JP2001244587A - Flexible printed board and biaxial-orientation film for it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a biaxial-orientation film for a flexible printed board, together with the flexible printed board comprising the film, which is excellent in dimensional stability and flatness for use under high temperature. SOLUTION: The biaxial-orientation film for the flexible printed board is provided which comprises polyimide and polyester at 1-50 wt.%. The biaxial- orientation film has a thermal contraction coefficient of 0.5% or less when hated at 150 deg.C for 30 minutes while 3.0% or less when heated at 200 deg.C for 10 minutes. The biaxial-orientation film is used for the flexible printed board.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a biaxially oriented film for flexible printed circuit boards made of polyester and polyimide, and a flexible printed circuit board using the biaxially oriented film. More specifically,
The present invention relates to a biaxially oriented film for a flexible printed circuit board comprising a polyester and a polyimide, wherein the polyimide is contained in an amount of 1% by weight or more and 50% by weight or less, and has excellent dimensional stability at high temperatures and excellent flatness. The present invention relates to a flexible printed circuit board.

[0002]

2. Description of the Related Art Conventionally, a polyimide film is generally used as a film for a flexible printed circuit board because of its good adhesion to a circuit and heat resistance in soldering when mounting circuit components. Have been. Also, polyester films have been used as films for flexible printed circuit boards because they have good chemical resistance and insulation properties and are inexpensive.

[0003] In recent years, computer parts, printers and other equipment parts, furniture, and automobiles have been digitized, and it has been particularly desired to provide inexpensive flexible printed wiring boards and the like. Furthermore, notebook personal computers, mobile phones, I
The spread of portable electric and electronic devices such as C-cards has been rapidly advanced, and at the same time, these portable devices have been actively miniaturized, and accordingly, miniaturization and high-density of circuits have been required. . While such advanced technology is required, competition for price reduction due to the recent spread of portable devices is increasing, but as long as polyimide films that have been used conventionally as films for flexible printed circuit boards are used, In fact, it has become difficult to lower prices. In addition to the fact that it is difficult to reduce the price of the polyimide film, it also has a high hygroscopic property, a large dimensional change at the time of moisture absorption, and a decrease in the adhesive strength to metal if the humidity control of the film during processing is neglected. This causes inconvenience, and there is a problem that humidity control of the film becomes indispensable and hinders improvement of production efficiency. Further, in the case of a polyimide film, if the solvent used for dissolving the polyimide resin used in the production remains in the film, a problem such as deterioration of the quality of the circuit board may be caused.

On the other hand, a polyester film used as a film for a flexible printed circuit board is inexpensive and suitable for cost reduction. However, dimensional changes due to heat treatment in the process of forming a membrane switch and soldering during mounting of circuit components are required. There is a problem that the flatness of the film after the attachment is deteriorated, and it cannot be used as a recent high-density circuit board film. In recent years, even when used as an antenna substrate of a contact / contactless IC card, which is expected to rapidly spread instead of a magnetic card, the antenna substrate is deformed due to the heat history received in the processing process, and disconnection occurs. There is a problem. In addition, due to advances in soldering technology when mounting circuit components, recent reflow soldering allows lower soldering temperatures compared to conventional flow soldering, but polyester films still lack heat resistance. . On the other hand, at present, the polyimide film has excessive solder heat resistance.

As a method for imparting heat resistance to such a film for a flexible printed board, Japanese Patent Application Laid-Open No.
No. 93991 discloses a flexible printed board film made of polyethylene-2,6-naphthalate (PE) having higher heat resistance than conventional polyethylene terephthalate.
N) It has been proposed to make a film. However, in the case of a PEN film, the film is easily torn in the processing step, and the dimensional stability at high temperatures required for high-density circuits is not always sufficient. What is being done is the current state of the art.

[0006]

SUMMARY OF THE INVENTION The present invention is directed to a biaxially oriented film for a flexible printed circuit board which solves the above-mentioned problems and has excellent dimensional stability and flatness in use at a high temperature. To provide a flexible printed circuit board.

[0007]

Means for Solving the Problems The present inventors diligently studied to solve the above problems. As a result, surprisingly, the biaxially oriented film for flexible printed circuit boards comprising 1% by weight or more and 50% by weight or less of polyimide and polyester is excellent in dimensional stability and flatness in use at high temperature and relatively inexpensive. This led to the present invention.

That is, the present invention relates to a biaxially oriented film for a flexible printed board comprising polyester and polyimide, wherein the polyimide is contained in an amount of 1% by weight or more and 50% by weight or less. The main feature is a biaxially oriented film and a flexible printed board made of the film.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The polyester used in the present invention is a polyester containing aromatic dicarboxylic acid, alicyclic dicarboxylic acid or aliphatic dicarboxylic acid and diol as main components.

As the aromatic dicarboxylic acid component, for example, terephthalic acid, isophthalic acid, phthalic acid, 1,4-
Naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, benzophenonedicarboxylic acid, 4,4′-diphenyldicarboxylic acid,
3,3′-diphenyldicarboxylic acid, 4,4′-diphenyletherdicarboxylic acid, 4,4′-diphenylsulfonedicarboxylic acid and the like can be used, and among them, terephthalic acid, phthalic acid, 6-Naphthalenedicarboxylic acid can be used.

As the alicyclic dicarboxylic acid component, for example, hexahydroterephthalic acid, 1,3-adamantanedicarboxylic acid, cyclohexanedicarboxylic acid and the like can be used. As the aliphatic dicarboxylic acid component, for example, adipic acid, succinic acid, azelaic acid, suberic acid, sebacic acid, dodecanedioic acid and the like can be used. One of these acid components may be used alone, or two or more thereof may be used in combination. Further, an oxyacid such as hydroxyethoxybenzoic acid may be partially copolymerized.

The diol component includes, for example, chlorohydroquinone, methylhydroquinone, 4,4 '
Aromatic diols such as dihydroxybiphenyl, 4,4'-dihydroxydiphenylsulfone, 4,4'-dihydroxydiphenylsulfide, 4,4'-dihydroxybenzophenone, p-xylene glycol, ethylene glycol, 1,2-propane Geols, 1,3
-Propanediol, neopentyl glycol, 1,3
-Butanediol, 1,4-butanediol, 1,5-
Pentanediol, 1,6-hexanediol, 1,2
-Cyclohexane dimethanol, 1,3-cyclohexane dimethanol, 1,4-cyclohexane dimethanol-
, Diethylene glycol, triethylene glycol,
Polyalkylene glycol, 2,2′-bis (4′-β-
(Hydroxyethoxyphenyl) propane and the like, among which ethylene glycol,
1,4-butanediol, 1,4-cyclohexanedimethanol, diethylene glycol and the like can be used, and particularly preferably, ethylene glycol and the like can be used. These diol components may be used alone or in combination of two or more. In addition, polyesters include trimellitic acid, pyromellitic acid, glycerol,
Other compounds such as polyfunctional compounds such as pentaerythritol, 2,4-dioxybenzoic acid, lauryl alcohol and phenyl isocyanate are copolymerized within a range where the polymer is substantially linear. May be. In addition to the glycol component, aromatic hydroxycarboxylic acids such as p-hydroxybenzoic acid, m-hydroxybenzoic acid, and 2,6-hydroxynaphthoic acid, and p-aminophenol and p-aminobenzoic acid are used in such an amount that the object of the present invention is not impaired. If it is a small amount, it can be further copolymerized.

In the present invention, as the polyester, it is preferable to use at least one selected from the group consisting of polyethylene terephthalate, polyethylene-2,6-naphthalate and a copolymer or modified product thereof. The polyethylene terephthalate and polyethylene-2,6-naphthalate constituting the polyester film of the present invention are polymers containing at least 80 mol% of terephthalic acid or 2,6-naphthalenedicarboxylic acid as an acid component. As for the acid component, a small amount of another dicarboxylic acid component may be copolymerized, and ethylene glycol is used as a main diol component, but another diol component may be added as a copolymer component.

In the present invention, the polyester is preferably contained in an amount of 50% by weight or more and 99% by weight or less. It is more preferably 60% by weight or more and 98% by weight or less, further preferably 65% by weight or more and 97% by weight or less, and most preferably 7% by weight or less.
0 to 95% by weight. When the polyester contained in the film is at least 50% by weight and at most 99% by weight, the compatibility between the polyester and the polyimide will be good, and the dimensional stability in use at high temperatures will be high.

The intrinsic viscosity of the polyester used in the present invention is preferably 0.5 or more from the viewpoints of melt kneading with polyimide, film forming property and decomposability during melt extrusion.
4 dl / g or less, more preferably 0.55 or more and 1.2 d
1 / g or less, most preferably 0.6 to 1.0 dl / g
It is as follows.

The polyimide in the present invention is a melt-moldable polymer containing a cyclic imide group, and is not particularly limited as long as it can be used for the purpose of the present invention, but may be aliphatic, alicyclic or aromatic. Polyetherimides containing a system ether unit and a cyclic imide group as repeating units are more preferred. For example, U.S. Patent Nos. 4,141,927, 2,622,678 and 2,606,912.
No. 2,606,914, Patent 2,596,565
No. 2,596,566, Japanese Patent No. 2,598,478, Japanese Patent No. 2,598,536, Japanese Patent No. 2,599,171, Japanese Unexamined Patent Publication No. 9-48852, Japanese Patent No. 2,565,556, Japanese Patent No. 2,564,636, Japanese Patent No. 2,564,637 and Japanese Patent. No. 2,563,548, Japanese Patent No. 2,563,547, Japanese Patent No. 2,558,341, Japanese Patent No. 2,558,339, and Japanese Patent No. 2,834,580. Further, as long as the effect of the present invention is not impaired, the cyclic imide is added to the main chain of the polyimide,
Structural units other than ether units, for example, aromatic, aliphatic, alicyclic ester units, oxycarbonyl units and the like may be contained.

As specific examples of the polyetherimide that can be preferably used in the present invention, a polymer represented by the following general formula can be exemplified.

[0018]

Embedded image (Where R ₁ is a divalent aromatic or aliphatic residue having 6 to 30 carbon atoms; R ₂ is a divalent aromatic residue having 6 to 30 carbon atoms; From the group consisting of alkylene groups having 2 to 20 carbon atoms, cycloalkylene groups having 2 to 20 carbon atoms, and polydiorganosiloxane groups chain-stopped with alkylene groups having 2 to 8 carbon atoms. It is a selected divalent organic group.) Examples of R ₁ and R ₂ include aromatic residues represented by the following formula group.

[0019]

Embedded image In the present invention, from the viewpoints of compatibility with the polyester, cost, melt moldability, and the like, a polyetherimide having a glass transition temperature of 350 ° C. or lower, more preferably 250 ° C. or lower is preferable, and has a structural unit represented by the following formula. And a condensate of 2,2-bis [4- (2,3-dicarboxyphenoxy) phenyl] propane dianhydride with m-phenylenediamine or p-phenylenediamine. Examples of the polyetherimide include “Ultem” (registered trademark) 1000 or 500 manufactured by GE Plastics.
0 series ".

[0020]

Embedded image Or

[0021]

Embedded image In the present invention, it is necessary that the polyimide is contained in an amount of 1% by weight or more and 50% by weight or less. Preferably it is 2% by weight or more and 40% by weight or less, more preferably 3% by weight or more and 35% by weight or less, most preferably 5% by weight or more and 30% by weight or less. If the amount of polyimide contained in the film is less than 1% by weight, the heat shrinkage of the film will be poor, and the dimensional stability and flatness will be poor. Also, 50% by weight of polyimide
Exceeding the above will cause a decrease in stretchability, and a decrease in the compatibility with the polyester, which will likely cause the extruded polymer to contain unmelted materials. Therefore, it becomes difficult to obtain the biaxially oriented film of the present invention.

The polyimide content in the film can be determined by a known measurement. next,
An example is shown in which the content of polyetherimide in a film that can be preferably used in the present invention is determined, but the present invention is not limited to such an example.

The weighed film (Xg) is dissolved in a mixed solution of hexafluoroisopropanol and chloroform and then reprecipitated with acetone to obtain polyester and polyetherimide powder particles. The polyetherimide component is eluted in chloroform from the obtained powdery particles, filtered out, and weighed (Yg). The content of the polyetherimide contained in the film is calculated from the following equation (1).

Polyetherimide content = Y / X × 100 [%] (1) In the biaxially oriented film of the present invention, other than polyester and polyimide, as long as the effects of the present invention are not impaired. A thermoplastic resin may be included. Examples of the thermoplastic resin include polyamide, polyethylene, polypropylene, polyvinyl chloride, polyvinylidene chloride, respective copolymers, and blends thereof.

The biaxially oriented film for a flexible printed board of the present invention needs to be a biaxially stretched film.
In an unstretched film or a uniaxially stretched film, the mechanical strength in the longitudinal direction or the width direction of the film is small, the dimensional stability and the flatness are deteriorated, and it is difficult to exert the effects of the present invention.

In the present invention, the glass transition temperature of the film is not particularly limited, but it is preferable that the film has a single glass transition temperature in a temperature range of 40 ° C. or more and 220 ° C. or less. More preferably 5
It is preferable that the temperature is single in a temperature range of 0 ° C. or more and 180 ° C. or less.

The glass transition temperature in the present invention is determined by JIS K from reversible specific heat or heat flux data obtained when a film is heated using a differential scanning calorimeter.
7121. When measuring the glass transition temperature of a film by differential scanning calorimetry, it is effective to apply a temperature modulation method or a high sensitivity method. here,
In the present invention, the glass transition temperature at which the reversible specific heat change detected by differential scanning calorimetry is 5 mJ / g / ° C. or less is ignored. When two or more glass transition temperatures exist by this determination method, the glass transition temperature on the low temperature side is defined as the glass transition temperature in the present invention. When the film has two or more glass transition, polyester and polyimide are not compatible in the film, and there are a large number of dispersed domains consisting of polyimide and its thermal decomposition products or reactants, etc. Should be noted that it becomes difficult to obtain the high quality film disclosed in the present invention.

When the biaxially oriented film for a flexible printed board of the present invention is heat-treated at 150 ° C. for 30 minutes, the heat shrinkage in both the longitudinal direction and the width direction is 0.1 mm.
It is preferably at most 5%. More preferably 0.3
%, More preferably 0.1% or less. When the heat shrinkage is 0.5% or less, the dimensional stability and flatness of the film are improved, which is preferable as a biaxially oriented film for a flexible printed board. Further, the difference between the heat shrinkage in the longitudinal direction and the heat shrinkage in the width direction is not particularly limited, but is preferably 0.5% or less in order to prevent deterioration in flatness.

When the biaxially oriented film for a flexible printed board of the present invention is heat-treated at 200 ° C. for 10 minutes, the heat shrinkage in both the longitudinal direction and the width direction is 3%.
The following is preferred. It is more preferably at most 2.5%, further preferably at most 2%. 3% heat shrinkage
In the following cases, the dimensional stability and flatness of the film are improved, which is preferable as a biaxially oriented film for a flexible printed board. The difference between the heat shrinkage in the longitudinal direction and the heat shrinkage in the width direction is not particularly limited, but is preferably 2.0% or less in order to prevent deterioration in flatness.

When the film of the present invention is heat-treated at 120 ° C. for 30 minutes, the heat shrinkage in the longitudinal direction and width direction of the film is preferably 0.2% or less. More preferably, the heat shrinkage is 0.1% or less, and most preferably 0.05% or less. It should be noted that if the heat shrinkage at 120 ° C. for 30 minutes exceeds 0.2%, the circuit on the antenna substrate of the IC card is likely to break due to dimensional change or deformation of the film.

The elastic modulus of the biaxially oriented film for a flexible printed board of the present invention is not particularly limited, but the elastic modulus in the longitudinal direction and the elastic modulus in the width direction are preferably 3 GPa or more and 8 GPa or less. It is preferable that the elastic modulus in the longitudinal direction and the elastic modulus in the width direction are 3 GPa or more and 8 GPa, respectively, because the dimensional stability and flatness of the film are improved. Further, the difference between the elastic modulus in the longitudinal direction and the elastic modulus in the width direction is preferably 3 GPa or less in order to prevent the deterioration of the flatness.

The intrinsic viscosity of the biaxially oriented film for a flexible printed board of the present invention is not particularly limited, but is preferably 0.5 dl from the viewpoint of the strength, dimensional stability and film forming property of the film.
/ G or more and 2.0 dl / g or less. More preferably, it is 0.55 dl / g or more and 1.4 dl / g or less, most preferably, 0.6 dl / g or more, 1.2 dl.
/ G or less.

The refractive index of the biaxially oriented film for a flexible printed board of the present invention is preferably from 1.47 to 1.55, more preferably from 1.48 to 1.53, in the thickness direction. It is as follows. When the refractive index in the thickness direction is 1.47 or more and 1.55 or less, the flatness of the film is improved and a high-quality film in which wrinkles are not easily formed is preferable.

The average refractive index of the biaxially oriented film for a flexible printed board of the present invention is preferably from 1.6 to 1.63. More preferably, it is 1.61 or more and 1.63 or less. It is preferable that the average refractive index is 1.6 or more and 1.63 or less because the dimensional stability and flatness of the film are improved.

The thickness of the film of the present invention can be appropriately determined according to the intended use and purpose. In the flexible printed circuit board application targeted by the present invention, generally, 10 to 40 is used.
A film having a thickness of 0 μm is preferably used.
00 μm is more preferred, and 50 to 200 μm is even more preferred. In the antenna board constituting the IC card, 25
-100 μm is more preferable.

In the biaxially oriented film for a flexible printed board of the present invention, inorganic and organic particles and other various additives such as a plasticizer, a weathering agent, an oxidizing agent, and the like, as long as the effects of the present invention are not impaired. An inhibitor, a heat stabilizer, a lubricant, an antistatic agent, a whitening agent, a coloring agent, a conductive agent, and the like may be added. Also, a small amount of another resin may be added.

Specific examples of the inorganic particles include silicon oxide,
Oxides such as aluminum oxide, magnesium oxide, and titanium oxide; complex oxides such as kaolin, talc, and montmorillonite; carbonates such as calcium carbonate and barium carbonate; sulfates such as calcium sulfate and barium sulfate; barium titanate; Titanate such as potassium, phosphate such as tertiary calcium phosphate, dibasic calcium phosphate, and monocalcium phosphate can be used, but not limited thereto. These may be used in combination of two or more depending on the purpose.

Specific examples of the organic particles include vinyl-based particles such as polystyrene or crosslinked polystyrene particles, styrene-acrylic and acrylic crosslinked particles, styrene-methacrylic and methacrylic crosslinked particles, and the like.
Particles such as benzoguanamine / formaldehyde, silicone, and polytetrafluoroethylene can be used.However, the present invention is not limited to these.At least a part of the constituent particles is an organic polymer fine particle insoluble in polyester. Any particles may be used.
The organic particles preferably have a spherical particle shape and a uniform particle size distribution from the viewpoint of smoothness and uniformity of formation of projections on the film surface.

The particle size, blending amount, shape and the like of these particles can be selected according to the application and purpose.
The average particle diameter is preferably in the range of 0.01 μm to 2 μm, and the blending amount is preferably in the range of 0.002% by weight to 2% by weight. The method of adding these particles is not particularly limited as long as the film is formed using polyester and polyimide.For example, the particles may be added at the polymerization stage, or may be added at the time of film formation. May be.

Next, a method of manufacturing the biaxially oriented film for a flexible printed board and the flexible printed board of the present invention will be described, but the present invention is not limited to such an example.

Pellets of Ultem 1010 (hereinafter Ultem, IV = 0.68) manufactured by General Electric Co. and pellets of polyethylene terephthalate (PET) (IV = 0.85) obtained by ordinary polycondensation with 1 to 50% by weight of pellets After drying 50 to 99% by weight in a vacuum drier at 180 ° C for 3 hours or more, they are mixed and charged into an extruder, and are preferably at 280 to 340 ° C, more preferably 290 to 33 ° C.
After being melt-extruded at 0 ° C. and passed through a fiber-sintered stainless steel metal filter, the sheet is discharged from a T-die at a draft ratio of 2 to 30 into a sheet shape.
It is brought into close contact with a cooling drum at 0 ° C. to be rapidly cooled and solidified to obtain a non-oriented film. At this time, it is also preferable to form a film using a chip which is obtained by melting and kneading Ultem and PET pellets in advance and forming a master, in order to obtain the film of the present invention. However, care must be taken because if the melt extrusion is repeated, the intrinsic viscosity of the polymer (film) may be reduced and a low quality film may be obtained.

The biaxial stretching of the film can be utilized by any of the known sequential biaxial stretching or simultaneous biaxial stretching.
In order to achieve high strength, a re-longitudinal stretching method, a re-horizontal stretching method, or a multi-stage stretching method can also be preferably performed.

Specifically, first, a non-oriented film was prepared using (Tg
-20) to (Tg + 120) C, preferably (Tg)
g-15) to (Tg + 90) ° C., more preferably (Tg + 90) ° C.
g-10) to (Tg + 70) ° C., heated by a group of heating rolls in a temperature range of 1.1 to 7 times, preferably 1.5 to 6.5 times, more preferably 2.0 to 7.0 times in the longitudinal direction. 6.3
The film is stretched twice and cooled by a cooling roll group at 20 to 50 ° C.
Here, Tg represents the glass transition temperature of the polymer.
Next, the film is gripped with a clip, guided to a tenter, and stretched in the width direction. The stretching ratio is preferably 2 to 8 times, more preferably 3 to 7 times. The stretching temperature is preferably in a temperature range of (Tg-20) to (Tg + 140) ° C, and more preferably (Tg-10) to (Tg + 1).
20) ° C., more preferably Tg to (Tg + 100) ° C.
Range. This film was continuously (Tm-60)
Heat fixing is performed in a temperature range of ~ (Tm-5) ° C. Here, Tm represents the melting temperature of the polymer. The heat setting after the biaxial stretching is preferably performed in a temperature range of (Tm-30) to (Tm-5) C, and is preferably performed in a range of (Tm-15) to (Tm-5).
A temperature range of ° C. is more preferred. When the heat setting is performed at such a high temperature, the stress remaining in the film is eliminated, and the heat shrinkage is effectively reduced by the relaxation treatment performed after the heat setting, so that the film of the present invention is easily obtained. . Further, if necessary, a relaxation treatment is performed in the width direction and / or the longitudinal direction during the cooling process from the heat setting temperature.
In this case, at two or more temperatures (for example, 180 to 130)
(At 130 ° C. and 130-90 ° C.). In the widthwise relaxation process, a method of sequentially reducing the rail in which the clip travels in the widthwise direction, in the longitudinal direction relaxation method, a method of sequentially reducing the interval between the clips gripping the film end portion, and on a roll after heat fixing. Until winding, a method of cutting off both ends of the film in the middle of the heat fixing zone and reducing the take-up speed with respect to the film supply speed, a method of heating with an IR heater between two different speed rolls, A method in which the film is transported on the heating transport roll and the speed of the transport roll after the heating transport roll is reduced, while the film is transported over a nozzle that blows out hot air after heat fixing, and the take-off speed is slower than the supply speed. Method, or after winding in a film forming machine, a method of reducing the speed of the transport roll by transporting the film on a heated transport roll, or There is a method for reducing the roll speed after the heating zone than the roll speed before the heating zone while conveying the heated zone by heat oven or IR heaters,
Either method may be used, and the relaxation process is performed by setting the deceleration rate of the take-up side speed to the supply-side speed at 0.1 to 15%. Thereafter, the film is cooled to room temperature, and the film edge is removed to obtain the biaxially oriented film for a flexible printed board of the present invention.

A circuit is formed on one of the films thus obtained by laminating a copper foil with an adhesive or by screen-printing a conductive paste, and then appropriately forming a protective sheet thereon as a protective sheet. Then, the film is laminated using a peelable adhesive to form a flexible printed circuit board. When an antenna substrate of an IC card is manufactured, a circuit is formed by a method such as screen printing using a conductive paste, and a chip such as an IC or a capacitor is printed using an anisotropic conductive film or the like. Connect to When an IC card is produced, a film having an adhesive, an adhesive or the like can be stacked on both sides of the antenna substrate as necessary, and the IC card can be obtained by laminating the film.

[Method for Measuring Physical Properties and Method for Evaluating Effect] (1) Thermal Shrinkage (%) In accordance with the method specified in JIS C-2318,
The heat shrinkage in the longitudinal and width directions of the film was measured. The sampling method was the same as for the sample of the elastic modulus. A sample having a sample width of 10 mm and a sample length of 200 mm was placed in a gear oven at 120 ° C. for 30 minutes at 150 ° C. for 30 minutes.
Heat treatment was performed for three minutes at 200 ° C. for 10 minutes, and the heat shrinkage was calculated from the change in sample length by the following equation.

Heat shrinkage (%) = [(length before heat treatment−length after heat treatment) / length before heat treatment] × 100 (2) Modulus of elasticity (GPa) Method specified in JIS K-7127 According to
Using an Instron type tensile tester, 25
The temperature was measured in an atmosphere at 65 ° C. and 65% RH. The sample was cut into a strip having a length between the evaluation lines of 100 mm and a width of 10 mm. The distance between the initial tension chucks was 100 mm, and the tension speed was 200 mm / min.

(3) Refractive index Using an Abbe type 4 refractive index manufactured by Atago Co., Ltd., a polarizing plate was inserted into the eyepiece, and one drop of methylene iodide was dropped on the prism of the refractometer to obtain a refractive index of 1 The measurement prism was placed in the longitudinal direction and the width direction of the sample, and the refractive index was obtained by measuring from both the front and back surfaces of the sample. The refractive index in the thickness direction was an average value of the refractive index in the thickness direction measured from each direction and surface. The average refractive index was calculated as the average value of the refractive indexes in the longitudinal direction, the width direction, and the thickness direction.

(4) Intrinsic viscosity 0.1 g / ml in orthochlorophenol at 25 ° C.
It is a measured value in concentration. The unit is represented by dl / g.

(5) Melt viscosity Using a high-low flow tester, 280 ° C., shear rate 1
The value at 000 sec-1 is measured. The unit is [Pa
s].

(6) Glass transition temperature (Tg), melting temperature (Tm) Using a film sample, specific heat was measured by a pseudo-isothermal method under the following apparatus and conditions, and determined according to JIS K7121.

Apparatus: Temperature-modulated DSC manufactured by TA Instrument Measurement conditions: Heating temperature: 270-570K (RCS cooling method) Temperature calibration: Melting point of high-purity indium and tin Temperature modulation amplitude: ± 1K Temperature modulation period: 60 seconds Temperature rise Step: 5K Sample weight: 5 mg Sample container: Aluminum open container (22 g) Reference container: Aluminum open container (18 g) The glass transition temperature was calculated by the following equation. Glass transition temperature = (extrapolated glass transition start temperature + extrapolated glass transition end temperature) / 2 (7) Appropriate use as flexible printed circuit board The surface of the film is subjected to a surface activation treatment by corona discharge treatment, and the width is 45 cm. Cut to a size of 50 cm in length, and print a model pattern of circular contacts and markers with a diameter of 6 mm on the surface by screen printing using conductive carbon paste as conductive ink. Was dried and solidified. Coating thickness is 1
Adjusted to 5 μm. Further, for heat curing, heat treatment was performed in a hot air oven at a temperature of 150 ° C. for 30 minutes. At this time, the reference mark length (about 400 mm) of the model pattern in the width direction, the longitudinal direction, and the −45 ° direction in the longitudinal direction (Lo)
And the length (L) after curing by heat treatment was measured using a phototube type dimension measuring device, and the dimensional change rate was calculated by the following equation.

Dimensional change (%) = L / Lo × 100 The flatness of the film is measured by the following measuring method. First,
The sample is spread on a cork table, and the surface is leveled with a sponge rod to completely eliminate air between the film and the table. Then, after standing for 3 minutes, the state of the portion where the film was lifted off the table was visually observed, and judged according to the following criteria. ：: Little lifting is observed. Δ: Uplift is observed in a part of the cut edge of the film. X: Lifting is also seen in the film.

(8) Suitability for use as an antenna substrate for an IC card 20 g of silver powder having an average particle size of 5 μm and a flatness of 10 and a phenoxy resin (UCAR PKH, manufactured by Union Carbide Co., Ltd.)
C) 6.7 g butyl carbitol solution (resin concentration 33
%) In a mortar, and butyl carbitol is added as appropriate so that the viscosity becomes 100,000 centipoise at a shear rate of 240 mm / min using a B-type viscometer to obtain a conductive paste for a printed antenna circuit. Was. Then, using a screen printing machine, the paste was coiled (20 turns, length 280) into the film of the present invention (thickness 100 μm, width 54 mm, length 86 mm, corona discharge treatment on both sides).
cm, a circuit width design value of 400 μm, and a circuit space design value of 250 μm), and then preliminarily dried at 100 ° C. and then dried at 150 ° C. to obtain a printed substrate on which a printed antenna circuit was formed. . After that, further thickness 250
A 20 μm chip (IC, capacitor) is formed using an anisotropic conductive film (AC-8301, manufactured by Hitachi Chemical Co., Ltd.).
Connect to the printed antenna circuit at 0 ° C, 60kg / cm2,
A printed board on which a chip and a printed antenna circuit were formed was obtained.
The connection between the circuit and the chip on the printed circuit board obtained here was observed and judged according to the following criteria. ：: There is no breakage or disconnection of the circuit around the IC. Δ: Deformation of the circuit around the IC and slight collapse are observed. X: The circuit was broken and broken around the IC.

[0054]

The present invention will be described in more detail with reference to the following examples. However, the present invention is not limited to these examples.

(Example 1) Intrinsic viscosity 0.65 (dl /
g) polyethylene terephthalate (hereinafter referred to as “PET”, melting point: 255 ° C.) chip and General Ele
"Ultem" (registered trademark) 1010 (I
V = 0.68 polyetherimide) pellets
After drying under reduced pressure (3 Torr) at 80 ° C. for 6 hours, these pellets were mixed at a ratio of 90:10 and supplied to an extruder.
After being melt-extruded at 90 ° C. and passed through a fiber sintered stainless metal filter, it is discharged in a sheet form from a T-die at a draft ratio of 5, and the sheet is brought into close contact with a cooling drum having a surface temperature of 25 ° C. It was quenched and solidified to obtain a non-oriented film. Next, this non-oriented film was stretched 3.3 times at 90 ° C. in the longitudinal direction and cooled by a group of cooling rolls at 50 ° C.
Next, the film is gripped with a clip and guided to a first tenter, stretched 3.4 times at 95 ° C. in the width direction, and then guided to a temperature zone of 245 ° C., and then a temperature controlled to 150 ° C. 1% in the longitudinal direction in the zone, 10
A 2% relaxation treatment was performed in the width direction in a temperature zone controlled at 0 ° C., followed by cooling to room temperature and removing the film edge to obtain a biaxially stretched film having a thickness of 70 μm.

(Example 2) A film was formed in the same manner as in Example 1 except that the PET used in Example 1 and "Ultem" (registered trademark) were mixed in a ratio of 70 to 30. An oriented film was obtained.

Example 3 A film was formed in the same manner as in Example 1 except that the PET used in Example 1 and “Ultem” (registered trademark) were mixed at a ratio of 97: 3, and a biaxial film was formed. An oriented film was obtained.

(Example 4) A biaxially oriented film was formed in the same manner as in Example 2 except that the stretching ratio in the longitudinal direction and the width direction were 3.5 times and 3.6 times, respectively. Obtained.

(Example 5) Except that the stretching temperature in the longitudinal direction and the width direction were 95 ° C and 100 ° C, respectively, and the stretching ratio in the longitudinal direction and the width direction were 3.6 times and 3.8 times, respectively. Was formed in the same manner as in Example 2 to obtain a biaxially oriented film.

Comparative Example 1 The stretching temperature in the longitudinal direction and the stretching direction in the width direction were 85 ° C. and 90 ° C., respectively, and the heat treatment temperature was 24 ° C.
A biaxially oriented film was obtained in the same manner as in Example 1 except that the temperature was set to 0 ° C., and PET and Ultem were mixed at a ratio of 100: 0.

(Comparative Example 2) A biaxially oriented film was formed in the same manner as in Comparative Example 1, except that PET and Ultem used in Example 1 were mixed at a ratio of 99.5 to 0.5. I got

Comparative Example 3 A film was formed in the same manner as in Example 1 except that the PET used in Example 1 and “Ultem” (registered trademark) were mixed at a ratio of 45:55. Occurred frequently and a film could not be obtained. Table 1 shows the evaluation results of the physical properties of the films obtained in Examples 1 to 5 and Comparative Examples 1 to 3 and the flatness of the flexible printed circuit board. From the above results, the biaxially oriented film of the present invention is excellent in thermal dimensional stability and planar stability, and the flexible printed circuit board using this biaxially oriented film has thermal dimensional stability under high temperature conditions. It was a high quality flexible printed board with excellent flatness.

Example 6 After transesterification of dimethyl naphthalene-2,6-dicarboxylate and ethylene glycol in the presence of manganese acetate by a conventional method, trimethyl phosphate was added. At this time, the addition amounts were adjusted so that the mole numbers of manganese and phosphorus were both 50 ppm. Subsequently, antimony trioxide and 0.3% by weight of silica having an average particle size of 1.5 μm are added, and polycondensation is carried out by a conventional method to obtain polyethylene having an intrinsic viscosity of 0.62.
2,6-Naphthalate (PEN) was obtained (melting temperature 26
3 ° C). Next, the P having an intrinsic viscosity of 0.62 obtained here was used.
90 parts by weight of EN and 10 parts by weight of polyetherimide "Ultem" 1010 manufactured by General Electric are vacuum-dried at 170 ° C. for 6 hours, then put into an extruder and melt-extruded at 305 ° C. to obtain a fiber-sintered stainless steel. Shear rate 30 sec- ¹ in metal filter (30 μm cut)
, And discharged in a sheet form from a T-die, and the obtained sheet-like material was solidified on a cooling drum having a surface temperature of 25 ° C. at a draft ratio of 10 at a speed of 13 m / min, and cooled.
An unstretched film having an intrinsic viscosity of 0.60 was obtained. Subsequently, the unstretched film was heated to 140 ° C by using a longitudinal stretching machine composed of a plurality of heated roll groups and utilizing the peripheral speed difference between the rolls.
The film was stretched at a temperature of ° C. in the longitudinal direction of the film at a magnification of 3.7 times. Thereafter, both ends of the film are gripped by clips and guided to a first tenter, and stretched in the width direction of the film at a stretching temperature of 145 ° C. and a stretching ratio of 3.8, and then heat-treated at a temperature of 248 ° C. After that, a relaxation treatment of 2% in the vertical direction and 2% in the width direction is performed in a cooling zone controlled at 170 ° C., and 0.3% in the vertical direction and width direction in a cooling zone controlled at 120 ° C. 0.
After performing a 4% relaxation treatment, the reduction rate of the winding speed of the winder on the take-up side is set to 1% with respect to the speed of the tenter, the relaxation treatment is performed in the longitudinal direction, and the resultant is cooled to room temperature. , Remove film edge, thickness 75μm
Was obtained.

(Comparative Example 4)
A film was formed in the same manner as in Example 6 except that only PEN of Example 6 was used as a raw material, to obtain a biaxially oriented film having a thickness of 75 μm.

(Embodiment 7) Here, an example in which an IC card is produced using the film of Embodiment 1 will be described. First, a biaxially oriented film having a thickness of 70 μm and 250 μm was obtained in the same manner as in Example 1. The thickness was adjusted by adjusting the discharge amount of the extruder. The obtained thickness of 70 μm and 2
50 μm film with card size (width 54 mm, length 8
6 mm). Then, using a biaxially oriented film having a thickness of 70 μm, a printed board on which a chip and a printed antenna circuit were formed was prepared as described above. On the other hand, another 70 μm thick biaxially oriented film (width 54 mm,
Film A having a length of 86 mm) was formed by hollowing out 100 μm in the width direction and the length direction from the chip forming portion of the printed substrate so that the chip was exposed when the printed substrate was overlaid. Next, after both surfaces of the film A were subjected to corona discharge treatment, the pressure-sensitive adhesive was
m, and were superposed so that the chip was exposed to the printed substrate. After that, both sides are subjected to corona discharge treatment,
Two 250 μm thick card-like films B each having an adhesive formed at 25 μm were prepared, and the film B was laminated on the upper and lower sides of a printed substrate on which the film A was laminated. Then, the multilayer laminate was heated at a roll temperature of 120 ° C. To produce an IC card having a thickness of about 840 μm. The card obtained here had no curl, had good flatness, and had an excellent appearance as a card. In addition, the antenna substrate inside the card was not deformed at all, and the chip was not crushed and the connection between the chip and the circuit was not broken.

[0066]

[Table 1]

[0067]

According to the present invention, it is possible to obtain a biaxially oriented film for a flexible printed circuit board which is excellent in dimensional stability and flatness when used at a high temperature and which is relatively inexpensive. Obtainable.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) // (C08L 67/00 (C08L 67/00 79:08) 79:08) B29K 67:00 B29K 67: 00 79:00 79:00 F term (reference) 4F071 AA43 AA45 AA46 AA60 AA88 AF20Y AF31Y AF61Y AH13 BB08 BC01 4F210 AA24 AA40 AH36 QA02 QA03 QC06 QG01 QG18 4J002 CF011 CF031 CF041 CF051 CF061 CF08101 CF061 CF08101 CF061

Claims (11)

[Claims] 1. A biaxially oriented film for a flexible printed board, comprising a polyester and a polyimide, wherein the polyimide is contained in an amount of 1% by weight to 50% by weight. . 2. The biaxially oriented film for a flexible printed circuit board according to claim 1, wherein the polyimide is a polyetherimide. 3. The film has a heat shrinkage of 0.5 in both the longitudinal and width directions when heated at 150 ° C. for 30 minutes.
% Or less, and the heat shrinkage in the longitudinal direction and width direction of the film when subjected to heat treatment at 200 ° C. for 10 minutes is 3.
The biaxially oriented film for a flexible printed board according to claim 1 or 2, wherein the content is 0% or less. 4. The film has a heat shrinkage in the longitudinal direction and width direction of 0.2% when subjected to heat treatment at 120 ° C. for 30 minutes.
The biaxially oriented film for a flexible printed circuit board according to claim 1, wherein: 5. The biaxially oriented film for a flexible printed board according to claim 1, wherein the Young's modulus in the longitudinal direction and the Young's modulus in the width direction are both 3 GPa or more and 8 GPa or less. 6. The refractive index in the thickness direction is 1.47 or more and 1.5.
The biaxially oriented film for a flexible printed board according to any one of claims 1 to 5, wherein the number is 5 or less. 7. The film has an intrinsic viscosity of 0.5 or more and 1.4.
(Dl / g) or less.
The biaxially oriented film for a flexible printed board according to any one of the above. 8. The polyester according to claim 1, wherein the polyester is at least one selected from the group consisting of polyethylene terephthalate, polyethylene-2,6-naphthalate and a copolymer or modified product thereof. 6. The biaxially oriented film for a flexible printed circuit board according to item 1. 9. A flexible printed board using the biaxially oriented film for a flexible printed board according to claim 1. 10. The flexible printed circuit board according to claim 9, which is used as an antenna board of an IC card. 11. An IC card using the flexible printed circuit board according to claim 10.