JP2003147099A - Aromatic polyimide film having low heat shrinkage stress and high adhesion and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an aromatic polyimide film simultaneously improved in heat shrinkage stress and adhesion. SOLUTION: This aromatic polyimide film having low heat shrinkage-stress and high adhesion is characterized by having <=10 MPa heat shrinkage stress and 75-150 mN/m surface free energy and has >=1×10<15> spins/g electron spin density.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a low-heat-shrinkage-stress and high-adhesion aromatic polyimide film in which heat-shrinkage stress and adhesiveness are simultaneously improved, and a method for producing the same. Especially high definition F
PC (Flexible Printed Circui
t), a high-definition COF (Chip on Film) circuit and a coverlay used for the same, a backing film (stiffener), and a low heat shrinkage stress and high adhesion aromatic polyimide film used for a lead frame holding tape, and a method for producing the same.

Further, low heat shrinkage stress and high adhesion fragrance used for a COF (Chip on Film) circuit substrate in which high-definition wiring with a pitch of 80 μm or less, which has improved adhesion to metal and flatness of metal vapor deposition product at the same time, is formed. Group polyimide film and a method for manufacturing the same.

[0003]

2. Description of the Related Art In recent years, the sophistication of electronics, especially the demand for printed circuit boards used for high frequencies has been increasing. In particular, for the purpose of cost reduction, the treatment is often performed in a large area, and the use at high temperature is also increasing. For this reason, the requirements for dimensional stability and adhesiveness are becoming strict, and the demand for polyimide films having improved properties at the same time is increasing. Conventionally, there was a method of discharging the polyimide film surface,
It was not possible to easily obtain a product which simultaneously satisfied the preferable heat shrinkage stress.

Japanese Patent Publication No. 35106/1995 proposes a polyimide film obtained by subjecting a polyimide film to a surface treatment in advance with low-temperature plasma and then heat-treating the polyimide film. The functional group on the surface obtained by the low-temperature plasma treatment is subjected to a heat treatment in a post-process, so that the functional group may sneak into the inside due to molecular motion or undergo a change over time, so that the effect is reduced. Further, in this publication, a preferable heat shrinkage ratio is obtained and the curl of the printed circuit board is reduced, and the adhesiveness is insufficient.

[0005]

However, as a result of earnest studies by the inventor, it was found that the curl of the laminated component is an imbalance of stress, and the present invention was completed. It has been clarified that reducing the heat shrinkage stress is an effective method for obtaining a good printed circuit board when used for a high frequency printed circuit board or a large area.

The present invention provides an aromatic polyimide film having simultaneously improved heat shrinkage stress and adhesion.

[0007]

[Means for Solving the Problems] Polly according to the present invention
Mid film has a surface with a heat shrinkage stress of 10 (MPa) or less
Free energy is 75 [mN / m] to 150 [mN / m
m] low heat shrinkage stress high adhesion aromatic polyimide fill
It is. Furthermore, the electron spin density is 1 × 10. ¹⁵[S
pins / g] or more, low heat shrinkage stress, high adhesion aromatic poly
It is a mid film. Furthermore, the water contact angle is 55 ° or less
With low heat shrinkage stress and high adhesion aromatic polyimide film
is there.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The polyimide film of the present invention is a polyimide having a structural unit represented by the following general formula (I).

[0009]

[Chemical 1]

R1 and R3 are tetracarboxylic dianhydride residues, and R2 and R4 are divalent diamine compound residues. A preferable tetracarboxylic dianhydride residue is represented by the following general formula (II).

[0011]

[Chemical 2]

More preferably (III),

[0013]

[Chemical 3]

Most preferred is (IV).

[0015]

[Chemical 4]

The preferred diamine compound residue is represented by the following general formula (V).

[0017]

[Chemical 5]

More preferably (VI),

[0019]

[Chemical 6]

Most preferably R2 is (VII)

[0021]

[Chemical 7]

R4 is (VIII).

[0023]

[Chemical 8]

The aromatic polyimide film is a polyimide film polymerized from at least 3,4'-oxydianiline and pyromellitic dianhydride. As a more specifically preferred composition of the polyimide film, the diamine component is at least paraphenylenediamine (PP
D), oxydianilines (ODA), and at least biphenyltetracarboxylic dianhydride (BPD)
A), consisting of pyromellitic dianhydride (PMDA),
PPD / ODA molar ratio 10/90 to 40/60, B
It is an aromatic polyimide film derived from a polyamic acid polymerized from a composition having a PDA / PMDA molar ratio of 10/90 to 40/60.

An aromatic polyimide film in which the aromatic polyimide film is polymerized from at least 4,4'-oxydianiline, paraphenylenediamine, biphenyltetracarboxylic dianhydride and pyromellitic dianhydride. As a particularly preferred composition of the polyimide film, the diamine component is at least 3,4′-oxydianiline (34′ODA), 4,4′-oxydianiline (44′ODA), and the acid dianhydride is at least biphenyltetracarboxylic acid. Composition consisting of dianhydride (BPDA) and pyromellitic dianhydride (PMDA), molar ratio of PPD / ODA is 20 / 80-80 / 20, molar ratio of BPDA / PMDA is 0 / 100-40 / 60. A polyimide film derived from a polyamic acid polymerized from an object.

The heat shrinkage stress is 10 (MPa) or less. It is preferably 5 (MPa) or less, more preferably 1 (MPa) or less, and most preferably 0.5 (MPa) or less. 1
When it exceeds 0 (MPa), when it is used as a flexible printed circuit board for high-dimensional definition, after copper etching, partial distortion or stress concentration occurs, resulting in dimensional change, resulting in poor flatness and curling. Occur. If the flatness is deteriorated or the curl is large, it becomes difficult to operate the flexible printed circuit board for high-definition definition when it is installed in the electric equipment.

The free energy range of the film surface is 75 [mN / m] or more. More preferably 85
[MN / m], most preferably 95 [mN / m]
Is. The larger this value is, the better, but the upper limit calculated from the range studied is 150 [mN / m]. 75 [mN
/ M], the adhesiveness with a part of the adhesive used in polyimide becomes low.

The preferred electron spin density in the film is 1.
× 10 ¹⁵ [spins / g] or more. Preferably 1 × 1
0 ¹⁶ [spins / g], and more preferably 1 × 10 ¹⁷ [spin
s / g]. Electron spin density is 1 × 10 ¹⁵ [spins /
If it is less than g], the adhesion to the vapor-deposited metal will be insufficient. The electron spin density represents the amount of radicals in the film, and the larger the electron spin density, the better the adhesiveness. The upper limit would be 1 × 10 ²⁵ [spins / g] calculated from the limit of throughput. To increase the amount of radicals, use the imidization temperature during production,
For example, it is also preferable to add a monomer, a radical generator or a polymer that is easily decomposed at 500 ° C. or lower to decompose and generate a radical. In addition, a method of thermally decomposing a part of the polyimide film by heating at the time of imidization at the time of production or ion implantation is also effective.

The conditions for thermally decomposing a part of the polyimide can be evaluated by TGA. The standard is to heat at a temperature of 200 ° C lower than the 1% heat loss temperature. Generally, the 1% heat loss temperature of an aromatic polyimide is 520 ° C. to 550 ° C., so if the temperature exceeds this temperature, thermal crosslinking will proceed excessively, which is not preferable. The preferred heating conditions are 200 ° C. or higher, more preferably 300 ° C. or higher, and most preferably 400 ° C. or higher. The atmosphere gas is nitrogen or air. When polyimide is heated to generate radicals, a part of the radicals causes thermal crosslinking. It is preferable to stabilize the generated radicals and prevent thermal crosslinking, but it is also possible to have appropriate thermal crosslinking.

The radical generator is preferably an organic substance capable of decomposing by a high temperature treatment at 300 ° C. or higher to generate radicals. Preferably decomposed at 1% by weight or more at 300 ° C or higher,
An organic substance having an aromatic ring having a substituent that causes a stable radical to exist in the polyimide film is preferable. Here, the aromatic ring functions to stabilize the radical for a long life, and a species having a long radical half-life of minutes order or longer is preferable.

Examples of the radical generator include benzoyl peroxide, dicumyl peroxide and cumene hydroperoxide. 0.01 as addition amount
It is 10 to 10% by weight, preferably 0.1 to 1% by weight.

The water contact angle is preferably 55 ° or less. It is more preferably 50 °, and particularly preferably 45 °. When the water contact angle exceeds 55 °, the adhesiveness with the adhesive or the metal used in polyimide may decrease. The lower limit of the water contact angle would be 1 °, calculated from the significant figures of the measurement.

The water contact angle, the surface free energy and the electron spin density in the film are all requirements for obtaining favorable adhesion.

As a typical processing method for obtaining the preferable heat shrinkage stress and adhesiveness of the present invention, it is preferable to carry out a heat treatment and then an adhesion imparting treatment for further increasing the surface free energy.

It is preferable that the heat treatment and the adhesion-imparting treatment are successively performed.

On the contrary, when heat treatment is performed after the adhesion-imparting treatment,
The relationship between the subsequent heat treatment temperature (T ° C.) and the heat treatment time (s minutes) is T × s ≦ 600. That is, when heat treatment is performed at high temperature for a long time, surface free energy tends to be lowered due to molecular motion of polar molecules on the surface, and therefore short-time treatment at low temperature is preferable. Further, it is preferable that the adhesion imparting treatment and the heat treatment are continuously performed.

The adhesion applying treatment method includes flame treatment, discharge treatment, corona treatment, ultraviolet treatment, reverse sputtering, electromagnetic wave,
There is a method of directly or indirectly generating a polar group by exciting a molecular energy state by light such as laser treatment, energy of high heat or electricity. Preferred are plasma discharge treatment, reverse sputtering, corona discharge treatment, arc discharge treatment and glow discharge treatment. Most preferable are atmospheric pressure plasma discharge treatment with ultraviolet light, atmospheric pressure corona discharge treatment, reverse sputtering, and atmospheric pressure glow discharge treatment.

A preferred processing method will be described below.

A preferable maximum heat treatment temperature condition for reducing the heat shrinkage stress to 10 (MPa) or less is 150 ° C. or more and 500 ° C. or less. It is preferably 250 ° C. or higher. More preferably, it is 300 ° C. or higher.

The maximum heat treatment temperature for continuous treatment is 2
If the temperature is lower than 00 ° C, the reason for which the reason is unknown is that the generation rate of the finally generated electron spin is slow or decreases, which is not preferable. 1 when heat treatment is performed at low temperature in batch processing
The heat treatment can be performed for about several days depending on the time, but the heat treatment time for a long product is preferably about 1 second to 10 minutes at a high temperature.

As a preferable method for reducing the heat shrinkage stress, it is preferable to carry out heat treatment at multi-step temperatures.
In this case, the temperature of the first heat treatment is higher than the temperature of the subsequent heat treatment. For example, as a multi-step heat treatment method, 440 ° C,
There is a method of performing heat treatment at 330 ° C. for 1 minute after heat treatment at 1 minute. There is a method in which the roll wound with the film is left in a heating oven, or a method in which it is heat-treated under no tension.
If only heat shrinkage stress is reduced, no tension is preferable. When the adhesion-imparting treatment is continuously performed by long winding, it is preferable to perform the treatment with a tension of 1 to 10 [kg / m] in the length direction of the film. Further, it is preferable to perform a heat treatment with hot air continuously while applying tension and then perform a cooling treatment.
A preferred range is 2 [kg / m] to 7 [kg / m].

If the tension in the lengthwise direction is less than 1 [kg / m], wrinkles may occur in the film, causing a problem of meandering during continuous winding. If it exceeds 10 [kg / m], the heat shrinkage stress may increase.

The heat source for the heat treatment is hot air, heat radiation from an infrared heater or the like, and electromagnetic waves.

The adhesion-imparting treatment is preferably carried out continuously after the heat treatment. The reason why the heat treatment is performed immediately before the discharge treatment is that the moisture content is low and the adhesion imparting treatment is remarkably effective.

By preliminarily undergoing a heat treatment step, the water content in the film can be reduced to 1/10 or less of the saturated water content in immersion. The water content immediately before the adhesion imparting treatment or at the time of the adhesion imparting treatment is preferably 1% or less. More preferably 0.5
% Or less. Most preferably, it is 0.1%. Although the reason is unknown, when the water content in the film is high, the effect of the electric discharge treatment is significantly reduced. Since the saturated moisture content of the polyimide film is usually about 3%, there is a problem that the adhesion imparting effect varies depending on the humidity in the air. The preferred production method of the present invention produces a surprising effect, and stably provides a low heat shrinkage stress and high adhesion aromatic polyimide film.

When the discharge treatment is not continuously performed after the heat treatment, it is preferable to store the film in a dry state so as not to absorb moisture. Therefore, storage in a drying room, combined use with a desiccant, and packaging with a moisture-proof film are also preferable.

Next, electric discharge machining is performed. As mentioned above, low pressure plasma and atmospheric pressure plasma are the preferred methods. The atmosphere gas in the plasma treatment is a gas selected from oxygen, nitrogen, argon, carbon dioxide, air, hydrogen and a mixed gas thereof. At this time, the water content is 1000 pp
It is preferably m or less. Most preferably, it is argon.

The frequency of the high voltage applied to the high voltage applying electrode is preferably selected in the range of 20 kHz to 100 MHz. More preferable frequency is 50 kHz to 500 kHz
Hz. The processing strength is preferably 50 W · min / m 2 or more, and more preferably 8 or more.
It is 0 W · min / m 2 or more.

In the molecular structure of the polyimide film, the acid or diamine component preferably contains a flexible portion. Although it is unknown for some reason, it is presumed that the flexible portion derived from the bending component is likely to be micro-roughened by being specifically treated by the electric discharge treatment. Therefore, a polyimid film composed of three or more components having a bending component and a linear component is particularly preferable.

The polyimid film having improved heat shrinkage stress and adhesiveness according to the present invention is suitable as a base film of FPC or a cover film (lining) thereof, or a lead frame suppressing tape.

The film of the present invention is also used in a field of application in which the substrate directly bonded to the surface having improved adhesion has a thin structure. It is preferably used for applications requiring high dimensional accuracy, in which the wiring has a pitch of 80 μm or less. Particularly, it is preferably used for applications requiring a high dimensional accuracy such as a pitch of 60 μm or 40 μm, and further 20 μm. Specific applications include PDP and LCD
It is a polyimide film used in flexible printed circuit boards for COF applications, such as display applications and HDD wireless suspension applications.
Adhesives or copper metal are the substrates that are directly bonded to it.

[0052]

EXAMPLES The low heat shrinkage stress and high adhesion aromatic polyimide film according to the present invention will be described below. The polyimide film referred to herein has a thickness of 5 μm or more. The upper limit is not particularly limited as long as it can be treated, but may be 300 μm or less. In the following examples, all percentages are by weight unless otherwise stated. The polyimide films used below were all stored at room temperature in a vacuum desiccator except during processing or evaluation.

Measurement and Evaluation 1. The heat shrinkage stress tensile type test piece of the polyimide film was measured in a constant length mode from room temperature (25 ° C.) using TMA (Seiko Denshi Kogyo KK, TMA / SS120C type). A test piece having a width of 5 mm and a measurement length of 20 mm was used, and measurement was performed under conditions of a temperature rising rate of 10 ° C./min and a maximum temperature of 500 ° C. A graph of heat shrinkage stress on the vertical axis and temperature on the horizontal axis was drawn, and the maximum heat shrinkage stress was taken as the heat shrinkage stress. 2. Thermal shrinkage According to JIS-B-0601 (1994), the dimensional shrinkage of the polyimide film before and after heat treatment is measured. The heat treatment condition is 300 ° C. × 2 hours. 3. Adhesion strength Using the sample after surface treatment stored in a vacuum desiccator, and using an acrylic adhesive ("Pyralax" manufactured by DuPont), the above treated film and copper foil (electrolysis manufactured by Mitsui Mining & Smelting Co., Ltd.) Copper foil “3EC” (thickness: 35 μm) was laminated and the adhesive was cured at 185 ° C. for 1 hour to prepare a film / adhesive / copper foil laminate (hereinafter referred to as FC laminate). A sample having a width of 10 mm and a length of 30 cm was cut out from the obtained FC laminated plate, and a pole test speed 50 was obtained by a tensile tester (A & D Tensilon universal tester UTA-300KN).
A tensile test of 90 ° peeling was performed at mm / min. Values were averaged for n = 5.

◎ Adhesion strength 18 N / cm or more, peeling at the interface between the copper foil and the adhesive.

○ Adhesive strength Peeling off at the interface between the adhesive and the polyimide film at 18 N / cm or more.

△ Adhesion strength 10 N / cm or more 18 N
</ Cm x adhesion strength <10 N / cm 4. Using a surface free energy contact angle meter (CA-X type, manufactured by Kyowa Interface Science Co., Ltd.), the contact angle between ethylene glycol, methylene iodide and water and the film was measured, and the dispersion force component γd and dipole of the film surface were measured. The component γp and the hydrogen bond component γh were determined. At this time, the values shown in Table 1 were used for the dispersion force component γd of the liquid, the dipole component γp, and the hydrogen bond component γh.

For the calculation, solid surface free energy analysis software EG-11 (manufactured by Kyowa Interface Science Co., Ltd.) to which the extended Fowkes theory was applied was used.

[0058]

[Table 1]

5. JES-FE3XG (manufactured by JEOL Ltd.) as electron spin density ESR measurement device, microwave frequency counter (TR5212, Advantest) and ESR data system (ES-PRIT2) as accessory devices
3, manufactured by JEOL Ltd.).

In order to avoid the signal saturation with respect to the microwave output, the sample with many spins has a microwave output of 4 μm.
W, a small sample was measured with a microwave output of 20 μW.
At the time of measurement, Mn ²⁺ in MgO was simultaneously measured as an external standard sample.

The electron spin density is a value calculated from the ESR signal intensity obtained by numerically integrating the observed ESR signal twice, and represents the amount of radicals per unit weight. Assuming that the ESR signal intensity complies with the Curie law, the radical amount was calculated using an ion-implanted polyethylene film as a secondary standard sample. The spin number of the polyethylene film is quantified in advance using copper sulfate pentahydrate.

The measurement conditions used are as follows.

Measurement temperature; room temperature Magnetic field sweep range; 326.2 to 346.2 mT modulation; 100 kHz, 0.32 mT microwave output; 4 μW or 20 μW, 9.43 GHz sweep time; 1.5 minutes × 20 times time constant; 0 1 second number of data points; 2048 points cavity; TE ₀₁₁ ; cylindrical type 6. Evaluation of Curvature of Metal Laminated Plate (Curl) A polyimide-based adhesive was applied to a polyimide film, and a copper foil was attached thereto at a temperature of 250 ° C. After that, the maximum temperature is raised to 300 ° C. to cure the adhesive, the obtained metal laminated plate is cut into a sample size of 35 mm × 120 mm, and left in an atmosphere of 25 ° C. and 60 RH% for 24 hours. Warpage was measured.
As for the warp, the sample was placed on a glass plate and the heights of the four corners were measured and averaged. The evaluation criteria were determined as follows according to the amount of warpage. × level is used as a metal wiring circuit board,
It is at a level where handling becomes difficult during transportation in the subsequent process.

Amount of warp less than 1 mm Δ Amount of warp 1 mm or more and less than 3 mm × Amount of warp 3 mm or more (Example) N, N-dimethylformamide (hereinafter DMA
70 mol% of 4,4′-diaminodiphenyl ether (hereinafter, 44′ODA) was supplied to and dissolved in c), followed by paraphenylenediamine (hereinafter, PP).
D) (30 mol%) and pyromellitic dianhydride (hereinafter referred to as PMDA) are sequentially supplied, and the mixture is stirred at room temperature for about 1 hour.
Finally, the polycarboxylic acid concentration 2 in which the tetracarboxylic dianhydride component and the diamine component are approximately 100 mol% stoichiometry
A 0 wt% solution was prepared.

This polyamic acid solution was ice-cooled and acetic anhydride was added.
After adding β-picoline and stirring, it was made into a heat-supporting film, then peeled from the support, the conversion reaction to imide was simplified and the solvent was dried, and it was wound into a roll as a 25 μm-thick polyimide film. (Film A) 3,4′-diaminodiphenyl ether (hereinafter referred to as 34′ODA) in DMAc was supplied and dissolved at 50 mol% based on the total diamine, and then PMDA was added on the basis of 4% based on the total acid anhydride.
Polyamic acid polymer A in which 9.5 mol% was supplied and reacted, and 0.5 mol% of acetic anhydride was added to block the acetyl end.
Was adjusted. Subsequently, 44'ODA (50 mol%) and the remaining PMDA were sequentially supplied, and the polymer B was polymerized by stirring at room temperature for about 1 hour. Finally, a solution of a polyamic acid concentration of 20% by weight was prepared, which was a mixed composition of the polymer A and the polymer B in which the tetracarboxylic dianhydride component and the diamine component had a stoichiometry of about 100 mol%.

This polyamic acid solution was ice-cooled, and acetic anhydride and β-picoline were added and stirred to form a heat-supporting film, which was then peeled from the support to further simplify the conversion reaction to an imide and to use a solvent. Was dried and wound into a roll as a polyimide film having a thickness of 10 μm (Film B) PPD was supplied and dissolved in DMAc in an amount of 20 mol% based on the total amount of diamine, and then PMDA was added to 1% based on the total amount of acid anhydride.
Polyamic acid polymer A in which 9.8 mol% was supplied and reacted, and 0.5 mol% of acetic anhydride was added to block the acetyl end.
Was adjusted. Subsequently, 44'ODA (80 mol%) and biphenyltetracarboxylic dianhydride (hereinafter BPDA,
25 mol%) and PMDA (55 mol%) are sequentially supplied,
Polymer B was polymerized by stirring at room temperature for about 1 hour. Finally, the tetracarboxylic dianhydride component and the diamine component are about 1
A solution having a polyamic acid concentration of 20% by weight was prepared from a mixed composition of polymer A and polymer B having a stoichiometry of 00 mol%.

This polyamic acid solution was ice-cooled, acetic anhydride and β-picoline were added, and the mixture was stirred to form a heat-supporting film, which was then peeled from the support to further simplify the conversion reaction to an imide and to use a solvent. Was dried and rolled into a roll as a polyimide film having a thickness of 45 μm (Film C) Examples 1 to 7 This polyimide film (Film A, Film B or Film C) was continuously fed to a tunnel hot air oven at room temperature. It was wound up while cooling. The film tension during heat treatment was adjusted by the difference in rotation speed between the feed roller and the take-up roller, and the heat treatment time was adjusted by the relative rotation speed of each roller. The heat-treated roll film is immediately 760To
Plasma treatment was performed in an atmosphere of argon gas or air at rr. Electrode width 1m, film running speed 10m / min-40
m / min, input power was 1000W to 1400W. The tension at this time was 3 to 5 kg / m.

Other conditions and results are shown in Table 2.

[Comparative Example] Comparative Example 1 was heat-treated only, Comparative Example 2 was electrical treatment only, and Comparative Example 3 was electrical treatment and then heat-treated.

In Comparative Example 4, a high temperature heat treatment at 550 ° C. was performed, followed by an electric treatment. When the high temperature heat treatment at 550 ° C. is performed with a low tension, the film is wrinkled due to shrinkage, so it is necessary to increase the tension and convey the film. Moreover, the flatness of the produced film was poor.

The results are shown in Table 2.

[0072]

[Table 2]

[0073]

The aromatic polyimide film of the present invention has improved heat shrinkage stress and adhesiveness at the same time.

Front page continuation (51) Int.Cl. ⁷ Identification code FI theme code (reference) // B29K 79:00 B29K 79:00 B29L 7:00 B29L 7:00 C08L 79:08 C08L 79:08 Z F term ( Reference) 4F071 AA60 AF06 AF34 AF36 AF58 AF61 AG16 AG17 AG18 AG19 AG28 AH12 AH13 BA02 BB02 BC01 BC12 BC17 4F073 AA01 AA29 AA32 BA31 BB01 CA01 CA21 CA45 CA46 CA49 CA62 CA63 CA64 CA65 CA69 GA01 GA03 GA05 A05 AD08A03 4F209 4 AH36 AM27 AM32. VA051 VA062 XA16 XA19 XB02 XB16 YA06 YA07 YA08 YA13 YA28 YA29 ZA02 ZA31 ZA34 ZA41 ZA60 ZB11 ZB47 ZB50 ZB60

Claims (7)

[Claims] 1. A heat shrinkage stress of 10 (MPa) or less and a surface free energy of 75 [mN / m] to 150 [mN / m].
A low heat shrinkage stress, high adhesion aromatic polyimide film. 2. The electron spin density is 1 × 10 ¹⁵ [spins /
g] or more, the low heat shrinkage stress and high adhesion aromatic polyimide film according to claim 1. 3. The low heat shrinkage stress, high adhesion aromatic polyimide film according to claim 1, which has a water contact angle of 55 ° or less. 4. The low heat shrinkage stress, high adhesion aromatic according to claim 1, wherein the aromatic polyimide film is polymerized from at least 3,4′-oxydianiline and pyromellitic dianhydride. Polyimide film. 5. The aromatic polyimide film is polymerized from at least 4,4′-oxydianiline, paraphenylenediamine, biphenyltetracarboxylic dianhydride and pyromellitic dianhydride.
A low heat shrinkage stress, high adhesion aromatic polyimide film as described in any one of 1. 6. An aromatic polyimide film having a thickness of 200 to 50.
A heat shrinkage stress of 10 MPa or less and a surface free energy of 75 to 1 characterized by undergoing a heat treatment step at a temperature of 0 ° C. and a step of subjecting one or both surfaces to an electric discharge treatment.
A method for producing an aromatic polyimide film having a rate of 50 mN / m. 7. The method for producing an aromatic polyimide film according to claim 6, wherein the tension in the longitudinal direction of the film during the heat treatment and the discharge treatment is 10 kg / m or less.