JP2000034556A - Formation of metal thin layer on polyimide film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for forming a metal thin film on a polyimide film, which enables a good adhesion of the metal thin film to the polyimide film. SOLUTION: The method for forming a metal thin film on a polyimide is comprised of the indispensable steps of (1) coating a photosensitive polyimide precursor on a substrate and drying, (2) exposing the resulting polyimide precursor according to the prescribed pattern and developing, (3) heating the substrate coated with the photosensitive polyimide precursor, (4) subjecting the resulting substrate coated with the photosensitive polyimide precursor to electric discharge treatment and (5) forming the metal thin film on the surface of the treated polyimide film, and the electric discharge treatment is carried out under a gaseous atmosphere containing at least one selected from oxygen or fluorinated compounds or under a mixed gaseous atmosphere selected from these gases.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a thin metal film on a polyimide film for firmly bonding the thin metal film on the polyimide film.

[0002]

2. Description of the Related Art Conventionally, a photosensitive polyimide precursor varnish includes a composition comprising a polymer containing polyamic acid as a main component, an amine compound having a carbon-carbon double bond, and a sensitizer added if necessary. A photosensitive polyimide precursor composition in which a photosensitive group is introduced into an acid by an ester group, a composition in which a photosensitive auxiliary having a photopolymerizable functional group is added to a polyimide precursor in which a photosensitive group is introduced into a polymer terminal, a polyimide precursor A composition which is sensitized by adding a 4- (2'-nitrophenyl) -4-hydropyridine derivative to the same is known. This material is used in the form of a varnish dissolved in an organic solvent. This varnish is applied to a substrate and dried to form a film, which is then irradiated with ultraviolet light through an appropriate photomask, developed and rinsed to obtain a desired relief pattern, and further heat-treated to have high heat resistance. A relief pattern of the photosensitive polyimide film can be formed. When forming a metal thin film for forming conductor wiring on the formed relief pattern, adhesion between the polyimide film and the metal thin film becomes a problem. In particular, when the polyimide film is a composition having a low coefficient of linear expansion, it is difficult to secure adhesion. Until now, various surface treatment methods have been studied to ensure adhesion, but stable and strong adhesion is ensured because unevenness in the treated surface is likely to occur or a sufficient adhesion effect does not occur. There was a need for a processing method that could be used.

[0003]

SUMMARY OF THE INVENTION The present invention has been made in view of the drawbacks of the prior art.
An object of the present invention is to provide a method for forming a metal thin film on a polyimide film which solves the above-mentioned problems and provides a strong and stable adhesiveness between the polyimide film and the metal thin film.

[0004]

The present invention provides: (1) a step of applying a photosensitive polyimide precursor on a substrate and drying; (2) a step of exposing and developing a pattern; and (3) a step of photosensitive polyimide. A step of performing a heat treatment on the substrate coated with the precursor; (4) a step of performing a discharge treatment after the heat treatment; and (5) a step of forming a metal thin film on the surface of the treated polyimide film. A method of forming a metal thin film on a polyimide film, wherein the method is performed in a gas atmosphere containing at least one of the system compounds or in a mixed gas atmosphere selected from these gases.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail. The polymer having the structural unit represented by the general formula (1) as a main component used in the present invention is the easiest to produce among those represented by the following general formula (2), and is excellent in pattern processability and film properties. However, a polymer obtained by adding a photosensitizer, an initiator, and a sensitizer as needed to a polymer having a structural unit represented by the general formula (2) as a main component can be used without any problem.

[0006]

Embedded image R1 is trivalent or tetravalent having at least 2 carbon atoms
Valent organic group, R2 represents a divalent organic group having at least 2 carbon atoms, R3 represents a hydroxyl group, -OR ^4, -N
HR ⁴ represents a group selected from —O ^— N ⁺ R ⁴ R ⁵ R ⁶ R ⁷ .
Here, R ⁴ represents at least one group having an ethylenically unsaturated bond, and R ⁵ , R ⁶ , and R ⁷ each represent a hydrogen atom or an organic group having 1 to 10 carbon atoms, which may be the same or different. Z represents hydrogen, a hydroxyl group, or an organic group having an ethylenically unsaturated bond. n is an integer of 3 to 10000, and m is 1 or 2.

[0007] These polymers can be obtained by the following method. R ³ is -OR ⁴ (R ⁴ is as defined above)
Is obtained by reacting an acid dianhydride with an alcohol having one kind of ethylenically unsaturated bond and then reacting with a diamine using a carbodiimide-type dehydrating condensing agent such as dicyclohexylcarbodiimide. be able to. Furthermore, R ³ is -O ^over N ⁺ R ⁴ R ⁵
As a method for polymerizing a compound that is R ⁶ R ⁷ (R ⁴ , R ⁵ , R ⁶ , and R ⁷ are the same as described above), one kind of polyamic acid obtained by reacting an acid dianhydride with a diamine is used. By mixing with an amine having an ethylenically unsaturated bond and ion-bonding to the carboxyl group of the amic acid.
As a method for polymerizing a compound in which R ³ is —NHR ⁴ (R 4 is the same as described above), a polyamic acid obtained by reacting an acid dianhydride with a diamine is added to a polyamic acid in the presence of a base catalyst.
It can be obtained by reacting with an isocyanate having a kind of ethylenically unsaturated bond. As a method for polymerizing a compound in which R ³ is a hydroxyl group and Z is an organic group having an ethylenically unsaturated bond, a mixture of a diamine and an aminobenzene having an unsaturated bond as a substituent is reacted with an acid dianhydride. Alternatively, it can be obtained by adding and reacting a trimellitic acid having an unsaturated bond as a substituent to a diamine and an acid dianhydride.

[0008] Among these, -O ^{over N + R 4 R 5 R 6} R 7 is a volatile prone ionic bonding type photosensitive agent in the cure is as R ^3, hydroxyl group or hydrogen are preferred as Z.

In the general formulas (1) and (2), R
1 is a trivalent or tetravalent organic group having at least two or more carbon atoms. In order to obtain a polyimide polymer having excellent heat resistance, R1 preferably contains an aromatic ring or an aromatic heterocyclic ring. Preferred specific examples of R1 include 3,3 ′, 4,4′-diphenyltetracarboxylic acid, 3,3 ′, 4,4′-diphenylethertetracarboxylic acid, and 3,3 ′, 4,4′-benzophenonetetracarboxylic acid. Examples include, but are not limited to, residues such as carboxylic acid, pyromellitic acid, and trimellitic acid. Further, R1 may be composed of one kind of the organic groups, or may be composed of two or more kinds.

In the general formulas (1) and (2), R
2 is a divalent organic group having at least 2 carbon atoms. In order to obtain a heat-resistant polyimide-based polymer, R2 is an aromatic ring-containing or aromatic heterocyclic-containing 2
It is preferably a valent group. Preferred specific examples of R2 include paraphenylenediamine, metaphenylenediamine, orthophenylenediamine, diaminodiphenylsulfone, diaminodiphenylether, dimethylbenzidine, bis (trifluoromethyl) benzidine, bis (aminophenoxy) benzene, bis (aminophenoxy) Biphenyl, bis (aminophenoxyphenyl)
Ether, bis (aminophenoxyphenyl) methane,
Examples include, but are not limited to, the residues of compounds such as bis (aminophenoxyphenyl) sulfone. Further, R2 may be composed of one kind of the above organic groups, or may be composed of two or more kinds.

Further, 10 to 85 mol% of R1 in the general formulas (1) and (2) is a residue of diphenyltetracarboxylic acid, and 15 to 90 mol% is a residue of pyromellitic acid. It is preferable that 30 to 100 mol% of the phenylenediamine residues and 0 to 70 mol% are aromatic diamine residues containing an ether bond in the molecule.

Further, in order to improve the adhesiveness of the polyimide-based polymer, an aliphatic group having a siloxane bond can be copolymerized as R2 as long as the heat resistance is not reduced. Preferred specific examples include, but are not limited to, bis (3-aminopropyl) tetramethyldisiloxane.

The polymer in the present invention may be composed of only structural units represented by the general formulas (1) and (2), or may be a copolymer or a blend with other structural units. It may be. At that time, it is preferable that the content of the structural unit represented by the general formula (2) is 80% or more. The type and amount of the structural unit used for copolymerization or blending are preferably selected within a range that does not significantly impair the heat resistance of the polyimide-based polymer obtained by the final heat treatment.

In the general formulas (1) and (2), m is 1
Or 2, and n is an integer of 3 to 10,000.

Examples of the photosensitive agent used in the present invention include, but are not limited to, compounds represented by formula (3) and 4- (2'-nitrophenyl) -4-hydropyridines.

[0016]

Embedded image R4, R5 and R6 are organic groups having 1 to 30 carbon atoms, at least one of which contains an ethylenically unsaturated double bond.

Preferred specific examples of the above general formula (3) include dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, dimethylaminoethyl acrylate, diethylaminoethyl acrylate, dimethylaminopropyl methacrylamide, dimethylaminopropyl methacrylate, dimethylaminopropyl acrylate, Examples include, but are not limited to, dimethylaminopropylacrylamide, diethylaminopropylacrylamide, dimethylaminoethylmethacrylamide, diethylaminoethylmethacrylamide, diethylaminoethylacrylamide, and the like. Also, 4- (2 ′
Specific examples of -nitrophenyl) -4-hydropyridine derivative include 2,6-dimethyl-3,5-dicyano-
4- (2'-nitrophenyl) -1,4-dihydropyridine, 2,6-dimethyl-3,5-diacetyl-4-
(2′-nitrophenyl-1,4-dihydropyridine,
2,6-dimethyl-3,5-diacetyl-4- (2 ′,
4'-dinitrophenyl) -1,4-dihydropyridine and the like.

The photoinitiator used in the present invention includes N
Aromatic amines such as -phenyldiethanolamine, N-phenylglycine and Michler's ketone; cyclic oxime compounds represented by 3-phenyl-5-isoxazolone; and 1-phenylpropanedione-2- (o-ethoxycarbonyl) oxime. Chain oxime compound, benzophenone, methyl o-benzoylbenzoate,
Benzophenone derivatives such as dibenzyl ketone and fluorene, thioxanthone, 2-methylthioxanthone,
Examples include thioxanthone derivatives such as isopropylthioxanthone, but are not limited thereto.

Examples of sensitizers suitable for the present invention include aromatic monoazides such as azidoanthraquinone and azidobenzalacetophenone, coumarin compounds such as 3,3'-carbonylbis (diethylaminocoumarin), benzanthrone and phenanthrenequinone. Aromatic ketones such as those generally used for photocurable resins and those used as charge transfer agents for electrophotography are preferably used.

The photoinitiator and the sensitizer are used in an amount of 0.0
1 to 30% by weight, more preferably 0.1 to 20% by weight
It is preferred to add. Care must be taken when the ratio is out of this range, since the photosensitivity is lowered and the mechanical properties of the polymer are lowered. These photoinitiators and sensitizers alone,
Alternatively, two or more kinds can be used in combination.

In order to enhance the photosensitive performance of the composition of the present invention, a photoreactive monomer can be used as appropriate. As photoreactive monomers, 2-hydroxyethyl methacrylate, trimethylolpropane trimethacrylate,
Trimethylolpropane triacrylate, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, propylene glycol dimethacrylate, methylenebismethacrylamide, methylenebisacrylamide, and the like, but are not limited thereto. .

The photoreactive monomer is used in an amount of 1 to 3 based on the polymer.
It is preferable to add in the range of 0% by weight. If the ratio is outside this range, the photosensitivity is lowered and the mechanical properties of the polymer are lowered. These photoreactive monomers can be used alone or in combination of two or more.

In order to improve the adhesion between the coating film of the composition of the present invention or the polyimide film after the heat treatment and the support, an adhesion aid can be appropriately used. Examples of the adhesion aid include organic silicon compounds such as oxypropyltrimethoxysilane, γ-glycidoxytrimethoxysilane, γ-aminopropyltriethoxysilane, γ-methacryloxypropyltrimethoxysilane, and aluminum monoethylacetoacetate diisopropylate. And aluminum chelate compounds such as aluminum tris (acetylacetonate) and titanium chelate compounds such as titanium bis (acetylacetonate). In addition, other additives have adhesiveness to the substrate,
Sensitivity and heat resistance may be included as long as they do not significantly decrease.

Next, examples of the substrate on which the photosensitive polyimide precursor varnish is applied include a metal plate or metal foil such as copper, aluminum, and stainless steel, glass, a silicon wafer, alumina, and ceramic. They are not limited to these. Preferably, it is a stainless steel foil having a thickness of 5 to 100 μm, and more preferably a stainless steel foil having a thickness of 10 to 30 μm.

As a coating method, means such as spin coating using a spinner, spray coating using a spray coater, dipping, printing, roll coating, and coating using a reverse coater are possible. The coating film thickness can be adjusted by changing the coating means, the solid content concentration and the viscosity of the composition, and the coating is usually applied so as to be in the range of 0.1 to 150 μm.

Next, the substrate coated with the photosensitive polyimide precursor is dried to obtain a photosensitive polyimide precursor composition film. Drying is preferably performed in the range of 50 to 180 ° C. using an oven, a hot plate, infrared rays, or the like.
It is more preferable to carry out in the range of 0 to 150 ° C. The drying time is preferably from one minute to several hours.

Next, exposure is performed using a mask having a desired pattern. The exposure amount is 50 to 2000 mJ /
A range of cm ² is preferred. If the resolution of the pattern at the time of development is improved or the allowable range of the development conditions is increased, a step of baking before development may be incorporated. The temperature is preferably in the range of 50 to 200C. The time is preferably from 10 seconds to several hours. If the ratio is out of this range, the reaction may not proceed or all the regions may not be dissolved.

Next, a relief pattern is obtained by dissolving and removing the unexposed portion with a developing solution. A suitable developer can be selected in accordance with the structure of the polymer, but an aqueous alkali solution such as ammonia, tetramethylammonium hydroxide, diethanolamine, or a solution obtained by adding an additive such as an alcohol to an alkaline aqueous solution can be used. It can be preferably used. Also, N-methyl-2-pyrrolidone, N-acetyl-2-pyrrolidone,
N, N-dimethylformamide, N, N-dimethylacetamide, dimethylsulfoxide, etc. alone or in methanol, ethanol, isopropyl alcohol, water, methyl carbitol, ethyl carbitol, toluene, xylene, ethyl lactate, ethyl pyribate, propylene glycol Monomethyl ether acetate, methyl-3-
A mixed solution of the composition with a poor solvent such as methoxypropionate, ethyl-3-ethoxypropionate, propylene carbonate, 2-heptanone, and ethyl acetate can also be preferably used.

In the development, the above developer is applied to the coating surface as it is,
Alternatively, emit in the form of a mist, immerse in a developer,
Alternatively, it can be performed by a method such as applying ultrasonic waves to the immersed product.

Next, it is preferable to wash the relief pattern formed by development with a rinsing liquid. As the rinsing liquid, methanol, ethanol, isopropyl alcohol, ethyl lactate, ethyl pyribate, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, methyl-3-methoxypropionate, and ethyl-3, which have good miscibility with the developing solution, are used.
-Ethoxypropionate, propylene carbonate, 2-heptanone, ethyl acetate or water is preferably used.

The relief pattern polymer obtained by the above treatment is a heat-resistant polyimide-based polymer precursor, and becomes a heat-resistant polymer having an imide ring or other cyclic structure by heat treatment. The heat treatment temperature is preferably from 250 ° C. to 450 ° C. 25
When the temperature is 0 ° C. or lower, the performance such as chemical resistance is insufficient, and there is an obstacle to the formation of a thin film on the polyimide. At a temperature of 450 ° C. or higher, thermal degradation of the polyimide is observed and is inappropriate. The heat treatment is usually performed in an inert gas atmosphere or vacuum while increasing the temperature stepwise or continuously.

In the present invention, the step of performing a discharge treatment on the surface of the polyimide film subjected to the heat treatment includes applying a high voltage of direct current or alternating current between the electrodes or applying a high frequency energy to the electrodes to discharge which is started and maintained. This refers to the treatment performed by exposing the substrate to be treated. In the present invention, the atmosphere employed for the discharge treatment is selected from oxygen, nitrogen, argon, carbon dioxide, each gas atmosphere of a fluorine-based compound, or a mixed gas thereof, preferably, oxygen, a fluorine-based compound. Or a mixed gas atmosphere selected from these gases, and more preferably a gas atmosphere containing a fluorine-based compound. Of the fluorine compounds, trifluoromethane and tetrafluoromethane are most preferred.

The pressure of the atmosphere during the discharge treatment is not particularly limited, but low-temperature plasma treatment, which tends to occur in a pressure range of 10 ^{-3 to} 10 torr, is preferable in terms of treatment uniformity and treatment efficiency, and more preferably 10 ^{-1 to 2} torr. A range is preferred.

The processing intensity is 13.56 MHz.
2.0W in power density 1 × 10 ^{over 3} W · min / cm 3 or more
-The range of min / cm ³ or less is preferable. Here, the power density of the discharge process is a value obtained by multiplying the output multiplied by the discharge time by the volume of the reaction chamber.

As the metal thin film formed in the present invention, C
u, Cr, Ti, Ni, Ag, Au, Pd, Pt, A
Metals such as l and Sn are conceivable, and these may be used alone, in the form of an alloy, or two or more metals may be formed in layers. Among these, Cr is particularly preferable as the metal thin film that comes into direct contact with the polyimide because of its adhesion to the polyimide. The thickness of these metal thin films is 1 to 1000
0 nm is used. Preferably it is 10 to 1000 nm.

Further, a step of processing the formed metal thin film into a pattern using a photoresist may be provided.

As a method of forming a metal thin film, methods such as sputtering, vapor deposition, and plating are used. Among them, sputtering is particularly preferred from the viewpoint of adhesion to polyimide.

According to the present invention, the adhesion between the metal thin film of the metal thin film formed on the polyimide film obtained by the above treatment and the polyimide is 350 g / 90 ° peel strength.
cm or more, more preferably 450 g / cm
It is preferable that it is above.

The 90 degree peel test is performed by the following method. After attaching a metal thin film to the polyimide film, a metal thin film pattern having a width of 1.25 mm and a length of 4 cm is formed using a positive resist. The interface between the metal thin film pattern and the polyimide is peeled off by 5 mm in the length direction, a "cellotape" is attached to the peeled end, and the speed is 40 mm / min in the vertical direction using a digital force gauge FGN-5 manufactured by Shinpo Kogyo. , And the maximum value at that time was measured. Since the measurement width of this method is 1.25 mm, the measured value is 8
The product was multiplied by twice to obtain the peel strength.

If necessary, a step of applying a polyimide precursor of the second layer on the polyimide-metal thin film, drying and processing the polyimide precursor into a pattern may be included.

The polyimide film formed above is subjected to linear expansion in order to minimize residual stress with a metal plate or ceramic used as a substrate as a base, and similarly with a metal thin film formed on the polyimide film. Coefficient is 25 ° C ~
The average is preferably 25 ppm or less at 100 ° C.
It is desirable that the content be 0 ppm or less. The average coefficient of linear expansion between 25 ° C. and 100 ° C. is defined as 25 ° C. and 10 ° C.
This corresponds to the gradient of a straight line connecting 0 ° C.

In the present invention, the coefficient of linear expansion was measured by winding a polyimide film having a thickness of 10 μm, a width of 15 mm and a length of 30 mm into a cylindrical shape in the longitudinal direction, and using TM
The measurement was performed using A / SS-6000 at a temperature rising rate of 5 ° C./min in the range of 25 to 100 ° C.

[0043]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. Synthesis Example 1 200 equipped with a thermometer, a dry air inlet and a stirrer
In a 0 ml four-necked flask, 105.92 g of 3,3 ', 4,4'-diphenyltetracarboxylic dianhydride (0.
36 mol) and 760 g of N-methyl-2-pyrrolidone
And 4,4'-diaminodiphenyl ether 6
8.48 g (0.342 mol), 86.30 g (0.798 mol) of p-phenylenediamine, 14.91 g of bis-3- (aminopropyl) tetramethylsiloxane
(0.06 mol) and 150 g of N-methyl-2-pyrrolidone were added, and the mixture was stirred at 60 ° C. for 1 hour under flowing dry air, and then cooled to room temperature. Thereafter, 183.22 g (0.84 mol) of pyromellitic dianhydride and 203 g of N-methyl-2-pyrrolidone were added, and the mixture was stirred at 60 ° C. for 3 hours in a dry air stream.

Next, 4.55 g of Michler's ketone, 1-phenyl-propanedione-2- (o
After mixing and stirring 4.55 g of -benzoyl) oxime and 200 g of N, N-dimethylaminoethyl methacrylate, the mixture was filtered through a filter to obtain a photosensitive polyimide precursor composition solution. The prepared photosensitive polyimide precursor composition solution was used as varnish A.

Synthesis Example 2 68.48 g of 4,4'-diaminodiphenyl ether
(0.342 mol), 86.3 p-phenylenediamine
Instead of 0 g (0.798 mol), 1,3-bis (4-
Aminophenoxy) benzene 52.62 g (0.18 mol), p-phenylenediamine 103.81 g (0.9
A photosensitive polyimide precursor composition was prepared in the same manner as in Synthesis Example 1 except that 6 mol) was used. The prepared photosensitive polyimide precursor composition solution was used as varnish B.

Synthesis Example 3 300 equipped with a thermometer, a dry air inlet and a stirrer
In a 0 ml four-necked flask, 68.48 g (0.342 mol) of 4,4'-diaminodiphenyl ether, 86.30 g (0.798 mol) of p-phenylenediamine, bis-3- (aminopropyl) tetramethylsiloxane 1
4.91 g (0.06 mol) is dissolved in 2052 g of N, N-dimethylacetamide, and 105.92 g of 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride while maintaining the temperature at about 50 ° C. (0.36 mol) and 183.22 g (0.84 mol) of pyromellitic dianhydride were added,
The mixture was stirred at 50 ° C. for 3 hours under a stream of dry air. Next, 12 g of N, N-dimethylbenzylamine at 40 ° C. under light shielding.
Isocyanate ethyl methacrylate 93
g (0.60 mol) was added slowly, and the mixture was stirred at 40 ° C. for 4 hours.
After mixing and stirring 5 g, the mixture was filtered with a filter to obtain a photosensitive polyimide precursor composition solution. The prepared photosensitive polyimide precursor composition solution was used as varnish C.

Synthesis Example 4 500 equipped with a thermometer, a dry air inlet and a stirrer
8.83 g of 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride (0.083 g,
3 mol), 2-hydroxyethyl methacrylate
03 g (0.20 mol), γ-butyrolactone 100 m
After stirring at 60 ° C. for 2 hours, 15.27 g (0.07 mol) of pyromellitic dianhydride was added under ice-cooling. Further, 17.0 g of pyridine was stirred with ice cooling.
Was added. After stirring at room temperature for 16 hours, a solution of 41.2 g (0.20 mol) of dicyclohexylcarbodiimide in 40 ml of γ-butyrolactone was added over 10 minutes under ice-cooling, followed by 7.35 g of p-phenylenediamine (0.30 g).
068 mol), 2.95 g (0.008 mol) of 4,4′-bis (4-aminophenoxy) biphenyl, bis-
3- (aminopropyl) tetramethylsiloxane 1.0
g (0.004 mol) was added over 15 minutes. Under ice cooling, 3
After stirring for 5 hours, ethanol (5 ml) was added, and the mixture was further stirred for 1 hour. After the precipitate was filtered off, the obtained solution was added, and 10 L of ethanol was added. The generated precipitate was washed with ethanol, and then dried under vacuum to obtain a powder. . Under light blocking, this powder 3
After dissolving 0 g, Michler's ketone 0.6 g, and 1-phenyl-propanedione-2- (o-benzoyl) oxime 0.6 g in N-methyl-2-pyrrolidone 45 g, the mixture was filtered through a filter to obtain a photosensitive polyimide precursor composition. Solution was obtained. The prepared photosensitive polyimide precursor composition solution was used as Varnish D.

Synthesis Example 5 500 equipped with a thermometer, a dry air inlet and a stirrer
N-methyl-2-pyrrolidone 2 in a 4-ml four-necked flask.
50 g, 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride 29.42 g (0.1 mol), paraphenylenediamine 4.33 g (0.04 mol), 1,1'-biphenyl-2 , 2'-di (trifluoromethyl) -4,
19.2 g (0.06 mol) of 4'-diamine was added and reacted at room temperature for 48 hours to obtain a polyimide precursor. Thereafter, 2,6-dimethyl-3,5-dicyano-4- (2 ′
-Nitrophenyl) -1,4-dihydropyridine 6
After adding and dissolving 0.6 g, the mixture was filtered through a filter to obtain a photosensitive polyimide precursor composition solution. The obtained photosensitive polyimide precursor composition was used as Varnish E.

Example 1 Varnish A was spin-coated on a 25 cm SUS foil of 10 cm × 10 cm square, and a YAMATO clean oven DT was used.
And dried at 90 ° C. for 100 minutes with a thickness of 20 μm.
Was formed. Using a contact aligner PLA501F manufactured by Canon Inc., exposure was performed at 800 mJ / cm ² at a wavelength where a wavelength of 365 nm was cut. Ultrasonic development was performed at 25 ° C. for 20 minutes using a developer DV-822 manufactured by Toray. Next, the substrate was rinsed with isopropyl alcohol for 1 minute, dried, and heat-treated in nitrogen at 140 ° C. × 30 minutes + 350 ° C. × 1 hour. The film thickness after the heat treatment was 10 μm.

Next, using a plasma reactor apparatus PR-501A manufactured by Yamato Scientific, an oscillation frequency of 13.56 MHz,
Output 300W, tetrafluoromethane flow rate 50ml / m
The discharge treatment was performed for 10 minutes under the conditions of in, pressure 0.5 torr. The discharge intensity at this time was 0.41 W · min / cm ³
Met.

Then, using an Anelva SPL-500 sputtering apparatus, the output of Cr was 2500 WRF and the pressure was 0.1 W.
6 Pa, Ar flow rate 50 sccm, sputtering time 40 seconds, then Cu output 3000 WDC, pressure 0.2 P
a, Sputtering was performed at an Ar flow rate of 30 sccm for a time of 5 minutes. The respective film thicknesses were 50 nm and 700 nm.

The formed Cr / Cu sputtered film was spin-coated with a positive resist AZP4620 manufactured by Clariant Japan and dried at 105 ° C. for 20 minutes using a YAMATO clean oven DT42. 1.25 m using a contact aligner PLA501F manufactured by Canon Inc.
Exposure at 400 mJ / cm ² was performed at all wavelengths using a mask on which a pattern having a width of m and a length of 4 cm was formed. Clariant Japan developer AZ-400K / water = 1/3 (w
The resist was patterned using the developing solution of t). Then, after forming a Cu plating layer of 10 μm on the Cu surface on which the resist was developed by copper sulfate plating, 2.5% N
The resist was etched with aOH. By etching the unsputtered portions of the Cu sputter film and the Cr sputter film, a Cr sputter layer 50 is formed on the polyimide.
nm, Cu sputtering layer 700 nm, Cu plating layer 9 μm
In this order, a conductor pattern having a width of 1.25 mm and a length of 4 cm was obtained. The interface between the conductor pattern and the polyimide is peeled off by 5 mm in the length direction, "Scotch tape" is attached to the peeled end, and a vertical force is applied at a speed of 40 mm / min using a digital force gauge FGN-5 manufactured by Shinpo Kogyo. 1 cm was pulled, and the maximum value at that time was measured. Peel strength is 60
It was 8 g / cm. The average linear expansion coefficient at 25 ° C to 100 ° C of the polyimide film produced from Varnish A was 14 ppm.

Examples 2 to 6, Comparative Examples 1 to 3 The same procedures as in Example 1 were carried out except that the type of varnish and the plasma treatment conditions were in accordance with Table 1. 9 obtained
Table 1 also shows the 0 degree peel strength and the coefficient of linear expansion.

Example 7 Using a varnish C, a film having a thickness of 20 μm was formed on a SUS foil in the same manner as in Example 1. 600 m at all wavelengths using a contact aligner PLA501F manufactured by Canon Inc.
Exposure of J / cm ² was performed. 25, using a developer consisting of N, N-dimethylacetamide / water = 4/1 (wt)
Ultrasonic development was performed at ° C. Next, rinse with isopropyl alcohol, and then dry.
Heat treatment was performed in nitrogen at 1 ° C. × 1 hour. The film thickness after heat treatment is 10
μm.

Next, using a plasma reactor apparatus PR-501A manufactured by Yamato Scientific, an oscillation frequency of 13.56 MHz,
Output 100W, tetrafluoromethane / oxygen = 15ml
/ 35ml mixed gas, pressure 0.5torr 4
Discharge treatment was performed for minutes.

When the device was manufactured and evaluated in the same manner as in Example 1,
The peel strength was 528 g / cm. Varnish C
The average linear expansion coefficient at 25 ° C to 100 ° C of the polyimide film produced from was 21 ppm.

Example 8 Varnish D was spin-coated on a 25 cm SUS foil of 10 cm × 10 cm square, and a YAMATO clean oven DT was used.
The resultant was dried at 80 ° C. for 60 minutes by using No. 42 to form a film having a thickness of 20 μm. 600 mJ / cm ² at all wavelengths using a contact aligner PLA501F manufactured by Canon Inc.
Was exposed. Cyclohexanone / xylene = 7/3
After performing ultrasonic development using a developing solution composed of (wt), the substrate was rinsed with isopropyl alcohol. After drying, 1
Heat treatment was performed in nitrogen at 50 ° C. × 60 minutes + 350 ° C. × 2 hours. The film thickness after the heat treatment was 10 μm.

Next, after performing a discharge treatment in the same manner as in Example 7,
When produced and evaluated in the same manner as in Example 1, the peel strength was 504 g / cm. The average linear expansion coefficient at 25 ° C to 100 ° C of the polyimide film produced from Varnish D was 22 ppm.

Example 9 Varnish E was spin-coated on a 25 μm SUS foil of 10 cm × 10 cm square, and a YAMATO clean oven DT
The resultant was dried at 85 ° C. for 20 minutes by using No. 42 to form a film having a thickness of 23 μm. 1500 mJ / cm at all wavelengths using a contact aligner PLA501F manufactured by Canon Inc.
After performing the exposure of ² , the YAMATO clean oven D
Dried at 170 ° C. for 15 minutes using T42. 5% tetramethylammonium hydroxide aqueous solution / ethanol = 1/1 (wt)) at 40 ° C.
Was subjected to ultrasonic development. Next, it was rinsed with water, dried, and heat-treated in nitrogen at 150 ° C. × 30 minutes + 380 ° C. × 2 hours. The film thickness after the heat treatment was 10 μm.

Next, after performing discharge treatment in the same manner as in Example 7,
When produced and evaluated in the same manner as in Example 1, the peel strength was 520 g / cm. The average linear expansion coefficient at 25 ° C to 100 ° C of the polyimide film produced from Varnish E was 15 ppm.

[0061]

[Table 1]

[0062]

According to the present invention, unevenness in the treated surface is less likely to occur, and a strong and stable adhesiveness between the polyimide film and the metal thin film can be obtained.

Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat II (reference) // C08L 79/08 C08L 79/08 A F term (reference) 4F073 AA04 BA31 BB01 CA21 CA62 CA67 HA14 4J002 CM041 EH076 EP016 EU026 EU046 FD206 GQ05 4K029 AA02 BA02 BA03 BA04 BA05 BA07 BA08 BA12 BA13 BA15 BA17 BA21 BA22 BB02 CA01 CA05 FA05 FA07

Claims (10)

[Claims] (1) a step of applying a photosensitive polyimide precursor on a substrate and drying; (2) a step of exposing and developing a pattern; and (3) a heat treatment of the substrate on which the photosensitive polyimide precursor is applied. (4) a step of performing a discharge treatment after the heat treatment; and (5) a step of forming a metal thin film on the surface of the treated polyimide film as an essential step, wherein the discharge treatment includes at least one of oxygen or a fluorine-based compound. A method for forming a metal thin film on a polyimide film, wherein the method is performed in an atmosphere or a mixed gas atmosphere selected from these gases. 2. The method for forming a metal thin film on a polyimide film according to claim 1, wherein the discharge treatment is performed in a gas atmosphere containing a fluorine compound. 3. The method for forming a metal thin film on a polyimide film according to claim 2, wherein the fluorine compound is trifluoromethane or tetrafluoromethane. 4. The method for forming a metal thin film on a polyimide film according to claim 1, wherein the average linear expansion coefficient of the polyimide film at 25 ° C. to 100 ° C. is 25 ppm or less. 5. A polyimide film having a metal thin film having a 90 degree peel strength between the metal thin film and the polyimide of 350 g / cm.
The method for forming a metal thin film on a polyimide film according to claim 1 or 4, wherein: 6. A polyimide film having a metal thin film, wherein the 90-degree peel strength between the metal thin film and the polyimide is 450 g / cm.
The method for forming a metal thin film on a polyimide film according to claim 1 or 4, wherein: 7. The photosensitive polyimide precursor represented by the general formula (1)
The method of forming a metal thin film on a polyimide film according to any one of claims 1 to 6, comprising a polymer having a structural unit represented by the following as a main component and an amine compound having an unsaturated bond. Embedded image (R1 represents a trivalent or tetravalent organic group having at least 2 carbon atoms, R2 represents a divalent organic group having at least 2 carbon atoms, n is an integer of 3 to 10,000, and m is 1 or 2.) 8. The method for forming a metal thin film on a polyimide film according to claim 1, wherein the metal thin film in contact with the polyimide film of the polyimide film having the metal thin film is a film. 9. The method according to claim 1, wherein the substrate is a metal foil. 10. The method for forming a metal thin film on a polyimide film according to claim 9, wherein the metal foil is a stainless steel foil of 5 to 100 μm.