JP2021170603A - Metal laminated board and circuit board - Google Patents

Abstract

To provide a metal laminated board and a circuit board in which the sufficient thickness of an insulating resin layer is secured and that can cope with high-frequency transmission accompanying high performance of an electronic device.SOLUTION: A double-sided copper-clad laminate 100 includes a resin laminate 18 containing a plurality of polyimide layers, and copper foil layers 11A and 11B laminated on at least one side of the resin laminate. The resin laminate includes a first polyimide layer (thermoplastic polyimide layers 12A, 12B) having an overall thickness in the range of 40 to 400 μm and in contact with the copper foil layer, and a second polyimide layer (non-thermoplastic polyimide laminate 17) directly or indirectly laminated on the first polyimide layer, and an E value which is an index showing dielectric properties calculated on the basis of E=εc×tanδ [here, εc indicates the relative permittivity at 10 GHz, and tan δ indicates the dielectric loss tangent at 10 GHz] is less than 0.01.SELECTED DRAWING: Figure 1

Description

The present invention relates to a metal-clad laminate and a circuit board that can cope with high frequencies associated with miniaturization and high performance of electronic devices.

In recent years, with the progress of miniaturization, weight reduction, and space saving of electronic devices, flexible circuit boards (FPCs) that are thin and lightweight, have flexibility, and have excellent durability even after repeated bending (FPC) ) Is increasing. Since FPC can be mounted three-dimensionally and at high density even in a limited space, its use is expanded to, for example, wiring of electronic devices such as HDDs, DVDs, mobile phones, and smartphones, and parts such as cables and connectors. I'm doing it.

In information processing and information communication, efforts are being made to increase the transmission frequency in order to transmit and process large volumes of information, and circuit board materials are required to reduce transmission loss by lowering the dielectric layer of the insulating resin layer. ing. Therefore, in order to cope with high frequency, an FPC having a liquid crystal polymer having a low dielectric constant and a low dielectric loss tangent as a dielectric layer is used. However, although the liquid crystal polymer has excellent dielectric properties, there is room for improvement in heat resistance and adhesiveness to metal foils. Therefore, polyimide is attracting attention as an insulating resin material having excellent heat resistance and adhesiveness. ..

In order to improve the high frequency transmission characteristics of the circuit board, it has been proposed to use polyimide having improved dielectric properties (for example, Patent Documents 1 to 3).

On the other hand, it has also been proposed to manufacture a double-sided copper-clad laminate having an insulating resin layer thickness of 50 μm or more by laminating the polyimide resin surfaces of two single-sided copper-clad laminates (for example, Patent Document 4, Patent Document 4). 5).

Patent Document 1 Japanese Patent Application Laid-Open No. 2016-193501 Patent Document 2 Japanese Patent Application Laid-Open No. 2016-192530 Patent Document 3 International Publication No. WO2018 / 061727 Patent Document 4 Japanese Patent Application Laid-Open No. 5886027 Patent Document 5 Japanese Patent Application Laid-Open No. 6031396

It is expected that the demand for higher frequencies in circuit boards will increase in the future, and the demand level for high frequency transmission characteristics will become stricter. From this point of view, it is necessary not only to improve the dielectric properties of the insulating resin layer but also to adjust the thickness of the insulating resin layer according to the width of the microstrip line in order to match the characteristic impedance. When adjusting to the width of the microstrip line, it is necessary to have an option to substantially increase the thickness of the insulating resin layer.
For example, when the thickness of the insulating layer is 25 μm and the relative permittivity is 3.5, the width of the microstrip line is 50 μm in order to set the characteristic impedance to 50 Ω, and the line of this width must be processed with high precision. It doesn't become. On the other hand, when the thickness of the insulating layer is 226 μm, the width of the microstrip line having a characteristic impedance of 50 Ω is 500 μm, and the processing accuracy can be remarkably improved.
However, in the examples of Patent Documents 1 to 3, the thickness of the insulating resin layer is about 25 μm, and it has not been studied to thicken the film to a thickness exceeding 50 μm, for example.
On the other hand, in Patent Documents 4 and 5, the correspondence to high-frequency transmission is not considered, and the configuration of polyimide when a thick insulating resin layer is adopted is not considered.

The polyimide film is mainly produced by solution film formation by casting, and it is difficult to produce a thick film due to the production method, or its productivity is extremely inferior.
The polyimide film used for the circuit board is manufactured so that its CTE (coefficient of linear expansion) matches that of copper. That is, the CTE of a completely amorphous polyimide resin is around 100 ppm / K, but when the film is formed, the orientation of the molecular chains is controlled by a stretching step or the like to realize a CTE almost close to copper.
Generally, the CTE (coefficient of linear expansion) of a polyimide film obtained by the casting method has a dependence on the film thickness, and as the thickness increases, the CTE becomes higher and it becomes difficult to match with copper. .. Since the microstrip line used in the high frequency circuit is asymmetric in the thickness direction, there is a concern that a large warp may occur if the CTE of the insulating layer is not matched with the copper foil.

Therefore, when polyimide is used as the insulating resin layer of the thick film, a method of laminating a plurality of polyimide films is used. That is, by laminating a polyimide film having a thickness having a CTE relatively close to copper to increase the thickness, a polyimide layer consistent with the copper foil can be realized even if it is thick. However, if the adhesive layer used for adhering the polyimides to each other is thick, or if the material has a higher water absorption than the polyimide film, the required dielectric properties cannot be obtained. Further, since the resin having an adhesive function is generally amorphous and has a high CTE, if the thickness of the adhesive layer is large, the CTE of the entire laminated body obtained will be high.

The present invention provides a metal-clad laminate and a circuit board that solve the above problems, ensure a sufficient thickness of the insulating resin layer, and support high-frequency transmission accompanying higher performance of electronic devices. There is.

The present inventors have found that the above problems can be solved by providing an insulating resin layer having a large thickness and making the adhesive layer between the metal and polyimide or the polyimides extremely thin, and complete the present invention. I arrived.

That is, the present invention has the following configuration.
[1] A metal-clad laminate comprising a resin laminate containing a plurality of polyimide layers and a metal layer laminated on at least one surface of the resin laminate, wherein the resin laminate is the following i) to iii. ) Condition;
i) The total thickness is in the range of 40-400 μm;
ii) Includes a first polyimide layer in contact with the metal layer and a second polyimide layer directly or indirectly laminated on the first polyimide layer;
iii) The following formula (a)
E = ε _c × tan δ ・ ・ ・ (a)
[Here, ε _c indicates the relative permittivity at 10 GHz, and tan δ indicates the dielectric loss tangent at 10 GHz. ]
The E value, which is the dielectric loss coefficient calculated based on, is less than 0.01;
A metal-clad laminate characterized by satisfying.
[2] The resin laminate has a structure in which at least the first polyimide layer and the second polyimide layer are laminated in this order from the metal layer side, respectively. Metal-plated laminate.
[3] The resin laminate is characterized in that the thickness of the adhesive layer between the metal layer and the first polyimide layer and between the first polyimide layer and the second polyimide layer is 100 nm or less [2]. ] The metal-clad laminate described in.
[4] A circuit board obtained by processing the metal layer of the metal-clad laminate according to any one of [1] to [3] in a wiring circuit.

The present invention can further include the following configurations.
[5] The above-mentioned [1] to [3], wherein the second polyimide layer contains 70% or more of a polyimide layer using biphenyltetracarboxylic acid as a raw material in a thickness ratio. Metal-plated laminate.
[6] The metal-clad laminate according to the above [3], wherein the adhesive layer is a condensate of a silane coupling agent.
[7] A metal-pasted laminated plate characterized in that when the second polyimide layer is laminated, the moisture absorption rate of each polyimide layer (polyimide film) is controlled to be 0.3% or less and laminated. Production method.

Since the metal-clad laminate of the present invention has a resin laminate having a sufficient thickness, a CTE consistent with a copper foil, and excellent dielectric properties, it is an electronic material that requires high-speed signal transmission. Can be suitably used as.

It is a schematic cross-sectional view which shows the structure of the double-sided copper laminated board (double-sided CCL) which concerns on one Embodiment of this invention. It is a drawing explaining one step of the manufacturing method of the double-sided CCL shown in FIG. FIG. 3 is a schematic view showing an example of the silane coupling agent coating device of the present invention. FIG. 4 is a schematic view showing an example of the non-thermoplastic polyimide laminate manufacturing apparatus of the present invention. FIG. 5 is a schematic view showing an example of the laminate manufacturing apparatus of the present invention.

Hereinafter, embodiments of the present invention will be described.

<Metal-clad laminate>
The metal-clad laminate of the present embodiment includes a resin laminate including a plurality of polyimide layers, and a metal layer laminated on at least one surface of the resin laminate.

<Resin laminate>
The resin laminate satisfies the following conditions i) to iii).

i) The total thickness of the resin laminate is in the range of 40 to 400 μm, preferably in the range of 45 to 350 μm, and more preferably in the range of 50 to 350 μm. If the total thickness of the resin laminate is less than 40 μm, sufficient high-frequency transmission characteristics may not be obtained, and if it exceeds 300 μm, problems such as warpage may occur. Further, since problems may occur in dimensional stability, flexibility, etc., the total thickness of the resin layer is preferably 200 μm or less.

ii) The resin laminate includes at least a first polyimide layer in contact with the metal layer and a second polyimide layer directly or indirectly laminated on the first polyimide layer. The polyimide constituting the first polyimide layer is preferably a thermoplastic polyimide, and the polyimide constituting the second polyimide layer is preferably a non-thermoplastic polyimide. It is preferable that the resin laminate has a structure in which at least the first polyimide layer and the second polyimide layer are laminated in this order from the metal layer side, respectively. The resin laminate may have an arbitrary resin layer other than the first polyimide layer and the second polyimide layer. Further, the resin laminate preferably has a layer structure symmetrical in the thickness direction with respect to the center in the thickness direction, but may have a layer structure asymmetrical in the thickness direction.

iii) The resin laminate is described in the following mathematical formula (a),
E = ε _c × tan δ ・ ・ ・ (a)
[Here, ε _c indicates the relative permittivity at 10 GHz, and tan δ indicates the dielectric loss tangent at 10 GHz. ] Is calculated. The E value, which is the dielectric loss coefficient, is less than 0.01, preferably 0.0095 or less, and more preferably 0.009 or less. Further, it is preferably 0.0025 or more, and more preferably 0.003 or more. When the E value is less than 0.01, a circuit board such as an FPC having excellent high frequency transmission characteristics can be manufactured. On the other hand, if the E value exceeds the above upper limit, inconveniences such as loss of electric signals are likely to occur on the transmission path of high frequency signals when used for a circuit board such as FPC.

Further, the resin laminate should control the CTE within the range of 10 to 35 ppm / K as a whole of the resin laminate from the viewpoint of suppressing warpage and deterioration of dimensional stability when the metal-clad laminate is formed. It is preferable to control the temperature in the range of 12 to 22 ppm / K, and further preferably in the range of 14 to 19 ppm / K. In this case, the CTE of the second polyimide layer that functions as the base layer (main layer) in the resin laminate is preferably in the range of 1 to 30 ppm / K, more preferably 5 to 25 ppm / K, and further preferably 10 to 10. The range of 20 ppm / K is good.

<First polyimide layer>
The polyimide constituting the first polyimide layer is preferably a thermoplastic polyimide. The thermoplastic polyimide preferably has a glass transition temperature (Tg) of 360 ° C. or lower, more preferably in the range of 200 to 320 ° C. Here, the thermoplastic polyimide is generally a polyimide in which the glass transition temperature (Tg) can be clearly confirmed, but in the present invention, it is measured at 30 ° C. using a dynamic viscoelasticity measuring device (DMA). A polyimide having a storage elastic modulus of 1.0 × 10 ⁹ Pa or more and a storage elastic modulus of ^{less than 3.0 × 10 8 Pa at 300 ° C.} The resin laminate has one or two first polyimide layers adjacent to the one or two metal layers, respectively. When having two first polyimide layers, the constituent polyimides may be of the same type or different types.

The thermoplastic polyimide constituting the first polyimide layer (thermoplastic polyimide layer) contains a tetracarboxylic acid residue and a diamine residue, and is derived from an aromatic tetracarboxylic acid dianhydride. It preferably contains an acid residue and an aromatic diamine residue derived from the aromatic diamine.

When the first polyimide layer is a thermoplastic polyimide layer, the tetracarboxylic acid component constituting the thermoplastic polyimide layer is not particularly limited, and for example, pyrolimetic acid dianhydride, 3,3', 4,4'-. Biphenyltetracarboxylic acid dianhydride and the like can be mentioned. The diamine component is not particularly limited, and is, for example, 2,2'-diaminobiphenyl, 3,3'-diaminobiphenyl, 4,4'-diaminobiphenyl, 2,2'-dimethyl-4,4'-. Examples thereof include diaminobiphenyl, 1,3-bis (2-aminophenoxy) benzene, 1,3-bis (3-aminophenoxy) benzene, and 1,3-bis (4-aminophenoxy) benzene.

Thermal expansion coefficient by selecting the types of the tetracarboxylic acid residue and diamine residue and the molar ratio of each when two or more types of tetracarboxylic acid residue or diamine residue are applied to the thermoplastic polyimide. , Tensile elasticity, glass transition temperature, etc. can be controlled. Further, in the thermoplastic polyimide, when a plurality of structural units of polyimide are present, it may exist as a block or randomly, but it is preferable that it exists randomly.

By using both the tetracarboxylic acid residue and the diamine residue contained in the thermoplastic polyimide as aromatic groups, the dimensional accuracy of the polyimide film in a high temperature environment can be improved, and in-plane retardation (RO) can be used. The amount of change can be suppressed.

The imide group concentration of the thermoplastic polyimide is preferably 33% by mass or less. Here, the "imide group concentration" means a value obtained by dividing the molecular weight of the imide base portion (-(CO) ₂ -N-) in the polyimide by the molecular weight of the entire structure of the polyimide. When the imide group concentration exceeds 33% by mass, the molecular weight of the resin itself becomes small, and the decrease in hygroscopicity may be deteriorated due to the increase in polar groups. By controlling the orientation of the molecules in the thermoplastic polyimide by selecting the combination of the above diamine compounds, the increase in CTE accompanying the decrease in the imide group concentration is suppressed, and low hygroscopicity is ensured.

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

Since the thermoplastic polyimide constituting the thermoplastic polyimide layer is, for example, an adhesive layer in the insulating resin of the circuit board, a completely imidized structure is most preferable in order to suppress the diffusion of copper. However, a part of the polyimide may be amic acid. ^{The imidization rate is around 1015 cm -1} by measuring the infrared absorption spectrum of the polyimide thin film by the single reflection ATR method using a Fourier transform infrared spectrophotometer (commercially available: FT / IR620 manufactured by JASCO Corporation). It is calculated from the absorbance of C = O expansion and contraction derived from the imide group of ^{1780 cm -1} based on the benzene ring absorber of.

<Second polyimide layer>
The polyimide constituting the second polyimide layer is preferably a low thermal expansion non-thermoplastic polyimide. When a plurality of second polyimide layers are provided, the polyimides constituting each layer may be of the same type or different types. Here, the non-thermoplastic polyimide is generally a polyimide that does not soften or show adhesiveness even when heated, but in the present invention, it is measured at 30 ° C. using a dynamic viscoelasticity measuring device (DMA). A polyimide having a storage elastic modulus of 1.0 × 10 ⁹ Pa or more and a storage elastic modulus of 3.0 × 10 ⁸ Pa or more at 300 ° C.

The details of the non-thermoplastic polyimide film will be described below. Generally, a polyimide-based resin film is a green film (hereinafter referred to as a green film) in which a polyamic acid (polyimide precursor) solution obtained by reacting diamines and tetracarboxylic acids in a solvent is applied to a support for producing a polyimide film and dried. It is also referred to as "polyamic acid film"), and is obtained by subjecting a green film to a high-temperature heat treatment to carry out a dehydration ring-closing reaction on a support for producing a polyimide film or in a state of being peeled off from the support.

The application of the polyamic acid (polyimide precursor) solution is, for example, application of a conventionally known solution such as spin coating, doctor blade, applicator, comma coater, screen printing method, slit coating, reverse coating, dip coating, curtain coating, slit die coating and the like. Means can be used as appropriate.

The diamines constituting the polyamic acid are not particularly limited, and aromatic diamines, aliphatic diamines, alicyclic diamines and the like usually used for polyimide synthesis can be used. From the viewpoint of heat resistance, aromatic diamines are preferable. The diamines may be used alone or in combination of two or more.

The diamines are not particularly limited, and examples thereof include oxydianiline (bis (4-aminophenyl) ether, para-phenylenediamine (1,4-phenylenediamine)) and the like.

Examples of the tetracarboxylic acids constituting the polyamic acid include aromatic tetracarboxylic acids (including the acid anhydride thereof), aliphatic tetracarboxylic acids (including the acid anhydride) and alicyclic tetracarboxylic acids usually used for polyimide synthesis. Acids (including its acid anhydride) can be used. When these are acid anhydrides, the number of anhydride structures in the molecule may be one or two, but those having two anhydride structures (dianhydride) are preferable. good. The tetracarboxylic acids may be used alone or in combination of two or more.

The tetracarboxylic acid is not particularly limited, and examples thereof include pyrolimetic acid dianhydride and 3,3', 4,4'-biphenyltetracarboxylic dianhydride.

It is preferable that the polyimide used for the first and second polyimide layers used in the present invention is subjected to a surface activation treatment. By the surface activation treatment, the polyimide surface is modified to a state in which functional groups are present (so-called activated state), and the affinity with the adhesive layer is improved.
The surface activation treatment in the present invention is a dry or wet surface treatment. As the dry treatment of the present invention, a treatment of irradiating the surface with active energy rays such as ultraviolet rays, electron beams, and X-rays, a corona treatment, a vacuum plasma treatment, a normal pressure plasma treatment, a flame treatment, an itro treatment, and the like can be used. .. As the wet treatment, a treatment in which the film surface is brought into contact with an acid or alkaline solution can be exemplified. The surface activation treatment preferably used in the present invention is a plasma treatment, which is a combination of a plasma treatment and a wet acid treatment.

The plasma treatment is not particularly limited, but includes RF plasma treatment in vacuum, microwave plasma treatment, microwave ECR plasma treatment, atmospheric pressure plasma treatment, corona treatment, etc., and gas treatment containing fluorine and ions. It also includes ion implantation treatment using a source, treatment using the PBII method, flame treatment exposed to thermal plasma, and itro treatment. Among these, RF plasma treatment in vacuum, microwave plasma treatment, and atmospheric pressure plasma treatment are preferable.

Suitable conditions for plasma treatment include oxygen plasma, plasma _{containing fluorine such as CF 4} , C ₂ F ₆ , and other plasmas known to have a high chemical etching effect, or Ne, Ar, Kr, Xe, and plasma. As described above, it is desirable to perform treatment with plasma, which has a high effect of physically etching by applying physical energy to the surface of the polymer. It is _{also preferable to add plasma such as CO 2} , CO, H ₂ , N ₂ , NH ₄ , CH ₄ and a mixed gas thereof, and further water vapor. In addition to these, OH, N ₂ , N, CO, CO ₂ , H, H ₂ , O ₂ , NH, NH ₂ , NH ₃ , COOH, NO, NO ₂ , He, Ne, Ar, Kr, Xe, CH _At least selected from the group consisting of 2 O, Si (OCH ₃ ) ₄ , Si (OC ₂ H ₅ ) ₄ , C ₃ H ₇ Si (OCH ₃ ) ₃ , and C ₃ H ₇ Si (OC ₂ H ₅ ) _3. It is preferable to prepare a plasma containing one or more components as a gas or as a decomposition product in the plasma. When aiming for processing in a short time, plasma with high energy density, high kinetic energy of ions in plasma, and plasma with high number density of active species are desirable, but energy is required because surface smoothness is required. There is a limit to increasing the density. When oxygen plasma is used, surface oxidation progresses, which is good in terms of forming OH groups, but it is easy to form a surface that already has poor adhesion to the film itself, and the surface roughness (roughness) increases. Adhesion also deteriorates.
Further, in plasma using Ar gas, the influence of purely physical collision occurs on the surface, and in this case as well, the surface roughness becomes large. Considering all of these, microwave plasma treatment, microwave ECR plasma treatment, plasma irradiation with an ion source that can easily shoot high-energy ions, PBII method, and the like are also desirable.

Such surface activation treatment cleans the polyimide surface and produces more active functional groups. The generated functional group is bonded to the adhesive layer by a hydrogen bond or a chemical reaction, and the polyimide and the adhesive layer can be firmly adhered to each other.
In the plasma treatment, the effect of etching the polyimide surface can also be obtained. In particular, in a polyimide containing a relatively large amount of lubricant particles, protrusions due to the lubricant may hinder the adhesion between the polyimides. In this case, it is possible to remove the lubricant particles in the vicinity of the polyimide surface by thinly etching the polyimide surface by plasma treatment to expose a part of the lubricant particles and then performing the treatment with hydrofluoric acid.

The surface activation treatment may be applied to all the polyimides, or may be applied to some of the polyimides constituting the resin laminate. Further, it may be applied to only one side of each polyimide film, or may be applied to both sides. When plasma treatment is performed on one side, the polyimide film is placed in contact with the electrode on one side in the plasma treatment with the parallel plate type electrode, so that the plasma treatment is performed only on the side of the porimido film that is not in contact with the electrode. be able to. Further, if the polyimide film is placed in a state of being electrically floated in the space between the two electrodes, plasma treatment can be performed on both sides. Further, one-sided treatment is possible by performing plasma treatment with a protective film attached to one side of the polyimide film. As the protective film, a PET film with an adhesive, an olefin film, or the like can be used.

The first polyimide film and the second polyimide film may be collectively referred to as a polyimide film. Further, the first polyimide layer and the second polyimide layer may be collectively referred to as a polyimide layer.

The hygroscopicity of the polyimide film is preferably 1% or less, more preferably 0.5% or less, still more preferably 0.3% or less, still more preferably 0.2% or less. It is more preferably 0.18% or less, particularly preferably 0.15% or less, and most preferably 0.13% or less. The lower limit is not particularly limited, but industrially, it may be 0.01% or more, or 0.05% or more. When the second polyimide film is composed of a plurality of layers, the hygroscopicity of at least one layer is preferably 0.2% or less, more preferably 0.18% or less, and further preferably 0.18% or less. Is 0.15% or less, and particularly preferably 0.13% or less. By suppressing the hygroscopicity of the polyimide film to be low in this way, the dielectric loss coefficient (E value) of the metal-coated laminate of the present invention can be suppressed to less than 0.01.

The moisture absorption rate of the polyimide film tends to decrease when the polarity of the polyimide is lowered or the number of hydrophobic structural units such as a benzene ring is increased in the structural unit of the polyimide. The number of hydrophilic structural units in the above tends to increase.

The viscosity of the polyamic acid solution of the thermoplastic polyimide is preferably in the range of 700 mPa · s to 50,000 mPa · s. If the viscosity is outside the range of 700 mPa · s to 50,000 mP · a, it is difficult to coat the metal layer, especially with RtoR.

The CTE (coefficient of linear expansion) of the first polyimide layer is preferably in the range of 10 ppm / K to 70 ppm / K, and more preferably 10 ppm / K to 60 ppm / K. The CTE of the polyimide film constituting the second polyimide layer is preferably 0 ppm / K to 30 ppm / K, and more preferably 10 ppm / K to 20 ppm / K. If the CTE difference between the first and second polyimide layers is large, it may cause warpage. Therefore, it is preferable that the CTE difference between the first and second polyimide layers is small.

<Metal layer>
As the metal layer, a metal foil can be preferably used. The material of the metal foil is not particularly limited, but for example, copper, stainless steel, iron, nickel, beryllium, aluminum, zinc, indium, silver, gold, tin, zirconium, tantalum, titanium, lead, magnesium, manganese and alloys thereof. And so on. Among these, copper or a copper alloy is particularly preferable. The copper foil may be rolled copper foil or electrolytic copper foil.

The surface of the metal foil used as the metal layer may be subjected to surface treatment such as rust prevention treatment, siding, aluminum alcoholate, aluminum chelate, and silane coupling agent.

In the metal-clad laminate of the present embodiment, for example, the thickness of the metal layer when used for manufacturing FPC is in the range of 3 to 50 μm, more preferably in the range of 5 to 30 μm, but the circuit pattern. The range of 5 to 20 μm is most preferable in order to thin the line width of. The thickness of the metal layer is preferably thick from the viewpoint of suppressing an increase in conductor loss in high-frequency transmission, but on the other hand, if the thickness becomes too large, it becomes difficult to apply it to miniaturization and the flexibility decreases. There is a risk that the adhesiveness between the wiring layer and the insulating resin layer will be impaired when the circuit is processed. In consideration of such a trade-off relationship, the thickness of the metal layer may be within the above range.

Further, from the viewpoint of achieving both high frequency transmission characteristics and adhesiveness to the resin laminate, the ten-point average roughness (Rz) of the surface of the metal layer in contact with the first polyimide layer is 1.2 μm or less, which is 0. It is preferably in the range of 05 to 1.0 μm. From the same viewpoint, the arithmetic mean height (Ra) of the surface of the metal layer in contact with the first polyimide layer is preferably 0.2 μm or less.

In the metal-clad laminate of the present embodiment, a commercially available copper foil can be used as the metal layer. Specific examples thereof include copper foil CF-T49A-DS-HD (trade name) manufactured by Fukuda Metal Foil Powder Industry Co., Ltd., copper foil TQ-M4-VSP (trade name) manufactured by Mitsui Metal Mining Co., Ltd., and JX Metal Co., Ltd. Examples thereof include copper foil GHY5-HA-V2 (trade name) and BHY (X) -HA-V2 (trade name) manufactured by the same company.

Next, the structure of the metal-clad laminate of the present embodiment will be specifically described with reference to the drawings. FIG. 1 is a schematic cross-sectional view showing the configuration of a double-sided copper-clad laminate (double-sided CCL) 100 according to an embodiment of the present invention. The double-sided CCL100 includes copper foil layers 11A and 11B as metal layers and a resin laminate 18 as a resin laminate, and has a structure in which copper foil layers 11A and 11B are laminated on both sides of the resin laminate 18. doing. Here, the resin laminate 18 is composed of a plurality of polyimide layers, and the thermoplastic polyimide layers 12A and 12B as the first polyimide layer and the non-thermoplastic polyimide laminate 17 as the second polyimide layer, non-thermal. The non-thermoplastic polyimide layers 13A, 13B, 15A, 15B constituting the plastic polyimide laminate 17, and 14A, 14B, 16 as adhesive layers are provided.

In the double-sided CCL100, the thermoplastic polyimide layers 12A and 12B are in contact with the copper foil layers 11A and 11B, respectively. The thermoplastic polyimide layer 12A and the thermoplastic polyimide layer 12B may have the same thickness or different thicknesses, and the polyimides constituting them may be of the same type or different types.

Further, in the double-sided CCL100, the non-thermoplastic polyimide layer 17 may be in contact with the thermoplastic polyimide layers 12A and 12B, but may not be in direct contact with the thermoplastic polyimide layer 12B, but may be indirectly laminated. The polyimide layers 13A, 13B, 15A, 15B, and 16 constituting the non-thermoplastic polyimide layer 17 may be of the same type or different types.

Further, in the double-sided CCL100, the thermoplastic polyimide layers 12A and 12B are made of thermoplastic polyimide having a glass transition temperature (Tg) of 360 ° C. or lower, for example, 200 to 320 ° C. in order to ensure adhesiveness. Is preferable.

The resin laminate 100 is not limited to the six-layer structure as shown in FIG. The resin laminate 100 is directly or indirectly attached to at least the thermoplastic polyimide layers 12A and 12B (first polyimide layers) in contact with the copper foil layers 11A and 11B and the thermoplastic polyimide layers 12A and 12B, respectively. The laminated non-thermoplastic polyimide layers 13A and 13B (second polyimide layer) may be included. For example, in the case of double-sided CCL, the structure may be such that the thermoplastic polyimides 12A and 12A sandwich one layer of non-thermoplastic polyimide (second polyimide layer). Further, the resin laminate 100 may include any layer other than those shown in FIG. The resin laminate 100 may include a resin layer other than the polyimide layer, but it is preferably composed of only a plurality of polyimide layers.

The polyimide layer constituting the resin laminate 18 may contain an inorganic filler, if necessary. Specific examples thereof include silicon dioxide, aluminum oxide, magnesium oxide, beryllium oxide, boron nitride, aluminum nitride, silicon nitride, aluminum fluoride and calcium fluoride. These can be used alone or in admixture of two or more.

The copper foil layers 11A and 11B may be copper foils having the same thickness and material, or copper foils having different configurations.

It is preferable that the adhesive layer is substantially not contained between the metal layer and the first polyimide layer. When the adhesive layer is not substantially contained, the film thickness is preferably 100 nm or less, more preferably 80 nm or less, further preferably 50 nm or less, still more preferably 30 nm or less, and particularly preferably 30 nm or less. It is 10 nm or less, most preferably 0 nm. The film thickness of the adhesive layer can be obtained by ellipsometry or by calculating from the concentration of the adhesive solution at the time of coating and the coating amount. Examples of the component of the adhesive layer include a silane coupling agent or a diamine described later.

It is preferable that the adhesive layer is substantially not contained between the first polyimide layer and the second polyimide layer. When the adhesive layer is not substantially contained, the film thickness is preferably 100 nm or less, more preferably 80 nm or less, further preferably 50 nm or less, still more preferably 30 nm or less, and particularly preferably 30 nm or less. It is 10 nm or less, most preferably 0 nm. Examples of the component of the adhesive layer include a silane coupling agent or a diamine described later.

<Manufacturing method of metal-clad laminate>
The double-sided CCL100 is preferably produced, for example, by the method shown below.
First, two single-sided copper-clad laminates (single-sided CCL) are prepared. That is, a single-sided copper-clad laminate having a copper foil layer 21A and a thermoplastic polyimide layer 22A (single-sided CCL) and a single-sided copper-clad laminate having a copper foil layer 21B and a thermoplastic polyimide layer 22B (single-sided CCL) are produced. In addition, the non-thermoplastic polyimide layer 27 is produced.

Next, as shown in FIG. 2, the thermoplastic polyimide layers 22A and 22B of the two single-sided CCL200 and 210 are arranged so as to face each other so as to sandwich the non-thermoplastic polyimide layer 27, and thermocompression bonding is performed by a hot press. Double-sided CCL100 can be manufactured. The two single-sided CCLs 200 and 210 may have exactly the same configuration, or may have different numbers of layers, resin types, metal layers, and the like.

For each of the polyimide layers constituting the single-sided CCL200 and 210, a resin solution of polyamic acid, which is a precursor of polyimide, is placed on the copper foil, which is a raw material of the copper foil layers 21A and 21B, because of the ease of controlling the thickness and physical properties. After coating and forming a coating film, it is preferably formed by a so-called cast (coating) method in which the coating is dried and cured by heat treatment. That is, in the single-sided CCL200 and 210, the thermoplastic polyimide layers 22A and 222B laminated on the copper foil layers 21A and 21B are preferably sequentially formed by the casting method.

In the casting method, the coating film can be formed by applying a resin solution of polyamic acid on a copper foil and then drying it. In the formation of the single-sided CCL200, 210, another polyamic acid solution having different constituent components can be sequentially applied onto the polyamic acid solution to form the single-sided CCL200, 210, or the polyamic acid solution having the same composition can be formed twice. The above may be applied. Further, a plurality of coating films may be laminated and formed at the same time by multi-layer extrusion. It is also possible to imidize the coating film of polyamic acid once to form a single-layer or a plurality of polyimide layers, and then further coat a resin solution of polyamic acid on the imidized film to form a polyimide layer. .. The method of application is not particularly limited, and for example, it can be applied with a coater such as a comma, a die, a knife, or a lip. In this case, the copper foil may have a shape such as a cut sheet, a roll, or an endless belt. In order to obtain productivity, it is efficient to use a roll-shaped or endless belt-shaped form so that continuous production is possible. Further, from the viewpoint of further exerting the effect of improving the wiring pattern accuracy on the circuit board, the copper foil is preferably in the form of a long roll.

The imidization method is not particularly limited, and for example, a heat treatment such as heating for a time in the range of 1 to 60 minutes under a temperature condition in the range of 80 to 400 ° C. is preferably adopted. In order to suppress the oxidation of the copper foil layers 21A and 22B, heat treatment in a low oxygen atmosphere is preferable, specifically, in an atmosphere of an inert gas such as nitrogen or a rare gas, an atmosphere of a reducing gas such as hydrogen, or a vacuum. It is preferable to do it inside. By the heat treatment, the polyamic acid in the coating film is imidized to form a polyimide.

As described above, single-sided CCL200, 210 having a plurality of polyimide layers and a copper foil layer 21A or 22B can be manufactured. As shown in FIG. 2, the two single-sided CCLs 200 and 210 thus obtained are arranged so that the surfaces of the thermoplastic polyimide layers 22A and 22B face each other, and are thermocompression bonded to the non-thermoplastic polyimide layer 27. Thereby, the double-sided CCL100 can be manufactured. Thermocompression bonding is preferably carried out by forming two single-sided CCL200, 210 and a non-thermoplastic polyimide layer 27 in a long length and transporting them by a roll-to-roll method using a pair of heating rolls. From the viewpoint of the transportability and bondability of the single-sided CCL, it is more preferable to carry out the transport speed between the heating rolls within the range of 1 to 10 m / min.

<Manufacturing method of the second polyimide layer (non-thermoplastic polyimide layer)>
In the metal-clad laminate of the present embodiment, when the second polyimide layer is composed of a plurality of non-thermoplastic polyimide layers, a silane coupling agent or a diamine is preferably used in order to bond the non-thermoplastic polyimides to each other. can.

The silane coupling agent has a function of physically or chemically interposing and adhering between the non-thermoplastic polyimides constituting the second polyimide layer, and the adhesive layer is a condensate layer of the silane coupling agent ( Hereinafter, it is also referred to as a silane coupling agent condensate layer or a silane coupling agent layer).
The silane coupling agent used in the present embodiment is not particularly limited, but preferably contains a coupling agent having an amino group.
Preferred specific examples of the silane coupling agent include N-2- (aminoethyl) -3-aminopropylmethyldimethoxysilane, N-2- (aminoethyl) -3-aminopropyltrimethoxysilane, and N-2-. (Aminoethyl) -3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-triethoxysilyl-N- (1,3-dimethyl-butylidene) propylamine, N −Phenyl-3-aminopropyltrimethoxysilane, N- (vinylbenzyl) -2-aminoethyl-3-aminopropyltrimethoxysilane hydrochloride, aminophenyltrimethoxysilane, aminophenetiltrimethoxysilane, aminophenylaminomethylphenethyl Examples thereof include trimethoxysilane.

Among the silane coupling agents, a silane coupling agent having one silicon atom in one molecule is particularly preferable, and for example, N-2- (aminoethyl) -3-aminopropylmethyldimethoxysilane, N- 2- (Aminoethyl) -3-aminopropyltrimethoxysilane, N-2- (Aminoethyl) -3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3- Examples thereof include triethoxysilyl-N- (1,3-dimethyl-butylidene) propylamine, aminophenyltrimethoxysilane, aminophenyl trimethoxysilane, aminophenylaminomethylphenetyl trimethoxysilane and the like. When particularly high heat resistance is required in the process, it is desirable to connect Si and an amino group with an aromatic group.

Further, another coupling agent can be used together with the silane coupling agent. Examples of the coupling agent include 11-amino-1-undecenothiol and the like.

In the metal-clad laminate of the present embodiment, diamine can be used as the reactive liquid together with the silane coupling agent. The diamine compound can be used alone or in a combination of a plurality of types. It can also be used as a solution of alcohol, water and various solvents. Further, the diamine in solution may be mixed with a reactive liquid other than diamine.

Examples of the diamine that can be used in the present invention include 1,4-butanediamine, 1,5-pentanediamine, 1,6-hexanediamine, 1,7-heptandiamine, 1,8-octanediamine, and 1,9-. Nonandiamine, 1,10-decanediamine, 1,2-hexanediamine, 1,3-hexanediamine, 1,4-hexanediamine, 1,5-hexanediamine, 1,2-pentanediamine, 1,3-pentanediamine , 1,4-pentanediamine and the like.

<Application of silane coupling agent to the second polyimide layer>
As a method of applying the silane coupling agent to the second polyimide film, a method of applying the silane coupling agent solution to the polyimide layer, a vapor deposition method, or the like can be used. The application of the silane coupling agent can be performed using, for example, the apparatus shown in FIGS. 3 and 4.

In the apparatus of FIG. 3, the silane coupling agent 35 is heated by the water bath 34, and the silane coupling agent vapor generated by sending nitrogen gas through the container can be introduced into the processing chamber 33. With this steam, the silane coupling agent can be applied to the surface of the non-thermoplastic polyimide film 32 fixed to the square frame 31.

The apparatus of FIG. 4 has unwinding portions 41 and 45 of a long non-thermoplastic polyimide film, a processing chamber, a laminator 46, and a winding portion of a long non-thermoplastic polyimide film bonded together. The non-thermoplastic polyimide film unwound from the long non-thermoplastic polyimide film unwinding section 41 is a silane coupling solution supplied from the silane coupling agent liquid supply section 42 using the wire bar 44 in the processing chamber. Is applied and laminated with a non-thermoplastic polyimide film unwound from a long non-thermoplastic polyimide film unwinding portion 45 using a laminator 46.

As a method of applying the silane coupling agent solution, a curtain coating method, a dip coating method, a slit die coating method, a gravure coating method, a bar coating method, and a comma are used by using a solution obtained by diluting the silane coupling agent with a solvent such as alcohol. Conventionally known solution coating means (conventional coating device) such as a coating method, an applicator method, a screen printing method, and a spray coating method can be appropriately used.

Further, the silane coupling agent layer can be formed by a vapor deposition method, and specifically, the polyimide film is formed by exposing the polyimide film to the vapor of the silane coupling agent, that is, the silane coupling agent in a substantially gaseous state. The vapor of the silane coupling agent can be obtained by heating the liquid silane coupling agent to a temperature from 40 ° C. to about the boiling point of the silane coupling agent. The boiling point of the silane coupling agent varies depending on the chemical structure, but is generally in the range of 100 to 250 ° C. However, heating at 200 ° C. or higher is not preferable because it may cause a side reaction on the organic group side of the silane coupling agent.
The environment for heating the silane coupling agent may be any of pressure, normal pressure, and reduced pressure, but in the case of promoting vaporization of the silane coupling agent, normal pressure or reduced pressure is preferable. Since many silane coupling agents are flammable liquids, it is preferable to carry out the vaporization work in a closed container, preferably after replacing the inside of the container with an inert gas.
The time for exposing the polyimide film to the silane coupling agent is not particularly limited, but is preferably 20 hours or less, more preferably 60 minutes or less, still more preferably 15 minutes or less, and most preferably 1 minute or less.
The temperature of the polyimide film during exposure of the polyimide film to the silane coupling agent is an appropriate temperature between -50 ° C and 200 ° C depending on the type of the silane coupling agent and the desired thickness of the silane coupling agent layer. It is preferable to control to.

The thickness of the silane coupling agent layer (adhesive layer) is extremely thin compared to a polyimide film or the like, and is a thickness that can be ignored from the viewpoint of mechanical design. A thickness on the order of the molecular layer is sufficient. The film thickness of the silane coupling agent layer is preferably 5 nm or more. Since the silane coupling agent layer is not clustered and forms a more uniform coating film, it is more preferably 10 nm or more, further preferably 20 nm or more, and particularly preferably 30 nm or more. Further, it is preferably 300 nm or less. Since the mechanical properties of the silane coupling agent layer itself can be ignored, it is more preferably 100 nm or less, further preferably 80 nm or less, and particularly preferably 50 nm or less. The film thickness of the silane coupling agent layer can be calculated from the ellipsometry method or the concentration of the silane coupling agent solution at the time of coating and the coating amount.

As the solution for diluting the silane coupling agent, water or a mixed medium of water and a water-soluble solvent can be used. Lower alcohol, low molecular weight ketone, tetrahydrofuran and the like can be used as the water-soluble solvent, and preferably used aqueous mediums are pure water, a mixed solvent of water and methanol, a mixed solvent of water and ethanol, water, isopropanol and methyl ethyl ketone. , A mixed solvent of water and tetrahydrofuran, and the like. An aqueous medium particularly preferably used in the present invention is water, a monohydric alcohol, a dihydric alcohol, or a trihydric alcohol that is liquid at room temperature, or a mixture having two or more components thereof. Further, a trace amount of surfactant may be added to the aqueous medium in order to improve the wettability between the aqueous medium and the polyimide film.

The silane coupling agent may be applied to the polyimide film on one side or both sides.

<Lamination of non-thermoplastic polyimide film>

As a method for laminating the non-thermoplastic polyimide film, a roll laminator method capable of continuously laminating is preferable. For example, press, laminating, or roll laminating can be used to pressurize a surface or line in an atmospheric pressure atmosphere or in a vacuum. The process can also be accelerated by heating during pressurization.

The pressing pressure at the time of laminating is preferably 0.2 MPa or more. By pressurizing at a pressure of 0.2 MPa or more, unevenness during laminating and air entrapment between the bonded heat-resistant polymer films can be suppressed. The lower limit of the pressing pressure is not particularly limited, but is preferably 0.5 MPa or more. When it is 0.5 MPa or more, it is possible to prevent a portion that does not adhere to each other and insufficient adhesion.

Of the upper and lower rolls used for laminating, it is desirable that at least one side is a roll made of a flexible material. The roll made of a flexible material referred to here refers to a silicon rubber roll having an elastic modulus of 300 MPa or less. If at least one of the rolls used for laminating is made of a flexible material, a high-quality non-thermoplastic polyimide laminate with less air bubbles biting can be produced.

Further, the pressurization treatment can be performed in an atmospheric pressure atmosphere, but it may be possible to obtain uniform adhesive force by performing the pressure treatment in a vacuum. As the degree of vacuum, the degree of vacuum by a normal oil rotary pump is sufficient, and about 10 Torr or less is sufficient.
As an apparatus that can be used for the pressure heat treatment, a roll-type film laminator in vacuum can be used for pressing in vacuum. Alternatively, for vacuum laminating such as a film laminator that applies pressure to the entire surface of the glass at once with a thin rubber film after vacuuming, for example, "MVLP" manufactured by Meiki Co., Ltd. can be used.

The non-thermoplastic polyimide laminate bonded via the silane coupling agent can be heat-treated to obtain sufficient interlayer adhesion strength. The heat treatment may be performed after laminating, or the laminating and heating may be performed at the same time by performing a heating laminating.

When performing heating laminating, first, a multi-layer polyimide bonded via a silane coupling agent is pressed (for example, at a relatively low temperature (for example, less than 80 ° C., more preferably 10 ° C. or higher, 60 ° C. or lower)). Adhesion between the two is ensured by preferably about 0.05 to 50 MPa), and then at a relatively high temperature (for example, 80 ° C. or higher, more preferably 80 ° C. or higher) under pressure (preferably 0.2 MPa or higher and 20 MPa or lower) or at normal pressure. By heating at 100 to 250 ° C., more preferably 120 to 220 ° C.), the chemical reaction at the adhesion interface is promoted, and the non-thermoplastic polyimide film can be laminated.

The heating step may be performed at the same time as laminating the thermoplastic polyimide and the copper foil. That is, after applying a resin solution of polyamic acid on a copper foil, a pre-laminated non-thermoplastic polyimide laminate may be placed on the copper foil and heated. At this time, it is preferable that the non-thermoplastic polyimide laminate is heated in advance to increase the peel strength between the layers.

<Circuit board>
The circuit board of the present embodiment can be manufactured by processing the metal layer of the metal-clad laminate into a pattern by a conventional method to form a wiring layer. The patterning of the metal layer can be performed by any method utilizing, for example, photolithography technology and etching.

When manufacturing a circuit board, as steps normally performed, for example, through-hole processing in the pre-process, terminal plating in the post-process, outer shape processing, and the like can be performed according to a conventional method.

As described above, by using the metal-clad laminate of the present embodiment as a circuit board material typified by FPC, it is possible to impart excellent impedance matching to the circuit board and improve the transmission characteristics of electric signals. Therefore, the reliability of the electronic device can be improved.

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

<Measurement of viscosity>
The viscosity was measured using an E-type viscometer (manufactured by Brookfield, trade name; DV-II + Pro) at 25 ° C. The rotation speed was set so that the torque was 10% to 90%, and 2 minutes after the start of the measurement, the value when the viscosity became stable was read.

<Glass transition temperature (measurement of Tg)>
The glass transition temperature is a heating rate of a polyimide film having a size of 5 mm × 20 mm from 30 ° C. to 400 ° C. using a dynamic viscoelasticity measuring device (DMA: manufactured by UBM, trade name: E4000F). The measurement was performed at 4 ° C./min and a frequency of 1 Hz, and the temperature at which the change in elastic modulus (mechanical tan δ) was maximized was defined as the glass transition temperature. “Thermoplastic” means that the storage elastic modulus at 30 ° C. measured using DMA is 1.0 × 10 ⁹ Pa or more and the storage elastic modulus at 300 ° C. is ^{less than 3.0 × 10 8 Pa.} A storage elastic modulus at 30 ° C. of 1.0 × 10 ⁹ Pa or more and a storage elastic modulus at 300 ° C. of 3.0 × 10 ⁸ Pa or more was defined as “non-thermoplastic”.

<Measurement of coefficient of thermal expansion (CTE)>
The copper foil of the copper-clad laminate is etched with an aqueous solution of cupric chloride, washed thoroughly with water, dried at 120 ° C. for 3 hours, and then dried under the conditions of temperature; 24-26 ° C. and humidity; 45-55%, 24. The sample left for a long time was used as a sample.
A sample cut into a size of 3 mm × 20 mm is heated from 30 ° C. to 265 ° C. at a constant heating rate while applying a load of 5.0 g using a thermomechanical analyzer (manufactured by Bruker, trade name; 4000SA). After holding the sample at that temperature for 10 minutes, the sample was cooled at a rate of 5 ° C./min to obtain an average coefficient of thermal expansion (coefficient of thermal expansion) from 250 ° C. to 100 ° C.

<Measurement of hygroscopicity>
The polyimide film was cut into pieces of about 10 cm square, and the mass was immediately measured to determine the moisture absorption mass. Then, it was dried by heating in a dry oven at 150 ° C. for 1 hour, taken out from the dry oven, and immediately measured by mass to determine the dry mass. The hygroscopicity was calculated by the following formula.
Moisture absorption rate (mass%) = [(moisture absorption mass-dry mass) / dry mass] x 100

<Measurement of relative permittivity and dielectric loss tangent>
The copper foil of the copper-clad laminate was etched with an aqueous solution of cupric chloride, washed thoroughly with water, dried at 120 ° C. for 3 hours, and then left at a temperature of 25 ° C. and humidity of 50% RH for 24 hours. The sample was used as a sample.
_{For the relative permittivity and dielectric loss tangent, use a network analyzer (manufactured by Anritsu) and measure the relative permittivity (ε c} ) and dielectric loss tangent (tan δ) of the sample at a temperature of 23 ° C and a frequency of 10 GHz by the cavity resonator perturbation method. bottom.
Further, E indicating the dielectric loss coefficient of the resin laminate was calculated based on the above mathematical formula (a).
E = ε _c × tan δ ・ ・ ・ (a)

<Measurement of surface roughness of copper foil>
Measurement of 10-point average roughness (Rz) and arithmetic mean height (Ra):
It was determined using a stylus type surface roughness meter (manufactured by Kosaka Laboratory Co., Ltd., trade name; surf coder ET-3000) under the measurement conditions of Force; 100 μN, Speed; 20 μm, Range; 800 μm. The surface roughness was calculated by a method based on JIS-B0601: 1994.

<Measurement of copper foil peel strength>
After processing the metal-clad laminate to a width of 1.0 mm, it was cut into a width of 8 cm and a length of 4 cm to prepare a measurement sample. Using a Tencilon tester (manufactured by Toyo Seiki Seisakusho, trade name; Strograph VE-1D), one side of the measurement sample is fixed to an aluminum plate with double-sided tape, and the other side is 50 mm / min in the 90 ° direction. The central strength when peeled by 10 mm was determined at a speed. The "copper foil peel strength" is the peel strength when peeled off at the interface between the copper foil layer on the cast side and the resin laminate.

<Measurement of interlayer peel strength of non-thermoplastic polyimide>
The interlayer peel strength of the non-thermoplastic polyimide means the 90-degree peel strength between the non-thermoplastic polyimide films after the non-thermoplastic polyimide laminate is heat-treated at 200 ° C. for 1 hour in an air atmosphere.

The measurement conditions for the 90-degree peel strength are as follows.
The other non-thermoplastic polyimide film is peeled off at an angle of 90 degrees with respect to the non-thermoplastic polyimide film fixed on the measurement stage with double-sided tape.
Measure 5 times and use the average value as the measured value.
Measurement temperature; room temperature (25 ° C)
Peeling speed; 100 mm / min
Atmosphere; Atmosphere measurement sample width; 2.5 cm

<Thickness of silane coupling agent condensate layer (adhesive layer)>
The thickness of the silane coupling agent condensate layer is determined by polishing the cross section of the polyimide film laminate in the direction perpendicular to the film surface, then making an ultrathin section with a microtome, taking a cross-sectional photograph with a transmission electron microscope, and measuring the measured value. It was calculated back from the magnification.

The abbreviations used in the synthesis examples indicate the following compounds.
PMDA: Pyrrolimet acid dianhydride BPDA: 3,3'-4,4'-biphenyltetracarboxylic acid dianhydride m-TB: 2,2'-dimethyl-4,4'-diaminobiphenyl TPE-R: 1, 3-Bis (4-Aminophenoxy) Benzene DMAc: N, N-Dimethylacetamide

<Manufacturing of thermoplastic polyimide>
200 g of DMAc was placed in a reaction vessel equipped with a thermocouple and a stirrer and capable of introducing nitrogen. 1.335 g of m-TB (0.0063 mol) and 10.414 g of TPE-R (0.0356 mol) were dissolved in this reaction vessel with stirring in the vessel. Next, 0.932 g of PMDA (0.0043 mol) and 11.319 g of BPDA (0.0385 mol) were added. Then, stirring was continued for 2 hours to prepare a resin solution a of polyamic acid having a solution viscosity of 1,420 mPa · s. Next, a resin solution a of polyamic acid was uniformly applied to one side (Rz; 2.1 μm) of a long electrolytic copper foil so that the thickness after curing was about 2 to 3 μm, and then at 120 ° C. The solvent was removed by heating and drying. Further, a stepwise heat treatment from 120 ° C. to 360 ° C. was performed within 30 minutes to complete imidization. The copper foil was removed by etching with an aqueous ferric chloride solution to prepare a polyimide film a (thermoplastic, Tg; 283 ° C., CTE; 53 ppm / K).

As the non-thermoplastic polyimide film, a commercially available film was used.
F1: Upirex (registered trademark) 25S (polyimide film manufactured by Ube Industries, Ltd., thickness 25 μm)
F2: Kapton (registered trademark) 100EN (polyimide film manufactured by Toray DuPont Co., Ltd., thickness 12.5 μm)
F3: Xenomax (registered trademark) F15LR2 (polyimide film manufactured by Toyobo Co., Ltd., thickness 15 μm)

<Vacuum plasma treatment of polyimide film>
As a pre-process for treating the polyimide film with a silane coupling agent, the polyimide film was subjected to vacuum plasma treatment. For vacuum plasma processing, a device for long film processing is used, the inside of the vacuum chamber is evacuated ^{until it becomes 1 × 10 -3} Pa or less, argon gas is introduced into the vacuum chamber, the discharge power is 100 W, and the frequency is 15 kHz. Under the conditions, a plasma treatment of argon gas was performed for 20 seconds. By winding the film after the plasma treatment in a roll shape in the processing apparatus, the hygroscopic state of the film can be kept substantially the same as the hygroscopic state during the plasma treatment. A sample of about 10 cm square was immediately cut out from the film after the plasma treatment, and the hygroscopicity was measured. As a result, the hygroscopicity of F1 was 0.12%, the hygroscopicity of F2 was 0.21%, and the hygroscopicity of F3 was 0.28%.

<Preparation of non-thermoplastic polyimide film temporary bonding laminate 1>
Using the apparatus shown in FIG. 5, a three-layer long temporary laminated body of the polyimide film F1 subjected to plasma treatment was produced. KBM-903 (3-aminopropyltrimethoxysilane, Shin-Etsu Silicone) was used as the coating liquid (silane coupling agent) to be the adhesive layer, and F1 was previously slit to a width of 120 mm.

<Preparation of non-thermoplastic polyimide film temporary bonding laminate 2>
It was produced in the same manner as the non-thermoplastic polyimide film laminate 1 except that F1, F1, F2, F1 and F1 were laminated in this order. In the device of FIG. 5, three-layer lamination is possible in one pass, but the completed three-layer temporary bonding laminate is set in the unwinding portion again, and the coating liquid is applied and laminated to form the five-layer laminate. Obtained.

<Preparation of non-thermoplastic polyimide film temporary bonding laminate 3>
It was produced in the same manner as the non-thermoplastic polyimide film laminate 2 except that F3, F1, F1, F1, F1, and F3 were laminated in this order.

<Preparation of non-thermoplastic polyimide film temporary bonding laminate 4>
It was produced in the same manner as the non-thermoplastic polyimide film laminate 2 except that F3, F2, F2, F2, F2, and F3 were laminated in this order.

<Example 1>
A resin solution a is uniformly applied to the surface of a long electrolytic copper foil (Rz; 0.8 μm, Ra; 0.2 μm) so that the thickness after curing is about 2 to 3 μm, and then at 120 ° C. The solvent was removed by heating and drying. The obtained copper foil and resin laminate were subjected to a stepwise heat treatment from 120 ° C. to 360 ° C. to complete imidization, and a thermoplastic polyimide with a single-sided copper foil was obtained. Two thermoplastic polyimide films with a single-sided copper foil were prepared, and the non-thermoplastic polyimide film temporary bonding laminate 1 was continuously connected between a pair of heating rolls at a rate of 1 m / min so as to be in contact with the thermoplastic polyimide layer. A double-sided copper-clad laminate having a resin laminate thickness of 81 μm was prepared by hot-pressing (roll surface temperature; 390 ° C., linear pressure between rolls; 134 kN / m). A polyimide film laminate was prepared by etching and removing the copper foil of the double-sided copper-coated laminate. Table 1 shows the dielectric loss coefficients E and CTE of this polyimide film laminate.

<Example 2>
A polyimide film laminate was prepared in the same manner as in Example 1 except that the non-thermoplastic polyimide film temporary laminate 2 was used. The thickness of the resin laminate was 121 μm. Table 1 shows the dielectric loss coefficients E and CTE of this polyimide film laminate.

<Example 3>
A polyimide film laminate was prepared in the same manner as in Example 1 except that the non-thermoplastic polyimide film temporary laminate 3 was used. The thickness of the resin laminate was 131 μm. Table 1 shows the dielectric loss coefficients E and CTE of this polyimide film laminate.

<Example 4>
A single-sided copper-coated laminate was prepared in the same manner as in Example 1 except that one thermoplastic polyimide film with a single-sided copper foil and the non-thermoplastic polyimide film temporary-bonded laminate 1 were used. A polyimide film laminate was prepared by etching and removing the copper foil of this single-sided copper-coated laminate. The thickness of the resin laminate was 81 μm. Table 1 shows the dielectric loss coefficients E and CTE of this polyimide film laminate. ..

<Comparative example 1>
A polyimide film laminate was prepared in the same manner as in Example 1 except that the non-thermoplastic polyimide film temporary laminate 4 was used. The thickness of the resin laminate was 91 μm. Table 1 shows the dielectric loss coefficients E and CTE of this polyimide film laminate.

11A Copper foil layer 11B Copper foil layer 12A Thermoplastic polyimide layer 12B Thermoplastic polyimide layer 13A Non-thermoplastic polyimide layer 13B Non-thermoplastic polyimide layer 14A Adhesive layer 14B Adhesive layer 15A Adhesive layer 15B Adhesive layer 16 Adhesive layer 17 Non-thermoplastic polyimide Laminated body 18 Resin laminated body 100 Double-sided copper-coated laminate 21A Copper foil layer 21B Copper foil layer 22A Thermoplastic polyimide layer 22B Thermoplastic polyimide layer 23A Non-thermoplastic polyimide layer 23B Non-thermoplastic polyimide layer 24A Adhesive layer 24B Adhesive layer 25A Non Thermoplastic polyimide layer 25B Non-thermoplastic polyimide layer 26 Adhesive layer 27 Non-thermoplastic polyimide layer 200 Single-sided CCL
210 Single-sided CCL
31 B-shaped frame 32 Non-thermoplastic polyimide film 33 Treatment chamber 34 Water bath 35 Silane coupling agent 41 Film unwinding part 42 Coating liquid supply part 43 Coating liquid discharge part 44 Wire bar 45 Long base material unwinding part 46 Pressurizing part 47 Winding part 48 Height adjustment roll of long base material 51 Film unwinding part 52 Coating liquid supply part 53 Coating liquid discharge part 54 Coating liquid steam exhaust port 55 Long base material unwinding Part 56 Pressurizing part 57 Winding part 58 Height adjustment roll of long base material

Claims (4)

A metal-clad laminate comprising a resin laminate containing a plurality of polyimide layers and a metal layer laminated on at least one side of the resin laminate, wherein the resin laminate is the following conditions i) to iii). ;
i) The total thickness is in the range of 40-400 μm;
ii) Includes a first polyimide layer in contact with the metal layer and a second polyimide layer directly or indirectly laminated on the first polyimide layer;
iii) The following formula (a)
E = ε _c × tan δ ・ ・ ・ (a)
[Here, ε _c indicates the relative permittivity at 10 GHz, and tan δ indicates the dielectric loss tangent at 10 GHz. ]
The E value, which is the dielectric loss coefficient calculated based on, is less than 0.01;
A metal-clad laminate characterized by satisfying. The metal-clad laminate according to claim 1, wherein the resin laminate has a structure in which at least the first polyimide layer and the second polyimide layer are laminated in this order from the metal layer side, respectively. .. The claim is characterized in that, in the resin laminate, the metal layer and the first polyimide layer, and the first polyimide layer and the second polyimide layer do not substantially contain an adhesive layer. 2. The metal-clad laminate according to 2. A circuit board in which a wiring circuit is processed on the metal layer of the metal-clad laminate according to any one of claims 1 to 3.

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