JP2018126886A - Method for producing multilayered polyimide film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a multilayered polyimide film which can be suitably used for a high frequency circuit board capable of reducing transmission loss.SOLUTION: There is provided a method for producing a multilayered polyimide film 4 in which two or more non-thermoplastic polyimide layers 2 having a dielectric tangent of 0.001 to 0.009 at 10 GHz are laminated on at least one surface of a non-thermoplastic polyimide film 1 and a thermoplastic polyimide layer 3 is further laminated, followed by subjecting the resulting prefilm to heat treatment, wherein the generation of curling is suppressed by controlling the coating thickness on the front and back surfaces in the roll film preparation step and the width in the TD direction perpendicular to the film flow direction.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for producing a multilayer polyimide film that can be suitably used for a high-frequency circuit board.

  Polyimide is excellent in mechanical strength, heat resistance, electrical insulation, and chemical resistance, and is therefore widely used for electronic substrate materials. For example, a flexible copper-clad laminate (hereinafter also referred to as FCCL) in which polyimide film is used as a substrate material and copper foil is laminated on at least one surface, and a flexible printed circuit board (hereinafter also referred to as FPC) in which a circuit is further produced are manufactured. Used in various electronic devices. In recent years, there has been an increasing demand for low dielectric constant and low dielectric loss tangent of polyimide, which is a substrate material, in order to increase the frequency of electrical signals transmitted through circuits associated with high-speed signal transmission of electronic devices. For example, a material having a low dielectric constant and dielectric loss tangent in a high frequency (1 GHz or higher) region is required. Furthermore, the propagation speed of signals in electronic circuits decreases as the dielectric constant of the substrate material increases. If the dielectric constant and dielectric loss tangent increase, the signal transmission loss also increases. Therefore, low dielectric constant and low dielectric loss tangent of polyimide, which is a substrate material, and low transmission loss in an FPC state are essential for improving the performance of electronic devices.

  Development of polyimide resin with low dielectric constant and low dielectric loss tangent is the mainstream for the study of FCCL applicable to high frequency and the film used for it. Patent Document 1 uses polyimide heat resistant resin for insulating resin layer. A printed circuit board is disclosed. On the other hand, Patent Document 2 discloses a technique for preventing the occurrence of curling of a laminated film by controlling the width of each laminated film.

JP-A-2005-026542 JP2013-202824

  A film material capable of supporting high frequency is composed of a core layer and an adhesive layer, and both layers have been studied with the aim of achieving both high frequency characteristics, peel-off characteristics, and dimensional stability. However, along with the increasing demand characteristics of the market, it is difficult to achieve both properties in the examination of the core layer and the adhesive layer, and material design is becoming difficult.

  The present inventors have designed and studied a multilayer film provided with a non-thermoplastic polyimide film having a low dielectric loss tangent, but in the production of a roll film, curling suppression during the application of the non-thermoplastic polyimide film is performed. It was difficult and the yield was low.

  Although patent document 1 is an approach which uses a multilayer polyimide film, there is no description regarding preparation of a roll film, and it does not touch curl suppression.

  Although Patent Document 2 is an approach related to a curl suppressing technique for a laminated film, it does not use a polyimide resin and is not an approach intended for a film capable of handling high frequencies.

  Therefore, it is necessary to develop a production method for suppressing curling at the time of producing a roll film in a multilayer film capable of handling a high frequency having a low dielectric constant and a dielectric loss tangent.

  The objective of this invention is providing the manufacturing method of the multilayer polyimide film of the low transmission loss which can be used conveniently for a high frequency circuit board.

  As a result of intensive studies to solve the above problems, the present inventors laminated a non-thermoplastic polyimide layer having a dielectric loss tangent at 10 GHz of 0.001 to 0.009 on at least one surface of the non-thermoplastic polyimide film. In addition, in the production of multilayer polyimide films in which a thermoplastic polyimide layer is laminated, it has been found that curling can be suppressed by controlling the coating thickness on the front and back surfaces of the roll film production process and the width in the TD direction perpendicular to the film flow direction. The present invention has been completed.

That is, the present invention
<1>
A multilayer polyimide film characterized by laminating a non-thermoplastic polyimide layer having a dielectric loss tangent at 10 GHz of 0.001 to 0.009 on at least one surface of the non-thermoplastic polyimide film, and further laminating a thermoplastic polyimide layer. A manufacturing method comprising:
(1) forming at least two or more non-thermoplastic polyimide layers having a dielectric loss tangent at 10 GHz of 0.001 to 0.009 on at least one surface of the non-thermoplastic polyimide film;
(2) A step of further laminating a thermoplastic polyimide layer through the non-thermoplastic polyimide layer obtained in step (1) and performing a heat treatment to obtain a prefilm,
(3) A step of further heat-treating the prefilm obtained in step (2) to obtain a multilayer polyimide film,
It is related with the manufacturing method of the multilayer polyimide film characterized by including.

<2>
The width of the non-thermoplastic polyimide layer having a dielectric loss tangent at 10 GHz in the step (1) of 0.001 to 0.009 and the non-heat in which the dielectric loss tangent at 10 GHz of the step (2) is 0.001 to 0.009. The present invention relates to the method for producing a multilayer polyimide film according to <1>, wherein the widths of the plastic polyimide layers are different.

<3>
The non-thermoplastic polyimide layer having a dielectric loss tangent of 0.001 to 0.009 at 10 GHz is at least 2,2′-dimethylbiphenyl-4,4′-diamine as an aromatic dianhydride, 1,3- Any one of bis (4-aminophenoxy) benzene, as an aromatic diamine, at least 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 3,3 ′, 4,4′-benzophenonetetracarboxylic The present invention relates to a method for producing a multilayer polyimide film according to <1> or <2>, comprising a polyimide having any one of acid dianhydride and pyromellitic dianhydride.

  According to the method for producing a multilayer polyimide film in the present invention, there is an effect that the yield of a roll film having a low transmission loss can be increased. Therefore, it is possible to cope with the higher frequency of electronic products, and is useful, for example, when developing a substrate for a high frequency circuit of 1 GHz or higher.

It is sectional drawing which shows an example of the multilayer polyimide film which concerns on this invention. It is sectional drawing which shows an example of the conventional multilayer polyimide film. It is sectional drawing which shows the structure of the non-thermoplastic polyimide film which has the low dielectric loss tangent property with the non-thermoplastic polyimide film obtained in Example 1. It is sectional drawing which shows the structure of the non-thermoplastic polyimide layer which has the low dielectric loss tangent property with the non-thermoplastic polyimide film obtained in Example 2. It is sectional drawing which shows the structure of the non-thermoplastic polyimide film which has the low-dielectric-tangent property and the non-thermoplastic polyimide film obtained in Example 3. It is sectional drawing which shows the structure of the non-thermoplastic polyimide film which was obtained in the comparative example 1, and has a low dielectric loss tangent property. It is sectional drawing which shows the structure of the non-thermoplastic polyimide layer which has the low-dielectric-tangent property and the non-thermoplastic polyimide film obtained in the comparative example 2. It is sectional drawing which shows the structure of the non-thermoplastic polyimide layer which has the non-thermoplastic polyimide film and low dielectric loss tangent obtained by the comparative example 3.

  Embodiments of the present invention will be described below. However, this invention is not limited to this, It can implement in the aspect which added the various deformation | transformation within the described range.

  Unless otherwise specified in the present specification, “A to B” representing a numerical range means “A or more (including A and greater than A)” and “B or less (including B and less than B)”.

(Non-thermoplastic polyimide layer with low dielectric loss tangent)
The insulating resin film used for conventional FCCL is generally a multilayer polyimide film composed of a substrate material (hereinafter also referred to as a core layer) and an adhesive layer to be bonded to the core layer and the metal foil. In order to satisfy general characteristics such as dimensional stability and peel strength that have been required in the past, the core layer mainly ensures the heat resistance and physical properties necessary for dimensional stabilization, and the adhesive layer mainly consists of metal foil. It plays the role of ensuring the physical properties necessary for the peel strength of the steel. Furthermore, it is necessary that the multilayer film including the core layer and the adhesive layer and the metal foil can be easily manufactured when they are laminated by a thermal laminating method or the like.

  The multilayer polyimide film of the present invention is a non-thermoplastic polyimide layer having a dielectric loss tangent at 10 GHz of 0.001 to 0.009 (hereinafter, non-thermoplastic polyimide having low dielectric loss tangent) on at least one surface of the non-thermoplastic polyimide film. A layer or an intermediate layer) and a thermoplastic polyimide layer.

  The low dielectric loss tangent in the present invention means that the dielectric loss tangent at 10 GHz is 0.001 to 0.009. That is, the non-thermoplastic polyimide layer having low dielectric loss tangent in the present invention means a non-thermoplastic polyimide layer having a dielectric loss tangent at 10 GHz of 0.001 to 0.009.

  In order to impart low transmission loss characteristics, it is necessary to reduce the dielectric constant, dielectric tangent, and moisture absorption of the insulating resin film, and it is necessary to share these characteristics between the core layer and the adhesive layer.

  However, the physical properties required for the above general properties and the properties required for low transmission loss are in a trade-off relationship, with the core layer and adhesive layer having high heat resistance, dimensional stabilization, It has been difficult to achieve both peel strength and low transmission loss characteristics. As a result of various studies, the present inventors have found that an additivity is substantially established in the dielectric constant and dielectric loss tangent of an insulating resin film using a polyimide film, and have a low dielectric loss tangent that is excellent in improving low transmission loss characteristics. A multilayer polyimide film with a thermoplastic polyimide layer achieves both general characteristics and low transmission loss characteristics.

  Specifically, the core layer and adhesive layer ensure the physical properties necessary for conventional heat resistance, dimensional stabilization, and peel strength from the metal foil, and the intermediate layer is required for low transmission loss. This is a method of ensuring the physical properties of low dielectric constant, low dielectric loss tangent, and low moisture absorption.

  As described above, the intermediate layer of the present invention is a material excellent in low dielectric constant, low dielectric loss tangent, and low moisture absorption that affects transmission loss. Unlike the non-thermoplastic polyimide used for the core layer, the intermediate layer is characterized by low moisture absorption. It is necessary to select a combination of materials.

  The intermediate layer in the present invention needs to have a low dielectric loss tangent. The intermediate layer in the present invention refers to a non-thermoplastic polyimide layer having a dielectric loss tangent at 10 GHz of 0.001 to 0.009. The dielectric loss tangent is more preferably 0.001 to 0.007. When the dielectric loss tangent is within this range, the transmission loss of the FPC is reduced, which is preferable.

  The intermediate layer in the present invention preferably has a low relative dielectric constant. It is more preferably 2.7 to 3.5, and particularly preferably 2.7 to 3.3. When the relative permittivity is within this range, the transmission loss of the FPC is reduced, which is preferable.

  Since the moisture absorption rate also affects transmission loss, the moisture absorption rate of the intermediate layer of the present invention is preferably low. It is more preferably 0.1% to 1.0%, and particularly preferably 0.1% to 0.8%. When the moisture absorption rate is in this range, the transmission loss of the FPC is reduced, which is preferable.

  The intermediate layer of the present invention is not particularly limited as long as the dielectric loss tangent is in the range of 0.001 to 0.009, and various polyamic acids can be used.

  The polyamic acid is obtained by reacting an aromatic diamine and an aromatic dianhydride. More specifically, usually, the aromatic diamine and the aromatic dianhydride are dissolved in an organic solvent so as to have a substantially equimolar amount, and the resulting solution is subjected to controlled temperature conditions. Below, it manufactures by stirring until superposition | polymerization with the said aromatic dianhydride and aromatic diamine is completed. The solution containing the polyamic acid thus obtained is usually obtained at a concentration of 5 wt% to 35 wt%, more preferably 10 wt% to 30 wt%. When the concentration is in this range, an appropriate molecular weight and solution viscosity are obtained. The polymerization method is not particularly limited, and the order of addition, the combination of monomers, and the composition (addition amount) are not particularly limited. For example, it may be random polymerization or may be sequence polymerization that can produce a block component.

  The aromatic diamine is not particularly limited, and examples thereof include 3,3′-diaminodiphenyl ether, 3,4′-diaminodiphenyl ether, 4,4′-diaminodiphenyl ether, and 2,2′-dimethylbiphenyl-4. , 4′-diamine, 2,2-bis {4- (4-aminophenoxy) phenyl} propane, 2,2-bis {4- (4-aminophenoxy) phenyl} hexafluoropropane, bis {4- (3 -Aminophenoxy) phenyl} sulfone, bis {4- (4-aminophenoxy) phenyl} sulfone, 1,3-bis (3-aminophenoxy) benzene, 1,3-bis (4-aminophenoxy) benzene, 1, 4-bis (4-aminophenoxy) benzene, 3,3′-diaminobenzophenone, 4,4′-diaminoben Phenone, 3,3′-dichlorobenzidine, 3,3′-dimethylbenzidine, 2,2′-dimethylbenzidine, 3,3′-dimethoxybenzidine, 2,2′-dimethoxybenzidine, 1,4-diaminobenzene (p -Phenylenediamine), 1,3-diaminobenzene (m-phenylenediamine), 4,4′-diaminodiphenylsulfone, 3,3′-diaminodiphenylsulfone, 9,9-bis (4-aminophenyl) fluorene, 4 4 ′-(1,4-phenylenebis (1-methylethylidene)) bisaniline, 4,4 ′-(1,3-phenylenebis (1-methylethylidene)) bisaniline, 4,4′-diaminobenzanilide, etc. Any one of these or a combination of two or more of these may be mentioned.

  The aromatic acid dianhydride is not particularly limited. For example, 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride, 2,2 ′, 3,3′-benzophenone Tetracarboxylic dianhydride, 4,4'-oxydiphthalic dianhydride, 3,4'-oxyphthalic dianhydride, ethylene bis (trimellitic acid monoester acid anhydride), bisphenol A bis (trimellitic acid mono Ester anhydride), pyromellitic dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride, 3,3 ′, 4,4′-diphenylsulfonetetracarboxylic dianhydride, 3,3 ′, 4,4′-dimethyldiphenylsilanetetracarboxylic dianhydride, 3,3 ′, 4,4′-tetraphenyl Lantetracarboxylic dianhydride, 1,2,3,4-furantetracarboxylic dianhydride, 4,4′-bis (3,4-dicarboxyphenoxy) diphenylpropane dianhydride, 4,4′- Hexafluoroisopropylidenediphthalic anhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 2,3,3 ′, 4′-biphenyltetracarboxylic dianhydride, p-phenylenebis (Trimellitic acid monoester anhydride), aromatic tetracarboxylic dianhydrides such as p-phenylenediphthalic anhydride, or a combination of two or more of these.

  Preferred examples of the aromatic diamine for exhibiting low dielectric loss tangent and low water absorption are 2,2′-dimethylbiphenyl-4,4′-diamine, 2,2-bis {4- (4-amino). Phenoxy) phenyl} propane, 1,3-bis (4-aminophenoxy) benzene, 1,4-bis (4-aminophenoxy) benzene, paraphenylenediamine, 4,4′-diamino-2,2′-bis ( Fluoromeric monomers such as (trifluoromethyl) biphenyl may be used alone or in combination. Preferred examples of aromatic dianhydrides for developing low dielectric loss tangent and low water absorption are 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride, pyromellitic dianhydride 4,4′-oxydiphthalic dianhydride and 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride may be used alone or in combination.

  The organic solvent used as the polymerization solvent for producing the polyamic acid is not particularly limited as long as it dissolves the aromatic diamine, the aromatic dianhydride, and the obtained polyamic acid. If, for example, N, N-dimethylformamide, N, N-diethylformamide, N-methyl-2-pyrrolidone, N, N-dimethylacetamide or the like is used as a polymerization solvent, the resulting polyamic acid solution can be used as it is. And a polyimide film.

  The reaction temperature for producing the polyamic acid is preferably −10 ° C. to 50 ° C. Within such a range, the reaction proceeds at a good reaction rate and is excellent in productivity, which is preferable. The reaction time is not particularly limited, but is usually from several minutes to several hours.

  The polyimide is produced by a method in which the polyamic acid is typified by thermal cure or chemical cure. Thermal curing is to advance imidization only by heat treatment. Chemical curing is a method of imidizing by mixing with a curing agent and heat-treating. The curing agent includes a dehydrating agent and a catalyst. Here, the dehydrating agent is not particularly limited as long as it is a dehydrating ring-closing agent for polyamic acid. For example, aliphatic acid anhydride, aromatic acid anhydride, N, N′-dialkylcarbodiimide, lower aliphatic halide, halogenated lower aliphatic acid anhydride, arylsulfonic acid dihalide, thionyl halide, etc. Can do. These may be used alone or in appropriate combination of two or more. Among these, aliphatic acid anhydrides and aromatic acid anhydrides can be suitably used, and acetic anhydride is particularly preferable. The catalyst is not particularly limited as long as it is a component having an effect of promoting the dehydration ring-closing action of the dehydrating agent on the polyamic acid. For example, an aliphatic tertiary amine, an aromatic tertiary amine, a heterocyclic tertiary amine, and the like can be given. Among these, for example, nitrogen-containing heterocyclic compounds such as imidazole, benzimidazole, isoquinoline, quinoline, diethylpyridine, and β-picoline are particularly preferably used.

  Non-thermoplasticity in the present invention means solution polymerization by combining raw material monomers, drying the obtained polyamic acid solution, and molding obtained mainly by at least one method of thermal imidization or chemical imidization (mainly When the film is heated at 450 ° C. for 1 minute, the film retains its shape without causing deformation such as wrinkles and elongation.

(Non-thermoplastic polyimide film)
By making a non-thermoplastic polyimide film into a core layer, the multilayer polyimide film of this invention can be comprised.

  The non-thermoplastic polyimide film may contain other resins together with the non-thermoplastic polyimide as long as the properties as the non-thermoplastic polyimide film are not impaired.

  The non-thermoplastic polyimide film (core layer) of the present invention preferably has a low dielectric loss tangent. Specifically, 0.001 to 0.012 is more preferable, and 0.001 to 0.010 is particularly preferable. When the dielectric loss tangent is in the above range, the dielectric loss tangent of the multilayer polyimide film can be controlled to 0.009 or less in the intermediate layer.

  It is preferable that the non-thermoplastic polyimide film layer (core layer) of the present invention also has a low moisture absorption rate. Specifically, it is more preferably 0.1% to 1.7%, and particularly preferably 0.1% to 1.4%.

  In order to suppress the dimensional change rate before and after the etching of the flexible metal-clad laminate, the thermal expansion coefficient (CTE) of the core layer is preferably 1 ppm to 15 ppm, and more preferably 2 to 12 ppm. When CTE is the said range, the dimensional change rate of a multilayer polyimide film can be controlled by the intermediate | middle layer to an appropriate range.

(Non-thermoplastic polyimide)
The non-thermoplastic polyimide contained in the non-thermoplastic polyimide film (core layer) is produced by imidization using polyamic acid as a precursor.

  The monomer constituting the polyamic acid that becomes a non-thermoplastic polyimide by imidization is not particularly limited as long as it can exhibit non-thermoplasticity. For example, the thing similar to the monomer which comprises an intermediate | middle layer can be illustrated.

  Examples of aromatic diamines suitably used for the non-thermoplastic polyimide contained in the non-thermoplastic polyimide film (core layer) include 2,2′-dimethylbiphenyl-4,4′-diamine and 2,2-bis. {4- (4-aminophenoxy) phenyl} propane, 1,3-bis (4-aminophenoxy) benzene, 1,4-bis (4-aminophenoxy) benzene, paraphenylenediamine, 4,4′-diaminodiphenyl Propane, 4,4′-bis (4-aminophenoxy) biphenyl, 4,4′-diaminodiphenylmethane, 4,4′-diaminodiphenyl sulfide, 2,2′-dimethyl-4,4′-diaminobiphenyl, 2, 2-bis (4-aminophenoxyphenyl) propane, 3,3′-dihydroxy-4,4′-diamino-1,1′-biphe Nil, and the like, and these can be used alone or in combination. Examples of aromatic dianhydrides suitably used for designing non-thermoplastic polyimides contained in non-thermoplastic polyimide films (core layers) include pyromellitic dianhydride, 2, 3, 6, 7-naphthalenetetracarboxylic dianhydride, 2,2 ′, 3,3′-biphenyltetracarboxylic dianhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 2,2- And bis (3,4-dicarboxyphenyl) propanoic acid dianhydride, p-phenylenebis (trimellitic acid monoester acid anhydride), 4,4′-oxydiphthalic acid dianhydride, and the like. Or it can be used in combination.

  The polymerization method, polymerization solvent, reaction temperature and reaction time of the non-thermoplastic polyimide contained in the non-thermoplastic polyimide film (core layer) are not particularly limited.

  There are no particular limitations on the curing agent, curing conditions, and the like when polyamic acid is used as polyimide. For example, the thing similar to what is used when manufacturing an intermediate | middle layer can be used.

(Thermoplastic polyimide layer)
If the thermoplastic polyimide layer (also referred to as an adhesive layer) according to the present invention can exhibit desired properties such as adhesive strength with a metal foil such as a copper foil and a suitable linear expansion coefficient, the thermoplastic polyimide layer contained in the adhesive layer The content, molecular structure, and thickness are not particularly limited. However, it is preferable to contain 50% by weight or more of thermoplastic polyimide in order to exhibit desired properties such as a significant adhesive force and a suitable linear expansion coefficient.

  It is preferable that the dielectric loss tangent of the thermoplastic polyimide layer (adhesive layer) of the present invention is also low. Specifically, 0.001 to 0.012 is more preferable, and 0.001 to 0.010 is particularly preferable. When the dielectric loss tangent exceeds the above range, it is difficult to reduce the dielectric loss tangent of the multilayer polyimide film in the intermediate layer.

  A lower moisture absorption rate is preferred. Specifically, it is more preferably 0.1% to 1.3%, and particularly preferably 0.1% to 0.9%.

  Considering that the adhesive strength with the metal foil is exhibited and the heat resistance of the obtained metal-clad laminate is not impaired, the thermoplastic polyimide in the present invention has a glass transition temperature (Tg) in the range of 150 ° C to 300 ° C. ) Is preferable. In addition, Tg can be calculated | required from the value of the inflexion point of the storage elastic modulus measured with the dynamic viscoelasticity measuring apparatus (DMA).

  The thermoplastic polyimide contained in the thermoplastic polyimide layer according to the present invention is obtained by a conversion reaction from the precursor polyamic acid. As the method for producing the polyamic acid, any known method can be used as in the case of the precursor of the non-thermoplastic polyimide, that is, the precursor of the high heat resistant polyimide layer.

  For the purpose of controlling the properties of the thermoplastic polyimide layer according to the present invention, inorganic or organic fillers and other resins may be added as necessary.

(Thermoplastic polyimide)
As the thermoplastic polyimide contained in the thermoplastic polyimide layer, thermoplastic polyimide, thermoplastic polyamideimide, thermoplastic polyetherimide, thermoplastic polyesterimide and the like can be suitably used. Among these, thermoplastic polyimide is particularly preferably used from the viewpoint of dimensional stability and adhesion.

  The polyamic acid that is a precursor of the thermoplastic polyimide used in the present invention is not particularly limited, and any known polyamic acid can be used. Regarding the production of the polyamic acid solution, the raw materials such as aromatic dianhydride and aromatic diamine used for the production of the precursor of the non-thermoplastic polyimide, the solvent, and the production conditions can be used in exactly the same manner.

  The properties of thermoplastic polyimide can be adjusted by combining various raw materials to be used, but generally the glass transition temperature increases and the storage elasticity during heat increases as the proportion of rigid aromatic diamine increases. This is not preferable because the rate increases and the adhesiveness and workability decrease. The ratio of the aromatic diamine having a rigid structure is preferably 40 mol% or less, more preferably 30 mol% or less, and particularly preferably 20 mol% or less.

  Examples of aromatic diamines particularly preferably used in the present invention include 1,3-bis (4-aminophenoxy) benzene, 2,2′-dimethylbiphenyl-4,4′-diamine, 4,4′-bis (4 -Aminophenoxy) biphenyl, 2,2-bis [4- (4-aminophenoxy) phenyl] propane and the like can be mentioned, and these can be used alone or in combination.

  Examples of aromatic dianhydrides particularly preferably used in the present invention include 4,4′-oxydiphthalic dianhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, pyromellitic acid 2 An anhydride etc. are mentioned, These can be used individually or in combination.

  The polymerization method of the thermoplastic polyimide, the polymerization solvent, the reaction temperature and the reaction time are not particularly limited.

  The curing agent used when the polyamic acid is made of polyimide is not particularly limited, but for example, the same one as used when the intermediate layer is produced can be used.

(Multilayer polyimide film)
The multilayer polyimide film of the present invention is thermoplastic on at least one surface of a non-thermoplastic polyimide film (core layer) via a non-thermoplastic polyimide layer (intermediate layer) having a dielectric loss tangent at 10 GHz of 0.001 to 0.009. It has a structure in which a polyimide layer (adhesive layer) is provided.

  Since the multilayer polyimide film of the present invention is used for a high-frequency circuit substrate or the like, it is preferable that the moisture absorption rate is low. Specifically, it is more preferably 0.1% to 1.3%, and particularly preferably 0.1% to 1.0%. It is preferable that the dielectric constant of the multilayer polyimide film of the present invention is also low. Specifically, it is more preferably 2.8 to 3.6, and particularly preferably 2.8 to 3.5.

  The dielectric loss tangent of the multilayer polyimide film of the present invention is preferably low. Specifically, it is more preferably 0.001 to 0.011, and particularly preferably 0.001 to 0.009.

  The total thickness of the multilayer polyimide film of the present invention is not particularly limited. For example, 12 μm to 54 μm are preferable, and 16.5 μm to 48 μm are more preferable. If the total thickness is within this range, the flexible wiring board will have appropriate hardness and bendability, and it will have good handling properties, and will not break through the manufacturing process. Less likely to occur.

  The total thickness of the core layer and the intermediate layer of the present invention is not particularly limited. For example, 8 μm to 50 μm is preferable, and 12.5 μm to 44 μm is more preferable. The thicknesses of the core layer and the intermediate layer can be arbitrarily determined within the preferable range of the total thickness. For example, in the total thickness range, the thickness of the intermediate layer is more preferably 3 μm to 40 μm, and particularly preferably 6 μm to 35 μm. Further, the composition ratio of the thickness of the intermediate layer to the total thickness is more preferably 30% to 80%, and particularly preferably 40% to 70%. When the thickness of the intermediate layer is within this range, the dielectric loss tangent of the multilayer polyimide film can be controlled to 0.009 or less in the intermediate layer.

  The thickness (one side) of the adhesive layer is not particularly limited. For example, 1.7 μm to 16 μm are preferable, 1.7 μm to 6 μm are more preferable, and 1.7 μm to 4 μm are even more preferable. When the thickness (single side) of the adhesive layer is within this range, although it depends on the roughness of the surface of the metal foil, the adhesion with the metal foil is good and the dimensional change rate after etching tends to be good. Moreover, when the adhesive layer is thick and the thickness component ratio of the adhesive layer occupying the total thickness of the multilayer polyimide film is 50% or less, the dimensional change rate when processed into a flexible metal-clad laminate is good. The thickness composition ratio of the adhesive layer in the total thickness of the multilayer polyimide film is more preferably 8% to 32%, and particularly preferably 12% to 24%. When the thickness composition ratio of the adhesive layer in the total thickness of the multilayer polyimide film is within this range, the peel strength and dimensional stability are favorable, which is preferable.

(Manufacturing method of multilayer polyimide film)
In the method for producing a multilayer polyimide film of the present invention, examples of a method for providing a thermoplastic polyimide layer on at least one surface of a non-thermoplastic polyimide film through a non-thermoplastic polyimide layer having low dielectric loss tangent include the following methods. be able to. (I) A method of forming a thermoplastic polyimide layer as an adhesive layer by forming a non-thermoplastic polyimide layer having a low dielectric loss tangent property as an intermediate layer on a non-thermoplastic polyimide layer as a core layer, (ii) a core layer And a method of forming a thermoplastic polyimide layer as an adhesive layer by simultaneous molding of the intermediate layer and the intermediate layer by multilayer extrusion or the like, and (iii) a method of simultaneously molding the core layer, intermediate layer and adhesive layer by multilayer extrusion or the like.

  When the intermediate layer is produced by the means (i), for example, after applying the precursor solution of the intermediate layer to the core layer, first, most of the organic solvent in the precursor solution of the intermediate layer is removed. Heat at low temperature. The temperature at this stage is preferably in the range of 50 ° C to 200 ° C. Next, heating is performed at a relatively low temperature in order to apply the precursor solution of the adhesive layer and remove most of the organic solvent in the adhesive layer solution. The temperature is preferably in the range of 50 ° C to 200 ° C.

  Finally, the multilayer polyimide film is heated at a high temperature in order to remove the solvent slightly remaining in the interlayer polyimide film and the adhesive layer and imidize the polyamic acid in the interlayer and adhesive layer. . The heat treatment temperature at this stage is preferably 250 ° C. or higher. When heat treatment is performed at a temperature of 250 ° C. or higher, dimensional stability and peel strength are good. If almost no solvent remains in the adhesive layer, heat is applied at a temperature equal to or higher than the melting point of the thermoplastic polyimide at this stage to remove the solvent, imidize the thermoplastic polyimide in the adhesive layer, and melt the adhesive layer. You may carry out collectively in a process. The temperature above the melting point of thermoplastic polyimide may be as high as about 390 ° C, and sudden cooling after heating may cause rapid shrinkage of the multilayer polyimide film, which may deteriorate the appearance. It is preferable to cool slowly.

  When a multilayer polyimide film is produced by the means (ii) above, the core layer and the intermediate layer are simultaneously formed by multilayer extrusion or the like, and then heated to remove the solvent, the core layer, imidation of the intermediate layer, the core layer, the intermediate layer To melt. Next, an adhesive layer is formed and heated to remove the solvent, imidize and melt the adhesive layer. The steps may be performed in the same manner as (i).

  When the multilayer polyimide film is produced by the means (iii), the core layer, the intermediate layer, and the adhesive layer are simultaneously formed by multilayer extrusion or the like, and then heated to remove the solvent, imidize, and melt. The temperature step may be performed in the same manner as (i).

  The heating means is not particularly limited, and examples thereof include a hot air system and a far infrared system, and these may be used in combination. As for the heating method, either batch processing or continuous processing may be used, but from the viewpoint of productivity of the multilayer polyimide film, continuous processing is preferable.

  In the manufacturing method of the intermediate layer, the adhesive layer, and the core layer according to the present invention, either a thermal curing method or a chemical curing method may be employed. However, in consideration of manufacturing efficiency, a chemical curing method is employed for the core layer. It is particularly preferable to do this.

  The production method of the present invention preferably includes the following steps (1), (2), and (3) with respect to (i).

That is, a multilayer having a structure in which a thermoplastic polyimide layer is provided on at least one surface of a non-thermoplastic polyimide film via a non-thermoplastic polyimide layer having a dielectric loss tangent at 10 GHz of 0.001 to 0.009. A method for producing a polyimide film,
(1) forming at least two or more non-thermoplastic polyimide layers having a dielectric loss tangent at 10 GHz of 0.001 to 0.009 on at least one surface of the non-thermoplastic polyimide film;
(2) A step of further laminating a thermoplastic polyimide layer through the non-thermoplastic polyimide layer obtained in step (1) and performing a heat treatment to obtain a prefilm,
(3) A step of further heat-treating the prefilm obtained in step (2) to obtain a multilayer polyimide film,
The manufacturing method of the multilayer polyimide film characterized by including.

(Process (1))
Step (1): A step of forming at least two non-thermoplastic polyimide layers having a dielectric loss tangent at 10 GHz of 0.001 to 0.009 on at least one surface of the non-thermoplastic polyimide film will be described.

  The step of forming at least two non-thermoplastic polyimide layers having a dielectric loss tangent at 10 GHz of 0.001 to 0.009 on at least one surface of the non-thermoplastic polyimide film is not particularly limited, and a conventionally known method is used. Is done.

  For example, the methods (i), (ii) and (iii) are preferably exemplified.

  When the intermediate layer is produced by the means (i), for example, (i-1) in order to remove most of the organic solvent in the intermediate layer solution after coating the intermediate layer precursor solution on the core layer, There is a method of heating at a relatively low temperature. The temperature at this stage is preferably in the range of 50 ° C to 200 ° C. By repeating this operation at least on the front surface or the back surface, the intermediate layer can be formed.

  As another method, (i-2) after coating the intermediate layer precursor solution on the core layer, the organic solvent in the intermediate layer solution is removed, and the polyamic acid in the intermediate layer is imidized. There is a method of performing heat treatment at a high temperature, and it is also possible to select to form an intermediate layer by repeating this operation at least on the front surface or the back surface.

  When a multilayer polyimide film is produced by the means (ii) above, the core layer and the intermediate layer are simultaneously formed by multilayer extrusion or the like, and then heated to remove the solvent, the core layer, imidation of the intermediate layer, the core layer, the intermediate layer To melt. By setting the number of intermediate layers at the time of extrusion to 2 or more, the target film can be obtained.

  When performing by the manufacturing method of (i-1), in order to control the dielectric loss tangent of a multilayer polyimide film to 0.009 or less, the thickness of the intermediate | middle layer in this invention is 40%-70% of composition ratio with respect to total thickness It is preferable that When the intermediate layer having the target thickness is applied once on one side, the warp (curl) of the film end toward the coated surface in the heating step is large, and it is difficult to wind the roll film with a high yield. Curling occurs because the balance of film thickness is lost on both sides due to the application of the intermediate layer, resulting in the occurrence of shrinkage stress on the coated surface side of the intermediate layer. In order to suppress curling, it is necessary to divide and coat the intermediate layer twice or more on one side to suppress the curl amount per coating.

  The yield in the present invention refers to the ratio of the production amount of the film actually wound on a roll to the production amount expected from the input amount of the film.

  For example, when coating an intermediate layer with a composition ratio of 60% of the total thickness, a coating method that suppresses curling, 15% of the composition ratio is applied twice on one side (surface), etc. A method of coating 30% of the composition ratio on one side (back side) will be described as an example. First, 15% coating is applied to the surface, and after drying, a shrinkage stress corresponding to 15% of the intermediate layer acts on the surface side. Next, 30% coating is applied to the back surface, and after drying, the thickness on the back surface side is increased by 15% from the front surface, so that a contraction stress of approximately 15% acts on the back surface side. Finally, after 15% coating on the surface and drying, the volume of the intermediate layer on the front and back surfaces is the same, so the shrinkage stress is generally canceled.

The difference in the composition ratio between the front surface and the back surface with respect to the total thickness of the intermediate layer in the coating process is preferably 20% or less, more preferably 17% to 20% from the viewpoint of the winding yield when considering the curl amount. Considering the balance between the number of coatings and the yield, 12% to 17% is most preferable. If it exceeds 20%, the yield of winding will be poor, and if it is 12% or less, the number of times of coating will increase and the process will become complicated, leading to an increase in cost.
Ultimately, it is necessary to determine the conditions in consideration of the balance between the total yield multiplied by the yield of each coating process and the number of times of coating.

  Moreover, in this invention, it is preferable that the width | variety of the TD direction of at least 1 or more laminated | stacked intermediate | middle layers differs.

  The curling suppression method can be adjusted by the above-described method of controlling the coating thickness on the front and back surfaces and the width in the TD direction on the front and back surfaces.

  Curling (curvature of the film edge) occurs when the stress balance between the front and back surfaces of the coating is broken, so changing the width in the TD direction on the front and back surfaces can reduce the curl during coating and drying. Can be suppressed.

  If curling occurs excessively, the yield may be lowered, and it may be difficult to produce a flexible copper clad laminate (FCCL) using a multilayer polyimide film obtained by laminating thermoplastic polyimide on the intermediate layer.

  For example, when an intermediate layer having a composition ratio of 60% with respect to the total thickness is applied, 15% of the composition ratio is applied to one surface (front surface), and 30% of the composition ratio is applied to one surface (back surface), then the composition is formed on one surface (front surface). A method of coating 15% of the ratio will be described as an example.

  15% coating on the surface, and after drying, the shrinkage stress of 15% of the intermediate layer acts on the surface side. When 30% coating is applied to the back surface, if the back surface is applied with the same width as the front surface, a shrinkage stress of approximately 15% acts on the back surface side by the amount of volume on the back surface side. At this time, if the width in the TD direction of the back surface is set inside (compared to be shorter) than the front surface, shrinkage stress to the front surface side where the volume of the coating end is large is generated. Is less than 15%.

  Subsequently, when applying 15% to the surface, it is necessary to determine the width in the TD direction in consideration of the stress balance after coating and drying.

(Process (2))
Step (2): A step of further laminating a thermoplastic polyimide layer through the non-thermoplastic polyimide layer obtained in step (1) and performing a heat treatment to obtain a prefilm will be described.

  In the method for producing a multilayer polyimide film of the present invention, a thermoplastic polyimide layer is further laminated via an intermediate layer, and a means for obtaining a multilayer polyimide film is obtained by applying a thermoplastic polyimide layer precursor solution, Heating is performed at a relatively low temperature to remove most of the organic solvent in the layer precursor solution. The temperature at this time is preferably in the range of 50 ° C to 200 ° C.

  The more preferable composition ratio with respect to the total thickness of the thickness of the thermoplastic polyimide layer in the present invention is 12% to 24%. Therefore, since the difference in the composition ratio of the front surface and the back surface with respect to the total thickness is 6% to 12%, it is not essential to divide the composition thickness performed in the intermediate layer twice or more, but curling suppression Can be used for

(Process (3))
Step (3): The step of further heat-treating the prefilm obtained in step (2) to obtain a multilayer polyimide film will be described.

  In order to remove the solvent slightly remaining in the interlayer polyimide film and the thermoplastic polyimide layer and imidize the polyamic acid remaining in the interlayer polyimide film, the multilayer polyimide film is heated to a high temperature. Heat treatment is performed at The heat treatment temperature at this stage is preferably 250 ° C. or higher. When heat treatment is performed at a temperature of 250 ° C. or higher, dimensional stability and peel strength are good. If almost no solvent remains in the thermoplastic polyimide layer, heat is applied at a temperature equal to or higher than the melting point of the thermoplastic polyimide at this stage to remove the solvent, imidize the thermoplastic polyimide, and melt the thermoplastic polyimide layer. You may carry out collectively in a process. Since the temperature above the melting point of the thermoplastic polyimide is as high as about 390 ° C., rapid cooling after heating may cause rapid shrinkage of the multilayer polyimide film, which may deteriorate the appearance. It is preferable to cool.

  The heating means is not particularly limited, and examples thereof include a hot air system and a far infrared system, and these may be used in combination. As for the heating method, either batch processing or continuous processing may be used, but from the viewpoint of productivity of the multilayer polyimide film, continuous processing is preferable.

  In the intermediate layer, the thermoplastic polyimide layer, and the manufacturing method thereof according to the present invention, either a thermal curing method or a chemical curing method may be employed. However, in consideration of manufacturing efficiency, a chemical curing method is employed for the core layer. Is particularly preferred.

  In the present invention, the non-thermoplastic polyimide layer (intermediate layer) whose dielectric loss tangent at 10 GHz in the step (1) is 0.001 to 0.009, in the TD direction perpendicular to the film flow direction (MD direction). The width of the thermoplastic polyimide layer to be further laminated through the non-thermoplastic polyimide layer having a lamination width (hereinafter, also simply referred to as width) and a dielectric loss tangent at 10 GHz of step (2) of 0.001 to 0.009. May be different.

  For example, the width of the intermediate layer in the step (1) and the width of the thermoplastic polyimide layer in the step (2) are not particularly limited as long as they are narrower than the width of the non-thermoplastic polyimide film serving as the core layer. If problems such as curling suppression and other edge irregularities can be solved, there is no problem whether the width of the intermediate layer in step (1) or the width of the thermoplastic polyimide layer in step (2) is wider. From the viewpoint of production efficiency, the width of the intermediate layer 1) is preferably wider. The width of the thermoplastic polyimide layer in the step (2) is not particularly limited as long as curling can be suppressed. It does not matter whether the width of the intermediate layer in step (1) or the width of the thermoplastic polyimide layer in step (2) is wider, but the width of the thermoplastic polyimide layer in step (2) is wider. It is preferable from the viewpoint of adhesiveness with a metal foil such as a copper foil.

(Metal foil)
The metal foil that can be used in the present invention is not particularly limited. For example, when the flexible metal-clad laminate of the present invention is used for electronic equipment / electric equipment, for example, copper or copper alloy, stainless steel or alloy thereof, nickel or nickel alloy (including 42 alloy), aluminum or aluminum A foil made of an alloy can be mentioned. In general flexible laminates, copper foil such as rolled copper foil and electrolytic copper foil is frequently used, but it can also be preferably used in the present invention. In addition, the surface of these metal foils may be coated with a rust inhibitor, a heat resistance imparting agent, or an adhesive. Moreover, it does not specifically limit about the thickness of the said metal foil, According to the use, what is necessary is just the thickness which can exhibit a sufficient function. A smooth surface of the metal foil is preferable for reducing transmission loss, and a copper foil of Ra 1.0 μm or less can be preferably used. Smooth copper foil for high-speed transmission is commercially available from various companies. The multilayer polyimide film used in the present invention has a high adhesiveness to the copper foil because the adhesive layer is a thermoplastic polyimide, and generally provides a good adhesion with a smooth copper foil that makes it difficult to obtain an anchor effect. Are better.

(Flexible metal-clad laminate)
In order to manufacture the flexible metal-clad laminate of the present invention, as a method of laminating a multilayer polyimide film and a metal foil, for example, a continuous treatment by a hot roll laminating apparatus having a pair of metal rolls or a double belt press (DBP) Can be used. Among these, it is preferable to use a hot roll laminating apparatus having a pair of metal rolls because the apparatus configuration is simple and advantageous in terms of maintenance cost. In addition, since a dimensional change is particularly likely to occur when bonded to a metal foil with a hot roll laminating apparatus having a pair of metal rolls, the multilayer polyimide film of the present invention was bonded to the metal foil with a hot roll laminating apparatus. In some cases, a significant effect is exhibited. The “heat roll laminating apparatus having a pair of metal rolls” herein may be an apparatus having a metal roll for heating and pressurizing a material, and the specific apparatus configuration is particularly limited. It is not a thing.

  The specific configuration of the means for carrying out the thermal lamination is not particularly limited, but a protective material is disposed between the pressing surface and the metal foil in order to improve the appearance of the resulting laminate. It is preferable to do. Examples of the protective material include materials that can withstand the heating temperature of the heat laminating process, that is, metal foil such as heat-resistant plastic, copper foil, aluminum foil, SUS foil, and the like. A material having the following is preferably used. The thickness of the protective material is not particularly limited as long as it can sufficiently serve as a buffer and a protective layer during lamination. For example, the thickness of the protective material is preferably 75 μm or more.

  Hereinafter, based on an Example and a comparative example, it demonstrates still more concretely about this invention. In addition, this invention is not limited to the following Example.

(Film thickness)
The thickness of the film was measured using LASER HOLOGAGE manufactured by Mitsutoyo.

(Measurement of dielectric loss tangent)
The dielectric loss tangent was measured using a network analyzer 8719C manufactured by HEWLETPACKARD and a cavity resonator vibration method dielectric constant measuring apparatus CP511 manufactured by Kanto Electronics Co., Ltd. A sample was cut into 2 mm × 100 mm, and the measurement was performed after conditioning for 24 hours in a 23 ° C./55% RH environment. The measurement was performed at 10 GHz.

(Yield)
Each process yield of the intermediate layers 1, 2, and 3 was calculated by B / A × 100 using the following A and B. The total yield was calculated by multiplying the yields of the intermediate layers 1, 2, and 3.
A: Production amount estimated from the input amount of film B: Production amount of film actually wound on a roll

(Synthesis Example 1: Synthesis of a precursor solution of non-thermoplastic polyimide having low dielectric loss tangent)
To a reaction vessel having a capacity of 100 L, 62.9 kg of dimethylformamide (DMF) and 2.3 kg of paraphenylenediamine (PDA) are added, and 3,3 ′, 4,4′-biphenyltetracarboxylic acid is stirred under a nitrogen atmosphere. 5.6 kg of dianhydride (BPDA) was gradually added. Subsequently, 2.6 kg of 1,3-bis (4-aminophenoxy) benzene (TPE-R) and 1.1 kg of BPDA were added, 0.5 kg of pyromellitic dianhydride (PMDA) was added, and the mixture was stirred for 1 hour. And dissolved. A solution in which 0.2 kg of PMDA was dissolved in 2.5 kg of DMF was separately prepared, and this was gradually added to the reaction solution while being careful of the viscosity and stirred. When the viscosity reached 1000 poise, the addition and stirring were stopped to obtain a polyamic acid solution 1 serving as a precursor solution of non-thermoplastic polyimide having low dielectric loss tangent.

  The polyamic acid solution was coated on an aluminum substrate so that the thickness after drying was 20 μm, heated at 120 ° C. for 3 minutes, and then dried at 350 ° C. for 120 seconds to obtain a single layer film. The dielectric loss tangent of this film was 0.004.

(Synthesis Example 2: Synthesis of precursor solution of thermoplastic polyimide)
To a reaction vessel having a capacity of 100 L, 64.1 kg of dimethylformamide (DMF) and 7.7 kg of BPDA were added, and 1.1 kg of TPE-R was gradually added while stirring under a nitrogen atmosphere. A solution in which 2 kg of TPE-R was dissolved in 40 kg of DMF was separately prepared, and this was gradually added to the reaction solution while being careful of the viscosity and stirred. When the viscosity reached 1000 poise, the addition and stirring were stopped to obtain a polyamic acid solution 2 to be a precursor solution of thermoplastic polyimide.

Example 1
9 μm thick high heat-resistant polyimide film (Apical (registered trademark) 9FP, Kaneka, 1600 mm wide roll film) is used as a core layer, and the inner side from the end 10 mm (a = 10 mm) of one side (A side) of this core layer The final single side of the non-thermoplastic polyimide having low dielectric loss tangent property (the intermediate layer 1) obtained by diluting the polyamic acid solution 1 obtained in Synthesis Example 1 with DMF until the solid content concentration becomes 8.0% by weight. The polyamic acid solution was applied so that the thickness was 2.5 μm, and then heated at 120 ° C. for 2 minutes. Subsequently, the polyamic acid solution obtained in Synthesis Example 1 was added with DMF until the solid content concentration became 8.0 wt% on the inner side from the end 20 mm (b = 20 mm) of the other side (B side) of the core layer. The dilute solution was coated with a polyamic acid solution so that the final one-side thickness of the non-thermoplastic polyimide having low dielectric loss tangent property (to be the intermediate layer 2) was 5 μm, and then heated at 120 ° C. for 2 minutes. Subsequently, a solution obtained by diluting the polyamic acid solution obtained in Synthesis Example 1 with DMF to a solid content concentration of 8.0% by weight on the inner side from the end 15 mm (c = 15 mm) of the A surface is low dielectric loss tangent. After applying the polyamic acid solution so that the final single-sided thickness of the non-thermoplastic polyimide (having the intermediate layer 3) having a thickness of 2.5 μm was heated at 120 ° C. for 2 minutes. Table 1 shows the results of the intermediate layer coating yield. The structure of the non-thermoplastic polyimide film and the non-thermoplastic polyimide layer having a low dielectric loss tangent is shown in FIG.

  Subsequently, the polyamic acid solution 2 obtained in Synthesis Example 2 is solidified on the outer surface of the intermediate layer applied to both surfaces of the core layer so that the final single-sided thickness of the thermoplastic polyimide (which becomes an adhesive layer) is 3 μm. After applying a polyamic acid solution diluted with DMF to a partial concentration of 8.0% by weight, heating was performed at 120 ° C. for 2 minutes to obtain a multilayer polyimide film. A rolled copper foil (GHY5-93F-HA; manufactured by JX Nippon Mining & Metals) having a thickness of 12 μm was thermally laminated on the obtained multilayer polyimide film, but a flexible copper foil laminate (FCCL) could be produced without any particular problem. .

(Example 2)
A laminated film was produced in the same manner as in Example 1 except that the position of the end of the intermediate layer 3 was changed to 25 mm (c = 25 mm). Table 1 shows the results of the intermediate layer coating yield. The structure of a non-thermoplastic polyimide film and a non-thermoplastic polyimide layer having a low dielectric loss tangent is shown in FIG.

(Example 3)
Each of the intermediate layer 1, the intermediate layer 2, and the intermediate layer 3 was produced in the same manner as in Example 1 except that the end position was changed to 10 mm (a = 10 mm, b = 10 mm, c = 10 mm), and a laminated film Was made. Table 1 shows the results of the intermediate layer coating yield. The structure of a non-thermoplastic polyimide film and a non-thermoplastic polyimide layer having a low dielectric loss tangent is shown in FIG.

(Comparative Example 1)
Fabricated in the same manner as in Example 1 except that the final single-sided thickness of the intermediate layer 1 is 5 μm (a = 5 mm), the position of the end of the intermediate layer 2 is 10 mm (b = 10 mm), and the intermediate layer 3 is not applied. Then, a laminated film was produced. Table 1 shows the results of the intermediate layer coating yield. The structure of the non-thermoplastic polyimide film and the non-thermoplastic polyimide layer having low dielectric loss tangent is shown in FIG.

  Further, as in Example 1, the polyamic acid solution 2 obtained in Synthesis Example 2 was applied and an attempt was made to heat laminate the rolled copper foil, but the curl of the multilayer polyimide film was tight and FCCL could not be obtained. .

(Comparative Example 2)
The intermediate layer 1 is placed inside the end 20 mm (a = 20 mm) on one side (A side) of the core layer so that the final single side thickness is 5 μm, and the end 10 mm on the other side (B side) of the core layer ( (b = 10 mm) inside, so that the final single-sided thickness is 2.5 μm, and further inside the B-side end 25 mm (c = 25 mm), so that the final single-sided thickness is 2.5 μm. Layer 3 was applied, and the others were produced in the same manner as in Example 1 to produce a laminated film. Table 1 shows the results of the intermediate layer coating yield. FIG. 7 shows the configuration of a non-thermoplastic polyimide film and a non-thermoplastic polyimide layer having a low dielectric loss tangent.

  As in Example 1, the polyamic acid solution 2 obtained in Synthesis Example 2 was applied and an attempt was made to heat laminate the rolled copper foil, but the multilayer polyimide film was curled and FCCL could not be obtained.

(Comparative Example 3)
Each of the intermediate layer 1, the intermediate layer 2, and the intermediate layer 3 was prepared in the same manner as in Comparative Example 2 except that the end position was changed to 10 mm (a = 10 mm, b = 10 mm, c = 10 mm), and a laminated film Was made. Table 1 shows the results of the intermediate layer coating yield. FIG. 8 shows the configuration of a non-thermoplastic polyimide film and a non-thermoplastic polyimide layer having a low dielectric loss tangent.

  As in Example 1, the polyamic acid solution 2 obtained in Synthesis Example 2 was applied and an attempt was made to heat laminate the rolled copper foil, but the multilayer polyimide film was curled and FCCL could not be obtained.

(Discussion)
From the results of Examples and Comparative Examples, it was confirmed that the yield was improved by laminating two or more layers on at least one side.

1. Non-thermoplastic polyimide film 2, 21, 22, 23. 2. Non-thermoplastic polyimide layer having low dielectric loss tangent 3. Thermoplastic polyimide layer Multilayer polyimide film

Claims (3)

A multilayer polyimide film characterized by laminating a non-thermoplastic polyimide layer having a dielectric loss tangent at 10 GHz of 0.001 to 0.009 on at least one surface of the non-thermoplastic polyimide film, and further laminating a thermoplastic polyimide layer. A manufacturing method comprising:
(1) forming at least two or more non-thermoplastic polyimide layers having a dielectric loss tangent at 10 GHz of 0.001 to 0.009 on at least one surface of the non-thermoplastic polyimide film;
(2) A step of further laminating a thermoplastic polyimide layer through the non-thermoplastic polyimide layer obtained in step (1) and performing a heat treatment to obtain a prefilm,
(3) A step of further heat-treating the prefilm obtained in step (2) to obtain a multilayer polyimide film,
The manufacturing method of the multilayer polyimide film characterized by including.   The width of the non-thermoplastic polyimide layer having a dielectric loss tangent at 10 GHz in the step (1) of 0.001 to 0.009 and the non-heat in which the dielectric loss tangent at 10 GHz of the step (2) is 0.001 to 0.009. The method for producing a multilayer polyimide film according to claim 1, wherein the widths of the plastic polyimide layers are different. The non-thermoplastic polyimide layer having a dielectric loss tangent of 0.001 to 0.009 at 10 GHz is at least 2,2′-dimethylbiphenyl-4,4′-diamine as an aromatic dianhydride, 1,3- Any one of bis (4-aminophenoxy) benzene, as an aromatic diamine, at least 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 3,3 ′, 4,4′-benzophenonetetracarboxylic The manufacturing method of the multilayer polyimide film of Claim 1 or 2 characterized by including the polyimide which has any one of acid dianhydride and pyromellitic dianhydride.