JP6767759B2 - Polyimide, resin film and metal-clad laminate - Google Patents

Description

The present invention relates to polyimide, and a resin film and a metal-clad laminate using this polyimide.

In recent years, with the progress of miniaturization, weight reduction, and space saving of electronic devices, a flexible printed wiring board (FPC; Flexible Printed Circuit Board) (FPC), which is thin and lightweight, has flexibility, and has excellent durability even after repeated bending. The demand for Circuits) is increasing. Since FPC can be mounted three-dimensionally and at high density even in a limited space, it can be used for wiring of moving parts of electronic devices such as HDDs, DVDs, and mobile phones, and for parts such as cables and connectors. It is expanding.

In addition to the above-mentioned high density, the high performance of the equipment has advanced, so it is also necessary to cope with the high frequency of the transmission signal. When a high-frequency signal is transmitted, if the transmission loss of the signal transmission path is large, inconveniences such as loss of an electric signal and long delay time of the signal occur. Therefore, it is important to reduce the transmission loss of the FPC. In order to cope with high frequency, an FPC having a liquid crystal polymer having a low dielectric constant and a low dielectric loss tangent as a dielectric layer is used. However, although the liquid crystal polymer has excellent dielectric properties, there is room for improvement in heat resistance and adhesiveness to the metal foil.

In order to improve heat resistance and adhesiveness, a metal-clad laminate having a polyimide as an insulating layer has been proposed (Patent Document 1). According to Patent Document 1, it is generally known that the dielectric constant is lowered by using an aliphatic monomer as the monomer of the polymer material, and an aliphatic (chain) tetracarboxylic dianhydride is used. Since the heat resistance of the obtained polyimide is extremely low, it cannot be used for processing such as soldering, which poses a practical problem. However, when an aliphatic tetracarboxylic dianhydride is used, it becomes a chain. It is said that a polyimide with improved heat resistance can be obtained. However, although the polyimide film formed from such a polyimide has a dielectric constant of 3.2 or less at 10 GHz, the dielectric loss tangent is more than 0.01, and the dielectric property is still not sufficient. In addition, many of the polyimides using the above-mentioned aliphatic monomers have a large coefficient of linear thermal expansion, and a metal-clad laminate having these as an insulating layer causes warpage, so that it is difficult to use the polyimide as an insulating layer of a circuit board. there were.

Japanese Unexamined Patent Publication No. 2004-358961

An object of the present invention is that it is possible to cope with high frequency in circuit wiring which is easily affected by the dielectric property in the thickness direction such as strip line and microstrip line which are mainly used for small electronic devices. It is an object of the present invention to provide a polyimide, a resin film and a metal-clad laminate having a low coefficient of expansion (CTE).

In order to solve the above-mentioned problems, the present inventors can keep the coefficient of linear thermal expansion (CTE) low when a resin film is formed, while the polyimide obtained from a specific monomer has low dielectric properties. Therefore, they have found that a circuit board such as an FPC that can be applied to high frequency applications can be obtained while suppressing the occurrence of warpage, and have completed the present invention.

That is, the polyimide of the present invention is a polyimide obtained by reacting an acid anhydride component containing an aromatic tetracarboxylic dianhydride with a diamine component containing an aromatic diamine, and is the following (i) to (iii). ) Condition;
(I) With respect to 100 mol parts of the acid anhydride component
2,3,6,7-Naphthalenetetracarboxylic dianhydride (NTCDA) is contained in the range of 40 to 80 mol parts, and 3,3', 4,4'-biphenyltetracarboxylic dianhydride (BPDA) is contained. ) In the range of 20 to 60 mol parts;
(Ii) With respect to 100 mol parts of the diamine component
It contains at least one aromatic diamine (diamine I) selected from the group consisting of aromatic diamines represented by the following general formulas (1) and (2) in the range of 60 to 90 mol parts.
It contains at least one aromatic diamine (diamine II) selected from the group consisting of aromatic diamines represented by the following general formulas (3) to (5) in the range of 10 to 40 mol parts;
(Iii) The ratio (A / B) of the total (A) of NTCDA and diamine I to the total (B) of BPDA and diamine II is in the range of 1.6 to 4.0;
It is characterized by satisfying.

［式（１）中、Ｒ_１及びＲ_２はそれぞれ独立に水素原子、又はハロゲン原子、あるいは炭素数１〜４のハロゲン原子で置換されてもよいアルキル基、アルコキシ基若しくはアルケニル基を示し、ｍ及びｎは１〜４の整数を示す。］

[In formula (1), R ₁ and R ₂ each represent an alkyl group, an alkoxy group or an alkenyl group which may be independently substituted with a hydrogen atom, a halogen atom, or a halogen atom having 1 to 4 carbon atoms, and m. And n represent integers 1 to 4. ]

［式（３）中、Ｒ_１及びＲ_２はそれぞれ独立に水素原子、又はハロゲン原子、あるいは炭素数１〜４のハロゲン原子で置換されてもよいアルキル基、アルコキシ基若しくはアルケニル基を示し、Ｘは−Ｏ−、−Ｓ−、−ＣＨ_２−、−ＣＨ(ＣＨ_３)−、−Ｃ(ＣＨ_３)_２−、−ＣＯ−、−ＣＯＯ−、−ＳＯ_２−、−ＮＨ−又は−ＮＨＣＯ−から選ばれる２価の基を示し、ｍ及びｎは独立に１〜４の整数を示す。］

[In formula (3), R ₁ and R ₂ represent an alkyl group, an alkoxy group or an alkenyl group which may be independently substituted with a hydrogen atom, a halogen atom, or a halogen atom having 1 to 4 carbon atoms, respectively, and X. Is -O-, -S-, -CH _2- , -CH (CH ₃ )-, -C (CH ₃ ) _2- , -CO-, -COO-, -SO _2- , -NH- or -NHCO Indicates a divalent group selected from −, where m and n independently represent integers 1 to 4. ]

［式（４）中、Ｒ_１、Ｒ_２及びＲ_３はそれぞれ独立に水素原子、又はハロゲン原子、あるいは炭素数１〜４のハロゲン原子で置換されてもよいアルキル基、アルコキシ基若しくはアルケニル基を示し、Ｘは−Ｏ−、−Ｓ−、−ＣＨ_２−、−ＣＨ(ＣＨ_３)−、−Ｃ(ＣＨ_３)_２−、−ＣＯ−、−ＣＯＯ−、−ＳＯ_２−、−ＮＨ−又は−ＮＨＣＯ−から選ばれる２価の基を示し、ｍ、ｎ及びｏは独立に１〜４の整数を示す。］

[In formula (4), R ₁ , R ₂ and R ₃ each independently contain an alkyl group, an alkoxy group or an alkenyl group which may be substituted with a hydrogen atom, a halogen atom, or a halogen atom having 1 to 4 carbon atoms. Indicated, X is -O-, -S-, -CH _2- , -CH (CH ₃ )-, -C (CH ₃ ) _2- , -CO-, -COO-, -SO _2- , -NH- Alternatively, it represents a divalent group selected from -NHCO-, where m, n and o independently represent integers 1 to 4. ]

［式（５）中、Ｒ_１、Ｒ_２、Ｒ_３及びＲ_４はそれぞれ独立に水素原子、又はハロゲン原子、あるいは炭素数１〜４のハロゲン原子で置換されてもよいアルキル基、アルコキシ基若しくはアルケニル基を示し、Ｘ及びＸ_１は単結合、−Ｏ−、−Ｓ−、−ＣＨ_２−、−ＣＨ(ＣＨ_３)−、−Ｃ(ＣＨ_３)_２−、−ＣＯ−、−ＣＯＯ−、−ＳＯ_２−、−ＮＨ−又は−ＮＨＣＯ−から選ばれる２価の基を示すが、Ｘ及びＸ_１の両方が単結合である場合を除くものとし、ｍ、ｎ、ｏ及びｐは独立に１〜４の整数を示す。］

[In formula (5), R ₁ , R ₂ , R ₃ and R ₄ are each independently substituted with a hydrogen atom, a halogen atom, or a halogen atom having 1 to 4 carbon atoms, an alkyl group, an alkoxy group, or the like. Representing an alkoxy group, X and X ₁ are single bonds, -O-, -S-, -CH _2- , -CH (CH ₃ )-, -C (CH ₃ ) _2- , -CO-, -COO- , -SO _2- , -NH- or -NHCO-, indicating a divalent group, except when both X and X ₁ are single bonds, and m, n, o and p are independent. Indicates an integer of 1 to 4. ]

In the polyimide of the present invention, the amount of aromatic tetracarboxylic dianhydride represented by the following general formula (6) may be 20 parts or less with respect to 100 parts by mole of the acid anhydride component.

［式（６）中、Ａは−Ｏ−、−Ｓ−、−Ｃ(ＣＨ_３)_２−、−Ｃ(ＣＦ_３)_２−又は−ＳＯ_２−から選ばれる２価の基を示す。］

[In formula (6), A represents a divalent group selected from -O-, -S-, -C (CH ₃ ) _2- , -C (CF ₃ ) _2- or -SO _2- . ]

The resin film of the present invention is characterized by being made of the above-mentioned polyimide.

The resin film of the present invention may have a coefficient of linear thermal expansion in the range of 5 × ^{10-6 to} 20 × ^10-6 (1 / K).

The metal-clad laminate of the present invention is a metal-clad laminate having an insulating resin layer and a metal layer.
The resin insulating layer has a single layer or a plurality of polyimide layers.
At least one of the polyimide layers is made of the polyimide and has a linear thermal expansion coefficient in the range of 5 × 10 ^{-6 to} 20 × 10 ^-6 (1 / K).

Although the polyimide of the present invention has low dielectric properties, it is possible to suppress a decrease in the glass transition temperature (Tg) and a low increase in the coefficient of linear thermal expansion (CTE) even when a resin film is formed. .. Therefore, the resin film using the polyimide of the present invention can be suitably used, for example, as an insulating resin layer of a metal-clad laminate. Further, by using the polyimide of the present invention as an insulating layer material, it is possible to provide a circuit board such as an FPC having good transmission characteristics while suppressing the occurrence of warpage.

Hereinafter, embodiments of the present invention will be described.

[Polyimide]
The polyimide of the present embodiment is a polyimide obtained by reacting an acid anhydride component containing an aromatic tetracarboxylic dianhydride component with a diamine component containing an aromatic diamine. Since polyimide is generally produced by reacting an acid anhydride with a diamine, a specific example of the polyimide can be understood by explaining the acid anhydride and the diamine. Hereinafter, preferable polyimides will be described with acid anhydride and diamine.

<Acid anhydride>
The polyimide of the present embodiment has 2,3,6,7-naphthalenetetracarboxylic dianhydride (NTCDA) and 3,3', 4,4'-biphenyltetracarboxylic dianhydride as raw material acid anhydride components. Anhydrous (BPDA) is used. Since NTCDA has a naphthalene skeleton, it is possible to control the orientation of molecules in polyimide as compared with other general acid anhydride components, suppress the coefficient of linear thermal expansion (CTE), and glass transition temperature (CTE). It has the effect of improving Tg). In particular, since NTCDA used in the present embodiment has a condensed structure derived from a carboxylic acid at positions 2, 3, 6 and 7 of the naphthalene skeleton, it is possible to extend the polymer chain in the longitudinal direction of the naphthalene skeleton. For example, a polymer having a condensed structure at the 1, 4, 5, and 8 positions has a higher effect of controlling the orientation of molecules in the polyimide, and a polymer having a condensed structure at the 2, 3, 6, and 7 positions has a higher effect. Since the acid anhydride structure is formed by the 5-membered ring, the reactivity with the diamine is higher than that of the one having the condensed structure at the 1, 4, 5, and 8 positions which form the acid anhydride structure by the 6-membered ring. Amidoic acid formation at room temperature is easy. Furthermore, since NTCDA has a larger molecular weight than general acid anhydrides, it has a large effect of lowering the imide group concentration and contributes to improvement of dielectric properties. Therefore, it is possible to achieve both improvement of the dielectric property and reduction of CTE. From such a viewpoint, NTCDA is preferably in the range of 40 to 80 mol parts, preferably in the range of 50 to 80 mol parts with respect to 100 parts by mole of the total acid anhydride component of the raw material. If the amount of NTCDA charged is less than 40 mol parts with respect to 100 mol parts of the total acid anhydride component of the raw material, the orientation of the molecule is lowered and it becomes difficult to reduce the CTE. On the other hand, if the amount of NTCDA charged exceeds 80 mol, it becomes difficult to apply it as an insulating layer for a circuit board due to its weakness as a film and high elastic modulus. In addition, BPDA can impart the self-supporting property of the gel film as the polyamic acid of the polyimide precursor, but increase the CTE as the film after imidization. From such a viewpoint, the BPDA is preferably in the range of 20 to 60 mol parts, preferably in the range of 20 to 50 mol parts with respect to 100 mol parts of the total acid anhydride component of the raw material.

Other acid anhydrides include, for example, pyromellitic dianhydride (PMDA), 3,3', 4,4'-diphenylsulfonetetracarboxylic hydride (DSDA), 4,4'-oxydiphthalic anhydride. Object (ODA), 2,2', 3,3'-, 2,3,3', 4'-or 3,3', 4,4'-benzophenone tetracarboxylic dianhydride (BTDA), 2, 3', 3,4'-biphenyltetracarboxylic acid dianhydride, 2,2', 3,3'-biphenyltetracarboxylic acid dianhydride, 2,3', 3,4'-diphenyl ether tetracarboxylic acid dianhydride Thing, bis (2,3-dicarboxyphenyl) ether dianhydride, 3,3'', 4,4''-, 2,3,3'', 4''-or 2,2'',3 , 3''-p-terphenyltetracarboxylic 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) sulfonate dianhydride, 1,1-bis (2,3- or 3,4-dicarboxyphenyl) Etan dianhydride, 1,2,7,8-, 1,2,6,7- or 1,2,9,10-phenanthrene-tetracarboxylic acid dianhydride, 2,3,6,7-anthracentetra Carboxyl dianhydride, 2,2-bis (3,4-dicarboxyphenyl) tetrafluoropropane dianhydride, 2,3,5,6-cyclohexane dianhydride, 1,2,5,6-naphthalenetetra Carboxyl dianhydride 1,4,5,8-naphthalenetetracarboxylic hydride 2,8-dimethyl-1,2,3,5,6,7-hexahydronaphthalene-1,2,5, 6-Tetracarboxylic acid dianhydride, 2,6- or 2,7-dichloronaphthalene-1,4,5,8-Tetracarboxylic acid 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, pyrrolidine-2,3,4,5-tetracarboxylic dianhydride, thiophene-2,3,4,5-tetracarboxylic dianhydride, 4, 4'-bis (2,3-dicarboxy) Phenoxy) Diphenylmethane dianhydride and the like can be mentioned.

The polyimide of the present embodiment preferably contains 20 mol parts or less of the aromatic tetracarboxylic acid anhydride represented by the above general formula (6) with respect to 100 mol parts of the acid anhydride component of the raw material. , More preferably 15 mol parts or less. When the amount of the aromatic tetracarboxylic dianhydride represented by the above general formula (6) is more than 20 parts by mole with respect to 100 parts by mole of the total acid anhydride component of the raw material, the orientation of the molecule is lowered. , It becomes difficult to reduce CTE. As a typical example of the aromatic tetracarboxylic dianhydride represented by the general formula (6), 2,3', 3,4'-diphenyl ether tetracarboxylic dianhydride, 3,3', 4,4'- Examples thereof include diphenylsulfonetetracarboxylic dianhydride (DSDA), 4,4'-oxydiphthalic acid anhydride (ODPA), 2,3', 3,4'-diphenyltetracarboxylic dianhydride and the like.

<Diamine>
The polyimide of the present embodiment has at least one aromatic diamine (diamine I) selected from the group consisting of aromatic diamines represented by the above general formulas (1) and (2) as a raw material diamine component, and At least one aromatic diamine (diamine II) selected from the group consisting of aromatic diamines represented by the above general formulas (3) to (5) is used. Diamine I can suppress the increase in CTE and improve Tg by controlling the orientation of molecules in polyimide. From such a viewpoint, the diamine I is preferably in the range of 60 to 90 mol parts, preferably in the range of 70 to 90 mol parts with respect to 100 mol parts of the total diamine component of the raw material. Since Diamine II has a flexible portion, it can impart flexibility to the polyimide. Here, when the number of benzene rings in the diamine II is 3 or 4, the amino group bonded to the benzene ring needs to be in the para position in order to suppress the increase in CTE. From such a viewpoint, the diamine II is preferably in the range of 10 to 40 mol parts, preferably in the range of 10 to 30 mol parts with respect to 100 mol parts of the total diamine component of the raw material. If the amount of diamine II charged is less than 10 mol parts with respect to 100 mol parts of the total diamine component of the raw material, the elongation of the film is lowered, and the bending resistance and the like are lowered. On the other hand, if the amount of diamine II charged exceeds 40 mol, the orientation of the molecule is lowered and it becomes difficult to reduce the CTE.

In the general formula (1), preferred examples of the groups R ₁ and R ₂ are an alkyl group that may be substituted with a hydrogen atom or a halogen atom having 1 to 3 carbon atoms, or an alkoxy group or an alkenyl having 1 to 3 carbon atoms. The group can be mentioned. Preferred specific examples of the aromatic diamine represented by the general formula (1) are 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'-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) and the like can be mentioned.

Preferred specific examples of the aromatic diamine represented by the general formula (2) include p-phenylenediamine (p-PDA) and m-phenylenediamine (m-PDA).

In the general formula (3), preferred examples of the groups R ₁ and R ₂ are an alkyl group that may be substituted with a hydrogen atom or a halogen atom having 1 to 4 carbon atoms, or an alkoxy group or an alkenyl having 1 to 3 carbon atoms. The group can be mentioned. Further, in the general formula (3), preferred examples of the linking group X include -O-, -S-, -CH _2- , -CH (CH ₃ ) _2- , -SO _2- or -CO-. be able to. Preferred specific examples of the aromatic diamine represented by the general formula (3) are 4,4'-diaminodiphenyl ether (4,4'-DAPE), 3,3'-diaminodiphenyl ether, and 3,4'-diaminodiphenyl ether. 4,4'-Diaminodiphenylmethane, 3,3'-diaminodiphenylmethane, 3,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylpropane, 3,3'-diaminodiphenylpropane, 3,4'-diaminodiphenyl Propane, 4,4'-diaminodiphenylsulfide, 3,3'-diaminodiphenylsulfide, 3,4'-diaminodiphenylsulfide, 4,4'-diaminodiphenylsulfone, 3,3′-diaminodiphenylsulfone, 4,4 '-Diaminobenzophenone, 3,4'-diaminobenzophenone, 3,3'-diaminobenzophenone and the like can be mentioned.

In the general formula (4), group Preferred examples of R _1, R ₂ and R ₃ is a hydrogen atom or an alkyl group optionally substituted by a halogen atom having 1 to 4 carbon atoms or alkoxy of 1 to 3 carbon atoms, Groups or alkoxy groups can be mentioned. Further, in the general formula (4), preferred examples of the linking group X include -O-, -S-, -CH _2- , -CH (CH ₃ ) _2- , -SO _2- or -CO-. be able to. Preferred specific examples of the aromatic diamine represented by the general formula (4) are 1,3-bis (4-aminophenoxy) benzene (TPE-R) and 1,4-bis (4-aminophenoxy) benzene ( TPE-Q), bis (4-aminophenoxy) -2,5-di-tert-butylbenzene (DTBAB), 4,4-bis (4-aminophenoxy) benzophenone (BACK), 1,3-bis [2] -(4-Aminophenyl) -2-propyl] benzene 1,4-bis [2- (4-aminophenyl) -2-propyl] benzene and the like can be mentioned.

In the general formula (5), preferred examples of groups _{R 1,} R 2, _{R 3} and _{R 4} is a hydrogen atom or an alkyl group optionally substituted by a halogen atom having 1 to 4 carbon atoms or carbon atoms 1, The alkoxy group or the alkenyl group of 3 can be mentioned. Further, in the general formula (5), preferred examples of the linking groups X and X1 are single bond, -O-, -S-, -CH _2- , -CH (CH ₃ ) _2- , -SO _2- or. -CO- can be mentioned. However, from the viewpoint of imparting bending site, shall unless both of the linking groups X and X ₁ is a single bond. Preferred specific examples of the aromatic diamine represented by the general formula (5) are 4,4'-bis (4-aminophenoxy) biphenyl (BABP) and 2,2'-bis [4- (4-aminophenoxy). ) Phenyl] propane (BAPP), 2,2'-bis [4- (4-aminophenoxy) phenyl] ether (BAPE), bis [4- (4-aminophenoxy) phenyl] sulfone and the like.

Examples of other amines include 2,2-bis- [4- (3-aminophenoxy) phenyl] propane, bis [4- (3-aminophenoxy) phenyl] sulfone, and bis [4- (3-aminophenoxy) phenyl]. ) Biphenyl, bis [1- (3-aminophenoxy)] biphenyl, 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-xylidine, 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-amino) Pentyl) 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 and the like can be mentioned.

Further, in the polyimide of the present embodiment, the ratio (A / B) of the total (A) of NTCDA and diamine I to the total (B) of BPDA and diamine II is within the range of 1.6 to 4.0. It is preferably in the range of 1.6 to 3.3. By controlling the ratio of NTCDA and diamine I used to impart the rigidity of the polyimide and BPDA and diamine II used to impart the flexibility and low elastic modulus of the polyimide, the film characteristics of the polyimide can be improved. It is possible to improve. When the ratio (A / B) is less than 1.6, the orientation of the molecules in the polyimide is lowered, it becomes difficult to reduce the CTE, and the Tg is lowered. If it exceeds 4.0, the elongation of the film is lowered, and the elastic modulus is changed to a high elastic modulus, so that the bending resistance and the like are lowered.

In the polyimide of the present embodiment, by selecting the types of the acid anhydride and diamine and the molar ratio of each when two or more kinds of acid anhydride or diamine are used, thermal expansion, adhesiveness, and glass The transition temperature (Tg) and the like can be controlled.

The polyimide according to the present embodiment can be produced by reacting the above-mentioned acid anhydride component with the above-mentioned diamine component in a solvent to generate polyamic acid, and then heat-closing the ring. For example, it is a precursor of polyimide by dissolving an acid anhydride component and a diamine component in an organic solvent in approximately equimolar amounts, stirring at a temperature in the range of 0 to 100 ° C. for 30 minutes to 24 hours, and carrying out a polymerization reaction. Polyamic acid is obtained. In the reaction, the reaction components are dissolved in the organic solvent so that the precursor produced is in the range of 5 to 30% by weight, preferably in the range of 10 to 20% by weight. Examples of the organic solvent used in the polymerization reaction include N, N-dimethylformamide (DMF), N, N-dimethylacetamide (DMAc), N, N-diethylacetamide, N-methyl-2-pyrrolidone (NMP), 2 -Butanone, dimethyl sulfoxide (DMSO), hexamethylphospholamide, N-methylcaprolactam, dimethyl sulfate, cyclohexanone, dioxane, tetrahydrofuran, diglime, triglime, cresol and the like can be mentioned. Two or more of these solvents can be used in combination, and aromatic hydrocarbons such as xylene and toluene can be used in combination. The amount of such an organic solvent used is not particularly limited, but the amount used may be adjusted so that the concentration of the polyamic acid solution obtained by the polymerization reaction is about 5 to 30% by weight. Is preferable.

The synthesized polyamic acid is usually advantageous to be used as a reaction solvent solution, but can be concentrated, diluted or replaced with another organic solvent if necessary. In addition, polyamic acid is generally excellent in solvent solubility and is therefore used advantageously. The viscosity of the polyamic acid solution is preferably in the range of 500 cP to 100,000 cP. If it is out of this range, defects such as thickness unevenness and streaks are likely to occur in the film during coating work by a coater or the like. The method for imidizing the polyamic acid is not particularly limited, and for example, a heat treatment such as heating in the solvent under a temperature condition in the range of 80 to 400 ° C. for 1 to 24 hours is preferably adopted.

[Resin film]
The resin film of the present embodiment is not particularly limited as long as it is an insulating resin film containing a polyimide layer formed from the polyimide of the present embodiment, and may be a film (sheet) made of an insulating resin. Often, it may be an insulating resin film in a state of being laminated on a base material such as a resin sheet such as a copper foil, a glass plate, a polyimide film, a polyamide film, or a polyester film. The thickness of the resin film of the present embodiment is preferably in the range of 3 to 100 μm, more preferably in the range of 3 to 75 μm.

The polyimide of the present embodiment is preferably applied as a base film layer (main layer of an insulating resin layer). Specifically, the coefficient of linear thermal expansion (CTE) is preferably in the range of 5 × 10 ^{-6 to} 20 × 10 ^-6 (1 / K), more preferably 10 × 10 ^{-6 to} 20 × 10 ^-6 (1 / K). When a low thermal expansion polyimide layer in the range of 1 / K) is applied to the base film layer, a great effect can be obtained. Among the low thermal expansion polyimides, a polyimide that can be preferably used is a non-thermoplastic polyimide. When the polyimide of the present embodiment is used to form a low thermal expansion base film layer, the thickness is preferably in the range of 5 to 50 μm, more preferably in the range of 10 to 35 μm.

On the other hand, a highly expandable polyimide layer having a coefficient of linear thermal expansion (CTE) exceeding the above is also preferably applied as an adhesive layer to a base material such as a metal layer or another resin layer. As the polyimide that can be suitably used as such an adhesive polyimide layer, a polyimide having a glass transition temperature (Tg) of, for example, 360 ° C. or lower is preferable, and a polyimide having a glass transition temperature (Tg) in the range of 200 to 320 ° C. is more preferable.

To obtain a highly expandable polyimide layer, for example, pyromellitic dianhydride, 3,3', 4,4'-biphenyltetracarboxylic dianhydride, 3,3', as an acid anhydride component of the raw material 4,4'-Benzenephenone tetracarboxylic dianhydride, 3,3', 4,4'-diphenylsulfonetetracarboxylic dianhydride, as a diamine component, 2,2'-bis [4- (4- (4- (4- (4-) Aminophenoxy) phenyl] propane, 4,4'-diaminodiphenyl ether, 1,3-bis (4-aminophenoxy) benzene are preferably used, and particularly preferably pyromellitic dianhydride and 2,2'-bis [ 4- (4-Aminophenoxy) phenyl] Propane should be the main component of each component of the raw material.

The method for forming the polyimide film as the resin film of the present embodiment is not particularly limited. For example, [1] a polyimide film is produced by applying a polyamic acid solution to a supporting base material, drying the film, and then imidizing the polyimide film. A method (hereinafter referred to as a casting method), [2] a method of applying a polyamic acid solution to a support base material, drying it, peeling the polyamic acid gel film from the support base material, and imidizing the support base material to produce a polyimide film. Can be mentioned. When the polyimide film produced in the present invention is composed of a plurality of polyimide resin layers, as an embodiment of the production method, for example, [3] a support base material is coated with a polyamic acid solution and dried. After repeating the above multiple times, imidization is performed (hereinafter referred to as the sequential coating method). [4] The support substrate is simultaneously coated and dried with a laminated structure of polyamic acid by multi-layer extrusion, and then imidization is performed. Examples thereof include a method (hereinafter referred to as a multilayer extrusion method). The method of applying the polyimide solution (or polyamic acid solution) on the substrate is not particularly limited, and for example, it can be applied with a coater such as a comma, a die, a knife, or a lip. When forming the multilayer polyimide layer, a method of repeatedly applying a polyimide solution (or a polyamic acid solution) to the substrate and drying the substrate is preferable.

The resin film of the present embodiment may include a single layer or a plurality of layers of polyimide layers. In this case, at least one layer (preferably a base film layer) of the polyimide layer may be formed by using the polyimide of the present embodiment. For example, assuming that the non-thermoplastic polyimide layer is P1 and the thermoplastic polyimide layer is P2, it is preferable to laminate the resin film in a combination of P2 / P1 when the resin film is two layers, and when the resin film is three layers. Is preferably laminated in the order of P2 / P1 / P2 or P2 / P1 / P1. Here, P1 becomes a base film layer formed by using the polyimide of the present embodiment. In addition, P2 may be composed of polyimide other than the polyimide of this embodiment.

The resin film of the present embodiment may contain an inorganic filler in the polyimide layer, if necessary. Specific examples thereof include silicon dioxide, aluminum oxide, magnesium oxide, beryllium oxide, boron nitride, aluminum nitride, silicon nitride, aluminum fluoride and calcium fluoride. These can be used alone or in admixture of two or more.

The resin film of the present embodiment applied as a low thermal expansion polyimide film can be applied, for example, as a coverlay film material in a coverlay film. An arbitrary adhesive layer can be laminated on the resin film of the present embodiment to form a coverlay film. The thickness of the coverlay film material layer is not particularly limited, but is preferably 5 μm or more and 100 μm or less, for example. The thickness of the adhesive layer is not particularly limited, but is preferably 15 μm or more and 50 μm or less, for example.

[Metal-clad laminate]
The metal-clad laminate of the present embodiment has an insulating resin layer and a metal layer laminated on at least one surface of the insulating resin layer. A preferable specific example of the metal-clad laminate is, for example, a copper-clad laminate (CCL).

<Insulation resin layer>
In the metal-clad laminate of the present embodiment, the insulating resin layer has a single layer or a plurality of polyimide layers. In this case, in order to impart excellent high-frequency characteristics to the metal-clad laminate, at least one layer (preferably a base film layer) of the polyimide layer may be formed using the polyimide of the present embodiment. Further, in order to enhance the adhesiveness between the insulating resin layer and the metal layer, the layer of the insulating resin layer in contact with the metal layer is preferably a thermoplastic polyimide layer. For example, when the insulating resin layer is two layers, if the non-thermoplastic polyimide layer is P1, the thermoplastic polyimide layer is P2, and the metal layer is M1, it is preferable to stack P1 / P2 / M1 in this order. Here, P1 becomes a base film layer formed by using the polyimide of the present embodiment. In addition, P2 may be composed of polyimide other than the polyimide of this embodiment.

<Metal layer>
The material of the metal layer in the metal-clad laminate of the present embodiment is not particularly limited, but for example, copper, stainless steel, iron, nickel, berylium, aluminum, zinc, indium, silver, gold, tin, zirconium, and tantalum. , Titanium, lead, magnesium, manganese and alloys thereof. Of these, copper or copper alloys are particularly preferable. The material of the wiring layer in the circuit board of the present embodiment described later is also the same as that of the metal layer.

When a high-frequency signal is supplied to the signal wiring, the current flows only on the surface of the signal wiring, and the effective cross-sectional area where the current flows decreases, the DC resistance increases, and the signal attenuates (skin effect). is there. By lowering the surface roughness of the surface of the metal layer in contact with the insulating resin layer, it is possible to suppress an increase in signal wiring resistance due to this skin effect. However, if the surface roughness is lowered in order to satisfy the required electrical performance standards, the adhesive strength (peeling strength) between the metal layer and the insulating resin layer is weakened. Therefore, from the viewpoint of satisfying the electrical performance requirements and improving the visibility of the metal-clad laminate while ensuring the adhesiveness with the insulating resin layer, the surface roughness of the surface of the metal layer in contact with the insulating resin layer is determined. The ten-point average roughness Rz is preferably 1.5 μm or less, and the arithmetic average roughness Ra is preferably 0.2 μm or less.

For the metal-clad laminate of the present embodiment, for example, a resin film composed of the polyimide of the present embodiment is prepared, metal is sputtered onto the resin film to form a seed layer, and then the metal layer is formed by plating, for example. It may be prepared by forming.

Further, the metal-clad laminate of the present embodiment may be prepared by preparing a resin film composed of the polyimide of the present embodiment and laminating a metal foil on the resin film by a method such as thermocompression bonding. Good.

Further, in the metal-clad laminate of the present embodiment, a coating liquid containing polyamic acid, which is a precursor of the polyimide of the present embodiment, is cast on a metal foil, dried to form a coating film, and then heat-treated. It may be prepared by imidizing the material and forming a polyimide layer.

[Circuit board]
The circuit board of the present embodiment has an insulating resin layer and a wiring layer formed on the insulating resin layer. In the circuit board of the present embodiment, the insulating resin layer may have a single layer or a plurality of polyimide layers. In this case, in order to impart excellent high frequency characteristics to the circuit board, at least one layer (preferably a base film layer) of the polyimide layer may be formed by using the polyimide of the present embodiment. Further, in order to enhance 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 formed by using the polyimide of the present embodiment. For example, when the insulating resin layer is two layers, if the non-thermoplastic polyimide layer is P1, the thermoplastic polyimide layer is P2, and the wiring layer is M2, it is preferable to stack P1 / P2 / M2 in this order. Here, P1 becomes a base film layer formed by using the polyimide of the present embodiment. In addition, P2 may be composed of polyimide other than the polyimide of this embodiment.

A method for producing a circuit board is not limited except that the polyimide of the present embodiment is used. For example, a subtractive method may be used in which a metal-clad laminate composed of an insulating resin layer containing polyimide and a metal layer of the present embodiment is prepared and the metal layer is etched to form wiring. Further, a semi-additive method may be used in which the seed layer is formed on the polyimide layer of the present embodiment, the resist is patterned, and the metal layer is pattern-plated to form the wiring.

As described above, by using the polyimide of the present embodiment, it is possible to form a metal-clad laminate with a small transmission loss.

Examples will be shown below, and the features of the present invention will be described in more detail. However, the scope of the present invention is not limited to the examples. In the following examples, various measurements and evaluations are as follows unless otherwise specified.

[Measurement of glass transition temperature (Tg)]
The glass transition temperature is a heating rate of a polyimide film having a size of 5 mm × 20 mm from 30 ° C. to 400 ° C. using a dynamic viscoelasticity measuring device (DMA: manufactured by UBM, trade name: E4000F). The measurement was performed at 4 ° C./min and a frequency of 11 Hz, and the temperature was determined from the maximum temperature of tan δ based on the main dispersion.

[Measurement of coefficient of linear 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). Further, after holding at that temperature for 10 minutes, the film was cooled at a rate of 5 ° C./min to obtain an average coefficient of thermal expansion (linear thermal expansion coefficient) from 250 ° C. to 100 ° C.

[Measurement of permittivity in the thickness direction]
Using a cavity resonator perturbation method dielectric constant evaluation device (manufactured by Agilent, trade name; vector network analyzer E8633B), the dielectric constant in the thickness direction of the resin sheet (resin sheet after curing) at a predetermined frequency was measured.
Two samples are prepared by laminating three resin sheets having a thickness of about 25 μm, and the sample is circular so as to have a laminated structure of circular copper foil / three resin sheets / conductor flat plate / three resin sheets / circular copper foil. Three resin sheets were sandwiched between the copper foil and the conductor flat plate, and the measurement was carried out. The resin sheet used for the measurement was left to stand for 24 hours under the conditions of temperature: 24-26 ° C. and humidity: 45-55%.

[Evaluation of film forming property]
Regarding the film-forming property, the self-supporting property of a film obtained by coating a copper foil with a polyamic acid, heat-treating it, and then etching the copper foil with an aqueous solution of ferric chloride was evaluated.
"○": The film etched with copper foil does not easily crack.
"X": The film etched with copper foil easily cracks and has no self-supporting property.

The abbreviations used in Examples and Comparative Examples indicate the following compounds.
m-TB: 2,2'-dimethyl-4,4'-diaminobiphenyl m-EOB: 2,2'-diethoxy-4,4'-diaminobiphenyl 4,4'-DAPE: 4,4'-diaminodiphenyl ether TPE-R: 1,3-bis (4-aminophenoxy) benzene p-PDA: p-phenylenediamine BAPP: 2,2-bis [4- (4-aminophenoxy) phenyl] propane BABP: 4,4'- Bis (4-aminophenoxy) biphenyl NTCDA: 2,3,6,7-naphthalenetetracarboxylic dianhydride PMDA: pyromellitic dianhydride BPDA: 3,3', 4,4'-biphenyltetracarboxylic dianhydride ODPA anhydride: 4,4'-oxydiphthalic anhydride DMAc: N, N-dimethylacetamide

[Synthesis Example A-1]
Under a nitrogen stream, 11.467 g of m-TB (0.0540 mol), 1.755 g of TPE-R (0.0060 mol) and 170.0 g of DMAc were placed in a 300 ml separable flask at room temperature. Was stirred and dissolved. Next, 10.436 g of BPDA (0.0355 mol) and 6.342 g of NTCDA (0.0237 mol) were added, and then the polymerization reaction was carried out by continuing stirring at room temperature for 3 hours to carry out the polymerization reaction, and the polyamic acid solution Aa. Got The solution viscosity of the polyamic acid solution AA was 38,100 cps.

[Synthesis Examples A-2 to A-19]
Polyamide acid solutions Ab to As were prepared in the same manner as in Synthesis Example A-1, except that the raw material compositions shown in Tables 1 to 3 were used. In addition, "A / B" in Tables 1 to 3 means the ratio (A / B) of the total (A) of NTCDA and diamine I to the total (B) of BPDA and diamine II.

[Example A-1]
The polyamic acid solution A-a prepared in Synthesis Example A-1 is uniformly applied to one side (surface roughness Rz; 2.1 μm) of an electrolytic copper foil having a thickness of 12 μm so that the thickness after curing is about 25 μm. After that, the solvent was removed by heating and drying at 120 ° C. Further, a stepwise heat treatment from 120 ° C. to 360 ° C. was performed within 30 minutes to complete imidization. A copper foil was etched and removed from the obtained metal-clad laminate with an aqueous ferric chloride solution to obtain a resin film A-1. The polyimide constituting the resin film A-1 was non-thermoplastic.
The linear thermal expansion coefficient of the resin film A-1, the glass transition temperature, and the dielectric constant in the thickness direction were determined, and the film-forming property was confirmed. The measurement results are shown in Table 4.

[Examples A-2 to A-10, Comparative Examples A-11 to A-18]
Resin films A-2 to A of Examples A-2 to A-10 and Comparative Examples A-11 to A-18 in the same manner as in Example A-1 except that the polyamic acid solution shown in Table 4 was used. -18 was obtained. The linear thermal expansion coefficient, the glass transition temperature, and the dielectric constant in the thickness direction of the obtained resin films A-2 to A-18 were determined, and the film-forming property was confirmed. The measurement results are shown in Tables 4 to 6.

[Example B-1]
A polyamic acid solution As was uniformly applied to one side (surface roughness Rz; 1.39 μm) of an electrolytic copper foil having a thickness of 12 μm so that the cured thickness would be about 2 to 3 μm, and then at 120 ° C. The solvent was removed by heating and drying. Next, the polyamic acid solution AC was uniformly applied thereto so that the thickness after curing was about 21 μm, and the mixture was heated and dried at 120 ° C. to remove the solvent. Further, a polyamic acid solution As was uniformly applied thereto so that the thickness after curing was about 2 to 3 μm, and then the solvent was removed by heating and drying at 120 ° C. After forming the three polyamic acid layers in this way, a stepwise heat treatment from 120 ° C. to 360 ° C. was performed within 30 minutes to complete imidization, and a metal-clad laminate was obtained. A copper foil was etched and removed from the obtained metal-clad laminate with an aqueous ferric chloride solution to obtain a resin film B-1. The CTE of the obtained film was 24.1 ppm / K, and the dielectric constant in the thickness direction was 2.93 at 14 GHz.

Although the embodiments of the present invention have been described in detail for the purpose of exemplification, the present invention is not limited to the above embodiments and can be modified in various ways.

Claims (5)

A polyimide obtained by reacting an acid anhydride component containing an aromatic tetracarboxylic dianhydride with a diamine component containing an aromatic diamine.
Conditions (i) to (iii) below;
(I) With respect to 100 mol parts of the acid anhydride component
2,3,6,7-Naphthalenetetracarboxylic dianhydride (NTCDA) is contained in the range of 40 to 80 mol parts, and 3,3', 4,4'-biphenyltetracarboxylic dianhydride (BPDA) is contained. ) In the range of 20 to 60 mol parts;
(Ii) As the diamine component, an aromatic diamine represented by the following general formula (1) is essentially contained, and with respect to 100 mol parts of the diamine component,
It contains at least one aromatic diamine (diamine I) selected from the group consisting of aromatic diamines represented by the following general formulas (1) and (2) in the range of 60 to 90 mol parts.
At least one aromatic diamine (diamine II) selected from the group consisting of aromatic diamines represented by the following general formulas (3) to (5) shall be contained in the range of 10 to 40 mol parts;
(Iii) The ratio (A / B) of the total (A) of NTCDA and diamine I to the total (B) of BPDA and diamine II is in the range of 1.6 to 4.0;
A polyimide characterized by satisfying.

[In formula (1), R ₁ and R ₂ each represent an alkyl group, an alkoxy group or an alkenyl group which may be independently substituted with a hydrogen atom or a halogen atom having 1 to 4 carbon atoms, and m and n are 1. Indicates an integer of ~ 4. ]

[In formula (3), R ₁ and R ₂ represent an alkyl group, an alkoxy group or an alkenyl group which may be independently substituted with a hydrogen atom, a halogen atom, or a halogen atom having 1 to 4 carbon atoms, respectively, and X. Is -O-, -S-, -CH _2- , -CH (CH ₃ )-, -C (CH ₃ ) _2- , -CO-, -COO-, -SO _2- , -NH- or -NHCO Indicates a divalent group selected from −, where m and n independently represent integers 1 to 4. ]

[In formula (4), R ₁ , R ₂ and R ₃ each independently contain an alkyl group, an alkoxy group or an alkenyl group which may be substituted with a hydrogen atom, a halogen atom, or a halogen atom having 1 to 4 carbon atoms. Indicated, X is -O-, -S-, -CH _2- , -CH (CH ₃ )-, -C (CH ₃ ) _2- , -CO-, -COO-, -SO _2- , -NH- Alternatively, it represents a divalent group selected from -NHCO-, where m, n and o independently represent integers 1 to 4. ]

[In formula (5), R ₁ , R ₂ , R ₃ and R ₄ are each independently substituted with a hydrogen atom, a halogen atom, or a halogen atom having 1 to 4 carbon atoms, an alkyl group, an alkoxy group, or the like. Representing an alkoxy group, X and X ₁ are single bonds, -O-, -S-, -CH _2- , -CH (CH ₃ )-, -C (CH ₃ ) _2- , -CO-, -COO- , -SO _2- , -NH- or -NHCO-, indicating a divalent group, except when both X and X ₁ are single bonds, and m, n, o and p are independent. Indicates an integer of 1 to 4. ] The polyimide according to claim 1, wherein the amount of the aromatic tetracarboxylic dianhydride represented by the following general formula (6) is 20 parts by mole or less with respect to 100 parts by mole of the acid anhydride component. ..

[In formula (6), A represents a divalent group selected from -O-, -S-, -C (CH ₃ ) _2- , -C (CF ₃ ) _2- or -SO _2- . ] A resin film comprising the polyimide according to claim 1 or 2. The resin film according to claim 3, wherein the coefficient of linear thermal expansion is in the range of 5 × 10 ^{-6 to} 20 × 10 ^-6 (1 / K). A metal-clad laminate having an insulating resin layer and a metal layer.
The resin insulating layer has a single layer or a plurality of polyimide layers.
At least one of the polyimide layers is a polyimide layer comprising the polyimide according to claim 1 or 2 and having a linear thermal expansion coefficient in the range of 5 × 10 ^{-6 to} 20 × 10 ^-6 (1 / K). A metal-clad laminate characterized by being present.