CN112601656A

CN112601656A - Method for manufacturing metal-clad laminate and method for manufacturing circuit board

Info

Publication number: CN112601656A
Application number: CN201980055481.7A
Authority: CN
Inventors: 山田裕明; 平石克文; 西山哲平; 安达康弘
Original assignee: Nippon Steel and Sumikin Chemical Co Ltd
Current assignee: Nippon Steel Chemical and Materials Co Ltd
Priority date: 2018-09-28
Filing date: 2019-09-10
Publication date: 2021-04-02
Also published as: KR20210068022A; TW202026151A; WO2020066595A1; CN115971017B; CN115971017A

Abstract

The method of manufacturing the metal clad laminate 100 includes: a step of forming a first polyamide resin layer 20A on the metal foil 10A; a step of imidizing the polyamic acid in the first polyamide resin layer 20A to form a first polyimide layer 20; a step of performing surface treatment on the first polyimide layer 20; a step of forming a second polyamide resin layer 30A on the first polyimide layer 20; and a step of imidizing the polyamic acid in the second polyamide resin layer 30A to form a second polyimide layer 30 and an insulating resin layer 40. The thickness (L1) of the first polyimide layer 20 is in the range of 0.5 to 100 [ mu ] m, the thickness (L) of the entire insulating resin layer 40 is in the range of 5 to less than 200 [ mu ] m, and the ratio (L/L1) is in the range of more than 1 to less than 400.

Description

Method for manufacturing metal-clad laminate and method for manufacturing circuit board

Technical Field

The present invention relates to a method for manufacturing a metal-clad laminate that can be used as a material for a circuit board or the like, and a method for manufacturing a circuit board.

Background

In recent years, with the progress of downsizing, weight saving, and space saving of electronic devices, there has been an increasing demand for a Flexible circuit board (FPC) that is thin and lightweight, has flexibility, and has excellent durability even when repeatedly bent. Since FPCs can be mounted three-dimensionally and at high density even in a limited space, their applications are gradually expanding in, for example, the wiring of electronic devices such as Hard Disk Drives (HDDs), Digital Video Disks (DVDs), mobile phones, and smart phones, and in parts such as cables and connectors. Polyimide resins having excellent heat resistance and adhesion have attracted attention as insulating resins used for FPCs.

As a method for manufacturing a metal-clad laminate as an FPC material, there are known: a casting (cast) method in which a resin solution of polyamic acid is applied to a metal foil to form a polyimide precursor layer, and then imidized to form a polyimide layer. In the case of producing a metal-clad laminate having a plurality of polyimide layers as insulating resin layers by a casting method, the following operations are generally performed: a plurality of polyimide precursor layers are sequentially formed on a base material such as a copper foil, and then, these layers are collectively imidized. However, if a plurality of polyimide precursor layers are imidized at once, the solvent or imidized water in the polyimide precursor layers cannot be completely removed, and foaming or peeling between the polyimide layers occurs due to the residual solvent or imidized water, which causes a problem of lowering the yield.

The problem of foaming or peeling can be solved by repeating the following operations: the polyimide precursor layer is imidized layer by layer, and a resin solution of polyamic acid is applied thereon. However, if a resin solution of polyamic acid is further applied onto the imidized polyimide layer and imidized, it is difficult to sufficiently obtain interlayer adhesiveness. In the prior art, there are proposed: before the resin liquid of polyamic acid is applied, the surface of a polyimide film or a polyimide layer of a substrate is subjected to surface treatment such as corona treatment or plasma treatment, thereby improving the adhesion between layers (for example, patent documents 1 and 2).

Documents of the prior art

Patent document

Patent document 1: japanese patent No. 5615253

Patent document 2: japanese patent No. 5480490

Disclosure of Invention

Problems to be solved by the invention

The purpose of the invention is as follows: in the case of producing a metal-clad laminate having a plurality of polyimide layers as insulating resin layers by a casting method, the adhesion between the polyimide layers is improved while suppressing foaming.

Means for solving the problems

The present inventors have found that the adhesion between polyimide layers can be improved while suppressing foaming by controlling the thickness of a plurality of polyimide layers formed by a casting method, and have completed the present invention.

That is, a method for manufacturing a metal-clad laminate according to the present invention is a method for manufacturing a metal-clad laminate including: the polyimide film includes an insulating resin layer including a plurality of polyimide layers, and a metal layer laminated on at least one surface of the insulating resin layer.

The method for manufacturing a metal-clad laminate of the present invention includes the following steps 1 to 5:

step 1) a step of forming a single or multi-layer first polyamide resin layer by coating a solution of polyamide acid on the metal layer;

step 2) a step of imidizing the polyamic acid in the first polyamide resin layer to form a first polyimide layer including a single layer or a plurality of layers;

step 3) a step of performing surface treatment on the surface of the first polyimide layer;

step 4) a step of forming a single or multiple layers of a second polyamide resin layer by further coating a solution of polyamide acid on the first polyimide layer; and

step 5) imidizing the polyamic acid in the second polyimide resin layer to form a second polyimide layer including a single layer or a plurality of layers, and forming the insulating resin layer in which the first polyimide layer and the second polyimide layer are laminated.

In the method for producing a metal-clad laminate of the present invention, the thickness (L1) of the first polyimide layer is in the range of 0.5 μm or more and 100 μm or less, the thickness (L) of the entire insulating resin layer is in the range of 5 μm or more and less than 200 μm, and the ratio (L/L1) of L to L1 is in the range of more than 1 and less than 400.

In the method for producing a metal-clad laminate of the present invention, the polyimide constituting the layer in contact with the metal layer in the first polyimide layer may be a thermoplastic polyimide.

In the method for producing a metal-clad laminate of the present invention, the moisture permeability of the metal layer may be 100g/m at 25 ℃ and a thickness of 25 μm²And/24 hr or less.

The method for manufacturing a circuit board of the present invention includes: and a step of performing wiring circuit processing on the metal layer of the metal-clad laminate manufactured by the method.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the method of the present invention, a metal-clad laminate having an insulating resin layer in which foaming is suppressed and adhesion between polyimide layers is excellent can be produced by a casting method.

Drawings

Fig. 1 is a step diagram showing the procedure of a method for manufacturing a metal-clad laminate according to a first embodiment of the present invention.

Fig. 2 is a step diagram showing the procedure of a method for manufacturing a metal-clad laminate according to a second embodiment of the present invention.

Fig. 3 is an explanatory diagram of a target (target) for position measurement used in the measurement of the dimensional change rate after etching.

Fig. 4 is an explanatory view of an evaluation sample used for measuring the dimensional change rate after etching.

Detailed Description

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[ first embodiment ]

A method of manufacturing a metal clad laminate according to a first embodiment of the present invention is a method of manufacturing a metal clad laminate including: the polyimide film includes an insulating resin layer including a plurality of polyimide layers, and a metal layer laminated on at least one surface of the insulating resin layer.

Fig. 1 is a step diagram showing the main sequence of the method for manufacturing a metal-clad laminate according to the first embodiment. The method of the present embodiment includes the following steps 1 to 5. In fig. 1, the numbers adjacent to the arrows indicate step 1 to step 5.

Step 1)

In step 1, a solution of polyamic acid is applied to a metal foil 10A to be a metal layer 10, thereby forming a single-layer or multi-layer first polyamide resin layer 20A. The method of applying the resin solution of polyamic acid on the metal foil 10A by the casting method is not particularly limited, and the coating may be performed by a coater such as a comma (comma), a die (die), a doctor blade (knife), or a die lip (lip).

When the first polyamide resin layer 20A is formed in a plurality of layers, for example, the following method can be used: a method of repeating the operation of applying and drying the solution of polyamic acid to the metal foil 10A plurality of times; or a method of coating polyamic acid on the metal foil 10A in a state of being laminated in a plurality of layers by multilayer extrusion and drying.

In step 1, it is preferable to form the first polyamide resin layer 20A so that the thickness (L1) of the first polyimide layer 20 cured in step 2 is in the range of 0.5 μm to 100 μm, as will be described later. In the casting method, the resin layer of the polyamic acid is imidized in a state of being fixed to the metal foil 10A, and therefore, the change in expansion and contraction of the polyimide layer during the imidization can be suppressed, and the thickness or dimensional accuracy can be maintained.

The material of the metal foil 10A is not particularly limited, and examples thereof include: copper, stainless steel, iron, nickel, beryllium, aluminum, zinc, indium, silver, gold, tin, zirconium, tantalum, titanium, lead, magnesium, manganese, alloys of these, and the like. Among them, copper or a copper alloy is particularly preferable. The copper foil may be a rolled copper foil or an electrolytic copper foil, and a commercially available copper foil is preferably used.

In the present embodiment, the metal layer 10 used for the production of FPC has a thickness preferably in the range of 3 to 80 μm, more preferably in the range of 5 to 30 μm.

The surface of the metal foil 10A used as the metal layer 10 may be subjected to surface treatment such as rust prevention treatment, finishing (sizing), aluminum alcoholate, aluminum chelate, silane coupling agent, and the like. The metal foil 10A may be in the form of a cut sheet, a roll, or a circular strip, and in order to obtain productivity, it is efficient to form the metal foil in the form of a roll or a circular strip and to form the metal foil in a form capable of continuous production. Further, from the viewpoint of more significantly exhibiting the effect of improving the accuracy of the wiring pattern on the circuit board, the metal foil 10A is preferably formed in a long roll shape.

The moisture permeability of the metal layer 10 is preferably 100g/m at 25 ℃ and a thickness of 25 μm, for example²And/24 hr or less. When the moisture permeability of the metal layer 10 is low and the solvent or the imidized water is hard to come off from the metal layer 10 side, the effect of the method of the present embodiment can be greatly exhibited.

Step 2)

In step 2, the polyamic acid in the first polyamide resin layer 20A formed in step 1 is imidized to form a first polyimide layer 20 including a single layer or a plurality of layers. By imidizing the polyamic acid contained in the first polyamide resin layer 20A, most of the solvent or imidized water contained in the first polyamide resin layer 20A can be removed.

The method for imidizing the polyamic acid is not particularly limited, and for example, heat treatment in which heating is performed at a temperature in the range of 80 to 400 ℃ for a time in the range of 1 to 60 minutes is preferable. In order to suppress oxidation of the metal layer 10, the heat treatment is preferably performed in a low-oxygen atmosphere, specifically, in an inert gas atmosphere such as nitrogen or a rare gas, a reducing gas atmosphere such as hydrogen, or in a vacuum.

Step 3)

In step 3, the surface of the first polyimide layer 20 is subjected to surface treatment.

The surface treatment is not particularly limited as long as it can improve the interlayer adhesiveness between the first polyimide layer 20 and the second polyimide layer 30, and examples thereof include: plasma treatment, corona treatment, flame treatment, ultraviolet treatment, ozone treatment, electron beam treatment, and radiationTreatment, sand blasting, fine line (hairline) processing, embossing, chemical treatment, steam treatment, surface grafting treatment, electrochemical treatment, undercoating treatment, and the like. In particular, when the first polyimide layer 20 is a thermoplastic polyimide layer, surface treatment such as plasma treatment, corona treatment, or ultraviolet treatment is preferable, and the conditions are preferably set to 300W/min/m²The following.

Step 4)

In step 4, a solution of polyamic acid is further applied on the first polyimide layer 20 surface-treated in step 3 to laminate and form a single or multiple second polyamide resin layer 30A. The method of applying the resin solution of polyamic acid on the first polyimide layer 20 by the casting method is not particularly limited, and for example, the coating can be performed by a coater such as a die wheel, a die, a doctor blade, or a die lip.

When the second polyamide resin layer 30A is formed in a plurality of layers, for example, the following method can be used: a method of repeating the operation of coating the solution of polyamic acid on the first polyimide layer 20 and drying a plurality of times; or a method of simultaneously coating polyamic acid on the first polyimide layer 20 in a state of being laminated in multiple layers by multilayer extrusion and drying.

In step 4, it is preferable to form the second polyamide resin layer 30A so that the thickness (L) of the entire insulating resin layer 40 after the next step 5 is in the range of 5 μm or more and less than 200 μm, as will be described later.

Step 5)

In step 5, the polyamic acid contained in the second polyimide resin layer 30A is imidized to be changed into the second polyimide layer 30, and the insulating resin layer 40 including the first polyimide layer 20 and the second polyimide layer 30 is formed.

In step 5, the polyamic acid contained in the second polyamide resin layer 30A is imidized to synthesize polyimide. The method of imidization is not particularly limited, and may be carried out under the same conditions as in step 2.

< any step >

The method of this embodiment may include any step other than the above.

Through the above steps 1 to 5, the metal-clad laminate 100 having the insulating resin layer 40 excellent in adhesion between the first polyimide layer 20 and the second polyimide layer 30 can be manufactured. In the method of the present embodiment, even when the first polyimide layer 20 is formed on the metal layer 10 by the casting method, the solvent or the imidized water can be removed by imidizing before the second polyimide layer 30 is formed, and thus problems such as foaming and interlayer peeling do not occur. In addition, by performing surface treatment on the first polyimide layer 20 before forming the second polyamide resin layer 30A, adhesion between the first polyimide layer 20 and the second polyimide layer 30 can be ensured.

In the insulating resin layer 40 of the metal-clad laminate 100 produced by the method of the present embodiment, the thickness (L1) of the first polyimide layer is in the range of 0.5 μm or more and 100 μm or less.

Here, when the first polyimide layer 20 is a single layer, the thickness (L1) thereof is preferably in the range of 0.5 μm or more and 5 μm or less, and more preferably in the range of 1 μm or more and 3 μm or less. In this case, in step 2, the solvent or the imidization water can be substantially removed by curing the film in a thin state in which the thickness (L1) after imidization is 5 μm or less. In addition, when the first polyimide layer 20 is a single layer, the thickness (L1) is controlled to be 5 μm or less, so that the residual polyamic acid at the interface with the metal layer 10, which is one of the causes of the decrease in peel strength (peel) from the metal layer 10, disappears, and complete imidization can be performed, and thus the peel strength can be improved. If the thickness (L1) is less than 0.5 μm, the adhesion to the metal layer 10 is reduced, and the insulating resin layer 40 is easily peeled off.

On the other hand, when the first polyimide layer 20 includes a plurality of layers, the thickness (L1) thereof is preferably in the range of 5 μm or more and 100 μm or less, and more preferably in the range of 25 μm or more and 100 μm or less. When the first polyimide layer 20 includes a plurality of layers, foaming is likely to occur if the thickness (L1) exceeds 100 μm.

The thickness (L) of the entire insulating resin layer 40 is in the range of 5 μm or more and less than 200 μm.

Here, when the first polyimide layer 20 is a single layer, the thickness (L) of the entire insulating resin layer 40 is preferably in the range of 5 μm or more and less than 30 μm, and more preferably in the range of 10 μm or more and 25 μm or less. When the first polyimide layer 20 is a single layer, if the thickness (L) of the entire insulating resin layer 40 is less than 5 μm, the effect of suppressing foaming, which is the effect of the present invention, is not easily exhibited, and the effect of improving dimensional stability is also not easily obtained.

On the other hand, when the first polyimide layer 20 includes a plurality of layers, the thickness (L) of the entire insulating resin layer 40 is preferably in the range of 10 μm or more and less than 200 μm, and more preferably in the range of 50 μm or more and less than 200 μm. When the first polyimide layer 20 includes a plurality of layers, foaming is likely to occur if the thickness (L) of the entire insulating resin layer 40 is 200 μm or more.

As described above, since the thickness (L1) of the first polyimide layer 20 and the thickness (L) of the entire insulating resin layer 40 affect the suppression of foaming, the improvement of dimensional stability, and the adhesion to the metal layer 10, the ratio (L/L1) of the thickness (L) to the thickness (L1) is set to be in a range of more than 1 and less than 400.

The ratio (L/L1) may preferably be in the range of more than 1 and less than 60, more preferably 4 or more and 45 or less, and most preferably 5 or more and 30 or less.

Further, the insulating resin layer 40 may include a polyimide layer other than the first polyimide layer 20 and the second polyimide layer 30. The polyimide layer constituting the insulating resin layer 40 may also 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, calcium fluoride, and the like. These may be used alone or in combination of two or more.

< polyimide >

Next, a preferred polyimide for forming the first polyimide layer 20 and the second polyimide layer 30 will be described. In the formation of the first polyimide layer 20 and the second polyimide layer 30, an acid anhydride component and a diamine component, which are generally used as raw materials for synthesizing polyimide, may be used without particular limitation.

In the metal-clad laminate 100, the polyimide constituting the first polyimide layer 20 may be either a thermoplastic polyimide or a non-thermoplastic polyimide, and is preferably a thermoplastic polyimide because adhesion to the metal layer 10 serving as a base is easily ensured.

The polyimide constituting the second polyimide layer 30 may be either a thermoplastic polyimide or a non-thermoplastic polyimide, and when a non-thermoplastic polyimide is used, the effects of the present invention can be remarkably exhibited.

That is, even when a resin layer of a polyamic acid that is a precursor of a non-thermoplastic polyimide is laminated on a polyimide layer having been imidized by a method such as a casting method and imidized, adhesion between polyimide layers is hardly obtained in general. However, in the present embodiment, by laminating the second polyamide resin layer 30A after the surface treatment of the first polyimide layer 20 as described above, excellent adhesion can be obtained between the layers of the first polyimide layer 20 regardless of whether the polyimide constituting the second polyimide layer 30 is thermoplastic or non-thermoplastic. Further, by using a non-thermoplastic polyimide as the second polyimide layer 30, it is possible to function as a main layer (base layer) that secures the mechanical strength of the polyimide layer in the metal laminate 100.

From the above, in the metal-clad laminate 100, the most preferable configuration is: a structure in which a thermoplastic polyimide layer is laminated as the first polyimide layer 20 and a non-thermoplastic polyimide layer is laminated as the second polyimide layer 30 is formed.

Among the polyimides, there are low thermal expansion polyimides and high thermal expansion polyimides, and generally, thermoplastic polyimides have high thermal expansion properties, while non-thermoplastic polyimides have low thermal expansion properties. For example, in the case where the first polyimide layer 20 is a thermoplastic polyimide layer, the thermal expansion coefficient may preferably be set to more than 30 × 10^-6 80X 10 and/or K^-6In the range of/K or less. By setting the thermal expansion coefficient of the thermoplastic polyimide layer within the above range, adhesion with the metal layer 10 as the first polyimide layer 20 can be ensured. Further, by providing the second polyimide layer 30 as a polyimide layer having low expansibility, it is possible to function as a main layer (foundation layer) for securing dimensional stability of the polyimide layer in the metal-clad laminate 100. Specifically, the low expansion polyimide layer may have a thermal expansion coefficient of 1 × 10^-6(1/K)～30×10^-6(1/K), preferably 1X 10^-6(1/K)～25×10^-6(1/K), more preferably 10X 10^-6(1/K)～25×10^-6(1/K). Further, since the non-thermoplastic polyimide has low thermal expansion, the thermal expansion coefficient can be suppressed low by increasing the thickness ratio of the non-thermoplastic polyimide layer. The first polyimide layer 20 and the second polyimide layer 30 can be made of polyimide layers having a desired thermal expansion coefficient by appropriately changing the combination of raw materials used, the thickness, and the drying/curing conditions.

The term "thermoplastic polyimide" generally means a polyimide whose glass transition temperature (Tg) is clearly observed, but in the present invention means that the storage elastic modulus at 30 ℃ measured with a Dynamic viscoelasticity measuring apparatus (Dynamic Mechanical Analyzer, DMA)) is 1.0 × 10⁹Pa or more and a storage elastic coefficient of less than 1.0X 10 at 350 DEG C⁸Pa of a polyimide. The term "non-thermoplastic polyimide" generally means a polyimide which does not exhibit softening or adhesion even when heated, but in the present invention means a polyimide having a storage elastic modulus at 30 ℃ of 1.0X 10 as measured by a dynamic viscoelasticity measuring apparatus (DMA)⁹Pa or more and a storage modulus of elasticity at 350 ℃ of 1.0X 10⁸Polyimide having Pa or more.

As the diamine compound to be a raw material of the polyimide, an aromatic diamine compound, an aliphatic diamine compound, or the like can be used, and for example, NH is preferable₂-Ar1-NH₂An aromatic diamine compound represented by the formula (I). Ar1 is selected from the group represented by the following formula. Ar1 may have a substituentThe substituent may be a lower alkyl group or a lower alkoxy group having 1 to 6 carbon atoms. These aromatic diamine compounds may be used alone, or two or more thereof may be used in combination.

[ solution 1]

The acid anhydride to be reacted with the diamine compound is preferably an aromatic tetracarboxylic acid anhydride in terms of ease of synthesis of the polyamic acid. The aromatic tetracarboxylic anhydride is not particularly limited, and is preferably, for example, O (CO)₂Ar2(CO)₂And O is a compound represented by formula (I). Ar2 may be a tetravalent aromatic group represented by the following formula. Acid anhydride group [ (CO)₂O]The substitution position(s) of (b) is an arbitrary position, preferably a symmetrical position. Ar2 may have a substituent, preferably none, or in the case of having it, the substituent may be a lower alkyl group having 1 to 6 carbon atoms.

[ solution 2]

(Synthesis of polyimide)

The polyimide constituting the polyimide layer can be produced by: the acid anhydride and the diamine are reacted in a solvent, and after the precursor resin is produced, ring closure is performed by heating. For example, a polyamic acid as a precursor of a polyimide is obtained by dissolving an acid anhydride component and a diamine component in an organic solvent in approximately equimolar amounts, and stirring the solution at a temperature in the range of 0 to 100 ℃ for 30 minutes to 24 hours to perform a polymerization reaction. During the reaction, the reaction components are dissolved in the organic solvent so that the produced precursor is in the range of 5 to 30 wt%, preferably 10 to 20 wt%. Examples of the organic solvent used in the polymerization reaction include: n, N-dimethylformamide, N-dimethylacetamide (DMAc), N-methyl-2-pyrrolidone, 2-butanone, dimethyl sulfoxide, dimethyl sulfate, cyclohexanone, dioxane, tetrahydrofuran, diglyme (diglyme), triglyme, and the like. Two or more of these solvents may be used in combination, and an aromatic hydrocarbon such as xylene or toluene may be used in combination. The amount of the organic solvent used is not particularly limited, but is preferably adjusted so that the concentration of the polyamic acid solution (polyimide precursor solution) obtained by the polymerization reaction is about 5 to 30 wt%. The synthesized precursors are generally advantageously used as a reaction vehicle solution, which may be concentrated, diluted or replaced by other organic vehicles as desired. In addition, the precursor is generally used advantageously because of excellent solvent solubility.

In the synthesis of polyimide, only one of the acid anhydride and the diamine may be used, or two or more thereof may be used in combination. The thermal expansion property, adhesion property, storage modulus of elasticity, glass transition temperature, and the like can be controlled by selecting the types of the acid anhydride and the diamine, or the molar ratio of each of the two or more types of the acid anhydride and the diamine. In the polyimide, when the polyimide has a plurality of structural units, the polyimide may be present in the form of blocks or may be present randomly, preferably randomly.

As described above, the metal-clad laminate obtained in the present embodiment can improve the reliability of electronic equipment by being used as a circuit board material represented by FPC while being excellent in adhesion between the first polyimide layer 20 and the second polyimide layer 30.

In the first embodiment, the imidized polyimide is subjected to surface treatment in order to obtain interlayer adhesiveness. When the surface treatment is performed, an apparatus for the surface treatment is required, and the number of steps is increased in some cases. Therefore, in the second embodiment of the present invention described below, the next polyimide precursor layer is laminated in a state where the polyimide precursor layer formed by the casting method is half-cured, whereby foaming can be suppressed and adhesion between polyimide layers can be improved without requiring a special step such as surface treatment.

[ second embodiment ]

A method of manufacturing a metal clad laminate according to a second embodiment of the present invention is a method of manufacturing a metal clad laminate including: the polyimide film includes an insulating resin layer including a plurality of polyimide layers, and a metal layer laminated on at least one surface of the insulating resin layer.

Fig. 2 is a step diagram showing the main sequence of the method for manufacturing a metal-clad laminate according to the second embodiment. The method of the present embodiment includes the following steps (a) to (d). In fig. 2, the english alphabet next to the arrow indicates step (a) to step (d).

In the present embodiment, the same configurations as those in the first embodiment may be omitted by referring to the first embodiment.

Step (a)

In step (a), a single or multiple layers of the first polyamide resin layer 20A are laminated by applying a solution of polyamic acid on the metal foil 10A to be the metal layer 10. The method of applying the resin solution of polyamic acid on the metal foil 10A by the casting method is not particularly limited, and for example, the coating can be performed by a coater such as a die wheel, a die, a doctor blade, or a die lip.

In step (a), the first polyamide resin layer 20A is preferably formed so that the thickness (L1) of the first polyimide layer 20 after curing in step (d) is in the range of 0.5 μm to 10 μm, as will be described later. In the casting method, the resin layer of the polyamic acid is imidized in a state of being fixed to the metal foil 10A, and therefore, the change in expansion and contraction of the polyimide layer during the imidization can be suppressed, and the thickness or dimensional accuracy can be maintained.

The material, thickness, surface treatment, shape, form, and moisture permeability of the metal foil 10A are the same as those of the first embodiment.

Step (b)

And a step of forming a single-layer or multi-layer semi-cured resin layer 20B by partially imidizing the polyamic acid contained in the first polyamide resin layer 20A so that a weight loss rate in a temperature range from 100 ℃ to 360 ℃ measured by a thermogravimetric-Differential Thermal Analyzer (TG-DTA) is in a range of 0.1% to 20%.

In the step (b), most of the solvent or imidized water contained in the first polyamide resin layer 20A can be removed by semi-curing the polyamic acid contained in the first polyamide resin layer 20A. In addition, in the case of the semi-cured state, unlike the cured state in which imidization is completed, sufficient interlayer adhesiveness is obtained between the second polyimide layer 30 as an upper layer formed in the subsequent step (c) or step (d).

Here, the semi-cured state by partial imidization is a state in which imidization reaction is generated in the polyamic acid but not completed, unlike the simple dry state or the cured state in which imidization is completed. The degree of imidization can be evaluated, for example, by the weight loss rate in a temperature range from 100 ℃ to 360 ℃ measured by a thermogravimetric differential thermal analyzer (TG-DTA). When the weight loss rate in this temperature range is in the range of 0.1% to 20%, it is considered that the resin is in a semi-cured state by partial imidization. If the weight loss rate is less than 0.1%, imidization may excessively proceed, and sufficient interlayer adhesiveness may not be obtained. On the other hand, when the weight reduction rate exceeds 20%, imidization hardly proceeds and cannot be distinguished from simple drying, so that there is a high possibility that the solvent contained in the first polyamide resin layer 20A remains, and further, the amount of imidization water generated before imidization is completed is large, so that there is a concern that this may cause foaming. In the step (b), the degree of imidization is preferably adjusted so that the weight loss rate is in the range of 1% to 15%.

The degree of imidization can also be evaluated from the imidization ratio. In the step (B), the imidization ratio of the semi-cured resin layer 20B is preferably adjusted to be within a range of 20% to 95%, and more preferably adjusted to be within a range of 22% to 90%. If the imidization ratio is less than 20%, imidization hardly proceeds and cannot be distinguished from simple drying, so that there is a high possibility that the solvent contained in the first polyamide resin layer 20A remains, and further, the amount of imidization water generated before imidization is completed is large, so that foaming may be caused. On the other hand, if the imidization ratio exceeds 95%, imidization may progress excessively, and sufficient interlayer adhesiveness may not be obtained.

The imidization ratio can be calculated as follows: the infrared absorption spectrum of the resin layer was measured by an Attenuated Total Reflection (ATR) method using a Fourier transform infrared spectrophotometer to obtain a spectrum of 1009cm^-1Based on the benzene ring hydrocarbon bond of (1), and according to 1778cm^-1The absorbance derived from the imide group (b) was calculated. Here, the first polyamide resin layer 20A was subjected to a stepwise heat treatment from 120 ℃ to 360 ℃, and the imidization rate after the 360 ℃ heat treatment was assumed to be 100%.

The method for semi-curing the polyamic acid in the step (b) is not particularly limited, and for example, it is preferable that: and heat treatment in which the heating is carried out under temperature conditions in the range of 120 to 300 ℃, preferably in the range of 140 to 280 ℃ while adjusting the time so that the weight reduction rate or the imidization rate is attained. In order to suppress oxidation of the metal layer 10, the heat treatment is preferably performed in a low-oxygen atmosphere, and more specifically, in an inert gas atmosphere such as nitrogen or a rare gas, a reducing gas atmosphere such as hydrogen, or a vacuum.

Step (c)

In the step (c), a single or multiple second polyamide resin layer 30A is laminated by further applying a solution of polyamide acid on the semi-hardened resin layer 20B formed in the step (B). The method of applying the resin solution of polyamic acid on the semi-cured resin layer 20B by the casting method is not particularly limited, and the application can be performed by a coater such as a die wheel, a die, a doctor blade, or a die lip.

When the second polyamide resin layer 30A is formed in a plurality of layers, for example, the following method can be used: a method of repeating the operation of coating the solution of polyamic acid on the semi-cured resin layer 20B and drying the same a plurality of times; or a method of simultaneously coating polyamic acid on the semi-cured resin layer 20B in a state of being laminated in a plurality of layers by multilayer extrusion and drying.

In the step (c), the second polyamide resin layer 30A is preferably formed so that the thickness (L) of the entire insulating resin layer 40 after the step (d) is in the range of 10 μm to 200 μm, as will be described later.

Step (d)

In the step (d), the polyamic acid contained in the semi-cured resin layer 20B and the polyamic acid contained in the second polyimide resin layer 30A are imidized to be changed into the first polyimide layer 20 and the second polyimide layer 30, thereby forming the insulating resin layer 40.

In the step (d), the semi-cured resin layer 20B is imidized together with the polyamic acid contained in the second polyamide resin layer 30A to synthesize polyimide. The method of imidization is not particularly limited, and for example, heat treatment such as heating at a temperature in the range of 80 to 400 ℃ for a time in the range of 1 to 60 minutes can be suitably employed. In order to suppress oxidation of the metal layer 10, the heat treatment is preferably performed in a low-oxygen atmosphere, specifically, in an inert gas atmosphere such as nitrogen or a rare gas, a reducing gas atmosphere such as hydrogen, or in a vacuum. The end point of imidization in step (d) can be indicated by, for example: the weight loss rate in the temperature range from 100 ℃ to 360 ℃ measured by a thermogravimetric differential thermal analyzer (TG-DTA) is less than 0.1, or the imidization rate exceeds 95%.

< any step >

The method of this embodiment may include any step other than the above. For example, a step of surface-treating the surface of the semi-hardened resin layer 20B may be further included after the step (B) and before the step (c) within a range not to impair the effect of the invention. The surface treatment is not particularly limited as long as it can improve the interlayer adhesion between the first polyimide layer 20 and the second polyimide layer 30, and the same treatment as in the first embodiment can be exemplified.

By the steps (a) to (d), the metal-clad laminate 100 having the insulating resin layer 40 excellent in adhesion between the first polyimide layer 20 and the second polyimide layer 30 can be produced without causing a decrease in yield (throughput) due to an increase in the number of steps. In the method of the present embodiment, even when the first polyimide layer 20 is formed on the metal layer 10 by the casting method, the solvent or the imidized water can be removed by half-curing before the second polyimide layer 30 is formed, and thus problems such as foaming and interlayer peeling do not occur.

In the insulating resin layer 40 of the metal-clad laminate 100 produced by the method of the present embodiment, the thickness (L1) of the first polyimide layer 20 is preferably in the range of 0.5 μm or more and 10 μm or less, and more preferably in the range of 1 μm or more and 7 μm or less. In the step (b), most of the solvent and the imidized water can be removed by half-curing in a state where the thickness (L1) after imidization is 10 μm or less. When the thickness (L1) after imidization exceeds 10 μm, it becomes difficult to remove the solvent or the imidization water, and dimensional stability also deteriorates. If the thickness (L1) of the first polyimide layer 20 is less than 0.5 μm, the adhesion to the metal layer 10 is reduced, and the insulating resin layer 40 is easily peeled off.

The thickness (L) of the entire insulating resin layer 40 is preferably in the range of 10 μm to 200 μm, and more preferably in the range of 12 μm to 150 μm. If the thickness (L) is less than 10 μm, the effect of suppressing foaming is difficult to be exhibited, and the effect of improving dimensional stability is also difficult to be obtained. On the other hand, if the thickness (L) exceeds 200. mu.m, foaming tends to occur.

As described above, since the thickness (L1) of the first polyimide layer 20 and the thickness (L) of the entire insulating resin layer 40 affect suppression of foaming or improvement of dimensional stability, the ratio (L/L1) of the thickness (L) to the thickness (L1) is preferably in the range of more than 1 and less than 400, more preferably 4 to 200, and still more preferably 5 to 100.

< polyimide >

A preferred polyimide for forming the first polyimide layer 20 and the second polyimide layer 30 in the second embodiment will be described. In the formation of the first polyimide layer 20 and the second polyimide layer 30, an acid anhydride component and a diamine component, which are generally used as raw materials for synthesizing polyimide, may be used without particular limitation.

That is, even when a resin layer of a polyamic acid that is a precursor of a non-thermoplastic polyimide is laminated on a polyimide layer having been imidized by a method such as a casting method and imidized, adhesion between polyimide layers is hardly obtained in general. However, in the present embodiment, by laminating the second polyamide resin layer 30A in a state where the first polyamide resin layer 20A is half-cured as described above, excellent adhesion can be obtained between the layers of the first polyimide layer 20 regardless of whether the polyimide constituting the second polyimide layer 30 is thermoplastic or non-thermoplastic. Further, by using a non-thermoplastic polyimide as the second polyimide layer 30, it is possible to function as a main layer (base layer) that secures the mechanical strength of the polyimide layer in the metal laminate 100.

In the second embodiment, the contents of the synthesis of the diamine compound and the acid anhydride, which are raw materials of the polyimide, and the like are the same as those of the first embodiment.

As described above, the method for manufacturing a metal-clad laminate according to the second embodiment of the present invention includes the following steps (a) to (d):

a step (a) of forming a single or multiple first polyamide resin layers by laminating by coating a solution of polyamic acid on the metal layer;

a step (b) of forming a single-layer or multi-layer semi-cured resin layer by partially imidizing a polyamic acid contained in the first polyamide resin layer so that a weight loss rate in a temperature range from 100 ℃ to 360 ℃ measured by a thermogravimetric differential thermal analyzer (TG-DTA) is in a range of 0.1% to 20%;

a step (c) of forming a second polyamide resin layer of a single layer or a plurality of layers by further applying a solution of polyamide acid on the semi-hardened resin layer; and

and (d) forming the insulating resin layer by imidizing the polyamic acid contained in the semi-cured resin layer and the polyamic acid contained in the second polyamide resin layer.

In the method for producing a metal-clad laminate according to the second embodiment of the present invention, the imidization ratio in the step (b) may be in the range of 20% to 95%.

In the method for producing a metal-clad laminate according to the second embodiment of the present invention, the thickness (L1) of the resin layer formed of the first polyamide resin layer may be in the range of 0.5 μm or more and 10 μm or less, the thickness (L) of the entire insulating resin layer may be in the range of 10 μm or more and 200 μm or less, and the ratio (L/L1) of L to L1 may be in the range of more than 1 and less than 400.

In the method for producing a metal-clad laminate according to the second embodiment of the present invention, the polyimide constituting the layer in contact with the metal layer in the resin layer formed of the first polyamide resin layer may be a thermoplastic polyimide.

In the method for producing a metal-clad laminate according to the second embodiment of the present invention, the moisture permeability of the metal layer may be 100g/m at 25 ℃ and 25 μm in thickness²And/24 hr or less.

The method for manufacturing a metal-clad laminate according to the second embodiment of the present invention may further include a step of surface-treating the surface of the semi-cured resin layer after the step (b) and before the step (c).

A method for manufacturing a circuit board according to a second embodiment of the present invention includes: and a step of processing a wiring circuit to the metal layer of the metal-clad laminate manufactured by any one of the methods.

In the first embodiment, the imidized polyimide is subjected to surface treatment in order to obtain interlayer adhesiveness, but when the surface treatment is performed, equipment for the surface treatment is required and the number of steps is increased in some cases. Therefore, in the third and fourth embodiments of the present invention described below, the adhesion between polyimide layers can be improved without requiring a special step such as surface treatment by utilizing the interaction between the resin component of the polyimide precursor layer formed by the casting method and the resin component of the polyimide layer to be the base thereof.

[ third embodiment: production method of polyimide film

The method for producing a polyimide film of the third embodiment is a method for producing a polyimide film including: the polyimide film includes a first polyimide layer (A) and a second polyimide layer (B) laminated on at least one surface of the first polyimide layer (A). The polyimide film obtained in the present embodiment may have a polyimide layer other than the first polyimide layer (a) and the second polyimide layer (B), or may be laminated on an arbitrary substrate.

The method for producing a polyimide film of the present embodiment includes the following steps I to III.

(step I):

in step I, a first polyimide layer (a) containing a polyimide having a ketone group is prepared. The polyimide having a ketone group has a ketone group (-CO-) in its molecule. The ketone group is derived from an acid dianhydride and/or a diamine compound as a raw material of polyimide. That is, the polyimide constituting the first polyimide layer (a) contains a tetracarboxylic acid residue (1a) and a diamine residue (2a), and either or both of the tetracarboxylic acid residue (1a) and the diamine residue (2a) contain a residue having a ketone group.

In the present invention, "tetracarboxylic acid residue" represents a tetravalent group derived from tetracarboxylic dianhydride, and "diamine residue" represents a divalent group derived from a diamine compound. In addition, in the "diamine compound", hydrogen atoms in the two terminal amino groups may be substituted.

Examples of the residue having a ketone group contained in the tetracarboxylic acid residue (1a) include: and a residue derived from "tetracarboxylic dianhydride having a ketone group in the molecule", such as 3,3',4,4' -benzophenonetetracarboxylic dianhydride, 2,3',3,4' -benzophenonetetracarboxylic dianhydride, 2',3,3' -benzophenonetetracarboxylic dianhydride, 4,4'- (p-phenylenedicarbonyl) diphthalic anhydride, and 4,4' - (m-phenylenedicarbonyl) diphthalic anhydride.

In the tetracarboxylic acid residue (1a), examples of residues other than the residue having a ketone group include residues derived from tetracarboxylic dianhydrides generally used in the synthesis of polyimides, in addition to the residues shown in examples described below.

Examples of the residue having a ketone group contained in the diamine residue (2a) include: is prepared from 3,3' -diaminobenzophenone, 3,4' -diaminobenzophenone, 4' -bis [4- (4-amino-alpha, alpha-dimethylbenzyl) phenoxy ] benzophenone, 4,4' -bis (4-aminophenoxy) benzophenone 4,4' -bis (3-aminophenoxy) benzophenone (4,4' -bis (3-aminophenoxy) benzophenone, BABP), 1,3-bis [4- (3-aminophenoxy) benzoyl ] benzene (1,3-bis [4- (3-aminophenoxy) benzoyl ] benzene, BABB), 1, 4-bis (4-aminobenzoyl) benzene, 1,3-bis (4-aminobenzoyl) benzene and the like "a residue derived from a diamine compound having a ketone group in the molecule".

In the diamine residue (2a), examples of residues other than the residue having a ketone group include residues derived from a diamine compound generally used for the synthesis of polyimide, in addition to the residues shown in examples described later.

The first polyimide layer (a) may contain another polyimide other than the polyimide having a ketone group. Among these, in order to ensure sufficient adhesion to the second polyimide layer (B), it is preferable that 10 mol% or more of the polyimide having a ketone group is contained, and more preferably 30 mol% or more of the polyimide is contained as a polyimide having a ketone group, based on the total amount of the polyimides constituting the first polyimide layer (a).

The amount (in terms of-CO-) of the ketone group present in the polyimide constituting the first polyimide layer (A) is preferably in the range of 5 to 200 parts by mole, more preferably in the range of 15 to 100 parts by mole, based on 100 parts by mole of the total of the tetracarboxylic acid residue (1a) and the diamine residue (2 a). If the amount of the ketone group present in the polyimide constituting the first polyimide layer (a) is less than 5 parts by mole, the probability of interaction with the functional group (for example, terminal amino group) present in the resin layer including the polyamic acid (b) laminated in step II becomes low, and the interlayer adhesiveness may not be sufficiently obtained.

As a method for forming the first polyimide layer (a), the following method and the like can be used: a method of coating a resin solution containing polyamic acid (a) having a ketone group on an arbitrary substrate (casting method); a method for laminating a gel film comprising a polyamic acid (a) having a ketone group on an arbitrary substrate.

In the casting method, a method of applying the resin solution containing the polyamic acid (a) is not particularly limited, and for example, the coating can be performed by a coater such as a notched wheel, a die, a doctor blade, or a die lip.

The first polyimide layer (a) may be laminated with another resin layer or may be laminated on an arbitrary substrate.

The first polyimide layer (a) is preferably formed by laminating a resin layer containing a polyamic acid (a) having a ketone group on a substrate and imidizing the polyamic acid (a) together with the substrate. In this way, even when the first polyimide layer (a) is formed on the substrate by the casting method, since imidization is completed before the second polyimide layer (B) is formed, the solvent or imidization water can be removed, and problems such as foaming and interlayer peeling do not occur.

The first polyimide layer (a) may be in the form of a sheet, a roll, an endless belt, or the like, and in order to obtain productivity, it is effective to be in the form of a roll or an endless belt and to be capable of continuous production. Further, from the viewpoint of more significantly exhibiting the effect of improving the accuracy of the wiring pattern on the circuit board, the first polyimide layer (a) is preferably formed in a roll shape in a long strip.

(step II)

In step II, a resin layer comprising a polyamic acid (b) containing a functional group having a property of interacting with the ketone group is laminated on the first polyimide layer (a) obtained in step I.

In step II, the "functional group having a property of interacting with a ketone group" is not particularly limited as long as it is a functional group capable of causing, for example, physical interaction by intermolecular force or chemical interaction by covalent bond with a ketone group, and typical examples thereof include an amino group (-NH)₂)。

In the functional group beingIn the case of an amino group, as the polyamic acid (b), a polyamic acid having an amino group at an end can be used, and preferably, a polyamic acid having an amino group at a majority of an end, and further preferably, a polyamic acid having an amino group at all ends can be used. Thus, the amino terminal-rich polyamic acid (b) can be formed by: the molar ratio of the two components is adjusted so that the diamine compound is in excess relative to the tetracarboxylic dianhydride in the raw material. For example, the ratio of the raw materials to be charged is adjusted so that the tetracarboxylic dianhydride is less than 1 mole per 1 mole of the diamine compound, whereby most of the synthesized polyamic acid can be stochastically made to have an amino terminal (-NH)₂) Polyamic acid (b) of (a). When the input ratio of the tetracarboxylic dianhydride exceeds 1 mol based on 1 mol of the diamine compound, the amino terminal (-NH-) is terminated₂) It is not preferable because it hardly remains. On the other hand, if the input ratio of the tetracarboxylic dianhydride to the diamine compound is too small, the increase in molecular weight of the polyamic acid is not sufficiently advanced. Therefore, the input ratio of the tetracarboxylic dianhydride to 1 mole of the diamine compound is, for example, preferably in the range of 0.970 to 0.998 moles, and more preferably in the range of 0.980 to 0.995 moles.

The polyamic acid (b) can be synthesized by using, as raw materials, a tetracarboxylic dianhydride and a diamine compound which are generally used for synthesizing a polyimide. Further, tetracarboxylic dianhydride having a ketone group in the molecule or diamine compound having a ketone group in the molecule may be used as the raw material.

Further, the polyamic acid (b) having a rich amino terminal can be synthesized by using a compound having a rich amino group in the molecule (for example, a triamine compound) instead of a part or all of the diamine compound as a raw material.

Further, the resin layer containing the polyamic acid (b) having an amino group-rich terminal can be formed by adding a small amount of a compound containing an amino group (for example, a triamine compound) while setting the charging ratio of the tetracarboxylic dianhydride to the diamine compound in the raw materials to be equimolar.

In the formation of the resin layer containing polyamic acid (b), other polyamic acid than polyamic acid (b) may be used in combination with polyamic acid (b). As the other polyimide acid, polyamic acid can be used which is synthesized by using tetracarboxylic dianhydride and diamine compound, which are generally used for synthesizing polyimide, as raw materials and by using these compounds in an equimolar molar ratio. Among these, from the viewpoint of ensuring sufficient adhesion to the first polyimide layer (a), the resin layer containing the polyamic acid (b) is preferably polyamic acid (b) in an amount of 10 mol% or more, and more preferably 30 mol% or more, based on the total amount of the polyamic acids to be formed.

The resin layer containing polyamic acid (b) can be formed by the following method or the like: a method of coating a resin solution containing polyamic acid (b) on the first polyimide layer (a) (casting method); in the method of laminating the gel film including the polyamic acid (B) on the first polyimide layer (a), a casting method is preferably used in order to improve the adhesion between the first polyimide layer (a) and the second polyimide layer (B). In addition, when the resin layer including the polyamic acid (b) is formed, it is not necessary to previously perform surface treatment such as plasma treatment or corona treatment on the surface of the first polyimide layer (a), but these surface treatments may be performed.

In the casting method, a method of applying the resin solution containing the polyamic acid (b) is not particularly limited, and for example, the application can be performed by a coater such as a die wheel, a film, a blade, or a die lip.

The resin layer containing polyamic acid (b) thus obtained is a resin layer as follows: comprises a tetracarboxylic acid residue (1b) and a diamine residue (2b), contains the tetracarboxylic acid residue (1b) in an amount of less than 1 mole, preferably in an amount of 0.970 to 0.998 mole, more preferably in an amount of 0.980 to 0.995 mole, relative to 1 mole of the diamine residue (2b), and is rich in an amino terminal group (-NH-) and a diamine residue (2b)₂)。

(step III)

In step III, the resin layer including the polyamic acid (B) is subjected to a heat treatment along with the first polyimide layer (a), and the polyamic acid (B) is imidized to form a second polyimide layer (B).

The method of imidization is not particularly limited, and for example, heat treatment such as heating at a temperature in the range of 80 to 400 ℃ for a time in the range of 1 to 60 minutes can be suitably employed. When the metal layer is included, the heat treatment in a low-oxygen atmosphere is preferable for suppressing oxidation, and specifically, the heat treatment is preferably performed in an inert gas atmosphere such as nitrogen or a rare gas, a reducing gas atmosphere such as hydrogen, or a vacuum.

In addition, it is considered that, in parallel with imidization, an interaction occurs between a ketone group present in a polyimide chain of the first polyimide layer (a) and the functional group (for example, a terminal amino group which is abundant) present in the resin layer including the polyamic acid (B), and the adhesiveness of the first polyimide layer (a) and the second polyimide layer (B) is greatly improved beyond the characteristics (for example, thermoplasticity, non-thermoplasticity, and the like) of the polyimides constituting the two layers. As for the interaction, all the mechanisms thereof cannot be clarified, and it is presumed that: in the case where the functional group is an amino group, as one possibility, an imine bond is generated between the ketone group and a terminal amino group by heat treatment at the time of imidizing the polyamic acid (b). Namely, it is inferred that: the polyimide bond is formed by dehydration condensation reaction between a ketone group in the polyimide chain of the first polyimide layer (a) and an amino group at the end of the polyamic acid (B) by heating, and the polyimide chain in the first polyimide layer (a) is chemically bonded to the imidized second polyimide layer (B), thereby enhancing the adhesion of the first polyimide layer (a) to the second polyimide layer (B).

In addition, when the first polyimide layer (a) and the second polyimide layer (B) are in an inverse relationship to the above, the effect of improving the interlayer adhesiveness cannot be obtained. That is, in the case where a resin layer including a polyamic acid (b) including a functional group having a property of interacting with a ketone group is first imidized to form a polyimide layer as a first layer, a resin layer including a polyamic acid (a) having a ketone group is formed thereon, and then imidized by heat treatment to form a polyimide layer as a second layer, the adhesion between the first layer and the second layer is not improved beyond the properties (e.g., thermoplastic, non-thermoplastic, etc.) of the polyimide constituting the two layers. The reason is considered to be: in the cured polyimide, the movement of the amino group as the terminal of the functional group is restricted to lower the reactivity, and therefore the interaction is difficult to occur.

The first polyimide layer (a) and the second polyimide layer (B) may also 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, calcium fluoride, and the like. These may be used alone or in combination of two or more.

By the above steps I to III, a polyimide film having excellent adhesion between the first polyimide layer (a) and the second polyimide layer (B) can be produced without causing a decrease in yield due to an increase in the number of steps.

[ fourth embodiment: method for producing metal-clad laminate

A fourth embodiment of the present invention is a method for manufacturing a metal clad laminate including steps i to iv, the method including: the polyimide film includes a metal layer, a first polyimide layer (A), and a second polyimide layer (B) laminated on one side of the first polyimide layer (A).

(step i)

In step i, at least one resin layer of polyamic acid is formed on the metal layer, the resin layer of polyamic acid including a resin layer of polyamic acid (a) having a ketone group in a surface layer portion.

As the metal layer, a metal foil may be preferably used. The material of the metal foil is not particularly limited, and examples thereof include: copper, stainless steel, iron, nickel, beryllium, aluminum, zinc, indium, silver, gold, tin, zirconium, tantalum, titanium, lead, magnesium, manganese, alloys of these, and the like. Among them, copper or a copper alloy is particularly preferable. The copper foil may be a rolled copper foil or an electrolytic copper foil, and a commercially available copper foil is preferably used.

In the present embodiment, the metal layer used for producing the FPC preferably has a thickness in a range of 3 to 50 μm, and more preferably in a range of 5 to 30 μm.

The metal foil used as the metal layer may be surface-treated with, for example, rust-proofing treatment, finishing, aluminum alcoholate, aluminum chelate, silane coupling agent, or the like. The metal foil may be in the form of a cut sheet, a roll, or a circular strip, and in order to obtain productivity, it is effective to form the metal foil in the form of a roll or a circular strip and to form the metal foil in a form capable of continuous production. Further, from the viewpoint of more significantly exhibiting the effect of improving the accuracy of the wiring pattern on the circuit board, the metal foil is preferably formed in a long roll shape.

In forming the first polyimide layer (a), at least one resin layer of polyamic acid is formed on the metal layer so that the resin layer containing polyamic acid (a) having a ketone group becomes a surface layer portion. In this case, the formation may be performed by the following method or the like: a method of coating a resin solution of polyamic acid on a metal layer (casting method); a method of laminating a gel film comprising polyamic acid (a) on a metal layer.

In addition, an arbitrary resin layer (a resin layer containing another polyamic acid) may be provided between the metal layer and the resin layer containing the polyamic acid (a) having a ketone group, and in this case, the resin layer containing the polyamic acid (a) having a ketone group may be formed on the arbitrary resin layer by the above-described method. In the case where the resin layer of the polyamic acid (a) having a ketone group is directly formed on the metal layer, it is preferable to use a casting method in order to improve the adhesion between the metal layer and the first polyimide layer (a).

(step ii)

In step ii, the resin layer of the polyamic acid including a resin layer including the polyamic acid (a) having a ketone group in a surface layer portion is subjected to heat treatment together with the metal layer to imidize the polyamic acid. Thereby, an intermediate in which a polyimide layer including the first polyimide layer (a) containing a polyimide having a ketone group as a surface layer portion is laminated is formed on the metal layer.

The imidization of the polyamic acid can be performed by the method described in the step (III) of the third embodiment. In the present embodiment, even in the case of forming a resin layer of polyamic acid on a metal foil by a casting method, since imidization is completed before forming the second polyimide layer (B), a solvent or imidized water is removed, and problems such as foaming or interlayer peeling do not occur.

(step iii)

In step iii, a resin layer including a polyamic acid (b) including a functional group having a property of interacting with the ketone group is laminated on the first polyimide layer (a).

This step iii can be performed in the same manner as step II of the third embodiment.

(step iv)

The resin layer including the polyamic acid (B) laminated on the intermediate in step iii is subjected to a heat treatment together with the intermediate to imidize the polyamic acid (B) to form a second polyimide layer (B).

This step iv can be performed in the same manner as step III of the third embodiment.

By the above steps i to iv, a metal clad laminate excellent in adhesion between the first polyimide layer (a) and the second polyimide layer (B) can be produced without causing a reduction in yield due to an increase in the number of steps.

Other configurations and effects of the present embodiment are the same as those of the third embodiment.

< polyimide >

Next, a preferred polyimide for forming the first polyimide layer (a) and the second polyimide layer (B) will be described. In the formation of the first polyimide layer (a), it is preferable to use the above-mentioned "tetracarboxylic dianhydride having a ketone group in the molecule" and/or "diamine compound having a ketone group in the molecule" in combination with an acid anhydride component and a diamine component which are generally used as raw materials for the synthesis of polyimide. In the formation of the second polyimide layer (B), an acid anhydride component and a diamine component, which are generally used as raw materials for synthesizing polyimide, can be used without particular limitation.

In the polyimide film or the metal-clad laminate, the polyimide constituting the first polyimide layer (a) may be either a thermoplastic polyimide or a non-thermoplastic polyimide, and is preferably a thermoplastic polyimide because adhesion to a base material, a metal foil, or a resin layer is easily ensured.

The polyimide constituting the second polyimide layer (B) may be either a thermoplastic polyimide or a non-thermoplastic polyimide, and the effect of the present invention can be remarkably exhibited when the non-thermoplastic polyimide is used.

That is, even when a resin layer of polyamic acid that is a precursor of non-thermoplastic polyimide is laminated on the imidized first polyimide layer (a) by a method such as a casting method and imidized, adhesion between polyimide layers is hardly obtained in general. However, in the present embodiment, excellent adhesion between the layers of the first polyimide layer (a) can be obtained by the interaction between the ketone group and the functional group (for example, terminal amino group) regardless of whether the polyimide constituting the second polyimide layer (B) is thermoplastic or non-thermoplastic. Further, by using a non-thermoplastic polyimide as the second polyimide layer (B), the polyimide film or the metal-clad laminate can function as a main layer (base layer) that secures the mechanical strength of the polyimide layer.

From the above, in the polyimide film or the metal-clad laminate, the most preferable embodiment is: a structure in which a thermoplastic polyimide layer is laminated as a first polyimide layer (a) and a non-thermoplastic polyimide layer is laminated as a second polyimide layer (B) is formed.

(thermoplastic polyimide)

The thermoplastic polyimide can be obtained by reacting an acid anhydride component with a diamine component. The acid anhydride component which is a raw material of the thermoplastic polyimide is not particularly limitedIn the synthesis of polyimide, a general acid anhydride is preferably used in combination with biphenyltetracarboxylic dianhydride (PMDA) from the viewpoint of achieving both adhesion to a metal layer and low dielectric characteristics. The biphenyltetracarboxylic dianhydride has an effect of lowering the glass transition temperature to such an extent that it does not affect the solder heat resistance of the polyimide, and can secure a sufficient adhesive force with a metal layer or the like. In addition, biphenyltetracarboxylic dianhydride reduces the imide group concentration of polyimide, and easily forms an ordered structure of a polymer, and improves dielectric characteristics by inhibiting the movement of molecules. Further, the biphenyltetracarboxylic dianhydride contributes to a reduction in polar groups of the polyimide, thereby improving moisture absorption characteristics. According to this case, biphenyltetracarboxylic dianhydride can reduce transmission loss of FPC. Further, the "imide group concentration" refers to the imide group (- (CO) in the polyimide to be used₂A value obtained by dividing the molecular weight of-N-) by the molecular weight of the entire structure of the polyimide.

Examples of the biphenyltetracarboxylic dianhydride include: 3,3',4,4' -biphenyltetracarboxylic dianhydride (BPDA), 2,3',3,4' -biphenyltetracarboxylic dianhydride, 2',3,3' -biphenyltetracarboxylic dianhydride, and the like. By using biphenyltetracarboxylic dianhydride in the above range, an ordered structure based on a rigid structure is formed, and therefore, a thermoplastic polyimide which is thermoplastic, has low gas permeability, and is excellent in long-term heat-resistant adhesion can be obtained while achieving a low dielectric loss tangent. Pyromellitic dianhydride is a monomer responsible for controlling the glass transition temperature, and contributes to improvement of solder heat resistance of polyimide.

Further, the thermoplastic polyimide may use acid anhydrides other than the above as the acid anhydride component. Examples of such acid anhydrides include: 3,3',4,4' -diphenylsulfone tetracarboxylic dianhydride, 4,4' -oxydiphthalic anhydride, 2',3,3' -benzophenonetetracarboxylic dianhydride, 2,3,3',4' -benzophenonetetracarboxylic dianhydride or 3,3',4,4' -benzophenonetetracarboxylic dianhydride, 2,3',3,4' -diphenylethertetracarboxylic dianhydride, bis (2, 3-dicarboxyphenyl) ether dianhydride, 3,3',4,4' -terphenyltetracarboxylic dianhydride, 2,3,3',4' -terphenyltetracarboxylic dianhydride or 2,2',3,3' -terphenyltetracarboxylic dianhydride, 2-bis (2, 3-dicarboxyphenyl) -propane dianhydride or 2,2-bis (3, 4-dicarboxyphenyl) -propane dianhydride, Bis (2, 3-dicarboxyphenyl) methane dianhydride or bis (3, 4-dicarboxyphenyl) methane dianhydride, bis (2, 3-dicarboxyphenyl) sulfone dianhydride or bis (3, 4-dicarboxyphenyl) sulfone dianhydride, 1-bis (2, 3-dicarboxyphenyl) ethane dianhydride or 1, 1-bis (3, 4-dicarboxyphenyl) ethane dianhydride, 1,2,7, 8-phenanthrene-tetracarboxylic acid dianhydride, 1,2,6, 7-phenanthrene-tetracarboxylic acid dianhydride or 1,2,9, 10-phenanthrene-tetracarboxylic acid dianhydride, 2,3,6, 7-anthracenetetracarboxylic acid dianhydride, 2-bis (3, 4-dicarboxyphenyl) tetrafluoropropane dianhydride, 2,3,5, 6-cyclohexane dianhydride, 2,3,6, 7-naphthalenetetracarboxylic acid dianhydride, 1,2,5, 6-naphthalenetetracarboxylic dianhydride, 1,4,5, 8-naphthalenetetracarboxylic dianhydride, 4, 8-dimethyl-1, 2,3,5,6, 7-hexahydronaphthalene-1, 2,5, 6-tetracarboxylic dianhydride, 2, 6-dichloronaphthalene-1, 4,5, 8-tetracarboxylic dianhydride or 2, 7-dichloronaphthalene-1, 4,5, 8-tetracarboxylic dianhydride, 2,3,6,7- (or 1,4,5,8-) tetrachloronaphthalene-1, 4,5,8- (or 2,3,6,7-) tetracarboxylic dianhydride, 2,3,8, 9-perylene-tetracarboxylic dianhydride, 3,4,9, 10-perylene-tetracarboxylic dianhydride, 4,5,10, 11-perylene-tetracarboxylic dianhydride or 5,6,11, 12-perylene-tetracarboxylic dianhydride, cyclopentane-1, 2,3, 4-tetracarboxylic dianhydride, pyrazine-2, 3,5, 6-tetracarboxylic dianhydride, pyrrolidine-2, 3,4, 5-tetracarboxylic dianhydride, thiophene-2, 3,4, 5-tetracarboxylic dianhydride, 4' -bis (2, 3-dicarboxyphenoxy) diphenylmethane dianhydride, 2-bis [4- (3, 4-dicarboxyphenoxy) phenyl ] propane dianhydride, and the like.

The diamine component to be a raw material of the thermoplastic polyimide is not particularly limited, and a general diamine used for synthesis of polyimide may be used, and preferably at least one selected from diamine compounds represented by the following general formulae (1) to (8) is contained.

[ solution 3]

In the formulae (1) to (7), R₁Independently represents a C1-6 monovalent hydrocarbon group or an alkoxy group, and the linking group A independently represents a group selected from-O-, -S-, -CO-, -SO-, -SO₂-、-COO-、-CH₂-、-C(CH₃)₂A divalent radical of-NH-or-CONH-, n₁Independently represent an integer of 0 to 4. Wherein a portion that overlaps with formula (2) is removed from formula (3), and a portion that overlaps with formula (4) is removed from formula (5). Here, "independently" means that in one or two or more of the above formulae (1) to (7), a plurality of linking groups a and a plurality of R groups₁Or a plurality of n₁May be the same or different.

[ solution 4]

In the formula (8), the linking group X represents a single bond or-CONH-, Y independently represents a C1-3 monovalent hydrocarbon group or alkoxy group which may be substituted with a halogen atom, n represents an integer of 0-2, and p and q independently represent an integer of 0-4.

Further, in the formulae (1) to (8), the hydrogen atoms in the terminal two amino groups may be substituted, and may be, for example, -NR₂R₃(Here, R is₂，R₃Independently represents an optional substituent such as an alkyl group).

The diamine represented by the formula (1) (hereinafter, sometimes referred to as "diamine (1)") is an aromatic diamine having two benzene rings. It is considered that the diamine (1) is located at the meta position with respect to the divalent linking group a via the amino group directly bonded to at least one benzene ring, and the polyimide molecular chain has an increased degree of freedom and high flexibility, contributing to improvement of flexibility of the polyimide molecular chain. Therefore, by using the diamine (1), the thermoplasticity of the polyimide is improved. Here, as the linking group a, preferred are: -O-, -CH₂-、-C(CH₃)₂-、-CO-、-SO₂-、-S-。

Examples of the diamine (1) include: 3,3' -diaminodiphenylmethane, 3' -diaminodiphenylpropane, 3' -diaminodiphenylsulfide, 3' -diaminodiphenylsulfone, 3-diaminodiphenylether, 3,4' -diaminodiphenylmethane, 3,4' -diaminodiphenylpropane, 3,4' -diaminodiphenylsulfide, 3' -diaminobenzophenone, (3,3' -diamino) diphenylamine and the like.

The diamine represented by the formula (2) (hereinafter, sometimes referred to as "diamine (2)") is an aromatic diamine having three benzene rings. It is considered that the diamine (2) is located at the meta position with respect to the divalent linking group a via the amino group directly bonded to at least one benzene ring, and the polyimide molecular chain has an increased degree of freedom and high flexibility, contributing to improvement of flexibility of the polyimide molecular chain. Therefore, by using the diamine (2), the thermoplasticity of the polyimide is improved. Here, the linking group A is preferably-O-.

Examples of the diamine (2) include: 1, 4-bis (3-aminophenoxy) benzene, 3- [4- (4-aminophenoxy) phenoxy ] aniline, 3- [3- (4-aminophenoxy) phenoxy ] aniline, and the like.

The diamine represented by the formula (3) (hereinafter, sometimes referred to as "diamine (3)") is an aromatic diamine having three benzene rings. It is considered that the diamine (3) is located at a meta position to each other via the two divalent linking groups a directly bonded to one benzene ring, and the polyimide molecular chain has an increased degree of freedom and high flexibility, contributing to improvement of flexibility of the polyimide molecular chain. Therefore, by using the diamine (3), the thermoplasticity of the polyimide is improved. Here, the linking group A is preferably-O-.

Examples of the diamine (3) include: 1,3-Bis (4-aminophenoxy) benzene (1,3-Bis (4-aminophenoxy) bezene, TPE-R), 1,3-Bis (3-aminophenoxy) benzene (1,3-Bis (3-aminophenoxy) bezene, APB), 4' - [ 2-methyl- (1, 3-phenylene) dioxy ] dianiline, 4' - [ 4-methyl- (1, 3-phenylene) dioxy ] dianiline, 4' - [ 5-methyl- (1, 3-phenylene) dioxy ] dianiline, and the like. Among these, 1,3-bis (4-aminophenoxy) benzene (TPE-R) is particularly preferable as a monomer that contributes to the high CTE (Coefficient of Thermal Expansion) of the thermoplastic polyimide, and that reduces the imide group concentration and improves the dielectric characteristics.

The diamine represented by the formula (4) (hereinafter, sometimes referred to as "diamine (4)") is an aromatic diamine having four benzene rings. The diamine (4) is believed to be linked divalent through an amino group bonded directly to at least one benzene ringThe group A is in a meta position, has high flexibility, and contributes to improvement of flexibility of the polyimide molecular chain. Therefore, by using the diamine (4), the thermoplasticity of the polyimide is improved. Here, the linking group A is preferably-O-, -CH₂-、-C(CH₃)₂-、-SO₂-、-CO-、-CONH-。

Examples of the diamine (4) include: bis [4- (3-aminophenoxy) phenyl ] methane, bis [4- (3-aminophenoxy) phenyl ] propane, bis [4- (3-aminophenoxy) phenyl ] ether, bis [4- (3-aminophenoxy) phenyl ] sulfone, bis [4- (3-aminophenoxy) ] benzophenone, bis [4,4' - (3-aminophenoxy) ] benzanilide, and the like.

The diamine represented by the formula (5) (hereinafter, sometimes referred to as "diamine (5)") is an aromatic diamine having four benzene rings. It is considered that the diamine (5) is located at a meta position to each other via the two divalent linking groups a directly bonded to at least one benzene ring, and the polyimide molecular chain has an increased degree of freedom and high flexibility, contributing to an improvement in flexibility of the polyimide molecular chain. Therefore, by using the diamine (5), the thermoplasticity of the polyimide is improved. Here, the linking group A is preferably-O-.

Examples of the diamine (5) include 4- [3- [4- (4-aminophenoxy) phenoxy ] aniline, 4' - [ oxybis (3, 1-phenyleneoxy) ] dianiline, and the like.

The diamine represented by the formula (6) (hereinafter, sometimes referred to as "diamine (6)") is an aromatic diamine having four benzene rings. The diamine (6) is considered to have high flexibility by having at least two ether bonds, and to contribute to improvement in flexibility of the polyimide molecular chain. Therefore, by using the diamine (6), the thermoplasticity of the polyimide is improved. Here, the linking group A is preferably-C (CH)₃)₂-、-O-、-SO₂-、-CO-。

Examples of the diamine (6) include: 2,2-Bis [4- (4-aminophenoxy) phenyl ] propane (2,2-Bis [4- (4-aminophenoxy) phenyl ] propane, BAPP), Bis [4- (4-aminophenoxy) phenyl ] ether (Bis [4- (4-aminophenoxy) phenyl ] ether, BAPE), Bis [4- (4-aminophenoxy) phenyl ] sulfone (Bis [4- (4-aminophenoxy) phenyl ] sulfone, BAPS), Bis [4- (4-aminophenoxy) phenyl ] ketone (Bis [4- (4-aminophenoxy) phenyl ] ketone, BAPK), and the like. Among these, 2-bis [4- (4-aminophenoxy) phenyl ] propane (BAPP) is particularly preferable as a monomer that greatly contributes to the improvement of adhesion to the metal layer.

The diamine represented by the formula (7) (hereinafter, sometimes referred to as "diamine (7)") is an aromatic diamine having four benzene rings. The diamine (7) is considered to contribute to improvement in flexibility of the polyimide molecular chain because it has the divalent linking group a having high flexibility on both sides of the diphenyl skeleton. Therefore, by using the diamine (7), the thermoplasticity of the polyimide is improved. Here, the linking group A is preferably-O-.

Examples of the diamine (7) include bis [4- (3-aminophenoxy) ] biphenyl and bis [4- (4-aminophenoxy) ] biphenyl.

The diamine represented by the general formula (8) (hereinafter, sometimes referred to as "diamine (8)") is an aromatic diamine having one to three benzene rings. The diamine (8) has a rigid structure, and therefore has an effect of imparting an ordered structure to the entire polymer. Therefore, by using one or more of the diamines (1) to (7) and one or more of the diamines (8) at a predetermined ratio in combination, a polyimide which has a low dielectric loss tangent, is thermoplastic, has low gas permeability, and has excellent long-term heat-resistant adhesion can be obtained. Here, the linking group X is preferably a single bond, -CONH-.

Examples of the diamine (8) include: p-Phenylenediamine (PDA), 4'-diamino-2,2' -dimethylbiphenyl (4,4'-diamino-2,2' -dimethyl biphenol, m-TB), 4 '-diamino-3, 3' -dimethylbiphenyl, 4'-diamino-2,2' -n-propylbiphenyl (4,4'-diamino-2,2' -n-propyl biphenol, m-NPB), 2'-methoxy-4,4' -diaminobenzanilide (2'-methoxy-4,4' -diaminobenzanilide, MABA), 4 '-diaminobenzanilide (4,4' -diaminobenzanilide, DABA), 2 '-bis (trifluoromethyl) -4,4' -diaminobiphenyl, and the like. Among these, 4'-diamino-2,2' -dimethylbiphenyl (m-TB) is particularly preferable as a monomer that contributes significantly to improvement of dielectric properties of thermoplastic polyimide, and further, to low moisture absorption and high heat resistance.

By using the diamines (1) to (7), the flexibility of the polyimide molecular chain can be improved and thermoplasticity can be imparted.

Further, by using the diamine (8), an ordered structure is formed as a whole in the polymer by utilizing a rigid structure derived from a monomer, and therefore, a polyimide which is thermoplastic, has low gas permeability, and is excellent in long-term heat-resistant adhesion can be obtained while achieving a low dielectric loss tangent.

Further, the thermoplastic polyimide may use a diamine other than the above as the diamine component.

(non-thermoplastic polyimide)

The non-thermoplastic polyimide may be obtained by reacting an acid anhydride component with a diamine component. As the acid anhydride component which becomes a raw material of the non-thermoplastic polyimide, a general acid anhydride used in synthesis of polyimide can be used without particular limitation, and in order to impart low dielectric characteristics, it is preferable to use at least one or more selected from pyromellitic dianhydride (PMDA), biphenyltetracarboxylic dianhydride, and naphthalenetetracarboxylic dianhydride as the acid anhydride component of the raw material. Here, as the biphenyltetracarboxylic dianhydride, 3',4,4' -biphenyltetracarboxylic dianhydride (BPDA) is particularly preferable, and as the naphthalenetetracarboxylic dianhydride, 2,3,6, 7-naphthalenetetracarboxylic dianhydride (2,3,6,7-naphthalene tetracarboxylic dianhydride, NTCDA) is particularly preferable.

PMDA can lower the Coefficient of Thermal Expansion (CTE) of polyimide. BPDA has the effect of lowering the glass transition temperature to such an extent that it does not affect the solder heat resistance of polyimide. In addition, BPDA reduces the imide group concentration of polyimide, and easily forms an ordered structure of a polymer, and improves dielectric characteristics by inhibiting the movement of molecules. Further, BPDA contributes to a reduction in polar groups of polyimide, thereby improving moisture absorption characteristics. Therefore, by using the BPDA, the transmission loss of the FPC can be reduced.

Further, the non-thermoplastic polyimide may use acid anhydrides other than the above as the acid anhydride component.

The diamine component to be a raw material of the non-thermoplastic polyimide is not particularly limited, and a general diamine used for synthesis of polyimide may be used, and is preferably a diamine selected from the diamines (1) to (8) exemplified in the description of the thermoplastic polyimide, and more preferably the diamine (8).

The diamine (8) is an aromatic diamine, and contributes to lowering the CTE or improving the dielectric characteristics, and further contributes to lowering the moisture absorption or increasing the heat resistance. In the diamine (8), in the general formula (8), those in which Y is an alkyl group having 1 to 3 carbon atoms are preferable, and 4,4'-diamino-2,2' -dimethylbiphenyl (m-TB) and 4,4 '-diamino-3, 3' -dimethylbiphenyl are more preferable. Of these, 4'-diamino-2,2' -dimethylbiphenyl (m-TB) is most preferred.

The non-thermoplastic polyimide may contain a diamine other than the above-mentioned diamine as a diamine component within a range not to impair the effects of the invention.

(Synthesis of polyimide)

The polyimide constituting the polyimide layer can be produced by: the acid anhydride and the diamine are reacted in a solvent, and after the precursor resin is produced, ring closure is performed by heating. For example, a polyamic acid as a precursor of a polyimide is obtained by dissolving an acid anhydride component and a diamine component in approximately equimolar amounts [ wherein the ratio of the diamine component is increased in the case of forming the second polyimide layer (B) ] in an organic solvent, and stirring the solution at a temperature in the range of 0 to 100 ℃ for 30 minutes to 24 hours to perform a polymerization reaction. During the reaction, the reaction components are dissolved in the organic solvent so that the produced precursor is in the range of 5 to 30 wt%, preferably 10 to 20 wt%. Examples of the organic solvent used in the polymerization reaction include: n, N-dimethylformamide, N-dimethylacetamide (DMAc), N-methyl-2-pyrrolidone, 2-butanone, dimethyl sulfoxide, dimethyl sulfate, cyclohexanone, dioxane, tetrahydrofuran, diglyme, triglyme, and the like. Two or more of these solvents may be used in combination, and an aromatic hydrocarbon such as xylene or toluene may be used in combination. The amount of the organic solvent used is not particularly limited, but is preferably adjusted so that the concentration of the polyamic acid solution (polyimide precursor solution) obtained by the polymerization reaction is about 5 to 30 wt%.

In the synthesis of polyimide, only one of the acid anhydride and the diamine may be used, or two or more thereof may be used in combination. The thermal expansibility, adhesiveness, glass transition temperature, etc. can be controlled by selecting the kind of the acid anhydride and the diamine, or the molar ratio of each of the acid anhydride and the diamine when two or more kinds thereof are used.

The synthesized precursors are generally advantageously used as a reaction vehicle solution, which may be concentrated, diluted or replaced by other organic vehicles as desired. In addition, the precursor is generally used advantageously because of excellent solvent solubility. The method for imidizing the precursor is not particularly limited, and for example, heat treatment such as heating at a temperature in the range of 80 to 400 ℃ for 1 to 24 hours in the solvent can be suitably used.

As described above, the method for producing a polyimide film according to the third embodiment of the present invention is a method for producing a polyimide film including: the polyimide film includes a first polyimide layer (A) and a second polyimide layer (B) laminated on at least one side of the first polyimide layer (A).

The method for producing a polyimide film according to the third embodiment of the present invention includes steps I to III:

I) a step of preparing a first polyimide layer (a) containing a polyimide having a ketone group;

II) a step of laminating a resin layer comprising a polyamic acid (b) containing a functional group having a property of causing an interaction with the ketone group on the first polyimide layer (a); and

III) a step of subjecting the resin layer including polyamic acid (B) to a heat treatment together with the first polyimide layer (a) to imidize the polyamic acid (B) and form a second polyimide layer (B).

In the method for producing a polyimide film according to the third embodiment of the present invention, the polyimide constituting the first polyimide layer (a) may contain a tetracarboxylic acid residue (1a) and a diamine residue (2a), and the ketone group may be 5 parts by mole or more based on 100 parts by mole of the total of the tetracarboxylic acid residue (1a) and the diamine residue (2 a).

In the method for producing a polyimide film according to the third embodiment of the present invention, the resin layer containing polyamic acid (b) contains tetracarboxylic acid residue (1b) and diamine residue (2b), and the tetracarboxylic acid residue (1b) may be less than 1 mole relative to 1 mole of the diamine residue (2 b).

In the method for producing a polyimide film according to the third embodiment of the present invention, the first polyimide layer (a) may be formed by laminating a resin layer including a polyamic acid (a) having a ketone group on a substrate and imidizing the polyamic acid (a) together with the substrate.

A method for manufacturing a metal-clad laminate according to a fourth embodiment of the present invention is a method for manufacturing a metal-clad laminate including: the polyimide film includes a metal layer, a first polyimide layer (A), and a second polyimide layer (B) laminated on one side of the first polyimide layer (A).

A method for manufacturing a metal-clad laminate according to a fourth embodiment of the present invention includes steps i to iv of:

i) a step of forming at least one resin layer of polyamic acid on the metal layer, the resin layer of polyamic acid including a resin layer containing polyamic acid (a) having a ketone group in a surface layer portion;

ii) a step of subjecting the resin layer of the polyamic acid to heat treatment together with the metal layer to imidize the polyamic acid, thereby forming an intermediate having a polyimide layer laminated thereon, the polyimide layer including a first polyimide layer (a) comprising a polyimide having a ketone group as a surface layer portion;

iii) a step of laminating a resin layer comprising a polyamic acid (b) containing a functional group having a property of interacting with the ketone group on the first polyimide layer (a); and

iv) a step of subjecting the resin layer of the polyamic acid (B) to heat treatment together with the intermediate to imidize the polyamic acid (B) to form a second polyimide layer (B).

The method for manufacturing a circuit board according to an embodiment of the present invention includes: and a step of processing a wiring circuit to the metal layer of the metal-clad laminate manufactured by the method of the fourth embodiment.

As described above, the polyimide film obtained in the third embodiment of the present invention and the metal-clad laminate obtained in the fourth embodiment can improve the reliability of electronic devices by being used as a circuit board material represented by FPC while being excellent in adhesion between the first polyimide layer (a) and the second polyimide layer (B).

< Circuit Board >

A circuit board according to an embodiment of the present invention includes: the wiring layer includes an insulating resin layer including a plurality of polyimide layers, and a wiring layer laminated on at least one surface of the insulating resin layer. The circuit substrate can be manufactured by: the metal layer of the metal-clad laminate obtained by the method of the first, second, or fourth embodiment is processed into a pattern by a conventional method to form a wiring layer. The patterning of the metal layer may be performed by using any method such as photolithography and etching.

In the case of manufacturing a circuit board, as a step which is usually performed, for example, through hole processing in a preceding step, or terminal plating, outline processing and the like in a subsequent step may be performed according to a conventional method.

Examples

The following examples are presented to illustrate and more particularly illustrate the features of the present invention. The scope of the present invention is not limited to the examples. In the following examples, comparative examples and reference examples, various measurements and evaluations were made based on the following descriptions unless otherwise specified.

[ measurement of viscosity ]

The viscosity of the resin was measured at 25 ℃ using an E-type viscometer (product name: DV-II + Pro, manufactured by Brookfield corporation). The rotation number was set so that the torque was 10% to 90%, and a value at which the viscosity was stable was read after 2 minutes had elapsed from the start of the measurement.

[ evaluation of foaming ]

The case where peeling was observed between the first polyimide layer and the second polyimide layer or cracks were generated in the polyimide layer was referred to as "foaming", and the case where peeling or cracks were not generated was referred to as "non-foaming".

[ measurement of dimensional Change Rate after etching ]

A metal-clad laminate of 80mm by 80mm in size was prepared. After a dry film resist (dry film resist) was provided on the metal layer of the laminate, exposure and development were performed, and 16 resist patterns having a diameter of 1mm were formed so that the entire laminate was a regular quadrangle as shown in fig. 2, thereby preparing position measurement targets that were spaced 50mm apart in the Machine Direction (MD) and Transverse Direction (TD) and that were capable of measuring 5 positions.

For the prepared samples, at temperature: 23 ± 2 ℃, relative humidity: in an environment of 50. + -. 5%, the distance between the targets in the Machine Direction (MD) and the Transverse Direction (TD) of the resist pattern in the target for position measurement was measured, and then the exposed portion of the metal layer in the opening portion of the resist pattern was removed by etching (temperature of the etching solution: 40 ℃ C. or less, etching time: 10 minutes or less), and as shown in FIG. 3, an evaluation sample having 16 remaining points of the metal layer was prepared. Subjecting the evaluation sample to a temperature: 23 ± 2 ℃, relative humidity: after standing in a 50. + -. 5% atmosphere for 24. + -. 4 hours, the distance between the remaining points of the metal layer in the Machine Direction (MD) and the Transverse Direction (TD) is measured. The dimensional change rate from the normal state at each 5 positions in the vertical and horizontal directions was calculated, and the average value of the dimensional change rates was defined as the post-etching dimensional change rate.

Each dimensional change rate is obtained by the following numerical expression.

Dimensional change after etching (%) - (B-a)/ax100

A: distance between targets after resist development

B: distance between metal layer remaining points after metal layer etching

The absolute value of the dimensional change rate after etching is 0.2% or less, the absolute value is "good", the absolute value exceeds 0.2% and is 0.4% or less is "ok", and the absolute value exceeds 0.4% is "no".

[ evaluation of curl (curl) ]

The film curl is a 4-angle floating height measured when the copper foil of the metal-clad laminate is etched on the entire surface and the first polyimide layer of the polyimide film having a size of 100mm × 100mm after removing the copper foil is set to be lower and left. The condition that the average value of the floating height of 4 corners exceeds 10mm is evaluated as "having curl".

[ evaluation of moisture permeability ]

A moisture absorbent/calcium chloride (anhydrous) was sealed in a moisture permeable cup in accordance with Japanese Industrial Standards (JIS) Z0208, and the mass increase of the cup after 24 hours was evaluated as the water vapor permeation amount.

[ measurement of moisture absorption Rate ]

A test piece (width 4 cm. times. length 25cm) of 2 pieces of polyimide film was prepared and dried at 80 ℃ for 1 hour. Immediately after drying, the mixture was placed in a constant temperature and humidity chamber at 23 ℃/50% RH, allowed to stand for 24 hours or more, and then the weight change between the two was determined by the following equation.

Moisture absorption rate (% by weight) [ (weight after moisture absorption-weight after drying)/weight after drying ] × 100

[ measurement of glass transition temperature (Tg) ]

The dynamic viscoelasticity of a polyimide film (10 mm. times.40 mm) when the temperature was raised from 20 ℃ to 500 ℃ at 5 ℃ per minute was measured by a dynamic thermomechanical analyzer (DMA: manufactured by TA Instruments Japan, trade name: RSA-G2), and the glass transition temperature (Tan. delta. maximum:. degree. C.) was determined.

[ measurement of storage modulus of elasticity ]

The storage modulus of elasticity was measured using a dynamic viscoelasticity measuring apparatus (DMA). The storage modulus of elasticity at 30 ℃ was 1.0X 10⁹Pa or more and a storage modulus of elasticity at 350 ℃ of 1.0X 10⁸The polyimide having Pa or more is a "non-thermoplastic polyimide", and the storage elastic modulus at 30 ℃ is 1.0X 10⁹Pa or more and a storage elastic coefficient of less than 1.0X 10 at 350 DEG C⁸The polyimide of Pa is referred to as "thermoplastic polyimide".

[ measurement of Coefficient of Thermal Expansion (CTE) ]

A polyimide film having a thickness of 25 μm and a size of 3 mm. times.20 mm was heated from 30 ℃ to 300 ℃ at a constant heating rate while applying a load of 5.0g using a thermomechanical analyzer (product name: 4000SA manufactured by Bruker Co., Ltd.), and was held at that temperature for 10 minutes and then cooled at a rate of 5 ℃/minute to determine an average thermal expansion coefficient (thermal expansion coefficient) between 250 ℃ and 100 ℃.

[ measurement of volatile component fraction ]

The volatile fraction in each example was measured by TG-DTA of the first polyamide resin layer film after half-curing in a temperature rise rate of 10 ℃/min in a range of 30 to 500 ℃, and the film weight at 100 ℃ was taken as 100%, whereas the weight reduction rate up to 100 to 360 ℃ was taken as the volatile fraction.

[ evaluation of imidization ratio ]

The imidization ratio of the polyimide layer can be calculated as follows: an infrared absorption spectrum in the state of a polyimide film was measured by a primary reflection ATR method using a Fourier transform infrared spectrophotometer (manufactured by JASCO corporation, trade name FT/IR) at 1009cm^-1Based on the benzene ring hydrocarbon bond of (1), and according to 1778cm^-1The absorbance derived from the imide group (b) was calculated. The first polyamide resin layer was subjected to a stepwise heat treatment from 120 ℃ to 360 ℃, and the imidization ratio of the polyimide film after the 360 ℃ heat treatment was 100%.

[ measurement of peeling Strength ]

The peel strength was measured by fixing the second polyimide layer side of a sample having a width of 10mm to an aluminum plate with a double-sided tape using a Tensilon Tester (manufactured by Toyo Seiko K.K.; trade name: Strograhi VE-1D), and stretching the metal-clad laminate on the first polyimide layer side in a 180 DEG direction at a speed of 50 mm/min to determine the force at which peeling occurred between the first polyimide layer and the second polyimide layer.

The abbreviations used in the synthesis examples represent the following compounds.

m-TB: 2,2 '-dimethyl-4, 4' -diaminobiphenyl

TPE-R: 1,3-bis (4-aminophenoxy) benzene

BAPP: 2,2-bis [4- (4-aminophenoxy) phenyl ] propane

TFMB: 2,2 '-bis (trifluoromethyl) -4,4' -diaminobiphenyl

BAFL: 9, 9-bis (4-aminophenyl) fluorene

APB: 1,3-bis (3-aminophenoxy) benzene

TPE-Q: 1, 4-bis (4-aminophenoxy) benzene

4,4' -DAPE: 4,4' -diaminodiphenyl ether

3,4' -DAPE: 3,4' -diaminodiphenyl ether

PDA: p-phenylenediamine

And (3) PMDA: pyromellitic dianhydride

BPDA: 3,3',4' -biphenyltetracarboxylic dianhydride

BTDA: 3,3',4' -benzophenone tetracarboxylic dianhydride

ODPA: 4,4' -oxydiphthalic dianhydride

DMAc: n, N-dimethyl acetamide

(Synthesis example A1)

A1000 ml separable flask was charged with 75.149g of m-TB (353.42mmol) and 850g of DMAc, and the mixture was stirred at room temperature under a nitrogen stream. After complete dissolution, 74.851g of PMDA (342.82mmol) was added and the mixture was stirred at room temperature for 4 hours to obtain polyamic acid solution A-A. The viscosity of the obtained polyamic acid solution A-A was 22,700 cP. The imidized polyimide of the obtained polyamic acid is non-thermoplastic. Further, the CTE of the obtained polyimide film (thickness: 25 μm) was 6.4 ppm/K.

(Synthesis example A2)

A1000 ml separable flask was charged with 65.054g of m-TB (310.65mmol), 10.090g of TPE-R (34.52mmol) and 850g of DMAc, and the mixture was stirred at room temperature under a nitrogen stream. After complete dissolution, 73.856g of PMDA (338.26mmol) was added and the mixture was stirred at room temperature for 4 hours to obtain polyamic acid solutions A to B. The viscosity of the obtained polyamic acid solution A-B was 26,500 cP. Imide of the obtained Polyamic acidThe polyimide after conversion was non-thermoplastic and had a glass transition temperature (Tg) of 303 ℃. The obtained polyimide film (thickness: 25 μm) had a CTE of 16.2ppm/K, a moisture absorption rate of 0.61 wt%, and a moisture permeability of 64g/m²/24hr。

(Synthesis example A3)

A1000 ml separable flask was charged with 89.621g of TFMB (279.33mmol) and 850g of DMAc, and the mixture was stirred at room temperature under a nitrogen stream. After complete dissolution, 60.379g of PMDA (276.54mmol) was added and the mixture was stirred at room temperature for 4 hours to obtain polyamic acid solutions A to C. The viscosity of the obtained polyamic acid solutions A to C was 21,200 cP. The imidized polyimide of the obtained polyamic acid is non-thermoplastic. Further, the CTE of the obtained polyimide film (thickness: 25 μm) was 0.5 ppm/K.

(Synthesis example A4)

A1000 ml separable flask was charged with 49.928g of TFMB (155.70mmol), 33.102g of m-TB (155.70mmol), and 850g of DMAc, and the mixture was stirred at room temperature under a nitrogen stream. After complete dissolution, 66.970g of PMDA (307.03mmol) was added and the mixture was stirred at room temperature for 4 hours to obtain polyamic acid solutions A to D. The viscosity of the obtained polyamic acid solutions A to D was 21,500 cP. The imidized polyimide of the obtained polyamic acid is non-thermoplastic. Further, the CTE of the obtained polyimide film (thickness: 25 μm) was 6.0 ppm/K.

(Synthesis example A5)

A300 ml separable flask was charged with 29.492g of BAPP (71.81mmol) and 255g of DMAc, and the mixture was stirred at room temperature under a nitrogen stream. After complete dissolution, 15.508g of PMDA (71.10mmol) was added and the mixture was stirred at room temperature for 4 hours to obtain polyamic acid solutions A to E. The viscosity of the obtained polyamic acid solutions A to E was 10,700 cP. The imidized polyimide of the obtained polyamic acid was thermoplastic and had a glass transition temperature (Tg) of 312 ℃. The obtained polyimide film (thickness: 25 μm) had a CTE of 63.1ppm/K, a moisture absorption rate of 0.54 wt%, and a moisture permeability of 64g/m²/24hr。

(Synthesis example A6)

A300 ml separable flask was charged with 25.889g of TPE-R (88.50mmol) and 255g of DMAc, and the mixture was stirred at room temperature under a nitrogen stream. After complete dissolution, 19.111g of PMDA (87.62mmol) was added and the mixture was stirred at room temperature for 4 hours to obtain polyamic acid solutions A to F. The viscosity of the obtained polyamic acid solutions A to F was 13,200 cP. The imidized polyimide of the obtained polyamic acid is non-thermoplastic. Further, the CTE of the obtained polyimide film (thickness: 25 μm) was 57.7 ppm/K.

(Synthesis example A7)

A300 ml separable flask was charged with 27.782g of BAFL (79.73mmol) and 255g of DMAc, and the mixture was stirred at room temperature under a nitrogen stream. After complete dissolution, 17.218G of PMDA (78.94mmol) was added and the mixture was stirred at room temperature for 4 hours to obtain polyamic acid solutions A to G. The viscosity of the obtained polyamic acid solutions A to G was 10,400 cP. The imidized polyimide of the obtained polyamic acid is non-thermoplastic. Further, the CTE of the obtained polyimide film (thickness: 25 μm) was 52.0 ppm/K.

Example A1

The polyamic acid solutions A to E to be the first polyimide layers were uniformly applied to an electrolytic copper foil having a thickness of 12 μm so that the cured thickness was 2 μm, and then the temperature was raised from 120 ℃ to 360 ℃ in stages to remove the solvent and imidize the same. Subjecting the obtained first polyimide layer to a treatment of 120 W.min/m²And carrying out corona treatment. Next, the polyamic acid solution a to be the second polyimide layer was uniformly applied thereon so that the cured thickness was 25 μm, and then dried by heating at 120 ℃ for 3 minutes to remove the solvent. Thereafter, the temperature was increased from 130 ℃ to 360 ℃ in stages to effect imidization, thereby producing a metal-clad laminate a 1. The thickness (L1) of the first polyimide layer was 2 μm, the thickness (L) of the entire insulating resin layer was 27 μm, and the ratio (L/L1) was 13.5. An adhesive tape was attached to the resin surface of the prepared metal-clad laminate a1, and a peeling test was performed by instantaneous peeling in the vertical direction, but peeling between the first polyimide layer and the second polyimide layer was not observed.

Example A2

A metal-clad laminate a2 was produced in the same manner as in example a1, except that polyamide acid solutions a to F were used instead of polyamide acid solutions a to E. The peel test of the prepared metal-clad laminate a2 was performed in the same manner as in example a1, but no interlayer peeling was observed between the first polyimide layer and the second polyimide layer.

Example A3

A metal-clad laminate A3 was produced in the same manner as in example a1, except that polyamide acid solutions a to G were used instead of polyamide acid solutions a to E. The peel test of the prepared metal-clad laminate A3 was performed in the same manner as in example a1, but no interlayer peeling was observed between the first polyimide layer and the second polyimide layer.

Example A4

A metal-clad laminate a4 was produced in the same manner as in example a1, except that polyamide acid solutions a to C were used instead of polyamide acid solutions a to E. The peel test of the prepared metal-clad laminate a4 was performed in the same manner as in example a1, but no interlayer peeling was observed between the first polyimide layer and the second polyimide layer.

Example A5

A metal-clad laminate a5 was produced in the same manner as in example a1, except that the polyamic acid solutions a to B were used instead of the polyamic acid solutions a to a. The peel test of the prepared metal-clad laminate a5 was performed in the same manner as in example a1, but no interlayer peeling was observed between the first polyimide layer and the second polyimide layer.

Example A6

Metal-clad laminate a6 was produced in the same manner as in example a1, except that polyamic acid solutions a to B were used instead of polyamic acid solutions a to a and that polyamic acid solutions a to F were used instead of polyamic acid solutions a to E. The peel test of the prepared metal-clad laminate a6 was performed in the same manner as in example a1, but no interlayer peeling was observed between the first polyimide layer and the second polyimide layer.

Example A7

Metal-clad laminate a7 was produced in the same manner as in example a1, except that polyamic acid solutions a to B were used instead of polyamic acid solutions a to a and that polyamic acid solutions a to G were used instead of polyamic acid solutions a to E. The peel test of the prepared metal-clad laminate a7 was performed in the same manner as in example a1, but no interlayer peeling was observed between the first polyimide layer and the second polyimide layer.

Example A8

Metal-clad laminate A8 was produced in the same manner as in example a1, except that polyamic acid solutions a to B were used instead of polyamic acid solutions a to a and a-a were used instead of polyamic acid solutions a to E. The peel test of the prepared metal-clad laminate A8 was performed in the same manner as in example a1, but no interlayer peeling was observed between the first polyimide layer and the second polyimide layer.

Example A9

Metal-clad laminate a9 was produced in the same manner as in example a1, except that polyamic acid solutions a to B were used instead of polyamic acid solutions a to a and that polyamic acid solutions a to C were used instead of polyamic acid solutions a to E. The peel test of the prepared metal-clad laminate a9 was performed in the same manner as in example a1, but no interlayer peeling was observed between the first polyimide layer and the second polyimide layer.

Example A10

A metal-clad laminate a10 was produced in the same manner as in example a1, except that polyamide acid solutions a to C were used instead of polyamide acid solutions a to a. The peel test of the prepared metal-clad laminate a10 was performed in the same manner as in example a1, but no interlayer peeling was observed between the first polyimide layer and the second polyimide layer.

Example A11

Metal-clad laminate a11 was produced in the same manner as in example a1, except that polyamic acid solutions a to C were used instead of polyamic acid solutions a to a and polyamic acid solutions a to F were used instead of polyamic acid solutions a to E. The peel test of the prepared metal-clad laminate a11 was performed in the same manner as in example a1, but no interlayer peeling was observed between the first polyimide layer and the second polyimide layer.

Example A12

Metal-clad laminate a12 was produced in the same manner as in example a1, except that polyamic acid solutions a to C were used instead of polyamic acid solutions a to a and polyamic acid solutions a to G were used instead of polyamic acid solutions a to E. The peel test of the prepared metal-clad laminate a12 was performed in the same manner as in example a1, but no interlayer peeling was observed between the first polyimide layer and the second polyimide layer.

Example A13

Metal-clad laminate a13 was produced in the same manner as in example a1, except that polyamic acid solutions a to C were used instead of polyamic acid solutions a to a and that polyamic acid solutions a to a were used instead of polyamic acid solutions a to E. The peel test of the prepared metal-clad laminate a13 was performed in the same manner as in example a1, but no interlayer peeling was observed between the first polyimide layer and the second polyimide layer.

Example A14

A metal-clad laminate a14 was produced in the same manner as in example a1, except that polyamide acid solutions a to D were used instead of polyamide acid solutions a to a. The peel test of the prepared metal-clad laminate a14 was performed in the same manner as in example a1, but no interlayer peeling was observed between the first polyimide layer and the second polyimide layer.

Example A15

Metal-clad laminate a15 was produced in the same manner as in example a1, except that polyamic acid solutions a to D were used instead of polyamic acid solutions a to a and polyamic acid solutions a to F were used instead of polyamic acid solutions a to E. The peel test of the prepared metal-clad laminate a15 was performed in the same manner as in example a1, but no interlayer peeling was observed between the first polyimide layer and the second polyimide layer.

Example A16

Metal-clad laminate a16 was produced in the same manner as in example a1, except that polyamic acid solutions a to D were used instead of polyamic acid solutions a to a and polyamic acid solutions a to G were used instead of polyamic acid solutions a to E. The peel test of the prepared metal-clad laminate a16 was performed in the same manner as in example a1, but no interlayer peeling was observed between the first polyimide layer and the second polyimide layer.

Example A17

Metal-clad laminate a17 was produced in the same manner as in example a1, except that polyamic acid solutions a to D were used instead of polyamic acid solutions a to a and that polyamic acid solutions a to a were used instead of polyamic acid solutions a to E. The peel test of the prepared metal-clad laminate a17 was performed in the same manner as in example a1, but no interlayer peeling was observed between the first polyimide layer and the second polyimide layer.

Example A18

Metal-clad laminate a18 was produced in the same manner as in example a1, except that polyamic acid solutions a to D were used instead of polyamic acid solutions a to a and polyamic acid solutions a to C were used instead of polyamic acid solutions a to E. The peel test of the prepared metal-clad laminate a18 was performed in the same manner as in example a1, but no interlayer peeling was observed between the first polyimide layer and the second polyimide layer.

Comparative example A1

A metal-clad laminate a19 was produced in the same manner as in example a1, except that the corona treatment was not performed. As a result of a peel test of the prepared metal-clad laminate a19 performed in the same manner as in example a1, interlayer peeling of the first polyimide layer and the second polyimide layer occurred.

Comparative example A2

A metal-clad laminate a20 was produced in the same manner as in example a2, except that the corona treatment was not performed. As a result of a peel test of the prepared metal-clad laminate a20 performed in the same manner as in example a1, interlayer peeling of the first polyimide layer and the second polyimide layer occurred.

Comparative example A3

A metal-clad laminate a21 was produced in the same manner as in example a14, except that the corona treatment was not performed. As a result of a peel test of the prepared metal-clad laminate a21 performed in the same manner as in example a1, interlayer peeling of the first polyimide layer and the second polyimide layer occurred.

Comparative example A4

A metal-clad laminate a22 was produced in the same manner as in example a15, except that the corona treatment was not performed. As a result of a peel test of the prepared metal-clad laminate a22 performed in the same manner as in example a1, interlayer peeling of the first polyimide layer and the second polyimide layer occurred.

Example A19

The polyamic acid solutions A to E to be the first polyimide layers were uniformly applied to an electrolytic copper foil having a thickness of 12 μm so that the cured thickness was 2.5 μm, and then the temperature was raised from 120 ℃ to 360 ℃ in stages to remove the solvent and imidize the same. Subjecting the obtained first polyimide layer to a treatment of 120 W.min/m²And carrying out corona treatment. Next, the polyamic acid solution a to a second polyimide layer was uniformly applied thereon so as to have a cured thickness of 20 μm, and then the polyamic acid solution a to E to a third polyimide layer was uniformly applied thereon so as to have a cured thickness of 2.5 μm, and the solvent was removed by heating and drying at 120 ℃ for 3 minutes. Thereafter, the temperature was increased from 130 ℃ to 360 ℃ in stages to effect imidization, thereby producing a metal-clad laminate a 23. The thickness (L1) of the first polyimide layer was 2.5 μm, the thickness (L) of the entire insulating resin layer was 25 μm, and the ratio (L/L1) was 10.0. No foaming was observed, and no curling of the polyimide film was observed after etching of the copper foil. In addition, the dimensional change rate was "good".

Example A20

A metal-clad laminate a24 was produced in the same manner as in example a19, except that the polyamic acid solutions a to F to be the first polyimide layer and the third polyimide layer were uniformly applied so that the cured thicknesses thereof were 2.7 μm, respectively, and the polyamic acid solution a to be the second polyimide layer was uniformly applied so that the cured thickness thereof was 19.6 μm, respectively, instead of the polyamic acid solutions a to E. The thickness (L1) of the first polyimide layer was 2.7 μm, the thickness (L) of the entire insulating resin layer was 25 μm, and the ratio (L/L1) was 9.3. No foaming was observed, and no curling of the polyimide film was observed after etching of the copper foil. In addition, the dimensional change rate was "good".

Example A21

A metal-clad laminate a25 was produced in the same manner as in example a19, except that the polyamic acid solutions a to G were uniformly applied so that the cured thicknesses thereof were 3.2 μm, respectively, instead of the polyamic acid solutions a to E to become the first polyimide layer and the third polyimide layer, and the polyamic acid solution a to become the second polyimide layer was uniformly applied so that the cured thickness thereof was 18.6 μm, respectively. The thickness (L1) of the first polyimide layer was 3.2 μm, the thickness (L) of the entire insulating resin layer was 25 μm, and the ratio (L/L1) was 7.8. No foaming was observed, and no curling of the polyimide film was observed after etching of the copper foil. In addition, the dimensional change rate is "ok".

Example A22

A metal-clad laminate a26 was produced in the same manner as in example a19, except that the polyamic acid solutions a to E to be the first polyimide layer and the third polyimide layer were uniformly applied so that the cured thicknesses thereof were 1.7 μm, the polyamic acid solution a to be the second polyimide layer was uniformly applied so that the cured thickness thereof was 22 μm, and the temperature increase time from 130 ℃ to 360 ℃ after the application of the polyamic acid solutions a to a and the polyamic acid solutions a to E to be the third polyimide layers was shortened to 1/3. The thickness (L1) of the first polyimide layer was 1.7 μm, the thickness (L) of the entire insulating resin layer was 25.4 μm, and the ratio (L/L1) was 14.9. No foaming was observed, and no curling of the polyimide film was observed after etching of the copper foil. In addition, the dimensional change rate was "good".

Example A23

A metal-clad laminate a27 was produced in the same manner as in example a19, except that the polyamic acid solutions a to E to be the first polyimide layer and the third polyimide layer were uniformly applied so that the cured thicknesses thereof were 1.8 μm, the polyamic acid solution a to be the second polyimide layer was uniformly applied so that the cured thickness thereof was 22 μm, and the temperature increase time from 130 ℃ to 360 ℃ after the application of the polyamic acid solutions a to a and the polyamic acid solutions a to E to be the third polyimide layers was shortened to 1/3. The thickness (L1) of the first polyimide layer was 1.8. mu.m, the thickness (L) of the entire insulating resin layer was 25.6. mu.m, and the ratio (L/L1) was 14.2. No foaming was observed, and no curling of the polyimide film was observed after etching of the copper foil. In addition, the dimensional change rate was "good".

Example A24

A metal-clad laminate a28 was produced in the same manner as in example a19, except that the polyamic acid solutions a to E to be the first polyimide layer and the third polyimide layer were uniformly applied so that the cured thicknesses thereof were 2.2 μm, the polyamic acid solution a to be the second polyimide layer was uniformly applied so that the cured thickness thereof was 20 μm, and the temperature increase time from 130 ℃ to 360 ℃ after the application of the polyamic acid solutions a to a and the polyamic acid solutions a to E to be the third polyimide layers was shortened to 1/3. The thickness (L1) of the first polyimide layer was 2.2 μm, the thickness (L) of the entire insulating resin layer was 24.4 μm, and the ratio (L/L1) was 11.1. No foaming was observed, and no curling of the polyimide film was observed after etching of the copper foil. In addition, the dimensional change rate was "good".

Example A25

A metal-clad laminate a29 was produced in the same manner as in example a19, except that the polyamic acid solutions a to E to be the first polyimide layer and the third polyimide layer were uniformly applied so that the cured thicknesses thereof were 2.4 μm, respectively, and the polyamic acid solutions a to D to be the second polyimide layer were uniformly applied so that the cured thicknesses thereof were 20.2 μm, respectively. The thickness (L1) of the first polyimide layer was 2.4 μm, the thickness (L) of the entire insulating resin layer was 25 μm, and the ratio (L/L1) was 10.4. No foaming was observed, and no curling of the polyimide film was observed after etching of the copper foil. In addition, the dimensional change rate was "good".

Example A26

A metal-clad laminate a30 was produced in the same manner as in example a19, except that the polyamic acid solutions a to F to be the first polyimide layer and the third polyimide layer were uniformly applied so that the cured thicknesses thereof were 2.7 μm, respectively, and the polyamic acid solutions a to D to be the second polyimide layer were uniformly applied so that the cured thicknesses thereof were 20 μm, respectively. The thickness (L1) of the first polyimide layer was 2.7 μm, the thickness (L) of the entire insulating resin layer was 25.4 μm, and the ratio (L/L1) was 9.4. No foaming was observed, and no curling of the polyimide film was observed after etching of the copper foil. In addition, the dimensional change rate was "good".

Example A27

A metal-clad laminate a31 was produced in the same manner as in example a19, except that the polyamic acid solutions a to G to be the first polyimide layer and the third polyimide layer were uniformly applied so that the cured thicknesses thereof were 3.2 μm, respectively, and the polyamic acid solutions a to D to be the second polyimide layer were uniformly applied so that the cured thicknesses thereof were 19 μm, respectively. The thickness (L1) of the first polyimide layer was 3.2 μm, the thickness (L) of the entire insulating resin layer was 25.4 μm, and the ratio (L/L1) was 7.9. No foaming was observed, and no curling of the polyimide film was observed after etching of the copper foil. In addition, the dimensional change rate is "ok".

Example A28

The polyamic acid solutions A to E were uniformly applied to an electrolytic copper foil having a thickness of 12 μm so that the cured thickness was 2.0. mu.m, and then the solvent was removed at 120 ℃. On the surface, polyamic acid solution A-A was uniformly applied to a cured thickness of 50 μm, and then the solvent was removed at 120 ℃ for 3 minutes. Further, the polyamic acid solutions a to E were uniformly applied thereon so that the cured thickness was 2.0 μm, and then the solvent was removed at 120 ℃, and the temperature was increased stepwise from 120 ℃ to 360 ℃ to remove the solvent and imidize, thereby obtaining a single-sided metal-clad laminate a28B in which the first polyimide layer was formed. The polyimide layer of the obtained single-sided metal-clad laminate A28B was coated at 120 W.min/m²And carrying out corona treatment. Next, the polyamic acid solution a to a second polyimide layer was uniformly applied thereon so as to have a cured thickness of 50 μm, and after the solvent was removed, the polyamic acid solution a to E to a third polyimide layer was uniformly applied thereon so as to have a cured thickness of 2.0 μm, and the solvent was removed by heating and drying at 120 ℃ for 3 minutes. After thatThen, the temperature was increased stepwise from 130 ℃ to 360 ℃ to effect imidization, thereby producing a single-sided metal-clad laminate A28. The thickness (L1) of the first polyimide layer was 54 μm, the thickness (L) of the entire insulating resin layer was 106 μm, and the ratio (L/L1) was 1.96. No foaming was observed, and no curling of the polyimide film was observed after etching of the copper foil. In addition, the dimensional change rate was "good".

Example A29

A single-sided metal-clad laminate a29 was produced in the same manner as in example a28, except that the polyamic acid solutions a to E constituting two of the first polyimide layers and the polyamic acid solutions a to E constituting the third polyimide layers were uniformly applied so that the cured thicknesses thereof were 10 μm, respectively. The thickness (L1) of the first polyimide layer was 70 μm, the thickness (L) of the entire insulating resin layer was 130 μm, and the ratio (L/L1) was 1.86. No foaming was observed, and no curling of the polyimide film was observed after etching of the copper foil. In addition, the dimensional change rate was "good".

Example A30

A single-sided metal-clad laminate a30 was prepared in the same manner as in example a28, except that the polyamic acid solutions a to E for forming two layers of the first polyimide layer and the polyamic acid solutions a to E for forming the third polyimide layer were each polyamic acid solutions a to F and were uniformly applied so that the cured thickness was 2.0 μm, and the polyamic acid solutions a to B for forming the second polyimide layer were uniformly applied so that the cured thickness was 50 μm. The thickness (L1) of the first polyimide layer was 54 μm, the thickness (L) of the entire insulating resin layer was 106 μm, and the ratio (L/L1) was 1.96. No foaming was observed, and no curling of the polyimide film was observed after etching of the copper foil. In addition, the dimensional change rate was "good".

Example A31

A single-sided metal-clad laminate a31 was produced in the same manner as in example a30, except that the polyamic acid solutions a to F for forming two layers of the first polyimide layer and the polyamic acid solutions a to F for forming the third polyimide layer were uniformly applied so that the cured thicknesses thereof were 10 μm, respectively. The thickness (L1) of the first polyimide layer was 70 μm, the thickness (L) of the entire insulating resin layer was 130 μm, and the ratio (L/L1) was 1.86. No foaming was observed, and no curling of the polyimide film was observed after etching of the copper foil. In addition, the dimensional change rate was "good".

Comparative example A5

A metal-clad laminate a32 was produced in the same manner as in example a19, except that the corona treatment was not performed, and as a result, curling of the polyimide film was confirmed after etching of the copper foil.

Comparative example A6

A metal-clad laminate a33 was produced in the same manner as in example a20, except that the corona treatment was not performed, and as a result, curling of the polyimide film was confirmed after etching of the copper foil.

Comparative example A7

A metal-clad laminate a34 was produced in the same manner as in example a21, except that the corona treatment was not performed, and as a result, curling of the polyimide film was confirmed after etching of the copper foil.

Comparative example A8

A metal-clad laminate a35 was produced in the same manner as in example a22, except that the corona treatment was not performed, and foaming was confirmed.

Comparative example A9

A metal-clad laminate a36 was produced in the same manner as in example a23, except that the corona treatment was not performed, and foaming was confirmed.

Comparative example A10

A metal-clad laminate a37 was produced in the same manner as in example a24, except that the corona treatment was not performed, and foaming was confirmed.

(Synthesis example B1)

A1000 ml separable flask was charged with 75.149g of m-TB (353.42mmol) and 850g of DMAc, and the mixture was stirred at room temperature under a nitrogen stream. After complete dissolution, 74.851g of PMDA (342.82mmol) was added and the mixture was stirred at room temperature for 4 hours to obtain a polyamic acid solution B-A. The viscosity of the obtained polyamic acid solution B-A was 22,700 cP.

(Synthesis example B2)

A1000 ml separable flask was charged with 65.054g of m-TB (310.65mmol), 10.090g of TPE-R (34.52mmol) and 850g of DMAc, and the mixture was stirred at room temperature under a nitrogen stream. After complete dissolution, 73.856g of PMDA (338.26mmol) was added and the mixture was stirred at room temperature for 4 hours to obtain polyamic acid solutions B to B. The viscosity of the obtained polyamic acid solution B-B was 26,500 cP.

(Synthesis example B3)

A1000 ml separable flask was charged with 89.621g of TFMB (279.33mmol) and 850g of DMAc, and the mixture was stirred at room temperature under a nitrogen stream. After complete dissolution, 60.379g of PMDA (276.54mmol) was added and the mixture was stirred at room temperature for 4 hours to obtain polyamic acid solutions B to C. The viscosity of the obtained polyamic acid solution B to C was 21,200 cP.

(Synthesis example B4)

A1000 ml separable flask was charged with 49.928g of TFMB (155.70mmol), 33.102g of m-TB (155.70mmol), and 850g of DMAc, and the mixture was stirred at room temperature under a nitrogen stream. After complete dissolution, 66.970g of PMDA (307.03mmol) was added and the mixture was stirred at room temperature for 4 hours to obtain polyamic acid solutions B to D. The viscosity of the obtained polyamic acid solutions B to D was 21,500 cP.

(Synthesis example B5)

A300 ml separable flask was charged with 29.492g of BAPP (71.81mmol) and 255g of DMAc, and the mixture was stirred at room temperature under a nitrogen stream. After complete dissolution, 15.508g of PMDA (71.10mmol) was added and the mixture was stirred at room temperature for 4 hours to obtain polyamic acid solutions B to E. The viscosity of the obtained polyamic acid solutions B to E was 10,700 cP.

(Synthesis example B6)

A300 ml separable flask was charged with 25.889g of TPE-R (88.50mmol) and 255g of DMAc, and the mixture was stirred at room temperature under a nitrogen stream. After complete dissolution, 19.111g of PMDA (87.62mmol) was added and the mixture was stirred at room temperature for 4 hours to obtain polyamic acid solutions B to F. The viscosity of the obtained polyamic acid solutions B to F was 13,200 cP.

(Synthesis example B7)

A300 ml separable flask was charged with 27.782g of BAFL (79.73mmol) and 255g of DMAc, and the mixture was stirred at room temperature under a nitrogen stream. After complete dissolution, 17.218G of PMDA (78.94mmol) was added and the mixture was stirred at room temperature for 4 hours to obtain polyamic acid solutions B to G. The viscosity of the obtained polyamic acid solutions B to G was 10,400 cP.

Example B1

The polyamic acid solutions B to E to be the first polyimide layers were uniformly applied to an electrolytic copper foil having a thickness of 12 μm so that the cured thickness was 2 μm, and then the temperature was raised from 120 ℃ to 240 ℃ in stages to remove an appropriate solvent and imidize the same. In this case, the volatilization fraction and imidization ratio of the first polyimide layer in a semi-cured state were 3.0% and 80%. Next, the polyamic acid solution B-a to be the second polyimide layer was uniformly applied thereon so that the cured thickness was 25 μm, and then dried by heating at 120 ℃ for 3 minutes to remove the solvent. Thereafter, the temperature was increased from 130 ℃ to 360 ℃ in stages to perform imidization, thereby forming a first polyimide layer and a second polyimide layer, and thus a metal-clad laminate B1 was prepared. An adhesive tape was attached to the resin surface of the prepared metal-clad laminate B1, and a peeling test was performed by instantaneous peeling in the vertical direction, but peeling between the first polyimide layer and the second polyimide layer was not observed.

Example B2

A metal-clad laminate B2 was produced in the same manner as in example B1, except that polyamic acid solutions B to F were used instead of polyamic acid solutions B to E. In this case, the volatilization fraction and imidization ratio of the first polyimide layer in a semi-cured state were 5.6% and 55%. The peel test of the prepared metal-clad laminate B2 was performed in the same manner as in example B1, but no interlayer peeling was observed between the first polyimide layer and the second polyimide layer.

Example B3

A metal-clad laminate B3 was produced in the same manner as in example B1, except that polyamic acid solutions B to G were used instead of polyamic acid solutions B to E. In this case, the volatilization fraction and imidization ratio of the first polyimide layer in a semi-cured state were 6.7% and 28%. The peel test of the prepared metal-clad laminate B3 was performed in the same manner as in example B1, but no interlayer peeling was observed between the first polyimide layer and the second polyimide layer.

Example B4

A metal-clad laminate B4 was produced in the same manner as in example B1, except that polyamic acid solutions B to C were used instead of polyamic acid solutions B to E. In this case, the volatilization fraction and imidization ratio of the first polyimide layer in a semi-cured state were 2.6% and 73%. The peel test of the prepared metal-clad laminate B4 was performed in the same manner as in example B1, but no interlayer peeling was observed between the first polyimide layer and the second polyimide layer.

Example B5

A metal-clad laminate B5 was produced in the same manner as in example B1, except that the polyamic acid solution B-B was used instead of the polyamic acid solution B-a. In this case, the volatilization fraction and imidization ratio of the first polyimide layer in a semi-cured state were 3.2% and 70%. The peel test of the prepared metal-clad laminate B5 was performed in the same manner as in example B1, but no interlayer peeling was observed between the first polyimide layer and the second polyimide layer.

Example B6

Metal-clad laminate B6 was produced in the same manner as in example B1, except that polyamic acid solutions B to B were used instead of polyamic acid solutions B to a and polyamic acid solutions B to F were used instead of polyamic acid solutions B to E. In this case, the volatilization fraction and imidization ratio of the first polyimide layer in a semi-cured state were 4.0% and 65%. The peel test of the prepared metal-clad laminate B6 was performed in the same manner as in example B1, but no interlayer peeling was observed between the first polyimide layer and the second polyimide layer.

Example B7

Metal-clad laminate B7 was produced in the same manner as in example B1, except that polyamic acid solutions B to B were used instead of polyamic acid solutions B to a and polyamic acid solutions B to G were used instead of polyamic acid solutions B to E. In this case, the volatilization fraction and imidization ratio of the first polyimide layer in a semi-cured state were 5.5% and 53%. The peel test of the prepared metal-clad laminate B7 was performed in the same manner as in example B1, but no interlayer peeling was observed between the first polyimide layer and the second polyimide layer.

Example B8

Metal-clad laminate B8 was produced in the same manner as in example B1, except that polyamic acid solution B-B was used instead of polyamic acid solution B-a and polyamic acid solution B-a was used instead of polyamic acid solution B-E. In this case, the volatilization fraction and imidization ratio of the first polyimide layer in a semi-cured state were 4.0% and 66%. The peel test of the prepared metal-clad laminate B8 was performed in the same manner as in example B1, but no interlayer peeling was observed between the first polyimide layer and the second polyimide layer.

Example B9

Metal-clad laminate B9 was produced in the same manner as in example B1, except that polyamic acid solutions B to B were used instead of polyamic acid solutions B to a and polyamic acid solutions B to C were used instead of polyamic acid solutions B to E. In this case, the volatilization fraction and imidization ratio of the first polyimide layer in a semi-cured state were 1.2% and 80%. The peel test of the prepared metal-clad laminate B9 was performed in the same manner as in example B1, but no interlayer peeling was observed between the first polyimide layer and the second polyimide layer.

Example B10

A metal-clad laminate B10 was produced in the same manner as in example B1, except that polyamic acid solutions B to C were used instead of polyamic acid solutions B to a. In this case, the volatilization fraction and imidization ratio of the first polyimide layer in a semi-cured state were 2.6% and 83%. The peel test of the prepared metal-clad laminate B10 was performed in the same manner as in example B1, but no interlayer peeling was observed between the first polyimide layer and the second polyimide layer.

Example B11

Metal-clad laminate B11 was produced in the same manner as in example B1, except that polyamic acid solutions B to C were used instead of polyamic acid solutions B to a, and polyamic acid solutions B to F were used instead of polyamic acid solutions B to E. In this case, the volatilization fraction and imidization ratio of the first polyimide layer in a semi-cured state were 4.4% and 59%. The peel test of the prepared metal-clad laminate B11 was performed in the same manner as in example B1, but no interlayer peeling was observed between the first polyimide layer and the second polyimide layer.

Example B12

Metal-clad laminate B12 was produced in the same manner as in example B1, except that polyamic acid solutions B to C were used instead of polyamic acid solutions B to a, and polyamic acid solutions B to G were used instead of polyamic acid solutions B to E. In this case, the volatilization fraction and imidization ratio of the first polyimide layer in a semi-cured state were 10.1% and 23%. The peel test of the prepared metal-clad laminate B12 was performed in the same manner as in example B1, but no interlayer peeling was observed between the first polyimide layer and the second polyimide layer.

Example B13

Metal-clad laminate B13 was produced in the same manner as in example B1, except that polyamic acid solutions B to C were used instead of polyamic acid solutions B to a and polyamic acid solutions B to a were used instead of polyamic acid solutions B to E. In this case, the volatilization fraction and imidization ratio of the first polyimide layer in a semi-cured state were 10.0% and 22%. The peel test of the prepared metal-clad laminate B13 was performed in the same manner as in example B1, but no interlayer peeling was observed between the first polyimide layer and the second polyimide layer.

Example B14

A metal-clad laminate B14 was produced in the same manner as in example B1, except that polyamic acid solutions B to D were used instead of polyamic acid solutions B to a. In this case, the volatilization fraction and imidization ratio of the first polyimide layer in a semi-cured state were 15.1% and 20%. The peel test of the prepared metal-clad laminate B14 was performed in the same manner as in example B1, but no interlayer peeling was observed between the first polyimide layer and the second polyimide layer.

Example B15

Metal-clad laminate B15 was produced in the same manner as in example B1, except that polyamic acid solutions B to D were used instead of polyamic acid solutions B to a, and polyamic acid solutions B to F were used instead of polyamic acid solutions B to E. In this case, the volatilization fraction and imidization ratio of the first polyimide layer in a semi-cured state were 8.3% and 31%. The peel test of the prepared metal-clad laminate B15 was performed in the same manner as in example B1, but no interlayer peeling was observed between the first polyimide layer and the second polyimide layer.

Example B16

Metal-clad laminate B16 was produced in the same manner as in example B1, except that polyamic acid solutions B to D were used instead of polyamic acid solutions B to a, and polyamic acid solutions B to G were used instead of polyamic acid solutions B to E. In this case, the volatilization fraction and imidization ratio of the first polyimide layer in a semi-cured state were 12.0% and 22%. The peel test of the prepared metal-clad laminate B16 was performed in the same manner as in example B1, but no interlayer peeling was observed between the first polyimide layer and the second polyimide layer.

Example B17

Metal-clad laminate B17 was produced in the same manner as in example B1, except that polyamic acid solutions B to D were used instead of polyamic acid solutions B to a and polyamic acid solutions B to a were used instead of polyamic acid solutions B to E. In this case, the volatilization fraction and imidization ratio of the first polyimide layer in a semi-cured state were 7.0% and 25%. The peel test of the prepared metal-clad laminate B17 was performed in the same manner as in example B1, but no interlayer peeling was observed between the first polyimide layer and the second polyimide layer.

Example B18

Metal-clad laminate B18 was produced in the same manner as in example B1, except that polyamic acid solutions B to D were used instead of polyamic acid solutions B to a, and polyamic acid solutions B to C were used instead of polyamic acid solutions B to E. In this case, the volatilization fraction and imidization ratio of the first polyimide layer in a semi-cured state were 8.2% and 21%. The peel test of the prepared metal-clad laminate B18 was performed in the same manner as in example B1, but no interlayer peeling was observed between the first polyimide layer and the second polyimide layer.

Comparative example B1

A metal-clad laminate B19 was produced in the same manner as in example B1, except that the polyamic acid solution to be the first polyimide layer was gradually heated to 360 ℃ from 120 ℃. In this case, the volatilization fraction and imidization ratio of the first polyimide layer were 0.0% and 100%. As a result of a peel test of the prepared metal-clad laminate B19, interlayer peeling of the first polyimide layer and the second polyimide layer was generated in the same manner as in example B1.

Comparative example B2

A metal-clad laminate B20 was produced in the same manner as in example B2, except that the polyamic acid solution to be the first polyimide layer was gradually heated to 360 ℃ from 120 ℃. In this case, the volatilization fraction and imidization ratio of the first polyimide layer were 0.0% and 100%. As a result of a peel test of the prepared metal-clad laminate B20, interlayer peeling of the first polyimide layer and the second polyimide layer was generated in the same manner as in example B1.

Comparative example B3

A metal-clad laminate B21 was produced in the same manner as in example B14, except that the polyamic acid solution to be the first polyimide layer was gradually heated to 360 ℃ from 120 ℃. In this case, the volatilization fraction and imidization ratio of the first polyimide layer were 0.0% and 100%. As a result of a peel test of the prepared metal-clad laminate B21, interlayer peeling of the first polyimide layer and the second polyimide layer was generated in the same manner as in example B1.

Comparative example B4

A metal-clad laminate B22 was produced in the same manner as in example B15, except that the polyamic acid solution to be the first polyimide layer was gradually heated to 360 ℃ from 120 ℃. In this case, the volatilization fraction and imidization ratio of the first polyimide layer were 0.0% and 100%. As a result of a peel test of the prepared metal-clad laminate B22, interlayer peeling of the first polyimide layer and the second polyimide layer was generated in the same manner as in example B1.

Example B19

The polyamic acid solutions B to E to be the first polyimide layers were uniformly applied to an electrolytic copper foil having a thickness of 12 μm so that the cured thickness was 2.5 μm, and then the temperature was raised from 120 ℃ to 240 ℃ in stages to remove an appropriate solvent and imidize the same. In this case, the volatilization fraction and imidization ratio of the first polyimide layer in a semi-cured state were 5.5% and 53%. Next, the polyamic acid solution B-a to be the second polyimide layer was uniformly applied thereon so as to have a cured thickness of 20 μm, and then the polyamic acid solution B-E to be the third polyimide layer was uniformly applied thereon so as to have a cured thickness of 2.5 μm, and the solvent was removed by heating and drying at 120 ℃ for 3 minutes. Thereafter, the temperature was increased stepwise from 130 ℃ to 360 ℃ to effect imidization, thereby producing a metal-clad laminate B23, but foaming was not observed, and curling of the polyimide film was not observed even after etching of the copper foil. In addition, the dimensional change rate was "good".

Example B20

A metal-clad laminate B24 was produced in the same manner as in example B19, except that the polyamic acid solutions B to F were uniformly applied so that the cured thicknesses thereof were 2.7 μm and the polyamic acid solution B to a was uniformly applied so that the cured thickness thereof was 19.6 μm, instead of the polyamic acid solutions B to E of the first polyimide layer and the third polyimide layer, respectively, and that curling of the polyimide film was not observed after etching of the copper foil. In addition, the dimensional change rate was "good". In this case, the volatilization fraction and imidization ratio of the first polyimide layer in a semi-cured state were 2.6% and 83%.

Example B21

A metal-clad laminate B25 was produced in the same manner as in example B19, except that the polyamic acid solutions B to G were uniformly applied so that the cured thicknesses thereof were 3.2 μm, respectively, instead of the polyamic acid solutions B to E to form the first polyimide layer and the third polyimide layer, and the polyamic acid solution B to a to form the second polyimide layer was uniformly applied so that the cured thickness thereof was 18.6 μm, respectively, but foaming was not confirmed, and curling of the polyimide film was not confirmed after etching of the copper foil. In addition, the dimensional change rate is "ok". In this case, the volatilization fraction and imidization ratio of the first polyimide layer in a semi-cured state were 3.2% and 70%.

Example B22

A metal-clad laminate B26 was prepared in the same manner as in example B19, except that the polyamic acid solutions B to E to become the first polyimide layer and the third polyimide layer were uniformly applied so that the cured thicknesses thereof were 1.7 μm, the polyamic acid solution B to a to become the second polyimide layer was uniformly applied so that the cured thicknesses thereof were 22 μm, and the temperature increase time from 130 ℃ to 360 ℃ after the application of the polyamic acid solutions B to a and the polyamic acid solutions B to E to become the third polyimide layers was shortened to 1/3. In addition, the dimensional change rate was "good". In this case, the volatilization fraction and imidization ratio of the first polyimide layer in a semi-cured state were 10.1% and 23%.

Example B23

A metal-clad laminate B27 was prepared in the same manner as in example B19, except that the polyamic acid solutions B to E to become the first polyimide layer and the third polyimide layer were uniformly applied so that the cured thicknesses thereof were 1.8 μm, the polyamic acid solution B to a to become the second polyimide layer was uniformly applied so that the cured thicknesses thereof were 22 μm, and the temperature increase time from 130 ℃ to 360 ℃ after the application of the polyamic acid solutions B to a and the polyamic acid solutions B to E to become the third polyimide layers was shortened to 1/3. In addition, the dimensional change rate was "good". In this case, the volatilization fraction and imidization ratio of the first polyimide layer in a semi-cured state were 6.7% and 28%.

Example B24

A metal-clad laminate B28 was prepared in the same manner as in example B19, except that the polyamic acid solutions B to E to become the first polyimide layer and the third polyimide layer were uniformly applied so that the cured thicknesses thereof were 2.2 μm, the polyamic acid solution B to a to become the second polyimide layer was uniformly applied so that the cured thicknesses thereof were 20 μm, and the temperature increase time from 130 ℃ to 360 ℃ after the application of the polyamic acid solutions B to a and the polyamic acid solutions B to E to become the third polyimide layer was shortened to 1/3. In addition, the dimensional change rate was "good". In this case, the volatilization fraction and imidization ratio of the first polyimide layer in a semi-cured state were 15.1% and 20%.

Example B25

A metal-clad laminate B29 was prepared in the same manner as in example B19, except that the polyamic acid solutions B to E to become the first polyimide layer and the third polyimide layer were uniformly applied so that the cured thicknesses thereof were 2.4 μm, and the polyamic acid solutions B to D to become the second polyimide layer were uniformly applied so that the cured thicknesses thereof were 20 μm. In addition, the dimensional change rate was "good". In this case, the volatilization fraction and imidization ratio of the first polyimide layer in a semi-cured state were 15.1% and 20%.

Example B26

A metal-clad laminate B30 was prepared in the same manner as in example B19, except that the polyamic acid solutions B to F to be the first polyimide layer and the third polyimide layer were uniformly applied so that the cured thicknesses thereof were 2.7 μm, and the polyamic acid solutions B to D to be the second polyimide layer were uniformly applied so that the cured thicknesses thereof were 20 μm. In addition, the dimensional change rate was "good". In this case, the volatilization fraction and imidization ratio of the first polyimide layer in a semi-cured state were 8.3% and 31%.

Example B27

A metal-clad laminate B31 was prepared in the same manner as in example B19, except that the polyamic acid solutions B to G to be the first polyimide layer and the third polyimide layer were uniformly applied so that the cured thicknesses thereof were 3.2 μm, and the polyamic acid solutions B to D to be the second polyimide layer were uniformly applied so that the cured thicknesses thereof were 19 μm. In addition, the dimensional change rate is "ok". In this case, the volatilization fraction and imidization ratio of the first polyimide layer in a semi-cured state were 12.0% and 22%.

Comparative example B5

A metal-clad laminate B32 was produced in the same manner as in example B19, except that the polyamic acid solution to be the first polyimide layer was dried by heating at 120 ℃ for 3 minutes, and as a result, curling of the polyimide film was confirmed after etching of the copper foil. In this case, the volatilization fraction and imidization ratio in the state in which the layer to be the first polyimide layer was dried by heating were 35.0% and 0%.

Comparative example B6

A metal-clad laminate B33 was produced in the same manner as in example B20, except that the polyamic acid solution to be the first polyimide layer was dried by heating at 120 ℃ for 3 minutes, and as a result, curling of the polyimide film was confirmed after etching of the copper foil. In this case, the volatilization fraction and imidization ratio in the state in which the layer to be the first polyimide layer was dried by heating were 32.0% and 0%.

Comparative example B7

A metal-clad laminate B34 was produced in the same manner as in example B21, except that the polyamic acid solution to be the first polyimide layer was dried by heating at 120 ℃ for 3 minutes, and as a result, curling of the polyimide film was confirmed after etching of the copper foil. In this case, the volatilization fraction and imidization ratio in the state in which the layer to be the first polyimide layer was dried by heating were 30.0% and 0%.

Comparative example B8

Metal-clad laminate B35 was prepared in the same manner as in example B22, except that the polyamic acid solution to be the first polyimide layer was dried by heating at 120 ℃ for 3 minutes, and as a result, foaming was confirmed. In this case, the volatilization fraction and imidization ratio in the state in which the layer to be the first polyimide layer was dried by heating were 34.0% and 0%.

Comparative example B9

Metal-clad laminate B36 was prepared in the same manner as in example B23, except that the polyamic acid solution to be the first polyimide layer was dried by heating at 120 ℃ for 3 minutes, and as a result, foaming was confirmed. In this case, the volatilization fraction and imidization ratio in the state in which the layer to be the first polyimide layer was dried by heating were 30.0% and 0%.

Comparative example B10

Metal-clad laminate B37 was prepared in the same manner as in example B24, except that the polyamic acid solution to be the first polyimide layer was dried by heating at 120 ℃ for 3 minutes, and as a result, foaming was confirmed. In this case, the volatilization fraction and imidization ratio in the state in which the layer to be the first polyimide layer was dried by heating were 31.0% and 0%.

(Synthesis example C1)

A1000 ml separable flask was charged with 45.989g of m-TB (216.63mmol), 15.832g of TPE-R (54.16mmol), and 680g of DMAc, and the mixture was stirred at room temperature under a nitrogen stream. After complete dissolution, 58.179g of PMDA (266.73mmol) was added and the mixture was stirred at room temperature for 4 hours to obtain a polyamic acid solution C-A. The viscosity of the obtained polyamic acid solution C-A was 22,000 cP.

(Synthesis example C2)

9.244g of 4,4' -DAPE (46.16mmol) and 176g of DMAc were put into a 300ml separable flask, and the mixture was stirred at room temperature under a nitrogen stream. After completely dissolving, 14.756g of BTDA (45.79mmol) was added thereto, and the mixture was stirred at room temperature for 4 hours to obtain polyamic acid solution C-B. The viscosity of the obtained polyamic acid solution C-B was 1,200 cP.

(Synthesis example C3)

11.464g of TPE-Q (39.22mmol) and 176g of DMAc were put into a 300ml separable flask, and stirred at room temperature under a nitrogen stream. After complete dissolution, 12.536g of BTDA (38.90mmol) was added, and the mixture was stirred at room temperature for 4 hours to obtain polyamic acid solutions C to C. The viscosity of the obtained polyamic acid solution C-C was 2,200 cP.

(Synthesis example C4)

A300 ml separable flask was charged with 11.464g of TPE-R (39.22mmol) and 176g of DMAc, and the mixture was stirred at room temperature under a nitrogen stream. After complete dissolution, 12.536g of BTDA (38.90mmol) was added, and the mixture was stirred at room temperature for 4 hours to obtain polyamic acid solutions C to D. The viscosity of the obtained polyamic acid solutions C to D was 1,100 cP.

(Synthesis example C5)

A300 ml separable flask was charged with 11.386g of APB (38.95mmol) and 176g of DMAc, and the mixture was stirred at room temperature under a nitrogen stream. After completely dissolving, 12.614g of BTDA (39.14mmol) was added thereto, and the mixture was stirred at room temperature for 4 hours to obtain polyamic acid solutions C to E. The viscosity of the obtained polyamic acid solutions C to E was 200 cP.

(Synthesis example C6)

A300 ml separable flask was charged with 13.493g of BAPP (32.87mmol) and 176g of DMAc, and the mixture was stirred at room temperature under a nitrogen stream. After completely dissolving, 10.507g of BTDA (32.61mmol) was added thereto, and the mixture was stirred at room temperature for 4 hours to obtain polyamic acid solutions C to F. The viscosity of the obtained polyamic acid solutions C to F was 1,400 cP.

(Synthesis example C7)

9.227g of 3,4' -DAPE (46.08mmol) and 176g of DMAc were put into a 300ml separable flask, and stirred at room temperature under a nitrogen stream. After completely dissolving, 14.773G of BTDA (45.85mmol) was added thereto, and the mixture was stirred at room temperature for 4 hours to obtain polyamic acid solutions C to G. The viscosity of the obtained polyamic acid solutions C to G was 500 cP.

(Synthesis example C8)

A300 ml separable flask was charged with 4.660g of PDA (43.09mmol), 2.157g of 4,4' -DAPE (10.77mmol) and 176g of DMAc, and the mixture was stirred at room temperature under a nitrogen stream. After complete dissolution, 17.183g of BTDA (53.33mmol) was added, and the mixture was stirred at room temperature for 4 hours to obtain polyamic acid solutions C to H. The viscosity of the obtained polyamic acid solution C to H was 1,500 cP.

(Synthesis example C9)

A300 ml separable flask was charged with 12.053g of TFMB (37.64mmol) and 176g of DMAc, and the mixture was stirred at room temperature under a nitrogen stream. After complete dissolution, 11.947g of BTDA (37.07mmol) was added thereto, and the mixture was stirred at room temperature for 4 hours to obtain a polyamic acid solution C-I. The viscosity of the obtained polyamic acid solution C-I was 1,200 cP.

(Synthesis example C10)

9.498g of 4,4' -DAPE (47.43mmol) and 176g of DMAc were put into a 300ml separable flask, and stirred at room temperature under a nitrogen stream. After completely dissolving, 7.581g of BTDA (23.53mmol) and 6.922g of BPDA (23.53mmol) were added, and the mixture was stirred at room temperature for 4 hours to obtain polyamic acid solutions C to J. The viscosity of the obtained polyamic acid solution C to J was 2,500 cP.

(Synthesis example C11)

9.727g of 4,4' -DAPE (48.58mmol) and 176g of DMAc were put into a 300ml separable flask, and stirred at room temperature under a nitrogen stream. After complete dissolution, 11.646g of BTDA (36.14mmol) and 2.628g of PMDA (12.05mmol) were added thereto, and the mixture was stirred at room temperature for 4 hours to obtain a polyamic acid solution C-K. The viscosity of the obtained polyamic acid solution C-K was 1,100 cP.

(Synthesis example C12)

A300 ml separable flask was charged with 4.575g of 4,4' -DAPE (22.85mmol), 4.850g of m-TB (22.85mmol) and 176g of DMAc, and the mixture was stirred at room temperature under a nitrogen stream. After completely dissolving, 14.576g of BTDA (45.23mmol) was added thereto, and the mixture was stirred at room temperature for 4 hours to obtain polyamic acid solutions C to L. The viscosity of the obtained polyamic acid solution C-L was 1,100 cP.

(Synthesis example C13)

A300 ml separable flask was charged with 9.807g of 4,4' -DAPE (48.97mmol) and 176g of DMAc, and the mixture was stirred at room temperature under a nitrogen stream. After complete dissolution, 14.193g of BPDA (48.24mmol) was added and stirred at room temperature for 4 hours to obtain a polyamic acid solution C-M. The viscosity of the obtained polyamic acid solution C-M was 1,000 cP.

(Synthesis example C14)

A1000 ml separable flask was charged with 62.734g of BAPP (152.82mmol) and 704g of DMAc, and the mixture was stirred at room temperature under a nitrogen stream. After complete dissolution, 33.266g of PMDA (152.51mmol) was added and the mixture was stirred at room temperature for 4 hours to obtain polyamic acid solutions C to N. The viscosity of the obtained polyamic acid solution C-N was 4,800 cP.

(Synthesis example C15)

38.27g of m-TB (180.27mmol) and 704g of DMAc were put into a 1000ml separable flask, and the mixture was stirred at room temperature under a nitrogen stream. After completely dissolving, 57.102g of BTDA (177.21mmol) and 0.629g of PMDA (2.88mmol) were added, and the mixture was stirred at room temperature for 4 hours to obtain a polyamic acid solution C-O. The viscosity of the obtained polyamic acid solution C to O was 43,000 cP.

(Synthesis example C16)

A1000 ml separable flask was charged with 19.536g of PDA (180.66mmol), 13.087g of BAPP (31.88mmol) and 704g of DMAc, and the mixture was stirred at room temperature under a nitrogen stream. After complete dissolution, 56.73g of BPDA (192.82mmol) and 6.646g of ODPA (21.42mmol) were added thereto, and the mixture was stirred at room temperature for 4 hours to obtain a polyamic acid solution C-P. The viscosity of the obtained polyamic acid solution C-P was 51,000 cP.

(Synthesis example C17)

A1000 ml separable flask was charged with 76.91g of BAPP (187.35mmol) and 680g of DMAc, and the mixture was stirred at room temperature under a nitrogen stream. After complete dissolution, 34.805g of PMDA (159.57mmol) and 8.285g of BPDA (28.16mmol) were added thereto, and the mixture was stirred at room temperature for 4 hours to obtain a polyamic acid solution C-Q. The viscosity of the obtained polyamic acid solution C to Q was 9,500 cP.

(Synthesis example C18)

A1000 ml separable flask was charged with 77.298g of BAPP (188.30mmol) and 680g of DMAc, and the mixture was stirred at room temperature under a nitrogen stream. After complete dissolution, 34.492g of PMDA (158.13mmol) and 8.210g of BPDA (27.91mmol) were added thereto, and the mixture was stirred at room temperature for 4 hours to obtain a polyamic acid solution C-R. The viscosity of the obtained polyamic acid solution C-R was 2,200 cP.

(Synthesis example C19)

A1000 ml separable flask was charged with 50.803g of m-TB (239.31mmol), 7.773g of TPE-R (26.59mmol) and 680g of DMAc, and the mixture was stirred at room temperature under a nitrogen stream. After complete dissolution, 45.934g of PMDA (210.59mmol) and 15.490g of BPDA (52.65mmol) were added thereto, and the mixture was stirred at room temperature for 4 hours to obtain a polyamic acid solution C-S. The viscosity of the obtained polyamic acid solution C-S was 23,000 cP.

(Synthesis example C20)

A1000 ml separable flask was charged with 44.203g of m-TB (208.22mmol), 6.763g of TPE-R (23.14mmol) and 680g of DMAc, and the mixture was stirred at room temperature under a nitrogen stream. After complete dissolution, 59.043g of BTDA (183.23mmol) and 9.992g of PMDA (45.81mmol) were added thereto, and the mixture was stirred at room temperature for 4 hours to obtain a polyamic acid solution C-T. The viscosity of the obtained polyamic acid solution C-T was 12,000 cP.

(Synthesis example C21)

A1000 ml separable flask was charged with 33.475g of TPE-R (114.51mmol), 14.346g of TPE-Q (49.08mmol), and 704g of DMAc, and the mixture was stirred at room temperature under a nitrogen stream. After complete dissolution, 48.179g of BPDA (163.75mmol) was added thereto, and the mixture was stirred at room temperature for 4 hours to obtain a polyamic acid solution C-U. The viscosity of the obtained polyamic acid solution C-U was 15,000 cP.

(Synthesis example C22)

A1000 ml separable flask was charged with 33.542g of TPE-R (114.74mmol), 14.375g of TPE-Q (49.17mmol), and 704g of DMAc, and the mixture was stirred at room temperature under a nitrogen stream. After complete dissolution, 48.083g of BPDA (163.42mmol) was added thereto, and the mixture was stirred at room temperature for 4 hours to obtain polyamic acid solutions C to V. The viscosity of the obtained polyamic acid solution C to V was 10,000 cP.

[ example C1]

A polyamic acid solution C-B to be a first polyimide layer was uniformly applied to an electrolytic copper foil having a thickness of 12 μm so that the cured thickness was 2 μm, and then the temperature was raised from 120 ℃ to 360 ℃ in stages to remove the solvent and imidize the same. Next, the polyamic acid solution C-a to be the second polyimide layer was uniformly applied thereon so that the cured thickness was 25 μm, and then dried by heating at 120 ℃ for 3 minutes to remove the solvent. Thereafter, the temperature was increased stepwise from 130 ℃ to 360 ℃ to effect imidization, thereby producing a metal-clad laminate C1. An adhesive tape was attached to the resin surface of the prepared metal-clad laminate C1, and a peeling test was performed by instantaneous peeling in the vertical direction, but peeling between the first polyimide layer and the second polyimide layer was not observed.

[ example C2]

A metal-clad laminate C2 was produced in the same manner as in example C1, except that a polyamic acid solution C — N was used instead of the polyamic acid solution C-a. The peel test of the prepared metal-clad laminate C2 was performed in the same manner as in example C1, but no interlayer peeling was observed between the first polyimide layer and the second polyimide layer.

[ example C3]

A metal-clad laminate C3 was produced in the same manner as in example C1, except that the polyamic acid solution C to C was used instead of the polyamic acid solution C to B. The peel test of the prepared metal-clad laminate C3 was performed in the same manner as in example C1, but no interlayer peeling was observed between the first polyimide layer and the second polyimide layer.

[ example C4]

Metal-clad laminate C4 was produced in the same manner as in example C1, except that polyamic acid solution C to C was used instead of polyamic acid solution C to B and polyamic acid solution C to N was used instead of polyamic acid solution C to a. The peel test of the prepared metal-clad laminate C4 was performed in the same manner as in example C1, but no interlayer peeling was observed between the first polyimide layer and the second polyimide layer.

[ example C5]

A metal-clad laminate C5 was produced in the same manner as in example C1, except that the polyamic acid solutions C to D were used instead of the polyamic acid solutions C to B. The peel test of the prepared metal-clad laminate C5 was performed in the same manner as in example C1, but no interlayer peeling was observed between the first polyimide layer and the second polyimide layer.

[ example C6]

Metal-clad laminate C6 was produced in the same manner as in example C1, except that polyamic acid solutions C to D were used instead of polyamic acid solutions C to B and polyamic acid solutions C to N were used instead of polyamic acid solutions C to a. The peel test of the prepared metal-clad laminate C6 was performed in the same manner as in example C1, but no interlayer peeling was observed between the first polyimide layer and the second polyimide layer.

[ example C7]

A metal-clad laminate C7 was produced in the same manner as in example C1, except that the polyamic acid solutions C to E were used instead of the polyamic acid solutions C to B. The peel test of the prepared metal-clad laminate C7 was performed in the same manner as in example C1, but no interlayer peeling was observed between the first polyimide layer and the second polyimide layer.

[ example C8]

Metal-clad laminate C8 was produced in the same manner as in example C1, except that polyamic acid solutions C to E were used instead of polyamic acid solutions C to B and polyamic acid solutions C to N were used instead of polyamic acid solutions C to a. The peel test of the prepared metal-clad laminate C8 was performed in the same manner as in example C1, but no interlayer peeling was observed between the first polyimide layer and the second polyimide layer.

[ example C9]

A metal-clad laminate C9 was produced in the same manner as in example C1, except that the polyamic acid solutions C to F were used instead of the polyamic acid solutions C to B. The peel test of the prepared metal-clad laminate C9 was performed in the same manner as in example C1, but no interlayer peeling was observed between the first polyimide layer and the second polyimide layer.

[ example C10]

Metal-clad laminate C10 was produced in the same manner as in example C1, except that polyamic acid solutions C to F were used instead of polyamic acid solutions C to B and polyamic acid solutions C to N were used instead of polyamic acid solutions C to a. The peel test of the prepared metal-clad laminate C10 was performed in the same manner as in example C1, but no interlayer peeling was observed between the first polyimide layer and the second polyimide layer.

[ example C11]

A metal-clad laminate C11 was produced in the same manner as in example C1, except that polyamic acid solutions C to G were used instead of polyamic acid solutions C to B. The peel test of the prepared metal-clad laminate C11 was performed in the same manner as in example C1, but no interlayer peeling was observed between the first polyimide layer and the second polyimide layer.

[ example C12]

Metal-clad laminate C12 was produced in the same manner as in example C1, except that polyamic acid solutions C to G were used instead of polyamic acid solutions C to B and polyamic acid solutions C to N were used instead of polyamic acid solutions C to a. The peel test of the prepared metal-clad laminate C12 was performed in the same manner as in example C1, but no interlayer peeling was observed between the first polyimide layer and the second polyimide layer.

[ example C13]

A metal-clad laminate C13 was produced in the same manner as in example C1, except that the polyamic acid solutions C to H were used instead of the polyamic acid solutions C to B. The peel test of the prepared metal-clad laminate C13 was performed in the same manner as in example C1, but no interlayer peeling was observed between the first polyimide layer and the second polyimide layer.

[ example C14]

Metal-clad laminate C14 was produced in the same manner as in example C1, except that polyamic acid solutions C to H were used instead of polyamic acid solutions C to B and polyamic acid solutions C to N were used instead of polyamic acid solutions C to a. The peel test of the prepared metal-clad laminate C14 was performed in the same manner as in example C1, but no interlayer peeling was observed between the first polyimide layer and the second polyimide layer.

[ example C15]

A metal-clad laminate C15 was produced in the same manner as in example C1, except that the polyamic acid solution C — I was used instead of the polyamic acid solution C-B. The peel test of the prepared metal-clad laminate C15 was performed in the same manner as in example C1, but no interlayer peeling was observed between the first polyimide layer and the second polyimide layer.

[ example C16]

Metal-clad laminate C16 was produced in the same manner as in example C1, except that polyamic acid solution C to I was used instead of polyamic acid solution C to B and polyamic acid solution C to N was used instead of polyamic acid solution C to a. The peel test of the prepared metal-clad laminate C16 was performed in the same manner as in example C1, but no interlayer peeling was observed between the first polyimide layer and the second polyimide layer.

[ example C17]

A metal-clad laminate C17 was produced in the same manner as in example C1, except that the polyamic acid solutions C to J were used instead of the polyamic acid solutions C to B. The peel test of the prepared metal-clad laminate C17 was performed in the same manner as in example C1, but no interlayer peeling was observed between the first polyimide layer and the second polyimide layer.

[ example C18]

Metal-clad laminate C18 was produced in the same manner as in example C1, except that polyamic acid solutions C to J were used instead of polyamic acid solutions C to B and polyamic acid solutions C to N were used instead of polyamic acid solutions C to a. The peel test of the prepared metal-clad laminate C18 was performed in the same manner as in example C1, but no interlayer peeling was observed between the first polyimide layer and the second polyimide layer.

[ example C19]

A metal-clad laminate C19 was produced in the same manner as in example C1, except that a polyamic acid solution C to K was used instead of the polyamic acid solution C to B. The peel test of the prepared metal-clad laminate C19 was performed in the same manner as in example C1, but no interlayer peeling was observed between the first polyimide layer and the second polyimide layer.

[ example C20]

Metal-clad laminate C20 was produced in the same manner as in example C1, except that polyamic acid solution C to K was used instead of polyamic acid solution C to B and polyamic acid solution C to N was used instead of polyamic acid solution C to a. The peel test of the prepared metal-clad laminate C20 was performed in the same manner as in example C1, but no interlayer peeling was observed between the first polyimide layer and the second polyimide layer.

[ example C21]

A metal-clad laminate C21 was produced in the same manner as in example C1, except that the polyamic acid solutions C to L were used instead of the polyamic acid solutions C to B. The peel test of the prepared metal-clad laminate C21 was performed in the same manner as in example C1, but no interlayer peeling was observed between the first polyimide layer and the second polyimide layer.

[ example C22]

Metal-clad laminate C22 was produced in the same manner as in example C1, except that polyamic acid solution C to L was used instead of polyamic acid solution C to B and polyamic acid solution C to N was used instead of polyamic acid solution C to a. The peel test of the prepared metal-clad laminate C22 was performed in the same manner as in example C1, but no interlayer peeling was observed between the first polyimide layer and the second polyimide layer.

[ example C23]

A metal-clad laminate C23 was produced in the same manner as in example C1, except that the polyamic acid solutions C to O were used instead of the polyamic acid solutions C to B. The peel test of the prepared metal-clad laminate C23 was performed in the same manner as in example C1, but no interlayer peeling was observed between the first polyimide layer and the second polyimide layer.

[ example C24]

Metal-clad laminate C24 was produced in the same manner as in example C1, except that polyamic acid solution C to O was used instead of polyamic acid solution C to B and polyamic acid solution C to N was used instead of polyamic acid solution C to a. The peel test of the prepared metal-clad laminate C24 was performed in the same manner as in example C1, but no interlayer peeling was observed between the first polyimide layer and the second polyimide layer.

[ example C25]

A metal-clad laminate C25 was produced in the same manner as in example C1, except that a polyamic acid solution C to T was used instead of the polyamic acid solution C to B. The peel test of the prepared metal-clad laminate C25 was performed in the same manner as in example C1, but no interlayer peeling was observed between the first polyimide layer and the second polyimide layer.

[ example C26]

Metal-clad laminate C26 was produced in the same manner as in example C1, except that polyamic acid solution C to T was used instead of polyamic acid solution C to B and polyamic acid solution C to N was used instead of polyamic acid solution C to a. The peel test of the prepared metal-clad laminate C26 was performed in the same manner as in example C1, but no interlayer peeling was observed between the first polyimide layer and the second polyimide layer.

Comparative example C1

A metal-clad laminate C27 was produced in the same manner as in example C1, except that the polyamic acid solutions C to M were used instead of the polyamic acid solutions C to B. As a result of a peel test of the prepared metal-clad laminate C27, interlayer peeling of the first polyimide layer and the second polyimide layer was generated in the same manner as in example C1.

Comparative example C2

Metal-clad laminate C28 was produced in the same manner as in example C1, except that polyamic acid solution C to M was used instead of polyamic acid solution C to B and polyamic acid solution C to N was used instead of polyamic acid solution C to a. As a result of a peel test of the prepared metal-clad laminate C28, interlayer peeling of the first polyimide layer and the second polyimide layer was generated in the same manner as in example C1.

Comparative example C3

A metal-clad laminate C29 was produced in the same manner as in example C1, except that a polyamic acid solution C — N was used instead of the polyamic acid solution C-B. As a result of a peel test of the prepared metal-clad laminate C29, interlayer peeling of the first polyimide layer and the second polyimide layer was generated in the same manner as in example C1.

Comparative example C4

A metal-clad laminate C30 was produced in the same manner as in example C1, except that a polyamic acid solution C — P was used instead of the polyamic acid solution C-a. As a result of a peel test of the prepared metal-clad laminate C30, interlayer peeling of the first polyimide layer and the second polyimide layer was generated in the same manner as in example C1.

Comparative example C5

Metal-clad laminate C31 was produced in the same manner as in example C1, except that polyamic acid solution C-a was used instead of polyamic acid solution C-B and polyamic acid solution C-B was used instead of polyamic acid solution C-a. As a result of a peel test of the prepared metal-clad laminate C31, interlayer peeling of the first polyimide layer and the second polyimide layer was generated in the same manner as in example C1.

[ example C27]

Metal-clad laminate C32 was produced in the same manner as in example C1, except that the temperature increase time after coating of polyamic acid solution C-a from 130 ℃ to 360 ℃ was shortened to 1/3, but foaming was not observed.

[ example C28]

Metal-clad laminate C33 was produced in the same manner as in example C1, except that polyamic acid solution C-a was used instead of polyamic acid solution C-B, and the temperature increase time after application of polyamic acid solution C-a from 130 ℃ to 360 ℃ was shortened to 1/3.

Comparative example C6

Metal-clad laminate C34 was produced in the same manner as in example C1 except that polyamic acid solution C-M was used instead of polyamic acid solution C-B and the temperature rise time after application of polyamic acid solution C-a from 130 ℃ to 360 ℃ was shortened to 1/3, resulting in foaming.

Comparative example C7

Metal-clad laminate C35 was produced in the same manner as in example C1 except that polyamic acid solution C-N was used instead of polyamic acid solution C-B and the temperature rise time after application of polyamic acid solution C-a from 130 ℃ to 360 ℃ was shortened to 1/3, resulting in foaming.

[ example C29]

The polyamic acid solution C to O, which becomes the first polyimide layer, was coated on a stainless steel substrate, and then dried at 120 ℃. The prepared gel film was peeled off from the stainless steel substrate, fixed to a tenter clip, and imidized by stepwise raising the temperature from 130 ℃ to 360 ℃ to prepare a polyimide film C36 having a thickness of 12.5. mu.m. On the prepared polyimide film C36, a polyamic acid solution C to R to be a second polyimide layer was applied in a thickness of 3 μm after hardening, and dried at 120 ℃. Thereafter, the temperature was increased stepwise from 130 ℃ to 360 ℃ to effect imidization, thereby producing a laminated polyimide film C36. The prepared laminated polyimide film C36 was cut with a dicing blade (cutter), and no interlayer peeling between the first polyimide layer and the second polyimide layer was observed with a Scanning Electron Microscope (SEM).

[ example C30]

A laminated polyimide film C37 was produced in the same manner as in example C29, except that a polyamic acid solution C to T was used instead of the polyamic acid solution C to O. Interlayer peeling of the prepared laminated polyimide film C37 was not confirmed by SEM observation.

[ example C31]

A laminated polyimide film C38 was prepared in the same manner as in example C29, except that the thickness of the first polyimide layer was set to 17 μm, and that a polyamic acid solution C to V was used in place of the polyamic acid solution C to R, and the thickness after curing was set to 4 μm. Interlayer peeling of the prepared laminated polyimide film C38 was not confirmed by SEM observation.

[ example C32]

A laminated polyimide film C39 was prepared in the same manner as in example C29, except that a polyamic acid solution C to T was used instead of the polyamic acid solution C to O and that a polyamic acid solution C to V was used instead of the polyamic acid solution C to R and that the thickness of the first polyimide layer after curing was set to 17 μm and that the thickness after curing was 4 μm. Interlayer peeling of the prepared laminated polyimide film C39 was not confirmed by SEM observation.

Comparative example C8

A laminated polyimide film C40 was produced in the same manner as in example C29, except that the polyamic acid solutions C to Q were used instead of the polyamic acid solutions C to R. Interlayer peeling was observed by SEM observation of the prepared laminated polyimide film C40.

Comparative example C9

A laminated polyimide film C41 was produced in the same manner as in example C29, except that a polyamic acid solution C — P was used instead of the polyamic acid solution C — O. Interlayer peeling was observed by SEM observation of the prepared laminated polyimide film C41.

Comparative example C10

A laminated polyimide film C42 was prepared in the same manner as in example C29, except that the thickness of the first polyimide layer was set to 17 μm, and that a polyamic acid solution C to U was used instead of the polyamic acid solution C to R, and the thickness after curing was set to 4 μm. Interlayer peeling was observed by SEM observation of the prepared laminated polyimide film C42.

[ example C33]

A polyamic acid solution C-T to be a first polyimide layer was uniformly applied to an electrolytic copper foil having a thickness of 12 μm so as to have a cured thickness of 25 μm, and then the temperature was raised from 120 ℃ to 360 ℃ in stages to remove the solvent and imidize the same. Next, the polyamic acid solution C to S to be the second polyimide layer was uniformly applied thereon so that the cured thickness was 25 μm, and then heated and dried at 120 ℃ to remove the solvent. Thereafter, the temperature was increased stepwise from 130 ℃ to 360 ℃ to effect imidization, thereby producing a metal-clad laminate C43. The peel strength of the first polyimide layer and the second polyimide layer in the prepared metal-clad laminate C43 was 1.5kN/m or more.

[ example C34]

The polyamic acid solutions C to S were uniformly applied to an electrolytic copper foil having a thickness of 12 μm so that the cured thickness was 23 μm, and the resultant was dried by heating at 120 ℃ to remove the solvent. On this, polyamic acid solutions C to B were uniformly applied to a cured thickness of 2 μm, and dried by heating at 120 ℃ to remove the solvent. Thereafter, the temperature was raised from 130 ℃ to 360 ℃ in stages to effect imidization, thereby forming a first polyimide layer. Next, the polyamic acid solution C to S to be the second polyimide layer was uniformly applied thereon so that the cured thickness was 25 μm, and then heated and dried at 120 ℃ to remove the solvent. Thereafter, the temperature was increased stepwise from 130 ℃ to 360 ℃ to effect imidization, thereby producing a metal-clad laminate C44. The peel strength of the first polyimide layer and the second polyimide layer in the prepared metal-clad laminate C44 was 1.5kN/m or more.

Comparative example C11

A metal-clad laminate C45 was produced in the same manner as in example C33, except that polyamic acid solutions C to S were used instead of polyamic acid solutions C to T. The peel strength between the first polyimide layer and the second polyimide layer in the prepared metal-clad laminate C45 was 0.1kN/m or less.

Comparative example C12

A metal-clad laminate C46 was produced in the same manner as in example C34, except that the polyamic acid solutions C to M were used instead of the polyamic acid solutions C to B. The peel strength between the first polyimide layer and the second polyimide layer in the prepared metal-clad laminate C46 was 0.1kN/m or less.

Reference example C

0.45g of phthalic anhydride (3.02mmol) was added to 100g of polyamic acid solution C-A, and the mixture was stirred for 4 hours to prepare polyamic acid solution C-A2. Metal-clad laminate C47 was produced in the same manner as in example C1 except that polyamic acid solution C-a2 was used instead of polyamic acid solution C-a, and as a result, foaming occurred. In addition, as a result of a peeling test of the prepared metal-clad laminate C47, interlayer peeling of the first polyimide layer and the second polyimide layer was generated in the same manner as in example C1.

The reason is considered to be that: the amino group of the second polyimide layer reacts with phthalic anhydride, whereby the functional group that can react with the first polyimide layer disappears, and chemical adhesion between resin layers does not occur.

The embodiments of the present invention have been described in detail for illustrative purposes, but the present invention is not limited to the embodiments.

The international application claims priority based on japanese patent application No. 2018-185874 (application date: 2018, 9, 28), japanese patent application No. 2018-185875 (application date: 2018, 9, 28) and japanese patent application No. 2018-185876 (application date: 2018, 9, 28), the entire contents of which are incorporated herein by reference.

Description of the symbols

10: metal layer

10A: metal foil

20: a first polyimide layer

20A: a first polyamide resin layer

30: second polyimide layer

30A: second polyamide resin layer

40: insulating resin layer

100: metal-clad laminated board

Claims

1. A method of manufacturing a metal clad laminate, which is a method of manufacturing a metal clad laminate, comprising: an insulating resin layer including a plurality of polyimide layers, and a metal layer laminated on at least one surface of the insulating resin layer, wherein the method for manufacturing a metal-clad laminated sheet is characterized in that:

comprises the following steps 1-5:

step 5) a step of imidizing the polyamic acid in the second polyimide resin layer to form a second polyimide layer including a single layer or a plurality of layers, and forming the insulating resin layer in which the first polyimide layer and the second polyimide layer are laminated, and

the thickness (L1) of the first polyimide layer is in the range of 0.5 [ mu ] m or more and 100 [ mu ] m or less, the thickness (L) of the entire insulating resin layer is in the range of 5 [ mu ] m or more and less than 200 [ mu ] m, and the ratio (L/L1) of L to the L1 is in the range of more than 1 and less than 400.

2. The metal-clad laminate production method according to claim 1, wherein the polyimide constituting the layer in contact with the metal layer in the first polyimide layer is a thermoplastic polyimide.

3. The method for producing a metal-clad laminate according to claim 1 or 2, wherein the moisture permeability of the metal layer is 100g/m at 25 ℃ and a thickness of 25 μm²And/24 hr or less.

4. A method of manufacturing a circuit substrate, comprising: a step of subjecting the metal layer of the metal-clad laminate manufactured by the method according to any one of claims 1 to 3 to wiring circuit processing.