JPH08281816A - Film and flexible printed board using the same - Google Patents

Abstract

PURPOSE: To obtain a film which has stable mechanical characteristics at high temperature and humidity and is suitably used for a flexible printed board. CONSTITUTION: A film is formed of organic polymer which has 70% or more of elongation holding rate when it is treated in a high-pressure steam atmosphere at 155 deg.C for four days and 1% or less of heat shrinkage factor at 250 deg.C. A flexible printed board formed of the film is provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a film suitable for use as a base film such as a flexible printed circuit board (hereinafter abbreviated as FPC) having stable performance even in a very harsh atmosphere.

[0002]

2. Description of the Related Art Conventionally, in the mechanical industry, the electrical industry field, the electronic industry field and the printing field, from the viewpoint of downsizing and weight reduction of equipment, the conversion from metal or ceramic materials to organic polymers has been promoted and A material having both properties and heat resistance is required. Taking an FPC as an example, the FPC has a form in which an electric circuit is formed on both sides or one side of a base film, and a cover film is laminated if necessary. Since it may be immersed in a solder bath when components are mounted, heat resistance is required as a base material, and a polyimide film is usually used.

[0003]

However, although the polyimide film has good heat resistance, it does not originally have high strength and Young's modulus, and its mechanical properties are significantly deteriorated under high temperature and high humidity. In the field where stable mechanical characteristics of movable parts such as printer heads are required, the reliability of the film is low in the field.

From this point of view, a material having excellent heat resistance and rigidity and having stable performance under high temperature and high humidity has been demanded.
For example, aromatic polyamide films are known to have excellent heat resistance and rigidity. However, the film swells due to moisture absorption and lacks dimensional stability. Further, a low temperature solution polymerization method using an acid chloride and a diamine is effective for increasing the degree of polymerization to obtain a highly rigid film. However, when the polymerization method is used, hydrochloric acid generated, a neutralizing agent, and a solubility improvement are generated. Often contains a large amount of ionic impurities such as additives.

Such impurities can be a factor that greatly deteriorates the physical properties under high temperature and high humidity.

[0006] Therefore, the inventors of the present invention conducted extensive studies and found that a film having stable performance under high temperature and high humidity could be obtained by controlling the constitution of the base material and impurities in the base material, and arrived at the present invention.

[0007]

That is, the present invention provides 15
An organic polymer having an elongation retention of 70% or more and a dimensional change rate of 1% or less at 250 ° C. when treated in a high-pressure steam atmosphere at 5 ° C. for 4 days. It is a film.

The organic polymer constituting the film of the present invention has an elongation retention rate of 70% or more, preferably 80% or more, and more preferably 85 when treated in a high-pressure steam atmosphere at 155 ° C. for 4 days. If it is at least%, there is no particular limitation. By satisfying the elongation retention within the range of the present invention, a stable product free from embrittlement can be obtained under high temperature and high humidity.

Examples of materials that can be used as these base materials include polyamide, polyimide, polyester, polycarbonate, polyacetate, polyacrylate, polyacrylonitrile, polyvinyl alcohol, polyalkylene resin, and fluororesin. Of these, polyamides, particularly aromatic polyamides, are preferred because of their high rigidity and excellent processability.

Here, the aromatic polyamide means the following general formula (I) and / or general formula (II)

Embedded image General formula (II)

Embedded image (Here, Ar ₁ , Ar ₂ and Ar ₃ are aromatic nuclei, and R, R ′ and R ″ are a halogen group, a nitro group, a cyano group, an alkyl group having 1 to 4 carbon atoms, and an alkyl group having 1 to 3 carbon atoms. A functional group selected from an alkoxy group and a trialkylsilyl group,
l, m and n are integers of 0-4. ), Which preferably contains 50 mol% or more of the repeating unit represented by the general formula (I) and / or the general formula (II),
It is more preferably 70 mol% or more.

Here, Ar ₁ , Ar ₂ and Ar ₃ are, for example, those represented by the general formula (III)

Embedded image And the like, X and Y are —O—, —CH ₂ —, —CO—, —SO ₂ —, —S—,
-C (CH _{3) 2} - is chosen from such, but is not limited thereto.

From the viewpoint of characteristics, the above-mentioned aromatic ring bonded in the para position is 50% or more, preferably 75% of the total aromatic ring.
%, A polymer having a high rigidity and a good heat resistance is preferable.

The para bond means that the main chain in the aromatic ring is bound to the para position or that the main chains at both ends of the residue consisting of two or more aromatic rings are coaxial or parallel. Means Examples of such aromatic rings include those of general formula (IV).

General formula (IV)

[Chemical 4] The aromatic polyamide contains 50 mol% of repeating units represented by the general formula (I) and / or the general formula (II).
The above content is included, and if it is less than 50 mol%, other repeating units may be copolymerized or blended as long as the present invention is satisfied.

Further, in order to improve the elongation retention of the aromatic polyamide, a part of hydrogen atoms on these aromatic rings is replaced with R, R in the general formula (I) and / or the general formula (II). Substitution with a substituent such as a halogen group (especially chlorine), a nitro group, an alkyl group having 1 to 4 carbon atoms (especially a methyl group) or an alkoxy group having 1 to 3 carbon atoms represented by ‘ The general formula (I) is preferable.
Alternatively, the values of l, m and n in the general formula (II) are arbitrary, but in the general formula (I), l + m is 1 or more and 4 or more.
Below, it is practical that it is preferably 2 or more and 4 or less, and l> 0 and m> 0. When l + m exceeds 5, the film becomes brittle, which is not preferable. In the general formula (II), it is practical that n is 0 or more and 2 or less, preferably 1 or more and 2 or less. In addition, among the substituents that can be introduced, the substituents that are preferably used include chlorine, methyl group, and methoxy group because they have almost no deterioration in mechanical properties, and have excellent moist-heat resistance and little decrease in elongation. Therefore, chlorine is more preferable. Unnecessarily bulky functional groups are rather unsuitable for the purpose of the present invention because they impair other important physical properties.

Further, when introducing a substituent into the aromatic ring, it is very important to introduce a substituent at the ortho position of the amide group in order to attain the object of the present invention. That is, when the ortho-position has a substituent, the elongation retention is improved. This ratio is arbitrary as long as the object of the present invention can be achieved, but it is preferably 60% or more of the total amide groups, and preferably 7%.
It is preferable that the substitution is 0% or more, and more preferably 80% or more.

The term "elongation retention rate" as used in the present invention means that a sample having an initial elongation of Er0% is sealed in a container by adding pure water, and the sample tube is treated in an oven at 155 ° C for 4 days. When the elongation afterwards is Er1%, (Er1 / Er0) × 100
It is a value defined by (%) and needs to be 70% or more. Only when this value is 70% or more, the mechanical stability under high temperature and high humidity is excellent, and when it is preferably 80% or more, more preferably 85% or more, a more reliable product can be obtained.

Also, the elongation is preferably 10% or more, preferably 20% or more, and more preferably 30% or more, because the toughness is excellent and appropriate flexibility is obtained.

In order to obtain the organic polymer having the elongation retention ratio of the present invention, there is a contribution based on its basic skeleton, but in addition to the method of introducing a substituent into the side chain as described above, the content of impurities is particularly high. Deterioration due to an ionic compound having a positive or negative charge in an aqueous solution has a great influence, and it is effective to remove this effectively. Especially IA and II of the periodic table
The influence of A, VIIB group, especially IA group ions is great.
These ionic compounds contained in the film are 3000
It is good to be below ppm, preferably below 100 ppm, and more preferably below 10 ppm. In order to reduce the amount of ionic impurities in the film, the raw material purity, the selection of additives, and the selection of polymerization conditions are important, but the method described below can also be used in the film forming step.

The strength retention of the film of the present invention is preferably 70% or more, more preferably 80% or more, and the Young's modulus retention is preferably 70% or more, more preferably 80% or more. It is preferable because the characteristics of 1) can be utilized, and the margin in product design can be increased.

Further, the present invention is a film which can be suitably used for FPC. At this time, the film also needs a high breakdown voltage, and the breakdown voltage is 100 k.
V / mm or more, preferably 150 kV / mm or more. Removal of impurities such as ions contained in the film is effective for the method for obtaining such a film, and in the polyamide film suitable for the present invention, the structure represented by the general formula (I) or the general formula (II) is used. It is preferable to have a nuclear substituent in since it further improves the dielectric breakdown voltage.

When the film of the present invention is extracted with methylene chloride, the extraction residue is preferably 0.2% by weight or less. If a large amount of low-molecular-weight components that can be extracted with methylene chloride remain in the film, there will be problems such as peeling due to poor adhesion to the wiring pattern that is deposited under high temperature and high humidity and formed on the film surface, and other configurations. . It also causes a decrease in the dielectric breakdown voltage.

The film of the present invention has a tensile Young's modulus E20 in at least one direction at 20 ° C. and 60% relative humidity of E20 ≧ 700 kg / mm ² , more preferably E20 ≧.
900 kg / mm ² , more preferably E20 ≧ 1000 kg / mm
² is good. As for the direction of tensioning, it does not matter if the longitudinal direction or the width direction is tempered. The degree of tensioning is not particularly limited, but considering characteristics such as elongation and tear resistance,
It is practical that the tensile Young's modulus EMD in the longitudinal direction and the tensile Young's modulus ETD in the width direction are in the range of 0.5 ≦ EMD / ETD ≦ 2. The film of the present invention may be used in response to the demand for thinning, and has a high Young's modulus (E20 ≧ 70) in order to withstand tension applied during processing or use.
It is required to have 0 kg / mm ² ). If the Young's modulus is lower than this range, the film stretches, causing problems such as disconnection.

The thickness of the film of the present invention is preferably 5 to
The thickness is preferably 200 μm, more preferably 10 to 100 μm, still more preferably 10 to 50 μm.

The heat shrinkage of the film of the present invention at 250 ° C. is 1% or less, preferably 0.5% or less. The present invention cannot be used as a product because it shrinks and wrinkles when heated by immersion in a solder bath or the like.

Further, the film of the present invention is 100% under load.
The dimensional change rate at 10 ° C. for 10 minutes is preferably 1% or less, more preferably 0.5% or less. When the content is 1% or less, the dimensional change of the film under temperature change or tension can be reduced, and a highly reliable product can be obtained.

The water vapor transmission rate of the film of the present invention is 2.0.
(G / m ² /24hr/0.1mm) or less, preferably when is 1.0 (g / m ² /24hr/0.1mm) or less, high elongation retention, and excellent insulating properties FPC Can be obtained.

The film of the present invention may be laminated and may be composed of the same polymer species or different polymer species. In addition, it is preferable that the above-mentioned characteristics are satisfied even when a laminated film is formed.

In the present invention, the substrate film may preferably contain particles for various purposes.

The type of such particles is not particularly limited, but for example, SiO ₂ , TiO ₂ , TiN, A
Examples thereof include inorganic particles and organic particles such as l ₂ O ₃ , ZrO ₂ , zeolite, and other fine metal powders.

The content of particles contained in the film is 0.01 to 40% by weight, preferably 0.05 to 20.
It is good if it is a weight%.

The present invention can be preferably used as a base film for FPC. As a method for obtaining the FPC, a known method can be used. For example, a method of etching a copper foil adhered via an adhesive layer or a metal wiring layer is formed on a base film by sputtering or electroless plating. Examples include a method of forming a copper wiring layer by electrolytic plating and a method of pressure-bonding the copper wiring layer. In addition, a corona discharge treatment is preferable for the base film to improve the adhesion of the wiring layer,
A plasma treatment, a treatment with a chemical solution, or a treatment for facilitating adhesion such as coating can be performed. It goes without saying that these can be applied to one side or both sides of the base film. Further, after forming the circuit pattern, a protective film may be provided with a cover film, a cover resist or the like.

Next, the method for producing the film of the present invention will be specifically described by taking an aromatic polyamide as an example from the group of polymers capable of most preferably achieving the object of the present invention, but the present invention is not limited thereto. .

Examples of the method for obtaining the aromatic polyamide include a low temperature solution polymerization method, an interfacial polymerization method, a melt polymerization method and a solid phase polymerization method. In the present invention, a solution system, particularly a low temperature solution polymerization method is used. It is suitable because polymerization is easily obtained as a highly rigid base material.

As the polymerization solvent, known solvents such as N-methylpyrrolidone (NMP) and dimethylacetamide (D
An aprotic organic polar solvent such as MAc) or dimethylformamide (DMF) is used. At this time, impurities such as water in the polymerization solvent must be removed as much as possible, and the water content is 200 ppm or less, preferably 100 ppm or less, and more preferably 50 ppm or less. Further, lithium chloride, lithium bromide, calcium chloride or the like may be added as a dissolution aid. Then the diamine and acid chloride are added. In the case of aromatic polyamide, the equivalence of diamine and acid chloride is very important for increasing the degree of polymerization, but when it is necessary to adjust the degree of polymerization, the diamine component is excessive because it has excellent thermal stability. It is preferable to use
Further, terminal blocking can be preferably carried out using benzoyl chloride or the like.

Although the acid chloride is often decomposed due to other factors such as moisture, the purity of the acid chloride used in the present invention is preferably 99.0% or more.

Further, it is preferable to use a reaction vessel which can be stirred as efficiently as possible.

When acid chloride and diamine are used as monomers in the polymer solution, hydrogen chloride is produced as a by-product. When neutralizing this, an inorganic solvent such as calcium hydroxide, calcium carbonate or lithium carbonate is used. Solubilizers and organic neutralizing agents such as ethylene oxide, propylene oxide, ammonia, triethylamine, triethanolamine and diethanolamine are used. Generally, these neutralizing agents also cause deterioration of mechanical properties, but as will be described later, the contained impurities can be effectively removed by optimizing the film forming process.

The polymer solution obtained by the above method has a high degree of polymerization and a low degree of dispersion as a result of uniform progress of polymerization, and the value obtained by dividing the number average molecular weight by the weight average molecular weight is The range of 1.2 or more and 3.5 or less, which is suitable for the present invention, is more preferably 1.2 or more and 2 or less.

These polymer solutions may be used directly as a film-forming stock solution, or the polymer may be isolated once and then redissolved in the above organic solvent or an inorganic solvent such as sulfuric acid to prepare a film-forming stock solution. Good, however, the inorganic solvent itself has a risk of lowering the elongation retention rate when it remains in the film, and therefore an organic solvent system should be used as much as possible. Further, the polymer concentration is preferably about 2 to 40% by weight.

In order to obtain the aromatic polyamide or aromatic polyimide film of the present invention, the intrinsic viscosity of the polymer (0.5 g of the polymer in 100 ml of a solution in sulfuric acid is used as a 3% solution).
The value measured at 0 ° C.) is preferably 0.5 or more.

The method of adding particles is not particularly limited, but a method of adding particles dispersed in a solvent can be mentioned. The solvent is preferably the same as that used for film formation, but other solvents may be used unless particularly adverse effects are observed. Further, additives such as a dispersion aid may be used in these solvents within a range that does not adversely affect dispersion. To disperse the particles, a stirring disperser, a ball mill, an ultrasonic disperser or the like is used to adjust the particle size and the degree of aggregation.

The dispersed particles are mixed with the above-mentioned polymer solution. In mixing, they may be added to a solvent before polymerization, added after polymerization, or added at the time of preparing a polymer solution, and further just before casting. It is important that it is uniformly dispersed in the undiluted solution from the viewpoint of ensuring runnability.

The stock solution for film formation prepared as described above is formed into a film by a so-called solution film forming method. The solution film-forming method includes a dry-wet method, a dry method, a wet method, and the like, and the film may be formed by any method, but the dry method is not general because it cannot remove nonvolatile impurities. The dry-wet method will be described below as an example.

When a film is formed by a dry-wet method, the stock solution is extruded from a spinneret onto a support such as a drum or an endless belt to form a thin film, and then the solvent is scattered from the thin film layer until the thin film has self-holding property. To do. Drying conditions are, for example:
Room temperature to 220 ° C, within 60 minutes, preferably room temperature to
It can be performed in the range of 200 ° C. The frequency of surface defects of the drum and endless belt used in this drying step can be controlled. For example, the frequency of surface defects having a diameter of 30 μm or more is 0.001 to 0.02 pieces / mm ² , preferably 0.002. It is enough to be up to 0.015 pieces / mm ² . The film after the dry process is peeled from the support and introduced into the wet process, but in order to effectively remove the impurities in the wet process, the polymer concentration in the film should be within the range that does not lose the self-holding property. Is preferably as low as possible, and if it is 50% or less, the purpose can be easily achieved. The peeled film is desalted and desolvated in the same manner as the above-mentioned wet method, and further stretched, dried and heat-treated to form a film.

In this process, the wet process and the stretching / heat treatment process play important roles. By controlling the wet process,
A substance that causes deterioration of the elongation retention rate can be discharged to the outside of the system to obtain a more suitable film.

Although water may be used as a desolvent in this step, a mixed medium of water and an organic solvent can be preferably used. At this time, the organic solvent is water-soluble, and preferably an aprotic organic polar solvent such as N-methylpyrrolidone (NMP), dimethylacetamide (DMAc), dimethylformamide (DMF) is preferable, and the composition ratio is similar to that of the polymerization solvent. The use of a plurality of baths having different values can more preferably achieve the object of the present invention. In addition, if the temperature of the bath is appropriate, the speed advantage is high, and if the temperature is 60 ° C. or higher, the purpose can be more easily achieved.

Further, a suitable stretching / heat treatment step gives a more ordered high-order structure, and contributes to improvement of elongation retention and heat shrinkage. Stretching is carried out at a stretch ratio of 0.8-
The area ratio is preferably 4.0 (the area magnification is defined as the value obtained by dividing the area of the film after stretching by the area of the film before stretching. 1 or less means relaxing), and more preferably 1 0 to 3.0. Furthermore, 200 ℃ ~ 5
Heat treatment at a temperature of 00 ° C, preferably 250 ° C to 400 ° C for a few seconds to a few minutes further improves the elongation retention rate. After stretching, cooling is preferably performed at a rate of 50 ° C./second or less.

The film of the present invention may be a laminated film. For example, in the case of two layers, the polymerized aromatic polyamide solution is divided into two, and different particles are added, respectively, and then laminated. The same applies to the case of three or more layers.
As a method of stacking these, there are known methods such as stacking in a die, stacking in a composite tube, and a method in which one layer is once formed and then another layer is formed thereon.

[0050]

EXAMPLES The methods of measuring physical properties and evaluating effects of the present invention are as follows.

(1) Tensile Strength, Elongation, Young's Modulus Measured using an Instron type tensile tester. The test piece is 10 mm wide and 50 mm long, and the pulling speed is 300 mm / min. Further, a constant temperature and constant humidity tank was used for the preparation of the E20 sample, and the sample whose temperature and humidity had been adjusted for 48 hours was taken out from the tank and quickly measured.

(2) Tensile Strength, Elongation, Young's Modulus, Retention Ratio Several cut films were sealed in a sealed tube by adding a small amount of water (however, having a liquid layer at 155 ° C.). The treatment was carried out in an oven for 4 days. Next, after cooling to room temperature, the seal was opened and each physical property was measured by the above-mentioned methods. Each retention rate was calculated by the following formula.

(Strength retention rate) = (strength after treatment) / (strength before treatment) × 100 (%) (elongation retention rate) = (elongation after treatment) / (elongation before treatment) × 100 (%) (Young's modulus retention rate) = (Young's modulus after treatment) / (Young's modulus before treatment) × 100 (%) (3) Thermal shrinkage The film is cut into a width of 10 mm and a length of 250 mm and cut from both ends. A test piece with a test length of 200 mm was created by marking the position of 25 mm, heated in an atmosphere of 250 ° C. for 10 minutes, and allowed to cool, and the length was measured to calculate the heat shrinkage rate by the following formula.

(Test length (mm) -length after heating (mm)) / (test length (mm)) × 100 (%) (4) Ion content The cation and anion are shown in (3-1) below. And (3-2)
And the sum was defined as the ion content.

(4-1) Qualitative and quantitative determination of metal ions 0.7 g of the film was precisely weighed in a platinum crucible and ashed at a temperature of 550 ° C. or higher. The ash was dissolved in nitric acid and hydrofluoric acid, and the volume was adjusted to a constant volume with dilute nitric acid. For this constant volume solution, K and Na were determined by atomic absorption spectrometry, and the other components were I
It was analyzed by CP emission spectrometry. The unit ppm is μg / g.

(4-2) Anion amount 20 g of the film was precisely weighed and refluxed in hot water for 24 hours to extract the ionic compound. Then, the extract was quantified by ion chromatography based on a calibration curve prepared in advance. The unit ppm is μg / g.

(5) Humidity expansion coefficient Dehumidification (humidity 30% R in a constant temperature and humidity chamber kept at 25 ° C.)
H) and when humidified (humidity 90% RH), the film lengths at the time when equilibrium was reached were read and obtained by the following formula.

(Film elongation (mm)) / (Test length (mm)) / 60 (6) Water vapor transmission rate Honeywell's high-speed water transmission rate measuring device (model: W
825) or JIS Z-0208.

(7) Bending / bending test Using the MIT bending resistance tester manufactured by Toyo Seiki Co., Ltd. for the sample subjected to the treatment described in (2) above, a sample cut into a thickness of 15 μm and a width of 1 cm was subjected to a load of 500 g. 10
A bending test was performed 10,000 times to evaluate whether or not the film was cut.

◯: The film is not cut. X: The film was broken.

(8) Wrinkle resistance test The film was immersed in a solder bath heated to 250 ° C. to evaluate the occurrence of wrinkles.

◯: No significant change in appearance of the film is observed. X: Large wrinkles can be confirmed.

Examples 1 to 4 and Comparative Examples 1 to 3 However, the respective abbreviations shown in the raw material column are as follows. The number before each abbreviation symbol indicates the substitution site of the substituent. (Example: 3,3'-DOB: 3,3'-dimethoxybenzidine) Aromatic diamine component: PA: Paraphenylenediamine CPA: Chloroparaphenylenediamine DOB: Dimethoxybenzidine DAE: Diaminodiphenyl ether acid chloride component: TPC: Terephthalo Ilchloride CTPC: Chloroterephthaloyl chloride Example 1 2-CPA corresponding to 80 mol% of N-methylpyrrolidone (NMP) as an aromatic diamine component, and 20 mol%
4,4'-DAE corresponding to
2-CTPC corresponding to mol% was added and stirred for 2 hours to complete the polymerization. Neutralize this with lithium hydroxide,
An aromatic polyamide solution having a polymer concentration of 10% by weight and a viscosity of 2900 poise was obtained.

This polymer solution was passed through a 5 μm-cut filter, cast on a SUS belt, heated with hot air at 180 ° C. for 2 minutes to evaporate the solvent, and a film having self-holding property was formed on the belt. Was continuously peeled off. Next 65 ° C
Water / NMP ratio kept at 1/1, 3/1, 5 /
The film was introduced into a plurality of water tanks having a concentration ratio of 1 and 10/0 to extract the residual solvent and inorganic salt, and the water was dried and heat-treated at 280 ° C. with a tenter to obtain a thickness of 1
A 0 μm aromatic polyamide film was obtained. During this period, the film was stretched 1.1 times and 1.2 times in the width direction and dried at 280 ° C. for 1.5 minutes and heat treated, and then slowly cooled at a rate of 20 ° C./sec.

The Young's modulus E20 of this film is 1100 kg
/ Mm ² , Young's modulus retention rate is 88%, strength is 40 kg / m
m ² , strength retention 87%, elongation 40%, elongation retention 82%, heat shrinkage 0.1%, ion content 1 pp
m, the humidity expansion coefficient is 10 × 10 ⁻⁶ , and the water vapor transmission rate is 0.
It was ² g / m 2/24 hr / 0.1 mm.

The bending resistance and wrinkle resistance of this film were good.

Comparative Example 1 The procedure of Example 1 was repeated except that the polymer solution used in Example 1 was used and the treatment temperature in the tenter was 120 ° C.
A μm aromatic polyamide film was obtained.

The Young's modulus E20 of this film is 520 kg /
mm ² , Young's modulus retention rate is 85%, strength is 27 kg / mm ² ,
Strength retention is 82%, elongation is 48%, elongation retention is 82
%, Thermal contraction rate 4.8%, ion content 1 ppm, humidity expansion coefficient 12 × 10 ⁻⁶ , water vapor permeability 0.4 g /
m was ^{2 /24hr/0.1mm.}

Although the film had good bending resistance, a large number of wrinkles were observed in the evaluation of wrinkle resistance.

Example 2 N-methylpyrrolidone (NMP), 4,4'-DOB corresponding to 80 mol% as an aromatic diamine component, and 20
4,4'-DAE corresponding to mol% was dissolved, 2-CTPC corresponding to 97 mol% was added thereto, and the mixture was stirred for 2 hours to complete the polymerization, and the film was stretched in the longitudinal direction of 1. Example 1 except for multiplying 1 times and 1.45 times in the width direction
An aromatic polyamide film having a thickness of 10 μm was obtained in the same manner as in.

The Young's modulus E20 of this film is 1300 kg
/ Mm ² , Young's modulus retention rate 89%, strength 36 kg / m
m ² , strength retention 85%, elongation 25%, elongation retention 87%, heat shrinkage 0.1%, ionic content 1 pp
m or less, 8 × 10 ^-6 humidity expansion coefficient, water vapor transmission rate was 0.2g / m ² /24hr/0.1mm.

The bending resistance and wrinkle resistance of this film were good.

Comparative Example 2 The same polymer solution as obtained in Example 2 was passed through a 5 μm-cut filter and then cast on a SUS belt at 200 ° C.
Was heated with hot air for 5 minutes to evaporate the solvent, and the self-supporting film was continuously peeled from the belt. Then 70
The residual solvent and the inorganic salt were extracted for 1/2 of the extraction time in Example 2 in a water bath maintained at 0 ° C., and then an aromatic polyamide film having a thickness of 6 μm was obtained in the same manner as in Example 1. .

The Young's modulus E20 of this film is 1200 kg
/ Mm ² , Young's modulus retention rate 81%, strength 31 kg / m
m ² , strength retention 80%, elongation 25%, elongation retention 25%, heat shrinkage 0.2%, ionic content 500
ppm, 8 × 10 ^-6 humidity expansion coefficient, water vapor transmission rate was 0.4g / m ² /24hr/0.1mm.

This film had good wrinkle resistance but poor flex resistance.

Example 3 PA corresponding to 100 mol% as an aromatic diamine component was dissolved in NMP and cooled to -10 ° C. 10 to this
Polymerization was completed by adding TPC corresponding to 0 mol% and stirring for 2 hours while pulverizing the solid precipitated during the polymerization into small pieces. This solid slurry was precipitated in water, washed with water, and dissolved in concentrated sulfuric acid to obtain an aromatic polyamide solution. After passing this polymer solution through a 5 μm-cut filter, the polymer solution was cast onto a gold-plated belt and allowed to stand until it became an isotropic solution in an atmosphere of 85% RH, and then it was introduced into a water tank to be solidified. Was removed from the belt, washed with water, and then passed through a 0.1% aqueous solution of caustic soda for neutralization, and then passed through a hot water bath at 70 ° C. so that the anion concentration in the film was 30 ppm. In the same manner as in 1, the film was stretched 1.1 times in the longitudinal direction and 1.45 times in the width direction to obtain an aromatic polyamide film having a thickness of 10 μm.

The Young's modulus E20 of this film is 1480 kg
/ Mm ² , Young's modulus retention rate is 84%, strength is 40 kg / m
m ² , strength retention 81%, elongation 20%, elongation retention 78%, heat shrinkage 0.15%, ionic content 50
ppm, 25 × 10 ^-6 humidity expansion coefficient, water vapor transmission rate was 2g / m ² /24hr/0.1mm.

The bending resistance and wrinkle resistance of this film were good.

Example 4 An aromatic polyamide film having a thickness of 6 μm was obtained in the same manner as in Example 1 except that aluminum triethoxide was used as the neutralizing agent.

It was difficult to stably form this film, probably because aluminum chloride produced during neutralization was hydrolyzed during film formation.

The Young's modulus E20 of this film is 1150 kg
/ Mm ² , Young's modulus retention rate is 85%, strength is 40 kg / m
m ² , strength retention rate is 84%, elongation rate is 25%, elongation retention rate is 82%, heat shrinkage rate is 0.1%, ionic species are mostly aluminum, total ion content is 7,000 ppm, humidity expansion coefficient Is 10 × 10 ^-6 , water vapor transmission rate is 1.0 g / m
Was ^{2 /24hr/0.1mm.}

The bending resistance and wrinkle resistance of this film were good.

Comparative Example 3 In the same manner as in Example 3, except that the polymer solution obtained in Example 3 was passed through a 5 μm-cut filter and then introduced into a water tank for 1/3 of the time for coagulation. An aromatic polyamide film having a thickness of 10 μm was obtained.

The Young's modulus E20 of this film is 1400 kg
/ Mm ² , Young's modulus retention rate is 70%, strength is 38 kg / m
m ² , strength retention 72%, elongation 21%, elongation retention 23%, heat shrinkage 0.2%, ionic content 350
0 ppm, 30 × 10 ^-6 humidity expansion coefficient, water vapor transmission rate was 4g / m ² /24hr/0.1mm.

The film had good wrinkle resistance, but poor flex resistance.

Comparative Example 4 The same evaluation was performed using an aromatic polyimide film “Kapton” (thickness 10 μm) manufactured by DuPont.

The Young's modulus E20 of this film is 300 kg /
mm ² , Young's modulus retention rate is 83%, strength is 16.8 kg / mm
^2. Strength retention rate is 74%, Elongation rate is 70%, Elongation retention rate is 41%, Thermal shrinkage rate is 0.4%, Humidity expansion coefficient is 22x1.
0 ^-6, water vapor transmission rate was 20g / m ² /24hr/0.1mm.

There was no problem in wrinkle resistance of this film, but it was inferior in bending resistance.

Comparative Example 5 Polyparaphenylene sulfide film manufactured by Toray Industries, Inc. "
Torelina ″ (thickness 10 μm) was used and evaluated in the same manner.

The Young's modulus E20 of this film is 400 kg /
mm ² , Young's modulus retention rate is 100%, strength is 22 kg / m
m ² , strength retention rate is 87%, elongation rate is 70%, elongation retention rate is 76%, heat shrinkage rate is 5.5%, and humidity expansion coefficient is 1.
5 × 10 ^-6, the water vapor transmission rate ^{2.5g / m 2 / 24hr / 0} .
It was 1 mm.

The flex resistance of this film was good, but the wrinkle resistance was poor.

Comparative Example 6 A polyethylene terephthalate film “Lumirror” (10 μm in thickness) manufactured by Toray Industries, Inc. was used and evaluated in the same manner.

The Young's modulus E20 of this film is 400 kg /
mm ² , strength was 25 kg / mm ² , elongation was 130%, and heat shrinkage was 5% or more, but after the treatment, each retention could not be determined because it was brittle. Note the humidity expansion coefficient 12 × 10 ^-6 of this film, water vapor transmission rate of 7g / m ² / 24hr
It was /0.1 mm.

This film was inferior in both flex resistance and wrinkle resistance.

[0095]

[Table 1]

[0096]

INDUSTRIAL APPLICABILITY The present invention is obtained as a film with almost no loss of the original characteristics of the organic polymer even under high temperature and high humidity, that is, in a harsh environment. It can be preferably used in exposed applications.

Claims (3)

[Claims] 1. An elongation retention rate of 70% or more when treated for 4 days in a high-pressure steam atmosphere at 155 ° C.,
A film made of an organic polymer, which has a heat shrinkage ratio at 50 ° C. of 1% or less. 2. The film according to claim 1, wherein the organic polymer is an aromatic polyamide. 3. A flexible printed circuit board comprising an electric circuit formed on at least one surface of the film according to claim 1.