WO2024004604A1

WO2024004604A1 - Film, method for producing same, metal clad laminated board, circuit board, and electronic device

Info

Publication number: WO2024004604A1
Application number: PCT/JP2023/021676
Authority: WO
Inventors: 愛実高間; 康大久保; 乃傲許; 浩西村
Original assignee: コニカミノルタ株式会社
Priority date: 2022-06-30
Filing date: 2023-06-12
Publication date: 2024-01-04

Abstract

The present invention addresses the problem of providing, for example, a film that reduces dielectric loss and is excellent in adhesiveness with a copper foil layer. The film according to the present invention contains a resin and a filler, the film being characterized in that: the dielectric dissipation factors in a frequency of 28 GHz of the resin and the filler in an environment of 22°C and 60% RH are both 0.0150 or less; the content of the filler falls within the range of 1.0%-70.0% by mass based on the total mass of the film; and when the quantities of surface free energy of two facing surfaces of the film are denoted as A [mJ/m²] and B [mJ/m²], respectively, the following expressions are satisfied.　(Expression 1): A ≤ B (Expression 2): 1 ≤ B/A < 1.30

Description

Films, manufacturing methods thereof, metal clad laminates, circuit boards and electronic devices

The present invention relates to a film. More specifically, the present invention relates to a film that reduces transmission loss and has excellent adhesiveness to a copper foil layer.

In recent years, with the increase in the use of the Internet and the increasing performance and functionality of information terminals, the introduction and widespread use of fifth generation mobile communication systems (5G), which can handle larger amounts of transmitted information and faster data processing, has increased. In anticipation of this, development of communication equipment compatible with 5G is underway.

In 5G, a frequency band below 6 GHz called the Sub-6 band and a frequency band above 24 GHz called the millimeter wave band are allocated. The amount of information that can be transmitted at once increases as the frequency of radio waves increases, so these 5G frequency bands are higher frequency bands than the previous generation 4G, and 5G communication equipment has a high frequency band. It needs to be adapted for use.

In circuit boards used in communication equipment, it is required to use materials with low transmission loss, but dielectric loss, which is one of the elements that make up transmission loss, increases as the frequency of radio waves increases. Using conventional materials increases dielectric loss. Therefore, it is required to use a low dielectric loss material that suppresses the increase in dielectric loss.

In addition to commonly used rigid boards, circuit boards include thin, flexible, and bendable flexible boards. This flexible substrate is manufactured by bonding a conductor foil (metal plate) to a base film via an adhesive layer.
Therefore, in flexible substrates, development of base films with further reduced dielectric loss is underway.

Patent Document 1 discloses a non-aqueous dispersion of a fluororesin that contains a fluororesin micropowder and a fluorine additive containing at least a fluorine-containing group and a lipophilic group, and has a water content of 5000 ppm or less by Karl Fischer method. A technique related to a fluororesin-containing polyimide precursor solution composition containing at least a polyimide precursor solution and a polyimide precursor solution is disclosed.

Moreover, Patent Document 2 discloses a technology related to a low dielectric constant polyimide terminal-capped with an alicyclic dicarboxylic acid anhydride or an alicyclic monoamine.

Although these techniques have made it possible to further reduce the dielectric loss of the base film, the demand for reducing dielectric loss is increasing, and further improvements are required.

Patent No. 6491947 Japanese Patent Application Publication No. 2020-070359

The present invention was made in view of the above problems and circumstances, and an object to be solved is to provide a film etc. that reduces dielectric loss and has excellent adhesiveness to a copper foil layer.

In order to solve the above problems, the present inventor investigated the causes of the above problems, and as a result, in a film containing a resin and a filler, the dielectric loss tangent of the resin and filler, the content of the filler, and the two aspects of the film were determined. The inventors have discovered that by controlling the surface free energy within a specific range, the dielectric loss of the film can be reduced and the adhesion between the film and the copper foil layer can be improved, leading to the present invention.
That is, the above-mentioned problems related to the present invention are solved by the following means.

1. A film containing a resin and a filler,
The dielectric loss tangents of the resin and the filler at a frequency of 28 GHz in an environment of 22° C. and 60% RH are both 0.0150 or less,
The content of the filler is within the range of 1.0 to 70.0% by mass based on the total mass of the film,
When the surface free energies of the two opposing surfaces of the film are respectively A [mJ/m ² ] and B [mJ/m ² ], the following formula is satisfied (Formula 1) A≦B
(Formula 2) 1≦B/A<1.30
A film characterized by

2. 2. The film according to item 1, wherein the dielectric loss tangent of the film at a frequency of 28 GHz in an environment of 22° C. and 60% RH is within the range of 0.0010 to 0.0150.

3. 3. The film according to item 1 or 2, wherein the content of the filler is within the range of 15.0 to 50.0% by mass based on the total mass of the film.

4. The film according to item 1 or 2, wherein the amount of residual solvent in the film is within the range of 200 to 3000 ppm by mass.

5. The film further contains a surfactant,
3. The film according to item 1 or 2, wherein the content of the surfactant is within the range of 0.10 to 1.00% by mass based on the total mass of the film.

6. 3. The film according to item 1 or 2, wherein the surface free energy of both opposing surfaces of the film is within the range of 25.00 to 75.00 mJ/m ² .

7. The film according to item 1 or 2, wherein the resin has a glass transition temperature of 200°C or higher.

8. The film according to item 1 or 2, wherein the resin and the filler are soluble or dispersible in a solvent having a boiling point of 150°C or less.

9. A film manufacturing method for manufacturing the film according to item 1 or 2, comprising:
preparing a coating liquid containing the resin, the filler, and a solvent;
a step of applying the coating liquid onto a support to form a coating film, and a step of drying the coating film,
A method for producing a film, characterized in that the surface free energy of the support is within a range of 30 to 80 mJ/m ² .

10. 10. The method for producing a film according to item 9, wherein in the step of preparing the coating liquid, the resin is added to a filler-containing liquid in which the filler is dissolved or dispersed in the solvent.

11. 11. The method for producing a film according to item 9 or 10, wherein the boiling point of the solvent is 150°C or less.

12. A metal-clad laminate comprising the film according to item 1 or 2.

13. A circuit board comprising the metal-clad laminate according to item 12.

14. An electronic device comprising the circuit board according to item 13.

By the means of the present invention, it is possible to provide a film that reduces transmission loss and has excellent adhesion to a copper foil layer, a method for producing the same, a metal-clad laminate, a circuit board, and an electronic device.

Although the mechanism of expression or action of the effects of the present invention is not clear, it is speculated as follows.

Although details will be described later, from the viewpoint of energy efficiency, it is preferable that the dielectric used for the circuit board be a film with less dielectric loss. Dielectric loss depends on the dielectric properties (relative permittivity and dielectric loss tangent) of a dielectric, and the smaller the dielectric constant and dielectric loss tangent, the smaller its value.

The film of the present invention is considered to be able to reduce dielectric loss because the dielectric loss tangents of the resin and filler at a frequency of 28 GHz in an environment of 22° C. and 60% RH are both 0.0150 or less. .
Further, it is considered that dielectric loss can be reduced by containing a relatively large amount of filler having a low dielectric loss tangent.
It is thought that this makes it possible to reduce the transmission loss of the film.

Furthermore, if the surface free energy of the two surfaces of the film satisfies the above (Formula 1) and (Formula 2) (the ratio of the surface free energies is within a specific range), that is, the two surfaces of the film Since the difference in measured surface free energy is relatively small, it is considered that the adhesiveness with the copper foil layer is excellent.

Diagram explaining the phenomenon of wetting Explanatory diagram of energy before and after separating the interface Cross-sectional view of an example of a metal-clad laminate (single-sided) of the present invention Cross-sectional view of an example of a metal-clad laminate (both sides) of the present invention A cross-sectional view of an example of a circuit board (single-sided structure) of the present invention A sectional view of an example of a circuit board (double-sided structure) of the present invention A sectional view of an example of a circuit board (multilayer structure) of the present invention

The film of the present invention is a film containing a resin and a filler, and the dielectric loss tangents of the resin and the filler at a frequency of 28 GHz in an environment of 22° C. and 60% RH are both 0.0150 or less, The content of the filler is within the range of 1.0 to 70.0% by mass based on the total mass of the film, and the surface free energy is A [mJ/ m ² ] and B [mJ/m ² ], it is characterized by satisfying the following formula.
(Formula 1) A≦B
(Formula 2) 1≦B/A<1.30
This feature is a technical feature common to or corresponding to the embodiments described below.

As an embodiment of the present invention, from the viewpoint of reducing the dielectric loss of the film and achieving both the adhesion between the film and the copper foil layer, the dielectric loss tangent of the film at a frequency of 28 GHz in an environment of 22° C. and 60% RH is , preferably within the range of 0.0010 to 0.0150.

In an embodiment of the present invention, from the viewpoint of reducing dielectric loss of the film and achieving both adhesion between the film and the copper foil layer, the content of the filler is 15.0 to 15.0 to It is preferably within the range of 50.0% by mass.

In an embodiment of the present invention, from the viewpoint of performance stability and production efficiency, the amount of residual solvent in the film is preferably within the range of 200 to 3000 ppm by mass.

In an embodiment of the present invention, the film further contains a surfactant, and the content of the surfactant is , is preferably within the range of 0.10 to 1.00% by mass based on the total mass of the film.

As an embodiment of the present invention, from the viewpoint of reducing the dielectric loss of the film and achieving both the adhesion between the film and the copper foil layer, the surface free energy of both opposing surfaces of the film is 25.00. It is preferably within the range of 75.00 mJ/m ² .

In an embodiment of the present invention, from the viewpoint of heat resistance of the film, it is preferable that the glass transition temperature of the resin is 200° C. or higher.

In an embodiment of the present invention, from the viewpoint that a solvent with a low boiling point (150°C or less) can be used in the production of the film, the resin and the filler are soluble in a solvent with a boiling point of 150°C or less. Or it is preferable to have dispersibility.

The film manufacturing method of the present invention is a film manufacturing method for manufacturing the film of the present invention, which includes a step of preparing a coating liquid containing the resin, the filler, and a solvent, and coating the coating liquid on a support. , a step of forming a coating film, and a step of drying the coating film, and is characterized in that the surface free energy of the support is within a range of 30 to 80 mJ/m ² .

In an embodiment of the present invention, from the viewpoint of reducing the dielectric loss of the film by improving the dispersibility of the filler, in the step of preparing the coating liquid, the filler containing the filler is dissolved or dispersed in the solvent. Preferably, the resin is added to the liquid.

In an embodiment of the present invention, the boiling point of the solvent is preferably 150° C. or lower, from the viewpoint of reducing the film manufacturing process temperature (particularly the drying temperature) and reducing thermal shrinkage.

The metal-clad laminate of the present invention is characterized by containing the film.

The circuit board of the present invention is characterized by comprising the metal-clad laminate.

The electronic device of the present invention is characterized by comprising the circuit board.

Hereinafter, the present invention, its constituent elements, and forms and aspects for carrying out the present invention will be described in detail. In this application, "~" is used to include the numerical values described before and after it as a lower limit value and an upper limit value.

1. Summary of the film The film of the present invention is a film containing a resin and a filler, and the dielectric loss tangent of the resin and the filler at a frequency of 28 GHz in an environment of 22° C. and 60% RH are both 0.0150 or less. , the filler content is within the range of 1.0 to 70.0% by mass based on the total mass of the film, and the surface free energy on the two opposing faces of the film is A [mJ/ m ² ] and B [mJ/m ² ], it is characterized by satisfying the following formula.
(Formula 1) A≦B
(Formula 2) 1≦B/A<1.30

From the perspective of energy efficiency, it is important to further reduce the degree of deterioration and attenuation (transmission loss) of electrical, light, sound, and other signals flowing on the circuit boards of communication equipment, especially the circuit boards included in communication equipment. preferable.
Transmission loss is thought to consist of the sum of the dielectric loss of the dielectric material (e.g., base film, etc.) used for the circuit board material, the conductor loss of the conductor used as the signal line on the circuit board, etc. In order to reduce transmission loss, it is considered preferable to mainly reduce dielectric loss and conductor loss.

"Dielectric loss" refers to the phenomenon in which when an alternating current electric field is applied to a dielectric from the outside, part of the electrical energy is lost as heat inside the dielectric, and also refers to the energy lost. In addition, in this specification, it is used in both meanings.

Dielectric loss can be calculated using the following formula.
(Formula 3) Dielectric loss (α _d ) = K×f×(ε _r ) ^1/2 × tan δ
[However, K is a proportionality constant, f is a frequency, ε _r is a relative dielectric constant, and tan δ is a dielectric loss tangent. ]

From the above (Formula 3), it can be seen that the larger (higher) the frequency, the larger the value of the dielectric loss, and the smaller the relative dielectric constant and dielectric loss tangent, the smaller the value. Therefore, it can be seen that dielectric loss can be reduced by using a material with a smaller relative dielectric constant and dielectric loss tangent.

"Conductor loss" is a phenomenon in which some of the electrical energy is lost as heat inside the conductor due to the resistance and skin effect of the conductor used as a signal line (wiring) on a circuit board, and It refers to energy.
In addition, "skin effect" refers to the phenomenon in which when an alternating current electric field is applied to a conductor, more current flows toward the outside than the center of the conductor. It occurs when eddy currents are generated inside the conductor due to induced electromotive force and induced current.

In order to reduce conductor loss, it is possible to reduce the resistance of the conductor, but copper is currently used as the conductor material, and the shape of the signal line depends on the design requirements. However, it is difficult to significantly reduce the resistance by changing the conductor material and the shape of the signal line. Therefore, at present, it is difficult to significantly reduce conductor loss, and in order to reduce transmission loss, it is effective to reduce dielectric loss.

The film of the present invention contains filler in addition to resin. It is considered that by containing a relatively large amount of filler with a low dielectric constant and dielectric loss tangent, the dielectric constant and dielectric loss tangent of the film can be lowered.
However, if too much filler is contained, the fillers tend to aggregate with each other, resulting in an increase in the particle size of the filler.

Regarding the relationship between the dispersion state of the filler in the film and the surface free energy of the film, the present inventor found that when the filler is uniformly dispersed, the deviation depending on the measurement location of the surface free energy of the film is relatively small; If there is agglomeration, it is assumed that the deviation depending on the measurement location will be relatively large.
That is, it is estimated that when the filler is uniformly dispersed, the difference in surface free energy measured between two opposing sides of the film can be made relatively small.

In the present invention, it is believed that by manufacturing the film using the manufacturing method described below, it is possible to make the film contain a relatively large amount of filler, and the surface free energy of the film can be adjusted within a specific range. It will be done.
Moreover, it is considered that the filler can be more uniformly dispersed by further containing a surfactant in the film as needed.

2. Structure of the film The film of the present invention is a film containing a resin and a filler, and the dielectric loss tangent of the resin and the filler at a frequency of 28 GHz in an environment of 22° C. and 60% RH are both 0.0150 or less. , the filler content is within the range of 1.0 to 70.0% by mass based on the total mass of the film, and the surface free energy of the two opposing faces of the film is as follows (Formula 1 ) and (Equation 2).
(Formula 1) A≦B
(Formula 2) 1≦B/A<1.30

The film of the present invention contains a resin and a filler. In addition, a surfactant or the like may be contained, if necessary.

(1) Resin The film of the present invention contains resin.
The resin has a dielectric loss tangent of 0.0150 or less at a frequency of 28 GHz in an environment of 22° C. and 60% RH.
The film of the present invention can reduce dielectric loss by containing the resin.

The dielectric loss tangent at a frequency of 28 GHz in an environment of 22° C. and 60% RH is preferably as low as possible; specifically, it is more preferably 0.0140 or less, and even more preferably 0.0100 or less.

The resin is not particularly limited as long as it satisfies the above dielectric loss tangent condition, and examples thereof include thermosetting resins and thermoplastic resins.
Examples of the thermosetting resin include polyimide, polyarylate, maleimide compound, cyanate resin, benzocyclobutene resin, polycarbodiimide, and the like.
Examples of thermoplastic resins include liquid crystal polymers.
These may be used alone or in combination of two or more.

(1.1) Polyimide In the present invention, "polyimide" refers to a polymer containing an imide bond in a repeating unit in its chemical structure, and is a general term thereof.

The polyimide used in the present invention is produced using an aromatic diamine compound and a tetracarboxylic dianhydride through the steps of polymerization to polyamic acid, chemical imidization reaction, formation of powder by precipitation of the polyimide produced, and drying. Preferably, it is produced (manufactured).
The powdered polyimide produced by this method will be described below, but the method for producing polyimide according to the present invention is not limited to this method. Alternatively, commercially available polyimide may be used.

(1.1.1) Powdered polyimide (1.1.1.1) Raw material (aromatic diamine compound)
The aromatic diamine compound, the tetracarboxylic dianhydride, and the polyamic acid are used in a common solvent (for example, It must be soluble in N,N-dimethylacetamide (DMAC).

From this point of view, aromatic diamine compounds include, for example, m-phenylenediamine, p-phenylenediamine, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl ether, 3,3 '-Diaminodiphenylsulfide, 3,4'-diaminodiphenylsulfide, 4,4'-diaminodiphenylsulfide, 3,3'-diaminodiphenylsulfone, 3,4'-diaminodiphenylsulfone, 4,4'-diaminodiphenylsulfone , 3,3'-diaminobenzophenone, 3,3'-diaminodiphenylmethane, 3,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylmethane, 2,2-bis(4-aminophenyl)propane, 2,2- Bis(3-aminophenyl)propane, 2-(3-aminophenyl)-2-(4-aminophenyl)propane, 2,2-bis(4-aminophenyl)-1,1,1,3,3, 3-hexafluoropropane, 2,2-bis(3-aminophenyl)-1,1,1,3,3,3-hexafluoropropane, 2-(3-aminophenyl)-2-(4-aminophenyl) )-1,1,1,3,3,3-hexafluoropropane, 1,3-bis(3-aminophenoxy)benzene, 1,3-bis(4-aminophenoxy)benzene, 1,4-bis( 3-aminophenoxy)benzene, 1,4-bis(4-aminophenoxy)benzene, 4,4'-bis(4-aminophenoxy)biphenyl, 3,3'-bis(4-aminophenoxy)biphenyl, 3, 4'-bis(3-aminophenoxy)biphenyl, bis[4-(4-aminophenoxy)phenyl] sulfide, bis[3-(4-aminophenoxy)phenyl] sulfide, bis[4-(3-aminophenoxy) phenyl]sulfide, bis[3-(4-aminophenoxy)phenyl]sulfide, bis[3-(3-aminophenoxy)phenyl]sulfide, bis[3-(4-aminophenoxy)phenyl]sulfone, bis[4- (4-aminophenyl) sulfone, bis[3-(3-aminophenoxy)phenyl]sulfone, bis[4-(3-aminophenyl)sulfone, bis[4-(3-aminophenoxy)phenyl]ether, Bis[4-(4-aminophenoxy)phenyl]ether, bis[3-(3-aminophenoxy)phenyl]ether, bis[4-(3-aminophenoxy)phenyl]methane, bis[4- (4-aminophenoxy)phenyl]methane, bis[3-(3-aminophenoxy)phenyl]methane, bis[3-(4-aminophenoxy)phenyl]methane, 2,2-bis[4-(3-amino) phenoxy)phenyl]propane, 2,2-bis[4-(4-aminophenoxy)phenyl]propane, 2,2-bis[3-(3-aminophenoxy)phenyl]propane, 2,2-bis[4- (3-aminophenoxy)phenyl]-1,1,1,3,3,3-hexafluoropropane, 2,2-bis[4-(4-aminophenoxy)phenyl]-1,1,1,3, 3,3-hexafluoropropane, 2,2-bis[3-(3-aminophenoxy)phenyl]-1,1,1,3,3,3-hexafluoropropane, 2,2-bis[3-( 4-aminophenoxy)phenyl]-1,1,1,3,3,3-hexafluoropropane, 1,3-bis[4-(4-amino-6-trifluoromethylphenoxy)-α,α-dimethyl benzyl]benzene, 1,3-bis[4-(4-amino-6-fluoromethylphenoxy)-α,α-dimethylbenzyl]benzene, 2,2'-dimethyl-4,4'-diaminobiphenyl, 3, 3'-dimethyl-4,4'-diaminobiphenyl, 3,3'-bis(trifluoromethyl)-4,4'-diaminobiphenyl, 2,2'-bis(trifluoromethyl)-4,4'- Examples include diaminobiphenyl.
These aromatic diamine compounds may be used alone or in combination of two or more.

Among them, from the viewpoint of heat resistance, 2,2-bis(4-aminophenyl)-1,1,1,3,3,3-hexafluoropropane, 2,2-bis(3-aminophenyl)-1, 1,1,3,3,3-hexafluoropropane, 2-(3-aminophenyl)-2-(4-aminophenyl)-1,1,1,3,3,3-hexafluoropropane, 2, 2-bis[4-(3-aminophenoxy)phenyl]-1,1,1,3,3,3-hexafluoropropane, 2,2-bis[4-(4-aminophenoxy)phenyl]-1, 1,1,3,3,3-hexafluoropropane, 2,2-bis[3-(3-aminophenoxy)phenyl]-1,1,1,3,3,3-hexafluoropropane, 2,2 -Bis[3-(4-aminophenoxy)phenyl]-1,1,1,3,3,3-hexafluoropropane, 1,3-bis[4-(4-amino-6-trifluoromethylphenoxy) -α,α-dimethylbenzyl]benzene, 3,3'-bis(trifluoromethyl)-4,4'-diaminobiphenyl, 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl, etc. It is preferably an aromatic diamine compound having a fluoro group, and more preferably 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl.

When two or more types of aromatic diamine compounds are used in combination, at least one type is preferably an aromatic diamine compound having a fluoro group.
By using an aromatic diamine compound having a fluoro group, heat resistance and solubility in a solvent can be further improved.

(Tetracarboxylic dianhydride)
Similar to aromatic diamine compounds, from the viewpoint of solubility in solvents, examples of tetracarboxylic dianhydride include 4,4'-(1,1,1,3,3,3-hexafluoropropane-2 ,2-diyl)diphthalic dianhydride, pyromellitic dianhydride, 3,3',4,4'-benzophenonetetracarboxylic dianhydride, 1,4-hydroquinone dibenzoate-3,3',4 , 4'-tetracarboxylic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 3,3',4,4'-diphenyl ether tetracarboxylic dianhydride, etc. .
These tetracarboxylic dianhydrides may be used alone or in combination of two or more.

Among them, from the viewpoint of heat resistance and solubility in solvents, 4,4'-(1,1,1,3,3,3-hexafluoropropane-2,2-diyl)diphthalic dianhydride is preferred. preferable.

When two or more types of tetracarboxylic dianhydrides are used in combination, at least one type is preferably a tetracarboxylic dianhydride having a fluoro group.
By using a tetracarboxylic dianhydride having a fluoro group, heat resistance and solubility in a solvent can be further improved.

(1.1.1.2) Polymerization to polyamic acid The above-mentioned aromatic diamine compound and tetracarboxylic dianhydride are reacted to polymerize to polyamic acid.

From the viewpoint that the aromatic diamine compound, tetracarboxylic dianhydride, and polyamic acid need to be soluble in a common solvent, N,N-dimethylacetamide, N,N-dimethyl are used as the solvent for polymerization to polyamic acid. Examples include formamide, N-methyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, dimethyl sulfoxide and the like.

The polymerization reaction to form polyamic acid is preferably carried out with stirring in a reaction vessel equipped with a stirring device. Examples of methods for obtaining polyamic acid include a method in which a predetermined amount of an aromatic diamine compound is dissolved in the above solvent, and a reaction is carried out by adding tetracarboxylic dianhydride while stirring; A method in which the reaction is carried out by dissolving the carboxylic dianhydride and adding an aromatic diamine compound while stirring. A method in which the reaction is carried out by adding the aromatic diamine compound and the tetracarboxylic dianhydride alternately to the above solvent. , etc.

The temperature in the polymerization reaction to form polyamic acid is not particularly limited, but is preferably within the range of 0 to 70°C, more preferably within the range of 10 to 60°C, and within the range of 20 to 50°C. It is even more preferable that there be. By falling within the above range, a high molecular weight polyamic acid with little coloration and excellent transparency can be obtained.

In addition, the aromatic diamine compound and tetracarboxylic dianhydride used for polymerization to polyamic acid are approximately equivalent (mole equivalent), but in order to control the degree of polymerization of the resulting polyamic acid, tetracarboxylic dianhydride is The molar amount of anhydride/molar amount of aromatic diamine compound (molar ratio) may be varied within the range of 0.950 to 1.050.

Among them, the molar ratio of the tetracarboxylic dianhydride and the aromatic diamine compound is preferably within the range of 1.001 to 1.020, more preferably within the range of 1.001 to 1.010. . In this way, by adding a slight excess of tetracarboxylic dianhydride, the degree of polymerization of the resulting polyamic acid can be stabilized, and the unit (structural unit) derived from the tetracarboxylic dianhydride can be added to the polymer. Since it can be placed at the end, a polyamic acid with little coloring and excellent transparency can be obtained.

The concentration of polyamic acid in the polyamic acid solution to be produced is within the range of 10 to 30% by mass based on the total mass of the polyamide solution, from the viewpoint of maintaining appropriate viscosity of the solution and facilitating handling in subsequent steps. It is preferable that
Note that the "produced polyamic acid solution" refers to a solution containing a polyamic acid and a solvent that is produced in the method for obtaining the polyamic acid described above.

(1.1.1.3) Chemical imidization reaction An imidization agent is added to the obtained polyamic acid solution to perform a chemical imidization reaction.

Examples of imidizing agents include carboxylic anhydrides such as acetic anhydride, propionic anhydride, succinic anhydride, phthalic anhydride, and benzoic anhydride.From the viewpoint of cost and ease of removal after reaction, Acetic anhydride is preferred. The amount of the imidizing agent added is preferably at least the equivalent of the amide bond of the polyamic acid that undergoes the chemical imidization reaction, and is preferably in the range of 1.1 to 5 times the equivalent of the amide bond.1. More preferably, it is within the range of 5 to 4 times. In this way, by using a slightly excess amount of imidizing agent with respect to the amide bond, the imidizing reaction can be carried out efficiently even at a relatively low temperature.

In addition, in the chemical imidization reaction, aliphatic, aromatic, or heterocyclic tertiary amines such as pyridine, picoline, quinoline, isoquinoline, trimethylamine, and triethylamine can be used as an imidization promoter. By using such amines, the imidization reaction can be carried out efficiently at a relatively low temperature, and as a result, a polyimide with excellent transparency and less coloring during the imidization reaction can be obtained.

The temperature in the chemical imidization reaction is not particularly limited, but is preferably in the range of 10°C or more and less than 50°C, more preferably in the range of 15°C or more and less than 45°C. By carrying out the chemical imidization reaction at a temperature of 10° C. or more and less than 50° C., a polyimide with excellent transparency and less coloring during the imidization reaction can be obtained.

(1.1.1.4) Formation of powder by precipitation of produced polyimide A poor solvent for polyimide is added to the polyimide solution obtained by chemical imidization reaction to precipitate polyimide, forming polyimide powder (precipitation・Powderization).

The poor solvent used for precipitation and powderization of polyimide is a poor solvent that can precipitate polyimide, and is preferably a poor solvent that is miscible with the solvent of the polyimide solution, such as , water, methanol, ethanol and the like. Among these, methanol is preferable from the viewpoint of being able to obtain polyimide powder having a stable average particle diameter.

It is necessary to use a sufficient amount of the poor solvent to precipitate and powderize the polyimide. It can be determined by taking into consideration the following:

Generally, the amount of the poor solvent used is preferably 0.5 times or more, more preferably 0.8 times or more, and 1 time or more relative to the total mass of the polyimide solution. is even more preferable. When the amount is 0.5 times or more with respect to the total mass of the polyimide solution, polyimide powder having a stable average particle diameter can be obtained in high yield.

In addition, the amount of the poor solvent to be used is generally preferably 10 times or less, more preferably 7 times or less, and even more preferably 5 times or less with respect to the total mass of the polyimide solution. Preferably, it is particularly preferably 4 times or less.

Precipitation and powdering of polyimide is preferably carried out by dropping a poor solvent while stirring the polyimide solution. From the viewpoint of easy diffusion of the poor solvent, the polyimide solution concentration (polyimide content based on the total mass of the polyimide solution) is preferably within the range of 5 to 30% by mass, and preferably within the range of 10 to 20% by mass. More preferably, the concentration of the polyimide solution is adjusted within the above range in advance.

Furthermore, it is preferable that the average particle diameter of the obtained polyimide powder is within the range of 0.02 to 0.80 mm. The average particle diameter can be controlled by the addition rate (addition amount per minute) of the poor solvent to the polyimide solution.

The preferable addition rate of the poor solvent depends somewhat on the structure of the polyimide and the concentration of polyimide in the solution. At the latest, immediately before precipitation of polyimide occurs, if the total amount of polyimide solution to be precipitated is Xg, the amount of poor solvent added per minute is preferably 0.0005 to 0.1 times X (g /min), more preferably within the range of 0.001 to 0.05 times of X, and even more preferably within the range of 0.001 to less than 0.04 times of X (g/min), and the addition By maintaining the speed within this range until the precipitation and pulverization of polyimide are completed, polyimide powder with a stable average particle size can be obtained.
For example, when precipitating and pulverizing 1000 g of a polyimide solution (polyimide solution concentration is 15% by mass), the addition rate of the poor solvent is preferably within the range of 0.5 to 100 g/min.

By setting the addition rate (addition amount per minute) of the poor solvent to at least 0.0005 times the total mass of the polyimide solution, the time required for precipitation and pulverization does not become too large, resulting in a decrease in productivity. can be suppressed. Moreover, the average particle diameter of the polyimide powder to be produced can be prevented from becoming too small.

On the other hand, by adding the poor solvent at a rate of 0.1 times or less of the total mass of the polyimide solution, the average particle size of the polyimide powder produced does not become too large, and the removal of volatile components by subsequent drying is prevented. Since it can be carried out efficiently, coloring of polyimide and deterioration of heat resistance can be suppressed.

Although it is necessary to control the addition rate of the poor solvent at the time when polyimide precipitation/powderization occurs, there is no particular need to control it until polyimide precipitation/powderization begins. Therefore, the poor solvent may be added at high speed in the initial stage of adding the poor solvent, before precipitation and pulverization occur. Then, the addition rate may be controlled within the above range immediately before the start of precipitation, that is, immediately before the polyimide solution becomes cloudy and precipitation and pulverization of polyimide are observed. Thereafter, the rate of addition must be maintained until precipitation/pulverization is complete.

The temperature for precipitation and powderization of polyimide is not particularly limited, but from the viewpoint of suppressing evaporation of the poor solvent used and performing precipitation efficiently, it is preferably carried out at 50 ° C. or lower, and it is preferably carried out at 40 ° C. or lower. It is more preferable.

Note that the precipitation and powderization of polyimide can also be carried out by adding a polyimide solution to an excess of a poor solvent, but the polyimide may precipitate in the form of fibers. Therefore, from the viewpoint of obtaining polyimide in a desired particle shape, it is preferable to perform precipitation and pulverization using the above method.

(1.1.1.5) Drying of powder The precipitated polyimide powder is filtered, washed if necessary, and dried.
Note that the polyimide powder obtained by the above method can be washed and dried without the need for further pulverization.

The polyimide powder may be dried at any temperature as long as it can remove the residues of the solvent (solvent added in the polymerization reaction to polyamic acid), imidization agent, imidization accelerator, poor solvent, etc. be able to.

However, when a poor solvent having a hydroxyl group such as methanol or ethanol is used as the poor solvent, the temperature is lower than 100°C until the volatile components in the polyimide powder are preferably less than 5%, more preferably less than 3%. After drying at a temperature of 100 to 350°C, more preferably 150 to 300°C, drying is preferably carried out for 0.1 to 24 hours. Thereby, components that are difficult to volatilize, such as imidization agents and imidization promoters, can also be removed.

In addition, by performing the first stage drying at a temperature of less than 100 ° C., it is possible to suppress the formation of ester bonds due to the reaction of the poor solvent with the carboxylic acid group or carboxylic acid anhydride group in the polyimide. Coloring of polyimide and deterioration of heat resistance can be suppressed.

The second step of drying at a high temperature of 100° C. or higher is preferably carried out in an inert and low-moisture atmosphere from the viewpoint of suppressing coloration of the polyimide and reduction in molecular weight.

Drying of polyimide may be performed under normal pressure or under reduced pressure.
Further, polyimide may be dried, for example, while the temperature is continuously raised from a low temperature of less than 100°C to a high temperature of 100°C or more. In this case, it is preferable that the volatile components contained in the polyimide powder be less than 5% before the drying temperature exceeds 100°C.

The amount of volatile components in the polyimide powder after drying at a temperature of less than 100°C is defined by the following formula.
Mass of polyimide powder after drying at a temperature below 100°C: Ag
Mass of polyimide powder after final drying at a temperature of 100°C or higher: Bg
Amount of volatile components remaining after drying at a temperature below 100°C: (AB)/A x 100%

(1.1.2) Other polyimides The polyimide according to the present invention is not limited to the above powdered polyimide, and commercially available products may be used.
Commercially available polyimide products include the "Neoprim (registered trademark)" series (manufactured by Mitsubishi Gas Chemical Co., Ltd.), the "Spixeria (registered trademark)" series (manufactured by Somar Corporation), and the "Q-PILON (registered trademark)" series (manufactured by Somar Corporation). (manufactured by P.I. Technology Institute), "WINGO" series (manufactured by Wingo Technology Co., Ltd.), "Tomide (registered trademark)" series (manufactured by T&K TOKA Co., Ltd.), "KPI-MX" series (manufactured by Kawamura Sangyo Co., Ltd.), Examples include the "Yupia (registered trademark)-AT" series (manufactured by Ube Industries, Ltd.).

(1.2) Polyarylate In the present invention, "polyarylate" specifically refers to amorphous polyarylate, and refers to a polycondensate of divalent phenol and dibasic acid. Among these, the dibasic acid is preferably an aromatic dicarboxylic acid.

Examples of divalent phenols include bisphenols, such as resorcinol, 2,2-bis(4-hydroxyphenyl)propane, 2,2-bis(4-hydroxy-3,5-dimethylphenyl)propane, , 2-bis(4-hydroxy-3-methylphenyl)propane, 2,2-bis(4-hydroxy-3,5-dibromophenyl)propane, 2,2-bis(4-hydroxy-3,5-dichlorophenyl) ) Propane, 4,4'-dihydroxydiphenyl sulfone, 4,4'-dihydroxydiphenyl ether, 4,4'-dihydroxydiphenyl sulfide, 4,4'-dihydroxydiphenyl ketone, 4,4'-dihydroxydiphenylmethane, 1,1- Examples include bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane and 1,1-bis(4-hydroxyphenyl)cyclohexane.
These may be used alone or in combination of two or more.

By using these bisphenols, the resulting polyarylate becomes amorphous and has better heat resistance. Among them, it is preferable to use 2,2-bis(4-hydroxyphenyl)propane, and it is more preferable to use one type alone.

Aromatic dicarboxylic acids are not particularly limited, but include, for example, terephthalic acid, isophthalic acid, phthalic acid, chlorophthalic acid, nitrophthalic acid, 2,5-naphthalene dicarboxylic acid, 2,6-naphthalene dicarboxylic acid, and 2,7-naphthalene. Dicarboxylic acid, 1,5-naphthalene dicarboxylic acid, methyl terephthalic acid, 4,4'-biphenyl dicarboxylic acid, 2,2'-biphenyl dicarboxylic acid, 4,4'-diphenyl ether dicarboxylic acid, 4,4'-diphenylmethane dicarboxylic acid , 4,4'-diphenylsulfone dicarboxylic acid, 4,4'-diphenylisopropylidene dicarboxylic acid, 1,2-bis(4-carboxyphenoxy)ethane, 5-sodium sulfoisophthalic acid, diphenic acid and derivatives thereof, etc. Can be mentioned.

Examples of the derivatives of aromatic dicarboxylic acids include esters and acid chlorides of alkyls having 1 to 3 carbon atoms in the above-mentioned aromatic dicarboxylic acids.
These may be used alone or in combination of two or more.

Among these, terephthalic acid, isophthalic acid, or derivatives thereof are preferred.
Further, from the viewpoint of achieving both heat resistance and fluidity during film formation, it is more preferable to use a mixture of both terephthalic acid or a derivative thereof and isophthalic acid or a derivative thereof. In this case, the mixing molar ratio (terephthalic acid/isophthalic acid) is not particularly limited, but is preferably within the range of 90/10 to 10/90, and preferably within the range of 70/30 to 30/70. More preferably, it is within the range of 55/45 to 45/55.
By being within the above range, the polyarylate obtained will be amorphous and have better heat resistance.

Polyarylate was prepared by dissolving 1.0 g of polyarylate sample in 100 ml of 1,1,2,2-tetrachloroethane from the viewpoint of improving fluidity, heat resistance, hydrolysis resistance, and mechanical properties when formed into a film. The logarithmic viscosity of the solution at a temperature of 25° C. is preferably within the range of 0.40 to 0.75 dL/g, more preferably within the range of 0.45 to 0.65 dL/g.

Polyarylate can be synthesized by a known method. Alternatively, commercially available products may be used.
Commercially available polyarylate resins include, for example, "U Polymer U Powder D type (log viscosity 0.72), L type (log viscosity 0.54)" and "Unifiner (registered trademark) M-2040" (both (manufactured by Unitika Co., Ltd.).

(1.3) Other thermosetting resins Examples of the maleimide compound used in the present invention include the maleimide compounds described in paragraphs 0047 to 0093 of JP-A No. 2022-061729.
Examples of the cyanate resin used in the present invention include the cyanate resins described in paragraphs 0066 to 0079 of JP-A No. 2022-009110, and the cyanate resins described in paragraph 0046 of JP-A No. 2022-061729. It will be done.

Commercially available maleimide compounds include, for example, "BMI" (manufactured by K.I. Kasei Co., Ltd.), "BMI-4000" (manufactured by Daiwa Kasei Kogyo Co., Ltd.), and "MIR-3000" (manufactured by Nippon Kayaku Co., Ltd.). etc.

(1.4) Liquid crystal polymer In the present invention, "liquid crystal polymer" refers to a thermotropic type of liquid crystal polymer, which is a thermoplastic polymer that exhibits liquid crystal-like properties in which linear chains of molecules are regularly arranged in a molten state. Refers to resin.

Examples of the liquid crystal polymer according to the present invention include liquid crystal polyesters, and among them, liquid crystal polyesters containing structural units represented by the following formulas (a1), (a2), and (a3) are preferable.
(a1) -O-Ar ¹ -CO-
(a2) -CO-Ar ² -CO-
(a3) -X-Ar ³ -Y-
[However, in formula (a1), Ar ¹ represents a 1,4-phenylene group, 2,6-naphthylene group, or 4,4'-biphenylene group, and in formula (a2), Ar ² represents 1,4 - represents a phenylene group, a 1,3-phenylene group or a 2,6-naphthylene group, in formula (a3), Ar ³ represents a 1,4-phenylene group or a 1,3-phenylene group, and X represents -NH -, and Y represents -O- or -NH-. ]

The content of the structural unit represented by formula (a1) is within the range of 30 to 80 mol% with respect to 100 mol% of the total structural units of the liquid crystal polyester, and the content of the structural unit represented by formula (a2) is within the range of 30 to 80 mol%. is preferably within the range of 10 to 35 mol%, and the content of the structural unit represented by formula (a3) is preferably within the range of 10 to 35 mol%.

The structural unit represented by formula (a1) is a structural unit derived from an aromatic hydroxycarboxylic acid, and the structural unit represented by formula (a2) is a structural unit derived from an aromatic dicarboxylic acid, and the structural unit represented by formula (a3) is a structural unit derived from an aromatic dicarboxylic acid. The structural unit is derived from an aromatic diamine or an aromatic amine having a phenolic hydroxyl group.

Among them, Ar ¹ is a 2,6-naphthylene group, Ar ² is a 1,3-phenylene group, Ar ³ is a 1,4-phenylene group, and Y is -O-. is preferred.

Examples of the structural unit represented by formula (a1) include structural units derived from p-hydroxybenzoic acid, 2-hydroxy-6-naphthoic acid, 4-hydroxy-4'-biphenylcarboxylic acid, etc. , is preferably a structural unit derived from 2-hydroxy-6-naphthoic acid.
These may be used alone or in combination of two or more.

The content of the structural unit represented by formula (a1) is preferably in the range of 30 to 80 mol%, and preferably in the range of 40 to 70 mol%, based on 100 mol% of the total structural units of the liquid crystal polyester. It is more preferably within the range of 45 to 65 mol%.

Examples of the structural unit represented by formula (a2) include structural units derived from terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, etc. Among them, structural units derived from isophthalic acid are preferred. .
These may be used alone or in combination of two or more.

The content of the structural unit represented by formula (a2) is preferably in the range of 10 to 35 mol%, and preferably in the range of 15 to 30 mol%, based on 100 mol% of the total structural units of the liquid crystal polyester. It is more preferably within the range of 17.5 to 27.5 mol%.

Examples of the structural unit represented by formula (a3) include structural units derived from 3-aminophenol, 4-aminophenol, 1,4-phenylenediamine, 1,3-phenylenediamine, 4-aminobenzoic acid, etc. Among them, a structural unit derived from 4-aminophenol is preferred.
These may be used alone or in combination of two or more.

The content of the structural unit represented by formula (a3) is preferably in the range of 10 to 35 mol%, and preferably in the range of 15 to 30 mol%, based on 100 mol% of the total structural units of the liquid crystal polyester. It is more preferably within the range of 17.5 to 27.5 mol%.

The liquid crystal polyester can be produced, for example, by the method described in JP-A-2019-163431.

(1.5) Physical properties (1.5.1) Dielectric loss tangent The resin according to the present invention has a dielectric loss tangent of 0.0150 or less at a frequency of 28 GHz in an environment of 22° C. and 60% RH.
In the present invention, "dielectric loss tangent" refers to the degree of electrical energy loss in a dielectric. Therefore, for the resin according to the present invention, the lower the dielectric loss tangent (the closer the value is to 0), the more preferable it is.

The dielectric loss tangent can be adjusted to a desired value by appropriately selecting the molecular structure, polymerization ratio, etc. of the monomers in the resin.

(Measurement method of dielectric loss tangent)
The dielectric loss tangent of the resin according to the present invention can be measured in accordance with JIS R1641:2007.
A test piece of 100 mm x 120 mm in size was prepared for the resin (mixed resin when two or more types are used together), and before measurement, the test piece was prepared in advance at a temperature of 22 ± 1 ° C. and a humidity of 60 ± 5% RH in an environment. Store for 90 hours. Thereafter, the dielectric loss tangent at a frequency of 28 GHz is measured by the cylindrical cavity method.

(1.5.2) Glass transition temperature The resin according to the present invention preferably has a glass transition temperature of 200°C or higher. By being 200° C. or higher, the film can be made heat resistant and can be used in 5G-compatible communication equipment, which is expected to generate more heat as the amount of information increases.

Regarding the glass transition temperature, when resins are used together, it is preferable that each resin has a glass transition temperature of 200°C or higher, and the desired glass transition temperature can be achieved by appropriately selecting the molecular structure of the monomer, polymerization method, polymerization ratio, etc. in the resin. can be adjusted to the value of

(Measurement method of glass transition temperature)
A test piece of 5 mm x 40 mm size was prepared for the resin (mixed resin when two or more types are used together), and the test piece was placed in a dynamic viscoelasticity device "RSA-G2" (T.A. Instruments). (manufactured by Mento Japan Co., Ltd.). While applying strain to the test piece in a nitrogen stream at a frequency of 1 Hz, the temperature was raised from 0°C to 450°C, the tensile storage modulus E' and the tensile loss modulus E'' were measured, and the loss tangent (tan δ = E''/E') is calculated. The temperature at the peak top of the loss tangent is defined as the glass transition temperature (Tg) of the resin.

(2) Filler The film of the present invention contains a filler.
The filler according to the present invention has a dielectric loss tangent of 0.0150 or less at a frequency of 28 GHz in an environment of 22° C. and 60% RH.
Further, the filler content is within the range of 1.0 to 70.0% by mass based on the total mass of the film.
The film of the present invention can reduce dielectric loss by containing a relatively large amount of filler having a low dielectric loss tangent.

In the present invention, "filler" refers to fine particles, fibers, or additives added for the purpose of reducing dielectric loss of the film. It may also include those that eventually phase separate in the film and are distributed like islands in the sea.
That is, when comparing the dielectric loss expressed by the above (Formula 3) in a film of a resin that does not contain a filler (or a mixed resin when two or more types are used together) and a film that contains a filler, Dielectric loss is reduced in films containing fillers.

As mentioned above, from the viewpoint of reducing dielectric loss, it is preferable to contain a relatively large amount of filler, but if a large amount of filler is contained, the surface free energy of the film will be reduced by the above (Formula 1) and (Formula 2) It becomes difficult to make adjustments within the range that satisfies the above.

However, by using the film manufacturing method described below, it is considered that the surface free energy of the film can be adjusted within a specific range and the filler can be contained in a relatively large amount.
Note that the method for manufacturing the film of the present invention is not particularly limited, and methods other than the film manufacturing method described below may be used.

The content of the filler is within the range of 1.0 to 70.0% by mass based on the total mass of the film. Further, it is preferably within the range of 10.0 to 60.0% by mass, and more preferably within the range of 15.0 to 50.0% by mass.

The filler according to the present invention is not particularly limited as long as it has a dielectric loss tangent of 0.0150 or less at a frequency of 28 GHz in an environment of 22° C. and 60% RH. Examples include fine particles.
As for the liquid crystal polymer, the same one as the liquid crystal polymer in the above resin can be used, but the physical properties and the like when used as a filler will be described later.

(2.1) Fluororesin fine particles In the present invention, the fluororesin fine particles are preferably mixed with the above resin as a non-aqueous dispersion.
The fluororesin dispersion contains fluororesin fine particles and at least a fluorine additive having a fluorine-containing substituent and a hydrophobic group, and has a water content of 5000 mass ppm or less by Karl Fischer method. , not particularly limited.

The fluororesin dispersion can be prepared using, for example, fluororesin fine particles having an average primary particle diameter of 1 μm or less, a fluorine-based additive containing a fluorine-containing substituent and a hydrophobic group, a solvent, and the like.

Examples of fluororesin fine particles include polytetrafluoroethylene (PTFE), fluorinated ethylene-propylene copolymer (FEP), perfluoroalkoxy polymer (PFA), chlorotrifluoroethylene (CTFE), and tetrafluoroethylene-chloro. Examples include trifluoroethylene copolymer (TFE/CTFE), ethylene-chlorotrifluoroethylene copolymer (ECTFE), polychlorotrifluoroethylene (PCTFE), etc. Among them, it has a low dielectric loss tangent and a low dielectric constant. From this point of view, polytetrafluoroethylene (PTFE, dielectric constant 2.1) is preferable.
These may be used alone or in combination of two or more.

The method for producing fluororesin fine particles is not particularly limited, but it is preferably an emulsion polymerization method, such as the method described in the Fluororesin Handbook (edited by Takaomi Satokawa, Nikkan Kogyo Shimbun), etc., which is commonly used. It can be produced by a method.
Then, the fluororesin fine particles produced by the emulsion polymerization method are aggregated and dried, and recovered as a fine powder in the form of secondary particles in which the primary particles are aggregated.

The average primary particle diameter of the fluororesin fine particles is preferably 1 μm or less, more preferably 0.5 μm or less, and even more preferably 0.3 μm or less. Since the average primary particle diameter is 1 μm or less, it is difficult to sediment and can be stably dispersed even in a highly hydrophobic solvent.
Further, the average primary particle diameter is preferably as small as possible, but from the viewpoint of ease of manufacture, it is preferably 0.05 μm or more.

Note that the "average primary particle diameter" here refers to the volume-based average particle diameter (50% volume diameter, median diameter) measured by laser diffraction/scattering method, dynamic light scattering method, image imaging method, etc. It refers to

The average primary particle diameter of the fluororesin fine particles is preferably a value obtained by a laser diffraction/scattering method, a dynamic light scattering method, etc. in the production stage. In the fine powder state after drying, the fluororesin fine particles are in the state of secondary particles, and the cohesive force between the primary particles is strong, so the primary particle diameter can be easily measured by laser diffraction/scattering method, dynamic light scattering method, etc. In this case, it may be a value obtained by an image imaging method because it is difficult to do so.

Measuring devices and methods include, for example, the dynamic light scattering method using a concentrated particle size analyzer “FPAR-1000” (manufactured by Otsuka Electronics Co., Ltd.), and the particle size distribution measuring device “Microtrack” (manufactured by Nikkiso Co., Ltd.). Examples include laser diffraction/scattering methods, and image imaging methods using image analysis particle size distribution measurement software "Macview" (manufactured by Mountec Co., Ltd.).

The content of fluororesin in the fluororesin dispersion is preferably within the range of 5 to 70% by mass, more preferably within the range of 10 to 50% by mass, based on the total mass of the fluororesin dispersion. preferable.

By having a fluororesin content of 5% by mass or more in the fluororesin dispersion, the amount of solvent does not become too large and a suitable viscosity is maintained, making it difficult for the fluororesin fine particles to settle and stably. Can be dispersed. In addition, when the content is 70% by mass or less, the fluororesin fine particles are less likely to aggregate with each other and can be stably dispersed.

The fluorine-based additive that can be used in the fluororesin dispersion is not particularly limited as long as it has at least a fluorine-containing substituent and a hydrophobic group, and may also have a hydrophilic group.

By using a fluorine-based additive, it is possible to lower the surface tension of the highly hydrophobic solvent that is the dispersion medium, improve the wettability of the surface of the fluororesin particles, and improve the dispersibility of the fluororesin particles. . In addition, the fluorine-containing substituent in the fluorine-based additive is adsorbed on the surface of the fluororesin fine particles, and the hydrophobic group in the fluorine-based additive extends into a highly hydrophobic solvent. Resin fine particles are less likely to aggregate and can be more stably dispersed.

Examples of the fluorine-containing substituent in the fluorine-based additive include a perfluoroalkyl group and a perfluoroalkenyl group. Examples of the hydrophobic group include an alkyl group, a phenyl group, and a siloxane group, and these may be used alone or in combination of two or more. Examples of the hydrophilic group include ethylene oxide, amide group, ketone group, carboxyl group, and sulfone group, and one type may be used alone or two or more types may be used in combination.

Commercially available fluorine-based additives include the "Surflon (registered trademark) series" (manufactured by AGC Seimi Chemical Co., Ltd.) such as Surflon (registered trademark) S-611 containing perfluoroalkyl groups, and Megafac (registered trademark) F. -555, Megafac (registered trademark) F-558, Megafac (registered trademark) F-563, etc., "Megafac (registered trademark) series" (manufactured by DIC), Unidyne (registered trademark), such as Unidyne DS-403N, etc. (Unidyne) series (manufactured by Daikin Industries, Ltd.).
These may be used alone or in combination of two or more.

The content of the fluorine-based additive in the fluororesin dispersion is preferably within the range of 0.1 to 50% by mass, and preferably within the range of 5 to 35% by mass, based on the total mass of the fluororesin fine particles. The content is more preferably within the range of 15 to 25% by mass.

When the content of the fluorine-based additive in the fluororesin dispersion is 0.1% by mass or more, the surface of the fluororesin fine particles can be sufficiently wetted with the solvent. Further, by setting the content to 50% by mass or less, it is possible to suppress the foaming of the dispersion from becoming strong and the efficiency of dispersion from decreasing.

In the fluororesin fine particle dispersion, other surfactants may be used in combination with the above-mentioned fluororesin additives to the extent that the effects of the present invention are not impaired. Other surfactants are not particularly limited, and nonionic, anionic, cationic, and other surfactants (details will be described later) can be used.

Examples of the solvent used in the fluororesin fine particle dispersion include acetone, methyl ethyl ketone, hexane, heptane, octane, 2-heptanone, cycloheptanone, cyclohexanone, cyclohexane, methylcyclohexane, ethylcyclohexane, methyl-n-pentylketone, and methyl. Isobutyl ketone, methyl isopentyl ketone, ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, ethylene glycol monoacetate, ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, diethylene glycol monoacetate, diethylene glycol diethyl ether, propylene glycol monoacetate , dipropylene glycol monoacetate, propylene glycol diacetate, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, cyclohexyl acetate, ethyl 3-ethoxypropionate, dioxane, methyl lactate, ethyl lactate, methyl acetate , ethyl acetate, butyl acetate, methyl pyruvate, ethyl pyruvate, methyl methoxypropionate, ethyl ethoxypropionate, anisole, ethyl benzyl ether, cresyl methyl ether, diphenyl ether, dibenzyl ether, phenethol, butylphenyl ether, benzene, Ethylbenzene, diethylbenzene, pentylbenzene, isopropylbenzene, toluene, xylene, cymene, mesitylene, methanol, ethanol, isopropanol, butanol, methyl monoglycidyl ether, ethyl monoglycidyl ether, butyl monoglycidyl ether, phenyl monoglycidyl ether, methyl diglycidyl ether , ethyl diglycidyl ether, butyl diglycidyl ether, phenyl diglycidyl ether, methylphenol monoglycidyl ether, ethylphenol monoglycidyl ether, butylphenol monoglycidyl ether, mineral spirit, 2-hydroxyethyl acrylate, tetrahydrofurfuryl acrylate, 4-vinyl Pyridine, 2-ethylhexyl acrylate, 2-hydroxyethyl methacrylate, hydroxypropyl methacrylate, glycidyl methacrylate, neopentyl glycol diacrylate, hexanediol diacrylate, trimethylolpropane triacrylate, methacrylate, methyl methacrylate, styrene, perfluorocarbon, hydrofluoroether , hydrochlorofluorocarbon, hydrofluorocarbon, perfluoropolyether, dimethylimidazoline, tetrahydrofuran, pyridine, formamide, acetanilide, dioxolane, o-cresol, m-cresol, p-cresol, phenol, N-methyl-2-pyrrolidone, N -Acetyl-2-pyrrolidone, N,N-dimethylformamide, N,N-diethylformamide, N,N-dimethylacetamide, N,N-diethylacetamide, 1,3-dimethyl-2-imidazolidinone, dimethylsulfoxide, Examples include diethyl sulfoxide, dimethyl sulfone, diethyl sulfone, γ-butyrolactone, sulfolane, halogenated phenols, and various silicone oils.
These may be used alone or in combination of two or more.

Among them, formamide, acetanilide, dioxolane, o-cresol, m-cresol, p-cresol, N-methyl-2-pyrrolidone, N-acetyl-2-pyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide , dimethyl sulfoxide, γ-butyrolactone, sulfolane, halogenated phenols, xylene, and acetone.

Depending on the polarity of the solvent, it may be highly compatible with water, but if the water content is too large, it may inhibit the dispersibility of the fluororesin fine particles in the solvent, causing increased viscosity and aggregation of particles. There is sex.

Therefore, it is preferable that the water content of the solvent as determined by Karl Fischer method is within the range of 0 to 5000 ppm by mass. The moisture content is measured by the Karl Fischer method in accordance with JIS K 0068:2001, and can be measured using, for example, a Karl Fischer moisture meter "MCU-610" (manufactured by Kyoto Denshi Kogyo Co., Ltd.).

When the water content in the solvent is within the above range, it is possible to obtain a fluororesin fine particle dispersion having a finer particle size, lower viscosity, and excellent storage stability. The water content in the solvent is preferably 3000 mass ppm or less, more preferably 2500 mass ppm or less, and even more preferably 2000 mass ppm or less.
Note that the water content in the solvent can be adjusted by using a commonly used method for dehydrating organic solvents, for example, using molecular sieves or the like.

The solvent can further contain an antifoaming agent. When the content of fluororesin fine particles in the fluororesin fine particle dispersion is relatively high, or when the content of fluorine-based additives in the fluororesin fine particles is relatively high, foaming of the dispersion can be suppressed by using an antifoaming agent. It can be suppressed.

Examples of antifoaming agents include silicone emulsion type, self-emulsifying type, oil type, oil compound type, solution type, powder type, and solid type. The antifoaming agent is preferably present at the interface between the solvent and air rather than at the interface between the solvent and the fluorine-based additive, and is preferably an antifoaming agent that exhibits hydrophilicity or water solubility.
The content of the antifoaming agent is appropriately selected depending on the content of the fluororesin fine particles, but is preferably 1% by mass or less based on the total mass of the fluororesin fine particle dispersion.

The average particle diameter of the fluororesin fine particles in the fluororesin fine particle dispersion is preferably 1 μm or less. In addition, the average particle diameter here is an average particle diameter measured by a laser diffraction/scattering method or a dynamic light scattering method.

Even when using fluororesin fine particles with an average primary particle size of 1 μm or less, the primary particles aggregate to form secondary particles in the dispersion, and the particle size of the secondary particles exceeds 1 μm. In some cases, In the dispersion, not only the primary particles but also the secondary particles have a particle diameter of 1 μm or less, thereby making it possible to obtain a dispersion with low viscosity and stability even during long-term storage.

In addition, as a method for dispersing the particle size of the primary particles or secondary particles in the dispersion to 1 μm or less, for example, an ultrasonic dispersion machine, a three-roll mill, a wet ball mill, a bead mill, a wet jet mill, a high-pressure homogenizer, etc. can be used. An example is a method of dispersing using

The fluororesin fine particle dispersion preferably has a moisture content in the range of 0 to 5000 ppm by mass as measured by Karl Fischer method. In addition to the amount of water contained in the solvent, water contained in the materials themselves such as fluororesin particles and fluorocarbon additives, and moisture mixed in during the manufacturing process of dispersing fluororesin particles in the solvent can be considered. Finally, by controlling the water content in the dispersion to 5000 mass ppm or less, storage stability can be improved.
The water content in the dispersion is preferably 3000 mass ppm or less, more preferably 2500 mass ppm or less, and even more preferably 2000 mass ppm or less.

To adjust the moisture content in materials such as fluororesin fine particles and fluorine additives, commonly used dehydration methods can be used, for example, molecular sieves can be used. Further, dehydration may be performed by heating or reducing pressure.
Furthermore, after preparing the fluororesin fine particle dispersion, water may be removed using molecular sieves, membrane separation, or the like. Methods other than those described above can be used without particular limitation as long as they can reduce the amount of water in the dispersion.

(2.2) Physical properties (2.2.1) Dielectric loss tangent The filler according to the present invention has a dielectric loss tangent of 0.0150 or less at a frequency of 28 GHz in an environment of 22° C. and 60% RH.

The dielectric loss tangent at a frequency of 28 GHz in an environment of 22° C. and 60% RH is preferably as low as possible from the viewpoint of reducing dielectric loss. Specifically, it is more preferably 0.0140 or less, and 0.0100 or less. It is even more preferable that there be.

The dielectric loss tangent can be adjusted to a desired value by appropriately selecting the molecular structure, polymerization ratio, etc. of the monomer in the filler.

(Measurement method of dielectric loss tangent)
The dielectric loss tangent of the filler according to the present invention can be measured in accordance with JIS R1641:2007.
15 g of filler is filled into an alumina crucible and heat treated at an electric furnace temperature of 1000° C. for 4 hours. After the heat treatment, it is cooled to 200° C. in a furnace, and further cooled to room temperature (25° C.) in a desiccator (23° C., 10% RH). Thereafter, the dielectric loss tangent at a frequency of 28 GHz is measured by the cylindrical cavity method. After the sample is cooled to room temperature, it is stored in a stand pack of an aluminum pack (PET/AL/PE laminate bag, manufactured by Seisaku Nippon Sha Co., Ltd.) until measurement and evaluation are performed.

(2.2.2) Glass transition temperature The filler according to the present invention preferably has a glass transition temperature of 260°C or higher. By being 260° C. or higher, the film can be made heat resistant and can be used in 5G-compatible communication equipment, which is expected to generate more heat as the amount of information increases.

Regarding the glass transition temperature, when fillers are used in combination, it is preferable that each filler has a glass transition temperature of 260°C or higher, and the glass transition temperature can be adjusted to a desired temperature by appropriately selecting the molecular structure of the monomer, polymerization method, polymerization ratio, etc. in the filler. can be adjusted to the value of

(Measurement method of glass transition temperature)
Using a differential scanning calorimeter "Q-100" (manufactured by T.A. Instruments Japan), 0.01 to 0.02 g of filler sample was weighed into an aluminum pan and heated to 200°C. , and cooled from that temperature to 0°C at a cooling rate of 10°C/min. Next, the sample is heated at a heating rate of 10° C./min, and the endothermic peak is measured. The temperature at the intersection of the extension line of the baseline below the highest endothermic peak temperature and the tangent line showing the maximum slope from the rising part of the peak to the top of the peak is defined as the glass transition temperature.

(2.3) Shape The filler according to the present invention is preferably fine particles from the viewpoint of uniform mixing with the resin according to the present invention, that is, from the viewpoint of dispersibility.

The shape of the filler is not particularly limited, and may be, for example, plate-shaped, spherical, polyhedral-shaped such as a cube, etc. In addition, "plate-like" refers to one in which the thickness of the filler is sufficiently smaller than the major axis or the minor axis of the flat part, preferably 1/2 or less, and further subdivided into, for example, flat-shaped , plate-like, flaky-like, scale-like, etc.

(3) Surfactant The film of the present invention preferably further contains a surfactant.
By containing the surfactant, the filler can be more uniformly dispersed in the film, that is, the dispersibility can be improved.

The surfactant is not particularly limited as long as it improves the dispersibility of the filler, and examples thereof include nonionic surfactants, anionic surfactants, cationic surfactants, and the like. Further, a polymer type surfactant such as polyvinyl alcohol or a derivative thereof may be used. Among these, nonionic surfactants are preferred from the viewpoint of reducing the dielectric loss tangent of the film.
The surfactants may be used alone or in combination of two or more.

When using fluororesin fine particles as the filler, the surfactant is preferably a fluorine-based surfactant having at least a fluorine-containing group and a hydrophilic group. By being a fluorine-based surfactant, it lowers the surface tension of the resin as a dispersion medium, improves the wettability of the surface of the fluororesin fine particles, and improves the dispersibility of the fluororesin fine particles. In addition, the fluorine-containing groups are adsorbed on the surface of the fluororesin fine particles, and the hydrophilic groups extend into the resin that serves as the dispersion medium, and the steric hindrance of these hydrophilic groups suppresses aggregation of the fluororesin fine particles, improving dispersion stability. Further improvement.

Examples of the fluorine-containing group include a perfluoroalkyl group and a perfluoroalkenyl group.
Examples of the hydrophilic group include ethylene oxide, propylene oxide, amino group, ketone group, carboxyl group, and sulfone group.
These may be used alone or in combination of two or more.

The fluorosurfactant may further have a hydrophobic group. Examples of the hydrophobic group include an alkyl group, a phenyl group, and a siloxane group.
These may be used alone or in combination of two or more.

Commercially available fluorosurfactants include, for example, the "Ftergent (registered trademark) series" (manufactured by Neos Co., Ltd.), the "Surflon (registered trademark) series" (manufactured by AGC Seimi Chemical Co., Ltd.), and the "Megafac (trademark) series" (manufactured by AGC Seimi Chemical Co., Ltd.). (registered trademark) series" (manufactured by DIC Corporation), "Unidyne (registered trademark) series" (manufactured by Daikin Industries, Ltd.), and the like.

It is preferable to select the most suitable fluorosurfactant depending on the resin used and the type of fluororesin fine particles used as a filler, and one type may be used alone or two or more types may be used in combination. Further, surfactants other than fluorosurfactants may be used in combination.

In addition, when using something other than fluororesin fine particles as the filler, polyoxyethylene lauryl ether, etc. can be used as the surfactant, and commercially available products include, for example, "Emulgen (registered trademark) series" (Kao Co., Ltd.), etc.

The content of the surfactant is preferably within the range of 0.10 to 1.00% by mass, and preferably within the range of 0.20 to 0.50% by mass, based on the total mass of the film. More preferred.

When the content of the surfactant is 0.10% by mass or more, the dispersion of the filler can be made more uniform (improvement of dispersibility), and when the content is 1.00% by mass or less, the film It is possible to suppress the surfactant from bleeding out onto the surface and improve adhesion.

(4) Others The film of the present invention may further contain inorganic fine particles, organic fine particles, plasticizers, curing accelerators, coupling agents, pigments, and flame retardants as optional ingredients as necessary to the extent that the effects of the invention are not impaired. etc. may be contained as appropriate.

Examples of inorganic fine particles include aluminum oxide, beryllium oxide, niobium oxide, titanium oxide, boron nitride, aluminum nitride, silicon nitride, aluminum fluoride, calcium fluoride, magnesium fluoride, potassium fluorosilicate, phosphinate metal salts, etc. Can be mentioned.
These may be used alone or in combination of two or more.

3. Physical properties of the film (1) Surface free energy The film of the present invention satisfies the following formula when the surface free energies of the two opposing surfaces are A [mJ/m ² ] and B [mJ/m ² ], respectively. .
(Formula 1) A≦B
(Formula 2) 1≦B/A<1.30

"Surface free energy" refers to the free energy per unit area on the surface, that is, the excess energy that the surface has compared to the interior (bulk). Note that the larger the surface free energy, the more easily gases and fine particles are adsorbed on the surface, and the easier it is for liquids to wet the surface.

The "two opposing surfaces" of the film of the present invention refer to the two surfaces with the largest area, and these two surfaces are in a parallel relationship.

In the above (Formula 1), of the surface free energies measured on two surfaces, the relatively lower one is A [mJ/m ² ], and the relatively higher one is B [mJ/m ² ]. means to do so.
In addition, if the above (Equation 2) is satisfied, that is, the ratio of the surface free energy measured on the two opposing surfaces is within a specific range, that is, the surface free energy measured on the two opposing surfaces It is thought that because the difference in energy is relatively small, the adhesion to the copper foil layer is excellent.

The film of the present invention is preferably laminated to a metal plate such as a copper foil layer and used as a metal-clad laminate. This metal-clad laminate, which will be described in detail later, is obtained by laminating the film of the present invention and a metal plate via an adhesive layer.
Furthermore, when the film of the present invention is used in a multilayer circuit board, two surfaces of the film of the present invention are bonded to other materials via an adhesive layer.

As mentioned above, surface free energy represents the ease with which gases and fine particles adsorb onto the surface, and the ease with which liquids wet the surface. If there is a difference, a material suitable for forming the adhesive layer on one side may not be suitable for forming the adhesive layer on the other side from the viewpoint of adhesion. Specifically, if there is a large difference in surface free energy, if an adhesive layer is formed using the same material on both sides of the film, the degree of shrinkage due to curing (curing shrinkage) will differ, causing a difference between the film and the other material bonded to it. may peel off.

However, in the film of the present invention, the ratio of the surface free energies is within a specific range, that is, the difference in the surface free energies measured on the two surfaces is relatively small. Even if the same material is used to form the adhesive layers on both sides, the curing shrinkage of the film is the same, so it is difficult to peel off and it is considered that the adhesive layer is excellent.
Furthermore, since the same material can be used to form the adhesive layer, productivity is thought to be improved.

Note that the film of the present invention has a remarkable effect when the copper foil layer is adhered to both sides of the film, but it also shows sufficient effect when the copper foil layer is adhered to only one side of the film.

In addition, in the metal-clad laminate described below, the adhesive layer is not essential, and for example, copper may be deposited directly on the film of the present invention to form a copper foil layer, and the copper foil layer formed in this way Also, it is considered that the adhesion with the film is excellent.

The surface free energies of the film of the present invention measured on two opposing surfaces are preferably both within the range of 25.00 to 75.00 mJ/m ² . When both surface free energies are 25.00 mJ/m ² or more, the adhesion with the copper foil layer is excellent, and when both are 75.00 mJ/m ² or less, dielectric loss can be further reduced. That is, it is possible to achieve both reduction in dielectric loss of the film and adhesion between the film and the copper foil layer.
Further, it is more preferable that the surface free energies measured on the two opposing surfaces are both within the range of 35.00 to 65.00 mJ/m ² .

The surface free energy measured on two opposing surfaces of the film of the present invention can be adjusted to a desired value by appropriately selecting the type, content, etc. of the material used in the film. Further, by producing (manufacturing) a film using the film manufacturing method described below, it is possible to adjust the value to a desired value.

(Method of measuring surface free energy)
Hereinafter, a method of calculating the surface free energy of a solid by dropping a known liquid onto the solid surface and measuring the contact angle will be described.

Regarding the wetting phenomenon shown in FIG. 1, Young's equation (Equation 7) below holds true.
(Formula 7) γ _S = γ _L・cos θ+γ _SL (Young's equation)
However, each symbol is as shown below.
γ _S : Surface tension of solid [N/m]
γ _L : Surface tension of liquid [N/m]
γ _SL : Solid-liquid interfacial tension [N/m]
θ: contact angle of liquid to solid

Here, the surface tension is defined as the tension acting on a unit length (unit: [N/m]). However, surface tension = force/length = (force x length)/(length x length) = energy/area, and the units of surface tension of a solid and surface free energy of a solid are different. The values of things match. Therefore, by determining γ _S , the surface free energy of the solid can be determined.
Note that the surface tension of a liquid, the surface free energy of a liquid, and the interfacial tension between a solid and a liquid and the interfacial free energy between a solid and a liquid can also be considered in the same way.

On the other hand, consider separating the solid and liquid at the interface when the solid is wet with a liquid.
An interfacial free energy γ _SL exists at the solid-liquid interface. Furthermore, if the energy required to separate this interface is expressed as the adhesion work _WSL , then as shown in Fig. 2, the sum of energy is equal before and after separating the interface, so the following (Equation 8) dupre (Dupre) ) holds true.
(Formula 8) γ _S + γ _L = W _SL + γ _SL (Dupré's equation)

The following (Formula 9) can be calculated from Young's formula and Dupre's formula.
(Formula 9) W _SL =γ _L (1+cosθ)
Therefore, the work of adhesion W _SL can be calculated by measuring the contact angle θ using a liquid whose surface free energy is known, that is, a liquid whose γ _L is known.

There are several theories on how to express the work of adhesion _WSL , and in the present invention, _WSL is expressed using the Kitazaki-Hata equation.

According to the idea proposed by Kitazaki and Hata, the surface free energy γ is divided into three components: a dispersion component γ ^d , a dipole component γ ^p and a hydrogen bond component γ ^h , and can be expressed as the following (Equation 10). can.
(Formula 10) γ=γ ^d + γ ^p + γ ^h
Therefore, the surface free energies γ _S and γ _L of solids and liquids can be expressed by the following (Formula 11) and (Formula 12).
(Formula 11) γ _S = γ _S ^d + γ _S ^p + γ _S ^h
(Formula 12) γ _L = γ _L ^d + γ _L ^p + γ _L ^h

Further, according to the idea proposed by Kitazaki and Hata, the adhesion work _WSL can be expressed by the following (Equation 13).
(Formula 13) W _SL =2×(γ _S ^d・γ _L ^d ) ^1/2 +2×(γ _S ^p・γ _L ^p ) ^1/2 +2×(γ _S ^h・γ _L ^h ) ^1/2

From the above (Formula 9) and (Formula 13), the following (Formula 14) can be calculated.
(Formula 14) (γ _S ^d・γ _L ^d ) ^1/2 + (γ _S ^p・γ _L ^p ) ^1/2 + (γ _S ^h・γ _L ^h ) ^1/2 = γ _L (1+cosθ)/2

The contact angle θ is measured using a liquid whose surface free energy is known, and a three-dimensional linear equation with unknown components (γ _S ^d , γ _S ^p , γ _S ^h ) in the surface free energy of the solid is solved, and ( By substituting into Equation 11), the surface free energy γ _S of the solid can be calculated.

Specifically, water, diiodomethane, and hexadecane were used as liquids whose surface free energy and the values of each component (dispersion component, dipole component, and hydrogen bond component) were known, and in an environment of 22°C and 60% RH. The contact angle of each liquid on the film of the present invention is measured using a contact angle meter "DropMaster DM501" (manufactured by Kyowa Interface Science Co., Ltd.).

The detailed measurement method includes two points in the TD direction of the film (the width direction of the film to be manufactured): the center of the film, the edges (positions 10 cm from both ends), and the midpoint between the center and the edges. The contact angle was measured at a total of five points, and the arithmetic mean value was taken as the value of the contact angle θ.

(2) Dielectric loss tangent The film of the present invention preferably has a dielectric loss tangent in a range of 0.0010 to 0.0150 at a frequency of 28 GHz in an environment of 22° C. and 60% RH.
As for the film of the present invention, the lower the dielectric loss tangent (the closer the value is to 0), the more preferable it is. However, when it is 0.0020 or more, the adhesiveness with the copper foil layer is improved.

The dielectric loss tangent at a frequency of 28 GHz in an environment of 22° C. and 60% RH is preferably within the range of 0.0010 to 0.0150, more preferably within the range of 0.0010 to 0.0070.

The dielectric loss tangent can be adjusted to a desired value by appropriately selecting the type, content, etc. of the material used for the film. Further, by producing (manufacturing) a film using the film manufacturing method described below, it is possible to adjust the value to a desired value.

(Measurement method of dielectric loss tangent)
The dielectric loss tangent of the film of the present invention can be measured in accordance with JIS R1641:2007.
Regarding the film of the present invention, a test piece with a size of 100 mm x 120 mm is prepared and stored for 90 hours in an environment with a temperature of 22±1° C. and a humidity of 60±5% RH before measurement. Thereafter, the dielectric loss tangent at a frequency of 28 GHz is measured by the cylindrical cavity method.

(3) Transmission loss The transmission loss of the film of the present invention at a frequency of 28 GHz in an environment of 23° C. and 65% RH is preferably 1.5 dB/10 mm or less, and preferably 0.5 dB/10 mm or less. More preferred. Because the transmission loss is 1.5 dB/10 mm or less, in other words, the film sufficiently suppresses the deterioration and attenuation of electrical, light, sound, etc. signals flowing on the circuit board, making it suitable for 5G compatible communication equipment. It can also be used in

(Method of measuring transmission loss)
One side of the film (one side of the two sides), an adhesive component such as an adhesive sheet, and a 2 μm thick copper plate are laminated with the adhesive sheet in the middle, and then heated at 90°C using a heat press, for example. After thermocompression bonding at 0.5 MPa for 0.5 minutes, the film, cured adhesive sheet, and copper plate were post-cured at 180°C, 2.0 MPa for 5 minutes, and then at 180°C for 1 hour. A laminate is obtained by sequentially laminating the layers.

Thereafter, a microstrip line with a wiring width of 140 μm and a length of 100 mm was formed as a circuit pattern on the surface of the copper foil layer by chemical etching so that the characteristic impedance was 50Ω, and this was used as a sample. Immediately after leaving the sample in an environment with a temperature of 23°C and a humidity of 65% RH for 24 hours, a network analyzer "8722ES" (manufactured by Agilent Technology Co., Ltd.) and a probe "ACP40-250" (manufactured by Cascade Microtech Co., Ltd.) were installed. The transmission loss (dB/10mm) at 28GHz is measured using

(4) Residual Solvent The amount of residual solvent in the film of the present invention is preferably within the range of 200 to 3000 ppm by mass.
Although the method for producing the film of the present invention is not particularly limited, when producing (manufacturing) the film by the method for producing a film described below, it is preferable that the amount of residual solvent is within the above range. By being within the above range, performance stability and production efficiency can be ensured. Note that "performance" here includes the performance of the film in addition to the effects of the present invention, which reduce the dielectric loss of the film and improve the adhesion between the film and the copper foil layer. It will be done.

The amount of residual solvent is more preferably within the range of 400 to 2000 mass ppm, and even more preferably within the range of 500 to 1500 mass ppm. Although it depends on the type of solvent, the effect on electrical properties will be reduced as the amount of residual solvent is reduced, but if the drying load is too high, productivity may deteriorate, so select a solvent while looking at the balance between performance and productivity. Bye.

The amount of residual solvent can be adjusted to a desired value by appropriately selecting the drying conditions and the like in the film manufacturing method.

(Method for measuring residual solvent amount)
The amount of residual solvent in the film of the present invention can be qualitatively and quantitatively determined by headspace gas chromatography. In headspace gas chromatography, a sample is sealed in a container, heated, and while the container is filled with volatile components, the gas in the container is immediately injected into a gas chromatograph, and the compounds are identified by mass spectrometry. Quantify volatile components while Quantification of volatile components is performed by preparing a calibration curve in advance using a sample whose concentration is known, and comparing the peak area of the volatile component obtained by measurement with the calibration curve.

The measurement conditions are shown below.
Head space device: HP7694 Head Space Sampler (manufactured by Hewlett-Packard)
Temperature conditions: Transfer line 140℃, loop temperature 140℃
Sample amount: 0.8g/20ml vial GC: HP5890 (manufactured by Hewlett-Packard)
MS: HP5971 (manufactured by Hewlett-Packard)
Column: HP-624 (30m x inner diameter 0.25mm)
Oven temperature: initial temperature 40°C (holding time 3 minutes), heating rate 10°C/min, final temperature 140°C (holding time 30 minutes)
Measurement mode: SIM (select ion monitor) mode

(5) Thickness The thickness of the film of the present invention is preferably within the range of 12.5 to 100.0 μm, more preferably within the range of 25.0 to 50.0 μm. By being within the above range, it is possible to achieve thinning of the circuit board and reduction of transmission loss.

4. Film manufacturing method The film manufacturing method of the present invention is the above-mentioned film manufacturing method, which includes a step of preparing a coating liquid containing a resin, a filler, and a solvent, and coating the coating liquid on a support to form a coating film. and drying the coating film, and is characterized in that the surface free energy of the support is within the range of 30 to 80 mJ/m ² .

In the method for producing a film of the present invention, the surface free energy of the support is within the range of 30 to 80 mJ/m ² , so that the surface free energy of the above (Formula 1) and ( A film that satisfies formula 2) can be manufactured.
In the present invention, when the surface free energy of the support is expressed to the first decimal place, the first decimal place is rounded off for determination.

The method for producing a film of the present invention is not particularly limited as long as it includes the following steps, and any known method for producing a film using a solution casting method can be applied.
1) Process of preparing the coating liquid 2) Process of forming the coating film 3) Process of drying the coating film

1) Step of preparing a coating liquid In the step of preparing a coating liquid, a coating liquid containing a resin, a filler, and a solvent is prepared. Here, the order of addition of the resin, filler, and solvent is not particularly limited, but it is preferable to dissolve or disperse the filler in the solvent and then add the resin to prepare the coating liquid. When the film further contains a surfactant or other components, it is preferable to add them together with the filler and then add the resin to prepare the coating liquid.

By adding resin to a filler-containing liquid in which filler, etc. (filler and surfactants and other ingredients added as necessary) are dissolved or dispersed in a solvent, filler, etc. can be uniformly dissolved or dispersed in the coating liquid. Can be dispersed.

The solvent is not particularly limited as long as the resin and filler used can be dissolved or dispersed, but if the resin and filler used are dissolved or dispersed in a solvent with a relatively low boiling point (for example, 150 ° C. or lower), , it is preferable to use a low boiling point solvent. By using a low boiling point solvent, the film manufacturing process temperature (particularly the drying temperature) can be reduced, and thermal shrinkage can be reduced.
The boiling point of the solvent is more preferably 120°C or lower, even more preferably 90°C or lower, and particularly preferably 70°C or lower.

Examples of low boiling point solvents include aromatic hydrocarbons such as toluene, alcohols such as methanol, ethanol, 2-propanol, and 1-butanol, ethyl acetate, butyl acetate, propylene glycol monomethyl ether acetate, and propylene glycol monoethyl ether. Esters such as acetate, ethers such as diethyl ether, propylene glycol monomethyl ether, and ethylene glycol monoethyl ether, amides such as dimethylformamide and N-methylpyrrolidone, ketones such as acetone, methyl ethyl ketone, acetylacetone, and cyclohexanone, and methylene chloride. Examples include halogenated hydrocarbons such as.
These may be used alone or in combination of two or more.

The method for dissolving the resin in the solvent is not particularly limited, and the resin used may be directly dissolved in the solvent, or the resin may be dissolved in the solvent by polymerizing monomers in the solvent.

In addition, the method of adding fillers, etc. to the solution obtained by dissolving the resin in a solvent is not particularly limited, and the fillers, etc. may be added directly to the solution, or after preparing each aggregate of fillers, etc. , may be added to the solution.

When the filler and other components added as necessary are particles made of a polymer (polymer particles), it is preferable to prepare an aggregate of polymer particles. A resin may be added to the aggregate, or the aggregate may be added to a solution in which the resin is dissolved. Aggregates of polymer particles are made by combining polymer particles, a surfactant (surfactant here refers to a surfactant used to form an aggregate), an inorganic powder, and an aqueous medium. It can be obtained by spray drying a slurry containing

Note that the polymer particle aggregate can be prepared, for example, by the method described in JP-A-2010-138365. The aggregate of polymer particles is composed of a plurality of polymer particles whose mutual connection (fusion) is suppressed. Therefore, the aggregate of polymer particles can be easily separated into polymer particles when dispersed in a solution in which a resin is dissolved in a solvent, and has excellent handling and dispersibility.

The content of the resin in the coating liquid is preferably within the range of 5 to 60% by mass, more preferably within the range of 10 to 40% by mass, and 10 to 30% by mass, based on the total mass of the coating liquid. It is more preferable that the amount is within the range of % by mass.

When the resin content in the coating liquid is 5% by mass or more, sufficient viscosity is imparted to the coating liquid, so that the thickness can be adjusted to a desired thickness when forming a coating film. Furthermore, by setting the content to 60% by mass or less, it is possible to suppress unevenness in the thickness of the coating film when forming the coating film.

2) Step of forming a coating film In the step of forming a coating film, the above coating liquid is applied onto a support to form a coating film.
Further, the surface free energy of the support used is within the range of 30 to 80 mJ/m ² .

Normally, in the method of manufacturing a film by coating a coating solution on a support to form a coating film and then drying the coating, one side of the coating film is formed in contact with the support, and the other side is in contact with the support. is formed in contact with the atmosphere, that is, the two sides of the coating film are formed under different conditions, so the surface free energy of the two opposing sides of the film obtained by drying the coating film is compared. It is thought that there will be a large difference in terms of performance. However, by adjusting the surface free energy of the surface of the support in contact with the coating film within the range of 30 to 80 mJ/ ^m2 , the difference in surface free energy between the two opposing surfaces of the film can be made relatively small. It is thought that it is possible to do so.

The surface free energy of the support is preferably within the range of 35 to 70 mJ/m ² , more preferably within the range of 40 to 60 mJ/m ² .

The support is not particularly limited as long as it is a film having a surface free energy of at least one side within the range of 30 to 80 mJ/m ² .
Commercial products of the support film include "Therapel (registered trademark) PJ101, PJ271 and HP2" (manufactured by Toray Industries, Inc.), "Cosmoshine (registered trademark) A4160" (manufactured by Toyobo Co., Ltd., etc.).

Alternatively, a support film may be prepared in advance, and the film of the present invention may be formed on the support film.

The method for applying the coating liquid onto the support is not particularly limited, and examples thereof include roll coating, rod bar coating, air knife coating, spray coating, curtain method, and the like.

3) Step of drying the coating film In the step of drying the coating film, the coating film is dried to form a film.
The method of drying the coating film is not particularly limited, and examples thereof include hot air, infrared rays, heated rolls, microwaves, and the like.

The amount of residual solvent in the film of the present invention is preferably within the range of 200 to 3000 ppm by mass, and it is preferable to appropriately select the drying method and drying conditions so that the amount of residual solvent is within the above range. The method for measuring the amount of residual solvent is as described above.

Further, the obtained film may be further stretched.
The film may be stretched in only one direction (uniaxial stretching) or in two orthogonal directions (biaxial stretching). Preferably, biaxial stretching is performed in which the film is stretched in two directions: the width direction (TD direction) of the film and the transport direction (MD direction) perpendicular to the width direction.

As for the stretching ratio, for example, [stretching ratio in the TD direction/stretching ratio in the MD direction] is preferably within the range of 1.0 to 3.0. The stretching ratios in the TD direction and the MD direction are preferably in the range of 1.01 to 3.5 times, and more preferably in the range of 1.01 to 1.3 times, respectively. The higher the stretching ratio, the greater the residual stress of the resulting film tends to be. The stretching ratio is defined as [(stretching direction size of the film after stretching)/(stretching direction size of the film before stretching)].

The stretching temperature is preferably (Tg-65)°C or higher and (Tg+60)°C or lower, and (Tg-50)°C or higher and (Tg+50)°C or lower, where Tg is the glass transition temperature of the resin used for the film. More preferably, the temperature is (Tg-30)°C or higher and (Tg+50)°C or lower.

By setting the stretching temperature to (Tg-30)°C or higher, the film tends to have flexibility suitable for stretching, and excessive tension is less likely to be applied to the film during stretching. Furthermore, by setting the stretching temperature to (Tg+60)° C. or lower, a suitable amount of residual stress tends to remain in the film after stretching, and the generation of bubbles due to vaporization of the solvent in the film can be suppressed.

Stretching of the film-like material in the MD direction can be carried out, for example, by a method (roll method) in which a plurality of rolls are provided with a difference in peripheral speed and the difference in peripheral speed between the rolls is utilized. Stretching of the film in the TD direction can be carried out, for example, by fixing both ends of the film with clips or pins and widening the interval between the clips or pins in the traveling direction (tenter method).

5. Metal-clad laminate The metal-clad laminate of the present invention is characterized by containing the film of the present invention.
Note that the metal-clad laminate of the present invention may contain layers other than the above-described film and metal layer of the present invention. An example of a case in which an adhesive layer is provided will be shown below, but in the present invention, the adhesive layer does not necessarily have to be provided.

FIG. 3 shows a cross-sectional view of an example of the metal-clad laminate (single-sided) of the present invention. The metal-clad laminate 100 is a single-sided metal-clad laminate in which a metal layer 101 is bonded to one side of a film 103 via an adhesive layer 102, and the metal layer is provided only on one side. Note that any layer other than the metal layer, adhesive layer, and film may be included.

FIG. 4 shows a cross-sectional view of an example of the metal-clad laminate (both sides) of the present invention. The metal-clad laminate 110 is a double-sided metal-clad laminate in which the metal layers 101 or 105 are bonded to both sides of the film 103 via the

adhesive layer

102 or 104, and the metal layers are provided on both sides. be. Note that any layer other than the metal layer, adhesive layer, and film may be included.

Further, the

adhesive layers

102 and 104 and the metal layers 101 and 105 may or may not be the same, respectively, but the film of the present invention has a difference in surface free energy between two opposing surfaces (both sides). is relatively small, so even if the same adhesive layer and metal layer are used on both sides, peeling due to differences in the degree of curing shrinkage can be suppressed.

The thickness of the metal-clad laminate is not particularly limited, but is preferably within the range of 50 to 500 μm, more preferably within the range of 100 to 300 μm. By being 50 μm or more, transmission loss can be sufficiently reduced when used as a circuit board, and by being 500 μm or less, a decrease in flexibility and productivity can be suppressed when used as a circuit board. Can be done.

(metal layer)
The metal used for the metal layer is not particularly limited, and examples thereof include copper, stainless steel, iron, nickel, beryllium, aluminum, zinc, indium, silver, gold, tin, zirconium, tantalum, titanium, lead, magnesium, manganese, and These alloys and the like can be mentioned. Among these, copper or a copper alloy is particularly preferred.

The thickness of the metal layer is not particularly limited, and for example, when using a metal foil such as copper foil, it is preferably 35 μm or less, and more preferably within the range of 5 to 25 μm. From the viewpoint of production stability and handling properties, the thickness of the metal foil is preferably 5 μm or more.

When using copper foil, rolled copper foil or electrolytic copper foil may be used, or commercially available copper foil may be used. Further, the metal foil may be subjected to a surface treatment using, for example, siding, aluminum alcoholate, aluminum chelate, a silane coupling agent, etc., for the purpose of antirust treatment or improvement of adhesive strength.

Further, as the metal foil, a carrier-attached metal foil containing two or more layers of metal foil may be used. Examples of the metal foil with a carrier include a copper foil with a carrier (thickness: 10 to 35 μm) and an ultra-thin copper foil (thickness: 2 to 5 μm) laminated on the copper foil with a carrier via a release layer. A carrier-attached copper foil consisting of: By using the carrier-attached copper foil, it is possible to form a fine pattern by MSAP (Modified Semi-Additive Process). Note that the release layer is preferably a metal layer containing nickel or chromium, or a multilayer metal layer in which these metal layers are laminated.
Examples of the carrier-attached metal foil include "FUTF-5DAF-2" (manufactured by Fukuda Metal Foil and Powder Industries Co., Ltd.).

(Adhesive layer)
The adhesive component used in the adhesive layer is not particularly limited as long as it has good adhesion between the film of the present invention and metal. Trademark) 500 Series" (manufactured by Toyochem Industries Co., Ltd.).

The thickness of the adhesive layer is not particularly limited, but for example, it is preferably within the range of 10 to 50 μm, and more preferably within the range of 15 to 30 μm.

(Production method)
The method for manufacturing the metal-clad laminate of the present invention includes, for example, forming a metal layer on the film of the present invention by heat-pressing a metal foil onto the film of the present invention via the adhesive component, or by metal vapor deposition. There are several methods.

For double-sided metal-clad laminates, for example, after forming a single-sided metal-clad laminate, two single-sided metal-clad laminates are stacked so that the films of the present invention face each other and bonded under heat. After forming the film, a method may be mentioned in which a metal foil is heat-pressed onto the surface of the film of the present invention opposite to the metal layer via the adhesive component.

In addition, heat compression bonding is carried out at a temperature of 90 to 250°C, preferably 150 to 190°C, a pressure of 0.5 to 5.0 MPa, preferably 1.0 to 3.0 MPa, The time is within the range of 0.5 to 150 minutes, preferably within the range of 5 to 60 minutes. Note that the curing may be performed in multiple stages by changing the curing conditions. This heat-pressing process is also called a vacuum press process.

Further, in order to accelerate curing, post-curing may be performed for 5 to 90 minutes at a temperature of 150 to 190° C. after heat and pressure bonding. Note that the curing may be performed in multiple stages by changing the curing conditions.
This heat-press bonding process and the post-cure process are collectively called an integration process.

6. Circuit Board The circuit board of the present invention is characterized by comprising the metal clad laminate of the present invention.
Specifically, a flexible substrate can be produced by processing one or more metal layers of the metal-clad laminate described above into a pattern to form a wiring layer (conductor circuit layer).

Flexible Printed Circuits (FPC) are thin and highly flexible, so they can be bent and used for three-dimensional wiring and operational wiring within devices, making electronic devices thin, compact, and lightweight. can contribute to the development of

Examples of the structure of the flexible substrate include a single-sided structure using a single-sided metal-clad laminate, a double-sided structure using a double-sided metal-clad laminate, and a multilayer structure in which three or more metal layers are formed by combining metal-clad laminates. Each structure will be described below, but the circuit board of the present invention may include any layer other than the metal layer, adhesive layer, and film. Further, for convenience, the metal layer 201 and the adhesive layer 202 are also collectively referred to as a wiring layer 206.

FIG. 5 shows a cross-sectional view of an example of the circuit board (single-sided structure) of the present invention. The circuit board 200 can be manufactured by printing a pattern on the metal-clad laminate 100. Note that the metal layer 201, adhesive layer 202, and film 203 correspond to the metal layer 101, adhesive layer 102, and film 103 described above.

FIG. 6 shows a cross-sectional view of an example of the circuit board (double-sided structure) of the present invention. The circuit board 210 can be manufactured by printing a pattern on the metal clad laminate 110. Note that the metal layers 201 and 205, the

adhesive layers

202 and 204, and the film 203 correspond to the metal layers 101 and 105, the

adhesive layers

102 and 104, and the film 103 described above.

FIG. 7 shows a cross-sectional view of an example of the circuit board (multilayer structure) of the present invention. The circuit board 220 can be manufactured by printing a pattern on a metal-clad laminate and laminating them with the adhesive layer 207 interposed therebetween. Note that the metal layer 201, adhesive layer 202, and film 203 correspond to the metal layer 101, adhesive layer 102, and film 103 described above.

(Production method)
Methods for manufacturing the circuit board of the present invention include, for example, a method of etching metal foil to process it into a predetermined transmission circuit, an electrolytic plating method (semi-additive process method (SAP method), modified semi-additive process method) of metal foil, etc. (MSAP method), etc.) to form a predetermined transmission circuit.

In the production of circuit boards, the unnecessary photoresist layer is finally removed and the circuit board is cleaned. The difference in surface free energy between the two opposing sides of the base film is relatively small, and the wettability is the same, meaning that the same level of cleanability can be obtained on the two sides, suppressing the remaining photoresist layer. It is thought that transmission loss in the circuit board can be suppressed.

Note that the film of the present invention may be used not only as a base film but also as a coverlay film. By using a coverlay film, circuits can be protected electrically, mechanically, chemically, and thermally.

7. Electronic Device The electronic device of the present invention is characterized by comprising the circuit board of the present invention.

The circuit board of the present invention can be suitably used, for example, in electronic devices such as computers, mobile phones, digital cameras, and televisions.

However, in addition to the above-mentioned circuit board, the film of the present invention can also be used for electronic circuits including active elements such as transistors and diodes, passive devices such as resistors, capacitors, and inductors, and sensor elements for sensing pressure, temperature, light, humidity, etc. It can also be suitably used for image display elements such as light emitting elements, liquid crystal displays, electrophoretic displays, and self-luminous displays, wireless and wired communication elements, arithmetic elements, memory elements, MEMS elements, solar cells, thin film transistors, etc. These are preferably included in electronic equipment.

EXAMPLES Hereinafter, the present invention will be specifically explained with reference to Examples, but the present invention is not limited thereto. In the examples, "parts" or "%" are used, but unless otherwise specified, "parts by mass" or "% by mass" are expressed.
In addition, in the following examples, operations were performed at room temperature (25° C.) unless otherwise specified.

<Example 1>
Film 1 was produced, and films 2 to 15 were produced by changing the constituent materials.

[Preparation of film 1]
[Preparation of coating liquid for film 1]
Before preparing the film coating solution, add an appropriate amount of methyl ethyl ketone to 100 parts by mass of a 10% by mass solution of filler F1 in methanol (MeOH) (NS-08 manufactured by Nagoya Gosei Co., Ltd.), and distill off the methanol under reduced pressure. A filler dispersion containing 20% by mass of filler in methyl ethyl ketone was prepared.
A coating liquid for Film 1 was obtained by mixing the following components.
Methyl ethyl ketone (boiling point 80°C) 400.0 parts by mass Resin P1 67.0 parts by mass Filler F1 33.0 parts by mass Filler F1 was added in the form of the above dispersion, and the total amount of methyl ethyl ketone added was as above. It was adjusted by separately adding methyl ethyl ketone. After the adjustment, dispersion treatment using a Manton-Gorlin homogenizer was performed three times to obtain a filler F1-containing liquid. Thereafter, the filler F1-containing liquid was added to the dissolution pot containing methyl ethyl ketone and stirred, and then the resin P1 was added and stirred to obtain a coating liquid for film 1.

[Formation of film 1]
On the release layer of the support S1, the coating liquid for film 1 is applied using a die by a back coating method, and the coating film is dried at 120 ° C. for 30 minutes to form a film with a thickness of 50 μm, Film 1 was obtained.
The thickness of the obtained film was measured using a "Film Thickness Measurement System" F20-UV (manufactured by Filmetrics Co., Ltd.).

[Preparation of film 2]
Film 2 was obtained in the same manner as in the formation of Film 1, except that the contents of the resin and filler were changed as shown in Table II.

[Preparation of film 3]
[Preparation of coating liquid for film 3]
A coating liquid for film 3 was obtained by mixing the following components.
Toluene (boiling point 111°C) 150.0 parts by mass Resin P2 30.0 parts by mass Filler F1 70.0 parts by mass Filler F1 was added in the form of a dispersion ("NS-06": manufactured by Nagoya Gosei Co., Ltd.). The total amount of toluene added was adjusted as above by adding toluene separately. After the adjustment, dispersion treatment using a Manton-Gorlin homogenizer was performed three times to obtain a filler F1-containing liquid. Thereafter, the filler F1-containing liquid was added to a dissolution pot containing toluene and stirred, and the resin P2 was further added and stirred to obtain a coating liquid for film 3.

[Formation of film 3]
Film 3 was obtained in the same manner as film 1 was formed.

[Preparation of films 4 to 12, 14 to 15]
Films 4 to 12 and 14 to 15 were obtained in the same manner as in the formation of film 3, except that the types and contents of the constituent materials were changed as shown in Table II.

[Preparation of film 13]
[Preparation of coating liquid for film 13]
Before preparing the film coating solution, 80 parts by mass of dimethylformamide (DMF) was added to 100 parts by mass of a 20% by mass solution of filler F1 in isopropyl alcohol (IPA) (NS-05 manufactured by Nagoya Gosei Co., Ltd.), A filler dispersion containing 20% by mass of filler in dimethylformamide was prepared by distilling off isopropyl alcohol under reduced pressure.
A coating liquid for film 13 was obtained by mixing the following components.
Dimethylformamide (boiling point 153°C) 150.0 parts by mass Resin P3 67.0 parts by mass Filler F1 33.0 parts by mass Filler F1 was added in the form of the above dispersion, and the total amount of dimethylformamide added was the same as above. It was adjusted by separately adding dimethylformamide so that After the adjustment, dispersion treatment using a Manton-Gorlin homogenizer was performed three times to obtain a filler F1-containing liquid. Thereafter, the filler F1-containing liquid was added to a dissolution pot containing dimethylformamide and stirred, and the resin P3 was further added and stirred to obtain a coating liquid for film 13.

[Formation of film 13]
Film 13 was obtained in the same manner as film 1 was formed.

In Examples 1 and 2, the following resins, fillers, surfactants, and supports were used.
(resin)
P1: "KPI-MX300F" (soluble polyimide powder, manufactured by Kawamura Sangyo Co., Ltd.)
P2: "Unifiner (registered trademark) M-2040" (polyarylate, manufactured by Unitika Co., Ltd.)
P3: "Polymer A" (synthesized as described in Comparative Example 4 of Publication No. JP-A-2003-201461)

(filler)
F1: "NS series" (polytetrafluoroethylene, manufactured by Nagoya Gosei Co., Ltd.)
F2: "Unifiner (registered trademark) V-575" (polyarylate, manufactured by Unitika Co., Ltd.)

(surfactant)
D1: "Megafac (registered trademark) F-563" (fluorine additive, manufactured by DIC Corporation)
D2: "Megafac (registered trademark) F-558" (fluorine additive, manufactured by DIC Corporation)

(Support)
S1: "Therapel (registered trademark) PJ101" (manufactured by Toray Industries, Inc.)
S2: "Cosmoshine (registered trademark) A4160" (manufactured by Toyobo Co., Ltd.)
S3: "Therapel (registered trademark) PJ271" (manufactured by Toray Industries, Inc.)
S4: "Lumirror (registered trademark) ATM1" (manufactured by Toray Industries, Inc.)

As filler F3, rubber particles prepared by the following method were used.
The following components were charged into a reactor equipped with a reflux condenser having an internal volume of 60 L, and the temperature was raised to 75° C. under a nitrogen atmosphere while stirring at a rotation speed of 250 rpm, so that there was virtually no influence of oxygen.
Ion exchange water 38.20L
Sodium dioctyl sulfosuccinate 111.60g

Then, the following ingredients were added and stirred for 5 minutes.
Ammonium persulfate (APS) 0.36g

Thereafter, a monomer mixture (c1) consisting of the following components was added all at once, and after the exothermic peak was detected, the mixture was maintained for an additional 20 minutes to complete the polymerization of the innermost hard layer.
Methyl methacrylate (MMA) 1657.00g
Butyl acrylate (BA) 21.60g
Allyl methacrylate (ALMA) 1.68g

Next, the following ingredients were added and stirred for 5 minutes.
Ammonium persulfate (APS) 3.48g

Then, a monomer mixture (a1) (BA/MMA=85/15 mass ratio) consisting of the following components was continuously added over 120 minutes, and after the addition was completed, the monomer mixture (a1) was maintained for an additional 120 minutes to complete the polymerization of the soft layer. Ta.
Butyl acrylate (BA) 1961.00g
Methyl methacrylate (MMA) 346.00g
Allyl methacrylate (ALMA) 264.00g

Next, the following ingredients were added and stirred for 5 minutes.
Ammonium persulfate (APS) 1.32g

Then, a monomer mixture (b1) consisting of the following components was continuously added over a period of 20 minutes, and after the addition was completed, the mixture was maintained for an additional 20 minutes to complete the polymerization of the hard layer 1.
Methyl methacrylate (MMA) 2106.00g
Butyl acrylate (BA) 201.60g

Then, a monomer mixture (b2) consisting of the following components was continuously added over a period of 20 minutes, and after the addition was completed, the mixture was maintained for an additional 20 minutes. Then, the temperature was raised to 95°C and held for 60 minutes to complete polymerization of the hard layer 2.
Methyl methacrylate (MMA) 3148.00g
Butyl acrylate (BA) 201.60g
n-octyl mercaptan (n-OM) 10.10g

The remaining latex was poured into a 3% by mass sodium sulfate warm aqueous solution to salt out and coagulate, and then, after repeated dehydration and washing, it was dried to obtain acrylic particles (rubber particles) with a four-layer structure. .

Table I shows the physical properties of the resin, filler, and support. In addition, each physical property was measured by the above-mentioned measuring method.

[evaluation]
The following measurements and evaluations were performed on the obtained films 1 to 15.

(1) Measurement of dielectric loss tangent The dielectric loss tangent of each film was measured in accordance with JIS R1641:2007.
For each film, a test piece with a size of 100 mm x 120 mm was prepared and stored in advance for 90 hours at a temperature of 22±1° C. and a humidity of 60±5% RH environment before measurement. Thereafter, the dielectric loss tangent at a frequency of 28 GHz was measured by the cylindrical cavity method.

(2) Measurement of surface free energy Using water, diiodomethane, and hexadecane, the contact of each liquid on each film was measured using a contact angle meter "DropMaster DM501" (manufactured by Kyowa Interface Science Co., Ltd.) in an environment of 22°C and 60% RH. The angle was measured and the surface free energy was calculated using the method described above. Then, among the surface free energies of the two opposing surfaces of each film, the smaller numerical value was defined as A, and the larger numerical value was defined as B, and a value expressed as A/B was calculated.

In addition, in the TD direction of the film (width direction of the film to be manufactured), a total of 5 points: the center of the film, the edges (positions 10 cm from both ends), and 2 points midway between the center and the edges. The contact angle was measured, and the arithmetic mean value was taken as the value of the contact angle θ.

(3) Copper foil layer adhesion One side of each film (one of the two sides), an adhesive sheet (“LIOELM TSU (registered trademark) 500 series” (manufactured by Toyochem Industries Co., Ltd.)) and a 2 μm thick The copper plates were laminated with the adhesive sheet in the middle, and after thermo-compression bonding at 90°C, 0.5MPa, 0.5 minutes using a hot press, 180°C, 2.0MPa, 5 minutes, further 180°C. A laminate was obtained in which each film, the cured adhesive sheet, and the copper plate were laminated in this order under the conditions of post-curing at ℃ for 1 hour. Then, the adhesive strength was measured by peeling off the copper plate of the obtained laminate. The strength when peeling the copper foil layer from this sample was measured using a force gauge "DPRS-2TR" (manufactured by Imada Co., Ltd.) in accordance with Section 7 "Performance Test" of the JPCA Electrical Circuit Board Standards 3rd edition. , was measured under the following conditions.
Jig: 90 degree peeling jig “P90-200N-BB” (manufactured by Imada Co., Ltd.)
Tensile speed: 50mm/min

The obtained peel strength was evaluated based on the following criteria. Note that a score of B or higher was considered to be a pass.
A: Peel strength is 0.8 N/mm or more.
B: Peel strength is 0.7 N/mm or more and less than 0.8 N/mm.
C: Peel strength is less than 0.7 N/mm.

(4) Transmission loss One side of each film (one of the two sides), an adhesive sheet (“LIOELM TSU (registered trademark) 500 series” (manufactured by Toyochem Industries, Ltd.)), and a 2 μm thick copper plate , laminated so that the adhesive sheet is in the middle, heat-compressed at 90°C, 0.5 MPa, 0.5 minutes using a heat press, then 180°C, 2.0 MPa, 5 minutes, then 180°C, 1 A laminate was obtained in which each film, the cured adhesive sheet, and the copper plate were laminated in this order under post-curing conditions for a period of time.

Thereafter, a microstrip line with a wiring width of 140 μm and a length of 100 mm was formed as a circuit pattern on the surface of the copper foil layer by chemical etching so that the characteristic impedance was 50Ω, and a sample was prepared. Immediately after leaving the sample in an environment with a temperature of 23°C and a humidity of 65% RH for 24 hours, a network analyzer "8722ES" (manufactured by Agilent Technology Co., Ltd.) and a probe "ACP40-250" (manufactured by Cascade Microtech Co., Ltd.) were used. The transmission loss (dB/10mm) at 28 GHz was measured using the following.

The obtained transmission loss was evaluated based on the following criteria. Note that a score of B or higher was considered to be a pass.
A: Less than 0.5 dB/10 mm.
B: 0.5 dB/10 mm or more and less than 1.5 dB/10 mm.
C: 1.5 dB/10 mm or more.

(5) Amount of residual solvent The amount of residual solvent was measured by the method described above.

Table II and Table III show the constituent materials and evaluation results of each film.
In Table III, "A" and "B" in the "Surface Free Energy" column each mean the value of the surface free energy. "A" and "B" in the columns of "copper foil layer adhesion" and "transmission loss" respectively mean evaluation criteria.

<Example 2>
Films 101 to 119 were produced by changing the constituent materials and manufacturing conditions. In addition, regarding film 109, the film was produced by changing the order of addition of the resin and filler in the coating liquid.

[Preparation of film 101]
[Preparation of coating liquid for film 101]
A coating liquid for film 101 was obtained by mixing the following components.
Toluene (boiling point 111°C) 150.0 parts by mass Resin P2 67.0 parts by mass Filler F1 33.0 parts by mass Filler F1 was added in the form of a dispersion ("NS-06": manufactured by Nagoya Gosei Co., Ltd.). The total amount of toluene added was adjusted as above by adding toluene separately. After the adjustment, dispersion treatment using a Manton-Gorlin homogenizer was performed three times to obtain a filler F1-containing liquid. Thereafter, the filler F1-containing liquid was added to a dissolution pot containing toluene and stirred, and then the resin P1 was added and stirred to obtain a coating liquid for film 101.

[Formation of film 101]
On the release layer of the support S1, a coating solution for the film 101 is applied using a die by a back coating method, and the coating film is dried at 100 ° C. for 30 minutes to form a film with a thickness of 50 μm, Film 101 was obtained.
The thickness of the obtained film was measured using a film thickness measurement system "F20-UV" (manufactured by Filmetrics Co., Ltd.).

[Preparation of film 102]
Film 102 was obtained in the same manner as film 101 except that the drying conditions were changed as shown in Table IV.

[Preparation of film 104]
[Preparation of coating liquid for film 104]
A coating liquid for film 104 was obtained by mixing the following components.
Toluene (boiling point 111°C) 150.0 parts by mass Resin P2 66.7 parts by mass Filler F1 33.0 parts by mass Surfactant D1 0.5 parts by mass Filler F1 is a dispersion liquid ("NS-06": Nagoya Gosei Co., Ltd.), and the total amount of toluene added was adjusted by adding toluene separately so that the total amount added was as above. After the adjustment, dispersion treatment using a Manton-Gorlin homogenizer was performed three times to obtain a filler F1-containing liquid. Thereafter, the filler F1-containing solution was added to a dissolution pot containing toluene and stirred, surfactant D1 was added and stirred, and resin P2 was further added and stirred to obtain a coating liquid for film 104. .

[Formation of film 104]
On the release layer of the support S1, a coating liquid for the film 104 is applied using a die by a back coating method, and the coating film is dried at 140° C. for 30 minutes to form a film with a thickness of 50 μm, A film 104 was obtained.
The thickness of the obtained film was measured using a film thickness measurement system "F20-UV" (manufactured by Filmetrics Co., Ltd.).

[Production of

films

103, 105, 106, 113 and 114]

Films

103, 105, 106, 113, and 114 were obtained in the same manner as in the production of film 104, except that the types and contents of the constituent materials were changed as shown in Table IV.

[Preparation of films 107, 108 and 119]
Films 107, 108, and 119 were obtained in the same manner as in the preparation of film 104, except that the type of support was changed as shown in Table IV.

[Preparation of film 109]
[Preparation of coating liquid for film 109]
A coating liquid for film 109 was obtained by mixing the following components.
Toluene (boiling point 111°C) 150.0 parts by mass Resin P2 66.7 parts by mass Filler F1 33.0 parts by mass Surfactant D1 0.5 parts by mass Filler F1 is a dispersion liquid ("NS-06": Nagoya Gosei Co., Ltd.), and the amount of toluene added was adjusted separately by adding toluene so that the total amount of toluene added was as above. After the adjustment, dispersion treatment using a Manton-Gorlin homogenizer was performed three times to obtain a filler F1-containing liquid. Thereafter, resin P2 was added to a dissolution pot containing toluene and stirred, filler F1-containing liquid was added and stirred, and surfactant D1 was further added and stirred to obtain a coating liquid for film 109. .

[Formation of film 109]
On the release layer of the support S1, a coating solution for the film 109 is applied using a die by a back coating method, and the coating film is dried at 140 ° C. for 30 minutes to form a film with a thickness of 50 μm, Film 109 was obtained.
The thickness of the obtained film was measured using a film thickness measurement system "F20-UV" (manufactured by Filmetrics Co., Ltd.).

[Preparation of film 110]
Film 110 was obtained in the same manner as film 101 except that the drying conditions were changed as follows.
On the release layer of the support S1, the coating solution for the film 110 is applied using a die by a back coating method, and after drying the coating film at 140° C. for 30 minutes, the amount of residual solvent becomes 180 mass ppm. Heat vacuum drying (HVCD) was performed at a vacuum degree of 100 Pa to form a film with a thickness of 50 μm, and a film 110 was obtained.

[Preparation of films 111 to 112]
Films 111 to 112 were obtained in the same manner as in the production of film 101, except that the drying conditions were changed as shown in Table IV.

[Preparation of films 115 to 117]
Films 115 to 117 were obtained in the same manner as film 101, except that the types and contents of constituent materials, the types of supports, and drying conditions were changed as shown in Table IV.

[evaluation]
The obtained films 101 to 119 were subjected to the same measurements and evaluations as in Example 1. Table IV and Table V show the constituent materials, manufacturing conditions, and evaluation results of each film.
In Table V, "A" and "B" in the "Surface Free Energy" column each mean the value of the surface free energy. "A" and "B" in the columns of "copper foil layer adhesion" and "transmission loss" respectively mean evaluation criteria.

The Examples and Comparative Examples of the present invention show that the film of the present invention reduces transmission loss and has excellent adhesion to the copper foil layer.

From a comparison of Films 3, 9, and 13, it was found that the dielectric loss tangent of the film at a frequency of 28 GHz in an environment of 22°C and 60% RH was within the range of 0.0010 to 0.0150. It is possible to achieve both reduction and adhesion between the film and the copper foil layer.

From a comparison of Films 3, 6, 10, and 11, it was found that the filler content was within the range of 15.0 to 50.0% by mass based on the total mass of the film, thereby reducing the dielectric loss of the film and It is possible to achieve both adhesion between the film and the copper foil layer.

From a comparison of

Films

101 and 110 to 112, it is possible to achieve both reduction in dielectric loss of the film and adhesion between the film and the copper foil layer by setting the amount of residual solvent in the film within the range of 200 to 3000 mass ppm.

Comparison of

films

102, 105, 113 and 114 shows that the film further contains a surfactant, and the content of the surfactant is in the range of 0.10 to 1.00% by mass based on the total mass of the film. By being within the range, it is possible to achieve both reduction in dielectric loss of the film and adhesion between the film and the copper foil layer.

From the comparison of Films 101 to 119, it was found that the surface free energies of the two opposing sides of the film were both within the range of 25.00 to 75.00 mJ/m ² , which resulted in a reduction in the dielectric loss of the film and a reduction in the film's dielectric loss. and adhesion to the copper foil layer.

From a comparison of Films 104, 107, 108 and 119, it was found that in the film manufacturing method, the surface free energy of the support was within the range of 30.00 to 80.00 mJ/m ² , so that , a film whose surface free energy satisfies the above (Formula 1) and (Formula 2) can be manufactured.

From the comparison of Films 104 and 109, the dielectric loss of the film can be reduced by adding a resin to the filler-containing liquid in which the filler is dissolved or dispersed in a solvent in the process of preparing the coating liquid in the film manufacturing method.

By using the present invention, it is possible to provide a film, etc. that reduces dielectric loss and has excellent adhesiveness to a copper foil layer. Furthermore, by using the film, etc., it is possible to provide communication equipment and the like that are compatible with use in high frequency bands.

100 Metal clad laminate (single side)
101 Metal layer 102 Adhesive layer 103 Film 104 Adhesive layer 105 Metal layer 110 Metal-clad laminate (both sides)
200 Circuit board (single-sided structure)
201 Metal layer 202 Adhesive layer 203 Film 204 Adhesive layer 205 Metal layer 206 Wiring layer 207 Adhesive layer 210 Circuit board (double-sided structure)
220 Circuit board (multilayer structure)
γ _S surface tension of solid γ _L surface tension of liquid γ _SL solid-liquid interfacial tension θ contact angle of liquid with solid W _SL work of adhesion

Claims

A film containing a resin and a filler,
The dielectric loss tangents of the resin and the filler at a frequency of 28 GHz in an environment of 22° C. and 60% RH are both 0.0150 or less,
The content of the filler is within the range of 1.0 to 70.0% by mass based on the total mass of the film,
When the surface free energies of the two opposing surfaces of the film are respectively A [mJ/m 2 ] and B [mJ/m 2 ], the following formula is satisfied (Formula 1) A≦B
(Formula 2) 1≦B/A<1.30
A film characterized by
The film according to claim 1, wherein the dielectric loss tangent of the film at a frequency of 28 GHz in an environment of 22° C. and 60% RH is within the range of 0.0010 to 0.0150.
The film according to claim 1 or 2, wherein the content of the filler is within the range of 15.0 to 50.0% by mass based on the total mass of the film.
The film according to claim 1 or 2, wherein the amount of residual solvent in the film is within the range of 200 to 3000 ppm by mass.
The film further contains a surfactant,
The film according to claim 1 or 2, wherein the content of the surfactant is within the range of 0.10 to 1.00% by mass based on the total mass of the film.
The film according to claim 1 or 2, wherein the surface free energy of two opposing surfaces of the film are both within the range of 25.00 to 75.00 mJ/m 2 .
The film according to claim 1 or 2, wherein the resin has a glass transition temperature of 200°C or higher.
The film according to claim 1 or 2, wherein the resin and the filler are soluble or dispersible in a solvent having a boiling point of 150° C. or lower.
A film manufacturing method for manufacturing the film according to claim 1 or claim 2, comprising:
preparing a coating liquid containing the resin, the filler, and a solvent;
a step of applying the coating liquid onto a support to form a coating film, and a step of drying the coating film,
A method for producing a film, characterized in that the surface free energy of the support is within a range of 30 to 80 mJ/m 2 .
10. The method for producing a film according to claim 9, wherein in the step of preparing the coating liquid, the resin is added to a filler-containing liquid in which the filler is dissolved or dispersed in the solvent.
The method for producing a film according to claim 9 or 10, wherein the boiling point of the solvent is 150°C or less.
A metal-clad laminate comprising the film according to claim 1 or claim 2.
A circuit board comprising the metal-clad laminate according to claim 12.
An electronic device comprising the circuit board according to claim 13.