KR102272950B1 - Polyimide film - Google Patents

Abstract

[Problem] To provide an adhesive film in which generation of a dimensional change in the diagonal direction is suppressed, and a flexible metal laminate obtained by laminating metal foils.
[Solution] When the film forming width is 1 m or more and the propagation velocity V of the ultrasonic pulse is measured at the orientation angle (θ) of the film at 45° and 135° with respect to the machine transport direction (MD) of the film The anisotropy index (AI) expressed by Equation 1 is 12 or less over the entire width, and the rate of dimensional change in the diagonal direction before and after etching of the flexible metal laminate in the diagonal (45°, 135°) direction over the entire width All of these are -0.05 to 0.05%, and a polyimide film having a thermoplastic polyimide layer having a thickness of 0.5 to 20 µm on at least one side thereof.
AI(45, 135)=|(V45^2-V135^2)/((V45^2+V135^2)/2)×100｜ (Equation 1)

Description

polyimide film {POLYIMIDE FILM}

The present invention relates to a polyimide film. It further relates to an adhesive film having a thermoplastic polyimide on at least one side of the polyimide film. Furthermore, it relates to the flexible metal laminated board obtained by bonding metal foil to this adhesive film.

A flexible printed wiring board (FPC: Flexible 　 printed circuits) is generally made of an insulating film formed of various insulating materials and having flexibility as a substrate, and superimposed on the surface of the substrate by heating and pressing metal foil through various adhesive materials. Manufactured by gluing method. As said insulating film. A polyimide film excellent in heat resistance and electrical insulation is preferably used. As the adhesive material, thermosetting adhesives such as epoxy and acrylic are generally used (FPC using these thermosetting adhesives is hereinafter also referred to as three-layer FPC).

The thermosetting adhesive has the advantage that adhesion at a relatively low temperature is possible. However, as the required characteristics such as heat resistance, flexibility, and electrical reliability become stricter in the future, it is considered that there are applications that are difficult to use in 3-layer FPC using a thermosetting adhesive. On the other hand, FPC (hereinafter also referred to as two-layer FPC) in which a metal layer is directly formed on an insulating film or using a thermoplastic polyimide as an adhesive layer has been proposed, and the demand for this two-layer FPC is expected to increase in the future.

In the manufacturing method of a flexible metal laminate used for two-layer FPC, a casting method in which polyamic acid, a precursor of polyimide, is cast and applied on a metal foil and then imidized, sputtering, and metallizing to make a metal layer directly on the polyimide film by plating method, and a lamination method in which a polyimide film and metal foil are laminated via a thermoplastic polyimide. Among these, the lamination method is excellent in that the thickness range of the applicable metal foil is wider than the casting method, and the apparatus cost is lower than the metalizing method. As an apparatus for laminating, a hot roll laminating apparatus or a double belt press apparatus for laminating continuously while continuously feeding out a roll-shaped material is used. Among the above, from the viewpoint of productivity, the hot roll lamination method can be used more preferably.

When producing the conventional three-layer FPC by the lamination method, since the thermosetting resin was used for the contact bonding layer, it was possible to perform lamination temperature at less than 200 degreeC (patent document 1). On the other hand, since the two-layer FPC uses a thermoplastic polyimide as an adhesive layer, it is necessary to apply a high temperature of 200°C or higher, or close to 400°C in some cases, in order to express heat-sealability. Therefore, residual distortion arises in the flexible metal laminated board obtained by lamination, and when etching and forming wiring, and performing soldering reflow in order to mount a component, the dimension changes and appears.

In particular, to give an example of the lamination method, when an adhesive layer containing a thermoplastic polyimide is formed on a polyimide film, polyamic acid, a precursor of a thermoplastic polyimide, is cast and coated, and then imidized by heating continuously, and metal foil is overlapped. Although there is a pasting method, since heating and pressurization are continuously performed not only in the imidization process but also when the metal layers are laminated, the material is often placed in a heating environment in a state in which tension is applied. As a result, when metal foil was etched from a flexible metal laminate and heated through solder reflow, this distortion was released, and a dimensional change appeared before and after these processes in many cases.

In recent years, in order to achieve miniaturization and weight reduction of electronic devices, miniaturization of wiring provided on a substrate is progressing, and components to be mounted are also mounted with miniaturized and high-density components. Therefore, if the dimensional change after formation of fine wiring becomes large, a problem arises in which it shifts|deviates from the component mounting position in a design stage, and a component and a board|substrate are not connected well. For this reason, requirements for polyimide films are also increasing, and for example, as physical properties of polyimide films, they are required to have a coefficient of linear expansion equivalent to that of metals and to reduce dimensional changes.

Until now, only the machine transport direction (MD direction) and the film width direction (TD direction) of the film were considered important for the dimensional change of flexible metal laminates. However, as wiring miniaturization and high lamination of wiring boards progress, only the MD and TD directions have been considered. A dimensional change of the flexible metal laminate has been requested also in the direction from the MD to the left and right 45 degrees from the MD, and a flexible metal laminate that satisfies these is expected.

In Patent Document 2, it is considered that the dimensional change rate at 250°C/30 min in the direction from the MD direction to the left and right 45° should be in the range of -0.10 to +0.10%, but in recent years, finer wiring has been demanded. , a dimensional change rate of -0.10 to +0.10% at 250°C/30 min is insufficient. It is preferable that it is -0.10 to +0.10% at 300 degreeC/30min. Patent Document 3 describes a method for reducing the anisotropy of a polyimide film, but the effect of film distortion due to the influence of residual stress in the tenter cooling process is not considered, and it is sufficient to improve the dimensional change in the diagonal direction of a flexible metal laminate. Did not do it.

Japanese Patent Laid-Open No. 9-199830 Japanese Patent Laid-Open No. 2007-91947 Japanese Patent Laid-Open No. 2008-12276

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This invention was made in view of the said subject, and an object of this invention is to provide the flexible metal laminated board obtained by bonding the adhesive film by which generation|occurrence|production of the dimensional change in the diagonal direction was suppressed, and metal foil.

MEANS TO SOLVE THE PROBLEM As a result of repeating earnest research in order to solve the said subject, the present inventors, based on the machine conveyance direction (MD) of the film, the orientation angle (θ) of the film is 45° and the orientation coefficient expressed by Equation 1 at 135° If the AI (45, 135) value satisfies that it is 12 or less over the entire width, and the difference in the dimensional change rate at 45° and 135° at 300°C/30 min is -0.05 to 0.05% over the entire width, FCCL And it was found that it is possible to suppress the dimensional change occurring in the manufacturing process of FPC, in particular, to suppress the dimensional change in the oblique direction of the film. Based on this knowledge, further research was advanced, and the present invention was completed.

That is, the present invention relates to the following inventions.

[1] The film forming width is 1 m or more, and the orientation angle (θ) of the film based on the machine transport direction (MD) of the film is the orientation coefficient AI (45, 135) expressed by Equation 1 in 45° and 135° ) value is 12 or less over the entire width, and the dimensional change rate before and after etching treatment of the flexible metal laminate in the diagonal (45°, 135°) direction with respect to the entire width is -0.05 to 0.05%, at least on one side, the thickness A polyimide film, characterized in that it has a thermoplastic polyimide layer of 0.5-20 μm.

AI(45, 135)=|(V45^2-V135^2)/((V45^2+V135^2)/2)×100｜ 　 (Equation 1)

[2] On a straight line perpendicular to the machine transport direction (MD) of the film, select two points that entered 200 mm from both ends of the film forming width, and within the range of the straight line joining the two points, a straight line including the two points The polyimide film according to the above [1], characterized in that the anisotropy index is 12 or less in at least all of these five points by selecting one point within ±200 mm of the center of the image and at least two points.

[3] A gel film having self-supporting properties was produced by casting and applying a polyamic acid solution, which is a polyimide precursor, on a support, partially drying and/or curing the gel film, and heating the gel film in at least two or more heating furnaces. It is produced by drying and/or heat treatment while holding both ends of the gel film in the width direction by passing it through a tenter heating furnace equipped with, and the film forming width is 1 m or more and the thickness is 3 to 50 μm. 1] or the polyimide film as described in [2].

[4] Furthermore, the polyimide film according to the above [3], characterized in that it is heat-treated at low tension in the machine transport direction (MD).

[5] The polyimide film contains at least one aromatic diamine component selected from the group consisting of paraphenylene diamine, 4,4'-diamino diphenyl ether and 3,4'-diamino diphenyl ether, and pyromellitic acid. Any one of [1] to [4] above, characterized in that it is prepared using at least one acid anhydride component selected from the group consisting of dianhydride and 3,3'-4,4'-diphenyl tetracarboxylic dianhydride The polyimide film according to one claim.

[6] A gel film having self-supporting properties in which a polyamic acid solution, which is a polyimide precursor, is cast and coated on a support, and partially dried and/or cured, is prepared, and the gel film is heated by a tenter equipped with at least two or more heating furnaces [1] to [5] above, characterized in that the drying speed in the tenter heating furnace is controlled by passing through a furnace and performing drying and/or heat treatment while gripping both ends of the gel film in the width direction. The manufacturing method of the polyimide film in any one of Claims.

[7] The above [6] characterized in that the polyimide film obtained by the production method of the above [6] is further subjected to a heating treatment, wherein the temperature of the heating treatment is 250°C or more and 500°C or less. A method for producing a polyimide film of a substrate.

[8] A flexible metal laminate obtained by laminating a metal foil on the polyimide film as described in [1] to [5] above.

In the polyimide film and flexible metal laminated board of this invention, generation|occurrence|production of a dimensional change is suppressed, and especially generation|occurrence|production of the dimensional change in the lamination method can also be suppressed effectively. Specifically, with respect to the rate of dimensional change before and after removing the metal foil, 45 degrees left and right from the machine transport direction (MD direction) of the film, each dimensional change rate can be made small, and at the same time, 45 degrees right from the MD direction and The difference in the dimensional change in the left 45 degree direction can be made small, and it is possible to set it as 0.05% or less of range. Therefore, it can be suitably used also for FPC etc. in which fine wiring was formed, and problems, such as a position shift, can be improved. In particular, in the case of an adhesive film having a width of 1 m or more that is continuously produced, not only the above-mentioned dimensional change rate is small, but also the effect of stabilizing the dimensional change rate over the entire width of the film is exhibited.

Fig. 1 shows the relationship between AIs 45 and 135 and the rate of dimensional change.
Fig. 2 is a schematic diagram showing an orientation axis and an orientation angle (θ). A white arrow shows the machine conveyance direction (MD) of a film, and the width direction (TD).
[FIG. 3] The ultrasonic velocity at each angle is made into a radar graph, an orientation axis is drawn from there, and it is calculated|required as orientation angle (theta). A white arrow shows the machine conveyance direction (MD) of a film.
It is a schematic diagram which shows the measurement position of AI(45,135) of this invention polyimide film. A white arrow shows the machine conveyance direction (MD) of a film.
5 shows the result of evaluating only the width direction about how much the position of the vertex shifts after copper foil etching of the flexible metal laminate which has been subjected to normal heat treatment or heat treatment (annealing treatment). The normal heat treatment means heat treatment at 150 to 200°C.

Hereinafter, the present invention will be described in detail. The polyimide film of the present invention has a film forming width of 1 m or more, and the orientation angle (θ) of the film with respect to the machine transport direction (MD) of the film is the propagation velocity V of the ultrasonic pulse at 45° and 135°. The anisotropy index (Anisotoropy Index: AI) expressed by Equation 1 when measured is 12 or less over the entire width, and the rate of dimensional change before and after etching of the flexible metal laminate in the diagonal (45°, 135°) direction with respect to the entire width All of these are -0.05 to 0.05%, and it is characterized by having a thermoplastic polyimide layer having a thickness of 0.5 to 20 µm on at least one surface.

(Equation 1) AI(45, 135)=|(V45^2-V135^2)/((V45^2+V135^2)/2)×100|

The propagation velocity (also referred to as an ultrasonic velocity) V of the ultrasonic pulse in Formula 1 of the present invention was measured using SST-2500 (Sonic Sheet Tester) manufactured by Nomura Corporation. When SST-2500 is used, the ultrasonic velocity in 16 directions is automatically measured little by little at 11.25° with respect to the film plane direction 0 to 180° (0° is parallel to the MD direction). Among the obtained velocities in each direction, the anisotropy index (Anisotoropy Index: AI) expressed by Equation 1 from the ultrasonic velocities V45 and V135 at 45° and 135° with respect to the MD direction is required.

(Equation 1) AI(45, 135)=|(V45^2-V135^2)/((V45^2+V135^2)/2)×100|

It shows that it is a film with small anisotropy on a diagonal, so that the value of AI(45,135) obtained is small, so that it is small. With respect to the present invention, the anisotropy index is 12 or less, more preferably 11 or less, still more preferably 8 or less, and particularly preferably 6 or less from the viewpoint of further suppressing the occurrence of dimensional change. .

As a result of intensive examination, the present inventors showed a correlation between the AI (45, 135) of the film and the rate of dimensional change of the flexible metal laminate using the adhesive film as shown in FIG. 1 , and specifically, the AI (45, 135) value of the film When this increased, it discovered that the dimensional change of the flexible metal laminated board using the said adhesive film also increased.

The orientation angle in this invention was measured using SST-2500 (Sonic Sheet Tester) made by Nomura Corporation. The orientation angle (θ) in the present invention means the direction of the orientation axis, and as shown in FIG. 2 , the machine transport direction (MD) of the film is set to 0 degrees as the reference line, and the reference line is rotated clockwise. indicates. When SST-2500 is used, the ultrasonic velocity in 16 directions is automatically measured at intervals of 11.25° to the film plane direction 0 to 180° (0° is parallel to MD). A pattern diagram as shown in FIG. 3 is drawn by performing radar graphing (using the graph function of Microsoft Excel) the obtained speed in each direction. The line drawn from the center of the circle toward the most bulging part of the pattern diagram was the orientation axis (g), and the angle (θ) of the orientation axis was measured with MD as the reference line and the reference line, and this was obtained as the orientation angle.

The rate of dimensional change in the present invention is a value measured by the method described in the following Examples.

As a result of earnest examination, the present inventors show a correlation as shown in FIG. 5 that the heat treatment temperature under the storage force by an oven shows a correlation as shown in FIG. 5 to the dimensional change rate of the flexible metal laminate using the adhesive film, and the heat treatment is a flexible metal using the adhesive film It discovered that it had an influence on reduction of the dimensional change of a laminated board.

In the flexible metal laminate obtained by using the polyimide film of the present invention, the rate of dimensional change before and after removing the metal foil is in the range of -0.05% to +0.05% in both the right 45° and left 45° directions from the MD direction. It is preferable to exist in the range of -0.045% to +0.045%, It is more preferable to exist in the range of -0.045% to +0.045%, It is especially preferable to exist in the range of -0.025% to +0.025%.

Moreover, it is preferable that the difference in the dimensional change rate in the right 45 degree direction and the left 45 degree direction is 0.01% or less, and it is preferable that it is 0.005% or less. The dimensional change rate before and after metal foil removal is represented by the ratio of the difference of the predetermined dimension in the flexible metal laminated board before an etching process and the predetermined dimension after an etching process, and the predetermined dimension before the said etching process.

When the dimensional change rate is out of this range, the dimensional change becomes large after forming fine wiring in the flexible metal laminate and at the time of component mounting, which may deviate from the component mounting position at the design stage. As a result, there exists a possibility that the component to be mounted and a board|substrate may not be connected well. In other words, if the dimensional change rate is within the above range, it can be seen that there is no problem in mounting the parts.

The measuring method of the said dimensional change rate is not specifically limited, Any conventionally well-known method can be used as long as it is a method which can measure the increase/decrease of the dimension which arises before and after an etching or a heating process in a flexible metal laminated board.

In addition, the specific conditions of the etching process at the time of measuring a dimensional change rate are not specifically limited. That is, since etching conditions differ depending on the kind of metal foil, the shape of the pattern wiring to be formed, etc., the conditions of the etching process at the time of measuring a dimensional change rate in this invention may be any conventionally well-known condition.

Furthermore, the orientation angle θ of the polyimide film of the present invention is preferably within the range of 90°±23°, more preferably within the range of 90°±12° with respect to the machine transport direction (MD). Here, the orientation angle of 90° is such that the orientation axis is oriented parallel to the film width direction (TD). That is, the fact that there is an orientation angle within the above range indicates that the orientation axis is oriented in the TD direction over the entire width of the film, and the imbalance is small. For this reason, also in any position, since the physical property value of a film approximates and the dimensional stability of TD is increasing, it is preferable. When the orientation angle (θ) exceeds 90±23°, the TD orientation of the film is broken and the physical properties are also changed, which is not preferable.

Although the manufacturing method of this invention polyimide film is not specifically limited, The detail of a manufacturing method is shown below. The first aspect of the manufacturing method is, for example, (1) the step of polymerizing the aromatic diamine component and the acid anhydride component in an organic solvent to obtain a polyamic acid solution, (2) the polyamic acid solution obtained in the above step (1) cyclization reaction to obtain a gel film, (3) MD stretching (hereinafter also referred to as longitudinal stretching) for the gel film obtained in the above step (2) is two-step stretching, and the stretching ratio of TD The process of biaxial stretching treatment of MD and TD which are 1.10 times or more and 1.50 times or less of the total draw ratio of this MD can be included.

A process (1) is a process of obtaining a polyamic-acid solution by superposing|polymerizing an aromatic diamine component and an acid anhydride component in an organic solvent.

Specific examples of the aromatic diamine are not particularly limited as long as the effects of the present invention are not hindered, but p -phenylene diamine, meta phenylene diamine, benzidine, p- xylene diamine, and 4,4'-diamino diphenyl ether , 3,4'-diamino diphenyl ether, 4,4'-diamino diphenyl methane, 4,4'-diamino diphenyl sulfone, 3,3'-dimethyl-4,4'-diamino diphenyl Methane, 1,5-diaminonaphthalene, 3,3'-dimethoxy bentidine, 1,4-bis(3-methyl-5-aminophenyl)benzene, or these amide-forming derivatives are mentioned. Among these, by adjusting the amount of diamines such as p -phenylene diamine and 3,4'-diamino diphenyl ether, which have an effect of increasing the tensile modulus of elasticity of the film, the final tensile modulus of elasticity of the polyimide film obtained is 4.0 GPa or more. It is preferable to do These aromatic diamines can be used individually or in mixture of 2 or more types. Among these aromatic diamines, p -phenylene diamine, 4,4'-diamino diphenyl ether, and 3,4'-diamino diphenyl ether are preferable. Although the usage-amount of aromatic diamine is not specifically limited, When p -phenylene diamine and 4,4'- diamino diphenyl ether and/or 3,4'- diamino diphenyl ether are used together, (i) 4,4 It is more preferable to use '-diamino diphenyl ether and/or 3,4'-diamino diphenyl ether and (ii) p -phenylene diamine in an amount of 69/31 to 90/10 (molar ratio), 70/30 It is particularly preferred to use ˜85/15 (molar ratio).

Specific examples of the acid anhydride component are not particularly limited as long as the effects of the present invention are not hindered, but pyromellitic acid, 3,3′, 4,4′-biphenyltetracarboxylic acid, 2,3′, 3, 4'-biphenyl tetracarboxylic acid, 3,3', 4,4'-benzophenone tetracarboxylic acid, 2,3,6,7-naphthalene tetracarboxylic acid, 2,2-bis(3,4-dicarboxyl) and acid anhydrides such as phenyl) ether, pyridine-2,3,5,6-tetracarboxylic acid, and amide-forming derivatives thereof, with an acid dianhydride of aromatic tetracarboxylic acid being preferred, and pyromellitic dianhydride and/or 3,3', 4,4'-biphenyl tetracarboxylic dianhydride is particularly preferred. These acid anhydride components can be used individually or in mixture of 2 or more types. The amount of the acid anhydride component used is not particularly limited, but when pyromellitic dianhydride and 3,3',4,4'-biphenyltetracarboxylic dianhydride are used together, pyromellitic dianhydride and 3,3', It is more preferable to use 4,4'- biphenyl tetracarboxylic dianhydride in 80/20-60/40 (molar ratio), and it is especially preferable to use in 75/25-65/35 (molar ratio).

In the present invention, the organic solvent used for the formation of the polyamic acid solution is not particularly limited, but for example, sulfoxide solvents such as dimethyl sulfoxide and diethyl sulfoxide; N,N-dimethylformamide, N Formamide solvents such as ,N-diethyl formamide; Acetamide solvents such as N,N-dimethyl acetamide and N,N-diethyl acetamide; N-methyl-2-pyrrolidone, N-vinyl Pyrrolidone solvents such as -2-pyrrolidone; Phenolic solvents such as phenol, o- , m- , or p- cresol, xylenol, halogenated phenol, and catechol; or hexamethyl phospholamide, γ- Aprotic polar solvents, such as butyrolactone, are mentioned, It is preferable to use these individually or as a mixture of 2 or more types, However, it is also possible to use aromatic hydrocarbons, such as xylene and toluene, in addition.

The polymerization method may be carried out by any known method, and is not particularly limited, but for example, (i) first put the whole amount of the aromatic diamine component in an organic solvent, and then add the acid anhydride component so that it is equivalent to the total amount of the aromatic diamine component. A method of polymerization, (ii) a method in which the entire amount of the acid anhydride component is first put in a solvent, and then the aromatic diamine component is added so as to be equivalent to the acid anhydride component, and polymerization is performed, (iii) one aromatic diamine component (a1) is placed in a solvent Then, after mixing for the time required for the reaction in a ratio such that the acid anhydride component (b1) is 95 to 105 mol% with respect to the reaction component, the other aromatic diamine component (a2) is added, and then the acid anhydride component (b2) ) by adding and polymerization so that the wholly aromatic diamine component and the acid anhydride component are approximately equivalent, (iv) one side of the acid anhydride component (b1) is placed in a solvent, and then one aromatic diamine component (a1) with respect to the reaction component After mixing for the time required for the reaction in a ratio of 95 to 105 mol%, the acid anhydride component (b2) is added, and then the other aromatic diamine component (a2) is mixed with the wholly aromatic diamine component and the total acid anhydride component. A method of polymerization by adding it so that it becomes almost equivalent, (v) reacting one aromatic diamine component and an acid anhydride component in a solvent so that either becomes excess to prepare a polyamic acid solution (A), Either an aromatic diamine component and an acid anhydride component are made to react so that it may become excess, and a polyamic-acid solution (B) is prepared. Next, when preparing a polyamic-acid solution (A) in the method of mixing each obtained polyamic-acid solution (A) and (B) to complete polymerization, (vi) (v), when an aromatic diamine component is excessive, In the mixed acid solution (B), the acid anhydride component is excessive, and in the polyamic acid solution (A), the acid anhydride component is excessive, and in the polyamic acid solution (B), the aromatic diamine component is excessive, and the polyamic acid solution (A) and (B) is mixed and the method of preparing so that the wholly aromatic diamine component and acid anhydride component used for these reaction may become substantially equivalent, etc. are mentioned.

The polyamic acid solution obtained in this way contains 5 to 40 weight% of solid content normally, Preferably it contains 10 to 30 weight% of solid content. In addition, the viscosity of the polyamic acid solution is a measured value according to the rotational viscometer method using a Brookfield viscometer according to JIS K6726_1994, and although it is not specifically limited, Usually 10-2000 Pa.s (100-20000 poise), For stable liquid feeding, it is preferably 100 to 1000 Pa·s (1000 to 10000 poise). Further, the polyamic acid in the organic solvent solution may be partially imidized.

The polyamic acid solution of the present invention is a chemically inert organic filler such as titanium oxide, microsilica, calcium carbonate, calcium phosphate, calcium hydrogen phosphate, polyimide filler, etc. Or you may contain an inorganic filler etc.

The inorganic filler (inorganic particle) used in the present invention is not particularly limited, but an inorganic filler having a total particle size of 0.005 µm or more and 2.0 µm or less is preferable, and an inorganic filler having a total particle size of 0.01 µm or more and 1.5 µm or less. A filler is more preferable. Although it does not specifically limit with respect to particle size distribution (volume basis), An inorganic filler whose particle diameter is 0.10 micrometer or more and 0.90 micrometer or less accounts for 80 volume% or more of all the particles is preferable, and since it is excellent in reverse activity, the particle diameter The inorganic filler in which the particle|grains of 0.10 micrometer or more and 0.75 micrometer or less occupy 80 volume% or more of all particle|grains is more preferable. When the average particle diameter is 0.05 µm or less, it is undesirable because the adverse effect of the film is lowered, and when it is 1.0 µm or more, it is not preferable because it exists as locally large particles. The said particle size distribution, an average particle diameter, and a particle diameter range can be measured using the laser dilution/scattering type particle size distribution analyzer LA-910 of Horiba Corporation. The said average particle diameter points out a volume average particle diameter.

Although the inorganic filler used for this invention is not specifically limited, It is preferable that it is uniformly disperse|distributed in a film in the ratio of 0.03 weight% or more and less than 1.0 weight% with respect to the weight of a polyamic acid solution, 0.30 from the point of an inverse activity effect. A ratio of not less than 0.80% by weight and not more than 0.80% by weight is more preferable. At 1.0 wt % or more, a decrease in mechanical strength can be seen, and at 0.03 wt % or less, a sufficient adverse effect is not observed, which is not preferable.

Process (2) is a process of making a cyclization reaction of the polyamic acid solution obtained by the said process (1), and obtaining a gel film. The method for cyclizing the polyamic acid solution is not particularly limited, but specifically, (i) a method of casting the polyamic acid solution on a film and thermally dehydrating it to obtain a gel film (thermal cyclization method), or (ii) mixing a cyclization catalyst and a conversion agent with the polyamic acid solution to chemically decyclize to prepare a gel film, and heating to obtain a gel film (chemical ring closure method), etc., to the resulting polyimide film On the other hand, the latter method is preferable in that the dimensional change can be uniformly suppressed by combination with other structural requirements. The polyamic acid solution may contain a gelation retardant or the like. It does not specifically limit as a gelation retardant, Acetyl acetone etc. can be used.

Although it does not specifically limit as said cyclization catalyst, For example, Aliphatic tertiary amines, such as trimethylamine and triethylenediamine; Aromatic tertiary amines, such as dimethylaniline; Inquinoline, pyridine, β-picoline, etc. of heterocyclic tertiary amines and the like, and at least one heterocyclic tertiary amine selected from the group consisting of inquinoline, pyridine and β-picoline is preferable. Although it does not specifically limit as said converting agent, For example, aliphatic carboxylic acid anhydrides, such as acetic anhydride, propionic anhydride, butyric anhydride; Aromatic carboxylic acid anhydrides, such as benzoic anhydride, etc. are mentioned, Acetic anhydride and/or anhydride Benzoic acid is preferred. Although content in particular of such a cyclization catalyst and conversion agent is not limited, About 10 to 40 weight% is preferable with respect to 100 weight% of polyamic acid solution, respectively, and about 15 to 30 weight% is more preferable.

The gel film is the polyamic acid solution or a mixed solution of a polyamic acid solution mixed with a cyclization catalyst and an inverting agent, and is molded into a film by being cast from a slit clasp on a support, and then heated from the support, hot air, or It can be obtained by heating with water heat from a heat source such as an electric heater, causing a ring closure reaction, and drying volatiles such as free organic solvent to form a gel film having self-supporting properties, and then peeling from the support.

Although it does not specifically limit as said support body, A metal (for example, stainless steel) rotating drum, an endless belt, etc. are mentioned, For example, The temperature of a support body is (i) a liquid or gas thermal medium, (ii) an electric heater, etc. It is controlled by the radiant heat of the, etc., it does not specifically limit, For example, 30-200 degreeC may be sufficient, and 40-150 degreeC is preferable.

In step (3), the gel film obtained in step (2) is subjected to two-step stretching in MD and biaxially in MD and TD, wherein the TD stretch ratio is 1.10 times or more and 1.50 times or less of the total draw ratio of MD. It is a process of stretching treatment.

The gel film peeled from the support body is stretched in the traveling direction MD while regulating the traveling speed by a rotating roll. The rotary roll requires a gripping force necessary to regulate the traveling speed of the gel film, and as the rotary roll, a nip roll made by combining a metal roll and a rubber roll, a vacuum roll, a multi-stage tension cut roll, or a suction roll of a reduced pressure suction system It is preferable to use, etc.

In the step (3), a biaxial stretching treatment is performed. Although the order of the said biaxial stretching process is not specifically limited, After stretching (longitudinal stretching) in the machine conveyance direction (MD), it is preferable to perform stretching (hereinafter also referred to as transverse stretching) in the width direction (TD). . In addition, the process of longitudinally stretching, then heat-treating, then transverse stretching, or longitudinally stretching and then performing transverse stretching in parallel with the heat treatment is uniform according to the combination with other constituent requirements. It is more preferable from the point which can suppress a dimensional change.

In order to suppress a dimensional change with respect to a polyimide film by combination with other structural requirements, the extending|stretching (vertical extending|stretching) of MD in the said biaxial stretching process is divided into two steps, and it is implemented. With respect to the two-step stretching in MD, the draw ratio (hereinafter also referred to as longitudinal stretch ratio) in the first step is not particularly limited, but is preferably 1.02 times or more and 1.3 times or less, and dimensional changes can be uniformly suppressed. , 1.04 times or more and 1.1 times or less are more preferable. The draw ratio of the MD in the second step is preferably 1.02 times or more and 1.3 times or less, and more preferably 1.04 times or more and 1.1 times or less from the viewpoint that dimensional changes can be uniformly suppressed by combination with other structural requirements. . Further, in the present invention, the ratio of the draw ratio of the first stage stretching to the total draw ratio of the MD is a point that dimensional change can be uniformly suppressed by combination with other structural requirements, so the total draw ratio of the MD 40% or more is preferable, and it is more preferable to set it as 50% or more and 80% or less from the point which dimensional change can be suppressed further. Here, the calculation method of the ratio of the draw ratio of the 1st stage drawing with respect to the total draw ratio of MD is as following formula (2).

(Equation 2)

For example, a draw ratio of 1.1 times is a state stretched 0.1 times with respect to the basic length (length before stretching) 1 . Therefore, it is calculated by subtracting 1 from the draw ratio. Although the total draw ratio of MD is not specifically limited, 1.04 times or more and 1.4 times or less are preferable, and 1.05 times or more and 1.3 times or less are more preferable. Although the extending|stretching temperature of MD is not specifically limited, About 60-100 degreeC is preferable, and about 65-90 degreeC is more preferable. Although the extending|stretching speed of MD is not specifically limited, When implementing two-stage extending|stretching, since a dimensional change can be suppressed uniformly by combination with other structural requirements, the extending|stretching of the 1st stage of the said two-stage extending|stretching. The rate is preferably about 1%/min to 20%/min, and more preferably about 2%/min to 10%/min. 1%/min - about 20%/min are preferable, and, as for the extending|stretching speed of the 2nd stage of the said 2-stage extending|stretching, about 2%/min - about 10%/min are more preferable. Two-step extending|stretching to MD WHEREIN: Although the extending|stretching time of each stage is not specifically limited, It is about 5 second - about 5 minutes, 10 second - 3 minutes are preferable. As the above-described longitudinal stretching pattern, from the draw ratio 1 to the draw ratio, a method of stretching at once, a method of stretching in order, a method of stretching at an indefinite magnification little by little, a method of stretching at a constant magnification little by little, or these A method of combining a plurality of , etc. are mentioned, and the method of extending|stretching at a constant ratio little by little is especially preferable.

In the case of heat treatment after stretching the MD, the heating temperature is not particularly limited, but a temperature higher than the temperature at the time of stretching the MD is preferable, and is usually about 80 to 550° C., preferably about 180 to 500° C. And about 200-450 degreeC is more preferable. When extending|stretching is started at less than 80 degreeC, a film may be hard and brittle, and there exists a possibility that extending|stretching may become difficult. 30 second - 20 minutes are preferable, and, as for heat processing time, 50 second - 10 minutes are more preferable. In addition, you may perform heat processing in multiple steps (two steps, three steps, etc.) at different temperatures. For example, the heating temperature of the first step, which is a case of performing heat treatment in multiple steps, is not particularly limited, but in order to sufficiently remove the solvent, 80°C or more and 300°C or less are preferable, and 100°C or more and 290°C or less are more It is preferable, and 120 degreeC or more and 285 degrees C or less are still more preferable. The heating temperature of the final step in the case of performing heat treatment in multiple steps is a temperature higher than the heating temperature of the first step, and is not particularly limited as long as it is different from the setting of the heating temperature of the first step, for example, 300°C or more and 550°C The following are preferable, 320 degreeC or more and 500 degrees C or less are more preferable, and 350 degreeC or more and 450 degrees C or less are still more preferable. When the heating temperature of the first stage is higher than the heating temperature of the final stage, the solvent evaporates rapidly and the resulting film becomes brittle, which is not practical. In the case of multi-step heat processing, the processing time of each step is as described above. For the heat treatment, a casting having a plurality of blocks (zones) having different temperatures, or a heating apparatus such as a heating furnace, etc. can be used. It is preferable to perform heat processing by fixing the both ends of a film with a pin-type tenter apparatus, a clip-type tenter apparatus, a zipper, etc. The solvent can be removed by the heat treatment. It is preferable that the tenter apparatus has at least two or more heating furnaces.

The gel film stretched on the MD is introduced into a tenter apparatus (tenter heating furnace) equipped with a heating furnace, held at both ends in the width direction by a tenter clip, and is stretched in the width direction (TD) while traveling with the tenter clip. The draw ratio of TD (hereinafter also referred to as transverse stretch ratio) is not particularly limited, but is preferably 1.35 times or more and 2.0 times or less, and can uniformly suppress dimensional changes by combination with other structural requirements, 1.40 times or more and 1.8 times or less are more preferable. The draw ratio of the said TD means the transverse stretch ratio in an Example. The draw ratio of TD (horizontal elongation) needs to be set higher than the draw ratio (vertical elongation) of MD, and specifically, it is usually 1.10 times or more and 1.50 times or less of the total draw ratio of MD, in combination with other structural requirements. From the viewpoint of uniformly suppressing a dimensional change, 1.15 times or more and 1.45 times or less are preferable. The stretching of the MD is the above-mentioned two-step stretching, the stretching ratio of the TD is set higher than the stretching ratio of the MD of the film, and a film in which the dimensional change is suppressed can be obtained in combination with other structural requirements. The stretching of the TD may be performed after the heat treatment or before the heat treatment, but from the viewpoint of more uniformly suppressing a dimensional change, it is preferably performed in parallel with the heat treatment. Although the extending|stretching time of extending|stretching of TD is not specifically limited, It is about 5 second - about 10 minutes, 10 second - 5 minutes are preferable. The transverse stretching pattern includes a method of stretching at a stretch from a draw ratio of 1 to the transverse stretching ratio, a method of stretching in order, a method of stretching at an indefinite magnification little by little, a method of stretching at a constant magnification little by little, or a plurality of these The combined method etc. are mentioned. In particular, when transverse stretching and multi-step heat treatment are performed in parallel, it is preferable to set the draw ratio of TD to be the maximum draw ratio at the time of the heat treatment in the first step, and to decrease the draw ratio little by little. It is also preferable to increase the draw ratio of the TD little by little even after the heat treatment in the first step and set it so that the draw ratio of the TD becomes the maximum elongation during the heat treatment in the second step or the final step.

It is preferable to control the drying rate when the gel film introduced into the tenter heating furnace is dried from the viewpoint of uniformly suppressing dimensional change in combination with other structural requirements. This effect is not particularly limited, and can be achieved by an optimal combination of the film forming rate and the drying rate of the film. When the film forming speed is set constant, if the drying rate is greater than the film forming rate, the film is oriented outward with respect to the film forming advancing direction, and conversely, if the drying rate is smaller than the film forming rate, the film is oriented inward with respect to the advancing direction. However, by appropriately controlling the film forming speed and the drying rate, it is possible to obtain a film in which the dimensional change in an oblique direction with respect to the film forming advancing direction is uniformly suppressed. Drying is performed with hot air heated by a heater, but control of the drying rate may be performed by the flow rate of the hot air or by the temperature of the hot air, and it is possible to obtain the same result by combining them. The film forming rate can be adjusted by the discharge rate of the raw material polymer (for example, 100 to 1000 kg/hour), the temperature of the support during gel film production, the content of the cyclization catalyst and conversion agent, the amount of residual volatile components, and the like. It is very suitable for suppressing the dimensional change in the diagonal direction that the orientation angle (θ) of the film is in the range of 90°±23° with respect to the machine transport direction (MD).

Furthermore, in order to produce a polyimide film having a desired rate of dimensional change over the entire width and having a uniform difference in dimensional change in the diagonal direction in the width direction of the film, the solvent residual rate at the time of TD stretching of the film has an effect. When the film is stretched in the TD direction in a situation in which the solvent is excessively removed or in a situation in which the solvent is insufficiently removed, the film is oriented obliquely at the end of the film by stretching in the TD direction and drying shrinkage in the MD direction. However, when the amount of the solvent contained in the gel film in the process of obtaining a gel film by cyclizing the polyamic acid solution is 100%, when the solvent residual ratio in the drying process is 50 to 90%, the width direction (TD ), the tension in the MD direction is relieved by the film itself, and a polyimide film having a uniform rate of dimensional change over the entire width can be manufactured. Moreover, 50-90 % is more preferable, and, as for the solvent residual rate at the time of 50 % of lateral elongation, 75 to 90 % is still more preferable at the point where the dispersion|variation in dimensional change rate is suppressed more. Moreover, it is more preferable that it is 50 to 90 %, and, as for the solvent residual rate at the time of lateral stretch rate of 80 %, 55 to 75 % is still more preferable. These solvent residual ratios may be combined, for example, when the lateral stretch is 50%, the solvent residual ratio is 60 to 90%, On the other hand, when the lateral stretch ratio is 80%, the solvent residual ratio may be 50 to 70%. The measurement of the imbalance of the dimensional change rate is performed, for example, at a position shown in FIG. 3 . Specifically, when the film forming width is 1 m or more, on a straight line perpendicular to the machine transport direction (MD) of the film, select two points that fall within 200 mm from both ends of the film forming width, and within the range of the straight line joining the two points. In , one point within ±200 mm of the center of the straight line including the two points, and any two additional points are further selected, and at least these five points can be mentioned.

Next, the 2nd aspect of the manufacturing method of the polyimide film of this invention is demonstrated in detail below. The second aspect of the manufacturing method is, for example, (1) the step of polymerizing the aromatic diamine component and the acid anhydride component in an organic solvent to obtain a polyamic acid solution, (2) the polyamic acid solution obtained in the above step (1) cyclization reaction to obtain a gel film, (3) the gel film obtained in the above step (2) is multi-stage stretching in which MD stretching (hereinafter also referred to as longitudinal stretching) is three or more stages, and the draw ratio of TD is MD It may include a process of biaxial stretching treatment of MD and TD that are 1.10 times or more and 1.50 times or less of the total draw ratio of .

With respect to the second manufacturing aspect, in the step (3), in the gel film obtained in the step (2), the stretching of the MD is a multi-step stretching of three or more steps, while the draw ratio of the TD is 1.10 times the total draw ratio of the MD It is a process of carrying out the biaxial stretching process to MD and TD which are more than 1.50 times or less.

The gel film peeled from the support in the step (2) is stretched in the traveling direction MD while regulating the traveling speed with a rotating roll. The rotary roll requires a gripping force that regulates the traveling speed of the gel film, and as the rotary roll, a nip roll formed by combining a metal roll and a rubber roll, a vacuum roll, a multi-stage tension cut roll, or a vacuum suction method succession, etc. It is preferable to use

In the step (3), a biaxial stretching treatment is performed. The order of the said biaxial stretching process can be implemented similarly to the said 1st manufacturing aspect.

In the said 2nd manufacturing aspect, the extending|stretching (vertical extending|stretching) of MD in the said biaxial stretching process is divided into three or more steps, and is implemented. The stretching (longitudinal stretching) of MD is not particularly limited as long as it is three or more stages, and may be performed in three stages, four stages, five stages, etc., but from the viewpoint of high uniformity of the coefficient of linear thermal expansion of the obtained film, three stages of stretching desirable.

Although the draw ratio of each step of MD is not specifically limited, For example, in the case of 3 step drawing, Although the draw ratio of the 1st step is not specifically limited, 1.02 times or more and 1.3 times or less are preferable, 1.04 times More than 1.1 times or less is more preferable. 1.005 times or more and 1.4 times or less are preferable, and, as for the draw ratio of MD of the 2nd stage, 1.01 times or more and 1.3 times or less are more preferable. 1.02 times or more and 1.3 times or less are preferable, and, as for the draw ratio of MD of 3rd stage, 1.04 times or more and 1.1 times or less are more preferable. Moreover, about this invention, 40 % or more is preferable and, as for the ratio of the draw ratio of 1st stage drawing with respect to the total draw ratio of MD, it is more preferable to set it as 50 % or more and 80 % or less. Moreover, it is preferable that it is 5 % or more, and, as for the ratio of the draw ratio of 2nd stage with respect to the total draw ratio of MD, it is more preferable that they are 8 % or more and 30 % or less. Although the total draw ratio of MD is not specifically limited, 1.04 times or more and 1.4 times or less are preferable, and 1.05 times or more and 1.3 times or less are more preferable. The calculation method of the ratio of the draw ratio of each MD draw with respect to the total draw ratio of MD is as described in the said 1st aspect.

The extending|stretching temperature of MD can be implemented similarly to the said 1st manufacturing aspect. The stretching rate of the MD may be appropriately selected under conditions in which the target coefficient of linear thermal expansion is obtained, and is not particularly limited, but when performing three-stage stretching, the stretching rate in the first stage of the three-stage stretching is 1% /min - about 20%/min are preferable, and 2%/min - about 10%/min are more preferable. 1%/min - about 20%/min are preferable and, as for the extending|stretching speed of the 2nd stage of the said 3-stage extending|stretching, about 2%/min - about 10%/min are more preferable. 1%/min - about 20%/min are preferable, and, as for the extending|stretching speed of the 3rd stage of the said 3-stage extending|stretching, about 2%/min - about 10%/min are more preferable. Three-step extending|stretching to MD WHEREIN: Although the extending|stretching time of each stage is not specifically limited, It is about 2 second - about 5 minutes, 5 second - 3 minutes are preferable. The patterns of longitudinal stretching and transverse stretching can be implemented in the same manner as in the first manufacturing aspect.

The heat treatment after extending|stretching of MD and extending|stretching of TD can be performed similarly to the 1st manufacturing aspect. By adjusting the draw ratio within this range and adjusting the solvent residual ratio, a film having a desired anisotropy index and capable of uniformly suppressing dimensional change in combination with other constituent requirements can be produced. have.

Although the thickness of the polyimide film of this invention is not specifically limited, It is preferable to set it as the range of 1 micrometer or more and 100 micrometers or less, It is more preferable to set it as the range of 3 micrometers or more and 50 micrometers or less. Although the film forming width|variety of the polyimide film of this invention is not specifically limited, 1 m or more is preferable. As a polyimide film of this invention, the film-forming width|variety is 1 m or more, and the thing of 3-50 micrometers in thickness is mentioned, for example.

As a result of intensive studies, the present inventors have found that even if the orientation of the film end in the oblique direction is controlled by controlling the solvent residual amount in TD stretching, the residual stress in the oblique direction due to the shrinkage caused in the annealing step after heat treatment is in the diagonal direction. It was found that the difference in the rate of dimensional change was affected. With respect to the polyimide film obtained by the 1st manufacturing aspect or 2nd manufacturing aspect, in order to release the stress applied, it is necessary to heat-treat (anneal treatment) at a predetermined temperature. Since both ends of the film are fixed by a pin-type tenter device, a clip-type tenter device, a zipper, or the like, a difference in the dimensional change rate in the oblique direction occurs due to the shrinkage of the film by fixing and cooling the film in the TD direction, thereby affecting the dimensional change. The thermal relaxation of the film occurs by the annealing treatment, and in addition to being able to suppress heat shrinkage small, the difference in dimensional change in the oblique direction of both ends can be improved. Although it does not specifically limit as temperature of annealing, 250 degreeC or more and 500 degrees C or less are preferable, 270 degreeC or more and 370 degrees C or less are more preferable, 300 degreeC or more and 350 degrees C or less are especially preferable. In the manufacturing method of the polyimide film of this invention, since the orientation to TD of a film is strong, although the heat shrinkage rate in TD tends to become high, the heat shrinkage rate at 200 degreeC by thermal relaxation from annealing treatment is both MD and TD of the film. It can be suppressed to 0.05 % or less, and since dimensional accuracy further increases, it is preferable. Specifically, in the furnace of 250 ° C or more and 500 ° C or less, preferably 270 ° C or more 370 ° C or less, particularly preferably 300 ° C or more and 350 ° C or less, the film is run in the machine conveying direction under a storage force to perform annealing treatment. desirable. Although the time for which a film stays in a furnace becomes processing time, it comes to control by changing a running speed, and the processing time of 30 second - 5 minutes is preferable. When the treatment time is shorter than this, heat is not sufficiently transmitted to the film, and when the treatment time is longer, it tends to overheat and impairs planarity, which is not preferable. Moreover, 10-50 N/m is preferable and, as for the film tension at the time of running, 15-30 N/m is more preferable. When the tension is lower than this range, the running property of the film deteriorates, and when the tension is high, the thermal contraction rate in the running direction of the obtained film becomes high, which is not preferable. As shown in FIG. 5, the twist was improved by the heat treatment. 5 is an evaluation of only the width direction about how much the vertex position shifts after copper foil etching of a flexible metal laminate when a normal heat treatment (150 to 200° C.) or an ignition treatment (300° C.) is performed. . From Fig. 5, it has been found that the twist is improved by changing the heat treatment from the normal heat treatment to the ignition treatment in the same lot and in the same position (in the case of the same heat treatment, the same twisting behavior is exhibited). The abscissa axis represents the twist when subjected to normal heat treatment, and the vertical axis represents the twist when subjected to the heat treatment.

In order to give the obtained polyimide film adhesiveness, you may give the film surface an electrical treatment like corona treatment and a plasma treatment, or a physical treatment like a blast treatment. The pressure of the atmosphere in which the plasma treatment is performed is not particularly limited, but is usually in the range of 13.3 to 1330 kPa, preferably in the range of 13.3 to 133 kPa (100 to 1000 Torr), and in the range of 80.0 to 120 kPa (600 to 900 Torr). more preferably.

The atmosphere for plasma treatment contains at least 20 mol% of an inert gas, and preferably contains 50 mol% or more of inert gas, more preferably 80 mol% or more, and most preferably contains 90 mol% or more. desirable. The inert gas includes He, Ar, Kr, Xe, Ne, RN, N2, and mixtures of two or more thereof. A particularly preferred inert gas is Ar. Furthermore, oxygen, air, carbon monoxide, carbon dioxide, carbon tetrachloride, chloroform, hydrogen, ammonia, tetrafluoromethane (carbon tetrafluoride), trichlorofluoroethane, trifluoromethane, etc. may be mixed with the inert gas. Preferred combinations of mixed gases used as the atmosphere for the plasma treatment of the present invention are argon/oxygen, argon/ammonia, argon/helium/oxygen, argon/carbon dioxide, argon/nitrogen/carbon dioxide, argon/helium/nitrogen, argon/helium. /nitrogen/carbon dioxide, argon/helium, helium/air, argon/helium/monosilane, argon/helium/disilane, etc. are mentioned.

The processing power density at the time of plasma treatment is not particularly limited, but 200 W min/m 2 or more is preferable, 500 W min/m 2 or more is more preferable, and 1000 W min/m 2 or more is most preferable. . 1 second - 10 minutes are preferable for the plasma irradiation time which carries out a plasma process. By setting the plasma irradiation time within this range, the effect of the plasma treatment can be sufficiently exhibited without deterioration of the film. The gas type, gas pressure, and processing density of the plasma processing are not limited to the above conditions, and may be performed in the atmosphere.

The thermoplastic polyimide used for this invention can be obtained by imidating the polyamic acid which is a precursor. It does not specifically limit also about the precursor of a thermoplastic polyimide, All well-known polyamic acids can be used. Moreover, also regarding the manufacture, well-known raw materials, reaction conditions, etc. can be used. Moreover, you may add the filler of an inorganic or organic substance as needed.

The glass transition temperature of a thermoplastic polyimide will not be specifically limited if it is the range of 150 degreeC - 350 degreeC.

The adhesive film of the present invention can be obtained by providing an adhesive layer containing a thermoplastic polyimide on at least one surface of the continuously produced specific polyimide film. As a specific manufacturing method, the method of forming an adhesive layer on the polyimide film used as a base material film, or the method of shaping|molding the adhesive layer into a sheet form, and fitting this suitably to the said polyimide film, etc. are suitable examples. Among these, in the case of adopting the former method, when the polyamic acid, which is a precursor of the thermoplastic polyimide contained in the adhesive layer, is completely imidized, the solubility in an organic solvent may decrease. It may become difficult to provide the said contact bonding layer. Therefore, from the said viewpoint, it is more preferable to prepare the solution containing the polyamic acid which is a precursor of a thermoplastic polyimide, apply|coat this to a base film, and it is more preferable to choose the order of imidation.

The method of casting and apply|coating a polyamic acid solution to a polyimide film is not specifically limited, Existing methods, such as a die coater, a reverse coater, and a braid coater, can be used. When the adhesive layer is continuously formed, the effect of the invention becomes remarkable. That is, it is a method of taking out the polyimide film obtained by making it above and taking out this, continuously unwinding, and apply|coating the solution containing the polyamic acid which is a precursor of a thermoplastic polyimide continuously. Moreover, you may contain other materials like a filler in the said polyamic-acid solution according to a use, for example. Moreover, about the thickness structure of each layer of a heat resistant adhesive film, what is necessary is just to adjust suitably so that it may become the total thickness according to a use.

As a method of imidation, either a heat imidation method or a chemical imidation method can be used. In any imidation procedure, heating is performed in order to efficiently proceed with imidization, but the temperature at that time is within the range of (glass transition temperature of thermoplastic polyimide - 100°C) to (glass transition temperature + 200°C). It is preferable to set, and it is more preferable to set in the range of (glass transition temperature of a thermoplastic polyimide -50 degreeC) - (glass transition temperature +150 degreeC). Since imidation tends to occur at a higher heating temperature, the imidization rate can be increased, which is preferable in terms of productivity. However, when it is too high, the thermoplastic polyimide may cause thermal decomposition. On the other hand, when heating temperature is too low, imidation will hardly advance also in chemical imidation, and the time required for an imidation process will become long.

The imidization time is not particularly limited, as long as TM is sufficient for the imidization and drying to be substantially completed.

0.1 micrometer or more and 30 micrometers or less are preferable and, as for the thickness of a thermoplastic polyimide, 0.5 micrometer or more and 20 micrometers or less are more preferable.

The type of metal used in the present invention is not particularly limited, and examples thereof include copper and copper alloys, stainless steel and alloys thereof, nickel and nickel alloys (including alloy 42), aluminum and aluminum alloys, and the like. Preferably copper and copper alloy. Moreover, what formed the waterproofing layer, a heat-resistant layer (for example, plating treatment of chromium, zinc, etc.), a silane coupling, etc. on the surface of such a metal can be used. Preferably, copper and / or nickel, zinc, iron, chromium, cobalt, molybutene, tungsten, vanadium, beryllium, titanium, tin, manganese, aluminum, phosphorus, silicon, etc., including at least one component and copper As copper alloys, they are favorably used for circuit processing. A particularly preferable metal foil is a copper foil formed by rolling or an electrolytic plating method, and the thickness thereof is preferably 3-150 µm, more preferably 3-35 µm.

As for the said metal foil, even if there is a thing which did not perform any roughening process on both surfaces, the roughening process may be given to one surface or both surfaces.

As a method for thermocompression bonding of a non-thermoplastic polyimide and a metal, the non-thermoplastic polyimide film is coated with a polyamic acid and/or a polyimide solution of a precursor of a thermoplastic polyimide, dried, and then adhered to the metal, or adhered to the metal in advance. After forming the thermoplastic polyimide by the same method, there is a method of overlapping with a non-thermoplastic polyimide film, and a hot press method and/or a continuous lamination method can be used for overlapping. By the hot press method, for example, it can manufacture by superposing|stacking the metal foil cut out to the predetermined size of a press machine, and polyimide, and thermocompression-bonding by hot press.

Although there is no restriction|limiting in particular as a continuous lamination method, For example, there exists a method of sandwiching between rolls and laminating|stacking. A metal roll, a rubber roll, etc. can be used for this roll. Although there is no restriction|limiting of a material, As a metal roll, a steel material or stainless material is used. It is preferable to use a treatment roll with increased surface hardness, such as hard chrome plating or tungsten carbide on the surface. As the rubber roll, it is preferable to use a heat-resistant silicone rubber or a fluorine-based rubber on the surface of the metal roll.

In addition, the upper and lower two metal rolls called belt lamination are made into one set, and two upper and lower seamless stainless belts are placed between the upper and lower rolls arranged in series with one or more sets, and the belt is pressed by the metal rolls. Furthermore, continuous lamination may be carried out by heating with a metal roll or another heat source.

As lamination temperature, the temperature range of 200-400 degreeC is preferable. It is also preferable to heat-anneal after hot press and/or continuous lamination.

The flexible metal laminate obtained by the manufacturing method of the present invention can be used as a flexible wiring board on which various miniaturized and high-density components are mounted by etching the metal foil to form desired patterned wiring as described above. Of course, the use of this invention is not limited to this, It cannot be overemphasized that it can utilize for various uses as long as it is a laminated body containing metal foil.

As long as the effect of this invention appears, this invention includes the aspect which combined the said structure in various ways within the technical scope of this invention.

[Example]

Next, the present invention will be described in more detail with reference to Examples, but the present invention is not limited by these Examples, and many modifications may be made within the technical spirit of the present invention, and the common knowledge in the art is not limited thereto. It is possible by those who have

The measuring method of the various characteristics in this invention is demonstrated below.

(1) AI(45, 135)

The propagation speed V of the ultrasonic pulse in this invention was measured using SST-2500 (Sonic Sheet Tester) made by Nomura Corporation. When the SST-2500 is used, the ultrasonic velocity in 16 directions is automatically measured at intervals of 11.25° with respect to the film plane direction 0 to 180 degrees (0 degrees is parallel to the MD direction). Among the obtained velocities in each direction, the anisotropy index (Anisotoropy Index: AI) expressed by Equation 1 is obtained from the ultrasonic velocities V45 and V135 at 45° and 135° with respect to the MD direction. Using the film obtained by the following Example and the comparative example, it measured at the position shown in FIG. 3, respectively.

(Equation 1): AI(45, 135) = | (V45^2-V135^2)/((V45^2+V135^2)/2)×100|

(2) orientation angle

The orientation angle in this invention was measured using SST-2500 (Sonic Sheet Tester) made by Nomura Corporation. When SST-2500 is used, the ultrasonic velocity in 16 directions is automatically measured at intervals of 11.25° to the film plane direction 0 to 180° (0° is parallel to the MD direction). A pattern diagram as shown in FIG. 3 is drawn by performing radar graphing (using the graph function of Microsoft Excel) the obtained speed in each direction. The line drawn from the center of the circle toward the most bulging part of the pattern diagram is the orientation axis (g), the MD direction is the reference line, and the angle (θ) of the orientation axis is measured from the reference line, and this is obtained as the orientation angle.

(3) Dimensional change rate

Based on JIS C6481 5.16, four holes were formed on the center and diagonal of the adhesive film of a sample, and each distance of each hole was measured from the center part. Next, after attaching the copper foil at 350 ° C./30 minutes, performing the etching step and removing the metal foil from the flexible metal laminate, the same as before the etching step, the respective distances from the center of the four holes were measured. The measured value of the distance of each hole before metal foil removal was made into D1, the measured value of the distance of each hole after metal foil removal was made into D2, and the dimensional change rate before and after etching was calculated|required by the following formula.

Dimensional change rate (%) = ｛(D2-D1)/D1｝×100

Also, the difference in dimensional change rate of 45° to the right and 45° to the left was calculated.

[Polyimide Synthesis Example 1]

Pyromellitic acid dianhydride (molecular weight 218.12) / 3,3', 4,4'-biphenyl tetracarboxylic dianhydride (molecular weight 294.22) / 4,4'-diamino diphenyl ether (molecular weight 200.24) / p- phenyl Rendiamine (molecular weight 108.14) was prepared in a molar ratio of 80/20/75/25 and polymerized with a 20 wt% solution in DMAc (N,N-dimethyl acetamide) to obtain 3500 poise of polyamic acid solution.

[Polyimide Synthesis Example 2]

Pyromellitic acid dianhydride (molecular weight 218.12) / 3,3', 4,4'-biphenyl tetracarboxylic dianhydride (molecular weight 294.22) / 4,4'-diamino diphenyl ether (molecular weight 200.24) / p- phenyl Rendiamine (molecular weight 108.14) was prepared in a molar ratio of 65/35/80/20 and polymerized with a 20 wt% solution in DMAc (N,N-dimethyl acetamide) to obtain 3500 poise of polyamic acid solution.

[Synthesis example A of thermoplastic polyimide]

1,3-bis-(4-aminophenoxy)benzene was added to the solvent dimethyl acetamide and stirred until dissolved. Then, 4,4'- dioxydiphthalic anhydride was added, it stirred, and the polyamic-acid solution was obtained. The solids content in dimethyl acetamide was 15%, and the Tg was 217°C.

[Example 1]

The particle size of all particles measured with a laser dilution/scattering particle size distribution analyzer LA-910 (manufactured by Horiba Corporation) falls within 0.01 μm or more and 1.5 μm or less, and the average particle diameter (volume average particle diameter) is 0.42 μm, and the particle size Regarding the distribution (by volume), a silica N,N-dimethyl acetamide slurry in which particles having a particle diameter of 0.15 to 0.60 μm occupy 89.9% by volume of the total particles was added to the polyamic acid solution obtained in Synthesis Example 1, 0.4 per resin weight % by weight was added, and the mixture was sufficiently stirred and dispersed. Acetic anhydride (molecular weight 102.09) and β-picoline were mixed with this polyamic acid solution in a ratio of 17% by weight and 17% by weight, respectively, and stirred with respect to the polyamic acid solution. The resulting mixture was cast on a stainless steel drum at 75 DEG C rotating from a T-shaped slit die to obtain a gel film having a self-supporting property of 55 wt% of remaining volatile components and a thickness of about 0.05 mm. This gel film was removed from the drum and conveyed through two sets of nip rolls. At that time, longitudinal stretching is performed in two stages by changing the rotation speed of each of the stainless drum (R1), the first nip roll (R2), and the second nip roll (R3), and the respective elongation rates are the values shown in Table 1 as follows. It extended longitudinally at 65 degreeC so that it might become this. After the longitudinal stretching, both ends of the film were gripped and treated with a heating furnace for 250°C × 50 seconds and 400°C × 75 seconds to obtain a polyimide film having a width of 2.2 m and a thickness of 20 μm. Transverse stretching was set so that it might become the maximum at the time of passing through the heating furnace which removes a solvent (250 degreeC x 50 second). The draw ratio at the time of passing through a heating furnace is made into the maximum draw ratio, and the lateral draw ratio falls after passing through a heating furnace. The transverse elongation was obtained by dividing the film width of the maximum lateral elongation by the gel film width after the drum was removed.

The obtained film was annealed at 300°C/30 seconds at a tension of 20 N/m in an oven capable of being continuously heated with hot air and a heater. The transverse elongation is shown in Table 1 as follows. About the obtained polyimide film, AI(45,135) is calculated|required about 5 points|pieces (b, b', c, d, d') shown in FIG. 4, and is shown in following Table 2.

[Method for Producing Thermoplastic Polyimide/Flexible Metal Laminate]

To the film prepared in Example 1, the polyamic acid solution of the thermoplastic polyimide of Synthesis Example A was applied to a thickness of 2 μm after drying, and thermal imidization was carried out at 150° C. for 10 minutes and at 350° C. for 1 minute (adhesive film). production of). Then, copper foil was laminated|stacked on the thermoplastic polyimide side at 350 degreeC/30min, and the flexible metal laminated board was produced. The rate of dimensional change before and after production of the flexible metal laminate was measured. The dimensional change rate is shown in Table 2 below.

[Examples 2-4]

Adhesion as in Example 1 for each polyimide film obtained in the same manner as in Example 1, except that the used polyamic acid solution, longitudinal elongation, lateral elongation, drying temperature, and polyimide film film thickness were respectively set as shown in Table 1. After setting it as a film, a flexible (flexible) metal laminated board is produced, the dimensional change rate is calculated|required, and it is shown in Table 2 below.

[Comparative Examples 1 and 2]

For each polyimide film obtained in the same manner as in Example 1, except that the polyamic acid solution used, the longitudinal elongation, the transverse elongation, the drying temperature, and the thickness of the polyimide film film were respectively set as shown in Table 1, adhesion as in Example 1 After setting it as a film, a flexible metal laminated board was produced, dimensional change rate was calculated|required, and it is shown in following Table 2.

[Comparative Example 3]

The polyimide film obtained in the same manner as in Example 1 was heated at 200° C./30 seconds except that the polyamic acid solution used, the longitudinal elongation, the transverse elongation, the drying temperature, and the thickness of the polyimide film film were respectively set as shown in Table 1. After annealing), a flexible metal laminate was prepared as an adhesive film, and the dimensional change rate was calculated and shown in Table 2 below.

From the said result, it has confirmed that the polyimide film of this invention can suppress a dimensional change, and can also reduce the imbalance of the dimensional change rate by the position of a film. On the other hand, in Comparative Examples 1-3, the dimensional change could not be suppressed as much as the polyimide film of this invention, but the imbalance of the dimensional change rate by the position of a film was also seen.

The polyimide film of this invention is useful for a flexible printed wiring board.

a Film forming width of polyimide film
b The point that enters 200 mm from the end of the film width
b' Point that entered 200 mm from the end of the film making width
c A point within ±200 mm of the center of the film making width
d Any point on the straight line connecting b and b'
d' Any point on the straight line connecting b and b'
e polyimide film
f Center of orientation angle measurement
g orientation axis
h orientation angle (θ)
i Ultrasonic velocity at each angle

Claims (8)

The film forming width is 1 m or more, and the orientation coefficient AI (45, 135) value expressed by Equation 1 in the film orientation angle (θ) is 45° and 135° based on the machine transport direction (MD) of the film. 12 or less over the entire width, the dimensional change rate before and after etching treatment of the flexible metal laminate in the diagonal (45°, 135°) direction in the entire width is -0.05 to 0.05%, and the thickness on at least one side is 0.5 to 20 A polyimide film, characterized in that it has a thermoplastic polyimide layer of μm.
(Equation 1) AI(45, 135)=|(V45^2-V135^2)/((V45^2+V135^2)/2)×100|
The method according to claim 1, wherein the polyimide precursor polyamic acid solution is cast and coated on a support to produce a partially dried and/or cured gel film having self-supporting properties, and the gel film is heated with at least two or more heating furnaces. Manufactured by passing through a tenter heating furnace, drying and/or heat treatment while gripping both ends of the gel film in the width direction, the film forming width is 1 m or more and the thickness is 3 to 50 μm, characterized in that the polyimide film.
The polyimide film according to claim 2, wherein the polyimide film is additionally heat-treated in the machine transport direction (MD) at 10 N/m to 50 N/m.
The method according to claim 1, wherein the polyimide film comprises at least one aromatic diamine component selected from the group consisting of p -phenylene diamine, 4,4'-diamino diphenyl ether and 3,4'-diamino diphenyl ether; A polyimide film prepared by using at least one acid anhydride component selected from the group consisting of pyromellitic dianhydride and 3,3'-4,4'-diphenyl tetracarboxylic dianhydride.
A gel film having self-supporting properties is produced by casting and applying a polyamic acid solution, which is a polyimide precursor, on a support to partially dry and/or harden the gel film, and heat the gel film with a tenter equipped with at least two heating furnaces. Any one of 1 to 4, characterized in that the drying speed is controlled in the tenter heating furnace by passing through a furnace and performing drying and/or heat treatment while gripping both ends of the gel film in the width direction. A method for producing the polyimide film according to the above item.
The method for manufacturing a polyimide film according to claim 5, further comprising a step of additionally heat-treating after the step of drying and/or heat treatment, wherein the temperature of the heat treatment is 250°C or more and 500°C or less.
A flexible metal laminate obtained by laminating a metal foil on the polyimide film according to any one of claims 1 to 4.
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