.

In addition, when manufacturing a metal-clad laminate having metal layers on both sides, for example, a transparent insulating resin layer can be applied directly onto the polyimide layer of the single-sided metal-clad laminate obtained by the above method, or as needed. It can be obtained by forming an adhesive layer that does not impede properties such as properties, and then laminating a metal layer by heat-pressure bonding or the like. The hot pressing temperature when the metal layer is heat-pressed is not particularly limited, but it is preferably higher than the glass transition temperature of the polyimide layer adjacent to the metal layer used. Furthermore, the hot press pressure is preferably in the range of 1 to 500 kg/m ² , although it depends on the type of press equipment used.

(Peel strength)
The 180° peel strength between the insulating resin layer and the metal layer in the metal-clad laminate of the present invention is preferably 0.3 kN/m or more, more preferably 0.5 kN/m.
In this specification, the evaluation of physical properties and characteristic values was measured under the conditions described in the examples, and unless otherwise specified, the values were measured at room temperature (23° C.).

<Circuit board>
The metal-clad laminate of the present invention is mainly useful as a material for circuit boards such as FPC. The circuit board of the present invention can be manufactured by processing the metal layer of the metal-clad laminate into a pattern by a conventional method to form a wiring layer. That is, the circuit board of the present invention includes an insulating resin layer and a wiring layer provided on at least one surface of the insulating resin layer, and a part or all of the insulating resin layer is made of the above polyimide. layer (polyimide film). Furthermore, in order to improve the adhesion between the insulating resin layer and the wiring layer, the layer of the insulating resin layer that is in contact with the wiring layer is preferably a thermoplastic polyimide layer.

Hereinafter, the content of the present invention will be specifically explained based on Examples, but the present invention is not limited to the scope of these Examples.

The abbreviations used in this example represent the following compounds.
BTDA: 3,3',4,4'-benzophenonetetracarboxylic dianhydride BPDA: 3,3',4,4'-biphenyltetracarboxylic dianhydride PMDA: Pyromellitic dianhydride DAPE: 4, 4'-diaminodiphenyl ether BAPP: 2,2-bis(4-aminophenoxyphenyl)propane m-TB: 2,2'-dimethyl-4,4'-diaminobiphenyl TPE-R: 1,3-bis(4- aminophenoxy)benzene DABA: 4,4'-diaminobenzanilide MABA: 4,4'-diamino-2'-methoxybenzanilide 3,4'-DAPE: 3,4'-diaminodiphenyl ether TPE-Q: 1,4 -Bis(4-aminophenoxy)benzeneDMAc: N,N-dimethylacetamide

Moreover, the following evaluation method was followed for each characteristic evaluated in the examples.

[Measurement of viscosity]
The viscosity of the polyamic acid solution was measured using a cone-plate viscometer (manufactured by Tokimec) with a constant temperature water bath.
Measurements were made at 25°C.

[Weight average molecular weight (Mw)]
It was measured by gel permeation chromatography (manufactured by Tosoh Corporation, trade name: HLC-8220GPC). Polystyrene was used as a standard substance, and N,N-dimethylacetamide was used as a developing solvent.

[Thickness direction thermal diffusivity (α), thickness direction thermal conductivity (λz)]
A polyimide resin film was cut into a size of 20 mm x 20 mm, and the thermal diffusivity α in the thickness direction was determined by the laser flash method (manufactured by NETZSCH, product name: Xenon Flash Analyzer LFA447 Nanoflash device), specific heat by differential scanning calorimetry (DSC), and the temperature in water. The density was measured by the substitution method, and the thermal conductivity (W/m·K) was calculated based on these results. Due to the convenience of the measuring device, a film with a thickness of 80 μm was used in this measurement.

[Tear propagation resistance]
A 63.5 mm x 50 mm polyimide resin film was used as a test piece, a cut with a length of 12.7 mm was made in the test piece, and the tear propagation resistance was measured using a light load tear tester manufactured by Toyo Seiki Co., Ltd.

[End tear resistance]
According to method B of JIS C2151 (2019), end tear resistance was measured using a polyimide film with a width of 20 mm and a length of 200 mm as a test piece using Strograph R1 manufactured by Toyo Seiki Co., Ltd., trade name.

[Tensile modulus, tensile strength, tensile elongation]
Prepare a test piece of polyimide film (10 mm x 15 mm) and test it using a Tensilon universal testing machine (Orientech Co., Ltd., RTA-250) at a tensile speed of 10 mm/min in accordance with IPC-TM-650, 2.4.19. A tensile test was conducted, and the tensile modulus, tensile strength, and tensile elongation were calculated.

[Coefficient of thermal expansion (CTE)]
A polyimide film (3 mm x 15 mm) was heated from 30°C to 280°C at a heating rate of 10°C/min while applying a load of 5.0g using a thermomechanical analysis (TMA) device, and then from 250°C to 280°C. The temperature was lowered to 100°C, and the coefficient of thermal expansion was measured from the amount of elongation (linear expansion) of the polyimide film at the time of cooling.

[Thermal decomposition temperature (Td1)]
The weight change when a polyimide film weighing 10 to 20 mg was heated at a constant rate from 30°C to 550°C in a thermogravimetric analysis (TG) device TG/DTA6200 manufactured by SEIKO in a nitrogen atmosphere. The weight at 200°C was set to zero, and the temperature at which the weight loss rate was 1% was defined as the thermal decomposition temperature (Td1).

[Peel strength]
In order to measure the peel strength, the obtained metal-clad laminate was plated with a metal layer of 25 μm to prepare a laminate, and then circuit-processed into a 1 mm pattern. Using a tension tester, the polyimide film side of the sample having a circuit with a width of 1 mm obtained from the laminate was fixed to an aluminum plate with double-sided tape, and the copper foil was peeled off in a 180° direction at a speed of 50 mm/min. The strength was determined.

Synthesis examples 1 to 13
To synthesize polyamic acid solutions A to N, DMAc as a solvent was added to a 500 ml separable flask under a nitrogen stream so that the solid content concentration shown in Table 1 was obtained, and the diamine components shown in Table 1 were added. and an acid anhydride component (molar parts) were added thereto and stirred at room temperature for 36 hours to carry out a polymerization reaction to prepare viscous solutions A to N of polyamic acid.

[Example 1]
Polyamic acid solution A obtained in Synthesis Example 1 was placed on copper foil 1 (electrolytic copper foil, manufactured by Fukuda Metal Foil and Powder Industry Co., Ltd., product name: CF-T4MDS-HD-12, thickness: 12 μm, Rz = 1.4 μm). was applied so that the thickness after curing was 21 μm, and the solvent was removed by heating and drying at 90 to 140°C. Thereafter, the temperature was raised stepwise over 30 minutes in a temperature range of 130 to 360°C to produce a metal clad laminate (CCL) 1A in which an insulating resin layer made of a polyimide layer was laminated on the copper foil 1. . In order to evaluate the characteristics of the polyimide layer in the metal-clad laminate 1A, the copper foil 1 was removed by etching to prepare the film 1a, and the tear propagation resistance, end tear resistance, glass transition temperature (Tg), CTE, Td1, and tensile elasticity were evaluated. The tensile strength, tensile elongation, and peel strength were evaluated.
Note that samples for measuring thermal diffusivity (α) and thermal conductivity (λ _z ) were prepared in the same manner as described above except that the resin thickness after curing was made to be 80 μm.

(Examples 2 to 9, Comparative Examples 1 to 4)
Metals according to Examples 2 to 9 using polyamic acid solutions B, C, D, E, K, L, M or N in the same manner as in Example 1 by changing the type and thickness of the polyamic acid solution used. Stretched laminates 2B to 9N and films 2b to 9n, and metal clad laminates 1G to 4J and films 1g to 4j according to Comparative Examples 1 to 4 using polyamic acid solutions G, H, I or J were obtained, and the same procedure was carried out. It was evaluated as follows.
The evaluation results are shown in Tables 2 to 4.

Claims (10)

An acid anhydride residue derived from an acid anhydride component represented by the following general formula (1),
Contains a diamine residue derived from a diamine component represented by general formula (2),
Contains 50 mol% or more of acid anhydride residues derived from the acid anhydride component represented by the following general formula (1) based on the total acid anhydride residues,
A polyamic acid characterized by containing 50 mol% or more of diamine residues derived from a diamine component represented by the following general formula (2) based on all diamine residues.

[In formula (2), R is independently a halogen atom, an alkyl group or alkoxy group having 1 to 6 carbon atoms which may be substituted with a halogen atom, or a monovalent group having 1 to 6 carbon atoms] represents a phenyl group or phenoxy group which may be substituted with a hydrocarbon group or an alkoxy group. m and n each independently represent the number of substitutions, m represents an integer of 0 to 4, and n represents an integer of 0 to 4. ] The polyamic acid according to claim 1, containing 10 mol% to 50 mol% of a diamine residue derived from a diamine component represented by the following general formula (3).

[In formula (3), Z represents -O-. R is independently a halogen atom, an alkyl group or alkoxy group having 1 to 6 carbon atoms which may be substituted with a halogen atom, or a monovalent hydrocarbon group having 1 to 6 carbon atoms or an alkoxy group represents a phenyl group or phenoxy group which may be substituted with n ₁ indicates the number of substitutions and is an integer from 0 to 4. n ₂ represents an integer from 0 to 3. ] A polyimide obtained by imidizing the polyamic acid according to claim 1 or 2. Below a) and b);
a) The end tear resistance measured at a width of 20 mm is within the range of 30 N or more and 500 N or less,
b) The thermal conductivity (λz) in the thickness direction is within the range of 0.20 W/m K or more,
The polyimide according to claim 3, which satisfies the following. Furthermore, the following condition c);
c) The thermal diffusivity (α) in the thickness direction is within the range of 0.100 m ² /s or more,
The polyimide according to claim 4, which satisfies the following. Furthermore, the following condition d);
d) The glass transition temperature is 250°C or higher,
The polyimide according to claim 4 or 5, which satisfies the following. Furthermore, the following condition e);
e) tear propagation resistance is 1.5 kN/m;
The polyimide according to any one of claims 4 to 6, which satisfies the following. Furthermore, the following condition f);
f) The coefficient of thermal expansion is 50 ppm/K or less;
The polyimide according to any one of claims 4 to 7, which satisfies the following. A metal-clad laminate comprising an insulating resin layer consisting of a single layer or multiple layers, and a metal layer laminated on one side or both sides of the insulating resin layer,
A metal-clad laminate, wherein at least one of the insulating resin layers is composed of a polyimide layer according to any one of claims 3 to 8. A circuit board comprising an insulating resin layer consisting of a single layer or multiple layers, and a conductor circuit layer laminated on one side or both sides of the insulating resin layer,
A circuit board, wherein at least one layer of the insulating resin layer is constituted by a layer of polyimide according to any one of claims 3 to 8.