JP2023049122A - Paek resin substrate for printed wiring board, and metal-clad laminate having the paek resin substrate - Google Patents

Abstract

Kind Code: A1 A metal-clad laminate having a metal film with a smooth surface that can reduce transmission loss of electrical signals, the metal film has good adhesion, a fine-pitch circuit pattern can be formed, and high-precision and minute patterns can be formed. To provide a metal-clad laminate capable of forming a circuit, ensuring connection reliability of through-holes when formed into a multilayer board, and sufficiently satisfying all these requirements. The present invention also provides a substrate for a printed wiring board, which is used for forming the above metal-clad laminate and has a coating film formed on a substrate film. A PAEK resin substrate for a printed wiring board in which a coating film is formed on a substrate film made of a polyarylene ether ketone (PAEK) resin, the coefficient of linear thermal expansion in the thickness direction of the PAEK resin substrate (CTE) is 170 ppm/° C. or less, the CTE in the thickness direction of the base film is 60 ppm/° C. or less, and the CTE in the thickness direction of the coating film is 300 ppm/° C. or less. . [Selection figure] None

Description

TECHNICAL FIELD The present invention relates to a PAEK resin base material for printed wiring boards and a metal-clad laminate having the PAEK resin base material.

In recent years, with the increase in communication speed and capacity in communication devices such as smartphones, the circuit boards used in these communication devices are required to have lower electrical signal loss, finer pitch circuit patterns, and higher precision. Therefore, fine circuit formation is demanded.
Metal-clad laminates (e.g., copper-clad laminates (CCL)) in which a metal film is placed and laminated on the surface of a base film made of a so-called insulating resin, which is the main material of a circuit board, also have the above-mentioned properties. Performance similar to that of circuit boards is required.
Various improved metal-clad laminates (for example, copper-clad laminates (CCL)) have been proposed (see, for example, Patent Document 1).

Japanese Unexamined Patent Application Publication No. 2011-14801

In order to reduce the transmission loss of electrical signals, it is effective that the surface of the metal film, which is the transmission path of the electrical signals, is smooth. However, if the surface of the metal film is smooth, adhesion between the metal film and other layers becomes a problem.
Therefore, it is desired to provide a metal-clad laminate that can reduce the transmission loss of electrical signals and has excellent adhesion between the metal film and the substrate film.
The present inventors have confirmed that a metal-clad laminate formed by forming a coating film on a substrate film and forming a metal film on the coating film is effective in ensuring good adhesion. .

By the way, with the increasing number of layers in electronic circuit boards, there is an increasing demand for the reliability of board materials for through-hole connections and the like.

Therefore, the present invention provides a metal-clad laminate having a metal film with a smooth surface capable of reducing transmission loss of electrical signals, which has good adhesion to the metal film, enables fine-pitch circuit patterns, and achieves high precision. It is an object of the present invention to provide a metal-clad laminate which satisfies all of these requirements such that a fine circuit can be formed in a multi-layer substrate and the connection reliability of through-holes can be ensured when the substrate is formed into a multi-layer substrate.
Another object of the present invention is to provide a substrate for a printed wiring board, which is used for forming the above metal-clad laminate and has a coating film formed on a substrate film.

As a result of intensive studies to solve the above problems, the present inventors have found that a metal-clad laminate formed using a polyarylene ether ketone (PAEK) resin substrate exhibiting a specific coefficient of linear thermal expansion (CTE) have found that the above problems can be solved, and have completed the present invention.

The present invention includes the following aspects.
[1] A PAEK resin substrate for a printed wiring board in which a coating film is formed on a substrate film made of polyarylene ether ketone (PAEK) resin,
The coefficient of linear thermal expansion (CTE) in the thickness direction of the PAEK resin base material is 170 ppm/° C. or less,
The CTE in the thickness direction of the base film is 60 ppm/° C. or less,
A PAEK resin base material, wherein the CTE in the thickness direction of the coating film is 300 ppm/°C or less.
[2] The PAEK resin substrate according to [1], wherein the ratio of the thickness of the substrate film to the thickness of the coating film (thickness of substrate film/thickness of coating film) is 1.2 or less.
[3] The PAEK resin substrate according to [1] or [2], wherein the substrate film has a dielectric constant of 3.5 or less and a dielectric loss tangent of 0.004 or less.
[4] The PAEK resin substrate according to any one of [1] to [3], wherein the coating film is made of a thermosetting resin.
[5] The PAEK resin substrate according to [4], wherein the coating film contains at least one of an epoxy resin, a polyimide resin, and a bismaleimide resin.
[6] The PAEK resin substrate according to any one of [1] to [5], wherein the coating film has a dielectric constant of 3.5 or less and a dielectric loss tangent of 0.004 or less.
[7] The PAEK resin substrate according to any one of [1] to [6], wherein the substrate film contains a filler.
[8] The PAEK resin base material according to [7], wherein the filler contains at least one of mica, talc, boron nitride (BN), magnesium oxide, and silica.
[9] The PAEK resin substrate according to [7] or [8], wherein the filler has a plate-like shape.
[10] The PAEK resin substrate according to any one of [7] to [9], wherein the filler has an aspect ratio of 5 or more and 500 or less.
[11] The PAEK resin base material according to any one of [7] to [10], wherein the filler has an average particle size of 20 μm or less.
[12] The PAEK resin substrate according to any one of [1] to [11], wherein the coating film contains a filler.
[13] The PAEK resin substrate according to any one of [1] to [12], wherein the substrate film has a surface roughness (RzP) of 1 μm or more and 10 μm or less.
[14] The PAEK resin substrate according to any one of [1] to [13], wherein the coating film has a surface roughness (Rz) of 0.01 μm or more and 1 μm or less.
[15] The PAEK resin base material according to any one of [1] to [14], wherein the film thickness of the coating film is the surface roughness (RzP) of the base film×0.7 or more.
[16] The PAEK resin base material according to any one of [1] to [15], wherein the surface of the base film and/or the coating film is corona-treated, plasma-treated, or ultraviolet-treated.
[17] A metal-clad laminate obtained by laminating a metal film on the PAEK resin base material according to any one of [1] to [16],
The coating film and the metal film are laminated in this order on the base film,
A metal-clad laminate, wherein the metal film is a metal film formed by at least one of plating, sputtering, and vapor deposition.
[18] The coating film and the metal film are laminated on both sides of the base film, and the metal film, the coating film, the base film, the coating film, and the metal film are laminated in this order, [17] A metal-clad laminate as described.
[19] The metal-clad laminate according to [17] or [18], wherein the metal film has a surface roughness (Rz) of 0.5 μm or less.
[20] The metal-clad laminate according to any one of [17] to [19], wherein the thickness of the metal film is 0.05 μm or more and 10 μm or less.
[21] The metal-clad laminate according to any one of [17] to [20], wherein the metal film is a copper metal film.

According to the present invention, there is provided a metal-clad laminate having a metal film with a smooth surface that can reduce the transmission loss of electrical signals, the adhesion of the metal film is good, the circuit pattern can be fine-pitched, and the precision is high. It is possible to provide a metal-clad laminate capable of forming a fine circuit and ensuring connection reliability of through-holes in a multi-layer substrate.
Further, according to the present invention, it is possible to provide a base material for printed wiring boards, which is used for forming the above metal-clad laminate and has a coating film formed on a base film.

BRIEF DESCRIPTION OF THE DRAWINGS It is sectional drawing which shows an example of a structure of the metal-clad laminated board of this invention. FIG. 3 is a cross-sectional view showing another example of the configuration of the metal-clad laminate of the present invention;

Hereinafter, the PAEK resin base material for printed wiring boards of the present invention and the metal-clad laminate of the present invention formed using the PAEK resin base material will be described in detail. , is an example as one embodiment of the present invention, and is not limited to these contents.
The following term definitions apply throughout the specification and claims.
The film thickness of the substrate film, coating film, metal film, etc. is the average value obtained by observing the cross section of the measurement target using a microscope, measuring the thickness at five locations, and averaging the thickness.

(PAEK resin base material for printed wiring board)
A polyarylene ether ketone (PAEK) resin base material is used as a printed wiring board, and is formed by forming a coating film on a base film made of a PAEK resin.
The coefficient of linear thermal expansion (CTE) in the thickness direction of the PAEK resin substrate (CTE at 25° C. to 140° C.) is 170 ppm/° C. or less.
The CTE in the thickness direction of the base film and the coating film constituting the PAEK resin base are as follows.
The CTE in the thickness direction of the base film (CTE from 25° C. to 140° C.) is 60 ppm/° C. or less, and the CTE in the thickness direction of the coating film (CTE from 25° C. to 140° C.) is 300 ppm/° C. or less.
As used herein, the coefficient of linear thermal expansion (CTE) is also referred to as coefficient of thermal expansion, linear thermal expansion coefficient, or coefficient of thermal expansion.

The coefficient of linear thermal expansion (CTE) in the thickness direction can be obtained as follows. In accordance with JIS R 3251, a laser thermal dilatometer [product name: LIX-2L manufactured by Advance Riko Co., Ltd.] was used to raise the temperature of the measurement sample from 25°C to 300°C at a rate of 5°C/min. By increasing the temperature and measuring the temperature change in the dimensions, the slope from 25° C. to 140° C. is obtained, and the coefficient of linear expansion is calculated.

<Base film>
The base film is a PAEK resin film.
Examples of PAEK resin films include polyetheretherketone (PEEK) resin films, polyetherketone (PEK) resin films, polyetherketoneketone (PEKK) resin films, polyetherketoneetherketoneketone (PEKEKK) resin films, and the like. mentioned.
Among these, a polyetheretherketone (PEEK) film is preferable from the viewpoint of adhesiveness and electrical properties.
The base film can contain a filler. The filler will be described in detail below.

<<Filler>>
The base film can contain a filler in order to impart various functions such as strength, insulation, heat resistance, and adjustment of coefficient of linear thermal expansion (CTE) to the base. Examples of fillers include inorganic fillers and organic fillers, which can be used alone or in combination.

Examples of inorganic fillers include mica, talc, boron nitride, magnesium oxide, silica, diatomaceous earth, titanium oxide, and zinc oxide. Among them, inorganic fillers such as mica, talc, boron nitride, magnesium oxide and silica are preferred.

Examples of organic fillers include, but are not limited to, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polystyrene, polyamide, polycarbonate, polyimide, polyetherketone, polyetheretherketone, polymethylmethacrylate, liquid crystal polymer, and polytetrafluoroethylene. organic particles such as

One of the inorganic fillers and organic fillers may be selected from the above and used alone, or two or more thereof may be used in combination. When two or more types are combined, a combination of an inorganic filler and an organic filler may be used.

The shape of the filler is not particularly limited and can be appropriately selected depending on the purpose. For example, the inorganic filler may be a spherical inorganic filler or a non-spherical inorganic filler, but a non-spherical inorganic filler is preferable from the viewpoint of coefficient of thermal expansion (CTE) and film strength. The shape of the non-spherical inorganic filler may be any three-dimensional shape other than a spherical shape (substantially spherical shape), and examples thereof include plate-like, scale-like, columnar, chain-like, and fibrous shapes. Among them, from the viewpoint of coefficient of thermal expansion (CTE) and film strength, plate-like and scale-like inorganic fillers are preferable, and plate-like inorganic fillers are more preferable.
In the case of a plate-like or scale-like inorganic filler, the average particle size in the plane direction is 0.05 μm or more and 20 μm or less, preferably 0.1 μm or more and 15 μm or less, preferably 0.1 μm or more and 10 μm or less, more preferably 0.1 μm or more. It is preferably 7 μm or less, and the aspect ratio (average major axis length/average minor axis length), which means the plane direction and thickness, is 5 or more and 500 or less from the viewpoint of coefficient of thermal expansion (CTE) and film strength. , preferably 20 or more and 500 or less, desirably 40 or more and 500 or less.
If the average particle size of the filler is 20 µm or less, the surface roughness of the substrate film can be reduced, and a smooth coating film can be easily formed.
If the aspect ratio is 5 or more, it is easy to make the CTE sufficiently small.
The larger the aspect ratio, the easier it is to adjust the CTE.

[Measurement of average particle size and aspect ratio]
The average particle size and aspect ratio of the inorganic filler can be obtained by observing, for example, using a scanning electron microscope (SEM) or a transmission electron microscope (TEM) and averaging measured values at three or more locations. Regarding the average particle size and aspect ratio of the inorganic filler present in the film (layer), for example, after embedding the film in epoxy resin, ion milling of the cross section of the film is performed using an ion milling device for cross-sectional observation. A sample is prepared, a cross section of the obtained sample is observed using a scanning electron microscope (SEM) or a transmission electron microscope (TEM), and the average of measured values at three or more points can be obtained.
In addition, the average particle size of the organic filler is obtained by observing the cut surface of the base film with an electron microscope and measuring the maximum diameter of at least 10 particles. It can be obtained as the average dispersed particle diameter when dispersed in the inside.

The filler content in the base film is preferably 1% by volume or more and 30% by volume or less, more preferably 3% by volume or more and 25% by volume or less.

<<Other Ingredients>>
In the present invention, the base film may optionally contain known additives as necessary. Examples of additives include antioxidants, light stabilizers, ultraviolet absorbers, crystal nucleating agents, plasticizers, filler dispersants, and the like.

<<Characteristics of base film>>
The film thickness of the substrate film is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 10 μm to 250 μm.

The surface roughness (RzP) of the base film is not particularly limited and can be appropriately selected according to the purpose. Considering various conditions, the surface roughness (RzP) of the base film is 1 μm or more. On the other hand, in order to keep the surface roughness (Rz) of the coating film formed on the base film within the desired range, the surface roughness (RzP) of the base film is preferably 10 μm or less. That is, the surface roughness (RzP) of the base film is preferably 1 μm or more and 10 μm or less.
In the present specification, the surface roughness (Rz) (including the surface roughness (RzP) of the base film, the surface roughness (Rz) of the coating film and the surface roughness (Rz) of the metal film described later) , refers to the ten-point average roughness of the film surface. The ten-point average roughness Rz can be obtained based on JIS B 0601:2013 (ISO 4287:1997 Amd.1:2009).

[Measurement of ten-point average roughness Rz]
The ten-point average roughness Rz (μm) of the surface of the sheet is obtained by measuring the roughness curve of the test piece using a laser microscope, and from this roughness curve, JIS B 0601: 2013 (ISO 4287: 1997 Amd.1: 2009), 10 samples are measured and the average value is obtained.

The relative dielectric constant and dielectric loss tangent of the base film are not particularly limited and can be appropriately selected according to the purpose. , the dielectric loss tangent is preferably 0.004 or less.

[Relative permittivity and dielectric loss tangent]
The relative dielectric constant and dielectric loss tangent of the base film were determined by the open resonator method using a network analyzer MS46122B (manufactured by Anritsu) and an open resonator Fabry-Perot DPS-03 (manufactured by KEYCOM) at a temperature of 23°C. , and a frequency of 28 GHz.

The surface of the substrate film may be surface-treated by corona treatment, plasma treatment, or ultraviolet treatment for the reason of improving adhesion to the coating film.

<Coating film>

A coating film is formed by film-forming and hardening a resin composition.
The resin composition forming the coating film is preferably made of a thermosetting resin.
Examples of thermosetting resins include phenol resins, epoxy resins, urea resins, melamine resins, unsaturated polyester resins, polyurethane resins, polyimide resins, silicone resins, and bismaleimide resins. From the viewpoint of properties and dielectric properties, the coating film preferably contains at least one of epoxy resin, polyimide resin, and bismaleimide resin.

<<epoxy resin>>
Examples of epoxy resins include bisphenol A type epoxy resins, bisphenol F type epoxy resins, or hydrogenated versions thereof; diglycidyl phthalate, diglycidyl isophthalate, diglycidyl terephthalate, p-hydroxybenzoic acid Glycidyl ester epoxy resins such as glycidyl ester, diglycidyl tetrahydrophthalate, diglycidyl succinate, diglycidyl adipate, diglycidyl sebacate, and triglycidyl trimellitate; ethylene glycol diglycidyl ether, propylene glycol Diglycidyl ether, 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, trimethylolpropane triglycidyl ether, pentaerythritol tetraglycidyl ether, tetraphenylglycidyl ether ethane, triphenylglycidyl ether ethane, sorbitol glycidyl ether-based epoxy resins such as polyglycidyl ether of polyglycerol and polyglycidyl ether of polyglycerol; glycidylamine-based epoxy resins such as triglycidyl isocyanurate and tetraglycidyldiaminodiphenylmethane; linear aliphatics such as epoxidized polybutadiene and epoxidized soybean oil Examples include, but are not limited to, epoxy resins and the like. Novolac epoxy resins such as xylene structure-containing novolac epoxy resins, naphthol novolac epoxy resins, phenol novolak epoxy resins, o-cresol novolak epoxy resins, and bisphenol A novolak epoxy resins can also be used.

Furthermore, examples of epoxy resins include brominated bisphenol A type epoxy resins, phosphorus-containing epoxy resins, fluorine-containing epoxy resins, dicyclopentadiene skeleton-containing epoxy resins, naphthalene skeleton-containing epoxy resins, anthracene-type epoxy resins, and tertiary-butylcatechol-type epoxy resins. Resin, triphenylmethane type epoxy resin, tetraphenylethane type epoxy resin, biphenyl type epoxy resin, bisphenol S type epoxy resin, etc. can be used. These epoxy resins may be used alone or in combination of two or more.

<<Bismaleimide resin>>
Examples of bismaleimide resins include 1-methyl-2,4-bismaleimidebenzene, N,N'-m-phenylenebismaleimide, N,N'-p-phenylenebismaleimide, N,N'-m-toluene. Irenebismaleimide, N,N'-4,4-biphenylenebismaleimide, N,N'-4,4-(3,3'-dimethyl-biphenylene)bismaleimide, N,N'-4,4-(3 ,3′-dimethyldiphenylmethane)bismaleimide, N,N′-4,4-(3,3′-diethyldiphenylmethane)bismaleimide, N,N′-4,4-diphenylmethanebismaleimide, N,N′-4 ,4-diphenylpropanebismaleimide, N,N'-4,4-diphenyletherbismaleimide, N,N'-3,3-diphenylsulfonebismaleimide and the like.
Furthermore, modified bismaleimide obtained by modifying the above bismaleimide resin with a compound having a primary amine, and a polymer obtained by chain extension with an amine-modified product such as dimer acid or trimer acid and maleic anhydride or pyromellitic acid. be done.
As the bismaleimide resin, a commercially available compound can also be used. Specifically, for example, DESIGNER MOLECURES Inc. can be preferably used.

The coating film may also contain other components such as fillers and various additives.

<<Filler>>
The coating film may contain a filler for improving heat resistance, controlling fluidity, and the like. The type of filler is not particularly limited and can be appropriately selected depending on the purpose. can be used.
The average particle diameter of the filler contained in the coating film is preferably 0.01 μm to 20 μm, preferably 0.01 μm to 10 μm, more preferably 0.01 to 5 μm.

The content of the filler in the coating film is preferably 0.1% by volume or more and 25% by volume or less, more preferably 1% by volume or more and 20% by volume or less.
Since the coating film is required to have a higher surface smoothness than the base film, it is preferable that the average particle diameter of the filler used is smaller than that of the base film and the content thereof is small.

<<Other Ingredients>>
In addition to the above-described thermosetting resins and fillers, the resin composition contains tackifiers, flame retardants, curing agents, curing accelerators, coupling agents, heat antioxidants, leveling agents, antifoaming agents, pigments, and a solvent, etc., can be contained to such an extent that the functions of the resin composition are not affected.

The surface roughness (Rz) of the coating film is preferably 0.01 μm or more and 1 μm or less. The method for measuring the surface roughness (Rz) is as described in the section <<characteristics of base film>> above.
When the surface roughness (Rz) of the coating film is within the above range, a metal film having a smooth surface can be formed, and in such a metal-clad laminate capable of reducing transmission loss, the adhesion of the metal film is improved. It is possible to obtain a metal-clad laminate that is also excellent in
The film thickness of the coating film is not particularly limited and can be appropriately selected according to the purpose. is more preferable, and 5 to 20 μm is more preferable. If the thickness of the coating film is 1 μm or more, sufficient uniformity can be maintained to smooth the surface of the base film, and if it is 100 μm or less, the peel strength between the base film, the coating film and the metal film can be strengthened.
In addition, the film thickness of the coating film should be adjusted according to the surface roughness of the substrate film ( It is preferably 0.7 times or more the value of RzP) μm, more preferably 1 time or more the value of surface roughness (RzP) μm of the substrate film, and the surface roughness of the substrate film (RzP ) is more preferably 1.2 times or more the value of μm.

The ratio of the thickness of the coating film to the thickness of the base film (thickness of the coating film/thickness of the base film) is such that if the coating film is too thick, the CTE in the thickness direction tends to increase, and the through-hole Since it becomes difficult to ensure connection reliability, it is preferably 1.2 or less.
In addition, when the coating film is formed on both sides of the metal-clad laminate, the "film thickness of the coating film" in the calculation of the above "film thickness of the coating film/thickness of the base film" The value obtained by adding the film thicknesses of the coating films formed in

The dielectric constant and dielectric loss tangent of the coating film are not particularly limited, and can be appropriately selected according to the purpose. , the dielectric loss tangent is preferably 0.004 or less.
The method for measuring the dielectric constant and the dielectric loss tangent is as described in the section <<characteristics of the base film>> of the base film.

The surface of the coating film may be surface-treated by corona treatment, plasma treatment, or ultraviolet treatment for the reason of improving adhesion to the metal film.

<<Method for producing coating film>>
A coating film can be produced by forming a film from the resin composition.
The resin composition can be produced by mixing epoxy resin, polyimide resin, bismaleimide resin, or the like with other components. The mixing method is not particularly limited as long as the resin composition is uniform. Since the resin composition is preferably used in the form of a solution or dispersion, a solvent is also usually used.
Examples of solvents include alcohols such as methanol, ethanol, isopropyl alcohol, n-propyl alcohol, isobutyl alcohol, n-butyl alcohol, benzyl alcohol, ethylene glycol monomethyl ether, propylene glycol monomethyl ether, diethylene glycol monomethyl ether, and diacetone alcohol. ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, methyl amyl ketone, cyclohexanone, and isophorone; aromatic hydrocarbons such as toluene, xylene, ethylbenzene, and mesitylene; methyl acetate, ethyl acetate, ethylene glycol monomethyl ether acetate, esters such as 3-methoxybutyl acetate; aliphatic hydrocarbons such as hexane, heptane, cyclohexane and methylcyclohexane; These solvents may be used alone or in combination of two or more.
When the resin composition is a solvent-containing solution or dispersion (resin varnish), the coating on the base film and the formation of the coating film can be performed smoothly, and the desired thickness and surface roughness of the coating film can be obtained. can be easily obtained.
When the resin composition contains a solvent, the solid content concentration is preferably in the range of 3 to 80% by mass, more preferably 10 to 50% by mass, from the viewpoint of workability including formation of a coating film. When the solid content concentration is 80% by mass or less, the viscosity of the solution is moderate, and it is easy to apply uniformly.
As a more specific embodiment of the method for producing a coating film, a resin varnish containing the above resin composition and a solvent is applied to the surface of a base film to form a resin varnish layer, and then, from the resin varnish layer By removing the solvent, a B-stage coating film can be formed. Here, the coating film is in a B-stage state means that the resin composition is in an uncured state or a semi-cured state in which a part of the resin composition has begun to be cured, and a state in which the resin composition is further cured by heating or the like. say.
Here, the method for applying the resin varnish on the substrate film is not particularly limited and can be appropriately selected according to the purpose. A blade coating method, a doctor roll method, a doctor blade method, a curtain coating method, a slit coating method, a screen printing method, an inkjet method, a dispensing method, and the like can be mentioned.
The B-stage coating film can be further subjected to heating or the like to form a cured coating film.

(Metal clad laminate)
The metal-clad laminate of the present invention is obtained by laminating a metal film on the PAEK resin substrate of the present invention.
In a metal-clad laminate, a coating film and a metal film are laminated in this order on a substrate film.
The metal film is preferably a metal film formed by at least one of plating, sputtering, and vapor deposition.
Also, in the metal-clad laminate of the present invention, the coating film and the metal film may be laminated on both sides of the substrate film.
In this case, the metal-clad laminate is laminated in the order of metal film, coating film, base film, coating film, and metal film.

FIG. 1 is a cross-sectional view showing an example of the configuration of the metal-clad laminate of the present invention.
A metal-clad laminate 1 has a base film 2, a coating film 3, and a metal film 4, which are laminated in this order.
FIG. 2 shows another example of the structure of the metal-clad laminate of the present invention.
The metal-clad laminate 1 of the present invention shown in FIG. 2 is formed by laminating a metal film 4a, a coating film 3a, a substrate film 2, a coating film 3b, and a metal film 4b in this order.

<Metal film>
The metal film is formed by at least one of plating, sputtering, and vapor deposition.
When a metal film is formed on a coating film having a surface roughness (Rz) of 1 μm or less by at least one of plating, sputtering, and vapor deposition, a metal film with a smooth surface can be formed. .
In addition, the metal films formed by these forming methods enable formation of fine pitch circuit patterns and high-precision fine circuit formation.
The plating method and the sputtering method may be used separately or in combination. For example, when used together, a copper film can be formed by electrolytic copper plating after spreading a thin copper film by sputtering.

The metal constituting the metal film is not particularly limited and can be appropriately selected depending on the intended purpose. An alloy or the like containing one or more selected types may be mentioned. Among them, copper and alloys containing copper are preferable from the viewpoint of shielding properties and economy.

Methods for forming a metal film include at least one of plating, sputtering, and vapor deposition, as described above. More specifically, for example, vapor deposition films formed by physical vapor deposition (vacuum vapor deposition, sputtering, ion beam vapor deposition, electron beam vapor deposition, etc.) or chemical vapor deposition, plated films formed by plating, and the like can be mentioned. Among them, a vacuum deposition film or a sputtering film formed by a vacuum deposition method (vacuum deposition method, sputtering method, etc.) or a plated film formed by an electrolytic plating method is preferable from the viewpoint of excellent electrical conductivity in the plane direction.

The film thickness of the metal film is preferably 0.05 μm to 10 μm, more preferably 0.1 to 10 μm, from the viewpoint of ensuring sufficient electrical signal transmission characteristics and enabling a fine pitch of the circuit pattern. and preferably 0.5 to 10 μm.
The surface roughness (Rz) of the metal film on the surface not in contact with the coating film is not particularly limited and can be appropriately selected according to the purpose. The following are preferable.

<Effect of metal-clad laminate>
It is difficult to make the surface of the base film smooth because the base film contains a filler or for manufacturing reasons of the base film. , a smooth metal film can be laminated, and transmission loss can be reduced. Moreover, since the coating film is provided, even if a smooth metal film is used, the metal-clad laminate exhibits excellent adhesion between the base film and the metal film.
Further, in the present invention, by specifying the coefficient of linear thermal expansion (CTE) in the thickness direction of the PAEK resin base material constituting the metal-clad laminate to a specific value, the through-thru when the metal-clad laminate is used as a multilayer substrate. Hall connection reliability can be ensured. In other words, by specifying the CTE of the PAEK resin base material and the CTE of the base film and coating film of the PAEK resin constituting the PAEK resin base material to specific values, the connection reliability of the through-holes when making a multi-layer board is improved. A metal-clad laminate having excellent properties can be obtained.
Furthermore, by forming the metal film formed on the PAEK resin base material by at least one of plating, sputtering, and vapor deposition, it is possible to form a fine pitch circuit pattern and to form a highly accurate and fine circuit. It can be a metal-clad laminate that can be used.

<Film thickness of metal-clad laminate>
The film thickness of the metal-clad laminate is not particularly limited and can be appropriately selected depending on the intended purpose. When the film thickness of the metal-clad laminate is at least the lower limit value of the above range, the handleability is excellent and the strength can be ensured. Moreover, when the thickness is equal to or less than the upper limit of the above range, lightness, thinness, shortness and flexibility can be imparted.

<Method for producing metal-clad laminate>
A coating film is formed on the base film.
A metal film is formed on the surface of the coating film opposite to the base film.
A more specific method for forming a coating film is as described in the section <<Method for producing coating film>>, in which a resin varnish containing a resin composition and a solvent is applied to the surface of the base film. After coating to form a resin varnish layer, a coating film can be formed by removing the solvent from the resin varnish layer. The coating film can be further subjected to heating or the like to form a cured coating film.
The method for applying the resin varnish is not particularly limited and can be appropriately selected depending on the intended purpose. A doctor blade method, a curtain coating method, a slit coating method, a screen printing method, an inkjet method, a dispensing method, and the like can be mentioned.
Examples of the method for forming the metal film include a method using a vacuum film forming method (vacuum deposition, sputtering), a method using an electroplating method, and the like.
From the point that a metal film having a desired film thickness and surface shape can be formed, a method of forming a deposited film by vacuum deposition, a method of forming a plated film by electrolytic plating, a method of forming a sputtered film by sputtering, or sputtering Electroplating can be performed later to form a metal film using both sputtering and plating.

When the metal-clad laminate of the present invention is a metal-clad laminate in which a coating film and a metal film are respectively provided on both sides of a base film as shown in FIG. On the other hand, a coating film and a metal film can be formed by the method described above, and then a coating film and a metal film can be formed on the other surface of the substrate film by the same method. Alternatively, a method of forming the coating film on both sides of the base film together and then forming the metal film on both sides together on the coating film may also be used.

When the substrate film and/or coating film uses a substrate film or coating surface-treated by corona treatment, plasma treatment, or ultraviolet treatment, for example, after preparing the substrate film, the prepared substrate The surface of the material film may be surface-treated, and a coating film may be formed on the surface-treated base film by the method described above. Moreover, after forming a coating film, the surface of the coating film may be surface-treated, and then a metal film may be formed by the method described above.

EXAMPLES The present invention will be described in more detail below with reference to Examples, but the scope of the present invention is not limited to these Examples. In the following, parts and % are based on mass unless otherwise specified.

(CTE measurement method)
<CTE measurement method in the thickness direction>
In accordance with JIS R 3251, a laser thermal dilatometer [product name: LIX-2L manufactured by Advance Riko Co., Ltd.] was used to raise the temperature of the measurement sample from 25°C to 300°C at a rate of 5°C/min. By increasing the temperature and measuring the temperature change of the dimensions, the slope from 25° C. to 140° C. was determined, and the coefficient of linear expansion was calculated.

<CTE measurement method in planar direction>
It was determined by thermal mechanical analysis (TMA) in accordance with JIS K 7197:1991.

(Production example 1)
Polyether ether ketone (PEEK) resin (Victrex Granules 450G: manufactured by Victrex) and synthetic mica (Micromica MK100: manufactured by Katakura Agricorp) are mixed so that the synthetic mica is 25% by volume, and the mixture is biaxially It was extruded with an extruder to produce pellets. The synthetic mica used had an average particle size of 4.9 μm and an aspect ratio of 35.
The obtained pellets are put into a single-screw extruder with a T-die having a width of 900 mm, melt-kneaded, and continuously extruded from the T-die to form a PEEK base film having a thickness of 100 μm (film Rz: 6.4 μm). got
The transverse direction (TD)/machine direction (MD) CTE of this PEEK base film was measured to be 40 ppm/30 ppm/°C.
When the CTE in the thickness direction of this PEEK base film was measured, it was 48 ppm/°C.

(Composition example 1)
Bismaleimide resin (SLK-3000-T50: Shin-Etsu Chemical Co., Ltd.), silica filler (SO-C2: Admatechs), and peroxide (Percumyl D: manufactured by NOF Corporation) are mixed according to the formulation in Table 1 below, A coating solution was obtained.
This coating solution was applied on a release polyethylene terephthalate (PET) film to a dry thickness of 25 μm, dried and cured, and then peeled off from the release PET film.
When the CTE in the planar direction of this coating film was measured, it was 260 ppm/°C.
When the CTE in the thickness direction of this coating film was measured, it was 270 ppm/°C.

(Formulation example 2)
A bismaleimide resin (SLK-3000-T50: Shin-Etsu Chemical Co., Ltd.) and a peroxide (Percumyl D: manufactured by NOF Corporation) were mixed according to the formulation shown in Table 1 below to obtain a coating solution.
This coating solution was applied on a release polyethylene terephthalate (PET) film to a dry thickness of 25 μm, dried and cured, and then peeled off from the release PET film.
When the CTE in the planar direction of this coating film was measured, it was 980 ppm/°C.
When the CTE in the thickness direction of this coating film was measured, it was 1015 ppm/°C.

(Example 1)
Both surfaces of the PEEK base film of Production Example 1 are corona-treated, and the solution of Formulation Example 1 is applied to both surfaces of the surface-treated PEEK base film so that the film thickness when dried is 8 μm. , dried.
The coating film was cured by placing it in an oven at 200° C. for 1 hour to obtain a PEEK resin substrate having smooth coating films formed on both surfaces of the PEEK substrate film.
The Rz of the coating film surface was 0.35 μm/0.36 μm (surface roughness Rz of the coating film provided on one side of the PEEK base film/surface roughness Rz of the coating film provided on the other side). rice field.
When the CTE in the thickness direction of this PEEK resin base material was measured, it was 80 ppm/°C.

(Reliability test)
A copper film (thickness: 5 μm) was formed on the PEEK resin substrate by sputtering.
Rz of the metal layer made of copper film was (0.15) μm.
For the metal-clad laminate (copper-clad laminate) of Example 1 thus obtained, the through-hole resistance was calculated as follows, and the change rate before and after the test was measured according to the following criteria. Hall connection reliability was evaluated. The results are shown in Table 2 below.

[Calculation of through-hole resistance]
In accordance with 9.2 of JIS C 5016,
The through-hole resistance was calculated after 100 cycles of −65° C. for 30 minutes→125° C. for 30 minutes.

[Through-hole connection reliability]
◎ The rate of change before and after the test is less than 0.2% 〇 The rate of change before and after the test is 0.2% or more and less than 0.5% △ The rate of change before and after the test is 0.5% or more and less than 1% × The rate of change before and after the test is 1% or more

Table 2 shows the measurement results of the PEEK base film and the coating film used in Example 1, and the evaluation results of the reliability test of the copper-clad laminate.

(Examples 2 to 9)
Copper-clad laminates of Examples 2 to 9 were produced in the same manner as in Example 1, except that the conditions of the PEEK base film and coating film used in Example 1 were changed as shown in Table 2. bottom.

The copper clad laminates produced in Examples 2 to 9 were evaluated in the same manner as in Example 1.
Table 2 shows the measurement results of the PEEK base films and coating films used in Examples 2 to 9, and the evaluation results of the reliability test of the copper-clad laminate.

(Comparative example 1)
Both surfaces of the PEEK base film of Production Example 1 were corona-treated, and the solution of Formulation Example 2 was applied to both surfaces of the surface-treated PEEK base film so that the film thickness when dried was 8 μm. , dried.
The coating film was cured by placing it in an oven at 200° C. for 1 hour to obtain a PEEK resin substrate having smooth coating films formed on both surfaces of the PEEK substrate film.
Rz of the coating film surface was 0.30 μm/0.32 μm.
When the CTE in the thickness direction of this PEEK resin base material was measured, it was 180 ppm/°C.

Table 2 shows the measurement results of the PEEK base film and the coating film used in Comparative Example 1, and the evaluation results of the reliability test of the copper-clad laminate.

(Comparative Examples 2 to 4)
Copper-clad laminates of Comparative Examples 2 to 4 were produced in the same manner as in Example 1, except that the conditions of the PEEK base film and coating film used in Example 1 were changed as shown in Table 2. bottom.

The copper clad laminates produced in Comparative Examples 2 to 4 were evaluated in the same manner as in Example 1.
Table 2 shows the measurement results of the PEEK base films and coating films used in Comparative Examples 2 to 4, and the evaluation results of the reliability test of the copper-clad laminate.

In Table 2, "coating film thickness/substrate thickness" is the ratio of the PEEK substrate film to the film thickness in the entire PEEK resin substrate on which the coating film is formed. Therefore, when the coating film is provided on both sides of the PEEK base film, the total thickness of both coating films provided on both sides of the PEEK base film (8 × 2 = 16) is the thickness of the PEEK base film. The value obtained by dividing by the thickness (100) is shown.
In Table 2, "coating thickness/RzP" is the relationship between the coating thickness and the surface roughness of the PEEK base film. However, the value (8/6.4) obtained by dividing the coating film thickness on one side by the surface roughness (RzP) of the PEEK base film is described.

The metal-clad laminates of the present invention produced in Examples have a smooth metal film surface, so that they are metal-clad laminates capable of reducing transmission loss. Since the coating film is provided, the adhesiveness between the base film and the metal film is excellent even if a smooth metal film is used.
In the metal-clad laminate of the present invention, the coefficient of linear thermal expansion (CTE) in the thickness direction of the PAEK resin base material constituting the metal-clad laminate is specified to a specific value, so when the metal-clad laminate is used as a multilayer substrate, The through-hole connection reliability was excellent.

The metal-clad laminate of the present invention can be suitably used for manufacturing FPC-related products for electronic devices such as smart phones, mobile phones, optical modules, digital cameras, game machines, laptop computers, and medical instruments.

1 Metal-clad laminate 2 Base film 3, 3a, 3b Coating film 4, 4a, 4b Metal film

Claims (10)

A PAEK resin substrate for a printed wiring board in which a coating film is formed on a substrate film made of polyarylene ether ketone (PAEK) resin,
The coefficient of linear thermal expansion (CTE) in the thickness direction of the PAEK resin base material is 170 ppm/° C. or less,
The CTE in the thickness direction of the base film is 60 ppm/° C. or less,
A PAEK resin base material, wherein the CTE in the thickness direction of the coating film is 300 ppm/°C or less. The PAEK resin substrate according to claim 1, wherein the ratio of the thickness of the substrate film to the thickness of the coating film (thickness of substrate film/thickness of coating film) is 1.2 or less. The PAEK resin substrate according to claim 1 or 2, wherein the substrate film has a dielectric constant of 3.5 or less and a dielectric loss tangent of 0.004 or less. The PAEK resin substrate according to any one of claims 1 to 3, wherein the coating film is made of a thermosetting resin. 5. The PAEK resin substrate according to claim 4, wherein the coating film contains at least one of epoxy resin, polyimide resin, and bismaleimide resin. The PAEK resin substrate according to any one of claims 1 to 5, wherein the substrate film contains a filler. The PAEK resin substrate according to any one of claims 1 to 6, wherein the substrate film has a surface roughness (RzP) of 1 µm or more and 10 µm or less. The PAEK resin substrate according to any one of claims 1 to 7, wherein the coating film has a surface roughness (Rz) of 0.01 µm or more and 1 µm or less. A metal-clad laminate obtained by laminating a metal film on the PAEK resin base material according to any one of claims 1 to 8,
The coating film and the metal film are laminated in this order on the base film,
A metal-clad laminate, wherein the metal film is a metal film formed by at least one of plating, sputtering, and vapor deposition. The metal according to claim 9, wherein the coating film and the metal film are laminated on both sides of the base film, and the metal film, the coating film, the base film, the coating film, and the metal film are laminated in this order. tension laminate.

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