JP4872187B2 - Metal-clad laminate - Google Patents

Description

  The present invention relates to a metal-clad laminate using a low dielectric constant polyimide having good heat resistance and adhesiveness. The metal-clad laminate is processed into a printed wiring board, a surface heating element, an electromagnetic shielding material, a flat cable, or the like.

  Some metal-clad laminates are manufactured by bonding an insulating substrate and a metal layer through an adhesive or an adhesive film. For example, a metal-clad laminate having a three-layer structure in which an aromatic polyimide film is used as an insulating substrate and the metal layer is bonded via an adhesive film has been proposed (see Patent Document 1).

  Conventionally, epoxy adhesives or acrylic adhesives have been mainly used as adhesives or adhesive films. However, since these resins are inferior in heat resistance, the heat resistance of the product after bonding becomes insufficient, and the subsequent processing conditions and use conditions are restricted.

  For this reason, adhesives and adhesive films with excellent heat resistance are required. For example, a dispersion of polyimide or polyamic acid is applied to an insulating substrate as an adhesive, and then solvent removal and, in some cases, imidization are performed. A method of performing a treatment to form a thermocompression-bonding adhesive layer is disclosed (see Patent Documents 2 and 3). Also disclosed is a method in which a resin dispersion is applied to a glass plate or the like, followed by solvent removal and, in some cases, imidization, to form a thermocompression adhesive film. An object to be bonded such as a metal layer is thermocompression bonded to the adhesive layer and the adhesive film thus formed (see Patent Documents 2 to 4).

  In addition, an insulating protective film is formed on a circuit surface of a printed wiring board using a liquid cover coat agent (also called cover lay ink) or a cover lay film. After the cover coating agent is applied to the circuit surface of the printed wiring board by a method such as screen printing, a cover coating layer is formed through a treatment such as curing. However, the widely used cover coat agent is mainly an epoxy resin that is inferior in heat resistance and flexibility, so that the heat resistance and flexibility of the printed wiring board after the cover coat become insufficient. The subsequent processing conditions and usage conditions were limited. Therefore, there is a need for a cover coating agent that is excellent in heat resistance and flexibility. For example, a polyimide or polyamic acid dispersion liquid using a solvent as a dispersion medium is applied to the circuit surface of a flexible printed wiring board as a cover coating agent, Thereafter, a method of forming a cover coat layer by removing the solvent and optionally imidizing is disclosed (see Patent Documents 5 and 6).

  As the cover lay film, a polyimide film having excellent heat resistance is used, but the film itself does not have many adhesive properties, and it is necessary to use an epoxy or acrylic heat resistance that is inferior separately. There was a similar problem. Therefore, there is a demand for an adhesive film that is flexible and has excellent heat resistance. For example, a polyimide or polyamic acid dispersion is applied to a film-forming support such as a glass plate or a metal plate, and then the solvent is removed. In some cases, an imidization treatment is performed to form a thermocompression adhesive cover lay film (see Patent Document 4).

In the information processing and communication fields in recent years, the transmission frequency and CPU operating frequency have been increased to transmit and process large volumes of information. At the same time as the insulating layer has become thinner, the adhesive layer and cover coat layer There is a need to shorten the signal propagation speed delay time by lowering the dielectric constant of the entire insulating layer including. However, the polyimides used in the conventional adhesive layer, adhesive film, cover coat layer, and coverlay film described above are aromatic polyimides, and their dielectric constant at 10 GHz is also the content of aromatic rings. However, in general, there is a high defect of about 3.5.
JP-A-55-91895 JP-A-5-32950 JP-A-5-59344 Japanese Patent No. 3213079 Japanese Patent No. 2820497 JP-A-8-109259

  An object of the present invention is to solve the problems of aromatic polyimides conventionally used for adhesive layers and cover coat layers, and is a low dielectric polyimide that is thermocompression-bondable, solvent-soluble, and has good heat resistance and adhesion. Another object of the present invention is to provide a metal-clad laminate using the above as an adhesive layer, cover coat layer, cover lay film or the like.

  In general, it is known that the use of an aliphatic monomer as the monomer constituting the polymer material lowers the dielectric constant. The present inventors synthesized a polyimide using a non-aromatic tetracarboxylic dianhydride. Non-aromatic tetracarboxylic dianhydrides include aliphatic (chain) tetracarboxylic dianhydrides such as 1,2,3,4-butanetetracarboxylic dianhydride; and 1,2,3 4-cyclobutanetetracarboxylic dianhydride, 1,2,4,5-cyclopentanetetracarboxylic dianhydride, bicyclo [2.2.2] oct-7-ene-2,3,5,6-tetra And alicyclic tetracarboxylic dianhydrides such as carboxylic dianhydrides. However, since the heat resistance of the polyimide obtained using the aliphatic (chain) tetracarboxylic dianhydride is extremely low, it cannot be used for processing such as soldering, which causes a problem in practice. On the other hand, when an alicyclic tetracarboxylic dianhydride is used, a polyimide having improved heat resistance compared to a chain-like one can be obtained. However, since polyimides obtained using 1,2,3,4-cyclobutanetetracarboxylic dianhydride have low solubility in solvents, polyimide solutions can be used for forming metal layers, insulating substrates or films. Even if it is applied to a support, a sufficient thickness for use as an adhesive layer, a cover coat layer and a cover lay film cannot be obtained. In addition, when 1,2,4,5-cyclopentanetetracarboxylic dianhydride and bicyclo [2.2.2] oct-7-ene-2,3,5,6-tetracarboxylic dianhydride are used. A polyimide having high solubility in a solvent can be obtained, but a film or a film obtained by applying a polyimide solution to a metal layer, an insulating substrate or a film-forming support has insufficient flexibility, and an adhesive layer. There are practical problems as a cover coat layer and a cover lay film.

As a result of intensive studies to solve the above problems, the present inventors have found that a polyimide having a repeating unit having a specific alicyclic tetracarboxylic acid structure is thermocompression-bondable and solvent-soluble, and has heat resistance and adhesiveness. It was found that the metal-clad laminate having good and low dielectric properties and the use of the polyimide had extremely suitable characteristics, and reached the present invention.
That is, the present invention is a metal-clad laminate including at least one polyimide layer, at least one insulating substrate, and at least one metal layer, wherein the polyimide layer is represented by the general formula I Provided is a metal-clad laminate comprising a polyimide having a unit.

(In the formula, R is a tetravalent group derived from cyclohexane. Φ is a group consisting of a divalent aliphatic group having 2 to 39 carbon atoms, an alicyclic group, an aromatic group, or a combination thereof. And the main chain of Φ is —O—, —SO ₂ —, —CO—, —CH ₂ —, —C (CH ₃ ) ₂ —, —OSi (CH ₃ ) ₂ —, —C ₂ H ₄ O. And at least one group selected from the group consisting of — and —S— may intervene.)
The polyimide layer is formed by applying an organic solvent solution of the polyimide (hereinafter sometimes referred to as “polyimide A”) onto the surface of the insulating substrate, the metal layer, or both, and evaporating the solvent. Is done. Moreover, the polyimide film which consists of polyimide A can also be used as the polyimide layer in this invention.

The polyimide layer may be disposed between the insulating substrate and the metal layer, or may be a cover coat layer or a cover lay film that forms the surface layer of the metal-clad laminate. By disposing and integrating a polyimide layer between the insulating substrate and the metal layer, the metal-clad laminate of the present invention can be obtained. The polyimide layer forming the surface layer of the metal-clad laminate can be patterned by a wet etching method using an aprotic polar organic solvent as an etchant.
The glass transition temperature of polyimide A is preferably 350 ° C. or lower, and the dielectric constant at 10 GHz is preferably 3.2 or lower.

  The insulating layer of the metal-clad laminate composed of the adhesive layer, adhesive film, cover coat layer and cover lay film of the present invention has a dielectric constant at 10 GHz of 3.2 or less, good adhesiveness, and high frequency use. It is suitable for a printed wiring board.

  The polyimide used in the present invention has a repeating unit represented by the following general formula I.

In the formula, R is a tetravalent group derived from cyclohexane. Φ is a group composed of a divalent aliphatic group having 2 to 39 carbon atoms, an alicyclic group, an aromatic group, or a combination thereof, and the main chain of Φ has —O—, —SO ₂ —, — _{CO -, - CH 2 -,} - C (CH 3) 2 -, - OSi (CH 3) 2 -, - C 2 H 4 O -, - such as S- may be interposed.

  Preferred Φ includes aliphatic groups such as polyalkylene, polyoxyalkylene, xylylene, and alkyl-substituted and halogen-substituted products thereof; cyclohexane, dicyclohexylmethane, dimethylcyclohexane, isophorone, norbornane, and alkyl-substituted products thereof, halogen A divalent alicyclic group derived from a substituent, and the like; and a divalent group derived from benzene, naphthalene, biphenyl, diphenylmethane, diphenyl ether, diphenylsulfone, benzophenone, and alkyl substituents, halogen substituents thereof, etc. An aromatic group is mentioned. More specifically, a divalent group represented by the following structural formula can be given.

  The content of the repeating unit represented by the general formula I is preferably 10 to 100 mol%, more preferably 50 to 100 mol% of all repeating units. In addition, the number of repeating units represented by the general formula I in one molecule of polyimide is preferably 10 to 2000, and more preferably 20 to 200.

  Polyimide A can be obtained by reacting a tetracarboxylic acid component with a diamine component (diamine and derivatives thereof). Examples of the tetracarboxylic acid component include cyclohexanetetracarboxylic acid, cyclohexanetetracarboxylic acid esters, cyclohexanetetracarboxylic dianhydride, and the like, and cyclohexanetetracarboxylic dianhydride is preferable. The tetracarboxylic acid component includes positional isomers.

  Polyimide A having a cyclohexanetetracarboxylic acid skeleton derived from the tetracarboxylic acid component is easy to obtain a high molecular weight, and it is easy to obtain a flexible film, and the solubility in a solvent is sufficiently high. This is advantageous. Further, it is very advantageous because it can be easily formed as a flexible adhesive layer or cover coat layer having sufficient thickness and durability by applying as an adhesive agent or a cover coat agent.

  The tetracarboxylic acid component may be other tetracarboxylic acid or a derivative thereof such as pyromellitic acid, 3, 3 ′, 4 as long as it does not impair the solvent solubility of polyimide A, film flexibility, thermocompression bonding, and high frequency characteristics. , 4′-biphenyltetracarboxylic acid, 2,3,3 ′, 4′-biphenyltetracarboxylic acid, 2,2-bis (3,4-dicarboxyphenyl) propane, 2,2-bis (2,3- Dicarboxyphenyl) propane, 2,2-bis (3,4-dicarboxyphenyl) -1,1,1,3,3,3-hexafluoropropane, 2,2-bis (2,3-dicarboxyphenyl) ) -1,1,1,3,3,3-hexafluoropropane, bis (3,4-dicarboxyphenyl) sulfone, bis (3,4-dicarboxyphenyl) ether, bi (2,3-dicarboxyphenyl) ether, 3,3 ′, 4,4′-benzophenone tetracarboxylic acid, 2,2 ′, 3,3′-benzophenone tetracarboxylic acid, 4,4- (p-phenylenediene) Oxy) diphthalic acid, 4,4- (m-phenylenedioxy) diphthalic acid, ethylenetetracarboxylic acid, 1,2,3,4-butanetetracarboxylic acid, 1,2,3,4-cyclobutanetetracarboxylic acid, 1,2,4,5-cyclopentanetetracarboxylic acid, 3-carboxymethyl-1,2,4-cyclopentanetricarboxylic acid, bicyclo [2.2.2] oct-7-ene-2,3,5 6-tetracarboxylic acid, dicyclohexyltetracarboxylic acid, 1,1-bis (2,3-dicarboxyphenyl) ethane, bis (2,3-dicarboxyphenyl) methane, bi Su (3,4-dicarboxyphenyl) methane and at least one compound selected from derivatives thereof may be included.

  Examples of the diamine component include diamines, diisocyanates, and diaminodisilanes, with diamines being preferred. The diamine content in the diamine-based component is preferably 50 mol% or more (including 100 mol%).

  The diamine may be an aliphatic diamine, an aromatic diamine, or a mixture thereof. In the present invention, “aromatic diamine” refers to a diamine in which an amino group is directly bonded to an aromatic ring, and an aliphatic group, an alicyclic group, and other substituents are included in a part of the structure. You may go out. The “aliphatic amine” refers to a diamine in which an amino group is directly bonded to an aliphatic group or an alicyclic group, and an aromatic group or other substituent may be included in a part of the structure.

  In general, when an aliphatic diamine is used as a constituent component, the polyamic acid as an intermediate product and the aliphatic diamine form a strong complex, and thus it is difficult to obtain a high molecular weight polyimide. Therefore, it is necessary to devise such as using a solvent having a relatively high solubility of the complex, such as cresol. However, when cyclohexanetetracarboxylic acid or a derivative thereof and an aliphatic diamine are used as components, a complex in which the bond between the polyamic acid and the aliphatic diamine is relatively weak is formed, so that the polyimide can be easily increased in molecular weight.

  Examples of the aliphatic diamine include 4,4′-diaminodicyclohexylmethane, ethylenediamine, hexamethylenediamine, polyethylene glycol bis (3-aminopropyl) ether, polypropylene glycol bis (3-aminopropyl) ether, 1,3- Examples include bis (aminomethyl) cyclohexane, 1,4-bis (aminomethyl) cyclohexane, m-xylylenediamine, p-xylylenediamine, isophorone diamine, norbornane diamine, and siloxane diamines.

  Examples of the aromatic diamine include 4,4′-diaminodiphenyl ether, 4,4′-diaminodiphenylmethane, 4,4′-diaminodiphenylsulfone, m-phenylenediamine, p-phenylenediamine, diaminobenzophenone, and 2,6. -Diaminonaphthalene, 1,5-diaminonaphthalene, etc. are mentioned.

  In the present invention, polyimide A is usually produced as an organic solvent solution. Examples of the organic solvent include N-methyl-2-pyrrolidone, N, N-dimethylacetamide, N, N-dimethylformamide, dimethyl sulfoxide, hexamethylphosphoramide, tetramethylene sulfone, p-chlorophenol, and m-cresol. , 2-chloro-4-hydroxytoluene and the like.

The organic solvent solution of polyimide A is obtained by the following methods (i) to (iii).
(I) A tetracarboxylic acid component is added to an organic solvent solution of a diamine-based component, or a diamine-based component is added to an organic solvent solution of a tetracarboxylic acid component, preferably at a temperature of 80 ° C. or less, particularly near room temperature or lower. For 0.5 to 3 hours. An azeotropic dehydration solvent such as toluene or xylene is added to the resulting polyamic acid solution of the reaction intermediate, and a dehydration reaction is performed while removing the generated water out of the system by azeotropy to obtain an organic solvent solution of polyimide A.
(Ii) After imidization by adding a dehydrating agent such as acetic anhydride to the polyamic acid solution of the reaction intermediate, a solvent having poor solubility in polyimide A such as methanol is added to precipitate polyimide A. After being separated as a solid by filtration, washing and drying, it is dissolved in a solvent such as N, N-dimethylacetamide to obtain an organic solvent solution of polyimide A.
(Iii) A polyamic acid solution is prepared using a high-boiling solvent such as cresol, and kept at 150 to 220 ° C. for 3 to 12 hours to be converted into a polyimide, and then a solvent having poor solubility in polyimide A such as methanol is added. Then, polyimide A is precipitated. After being separated as a solid by filtration, washing and drying, it is dissolved in a solvent such as N, N-dimethylacetamide to obtain an organic solvent solution of polyimide A.

  The polyimide A concentration in the organic solvent solution is preferably 5 to 50% by weight, and more preferably 10 to 40% by weight.

  In the present invention, the polyimide layer is formed by applying an organic solvent solution of polyimide A obtained by the above methods (i) to (iii) to a metal layer or the like and then heating to evaporate the solvent. . Alternatively, a polyimide film obtained in advance from the organic solvent solution can be used as a polyimide layer. In such a polyimide film, the organic solvent solution is applied to a film-forming support such as a glass plate or a metal plate, heated to 200 ° C. to 350 ° C. to evaporate the solvent, and the formed film is supported. It is manufactured by peeling from. A polyimide film can also be produced by a method in which an organic solvent solution of polyamic acid is applied to a film-forming support and heated to 200 ° C. to 350 ° C. to perform a dehydrating imidization reaction. The thickness of the polyimide layer is preferably 1 to 100 μm.

  In addition to the feature that the dielectric constant at high frequency is low, the polyimide A used in the present invention has a low frequency dependence of the dielectric constant in a frequency range of 1 to 20 GHz which is a practically important frequency range, and shows a substantially constant value. It also has characteristics and is extremely preferable as an insulating material. When an aliphatic diamine is selected as the diamine, the dielectric constant at 10 GHz is 2.8 or less, which is particularly preferable. However, even when an aromatic diamine is used, 3.2 or less is achieved. The lower limit of the dielectric constant that can be achieved is usually 2.6. Furthermore, polyimide A has a low frequency dependency for the dielectric loss tangent in the range of 1 to 20 GHz, and also has a characteristic of showing a substantially constant value in the range of 0.008 to 0.018, and has extremely excellent high frequency characteristics. have.

  The glass transition temperature of the polyimide film made of polyimide A varies depending on the selected diamine, but is generally 350 ° C. or lower. Although depending on the amount of residual solvent, adhesiveness develops at temperatures above the glass transition temperature, so if the glass transition temperature is too high, the thermocompression bonding temperature becomes too high, and if the glass transition temperature is too low, the heat resistance of the film itself It is not preferable because of lack of sex. The range of a preferable glass transition temperature is 200 to 350 ° C., and particularly preferably 250 to 320 ° C.

  The metal-clad laminate of the present invention forms a polyimide adhesive layer by applying an organic solvent solution of polyimide A to the surface of an insulating substrate, a metal layer, or both, and then evaporating the solvent. A body (insulating base material, metal layer, printed wiring board, etc.) can be manufactured by thermocompression bonding to the adhesive layer. Further, an organic solvent solution of polyimide A may be applied to both surfaces such as an insulating base material and a metal layer, and an adhesive layer may be formed, and then the adherend may be thermocompression bonded to the adhesive layers on both surfaces. Further, it is also possible to impregnate a glass fiber cloth or carbon fiber cloth with an organic solvent solution of polyimide A for use. Moreover, the metal-clad laminate of this invention can be manufactured by using a film of polyimide A as an adhesive polyimide layer and sandwiching it between a plurality of adherends, followed by thermocompression bonding. In addition, a metal thin film is directly formed on the surface of the polyimide A film by sputtering, vapor deposition, electroless plating, or the like to obtain a laminated structure of a metal layer and a polyimide layer, and then metallized by thermocompression bonding with an adherend. A tension laminate can also be produced. The printed wiring board is composed of the following insulating base material and metal layer, and a conductor pattern is formed by printing based on circuit design and subjected to predetermined processing.

More specifically, an organic solvent solution of polyimide A is first applied on an insulating substrate, and then the solvent is evaporated to form an adhesive layer. Next, a metal-clad laminate can be produced by placing a metal layer on the formed adhesive layer surface and continuously thermocompressing the metal layer using a pressure roll or the like.
Moreover, the organic solvent solution of polyimide A can also be used as an adhesive for a general coverlay film. In this case, after applying an organic solvent solution of polyimide A to the surface of the coverlay film and removing the solvent to form an adhesive layer, the printed wiring board on which the circuit pattern was created using a hot press molding machine A metal-clad laminate can be manufactured by thermocompression bonding.
The organic solvent solution of polyimide A can also be used as a cover coat agent. After applying the solution to the circuit surface of the printed wiring board after creating the circuit pattern, the film is heated to 100 ° C. to 350 ° C. to evaporate the solvent, whereby a polyimide A film (cover coat layer) is formed on the circuit surface. By forming the metal-clad laminate, a metal-clad laminate can be manufactured. By this method, a cover coat layer having sufficient thickness, flexibility, and good adhesion to the circuit surface can be formed.

  Moreover, as above-mentioned, the organic solvent solution of polyimide A can also be made into an adhesive polyimide film previously. A metal-clad laminate can be produced by adhering such an adhesive polyimide film to an adherend such as a metal layer, an insulating substrate, or a printed wiring board by thermocompression bonding. For example, continuous thermocompression bonding of aromatic polyimide film (insulating substrate) such as “Kapton” (manufactured by Toray DuPont Co., Ltd.), adhesive polyimide film and metal layer using a pressure roll. Thus, a metal-clad laminate can be manufactured. Furthermore, the adhesive polyimide film can be used not only for adhesion between a printed wiring board and a general coverlay film, but can also be used as an adhesive coverlay film. In this case, for example, a metal-clad laminate can be manufactured by thermocompression bonding a printed wiring board and an adhesive coverlay film using a thermoforming machine such as a hot press.

  Further, a metal layer / polyimide layer structure can be obtained by directly forming a metal thin film on the surface of the polyimide A film by a method such as sputtering, vapor deposition and electroless plating. As a vapor deposition method, a CVD method, an ion plating method, or the like can be applied in addition to normal vapor deposition. In addition, after a metal thin film is once formed by these methods, another metal film is formed on the metal thin film using another method, for example, electroplating (also called electrolytic plating) to obtain a desired film thickness. You can also A metal-clad laminate can also be produced by bonding such a polyimide layer and an insulating substrate by thermocompression bonding. In this method, before forming the metal thin film, the polyimide film surface may be subjected to a known pretreatment such as treatment with an alkaline chemical solution, plasma treatment, or sandblast treatment. By such pretreatment, the adhesive strength between the polyimide layer and the metal layer is further improved.

  Furthermore, a multilayer metal-clad laminate is obtained by arranging the polyimide layer obtained by each of the above methods on the circuit surface and / or non-circuit surface of a plurality of arbitrary printed wiring boards and integrating them by thermocompression bonding. Can also be made.

  Examples of the material for the metal layer used in the present invention include copper, aluminum, stainless steel, gold, silver, nickel, and the like, preferably copper, aluminum, and stainless steel. As the metal layer, a metal foil obtained by a method such as electrolysis or rolling may be used. Alternatively, a metal layer formed directly on the surface of the polyimide layer and / or the insulating substrate as described above may be used. Although there is no restriction | limiting in particular in the thickness of a metal layer, The range of 1-100 micrometers normally used is preferable.

  The insulating base material used in the present invention includes a flexible type and a rigid type. Flexible insulating base materials include polyimide (excluding polyimide A), polybenzimidazole, polybenzoxazole, polyamide (including aramid), polyetherimide, polyamideimide, polyester (including liquid crystalline polyester), polysulfone , Polyethersulfone, polyetherketone, polyetheretherketone, and polyimide, polybenzimidazole, polyamide (including aramid), polyetherimide, polyamideimide, and polyethersulfone are preferable. The thickness of the flexible type insulating substrate is not particularly limited, but is preferably 3 to 150 μm. Rigid type insulating base materials include glass plates, ceramic plates, plastic plates, etc. and metal plates with insulating coatings, liquid crystal polymers, phenolic resins, epoxy resins, etc., thermoplastic and thermosetting And a molded product obtained by impregnating and kneading these various resins with a reinforcing agent such as glass fiber cloth, plastic fiber cloth, and short glass fiber. The thickness of the rigid type insulating substrate is not particularly limited, but is preferably 100 to 2000 μm.

When using either the adhesive layer formed from the organic solvent solution of polyimide A and the adhesive polyimide film obtained therefrom, the thermocompression bonding temperature is preferably 200 to 400 ° C, more preferably 250 to 350 ° C. The applied pressure is preferably 0.1 to 200 kgf / cm ² , more preferably 1 to 100 kgf / cm ² . Further, thermocompression bonding may be performed in a reduced pressure atmosphere to remove the solvent and bubbles. An extremely good adhesive strength can be obtained by thermocompression bonding under the above conditions using an adhesive layer or an adhesive polyimide film.

  Polyimide A used in the present invention includes N-methyl-2-pyrrolidone, N, N-dimethylacetamide, N, N-dimethylformamide, dimethyl sulfoxide, hexamethylphosphoramide, tetramethylsulfone, γ-butyrolactone, propylene carbonate It is soluble in aprotic polar organic solvents such as dioxane. Therefore, the polyimide layer of the printed wiring board after forming the metal-clad laminate and circuit pattern of the present invention obtained by the above methods is patterned by wet etching using an aprotic polar organic solvent as an etchant. It is possible. That is, when forming a via hole or flying lead or removing a cover coat existing on a portion to be a terminal, productivity is remarkably improved as compared with the conventional patterning by dry etching, which is extremely advantageous. . Further, various applications such as exposing only a specific part of the circuit and plating a noble metal only on that part are possible.

  Hereinafter, the present invention will be described specifically by way of examples. However, this invention is not restrict | limited at all by these Examples.

Evaluation of the polyimide films obtained in Examples and Comparative Examples and the copper clad laminate were performed as follows.
(1) Dielectric constant, dielectric loss tangent Measure dielectric constant and dielectric loss tangent by cavity resonator perturbation method using dielectric constant dielectric loss tangent measuring device (CP431 / 461/501 // 531) manufactured by Kanto Electronics Co., Ltd. did.
(2) Glass transition temperature Using a differential scanning calorimeter (DSC-50) manufactured by Shimadzu Corporation, DSC measurement was performed under the condition of a heating rate of 10 ° C./min to obtain a glass transition temperature.
(3) Adhesive strength Adhesive strength was measured in accordance with JIS C 6481.

Reference Example 1,2,4,5-Cyclohexanetetracarboxylic dianhydride synthesis A catalyst with 552 g pyromellitic acid in a 5 liter Hastelloy (HC22) autoclave and rhodium supported on activated carbon 200 g and 1656 g of water were charged, and the inside of the reactor was replaced with nitrogen gas while stirring. Next, the inside of the reactor was replaced with hydrogen gas, and the temperature of the reactor was increased to 60 ° C. with a hydrogen pressure of 5.0 MPa. The reaction was carried out for 2 hours while maintaining the hydrogen pressure at 5.0 MPa. The hydrogen gas in the reactor was replaced with nitrogen gas, the reaction solution was extracted from the autoclave, and the reaction solution was filtered while hot to separate the catalyst. The filtrate was concentrated by evaporating water under reduced pressure using a rotary evaporator to precipitate crystals. The precipitated crystals were separated into solid and liquid at room temperature and dried to obtain 481, g (yield: 85.0%) of 1,2,4,5-cyclohexanetetracarboxylic acid.
Subsequently, 450 g of the obtained 1,2,4,5-cyclohexanetetracarboxylic acid and 4000 g of acetic anhydride were charged into a 5-liter glass separable flask (with Dimroth condenser), and the inside of the reactor was stirred. Replaced with nitrogen gas. The temperature was raised to the reflux temperature of the solvent under a nitrogen gas atmosphere, and the solvent was refluxed for 10 minutes. While stirring, the mixture was cooled to room temperature to precipitate crystals. The precipitated crystals were separated into solid and liquid and dried to obtain primary crystals. Further, the separated mother liquor was concentrated under reduced pressure using a rotary evaporator to precipitate crystals. The crystals were separated into solid and liquid and dried to obtain secondary crystals. The primary crystal and the secondary crystal were combined to obtain 375 g of 1,2,4,5-cyclohexanetetracarboxylic dianhydride (anhydrous yield of 96.6%).

Example 1
In a 500 mL five-necked flask equipped with a thermometer, stirrer, nitrogen inlet tube, dropping funnel with side tube, Dean Stark, and condenser tube, 10.0 g (0.05 mol) of 4,4′-diaminodiphenyl ether under nitrogen flow Then, 85 g of N-methyl-2-pyrrolidone as a solvent was added and dissolved, and then 11.2 g (0.05 g) of 1,2,4,5-cyclohexanetetracarboxylic dianhydride synthesized in Reference Example at room temperature. Mol) was added in portions over 1 hour as a solid and stirred at room temperature for 2 hours. Next, 30.0 g of xylene was added as an azeotropic dehydration solvent, the temperature was raised to 180 ° C., the reaction was carried out for 3 hours, and xylene was refluxed with a Dean Stark to separate azeotropically produced water. After 3 hours, it was confirmed that the distillation of water had ended, xylene was distilled off while raising the temperature to 190 ° C. over 1 hour, 29.0 g was recovered, and then air-cooled until the internal temperature reached 60 ° C. Thus, an organic solvent solution of polyimide was obtained. The obtained solution was applied to a glass plate, heated on a hot plate at 90 ° C. for 1 hour to evaporate the solvent, and then peeled off from the glass plate to obtain a self-supporting film. This self-supporting film was fixed to a stainless steel fixing jig and heated in a hot air dryer at 220 ° C. for 2 hours to further evaporate the solvent, thereby obtaining a light brown flexible film having a thickness of 100 μm. When the IR spectrum of this film was measured, characteristic absorption of an imide ring was observed at ν (C═O) 1772 and 1700 (cm ⁻¹ ), and it was identified as a polyimide having a repeating unit of the following formula II.

Tables 1 and 2 show the glass transition temperature, dielectric constant, and dielectric loss tangent of the obtained film.
The polyimide organic solvent solution was formed on a commercially available polyimide film (manufactured by Toray DuPont Co., Ltd., Kapton 100H, thickness 25 μm, hereinafter abbreviated as “Kapton 100H film”) to a thickness of 200 μm using a doctor blade. Applied. After drying on a hot plate at 90 ° C. for 1 hour, it was further dried at 220 ° C. for 1 hour in a hot air dryer to form an adhesive layer having a thickness of 20 μm. Electrolytic copper foil (3EC-VLP manufactured by Mitsui Mining & Smelting Co., Ltd., thickness 18 μm, hereinafter abbreviated as “copper foil 3EC-VLP”) was thermocompression bonded to this adhesive layer for 30 minutes with a hot press set at 330 ° C. Thus, a copper clad laminate was obtained. The adhesive strength is shown in Table 1. Adhesion was good.

Example 2
In the same 500 ml five-necked flask as in Example 1, 11.2 g (0.05 mol) of 1,2,4,5-cyclohexanetetracarboxylic dianhydride synthesized in Reference Example and N-methyl-as a solvent were used. A solution prepared by dissolving 40.0 g of 2-pyrrolidone and dissolving 10.5 g (0.05 mol) of 4,4′-diaminodicyclohexylmethane in 45.0 g of dimethylacetamide at room temperature over 2 hours from a dropping funnel. And dripped. After completion of dropping, the temperature was raised to 90 ° C. and stirred for 1 hour. Next, 30.0 g of xylene was added as an azeotropic dehydration solvent, the temperature was raised to 180 ° C., the reaction was carried out for 3 hours, and xylene was refluxed with a Dean Stark to separate azeotropically produced water. After 3 hours, it was confirmed that the distillation of water had ended, xylene was distilled off while raising the temperature to 190 ° C. over 1 hour, 30.0 g was recovered, and then air-cooled until the internal temperature reached 60 ° C. Thus, an organic solvent solution of polyimide was obtained. The obtained solution was applied to a glass plate, heated on a hot plate at 90 ° C. for 1 hour to evaporate the solvent, and then peeled off from the glass plate to obtain a self-supporting film. The self-supporting film was fixed to a stainless steel fixing jig and heated in a hot air dryer at 220 ° C. for 2 hours to further evaporate the solvent, thereby obtaining a colorless, transparent and flexible film having a thickness of 100 μm. When the IR spectrum of this film was measured, characteristic absorption of the imide ring was observed at ν (C═O) 1764, 1691 (cm ⁻¹ ), and it was identified as a polyimide having a repeating unit of the formula III.

Tables 1 and 2 show the glass transition temperature, dielectric constant, and dielectric loss tangent of the obtained film.
The polyimide organic solvent solution was applied onto copper foil 3EC-VLP to a thickness of 200 μm using a doctor blade. After drying on a hot plate at 90 ° C. for 1 hour, it was further dried at 220 ° C. for 1 hour in a hot air dryer to form an adhesive layer having a thickness of 20 μm. A Kapton 100H film was thermocompression bonded to this adhesive layer with a hot press set at 280 ° C. for 30 minutes to obtain a copper clad laminate. The adhesive strength is shown in Table 1. Adhesion was good.

Comparative Example 1
In the same 500 ml five-necked flask as in Example 1, 10.0 g (0.05 mol) of 4,4′-diaminodiphenyl ether and 85.0 g of dimethylacetamide as a solvent were dissolved and dissolved at room temperature in a nitrogen stream. 10.9 g (0.05 mol) of pyromellitic dianhydride was added as a solid over about 1 hour, and after completion of the addition, the mixture was stirred at room temperature for 3 hours to obtain a polyamic acid adhesive solution.
The obtained adhesive solution was applied to a glass plate, dried on a hot plate at 50 ° C. for 1 hour, and then peeled off from the glass plate to obtain a self-supporting film. This self-supporting film is fixed on a stainless steel fixture and heated in a hot air dryer at 100 ° C. for 3 hours, 200 ° C. for 3 hours, 250 ° C. for 2 hours, 300 ° C. for 1 hour, and 400 ° C. for 1 hour. The solvent was evaporated to obtain a brown and flexible film with a thickness of 50 μm. Table 1 shows the glass transition temperature, dielectric constant, and dielectric loss tangent of the obtained film.
The polyamic acid adhesive solution was applied to a thickness of 200 μm on a Kapton 100H film using a doctor blade. After drying for 1 hour on a hot plate at 50 ° C, heat in a hot air dryer for 3 hours at 100 ° C, 3 hours at 200 ° C, 2 hours at 250 ° C, 1 hour at 300 ° C, and 1 hour at 400 ° C. An imidization treatment was performed to form an adhesive layer having a thickness of 15 μm. Copper foil 3EC-VLP was thermocompression bonded to this adhesive layer with a hot press set at 350 ° C. for 30 minutes to obtain a copper clad laminate. The adhesive strength is shown in Table 1. Adhesive strength was insufficient.

Copper foil used: 3EC-VLP (thickness 18 μm) manufactured by Mitsui Kinzoku Co., Ltd.
Polyimide film used: Kapton 100H manufactured by Toray DuPont Co., Ltd. (thickness 25 μm)
CTDA: 1,2,4,5-cyclohexanetetracarboxylic dianhydride
PMDA: pyromellitic dianhydride
ODA: 4,4'-diaminodiphenyl ether
DCHM: 4,4'-diaminodicyclohexylmethane

Example 3
The polyimide organic solvent solution obtained in Example 2 was applied onto a Kapton 100H film to a thickness of 200 μm using a doctor blade. After drying on a hot plate at 90 ° C. for 1 hour, it was further dried at 220 ° C. for 1 hour in a hot air dryer to form an adhesive layer having a thickness of 20 μm. Using the Kapton 100H film with this adhesive layer as an adhesive coverlay film, the adhesive layer is placed on the circuit surface of a two-layer flexible printed wiring board (Toyobo Co., Ltd. Viroflex) made of a copper layer / polyimide film. Then, they were thermocompression bonded with a hot press set at 280 ° C. for 30 minutes. The copper clad laminate having a coverlay film showed sufficient flexibility, and the adhesion between the circuit surface and the coverlay film was also good.

Example 4
The polyimide organic solvent solution obtained in Example 1 was applied to a glass plate, heated on a hot plate at 90 ° C. for 1 hour to evaporate the solvent, and then peeled off from the glass plate to obtain a self-supporting film. The self-supporting film was fixed to a stainless steel fixing jig and heated in a hot air dryer at 220 ° C. for 2 hours to evaporate the solvent, thereby obtaining a light brown flexible polyimide film having a thickness of 30 μm. The obtained adhesive polyimide film was sandwiched between copper foil 3EC-VLP and Kapton 100H film, and thermocompression bonded with a hot press set at 330 ° C. for 30 minutes to obtain a flexible copper-clad laminate. Table 3 shows the adhesive strength of the flexible copper-clad laminate.

Comparative Example 2
The polyamic acid adhesive solution obtained in Comparative Example 1 was applied to a glass plate, heated on a hot plate at 90 ° C. for 1 hour to evaporate the solvent, and then peeled off from the glass plate to obtain a self-supporting film. This self-supporting film is fixed to a stainless steel fixing jig in a hot air dryer at 100 ° C. for 3 hours, 200 ° C. for 3 hours, 250 ° C. for 2 hours, 300 ° C. for 1 hour, and 400 ° C. for 1 hour. The solvent was evaporated by heating to obtain a brown and flexible adhesive polyimide film having a thickness of 30 μm. The obtained adhesive polyimide film was sandwiched between copper foil 3EC-VLP and Kapton 100H film, and thermocompression bonded with a hot press set at 330 ° C. for 30 minutes to obtain a flexible copper-clad laminate. Table 3 shows the adhesive strength of the flexible copper-clad laminate.

Copper foil used: 3EC-VLP (thickness 18 μm) manufactured by Mitsui Kinzoku Co., Ltd.
Polyimide film used: Kapton 100H manufactured by Toray DuPont Co., Ltd. (thickness 25 μm)
CTDA: 1,2,4,5-cyclohexanetetracarboxylic dianhydride
PMDA: pyromellitic dianhydride
ODA: 4,4'-diaminodiphenyl ether

Example 5
The polyimide organic solvent solution obtained in Example 2 was applied to a glass plate, heated on a hot plate at 90 ° C. for 1 hour to evaporate the solvent, and then peeled off from the glass plate to obtain a self-supporting film. This self-supporting film was fixed to a stainless steel fixing jig and heated in a hot air dryer at 220 ° C. for 2 hours to evaporate the solvent, thereby obtaining a colorless, transparent and flexible 30 μm thick adhesive polyimide film. Using the obtained adhesive polyimide film as an adhesive cover lay film, the circuit surface of a two-layer flexible printed wiring board (Viroflex) made of a copper layer / polyimide film is heated for 30 minutes at 280 ° C. Thermocompression bonding was performed. The copper clad laminate having a coverlay film showed sufficient flexibility, and the adhesion between the circuit surface and the coverlay film was also good.

Example 6
The polyimide organic solvent solution obtained in Example 1 was applied to a glass plate, heated on a hot plate at 90 ° C. for 1 hour to evaporate the solvent, and then peeled off from the glass plate to obtain a self-supporting film. This self-supporting film was fixed on a stainless steel fixing jig and heated in a hot air dryer at 220 ° C. for 2 hours to evaporate the solvent, thereby obtaining a colorless, transparent and flexible adhesive polyimide film having a thickness of 30 μm. Using the obtained adhesive polyimide film as an adhesive coverlay film, the heat treatment set at 330 ° C. for 30 minutes on the circuit surface of a two-layer flexible printed wiring board (Viroflex) composed of a copper layer / polyimide film. Thermocompression bonding was performed. The copper clad laminate having a coverlay film showed sufficient flexibility, and the adhesion between the circuit surface and the coverlay film was also good.

Example 7
Using the organic solvent solution of polyimide obtained in Example 1 as a cover coating agent, a thickness of 200 μm using a doctor blade on the circuit surface of a two-layer flexible printed wiring board (Viroflex) made of a copper layer / polyimide film. It was applied. After drying on a hot plate at 90 ° C. for 1 hour, it was further dried at 220 ° C. for 1 hour in a hot air dryer to form a cover coat layer having a thickness of 30 μm. The cover coat layer showed sufficient flexibility and also had good adhesion to the printed wiring board.

Example 8
Using a doctor blade on the circuit surface of a two-layer flexible printed wiring board (Viloflex) made of a copper layer / polyimide film using the polyimide organic solvent solution obtained in Example 2 as a cover coating agent, a thickness of 200 μm It was applied to. After drying on a hot plate at 90 ° C. for 1 hour, it was further dried at 220 ° C. for 1 hour in a hot air dryer to form a cover coat layer having a thickness of 30 μm. The cover coat layer showed sufficient flexibility and also had good adhesion to the printed wiring board.

Comparative Example 3
Using the polyamic acid adhesive solution obtained in Comparative Example 1 as a cover coating agent, a doctor blade is used on the circuit surface of a two-layer flexible printed wiring board (Viroflex) made of a copper layer / polyimide film to a thickness of 200 μm. It was applied. After drying on a hot plate at 50 ° C for 1 hour, further heating in a hot air dryer at 100 ° C for 3 hours, 200 ° C for 3 hours, 250 ° C for 2 hours, 300 ° C for 1 hour, and 400 ° C for 1 hour Then, an imidization treatment was performed to form a cover coat layer. The cover coat layer did not adhere to the printed wiring board, and the strength was insufficient.

Comparative Example 4
The polyamic acid adhesive solution obtained in Comparative Example 1 was applied to a glass plate, heated on a hot plate at 90 ° C. for 1 hour to evaporate the solvent, and then peeled off from the glass plate to obtain a self-supporting film. This self-supporting film is fixed on a stainless steel fixture and heated in a hot air dryer at 100 ° C. for 3 hours, 200 ° C. for 3 hours, 250 ° C. for 2 hours, 300 ° C. for 1 hour, and 400 ° C. for 1 hour. Then, the solvent was evaporated to obtain a brown and flexible adhesive polyimide film having a thickness of 30 μm. Using the obtained adhesive polyimide film as an adhesive cover lay film, the circuit surface of a two-layer flexible printed wiring board (Viroflex) made of a copper layer / polyimide film is heated for 30 minutes at 280 ° C. Thermocompression bonding was performed. The coverlay film did not adhere to the printed wiring board, and the strength was insufficient.

Example 9
The adhesive polyimide film obtained in Example 4 was obtained by using a glass cloth base epoxy resin rigid printed wiring board (manufactured by Fujitsu Interconnect Technologies Ltd., NEMA: FR-4) and a copper layer / polyimide film. The flexible rigid copper-clad laminate was obtained by sandwiching it between the two-layer flexible printed wiring board (Viroflex) and the circuit surface of the two-layered flexible printed wiring board and thermocompression bonding with a hot press set at 330 ° C. for 30 minutes. This flexible rigid copper-clad laminate did not have non-adhered portions such as bubbles and had a good adhesion state.

Example 10
Using a polyimide organic solvent solution obtained in Example 1 as a cover coating agent, a thickness of 200 μm using a doctor blade on the circuit surface of an epoxy resin rigid printed wiring board (NEMA: FR-4) of a glass cloth substrate It was applied to. After drying on a hot plate at 90 ° C. for 1 hour, it was further dried at 220 ° C. for 1 hour in a hot air dryer to form a cover coat layer having a thickness of 30 μm. Adhesion between the cover coat layer and the printed wiring board was good.

Example 11
The polyimide organic solvent solution obtained in Example 1 was applied to a glass plate, heated on a hot plate at 90 ° C. for 1 hour to evaporate the solvent, and then peeled off from the glass plate to obtain a self-supporting film. This self-supporting film was fixed to a stainless steel fixing jig and heated in a hot air dryer at 220 ° C. for 2 hours to evaporate the solvent, thereby obtaining two light brown flexible 30 μm thick adhesive polyimide films. Using the obtained adhesive polyimide film as a cover lay film, heat treatment set at 330 ° C. for 30 minutes on both circuit surfaces of a two-layer double-sided flexible printed wiring board (Viroflex) consisting of a copper layer / polyimide film A copper-clad laminate was obtained by thermocompression bonding. This copper clad laminate exhibited sufficient flexibility, and the adhesion between the circuit surface of the printed wiring board and the coverlay film was also good.
An acrylic resist was applied to both surfaces of the obtained copper-clad laminate with coverlay by screen printing, and pattern exposure and development were performed to form a resist pattern. Next, this laminate was immersed in an N-methyl-2-pyrrolidone bath at 80 ° C. for 10 minutes, and then taken out and washed with water. Next, the laminate was immersed in an aqueous resist stripping solution bath at 40 ° C. for 10 minutes, and then taken out and washed with water. By this wet etching, the non-mask region of the coverlay was removed in a good shape.

Example 12
The polyimide solution obtained in Example 2 was applied to a glass plate, heated on a hot plate at 90 ° C. for 1 hour to evaporate the solvent, and then peeled off from the glass plate to obtain a self-supporting film. The self-supporting film was fixed on a stainless steel fixing jig and heated in a hot air dryer at 220 ° C. for 1 hour to further evaporate the solvent, thereby obtaining a colorless and transparent adhesive polyimide film having a thickness of 30 μm. Next, the obtained polyimide film was immersed in an aqueous solution containing 5 mol / L hydrazine and 1 mol / L sodium hydroxide at 25 ° C. for 1 minute and washed with water. After drying this film, it is put into a high-frequency sputtering device, and copper is sputtered for 20 minutes at 0.1 Pa, substrate temperature of 100 ° C., power density of 60 kW / m ² , and applied voltage of ² kV in the presence of Ar gas, and the thickness is deposited on the polyimide film. A 0.6 μm copper thin film was formed.
Furthermore, this polyimide film with a copper thin film was immersed in a copper plating bath made of an aqueous solution containing 100 g / L of copper sulfate and 120 g / L of 98% sulfuric acid, and electroplated at a current density of 1 A / dm ² at 25 ° C. for 20 minutes. Went. The total thickness of the sputtering copper film and the electrolytic copper plating film formed on the film was 8 μm.
After superimposing a Kapton 100H film on the polyimide surface of the polyimide layer / copper layer laminate obtained in this way, a copper-clad laminate was obtained by thermocompression with a hot press set at 280 ° C. for 30 minutes. It was. The adhesive strength between the polyimide layer and the Kapton film was 1.43 kgf / cm ² , and the adhesiveness was good.

Claims (16)

A metal-clad laminate comprising at least one polyimide layer, at least one insulating substrate, and at least one metal layer, wherein the polyimide layer is made of polyimide having a repeating unit represented by the general formula I A metal-clad laminate characterized by comprising:

(In the formula, R is a tetravalent group derived from cyclohexane.

Or

It is a bivalent group represented by these. ) The metal-clad laminate according to claim 1, wherein the polyimide layer is formed on the surface of the insulating substrate, the metal layer, or both. The metal-clad laminate according to claim 1, wherein the polyimide layer is disposed between the insulating substrate and the metal layer. The polyimide layer is an adhesive layer formed by applying an organic solvent solution of the polyimide to the surface of the insulating substrate, the metal layer, or both, and evaporating the solvent. The metal-clad laminate according to any one of claims 1 to 3. The metal-clad laminate according to claim 1, wherein the polyimide layer is an adhesive polyimide film made of the polyimide. The metal-clad laminate according to claim 1, wherein the polyimide layer is a surface layer of the metal-clad laminate. The metal-clad laminate according to claim 6, wherein the polyimide layer is a cover coat layer formed by applying an organic solvent solution of the polyimide and evaporating the solvent. The metal-clad laminate according to claim 6, wherein the polyimide layer is a coverlay film made of the polyimide. The metal-clad laminate according to claim 6, wherein the polyimide layer is patterned by a wet etching method using an aprotic polar organic solvent as an etchant. The polyimide layer is disposed between the insulating substrate and the metal layer, and an adhesive layer formed by applying an organic solvent solution of the polyimide and evaporating the solvent, or the polyimide The metal-clad laminate according to claim 1, wherein the metal-clad laminate is an adhesive polyimide film. The metal-clad laminate according to claim 1, wherein the polyimide layer is disposed on a circuit surface and / or a non-circuit surface of a printed wiring board composed of the insulating base and the metal layer. The metal-clad laminate according to claim 1, wherein an insulating base material is further disposed on the polyimide layer. The metal-clad laminate according to claim 11, further comprising a printed wiring board disposed on the polyimide layer. The metal-clad laminate according to claim 1, wherein the polyimide has a glass transition temperature in the range of 250 to 320 ° C. The metal-clad laminate according to claim 1, wherein the polyimide has a dielectric constant at 10 GHz of 3.2 or less. The polyimide layer is formed by applying an organic solvent solution of the polyimide to the surface of the insulating substrate, the metal layer, or both, and drying, and the organic solvent solution is an organic diamine component. Addition of tetracarboxylic acid component to solvent solution, or addition of diamine component to organic solvent solution of tetracarboxylic acid component and reaction at a temperature of 80 ° C or less, azeotropic dehydration to polyamic acid solution of reaction intermediate obtained The metal-clad laminate according to claim 1, wherein the metal-clad laminate is obtained by performing a dehydration reaction after removing the generated water from the system azeotropically after adding the solvent .