TWI512022B - Heat treated polyimide film, film roll thereof and method for producing heat treated polyimide film - Google Patents

Description

Heat treatment polyimine film, film roll thereof and heat treatment polyimide film manufacturing method

The present invention relates to a polyimide film suitable as a material for a flexible printed circuit board used in the field of electrical and electronic equipment, and more particularly to a polyimide film as a substrate, and The one-side or two-side transmissive polyimide-based adhesive is then formed on a copper plate, and is suitable as a material of a flexible printed circuit board to improve a polyimine film having an uneven linear expansion coefficient.

In recent years, printed circuit boards have been widely used in electronic and electrical machines. Among them, flexible printed circuit boards (FPC) are widely used in parts such as a hinge, a hard disk, and the like which are required to be bent by a personal computer, a digital camera, or a mobile phone.

From the viewpoint of heat resistance, a copper clad laminated board (Copper Clad Lamination; CCL) using a polyimide film is known as a main material of a flexible printed circuit board constituting an electronic use. The copper clad laminate is roughly distinguished by three layers of CCL and two layers of CCL. Compared with the 3-layer CCL, in general, the 2-layer CCL is better in heat resistance, dimensional stability, and electrical characteristics, and more often when the 3-layer CCL cannot achieve the required characteristics (such as a plasma display, a folding mobile phone). The shaft part, etc.) is used.

The manufacturing method of the two-layer CCL is a casting method of a copper foil-coated polyimine resin, a laminate method of a copper foil and a polyimide film using a polyimide-based adhesive, and a polyimine. The film is vapor deposited or sputtered with metal and then plated with copper.

In the lamination method, an epoxy-based adhesive or an acrylic-based adhesive is also used. However, in order to fully exhibit the excellent properties of the polyimide film, a polyimide-based adhesive having excellent heat resistance may be used (Patent Document) 1). When a polyimine-based adhesive is used in the lamination method, the chemical structure of the polyimide and the stability of the chemical (solvent) are often insufficient in adhesion to the copper foil, and it is necessary to increase the adhesion to 300 ° C or higher. In the high temperature, the copper foil is thermocompression bonded to laminate.

However, after the above-mentioned layering and subsequent etching treatment, etc., since the polyimide film shrinks, even if a partial polyimide film having a small coefficient of linear expansion is obtained, a portion having a large coefficient of linear expansion is produced. The polyimine film has a large coefficient of linear expansion. Therefore, when using a polyimide film, it is necessary to select a portion having a small coefficient of linear expansion. As a product quality unevenness is a practical problem, it is desirable to develop a polyimide film having a uniform film and a small coefficient of linear expansion. sheet.

[references] (Patent Literature)

Patent Document 1: Japanese Laid-Open Patent Publication No. 2005-186274

SUMMARY OF THE INVENTION An object of the present invention is to provide a polyimide film having uniform uniform dimensional stability regardless of the position of the film and which has improved coefficient of linear expansion.

The inventors of the present invention have focused on the results of repeated studies in view of the above circumstances, and found that in the lamination method, a strong heat treatment is performed in a specific temperature range before coating a polyimide polyimide-based adhesive on the surface of the polyimide film. The present invention has been completed by reviewing and examining the polyimide film having a uniform dimensional stability in the width direction of the film.

That is, the present invention encompasses the following inventions.

[1] A heat-treated polyimine film characterized in that a rate of change in linear expansion coefficient in a mechanical transport direction is 25%, and a polyimine film having a temperature of 200 ° C or more is higher than the aforementioned linear expansion coefficient The rate of change is 25%, and the heat treatment is performed at a temperature higher than 100 ° C to 150 ° C; wherein, for any two points, the difference in linear expansion coefficient of the mechanical transport direction is 15 ppm at 50 ° C to 300 ° C / Below °C.

[2] The heat-treated polyimide film according to the above [1], wherein the heat treatment time is more than 0 seconds and not more than 10 seconds.

[3] A film roll comprising a heat-treated polyimide film according to the above [1] or [2] having a width of 500 mm or more and a length of 50 m or more.

[4] A method for producing a heat-treated polyimide film, characterized in that it has a step of increasing the linear expansion coefficient in the mechanical transport direction to 25% and a temperature of 200 ° C or more. The imide film is subjected to heat treatment at a temperature higher than a temperature at which the rate of change of the linear expansion coefficient is 25% higher than 100 ° C to 150 ° C.

[5] The method for producing a heat-treated polyimide film according to the above [4], wherein the heat treatment time is more than 0 seconds and not more than 10 seconds.

The heat-treated polyimine film of the present invention has a uniform linear expansion coefficient and dimensional stability irrespective of the position on the film, so that there is no problem in the lamination method, no warpage, excellent heat resistance, and no need The processing of classifying the film portion and cutting the portion is particularly useful for a flexible printed circuit board.

The invention is specifically described below.

The heat-treated polyimine film of the present invention is characterized in that the rate of change of the linear expansion coefficient in the mechanical transport direction is 25%, and the polyimine film having a temperature of 200 ° C or more has a change in the linear expansion coefficient. The heat treatment is carried out at a temperature of 25% higher than 100 ° C to 150 ° C, wherein, for any two points, the difference in linear expansion coefficient of the mechanical transport direction is 15 ppm at 50 ° C to 300 ° C. / °C below.

In the present invention, the heat-treated polyimine film refers to a polyimide film after the heat treatment described above. In addition, the following mechanical transport direction is called MD, the width direction is called TD, and the linear expansion coefficient of the mechanical transport direction is called α _MD . The measurement method of α _{MD and} the measurement method of the change rate of α _MD are as follows.

The evaluation method and evaluation criteria of each characteristic in the present invention are as follows.

(1) Linear expansion coefficient

The coefficient of linear expansion was increased from room temperature to 320 ° C at a temperature increase rate of 10 ° C/min using a thermal analyzer (TMA-50, manufactured by Shimadzu Corporation), and the value in the range of 50 to 300 ° C was analyzed.

(2) Rate of change of linear expansion coefficient

The rate of change of α _MD was measured at 50 ° C to 450 ° C at a temperature increase rate of 10 ° C / min using a thermal analyzer (TMA-50, manufactured by Shimadzu Corporation). The average of the linear expansion coefficients was obtained per 10 ° C from the starting point of 50 ° C, and the rate of change was obtained by the following formula.

Rate of change (%) = ((C2-C1) / C1) × 100

C2: the coefficient of linear expansion of the temperature at which the rate of change is desired

C1: coefficient of linear expansion at a temperature 10 ° C lower than C2

(3) Diaphragm temperature

A measurement unit of a sheathed thermocouple (K type (T-35), manufactured by Okazaki Co., Ltd.) was attached to the surface of the membrane, and the terminal was connected to a recorder (NR-1000, manufactured by Keyence). It was transported to the oven under the processing conditions of the membrane and the actual temperature of the membrane was measured.

(4) Determination of wind speed

The wind speed of the air on the surface of the diaphragm was measured using an anemometer (Anemomaster anemometer MODEL 6162, manufactured by KANOMAX Co., Ltd.).

The heat treatment of the present invention is preferably carried out at a temperature of about 100 to 150 ° C higher than the temperature at which the α _MD change rate of the heat-treated polyimide film is 25%, more preferably about 100 to 140 higher. The temperature is °C. When the temperature of the heat treatment exceeds a temperature higher than 150 ° C at a temperature at which the α _MD change rate of the heat-treated polyimide film is 25%, the film partially expands and contracts, and thus the planarity cannot be maintained. It is not good to look at it. Further, when the temperature of the heat treatment is lower than the temperature at which the α _MD change rate of the heat-treated polyimide film is 25% higher than 100 ° C, the unevenness of the linear expansion coefficient cannot be sufficiently lowered, which is not preferable.

Further, the aforementioned heat treatment may be carried out in multiple stages, and the temperature at the final stage is preferably higher than the temperature of the first stage. When the heat treatment is carried out in multiple stages, it is preferred that the temperature at which the rate of change of the α _MD of the heat-treated polyimide film is 25% higher than the temperature of about 100 to 150 ° C as the highest temperature, and the aforementioned α _It is preferable that the rate of change of _MD becomes 25% or more of the temperature as the lowest temperature.

The time for performing the above heat treatment is preferably more than 0 second and not more than 10 seconds, more preferably more than 0 second and not more than 8 seconds, and more preferably 3 seconds or more and 8 seconds or less. Further, the aforementioned heat treatment may be carried out in plural times, and the time at which the heat treatment is performed refers to the total treatment time. When the heat treatment time exceeds 10 seconds, the unevenness of α _MD cannot be suppressed, and the planarity of the obtained film sheet is remarkably deteriorated, which is not preferable. The time during which the heat treatment is performed can be adjusted, for example, by the relative rotational speed of each roller. When the heat treatment is performed in multiple stages, the total processing time in all stages is preferably more than 0 seconds and less than 10 seconds, more preferably more than 0 seconds and less than 8 seconds, and more preferably more than 3 seconds. At a level below 8 seconds.

The means for the heat treatment of the present invention is not particularly limited as long as it does not impair the effects of the present invention, and examples thereof include a method of irradiating far infrared rays using a ceramic heater or the like, a method of blowing hot air, and a method using a radiant heater, and the like. Two or more types can also be used together. In view of the heat treatment in a very short time, the far-infrared rays are preferably those having a wavelength of about 2 μm to 10 μm. In the method of blowing hot air, the hot air wind speed is preferably about 1.5 to 2.5 m/sec. When the wind speed is 1.5 m/sec or more and the air is circulated, the heat transfer efficiency in the environment is improved, and it is preferable that the film is easily heat-treated uniformly. Further, when the wind speed exceeds 2.5 m/sec, the pressure of the hot air is blown to deteriorate the slack, which is not preferable.

The heat treatment is preferably carried out, for example, in a furnace having the above heat treatment means to move the diaphragm. At this time, the time during which the diaphragm stays in the furnace corresponds to the heat treatment time. The tension when the film is moved in the furnace is not particularly limited as long as it does not impair the effects of the present invention, but is preferably from about 1 to 50 N/m, more preferably from about 5 to 25 N/m. When the tension is less than this range, the mobility of the film is deteriorated, and if the tension is high, the heat shrinkage rate of the obtained film for MD becomes high, which is not preferable. The diaphragm tension in the heat treatment can be adjusted, for example, by the difference in rotational speed between the take-up roll and the take-up roll. Further, the moving speed of the diaphragm is not particularly limited as long as it does not impair the effects of the present invention, but is preferably about 10 to 200 m/min, more preferably about 30 to 30, in order to improve the unevenness of the α _MD . 120m/min.

Further, the heat-treated polyimine film of the present invention preferably has an α _MD difference of from about 5 ppm/°C or less, more preferably about 10 ppm/°C or less, in the range of from 50 °C to 300 °C. If the difference between the above-mentioned α _MD is directly used, there is a problem that it is unfavorable, and it is necessary to select a portion having a small difference in α _MD and use it, which is not preferable. Further, the α _{MD of} each point is preferably about 50 ppm / ° C or less, more preferably about 40 ppm / ° C or less at 50 ° C to 300 ° C.

The form of the heat-treated polyimide film of the present invention is not particularly limited as long as it does not impair the effects of the present invention, and is usually in the form of a roll or a sheet. Since the linear expansion coefficient of the heat-treated polyimide film according to the present invention is not small, it is suitable to roll a film having a width of 500 mm or more and/or a length of 50 m or more into a roll shape.

The polyimine film used for producing the heat-treated polyimide film of the present invention is not particularly limited as long as it does not impair the effects of the present invention, but it is preferable that the temperature at which the rate of change of α _MD is 25% is about 200. Above °C, more preferably about 250 °C or more. Further, from the viewpoint of obtaining good uniformity, the polyimide film has a thickness of preferably from about 1 to 250 μm, more preferably from about 5 to 50 μm. These membranes can be widely used: commercially available, manufactured by a known method, and the like.

The following is an example of a method for producing a polyimide film for use in the present invention. The polyimine film used in the present invention is produced by a method comprising the steps of: (a) polymerizing an aromatic diamine component and an acid anhydride component in an organic solvent to obtain a poly-proline a step of solution; (b) a step of subjecting the polyamic acid solution to a cyclization reaction to obtain a gel-like membrane; and (c) a step of stretching the membrane obtained in the above step (b).

The above step (a) is a step of obtaining a polyaminic acid solution by polymerizing an aromatic diamine component and an acid anhydride in an organic solvent. The polyamic acid contained in the polyamic acid solution is preferably composed of an aromatic tetracarboxylic acid and an aromatic diamine, and is composed of a repeating unit represented by the following formula (1). The polyamic acid may be partially imidized in a solution, or may contain a small amount of an inorganic compound or the like.

In the above formula (1), R ¹ is a divalent organic group having at least one aromatic ring and having a carbon number of 25 or less, and R ² is a divalent organic group having at least one aromatic ring and having a carbon number It is 25 or less.

The aromatic tetracarboxylic acid and the aromatic diamine are each formulated to have a molar ratio substantially equal to each other, but one of them may be in the range of about 10 mol%, preferably about 5 mol%. And the other is over-provisioned.

Specific examples of the aromatic tetracarboxylic acid include pyromellitic acid; 3,3',4,4'-diphenyltetracarboxylic acid; 2,3',3,4'-biphenyl 2,3',3,4'-biphenyltetracarboxylic acid; 3,3',4,4'-benzophenone tetracarboxylic acid 2,3,6,7-naphthalenetetracarboxylic acid, 2,2-bis(3,4-dicarboxyphenyl)propane; pyridine-2,3,5,6-tetracarboxylic acid (pyridine-2,3 , 5,6-tetracarboxylic acid) or an anhydride thereof or an acid dianhydride, or an aromatic tetracarboxylic acid derived from an ester compound or a halide of the acid.

Specific examples of the aromatic diamines include para-phenylene diamine, meta-phenylene diamine, benzidine, and para-xylylene diamine. , 4,4'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenyl 4,4'-diaminediphenyl sulfone, 3,3'-dimethyl-4,4'-diaminodiphenylmethane, 1,5-diaminonaphthalene, 3,3'-dimethyl Oxybenzidine, 1,4-bis(3-methyl-5-aminophenyl)benzene, and the like.

Particularly suitable for the combination of the aromatic tetracarboxylic acid component and the aromatic diamine component of the present invention, preferably pyromellitic dianhydride and 4,4'-diaminodiphenyl ether, and 3,3' , a combination of 4,4'-diphenyltetracarboxylic dianhydride and 4,4'-diaminodiphenyl ether or the like. Further, the polyamic acid obtained from the aromatic tetracarboxylic acid component and the aromatic diamine component is preferably obtained by copolymerization of the above-mentioned copolymerization and/or copolymerization with p-phenylenediamine.

Specific examples of the organic solvent used for preparing the polyamic acid solution include N,N-dimethylformamide and N,N-dimethylacetamide (N). , an organic polar amide-based solvent such as N-methylacetamide or N-methyl pyrrolidone, and these organic solvents may be used singly or in combination of two or more, but may be used together with benzene or A non-solvent such as toluene or xylene is used in combination.

The polymerization reaction is carried out continuously for about 10 minutes to 30 hours at a temperature of about 0 to 80 ° C while stirring and/or mixing in an organic solvent, but the temperature may be increased or decreased as necessary, or the polymerization may be carried out. The reaction is divided into multiple rounds. The order of addition of the two reactants is not particularly limited, but it is preferred to add an aromatic tetracarboxylic acid to the aromatic diamine solution. An effective method for producing a good organic solvent solution of polylysine by vacuum defoaming in the above polymerization reaction. Further, a small amount of an end-capping agent may be added to the aromatic diamine before the polymerization to control the polymerization.

The polyamic acid solution preferably has a solid content of from about 5 to 40% by weight, more preferably from about 10 to 30% by weight. Further, in order to provide a stable liquid supply, the viscosity is preferably about 10 to 2000 Pa‧s, more preferably about 100 to 1000 Pa‧s, as measured by a BROOKFIELD viscometer.

In order to obtain the slipperiness of the film, the polyamic acid solution may contain a chemically inactive organic compound such as titanium oxide, fine cerium oxide, calcium carbonate, calcium phosphate, calcium hydrogen phosphate or polythenimine filler as necessary. Filler or inorganic filler, etc., such filler is preferably cerium oxide.

The above step (b) is a step of subjecting the polyamic acid solution to a cyclization reaction to obtain a gel-like membrane. Examples of the cyclization reaction include a thermal ring closure method and a chemical ring closure method. The thermal closed-loop method refers to an organic solvent solution of the polyamic acid containing no ring-closing catalyst and a dehydrating agent, which is cast into a support by a slit-attached opening and formed into a diaphragm shape, and A method in which a support is heated and dried to be dehydrated and cyclized to obtain a gel-like membrane. In addition, the chemical ring closure method refers to an organic solvent solution of the polyamic acid containing the ring-closing catalyst and the dehydrating agent, which is cast into a support from the opening of the slit to form a diaphragm, and is supported on the support. A method in which a part of the cyclization is carried out by peeling and heating the support, thereby obtaining a gel-like film.

The gel-like membrane of the present invention refers to a membrane containing a part of quinone imidized polylysine and a solvent and having self-supporting properties. The amount of the solvent contained in the gel-like membrane is not particularly limited, but it is usually from about 1 to 90% based on the solvent of the gel-like membrane.

In the foregoing cyclization reaction, any of the above closed-loop methods may be employed, although the chemical ring closure method requires a device containing a ring-closing catalyst and a dehydrating agent in an organic solvent solution of poly-proline, but a self-supporting gel is obtained in a short time. The film is a preferred method from this point of view.

Specific examples of the ring-closing catalyst used in the present invention include aliphatic tertiary amines such as trimethylamine and triethylamine, isoquinoline, pyridine, β-picoline, and the like. Heterocyclic tertiary amines and the like, but it is preferred to use at least one amine selected from heterocyclic tertiary amines. For polylysine, the ring closure catalyst content is preferably such that the ring closure catalyst content (mole) / polyglycine content (mole) is in the range of about 0.5 to 8.

Specific examples of the dehydrating agent to be used in the present invention include aliphatic carboxylic anhydrides such as phthalic anhydride, propionic anhydride, and butyric anhydride, and aromatic carboxylic anhydrides such as benzoic anhydride, and preferably acetic anhydride and/or benzoic anhydride. Further, the content of the dehydrating agent relative to the poly-proline is preferably such that the dehydrating agent content (mole) / polyglycine content (mole) is in the range of about 0.1 to 4. Further, at this time, a gelation retarder such as acetonitrile acetone may be used in combination.

The intrinsic viscosity (measured in sulfuric acid at 25 ° C) of the polyimine contained in the aforementioned gel-like film is preferably in the range of about 0.2 to 3.0, more preferably in the range of about 0.8 to 2.0.

The aforementioned step (c) is a step of stretching the gel-like film obtained in the above step (b). The stretching method is not particularly limited as long as it does not impair the effects of the present invention, but is preferably biaxially stretched in the machine transport direction (MD) and the width direction (TD).

The order of the biaxial stretching treatment is not particularly limited, and it is preferably stretched in the machine direction (MD) (hereinafter referred to as longitudinal stretching) and then stretched in the width direction (TD) (hereinafter referred to as Horizontal stretching). Further, from the viewpoint of improving the uniformity of the coefficient of thermal expansion of the wire, it is more preferable to carry out the step of longitudinally stretching and then heat-treating, followed by the step of transverse stretching, or longitudinal stretching, followed by simultaneous heat treatment and transverse stretching. The steps. The heat treatment described herein is to obtain a polyimide film for removing the solvent contained in the gel film. In the present invention, the polyimine film is heat-treated to obtain a heat-treated polyimide film.

The stretching (longitudinal stretching) of MD in the biaxial stretching treatment is preferably carried out in two or more stages. The total stretching ratio of MD is not particularly limited, but is preferably 1.04 times or more and 1.5 times or less, more preferably 1.05 times or more and 1.4 times or less. Further, the stretching temperature of the MD is not particularly limited, but is preferably about 50 to 100 ° C, more preferably about 60 ° C to 90 ° C. The form of the longitudinal stretching may be a method of stretching once from the stretching ratio 1 to the stretching ratio, a method of successive stretching, a method of sequentially stretching at an indefinite magnification, and a stepwise stretching at a fixed magnification. The method, or the method of combining the plurals, etc., is particularly preferably a method of fractionally stretching at a fixed magnification.

In the heat treatment after the longitudinal stretching, the heating temperature is not particularly limited, but is preferably a temperature higher than the temperature at the time of stretching of MD. Further, the heat treatment may be carried out in multiple stages at different temperatures, and in this case, the heating temperature in the final stage is preferably higher than the heating temperature of the first stage. A heating device such as a mold furnace or a heating furnace having a plurality of blocks (regions) having different temperatures may be used in the heat treatment. The heat treatment is preferably carried out by fixing the ends of the diaphragm by a pin tenter, a clip-on tenter, a zipper or the like. The solvent can be removed by this heat treatment.

When the transverse stretching is performed after the longitudinal stretching, the MD-shaped gel-like film is introduced into the tenter device, and the both ends in the width direction are sandwiched by a tenter clip or the like, and moved together with the tenter clip or the like, and are widened at the same time. Direction (TD) stretching. The stretching ratio of TD (hereinafter referred to as the transverse stretching ratio) is not particularly limited, but is preferably 1.1 times or more and 2.0 times or less, more preferably 1.2 times or more and 1.8 times or less. The draw ratio (transverse stretch ratio) of TD is preferably set to be higher than the draw ratio (longitudinal stretch ratio) of MD, and specifically, it is preferably 1.10 times or more and 1.50 times or less of the total draw ratio of MD. More preferably, it is 1.15 times or more and 1.45 times or less. By setting the stretching ratio of the film TD to be higher than the stretching ratio of MD, the film can be obtained, and the MD of the film maintains a linear thermal expansion coefficient of the metal, and at the same time, the linear thermal expansion coefficient of the TD of the film can be suppressed to be low. value. The heat-treated polyimide film of the present invention produced using the film is suitable for a flexible printed circuit board or the like.

The stretching of TD may be carried out after the above heat treatment, or may be performed before the heat treatment. However, from the viewpoint of improving the uniformity of the linear thermal expansion coefficient, it is preferred to carry out the above-described heat treatment. The stretching stretching time of TD is not particularly limited, but is about 5 seconds to 10 minutes, preferably 10 seconds to 8 minutes. The form of the horizontal stretching described above may be a method of stretching once from the stretching ratio 1 to the transverse stretching ratio, a method of successive stretching, a method of sequentially stretching at an indefinite magnification, and a stepwise stretching at a fixed magnification. The method, the method of combining the plurals, and the like. In particular, when the transverse stretching and the multi-stage heat treatment are simultaneously performed, it is preferable to set the stretching ratio of TD at the time of the first-stage heat treatment to the maximum stretching ratio, and to decrease the stretching ratio in stages. Further, it is preferable to set the stretching ratio of TD to be slightly increased once after the first-stage heat treatment, and to increase the stretching ratio of TD in the second-stage or final-stage heat treatment.

The gel-like film peeled off from the support is stretched in the moving direction (MD) while restraining the moving speed while rotating the roller. The rotating roller must have a gripping force for regulating the moving speed of the gel-like diaphragm, and the rotating roller is preferably a nip roll, a vacuum roll, a multi-stage tension cutting roller which is formed by using a combination of a metal roller and a rubber roller. Cut roll), or a vacuum suction type suction roll or the like.

(Example)

The invention is illustrated by the following examples, but the invention is not limited to the examples.

[Manufacturing Example 1]

To the polymerization apparatus having a stirrer, 1900.6 kg of dry N,N-dimethylacetamide was added, and 12.43 kg (0.115 kmol) of p-phenylenediamine was stirred and dissolved therein. Then, 24.45 kg (0.112 kmol) of pyromellitic dianhydride was added in small portions, and stirring was continued for 1 hour. Thereafter, 169.17 kg (0.845 kmol) of 4,4'-diaminodiphenyl ether was charged and stirred until homogeneous, and then 3,3'-4,4'-diphenyltetracarboxylic dianhydride 56.49 (0.192) was added. Kmol) and reacted for 1 hour. Next, 143.09 kg (0.656 kmol) of pyromellitic dianhydride was added to carry out a complex reaction for 1 hour to obtain a polyaminic acid solution. The solution had a viscosity of 320 Pa‧s at 20 °C.

250.0 kg of dried N,N-dimethylacetamide, 2.5 mol of phthalic anhydride relative to the poly-proline unit, and 2.0 mol of pyridine relative to the polyglycolate were mixed in the polyamic acid solution. Modulate the polyaminic acid solution.

The polyamic acid solution was extruded from a T-film head having an opening slit width of 2.5 mm and a length of 1600 mm, and cast on a metal ring belt of 70 ° C to obtain a self-supporting gel-like film. The gel-like membrane was transported at a temperature of 1.15 times in the MD at room temperature of 60 ° C. Both ends in the width direction of the gel-like membrane were held by a needle by a needle tenter, and dried at 260 ° C for 2 minutes while stretching at TD 1.35 times, followed by heat treatment at 340 ° C for 5 minutes. Thereafter, the side was allowed to cool while cooling at a temperature of 30 ° C for 2 minutes. The edge of the end of the film was cut while being conveyed, and the surface of the film was cleaned with a web cleaner (MODEL SC2202, manufactured by Hugle Electronics Co., Ltd.), thereby adopting a polyimide film having a width of 1600 mm and a thickness of 12 μm. Sheet 3200m. This was slit by a slitting machine to obtain a film roll (hereinafter referred to as PI roll-1) having a width of 510 mm and a length of 300 m. Further, the temperature at which the rate of change of the α _MD of the PI roller-1 was 25% was 250 ° C, and the difference between the maximum value and the minimum value of the α _MD obtained by measuring 16 points at intervals of 30 mm in the width of 510 mm was 18 ppm/°C.

[Manufacturing Example 2]

The prepared polyaminic acid solution was extruded in a T-film head having an opening slit width of 2.5 mm and a length of 1600 mm in the same manner as in Production Example 1, and cast on a metal ring belt of 58 ° C to obtain a self-supporting gel-like film. . The gel-like membrane was transported at a depth of 1.10 times in the MD at 65 ° C. The needle-shaped tenter device holds and conveys both ends of the gel-like membrane in the width direction by a needle, and is dried at 260 ° C for 3 minutes while stretching at TD for 1.40 times, and further heat treatment at 340 ° C for 7.5 minutes. And cooling at 30 ° C while cooling the area while relaxing for 1.5 minutes. The edge of the end of the film was cut while being conveyed, and the surface of the film was cleaned with a cotton net cleaner (MODEL SC2202, manufactured by Hugle Electronics Co., Ltd.), whereby a polyimide film having a width of 1585 mm and a thickness of 25 μm was taken at 1,100 m. This was cut into a slitter to obtain a film roll having a width of 510 mm and a length of 300 m (hereinafter referred to as PI roll-2). Further, the rate of change of the α _MD of the PI roller-2 was 25%, and the temperature was 250 ° C. The difference between the maximum value and the minimum value of the α _MD obtained by measuring 16 points at intervals of 30 mm in the width of 510 mm was 22 ppm/°C.

[Example 1]

The PI roll-1 was continuously fed into a heating device by a take-up roll, and heat treatment was performed for 7 seconds under the conditions of a tension of 10 N/m and a maximum processing temperature of 385 °C. The heating device used in the present embodiment has two heating chambers as shown in Fig. 1 (hereinafter referred to as a heating chamber 1 and a heating chamber 2 in the order of the winding-out side), and a ceramic heater is disposed in the heating chamber. 2. The upper air supply nozzle 3 and the lower air supply nozzle 4 are provided with an exhaust port at a position where the diaphragm processing unit is displaced in the width direction. After the heat treatment, it was cooled to room temperature while being taken up outside the heating device. The temperature of the ceramic heater was adjusted to 630 ° C, and the upper and lower wind speeds were both 2.4 m / sec. Further, the air introduced from the upper and lower air supply nozzles has a temperature of 130 ° C in the heating chamber 1 and 150 ° C in the heating chamber 2, and a polyimine film roll having a winding speed of 50 m/min to obtain 250 m. . The unwinding speed described herein corresponds to the moving speed of the aforementioned diaphragm. The difference between the maximum value and the minimum value of the α _MD obtained by measuring 16 points at intervals of 30 mm in the width of the obtained film was 510 mm, which was 9 ppm/°C.

[Embodiment 2]

A 250 m polyimine film roll was obtained in the same manner as in Example 1 except that the processing conditions were changed so that the temperature of the ceramic heater was 580 ° C and the maximum processing temperature was 350 ° C. The difference between the maximum value and the minimum value of the obtained α _MD obtained by measuring 16 points at intervals of 30 mm in a width of 510 mm was 10 ppm/°C.

[Comparative Example 1]

A 250 m polyimine film roll was obtained in the same manner as in Example 1 except that the processing conditions were changed so that the temperature of the ceramic heater was 480 ° C and the maximum processing temperature was 280 ° C. The difference between the maximum value and the minimum value of the obtained α _MD obtained by measuring 16 points at intervals of 30 mm in a width of 510 mm was 20 ppm/°C.

[Comparative Example 2]

The same operation as in Example 1 was carried out except that the treatment conditions were changed so that the temperature of the ceramic heater was 480 ° C, the maximum treatment temperature was 265 ° C, and the unwinding speed was 100 m/min, thereby obtaining a polyimine of 250 m. Diaphragm roller. The difference between the maximum value and the minimum value of the obtained α _MD obtained by measuring 16 points at intervals of 30 mm in a width of 510 mm in the width of the film was 23 ppm/°C.

[Comparative Example 3]

A 250 m polyimine film roll was obtained in the same manner as in Example 1 except that the processing conditions were changed so that the temperature of the ceramic heater was 680 ° C and the maximum processing temperature was 420 ° C. The difference between the maximum value and the minimum value of the obtained α _MD obtained by measuring 16 points at intervals of 30 mm in a width of 510 mm was 17 ppm/°C.

[Example 3]

A 250 m polyimine film roll was obtained in the same manner as in Example 1 except that the treatment roll was changed to PI roll-2 and the unwinding speed was 100 m/min. The difference between the maximum value and the minimum value of the obtained α _MD obtained by measuring 16 points at intervals of 30 mm in a width of 510 mm was 11 ppm/°C.

The heat-treated polyimine film of Comparative Examples 1 to 3 had a difference between the maximum value and the minimum value of the 16-point α _MD measured at 20 ppm/° C., 23 ppm/° C., and 17 ppm/° C C, respectively, at different positions on the film. α _{MD is} not uniform. On the other hand, in Examples 1 to 3 of the present invention, the position on the α _MD- independent film sheet was uniform, and a high-quality heat-treated polyimide film having a reduced unevenness was obtained.

(industrial availability)

The heat-treated polyimine film of the present invention has a uniform α _MD due to the position on the film, so that there is no problem of workability in the lamination method and warpage does not occur, and the coefficient of linear expansion after etching is small. It is also excellent in heat resistance, and can improve the unevenness of α _MD , and is particularly useful in materials for flexible printed circuit boards.

1. . . Polyimine film

2. . . Ceramic heater

3. . . Upper air supply nozzle

4. . . Lower air supply nozzle

5. . . Transport roller

6. . . Heating chamber 1

7. . . Heating chamber 2

8. . . Polyimine film transport direction

Fig. 1 is a view schematically showing heating devices of Examples 1 to 3 and Comparative Examples 1 to 3.

The drawings in the present invention are diagrams showing the heating device in an outline of the embodiment and the comparative example, and are not representative of the present invention. Therefore, there is no designated representative map in this case.

Claims (5)

A heat-treated polyimine film characterized in that the rate of change of the linear expansion coefficient in the direction of mechanical transport is 25%, and the rate of change of the polyimine film having a temperature of 200 ° C or more is higher than the linear expansion coefficient The heat treatment is carried out at a temperature of 25% higher than 100 ° C to 150 ° C, wherein the difference in linear expansion coefficient in the mechanical transport direction is 15 ppm/° C. or less at 50 ° C to 300 ° C for any two points. The heat-treated polyimide film according to claim 1, wherein the heat treatment time is more than 0 seconds and less than 10 seconds. A film roll characterized by comprising a heat-treated polyimine film according to item 1 or item 2 of the patent application scope of 500 mm or more in length and 50 m or more in length. A method for producing a heat-treated polyimine film, characterized in that it has a step of a polyimine film having a rate of change of linear expansion coefficient of 25% in a mechanical transport direction of 200 ° C or more The sheet is subjected to heat treatment at a temperature higher than a temperature at which the linear expansion coefficient change rate is 25% higher than 100 ° C to 150 ° C. The method for producing a heat-treated polyimine film according to the invention of claim 4, wherein the heat treatment time is more than 0 seconds and not more than 10 seconds.