JP7115165B2 - Laminates for high-frequency circuits and flexible printed circuit boards - Google Patents

Description

TECHNICAL FIELD The present invention relates to a high-frequency circuit laminate obtained by laminating a resin layer and a metal layer, a method for producing the same, and a B-stage sheet.

Along with recent advances in performance of information terminal equipment and dramatic progress in network technology, the frequency of electrical signals handled in the field of information communication is increasing for high-speed, large-capacity transmission. In order to cope with this, the printed wiring board used has a low dielectric constant (low ε _r ) and low dielectric loss tangent (low tan δ) that can reduce transmission loss, which is a problem in transmitting and processing high-frequency signals and high-speed digital signals. ) There is an increasing demand for materials (see, for example, Patent Documents 1 to 4).

As printed wiring boards, flexible printed boards (hereinafter also referred to as "FPC") and flexible flat cables (hereinafter also referred to as "FFC") are used in electronic and electrical equipment. FPC is made by processing a copper-clad laminate (CCL) consisting of an insulator layer and a copper foil layer to form an electric circuit, and then applying a coverlay consisting of an insulation layer and an adhesive layer to protect the circuit. CL) is manufactured through the process of attaching the adhesive part to the circuit part. In addition, FFC is obtained by using a base material consisting of an insulating layer and an adhesive layer and a conductor such as a copper foil formed in a wiring shape, and arranging and bonding a plurality of conductors between the adhesive parts of the base material. It is an electrical circuit that

JP 2014-197611 A JP 2015-176921 A JP 2016-087799 A Japanese Unexamined Patent Application Publication No. 2016-032098

However, the higher the frequency of the electrical signal, the more likely it is to attenuate and the greater the transmission loss tends to be. Therefore, in next-generation high-frequency (10 GHz or higher) mounting substrates, low dielectric properties to reduce crosstalk between wires and low dielectric loss properties to suppress transmission loss of electrical signals are essential properties of insulator materials. It's becoming Moreover, in order to suppress the transmission loss of electric signals, it is also important that the mounting board has excellent smoothness. Especially in FPC and FFC, an adhesive is used to laminate the resin layer and the metal layer, and the adhesive layer formed by the adhesive is one of the factors that impair the low dielectric loss characteristics and smoothness of the mounting board. it is conceivable that.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a laminate for a high-frequency circuit, which reduces the transmission loss of electrical signals in the high-frequency circuit and enables the manufacture of a circuit board with excellent smoothness. . Another object of the present invention is to provide a method for manufacturing a laminate for high-frequency circuits, which can be manufactured by bonding at a low temperature and has excellent adhesiveness between a resin layer and a metal layer.

The present invention has been made to solve at least part of the above problems, and can be implemented as the following aspects or application examples.

[Application example 1]
One aspect of the high-frequency circuit laminate according to the present invention is
The metal layer and the resin layer are laminated in contact with each other,
The elastic modulus of the resin layer is 0.1 to 3 GPa,
At 23° C., the resin layer has a dielectric loss tangent of 0.001 to 0.01 at a frequency of 10 GHz and a dielectric constant of 2 to 3.

[Application example 2]
In the high-frequency circuit laminate of Application Example 1,
A peel strength between the resin layer and the metal layer may be 5 N/cm or more.

[Application example 3]
In the high-frequency circuit laminate of Application Example 1 or Application Example 2,
The resin layer may have a thickness of 10 to 100 μm, and the metal layer may have a thickness of 10 to 50 μm.

[Application example 4]
In the high-frequency circuit laminate according to any one of Application Examples 1 to 3,
The thickness can be 50-200 μm.

[Application example 5]
One aspect of the flexible printed circuit board according to the present invention is
A high-frequency circuit laminate according to any one of Application Examples 1 to 4 is provided.

[Application example 6]
One aspect of the method for manufacturing a high-frequency circuit laminate according to the present invention includes:
A B-stage resin layer with a surface roughness Ra of 1 to 100 nm and a metal layer with a surface roughness Ra of 10 to 300 nm are heated to 50 to 200° C. and a linear load of 1 to 19 kN/m is applied to bond them together. It is characterized by including steps.

[Application example 7]
One aspect of the B stage sheet according to the present invention is
A B-stage sheet having a B-stage resin layer and a release layer formed on at least one surface of the B-stage resin layer,
When the B stage resin layer is cured to become a C stage resin layer,
The C-stage resin layer has an elastic modulus of 0.1 to 3 GPa,
The C-stage resin layer has a dielectric loss tangent of 0.001 to 0.01 at 23° C. and a frequency of 10 GHz, and a dielectric constant of 2 to 3.

According to the high-frequency circuit laminate of the present invention, it is possible to reduce the transmission loss of electric signals in the high-frequency circuit and to manufacture a circuit board having excellent smoothness. Further, according to the method for producing a laminate for high-frequency circuits according to the present invention, it is possible to produce a laminate for high-frequency circuits by bonding at a low temperature and having excellent adhesiveness between the resin layer and the metal layer. can.

FIG. 4 is a cross-sectional view schematically showing each step in Production Example A of the laminate for high-frequency circuits. FIG. 4 is a cross-sectional view schematically showing each step in Production Example B of a laminate for high-frequency circuits.

Preferred embodiments of the present invention will be described in detail below. It should be understood that the present invention is not limited only to the embodiments described below, but includes various modifications implemented without departing from the gist of the present invention.

1. High-Frequency Circuit Laminate The terms used in this specification are defined as follows.
- "Laminate for high-frequency circuits" means a laminate for use in manufacturing high-frequency circuits driven at frequencies of 10 GHz or higher.
- "B stage resin layer" refers to a layer in which the resin is semi-cured.
- "C-stage resin layer" refers to a layer in which the resin is completely cured. In addition, in this invention, a "C stage resin layer" may be called simply a "resin layer."

The high-frequency circuit laminate according to this embodiment is formed by laminating a metal layer and a resin layer in contact with each other, and an adhesive layer such as a primer resin layer is not interposed between the metal layer and the resin layer. In general circuit laminates, an adhesive layer is interposed between the resin layer and the metal layer in order to improve the adhesion between the metal layer that has a conductive function and the resin layer that has an insulating function. The adhesive layer is formed by a method such as coating, mainly using an adhesive containing a polymer having a polar functional group. However, since such an adhesive layer has poor electrical properties, it increases the effective dielectric constant and effective dielectric loss of the resin layer that has an insulating function, making it unsuitable for high-frequency circuits. In contrast, in the high-frequency circuit laminate according to the present embodiment, the adhesion between the metal layer and the resin layer is good without using an adhesive, and the metal layer and the resin layer are laminated in contact with each other. As a result, the inventors succeeded in obtaining a laminate suitable for high-frequency circuits without deteriorating the effective electrical properties of the resin layer.

The high-frequency circuit laminate used in the present embodiment preferably has a peel strength between the resin layer and the metal layer of 5 N/cm or more, more preferably 5.3 N/cm or more, and 6 N/cm or more. is particularly preferred. Since the high-frequency circuit laminate used in the present embodiment has a peel strength within the above range, the adhesion between the metal layer and the resin layer is good without using an adhesive. The peel strength can be measured according to the method described in "IPC-TM-650 2.4.9".

The thickness of the high-frequency circuit laminate used in this embodiment is preferably 50 to 200 μm, more preferably 60 to 180 μm, and particularly preferably 70 to 150 μm. When the thickness of the high-frequency circuit laminate is within the above range, not only can a thin high-frequency circuit board be produced, but also curling is less likely to occur when wound around a core.

Hereinafter, the structure of each layer constituting the high-frequency circuit laminate according to the present embodiment and the manufacturing method thereof will be described in detail.

1.1. Resin Layer The high-frequency circuit laminate according to the present embodiment includes a resin layer. The elastic modulus of the resin layer is 0.1 to 3 GPa, preferably 0.2 to 2.5 GPa. When the elastic modulus of the resin layer is within the above range, the laminate for high-frequency circuits is excellent in flexibility, so that the circuit board can be produced under more flexible conditions. The elastic modulus of the resin layer is the tensile elastic modulus, which is defined in JIS K
7161 can be measured.

The dielectric constant of the resin layer at 23° C. and a frequency of 10 GHz is 2 to 3, preferably 2.1 to 2.8. Further, the dielectric loss tangent of the resin layer at 23° C. and a frequency of 10 GHz is 0.001 to 0.01, preferably 0.002 to 0.009. When the dielectric constant and the dielectric loss tangent are within the above ranges, a circuit board having excellent high frequency characteristics can be produced. The dielectric constant and dielectric loss tangent of the resin layer at a frequency of 10 GHz at 23° C. can be measured using a cavity resonator perturbation dielectric constant measuring device.

Also, the thickness of the resin layer is preferably 10 to 100 μm, more preferably 20 to 90 μm, and particularly preferably 25 to 80 μm.

The present invention also includes an aspect in which the resin layer is composed of a plurality of different resin layers. When the resin layer is composed of a plurality of resin layers, the elastic modulus, dielectric constant, and dielectric loss tangent of each resin single layer are not necessarily limited to the preferred ranges described above, and may be within the preferred ranges as a whole. Just do it.

The method for producing such a resin layer is not particularly limited, but it is produced by a method such as applying the resin layer composition to a substrate such as a release layer or metal foil, or extruding to produce a self-supporting film. can do.

The composition of the resin layer composition is not particularly limited as long as the resulting resin layer has a composition that satisfies the elastic modulus, the dielectric loss tangent and the dielectric constant. It is preferable to contain a curing aid and a solvent.

1.1.1. Composition for Resin Layer <Polymer>
As the polymer that can be contained in the composition for the resin layer, known materials having low dielectric constant and low dielectric loss tangent characteristics such as epoxy resin, polyimide, polyarylene, etc. can be appropriately used. A polymer or the like having a repeating unit represented by at least one of the following formulas (1-1), (1-2) and (1-3) can be preferably used.

〔式（１－１）～（１－３）中、Ｒ^１は、それぞれ独立して、ハロゲン原子、炭素数１～２０の１価の炭化水素基、炭素数１～２０の１価のハロゲン化炭化水素基、ニトロ基、シアノ基、１～３級アミノ基、又は１～３級アミノ基の塩である。ｎは、それぞれ独立して、０～２の整数である。ｎが２の場合、複数のＲ^１は、同一であっても異なっていてもよく、任意の組み合わせで結合して環構造の一部を形成していてもよい。〕

[In formulas (1-1) to (1-3), R ¹ is each independently a halogen atom, a monovalent hydrocarbon group having 1 to 20 carbon atoms, a monovalent halogen having 1 to 20 carbon atoms, a hydrocarbon group, a nitro group, a cyano group, a primary to tertiary amino group, or a salt of a primary to tertiary amino group. Each n is independently an integer of 0 to 2. When n is 2, multiple R ^1s may be the same or different, and may be combined in any combination to form a part of the ring structure. ]

R ¹ is a halogen atom, a monovalent hydrocarbon group having 1 to 6 carbon atoms, a monovalent halogenated hydrocarbon group having 1 to 6 carbon atoms, a nitro group, a cyano group, a primary to tertiary amino group, or Salts of primary to tertiary amino groups are preferred, and fluorine atom, chlorine atom, methyl group, nitro group, cyano group, t-butyl group, phenyl group and amino group are more preferred. n is preferably 0 or 1, more preferably 0.

The position of one bond of the repeating unit with respect to the other bond is not particularly limited, but the meta position is preferred from the viewpoint of improving the polymerization reactivity of the monomer that provides the repeating unit. Moreover, as the repeating unit, a structural unit represented by the above formula (1-2) having a pyrimidine skeleton is preferable.

The polymer may optionally have a repeating unit other than the repeating unit represented by at least one of the above formulas (1-1), (1-2) and (1-3), The content of repeating units represented by at least one of the above formulas (1-1), (1-2) and (1-3) in the polymer is 100% of the total of all structural units in the polymer. In terms of mol %, it is preferably 5 to 95 mol %, more preferably 10 to 60 mol %.

A method for synthesizing a polymer having a repeating unit represented by at least one of the above formulas (1-1), (1-2) and (1-3) is not particularly limited, and a known method may be used. can be done. For example, a monomer that provides a repeating unit represented by at least one of the above formulas (1-1), (1-2) and (1-3), and optionally other monomers can be synthesized by heating with an alkali metal or the like in an organic solvent.

The lower limit of the weight average molecular weight (Mw) of the polymer having repeating units represented by at least one of the above formulas (1-1), (1-2) and (1-3) is 500. is preferred, 1,000 is more preferred, 10,000 is even more preferred, and 30,000 is particularly preferred. The upper limit of the weight average molecular weight (Mw) is preferably 600,000, more preferably 400,000, even more preferably 300,000, and particularly preferably 200,000.

The lower limit of the glass transition temperature (Tg) of the polymer having repeating units represented by at least one of the above formulas (1-1), (1-2) and (1-3) is preferably 150°C. , 180° C. are more preferred. The upper limit of the glass transition temperature (Tg) is preferably 320°C, more preferably 300°C.

Preferably, the polymer further has a repeating unit represented by the following general formula (2).

（式（２）中、Ｒ^３及びＲ^４はそれぞれ独立して、ハロゲン原子、ニトロ基、シアノ基又は炭素数１～２０の１価の有機基、ｃ及びｄはそれぞれ独立して０～８の整数、ｅ、ｆ、ｙはそれぞれ独立して０～２の整数、Ｌは、単結合、－Ｏ－、－Ｓ－、－ＣＯ－、－ＳＯ－、－ＳＯ_２－又は炭素数１～２０の２価の有機基である。）

(wherein R ³ and R ⁴ are each independently a halogen atom, a nitro group, a cyano group, or a monovalent organic group having 1 to 20 carbon atoms; c and d are each independently 0 to 8; , e, f, and y are each independently an integer of 0 to 2, L is a single bond, —O—, —S—, —CO—, —SO—, —SO ₂ —, or 1 to 1 carbon atoms 20 divalent organic groups.)

Halogen atoms represented by R ³ and R ⁴ include, for example, fluorine, chlorine, bromine and iodine atoms.

Examples of monovalent hydrocarbon groups having 1 to 20 carbon atoms represented by R ³ and R ⁴ include monovalent chain hydrocarbon groups, monovalent alicyclic hydrocarbon groups, and monovalent aromatic A hydrocarbon group etc. are mentioned.

Examples of the monovalent chain hydrocarbon group include methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, i-butyl group, sec-butyl group, t-butyl group, n-
Alkyl groups such as pentyl group; alkenyl groups such as ethenyl group, propenyl group, butenyl group and pentenyl group; alkynyl groups such as ethynyl group, propynyl group, butynyl group and pentynyl group;

Examples of the monovalent alicyclic hydrocarbon group include monocyclic cycloalkyl groups such as cyclopropyl group, cyclobutyl group, cyclopentyl group and cyclohexyl group; polycyclic cycloalkyl groups such as norbornyl group and adamantyl group; monocyclic cycloalkenyl groups such as cyclopropenyl group, cyclobutenyl group, cyclopentenyl group and cyclohexenyl group; and polycyclic cycloalkenyl groups such as norbornenyl group.

Examples of the monovalent aromatic hydrocarbon group include aryl groups such as phenyl group, tolyl group, xylyl group, naphthyl group and anthryl group; aralkyl groups such as benzyl group, phenethyl group, phenylpropyl group and naphthylmethyl group; etc.

Examples of the C 1-20 monovalent halogenated hydrocarbon groups represented by R ³ and R ⁴ include the C 1-20 monovalent groups represented by R ³ and R ⁴ above. and a group in which some or all of the hydrogen atoms in the hydrocarbon group of are substituted with halogen atoms such as a fluorine atom, a chlorine atom, a bromine atom and an iodine atom.

Examples of the divalent organic group having 1 to 20 carbon atoms represented by L include a divalent chain hydrocarbon group having 1 to 20 carbon atoms and a divalent fluorinated chain carbonization group having 1 to 20 carbon atoms. Examples thereof include a hydrogen group, a divalent aromatic hydrocarbon group having 6 to 20 carbon atoms, a divalent fluorinated aromatic hydrocarbon group having 6 to 20 carbon atoms, and the like.

Examples of the divalent chain hydrocarbon group include methylene group, ethylene group, n-propylene group, isopropylene group, n-butylene group, sec-butylene group, t-butylene group, neopentylene group, 4-methyl -pentane-2,2-diyl group, nonane-1,9-diyl group and the like.

Examples of the divalent alicyclic hydrocarbon group include monocyclic cycloalkyl groups such as cyclopropyl group, cyclobutyl group, cyclopentyl group and cyclohexyl group; polycyclic cycloalkyl groups such as norbornyl group and adamantyl group; monocyclic cycloalkenyl groups such as cyclopropenyl group, cyclobutenyl group, cyclopentenyl group and cyclohexenyl group; and polycyclic cycloalkenyl groups such as norbornenyl group.

Examples of the divalent aromatic hydrocarbon group include aryl groups such as phenyl group, tolyl group, xylyl group, naphthyl group and anthryl group; aralkyl groups such as benzyl group, phenethyl group, phenylpropyl group and naphthylmethyl group; etc.

Examples of these polymers include the polymers described in JP-A-2015-209511, WO 2016/143447, JP-A-2017-197725, JP-A-2018-024827, and the like.

The content of the polymer in the resin layer composition is preferably 10 parts by mass or more and 90 parts by mass or less with respect to a total of 100 parts by mass of the curable compound and the polymer, which will be described later.

<Curable compound>
The curable compound is a compound that is cured by irradiation with heat or light (e.g., visible light, ultraviolet rays, near-infrared rays, far-infrared rays, electron beams, etc.), and may require a curing aid, which will be described later. . Examples of such curable compounds include epoxy compounds, cyanate ester compounds, vinyl compounds, silicone compounds, oxazine compounds, maleimide compounds, allyl compounds, acrylic compounds, methacrylic compounds, and urethane compounds. These may be used individually by 1 type, and 2 or more types may be used together. Among these, at least one selected from epoxy compounds, cyanate ester compounds, vinyl compounds, silicone compounds, oxazine compounds, maleimide compounds, and allyl compounds from the viewpoint of compatibility with the polymer and properties such as heat resistance. and more preferably at least one of an epoxy compound, a cyanate ester compound, a vinyl compound, an allyl compound, and a silicone compound.

The content of the curable compound in the composition for the resin layer is preferably 10 parts by mass or more and 90 parts by mass or less, and is preferably 20 parts by mass or more and 80 parts by mass or less with respect to 100 parts by mass of the composition for the resin layer. It is more preferable to have

<Curing aid>
Examples of curing aids include polymerization initiators such as photoreaction initiators (photoradical generators, photoacid generators, photobase generators). Specific examples of curing aids include onium salt compounds, sulfone compounds, sulfonic acid ester compounds, sulfonimide compounds, disulfonyldiazomethane compounds, disulfonylmethane compounds, oximesulfonate compounds, hydrazinesulfonate compounds, triazine compounds, nitrobenzyl compounds, Examples include benzylimidazole compounds, organic halides, metal octylate, disulfones, and the like. These curing aids may be used singly or in combination of two or more regardless of the type.

The content of the curing aid in the resin layer composition is preferably 5 parts by mass or more and 20 parts by mass or less, more preferably 5 parts by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the resin layer composition. It is more preferable to have

<Solvent>
The resin layer composition may contain a solvent, if necessary. Examples of solvents include amides such as N,N-dimethylacetamide, N,N-dimethylformamide, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, etc. Ester solvents such as γ-butyrolactone and butyl acetate; Ketone solvents such as cyclopentanone, cyclohexanone, methyl ethyl ketone and benzophenone; Ether solvents such as 1,2-methoxyethane and diphenyl ether; 1-methoxy-2- Polyfunctional solvents such as propanol and propylene glycol methyl ether acetate; Examples thereof include dialkoxybenzene (the number of carbon atoms in the alkoxy group; 1 to 4) and trialkoxybenzene (the number of carbon atoms in the alkoxy group; 1 to 4). These solvents may be used singly or in combination of two or more.

When the resin layer composition contains a solvent, it is preferably 2000 parts by mass or less, more preferably 200 parts by mass or less, relative to 100 parts by mass of the resin layer composition excluding the solvent.

<Other ingredients>
The resin layer composition may contain other components as necessary. Other components include, for example, antioxidants, reinforcing agents, lubricants, flame retardants, antibacterial agents, colorants, release agents, foaming agents, and polymers other than the above polymers.

<Method for Preparing Resin Layer Composition>
The method for preparing the resin layer composition is not particularly limited, but for example, a polymer, a curable compound, and optionally other additives (e.g., other components such as a curing aid, a solvent, and an antioxidant). can be prepared by uniformly mixing Moreover, the form of the composition can be liquid, paste, or the like.

1.2. Metal Layer The high-frequency circuit laminate according to the present embodiment includes a metal layer. As the metal layer, it is preferable to use a metal foil or a sputtered film. A copper foil is preferable as the metal foil. There are electrolytic foil and rolled foil as types of copper foil, and either of them may be used.

The surface roughness Ra of the metal layer is preferably 10 to 300 nm, more preferably 30 to 200 nm, particularly preferably 30 to 100 nm. When the surface roughness Ra of the metal layer is within the above range, the adhesion between the resin layer and the metal layer can be further improved when the laminate for high frequency circuits is produced. Furthermore, the in-plane thickness of the high-frequency circuit laminate can be made more uniform, and peeling of the resin layer and the metal layer can be suppressed when the high-frequency circuit laminate is wound into a roll. can. The surface roughness Ra of the metal layer means "arithmetic mean roughness" measured according to JIS B0601-2001.

The thickness of the metal layer is preferably 3 to 50 μm, more preferably 5 to 40 μm, particularly preferably 7 to 35 μm.

When a metal foil is used as the metal layer, if the surface roughness Ra of the metal foil is within the above range, the thinned metal foil may be used as it is. is controlled within the above range. Methods for controlling the surface roughness of the metal foil include, but are not limited to, etching treatment (acid treatment, etc.), laser treatment, electrolytic plating, electroless plating, sputtering treatment, sandblasting, and the like. not something.

1.3. Method for Producing High-Frequency Circuit Laminate The method for producing the high-frequency circuit laminate according to the present embodiment is not particularly limited as long as the resin layer and the metal layer can be laminated in contact with each other. “The resin layer and the metal layer are in contact with each other” is not limited to the case where one surface of the resin layer is in contact with the entire surface of the metal layer, and at least a portion of one surface of the resin layer is in contact with the metal layer. Including cases.

A preferable manufacturing example of the high-frequency circuit laminate according to the present embodiment will be described below.

<Production example A>
1(A) to 1(D) are diagrams schematically showing cross sections in each step of Production Example A. FIG. Production Example A will be described with reference to FIGS. 1(A) to 1(D).

(Step A1)
As shown in FIG. 1A, a resin layer composition is applied onto the release layer 10 to form a B-stage resin layer 12, and a "B-stage resin layer/release layer laminate"("B-stage sheet ”) is produced. A known film such as a PET film can be used as the release layer 10 . The PET film is not particularly limited, but for example, PanaProtect MK38S manufactured by Panac Co., Ltd. can be used. As for the coating method of the resin layer composition, a known coating method can be used, but it is preferable to adjust the film thickness using a bar coater, for example.

After coating the release layer 10 with the resin layer composition, it is preferable to form a semi-cured B-stage resin layer 12 using a known heating means such as an oven. The heating temperature is preferably 50 to 150°C, more preferably 70 to 130°C. When heating, for example, the heating may be performed in two steps such as 50 to 100°C and 100 to 150°C. Also, the total heating time is preferably less than 30 minutes, more preferably less than 20 minutes. By heating under conditions of temperature and time within the above ranges, a B-stage resin layer 12 having a highly uniform film thickness can be produced, and deterioration of the peeling layer 10 can be suppressed, so that the manufacturing process can be performed satisfactorily. The release layer 10 can be peeled off.

The surface roughness Ra of the B-stage resin layer 12 exposed on the surface is preferably 1 to 100 nm, more preferably 10 to 50 nm. When the surface roughness Ra of the B-stage resin layer 12 is within the above range, the adhesion between the resin layer and the metal layer or between the resin layers can be further improved when manufacturing a laminate for high frequency circuits. The surface roughness Ra of the B-stage resin layer in the present invention means "arithmetic mean roughness" measured according to JIS B0601-2001.

The elastic modulus of the B-stage resin layer 12 preferably has a maximum elastic modulus (MPa) of 1 MPa or higher, more preferably 3 MPa or higher, at 50° C. or higher and lower than 80° C. under the measurement condition of 1 Hz. Also, the minimum value of the elastic modulus (MPa) within the temperature range of 80° C. to 200° C. is preferably 20 MPa or less, more preferably 15 MPa or less. When the elastic modulus of the B-stage resin layer is within each temperature range, when the laminated body for high-frequency circuits is produced by hot pressing, unevenness between the wiring portion and the non-wiring portion can be suppressed, and transmission loss can be suppressed. be able to.

(Step A2)
As shown in FIG. 1B, the exposed resin layer surface 13 and the metal layer 14 of the "B stage resin layer/release layer laminate" prepared in step A1 are bonded together to form a "metal layer/B stage resin layer/ Release layer laminate” is prepared. The surface roughness Ra of the metal layer 14 bonded to the resin layer surface 13 is preferably 10 to 300 nm, more preferably 30 to 200 nm, and particularly preferably 30 to 100 nm.

When laminating together, the resin layer surface 13 and the metal layer 14 of the "B-stage resin layer/release layer laminate" are overlapped, and then a heated roll (also referred to as a "heat roll" in this specification) is used. It is preferable to carry out thermocompression bonding using, for example. The line load during thermocompression bonding is preferably 1 to 19 kN/m, more preferably 5 to 18 kN/m. The temperature for thermocompression bonding is preferably 50 to 200.degree. C., more preferably 50 to 150.degree. C., and particularly preferably 70 to 130.degree.

Further, in step A2, the "metal layer/B stage resin layer/release layer laminate" immediately after bonding is subsequently annealed by bringing it into contact with heated rolls or passing it through a heating furnace. may Such annealing treatment may be performed at a temperature equal to or higher than the melting point of the resin, preferably 100 to 250.degree. C., more preferably 110 to 230.degree. The heating time is not particularly limited, but is preferably 5 to 600 seconds, more preferably 10 to 300 seconds. By using a hot roll to perform an annealing treatment in a short period of time, for example, about 5 to 600 seconds, a B-stage resin layer with high uniformity in film thickness can be produced, and deterioration of the release layer can be suppressed. , the release layer can be removed satisfactorily in the manufacturing process. It should be noted that the above-mentioned "continuously processing the 'metal layer/B stage resin layer/release layer laminate' immediately after bonding" means that the laminated body that has been bonded in the production line for bonding the laminate. It is a step of in-line processing subsequent to the bonding process without removing from the production line.

(Step A3)
As shown in FIG. 1(C), the release layer 10 is peeled off from the "metal layer/B stage resin layer/release layer laminate" produced in step A2, and the exposed resin layer surface 11 and the metal foil 16 are exposed as necessary. and pasted together. When peeling off the peeling layer 10 from the "metal layer/B stage resin layer/peeling layer laminate" and bonding the exposed B stage resin layer surface 11 and the metal layer 16 together, the exposed resin layer surface 11 and the metal layer 16 are superimposed on each other and further heat-pressed using a hot roll or the like. The thermocompression bonding is preferably performed under the same conditions as in step A2.

The surface roughness Ra of the resin layer surface 11 exposed by peeling the release layer 10 from the "metal layer/B stage resin layer/release layer laminate" is preferably 1 to 100 nm, and preferably 10 to 50 nm. is more preferred. When the surface roughness Ra of the B-stage resin layer is within the above range, the adhesion between the resin layer and the metal layer or between the resin layers can be further improved when producing a laminate for high frequency circuits.

(Step A4)
As shown in FIG. 1(D), the high-frequency circuit laminate 100 is obtained by curing the B-stage resin layer 12 to form the C-stage resin layer 18 . In order to cure the B-stage resin layer 12, it is preferable to heat the laminate obtained in step A3 to 50 to 200°C using a known heating means such as an oven, and it is preferable to heat to 100 to 200°C. more preferred. When heating, for example, the heating may be performed in two steps such as 50 to 100°C and 100 to 200°C. Also, the heating time is preferably less than 5 hours, more preferably less than 3 hours. By heating under the temperature and time conditions within the above ranges, a C-stage resin layer having high film thickness uniformity can be produced by curing the B-stage resin layer.

<Manufacturing example B>
2A to 2C are diagrams schematically showing cross sections in each step of Production Example B. FIG. Manufacturing Example B will be described with reference to FIGS. 2(A) to 2(C).

(Step B1)
As shown in FIG. 2A, a resin layer composition is applied to a metal layer 20 to form a B-stage resin layer 22 to produce a "metal layer/B-stage resin layer laminate". As for the coating method of the resin layer composition, a known coating method can be used, but it is preferable to adjust the film thickness using a bar coater, for example.

After the resin layer composition is applied to the metal layer 20 in this way, it is preferable to form the semi-cured B-stage resin layer 22 using a known heating means such as an oven. The heating temperature is preferably 50 to 150°C, more preferably 70 to 130°C. When heating, for example, the heating may be performed in two steps such as 50 to 100°C and 100 to 150°C. Also, the total heating time is preferably less than 30 minutes, more preferably less than 20 minutes. A B-stage resin layer 22 with high film thickness uniformity can be produced by heating under conditions of temperature and time within the above ranges.

(Step B2)
As shown in FIG. 2(B), a metal layer 24 is attached to the exposed resin layer surface 23 of the "metal layer/B stage resin layer laminate" produced in step B1 to form a "metal layer/B stage resin layer/ A "metal layer laminate" is produced. When the metal layer 24 is attached to the exposed resin layer surface 23, it is preferable that the exposed resin layer surface 23 and the metal layer 24 are superimposed and then heat-pressed using a hot roll or the like. Moreover, the conditions similar to said process A2 are preferable for thermocompression-bonding.

Further, in step B2, the "metal layer/B-stage resin layer/metal layer" immediately after bonding is subsequently subjected to annealing treatment by contacting with a heated roll or passing through a heating furnace. good. The annealing treatment is preferably performed under the same conditions as in step A2 above.

The surface roughness Ra of the exposed resin layer surface 23 is preferably 1 to 100 nm, more preferably 10 to 50 nm. When the surface roughness Ra of the B-stage resin layer is within the above range, it is possible to further improve the adhesion between the resin layer and the metal layer when producing a laminate for high frequency circuits. The surface roughness Ra of the metal layer 24 bonded to the resin layer surface 23 is preferably 10 to 300 nm, more preferably 30 to 200 nm, and particularly preferably 30 to 100 nm.

(Step B3)
As shown in FIG. 3C, the high-frequency circuit laminate 200 is obtained by curing the B-stage resin layer 22 to form the C-stage resin layer 26 . In step B3, the "metal layer/B stage resin layer/metal layer laminate" prepared in step B2 is preferably heated to 50 to 200°C using a known heating means such as an oven, and heated to 100 to 200°C. is more preferable. When heating, for example, the heating may be performed in two steps such as 50 to 100°C and 100 to 200°C. Also, the heating time is preferably less than 5 hours, more preferably less than 3 hours. By heating under the temperature and time conditions within the above ranges, the C-stage resin layer 26 having high film thickness uniformity can be produced by curing the B-stage resin layer 22 .

2. Circuit board (flexible printed circuit board)
A circuit board such as an FPC can be manufactured using the above-described high-frequency circuit laminate of the present invention. Such a circuit board can reduce transmission loss even when driven at a high frequency by using the high-frequency circuit laminate of the present invention as at least a part of the laminate structure. Such a circuit board may include the high-frequency circuit laminate of the present invention as part of the laminate structure, and can be produced by a known method. It can be manufactured by applying the manufacturing process described in JP-A-231770 or the like.

Manufacture a circuit board by laminating the high-frequency circuit laminate of the present invention, patterning the metal layer of the high-frequency circuit laminate of the present invention by etching, drilling holes, cutting to a required size, etc. can do.

Since such a circuit board does not have an adhesive layer interposed therebetween, the resin layer covering the metal wiring layer, which is a convex portion, does not form a large step, and the surface of the resin layer becomes smooth. Therefore, even if the circuits are stacked, high positioning accuracy can be satisfied, and circuits with more layers can be integrated.

Such a circuit board may be, for example,
- Step (a): a step of laminating a resin film on a circuit substrate to form a resin layer;
- Step (b): a step of flattening the resin layer by heating and pressurizing it;
- Step (c): a step of further forming a circuit layer on the resin layer;
etc. can be manufactured.

The method of laminating the resin film on the circuit board in the step (a) is not particularly limited, but examples thereof include a method of laminating using a multistage press, a vacuum press, a normal pressure laminator, and a laminator that heats and presses under vacuum. A method using a laminator that heats and presses under vacuum is preferred. As a result, even if the circuit substrate has fine wiring circuits on its surface, the gaps between the circuits can be filled with resin without voids. Although the lamination conditions are not particularly limited, it is preferable to laminate at a compression temperature of 70 to 130° C. and a compression pressure of 1 to 11 kgf/cm ² under reduced pressure or vacuum. Lamination may be batchwise or continuous on rolls.

The circuit substrate is not particularly limited, and glass epoxy substrates, metal substrates, polyester substrates, polyimide substrates, BT resin substrates, thermosetting polyphenylene ether substrates, fluorine resin substrates, etc. can be used. The surface of the circuit board on which the resin film is laminated may be roughened in advance. Moreover, the number of circuit layers of the circuit board is not limited. For example, when manufacturing a printed wiring board for millimeter wave radar, it is possible to freely select from 2 to 20 layers according to the design.

In step (b), the resin film and circuit board laminated in step (a) are heated and pressurized to flatten. Although the conditions are not particularly limited, a temperature of 100°C to 250°C, a pressure of 0.2 to 10 MPa, and a time of 30 to 120 minutes are preferable, and 150°C to 220°C are more preferable.

In step (c), a circuit layer is further formed on the resin layer produced by heating and pressurizing the resin film and circuit substrate. The method of forming the circuit layer formed on the resin layer in this manner is not particularly limited, and may be formed, for example, by an etching method such as a subtractive method, a semi-additive method, or the like.

In the subtractive method, an etching resist layer having a shape corresponding to the desired pattern shape is formed on the metal layer, and the metal layer where the resist has been removed is dissolved and removed with a chemical solution by subsequent development processing. is a method of forming a desired circuit.

In the semi-additive method, a metal film is formed on the surface of a resin layer by electroless plating, a plating resist layer having a shape corresponding to a desired pattern is formed on the metal film, and then a metal layer is formed by electrolytic plating. After that, the unnecessary electroless plating layer is removed with a chemical solution or the like to form a desired circuit layer.

Moreover, holes such as via holes may be formed in the resin layer as necessary. A hole forming method is not limited, but NC drill, carbon dioxide laser, UV laser, YAG laser, plasma, etc. can be applied.

3. Examples Hereinafter, the present invention will be specifically described based on examples, but the present invention is not limited to these examples. "Parts" and "%" in Examples and Comparative Examples are based on mass unless otherwise specified.

3.1. Synthesis of Polymer <Synthesis Example 1>
1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane (BisTMC) (18.6 g, 60.0 mmol), 4,6- Dichloropyrimidine (Pym) (8.9 g, 60.0 mmol) and potassium carbonate (11.1 g, 81.0 mmol) were weighed, N-methyl-2-pyrrolidone (64 g) was added, and the temperature was maintained at 130°C under a nitrogen atmosphere. was reacted for 6 hours. After completion of the reaction, N-methyl-2-pyrrolidone (368 g) was added, the salt was removed by filtration, and this solution was poured into methanol (9.1 kg). The precipitated solid was filtered off, washed with a small amount of methanol, filtered again and collected, dried under reduced pressure at 120 ° C. for 12 hours using a vacuum dryer, and the structure represented by the following formula (P-1) A polymer P-1 having units was obtained (yield: 20.5 g, yield: 90%, weight average molecular weight (Mw): 32,000, glass transition temperature (Tg): 206°C).

The glass transition temperature (Tg) is measured using a dynamic viscoelasticity measuring device (manufactured by Seiko Instruments Inc., "DMS7100") at a frequency of 1 Hz and a heating rate of 10 ° C./min. temperature. The loss tangent was obtained by dividing the storage modulus by the loss modulus.

Further, the weight average molecular weight (Mw) was measured using a GPC apparatus ("HLC-8320 type" manufactured by Tosoh Corporation) under the following conditions.
Column: Tosoh's "TSKgel α-M" and Tosoh's "TSKgel guard column α" Developing solvent: N-methyl-2-pyrrolidone Column temperature: 40°C
Flow rate: 1.0 mL/min Sample concentration: 0.75% by mass
Sample injection volume: 50 μL
Detector: Differential refractometer Standard substance: Monodisperse polystyrene

<Synthesis Example 2>
1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane (BisTMC) (10.7 g, 34.5 mmol), 3,6- Dichloropyridazine (Pyd) (5.1 g, 34.2 mmol) and potassium carbonate (6.5 g, 47.0 mmol) were weighed, N-methyl-2-pyrrolidone (36 g) was added, and the temperature was maintained at 145°C under a nitrogen atmosphere. was reacted for 9 hours. After completion of the reaction, N-methyl-2-pyrrolidone (150 g) was added for dilution, and after removing salts by filtration, this solution was poured into methanol (3 kg). The precipitated solid was filtered, washed with a small amount of methanol, filtered again and collected, dried under the same conditions as in Synthesis Example 1, and polymer P having a structural unit represented by the following formula (P-2). -2 was obtained (yield 7.6 g, yield 48%, weight average molecular weight (Mw); 30,000, glass transition temperature (Tg); 232°C). The weight average molecular weight and glass transition temperature were measured in the same manner as in Synthesis Example 1.

<Synthesis Example 3>
1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane (BisTMC) (18.6 g, 60.0 mmol), 4,6- Dichloro-2-phenylpyrimidine (PhPym) (13.7 g, 61.1 mmol) and potassium carbonate (11.4 g, 82.5 mmol) were weighed, N-methyl-2-pyrrolidone (75 g) was added, and a nitrogen atmosphere was added. The mixture was reacted at 130° C. for 6 hours. After completion of the reaction, N-methyl-2-pyrrolidone (368 g) was added for dilution, and after removing salts by filtration, this solution was poured into methanol (9.1 kg). The precipitated solid was filtered off, washed with a small amount of methanol, filtered again and collected, dried under the same conditions as in Synthesis Example 1, and polymer P having a structural unit represented by the following formula (P-3): -3 was obtained (yield 20.5 g, yield 90%, weight average molecular weight (Mw); 187,000, glass transition temperature (Tg); 223°C). The weight average molecular weight and glass transition temperature were measured in the same manner as in Synthesis Example 1.

<Synthesis Example 4>
1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane (BisTMC) (12.4 g, 40.0 mmol), 2,2- bis(4-hydroxyphenyl)-propane (BisA) (2.3 g, 10.0 mmol), 1,1-bis(4-hydroxyphenyl)-nonane (BisP-DED) (3.3 g, 10.0 mmol), 4,6-dichloro-2-phenylpyrimidine (PhPym) (13.7 g, 61.1 mmol) and potassium carbonate (11.4 g, 82.5 mmol) were weighed in and N-methyl-2-pyrrolidone (75 g) was added. In addition, they were reacted at 130° C. for 6 hours under a nitrogen atmosphere. After completion of the reaction, N-methyl-2-pyrrolidone (368 g) was added for dilution, and after removing salts by filtration, this solution was poured into methanol (9.1 kg). The precipitated solid was filtered, washed with a small amount of methanol, filtered again and collected, dried under the same conditions as in Synthesis Example 1, and the polymer P having a structural unit represented by the following formula (P-4): -4 was obtained (yield 23.5 g, yield 87%, weight average molecular weight (Mw); 165,000, glass transition temperature (Tg); 196°C). The weight average molecular weight and glass transition temperature were measured in the same manner as in Synthesis Example 1.

<Synthesis Example 5>
1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane (BisTMC) (12.4 g, 40.0 g) was placed in a four-necked separable flask equipped with a stirrer.
mmol), 4,4′-(1,3-dimethylbutylidene)bisphenol (BisP-MIBK) (2.7 g, 10.0 mmol), 1,1-bis(4-hydroxyphenyl)-nonane (BisP-DED ) (3.3 g, 10.0 mmol), 4,6-dichloro-2-phenylpyrimidine (PhPym) (13.7 g, 61.1 mmol), and potassium carbonate (11.4 g, 82.5 mmol), N-methyl-2-pyrrolidone (75 g) was added and reacted at 130° C. for 6 hours under nitrogen atmosphere. After completion of the reaction, N-methyl-2-pyrrolidone (368 g) was added for dilution, and after removing salts by filtration, this solution was poured into methanol (9.1 kg). The precipitated solid was filtered, washed with a small amount of methanol, filtered again and collected, dried under the same conditions as in Synthesis Example 1, and polymer P having a structural unit represented by the following formula (P-5). -5 was obtained (yield 23.8 g, yield 88%, weight average molecular weight (Mw); 157,000, glass transition temperature (Tg); 190°C). The weight average molecular weight and glass transition temperature were measured in the same manner as in Synthesis Example 1.

3.2. Example 1
3.2.1. Preparation of B-stage resin layer / release layer laminate 50 parts of polymer P-1, 50 parts of 2,2'-bis (4-cyanatophenyl) propane (manufactured by Tokyo Chemical Industry Co., Ltd.) as a curable compound, and cured 5 parts of 1-benzyl-2-methylimidazole (manufactured by Mitsubishi Chemical Corporation, product name “BMI 12”) as an auxiliary agent and 160 parts of cyclopentanone were mixed to prepare a resin layer composition.

As a release layer, the resin layer composition prepared above so that the film thickness after curing is 25 μm on a 100 μm thick PET film (manufactured by Teijin Film Solution Co., Ltd., Teijin Tetron Film G2) using a bar coater. , heated at 70 ° C. for 10 minutes using an oven, and then heated at 130 ° C. for 10 minutes to form a “B stage resin layer / release layer laminate” in which the B stage resin layer is laminated on the PET film. ” was obtained.

<Surface roughness Ra>
The surface of the resin layer of the "B stage resin layer / peeling layer laminate" obtained above was measured using a white interference microscope (New View 5032 manufactured by ZYGO), and 10 μm in accordance with JIS B0601-2001. The "arithmetic mean roughness" calculated for the range of ×10 μm was defined as the surface roughness Ra. Table 1 shows the results.

<Measurement of elastic modulus of resin layer at 50°C to 200°C>
Peel off the release layer (PET film) from the "B stage resin layer / release layer laminate" obtained above, cut out a test piece (width 3 mm × length 2 cm), DMS tester (manufactured by Seiko Instruments Inc.) At 1 Hz, under the measurement conditions of 10 ° C./min, the maximum value of the elastic modulus (MPa) in the temperature range of 50 ° C. or higher and lower than 80 ° C. and the elastic modulus (MPa) in the temperature range of 80 ° C. or higher and 200 ° C. or lower was measured. Table 1 shows the results.

3.2.2. Preparation of metal layer/B stage resin layer/release layer laminate On the exposed resin layer of the "B stage resin layer/release layer laminate" obtained above, a thickness of 18
μm copper foil (manufactured by Mitsui Kinzoku Co., Ltd., model number “TQ-M4-VSP”, surface roughness 110 nm) is superimposed and further pressed with a hot roll at 150 ° C. under the condition of a line load of 10 kN / m, copper foil / B A “metal layer/B stage resin layer/release layer laminate” having a laminated structure of stage resin layer/PET film was produced. The surface roughness Ra of the copper foil was measured using a white interference microscope (New View 5032 manufactured by ZYGO), and was calculated for a range of 10 μm × 10 μm according to JIS B0601-2001. ” was taken as the surface roughness Ra. Table 1 shows the results.

<Surface roughness Ra after separation of release layer>
The release layer (PET film) was peeled off from the "metal layer/B stage resin layer/release layer laminate" obtained above, and the surface of the exposed resin layer was observed with a white interference microscope (New View 5032 manufactured by ZYGO). and the "arithmetic mean roughness" calculated for a range of 10 μm×10 μm in accordance with JIS B0601-2001 was taken as the surface roughness Ra. Table 1 shows the results.

3.2.3. Preparation and evaluation of high-frequency circuit laminate The release layer (PET film) was peeled off from the "metal layer / B stage resin layer / release layer laminate" obtained above, and the exposed resin layer surface and a copper foil with a thickness of 18 µm (manufactured by Mitsui Kinzoku Co., Ltd., model number “TQ-M4-VSP”, surface roughness 110 nm) are placed on top of each other, pressed with a hot roll at 150 ° C. under a condition of a line load of 10 kN / m, and then using an oven. "Copper foil (thickness 18 μm)/C stage resin layer (thickness 25 μm)/Copper foil (thickness 18 μm)" in which copper foil is laminated on both sides of the C stage resin layer by heating at 250 ° C. for 3 hours. A laminate for high-frequency circuits having a laminate structure of The surface roughness Ra of the copper foil (metal layer) was measured using a white interference microscope (New View 5032 manufactured by ZYGO), and was calculated for a range of 10 μm × 10 μm in accordance with JIS B0601-2001. Arithmetic mean roughness" was taken as the surface roughness Ra. Table 1 shows the results.

<Tensile strength and tensile elongation>
The produced laminate for high-frequency circuits was etched to remove the copper foil, and a resin film for evaluation was produced. A JIS K 7161 No. 7 dumbbell-shaped test piece is cut out from the prepared resin film, and is pulled at 5 mm/min using "Ez-LX" manufactured by Shimadzu Corporation. did. Table 1 shows the results.

<Glass transition temperature (Tg)>
The produced laminate for high-frequency circuits was etched to remove the copper foil, and a resin film for evaluation was produced. A test piece (3 mm wide×1 cm long) was cut out from the prepared resin film, and the glass transition temperature (Tg) was measured with a DMS tester (manufactured by Seiko Instruments Inc., model number “EXSTAR4000”). Table 1 shows the results.

<Elastic modulus>
The produced laminate for high-frequency circuits was etched to remove the copper foil, and a resin film for evaluation was produced. A JIS K 7161 No. 7 dumbbell was cut out from the prepared resin film and subjected to a tensile test at 5 mm/min according to JIS K 7161 using "Ez-LX" manufactured by Shimadzu Corporation to measure the tensile modulus. Table 1 shows the results.

<Electrical properties (relative permittivity, dielectric loss tangent)>
The produced laminate for high-frequency circuits was etched to remove the copper foil, and a resin film for evaluation was produced. A test piece (width 2.6 mm × length 80 mm) was cut out from the prepared resin film, and a cavity resonator perturbation method dielectric constant measurement device (manufactured by Agilent Technologies, model number “PNA-L network analyzer N5230A”, Kanto Denshi Applied Development Co., Ltd. Model number "Cavity Resonator 1
The dielectric constant and dielectric loss tangent were measured at 23° C. and 10 GHz using CP531) for 0 GHz. Table 1 shows the results.

<Peel strength>
A test piece (width 1 cm x length 10 cm) was cut out from the produced high-frequency circuit laminate, and was pulled in a direction of 90 degrees at 500 mm/min using "Instron 5567" manufactured by Instron. The peel strength was measured according to ".4.9". Table 1 shows the results.

3.2.4. Production and Evaluation of Circuit Board On one side of the high-frequency circuit laminate produced above, a copper foil was patterned using a photosensitive dry film, and the pitch was 150 μm and the line widths were 40, 45, 50, 55, and 60 μm, respectively. and copper wiring patterns with a pitch of 750 μm and line widths of 200, 220, 240, 260 and 280 μm, respectively. Then, the "B stage resin layer/release layer laminate" prepared above is placed on the surface of the prepared copper wiring pattern so that the B stage resin layer side is in contact with the copper wiring of the patterned high frequency circuit laminate. , Place a panel on top of it, heat and pressure mold under press conditions of 120°C/3.0 MPa/5 minutes, peel off the release layer (PET film) and heat at 250°C for 3 hours to fabricate a circuit board. did.

<Transmission loss evaluation>
For the circuit board produced above, the transmission loss at a frequency of 20 GHz at 25° C. was measured using a measuring probe (manufactured by Cascade Microtech, single (ACP40GSG250), vector type network analyzer (Keysight technology E8363B). The transmission loss is − A value of 5 dB/100 mm or more was judged to be good.

<Substrate step evaluation>
Both sides of the laminate for high-frequency circuits prepared above are subjected to double-sided etching so that the copper foil has a thickness of 9 μm, and the copper foil is patterned using a photosensitive dry film, so that the pitch is 100 μm and the line width is 50 μm. A copper wiring pattern was produced.
Next, the release layer (PET film) is peeled off from the "metal layer/B stage resin layer/release layer laminate" prepared above, and the resin layer exposed by peeling is in contact with the prepared copper wiring pattern. , sandwiched between end plates, heated and pressurized under press conditions of 120° C./1.1 MPa/2 minutes, and further heated at 250° C. for 3 hours.
Thereafter, the copper foil was patterned using a photosensitive dry film to form copper wiring patterns with a pitch of 100 μm and a line width of 50 μm on both sides.
Finally, the release layer (PET film) was peeled off from the "B-stage resin layer/release layer laminate" prepared above, and the resin layer on the release surface and the prepared copper wiring pattern were placed on both sides so that they were in contact with each other. Then, it was further sandwiched between end plates, heat-pressed under press conditions of 120° C./1.1 MPa/2 min, and further heated at 250° C. for 3 hours to prepare an evaluation board having four layers of copper wiring.

The cross-sectional shape of the prepared evaluation substrate is observed using a scanning electron microscope. If the difference between the concave and convex portions is 5% or less, it is judged to be practical and good, and if it exceeds 5%, it is not practical. It was judged to be bad. Table 1 shows the results.

3.3. Examples 2-7, Comparative Examples 1-3
A laminate for high-frequency circuits was produced in the same manner as in Example 1, except that the resin layer composition was changed to the composition shown in Table 1, and the type of metal film, various film thicknesses, and lamination conditions were changed as shown in Table 1. and evaluated. Table 1 shows the results.

3.4. Example 8
For the resin layer prepared in Example 1 so that the film thickness after curing is 25 μm on a 18 μm thick copper foil (manufactured by Mitsui Kinzoku Co., Ltd., model number “TQ-M4-VSP”, surface roughness 110 nm) The composition is applied using a bar coater, heated at 70 ° C. for 10 minutes using an oven, and then heated at 130 ° C. for 10 minutes to form a "metal layer" having a laminated structure of copper foil / B stage resin layer. /B stage resin layer laminate” was produced.

A 18 μm thick copper foil (manufactured by Mitsui Kinzoku Co., Ltd., model number “TQ-M4-VSP”, surface roughness 110 nm) is superimposed on the exposed resin layer surface of the prepared “metal layer / B stage resin layer laminate”, Pressed with a hot roll at 150 ° C. under the condition of a line load of 10 kN / m, then heated at 250 ° C. for 3 hours using an oven, copper foil was laminated on both sides of the C stage resin layer, copper foil ( A laminate for a high-frequency circuit having a laminate structure of a film thickness of 18 μm)/C stage resin layer (film thickness of 25 μm)/copper foil (film thickness of 18 μm) was produced. The high-frequency circuit laminate thus produced was evaluated in the same manner as in Example 1. Table 1 shows the results.

3.5. Comparative example 4
A resin layer composition was prepared in the same manner as in Example 1 so as to have the composition shown in Table 1, and a copper foil having a thickness of 18 μm (manufactured by Mitsui Kinzoku Co., Ltd., model number “TQ-M4-VSP”, surface roughness 110 nm). Then, the resin layer composition was applied using a bar coater so that the film thickness after curing was 25 μm, heated in an oven at 70° C. for 10 minutes, and then heated at 130° C. for 10 minutes. Furthermore, it heated at 250 degreeC for 3 hours.

After that, copper sputtering is performed on the exposed resin layer surface, and a copper layer is laminated on both sides of the resin layer. A circuit laminate was produced. The high-frequency circuit laminate thus produced was evaluated in the same manner as in Example 1. Table 1 shows the results.

3.6. Comparative example 5
Maleic acid-modified styrene-ethylene butylene-styrene block copolymer (manufactured by Asahi Kasei Chemicals, trade name "Tuftec M1913") was roll-coated. Then, the coated film is left still in an oven and dried at 100° C. for 3 minutes to form a coating (adhesive layer) having a thickness of 25 μm to obtain an “adhesive layer/polyimide layer laminate”. rice field.
After that, both sides of a 18 μm thick copper foil (manufactured by Mitsui Kinzoku Co., Ltd., model number “TQ-M4-VSP”, surface roughness 110 nm) were coated on the surface of the adhesive layer of the prepared “adhesive layer / polyimide layer laminate”. , pressed with a hot roll at 120 ° C. under the condition of a linear load of 10 kN / m, then heated in an oven at 180 ° C. under the conditions of a pressure of 3 MPa for 1 minute, and then After heating at 180°C for 1 hour, a laminated structure of “copper foil (film thickness 18 μm)/polyimide layer (film thickness 25 μm)/copper foil (film thickness 18 μm)” in which copper foil is laminated on both sides of the polyimide layer is formed. A laminate for high-frequency circuits having The high-frequency circuit laminate thus produced was evaluated in the same manner as in Example 1. Table 1 shows the results.

3.7. Evaluation Results Table 1 shows the composition of the resin layer composition used in each example and each comparative example, and the evaluation results of each layer and the high-frequency circuit laminate.

In Table 1 above, the following abbreviations, etc. are supplemented.
<Polymer>
· P-6: manufactured by Sabic, model number "PPO resin powder", glass transition temperature (Tg); 215 ° C.
<Curable compound>
- Compound A: 2,2'-bis (4-cyanatophenyl) propane (manufactured by Tokyo Chemical Industry Co., Ltd.)
- Compound B: SR-16H (manufactured by Sakamoto Yakuhin Kogyo Co., Ltd., epoxy equivalent: 160 g / eq)
- Compound C: HP-4032D (manufactured by DIC, epoxy equivalent; 141 meq / g)
- Compound D: SR-4PG (manufactured by Sakamoto Yakuhin Kogyo Co., Ltd., epoxy equivalent: 305 g / eq)
<Curing aid>
- Curing aid A: 1-benzyl-2-methylimidazole (manufactured by Mitsubishi Chemical Corporation, product name "BMI
12")
・ Curing aid B: Zinc 2-ethyloctylate (manufactured by Wako Pure Chemical Industries, Ltd.)
<Solvent>
・ Solvent A: Cyclopentanone (manufactured by Tokyo Chemical Industry Co., Ltd.)
・ Solvent B: methylene chloride (manufactured by Tokyo Chemical Industry Co., Ltd.)
<Metal layer type>
・Electrolytic copper foil A: manufactured by Mitsui Kinzoku Co., Ltd., product number “TQ-M4-VSP”
・Electrolytic copper foil B: manufactured by Mitsui Kinzoku Co., Ltd., product number “3EC-M3S-HTE”
・ Rolled copper foil A: JX Metals Co., Ltd., product number “GHY5-HA”

From the results in Table 1, when a circuit board is produced using the high-frequency circuit laminates obtained in Examples 1 to 8, the transmission loss of electrical signals in the high-frequency circuit is reduced, and a circuit board with excellent smoothness is produced. It turns out you can.

DESCRIPTION OF SYMBOLS 10... Release layer, 11... Resin layer surface (exposed surface), 12... B stage resin layer, 13... Resin layer surface (exposed surface), 14... Metal layer, 16... Metal layer, 18... C stage resin layer, 20... Metal Layer 22...B stage resin layer 23...Resin layer surface (exposed surface) 24...Metal layer 26...C stage resin layer 100...Laminate for high frequency circuit 200...Laminate for high frequency circuit

Claims (5)

The metal layer and the resin layer are laminated in contact with each other,
The elastic modulus of the resin layer is 0.1 to 3 GPa,
At 23° C., the resin layer has a dielectric loss tangent of 0.001 to 0.01 at a frequency of 10 GHz and a relative dielectric constant of 2 to 3 ,
The resin layer is formed from a resin layer composition,
The resin layer composition is
A repeating unit represented by at least one of the following general formulas (1-1), (1-2) and (1-3) and a repeating unit represented by the following general formula (2): coalescence and
a curable compound that is at least one of an epoxy compound, a cyanate ester compound, a vinyl compound, a silicone compound, an oxazine compound, a maleimide compound, and an allyl compound;
Onium salt compounds, sulfone compounds, sulfonate compounds, sulfonimide compounds, disulfonyldiazomethane compounds, disulfonylmethane compounds, oximesulfonate compounds, hydrazinesulfonate compounds, triazine compounds, nitrobenzyl compounds, benzylimidazole compounds, organic halides, a curing aid that is at least one of a metal octylate and a disulfone;
contains
The content of the polymer is 10 parts by mass or more and 90 parts by mass or less with respect to a total of 100 parts by mass of the curable compound and the polymer,
The content of the curable compound is 10 parts by mass or more and 90 parts by mass or less with respect to 100 parts by mass of the resin layer composition,
A laminate for a high-frequency circuit , wherein the content of the curing aid is 0.08 parts by mass or more and 20 parts by mass or less with respect to 100 parts by mass of the resin layer composition .

[In formulas (1-1) to (1-3), R ¹ is each independently a halogen atom, a monovalent hydrocarbon group having 1 to 20 carbon atoms, a monovalent halogen having 1 to 20 carbon atoms, a hydrocarbon group, a nitro group, a cyano group, a primary to tertiary amino group, or a salt of a primary to tertiary amino group. Each n is independently an integer of 0 to 2. When n is 2, multiple R ^1s may be the same or different, and may be combined in any combination to form a part of the ring structure. ]

[In the formula (2), R ³ and R ⁴ are each independently a halogen atom, a nitro group, a cyano group or a monovalent organic group having 1 to 20 carbon atoms, and c and d are each independently 0 to 8 , e, f, and y are each independently integers of 0 to 2, L is a single bond, —O—, —S—, —CO—, —SO—, —SO ₂ — or carbon atoms of 1 to 20 divalent organic groups. ] 2. The laminate for high-frequency circuits according to claim 1, wherein the peel strength between said resin layer and said metal layer is 5 N/cm or more. 3. The high-frequency circuit laminate according to claim 1, wherein the resin layer has a thickness of 10 to 100 μm, and the metal layer has a thickness of 10 to 50 μm. 4. The laminate for high-frequency circuits according to claim 1, which has a thickness of 50 to 200 μm. A flexible printed circuit board comprising the high-frequency circuit laminate according to any one of claims 1 to 4.

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