JP2021055057A - Production method of polyimide film and production method of metal-clad laminate - Google Patents

Abstract

To provide a production method of a polyimide film by a cast method, in which both reduction of CTE and uniformization of orientation distribution in a film thickness direction are achieved.SOLUTION: A polyimide film of which the resin component is composed of non-thermoplastic polyimide is produced by: laminating a polyamic acid containing a diamine residue derived from a diamine component and an acid anhydride residue derived from an acid anhydride component on a base material; and imidizing the polyamic acid by heat treatment with an infrared heater. Based on 100 pts.mol of the total diamine residue, the non-thermoplastic polyimide has 50 pts.mol or more of the diamine residue derived from a diamine compound represented by a formula (1).SELECTED DRAWING: None

Description

The present invention relates to a method for producing a polyimide film and a method for producing a metal-clad laminate.

Polyimide is widely used in electronic, electrical equipment, and electronic components as a material for circuit boards and the like because it has features such as high insulation, dimensional stability, easy molding, and light weight. Polyimide is generally used in the form of a film (polyimide film) or a layered layer (polyimide layer) laminated on an arbitrary base material. In the present invention, the "polyimide film" includes the state of the polyimide layer. As a method for forming a polyimide film, a resin solution of polyamic acid, which is a precursor of polyimide, is applied onto a substrate to form a coating film, and the coating film is dried and imidized to obtain a polyimide film (so-called). Cast method) is known.

In the casting method, a solution of polyamic acid is applied to the base material, dried and cured, so the solvent volatilizes only from the surface side where the base material does not exist, and in addition, the base material is directly exposed to heat. Only from the non-existent surface side. Therefore, on the surface (surface layer portion) directly exposed to heat, the orientation and imidization of the molecules tend to proceed, and the polyimide film formed tends to have a difference in the orientation distribution in the thickness direction. This tendency becomes more remarkable as the resin composition is more likely to form an orientation, that is, to have a low coefficient of thermal expansion (CTE).

Patent Document 1 proposes thermosetting using far infrared rays in order to perform uniform imidization of a polyamic acid coating film by a casting method in a short time.

By the way, in a copper-clad laminate (CCL) using polyimide, the insulating resin layer has a three-layer structure of a bottom layer / a base layer / a top layer, and the thickness of the bottom layer and the top layer is intentionally changed. The occurrence of warpage was suppressed when the base layer had an orientation distribution. Therefore, it is necessary to provide a bottom layer and a top layer having a certain thickness or more, and it is difficult to make the insulating resin layer thin and to design with an emphasis on the characteristics of the resin constituting the base layer.

As an evaluation of the orientation distribution, it is effective to evaluate the warp of the polyimide film single film. This is because the orientation distribution occurs in the thickness direction, so that the CTE in the thickness direction also has a distribution, and warpage occurs due to heat shrinkage during cooling. In Patent Document 2, as a flexible metal laminate having excellent high-temperature processability and good adhesiveness, a flexible metal laminate having a single-layer polyimide layer obtained by using a specific acid anhydride component and a diamine component as raw materials is described. Although it has been proposed, no consideration is given to the orientation distribution of the polyimide layer in the thickness direction.

Japanese Unexamined Patent Publication No. 2006-192861 Japanese Unexamined Patent Publication No. 2010-53322

As described above, the polyimide film produced by the casting method had a trade-off relationship between low CTE and uniform orientation distribution in the thickness direction of the film.
Therefore, an object of the present invention is to provide a method for producing a polyimide film having both low CTE and uniform orientation distribution in the thickness direction of the film by a casting method.

As a result of diligent research, the present inventors have found that the above problems can be solved by imidizing a polyamic acid having a specific resin composition using an infrared heater as a means of heat treatment, and have completed the present invention.

That is, in the method for producing a polyimide film of the present invention, a polyamic acid solution containing a diamine residue derived from a diamine component and an acid anhydride residue derived from an acid anhydride component is placed on a substrate. This is a method for producing a polyimide film, which comprises a step of forming a polyimide film in which the resin component is made of a non-thermoplastic polyimide by coating and imidizing by heat treatment with an infrared heater. The method for producing a polyimide film of the present invention is a method for producing a diamine residue derived from a diamine compound represented by the following general formula (1) with respect to 100 mol parts of all diamine residues contained in the non-thermoplastic polyimide. The group is characterized by having 50 mol parts or more.

In the formula (1), the linking group Z represents a single bond or −COO−, and Y is a monovalent hydrocarbon group having 1 to 3 carbon atoms or 1 carbon number which may be independently substituted with a halogen atom or a phenyl group. It represents an alkoxy group of ~ 3 or a perfluoroalkyl group or an alkenyl group having 1 to 3 carbon atoms, n represents an integer of 1 or 2, and p and q independently represent an integer of 0 to 4.

In the method for producing a polyimide film of the present invention, a diamine residue derived from the diamine compound represented by the general formula (1) is added to 100 mol parts of all diamine residues contained in the non-thermoplastic polyimide. It may be in the range of 50 to 99 mol parts, and the diamine residue derived from the diamine compound represented by the following general formula (2) may be in the range of 1 to 50 mol parts.

In formula (2), R is independently an alkyl group or an alkoxy group which may be substituted with a halogen atom or a halogen atom having 1 to 6 carbon atoms, or a monovalent hydrocarbon group or alkoxy having 1 to 6 carbon atoms. Indicates a phenyl or phenoxy group that may be substituted with a group, where Z ₁ is an independent single bond, -O-, -S-, -CH _2- , -CH (CH ₃ )-, -C (CH ₃ ). _It represents a divalent group selected from _2- , -CO-, -SO _{2-, or -NH-, where n 3} independently represents an integer 0-4 and n ₄ represents an integer 0-2. However, _{at least one of Z 1} is -O-, -S-, -CH _2- , -CH (CH ₃ )-, -C (CH ₃ ) _2- , -CO-, -SO _2- , or-. The divalent group selected from NH- is shown.

In the method for producing a polyimide film of the present invention, the diamine compound represented by the general formula (1) may be a diamine compound represented by the following general formula (A1).

一般式（Ａ１）において、Ｘは独立にフッ素原子で置換されてもよい炭素数１〜３のアルキル基を示し、ｎ₁及びｎ_２は独立に１〜４の整数を示す。

In the general formula (A1), X represents an alkyl group having 1 to 3 carbon atoms which may be independently substituted with a fluorine atom, and n ₁ and n ₂ independently represent an integer of 1 to 4.

The method for producing a polyimide film of the present invention is a 3,3', 4,4'-biphenyltetracarboxylic dianhydride (3,3', 4,4'-biphenyltetracarboxylic dianhydride, based on 100 mol parts of total acid anhydride residue contained in the non-thermoplastic polyimide. The BPDA residue derived from BPDA) may be in the range of 20 to 70 mol parts.

In the method for producing a polyimide film of the present invention, a polyimide film having a coefficient of thermal expansion (CTE) of less than 20 ppm / K and a 50 mm square polyimide after 20 hours of humidity control under the conditions of 23 ° C. and 50% humidity. When the convex surface of the central portion of the film is allowed to stand in contact with a flat surface and the average value of the amount of floating of the four corners is taken as the average amount of warpage, the average amount of warpage may be 15 mm or less.

In the method for producing a polyimide film of the present invention, the thickness of the polyimide film may be in the range of 5 to 80 μm.

In the method for producing a polyimide film of the present invention, the heat treatment may be performed on the substrate.

The method for producing a metal-clad laminate of the present invention is a method for producing a metal-clad laminate comprising an insulating resin layer and a metal layer laminated on one side or both sides of the insulating resin layer.
In the method for producing a metal-clad laminate of the present invention, the insulating resin layer has a polyimide layer in which the resin component is a non-thermoplastic polyimide.
Further, in the method for producing a metal-clad laminate of the present invention, a polyamic acid containing a diamine residue derived from a diamine component and an acid anhydride residue derived from an acid anhydride component is placed on a metal foil. It includes a step of forming the polyimide layer by directly or indirectly laminating the polyimide layer and imidizing the polyimide layer by a heat treatment with an infrared heater.
Then, the method for producing a metal-clad laminate of the present invention is derived from a diamine compound represented by the following general formula (1) with respect to 100 mol parts of all diamine residues contained in the non-thermoplastic polyimide. It is characterized in that the diamine residue is 50 mol parts or more.

式（１）において、連結基Ｚは単結合若しくは−ＣＯＯ−を示し、Ｙは独立にハロゲン原子若しくはフェニル基で置換されてもよい炭素数１〜３の１価の炭化水素基又は炭素数１〜３のアルコキシ基、又は炭素数１〜３のパーフルオロアルキル基、又はアルケニル基を示し、ｎは１又は２の整数を示し、ｐ及びｑは独立に０〜４の整数を示す。

In the formula (1), the linking group Z represents a single bond or −COO−, and Y is a monovalent hydrocarbon group having 1 to 3 carbon atoms or 1 carbon number which may be independently substituted with a halogen atom or a phenyl group. It represents an alkoxy group of ~ 3 or a perfluoroalkyl group or an alkenyl group having 1 to 3 carbon atoms, n represents an integer of 1 or 2, and p and q independently represent an integer of 0 to 4.

According to the present invention, by imidizing a polyamic acid having a specific resin composition using an infrared heater as a means of heat treatment, it is possible to achieve both low CTE reduction of the polyimide film and uniform orientation distribution. It will be possible. The method of the present invention can also be applied to the production of, for example, a single-layer polyimide film for CCL, a single-layer polyimide film for POP (package on package), a single-layer polyimide film for semi-additive (SAP), and the like. is there. Therefore, the method of the present invention is particularly useful in the manufacturing process of an industrial-scale polyimide film, and has high utility value.

The method for producing a polyimide film according to an embodiment of the present invention is
(1) A coating film forming step of forming a coating film by applying a polyamic acid solution to a substrate,
(2) The first heat treatment step of heat-treating the coating film to dry it.
(3) A second heat treatment step of forming a polyimide film by imidizing the polyamic acid by heat-treating the dried coating film with an infrared heater.
Can be included.

When a plurality of polyimide layers are laminated, the coating film forming step and the first heat treatment step can be repeatedly carried out before the second heat treatment step. That is, a solution of polyamic acid is applied to the base material and dried is repeated a plurality of times to obtain a state in which a plurality of coating films are laminated, and then a second heat treatment step is carried out to carry out the second heat treatment step to obtain the polyamic acid in the plurality of coating films. It is preferable to imidize all at once. In this case, one of the plurality of polyimide layers may be a polyimide film produced by the method of the present embodiment.

Hereinafter, each step will be described in detail.

[Coating film forming process]
In the coating film forming step, a coating film is formed by applying a polyamic acid solution to the substrate.

As the base material, for example, a metal foil such as a copper foil, a glass plate, a polyimide film, a polyamide film, a resin sheet such as a polyester film, or the like can be used.

For polyamic acid, which is a precursor of polyimide, for example, acid dianhydride, which is a raw material monomer, and a diamine compound are dissolved in an organic solvent in approximately equimolar amounts, and the temperature is in the range of 0 to 100 ° C. for 30 minutes to 24. It is obtained by stirring for a time and causing a polymerization reaction.

As the raw material monomers, the acid dianhydride and the diamine compound, those mentioned in the description of the non-thermoplastic polyimide described later can be used. The composition ratio of the raw material monomer is the same as the composition ratio of the acid anhydride residue and the diamine residue contained in the non-thermoplastic polyimide. In the present invention, the acid anhydride residue represents a tetravalent group derived from a tetracarboxylic dianhydride, and the diamine residue is a divalent group derived from a diamine compound. Represents that.

Examples of the organic solvent used in the polymerization reaction of polyamic acid include N, N-dimethylformamide (DMF), N, N-dimethylacetamide (DMAc), N, N-diethylacetamide, and N-methyl-2-pyrrolidone (NMP). ), 2-Butanone, dimethyl sulfoxide (DMSO), hexamethylphosphoramide, N-methylcaprolactam, dimethyl sulfate, cyclohexanone, dioxane, tetrahydrofuran, diglime, triglime, cresol and the like. 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 the organic solvent used is not particularly limited, but it is preferable to adjust the amount used so that the concentration of the polyamic acid solution obtained by the polymerization reaction is about 5 to 30% by weight.

The synthesized polyamic acid can usually be used as a reaction solvent solution, but can be concentrated, diluted or replaced with another organic solvent if necessary. Any of these can be used as a solution of the polyamic acid of the present embodiment.

If necessary, a filler may be contained in the polyamic acid solution. Preferred fillers include, for example, silicon dioxide, aluminum oxide, magnesium oxide, beryllium oxide, boron nitride, aluminum nitride, silicon nitride, aluminum fluoride, calcium fluoride and the like. These can be used alone or in admixture of two or more.

The method of applying the polyamic acid solution on the substrate is not particularly limited, and it is preferable to use a coater such as a comma, a die, a knife, or a lip.

The viscosity of the polyamic acid solution is preferably in the range of, for example, 500 cps to 100,000 cps. 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 thickness of the coating film in the coating film forming step is not particularly limited because it can be appropriately set according to the film thickness of the polyimide film finally obtained, but it is preferably the thickness after imidization (that is, the thickness of the polyimide film). It is preferable to apply the film so that it is within the range of 5 to 80 μm, more preferably within the range of 25 to 50 μm.

[First heat treatment step]
The first heat treatment step is a step of heat-treating the coating film to dry the solvent.
The heating means in the first heat treatment step is not particularly limited as long as the coating film can be heated to a predetermined temperature, and for example, heat drying with hot air (hot air drying), heat drying with an infrared heater, and the like are preferable. As a condition in the first heat treatment step, the heating temperature is preferably in the range of 80 to 160 ° C., and the heating time is preferably in the range of 30 seconds to 6 minutes.
In the present specification, the "heat treatment temperature" and the "heating temperature" mean the base material temperature in the heat treatment container unless otherwise specified.

[Second heat treatment step]
In the second heat treatment step, the coated film after drying is heat-treated to imidize the polyamic acid to form a polyimide film in which the resin component is polyimide. An infrared heater is used for the heat treatment in this step. Since infrared rays can be heated uniformly in the thickness direction of the coating film, imidization proceeds uniformly in the thickness direction of the coating film. Therefore, unlike hot air, imidization proceeds from the surface side of the coating film, and there is no difference in the orientation distribution in the thickness direction. Therefore, by using the infrared heater, the orientation distribution of the polyimide film can be made uniform. In addition, the infrared heater saves space and can heat evenly in the thickness direction in a short time.

The wavelength of infrared rays is preferably in the range of, for example, 1 to 8 μm, and more preferably in the range of 4 to 6 μm, as the maximum radiant energy wavelength from the viewpoint of efficiently absorbing energy of the coating film. If the maximum radiant energy wavelength is out of the above range, the imidization efficiency may decrease.

As a condition in the second heat treatment step, the heating temperature is preferably in the range of, for example, 100 to 450 ° C, more preferably in the range of 120 to 400 ° C. The heat treatment time may be appropriately set depending on the thickness of the coating film, and is preferably completed within 3 hours, more preferably within 60 minutes, at the above heating temperature. Further, it is preferable that the heat treatment is carried out by gradually raising the temperature within the above temperature range.

In this step, it is preferable to imidize the polyamic acid on the substrate. Since the polyamic acid coating film is imidized in a state of being fixed to the base material, it is possible to suppress the expansion and contraction change of the formed polyimide film and maintain the thickness and dimensional accuracy of the polyimide film.

The polyimide film obtained by the above steps has a resin component made of the non-thermoplastic polyimide described below, has a low CTE, and has suppressed warpage. The polyimide film produced by the method of the present embodiment is a single layer, and when a structure in which a plurality of polyimide layers are laminated is used, one layer among the plurality of polyimide layers is the same as that of the present embodiment. Any polyimide film produced by the method may be used.

<Non-thermoplastic polyimide>
The non-thermoplastic polyimide constituting the polyimide film contains 50 mol parts of diamine residues derived from the diamine compound represented by the following general formula (1) with respect to 100 mol parts of all diamine residues contained therein. Contains the above.

In the formula (1), the linking group Z represents a single bond or −COO−, and Y is a monovalent hydrocarbon group having 1 to 3 carbon atoms or 1 carbon number which may be independently substituted with a halogen atom or a phenyl group. It represents an alkoxy group of ~ 3 or a perfluoroalkyl group or an alkenyl group having 1 to 3 carbon atoms, n represents an integer of 1 or 2, and p and q independently represent an integer of 0 to 4. In the "diamine compound", the hydrogen atom in the two terminal amino groups may be substituted, for example, -NR ₁ R ₂ (where R ₁ and R ₂ are independently arbitrary alkyl groups and the like. It may mean a substituent).

The diamine residue derived from the diamine compound represented by the general formula (1) easily forms an ordered structure and lowers the CTE, so that dimensional stability can be improved. In addition, since it contains two or more benzene rings, it is also advantageous in improving dimensional stability to reduce the imide group concentration and contribute to low hygroscopicity. From this point of view, the diamine residue derived from the diamine compound represented by the general formula (1) is 60 to 100 mol parts with respect to 100 mol parts of all diamine residues contained in the non-thermoplastic polyimide. It is preferable that the content is within the range of. If the amount of diamine residue derived from the diamine compound represented by the general formula (1) is less than 50 mol, CTE increases and dimensional stability deteriorates.

Preferred specific examples of the diamine residue derived from the diamine compound 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'- Diamines derived from diamine compounds such as diaminobiphenyl, 4,4'-diamino-2,2'-bis (trifluoromethyl) biphenyl (TFMB), 4,4''-diamino-p-terphenyl (DATP) Residues are mentioned. Among these, 2,2'-dimethyl-4,4'-diaminobiphenyl (m-TB), 2,2'-diethyl-4,4'-diaminobiphenyl (m-EB), 4,4'-diamino -2,2'-bis (trifluoromethyl) biphenyl (TFMB), 4,4''-diamino-p-terphenyl (DATP) are mentioned as suitable, in particular 2,2'-dimethyl-4. , 4'-Diaminobiphenyl (m-TB) is most preferable because it easily forms an ordered structure, lowers the imide group concentration, and lowers the moisture absorption rate.

Further, it is more preferable that the diamine compound represented by the general formula (1) is a diamine compound represented by the following general formula (A1).

In the general formula (A1), X represents an alkyl group having 1 to 3 carbon atoms which may be independently substituted with a fluorine atom, and n ₁ and n ₂ independently represent an integer of 1 to 4.

Since the diamine compound represented by the general formula (A1) has a biphenyl skeleton and a substituent effective in suppressing the movement of molecules in the side chain, it contributes to lowering the CTE of the polyimide film. Further, the molecular orientation is determined by the resin composition containing 50 mol parts or more of the diamine residue derived from the diamine compound represented by the general formula (A1) with respect to 100 mol parts of all diamine residues. Since it does not go too far, it is possible to achieve both low CTE and suppression of warpage by reducing the orientation distribution by heat treatment with an infrared heater.

Further, the non-thermoplastic polyimide preferably contains a diamine residue derived from a diamine compound represented by the following general formula (2).

In formula (2), R is independently an alkyl group or an alkoxy group which may be substituted with a halogen atom or a halogen atom having 1 to 6 carbon atoms, or a monovalent hydrocarbon group or alkoxy having 1 to 6 carbon atoms. Indicates a phenyl or phenoxy group that may be substituted with a group, where Z ₁ is an independent single bond, -O-, -S-, -CH _2- , -CH (CH ₃ )-, -C (CH ₃ ). _It represents a divalent group selected from _2- , -CO-, -SO _{2-, or -NH-, where n 3} independently represents an integer 0-4 and n ₄ represents an integer 0-2. However, _{at least one of Z 1} is -O-, -S-, -CH _2- , -CH (CH ₃ )-, -C (CH ₃ ) _2- , -CO-, -SO _2- , or-. The divalent group selected from NH- is shown.

Since the diamine residue derived from the diamine compound represented by the general formula (2) has a flexible portion, flexibility can be imparted to the polyimide film. From this point of view, the diamine residue derived from the diamine compound represented by the general formula (2) is 1 to 50 mol parts with respect to 100 mol parts of all diamine residues contained in the non-thermoplastic polyimide. It is preferable to contain it in the range of 1 to 40 parts, and more preferably it is contained in the range of 1 to 40 parts. If the diamine residue derived from the diamine compound represented by the general formula (2) is contained in an amount of more than 50 mol, the CTE increases and the dimensional stability deteriorates. Further, when the content is less than 1 mol, the flexibility is deteriorated, so that the bending characteristic is deteriorated. Further, the non-thermoplastic polyimide has both a diamine residue derived from the diamine compound represented by the general formula (1) and a diamine residue derived from the diamine compound represented by the general formula (2). When it is contained, the content of the diamine residue derived from the diamine compound represented by the general formula (1) is 50 to 99 mol with respect to 100 mol parts of the total diamine residue contained in the non-thermoplastic polyimide. It is more preferably within the range of parts, and most preferably within the range of 60 to 99 mol parts.

Preferred specific examples of the diamine compound represented by the general formula (2) include, for example, 3,3'-diaminodiphenylmethane, 3,3'-diaminodiphenylpropane, 3,3'-diaminodiphenylsulfide, 3,3'. -Diaminodiphenylsulfone, 4,4'-diaminodiphenyl ether (4,5'-DAPE), 3,3-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 3,4'-diaminodiphenylmethane, 3,4'-diamino Diphenylpropane, 3,4'-diaminodiphenylsulfide, 3,4'-diaminobenzophenone, (3,3'-bisamino) diphenylamine, 1,4-bis (3-aminophenoxy) benzene, 1,3-bis (4) -Aminophenoxy) Benzene (TPE-R), 1,4-bis (4-Aminophenoxy) Benzene (TPE-Q), 3- [4- (4-Aminophenoxy) Phenoxy] Benzeneamine, 3- [3- (4-Aminophenoxy) Phenoxy] Benzeneamine, 1,3-bis (3-aminophenoxy) Benzene (APB), 4,4'-[2-methyl- (1,3-phenylene) bisoxy] bisaniline, 4, 4'-[4-Methyl- (1,3-phenylene) bisoxy] bisaniline, 4,4'-[5-methyl- (1,3-phenylene) bisoxy] bisaniline, bis [4- (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)] Benzenephenone, Bis [4,4'-(3-Aminophenoxy)] Benzenelide, 4- [3- [4- (4-Aminophenoxy) Phenoxy] Phenoxy] Aniline, 4,4'- [Oxybis (3,1-phenyleneoxy)] bisaniline, bis [4- (4-aminophenoxy) phenyl] ether (BAPE), bis [4- (4-aminophenoxy) phenyl] ketone (BACK), bis [4 -(3-Aminophenoxy)] biphenyl, bis [4- (4-aminophenoxy)] biphenyl, 2,2-bis (4-aminophenoxyphenyl) propane (BAPP) and the like can be mentioned. Among these, those in which n ₃ in the general formula (2) is 0 are preferable, and for example, 4,4'-diaminodiphenyl ether (4,4'-DAPE) and 1,3-bis (4-aminophenoxy) benzene are preferable. (TPE-R), 1,3-bis (3-aminophenoxy) benzene (APB), 1,4-bis (4-aminophenoxy) benzene (TPE-Q), 2,2-bis (4-aminophenoxy) Phenyl) propane (BAPP) is preferred.

However, other diamines usually used as a raw material for polyimide can be used in combination as long as the object of the present invention is not impaired. Examples of other diamines include p-phenylenediamine (p-PDA) and m-phenylenediamine (m-PDA).

The acid anhydride residue contained in the non-thermoplastic polyimide is not particularly limited, but for example, an acid anhydride residue derived from pyromellitic dianhydride (PMDA) (hereinafter, also referred to as PMDA residue). Is preferably mentioned. Since the PMDA residue has one benzene ring number among the acid anhydride residues, the imide group concentration can be increased, which is an advantageous acid anhydride residue for lowering the CTE. Further, an acid anhydride residue derived from 3,3', 4,4'-biphenyltetracarboxylic dianhydride (BPDA) (hereinafter, also referred to as BPDA residue) is also preferably mentioned. The BPDA residue has a biphenyl structure, easily forms an ordered structure, can be reduced in CTE, and has a lower imide group concentration than the PMDA residue and contributes to lower hygroscopicity, and thus is dimensionally stable. It becomes an acid anhydride which is advantageous in enhancing. In addition, since it contains two or more benzene rings, it is also advantageous in improving dimensional stability to reduce the imide group concentration and contribute to low hygroscopicity.
In particular, the BPDA residue is preferably in the range of 20 to 70 mol, more preferably in the range of 20 to 50 mol, with respect to 100 mol of the total acid anhydride residue contained in the non-thermoplastic polyimide. May contain. If the content of the BPDA residue is less than 20 mol, the hygroscopicity tends to deteriorate and the dimensional stability tends to deteriorate. When the content of BPDA residue exceeds 70 mol parts, CTE tends to increase and dimensional stability tends to deteriorate.

Other acid anhydride residues contained in the non-thermoplastic polyimide include, for example, 2,3', 3,4'-biphenyltetracarboxylic dianhydride, 2,2', 3,3'-biphenyltetracarboxylic. Acid dianhydride, 3,3', 4,4'-diphenylsulfonetetracarboxylic acid dianhydride, 4,4'-oxydiphthalic anhydride, 2,3', 3,4'-biphenyltetracarboxylic dianhydride 2,2', 3,3'-, 2,3,3', 4'-or 3,3', 4,4'-benzophenone tetracarboxylic dianhydride, 2,3', 3,4 '-Diphenyl ether tetracarboxylic acid dianhydride, 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) ethane dianhydride, 1,2,7,8-, 1,2,6,7- or 1,2,9,10-phenanthrene-tetracarboxylic acid dianhydride, 2, 3,6,7-Anthracene tetracarboxylic acid dianhydride, 2,2-bis (3,4-dicarboxyphenyl) tetrafluoropropane dianhydride, 2,3,5,6-cyclohexane dianhydride, 1, 2,5,6-naphthalenetetracarboxylic acid dianhydride 1,4,5,8-naphthalenetetracarboxylic acid dianhydride 2,3,6,7-naphthalenetetracarboxylic acid dianhydride 4,8- Dimethyl-1,2,3,5,6,7-Hexahydronaphthalene-1,2,5,6-tetracarboxylic dianhydride 2,6- or 2,7-dichloronaphthalene-1,4,5 , 8-Tetracarboxylic Acid Dianhydride 2,3,6,7-(or 1,4,5,8-) Tetrachloronaphthalene-1,4,5,8-(or 2,3,6,7-) -) Tetracarboxylic hydride, 2,3,8,9-,3,4,9,10-,4,5,10,11-or 5,6,11,12-perylene-tetracarboxylic acid dianhydride Anhydride, cyclopentane-1,2,3,4-tetracarboxylic acid dianhydride, pyrazine-2,3,5,6-tetracarboxylic acid dianhydride, pyrrolidine-2,3,4,5-tetracarboxylic Acid dianhydride, thiophene-2,3,4 , 5-Tetracarboxylic dianhydride, 4,4'-bis (2,3-dicarboxyphenoxy) Diphenylmethane dianhydride and other aromatic tetracarboxylic dianhydride residues. Be done.

When the above types of acid anhydride and diamine, and two or more types of acid anhydride or diamine are used, the physical properties such as thermal expansion and orientation of the non-thermoplastic polyimide can be controlled by selecting the respective molar ratios. can do.

Further, in the non-thermoplastic polyimide, when a plurality of structural units of polyimide are present, it may exist as a block or randomly, but it is preferable that it exists randomly.

The imide group concentration of the non-thermoplastic polyimide is preferably 35% by weight or less. Here, the "imide group concentration" means a value obtained by dividing the molecular weight of the imide base portion (-(CO) ₂ -N-) in the polyimide by the molecular weight of the entire structure of the polyimide. When the imide group concentration exceeds 35% by weight, the molecular weight of the resin itself becomes small, and the decrease in hygroscopicity deteriorates due to the increase in polar groups. By selecting the combination of the acid anhydride and the diamine compound, the orientation of the molecules in the non-thermoplastic polyimide is controlled, thereby suppressing the increase in CTE due to the decrease in the imide group concentration and ensuring low hygroscopicity. ing.

The weight average molecular weight of the non-thermoplastic polyimide is preferably in the range of, for example, 10,000 to 400,000, and more preferably in the range of 50,000 to 350,000. If the weight average molecular weight is less than 10,000, the strength of the polyimide film is lowered and the polyimide film tends to be brittle. On the other hand, when the weight average molecular weight exceeds 400,000, the viscosity is excessively increased, and defects such as thickness unevenness and streaks tend to occur easily during the coating work.

<CTE>
The polyimide film produced by the method of the present embodiment has realized low CTE by heating the polyamic acid having the above resin composition with an infrared heater. The CTE of the polyimide film is preferably less than 20 ppm / K, more preferably 18 ppm / K or less. When the CTE is 20 ppm / K or more, for example, warpage is likely to occur when a polyimide film is composited with a metal layer to form a metal-clad laminate, or dimensional stability when the metal layer is etched and patterned. Decreases.

<Warp>
In the polyimide film produced by the method of the present embodiment, the orientation distribution is made uniform by heating the polyamic acid having the above resin composition with an infrared heater, and the warpage is effectively reduced. .. The warp of the polyimide film is, for example, under the conditions of 23 ° C. and 50% humidity, and after controlling the humidity for 20 hours, the polyimide film is allowed to stand so that the convex surface at the center of the 50 mm square polyimide film is in contact with a flat surface, and the four corners are formed. When the average value of the floating amount is taken as the average warp amount, the average warp amount is 15 mm or less, preferably 10 mm or less.

<Thickness>
The thickness of the polyimide film produced by the method of the present embodiment is preferably in the range of 5 to 80 μm, more preferably in the range of 25 to 50 μm from the viewpoint of insulating properties when used as an insulating layer of a circuit board. Is. The polyimide film produced by the method of the present embodiment can have a laminated structure with another resin layer, if necessary.

Since the polyimide film produced by the method of the present embodiment has low CTE and suppression of warpage, for example, a single-layer polyimide film for CCL and a single layer for POP (package on package). It can be preferably used for layered polyimide films, single-layer polyimide films for semi-additives (SAP), and the like.
Therefore, the method of the present embodiment is particularly useful in the manufacturing process of an industrial-scale polyimide film, and has high utility value.

[Metal-clad laminate]
The metal-clad laminate of the present embodiment includes an insulating resin layer and a metal layer provided on at least one surface of the insulating resin layer, and is a polyimide layer forming a part or all of the insulating resin layer. However, it may be formed of the polyimide film obtained by the production method of the above embodiment.

The material of the metal layer is not particularly limited, but for example, copper, stainless steel, iron, nickel, beryllium, aluminum, zinc, indium, silver, gold, tin, zirconium, tantalum, titanium, lead, magnesium, manganese and these. Examples include the alloy of. Of these, copper or copper alloys are particularly preferable. The material of the wiring layer in the circuit board described later is the same as that of the metal layer.

The thickness of the metal layer is not particularly limited, but when a metal foil typified by copper foil is used, for example, it is preferably 35 μm or less, and more preferably 5 to 25 μm. From the viewpoint of production stability and handleability, the lower limit of the thickness of the metal foil is preferably 5 μm. When copper foil is used, it may be rolled copper foil or electrolytic copper foil. Further, as the copper foil, a commercially available copper foil can be used.

Further, the metal foil may be surface-treated with, for example, siding, aluminum alcoholate, aluminum chelate, silane coupling agent, etc. for the purpose of rust prevention treatment and improvement of adhesive strength.

[Circuit board]
The metal-clad laminate of the above embodiment is mainly useful as a circuit board material for FPC and the like. That is, a circuit board 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.

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 coefficient of thermal expansion (CTE)]
The coefficient of thermal expansion is 30 ° C to 250 ° C at a constant temperature rise rate while applying a load of 5.0 g to a polyimide film with a size of 3 mm x 20 mm using a thermomechanical analyzer (manufactured by Bruker, trade name; 4000SA). The temperature was raised to 100 ° C., and the temperature was further maintained at that temperature for 10 minutes, and then cooled at a rate of 5 ° C./min to obtain an average coefficient of thermal expansion (coefficient of thermal expansion) from 250 ° C. to 100 ° C.

[Measurement of storage elastic modulus]
For the storage elastic modulus, a polyimide film having a size of 5 mm × 20 mm is heated in an oven at 120 ° C. for 2 hours and at 170 ° C. for 3 hours, and a dynamic viscoelastic device (DMA: manufactured by UBM, trade name; E4000F). ) Was stepwise heated from 30 ° C. to 400 ° C. at a heating rate of 4 ° C./min, and measurement was performed at a frequency of 11 Hz. A polyimide having a storage elastic modulus of 1.0 × 10 ⁹ Pa or more at 30 ° C. and a storage elastic modulus of 1.0 × 10 ⁸ Pa or more at 350 ° C. is made non-thermoplastic, and the storage elastic modulus at 30 ° C. is 1. A thermoplastic having a storage elastic modulus of 1.0 × 10 ⁹ Pa or more and a storage elastic modulus at 350 ° C. of ^{less than 1.0 × 10 8} Pa is defined as thermoplastic.

[Measurement of warpage]
To warp the polyimide film, a polyimide film having a size of 50 mm × 50 mm is adjusted for 20 hours under the conditions of 23 ° C. and 50% humidity, and then the sample is allowed to stand so that the convex surface at the center of the sample is in contact with a flat surface. The distances from the stationary surface were measured for the four corners of the above, and the average value was taken as the average warpage amount.

[Measurement of surface roughness of copper foil]
The surface roughness of the copper foil is AFM (manufactured by Bruker AXS Co., Ltd., trade name: Dimension Icon type SPM), probe (manufactured by Bruker AXS Co., Ltd., trade name: TESSA (NCHV), tip radius of curvature 10 nm, Using a spring constant of 42 N / m), the copper foil surface was measured in a tapping mode in a range of 80 μm × 80 μm, and a ten-point average roughness (Rzjis) was determined.

The abbreviations used in Examples and Reference Examples indicate the following compounds.
m-TB: 2,2'-dimethyl-4,4'-diaminobiphenyl DAPE: 4,4'-diaminodiphenyl ether PMDA: pyromellitic acid benzene BPDA: 3,3', 4,4'-biphenyltetracarboxylic Acid dianhydride TFMB: 2,2'bis (trifluoromethyl) benzidine TPE-R: 1,3-bis (4-aminophenoxy) benzene p-PDA: p-phenylenediamine BAPP: 2,2-bis (4) -Aminophenoxyphenyl) Propane DMAc: N, N-dimethylacetamide

(Synthesis Example 1)
14.472 g of DAPE (0.0723 mol) and 170 g of DMAc were added to a 300 ml separable flask under a nitrogen stream so that the solid content concentration was 15% by weight, and the mixture was stirred and dissolved at room temperature. I let you. Next, after adding 15.528 g of PMDA (0.0712 mol), the polymerization reaction was carried out by continuing stirring at room temperature for 3 hours to prepare a polyamic acid solution 1.

(Synthesis Example 2)
8.139 g of DAPE (0.0407 mol) and 4.296 g of p-PDA (0.0407 mol) and so that the solid content concentration is 15% by weight in a 300 ml separable flask under a nitrogen stream. 170 g of DMAc was added and stirred at room temperature to dissolve. Next, after adding 17.466 g of PMDA (0.0801 mol), the polymerization reaction was carried out by continuing stirring at room temperature for 3 hours to prepare a polyamic acid solution 2.

(Synthesis Example 3)
8.995 g of p-PDA (0.0832 mol) and 170 g of DMAc were added to a 300 ml separable flask under a nitrogen stream so that the solid content concentration was 15% by weight, and the mixture was stirred at room temperature. Dissolved. Next, 12.07 g of BPDA (0.041 mol) and 8.935 g of PMDA (0.041 mol) were added, and then the polymerization reaction was carried out by continuing stirring at room temperature for 3 hours to prepare a polyamic acid solution 3. did.

(Synthesis Example 4)
7.385 g of DAPE (0.0369 mol) and 3.988 g of p-PDA (0.03688 mol) and so on so that the solid content concentration is 15% by weight in a 300 ml separable flask under a nitrogen stream. 170 g of DMAc was added and stirred at room temperature to dissolve. Next, 10.704 g of BPDA (0.0363 mol) and 7.923 g of PMDA (0.0363 mol) were added, and then stirring was continued for 3 hours at room temperature to carry out a polymerization reaction to prepare a polyamic acid solution 4. did.

(Synthesis Example 5)
2.883 g DAPE (0.0144 mol), 6.227 g p-PDA (0.0576 mol) and so that the solid content concentration is 15% by weight in a 300 ml separable flask under a nitrogen stream. 170 g of DMAc was added and stirred at room temperature to dissolve. Next, after adding 20.891 g of BPDA (0.0709 mol), the polymerization reaction was carried out by continuing stirring at room temperature for 3 hours to prepare a polyamic acid solution 5.

(Synthesis Example 6)
In a 300 ml separable flask under a nitrogen stream, 7.13 g DAPE (0.0356 mol), 7.571 g m-TB (0.0356 mol) and so that the solid content concentration is 15% by weight. 170 g of DMAc was added and stirred at room temperature to dissolve. Next, after adding 15.3 g of PMDA (0.0701 mol), the polymerization reaction was carried out by continuing stirring at room temperature for 3 hours to prepare a polyamic acid solution 6.

(Synthesis Example 7)
In a 300 ml separable flask under a nitrogen stream, 1.947 g of TPE-R (0.0066 mol) and 12.745 g of m-TB (0.0599 mol) so that the solid content concentration is 15% by weight. ) And 170 g of DMAc were added and stirred at room temperature to dissolve. Next, after adding 3.86 g of BPDA (0.0131 mol) and 11.447 g of PMDA (0.0525 mol), stirring was continued for 3 hours at room temperature to carry out a polymerization reaction to prepare a polyamic acid solution 7. did.

(Synthesis Example 8)
Under a nitrogen stream, 13.707 g of m-TB (0.0646 mol) and 170 g of DMAc were added to a 300 ml separable flask so that the solid content concentration was 15% by weight, and the mixture was stirred at room temperature. It was dissolved. Next, 9.356 g of BPDA (0.0318 mol) and 6.936 g of PMDA (0.0318 mol) were added, and then the polymerization reaction was carried out by continuing stirring at room temperature for 3 hours to prepare a polyamic acid solution 8. did.

(Synthesis Example 9)
In a 300 ml separable flask under a nitrogen stream, 6.299 g of DAPE (0.0315 mol), 10.087 g of TFMB (0.0315 mol) and 170 g so that the solid content concentration is 15% by weight. DMAc was added and stirred at room temperature to dissolve. Next, after adding 13.613 g of PMDA (0.0624 mol), the polymerization reaction was carried out by continuing stirring at room temperature for 3 hours to prepare a polyamic acid solution 9.

(Synthesis Example 10)
26.44 g of BAPP (0.0636 mol) and 170 g of DMAc were added to a 300 ml separable flask under a nitrogen stream so that the solid content concentration was 15% by weight, and the mixture was stirred and dissolved at room temperature. It was. Next, after adding 18.56 g of BPDA (0.063 mol), the polymerization reaction was carried out by continuing stirring at room temperature for 3 hours to prepare a polyamic acid solution 10.

(Reference example 1)
A polyamic acid solution 1 was uniformly applied to a copper foil 1 (electrolytic copper foil, thickness; 12 μm, Rzjis; 0.6 μm) so that the cured thickness would be about 25 μm, and then heated and dried at 130 ° C. to obtain a polyamide. An acid coating film was formed. Then, the coating film was subjected to a stepwise heat treatment from 130 ° C. to 360 ° C. using an infrared heater under the condition of a maximum radiant energy wavelength of 3 to 7 μm, and imidization was completed within 15 minutes. The copper foil was etched and removed using an aqueous ferric chloride solution to prepare a polyimide film 1 (non-thermoplastic, CTE; 40.4 ppm / K). In the evaluation of the warp of the polyimide film 1, the warp was large and became tubular, and it was impossible to measure the warp. The results are shown in Table 1.

(Reference Examples 2 to 5, Examples 1 to 4)
Polyimide films 2 to 9 were prepared in the same manner as in Reference Example 1 except that the polyamic acid solution shown in Table 1 was used. CTE and warpage were measured for the polyimide films 2 to 9, and the results are shown in Table 1.

The above results are summarized in Table 1. In addition, in the "warp" in Table 1, the sample which became tubular and could not be measured was indicated as "Large".

From the results in Table 1, as a diamine component, the polyimide films 6 to 8 of Examples 1 to 3 containing 50 parts or more of m-TB and 50 parts or more of TFMB were contained with respect to 100 parts of all diamine residues. It can be seen that the polyimide film 9 of Example 4 has a CTE of less than 20 ppm / K and a warp of less than 15 mm. Therefore, by curing the polyamic acid using these diamine compounds with an infrared heater, the gradient of the orientation state of the polyimide in the thickness direction of the polyimide layer laminated on the copper foil becomes small, and the CTE of the polyimide layer is lowered and the warp is reduced. It was confirmed that the suppression of

(Reference example 6)
Using the polyamic acid solution 7, a polyamic acid coating film was formed in the same manner as in Reference Example 1. Then, the coating film was heat-treated from 130 ° C. to 360 ° C. using a hot air curing furnace to complete imidization within 15 minutes. The copper foil was removed by etching in the same manner as in Reference Example 1 to prepare a polyimide film 10 (non-thermoplastic, CTE; 16.8 ppm / K). The warp of the polyimide film 10 was 16 mm.

(Example 5)
The polyamic acid solution 10 was uniformly applied to the copper foil 1 so as to have a thickness of 2.5 μm after curing, and then heated and dried at 130 ° C. A polyamic acid solution 7 was uniformly applied onto the polyamic acid solution 7 so as to have a thickness of about 25 μm after curing, and then heat-dried at 130 ° C. Further, the polyamic acid solution 10 was uniformly applied onto the polyamic acid solution 10 so as to have a thickness of 2.5 μm after curing, and then heat-dried at 130 ° C. to form a polyamic acid coating film. Then, the coating film is subjected to stepwise heat treatment from 130 ° C. to 360 ° C. using an infrared heater under the conditions of maximum radiant energy wavelength; 3 to 7 μm, imidization is completed within 15 minutes, and the metal-clad laminate 10 is used. Was prepared.

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 (8)

A solution of a polyamic acid containing a diamine residue derived from a diamine component and an acid anhydride residue derived from an acid anhydride component is applied onto a substrate and imidized by heat treatment with an infrared heater. A method for producing a polyimide film, which comprises a step of forming a polyimide film in which the resin component is made of a non-thermoplastic polyimide.
The diamine residue derived from the diamine compound represented by the following general formula (1) is 50 mol parts or more with respect to 100 mol parts of all diamine residues contained in the non-thermoplastic polyimide. A method for producing a polyimide film.

[In the formula (1), the linking group Z represents a single bond or −COO−, and Y is a monovalent hydrocarbon group or carbon number having 1 to 3 carbon atoms which may be independently substituted with a halogen atom or a phenyl group. It represents an alkoxy group of 1 to 3 or a perfluoroalkyl group or an alkenyl group having 1 to 3 carbon atoms, n represents an integer of 1 or 2, and p and q independently represent an integer of 0 to 4. ] The diamine residue derived from the diamine compound represented by the general formula (1) is in the range of 50 to 99 mol parts with respect to 100 mol parts of all diamine residues contained in the non-thermoplastic polyimide. The method for producing a polyimide film according to claim 1, wherein the diamine residue derived from the diamine compound represented by the following general formula (2) is in the range of 1 to 50 mol parts.

[In the formula (2), R is an alkyl group or an alkoxy group which may be independently substituted with a halogen atom or a halogen atom having 1 to 6 carbon atoms, or a monovalent hydrocarbon group having 1 to 6 carbon atoms. Indicates a phenyl or phenoxy group that may be substituted with an alkoxy group, where Z ₁ is independently single-bonded, -O-, -S-, -CH _2- , -CH (CH ₃ )-, -C (CH _3). ) _2- , -CO-, -SO _2- , or -NH- indicates a divalent group, n ₃ independently represents an integer of 0 to 4, and n ₄ represents an integer of 0 to 2. However, _{at least one of Z 1} is -O-, -S-, -CH _2- , -CH (CH ₃ )-, -C (CH ₃ ) _2- , -CO-, -SO _2- , or-. The divalent group selected from NH- is shown. ] The method for producing a polyimide film according to claim 1 or 2, wherein the diamine compound represented by the general formula (1) is a diamine compound represented by the following general formula (A1).

[In the general formula (A1), X represents an alkyl group having 1 to 3 carbon atoms which may be independently substituted with a fluorine atom, and n ₁ and n ₂ independently represent an integer of 1 to 4. ] For 100 mol parts of the total acid anhydride residue contained in the non-thermoplastic polyimide, the BPDA residue derived from 3,3', 4,4'-biphenyltetracarboxylic dianhydride (BPDA) is contained. The method for producing a polyimide film according to claim 1, wherein the amount is within the range of 20 to 70 mol parts. The polyimide film has a coefficient of thermal expansion (CTE) of less than 20 ppm / K, and under the conditions of 23 ° C. and 50% humidity, the convex surface of the central portion of the 50 mm square polyimide film after humidity control for 20 hours is flat. The production of the polyimide film according to claim 1, wherein the polyimide film is allowed to stand in contact with a surface surface, and the average warpage amount is 15 mm or less when the average value of the lifted amounts of the four corners is taken as the average warp amount. Method. The method for producing a polyimide film according to claim 1, wherein the thickness of the polyimide film is within the range of 5 to 80 μm. The method for producing a polyimide film according to claim 1, wherein the heat treatment is performed on the substrate. A method for manufacturing a metal-clad laminate comprising an insulating resin layer and a metal layer laminated on one side or both sides of the insulating resin layer.
The insulating resin layer has a polyimide layer in which the resin component is a non-thermoplastic polyimide.
A polyamic acid containing a diamine residue derived from a diamine component and an acid anhydride residue derived from an acid anhydride component is directly or indirectly laminated on a metal foil, followed by heat treatment with an infrared heater. Including the step of forming the polyimide layer by imidization with
The diamine residue derived from the diamine compound represented by the following general formula (1) is 50 mol parts or more with respect to 100 mol parts of all diamine residues contained in the non-thermoplastic polyimide. A method for manufacturing a metal-clad laminate.

[In the formula (1), the linking group Z represents a single bond or −COO−, and Y is a monovalent hydrocarbon group or carbon number having 1 to 3 carbon atoms which may be independently substituted with a halogen atom or a phenyl group. It represents an alkoxy group of 1 to 3 or a perfluoroalkyl group or an alkenyl group having 1 to 3 carbon atoms, n represents an integer of 1 or 2, and p and q independently represent an integer of 0 to 4. ]