WO2023189794A1

WO2023189794A1 - Metal-clad laminated board and method for producing same

Info

Publication number: WO2023189794A1
Application number: PCT/JP2023/010803
Authority: WO
Inventors: 智典安藤; 哲平西山
Original assignee: 日鉄ケミカル＆マテリアル株式会社
Priority date: 2022-03-31
Filing date: 2023-03-20
Publication date: 2023-10-05
Also published as: TW202404808A

Abstract

This metal-clad laminated board 100 has a structure that (a metal layer 10A)/(an adhesive layer 20A)/(an inorganic filler-containing fluororesin layer 30)/(an adhesive layer 20B)/(a metal layer 10B) are laminated in this order. The metal-clad laminated board 100 satisfies either one of the requirements (a) and (b): (a) when a main resin constituting the adhesive layer 20A, 20B is a crystalline resin, the melting point Tm1 of the adhesive layer 20A, 20B is higher than the melting point Tm2 of the inorganic filler-containing fluororesin layer 30; and (b) when the main resin constituting the adhesive layer 20A, 20B is an amorphous resin, the storage modulus E' of the adhesive layer 20A, 20B at the melting point Tm2 of the inorganic filler-containing fluororesin layer 30 is 1×106Pa or more. In the metal-clad laminated board 100, the thermal expansion coefficient of the inorganic filler-containing fluororesin layer is 60 ppm/K or less.

Description

Metal-clad laminate and its manufacturing method

The present invention relates to a method for manufacturing a metal-clad laminate useful as, for example, a circuit board material.

In recent years, as electronic devices have become smaller, lighter, and space-saving, flexible printed circuit boards (FPCs) have become thinner, lighter, more flexible, and have excellent durability even after repeated bending. Demand for circuits is increasing. FPCs can be mounted three-dimensionally and with high density even in limited spaces, so their use is expanding, for example, for wiring of electronic devices such as HDDs, DVDs, and smartphones, as well as parts such as cables and connectors. .

FPC is manufactured by etching the metal layer of a metal clad laminate such as a copper clad laminate (CCL) to form wiring. Currently, metal-clad laminates in which highly heat-resistant polyimide is used for the insulating resin layer in contact with the metal foil are commonly used. However, as the speed of communication equipment has increased in recent years, the development of 5G communication and even 6G communication is progressing, and circuit board materials are also becoming more suitable for millimeter wave radar boards, antenna boards, etc. that can support high-speed communication standards. Materials are currently being considered. Among such materials, fluororesins are attracting attention because they have a low dielectric loss tangent and are expected to reduce signal transmission loss.

Since fluororesins have a large coefficient of thermal expansion, studies are being conducted to incorporate inorganic fillers in order to take advantage of the property of low dielectric loss tangent and achieve low thermal expansion, which is a required property as an insulating material for circuit boards. However, there is a problem in that when the inorganic filler is highly filled, the adhesion with the low roughening copper foil decreases (for example, Patent Document 1).

Patent No. 6997104

In Patent Document 1, in the process of manufacturing a composite material layer containing an inorganic filler in a fluororesin matrix, a casting process is performed in which a dispersion composition containing a fluororesin and an inorganic filler is applied to a base material and dried. ing. When a composite material containing an inorganic filler is formed in a casting process in this way, voids are generated in the coating film. In order to eliminate voids, it is necessary to heat the composite material by applying heat to a temperature higher than the flow temperature of the composite material by thermocompression bonding. However, when an adhesive layer is previously formed on the metal foil and a coating film is formed thereon, it is necessary to consider both the suppression of flow of the adhesive layer and the elimination of voids in the composite material layer. That is, when an adhesive layer is provided, there is a concern that it is difficult to simultaneously eliminate voids and suppress flow of the adhesive layer and thickness unevenness. Regarding this point, Patent Document 1 does not provide a layer that is clearly positioned as an adhesive layer adjacent to the metal layer, and therefore does not consider suppressing the flow of the adhesive layer.

Therefore, the present invention aims to eliminate voids in the inorganic filler-containing fluororesin layer and ensure adhesion to the metal foil, while preventing the adhesive layer from flowing out and uneven thickness during thermocompression bonding. purpose.

In view of the above circumstances, as a result of intensive studies, the above problem can be solved by focusing on the melting point of the inorganic filler-containing fluororesin layer and considering the relationship between this melting point and the melting point or storage modulus of the adhesive layer. They discovered this and completed the present invention.

That is, the metal-clad laminate of the present invention is
a metal layer;
an adhesive layer in direct contact with the metal layer;
an inorganic filler-containing fluororesin layer containing an inorganic filler in the fluororesin, which is laminated directly or indirectly on the adhesive layer;
It is equipped with
In the metal-clad laminate of the present invention, the adhesive layer and the inorganic filler-containing fluororesin layer are a) or b) as follows:
a) When the main resin constituting the adhesive layer is a crystalline resin, the melting point Tm1 of the adhesive layer is higher than the melting point Tm2 of the inorganic filler-containing fluororesin layer;
b) When the main resin constituting the adhesive layer is an amorphous resin, the storage elastic modulus E' of the adhesive layer at the melting point Tm2 of the inorganic filler-containing fluororesin layer is 1 x 10 ⁶ Pa or more;
The inorganic filler-containing fluororesin layer has a coefficient of thermal expansion (CTE) of 60 ppm/K or less.

The metal-clad laminate of the present invention was measured using a split cylinder resonator (SCR resonator) after controlling the humidity of the inorganic filler-containing fluororesin layer for 24 hours under constant temperature and humidity conditions of 23° C. and 50% RH. The dielectric loss tangent at 60 GHz may be less than 0.0025.

The metal-clad laminate of the present invention may have a layer structure in which metal layer/adhesive layer/inorganic filler-containing fluororesin layer/adhesive layer/metal layer are laminated in this order.

In the metal-clad laminate of the present invention, the ratio of the thickness of the adhesive layer to the total thickness of the adhesive layer and the inorganic filler-containing fluororesin layer may be within a range of 1 to 25%.

The method for manufacturing a metal-clad laminate of the present invention is a method for manufacturing the metal-clad laminate described above, comprising:
preparing a first laminate in which an adhesive layer is laminated on a metal layer;
A second laminate in which the adhesive layer and the dispersion composition layer are laminated on the metal layer is formed by applying a dispersion composition containing an inorganic filler and a fluororesin on the adhesive layer and heat-treating the adhesive layer. a step of forming;
By using two of the second laminates and thermocompression bonding with the dispersion composition layers facing each other, or by using the first laminate and the second laminate, the adhesive layer and the By thermocompression bonding the dispersion composition layers facing each other, a metal-clad laminate having a layer structure in which metal layer/adhesive layer/inorganic filler-containing fluororesin layer/adhesive layer/metal layer is laminated in this order is formed. The process of
Contains.

In the metal-clad laminate of the present invention, the melting point Tm1 or storage modulus E' of the adhesive layer is taken into consideration in relation to the melting point Tm2 of the inorganic filler-containing fluororesin layer, so the adhesive layer flows out during thermocompression bonding. This attempt is made to both eliminate voids in the inorganic filler-containing fluororesin layer and ensure adhesion to the metal foil while preventing the occurrence of thickness unevenness. Therefore, the metal-clad laminate of the present invention is useful as a circuit board material compatible with high-speed communication standards.

FIG. 1 is a schematic cross-sectional view showing the layer structure of a metal-clad laminate according to a preferred embodiment of the present invention. FIG. 2 is an explanatory diagram of the manufacturing process of the metal-clad laminate shown in FIG. 1. FIG. FIG. 2 is an explanatory diagram of another manufacturing process of the metal-clad laminate shown in FIG. 1. FIG. FIG. 2 is an explanatory diagram of still another manufacturing process of the metal-clad laminate of FIG. 1. FIG. FIG. 2 is an explanatory diagram of still another manufacturing process of the metal-clad laminate of FIG. 1. FIG.

Embodiments of the present invention will be described with reference to the drawings as appropriate.

[Metal-clad laminate]
The metal-clad laminate of the present invention includes a metal foil, an adhesive layer in direct contact with the metal foil, and an inorganic filler containing an inorganic filler in a fluororesin that is laminated directly or indirectly on the adhesive layer. A fluororesin layer. In addition, the metal-clad laminate of the present invention may have any layer other than the above.

The metal-clad laminate of the present invention satisfies either of the following conditions a) or b). In the present invention, the term "main resin" refers to a resin that is contained in an amount exceeding 50% by weight based on all the resin components constituting the adhesive layer (the same applies hereinafter).

Condition a)
When the main resin constituting the adhesive layer is a crystalline resin, the melting point Tm1 of the adhesive layer is higher than the melting point Tm2 of the inorganic filler-containing fluororesin layer.
Because the melting point Tm1 is higher than the melting point Tm2 (Tm1>Tm2), flow out occurs in the adhesive layer when thermocompression bonding is performed at a temperature exceeding the melting point Tm2 in order to eliminate voids in the inorganic filler-containing fluororesin layer. It is possible to effectively prevent the occurrence of uneven thickness. Therefore, in the metal-clad laminate, it is possible to reduce the voids in the inorganic filler-containing fluororesin layer and ensure adhesion to the metal foil while preventing the adhesive layer from flowing out or causing thickness unevenness. On the other hand, if the melting point Tm1 is the same as or lower than the melting point Tm2 (Tm1≦Tm2), flow may occur in the adhesive layer or thickness unevenness may occur during thermocompression bonding at a temperature exceeding the melting point Tm2. There is a risk of From the above viewpoint, the melting point Tm1 of the adhesive layer is preferably +5°C or more higher than the melting point Tm2 of the inorganic filler-containing fluororesin layer, and more preferably within the range of +10°C to +50°C.

Regarding the melting point Tm2, the reason why it is defined as the "melting point of the fluororesin layer containing inorganic filler" rather than the "melting point of the fluororesin" is that even if the same fluororesin is used, it is compared to the state without the inorganic filler. This is because when an inorganic filler is contained, the melting point increases due to the influence of the inorganic filler. Therefore, the melting point is not the melting point of the resin alone, but of the "layer" containing the inorganic filler. The melting point Tm2 also changes depending on the content of the inorganic filler, and as the amount of the inorganic filler increases, the melting point Tm2 also increases. Therefore, the melting point Tm2 is a physical property value determined depending on the content of the inorganic filler.

Preferred combinations of resins in which the melting point Tm1 of the crystalline resin constituting the adhesive layer is higher than the melting point Tm2 of the inorganic filler-containing fluororesin layer include, for example:
- The crystalline resin constituting the adhesive layer is a tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA; Tm1 = 305°C), and the inorganic filler-containing fluororesin layer is an ethylene-tetrafluoroethylene copolymer (PFA; Tm1 = 305°C). A combination that is a layer of ETFE; Tm2 = 270-315°C);
・The crystalline resin constituting the adhesive layer is an ethylene-tetrafluoroethylene copolymer (ETFE; Tm1=270°C), and the inorganic filler-containing fluororesin layer is a tetrafluoroethylene-hexafluoropropylene copolymer (FEP). ;Tm2=260~305°C);
- The crystalline resin constituting the adhesive layer is a liquid crystal polymer (Tm1 = 280 to 400°C), and the inorganic filler-containing fluororesin layer is a tetrafluoroethylene-hexafluoropropylene copolymer (FEP; Tm2 = 260 to 305 °C), ethylene-tetrafluoroethylene copolymer (ETFE; Tm2 = 270 to 315 °C), and tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA; Tm2 = 305 to 350 °C). A combination that is a layer;
etc. can be mentioned.

Condition b):
When the main resin constituting the adhesive layer is an amorphous resin, the storage elastic modulus E' of the adhesive layer at the melting point Tm2 of the inorganic filler-containing fluororesin layer is 1×10 ⁶ Pa or more.
Since the storage elastic modulus E' of the adhesive layer at the melting point Tm2 is 1 x 10 ⁶ Pa or more, in order to eliminate voids in the inorganic filler-containing fluororesin layer, when thermocompression bonding is performed at a temperature exceeding the melting point Tm2. In addition, it is possible to effectively prevent the adhesive layer from flowing out or becoming uneven in thickness. Therefore, in the metal-clad laminate, it is possible to reduce the voids in the inorganic filler-containing fluororesin layer and ensure adhesion to the metal foil while preventing the adhesive layer from flowing out or causing thickness unevenness. On the other hand, if the storage elastic modulus E' of the adhesive layer at the melting point Tm2 is less than 1 x 10 ⁶ Pa, flow may occur in the adhesive layer or thickness unevenness may occur during thermocompression bonding at a temperature exceeding the melting point Tm2. There is a possibility that this may occur. From the above viewpoint, the storage elastic modulus E' of the adhesive layer at the melting point Tm2 is preferably 1×10 ⁷ Pa or more.

Preferred combinations of amorphous resins in which the storage modulus E' at the melting point Tm2 of the inorganic filler-containing fluororesin layer is 1 x 10 ⁶ Pa or more include, for example:
- The inorganic filler-containing fluororesin layer is a tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer layer (PFA; Tm2 = 305 to 350°C), and the amorphous resin constituting the adhesive layer has an E' at Tm2. a combination of one or more selected from thermoplastic polyimide, thermoplastic polyamide, and thermoplastic polyamide-imide having a pressure of 1×10 ⁶ Pa or more;
- The inorganic filler-containing fluororesin layer is a tetrafluoroethylene-hexafluoropropylene copolymer layer (FEP; Tm2 = 260 to 305°C), and the amorphous resin constituting the adhesive layer has an E' at Tm2 of A combination of one or more selected from thermoplastic polyimide, thermoplastic polyamide, and thermoplastic polyamideimide having a pressure of 1×10 ⁶ Pa or more;
- The inorganic filler-containing fluororesin layer is a layer of ethylene-tetrafluoroethylene copolymer (ETFE; Tm2 = 270 to 315°C), and the amorphous resin constituting the adhesive layer has an E' at Tm2 of 1× A combination of one or more selected from thermoplastic polyimide, thermoplastic polyamide, and thermoplastic polyamide-imide having a pressure of 10 ⁶ Pa or more;
etc. can be mentioned.

Next, each layer constituting the metal-clad laminate of the present invention will be explained.

(metal layer)
The material of the metal layer is not particularly limited, but examples include copper, stainless steel, iron, nickel, beryllium, aluminum, zinc, indium, silver, gold, tin, zirconium, tantalum, titanium, lead, magnesium, manganese, and these. Examples include alloys of Among these, copper or copper alloy is particularly preferred. Note that the material of the wiring layer in the circuit board of this embodiment, which will be described later, is also the same as that of the metal layer.

The thickness of the metal layer is not particularly limited, but if a metal foil such as copper foil is used, it is preferably 35 μm or less, more preferably within the range of 5 to 25 μm. From the viewpoint of production stability and handling properties, the lower limit of the thickness of the metal foil is preferably 5 μm. In addition, when using copper foil, rolled copper foil or electrolytic copper foil may be used. Moreover, as the copper foil, commercially available copper foil can be used.

The surface roughness of the metal layer is not particularly limited, but from the viewpoint of ensuring both adhesion with the adhesive layer and conductor loss, the ten-point average roughness (Rzjis) is 0.3 to 1.5. It is preferred to have a roughened surface within the range of . Note that the lower the surface roughness of the metal layer, the greater the effect of providing the adhesive layer, so the ten-point average roughness (Rzjis) is more preferably within the range of 0.3 to 1.0.
Further, the metal foil may be subjected to a surface treatment using, for example, siding, aluminum alcoholate, aluminum chelate, a silane coupling agent, etc., for the purpose of antirust treatment or improvement of adhesive strength.

(Adhesive layer)
The resin constituting the adhesive layer is not particularly limited, but for example, thermoplastic polyimide, thermoplastic polyamideimide, thermoplastic polyamide, fluororesin, liquid crystal polymer, etc. are preferable. As the fluororesin, the same fluororesin as used in the inorganic filler-containing fluororesin layer described below can be used, provided that condition a or b is satisfied.

(Fluororesin layer containing inorganic filler)
The inorganic filler-containing fluororesin layer contains a fluororesin as a matrix resin and an inorganic filler dispersed in the matrix resin.
The fluororesin constituting the inorganic filler-containing fluororesin layer is a polymer containing fluorine atoms, and its type is not particularly limited, but examples include polytetrafluoroethylene (PTFE), tetrafluoroethylene-perfluoroalkyl vinyl ether, etc. Polymer (PFA), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), ethylene-tetrafluoroethylene copolymer (ETFE), ethylene-tetrafluoroethylene-hexafluoropropylene copolymer (EFEP), polyfluoride Examples include vinyl (PVF) and polyvinylidene fluoride (PVDF). These may be used in combination of two or more types, and a portion of the fluororesin may contain a monomer unit based on a perfluoroolefin having a functional group. As the functional group, a carbonyl group-containing group, a hydroxy group, an epoxy group, an amide group, an amino group, and an isocyanate group are preferable. Among these fluororesins, those showing low dielectric loss tangent include polytetrafluoroethylene (PTFE), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), and tetrafluoroethylene-hexafluoropropylene copolymer ( FEP) is more preferred.

The type of inorganic filler is not particularly limited, but from the viewpoint of reducing the thermal expansion coefficient of the inorganic filler-containing fluororesin layer, for example, silicon dioxide (silica), aluminum oxide (alumina), magnesium oxide (magnesia), beryllium oxide, Niobium oxide, titanium oxide, boron nitride, aluminum nitride, silicon nitride, aluminum fluoride, calcium fluoride, magnesium fluoride, potassium silicofluoride, talc, glass, barium titanate, and the like are preferred. These may be used in combination of two or more types. Among these, silicon dioxide (silica), aluminum oxide, boron nitride, glass, etc. are more preferable as they have a low coefficient of thermal expansion.

The average particle diameter (D ₅₀ ) of the inorganic filler is not particularly limited, but it should be taken into consideration the ratio to the thickness of the insulating resin layer when used in a circuit board, and from the viewpoint of ensuring the punchability of the insulating resin layer. For example, it is within the range of 0.05 to 50 μm, preferably within the range of 0.1 to 20 μm. Further, the specific surface area is not particularly limited, but from the viewpoint of suppressing deterioration of the dielectric loss tangent, it is preferably within the range of 0.1 to 20 m ² /g, preferably within the range of 0.1 to 10 m ² /g. The average particle diameter of the inorganic filler can be determined by measuring the particle size distribution of the powder particles using, for example, a laser diffraction/scattering method, calculating a cumulative curve with the total volume of the powder particles as 100%, and determining the cumulative volume on the cumulative curve of 50%. % by measuring the particle diameter, and the specific surface area can be measured by the BET method.

The shape of the inorganic filler is not particularly limited, but from the viewpoint of reducing the difference in coefficient of thermal expansion in the thickness direction and in the surface direction, for example, spherical shape, crushed spherical shape, etc. are preferable. Further, the inorganic filler may be hollow.

It is preferable that the inorganic filler is surface-treated with a coupling agent or the like. Examples of coupling agents used for surface treatment include 3-aminopropylethoxysilane, vinyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-methacryloxypropylethoxysilane, Examples include 3-isocyanatepropylethoxysilane and hexamethyldisilazane.

The dispersion composition used to form the inorganic filler-containing fluororesin layer preferably contains a dispersant. The type of dispersant is not particularly limited, but from the viewpoint of dispersing the fluororesin well, for example, a fluorine surfactant is preferable. As the fluorine-based surfactant, for example, a nonionic fluorine-based surfactant having a perfluoroalkenyl structure having a double bond in the molecule is more preferable.

The weight ratio of the fluororesin in the inorganic filler-containing fluororesin layer is 15 parts by weight per 100 parts by weight of the total solid content of the inorganic filler-containing fluororesin layer, from the viewpoint of lowering the dielectric loss tangent and supporting high-frequency signal transmission. It is preferably within the range of ~40 parts by weight, and more preferably within the range of 20-35 parts by weight.
In addition, the weight ratio of the inorganic filler is determined based on 100 parts by weight of the total solid content of the fluororesin layer containing the inorganic filler, from the viewpoint of lowering the coefficient of thermal expansion (CTE) and ensuring dimensional stability when applied to a circuit board. , preferably within the range of 55 to 75 parts by weight, and more preferably within the range of 60 to 70 parts by weight. In addition, from another perspective, in order to suppress the coefficient of thermal expansion (CTE) of the fluororesin layer containing inorganic filler, the content ratio of the inorganic filler in the fluororesin layer containing inorganic filler is determined by the total solid content of the fluororesin layer containing inorganic filler. For example, it is preferably within the range of 55 to 75 volume %, more preferably 60 to 70 volume %. In particular, by containing the inorganic filler at a high concentration of 60% by volume or more, voids are likely to occur in the coating film, so that the effects of the invention are more likely to be exhibited. The content of the dispersant in the dispersion composition used to form the inorganic filler-containing fluororesin layer is, for example, 10 parts by weight as the dispersant active ingredient, based on 100 parts by weight of the total solid content of the inorganic filler-containing fluororesin layer. It is preferably within the range of 0.5 to 5 parts by weight, and more preferably within the range of 0.5 to 5 parts by weight.

The coefficient of thermal expansion (CTE) of the fluororesin layer containing an inorganic filler is preferably 60 ppm/K or less, and more preferably within the range of 10 ppm/K or more and 30 ppm/K or less. If the coefficient of thermal expansion (CTE) of the fluororesin layer containing inorganic filler exceeds 60 ppm/K, the dimensional stability of the metal-clad laminate cannot be guaranteed, and problems such as misalignment of wiring positions may occur after circuit processing. There are cases.

In addition, the inorganic filler-containing fluororesin layer has a dielectric loss tangent of 0 at 60 GHz as measured by a split cylinder resonator (SCR resonator) after 24 hours of humidity control under constant temperature and humidity conditions of 23°C and 50% RH. It is preferably less than .0025, more preferably less than 0.0020. Further, the dielectric constant measured under the same conditions is preferably 4.0 or less, more preferably 3.5 or less, and still more preferably 3.0 or less.
If the dielectric loss tangent and relative permittivity exceed the above values, when applied to a circuit board, it will lead to an increase in dielectric loss and cause electrical signal loss on the transmission path of high-frequency signals in the GHz band (for example, 1 to 80 GHz). Such inconveniences are likely to occur.

FIG. 1 shows a cross-sectional configuration of a metal-clad laminate 100 according to a preferred embodiment of the present invention. The metal-clad laminate 100 has a structure in which metal layer 10A/adhesive layer 20A/inorganic filler-containing fluororesin layer 30/adhesive layer 20B/metal layer 10B are laminated in this order. The metal layer 10A and the metal layer 10B are located at the outermost sides, and the adhesive layer 20A and the adhesive layer 20B are arranged inside them, and between the adhesive layer 20A and the adhesive layer 20B, a fluororesin containing an inorganic filler is arranged. A layer 30 is interposed. Note that the metal-clad laminate is not limited to the layer configuration shown in FIG. 1, and may have any layers, for example.

As described above, the metal clad laminate 100 includes:
a) When the main resin constituting the adhesive layer 20A and the adhesive layer 20B is a crystalline resin, the melting point Tm1 of the adhesive layer 20A and the adhesive layer 20B is higher than the melting point Tm2 of the inorganic filler-containing fluororesin layer 30;
b) When the main resin constituting the adhesive layer 20A and the adhesive layer 20B is an amorphous resin, the storage elastic modulus E' of the adhesive layer 20A and the adhesive layer 20B at the melting point Tm2 of the inorganic filler-containing fluororesin layer 30 is 1. ×10 ⁶ Pa or more;
meets any of the following conditions.

In the metal-clad laminate 100, the adhesive layer 20A and the adhesive layer 20B may have the same configuration or different configurations, but preferably have the same configuration. Note that when the adhesive layer 20A and the adhesive layer 20B have different configurations, it is preferable that each of them satisfy the above conditions a) or b).

In the metal-clad laminate 100, the thickness of the adhesive layer 20A and the adhesive layer 20B is preferably within the range of 1 to 20 μm, and more preferably within the range of 2 to 10 μm. If the thickness is less than 1 μm, sufficient adhesion to the

metal layers

10A and 10B may not be obtained, and if it exceeds 20 μm, the dimensional stability of the entire metal-clad laminate 100 may be impaired and the dielectric properties may deteriorate. there is a possibility. Note that the thicknesses of the adhesive layer 20A and the adhesive layer 20B may be the same or different, but are preferably the same.

In the metal-clad laminate 100, the thickness of the inorganic filler-containing fluororesin layer 30 is preferably within the range of 60 to 150 μm, more preferably within the range of 80 to 130 μm. If the thickness is less than 60 μm, it may be difficult to suppress transmission loss when the metal-clad laminate 100 is used as a circuit board, making it difficult to support high-frequency signal transmission. Handling may be difficult.

In the metal-clad laminate 100, the total thickness T _AD of the adhesive layers relative to the total thickness T of the

adhesive layers

20A and 20B and the inorganic filler-containing fluororesin layer 30 (that is, the total thickness of the

adhesive layers

20A and 20B) The ratio [(T _AD /T)×100] is preferably within the range of 1 to 25%, more preferably within the range of 2 to 20%. When the ratio [(T _AD /T) x 100] is less than 1%, sufficient adhesion to the

metal layers

10A and 10B may not be obtained, and when it exceeds 25%, the dimensional stability of the entire metal-clad laminate 100 may be impaired. properties and dielectric properties may deteriorate.

[Method for manufacturing metal-clad laminates]
The metal-clad laminate 100 can be manufactured, for example, by Method 1 or Method 2 below.

(Method 1)
First, as shown in FIG. 2, a laminate in which a metal layer 10A and an adhesive layer 20A are laminated, and a laminate in which a metal layer 10B and an adhesive layer 20B are laminated are respectively prepared. These will be referred to as a first laminate 40.

Next, a dispersion composition that will become the inorganic filler-containing fluororesin layer 30 is applied to the adhesive layer 20A and the adhesive layer 20B of the first laminate 40 to a predetermined thickness, and after drying, the fluororesin is melted. By heating to a temperature higher than that temperature, a dispersed composition layer 31 is formed as shown in FIG. 3, and two second laminates 50 are produced. At this stage, the dispersed composition layer 31 of the second laminate 50 includes voids.

Next, as shown in FIG. 4, the two second laminates 50 are bonded together by thermocompression so that the dispersed composition layers 31 face each other. After the fluororesin in the dispersed composition layer 31 is melted by thermocompression bonding, the fluororesin layer 31 is cooled and solidified to eliminate voids and form the fluororesin layer 30 containing an inorganic filler. The thermocompression bonding temperature may be at least the melting point Tm2 of the inorganic filler-containing fluororesin layer 30, and the upper limit can be set as appropriate depending on the resin type, but for example, within the range of 10 to 80 °C below the melting point Tm2. Preferably, the temperature is high. The pressure during thermocompression bonding can be determined as appropriate depending on the type of resin, but is preferably within the range of 2 to 12 MPa, for example. In this way, as shown in FIG. 1, metal layer 10A/adhesive layer 20A/inorganic filler-containing fluororesin layer 30 (however, a layer in which two dispersed composition layers 31 are bonded together)/adhesive layer 20B/ A metal-clad laminate 100 having a layered structure in which the metal layers 10B are laminated in this order can be manufactured.

(Method 2)
First, a laminate in which the metal layer 10A and the adhesive layer 20A are laminated, and a laminate in which the metal layer 10B and the adhesive layer 20B are laminated are respectively prepared, and these are referred to as the first laminate 40 (FIG. 2 ).

Next, a dispersion composition that will become the inorganic filler-containing fluororesin layer 30 is applied to a predetermined thickness on the adhesive layer 20A of the first laminate, and after drying, the fluororesin is heated to a temperature higher than its melting temperature and dispersed. A composition layer 31 is formed to form a second laminate 50 (see FIG. 3). However, in method 2, the thickness of the dispersed composition layer 31 is made approximately twice as thick as in method 1. At this stage, the dispersed composition layer 31 of the second laminate 50 includes voids.

Next, as shown in FIG. 5, the second laminate 50 and the first laminate are placed so that the dispersed composition layer 31 of the second laminate 50 and the adhesive layer 20B of the first laminate 40 face each other. The laminate 40 is bonded by thermocompression. After the fluororesin in the dispersion composition layer 31 is melted by thermocompression bonding, the fluororesin in the dispersed composition layer 31 is cooled and solidified to eliminate voids and become the inorganic filler-containing fluororesin layer 30. The conditions for thermocompression bonding can be the same as in Method 1. In this way, a metal-clad laminate 100 having a layer structure in which metal layer 10A/adhesive layer 20A/inorganic filler-containing fluororesin layer 30/adhesive layer 20B/metal layer 10B are laminated in this order can be manufactured. .

The dispersion composition used in Methods 1 and 2 preferably contains a fluororesin powder and an inorganic filler, and further contains a dispersant, an organic solvent, etc., if necessary. The weight proportion of the fluororesin powder in the dispersion composition is determined based on 100 parts by weight of the total solid content in the dispersion composition, from the viewpoint of lowering the dielectric loss tangent when formed into a film and making it compatible with high-frequency signal transmission. It is preferably within the range of 15 to 40 parts by weight, and more preferably within the range of 20 to 35 parts by weight.
In addition, the weight ratio of the inorganic filler in the dispersion composition is determined from the viewpoint of lowering the coefficient of thermal expansion (CTE) when formed into a film and ensuring dimensional stability when applied to a circuit board. It is preferably within the range of 55 to 75 parts by weight, and more preferably within the range of 60 to 70 parts by weight, based on 100 parts by weight of solid content.
Furthermore, when a dispersant is included, the content is preferably 10 parts by weight or less, for example, 0.5 to 5 parts by weight, as an active ingredient of the dispersant, based on 100 parts by weight of the total solid content of the dispersion composition. It is more preferable to set it within the range of 1. In addition, when containing an organic solvent, in order to obtain good dispersibility and good coating properties, the total amount of fluororesin powder and inorganic filler should be within the range of 50 to 80% by weight of the entire composition. It is preferable that the content be within the range of 60 to 70% by weight, and more preferably within the range of 60 to 70% by weight. Note that the solid content in the dispersion composition means the total of the components excluding the solvent.
Further, the viscosity of the dispersion composition is not particularly limited, but for example, when the purpose is to coat a thick film of 30 μm or more, it is preferably within the range of 500 to 50,000 cP, and more preferably within the range of 500 to 30,000 cP. If the viscosity is less than 500 cP, the fluidity becomes too high when the dispersion composition is cast, making it difficult to form a thick coating. In particular, it becomes impossible to form a relatively thick coating film in the range of 30 to 150 μm for high frequency transmission applications. Further, if the viscosity is less than 500 cP, sedimentation or aggregation of solid content may occur. On the other hand, if the viscosity of the dispersion composition exceeds 50,000 cP, the viscosity is too high and it becomes difficult to form a coating film by casting.
Note that the viscosity of the dispersion composition can be measured at a temperature of 25° C. using an E-type viscometer.

The first laminate 40 used in Methods 1 and 2 can be manufactured, for example, by applying and drying a solution of the adhesive composition onto the metal foil that will become the

metal layers

10A and 10B.

In the above, the method of applying the solution of the dispersion composition or adhesive composition onto the metal foil or the

adhesive layers

20A, 20B is not particularly limited, and for example, it may be applied using a comma, die, knife, lip, etc. coater. Is possible.

The metal-clad laminate 100 of the present embodiment obtained as described above can be used as a single-sided circuit board or a double-sided circuit board by processing the wiring circuit by etching the metal layer 10A and/or the metal layer 10B. Circuit boards can be manufactured.

[Circuit board]
The metal-clad laminate 100 of this embodiment is mainly useful as a material for circuit boards such as FPCs, rigid-flex circuit boards, and rigid boards. For example, in one embodiment of the present invention, one or both of the two

metal layers

10A and 10B of the metal-clad laminate 100 shown in FIG. 1 is processed into a pattern by a conventional method to form a wiring layer. It is possible to manufacture circuit boards such as certain FPCs.

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

[Measurement of viscosity]
The viscosity at 25° C. was measured using an E-type viscometer (manufactured by Brookfield, trade name: DV-II+Pro).

[Measurement of peel strength]
A circuit was processed on only one copper foil side of the double-sided copper-clad laminate to a width of 1 mm in the resin coating direction at 10 mm intervals, and the circuit was cut into 8 cm width x 4 cm length to prepare a measurement sample. Peel strength was measured using a Tensilon tester (manufactured by Toyo Seiki Seisakusho Co., Ltd., product name: Strograph VE-1D). The copper foil was peeled off in a 180° direction at a rate of 50 mm/min, and the median strength was determined when 10 mm was peeled off.

[Measurement of amount of resin flowing out]
Visually check the edges of the fabricated double-sided copper-clad laminate to see if there is any resin flowing out, and only if flowing out is confirmed, measure the length of the area with a large amount of flowing out using an optical microscope. The amount of outflow was calculated.

[Measurement of resin layer thickness]
For the produced double-sided copper-clad laminate, a cross-section polisher was used to create a precisely polished cross-section in the direction perpendicular to the double-sided copper-clad laminate, and each resin layer was examined using a scanning electron microscope (SEM) on this cross-section. The thickness was measured.

[Void evaluation]
For the produced double-sided copper-clad laminate, a cross-section polisher was used to create a precisely polished cross-section in the direction perpendicular to the double-sided copper-clad laminate, and this cross-section was examined using a scanning electron microscope (SEM) at a magnification of 2000x. Five reflection images of the inorganic filler-containing fluororesin layer were randomly acquired. Next, all of the obtained images were analyzed using image analysis software (trade name: Image-Pro10, manufactured by Hakuto Co., Ltd.), and the percentage of voids was calculated.
Specifically, the image size was determined based on the scale bar of the image obtained by SEM. Next, after setting a brightness range that included only the voids in the image from the brightness distribution, the ratio of the voids to the entire image was calculated, and the average value of the ratios of the voids in the five images was taken as the porosity.
Although the porosity calculated from the image is an area ratio, it was treated as equivalent to a volume ratio by calculating the average value of a plurality of images.

[Measurement of coefficient of thermal expansion (CTE)]
A fluororesin film cut into a size of 3 mm in the coating width direction and 20 mm in the coating direction was set in a thermomechanical analyzer (Hitachi High-Technology, trade name: TMA/SS7100). At this time, the distance between the device jigs (measurement effective length) was 15 mm. Next, the temperature was raised from 30°C to 260°C at a constant temperature increase rate while applying a load of 5.0g, and after holding at that temperature for 10 minutes, it was cooled at a rate of 5°C/min, and from 250°C to 100°C. The average coefficient of thermal expansion (coefficient of thermal expansion) up to ℃ was determined.

[Measurement of dielectric loss tangent]
The dielectric loss tangent (Df) of the film at 60 GHz was measured using a network analyzer (manufactured by Keysight Technologies, trade name: PNA N5227B) and a split cylinder resonator (SCR resonator).
Note that Df during humidity control was measured after the film used for measurement was left for 24 hours under conditions of temperature: 22 to 24° C. and humidity: 45 to 55%.

[Measurement of surface roughness of copper foil]
The surface roughness of the copper foil was measured using AFM (manufactured by Bruker AXS, trade name: Dimension Icon type SPM), probe (manufactured by Bruker AXS, trade name: TESPA (NCHV), tip radius of curvature 10 nm, Using a spring constant of 42 N/m), measurement was performed in a tapping mode in an area of 80 μm x 80 μm on the surface of the copper foil, and the ten-point average roughness (Rzjis) was determined.

[Measurement of inorganic filler-containing fluororesin layer, melting point of crystalline resin, and storage modulus of amorphous resin at 300°C and 350°C]
The melting points of the inorganic filler-containing fluororesin layer and the crystalline resin were measured using a dynamic viscoelasticity measuring device (DMA: manufactured by TA Instruments, trade name: RSA G2) using a film with a size of 5 mm x 70 mm. Measurements were performed from 30° C. to 400° C. at a heating rate of 4° C./min and a frequency of 10 Hz, and the temperature was set at which the change in elastic modulus (tan δ) was maximum.
The storage modulus of the amorphous resin at 300° C. and 350° C. was measured using a dynamic viscoelasticity measuring device in the same manner as the melting point of the crystalline resin, and the storage modulus at each temperature was confirmed.
Note that the determination of whether it is a crystalline resin or an amorphous resin is determined by the temperature at which the maximum tan δ obtained by dynamic viscoelasticity measurement is obtained when the film is measured using a differential scanning calorimeter. A case where there was a clear endothermic peak associated with melting in the vicinity was defined as a crystalline resin, and a case where there was a baseline shift due to glass transition was defined as an amorphous resin.

The compounds used in the synthesis examples and dispersion composition preparation examples are shown below.
Fluorine resin powder (1): Fluon+ (Fluon is a registered trademark) EA-2000PW 10, AGC fluorine resin powder, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, average particle size: 2 to 3 μm
Fluorine resin dispersion (1): NEOFLON FEP ND-2R, FEP dispersion manufactured by Daikin Industries, tetrafluoroethylene-hexafluoropropylene copolymer silica filler (1): SC70-2: Amorphous manufactured by Nippon Steel Chemical & Materials Quality silica filler, average particle diameter (D ₅₀ ): 11.7 μm, specific surface area 1.1 m ² /g, treated with 0.12% by weight of silica by hexamethyldisilazane dispersant (1 ): Ftergent 710FL: Nonionic fluorine-containing dispersant manufactured by Neos (dispersant active ingredient 50% by weight, ethyl acetate 50% by weight)
BPDA: 3,3',4,4'-biphenyltetracarboxylic dianhydride PMDA: Pyromellitic dianhydride m-TB: 2,2'-dimethyl-4,4'-diaminobiphenyl TPE-R: 1 ,3-bis(4-aminophenoxy)benzene BAPP: 2,2-bis[4-(4-aminophenoxy)phenyl]propaneDMAc: N,N-dimethylacetamide

(Dispersion composition preparation example 1)
T. of Primix Co., Ltd. (former company name: Tokushu Kika Kogyo Co., Ltd.) K. In a container of HIVIS MIX (model 2P-03), 70.4 g of fluororesin powder (1), 169.6 g of silica filler (1), 24 g of dispersant (1) (12 g of dispersant active ingredient), and 26.7 g of DMAc was added and stirred at 20 rpm for 5 minutes. Thereafter, the apparatus was stopped, and the stirring blades and the side wall of the container were scraped off with the kneaded material. After the above-mentioned stirring and the apparatus was stopped, scraping of the kneaded material from the stirring blade and the side wall of the container was carried out three times.

Next, in order to finely adjust the ratio of the fluororesin powder (1) and silica filler (1) to the total amount, a small amount of DMAc was added to the kneaded product, and the mixture was stirred at 30 rpm for 5 minutes, and the state of the kneaded product was checked. . This operation was repeated until the kneaded material was in the form of a lump with no powdery parts. In this study, when the total proportion of fluororesin powder (1) and silica filler (1) reached 81% by weight based on the total amount, it became lumpy, and powdery parts were also observed inside the kneaded lump. It wasn't done. From the lumpy state, kneading was started at 30 rpm, stopped at 15 minute intervals, and the kneaded material was scraped off from the stirring blade and the side wall of the container. This operation was repeated four times in total for a total of 60 minutes to obtain a dispersion composition 1-1. Dispersion Composition 1-1 was judged to be a "solid" because it had no fluidity and its viscosity could not be measured.

Thereafter, dispersion composition 1-1 was diluted and stirred in stages with DMAc so that the total proportion of fluororesin powder (1) and silica filler (1) was 70% by weight based on the total amount, and the mixture was stirred at 100 rpm. A dispersion composition 1-2 having a viscosity of 1080 cP as measured was obtained.

(Dispersion composition preparation example 2)
In a 310 ml polypropylene container, 100.0 g of fluororesin dispersion (1) (FEP 25.0 g), 59.7 g of silica filler (1), and 6.0 g of dispersant (1) (dispersant active ingredient 3) .0g) were added. Next, the two samples were set in a rotation-revolution stirrer [SK-350G manufactured by Photo Kagaku Co., Ltd.] and stirred for 4 minutes at a revolution speed of 1060 rpm and an autorotation speed of 1060 rpm. I got it.

(Dispersion composition preparation example 3)
T. of Primix Co., Ltd. (former company name: Tokushu Kika Kogyo Co., Ltd.) K. In a container of HIVIS MIX (model 2P-03), 94.2 g of fluororesin powder (1), 145.9 g of silica filler (1), 24 g of dispersant (1) (12 g of dispersant active ingredient), and 26.7 g of DMAc was added and stirred at 20 rpm for 5 minutes. Thereafter, the apparatus was stopped, and the stirring blades and the side wall of the container were scraped off with the kneaded material. After the above-mentioned stirring and the apparatus was stopped, scraping of the kneaded material from the stirring blade and the side wall of the container was carried out three times.

Next, in order to finely adjust the ratio of the fluororesin powder (1) and silica filler (1) to the total amount, a small amount of DMAc was added to the kneaded product, and the mixture was stirred at 30 rpm for 5 minutes, and the state of the kneaded product was checked. . This operation was repeated until the kneaded material was in the form of a lump with no powdery parts. In this study, when the total proportion of fluororesin powder (1) and silica filler (1) reached 79% by weight based on the total amount, it became lumpy, and powdery parts were also observed inside the kneaded lump. It wasn't done. From the lumpy state, kneading was started at 30 rpm, stopped at 15 minute intervals, and the kneaded material was scraped off from the stirring blade and the side wall of the container. This operation was repeated four times in total for a total of 60 minutes to obtain a dispersion composition 3-1. Dispersion Composition 3-1 was judged to be a "solid" because it had no fluidity and its viscosity could not be measured.

Thereafter, dispersion composition 3-1 was diluted stepwise with DMAc and stirred so that the total proportion of fluororesin powder (1) and silica filler (1) was 65% by weight based on the total amount, and the mixture was stirred at 100 rpm. A dispersion composition 3-2 having a viscosity of 1480 cP was obtained when measured.

(Dispersion composition preparation example 4)
Two samples were prepared by adding 100.0 g of fluororesin powder (1), 10.0 g of dispersant (1) (5.0 g of dispersant active ingredient), and 90 g of DMAc in a 310 ml polypropylene container. Next, the two samples were set in a rotation-revolution stirrer [SK-350G manufactured by Photo Kagaku Co., Ltd.] and stirred for 4 minutes under the conditions of revolution of 1060 rpm and rotation of 1060 rpm.Dispersion Composition 4 with a viscosity of 130 cP when measured at 100 rpm I got it.

(Synthesis example 1)
Under a nitrogen stream, 2.7701 g of m-TB (0.01305 mol) and 15.2580 g of TPE-R (0.05219 mol) and a solid content concentration after polymerization of 12% by weight were placed in a 500 ml separable flask. An amount of DMAc was added and dissolved by stirring at room temperature. Next, after adding 13.6386 g of BPDA (0.04636 mol) and 4.3333 g of PMDA (0.01987 mol), a polymerization reaction was carried out by continuing stirring at room temperature for 3 hours to obtain polyamic acid solution A. Ta. The solution viscosity of polyamic acid solution A was 1600 cP.

(Synthesis example 2)
Under a nitrogen stream, 23.3871 g of BAPP (0.05697 mol) and DMAc in an amount such that the solid content concentration after polymerization is 12% by weight were placed in a 500 ml separable flask, and dissolved by stirring at room temperature. Ta. Next, after adding 12.6129 g of PMDA (0.05783 mol), stirring was continued for 3 hours at room temperature to carry out a polymerization reaction to obtain polyamic acid solution B. The solution viscosity of polyamic acid solution B was 2130 cP.

(Manufacturing example 1)
After coating the dispersion composition 1-2 on a copper foil (electrolytic copper foil, thickness: 12 μm, ten-point average roughness Rzjis on the resin layer side: 0.6 μm), it was heated at 80° C. using a hot air oven. Drying treatment was performed for 1 minute and at 120° C. for 3 minutes. Next, heat treatment was performed at 280° C. for 3 minutes and at 340° C. for 6 minutes to obtain a single-sided copper-clad laminate 1.

Next, prepare two single-sided copper-clad laminates 1, put the resin sides together and put them into a batch press machine, then heat them under vacuum from 40°C to 360°C over 60 minutes until the temperature reaches 360°C. At the same time, pressurization was performed at a pressure of 8 MPa. After that, after holding at 360℃ for 5 minutes, cooling to 40℃ for 60 minutes, and as soon as the temperature reached 40℃, the pressure was released to form a double-sided copper-clad laminate with a dielectric layer thickness of 100μm. Board 1 was obtained.

Subsequently, the copper foil of the double-sided copper-clad laminate 1 was removed by etching using a ferric chloride aqueous solution to prepare a fluororesin film 1.
The CTE of the fluororesin film 1 was 23 ppm/K, and the melting point (Tm) was 350°C.

(Manufacturing example 2)
After coating the dispersion composition 2 on a copper foil (electrolytic copper foil, thickness: 12 μm, ten-point average roughness Rzjis on the resin layer side: 0.6 μm), it was heated at 80° C. for 1 minute using a hot air oven. , a drying process was performed at 120° C. for 3 minutes. Next, heat treatment was performed at 220° C. for 3 minutes and at 300° C. for 6 minutes to obtain a single-sided copper-clad laminate 2.

Next, prepare two single-sided copper-clad laminates 2, put their resin sides together and put them into a batch press machine, then heat them under vacuum from 40°C to 310°C over 50 minutes until the temperature reaches 310°C. At the same time, pressurization was performed at a pressure of 8 MPa. After that, after holding at 310℃ for 5 minutes, cooling to 40℃ for 50 minutes, and as soon as the temperature reached 40℃, the pressure was released to form a double-sided copper clad laminate with a dielectric layer thickness of 100μm. Board 2 was obtained.

Subsequently, the copper foil of the double-sided copper-clad laminate 2 was removed by etching using a ferric chloride aqueous solution to prepare a fluororesin film 2.
The CTE of the fluororesin film 2 was 23 ppm/K, and the melting point (Tm) was 303°C.

(Manufacturing example 3)
After coating the dispersion composition 3-2 on a copper foil (electrolytic copper foil, thickness: 12 μm, ten-point average roughness Rzjis on the resin layer side: 0.6 μm), it was heated at 80° C. using a hot air oven. Drying treatment was performed for 1 minute and at 120° C. for 3 minutes. Next, heat treatment was performed at 280° C. for 3 minutes and at 340° C. for 6 minutes to obtain a single-sided copper-clad laminate 3.

Next, prepare two single-sided copper-clad laminates 3, put their resin sides together and put them into a batch press machine, then heat them under vacuum from 40°C to 360°C over 60 minutes until the temperature reaches 360°C. At the same time, pressurization was performed at a pressure of 8 MPa. After that, after holding at 360℃ for 5 minutes, cooling to 40℃ for 60 minutes, and as soon as the temperature reached 40℃, the pressure was released to form a double-sided copper-clad laminate with a dielectric layer thickness of 100μm. Board 3 was obtained.

Subsequently, the copper foil of the double-sided copper-clad laminate 3 was removed by etching using a ferric chloride aqueous solution to prepare a fluororesin film 3.
The CTE of the fluororesin film 3 was 52 ppm/K, and the melting point (Tm) was 325°C.

(Manufacturing example 4)
After coating the dispersion composition 4 on a copper foil (electrolytic copper foil, thickness: 12 μm, ten-point average roughness Rzjis on the resin layer side: 0.6 μm), it was heated at 80° C. for 1 minute using a hot air oven. , a drying process was performed at 120° C. for 3 minutes. Next, heat treatment was performed at 280° C. for 3 minutes and at 340° C. for 3 minutes to obtain a single-sided copper-clad laminate 4.

Next, prepare two single-sided copper-clad laminates 4, put their resin sides together, put them into a batch press, and heat them under vacuum from 40°C to 320°C over 50 minutes until the temperature reaches 320°C. At the same time, pressurization was performed at a pressure of 2 MPa. After that, after holding at 320℃ for 5 minutes, cooling to 40℃ for 50 minutes, and as soon as the temperature reached 40℃, the pressure was released to form a double-sided copper clad laminate with a dielectric layer thickness of 100μm. Plate 4 was obtained.

Subsequently, the copper foil of the double-sided copper-clad laminate 4 was removed by etching using a ferric chloride aqueous solution to prepare a fluororesin film 4.
The CTE of the fluororesin film 4 was 240 ppm/K, and the melting point (Tm) was 305°C.

(Manufacturing example 5)
After coating the fluororesin dispersion (1) on a copper foil (electrolytic copper foil, thickness: 12 μm, ten-point average roughness Rzjis on the resin layer side: 0.6 μm), it was heated for 80 minutes using a hot air oven. Drying treatment was performed at 120°C for 1 minute and 3 minutes at 120°C. Next, heat treatment was performed at 240° C. for 3 minutes and at 300° C. for 3 minutes to obtain a single-sided copper-clad laminate 5.

Next, prepare two single-sided copper-clad laminates 5, put their resin sides together and put them into a batch press, and heat them under vacuum from 40°C to 30°C over 45 minutes until the temperature reaches 290°C. At the same time, pressurization was performed at a pressure of 2 MPa. After that, after holding at 290℃ for 5 minutes, cooling to 40℃ for 45 minutes, and as soon as the temperature reached 40℃, the pressure was released to form a double-sided copper-clad laminate with a dielectric layer thickness of 100μm. Plate 5 was obtained.

Subsequently, the copper foil of the double-sided copper-clad laminate 5 was removed by etching using a ferric chloride aqueous solution to prepare a fluororesin film 5.
The CTE of the fluororesin film 5 was 180 ppm/K, and the melting point (Tm) was 260°C.

(Manufacturing example 6)
Polyamic acid solution A was evenly applied onto a copper foil (electrolytic copper foil, thickness: 12 μm, ten-point average roughness Rzjis on the resin layer side: 0.6 μm) so that the thickness after curing was approximately 25 μm. After that, heat drying was performed at 120° C. for 2 minutes to remove the solvent. Furthermore, stepwise heat treatment was performed from 120° C. to 360° C. for 10 minutes to complete imidization and obtain a single-sided copper-clad laminate 6.

Subsequently, the copper foil of the single-sided copper-clad laminate 6 was removed by etching using a ferric chloride aqueous solution to prepare a polyimide film A. Polyimide film A had a CTE of 51 ppm/K, a glass transition temperature of 227°C, a storage modulus of 2.7 x 10 ⁷ Pa at 300°C, and a storage modulus of 1.1 x 10 ⁷ Pa at 350°C. This confirmed that it was a thermoplastic polyimide and had a storage modulus of 1×10 ⁶ Pa or more at 325°C.

(Manufacturing example 7)
Polyamic acid solution B was evenly applied onto a copper foil (electrolytic copper foil, thickness: 12 μm, ten-point average roughness Rzjis on the resin layer side: 0.6 μm) so that the thickness after curing was approximately 25 μm. After that, heat drying was performed at 120° C. for 2 minutes to remove the solvent. Furthermore, stepwise heat treatment was performed from 120° C. to 360° C. for 10 minutes to complete imidization and obtain a single-sided copper-clad laminate 7.

Subsequently, the copper foil of the single-sided copper-clad laminate 7 was removed by etching using a ferric chloride aqueous solution to prepare a polyimide film B.
Polyimide film B has a CTE of 55 ppm/K, a glass transition temperature of 332°C, a storage modulus of 1.0 x 10 ⁹ Pa at 300°C, and a storage modulus of 5.6 x 10 ⁷ Pa at 350°C. It was a thermoplastic polyimide.

<Example 1>
After applying polyamic acid solution A as an adhesive layer on a copper foil (electrolytic copper foil, thickness: 12 μm, ten-point average roughness Rzjis on the resin layer side: 0.6 μm), it was heated at 120°C for 1 minute. The solvent was removed by heating and drying. Furthermore, stepwise heat treatment was performed from 120° C. to 360° C. for 5 minutes to complete imidization.

Next, after coating the dispersion composition 1-2 on the adhesive layer as a fluororesin layer containing an inorganic filler, drying treatment was performed at 80° C. for 1 minute and at 120° C. for 3 minutes using a hot air oven. Next, heat treatment was performed at 280° C. for 3 minutes and at 340° C. for 6 minutes to obtain a single-sided copper-clad laminate 8.

Two of the obtained single-sided copper-clad laminates 8 were prepared, and the resin surfaces overlapped and put into a batch press machine, heated to 360°C under vacuum, and after reaching 360°C, heated to 8 MPa for 5 minutes. By pressing at a pressure of 100 μm, a double-sided copper-clad laminate 6 with a dielectric layer thickness of 100 μm was obtained.
At this time, the thickness of each adhesive layer was 4 μm, the thickness of the inorganic filler-containing fluororesin layer was 92 μm, and the total thickness of the dielectric layer was 100 μm. Furthermore, no flow of the adhesive layer was observed at the ends of the double-sided copper-clad laminate 6.
The obtained double-sided copper-clad laminate 6 and the fluororesin film 6 from which the copper foil was removed were evaluated as follows. The evaluation results are shown in Table 1.

Note that the determination of the evaluation results is as described below.
・Peel strength:
0.7 kN/m or more was rated as ○ (good), and less than 0.7 kN/m was rated as × (unsatisfactory).
・Resin flow:
A case where the maximum amount of resin flowing out from the edge of the double-sided copper-clad laminate was less than 1 mm was rated as ○ (good), and a case where the maximum amount of resin flowing out from the edge of the double-sided copper-clad laminate was 1 mm or more was rated as × (unsatisfactory).
・Void:
A cross-sectional observation using SEM revealed that the void was 5 vol. % is ○ (good), and the void is 5 vol. % or more was marked as × (impossible).
・CTE:
30 ppm/K or less was rated ◎ (excellent), more than 30 ppm/K and less than 60 ppm/K was rated ○ (good), and more than 60 ppm/K was rated × (unsatisfactory).
・Dielectric loss tangent:
Those less than 0.0020 were rated ◎ (excellent), those greater than 0.0020 and less than 0.0025 were rated ○ (good), and those greater than 0.0025 were rated × (unsatisfactory).

<Example 2>
A single-sided copper-clad laminate 9 was produced in the same manner as in Example 1, except that polyamic acid solution B was applied as an adhesive layer, and then a double-sided copper-clad laminate 7 was produced by pressing. A fluororesin film 7 was obtained by removing the copper foil of the plate 7. The obtained double-sided copper-clad laminate 7 and fluororesin film 7 were evaluated. The evaluation results are shown in Table 1. Note that the evaluation results were determined in the same manner as in Example 1.

<Example 3>
After producing a single-sided copper-clad laminate 10 in the same manner as in Example 2 except for changing the thickness of the adhesive layer and the inorganic filler-containing fluororesin layer, pressing was performed to produce a double-sided copper-clad laminate 8, A fluororesin film 8 was obtained by removing the copper foil from the double-sided copper-clad laminate 8. The obtained double-sided copper-clad laminate 8 and fluororesin film 8 were evaluated. The evaluation results are shown in Table 1. Note that the evaluation results were determined in the same manner as in Example 1.

<Example 4>
After applying the dispersion composition 4 as an adhesive layer on a copper foil (electrolytic copper foil, thickness: 12 μm, ten-point average roughness Rzjis on the resin layer side: 0.6 μm), at 80° C. for 1 minute, The solvent was removed by heating and drying at 120° C. for 3 minutes. Furthermore, heat treatment was performed at 280°C for 1.5 minutes and at 340°C for 3 minutes.

Next, after coating Dispersion Composition 2 on the adhesive layer as an inorganic filler-containing fluororesin layer, drying treatment was performed at 80° C. for 1 minute and at 120° C. for 3 minutes using a hot air oven. Next, heat treatment was performed at 240° C. for 3 minutes and at 300° C. for 6 minutes to obtain a single-sided copper-clad laminate 11.

Two of the obtained single-sided copper-clad laminates 11 were prepared, and the resin surfaces were put into a batch press machine, heated to 315°C under vacuum, and after reaching 315°C, heated at 8 MPa for 5 minutes. By pressing at a pressure of 100 μm, a double-sided copper-clad laminate 9 with a dielectric layer thickness of 100 μm was obtained.
At this time, the thickness of each adhesive layer was 4 μm, the thickness of the inorganic filler-containing fluororesin layer was 92 μm, and the total thickness of the dielectric layer was 100 μm. Furthermore, no flow of the adhesive layer was observed at the edges of the double-sided copper-clad laminate 9.
The obtained double-sided copper-clad laminate 9 and the fluororesin film 9 from which the copper foil was removed were evaluated. The evaluation results are shown in Table 1. Note that the evaluation results were determined in the same manner as in Example 1.

<Example 5>
After producing the single-sided copper-clad laminate 12 in the same manner as in Example 1, except that the dispersion composition 3-2 was applied as the inorganic filler-containing fluororesin layer and the pressing temperature was 335° C., pressing was performed. A double-sided copper-clad laminate 10 was prepared, and the copper foil of the double-sided copper-clad laminate 10 was removed to obtain a fluororesin film 10. The obtained double-sided copper-clad laminate 10 and fluororesin film 10 were evaluated. The evaluation results are shown in Table 1. Note that the evaluation results were determined in the same manner as in Example 1.

<Comparative example 1>
After applying the fluororesin dispersion (1) as an adhesive layer on a copper foil (electrolytic copper foil, thickness: 12 μm, ten point average roughness Rzjis on the resin layer side: 0.6 μm), the temperature was 80°C. The solvent was removed by heating and drying at 120°C for 1 minute and 3 minutes at 120°C. Furthermore, heat treatment was performed at 240°C for 1.5 minutes and at 300°C for 3 minutes.

Next, after coating the dispersion composition 1-2 on the adhesive layer as a fluororesin layer containing an inorganic filler, drying treatment was performed at 80° C. for 1 minute and at 120° C. for 3 minutes using a hot air oven. Next, heat treatment was performed at 280° C. for 3 minutes and at 340° C. for 6 minutes to obtain a single-sided copper-clad laminate 13.

Two of the obtained single-sided copper-clad laminates 13 were prepared, and the resin surfaces overlapped and put into a batch press, heated to 360°C under vacuum, and after reaching 360°C, heated to 8 MPa for 5 minutes. By pressing at a pressure of 100 μm, a double-sided copper-clad laminate 11 with a dielectric layer thickness of 100 μm was obtained.
At this time, the thickness of each adhesive layer was 4 μm, the thickness of the inorganic filler-containing fluororesin layer was 92 μm, and the total thickness of the dielectric layer was 100 μm. In addition, flow of the adhesive layer was observed at the edges of the double-sided copper-clad laminate 11.
The obtained double-sided copper-clad laminate 11 and the fluororesin film 11 from which the copper foil was removed were evaluated. The evaluation results are shown in Table 2. Note that the evaluation results were determined in the same manner as in Example 1.

<Comparative example 2>
A single-sided copper-clad laminate 14 was produced in the same manner as in Comparative Example 1, except that the pressing temperature was 290°C, and then pressing was performed to produce a double-sided copper-clad laminate 12. A fluororesin film 12 was obtained by removing the copper foil. The obtained double-sided copper-clad laminate 12 and fluororesin film 12 were evaluated. The evaluation results are shown in Table 2. Note that the evaluation results were determined in the same manner as in Example 1.

<Comparative example 3>
After applying the fluororesin dispersion (1) as an adhesive layer on a copper foil (electrolytic copper foil, thickness: 12 μm, ten point average roughness Rzjis on the resin layer side: 0.6 μm), the temperature was 80°C. The solvent was removed by heating and drying at 120°C for 1 minute and 3 minutes at 120°C. Furthermore, heat treatment was performed at 240°C for 1.5 minutes and at 300°C for 3 minutes.

Next, after coating Dispersion Composition 2 on the adhesive layer as an inorganic filler-containing fluororesin layer, drying treatment was performed at 80° C. for 1 minute and at 120° C. for 3 minutes using a hot air oven. Next, heat treatment was performed at 240° C. for 3 minutes and at 300° C. for 6 minutes to obtain a single-sided copper-clad laminate 15.

Two of the obtained single-sided copper-clad laminates 15 were prepared, and the resin surfaces overlapped and put into a batch press, heated to 315°C under vacuum, and after reaching 315°C, heated to 8 MPa for 5 minutes. By pressing at a pressure of 100 μm, a double-sided copper-clad laminate 13 with a dielectric layer thickness of 100 μm was obtained.
At this time, the thickness of each adhesive layer was 4 μm, the thickness of the inorganic filler-containing fluororesin layer was 92 μm, and the total thickness of the dielectric layer was 100 μm. In addition, flow of the adhesive layer was observed at the edges of the double-sided copper-clad laminate 13.
The obtained double-sided copper-clad laminate 13 and the fluororesin film 13 from which the copper foil was removed were evaluated. The evaluation results are shown in Table 2. Note that the evaluation results were determined in the same manner as in Example 1.

<Comparative example 4>
After producing a single-sided copper-clad laminate 16 in the same manner as in Example 2 except for changing the thickness of the adhesive layer and the inorganic filler-containing fluororesin layer, pressing was performed to produce a double-sided copper-clad laminate 14, A fluororesin film 14 was obtained by removing the copper foil from the double-sided copper-clad laminate 14. The obtained double-sided copper-clad laminate 14 and fluororesin film 14 were evaluated. The evaluation results are shown in Table 2. Note that the evaluation results were determined in the same manner as in Example 1.

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

This application claims priority based on Japanese Patent Application No. 2022-060071 filed in Japan on March 31, 2022, and the entire contents of the application are incorporated herein.

10A, 10B...metal layer, 20A, 20B...adhesive layer, 30...inorganic filler-containing fluororesin layer, 31...dispersed composition layer, 40...first laminate, 50...second laminate, 100...metal tension laminate

Claims

a metal layer;
an adhesive layer in direct contact with the metal layer;
an inorganic filler-containing fluororesin layer containing an inorganic filler in the fluororesin, which is laminated directly or indirectly on the adhesive layer;
Equipped with
The adhesive layer and the inorganic filler-containing fluororesin layer have the following a) or b),
a) When the main resin constituting the adhesive layer is a crystalline resin, the melting point Tm1 of the adhesive layer is higher than the melting point Tm2 of the inorganic filler-containing fluororesin layer;
b) When the main resin constituting the adhesive layer is an amorphous resin, the storage elastic modulus E' of the adhesive layer at the melting point Tm2 of the inorganic filler-containing fluororesin layer is 1 x 10 6 Pa or more;
A metal-clad laminate that satisfies any of the following conditions and has a coefficient of thermal expansion (CTE) of the inorganic filler-containing fluororesin layer of 60 ppm/K or less.
The inorganic filler-containing fluororesin layer has a dielectric loss tangent of 0.0025 at 60 GHz as measured by a split cylinder resonator (SCR resonator) after 24 hours of humidity control under constant temperature and humidity conditions of 23° C. and 50% RH. The metal-clad laminate according to claim 1, wherein the metal-clad laminate is less than 1.
The metal-clad laminate according to claim 1, which has a layer structure in which metal layer/adhesive layer/inorganic filler-containing fluororesin layer/adhesive layer/metal layer are laminated in this order.
The metal-clad laminate according to claim 1, wherein the ratio of the thickness of the adhesive layer to the total thickness of the adhesive layer and the inorganic filler-containing fluororesin layer is within the range of 1 to 25%.
A method for manufacturing a metal-clad laminate according to any one of claims 1 to 4, comprising:
preparing a first laminate in which an adhesive layer is laminated on a metal layer;
A second laminate in which the adhesive layer and the dispersion composition layer are laminated on the metal layer is formed by applying a dispersion composition containing an inorganic filler and a fluororesin on the adhesive layer and heat-treating the adhesive layer. a step of forming;
By using two of the second laminates and thermocompression bonding with the dispersion composition layers facing each other, or by using the first laminate and the second laminate, the adhesive layer and the By thermocompression bonding the dispersion composition layers facing each other, a metal-clad laminate having a layer structure in which metal layer/adhesive layer/inorganic filler-containing fluororesin layer/adhesive layer/metal layer is laminated in this order is formed. The process of
A method for manufacturing a metal-clad laminate including.