JP2007105955A - Laminated polyimide film and its production method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laminated polyimide film in which a reinforcing backing film having proper strength when a flexible printed circuit or the like is processed/produced, dimensional stability by thermal deformation, and peelability is laminated, and a thin functional film such as copper is formed on the other surface. <P>SOLUTION: In a method for producing the laminated polyimide film, a polyimide film of 0.5-10μm thick in which the reinforcing backing film is laminated on one surface is used, and a thin functional film layer is formed on the other surface different from the surface on which the backing film for reinforcing the polyimide film is laminated. In the laminated polyimide film obtained by these methods, the thin functional film layer is formed on the other different surface of the polyimide film of 0.5-10 μm in thickness on which the reinforcing backing film is laminated. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention is a reinforcing backing suitable for handling an ultra-thin polyimide film used in processing / manufacturing of a flexible printed circuit (hereinafter referred to as FPC) and having appropriate rigidity, thermal dimensional stability, and peelability. The present invention relates to a laminated polyimide film in which a functional thin film layer such as copper is formed on a polyimide film on which a film is laminated, and a method for producing the same.

Along with technological advances in electronic devices such as mobile phones, the demand for build-up layers of multilayer substrates using FPC (Flexible Printed Circuit) TAB, COF, and films is growing rapidly. In response to light weight and high density wiring, thinning of FPC and the like is progressing. For this reason, thinning of the FPC copper-clad film (FCL) is also progressing at the same time, but this reduces the rigidity of the film itself and makes it difficult to process FPC and FCL.
As a method for improving workability when manufacturing an FPC, a method of giving rigidity as a whole by attaching an FPC reinforcing film in advance is used. At that time, a slightly tacky reinforcing film that can be easily handled at the time of processing and can be peeled and removed after the processing is finished is used. Conventionally, acrylic or rubber adhesive sheets have been used for this purpose, but these sheets have high adhesive strength, and the adhesive strength varies significantly with temperature and pressure. There were cases where it could not be used depending on the conditions.
For example, in a flexible laminate with metal foil on only one side, coexistence of metal foil, thermoplastic polyimide layer, non-thermoplastic polyimide layer, and imidization accelerator to prevent warpage and decrease in production efficiency A flexible laminate (see Patent Document 1) obtained by laminating a polyimide resin backing layer obtained by converting the polyamic acid below in this order, polyester (A) and polyimide ( B), a polyester film for reinforcement having a thermal shrinkage rate of 0.25% or less and a thermal expansion coefficient of 13 × 10 ⁻⁶ / ° C. or more and 50 × 10 ⁻⁶ / ° C. or less (see Patent Document 2). Proposed.
JP 2005-186274 A JP 2003-101166 A

  Moreover, in the process of creating FCL, although it differs in FCL by casting on a copper foil, with regard to other production methods, handling of a thin film particularly in roll-to-roll is mostly performed. Examples include copper thin film deposition, plating, or adhesive application, copper foil lamination, thermocompression bonding, and pressing by sputtering. For this reason, it becomes necessary to convey a thin film without wrinkles, distortion, or rubbing. Particularly in the sputtering process, it is necessary to transport the film in a vacuum. Since there is no air layer between the film and the transport roll, the friction also changes, making it difficult to transport properly without wrinkles and distortion and rubbing with the roll. In addition, since the plating process is performed in the liquid, the conditions are also different from those in the air, and it is difficult to use an appropriate carrier wave without wrinkles, distortion, and rubbing.

  The present invention is a reinforcing backing film having suitable rigidity, thermal dimensional stability, and peelability suitable for handling an ultrathin polyimide film used in processing / manufacturing of a flexible printed circuit (hereinafter referred to as FPC). The present invention provides a laminated polyimide film in which a functional thin film layer is formed on a polyimide film on which is laminated, and a method for producing the same.

That is, this invention consists of the following structures.
1. A laminated polyimide film, wherein a functional thin film layer is formed on the other surface of a polyimide film having a thickness of 0.5 μm to 10 μm in which a reinforcing backing film is laminated on one side.
2. 2. The laminated polyimide film as described in 1 above, wherein the polyimide film is a polyimide film mainly composed of polyimide benzoxazole obtained by condensation of aromatic tetracarboxylic acids and diamines having a benzoxazole structure.
3. 3. The laminated polyimide film as described in 1 or 2 above, wherein the functional thin film layer is a copper thin film layer.
4). Using a polyimide film with a thickness of 0.5 μm to 10 μm with a reinforcing backing film laminated on one side, a functional thin film layer is formed on the other side different from the side on which the reinforcing backing film of the polyimide film is laminated A method for producing a laminated polyimide film, comprising:
5. 5. The method for producing a laminated polyimide film as described in 4 above, wherein the polyimide film is a polyimide film mainly composed of polyimide benzoxazole obtained by condensation of aromatic tetracarboxylic acids and diamines having a benzoxazole structure.
6). 6. The method for producing a laminated polyimide film according to 4 or 5, wherein the functional thin film layer is a copper thin film layer.

  In the present invention, a laminated polyimide film in which a reinforcing backing film is laminated and a functional thin film is laminated on the other side is laminated with a thin film such as a copper thin film on the opposite side of the surface on which the polyimide backing film is laminated. When forming or handling the film of the present invention in various processes, wrinkles, distortion, and rubbing are unlikely to occur, and when necessary, the polyimide film is also wrinkled and distorted when the reinforcing backing film is peeled off from the laminated polyimide film. Insulation reliability and lightness (light thinness) are reduced by using polyimide that has a higher level of heat resistance, flexibility, and mechanical strength and has a thickness less than a certain thickness as an insulating layer. This is industrially very significant as a functional film capable of dealing with fine, light, short and thin electrical components such as thin FPC.

The laminated polyimide film of the present invention is a polyimide film whose main constituent component is a polyimide film having a thickness of 0.5 μm to 10 μm. The thickness of this polyimide film needs to be 10 μm or less and 0.5 μm or more. If the thickness is less than 5 μm, there will be many problems in terms of handling difficulties such as generation of wrinkles and distortion and securing insulation when the laminated polyimide film of the present invention is produced by laminating a reinforcing backing film. In the case of exceeding 10 μm, it is possible in many cases even if a conventional general apparatus is used for transport without a backing film, and it is less effective for lightening.
The laminated polyimide film of the present invention is a polyimide film having a thickness of 0.5 μm to 10 μm as a main constituent polyimide film, and the tensile elastic modulus of the polyimide film is preferably 6 GPa or more, and a thin film in a predetermined range Is less than 6 GPa from the viewpoint of handling a thin film in the process of laminating and laminating and laminating a backing film for reinforcement.
The tensile modulus of the polyimide film is 6 GPa or more, preferably 7 GPa or more, and more preferably 8 GPa or more. The upper limit of the tensile elastic modulus of the polyimide film in the present invention is not particularly limited, but is about 30 GPa from the viewpoint of maintaining the minimum flexibility in handling.
In addition, the polyimide film preferably has a linear expansion coefficient (CTE) of 0 to 10 ppm / ° C., is free from distortion and wrinkles when exposed to high temperatures such as soldering, and has a small deviation from the linear expansion coefficient of the thin film. Thus, the effect of preventing the peeling of the thin film does not occur. When deviating from this range, the above effect reduction becomes large.

The most preferred embodiment of the polyimide film used in the present invention is mainly composed of polyimide benzoxazole obtained by reacting (aromatic) diamines having a benzoxazole structure with aromatic tetracarboxylic acids. .
The polyimide film used in the present invention was subjected to a ring-opening polyaddition reaction of diamines and aromatic tetracarboxylic acids in a solvent to obtain a polyamic acid solution, and then a green film was formed from the polyamic acid solution. It can be obtained later by dehydration condensation (imidization).
Although the polyimide film in this invention is not specifically limited, The combination of the following aromatic diamine and aromatic tetracarboxylic acid (anhydride) is mentioned as a preferable example.
A. A combination of an aromatic diamine having a benzoxazole structure and an aromatic tetracarboxylic acid.
B. A combination of an aromatic diamine having a diaminodiphenyl ether skeleton and an aromatic tetracarboxylic acid having a pyromellitic acid skeleton.
C. A combination of an aromatic diamine having a phenylenediamine skeleton and an aromatic tetracarboxylic acid having a biphenyltetracarboxylic acid skeleton.
D. A combination of one or more of the above ABCs.
Among these, A. A polyimide film comprising a combination of a diamine having a benzoxazole structure and an aromatic tetracarboxylic acid is preferred.
Examples of aromatic diamines having a benzoxazole structure that can be most preferably used in the present invention include the following compounds.

  Benzoxazole used for a polyimide film mainly composed of polyimide benzoxazole obtained by reacting (aromatic) diamine having a benzoxazole structure with aromatic tetracarboxylic acids, which is the most preferred embodiment of the present invention Specific examples of the aromatic diamine having a structure include the following.

Among these, amino (aminophenyl) benzoxazole isomers are preferable from the viewpoint of ease of synthesis. Here, “each isomer” refers to each isomer in which two amino groups of amino (aminophenyl) benzoxazole are determined according to the coordination position (eg, the above “formula 1” to “formula 4”). Each compound described in the above. These diamines may be used alone or in combination of two or more.
In the present invention, it is preferable to use 70 mol% or more of the aromatic diamine having the benzoxazole structure.

The present invention is not limited to the above items, and the following aromatic diamines may be used. Preferably, the diamines do not have the benzoxazole structure exemplified below as long as the total aromatic diamine is less than 30 mol%. Is a polyimide film using one or two or more in combination.
Examples of such diamines include 4,4′-bis (3-aminophenoxy) biphenyl, bis [4- (3-aminophenoxy) phenyl] ketone, and 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, m-phenylenediamine, o-phenylenediamine, p-phenylenediamine, m-aminobenzylamine, p-aminobenzylamine,

3,3'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl ether, 3,3'-diaminodiphenyl sulfide, 3,3'-diaminodiphenyl 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-Bi [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,

1,1-bis [4- (4-aminophenoxy) phenyl] butane, 1,3-bis [4- (4-aminophenoxy) phenyl] butane, 1,4-bis [4- (4-aminophenoxy) Phenyl] butane, 2,2-bis [4- (4-aminophenoxy) phenyl] butane, 2,3-bis [4- (4-aminophenoxy) phenyl] butane, 2- [4- (4-aminophenoxy) Phenyl] -2- [4- (4-aminophenoxy) -3-methylphenyl] propane, 2,2-bis [4- (4-aminophenoxy) -3-methylphenyl] propane, 2- [4- ( 4-aminophenoxy) phenyl] -2- [4- (4-aminophenoxy) -3,5-dimethylphenyl] propane, 2,2-bis [4- (4-aminophenoxy) -3,5-dimethylphen Le] propane, 2,2-bis [4- (4-aminophenoxy) phenyl] -1,1,1,3,3,3-hexafluoropropane,

1,4-bis (3-aminophenoxy) benzene, 1,3-bis (3-aminophenoxy) benzene, 1,4-bis (4-aminophenoxy) benzene, 4,4′-bis (4-aminophenoxy) ) Biphenyl, bis [4- (4-aminophenoxy) phenyl] ketone, bis [4- (4-aminophenoxy) phenyl] sulfide, bis [4- (4-aminophenoxy) phenyl] sulfoxide, bis [4- ( 4-aminophenoxy) phenyl] sulfone, bis [4- (3-aminophenoxy) phenyl] ether, bis [4- (4-aminophenoxy) phenyl] ether, 1,3-bis [4- (4-aminophenoxy) ) Benzoyl] benzene, 1,3-bis [4- (3-aminophenoxy) benzoyl] benzene, 1,4-bis [4- (3 Aminophenoxy) benzoyl] benzene, 4,4′-bis [(3-aminophenoxy) benzoyl] benzene, 1,1-bis [4- (3-aminophenoxy) phenyl] propane, 1,3-bis [4- (3-aminophenoxy) phenyl] propane, 3,4'-diaminodiphenyl sulfide,

2,2-bis [3- (3-aminophenoxy) phenyl] -1,1,1,3,3,3-hexafluoropropane, bis [4- (3-aminophenoxy) phenyl] methane, 1,1 -Bis [4- (3-aminophenoxy) phenyl] ethane, 1,2-bis [4- (3-aminophenoxy) phenyl] ethane, bis [4- (3-aminophenoxy) phenyl] sulfoxide, 4,4 '-Bis [3- (4-aminophenoxy) benzoyl] diphenyl ether, 4,4'-bis [3- (3-aminophenoxy) benzoyl] diphenyl ether, 4,4'-bis [4- (4-amino-α) , Α-dimethylbenzyl) phenoxy] benzophenone, 4,4′-bis [4- (4-amino-α, α-dimethylbenzyl) phenoxy] diphenylsulfone, bis 4- {4- (4-aminophenoxy) phenoxy} phenyl] sulfone, 1,4-bis [4- (4-aminophenoxy) phenoxy-α, α-dimethylbenzyl] benzene, 1,3-bis [4- (4-aminophenoxy) phenoxy-α, α-dimethylbenzyl] benzene, 1,3-bis [4- (4-amino-6-trifluoromethylphenoxy) -α, α-dimethylbenzyl] benzene, 1,3 -Bis [4- (4-amino-6-fluorophenoxy) -α, α-dimethylbenzyl] benzene, 1,3-bis [4- (4-amino-6-methylphenoxy) -α, α-dimethylbenzyl Benzene, 1,3-bis [4- (4-amino-6-cyanophenoxy) -α, α-dimethylbenzyl] benzene,

3,3′-diamino-4,4′-diphenoxybenzophenone, 4,4′-diamino-5,5′-diphenoxybenzophenone, 3,4′-diamino-4,5′-diphenoxybenzophenone, 3, 3'-diamino-4-phenoxybenzophenone, 4,4'-diamino-5-phenoxybenzophenone, 3,4'-diamino-4-phenoxybenzophenone, 3,4'-diamino-5'-phenoxybenzophenone, 3,3 '-Diamino-4,4'-dibiphenoxybenzophenone, 4,4'-diamino-5,5'-dibiphenoxybenzophenone, 3,4'-diamino-4,5'-dibiphenoxybenzophenone, 3,3'- Diamino-4-biphenoxybenzophenone, 4,4′-diamino-5-biphenoxybenzophenone, 3,4 -Diamino-4-biphenoxybenzophenone, 3,4'-diamino-5'-biphenoxybenzophenone, 1,3-bis (3-amino-4-phenoxybenzoyl) benzene, 1,4-bis (3-amino- 4-phenoxybenzoyl) benzene, 1,3-bis (4-amino-5-phenoxybenzoyl) benzene, 1,4-bis (4-amino-5-phenoxybenzoyl) benzene, 1,3-bis (3-amino) -4-biphenoxybenzoyl) benzene, 1,4-bis (3-amino-4-biphenoxybenzoyl) benzene, 1,3-bis (4-amino-5-biphenoxybenzoyl) benzene, 1,4-bis (4-Amino-5-biphenoxybenzoyl) benzene, 2,6-bis [4- (4-amino-α, α-dimethylbenzyl) pheno Si] benzonitrile and 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 alkyl groups or alkoxyl group hydrogen atoms. Examples thereof include aromatic diamines substituted with a halogenated alkyl group having 1 to 3 carbon atoms, partially or entirely substituted with halogen atoms, or alkoxyl groups.

  The aromatic tetracarboxylic acids used in the present invention are, for example, aromatic tetracarboxylic anhydrides. Specific examples of the aromatic tetracarboxylic acid anhydrides include the following.

These tetracarboxylic dianhydrides may be used alone or in combination of two or more.
In the present invention, one or two or more non-aromatic tetracarboxylic dianhydrides exemplified below may be used in combination as long as they are less than 30 mol% of the total tetracarboxylic dianhydrides. Examples of such tetracarboxylic acid anhydrides include butane-1,2,3,4-tetracarboxylic dianhydride, pentane-1,2,4,5-tetracarboxylic dianhydride, and cyclobutanetetracarboxylic acid. Acid dianhydride, cyclopentane-1,2,3,4-tetracarboxylic dianhydride, cyclohexane-1,2,4,5-tetracarboxylic dianhydride, cyclohex-1-ene-2,3 5,6-tetracarboxylic dianhydride, 3-ethylcyclohex-1-ene-3- (1,2), 5,6-tetracarboxylic dianhydride, 1-methyl-3-ethylcyclohexane-3 -(1,2), 5,6-tetracarboxylic dianhydride, 1-methyl-3-ethylcyclohex-1-ene-3- (1,2), 5,6-tetracarboxylic dianhydride 1-ethylcyclohexane -(1,2), 3,4-tetracarboxylic dianhydride, 1-propylcyclohexane-1- (2,3), 3,4-tetracarboxylic dianhydride, 1,3-dipropylcyclohexane- 1- (2,3), 3- (2,3) -tetracarboxylic dianhydride, dicyclohexyl-3,4,3 ′, 4′-tetracarboxylic dianhydride,

Bicyclo [2.2.1] heptane-2,3,5,6-tetracarboxylic dianhydride, 1-propylcyclohexane-1- (2,3), 3,4-tetracarboxylic dianhydride, 1 , 3-Dipropylcyclohexane-1- (2,3), 3- (2,3) -tetracarboxylic dianhydride, dicyclohexyl-3,4,3 ′, 4′-tetracarboxylic dianhydride, bicyclo [2.2.1] Heptane-2,3,5,6-tetracarboxylic dianhydride, bicyclo [2.2.2] octane-2,3,5,6-tetracarboxylic dianhydride, bicyclo [2.2.2] Oct-7-ene-2,3,5,6-tetracarboxylic dianhydride and the like. These tetracarboxylic dianhydrides may be used alone or in combination of two or more.

  The solvent used when polyamic acid is obtained by polycondensation (polymerization) of the diamines and aromatic tetracarboxylic acids (anhydrides) is one that dissolves both the raw material monomer and the resulting polyamic acid. Is not particularly limited, but a polar organic solvent is preferable, for example, N-methyl-2-pyrrolidone, N-acetyl-2-pyrrolidone, N, N-dimethylformamide, N, N-diethylformamide, N, N- Examples thereof include dimethylacetamide, dimethyl sulfoxide, hexamethylphosphoric amide, ethyl cellosolve acetate, diethylene glycol dimethyl ether, sulfolane, and halogenated phenols. These solvents can be used alone or in combination. The amount of the solvent used may be an amount sufficient to dissolve the monomer as a raw material. As a specific amount used, the mass of the monomer in the solution in which the monomer is dissolved is usually 5 to 40% by mass, The amount is preferably 10 to 30% by mass.

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 3.0 dl / g or more, and more preferably 4.0 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.

  As an imidization method by high-temperature treatment, a conventionally known imidation reaction can be appropriately used. For example, using a polyamic acid solution that does not contain a ring-closing catalyst or a dehydrating agent, the imidization reaction proceeds by subjecting it to a heat treatment (so-called thermal ring-closing method), or a polycyclic acid solution containing a ring-closing catalyst and a dehydrating agent In particular, a chemical ring closing method in which an imidization reaction is performed by the action of the above ring closing catalyst and a dehydrating agent can be given.

  100-500 degreeC is illustrated as a heating maximum temperature of a thermal ring closure method, Preferably it is 200-480 degreeC. When the maximum heating temperature is lower than this range, it is difficult to close the ring sufficiently, and when it is higher than this range, the deterioration proceeds and the composite tends to become brittle. A more preferable embodiment includes a two-stage heat treatment in which treatment is performed at 150 to 250 ° C. for 3 to 20 minutes and then treatment at 350 to 500 ° C. for 3 to 20 minutes.

The reinforcing backing film used in the present invention is not particularly limited as long as the heat resistance, mechanical strength, etc., such as polyimide film, polyester film, acetate film, polyolefin and aluminum foil are above a certain level. .
Among these films, the adhesive strength with the polyimide film is adhered to the reinforcing backing film so that the adhesive strength with the polyimide film is 1.0 N / 20 mm or less via the adhesive layer. A film having a functioning adhesive layer is preferable. The adhesive strength of the adhesive layer is more preferably 0.5 N / 20 mm or less.
Further, for the purpose of the present invention, the reinforcing backing film has a water absorption of 0.5% or less, and its linear expansion coefficient is 50 ppm / ° C. or less, more preferably 30 ppm / ° C. or less.

The thickness of the reinforcing backing film used in the present invention is not limited, but a polyimide film or a polyester film having a thickness of about 12 μm to 200 μm is preferable from the gist of the present invention. More preferably, the adhesive having the above-mentioned adhesive function having high heat resistance to these films. For example, those in which a layer of vinyl chloride, acrylic or urethane adhesive is formed are preferred.
For example, a laminated polyimide film can be produced such that a reinforcing backing film is laminated on a polyimide film via this adhesive layer by pressure welding or thermocompression bonding.

  As the functional thin film layer in the present invention, an oxide thin film such as ITO (indium tin oxide), a metal thin film such as copper, gold, silver, chromium, titanium, aluminum, a semiconductor thin film such as silicon, germanium, These composite films and laminated films can be mentioned, among which a thin film containing copper as a main component can be preferably applied. Thus, when copper is the main component, a copper thin film containing a trace amount of other elements, or between a film and a copper thin film, Cr, Ni, Mo, Ti, Ta, V, a thin film, and these Alloy thin films, oxides of these metals, ITO, Si, Al and the like, and composite oxide thin films sandwiched between them as an underlayer. The thin film forming method is not particularly limited, but dry thin film forming methods such as vapor deposition and sputtering are preferably applicable.

(Tensile modulus, tensile breaking strength and tensile breaking elongation of polyimide film)
In the present invention, the tensile modulus, tensile breaking strength and tensile breaking elongation of the polyimide film were measured by the following methods.
A test piece was prepared by cutting a polyimide film to be measured into a strip of 100 mm × 10 mm in the flow direction (hereinafter also referred to as MD direction) and the width direction (hereinafter also referred to as TD direction). Using a tensile tester (manufactured by Shimadzu Corp., Autograph (registered trademark) model name AG-5000A) under the conditions of a tensile speed of 50 mm / min and a distance between chucks of 40 mm, the tensile modulus and tension in each of the MD and TD directions. The breaking strength and tensile breaking elongation were measured.

(Melting point of polyimide film, glass transition temperature)
Moreover, melting | fusing point and glass transition temperature of the polyimide film were measured with the following method.
The polyimide film to be measured was subjected to differential scanning calorimetry (DSC) under the following conditions, and the melting point (melting peak temperature Tpm) and glass transition point (Tmg) were determined in accordance with JIS K7121.
Device name: DSC3100S manufactured by MAC Science
Pan ： Aluminum pan (non-airtight)
Sample mass: 4mg
Temperature rising start temperature: 30 ° C
Temperature rising end temperature: 600 ° C
Temperature increase rate: 20 ° C / min
Atmosphere; Argon Atmosphere; Argon

(Linear expansion coefficient of polyimide film)
The linear expansion coefficient (CTE) of the polyimide film was measured by the following method.
For the polyimide film to be measured, the stretch rate in the MD direction and 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.,. 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).
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

(Water absorption of film)
The water absorption rate of the film is determined by cutting the film into about 10 cm × 10 cm, drying the test piece in a dry oven at 150 ° C. for 1 hour, measuring the mass immediately after that, and then setting the initial value, then the ion at 25 ° C. The test piece was placed in the exchange water for 24 hours, and then water droplets on the surface were sufficiently wiped off and reweighed to obtain the water absorption value. The water absorption was determined from the following formula.
Water absorption rate = 100 × (water absorption value−initial value) / (initial value) [mass%]

  EXAMPLES Hereinafter, although an Example and a comparative example are shown and this invention is demonstrated more concretely, this invention is not limited by a following example. In addition, the evaluation method of the physical property in a following example is as follows except having mentioned above.

1. Reduced viscosity of polyamic acid (ηsp / C)
A solution dissolved in N-methyl-2-pyrrolidone (or N, N-dimethylacetamide) so that the polymer concentration was 0.2 g / dl was measured at 30 ° C. with an Ubbelohde type viscosity tube. (When the solvent used for preparing the polyamic acid solution was N, N-dimethylacetamide, the polymer was dissolved using N, N-dimethylacetamide and measured.)

2. The thickness of the polyimide film and the laminated polyimide film The thickness was measured using a micrometer (Minetron 1254D, manufactured by Finelfu).

3. Judgment of film swelling Visually confirmed whether there were air bubbles or cavities between the adhesive layer of the reinforcing backing film and the polyimide film.

4). Judgment of adhesive layer transfer After peeling off the reinforcing backing film, visually determine whether the adhesive layer has completely moved to the reinforcing backing film side, and the adhesive layer has completely moved to the reinforcing backing film side. ○, the case where the adhesive layer was not completely transferred to the reinforcing backing film side but remained on the polyimide film side was evaluated as x.

5. Judgment of peeled condition When the reinforcing backing film is peeled off, the polyimide film is visually checked for abnormalities such as wrinkles and distortion, and those with almost no abnormalities such as wrinkles and distortion are found. A case where a slight abnormality was observed was evaluated as x, and a case where a large amount of abnormality such as Δ, wrinkles and distortion was observed.
6). Adhesive strength Measured according to JIS Z-0237 at a tensile speed of 300 mm / min and a peeling angle of 180 °.

[Reference Example 1]
The nitrogen inlet tube, the thermometer, the wetted part of the vessel equipped with the stirring rod, and the infusion pipe were replaced with nitrogen in the reaction vessel made of austenitic stainless steel SUS316L, and then 5-amino-2- (p-aminophenyl) ) Snowtex (registered trademark) DMAC-ST30 (Nissan Chemical Co., Ltd.) obtained by adding 223 parts by mass of benzoxazole and 4416 parts by mass of N, N-dimethylacetamide and completely dissolving it, and then dispersing colloidal silica in dimethylacetamide 40.5 parts by mass (including 8.1 parts by mass of silica) and 217 parts by mass of pyromellitic dianhydride are added and stirred at a reaction temperature of 25 ° C. for 24 hours. A was obtained. Ηsp / C of this product was 4.0 dl / g.

[Reference Example 2]
(Preparation of polyamic acid solution)
The liquid contact part of the vessel equipped with a nitrogen introduction tube, a thermometer, a stirring rod, and the pipe for infusion were substituted with nitrogen in the reaction vessel made of austenitic stainless steel SUS316L, and then 200 parts by mass of diaminodiphenyl ether was added. Next, 4170 parts by mass of N-methyl-2-pyrrolidone was added and completely dissolved, and then Snowtex (registered trademark) DMAC-ST30 (manufactured by Nissan Chemical Industries, Ltd.) in which colloidal silica was dispersed in dimethylacetamide. When 40.5 parts by mass (including 8.1 parts by mass of silica) and 217 parts by mass of pyromellitic dianhydride are added and stirred at 25 ° C. for 5 hours, a brown viscous polyamic acid solution B is obtained. Obtained. The reduced viscosity (ηsp / C) was 3.7 dl / g.

[Reference Example 3]
(Preliminary dispersion of inorganic particles)
(Preparation of polyamic acid solution)
The wetted part of the vessel equipped with a nitrogen introduction tube, a thermometer, and a stirring rod, and the infusion piping were substituted with nitrogen in the reaction vessel made of austenitic stainless steel SUS316L, and then 108 parts by mass of phenylenediamine was added. Next, Snowtex (registered trademark) DMAC-ST30 (manufactured by Nissan Chemical Industries, Ltd.), in which 4010 parts by mass of N-methyl-2-pyrrolidone is added and completely dissolved, and then colloidal silica is dispersed in dimethylacetamide. When 40.5 parts by mass (including 8.1 parts by mass of silica) and 292.5 parts by mass of diphenyltetracarboxylic dianhydride are added and stirred at 25 ° C. for 12 hours, a brown viscous polyamic acid solution C was obtained. The reduced viscosity (ηsp / C) was 4.5 dl / g.

[Production Example 1]
The polyamic acid solution A obtained in Reference Example 1 was coated on the non-lubricant surface of polyethylene terephthalate film A-4100 (manufactured by Toyobo Co., Ltd.) using a comma coater (gap: 150 μm, coating width: 1240 mm). ), And dried at 90 ° C. for 60 minutes. The polyamic acid film that became self-supporting after drying was peeled from the support and cut at both ends to obtain a green film having a thickness of 10 μm and a width of 1200 mm.
A pin sheet in which pins made of carbon steel (height 10 mm) are implanted so that the obtained green film has an inclination angle of 3 to 13 degrees in the lateral direction of film conveyance, and a connex with a thickness of 0.5 mm ( Using a pin tenter having a brush roll obtained by winding a unit brush manufactured by Nihon Unit Co., Ltd., which has a hair material made of (registered trademark) as a film pusher, the green film is projected onto the pin and gripped. The heat treatment was performed.
The heat treatment settings for the tenter are as follows. The first stage was heated at 200 ° C. for 5 minutes and the heating rate was 4 ° C./second, and the second stage was heated at 450 ° C. for 5 minutes under two conditions to proceed the imidization reaction. The maximum wind speed in the tenter was 0.5 m / sec.
Up to the midpoint of the first stage of the tenter, the width of the pins at both ends was reduced by 2% to 98% of the initial width. In the second half of the first stage, the pin width is slightly widened to 99% of the initial width, expanded to 102% in the temperature rise interval, and further expanded to the middle point of the second stage to 103%, and thereafter constant Processed in width. Then, it cooled to room temperature in 5 minutes, the part where the flatness of the both ends of a film was bad was cut off with the slitter, and it rolled up in roll shape, and obtained polyimide film A1 which exhibits brown.
Similarly, polyimide films A2, A3 and A4 having various thicknesses were obtained. The physical properties of the obtained film are shown in Table 1.

[Production Example 2]
Using the polyamic acid solution B obtained in Reference Example 2, the same procedure was followed to obtain a polyimide film B. The physical properties of the obtained film are shown in Table 1.

[Production Example 3]
Using the polyamic acid solution C obtained in Reference Example 3, the same procedure was followed to obtain a polyimide film C. The physical properties of the obtained film are shown in Table 1.

[Examples 1 to 4]
Polyimide films A1 to C of each production example were used, and a polyester film having a release sheet of 43 μm using an acrylic pressure-sensitive adhesive layer as a backing film for reinforcement (water absorption 0.35%, linear expansion coefficient 14 ppm / The adhesive layer and one surface of the polyimide film were bonded together while peeling the release sheet in a clean room. At the time of this bonding, no problem occurred in each example.
Each reinforcing backing film laminated polyimide film thus obtained was put into a roll-to-roll sputtering machine, and sputtering was performed on the side where the reinforcing backing film was not attached.
In sputtering, a NiCr thin film of 20 nm was formed as an underlayer, and a copper thin film of 200 nm was formed thereon. Table 2 shows the results of evaluation of each metallized laminated polyimide film obtained. What used the film of A4 cannot be said to have a big effect on lightness (lightness thinning).

[Examples 5 to 8]
Polyimide films A1 to C of each reference example are used, and a polyester film release sheet using various adhesive layers as a reinforcing backing film (thickness 30 to 50 μm, adhesive strength 0.1 to 0.5 N) / 20 mm, water absorption 0.35 to 0.45%, linear expansion coefficient 13 to 18 ppm / ° C.) using various commercial products, while peeling the release sheet in a clean room, Were pasted together. At the time of this bonding, no problem occurred in each example.
Each reinforcing backing film laminated polyimide film thus obtained was put into a roll-to-roll sputtering machine, and sputtering was performed on the side where the reinforcing backing film was not attached.
In sputtering, a NiCr thin film of 20 nm was formed as an underlayer, and a copper thin film of 200 nm was formed thereon. Each metallized laminated polyimide film obtained was evaluated. The results are shown in Table 2.
[Comparative example]
As a comparative example, the polyimide films A1 to C of the reference example were used, and the sputtering film was put in a roll-to-roll sputtering machine without attaching the reinforcing backing film.
In sputtering, a NiCr thin film of 20 nm was formed as an underlayer, and a copper thin film of 200 nm was formed thereon. At this time, all the films did not run well, wrinkles occurred when the film was fed, and film bulging occurred at the wrinkles. In addition, instability of film running along the way occurred.

  As described above, the functional thin film forming laminated polyimide film in which the functional thin film layer is formed on the other surface of the polyimide film on which the reinforcing backing film of the present invention is laminated is an extremely thin polyimide film. However, it is difficult to cause wrinkles and distortion during handling such as when forming a thin film, has a high elastic modulus and sufficient mechanical strength for practical use, and is a substrate material for ultra-thin multilayer wiring boards with high durability and insulation. It can be applied widely, and has great industrial value.

Claims (6)

  A functional thin film layer is formed on the other side of the polyimide film having a thickness of 0.5 μm to 10 μm with the reinforcing backing film laminated on one side (the side opposite to the side on which the reinforcing backing film is laminated). A feature of laminated polyimide film.   The laminated polyimide film according to claim 1, wherein the polyimide film is a polyimide film mainly composed of polyimide benzoxazole obtained by condensation of an aromatic tetracarboxylic acid and a diamine having a benzoxazole structure.   The laminated polyimide film according to claim 1 or 2, wherein the functional thin film layer is a thin film layer containing copper as a main component.   Using a polyimide film with a thickness of 0.5 μm to 10 μm with a reinforcing backing film laminated on one side, a functional thin film layer is formed on the other side different from the side on which the reinforcing backing film of the polyimide film is laminated A method for producing a laminated polyimide film, comprising:   The method for producing a laminated polyimide film according to claim 4, wherein the polyimide film is a polyimide film mainly composed of polyimide benzoxazole obtained by condensation of an aromatic tetracarboxylic acid and a diamine having a benzoxazole structure.   The method for producing a laminated polyimide film according to claim 4 or 5, wherein the functional thin film layer is a copper thin film layer.