JP2007253384A - Multilayered polyimide film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a multilayered polyimide film which has heat resistance and surface adhesiveness and of which the coefficient of linear expansion is within a specific range. <P>SOLUTION: The multilayered polyimide film is constituted by laminating a layer (a) comprising a polyamideimide and a layer (b) comprising a polyimide which has at least a pyromellitic acid residue as a residue of an aromatic tetracarboxylic acid and a diamine residue having an oxidianilin (diaminophenyl ether) skeleton as a residue of an aromatic diamine. The thickness ratio (a)/(b) of the layer (a) and the layer (b) is 0.001-0.5 and the thickness of the layer (b) is 3-50 μm. The coefficient of linear expansion in the surface direction of the multilayered polyimide film is 10-25 ppm/°C. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  This invention uses the polyimide film excellent in heat resistance as a base film (b), and the heat resistance characteristic of a base film (b) is hold | maintained by laminating the surface with a polyamideimide (a), and surface physical properties are obtained. The present invention relates to a multilayer polyimide film having physical properties excellent in adhesion possessed by polyamideimide (a).

  Polyimide films have very little change in physical properties over a wide temperature range from −269 ° C. to 300 ° C., and therefore, applications and uses in the electric and electronic fields are expanding. In the electric field, for example, it is used for coil insulation of vehicle motors, industrial motors, etc., insulation of aircraft electric wires and superconducting wires. On the other hand, in the electronic field, for example, it is used for a flexible printed circuit board, a base film of a film carrier for semiconductor mounting, and the like. Thus, the polyimide film is widely used in the electrical and electronic fields as a highly reliable film among various functional polymer films. Recently, however, major problems have become apparent with the refinement of the electric and electronic fields. For example, a printed circuit board made of a polyimide film base material in which copper is copper-clad by vapor deposition or plating or the like has a tendency that the adhesive force of the copper layer is lowered due to a change with time and an environmental change, and further peeling occurs.

In addition, ceramic has been conventionally used as a material for base materials of electronic components such as information communication equipment (broadcast equipment, mobile radio equipment, portable communication equipment, etc.), radar, high-speed information processing devices, and the like. A base material made of ceramic has heat resistance, and can cope with an increase in the frequency band (reaching the GHz band) of information communication equipment in recent years. However, ceramics are not flexible and cannot be thinned, so the fields that can be used are limited.
For this reason, studies have been made to use a film made of an organic material as a base material for an electronic component, and a film made of polyimide and a film made of polytetrafluoroethylene have been proposed. A film made of polyimide has excellent heat resistance and has the advantage that the film can be thin because it is tough. However, there are concerns about problems such as low signal strength and signal transmission delay when applied to high-frequency signals. However, the tensile strength at break and the tensile modulus are still insufficient, and the linear expansion coefficient is too large. A film made of polytetrafluoroethylene can handle high frequencies, but the tensile modulus is low, so the film cannot be made thin, the adhesion to metal conductors and resistors on the surface is poor, and the coefficient of linear expansion However, it is problematic in that it is not suitable for the production of a circuit having fine wiring due to a large dimensional change due to temperature change. Thus, a film having sufficient physical properties for a substrate having heat resistance, high mechanical properties, and flexibility has not been obtained yet.

As a polyimide film having a high tensile modulus, a polyimide benzoxazole film made of polyimide having a benzoxazole ring in the main chain has been proposed (see Patent Document 1). A printed wiring board using the polyimide benzoxazole film as a dielectric layer has also been proposed (see Patent Document 2 and Patent Document 3).
Polyimide benzoxazole films consisting of polyimides with these benzoxazole rings in the main chain have improved tensile tensile strength and tensile elastic modulus and are within the range of satisfactory linear expansion coefficients. In spite of its physical properties, it has problems such as insufficient surface properties in terms of adhesion.
Various proposals have been made to improve the adhesion of polyimide with excellent physical properties. For example, a polyimide film that has a thermoplastic resin layer on at least one surface of a polyimide film that does not have adhesion (see Patent Document 4), a polyimide film And at least a two-layer film in which a film made of polyamide resin is laminated (see Patent Document 5).
Those with a thermoplastic resin layer on these polyimide films are not fully satisfactory in improving adhesion, and the low heat resistance of these thermoplastic resins ruins the heat resistance of the folded polyimide film. Had a tendency to
Japanese Patent Laid-Open No. 06-56992 Japanese National Patent Publication No. 11-504369 Japanese National Patent Publication No. 11-505184 Japanese Patent Laid-Open No. 09-169088 JP 07-186350 A

  An object of the present invention is to provide a film having excellent mechanical properties of a polyimide film excellent in heat resistance and sufficiently improved surface properties such as adhesiveness.

This invention solves the said subject by laminating | stacking a specific adhesive bond layer on the at least single side | surface of a specific polyimide, and achieves the objective.
That is, this invention consists of the following structures.
1. The multilayer polyimide film of the structure by which the following (a) layer and (b) layer are laminated | stacked at least.
(A) Layer: polyamideimide,
(B) Layer: A polyimide having at least a pyromellitic acid residue as an aromatic tetracarboxylic acid residue and a diamine residue having an oxydianiline skeleton as an aromatic diamine residue.
2. 2. The multilayer polyimide film according to 1 above, wherein the multilayer polyimide film has a three-layer structure of (a) / (b) / (a).
3. (A) The multilayer polyimide film according to 1 or 2 above, wherein the polyamideimide of the layer is a polyamideimide composition in which an epoxy resin of 1% by mass to 30% by mass in terms of solid content is blended.
4). The ratio (a) / (b) of the thickness of the (a) layer and the (b) layer is 0.001 to 0.5, and the thickness of the (b) layer is 3 to 50 μm. A multilayer polyimide film according to any one of the above.
5). The multilayer polyimide film according to any one of 1 to 4 above, wherein a linear expansion coefficient in the plane direction of the multilayer polyimide film is 10 to 25 ppm / ° C.

  The polyamideimide of the (a) layer of the present invention and the pyromellitic acid residue as the residue of at least the aromatic tetracarboxylic acid of the (b) layer, and the diamine residue having an oxydianiline skeleton as the residue of the aromatic diamine A film in which polyimide having (hereinafter also referred to as diaminodiphenyl ether residue) is laminated, and the ratio (a) / (b) of the thickness of (a) layer and (b) layer is 0.001 to 0.5. (B) The multilayer polyimide film having a layer thickness of 3 to 50 μm retains the heat resistance of the (b) layer polyimide film and the linear expansion coefficient in a specific range, and is in contact with the metal. The surface becomes a film possessing the physical properties possessed by the polyamide-imide having excellent adhesion of the layer (a) and has both excellent points. It is effective like the substrate film of Lum, for example, very useful as a flexible printed circuit board.

The multilayer polyimide film of the present invention is a multilayer polyimide film having a configuration in which at least (a) layer and (b) layer are laminated, (a) layer is composed of a polyamideimide layer, and (b) layer is at least aromatic. A layer of polyimide having a pyromellitic acid residue as a residue of an aromatic tetracarboxylic acid and a diamine residue having an oxydianiline skeleton as a residue of an aromatic diamine, wherein the layers (a) and (b) A multilayer polyimide film having a thickness ratio (a) / (b) of 0.001 to 0.5 and (b) a thickness of 3 to 50 μm.
The polyimide film having a diamine residue having an oxydianiline skeleton as a residue of at least a pyromellitic acid residue as a residue of an aromatic tetracarboxylic acid and a residue of an aromatic diamine as a layer (b) in the present invention, For example, an aromatic tetracarboxylic acid such as pyromellitic acid (including anhydrides and derivatives) and a diamine having an oxydianiline skeleton are reacted in a solvent to obtain a polyamic acid solution that is a precursor of the polyimide. Can be cast on a support, dried to obtain a polyimide precursor film (also referred to as a green film), and the precursor film is further heat-treated to be imidized to obtain a polyimide film.

The polyimide having a pyromellitic acid residue as the residue of the aromatic tetracarboxylic acid that is the layer (b) and the oxydianiline skeleton as the residue of the aromatic diamine in the present invention will be described in detail below.
In the present invention, a pyromellitic acid residue is a pyromellitic acid that is formed by a reaction with an aromatic diamine from a functional derivative such as pyromellitic acid and an anhydride or halide. It refers to a residue derived from merit acid. A diamine residue (diaminodiphenyl ether residue) having an oxydianiline skeleton is a bond in polyamic acid or polyimide formed by reaction of oxydianiline (diaminodiphenyl ether) with aromatic tetracarboxylic acids from various derivatives thereof. This is a residue derived from oxydianiline (diaminodiphenyl ether).
Hereinafter, in the present invention, other aromatic tetracarboxylic acid residues and other aromatic diamine residues have the same meaning.

The polyimide film of layer (b) as the substrate of the present invention is made of polyimide obtained by reacting aromatic diamines and aromatic tetracarboxylic acids, and the polyimide is at least a residue of aromatic tetracarboxylic acids. It has a pyromellitic acid residue as a group and a diaminodiphenyl ether residue as a residue of an aromatic diamine.
In the above-mentioned “reaction”, first, aromatic diamines and aromatic tetracarboxylic acids are subjected to a ring-opening polyaddition reaction or the like in a solvent to obtain an aromatic polyamic acid solution, and then the aromatic polyamic acid solution. After forming a green film from the above, it is performed by high-temperature heat treatment or dehydration condensation (imidization).

The aromatic polyamic acid is a substance comprising the above aromatic tetracarboxylic acids (collectively referred to as acids, anhydrides and functional derivatives, hereinafter also referred to as aromatic tetracarboxylic acids) and aromatic diamines (hereinafter also referred to as aromatic diamines). In particular, an equimolar amount is preferably produced by reacting and polymerizing in an inert organic solvent at a polymerization temperature of 90 ° C. or less for 1 minute to several days. The aromatic tetracarboxylic acid and the aromatic diamine may be added to the organic solvent as a mixture or as a solution, or an organic solvent may be added to the above components. The organic solvent may dissolve some or all of the polymerization components and preferably dissolves the copolyamic acid polymer.
Preferred solvents include N, N-dimethylformamide and N, N-dimethylacetamide. Other useful compounds of this type are N, N-diethylformamide and N, N-diethylacetamide. Other solvents that can be used are dimethyl sulfoxide, N-methyl-2-pyrrolidone, N-cyclohexyl-2-pyrrolidone and the like. Solvents can be used alone or in combination with each other or with poor solvents such as benzene, benzonitrile, dioxane and the like.
The amount of solvent used is preferably in the range of 75-90% by weight of the aromatic polyamic acid solution, since this concentration range gives the optimum molecular weight. The aromatic tetracarboxylic acid and the aromatic diamine component need not be used in absolute equimolar amounts. In order to adjust the molecular weight, the molar ratio of aromatic tetracarboxylic acid: aromatic diamine is in the range of 0.90 to 1.10.
The aromatic polyamic acid solution produced as described above contains 5 to 40% by mass, preferably 10 to 25% by mass of the polyamic acid polymer.

In the present invention, among these aromatic diamines, diaminodiphenyl ether (oxydianiline) is a preferred diamine. Specific examples of diaminodiphenyl ether include 4,4′-diaminodiphenyl ether (DADE), 3,3′-diaminodiphenyl ether and 3,4′-diaminodiphenyl ether.
In a preferred embodiment, a small amount of phenylenediamine, preferably p-phenylenediamine, can be used in addition to these diaminodiphenyl ethers. Furthermore, in addition to these aromatic diamines, other aromatic diamines may be appropriately selected and used.
In the present invention, among the aromatic tetracarboxylic acids, pyromellitic acids (pyromellitic acid and its dianhydride (PMDA) and lower alcohol esters thereof) are preferable.
As a preferred embodiment, in addition to pyromellitic acid, a small amount of biphenyltetracarboxylic acid, preferably 3,3 ′, 4,4′-biphenyltetracarboxylic acid can be used. Furthermore, in addition to these aromatic tetracarboxylic acids, other aromatic tetracarboxylic acids may be appropriately selected and used.
In the present invention, diaminodiphenyl ethers are 80 to 100 mol% based on the total aromatic diamines, phenylenediamines are 0 to 20 mol% based on the total aromatic diamines, and other aromatic diamines other than the former two. It is preferable to use 0 to 20 mol% of the aromatics based on the total aromatic diamines. When the mole% ratio exceeds this range, the balance as a heat-resistant polyimide film such as flexibility, rigidity, strength, elastic modulus water absorption, hygroscopic expansion coefficient, and elongation is lost.

  In the present invention, pyromellitic anhydride is 80 to 100 mol% with respect to the wholly aromatic tetracarboxylic acid, and biphenyltetracarboxylic acid, preferably 3,3 ', 4,4'-biphenyltetracarboxylic anhydride is wholly aromatic. It is preferable to use 0-20 mol% with respect to the aromatic tetracarboxylic acids, and 0-20 mol% with respect to the total aromatic tetracarboxylic acids. When the mole% ratio exceeds this range, the balance as a heat-resistant polyimide film such as flexibility, rigidity, strength, elastic modulus, water absorption rate, hygroscopic expansion coefficient, and elongation is lost, which is not preferable.

Although what can be used other than said aromatic diamines and aromatic tetracarboxylic acids is not specifically limited, For example, it shows as follows.
5-amino-2- (p-aminophenyl) benzoxazole, 6-amino-2- (p-aminophenyl) benzoxazole, 5-amino-2- (m-aminophenyl) benzoxazole, 6-amino-2 -(M-aminophenyl) benzoxazole, 4,4'-bis (3-aminophenoxy) biphenyl, bis [4- (3-aminophenoxy) phenyl] ketone, bis [4- (3-aminophenoxy) phenyl] Sulfide, bis [4- (3-aminophenoxy) phenyl] sulfone, 2,2-bis [4- (3-aminophenoxy) phenyl] propane, 2,2-bis [4- (3-aminophenoxy) phenyl] -1,1,1,3,3,3-hexafluoropropane, 3,3′-diaminodiphenyl sulfide, 3,3′-diaminodiph Nyl sulfoxide, 3,4'-diaminodiphenyl sulfoxide, 4,4'-diaminodiphenyl sulfoxide, 3,3'-diaminodiphenyl sulfone, 3,4'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl sulfone, 3, 3'-diaminobenzophenone, 3,4'-diaminobenzophenone, 4,4'-diaminobenzophenone, 3,3'-diaminodiphenylmethane, 3,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylmethane, bis [4- (4-aminophenoxy) phenyl] methane, 1,1-bis [4- (4-aminophenoxy) phenyl] ethane, 1,2-bis [4- (4-aminophenoxy) phenyl] ethane, 1,1- Bis [4- (4-aminophenoxy) phenyl] propane, 1,2-bis [4- ( 4-aminophenoxy) phenyl] propane, 1,3-bis [4- (4-aminophenoxy) phenyl] propane, 2,2-bis [4- (4-aminophenoxy) phenyl] propane.
Some or all of the hydrogen atoms on the aromatic ring in the aromatic diamine are halogen atoms, alkyl groups having 1 to 3 carbon atoms or alkoxyl groups, cyano groups, or some or all of hydrogen atoms of alkyl groups or alkoxyl groups. An aromatic diamine substituted with a halogenated alkyl group having 1 to 3 carbon atoms substituted with a halogen atom or an alkoxyl group is exemplified.

Bisphenol A bis (trimellitic acid monoester acid anhydride), 2,2-bis [4- (3,4-dicarboxyphenoxy) phenyl] propanoic acid anhydride, 3,3 ′, 4,4′-benzophenone tetra Carboxylic dianhydride, 3,3 ′, 4,4′-diphenylsulfone tetracarboxylic dianhydride, 1,4,5,8-naphthalene tetracarboxylic dianhydride, 2,3,6,7-naphthalene Tetracarboxylic dianhydride, 4,4′-oxydiphthalic anhydride, 3,3 ′, 4,4′-dimethyldiphenylsilanetetracarboxylic dianhydride, 1,2,3,4-furantetracarboxylic acid Anhydrides, 4,4′-bis (3,4-dicarboxyphenoxy) diphenylpropanoic acid dianhydride, 4,4′-hexafluoroisopropylidenediphthalic anhydride and the like.
Although the thickness of the polyimide film as the (b) layer as the substrate of the present invention is not particularly limited, it is usually from 1 to 150 μm, preferably from 3 to 50 μm in consideration of use as the substrate of the electronic substrate. This thickness can be easily controlled by the amount of the polyamic acid solution applied to the support and the concentration of the polyamic acid solution.
In the polyimide film as the substrate of the present invention, it is preferable to improve the slipperiness of the film by imparting fine irregularities to the film surface by adding a lubricant to the polyimide.
As the lubricant, inorganic or organic fine particles having an average particle diameter of about 0.03 to 3 μm can be used. Specific examples include titanium oxide, alumina, silica, calcium carbonate, calcium phosphate, calcium hydrogen phosphate, calcium pyrophosphate, Examples include magnesium oxide, calcium oxide, and clay minerals.

Conventionally known conditions may be applied for the polymerization reaction for obtaining the polyamic acid (hereinafter also simply referred to as “polymerization reaction”). As a specific example, in a temperature range of 0 to 80 ° C., 10 Stirring and / or mixing continuously for 30 minutes. If necessary, the polymerization reaction may be divided or the temperature may be increased or decreased. In this case, the order of adding both monomers is not particularly limited, but it is preferable to add aromatic tetracarboxylic acid anhydrides to the solution of aromatic diamines. The mass of the polyamic acid in the polyamic acid solution obtained by the polymerization reaction is preferably 5 to 40% by mass, more preferably 10 to 30% by mass, and the viscosity of the solution is measured with a Brookfield viscometer (25 ° C.). From the viewpoint of the stability of liquid feeding, it is preferably 10 to 2000 Pa · s, and more preferably 100 to 1000 Pa · s.
The reduced viscosity (ηsp / C) of the polyamic acid in the present invention is not particularly limited, but is preferably 2.0 dl / g or more, and more preferably 3.0 dl / g or more.

Vacuum defoaming during the polymerization reaction is effective for producing a high-quality polyamic acid organic solvent solution. Moreover, you may perform superposition | polymerization by adding a small amount of terminal blockers to aromatic diamines before a polymerization reaction. Examples of the end capping agent include compounds having a carbon-carbon double bond such as maleic anhydride. The amount of maleic anhydride used is preferably 0.001 to 1.0 mol per mol of aromatic diamine.
In order to form the polyimide film of the layer (b) from the polyamic acid solution obtained by the polymerization reaction, the polyamic acid solution is applied on a support and dried to obtain a green film. A method of imidization reaction by subjecting to heat treatment can be mentioned.

  The support to which the polyamic acid solution is applied (similarly in the case of coextrusion) only needs to have smoothness and rigidity sufficient to form the polyamic acid solution into a film, and the surface thereof is made of metal, plastic, Examples thereof include a drum or belt-shaped rotating body such as glass and porcelain. A method using a polymer film having moderate rigidity and high smoothness is also a preferred embodiment. Among them, the surface of the support is preferably a metal, more preferably stainless steel that does not rust and has excellent corrosion resistance. The surface of the support may be plated with metal such as Cr, Ni, or Sn. The surface of the support can be mirror-finished or processed into a satin finish as required. Application of the polyamic acid solution to the support includes, but is not limited to, casting from a slit base, extrusion through an extruder, squeegee coating, reverse coating, die coating, applicator coating, wire bar coating, etc. Conventionally known solution coating means can be appropriately used.

The polyamideimide as the layer (a) in the present invention can be produced by a conventionally known direct method (reaction of acid anhydride and amine), an acid chloride method, an isocyanate method, or the like.
Examples of monomers that can be used are shown below in the form of an acid component and an amine component. These isocyanates can be used as the amine component, and these acid anhydrides and acid chlorides can also be used as the acid component.
Examples of the amine component include p-phenylenediamine, m-phenylenediamine, 4,4′-diaminodiphenyl ether, 4,4′-diaminodiphenylmethane, 4,4′-diamino-diphenylsulfone, 4,4′-diaminobenzophenone, 2 2,2'-bis (4-aminophenyl) propane, 2,4-tolylenediamine, 2,6-tolylenediamine, p-xylylenediamine, m-xylylenediamine, isophorone, hexamethylenediamine and the like. .
Examples of the acid component include terephthalic acid, isophthalic acid, trimellitic acid, 4,4′-biphenyldicarboxylic acid, pyromellitic acid, 3,3 ′, 4,4′-benzophenonetetracarboxylic acid, 3,3 ′, 4, Examples include 4'-biphenylsulfonetetracarboxylic acid, adipic acid, sebacic acid, maleic acid, fumaric acid, dimer acid, stilbene dicarboxylic acid, and the like.

The polyamideimide as the layer (a) in the present invention is 1% by mass to 30% in terms of solid content.
It is a preferable embodiment to contain a mass% of an epoxy resin. Examples of the epoxy resin used in the present invention include phenol novolac type epoxy resins, O-cresol novolac type epoxy resins, bisphenol A type epoxy resins, bisphenol F type epoxy resins, glycidyl amine type epoxy resins, glycidyl ether type epoxy resins, and glycidyl. Epoxy equivalents of ester-type epoxy resins, amine-modified epoxy resins such as N, N, N ′, N′-tetraglycidylmetaxylenediamine, isocyanurate epoxy resins such as triglycidyl isocyanurate, or hydrides and halides thereof. Can be used regardless. In particular, a phenol novolac type epoxy resin such as Epicoat 154 (manufactured by Yuka Shell Co., Ltd.) is preferable from the balance between heat resistance after lamination and curing and heat fusion property at the time of lamination, and the blending amount is from 1% by mass. 30% by mass is preferred. If it is less than 1% by mass, the effect of improving the heat-fusibility at the time of lamination is small, and if it exceeds 30% by mass, the heat resistance after lamination and curing is lowered. Moreover, the epoxy resin used by this invention can also be used with 2 or more types of mixtures.

The method of multilayering (lamination) of the multilayer polyimide film of the present invention is not particularly limited as long as there is no problem in adhesion between the two layers, and the multilayer polyimide film is adhered without interposing another layer such as an adhesive layer. For example, a method by coextrusion, a method in which the other polyamic acid solution is cast on a polyimide film which is one layer, and imidized by this, (b) a polyamide in (a) on a layer Examples include a method of imidizing by applying an acid solution by spray coating or the like.
The multi-layer structure is sufficient if at least the (a) layer and the (b) layer are laminated, but the (a) layer is laminated on the (b) layer, (a) / (b) / (a The layer (a) is preferably laminated on both sides of the layer (b).

The thickness ratio of (a) / (b) in the multilayer polyimide film of the present invention is the ratio of the thickness of (a) / (b) (in the case of a three-layer structure (a ) Is a calculation in a single layer) is preferably 0.001 to 0.5, more preferably 0.005 to 0.20. When the thickness ratio of (a) / (b) exceeds 0.5, the mechanical strength may be insufficient or the linear expansion coefficient may be too large. On the other hand, if it is less than 0.001, the effect of improving the surface characteristics may be insufficient. The thickness of the (b) layer mainly responsible for mechanical strength is preferably 3 to 50 μm.
With these structures, a multilayer polyimide film having heat resistance and a linear expansion coefficient in the plane direction of 10 to 25 ppm / ° C. is obtained.

The measurement of the linear expansion coefficient (CTE) in the surface direction in the present invention is as follows.
<Measurement of linear expansion coefficient of multilayer polyimide film>
About the multilayer polyimide film to be measured, the stretch rate in the MD direction and the TD direction is measured under the following conditions, and the stretch rate / temperature at intervals of 90 ° C. to 100 ° C., 100 ° C. to 110 ° C.,. Then, this measurement was performed up to 400 ° C., and the average value of all measured values from 100 ° C. to 350 ° C. was calculated as CTE (average value). The meanings of the MD direction and the TD direction indicate the flow direction (MD direction; the length direction of the long film) and the width direction (TD direction; the width direction of the long film). The linear expansion coefficient in the plane direction is an average value of values in the MD direction and the TD direction.
Device name: TMA4000S manufactured by MAC Science
Sample length; 10mm
Sample width: 2 mm
Temperature rise start temperature: 25 ° C
Temperature rising end temperature: 400 ° C
Temperature increase rate: 5 ° C / min
Atmosphere: Argon

In the multilayer polyimide film of the present invention, the layer (a) and the layer (b) are provided with a lubricant in the polyimide to give fine irregularities on the surface of the layer (film), thereby improving the slipperiness of the film. It is preferable.
As the lubricant, inorganic or organic fine particles having an average particle diameter of about 0.03 μm to 3 μm can be used. Specific examples include titanium oxide, alumina, silica, calcium carbonate, calcium phosphate, calcium hydrogen phosphate, calcium pyrophosphate, Examples include magnesium oxide, calcium oxide, and clay minerals.
In the present invention, the surface of the obtained multilayer polyimide film (particularly the surface of (a)) is preferably subjected to corona treatment, atmospheric pressure plasma treatment and vacuum plasma discharge treatment in order to further increase the adhesive force. is there.
The atmospheric pressure plasma treatment is preferably an inert gas plasma, and nitrogen gas, Ne, Ar, Kr, or Xe is used as the inert gas. There is no particular limitation on the method for generating plasma, and an inert gas may be introduced into the plasma generator to generate plasma. The time required for the plasma treatment is not particularly limited, and is usually 1 second to 30 minutes, preferably 10 seconds to 10 minutes. There are no particular restrictions on the frequency and output of the plasma during the plasma processing, the gas pressure for generating the plasma, and the processing temperature as long as they can be handled by the plasma processing apparatus. The frequency is usually 13.56 MHz, the output is usually 50 W to 1000 W, the gas pressure is usually 0.01 Pa to 10 Pa, and the temperature is usually 20 ° C. to 250 ° C., preferably 20 ° C. to 180 ° C. If the output is too high, the film surface may crack. If the gas pressure is too high, the smoothness of the film surface may be reduced.

EXAMPLES Hereinafter, although this invention is demonstrated in detail based on an Example, this invention is not limited by these Examples. In addition, evaluation and measurement in Examples and the like are as follows except for those described above. In addition, it is appropriately described in the description of examples and the like.
1. Reduced viscosity of polyamic acid (ηsp / C)
A solution dissolved in N-methyl-2-pyrrolidone so that the polymer concentration was 0.2 g / dl was measured at 30 ° C. using an Ubbelohde type viscosity tube.
2. Measurement of Solution Viscosity The solution viscosity of the polymer solution was measured using 20 ° C., 1 rpm, and optional rotor 3 ° R14 (Toki Sangyo Co., Ltd., R115 viscometer).
3. Film thickness The film thickness was measured using a micrometer (Millitron 1254D manufactured by Fine Reef Co., Ltd.).

4). Peel strength After the metallized film to be measured was processed into a TAB tape pattern with a wiring width of 90 μm, the peel strength was defined as the strength required when peeled off in the 90 ° direction. The measurement was performed using a tensile tester (manufactured by Shimadzu Corporation, autograph model name AG-5000A) according to JIS C6481.

[Polymerization of polyamic acid (1)]
<Polymerization of polyamic acid composed of diamine having paradiaminodiphenyl ether>
A container equipped with a nitrogen introduction tube, a thermometer, and a stirring rod was purged with nitrogen, and then diaminodiphenyl ether (ODA) was added. Next, dimethylacetamide (DMAC) was added and completely dissolved, and then pyromellitic dianhydride (PMDA) was added in an equimolar amount with respect to diaminodiphenyl ether so that ODA and PMDA as monomers were 1/1. Polymerization was carried out in DMAC at a molar ratio so that the monomer charge concentration was 15% by mass and stirring was carried out at 25 ° C. for 48 hours to obtain a brown viscous polyamic acid solution (1). Ηsp / C of the obtained solution was 4.2 dl / g. The solution viscosity was 89 Pa · s.

[Preparation of polyamideimide solution (2)]
In a four-necked separable flask equipped with a thermometer, a stirrer, a reflux condenser and a nitrogen introduction tube, 19.28 g (0.10 mol) of trimellitic anhydride, 2,4-tolylene diisocyanate (2,4-TDI) ) 3.50 g (0.02 mol) and 21.10 g (0.08 mol) of tolylene diisocyanate (TODI) are added to 150 g of N-methyl-2-pyrrolidone (NMP), and the mixture is stirred up to 160 ° C. The temperature was raised over time, and the reaction was further continued at 160 ° C. for 5 hours to obtain a polyamideimide solution (2). The reduced viscosity of the obtained polymer in NMP was 1.81 dl / g. The solution viscosity was 25 Pa · s.

[Adjustment of polyamide-imide epoxy mixed resin (3)]
By blending 10% by mass of a commercially available epoxy resin (produced by Japan Epoxy Resin Co., Ltd., Epicoat 154 (trade name)) with the above polyamideimide solution (2), NMP is added to obtain a 15% by mass solution. A polyamideimide epoxy mixed resin solution (3) was prepared. The solution viscosity was 14 Pa · s.

[Adjustment of polyamide-imide epoxy mixed resin (4)]
By blending 3% by mass of a commercially available epoxy resin (Japan Epoxy Resin Co., Ltd., Epicoat 154 (trade name)) with the above polyamideimide solution (2), NMP is added to make a 15% by mass solution. A polyamideimide epoxy mixed resin solution (4) was prepared. The solution viscosity was 13 Pa · s.

[Adjustment of Polyamidoimide Epoxy Mixed Resin (5)]
By blending 50% by mass of a commercially available epoxy resin (produced by Japan Epoxy Resin Co., Ltd., Epicoat 154 (trade name)) with the above polyamideimide solution (2), NMP is added to obtain a 15% by mass solution. A polyamideimide epoxy mixed resin solution (5) was prepared. The solution viscosity was 20 Pa · s.

Example 1
The above-mentioned polyamic acid solution (1) and the polyamidoimide solution (2) were coated on a stainless steel belt using a three-layer coextrusion T-die. (1) was used as the core layer ((b) layer), and (2) was used as the skin layer ((a) layer). The die lip gap was 50 μm skin layer and 400 μm core layer. Next, the polyamic acid film having self-supporting property obtained by drying at 90 ° C. for 60 minutes was peeled from the stainless steel belt to obtain a polyimide precursor film (green film) having a thickness of 40 μm.
The obtained green film was heated in a continuous drying oven at 170 ° C. for 3 minutes, then heated to 450 ° C. in about 20 seconds and heated at 450 ° C. for 7 minutes, and then in 5 minutes. After cooling to room temperature, a brown multilayer polyimide film having a thickness of 25 μm was obtained. This multilayer polyimide film was slit to a width of 500 mm to obtain a multilayer polyimide film. The thickness ratio of (a) / (b) / (a) in this multilayer polyimide film is 0.13 / 1 / 0.13. The obtained multilayer film was embedded with an epoxy resin, cut with a microtome so that the film cross section could be observed, and the cross section was observed with a scanning electron microscope. In the electron microscopic image of the cross section, the boundary between the layers having different compositions could be observed in a striped pattern, and the thickness ratio was consistent with the thickness ratio obtained from the coating thickness.

The above film is mounted on a continuous sputtering apparatus, using a target of a frequency of 13.56 MHz, an output of 400 W, a gas pressure of 0.8 Pa, a nickel-chromium (chromium content 10%) alloy target, and an RF sputtering method in a xenon atmosphere. Thus, a nickel-chromium alloy film having a thickness of 50 mm was formed at a rate of 10 mm / sec. Subsequently, copper was vapor-deposited at a rate of 100 liters / second to form a copper thin film having a thickness of 0.3 μm. Thereafter, this film is cut out to 250 mm × 400 mm, fixed to a plastic frame, and a thick copper plating layer having a thickness of 5 μm is formed on the copper thin film using a copper sulfate plating bath. A polyimide film was obtained.
After the obtained metallized multilayer polyimide film was processed into a TAB tape pattern having a wiring width of 90 μm, the strength required when peeled off in the 90-degree direction was measured.
The results are shown in Table 1. (In the table, the measurement results of the multilayer polyimide film are shown except for the peel strength. The same applies hereinafter.)

(Example 2)
The above polyamic acid solution (1) was coated on a stainless steel belt using a T-type die. The die lip gap was 400 μm. Next, the self-supporting polyamic acid film obtained by drying at 90 ° C. for 60 minutes was peeled off from the stainless steel belt to obtain a polyimide precursor film (green film) having a thickness of 32 μm.
The NMP solution (2) was coated again on the green film using a T-type die. The die lip gap was 50 μm. Next, a multilayer polyimide acid precursor film having a thickness of 36 μm and having a self-supporting property obtained by drying at 90 ° C. for 60 minutes was obtained.
A multilayer polyimide film was obtained in the same manner as in Example 1. The thickness ratio of (a) / (b) in this multilayer polyimide film is 0.13 / 1.
Thereafter, a metallized multilayer polyimide film was obtained in the same manner as in Example 1.
After the obtained metallized multilayer polyimide film was processed into a TAB tape pattern having a wiring width of 90 μm, the strength required when peeled off in the 90-degree direction was measured. The results are shown in Table 1.

(Example 3)
The above polyamic acid solution (1) was coated on a stainless steel belt using a T-type die. The die lip gap was 400 μm. Next, the self-supporting polyamic acid film obtained by drying at 90 ° C. for 60 minutes was peeled off from the stainless steel belt to obtain a polyimide precursor film (green film) having a thickness of 32 μm.
The obtained green film was heated in a continuous drying oven at 170 ° C. for 3 minutes, then heated to 450 ° C. in about 20 seconds and heated at 450 ° C. for 7 minutes, and then in 5 minutes. After cooling to room temperature, a brown polyimide film having a thickness of 20 μm was slit into a width of 500 mm to obtain a polyimide film.
The polyamideimide solution (2) was coated again on the obtained polyimide film using a T-type die. The lip gap of the die was 100 μm. Next, a multilayer polyamic acid precursor film having a thickness of 30 μm and having a self-supporting property obtained by drying at 90 ° C. for 60 minutes was obtained.
The obtained green film was obtained in a continuous drying furnace at 170 ° C. for 3 minutes, then heated to 450 ° C. in about 20 seconds and heated at 450 ° C. for 7 minutes. Then, it was cooled to room temperature in 5 minutes, and a brown film having a thickness of 25 μm was slit into a width of 500 mm to obtain a multilayer polyimide film. The thickness ratio of (a) / (b) in this multilayer polyimide film is 0.25 / 1.
Thereafter, a metallized multilayer polyimide film was obtained in the same manner as in Example 1.
After the obtained metallized multilayer polyimide film was processed into a TAB tape pattern having a wiring width of 90 μm, the strength required when peeled off in the 90-degree direction was measured. The results are shown in Table 1.

Example 4
The above polyamic acid solution (1) was coated on a stainless steel belt using a T-type die. The die lip gap was 400 μm. Next, the self-supporting polyamic acid film obtained by drying at 90 ° C. for 60 minutes was peeled from the stainless steel belt to obtain a polyimide precursor film (green film) having a thickness of 36 μm.
The obtained green film was heated in a continuous drying oven at 170 ° C. for 3 minutes, then heated to 450 ° C. in about 20 seconds and heated at 450 ° C. for 7 minutes, and then in 5 minutes. After cooling to room temperature, a brown polyimide film having a thickness of 20 μm was slit into a width of 500 mm to obtain a polyimide film.
The polyamideimide solution (2) was coated again on the obtained polyimide film using a T-type die. The die lip gap was 150 μm. Next, a multilayer polyimide film having a thickness of 40 μm and having a self-supporting property obtained by drying at 90 ° C. for 60 minutes was obtained. The thickness ratio of (a) / (b) in this multilayer polyimide film is 0.25 / 1.
A 35 μm thick copper foil (BHY-22B-T, manufactured by Nikko Materials Co., Ltd.) was laminated on the (a) layer side of the obtained multilayer polyimide film with a laminator.
Then, the (a) layer was hardened by processing at 150 degreeC for 2 hours. Then, the metallized multilayer polyimide film was obtained by cutting this film into 250 mm x 400 mm.
After the obtained metallized multilayer polyimide film was processed into a TAB tape pattern having a wiring width of 90 μm, the strength required when peeled off in the 90-degree direction was measured. The results are shown in Table 1.

(Example 5)
A metallized multilayer polyimide film was obtained in the same manner as in Example 4 using the polyamideimide epoxy mixed resin solution (3) instead of the NMP solution (2).
After the obtained metallized multilayer polyimide film was processed into a TAB tape pattern having a wiring width of 90 μm, the strength required when peeled off in the 90-degree direction was measured. The results are shown in Table 1.

(Example 6)
A metallized multilayer polyimide film was obtained in the same manner as in Example 4 using the polyamideimide epoxy mixed resin solution (4) instead of the NMP solution (2).
After the obtained metallized multilayer polyimide film was processed into a TAB tape pattern having a wiring width of 90 μm, the strength required when peeled off in the 90-degree direction was measured. The results are shown in Table 1.

(Example 7)
The polyamic acid solution (1) was coated on a stainless steel belt using a T-type die. The lip gap of the die was 520 μm. Subsequently, the polyamic acid film having self-supporting property obtained by drying at 90 ° C. for 60 minutes was peeled from the stainless steel belt to obtain a polyimide precursor film (green film) having a thickness of 48 μm.
The obtained green film was heated in a continuous drying oven at 170 ° C. for 3 minutes, then heated to 450 ° C. in about 20 seconds and heated at 450 ° C. for 7 minutes, and then in 5 minutes. After cooling to room temperature, a brown polyimide film having a thickness of 22 μm was slit to a width of 500 mm to obtain a polyimide film.
A solution obtained by diluting the polyamideimide-epoxy mixed resin solution (3) 10 times with DMAC was prepared, and the resulting polyimide film was coated using a bar coater. Next, a multilayer polyimide film having a thickness of 24 μm and having a self-supporting property obtained by drying at 90 ° C. for 10 minutes was obtained. The thickness ratio of (a) / (b) in this multilayer polyimide film is 0.04 / 1. On the (a) layer side of the multilayer polyimide film, a 35 μm thick copper foil (BHY-22B-T, manufactured by Nikko Materials Co., Ltd.) was laminated with a laminator.
Then, (a) layer (adhesive layer) was hardened by processing at 150 ° C for 2 hours. Then, the metallized multilayer polyimide film was obtained by cutting this film into 250 mm x 400 mm.
After the obtained metallized multilayer polyimide film was processed into a TAB tape pattern having a wiring width of 90 μm, the strength required when peeled off in the 90-degree direction was measured. The results are shown in Table 1.

(Comparative Example 1)
The above polyamic acid solution (1) was coated on a stainless steel belt using a T-type die. The lip gap of the die was 650 μm. Subsequently, the polyamic acid film having a self-supporting property obtained by drying at 90 ° C. for 60 minutes was peeled from the stainless steel belt to obtain a polyimide precursor film (green film) having a thickness of 60 μm.
The obtained green film was heated in a continuous drying oven at 170 ° C. for 3 minutes, then heated to 450 ° C. in about 20 seconds and heated at 450 ° C. for 7 minutes, and then in 5 minutes. After cooling to room temperature, a brown polyimide film having a thickness of 30 μm was slit into a width of 500 mm.
Thereafter, a metallized film was obtained in the same manner as in Example 1.
After the obtained metallized polyimide film was processed into a TAB tape pattern having a wiring width of 90 μm, the strength required when peeled off in the 90 ° direction was measured. The results are shown in Table 1.

(Comparative Example 2)
A metallized multilayer polyimide film was obtained in the same manner as in Example 4 except that the polyamideimide epoxy mixed resin solution (5) was used instead of the polyamideimide solution (2).
After the obtained metallized multilayer polyimide film was processed into a TAB tape pattern having a wiring width of 90 μm, the strength required when peeled off in the 90-degree direction was measured. The results are shown in Table 1.

  As described above, the multilayer polyimide film of the present invention comprises (a) a layer of polyamideimide and (b) a layer of at least an aromatic tetracarboxylic acid as a residue of pyromellitic acid and aromatic diamines. It is a multilayer polyimide film in which a polyimide having a diamine residue of oxydianiline (diaminodiphenyl ether) as a residue is laminated, and the linear expansion coefficient in the plane direction of the multilayer polyimide film is 10 to 25 ppm / ° C. A multilayer polyimide film in which the ratio (a) / (b) of the thickness of the (a) layer and the (b) layer is 0.001 to 0.5, and the thickness of the (b) layer is 3 to 50 μm. A specific polyimide film having a linear expansion coefficient in a specific range and excellent in heat resistance is used as a base film (b), and its surface is made of polyamideimide (a). Multilayer polyimide film that retains the properties possessed by the base film (b) by layering and has the surface physical properties possessed by the polyamideimide (a), has excellent heat resistance properties, and a linear expansion coefficient within a specific range When this film is used as a base film, it is a flexible metal laminated board that is excellent in bonding with metal thin films and metal foils at high temperatures, and has no deformation, warpage, or distortion at high temperatures, such as flexible printed circuit boards. As extremely useful.

Claims (6)

The multilayer polyimide film of the structure by which the following (a) layer and (b) layer are laminated | stacked at least.
(A) Layer: polyamideimide,
(B) Layer: A polyimide having at least a pyromellitic acid residue as an aromatic tetracarboxylic acid residue and a diamine residue having an oxydianiline skeleton as an aromatic diamine residue.   The multilayer polyimide film according to claim 1, wherein the multilayer polyimide film has a three-layer structure of (a) / (b) / (a).   The multilayer polyimide film according to claim 1 or 2, wherein the polyamideimide of the layer (a) is a polyamideimide composition comprising 1% by mass to 30% by mass of an epoxy resin in terms of solid content.   The ratio (a) / (b) of the thickness of the (a) layer and the (b) layer is 0.001 to 0.5, and the thickness of the (b) layer is 3 to 50 μm. 4. The multilayer polyimide film according to any one of 3.   The multilayer polyimide film according to any one of claims 1 to 4, wherein the multilayer polyimide film has a linear expansion coefficient in the plane direction of 10 to 25 ppm / ° C.   The method for producing a multilayer polyimide film according to claim 1, comprising a step of co-casting a polyimide precursor solution having a solution viscosity of 10 Pa · s to 5000 Pa · s and a polyamideimide solution having a solution viscosity of 1 Pa · s to 500 Pa · s.